preprints > subject area > engineering
Reality Capture of Buildings Using 3D Laser Scanners
Avar Almukhtar, Henry Abanda, Zaid O. Saeed, Joseph H.M. Tah
Subject: Engineering, Construction Keywords: 3D Laser Scanners 1; Point-cloud Data 2; Reality Capture; BIM; Refurbishment
The urgent need to improve performance in the construction industry has led to the adoption of many innovative technologies. 3D laser scanners are amongst the leading technologies being used to capture and process assets or construction project data for use in various applications. Due to its nascent nature, many questions are still unanswered about 3D laser scanning, which in turn contribute to the slow adaptation of the technology. Some of these include the role of 3D laser scanners in capturing and processing raw construction project data. How accurate is the 3D laser scanner or point cloud data? How does laser scanning fit with other wider emerging technologies such as Building Information Modelling (BIM)? This study adopts a proof-of-concept approach, which in addition to answering the afore-mentioned questions, illustrates the application of the technology in practice. The study finds that the quality of the data, commonly referred to as point cloud data is still a major issue as it depends on the distance between the target object and 3D laser scanner's station. Additionally, the quality of the data is still very dependent on data file sizes and the computational power of the processing machine. Lastly, the connection between laser scanning and BIM approaches is still weak as what can be done with a point cloud data model in a BIM environment is still very limited. The aforementioned findings reinforce existing views on the use of 3D laser scanners in capturing and processing construction project data.
From Shipbreaking Literature to Sustainability Framework for Developing Country Recycling: a Review (Part 2)
Sm Rahman
Subject: Engineering, Automotive Engineering Keywords: shipbreaking; triple bottom line sustainability; strange alliance; organizational learning
Shipbreaking research has not been in the forefront until the last decade in which environmental and occupational hazards have been highlighted while economic sustainability and contextual conditions were not equally considered. The adoption of a triple bottom line approach across core business issues (environmental impacts, workplace safety ) as well as peripheral stakeholders expectation (environmental sustainability focus) has been retarded due to the less attention on the latter. Based on the findings of the 128 review papers, the study suggests that organizational learning and economic sustainability needs to prioritize through the formation of strange alliance among the stakeholders. The study argues that the dialogue and discussion on the peripheral stakeholders (NGOs, yard managers, national and international policy organizations) would lead to a more sustainable shipbreaking industry in the south Asian regions.
Preliminary Modeling of Rockfall Runout: Definition of the Input Parameters for the Plugin QPROTO
Marta Castelli, Giulia Torsello, Gianmarco Vallero
Subject: Engineering, Automotive Engineering Keywords: Rockfall hazard; Rockfall runout; QGIS; QPROTO; Cone Method
The identification of the most rockfall-prone areas is the first step of the risk assessment procedure. In the case of land and urban planning, hazard and risk analyses involve large portions of territory and thus preliminary methods are preferred to define specific zones where more detailed computations are needed. To reach this goal, we developed the QGIS-based plugin QPROTO, able to quantitatively compute rockfall time-independent hazard over a three-dimensional topography on the basis of the Cone Method. This is obtained by combining kinetic energy, passing frequency and detachment propensity of each rockfall source. QPROTO requires the definition of few angles (i.e., the energy angle ϕ_p and the lateral angle α) that should take into account all the phenomena occurring during the complex block movement along the slope. The outputs of the plugin are a series of raster maps reporting the invasion zones and the quantification of both the susceptibility and the hazard. In this paper, we propose a method to relate these angles to some characteristics of the block (volume and shape) and the slope (inclination, forest density), to provide QPROTO users with a tool for estimating the input parameters. The results are validated on a series of case studies belonging to the North Western Italian Alps.
Experiences from City Scale Simulation of Thermal Grids
Johan Simonsson, Gerald Schweiger, Wolfgang Birk, Khalid Atta
Subject: Engineering, Automotive Engineering Keywords: Digital twin; Simulation; District heating; District cooling; 4GDH; DHC
Dynamic simulation of district heating and cooling networks has an increased importance in the transition towards renewable energy sources and lower temperature district heating grids, as both temporal and spatial behavior need to be considered. Even though a lot and research and development has been performed in the field, there are several pitfalls and challenges towards dynamic district heating and cooling simulation for everyday use. This article presents the experiences from working with district heating and cooling projects, along with relevant research, corresponding research gaps and proposed research directions.
Effect of Fuel Composition and O2 Concentration on Autoignition Characteristics of n-Heptane/Methane Blended Fuels
Myeongsu Yoon, Gyungmin Choi
Subject: Engineering, Automotive Engineering Keywords: ignition delay time; n-heptane; methane; homogeneous change compression ignition; compression ratio; exhaust gas recirculation
This study numerically analyzed the effect of composition and temperature and oxygen concentration changes on the selfignition characteristics of n-heptane/methane blended fuels in order to cope with development of alternative fuels and international environmental regulations. CHEMKIN-PRO is used as the analysis program and the LLNL model is used as the reaction model. The numerical results revealed that on autoignition and ignition delay time were sensitive to changes in fuel composition and oxygen concentration. As the methane ratio increases, OH radicals causing ignition are delayed in generation and the concentration is lowered, thus longer the ignition timing. The oxygen concentration in the mixed fuels are changed to simulate the exhaust gas recirculation and a numerical analysis in then performed. As the oxygen concentration decreases, the ignition delay time longer because the nitrogen gas acts as a thermal load in the combustion chamber.
Device Classification-based Context Management for Ubiquitous Computing using Machine Learning
Nalini Mhetre, Arvind Deshpande, Parikshit Mahalle
Subject: Engineering, Automotive Engineering Keywords: context management; device classification; IoT device management; k-Means clustering; ubiquitous computing; unsupervised machine learning
Ubiquitous computing comprises scenarios where networks, devices within the network, and software components change frequently. Market demand and cost-effectiveness are forcing device manufacturers to introduce new-age devices. Also, the Internet of Things (IoT) is transitioning rapidly from the IoT to the Internet of Everything (IoE). Due to this enormous scale, effective management of these devices becomes vital to support trustworthy and high-quality applications. One of the key challenges of IoT device management is automatic device classification with the logically semantic type and using that as a parameter for device context management. This would enable smart security solutions. In this paper, a device classification approach is proposed for the context management of ubiquitous devices based on unsupervised machine learning. To classify unknown devices and to label them logically, a proactive device classification model is framed using a k-Means clustering algorithm. To group devices, it uses the information of network parameters such as Received Signal Strength Indicator (rssi), packet_size, number_of_nodes in the network, throughput, etc. Experimental analysis suggests that the well-formedness of clusters can be used to derive cluster labels as a logically semantic device type which would be a context for resource management and authorization of resources. This paper fulfills an identified need of proactive device classification for device management.
Scaling of Measure Fluctuations on a Flapping Flag Device in the Open Channel Around a Cylinder At $Re=10^4$ : Taylor's Law Approach
Samuele De Bartolo, Massimo De Vittorio, Antonio Francone, Francesco Guido, Elisa LEONE, Vincenzo Mariano Mastronardi, Andrea Notaro, Giuseppe Roberto Tomasicchio
Subject: Engineering, Automotive Engineering Keywords: sensors technologies; sensor systems for water flow; hydrodynamics monitoring of rivers; hydraulics; MEMS; Fluid-structure interactions
Experimental evidence showed how various complex systems, characterized by a fluctuation scaling, satisfy the well-known Taylor's law. The present work aims to apply for the first time Taylor's law, given its general treatment, for a flow field at $Re$ around $10^4$, since activity of each fluid particle is highly fluctuating, especially in the context of vortex shedding. In addition, the further element of innovation is the use of an innovative thin-films based device consisting of an elastic piezoelectric flapping flag that is proposed as a measuring instrument of the flow field. The oscillations of the flapping flag, due to the vortexes release downstream to an obstacle of cylindrical shape, generate an alternating piezoelectric voltage whose time history is similar to the chaotic components of the fully developed turbulent speed. Preliminary experimental results about the use of thin-films based device in a flume channel are reported together with a second order analysis on the voltage difference and a scaling law of the exponent scale.
Reanalysis of the Sydney Harbor RiverCat Ferry
Lawrence Doctors
Subject: Engineering, Marine Engineering Keywords: Ferry design; wave generation; ship hydrodynamics
In this paper, we revisit the hydrodynamics supporting the design and development of the RiverCat class of catamaran ferries operating in Sydney Harbor since 1991. More advanced software is used here. This software accounts for the hydrodynamics of the transom demisterns which experience partial or full ventilation, depending on the vessel speed. This ventilation gives rise to the hydrostatic drag, which adds to the total drag of the vessel. The presence of the transom also creates a hollow in the water. This hollow causes an effective hydrodynamic lengthening of the vessel, which leads to a reduction in the wave resistance. Hence a detailed analysis is required in order to optimize the size of the transom. It is demonstrated that the drag of the vessel and the wave generation can be predicted with good accuracy. Finally, the software is also used to optimize the vessel further by means of affine transformations of the hull geometry.
High-Speed and Unified ECC Processor for Generic Weierstrass Curves over GF(p) on FPGA
Asep Muhamad Awaludin, Harashta Tatimma Larasati, Howon Kim
Subject: Engineering, Electrical & Electronic Engineering Keywords: elliptic curves cryptography (ECC); high speed implementation; unified; Montgomery multiplication; field-programmable gate array (FPGA)
In this paper, we present a high-speed, unified elliptic curve cryptography (ECC) processor for arbitrary Weierstrass curves over GF(p), which to the best of our knowledge, outperforms other similar works in terms of execution time. Our approach employs the combination of the schoolbook long and Karatsuba multiplication algorithm for the elliptic curve point multiplication (ECPM) to achieve better parallelization while retaining low complexity. In the hardware implementation, the substantial gain in speed is also contributed by our n-bit pipelined Montgomery Modular Multiplier (pMMM), which is constructed from our n-bit pipelined multiplier-accumulators that utilizes DSP primitives as digit multipliers. Additionally, we also introduce our unified, pipelined modular adder/subtractor (pMAS) for the underlying field arithmetic, and leverage a more efficient yet compact scheduling of the Montgomery ladder algorithm. The implementation on the 7-series FPGA: Virtex-7, Kintex-7, and XC7Z020, yields 0.139, 0.138, and 0.206 ms of execution time, respectively. Furthermore, since our pMMM module is generic for any curve in Weierstrass form, we support multi-curve parameters, resulting in a unified ECC architecture. Lastly, our method also works in constant time, making it suitable for applications requiring high speed and SCA-resistant characteristics.
Extracting the Resistive Current Component from a Surge Arrester`s Leakage Current without Voltage Reference
Vid Vončina, Jože Pihler, Miro Milanovič
Subject: Engineering, Electrical & Electronic Engineering Keywords: IoT; leakage current; Metal Oxide Surge Arrester; remote monitoring; resistive component of leakage current.
This article presents the development of the theoretical background and the design of an electronic device for monitoring the condition of a gapless Metal Oxide Surge Arrester (MOSA). The device is intended to be used online. Due to the inaccessibility and possible remote location of most surge arresters, it is equipped with a communication system, allowing the device to convey the measurement of the surge arrester characteristics under any conditions. By gathering measurements of the surge arrester's resistive component of leakage current, it is possible to determine the condition of the MOSA. After interpreting the results, these can be sent via a data transfer unit to a server, which, in turn, sends it onward to the authorised personnel through the surge arrester control centre.
Non-Symmetrical Collapse of an Empty Cylindrical Cavity Studied with Smoothed Particle Hydrodynamics
Andrea Albano, Alessio Alexiadis
Subject: Engineering, Automotive Engineering Keywords: Particle method; Smoothed particle hydrodynamics; Modeling; Simulations; Shock wave
The non-symmetrical collapse of an empty cylindrical cavity is modelled using Smoothed Particle Hydrodynamics. The presence of a nearby surface produces an anisotropic pressure field generating a high velocity jet that hits the surface. The collapse follows a different dynamic based to the initial distance between the centre of the cavity and the surface. When the distance is greater than the cavity radius (detached cavity) the surface is hit by travelling shock waves. When the distance is less than the cavity radius (attached cavity) the surface is directly hit by the jet and later by other shock waves generated in the last stages of the of the collapse. The results show that the surface is hit by a stronger shock when distance between the centre of the cavity and the surface is zero while showing more complex double peaks behaviour for other distances.
Design and Implementation Procedure of a High-Gain Three-Input Step-Up 1kW Converter
Edgardo Netzahuatl, Leobardo Hernandez-Gonzalez, Domingo Cortes, Jazmin Ramirez-Hernandez
Subject: Engineering, Electrical & Electronic Engineering Keywords: Multi-output converter; DC-DC converter; Boost converter; Renewable energy
The use of different sources to energize a load is convenient in many applications, particularly those where two or more renewable energy sources are employed as: energy harvesting, hybrid vehicles, and off-grid systems. In these cases, a multi-input converter able to admit sources with different characteristics and, if necessary, select the output power of each source. Several topologies of multi-input converters have been proposed to this aim, however, most of them are based on multi-stage designs, which decreases efficiency and increases control complexity, particularly when more than two sources are used. In this work, a three-input step-up converter easy to control in open loop condition is analyzed. A designed procedure is described, and experimental results are presented for a 1 kW power converter. The implemented converter results in a higher voltage gain, less storage element keeping high efficiency compared to similar topologies. Using the procedure here proposed, this converter that was initially proposed for photovoltaic applications is enabled to be used in medium and high-power applications, for example when renewable energy sources are used.
Synthesizing Multi-Layer Perceptron Network with Ant Lion, Biogeography-Based, Dragonfly Algorithm, Evolutionary Strategy, Invasive Weed, and League Champion Optimization Hybrid Algorithms in Predicting Heating Load in Residential Buildings
Hossein Moayedi, Amir Mosavi
Subject: Engineering, Automotive Engineering Keywords: energy-efficient building; heating load; neural computing; biogeography-based optimization
: The significance of heating load (HL) accurate approximation is the primary motivation of this research to distinguish the most efficient predictive model among several neural-metaheuristic models. The proposed models are through synthesizing multi-layer perceptron network (MLP) with ant lion optimization (ALO), biogeography-based optimization (BBO), dragonfly algorithm (DA), evolutionary strategy (ES), invasive weed optimization (IWO), and league champion optimization (LCA) hybrid algorithms. Each ensemble is optimized in terms of the operating population. Accordingly, the ALO-MLP, BBO-MLP, DA-MLP, ES-MLP, IWO-MLP, and LCA-MLP presented their best performance for population sizes of 350, 400, 200, 500, 50, and 300, respectively. The comparison was carried out by implementing a ranking system. Based on the obtained overall scores (OSs), the BBO (OS = 36) featured as the most capable optimization technique, followed by ALO (OS = 27) and ES (OS = 20). Due to the efficient performance of these algorithms, the corresponding MLPs can be promising substitutes for traditional methods used for HL analysis.
Estimate e-Golf Battery State Using Diagnostic Data and a Digital Twin
Lukas Merkle, Michael Pöthig, Florian Schmid
Subject: Engineering, Automotive Engineering Keywords: UDS-Diagnosis; Battery Twin; Data Logger; SOH
Li-ion battery packs are the heart of modern electric vehicles. Due to their perishable nature, it is crucial to supervise them closely. In addition to on-board supervision over safety and range, insights into the battery's degradation are also becoming increasingly important, not only for the vehicle manufacturers but also for vehicle users. The concept of digital twins has already emerged on the field of automotive technology, and can also help to digitalize the vehicle's battery. In this work, we set up a data pipeline and digital battery twin to track the battery state, including state of charge (SOC), state of health (Capacity) (SOHc ) and state of health (Resistance) (SOHr ). To achieve this goal, we reverse-engineer the diagnostics interface of a 2014 e-Golf to query for Unified Diagnostic Services (UDS) messages containing both battery pack and cell-individual data. An on-board diagnosis (OBD) logger records the data with edge-processing capability. Pushing this data into the cloud twin system using IoT-technology, we can fit battery models to the data and infer cell individual internal resistance from them. We find that the resistances of the cells differ by a magnitude of two. Furthermore, we propose an architecture for the battery twin in which the twin fleet shares resources like models by encapsulating them in Docker containers run on a cloud stack. By using web technology, we present the analyzed results on a web interface.
