361 articles found
Effect of Modification in Flow Distributor Valve Geometry on the Pressure Drop and Chamber Pressures, in Numerical and Analytical Way, in ORBIT Motor HST Unit
Debanshu Roy, Amit Kumar , Rathindranath Maiti , Prasanta Kumar Das
Subject: Engineering, Mechanical Engineering Keywords: pintle type rotary spool valve; flow distributor valve; computational fluid dynamics (CFD); orbit motor
In this paper, an attempt has been made to analyze the effect of spool port/ groove geometry on the pressure drop and chamber pressures which effect the performance parameters of the flow distributor valve. The work mainly involves formulation of detailed mathematical model of the valve and compare them on the same platform. For mathematical modelling, Matlab has been used. The size of the orifices is considered same throughout the model for better comparison. Initially the construction and functioning of flow distributor valve along with working principles of hydrostatic motor (Rotary Piston) is shown. Next shown the analytical analysis of area change and pressure drops due to different geometry of the spool valve ports. After that the computational fluid dynamics (CFD) analysis has been shown. A complete mathematical model to describe such flow distributor valve is developed after having a comprehensive knowledge of orifice characteristics, flow interactions based on valve geometry. Equations of flow through different orifices (fixed and variable area) of the valve have been developed based on the relationships obtained earlier.
Research on The Controllable Interface Response Enhancement of The Textured Pilot Valve
Jing Xu, Guiming Zhang, Shaochao Fan, Jing Ni, Jiadi Lian
Subject: Engineering, Mechanical Engineering Keywords: pilot valve; texture; response; stress; flow field analysis
Based on the textured controllable interface effect, the dynamic performances of the textured and ordinary pilot valve are analyzed experimentally, and the influence of the textured controllable interface on the response of pilot valve is studied. Results show that when Pin is small, the textured surface shortens the reciprocating time of valve core, increasing the flow rate, and speeds up the piston stroke of oil cylinder. The valve core actions much more stable and sensitivity. Meanwhile, combined with the theoretical calculation, the operation mechanism of texturing the pilot valve is analyzed. It is concluded that the stress of textured valve core sealing surface is greater than that of ordinary one, and the pressure difference gradually decreases with the increase of Pin, and the flow difference is basically the same as the force on the sealing surface. This indicates that the textured surface improves lubrication characteristics, reduces the friction between components. The textured valve makes the velocity changes gently, and enhances the responsiveness and stability of the valve. Those related results provide a new idea for enhancing the response design of the pilot valve.
Possible Early Generation of Physiological Helical Flow Could Benefit the Triflo Trileaflet Heart Valve Prosthesis Compared to Bileaflet Valves
Ch. Bruecker, Qianhui Li
Subject: Life Sciences, Biochemistry Keywords: physiological helical flow; mechanical heart valve prostheses; aorta; PIV; trileaflet
Background - Physiological helical flow in the ascending aorta has been well documented in the last two decades, accompanied by discussions on possible physiological benefits of such axial swirl. Recent 4D-MRI studies on healthy volunteers have shown indication of early generation of helical flow, early in the systole and already close to the valve plane. Objectives - Firstly, the aim of the study is to investigate the hypothesis of premature swirl existence in the ventricular outflow tract leading to already helical flow in the valve plane, and second to investigate the possible impact of two different mechanical valves design on the preservation of this early helical flow and its subsequent hemodynamic consequences. Methods - We use a pulse duplicator with an aortic arch and High Speed Particle Image Velocimetry to document the flow evolution in the systolic cycle. The pulse-duplicator is modified with a swirl-generating insert to generate early helical flow in the valve plane. Special focus is laid on the interaction of such helical flow with different designs of mechanical prosthetic heart valves, comparing a classical bileaflet mechanical heart valve, the St Jude Medical Regent valve (SJM Regent BMHV) with the Triflo trileaflet mechanical heart valve T2B version (Triflo TMHV). Results – When the swirl-generator is inserted, a vortex is generated in the core flow demonstrating early helical flow in the valve plane, similar as observed in the recent 4-D-MRI study taken for comparison. For the Triflo trileaflet valve, the early helical flow is not obstructed in the central orifice, similar as in the case of the natural valve. Conservation of angular momentum leads to radial expansion of the core flow and flattening of the axial flow profile downstream in the arch. Furthermore, the early helical flow helps to overcome separation at the outer and inner curvature. In contrast, the two parallel leaflets for the bileaflet valve impose a flow straightener effect, annihilating the angular momentum with negative impact on kinetic energy of the flow. Conclusion - The results imply better hemodynamics for the Triflo trileaflet valve based on hydrodynamic arguments under the discussed hypothesis. In addition, it makes the Triflo valve a better candidate for replacements in patients with pathological generation of nonaxial velocity in ventricle outflow tract.
Flow Pattern and Pressure Drop for Oil-Water Flows in and around 180° Bends
Paul Onubi Ayegba, Lawrence C. Edomwonyi-Otu, Abdulkareem Abubakar, Nurudeen Yusuf
Subject: Keywords: U-bend; oil-water flow; flow pattern; pressure losses; flow redevelopment
Pressure drop and flow pattern of oil-water flows were investigated in a 19 mm ID clear polyvinyl chloride pipe consisting of U-bend with radius of curvature of 100 mm. The range for oil and water superficial velocities tested were and respectively. Measurements were carried out under different flow conditions in a test section that consisted of four different parts: upstream of the bend, at the bend and at two redeveloping flow locations after the bend. The result indicated that the bend had limited influence on downstream flow patterns. However, the shear forces imposed by the bend caused some shift flow pattern transition and bubble characteristics in the redeveloping flow section after the bend relative to develop flow before the bend. Generally, pressure gradient at all the test sections increased with both oil fraction and water superficial velocity and there was a sharp change of pressure gradient profile during phase inversion. The transition point where phase inversion occurred was always within the range of . Pressure losses differed at the various test sections and the difference was strongly linked to the superficial velocity of the phases and the flow pattern. At high mixture velocity, pressure losses at the redeveloping section after the bend were higher than that at the bend and that for fully developed flows. At low mixture velocity, pressure losses at the bend are higher than in the straight sections. Pressure drop generally decreased with level of flow development downstream of the bend.
Optical Micro-Angiography (OMAG) Based Range Optimization Method for Liquid Flow Rate
Peng Chen, Lei Jiang, Haixia Wang, Xiaorui Guo, Yilong Zhang, Yonghong He, Ronghua Liang
Subject: Physical Sciences, Optics Keywords: OMAG method; flow rate measurement; micro flow rate
Optical micro-angiography (OMAG) is a new method of detecting flow rate and widely used for in vivo imaging. Although OMAG can distinguish between flowing and stationary parts, it cannot obtain accurate flow rate information. This study proposed a range formula for OMAG and the ultrahigh-sensitivity OMAG (UHS-OMAG) method to quantify the measurement range of an entire system. The parameters of the angle between beam scanning and flow directions, the angular velocity of the galvanometer, and the offset of incident light were introduced, and a formula for calculating the range was derived. Experiments were conducted to measure fine and ultra-fine flow rates by using OMAG and UHS-OMAG methods. The minimum measured flow rate was approximately 30 μm/s, and the maximum measured flow rate was approximately 8 mm/s. Experimental results are in good agreement with the preset results.
A Low-Cost Air Flow Sensor/Transducer for Medical Applications: Design and Experimental Characterization
Jesús Calderón, Carlos Rincón, Bray Agreda, Sebastián Calero, Manuel Bornas, Juan José Jiménez de Cisneros
Subject: Engineering, Automotive Engineering Keywords: air flow medical sensor; emergency air flow sensor; low-cost air flow sensor; COVID-19
Mechanical ventilation systems, which are used for breathing support when a person is not able to do it by their own, requires a device for measuring the air flow to the patient in order to monitoring and a assure the magnitude establish by a medical staff. Flow sensors are the conventional devices used for the air flow measuring; however, there were not available in Peru, because of the international demand during COVID-19 pandemic. In this sense, a novel air flow sensor based on orifice plate and an intelligent transducer stage were developed as an integrated design. Advanced methodologies in simulations and experiments using specially designed equipment for this application were carried out. The obtained data was used for a mathematical characterization and dimensions validation of the integrated design. The device was tested in its real working conditions, it was implemented in a breathing circuit connected to a low-cost mechanical ventilation system based on cams. Results indicate that the designed air flow sensor/transducer is a low-cost complete medical device for mechanical ventilators able to provide satisfactorily all the ventilation parameters air flow, pressure and volume over time by measuring the air flow and calculating the others. Furthermore, this device provides directly a filtered equivalent electrical signal for a display or a computer.