An Experimental Research on Microseismic Monitoring Technology in Detecting the Contact Time of Badminton Amateurs' Lunge
Yang Yang, Yingchun Cui, Wenfa Yan
Subject: Engineering, Automotive Engineering Keywords: badminton; amateurs; lunge evaluation; contact time; microseismic; feasibility
The fast and flexible characteristics of badminton determine the necessity of its lunge, and fast lunge will have an important impact on the results of the game in actual combat. In lunge evaluation, the contact time to the ground is a key indicator. This article selects two middle-aged male badminton amateurs with similar body shape and age, but different skill levels as the research objects to carry out comparative experiments. The microseismic equipment is used to record the floor vibration which is caused by the running of badminton amateurs in sports. The microseismic signals of lunge are processed and analyzed by MATLAB software. And we evaluate the pro and cons of various time to touch the ground from amateurs with different skill levels. The research found that 1. Microseismic technology can detect the contact time to the ground. 2. High-level badminton amateurs have obvious advantages in the footwork contact time. Microseismic technology has a certain feasibility as a tool for evaluating the footwork contact time of badminton.
Analysis of Mechanical Behaviors of Waterbomb Thin-Shell Structures Under Quasi-Static Load
Lijuan Zhao, Zuen Shang, Tianyi Zhang, Zhan Liu, Liguo Han, and Chongwang Wang
Subject: Engineering, Automotive Engineering Keywords: Waterbomb structure; Origami pattern; Quasi-static load; Critical axial buckling load-to-weight ratio; Radial stiffness-to-weight ratio
Waterbomb structures are origami-inspired deformable structural components used in new types of robots. They have a unique radially deployable ability that enables robots to better adapt to their environment. In this paper, we propose a series of new waterbomb structures with square, rectangle, and parallelogram base units. Through quasi-static axial and radial compression experiments and numerical simulations, we prove that the parallelogram waterbomb structure has a twist displacement mode along the axial direction. Compared with the square waterbomb structure, the proposed optimal design of the parallelogram waterbomb structure reduces the critical axial buckling load-to-weight ratio by 55.4% and increases the radial stiffness-to-weight ratio by 67.6%. The significant increase in the radial stiffness-to-weight ratio of the waterbomb structure and decrease in the critical axial buckling load-to-weight ratio make the proposed origami pattern attractive for practical robotics applications.
Effect of Pr6O11 on the Microstructures and Mechanical Properties of High-Strength Steel Weld Metal
Tianli Zhang, Hang Yu, Shiliang Li, Weiguang Wang, Wen Wu, Haoxin Chen, Yu Chen
Subject: Engineering, Mechanical Engineering Keywords: high-strength steel; weld metal; Pr6O11; microstructure; mechanical properties
The effect of rare earth Pr6O11 on the microstructure and mechanical properties of high-strength steel weld metal was investigated by optical microscopy, scanning electron microscopy and mechanical testing. Three different contents of Pr6O11 were added to the flux-cored wires. The results showed that the addition of 1% Pr6O11 can promote the refinement and spheroidization of inclusions, refine the grains, form acicular ferrites, and significantly improve the toughness of weld metal. The addition of Pr6O11 promoted the formation of rare earth composite inclusions and acicular ferrites in the weld metal, refined the lath microstructure, inhibited the formation of martensite and bainite. The crack formation mode changed from the boundary cracking of the bainite clusters caused by the surface shear stress to the surface shear stress-induced decohesion of inclusion. However, excessive addition of Pr6O11 will reduce the number of inclusion nucleation and deteriorate the mechanical properties. The wire No.2 with 1% Pr6O11 had the good comprehensive mechanical properties, and the corresponding values were 835MPa of tensile strength and 72 J of impact toughness. These findings suggest that the control of Pr6O11 can be an effective way to improve the impact toughness of weld metal.
Tribology of Polymer Blends PBT + PTFE
Constantin Georgescu, Lorena Deleanu, Larisa Chiper (Titire), Alina Cantaragiu Ceoromila
Subject: Engineering, Mechanical Engineering Keywords: Polybutylene terephthalate (PBT); polytetrafluoroethylene (PTFE); blend PBT + PTFE; block-on-ring test; friction coefficient; wear rate
This paper presents results on tribological characteristics for polymer blends made of polybutylene terephthalate (PBT) and polytetrafluoroethylene (PTFE). This blend is relatively new in research as PBT has restricted processability because of its processing temperature near the degradation one. Tests were done block-on-ring tribotester, in dry regime, the variables being the PTFE concentration (0%, 5%, 10% and 15%wt) and the sliding regime parameters (load: 1 N, 2.5 N and 5 N, the sliding speed: 0.25 m/s, 0.5 m/s and 0.75 m/s, and the sliding distance: 2500 m, 5000 m and 7500 m). Results are encouraging as PBT as neat polymer has very good tribological characteristics in terms of friction coefficient and wear rate. SEM investigation reveals a quite uniform dispersion of PTFE drops in the PBT matrix.
Chassis Influence on the Exposure Assessment of a Compact EV during WPT Recharging Operations
Valerio De Santis, Luca Giaccone, Fabio Freschi
Subject: Engineering, Electrical & Electronic Engineering Keywords: Computational electromagnetics; Electric Vehicle; EMF safety; low frequency dosimetry; Wireless Power Transfer
In this study, the external magnetic field emitted by a wireless power transfer (WPT) system and the internal electric field induced into human body models during recharging operations of a compact electric vehicle (EV) are evaluated. To this aim an ad-hoc formulation for the source modeling is coupled with a commercial software that performs numerical dosimetry. Specifically, two realistic anatomical models both in a driving position and in a standing posture are considered, and the chassis of the EV is modeled either as a currently employed aluminum alloys and as a futuristic carbon fiber composite panel. Aligned and misaligned coil configurations of the WPT system are considered as well. The analysis of the obtained results shows that the ICNIRP reference levels are exceeded in the driving position, especially for the carbon fiber chassis, whereas no exceedance is observed in terms of basic restrictions, at least for the considered scenarios.
Stochastic Computing Implementation of Chaotic Systems
Oscar Camps, Stavros G. Stavrinides, Rodrigo Picos
Subject: Engineering, Electrical & Electronic Engineering Keywords: Stochastic Logic; Chaotic Systems; Approximate Computing; Shimizu-Morioka System; Chaotic Circuits; FPGA Implementation
An exploding demand for processing capabilities related to the emergence of the IoT, AI and big data, has led to the quest for increasingly efficient ways to expeditiously process the rapidly increasing amount of data. These ways include different approaches like improved devices capable of going further in the more Moore path, but also new devices and architectures capable of going beyond Moore and getting more than Moore. Among the solutions being proposed, Stochastic Computing has positioned itself as a very reasonable alternative for low-power, low-area, low-speed, and adjustable precision calculations; four key-points beneficial to edge computing. On the other hand, chaotic circuits and systems appear to be an attractive solution for (low-power, green) secure data transmission in the frame of edge computing and IoT in general. Classical implementations of this class of circuits require intensive and precise calculations. This paper discusses the use of the SC framework for the implementation of nonlinear systems, showing that it can provide results comparable to those of classical integration, with much simpler hardware, paving the way for relevant applications.
Intensification of Biokinetics of Enzymes using Ultrasound Assisted Methods: A Critical Review
Altab Khan, Mohd Riyaz Beg, Pramod Waghmare
Subject: Engineering, Automotive Engineering Keywords: ultrasound; ultrasonic reactors; enzyme kinetic; enzymatic reaction; sonochemical reaction
The use of low-intensity ultrasound has gotten surprising consideration over the last decade as a method for enhancing the catalytic activity of the enzyme. Ultrasounds have the potential to significantly influence the activity of the enzymatic processes, provided that the energy input is not too high to inactivate the enzyme. By providing the variation in parameters, various physical and chemical effects can be attained that can enhance the enzymatic reaction. Ultrasonic reactors are known for their application in bioprocesses. However, the potential of their applications is still limited broadly due to the lack of proper information about their operational and performance parameters. In this review, the detailed information about ultrasonic reactors is provided by defining the different types of reactors, number and position of ultrasonic transducers. Also, it includes the mechanism of intensification and influence of ultrasonic parameters (intensity, duty cycle and frequency) and enzymatic factors (enzyme concentration, temperature and pH) on the catalytic activity of enzyme during ultrasound treatment.
Valuation of Wind Energy Turbines Using Volatility of Wind and Price
Doron Greenberg, Michael Byalsky, Asher Yahalom
Subject: Engineering, Automotive Engineering Keywords: Wind energy; Renewable resources; Black-Scholes model
The limitedness of the nonrenewable local energy resources in Israel, even in background of the later gas fields' findings, continues to force the state to devote various efforts for the 'green' energy development. These efforts include installations both in the solar and in the wind energy, with a purpose to improve the diversity of energy sources. While the standard discounted cash flow (DCF) method using the net present value (NPV) criterion is extensively adopted to evaluate investments, the standard DCF method is inappropriate for the rapidly changing investment climate and for the managerial flexibility in investment decisions. In recent years, the real options analysis (ROA) technique is widely applied in many studies for valuation of renewable energy investment projects. Hence, we apply in this study the real options analysis approach for the valuation of wind energy turbines and apply it to the analysis of wind energy economic potential in Israel.
Development of a Resolver-to-Digital Converter Based on Second-Order Difference Generalized Predictive Control
Thyago Estrabis, Gabriel Gentil, Raymundo Cordero
Subject: Engineering, Automotive Engineering Keywords: angle tracking observer; generalized predictive control; resolver; resolver-to-digital converter; tracking
High-performance motor drives that operate in harsh conditions require an accurate and robust angular position measurement to correctly estimate the speed and reduce the torque ripple produced by angular estimation error. For that reason, a resolver is used in motor drives as a position sensor due to its robustness. A resolver-to-digital converter (RDC) is an observer used to get the angular position from the resolver signals. Most RDCs are based on angle tracking observers (ATOs). On the other hand, generalized predictive control (GPC) has become a powerful tool in developing controllers and observers for industrial applications. However, no GPC-based RDC with zero steady-state error during constant speed operation was proposed. This paper proposes an RDC based on a second-order difference GPC (SOD-GPC). In SOD-GPC, the second-order difference operator is applied to design a GPC model with two embedded integrators. Thus, the SOD-GPC is used to design a type-II ATO whose steady-state angle estimation error tends to zero during constant speed operation. Simulation and experimental results prove that the proposed RDC system has better performance than other literature approaches.
Collect and Treat Urban Wastewater to Fight the Pandemic Disease of COVID-19 Effectively
Abdol Aziz Shahraki
Subject: Engineering, Automotive Engineering Keywords: coronavirus; wastewater treatment techniques; mathematical model; statistical procedures; bacterial reactors, anaerobic ponds
This paper presents multidisciplinary and innovative research concerning fighting against coronavirus through wastewater collection and treatment. Studies suggest that coronavirus exists in the wastewaters. Untreated wastewater is proved to spread the virus. Coronavirus is attacking people globally and shrinking the economy. This paper highlights the idea that the coronavirus shall be defeated with the help of wastewater collection and treatment as well. The question addressed by this paper is will communities defeat the coronavirus without well-collected and treated wastewaters? This research aims to display the role of wastewaters in the spread of coronavirus in cities and to require their collection. The methods to achieve the goals are theoretical surveys, case study strategy, mathematical modeling, statistical procedures, forecasting of future, and dialectical discussions. The findings of this research demonstrate the need for carefully collected and treated wastewaters to overcome the coronavirus. This paper gives suitable techniques to collect and treat wastewater such as wastewater stabilization ponds, bacterial reactors, and anaerobic ponds. The innovative idea of this paper, its suggested indicators to select a certain wastewater treatment technique in every city, and its outcome will assist the global community to fight the coronavirus more effectively.
Evaluation of Coating Thickness Using Lift-Off Insensitivity of Eddy Current Sensor
Xiaobai Meng, Mingyang Lu, Wuliang Yin, Abdeldjalil Bennecer, Katherine Kirk
Subject: Engineering, Automotive Engineering Keywords: Multi-frequency eddy current; lift-off inversion; coating thickness; non-destructive testing; multi-layer conductor.
Defect detection in ferromagnetic substrates is often hampered by non-magnetic coating thickness variation when using conventional eddy current testing technique. The lift-off distance between the sample and the sensor is one of the main obstacles for the thickness measurement of non-magnetic coatings on ferromagnetic substrates when using the eddy current testing technique. Based on the eddy current thin-skin effect and the lift-off insensitive inductance (LII), a simplified iterative algorithm is proposed for reducing the lift-off variation effect using a multi-frequency sensor. Compared to the previous techniques on compensating the lift-off error (e.g., the lift-off point of intersection) while retrieving the thickness, the simplified inductance algorithms avoid the computation burden of integration, which are used as embedded algorithms for the online retrieval of lift-offs via each frequency channel. The LII is determined by the dimension and geometry of the sensor, thus eliminating the need for empirical calibration. The method is validated by means of experimental measurements of the inductance of coatings with different materials and thicknesses on ferrous substrates (dual-phase alloy). The error of the calculated coating thickness has been controlled to within 3 % for an extended lift-off range of up to 10 mm.
Nanotechnology for Biosensors: A Review
Aishwaryadev Banerjee, Swagata Maity, Carlos H. Mastrangelo
Subject: Engineering, Automotive Engineering Keywords: Biosensors; review; nanotechnology; cancer detection; IoT; low power sensors
Biosensors are essential tools which have been traditionally used to monitor environmental pollution, detect the presence of toxic elements and biohazardous bacteria or virus in organic matter and biomolecules for clinical diagnostics. In the last couple of decades, the scientific community has witnessed their widespread application in the fields of military, health care, industrial process control, environmental monitoring, food-quality control, and microbiology. Biosensor technology has greatly evolved from the in vitro studies based on the biosensing ability of organic beings to the highly sophisticated world of nanofabrication enabled miniaturized biosensors. The incorporation of nanotechnology in the vast field of biosensing has led to the development of novel sensors and sensing mechanisms, as well as an increase in the sensitivity and performance of the existing biosensors. Additionally, the nanoscale dimension further assists the development of sensors for rapid and simple detection in vivo as well as the ability to probe single-biomolecules and obtain critical information for their detection and analysis. However, the major drawbacks of this include, but are not limited to potential toxicities associated with the unavoidable release of nanoparticles into the environment, miniaturization induced unreliability, lack of automation, and difficulty of integrating the nanostructured-based biosensors as well as unreliable transduction signals from these devices. Although the field of biosensors is vast, we intend to explore various nanotechnology enabled biosensors as part of this review article and provide a brief description of their fundamental working principles and potential applications.
Inverse Analysis Method on the Performance Evaluation of Geosynthetic Reinforcements in Highway Pavement on Expansive Soils
Debojit Sarker, Jay Wang
Subject: Engineering, Automotive Engineering Keywords: Expansive soils; Pavement; Geosynthetics; Inverse analysis; Virtual load
Sometimes a pavement deflects only because of seasonal volume change of expansive soils in the pavement subgrade. Engineering practitioners expect an implementable and straightforward analysis method for a geosynthetic-reinforced pavement subjected to the swelling/shrinkage issue of expansive clayey subgrade, in an effort to find the bending moment, shear force and tension force distributions through the reinforced pavement, which are induced from the volumetric changes of subgrade soils. The virtual load method (VLM) was proposed in the past following the Timoshenko beam theory to analyze geosynthetic-reinforced pavement on expansive soils. In the VLM, the unknown virtual distributed load was obtained in the way by applying the inverse theory for the identification of material parameters of the pavement-foundation system. It was seen that the selection of the number of material parameters to obtain virtual load significantly affects the accuracy of the structural properties of the pavement and tensile properties of the geosynthetics if the linear least square method is used. In this paper, a unique numerical scheme was proposed in the hopes of solving the issue. After a forward problem was solved numerically, the Timoshenko beam deflection was taken as a start-up for the inverse problem to back analyze the load applied to the pavement. Solutions from forward/backward examples have explicitly shown the accuracy achieved related to the bending moment in the pavement and tension in the geosynthetic reinforcements. The proposed methodology can be applied for an in-depth understanding of the geosynthetic function for the mitigation of longitudinal cracks on pavements caused by heave/shrinkage of expansive soils.