Visualization and Understanding of Traffic Flow and Congestion in India
Tsutomu Tsuboi
Subject: Earth Sciences, Environmental Sciences Keywords: traffic flow analysis; traffic congestion; fundamental traffic flow characteristics
This study focuses on traffic condition analysis, especially in under developing country India and makes more visible of traffic flow by using traffic flow theory in order to understand real traffic condition. India is one of rapid economic growing countries and large market with second largest population 1.3 billion in 2018. On the other hand, there are social issues such as environment air pollution and global warming by traffic CO2 emission of transportation. This kind of condition is not only in India, but in other South East Asia and Africa in future. From recent more than one-month traffic observation in a typical major city Ahmedabad in Gujarat state, which has about 8 million population and industrialized city. In terms of traffic data collection, 14 CCTV cameras are used in the city. Based on multiple traffic cameras monitoring, author found the unique traffic flow characteristics and compares traffic flow theory. In this study, it is described what is key parameters to show real traffic congestion condition and how these congestion occurs.
Hydrodynamic and Hydrographic Modeling of Istanbul Strait
Mehmet Melih Koşucu, Mehmet Cüneyd Demirel, V.S. Ozgur Kirca, Mehmet Özger
Subject: Earth Sciences, Oceanography Keywords: Istanbul Strait; stratified flow; gravity driven flow; numerical modelling
The aim of this study is to model hydrodynamic processes of the Istanbul Strait with its stratified flow characteristic and calibrate the most important parameters using local and global search algorithms. For that two open boundary conditions are defined, which are in the North and South part of the Strait. Observed bathymetric, hydrographic, meteorological and water level data are used to set up the Delft3D-FLOW model. First, the sensitivities of model parameters on the numerical model outputs are assessed using PEST toolbox. Then, the model is calibrated based on the objective functions focusing on the flowrates of upper and lower layers. The salinity and temperature profiles of the Strait are only used for model validation. The results show that the calibrated model outputs of Istanbul Strait are reliable and consistent with the in-situ measurements. The sensitivity analysis reveals that the Spatial Low-Pass Filter Coefficient, Horizontal Eddy Viscosity, Prandtl-Schmidt Number, Slope in log-log Spectrum and Manning Roughness Coefficient are most sensitive parameters affecting flowrate performance of the model. The agreement between observed salinity profiles and simulated model outputs is promising whereas the match between observed and simulated temperature profiles is weak showing that the model can be improved particularly for simulating the mixing layer.
Introducing a Structured Daily Multi-Disciplinary Board Round to Safely Enhance Surgical Ward Patient Flow in the Bed Shortage Era: A Quality Improvement Research Report
Roberto Valente, Gregorio Santori, Lorna Stanton, Ajit Abraham, Mohamed Thaha
Subject: Medicine & Pharmacology, Other Keywords: Patient flow; Surgery; Quality improvement
Hospital bed shortage is a worldwide concern. Beds unavailability has caused elective surgery cancellations, at our hospital peaking in spring 2016 at over 50%. This is often due to difficult patient step-down from intensive care (ICU) and high-dependency units (HDU). In our general/digestive surgery service admitting approximately 1000 patients yearly, ward rounds were run on a consultant firm basis. We report a quality improvement (ISRCTN13976096) introducing in our service a structured daily multi-disciplinary board round framework (SAFER Surgery R2G) adapted from the "SAFER patient flow bundle" and the "Red to Green days" approaches to enhance flow, comparing the previous year to 2017, when our framework was applied for 12 months.We used a Plan-Do-Study-Act (PDSA) methodology. Our intervention consisted in 1) systematic communication of the key care plan after the afternoon ward rounds to the nurse in charge; 2) 30' 10AM Monday-to-Friday multidisciplinary board rounds, attended daily by the senior-team and weekly by hospital and site managers, revising the key care plan aiming at safe, early discharges, assessing the appropriateness of each inpatient day and tackling any cause of delay. We measured patient flow by average length of stay (LOS), ICU/HDU step-downs and operation cancellations count, monitoring safety through early 30-day readmissions. Compliance was assessed by board round attendance and staff satisfaction rate surveys.After 12 months (PDSA 2, N=1032), LOS significantly decreased from 7.2(±8.9) to 6.3(±7.4) days (p=0.003); ICU/HDU bed step-down flow increased by 9.3% from 345 to 375 (p=0.197), surgery cancellations dropped from 38 to 15 (p=0.100). 30-day re-admissions increased from 0.9% (N=9) to 1.3% (N=14)(p=0.390). Average cross-specialty attendance was 80%. Satisfaction rates were >75%, regarding enhanced teamwork and faster decisions.The SAFER Surgery R2G framework has shown an increase in patient flow in the context of an enhanced multidisciplinary approach, requiring senior staff commitment to remain sustainable.