Suggesting a Stochastic Fractal Search Paradigm in Combination With Artificial Neural Network for Early Prediction of Cooling Load in Residential Buildings
Subject: Engineering, Automotive Engineering Keywords: Energy-efficiency; HVAC system; Neural network; Cooling load; Metaheuristic search.
Early prediction of thermal loads plays an essential role in analyzing energy-efficient buildings' energy performance. On the other hand, stochastic algorithms have recently shown high proficiency in dealing with this issue. These are the reasons that this work is dedicated to evaluating an innovative hybrid method for predicting the cooling load (CL) in buildings with residential usage. The proposed model is a combination of artificial neural networks and stochastic fractal search (SFS-ANN). Two benchmark algorithms, namely the grasshopper optimization algorithm (GOA) and firefly algorithm (FA), are also considered to be compared with the SFS. The non-linear effect of eight independent factors on the CL is analyzed using each model's optimal structure. Evaluation of the results outlined that all three metaheuristic algorithms (with more than 90 % correlation) can adequately optimize the ANN. In this regard, this tool's prediction error declined by nearly 23, 18, and 36 % by applying the GOA, FA, and SFS techniques. Also, all used accuracy criteria indicated the superiority of the SFS over the benchmark schemes. Therefore, it is inferred that utilizing the SFS along with ANN provides a reliable hybrid model for the early prediction of CL.
VEGF Detection via Simplified FLISA Using a 3D Microfluidic Disk Platform
Dong Hee Kang, Na Kyong Kim, Sang-Woo Park, Hyun Wook Kang
Subject: Engineering, Automotive Engineering Keywords: Lab-on-a-disk; 3D microstructure; FLISA; VEGF
Fluorescence-linked immunosorbent assay (FLISA) is a commonly used, quantitative technique for detecting biochemical based on antigen–antibody binding reactions using a well-plate platform. With the developments in the manufacturing technology of microfluidic systems, FLISA can be implemented onto microfluidic disk platforms, which allows the detection of trace biochemical with high resolutions. Apart from requiring a lower proportion of reagent (1/10), this method also reduces the time required for the entire process to less than an hour. The incubation process involves antigen–antibody binding reactions as well as the binding of fluorogenic substrates to target proteins. The protocol for FLISA on a microfluidic platform necessitates the appropriate execution of liquid reagent movements during each step in order to ensure sufficient binding reactions. Herein, we propose a novel microfluidic disk comprising a 3D incubation chamber. Vascular endothelial growth factor as concentration with ng mL-1 is detected sequentially using a benchtop process employing this 3D microfluidic disk. The 3D microfluidic disk is implemented without requiring manual intervention or additional procedures for liquid control. During the incubation process, microbead movement is controlled through centrifugal force, generated due to disk rotation, and gravitational force via bead sedimentation on the sloped floor of the chamber.
Mobility as a Service: A Review on Recent Development and Future Envision
Haoning Xi
Subject: Engineering, Automotive Engineering Keywords: Mobility as a Service (MaaS); future envision
Mobility as a Service (MaaS) is an innovative transport concept, anticipated to provide travelers with different kinds of travel services, more sustainable than a private car, in a simpler, packaged way. It combines different transport modes to offer a tailored mobility package, like a monthly mobile phone contract. The rapid development of intelligent transportation system and the shared economy has speeded up the development of MaaS in these years. In this paper, we aim at classifying the existing research on MaaS and the characteristics of MaaS into different categories, in order to answer the following questions after reviewing the existing literature: What is MaaS? Who are the main actors in MaaS? How can MaaS be implemented? Why should it be implemented? Where will MaaS end up in this wave of disruption? When we talk about MaaS, what are we focusing on? What is the future leading frequency of MaaS? Finally, based on the existing literature, we envision the leading future of MaaS.
Double-Target Based Network in Predicting Energy Consumption in Residential Buildings
Subject: Engineering, Automotive Engineering Keywords: Energy efficiency; Heating loads; heating ventilation and air conditioning; metaheuristic; optimization algorithms.
Reliable prediction of sustainable energy consumption is the key to designing environmental friend buildings. In this study, two novel hybrid intelligent methods, namely grasshopper optimization algorithm (GOA), wind-driven optimization (WDO), and biogeography-based optimization (BBO) is employed to optimize the multitarget prediction of heating loads (HLs) and cooling loads (CLs) in heating ventilation and air conditioning (HVAC) systems. Concerning the optimization of applied hybrid algorithms, a series of swarm-based iteration is performed, and the best structure for the abovementioned methods are proposed. Besides, through sensitivity analyzing the relationship between the HLs and CLs and influential factors are highlighted. In other words, the GOA, WDO, and BBO algorithm are mixed with a class of feedforward artificial neural networks (ANN), which called MLP (multi-layer perceptron) to predict the HLs and CLs. According to the provided sensitivity analysis, the WDO with swarm size = 500 proposes the most proper-fitted terms after it has been combined with optimized MLP. The proposed WDO-MLP (training (R2 correlation=0.977 and RMSE error=0.183) and testing (R2 correlation=0.973 and RMSE error=0.190)) provided accurate prediction in the heating load and (training (R2 correlation=0.99 and RMSE error=0.147) and testing (R2 correlation=0.99 and RMSE error=0.148)) presents the most-fit prediction in the cooling load.
Potential for Potable Water Savings Due to Rainwater use in a Precast Concrete Factory
Giovanna Bertuzzi, Enedir Ghisi
Subject: Engineering, Automotive Engineering Keywords: rainwater harvesting; rainwater quality; precast concrete; financial analysis; computer simulation
The objective of this paper is to assess the potential for potable water savings due to rainwater use in a precast concrete factory in southern Brazil. The economic feasibility and the rainwater quality were also assessed. The current water consumption, future water demand and rainwater demand in the factory were estimated. The future demand considered was two times higher than the current water consumption since there are plans to increase the production. Three scenarios were then simulated using the computer programme Netuno. The ideal rainwater tank capacity, the potential for potable water savings and the economic feasibility analysis for each scenario were estimated. Samples of rainwater were collected in the factory and tested for quality for manufacturing precast concrete. For a rainwater tank capacity equal to 25,000 litres, the potential for potable water savings for the first scenario was 55.4%, but the first scenario was considered economically unfeasible. For the same tank capacity, the second and third scenarios presented viable results regarding potable water savings and payback. As for the rainwater quality, it was proven to be adequate for manufacturing precast concrete. The main conclusion is that rainwater can be used to manufacture precast concrete in the factory studied herein.
Efficacy Advanced Chemical Oxidation Process (AOP) for Sustainable Pretreatment of Mixed Dairy and Poultry Wastewaters in Nablus, Palestine
Saja Younes, Rashed Al-Sa`ed
Subject: Engineering, Automotive Engineering Keywords: Advanced oxidation processes; Fenton reaction; sustainable agro-industrial sector; sewer connection permit
This study investigated the efficacy of advanced oxidation process (AOP) for the reduction of pollution loads in mixed agro-food industrial wastewaters (dairy and slaughterhouse) in Nablus city, Palestine. Bench-scale Jar tests using an advanced oxidation process (AOP) were performed as a pretreatment stage. Initial results on direct applications of Fenton's process on mixed agro-food wastewater (COD: 15400-18200 mg/l) were unsatisfactory. Hence, the performance of the Fenton process was applied on three mixed wastewater samples with different pre-treatment trials: (A) coagulant (FeCl3.6H2O) addition, (B) settling (2h), and use of flocculent (lime Ca(OH)2) in sample (C). Preceded with lime, Fenton`s process (Sample C) was most effective in the removal of organic carbon and nitrogen (89% COD; 80% TKN). The removal efficiency in inorganic loads (91% TSS; 62% TS) were achieved under H2O2/COD (w/w ratio 2:1), H2O2/Fe+2 (w/w ratio 10:1) and acidic conditions (pH = 3). The adoption of AOP technology by agro-food industries could ensure compliance with municipal by-laws and acquire connection permits to sewerage networks.
The Hydromechanical Interplay in the Three-dimensional Limit Equilibrium Analyses of Unsaturated Slope Stability
Panagiotis Sitarenios, Francesca Casini
Subject: Engineering, Automotive Engineering Keywords: unsaturated slope; Ruedlingen field experiment; lateral resistance; limit equilibrium solution
The paper presents a three-dimensional slope stability limit equilibrium solution for translational, planar failure modes. The proposed solution uses Bishop's average skeleton stress combined with the Mohr – Coulomb failure criterion to describe soil strength evolution under unsaturated conditions while its formulation ensures a natural and smooth transition from the unsaturated to the saturated regime and vice versa. The proposed analytical solution is evaluated by comparing its predictions with the results of the Ruedlingen slope failure experiment [1]. The comparison suggests that despite its relative simplicity the analytical solution can capture well the experimentally observed behaviour and highlights the importance of lateral resistance consideration together with a realistic interplay between mechanical parameters (cohesion) and hydraulic (pore water pressure) conditions.
Challenges and Experiences of Online Evaluation in Courses of Civil Engineering During the Lockdown Motivated by the COVID-19 Crisis
Marcos García-Alberti, Fernando Suárez, Isabel Chiyón, Juan Carlos Mosquera Feijoo
Subject: Engineering, Automotive Engineering Keywords: COVID-19; online learning; higher education; evaluation
As a consequence of the global sanitary crisis in early 2020, universities had to tackle with a sudden shift in their teaching-learning strategies so that the preset competences could be fulfilled. This study presents the learning outcomes of the tasks implemented, student experiences and feedback, as well as some reflections from the instructors with a holistic perspective of the courses due to the measures and adaptations adopted. Six courses taught at Civil Engineering degrees of three universities, two from Spain and one from Peru, are analyzed. The teaching and evaluation strategies are described and some reflections are made by comparing the student's performance with the previous course. Although the shift to online learning had to be made from day to day, with no time for preparation, the experience has proved that online learning can be beneficial in some aspects and have probably come to stay, although some others are difficult to replace with respect to face-to-face learning, especially students' engagement and motivation.
Working Paper CONCEPT PAPER
Process Design and Sustainable Development - a European Perspective
Peter Glavič, Zorka Novak Pintarič, Miloš Bogataj
Subject: Engineering, Biomedical & Chemical Engineering Keywords: process design; sustainable development; chemical industry; process industry; megatrends; design tools
This paper describes the state of the art and future opportunities for process design and sustainable development. In the Introduction the main global megatrends and European Union's response to two of them, the European Green Deal, are presented. The organization of professionals in the field, their conferences and publications support the two topics. A brief analysis of the published documents in the two most popular databases shows that the environmental dimension predominates, followed by an economic one, while the social pillar of sustainable development is undervalued. The main design tools for sustainability are described. As an important practical case, the European chemical and process industries are analyzed and their achievements in sustainable development are highlighted; in particular, their strategies are presented in more detail. The conclusions cover the most urgent future development areas of the process industries, carbon capture with utilization or storage, process analysis, simulation, synthesis and optimization tools; zero waste, circular economy and resource efficiency already play an important role. However, more profound changes are needed in the coming decades, including a shift away from growth with changes in habits, lifestyles and business models. Lifelong education for sustainable development will play a very important role in the growth of democracy and happiness instead of consumerism and neoliberalism.
An Innovative Metaheuristic Strategy for Solar Energy Management Through a Neural Framework
Subject: Engineering, Automotive Engineering Keywords: Power plant; Electrical power modeling; Metaheuristic strategy; Water cycle algorithm
Proper management of solar energy, as an effective renewable source, is of high importance toward sustainable energy harvesting. This paper offers a novel sophisticated method for predicting solar irradiance (SIr) from environmental conditions. To this end, an efficient metaheuristic technique, namely electromagnetic field optimization (EFO) is employed for optimizing a neural network. This algorithm quickly mines a publicly available dataset for non-linearly tuning the network parameters. To suggest an optimal configuration, five influential parameters of the EFO (i.e., NPop, R_rate, Ps_rate, P_field, and N_field) are optimized by an extensive trial and error practice. Analyzing the results showed that the proposed model can learn the SIr pattern and predict it for unseen conditions with high accuracy. Furthermore, it provided about 10% and 16% higher accuracy compared to two benchmark optimizers, namely shuffled complex evolution and shuffled frog leaping algorithm. Hence, the EFO-supervised neural network can be a promising tool for the early prediction of SIr in practice. The findings of this research may shed light on the use of advanced intelligent models for efficient energy development.
Leveraging Machine-Learning for D2D Communications in 5G/Beyond 5G Networks
Sherief Hashima, Basem Elhalwany, Kohei Hatano, Kaishun Wu, Ehab Mahmoud Mohammed
Subject: Engineering, Automotive Engineering Keywords: D2D communication; mmWave; machine-learning applications; 5G; B5G
Device-to-device (D2D) communication is a promising paradigm for the fifth generation 2 (5G) and beyond 5G (B5G) networks. Although D2D communication provides several benefits, 3 including limited interference, energy efficiency, reduced delay, and network overhead, it faces a lot 4 of technical challenges such as network architecture, and neighbor discovery, etc. The complexity 5 of configuring D2D links and managing their interference, especially when using millimeter-wave 6 (mmWave), inspire researchers to leverage different machine-learning (ML) techniques to address 7 these problems towards boosting the performance of D2D networks. In this paper, a comprehensive 8 survey about recent research activities on D2D networks will be explored with putting more 9 emphasis on utilizing mmWave and ML methods. After exploring existing D2D research directions 10 accompanied with their existing conventional solutions, we will show how different ML techniques 11 can be applied to enhance the D2D networks performance over using conventional ways. Then, still 12 open research directions in ML applications on D2D networks will be investigated including their 13 essential needs. A case study of applying multi-armed bandit (MAB) as an efficient online ML tool 14 to enhance the performance of neighbor discovery and selection (NDS) in mmWave D2D networks 15 will be presented. This case study will put emphasis on the high potency of using ML solutions 16 over using the conventional non-ML based methods for highly improving the average throughput 17 performance of mmWave NDS.
Seakeeping Tests of a Fowt in Wind and Waves: An Analysis of Dynamic Coupling Effects and Their Impact on the Predictions of Pitch Motion Response
Giovanni Aiosa do Amaral, Pedro Mello, Lucas Henrique Souza Carmo, Izabela Franzão Alberto, Edgard Borges Malta, Alexandre Nicolaos Simos, Guilherme Rosa Franzini, Rodolfo T. Gonçalves, Hideyuki Suzuki
Subject: Engineering, Automotive Engineering Keywords: FOWT dynamics; seakeeping model tests; dynamic coupling effects; pitch motion response.
The present work highlights some of the dynamic couplings observed in a series of tests performed in a wave basin with a scaled-model of a FOWT with semi-submersible substructure. The model was moored by means of a conventional chain catenary system and an actively controlled fan was used for emulating the thrust loads during the tests. A set of wave tests comprising regular and irregular waves was done for different wave angles and wind velocities. The experimental records illustrate the main coupling effects involved and how they affect the FOWT motions in waves, especially when the floater presents a non-negligible tilt angle.. In addition, an analysis of the frequency-domain dynamic model was made in order to evaluate its ability to capture these effects properly. The influence of different modes of fan response, floater trim angles (changeable with ballast compensation) and variations of the mooring stiffness with the offsets were investigated in the analysis. Results attest that significant changes in the FOWT responses may indeed arise from coupling effects, thus indicating that caution must be taken when simplifying the hydrodynamic frequency-domain models often used as a basis for the simulation of FOWTs in waves and in in optimization procedures for the design of the floater and mooring lines.
Resilience in Complex Catchment Systems
Lindsay Beevers, Melissa Bedinger, Kerri McClymont, Annie Visser-Quinn
Subject: Engineering, Civil Engineering Keywords: resilience; complex systems; catchment
In this paper we explore how we can use catchment resilience as a unifying concept to manage and regulate catchments, using structured reviews to support our perspective. River catchments are physical boundaries which delineate where all surface water (e.g. precipitation, snow, meltwater) falling on a piece of land runs off or flows to a single point at a lower elevation, where the river meets a larger body of water (e.g. sea, lake). Catchments are complex systems with interrelated natural, social, and technical aspects. The exposure, vulnerability, and resilience of these aspects (separately and in combination) are the latent conditions which when triggered by a specific hazard, result in catchment impacts. In complex catchment systems, resilience is the ability to bounce-back, the ability to absorb, and the ability to transform. When all three abilities are accounted for, we are forced to consider the interactions of the catchment system. Six main complexity concepts can be used to frame how we approach evaluating catchment resilience. These concepts are: natural-social-technical aspects, interactions, spatial scales, time scales, multiple forms of evidence, and uncertainty. In analysing these complexity concepts we have found that there are several gaps in current practice. For example critical interactions which need further methodological study are the linkages between the natural-social-technical realms, as well as across spatial scales (e.g. households or communities) and time scales (e.g. days or years). Requirements for future methodological approaches are suggested. Central to these is (1) the study of interactions linking the short- to medium-term time scales (2) better integration of bottom-up and top-down approaches, to link local context with higher-level decision-making, and (3) developing 'hazard-agnostic' methods which can address the impacts of floods, droughts – even acknowledging dormant 'socio-technical hazards'. There is no 'one size fits all' approach to catchment resilience. Mixed method approaches are required and their selection will depend on contextual issues identified early in the process for specific catchments. Central to any effective approach is the incorporation of a linking systems or interaction analysis, which draws together the natural-social-technical system in a meaningful way. If our approaches do not begin to acknowledge the interdependencies and interactions, we may miss substantial opportunities to enhance catchment resilience.
Commercial Thermal Technologies for Desalination of Water from Renewable Energies: A State of the Art Review
Jhon Feria-Díaz, María Cristina López-Méndez, Luis Sandoval-Herazo, Felipe Correa-Mahecha, Juan Rodríguez-Miranda
Subject: Engineering, Other Keywords: Desalination; Multi Effect Distillation; Multi Stage Flash; Vapor Compression Distillation; Renewable Energies.
Abstract: Thermal desalination is yet a reliable technology in the treatment of brackish water and seawater; however, its demanding high energy requirements have lagged it compared to other non-thermal technologies such as reverse osmosis. This review provides an outline of the development and trends of the three most commercially used thermal or phase change technologies worldwide: Multi Effect Distillation (MED), Multi Stage Flash (MSF), and Vapor Compression Distillation (VCD). First, state of water stress suffered by regions with little fresh water availability and existing desalination technologies that could become an alternative solution are shown. The most recent studies published for each commercial thermal technology are presented, focusing on optimizing the desalination process, improving efficiencies, and reducing energy demands. Then, an overview of the use of renewable energy and its potential for integration into both commercial and non-commercial desalination systems is shown. Finally, research trends and their orientation towards hybridization of technologies and use of renewable energies as a relevant alternative to the current problems of brackish water desalination are discussed. This reflective and updated review will help researchers to have a detailed state of the art of the subject and to have a starting point for their research, since current advances and trends on thermal desalination are shown.
Model of Problem Solving for Robotic Actions Planning
Oleksandr Tsymbal, Paolo Mercorelli
Subject: Engineering, Control & Systems Engineering Keywords: adaptation; problem-solving; robotics; predicates; manufacturing system
Proposed article deals with analyses on trends of problem-solving robotic applications in manu-facturing, especially in transportations and manipulations. Intelligent agent-based manufacturing systems with robotic agents are observed. Intelligent core of such units must be able to propose the plan of problem-solving in form of strategy. The logical model of adaptive strategies planning for intelligent robotic system is described in form of predicates with presentation of data processing on base of set theory descriptions. Dynamic structure of workspace and possible change of goals are considered as reasons for functional strategies adaptation. Proposed formal descriptions are sup-ported by model of mobile robotic platform, acting in warehouse.
Microorganisms: A Potential Source of Bioactive molecules for Antioxidants and Antimicrobial Applications
Alka Rani, Khem Chand Saini, Felix Bast, Sanjeet Mehariya, Shashi Kant Bhatia, Roberto Lavecchia, Antonio Zuorro
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Astaxanthin; natural antioxidant; bacteriocins; hispidin; oxidative stress
Oxidative stress is an elevated intracellular level of free oxygen radicals that cause lipid peroxidation, protein denaturation, DNA hydroxylation, and apoptosis, ultimately negotiating cells viability. Antioxidants can scavenge such free radicals, thus reducing the oxidative stress and eventually prevent cellular damage. Medicinal plants, fruits, and spices remain the prioritized sources of antioxidants and antimicrobial properties since the time immemorial, but in contrast to plants, microorganisms can be grown at a faster rate under controlled conditions. They are non-toxic, non-carcinogenic, and biodegradable as compared to synthetic antioxidants. Microorganisms including actinomycetes, archaea, bacteria, protozoa, yeast, and fungi are auspicious source of vital bioactive compounds. The list comprises ample of bioactive components from microorganisms. One of them is bacteriocins, which are ribosomally synthesized antimicrobial peptides product of Eurotium sp., Streptomyces parvulus, S. thermophiles, Lactococcus lactis, etc. It has a great potential as next-generation antibiotics targeting the multiple-drug resistant pathogens. Pneumocandins are antifungal lipohexapeptides derived from the fungus Glarea lozoyensis, and inhibit 1,3-β-glucan synthase of the fungal cell wall and act as a precursor for the synthesis of caspofungin. It is widely used against invasive fungal infections and has been recently approved by the FDA. Taxol (paclitaxel), a chemotherapeutic drug derived from the bark of Taxus brevifolia can also be produced by endophytic fungi Taxomyces andreanae and Nodulisporium sylviforme. It is known to inhibit several fungi such as Pythium, Aphanomyces and Phytophthora. Hispidin and its derivate isolated from P. hispidus, reduce inducible nitric oxide synthase (iNOS) expression, obstruct the transcriptional activity of NF-κB, and also decrease the production of reactive oxygen species (ROS) in macrophages. Astaxanthin, known as an "aquatic" carotenoid produced by H. pluvialis, also has excellent ROS quenching activity. This study mainly focuses on fascinating antioxidant and antimicrobial compounds that have been scarcely investigated in microorganisms and discuss the promise and challenges of microorganisms as providers of health benefits.
An Expansion Planning Method for Extending Distributed Energy System Lifespan with ESS
Said Mirza Tercan, Onur Elma, Erdin Gokalp, Umit Cali
Subject: Engineering, Automotive Engineering Keywords: Energy storage systems; distribution energy systems; cost analysis; upgrade deferring; voltage improvement
Growing energy demand in the distributed energy system (DES) besides new charging loads of electric vehicles (EVs) make DES infrastructure unavailable earlier than normal projections. DES lines need to be upgraded to carry the modern demand of customers. DES line upgrade (LU) cost minimized and deferred to the next years by using energy storage system (ESS). ESS offers the opportunity to use energy flexibly in the distribution grid. It is possible to use ESS to shift the inevitable upgrade costs of the distribution grid elements and increase the power quality of the distribution grid. In this study, a method is proposed to extend the lifespan of DES with ESS and reduce line upgrade and investment costs in the distribution system. For this purpose, the IEEE 33 bus test grid is used, and the proposed method is tested and analyzed with different case studies. According to the results, the proposed method can reduce the investment cost by up to 80%. Besides, ESS usage considering load increase and line conditions of the distribution grid, upgrade costs of distribution grid are shifted, resulting in an optimal dimensioning and positioning while extending the lifespan of the distribution grid elements and, at the same time, offering significant improvements in energy quality. Additionally, it is seen that the power losses of the distribution grid are reduced up to 26%, and the voltage profile of buses is improved with the usage of ESS.
Hybrid Optimization Model for Conjunctive Use of Surface and Groundwater Resources in Water Deficit Irrigation System
Karthikeyan MoothampalayamSampathkumar, Saravanan Ramasamy, Balamurugan Ramasubbu, Hamid Reza Pourghasemi, Saravanan Karuppanan, Balaji Lakshminarayanan
Subject: Engineering, Automotive Engineering Keywords: conjunctive use; cropping pattern; genetic algorithm; bacterial foraging optimization; ant colony optimization; hybrid optimization; productivity
Increasing demand for food production with limited available water resources pose the threat to agricultural activities. The conjunctive allocation of water resources maximizes the net benefit of farmers efficiently. In this study, a novel hybrid optimization model was developed based on a genetic algorithm (GA), bacterial foraging optimization (BFO) and ant colony optimization (ACO) to maximize the net benefit of water deficit Sathanur reservoir command. The GA-based opti-mization model considered crop-related physical and economical parameters to derive optimal cropping patterns for three different conjunctive use policies and further allocation of surface and groundwater for different crops are enhanced with the BFO. The allocation of surface and groundwater for the head, middle and tail reach obtained from BFO is considered as input to ACO as a guiding mechanism to attain an optimal cropping pattern. Comparing the average produc-tivity values Policy 3 (3.665 Rs/m3) has better values relating to Policy 1 (3.662 Rs/m3) and Policy 2 (3.440 Rs/m3). Thus, the developed novel hybrid optimization model (GA-BFO-ACO) is very promising to enhance the farmer's net income as well as for the command area water conservation and can be replicated in other irrigated regions of the globe to overcome chronic land and water problems.
Dual-Rate Lane-Keeping Control for an Autonomous Ground Vehicle. Comparison of Different Strategies
Julian Mauricio Salt Ducajú, Julián J. Salt Llobregat, Angel Cuenca Lacruz, Masayoshi Tomizuka
Subject: Engineering, Automotive Engineering Keywords: Autonomous Vehicle; Dual-rate control; Dual-rate EKF; MPC; LPV model
In this contribution, different lane-keeping control strategies for Autonomous Ground Vehicles (AGV) have been analyzed and compared. The AGV must be oriented and kept within a given reference path using the front wheel steering angle as the control action for a specific longitudinal velocity. While non-linear models can describe the lateral dynamics of the vehicle in an accurate manner, they might lead to difficulties when computing some real-time control laws such as Model Predictive Control (MPC). Linear Parameter Varying (LPV) models can provide a trade-off between computational complexity and model accuracy. Another way to reduce computational complexity is to explore other control strategies, for example, the one based on the Inverse Kinematic Bicycle model (IKIBI). Additionally, AGV sensors typically work at different measurement acquisition frequencies so that Kalman Filters (KF) are usually needed for sensor fusion. If these frequencies are slower than the actuation rate, a multi-rate KF may be needed. The two control strategies (MPC using a LPV model and IKIBI) have been compared in simulations over a circuit path in the presence of process and measurement Gaussian noise. The MPC controller has shown to provide a more accurate lane-keeping behavior than an IKIBI control strategy. Finally, it has been seen that Dual-Rate Extended Kalman Filters (DREKF) constitute an essential tool when only slow and noisy sensor feedback is available in an AGV lane-keeping application.
Contextual Emotion Appraisal Based on a Sentential Cognitive System for Robots
Hyunsik Ahn, Sung Park
Subject: Engineering, Automotive Engineering Keywords: emotion appraisal system; contextual emotion appraisal; cognitive robotics; sentential cognitive system; HRI
Emotion plays a powerful role in humans' interaction with robots. In order to express more human-friendly emotions, robots need the capability of contextual appraisal that expresses the emotional relevance of various targets in the spatiotemporal situation. In this paper, an emotional appraisal methodology is proposed in this study to cope with such contexts. Specifically, the Ortony, Clore, and Collins model is abstracted and simplified to approximate an emotional appraisal model in the form of a sentence-based cognitive system. The contextual emotion appraisal is modeled by formulating the emotional relationships among multiple targets and the emotional transition with events and time passing. To verify the proposed robotic system's feasibility, simulations were conducted for scenarios where it emotional interacts with humans manipulating liked or disliked objects on a table. This experiment demonstrated that the robot's emotion can variously change over time like human by using a proposed formula for emotional valence, which is moderated by emotion appraisal of occurring events.
Microgrids Power Quality Enhancement Using Model Predictive Control
Félix Garcia-Torres, Sergio Vazquez, Isabel Moreno-Garcia, Aurora Gil-de-Castro, Pedro Roncero-Sánchez, Antonio Moreno-Munoz
Subject: Engineering, Automotive Engineering Keywords: Microgrids; Power Quality and Reliability; Model Predictive Control; Interconnected systems; Harmonics; Power System Control
In this paper, the power quality of interconnected microgrids is managed using a Model Predictive Control (MPC) methodology which manipulates the power converters of the microgrids in order to achieve the requirements. The control algorithm is developed for the microgrids working modes: grid-connected, islanded and interconnected. The results and simulations are also applied to the transition between the different working modes. In order to show the potential of the control algorithm, a comparison study is carried out with classical Proportional-Integral Pulse Width Modulation (PI-PWM) based controllers. The proposed control algorithm not only improves the transient response in comparison with classical methods but also shows an optimal behavior in all the working modes, minimizing the harmonics content in current and voltage even with the presence of non-balanced and non-harmonic-free three-phase voltage and current systems
CFD Modelling and Optimization Procedure of an Adhesive System for a Modular Climbing Robot
Miguel Hernando, Virgilio Gómez, Alberto Brunete, Ernesto Gambao
Subject: Engineering, Automotive Engineering Keywords: Modular Climbing Robots; Vacuum Generation; Computer Fluid Dynamics; Optimization
Adhesion systems are very important in robots for infrastructure inspection (especially in vertical walls). They present the challenge of optimizing the ratio vacuum/power consumption in battery-powered robots. In this paper a CFD (Computer Fluid Dynamics) modelling and optimization process of a robot adhesion system is carried out to determine the best performing configuration in terms of vacuum and power consumption. Analytical and numerical models were developed to predict the behaviour of the system for different configurations. The models were validated, using test rig measurements, by calibrating an arbitrary defined inlet height that simulates the leakage flow. Then, different geometric parameters were varied to determine the best performing configuration based on the vacuum/power consumption ratio value. The model presented in the paper was capable of predicting the behaviour of the system for different configurations, with a margin of error of 15% for the vacuum prediction and a 25% for the motor power calculation. Finally, the model was used to optimize parameters of the system, like the number of blades of the impeller. The adhesion system was conceived for the modular autonomous climbing legged robot ROMERIN.
Efficacy of Natural Wetlands along Wadi Zomer as a Sustainable Phytoremediation Alternative for Industrial Effluents from Nablus West, Palestine
Odai Attili, Rashed Al-Sa'ed
Subject: Engineering, Automotive Engineering Keywords: heavy metals; industrial wastewater; natural wetlands; phytoremediation; Wadi Zomer restoration; water quality
This paper investigated the effectiveness of natural wetlands (Phragmites australis) along Wadi Zomer in reducing the organic and inorganic pollution loads from diverse industrial discharges including occasional emergency discharges from Nablus West Sewage Treatment Plant (NWSTP), Palestine. We monitored physical and chemical parameters at four selective sampling stations (S1-S4) along Wadi Zomer with a length of 5 km downstream of NWSTP to assess the purification capacity of Wadi Zomer treatment wetlands (water, sediment, and vegetation) with Phragmites australis in pollution loads reduction. The results showed that S2 (0+0.5 km) and S3 (0+3.0 km) reflected an increase in pollution loads due to illicit industrial discharge and sewer overflow discharge from NWSTP during emergency conditions. BOD values varied significantly along the sampling sites from 6.64 mg/l (S1) to 437.10 mg/l (S3). The BOD at S1 and S2 in water samples were below the Palestinian Water Standard (PWS) compared to S3 and S4 with 437.1 and 333.9 mg/l, respectively. Water samples from all sites (S1-S4) showed a decreasing tendency in heavy metals concentrations (Fe>Cu>Zn>Cr >Ni) and were below the PWS limits, sediment samples followed the same decrease pattern for Zn, Cr, and Ni content with Wadi Zomer flow course. The concentration of Fe (6687 mg/kg) and Cu (1384.7 mg/kg) were highest in the sediment samples (S1-S4); this might be due to non-point sources of pollution. The research demonstrated that phytoremediation is a sustainable nature-based technology for the restoration of heavily polluted surface water bodies in Palestine.