Efficiency Comparison of Hydro Turbines in a Micro Generator System from Free-flow Vortex
Piyawat Sritram, Ratchaphon Suntivarakorn
Subject: Engineering, Energy & Fuel Technology Keywords: Gravitational vortex; Free-flow vortex; Cross flow turbine; Propeller turbine.
This study aimed to enhance a micro hydroelectric generator system driven by free-flow vortex and to compare efficiency of Propeller and Crossflow turbines. Series of turbines in each type were designed and tested at water-flowrate of 0.02 m3/s. The turbine housing has 1 meter in diameter and 0.5-meter height with 2 meters outlet drain at the bottom. The best efficiency extracted from Crossflow turbines with the same height (0.3 meter) but different in diameter (0.4, 0.5, 0.6, and 0.7 meter) and numbers of blade (12, 18, 24, 30, and 23) was from an 18 blades turbine at 23.01% of efficiency. The best efficiency extracted from Propeller turbines with 5 blades was from a 0.4-meter-high turbine with a diameter of 0.7 meter at 13.92% of efficiency. There were 12 Propeller turbines designed in this study. They were different in height (0.2, 0.3, and 0.4 meter) and, in each height, 0.4, 0.5, 0.6, and 0.7 of diameter was applied. The result revealed that Cross Flow turbine had more efficiency to the system than Propeller turbine (9.09%) at the water-flowrate of 0.02 m3/s
Overtopping Metrics and Coastal Safety: A Case of Study from the Catalan Coast
Corrado Altomare, Xavi Gironella, Tomohiro Suzuki, Giacomo Viccione, Alessandra Saponieri
Subject: Engineering, Civil Engineering Keywords: wave overtopping; coastal safety; flow velocity; flow depth; sea dikes
Design criteria for coastal defenses exposed to wave overtopping are usually assessed by mean overtopping discharges and maximum individual overtopping volumes. However, it is often difficult to give clear and precise limits of tolerable overtopping for all kind of layouts. A few studies analyzed the relationship between wave overtopping flows and hazard levels for people on sea dikes, confirming that one single value of admissible mean discharge or individual overtopping volume is not a sufficient indicator of the hazard, but detailed characterization of flow velocities and depths is required. This work presents the results of an experimental campaign aiming at characterizing the flow characteristics associated to maximum individual overtopping volumes for an urbanized stretch of a town along the Catalan coast, where a walking and bike path and a railway run along the coastline are exposed to significant overtopping events every stormy season. The work compares different safety criteria for pedestrian. Results prove that safety of pedestrian on a sea dike can be still guaranteed even for overtopping volumes larger than 1000 l/m. Pedestrian hazard is rather proved to be linked to the combination of overtopping flow velocity and flow depth.
A Novel Approach to Model the Hydrodynamic Response of the Surficial Level of the Ionian Multilayered Aquifer during Episodic Rainfall Events
Nicola Pastore, Claudia Cherubini, Angelo Doglioni, Concetta I. Giasi, Vincenzo Simeone
Subject: Earth Sciences, Environmental Sciences Keywords: episodic rainfall; multilayered aquifer; unsaturated flow; preferential flow; kinematic dispersion wave model; random walk; confined-unconfined flow conversion
The paper presents a modeling framework to analyze the effect of episodic rainfall supply on groundwater dynamics in the Ionian coastal plain multilayered aquifer. The focus is essentially on the short-term behavior of the shallowest layer, with a specific analysis on episodic rainfall events. In the studied aquifer, groundwater level responds sensitively to rainfall events, highlighting the presence of preferential recharge zones. The hydraulic head peak is a function of groundwater level antecedent to the rainfall event. A kinematic dispersion wave model was used to model infiltration processes via preferential pathways. A one-dimensional and non-linear particle based numerical model was developed. Particles with constant water volume travel according to celerity and hydraulic dispersion to simulate the infiltration rate wave through the vadose zone. The flow rate that reaches the water table represents the input function to determine groundwater level fluctuations along groundwater flow direction and according to the lithological features of the surficial levels of the multilayered aquifer, its storage capacity changes passing from unconfined to confined conditions. The model was validated with high time resolution time series of precipitation and groundwater level coming from Terra Montonata meteo-climatic and groundwater level monitoring station. The developed model represents a basis for evaluating and predicting groundwater discharge of the shallowest layers of the Ionian coastal multilayered aquifer under natural conditions including episodic rainfall.
Computational Fluid Dynamic (CFD) Simulation of Bifurcate Artery
Yas Barzegar, Atrin Barzegar
Subject: Keywords: flow pattern; Artery wall; heart muscle; flow rate; computational fluid dynamic
Heart attacks and strokes are one of the leading causes of death in the world today, and heart attacks caused by clogged arteries that carry blood to the heart muscle are a significant part of these strokes. These are caused by the accumulation of fat particles in the walls of the arteries and the reduction of blood flow through it over a long process. The process of fat penetration in the underlying layers of the Artery wall has been the focus of many researchers, and various researches and Simulations have been done on it, in each of them, the effect of specific parameters has been considered. In the present study, the effect of blood flow rate on the flow pattern in a bifurcate artery with two ducts has been investigated using FLUENT software with Computation fluid dynamic Method. The effect of the angle between the two ducts of the Artery on the flow pattern has been investigated.
StEMORS: A Stochastic Eco-Hydrological Model for Optimal Reservoir Sizing
Aristotelis Koskinas, Pinelopi Tsira, Aristoteles Tegos
Subject: Engineering, Civil Engineering Keywords: environmental flow assessment; water balance model; stochastic analysis; reliability; dynamic flow regime
Dams design and their operation cause strong environmental alteration and therefore a long-term debate is ongoing for the scale of these projects. At the same time, the concept of Environmental Flow Assessment (EFA) is a crucial element of modified ecosystems featuring large infrastructure such as dams and reservoirs for mitigating potential environmental degradation while they operate. Nowadays, integrated scientific frameworks are required to quantify the risks caused by large infrastructure. Through the use of stochastic analysis, it is possible to quantify these uncertainties, and present a solution that incorporates long-term persistence and environmental sustainability into a balanced reservoir simulation model. In this work, an attempt is made to determine a benchmark reservoir size incorporating hydrological and ecological criteria though stochastic analysis. The primary goal is to ensure the best possible conditions for the ecosystem, and then secondarily to allow a steady supply of water for other uses. Using a synthetic timeseries based on historical inputs, it is possible to determine and preserve essential statistical characteristics of a river's streamflow, and use these to detect the optimal reservoir capacity that maximizes environmental and local water demand reliability.
Flow Structure Around Marginal Bank with Different Slopes Under the Action of Unsteady Flow
Pingyi Wang, Ye Tian, Genting Guo, Meili Wang
Subject: Earth Sciences, Environmental Sciences Keywords: marginal bank; unsteady flow; different slopes; water flow structure; experimentation; Yangtze River
Unsteady flow is the most common and complicated form of fluid motion in nature. This paper takes the beaches of key waterways in the middle and lower reaches of the Yangtze River as the research object, analyzes the water surface distribution and average flow velocity distribution near the beach, and analyzes the differences. The relationship between the flow pattern of the steep slope and the water flow pattern of the entire survey area and the steep slope of the beach and its nearby water flow structure. The water flow near the beach is divided into four major blocks: the swelling water area, the falling water area, the backwater area and the maximum flow rate area. The water flow structure characteristics and the cause of each block are analyzed.