Microstructure and Mechanical Properties of Laser-welded DP Steels Used in the Automotive Industry
Hanbing He, Farnoosh Forouzan, Joerg Volpp, Stephanie M. Robertson, Esa Vuorinen
Subject: Engineering, Industrial & Manufacturing Engineering Keywords: Laser welding; Dual phase steel; Similar/dissimilar welded joints; Microhardness; Tensile properties; Fatigue
The aim of this work was to investigate the microstructure and the mechanical properties of la-ser-welded joints combined of DP800 and DP1000 high strength thin steel sheets. The welded joints (WJ) comprised of similar/dissimilar steels with similar/dissimilar thickness were consisted of different zones and exhibited similar microstructural characteristics. The trend of microhard-ness for all WJs was consistent, characterized of the highest value at hardening zone (HZ) and lowest at softening zone (SZ). The degree of softening was more severe and the size of SZ was wider in the WJ combinations of DP1000 than DP800. The tensile test fractures were located at the base material (BM) for all DP800 weldments, while the fractures occurred at the fusion zone (FZ) for the weldments with DP1000 and those with dissimilar sheet thicknesses. The DP800-DP1000 weldment presented similar yield strength (YS) and ultimate tensile strength (UTS) values but lower elongation (EI) in comparison with the DP800-DP800 weldment, which showed similar strength properties as the BM of DP800. However, the EI of DP1000-DP1000 weldment was much lower in comparison with the BM of DP1000. The DP800-DP1000 weldment with dissimilar thicknesses showed the highest YS and UTS values compared with the other weldments, but with the lowest EI. The fatigue fractures occurred at the WJ for all types of weldments. The DP800-DP800 weldment had the highest fatigue limit and DP800-DP1000 with dissimilar thick-nesses had the lowest fatigue limit. The fatigue crack initiated from the weld surface.
Evaluation of Advanced Chemical Oxidation Process for the Pretreatment of Mixed Agro-Food Industrial Wastewater in Nablus, Palestine
Saja Younis, Rashed Al-Sa`ed
Subject: Engineering, Civil Engineering Keywords: Advanced oxidation processes; Fenton reaction; agro-industrial wastewater; municipal by-laws; sewer connection permit
This study investigated the reduction of organic loads from mixed agro-food industrial wastewaters (dairy and slaughterhouse) of Nablus city using advanced oxidation process (AOP), a high- rate chemical oxidation reaction. Bench-scale Jar tests using an advanced oxidation process (AOP) were performed as a pretreatment stage. Direct applications of classical Fenton's process on mixed raw agro-food wastewater samples (COD: 15400-18200 mg/l) revealed unsatisfactory results. The performance of the Fenton process was evaluated using three mixed samples with different pre-treatment trials: (A) coagulant (FeCl3.6H2O) addition, (B) settling (2h) allowed, and use of flocculent (lime Ca(OH)2) in sample (C). Compared with other partial treatments, sample (C), Fenton`s process lime preceded, was the most effective in the removal of organic (89% COD; 80% TKN) and inorganic loads (91% TSS; 62% TS) under H2O2/COD (w/w ratio 2:1), H2O2/Fe+2 (w/w ratio 10:1) and acidic conditions (pH =3). Obtained results comply with Nablus municipal by-law (COD below 2000 mg/l), which help decision-makers within the agro-food industries install pollution reduction systems. Investment in the Fenton-based peroxidation process, allow agro-food industries to obtain connection permits to sewage networks.
Mesh-type 3D Printing of Human Organs and Tumors: Fast, Cost-Effective, and Personalized Anatomic Modeling
Jungirl Seok, Sungmin Yoon, Chang Hwan Ryu, Junsun Ryu, Seok-ki Kim, Yuh-Seog Jung
Subject: Engineering, Automotive Engineering Keywords: 3D printing; anatomic modeling
OBJECTIVE: Although 3D-printed anatomic models are not new to medicine, the high costs and lengthy production times entailed have limited their application. Our goal was developing a new and less costly 3D modeling method to depict organ-tumor relations at faster printing speeds. METHODS: We have devised a method of 3D modeling using DICOM images. Coordinates are extracted at a specified interval, connecting them to create mesh-work replicas. Adjacent constructs are depicted by density variations, showing anatomic targets (ie, tumors) in contrasting color. RESULTS: An array of organ solid-tumor models were printed via Fused Deposition Modeling 3D printer at significantly less cost ($0.05/cm3) and time expenditure (1.73 min/cm3; both, p<.001). Printed models helped promote visual appreciation of organ-tumor anatomy and adjacent tissues. Our mesh-work 3D thyroidal prototype reproduced glangular size/contour and tumor location, readily approximating the surgical specimen. CONCLUSIONS: This newly devised mesh-type 3D printing method may facilitate anatomic modeling for personalized care and improve patient awareness during informed surgical consent.
Biorefinery-Based Approach to Exploit Mixed Cultures of Lipomyces Starkeyi and Chloroidium saccharophilum for Single Cell Oil Production
Gaetano Zuccaro, Angelo del Mondo, Gabriele Pinto, Antonino Pollio, Antonino De Natale
Subject: Engineering, Automotive Engineering Keywords: Mixed culture; Lipomyces starkeyi; Chloroidium saccharophilum; Single Cell Oils (SCOs); Arundo donax; biorefinery.
The mutualistic interactions between the oleaginous yeast Lipomyces starkeyi and the green mi-croalga Chloroidium saccharophilum in mixed cultures were investigated to exploit possible syner-gistic effects. As a matter of facts, microalga could act as an oxygen generator for the yeast, while the yeast could provide carbon dioxide to microalga. A lignocellulosic hydrolysate from steam exploded Arundo donax (Giant reed) was used as low cost feedstock. The overall lipid content and lipid productivity obtained in the mixed culture treating the hydrolysate of Arundo donax were equal to 0.081 glipid.gbiomass-1 and 37.2 mglipid.L-1.d-1, respectively. They represented promising re-sults if compared to the model systems where synthetic media were used. This study provided new input for the integration of Single Cell Oil (SCO) production with agro-industrial feedstock and the fatty acid distribution mainly consisting of stearic (C18:0) and oleic acid (C18:1) allows promising applications in biofuels, cosmetics, food additives and other products of industrial interest.
A Thermal-Hydraulic Model for the Stagnation of Solar Thermal Systems with Flat-Plate Collector Arrays
Ralph Eismann, Sebastian Hummel, Federico Giovannetti
Subject: Engineering, Energy & Fuel Technology Keywords: Solar thermal; flat-plate collector; stagnation; steam range; two-phase mixture model; thermal-hydraulic model.
Stagnation is the transient state of a solar thermal system under high solar irradiation where the useful solar gain is zero. Both flat-plate collectors with selective absorber coatings and vacuum-tube collectors exhibit stagnation temperatures far above the saturation temperature of the glycol-based heat carriers within the range of typical system pressures. Therefore, stagnation is always associated with vaporization and propagation of vapor into the pipes of the solar circuit. It is therefore essential to design the system in such a way that vapor never reaches components that cannot withstand high temperatures. In this article, a thermal-hydraulic model based on the integral form of a two-phase mixture model and a drift-flux correlation is presented. The model is applicable to solar thermal flat-plate collectors with meander-shaped absorber tubes and selective absorber coatings. Experimental data from stagnation experiments on two systems, which are identical except for the optical properties of the absorber coating, allowed comparison with simulations carried out under the same boundary conditions. The absorber of one system features a conventional highly selective coating, while the absorber of the other system features a thermochromic coating, which exhibits a significantly lower stagnation temperature. Comparison of simulation results and experimental data show good conformity. This model is implemented into an open-source software tool called "THD" for the thermal-hydraulic dimensioning of solar systems. The latest version of THD, updated by the results of this article, enables planners to achieve cost-optimal design of solar thermal systems and to ensure failsafe operation by predicting the steam range under the initial and boundary conditions of worst-case scenarios.
Mechanical Behaviors and Frost-Resistance of Alkali Activated Cement Concrete with Different Binder Systems
Biruk Hailu Tekle, Klaus Holschemacher, Philipp Löber, Björn Heiden
Subject: Engineering, Automotive Engineering Keywords: alkali activated; fly ash; blast furnace slag; silica fume; metakaolin; ambient curing; strength development; flexural strength; freeze-thaw resistance
Concrete is the most commonly used construction material due to its various advantages, such as versatility, familiarity, strength and durability and it will continue to be in demand far into the future. However, with today's sensitivity to the environmental protection, this material is facing unprecedented challenges due to its high greenhouse gas emission mainly during cement production. This paper investigates one of the promising cement replacement materials, alkali activated cement (AAC) concrete. Being produced mainly from byproduct materials and having a comparable structural performance to conventional concrete, AAC concrete has a potential to transform the construction industry. Mechanical properties such as compressive and flexural strength and the relationship between them are studied. Different source materials such as fly ash (FA), ground granulated blast furnace slag (GGBS), silica fume (SF) and Metakaolin (MK) are used. The effect of the source materials and the activator solutions on the concrete performance is studied. Furthermore, the freeze-thaw resistance of the concrete is studied. The results of the study showed that the behavior of AAC depends highly on the source material combinations as well as type used. The effect of the alkaline solution is also dependent on the source material used. Mixes with higher GGBS content in general showed the highest strength while mixes with MK showed the highest flexural strength. The results from the freeze-thaw test showed that proper design of AAC concrete with a lower water content is critical to achieve a good resistance.
Impact of using CSS PHY and RTS/CTS Combined with Frame Concatenation in the IEEE 802.15.4 Non-beacon Enabled Mode Performance
Norberto Barroca, Luís M. Borges, Fernando José Velez, Periklis Chatzimisios
Subject: Engineering, Electrical & Electronic Engineering Keywords: Wireless Sensor Networks; MAC sub-layer; RTS/CTS/ non-beacon mode; packet concatenation; channel use; IEEE 802.15.4
This paper studies the performance improvement for the nonbeacon-enabled mode of IEEE 802.15.4 originated by the inclusion of the Request-To-Send/Clear-To-Send (RTS/CTS) handshake mechanism combined with frame concatenation. Under IEEE 802.15.4 employing RTS/CTS, the backoff procedure is not repeated for each data frame sent but only for each RTS/CTS set. The throughput and delay performance are mathematically derived for both the Chirp Spread Spectrum and Direct Sequence Spread Spectrum Physical layers for the 2.4 GHz band. The results show that the utilization of RTS/CTS significantly enhances the performance of IEEE 802.15.4 in terms of maximum throughput, minimum delay and bandwidth efficiency.
Two Link's Motion Simulation of Exoskeleton Supporting Leg in 3-D
Andrey Borisov
Subject: Engineering, Automotive Engineering Keywords: exoskeleton; hinge; variable-length link; human musculoskeletal system; angle between links; local system of coordinates; controlling forces and torques
A two-link model of exoskeleton with variable-length links for supporting the lower limbs of the human musculoskeletal system is proposed in the article. The researched model differs from the existing ones by the variable-length links, and by the angle calculation method. While in the existing models, the angles are calculated from the regular direction – from vertical, or from horizontal, - in the proposed research they are calculated between the links. As for practical exoskeleton implementation, the proposed method of angle calculation is appropriate to the actual working conditions of the electrical motors with the reduction gears installed in the hinges, which change the angles between the links. The mathematical model in the form of the system of Lagrange differential equations of the second kind is obtained. The obtained mathematical model is examined for existence and uniqueness of the Cauchy solution. The kinematic trajectory of the link motion has been synthesized. The controlling actions required for its implementation have been found.
Adaptive Design of Formworks for Building Renovation Considering the Sustainability of Construction in Bim Environment – Case Study
Peter Mésároš, Marcela Spišáková, Tomáš Mandičák, Jozef Čabala, Milan Oravec
Subject: Engineering, Automotive Engineering Keywords: adaptive design; sustainability of construction; BIM environment; formwork
Progressive technologies and practices are shifting the possibilities of building design and improving work efficiency. Constantly changing site conditions require different procedures and designs that take into account these changing conditions, whether it is a design solution, a change in environmental conditions, or just sustainability factors. Adaptive building design offers opportunities to cope with changing factors to achieve the highest possible level of building quality. This case study deals with the topic of adaptive formwork design for building renovation, taking into account sustainability. Aim of the article is an investigation and demonstration of the building information modelling (BIM) environment used for the adaptive design of formwork elements for the building renovation in the context of sustainability. The object of the case study is a building in the center of Kosice, Slovakia. BIM environment allows prompt and correct adaptation of the formwork design to changing conditions of lighting, ventilation, heating and temperature during the design of the building.
Improved RRT-Connect Algorithm Based on Triangular Inequality for Robot Path Planning
Jin-Gu Kang, Dong-Woo Lim, Yong-Sik Choi, Woo-Jin Jang, Jin-Woo Jung
Subject: Engineering, Automotive Engineering Keywords: RRT-Connect; triangular inequality; rewiring; optimality; robot path planning
This paper proposed a triangular inequality-based rewiring method for the Rapidly exploring Random Tree (RRT)-Connect robot path-planning algorithm that guarantees the planning time compared to the RRT algorithm, to bring it closer to the optimum. To check the proposed algorithm's performance, this paper compared the RRT and RRT-Connect algorithms in various environments through simulation. From these experimental results, the proposed algorithm shows both quicker planning time and shorter path length than the RRT algorithm and shorter path length than the RRT-Connect algorithm with a similar number of samples and planning time.
Conceptual Framework for Quantum Affective Computing and Its Use in Fusion of Multi-Robot Emotions
Fei Yan, Abdullah Iliyasu, Kaoru Hirota
Subject: Engineering, Electrical & Electronic Engineering Keywords: Affective computing; Artificial intelligence; Quantum emotion; Emotion fusion; Social robots
This study presents a modest attempt to interpret, formulate, and manipulate emotion of robots within the precepts of quantum mechanics. Our proposed framework encodes the emotion information as a superposition state whilst unitary operators are used to manipulate the transition of the emotion states which are recovered via appropriate quantum measurement operations. The framework described provides essential steps towards exploiting the potency of quantum mechanics in a quantum affective computing paradigm. Further, the emotions of multi-robots in a specified communication scenario are fused using quantum entanglement thereby reducing the number of qubits required to capture the emotion states of all the robots in the environment, and fewer quantum gates are needed to transform the emotion of all or part of the robots from one state to another. In addition to the mathematical rigours expected of the proposed framework, we present a few simulation-based demonstrations to illustrate its feasibility and effectiveness. This exposition is an important step in the transition of formulations of emotional intelligence to the quantum era.
Towards a Biomanufactory on Mars
Aaron Berliner, Jacob M. Hilzinger, Anthony J. Abel, Matthew McNulty, George Makrygiorgos, Nils J.H. Averesch, Soumyajit Sen Gupta, Alexander Benvenuti, Daniel Caddell, Stefano Cestellos-Blanco, Anna Doloman, Skyler Friedline, Desiree Ho, Wenyu Gu, Avery Hill, Paul Kusuma, Isaac Lipsky, Mia Mirkovic, Jorge Meraz, Vince Pane, Kyle B. Sander, Fengzhe Shi, Jeffrey M. Skerker, Alexander Styer, Kyle Valgardson, Kelly Wetmore, Sung-Geun Woo, Yongao Xiong, Kevin Yates, Cindy Zhang, Shuyang Zhen, Bruce Bugbee, Devin Coleman-Derr, Ali Mesbah, Somen Nandi, Robert W. Waymouth, Peidong Yang, Craig S. Criddle, Karen A. McDonald, Amor A. Menezes, Lance C. Seefeldt, Douglas S. Clark, Adam P. Arkin
Subject: Engineering, Automotive Engineering Keywords: space systems bioengineering; human exploration; mars; in situ resource utilization; life support systems; biomanufacturing
A crewed mission to and from Mars may include an exciting array of enabling biotechnologies that leverage inherent mass, power, and volume advantages over traditional abiotic approaches. In this perspective, we articulate the scientific and engineering goals and constraints, along with example systems, that guide the design of a surface biomanufactory. Extending past arguments for exploiting stand-alone elements of biology, we argue for an integrated biomanufacturing plant replete with modules for microbial \textit{in situ} resource utilization, production, and recycling of food, pharmaceuticals, and biomaterials required for sustaining future intrepid astronauts. We also discuss aspirational technology trends in each of these target areas in the context of human and robotic exploration missions in the coming century.
The Potential Role of Artificial Marsh on Coastal Protection in Long Island Sound
Amin Ilia
Subject: Engineering, Automotive Engineering Keywords: Salt Marsh; Coastal Protection; Long Island Sound; Connecticut; Green Structures; Ecosystem based
Connecticut marshes, like other marshes in the world, are vulnerable to anthropogenic and climate change effects. However, assessment of current sea level rise and average marsh accretion rates in Connecticut demonstrate sea level rise is not the main vulnerable factor for salt marshes loss. The study on the feasibility of developing an ecosystem-based on two coastlines in Connecticut, Guilford and Stratford, shows that both coastlines, like other coastlines in Connecticut, have limited wave energy, which is a positive factor for marsh growth. The available data assessment represents that sediment supply is the most important parameter to guarantee the resilience and sustainability of a newly developed salt marsh system in Connecticut. In Stratford, conditions for establishing a new ecosystem seem to be better, as the fetch length is pretty small, and there is some sediment supply for the ecosystem. In Guilford, wave energy is limited, but it is more than in Stratford case. Besides, sediment availability is low and the coastline experienced considerable erosion during hurricane Sandy and has not recovered yet.
Effects of MOVPE Growth Conditions on GaN Layers Doped with Germanium
Dario Schiavon, Elżbieta Litwin-Staszewska, Rafał Jakieła, Szymon Grzanka, Piotr Perlin
Subject: Engineering, Electrical & Electronic Engineering Keywords: Ge; germanium; doping; GaN; gallium; nitride; MOVPE; epitaxy
The effect of growth temperature and precursor flows on the doping level and surface morphology of Ge-doped GaN layers was researched. The results show that germanium is more readily incorporated at low temperature, high growth rate and high V/III ratio, thus revealing a similar behavior to what was previously observed for indium. V-pit formation can be blocked at high temperature but also at low V/III ratio, the latter of which however causing step bunching.
Sat, 26 December 2020
Biofilm Early Stages Growth and Accumulation Theoretical Model
José Carvalho, Manuel Carrondo, Luis Bonilla
Subject: Engineering, Automotive Engineering Keywords: biofilm; Miller recurrent algorithm; Bessel functions; differential-difference master equations
A theoretical model to translate the evolution over time, in early stages, of growth and accumulation of biofilm bacterial mass is introduced. The model implies the solution of a system of differential-difference master equations. The application of an algorithm like Miller´s tree term recurrence, already known for Bessel functions of first kind, allows an exact calculation of the solutions of such equations, for a wide range of parameters values and time. For biofilm model a five term recurrence is deduced and applied in a backwards computation. A suitable normalisation condition completes the reach of the solution.
Dynamic Real-Time Risk Analytics of Uncontrollable States in Complex Internet of Things Systems: Cyber Risk at the Edge
Petar Radanliev, David De Roure, Max Van Kleek, Pete Burnap, Eirini Anthi, Jason R.C. Nurse, Omar Santos, Rafael Mantilla Montalvo, La'Treall Maddox
Subject: Engineering, Automotive Engineering Keywords: functional dependency; network-based linear dependency modelling; internet of things; micro mort model; goal-oriented approach; transformation roadmap; cyber risk regulations; empirical analysis; cyber risk self-assessment; cyber risk target state.
The Internet-of-Things (IoT) triggers new types of cyber risks. Therefore, the integration of new IoT devices and services requires a self-assessment of IoT cyber security posture. By security posture this article refers to the cybersecurity strength of an organisation to predict, prevent and respond to cyberthreats. At present, there is a gap in the state-of-the-art, because there are no self-assessment methods for quantifying IoT cyber risk posture. To address this gap, an empirical analysis is performed of 12 cyber risk assessment approaches. The results and the main findings from the analysis is presented as the current and a target risk state for IoT systems, followed by conclusions and recommendations on a transformation roadmap, describing how IoT systems can achieve the target state with a new goal-oriented dependency model. By target state, we refer to the cyber security target that matches the generic security requirements of an organisation. The research paper studies and adapts four alternatives for IoT risk assessment and identifies the goal-oriented dependency modelling as a dominant approach among the risk assessment models studied. The new goal-oriented dependency model in this article enables the assessment of uncontrollable risk states in complex IoT systems and can be used for a quantitative self-assessment of IoT cyber risk posture.
GNSS RUMS: GNSS Realistic Urban Multi-agent Simulator for Collaborative Positioning Research
Guohao Zhang, Bing Xu, Hoi-Fung Ng, Li-Ta Hsu
Subject: Engineering, Automotive Engineering Keywords: global navigation satellite system (GNSS); simulator; collaborative positioning; Vehicle-to-everything (V2X); 3D building model; urban canyon
Accurate localization of road agents is the basis of intelligent transportation systems, which is still difficult to achieve for GNSS positioning in urban areas due to the signal interferences from buildings. Various collaborative positioning techniques are recently developed to improve the positioning performance by the aid from neighboring agents. However, it is still challenging to study their performances comprehensively. The GNSS measurement error behavior is complicated in urban areas and unable to be represented by naive models. On the other hand, real experiment requiring numbers of devices is hard to be conducted, especially for a large-scale test. Therefore, a GNSS realistic urban measurement simulator is developed to provide measurements for collaborative positioning studies. The proposed simulator employs a ray-tracing technique searching for all possible interferences in the urban area. Then, it categorizes them into direct, reflected, diffracted, and multipath signal to simulate the pseudorange, carrier-phase, 〖C/N〗_0, and Doppler shift measurements correspondingly. The performance of the proposed simulator is validated through real experimental comparisons with different scenarios. The proposed simulator is also applied with different positioning algorithms, which verifies it is sophisticated enough for the collaborative positioning studies in the urban area.
Apply VGGNet-Based Deep Learning Model of Vibration Data for Prediction Model of Gravity Acceleration Equipment
SeonWoo Lee, HyeonTak Yu, HoJun Yang, InSeo Song, JaeHeung Yang, GangMin Lim, KyuSung Kim, ByeongKeun Choi, JangWoo Kwon
Subject: Engineering, Automotive Engineering Keywords: artificial intelligence, deep learning, classification model, hyper-gravity machine, vibration monitoring
Hypergravity accelerators are a type of large machinery used for gravity training or medical research. A failure of such large equipment can be a serious problem in terms of safety or costs. This paper proposes a prediction model that can proactively prevent failures that may occur in a hy-pergravity accelerator. The method proposed in this paper was to convert vibration signals to spectograms and perform classification training using a deep learning model. An experiment was conducted to evaluate the performance of the method proposed in this paper. A 4-channel accel-erometer was attached to the bearing housing, which is a rotor, and time-amplitude data were obtained from the measured values by sampling. The data were converted to a two-dimensional spectrogram, and classification training was performed using a deep learning model for four conditions of the equipment: Unbalance, Misalignment, Shaft Rubbing, and Normal. The ex-perimental results showed that the proposed method had a 99.5% F1-Score, which was up to 23% higher than the 76.25% for existing feature-based learning models.
Mitigation of Gaseous Emissions from Stored Swine Manure with Biochar: Effect of Dose and Reapplication on A Pilot-Scale
Baitong Chen, Jacek A. Koziel, Chumki Banik, Hantian Ma, Myeongseong Lee, Samuel C. O'Brien, Peiyang Li, Daniel S. Andersen, Andrzej Białowiec, Robert C. Brown
Subject: Engineering, Civil Engineering Keywords: livestock manure; waste management; air pollution; air quality; biocoal; odor emission
The rural communities are affected by gaseous emissions from intensive livestock production. Practical mitigation technologies are needed to minimize emissions from stored manure and improve air quality inside barns. In our previous research, the one-time surficial application of biochar to swine manure significantly reduced emissions of NH3 and phenol. We observed that the mitigation effect decreased with time during the 30-day trials. In this research, we hypothe-sized that bi-weekly reapplication of biochar could improve the mitigation effect on a wider range of odorous compounds using larger scale and longer trials. The objective was to evaluate the effectiveness of biochar dose and reapplication on mitigation of targeted gases (NH3, odor-ous VOCs, odor, GHGs) from stored swine manure on a pilot-scale setup over 8-weeks. The bi-weekly reapplication of the lower biochar dose (2 kg/m2) showed much higher significant percent reductions of emissions for NH3 (33% without & 53% with reapplication) and skatole (42% without & 80% with reapplication), respectively. In addition, the reapplication resulted in the emergence of statistical significance to the mitigation effect for all other targeted VOCs. Spe-cifically, for indole, the % reduction improved from 38% (p=0.47, without reapplication) to 78% (p=0.018, with reapplication). For phenol, the % reduction improved from 28% (p=0.71, without reapplication) to 89% (p=0.005, with reapplication). For p-cresol, the % reduction improved from 31% (p=0.86, without reapplication) to 74% (p=0.028, with reapplication). For 4-ethyl phenol, the percent emissions reduction improved from 66% (p=0.44, without reapplication) to 87% (p=0.007, with reapplication). The one-time 2 kg/m2 and 4 kg/m2 treatments showed similar effectiveness in mitigating all targeted gases, and no statistical difference was found between the dosages. The one-time treatments showed significant % reductions of 33% & 42% and 25% & 48% for NH3 and skatole, respectively. The practical significance is that the higher (one-time) biochar dose may not necessarily result in improved performance over the 8-week manure storage, but the bi-weekly reapplication showed significant improvement in mitigating NH3 and odorous VOCs. The lower dosages and the frequency of reapplication on the larger-scale should be explored to optimize biochar treatment and bring it closer to on-farm trials.
Kinetic and Isotherm Studies of Sewage Sludge Biochar on Ammonium Solution
Khairunissa Syairah Ahmad Sohaimi, Ong Chyh Shyang, Nur Izzati Iberahim, Alina Rahayu Mohamed, Noor Ainee Zainol
Subject: Engineering, Biomedical & Chemical Engineering Keywords: ammonium; adsorption; sewage sludge; kinetic; isotherm
Sewage sludge was utilized into biochar using the slow pyrolysis method. The biochar was then being used for ammonium removal. The sewage sludge biochar was produced at temperature of 550°C, 600°C, 650°C, 700°C and 750°C. A few characterization tests were carried out to study about the physical and chemical properties of the biochar. For instance, moisture and ash content analysis, FTIR spectroscopy, pH Zero Point Charge, biochar yield and SEM. As the pyrolysis temperature increased, the moisture content of SSB decreased while the ash content increased. The FTIR spectra of sewage sludge biochar showed that there were various organic functional groups on the surface of the biochar which were responsible for ammonium adsorption. Furthermore, through pH Zero Point Charge analysis, pH 7.0 was the most optimum pH for the adsorption test of ammonium. The optimum adsorbent dosage was 0.01g while optimum contact time was 150 minutes. Furthermore, 1.2ppm was the most optimum concentration for adsorption process. Based on the result of the characterization tests, SSB700 was the most effective biochar for ammonium adsorption. Based on the result of kinetic and isotherm analysis, the adsorption of ammonium ions usign sewage sludge biochar was a monolayer chemisorption process.
Cyber Risk at the Edge: Current and future trends on Cyber Risk Analytics and Artificial Intelligence in the Industrial Internet of Things and Industry 4.0 Supply Chains
Petar Radanliev, David De Roure, Kevin Page, Jason R.C. Nurse, Rafael Mantilla Montalvo, Omar Santos, La'Treall Maddox, Peter Burnap
Subject: Engineering, Automotive Engineering Keywords: Industry 4.0; Supply Chain Design; Transformational Design Roadmap; IIoT Supply Chain Model; Decision Support for Information Management
Digital technologies have changed the way supply chain operations are structured. In this article, we conduct systematic syntheses of literature on the impact of new technologies on supply chains and the related cyber risks. A taxonomic/cladistic approach is used for the evaluations of progress in the area of supply chain integration in the Industrial Internet of Things and Industry 4.0, with a specific focus on the mitigation of cyber risks. An analytical framework is presented, based on a critical assessment with respect to issues related to new types of cyber risk and the integration of supply chains with new technologies. This paper identifies a dynamic and self-adapting supply chain system supported with Artificial Intelligence and Machine Learning (AI/ML) and real-time intelligence for predictive cyber risk analytics. The system is integrated into a cognition engine that enables predictive cyber risk analytics with real-time intelligence from IoT networks at the edge. This enhances capacities and assist in the creation of a comprehensive understanding of the opportunities and threats that arise when edge computing nodes are deployed, and when AI/ML technologies are migrated to the periphery of IoT networks.
An Adaptive and Resilient Islanding Approach for Power System Considering Secondary Collapses
Sanaullah Kaka, Mingchao Xia, Mazhar Hussain, Ali Raza Meer, Shubash Kumar
Subject: Engineering, Automotive Engineering Keywords: Adaptive Island; Minimum spanning tree; Load forecasting; Controllable switches; Distributed generations
The power system vulnerability leads to faults and the severity of the fault may lead to prolonged load-shedding. The power system needs to be configured in extreme failure scenarios for protecting the network from further contingencies and prolonged load-shedding. Distributed generation resources (DGs) can be useful to form intentional islands after faults to maintain the continuity of power supply to loads based on their weightage during faulty periods and to reduce overall load shedding duration. Power system is bound to collapses and secondary collapse in the formed island is possible. This research represents a novel method of impedance based path finding for intentional islanding, which adapts itself with the changes in the demands, DGs outputs or further severities during restoration period. In this adaptive islanding approach, network adjusts itself with the changes in either the load demands or renewable DGs outputs and rearranges the restoration plan by curtailing or adding some of the loads through controllable switches. Further a secondary collapse in the existing island is studied by injecting multiple faults at various positions of the network to validate the system resilience to cope with severities. A short-term load forecasting approach is used to predict changes in load demands and variations in DG outputs during the islanding scheme. During the restoration period, these variations are tracked and the islands are modified accordingly. In order to minimize the overall generation cost by using less fuel, an economical approach is used in the selection of controllable DGs. The proposed approach is formulated as a multi-objective, that incorporates several operational constraints and simulation is carried out using the modified IEEE 69-bus distribution system to assess the efficacy of the proposed model.
Design and Testing of Mobile Laboratory for Mitigation of Gaseous Emissions from Livestock Agriculture with Photocatalysis
Myeongseong Lee, Jacek A. Koziel, Wyatt Murphy, William Jenks, Blake Fonken, Ryan Storjohann, Baitong Chen, Peiyang Li, Chumki Banik, Landon Wahe, Heekwon Ahn
Subject: Engineering, Civil Engineering Keywords: air pollution control; air quality; environmental technology; advanced oxidation; odor; volatile organic compounds
Livestock production systems generate nuisance odor and gaseous emissions affecting local communities and regional air quality. Also, there are concerns about the occupational health and safety of farm workers. Proven mitigation technologies that are consistent with the socio-economic challenges of animal farming are needed. We have been scaling up the photocatalytic treatment of emissions from lab-scale, aiming at farm-scale readiness. In this paper, we present the design, testing, and commissioning of a mobile laboratory for on-farm research and demonstration of performance in real farm conditions. The mobile lab is capable of treating up to 1.2 m3·s-1 of air with TiO2-based photocatalysis and adjustable UV-A dose based on LED lamps. We summarize the main technical requirements, constraints, approach, and performance metrics for the mobile laboratory, such as the effectiveness (measured as the percent reduction) and cost of photocatalytic treatment of air. The commissioning of all systems with standard gases resulted in ~9% and 34% reduction of NH3 and butan-1-ol, respectively. We demonstrated that as the percent reduction of standard gases increased with increased light intensity and treatment time. These results show that the mobile laboratory was ready for on-farm deployment and evaluating the effectiveness of UV treatment.
Towards Bengali Word Embedding: Corpus Creation, Intrinsic and Extrinsic Evaluations
Md. Rajib Hossain, Mohammed Moshiul Hoque
Subject: Engineering, Automotive Engineering Keywords: Natural language processing; Extrinsic evaluation; Intrinsic evaluation; Word analogy; Word embedding
Distributional word vector representation orword embedding has become an essential ingredient in many natural language processing (NLP) tasks such as machine translation, document classification, information retrieval andquestion answering. Investigation of embedding model helps to reduce the feature space and improves textual semantic as well as syntactic relations.This paper presents three embedding techniques (such as Word2Vec, GloVe, and FastText) with different hyperparameters implemented on a Bengali corpusconsists of180 million words. The performance of the embedding techniques is evaluated with extrinsic and intrinsic ways. Extrinsic performance evaluated by text classification, which achieved a maximum of 96.48% accuracy. Intrinsic performance evaluatedby word similarity (e.g., semantic, syntactic and relatedness) and analogy tasks. The maximum Pearson (ˆr) correlation accuracy of 60.66% (Ssˆr) achieved for semantic similarities and 71.64% (Syˆr) for syntactic similarities whereas the relatedness obtained 79.80% (Rsˆr). The semantic word analogy tasks achieved 44.00% of accuracy while syntactic word analogy tasks obtained 36.00%
Petar Radanliev, David De Roure, Kevin Page, Jason R.C. Nurse, Rafael Mantilla Montalvo, Omar Santos, La'Treall Maddox, Pete Burnap
Subject: Engineering, Automotive Engineering Keywords: Industry 4.0; Supply Chain Design; Transformational Design Roadmap; IIoT Supply Chain Model; Decision Support for Information Management, Artificial Intelligence and Machine Learning (AI/ML), dynamic self-adapting system, cognition engine, predictive cyber risk analytics.
Panchromatic Image Super-Resolution via Self Attention-augmented WGAN
Juan Du, Kuanhong Cheng, Yue Yu, Dabao Wang, Huixin Zhou
Subject: Engineering, Automotive Engineering Keywords: Super Resolution; Attention-augmented Convolution; Panchromatic Images; WGAN
Panchromatic (PAN) images contain abundant spatial information that is useful for earth observation, but always suffer from low-resolution due to the sensor limitation and large-scale view field. The current super-resolution (SR) methods based on traditional attention mechanism have shown remarkable advantages but remain imperfect to reconstruct the edge details of SR images. To address this problem, an improved super-resolution model which involves the self-attention augmented WGAN is designed to dig out the reference information among multiple features for detail enhancement. We use an encoder-decoder network followed by a fully convolutional network (FCN) as the backbone to extract multi-scale features and reconstruct the HR results. To exploit the relevance between multi-layer feature maps, we first integrate a convolutional block attention module (CBAM) into each skip-connection of the encoder-decoder subnet, generating weighted maps to enhance both channel-wise and spatial-wise feature representation automatically. Besides, considering that the HR results and LR inputs are highly similar in structure, yet cannot be fully reflected in traditional attention mechanism, we therefore design a self augmented attention (SAA) module, where the attention weights are produced dynamically via a similarity function between hidden features, this design allows the network to flexibly adjust the fraction relevance among multi-layer features and keep the long-range inter information, which is helpful to preserve details. In addition, the pixel-wise loss is combined with perceptual and gradient loss to achieve comprehensive supervision. Experiments on benchmark datasets demonstrate that the proposed method outperforms other SR methods in terms of both objective evaluation and visual effect.
Comparing Statistical and Neural Machine Translation Performance on Hindi-to-Tamil and English-to-Tamil
Akshai Ramesh, Venkatesh Balavadhani Parthasarathy, Andy Way, Rejwanul Haque
Subject: Engineering, Automotive Engineering Keywords: Machine Translation; Statistical Machine Translation; Neural Machine Translation; Terminology Translation; Low-resource Machine Translation; Byte-Pair Encoding
Statistical machine translation (SMT) which was the dominant paradigm in machine translation (MT) research for nearly three decades has recently been superseded by the end-to-end deep learning approaches to MT. Although deep neural models produce state-of-the-art results in many translation tasks, they are found to under-perform on resource-poor scenarios. Despite some success, none of the present-day benchmarks that have tried to overcome this problem can be regarded as a universal solution to the problem of translation of many low-resource languages. In this work, we investigate the performance of phrase-based SMT (PB-SMT) and NMT on two rarely-tested low-resource language-pairs, English-to-Tamil and Hindi-to-Tamil, taking a specialised data domain (software localisation) into consideration. This paper demonstrates our findings including the identification of several issues of the current neural approaches to low-resource domain-specific text translation and rankings of our MT systems via a social media platform-based human evaluation scheme.
An Adaptive Controller for DSTATCOM for Power Quality Improvement in Distribution System
Atma Ram, Parsh Ram Sharma, Rajesh Kumar Ahuja
Subject: Engineering, Electrical & Electronic Engineering Keywords: Linear/nonlinear load; power quality; four leg VSC; neutral current compensation
An adaptive control technique has been implemented for DSTATCOM for power quality enhancement in three phase four wires(3P4W) distribution system. The reference source currents are extracted from active components of load current for each phase by using this technique. It has also been used for load balancing, harmonic suppression, power factor improvement and reactive power compensation in distribution system. The adaptive control technique has been tested at varying load in steady state and dynamic conditions. This technique is developed using MATLAB/Simulink and source side harmonics are mitigated under different load conditions which are acceptable in accordance with IEEE standard.
An Experimental Study of the Acetic Acid Steam Reforming Over Co-Based Catalysts
Marta Cortese, Concetta Ruocco, Vincenzo Palma, Pedro Mejia, Alicia Carrero, José Antonio Calles
Subject: Engineering, Automotive Engineering Keywords: acetic acid; reforming; hydrogen; cobalt; ceria
This work focuses on the support effect on the performances of Co-based catalysts for the acetic acid steam reforming. SBA-15, a well ordered hexagonal mesoporous silica structure, and CeO2 have been selected as the supports, with the impact of chromium addition also being investigated. Better acetic acid steam reforming performances have been recorded for CeO2 compared to SBA-15 supported catalysts and, in particular, the 7Co/CeO2 catalyst showed the highest values of acetic acid conversions with enhanced H2 yields below 480°C, in comparison to the other investigated catalytic formulations. In addition, more pronounced coke depositions and acetone concentrations have been obtained with CeO2 supported catalysts, due to the tendency of ceria to catalyse the ketonization reaction. Chromium addition to Co/SBA-15 catalysts led to an enhancement in the activity towards acetic acid steam reforming, while on CeO2 supported catalysts no improvement in the catalysts activity was observed; however, on both SBA-15 and CeO2 supported catalysts, Cr addition reduced the amount of coke deposited on the catalysts surface.
Effect of Design on the Evacuation Time for Large Arenas of Different Epochs
Marina Gravit, Ekaterina Kirik, Egor Savchenko, Tatyana Vitova
Subject: Engineering, Civil Engineering Keywords: arena; design; evacuation time; fire safety; computer simulation
The designs of two large arenas of different epochs are discussed, which are the most famous antique amphitheater the Roman Colosseum (Italy) and the modern Gazprom Arena stadium (St. Petersburg, Russia). 3D-computer models of the arenas have been built and evacuation of people has been simulated in the Sigma FS software (Russia). The arena designs are analyzed in terms of organizing pedestrian evacuation, a comparative analysis is made, and the specific characteristics affecting the evacuation time are established.
Development of a Technology of Isothermal Annealing With the Use of the Forging Heat for Chromium-Molybdenum Steel
Artur Barełkowski, Roman Kuziak
Subject: Engineering, Automotive Engineering Keywords: die forging; isothermal annealing; thermo-mechanical treatment
The article discusses the results of investigations performed during a thermo-mechanical treatment of forgings made of chromium-molybdenum 42CrMo4 grade steel. The treatment was realized during a regular series production. The forging process was combined with a heat treatment carried out directly after forging on a specially adapted station. Such a production technology will make it possible to eliminate the step of repeated heating of the forgings. On the example of an element of a steering gear, it was demonstrated how it is possible to perform an isothermal annealing process starting from the temperature at which the trimming of the forgings ends. During the cooling of the forgings, it is enough to maintain the temperature at the proper level in order for the exothermal phase transformation of austenite into pearlite to take place. With an appropriate design of the processing line, the heat released during the transformation could be used to maintain the applied temperature, thus limiting the consumption of energy needed to power the devices. The test results show that, with the properly selected temperature of isothermal annealing, it is possible to obtain an equilibrial ferritic-pearlitic structure in the required hardness scope. Introducing such a solution into the industrial practice would allow significant savings of the energy used for the heat treatment.
The Effect of Ni-Modified LSFCO Promoting Layer on the Gas Produced Through Co-Electrolysis of CO2 and H2O at Intermediate Temperatures
Massimiliano Lo Faro, Sabrina Campagna Zignani, Vincenzo Antonucci, Antonino Salvatore Aricò
Subject: Engineering, Automotive Engineering Keywords: valorization of CO2; solid oxide electrochemical cells; green methane; energy storage; power-to-gas
The co-electrolysis of CO2 and H2O at intermediate temperature is a viable approach for the power-to-gas conversion that deserves for further investigation, considering the need for green energy storage. The commercial solid oxide electrolyser is a promising device, but it is still facing to solve issues concerning the high operating temperatures and the improvement of gas value. In this paper we reported the recent findings of a simple approach that we have amply suggested for solid oxide cells consisting in the addition of a functional layer coated to the fuel electrode of commercial electrochemical cells. This approach simplifies the transition to the next generation of cells manufactured with the most promising materials currently developed and improves the gas value in the outlet stream of cell. Here, the material in use as a coating layer consisted of a Ni-modified La0.6Sr0.4Fe0.8Co0.2O3 which was developed and demonstrated as promising fuel electrode for solid oxide fuel cells. The results discussed in this paper proved the positive role of Ni-modified perovskite as a coating layer for the cathode, since an improvement of about twice was obtained about the quality of gas produced.
Visual Cortical Prosthesis : An Electrical Perspective
Léo Pio-Lopez, Romanos Poulkouras, Damien Depannemaecker
Subject: Engineering, Biomedical & Chemical Engineering Keywords: visual cortical prosthesis; brain-machine interface; electrical stimulation; prosthetic vision
The electrical stimulation of the visual cortices has the potential to restore vision to blind individuals. Until now, the results of visual cortical prosthetics has been limited as no prosthesis has restored a full working vision but the field has shown a renewed interest these last years thanks to wireless and technological advances. However, several scientific and technical challenges are still open in order to achieve the therapeutic benefit expected by these new devices. One of the main challenges is the electrical stimulation of the brain itself. In this review, we analyze the results in electrode-based visual cortical prosthetics from the electrical point of view. We first briefly describe what is known about the electrode-tissue interface and safety of electrical stimulation. Then we focus on the psychophysics of prosthetic vision and the state-of-the-art on the interplay between the electrical stimulation of the visual cortex and phosphene perception. Lastly, we discuss the challenges and perspectives of visual cortex electrical stimulation and electrode array design to develop the new generation implantable cortical visual prostheses.
A Novel Piezoelectric Ultrasonic Biological Micro-Dissection Device Based on Flexure Mechanism for Suppressing Vibration
Haibo Huang, Yifan Pan, Yan Pang, Hao Shen, Xiwei Gao, Yichen Zhu, Liguo Chen, Lining Sun
Subject: Engineering, Automotive Engineering Keywords: Micro-dissection; Ultrasonic vibration; Flexure-guided; Tissue section
Biological micro-dissection has a wide range of applications in the field of molecular pathology. The current laser-assisted dissection technology is expensive, and laser radiation can lead to sample contamination. As an economical and pollution-free micro-dissection method, piezoelectric ultrasonic micro-dissection has a wide application prospect. However, the performance of the current piezoelectric ultrasonic micro-dissection technology is unsatisfactory. In this paper, a novel piezoelectric ultrasonic micro-dissection device based on a flexure mechanism is proposed in order to solve the problems of low dissecting precision and excessive wear of the dissecting needle caused by the harmful lateral vibration of the current piezoelectric ultrasonic micro-dissection device. By analyzing the flexibility of flexure hinge, the type of flexure beam and the optimal design parameters are determined. Through comparing the harmonic response simulation analysis of the micro-dissection device based on a flexure mechanism and the traditional micro-dissection device without the flexure mechanism, the newly designed micro-dissection device achieves the best vibration effect when the driving frequency is 28kHz, compared with the traditional micro-dissection device, the lateral vibration suppression effect is improved by 68%. Then, based on the 3D printing technology, a prototype of a novel micro-dissection device was produced, and its performance was tested. It was found that the flexure mechanism did indeed suppress the lateral vibration of the needle tip. Finally, the experiments of 5μm thick paraffin-embedded rat liver sections were carried out, and the effects of different dissecting parameters on the dissecting effect were analyzed, and the optimal dissecting parameters were obtained. By comparing the dissecting effects of the tissue sample and the wear condition of the needle tip between the novel micro-dissection device and the traditional micro-dissection device under their optimal dissecting parameters, it is proved that the suppression of harmful lateral vibration not only significantly improves the dissecting effect, but also improves the service life and durability of the dissecting needle, which is beneficial to reduce the equipment costs.
Tensile Fatigue Behaviour of Polyester and Vinyl Ester Based Gfrp Laminates – a Comparative Evaluation
Wahid Ferdous, Allan Manalo, Peng Yu, Choman Salih, Rajab Abousnina, Tom Heyer, Peter Schubel
Subject: Engineering, Automotive Engineering Keywords: Fatigue; fibre composites; polyester and vinyl ester resins; stress ratio; fatigue model.
Fatigue loading is critical to fibre reinforced polymer composites due to their anisotropic and heterogenous nature. This study investigated the tensile fatigue behaviour of polyester and vinyl ester based GFRP laminates to understand the critical aspects of failure mode and fatigue life under cyclic loading. GFRP laminates with two different resin systems (polyester and vinyl ester), two different stress ratios (0.1 and 0.5) and two different environmental conditions (air and water) were investigated at an applied stress of 80%, 60% and 40% of the ultimate capacity. Based on the investigated parameters (i.e., resin types, stress ratio, environmental conditioning and maximum applied stress), a fatigue model was proposed. Results show that the resin system plays a great role in fatigue failure mode while the stress ratio and environmental condition significantly affect the tensile fatigue life of GFRP laminates. The types of resin used in GFRP laminates and environmental conditions as input parameter in the proposed fatigue model is a unique contribution.
A Simple and Cheap Aerosol Penetrometer for Filter Testing Using an Electronic Cigarette
Sebastian Lifka, Ivan Ponomarev, Agnes Weth, David Baumgartner, Bernd Lamprecht, Werner Baumgartner
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Filter; face masks; penetrometer; electronic cigarette; COVID-19; light scattering detector
During the COVID-19 pandemic face masks grew in importance as their use by the general population was recommended by health officials in order to minimize the risk of infection and prevent further spread of the virus. To ensure health protection of medical personal and other system relevant staff, it is of considerable interest to quickly test if a certain lot of filtering facepiece masks meets the requirements or if the permeability changes under different conditions. As certified penetrometers are rather expensive and were difficult to obtain during the COVID-19 pandemic, we describe two quite simple and cheap methods to quickly test the filter permeability based on an electronic cigarette. The first method uses a precision scale, the second method uses a light scattering detector to measure the filter penetration. To make sure these two methods yield reliable results, both were tested with freshly cut filter samples covering the range of approx. 7% to 60% permeability and compared to the results of a certified penetrometer. The comparison of the two methods with the certified penetrometer showed a good correlation and therefore allow a quick and rather reliable estimation of the permeability. Several examples about the use of faulty masks and the resulting health risks show that simple, fast, cheap and broadly available methods for filter characterization might be useful in these days.
Offshore Wind Energy Potential for Bahrain via Multi-criteria Evaluation
Diane Palmer, Mohamed Elgabiri, Hanan Al Buflasa, Murray Thomson
Subject: Engineering, Energy & Fuel Technology Keywords: Offshore wind farm siting; Suitability maps; Geographical Information Systems (GIS); Multi-criteria; Analytic hierarchy process (AHP); Offshore wind energy potential.
Current global commitments to reduce emissions of greenhouse gases encourage national targets for renewable generation. Due to its small land mass, offshore wind could help Bahrain to fulfill its obligations. However, no scoping study has yet been carried out. The methodology presented here addresses this research need. It employs Analytical Hierarchy Process and pairwise comparison methods in a Geographical Information Systems environment. Publicly available land use, infrastructure and transport data are used to exclude areas unsuitable for development due to physical and safety constraints. Meteorological and oceanic opportunities are ranked, then competing uses are analyzed to deliver optimal sites for wind farms. The potential annual wind energy yield is calculated by dividing the sum of optimal areas by a suitable turbine footprint, to deliver maximum turbine number. Ten favourable wind farm areas were identified in Bahrain's territorial waters, representing about 4% of the total maritime area, and capable of supplying 2.68 TWh/yr of wind energy or almost 10% of the Kingdom's annual electricity consumption. Detailed maps of potential sites for offshore wind construction are provided in the paper, giving an initial plan for installation in these locations.
Autonomous Vision-Based Primary Distribution Systems Porcelain Insulators Inspection Using UAVs
Ehab Ur Rahman, Yihong Zhang, Sohail Ahmad, Hafiz Ishfaq Ahmad, Sayed Jobaer
Subject: Engineering, Automotive Engineering Keywords: Primary distribution systems; Transfer learning; YoloV4; Porcelain Insulator detection; UAVs; BRISQUE; LIME; LapSRN; YoloV5
The primary distribution systems are comprised of power lines delivering power to utility feeders from substations. The inspection and maintenance of damaged and broken power system insulators are of paramount importance for continuous power supply and public safety. hence, to identify any faults and defects in advance a periodic inspection of power line insulators and other components be ensured beforehand. To automate the process and reduce operational cost and risk Unmanned Aerial Vehicles (UAVs) are being extensively utilized. As they present a safer and efficient way to examine the power system insulators and their components without closing the power distribution system ensuring continuous supply to the end-users. To achieve these objectives in this work a novel dataset is designed by capturing real images using UAVs and manually generated images collected to overcome the data insufficiency problem. Deep Laplacian pyramids based super-resolution network is implemented to reconstruct high-resolution training images. To improve the visibility of low light images a low light image enhancement technique is used for the robust exposure correction of the training images. Using computer vision-based object detection techniques to identify faults and classify them according to classes they belong. A different fine-tuning strategy is implemented for fine-tuning the object detection model to increase detection accuracy for the specific faulty insulators. To improve the faults detection several flight path strategies are proposed for efficient inspection. Such strategies overcome the shuttering effect of insulators along with providing a less complex, time, and energy-efficient approach for capturing video stream of the power system components. Performance of different object detection models is presented for selecting the suitable one for fine-tuning on the specific faulty insulator dataset. Our proposed approach gives a less complex and more efficient flight strategy along with better results. For defect detection, our proposed method achieved an F1-score of 0.81 and 0.77 on two different datasets. Our approach is based on real aerial inspection of in-service porcelain insulators by extensive evaluation of several video sequences showing robust faults recognition and diagnostic capabilities. Our approach is demonstrated on data acquired by a drone in Swat Pakistan.
Kinetic and Isotherm Studies Biochar on Ammonium Solution
Khairunissa Syairah Ahmad Sohaimi, Ong Chyh Shyang, Nur Izzati Iberahim, Alina Rahayu Mohamed
Subject: Engineering, Automotive Engineering Keywords: ammonium; adsorption; sewage sludge; kinetic; isotherm
Analyses and Optimization Methods of Legged Robots: A Review
Venkata Sainaveen Nandam, Praveen Seelaboyina, Sandeep Chowdary Kodavati, Harikrishna Molleti
Subject: Engineering, Automotive Engineering Keywords: legged robots; optimization; kinematic analysis; compliant Joints 6049816627759
During the most recent years, a lot of research has been done in creating robots with more self-governance so that they can overcome the challenges that real world environments present. The robot's limited versatility in real world applications can be overcome by the development of Legged robots. Also, as they permit movement in unavailable territory to robots with wheels, Legged Robots are more advantageous. But the potency of the legged robots explicitly its energy usage among alternate points of view really fall behind robots that use wheels. So, the present status of development, there are as yet a few perspectives that need to be analysed, optimized and enhanced. This paper presents review of literature of various biologically inspired legged robots, various techniques adopted for their analysis and optimization and the analysis and optimization of the ones that are not biologically inspired
Life Cycle Assessment of Hot Mix Asphalt Production with Reclaimed Asphalt Pavement in Washington State
Milad Zokaei Ashtiani
Subject: Engineering, Automotive Engineering Keywords: lifecycle assessment; LCA; hot mix asphalt; reclaimed asphalt pavement; rehabilitation
This study is an attempt to create a framework, using the best available inventory data, to perform lifecycle assessment (LCA) on asphalt pavement production. In particular, the use of reclaimed asphalt pavement (RAP) as an end-of-life product of deteriorated pavements is under consideration. Following ISO 14000 series standards, the framework constitutes the four major LCA steps in defining goal and scope, lifecycle inventory analysis, environmental impact assessment, and results interpretation. Three different scenarios in which varying portions of RAP are incorporated into hot mix asphalt production are to be compared. The system boundary of this study is limited to the construction and rehabilitation phases and ignores the vehicular use phase. It was found under this study that since high RAP mixtures require more frequent and aggressive maintenance activities, the overall footprint of asphalt pavements constructed with higher RAP contents is also higher. This would necessitate more efficient design procedures and protocols for mixtures produced with high RAP contents to compensate for their lack of long-term performance.
Design and Analysis of a Mechanical Ventilation System Based on Cams
Jesús Calderón, Carlos Rincón, Bray Agreda, Juan José Jiménez
Subject: Engineering, Automotive Engineering Keywords: mechanical ventilation design; low cost mechanical ventilator; experimental ventilation curves; mechanical ventilation mathematical model; COVID-19
A mechanical ventilation system is a big support for breathing complications, in which an external solution is quite necessary to keep oxygen compensation in the patients. Its knowledge is well widespread and different equipment has been developed. However, they are very expensive and their quantity in medical centers is not sufficient, especially in Peru. Hence, it has been required to develop new methods to provide oxygen by a low cost equipment; Protofy, a research group from Spain, designed one of the first low cost mechanical ventilation systems which was medically validated by its government. In this sense, a redesign of the mechanical ventilation system was carried out according to the local requirements and available technology, a different airbag resuscitator with different properties and geometry, but maintaining its working concept based on a cam compression mechanism. Sensors and a display were added to improve the performance with a control algorithm for the rotation frequency and to show the ventilation curves over time to the medical staff. It was necessary to develop a mathematical model to relate the behavior between ventilation curves for a patient and physical variables of the design, especially in the epidemic COVID 19, that many countries are dealing with at the time research is being conducted. The mechanical ventilation system was redesigned, fabricated, and tested measuring its ventilation curves over time. Results indicate that this redesign provides a sturdy equipment able to work during a longer lifetime than the original. The replicability of the ventilation curves behavior is assured, while the mechanism dimensions are adapted for a particular airbag resuscitator. The mathematical model of the whole system can predict satisfactorily the ventilation curves over time and was used to provide the air pressure, volume, and flow as a function of the rotation angle measured by sensors.
Challenges in Incorporating Electric Vehicles to Mitigate Greenhouse Gas Emissions
Subject: Engineering, Automotive Engineering Keywords: Electric Vehicles; Greenhouse Gas; Climate Change; Transportation; Energy; Renewables; Lifecycle Assessment; Electricity Grid
An indisputable fact about our planet is that its atmospheric temperature has risen dramatically during the past century. Combustion of fossil fuels and their subsequent greenhouse gas emissions are thought to be the main contributors to recent changes within the Earth's ecosystem. The transportation sector and electricity generating power plants are each responsible for approximately one-third of these emissions. Shifting towards a cleaner and renewable resources to generate electricity is believed to omit a big portion of polluting substances. Improvements in vehicles' fuel efficiency and the introduction of alternative fuels besides strategic plans to control travel demand are among the most promising approaches to alleviate emissions from the transportation sector. Recent technology advancements, however, drew much attention to the production and manufacturing of alternative fuel vehicles, electric vehicles in particular. Since these vehicles use electricity as part of or all their powertrain, assessing the amount of emissions they produce is closely tied to the cleanliness of the electricity source. In order for a valid comparison to be made between internal combustion and electric vehicles, hence, a life cycle assessment procedure needs to be followed from production stages to terminal life of vehicles. Involvement of numerous affecting factors during the lifetime of a vehicle on one hand, and the ambiguity in the exact source of electricity used to charge electric vehicles on the other hand bring about more complexities. The latter case is more commonly known as the marginal grid problem, which deals with how a combination of sources used to generate electricity can influence the life cycle emissions. There are also other concerns regarding the growth in fuel-efficient and electric vehicles. Transportation planners argue that new developments in the vehicle industry may attract more people to owning and driving cars. This phenomenon which is better known as a rebound effect not only will result in increased traffic congestion, but it can also outpace the environmental benefits from utilizing electric vehicles. Moreover, since fuel taxes comprise the majority of Highway Trust Funds, alternative ways to compensate for state and federal revenues should be devised. This paper is an attempt to review the existing literature to better elaborate on the role of the transportation sector in controlling climate change threats. More specifically, issues around the use of electric vehicles and how they can contribute to more environmentally friendly communities are discussed.
Time-Dependent Motion of a Floating Circular Elastic Plate
Michael Meylan
Subject: Engineering, Marine Engineering Keywords: Hydroelasticity; Floating Plate; Linear Water Waves
The motion of a circular elastic plate floating on the surface is investigated in the time–domain. The solution is found from the single frequency solutions and the method to solve for the circular plate is given using the eigenfunction matching method. Simple plane incident waves with a Gaussian profile in wavenumber space are considered and a more complex focused wave group is considered. Results are given for a range of plate and incident wave parameters are investigated. Code is provided to show how to simulate the complex motion.
PFDA- FMEA. An Integrated Method Improving FMEA Assessment in Product Design
Pedro Garcia, Luis Perez-Dominguez, David Luviano-Cruz, Jesus Jaime Solano Noriega, Erwing Martinez Gomez, Mauro Callejas-Cuervo
Subject: Engineering, Automotive Engineering Keywords: Product Design (PD); Failure Mode and Effect Analysis (FMEA); Dimensional Analysis (DA); Pythagorean Fuzzy Sets (PFS)
Product Design is getting nowadays new challenges on developing new products, since the industry is in a rush to introduce products into the marketplace, where customers demand products faster, cheaper, and free of failures. In the meantime, global companies are always trying to improve their Product Design process to get advantages over their competitors using proven tools like FEMA and mixing methodologies like Fuzzy theories with FMEA. Even today using all this tools and combination of methodologies there is a gap to address and it is required a robust risk analysis solving current issues in the electronic industry. This document aims to reveal a novel integrated method, where Failure Mode and Effect Analysis, Pythagorean Fuzzy Sets and Dimensional Analysis are cohesive into a model that minimize the uncertainty of the ranking and prioritization over the Failure Mode and Effect Analysis execution, helping to identify risks within an accurate grade over possible failures in the Product Design process. A real practical example is used to show the proposed method, where it is identified a robust methodology integration and solid and results using a sensitivity analysis.
Optimization of the Mix Formulation of Geopolymer using Nickel-laterite Mine Waste and Coal Fly Ash
Alberto Jr Longos, April Anne Tigue, Ithan Jessemar Dollente, Roy Alvin Malenab, Ivyleen Bernardo-Arugay, Hirofumi Hinode, Winarto Kurniawan, Michael Angelo Promentilla
Subject: Engineering, Construction Keywords: geopolymer; laterite; alkali-activated; alumino-silicates; I-optimal; response surface methodology; optimization; mine waste.
Geopolymer cement has been popularly studied nowadays compared to ordinary Portland cement because it demonstrated superior environmental advantages due to its lower carbon emissions and waste material utilization. This paper focuses on the formulation of geopolymer cement from nickel-laterite mine waste (NMW) and coal fly ash (CFA) as geopolymer precursors, and sodium hydroxide (SH) and sodium silicate (SS) as alkali activators. Different mix formulations of raw materials are synthesized to produce a geopolymer based from an I-optimal design and obtained different compressive strengths. A mixed formulation of 50% NMW and 50% CFA, SH-to-SS ratio of 0.5, and an activator-to-precursor ratio of 0.429 yielded the highest 28-day unconfined compressive strength (UCS) of 22.10 ± 5.40 MPa. Furthermore, using an optimized formulation of 50.12% NMW, SH-to-SS ratio of 0.516, and an activator-to-precursor ratio of 0.428, a UCS value of 36.30 ± 3.60 MPa was obtained. The result implies that the synthesized geopolymer material can be potentially used for concrete structures and pavers, pedestrian pavers, light traffic pavers, and plain concrete.
Small Symmetrical Deformation of Thin Torus with Circular Cross-Section
Bohua Sun
Subject: Engineering, Automotive Engineering Keywords: toroidal shell; deformation; Gauss curvature; Heun function; hypergeometric function; Maple
By introducing a variable transformation $\xi=\frac{1}{2}(\sin \theta+1)$, a complex-form ordinary differential equation (ODE) for the small symmetrical deformation of an elastic torus is successfully transformed into the well-known Heun's ODE, whose exact solution is obtained in terms of Heun's functions. To overcome the computational difficulties of the complex-form ODE in dealing with boundary conditions, a real-form ODE system is proposed. A general code of numerical solution of the real-form ODE is written by using Maple. Some numerical studies are carried out and verified by finite element analysis. Our investigations show that the mechanics of an elastic torus are sensitive to the radius ratio, and suggest that the analysis of a torus should be done by using the bending theory of a shell. A general Maple code is provided as essential part of this paper.
Almost Global Stability of Nonlinear Switched System with Stable and Unstable Subsystems
Aysegul Kivilcim, Ozkan Karabacak, Rafal Wisniewski
Subject: Engineering, Automotive Engineering Keywords: switched systems, stable and unstable subsystems, Lyapunov density, average dwell time, mode-dependent average dwell time
This paper presents sufficient conditions for almost global stability of nonlinear switched systems consisting of both stable and unstable subsystems. Techniques from the stability analysis of switched systems have been combined with the multiple Lyapunov density approach - recently proposed by the authors for the almost global stability of nonlinear switched systems composed of stable subsystems. By using slow switching for stable subsystems and fast switching for unstable subsystems lower and upper bounds for mode-dependent average dwell times are obtained. In addition to that, by allowing each subsystem to perform slow switching and using some restrictions on total operation time of unstable subsystems and stable subsystems, we have obtained a lower bound for an average dwell time.