Symbolic Regression Based Genetic Approximations of the Colebrook Equation for Flow Friction
Pavel Praks, Dejan Brkić
Subject: Engineering, General Engineering Keywords: Colebrook equation; flow friction; turbulent flow; genetic programming; symbolic regression; explicit approximations
Widely used in hydraulics, the Colebrook equation for flow friction relates implicitly to the input parameters; the Reynolds number, Re and the relative roughness of inner pipe surface, ε/D with the output unknown parameter; the flow friction factor, λ; λ=f(λ, Re, ε/D). In this paper, a few explicit approximations to the Colebrook equation; λ≈f(Re, ε/D), are generated using the ability of artificial intelligence to make inner patterns to connect input and output parameters in explicit way not knowing their nature or the physical law that connects them, but only knowing raw numbers, {Re, ε/D}→{λ}. The fact that the used genetic programming tool does not know the structure of the Colebrook equation which is based on computationally expensive logarithmic law, is used to obtain better structure of the approximations which is less demanding for calculation but also enough accurate. All generated approximations are with low computational cost because they contain a limited number of logarithmic forms used although for normalization of input parameters or for acceleration, but they are also sufficiently accurate. The relative error regarding the friction factor λ, in best case is up to 0.13% with only two logarithmic forms used. As the second logarithm can be accurately approximated by the Padé approximation, practically the same error is obtained also using only one logarithm.
High-Speed Visual Analysis of Fluid Flow and Heat Transfer in Oscillating Heat Pipes with Different Diameters
Xiangdong Liu, Qing Sun, Chengbin Zhang, Liangyu Wu
Subject: Engineering, Energy & Fuel Technology Keywords: oscillating heat pipe; fluid flow motion; flow pattern; thermal performance; inner diameter
The oscillating heat pipe (OHP) is a new member in the family of heat pipes, and it has great potential applications in energy conservation. However, the fluid flow and heat transfer in the OHP as well as the fundamental effects of inner diameter on them have not been fully understood, which are essential to the design and optimization of the OHP in real applications. Therefore, by combining the high-speed visualization method and infrared thermal imaging technique, the fluid flow and thermal performance in the OHPs with inner diameters of 1, 2 and 3 mm are presented and analyzed. The results indicate that three fluid flow motions, including small oscillation, bulk oscillation and circulation, coexist or, respectively, exist alone with the increasing heating load under different inner diameters, with three flow patterns occurring in the OHPs, viz. bubbly flow, slug flow and annular flow. These fluid flow motions are closely correlated with the heat and mass transfer performance in the OHPs, which can be reflected by the characteristics of infrared thermal images of condensers. The decrease in the inner diameter increases the frictional flow resistance and capillary instability while restricting the nucleate boiling in OHPs, which leads to a smaller proportion of bubbly flow, a larger proportion of short slug flow, a poorer thermal performance, and easier dry-out of working fluid. In addition, when compared with the 2 mm OHP, the increasing role of gravity induces the thermosyphon effect and weakens the 'bubble pumping' action, which results in a little smaller and bigger thermal resistances of 3 mm OHP under small and bulk oscillation of working fluid, respectively.
An Extension of the All-Mach Number Pressure-Based Solution Framework for Numerical Modelling of Two-Phase Flows with Interface
Matvey Kraposhin, Aleksandr Kukharskii, Viktoria Korchagova, Aleksandr Shevelev
Subject: Physical Sciences, Fluids & Plasmas Keywords: two-phase flow; compressible flow; interfacial flow; computational hydrodynamic; computational gas dynamic; finite volume method; OpenFOAM; All-Mach number solver
In this paper, we present the extension of the pressure-based solver designed for the simulation of compressible and/or incompressible two-phase flows of viscous fluids. The core of the numerical scheme is based on the hybrid Kurganov— Noele — Petrova/PIMPLE algorithm. The governing equations are discretized in the conservative form and solved for velocity and pressure, with the density evaluated by an equation of state. The acoustic-conservative interface discretization technique helps to prevent the unphysical instabilities on the interface. The solver was validated on various cases in wide range of Mach number, both for single-phase and two-phase flows. The numerical algorithm was implemented on the basis of the well-known open-source Computational Fluid Dynamics library OpenFOAM in the solver called interTwoPhaseCentralFoam. The source code and the pack of test cases are available on GitHub: https://github.com/unicfdlab/hybridCentralSolvers
Turbulent Poiseuille Flow Modelling by an Modified Prandtl-van Driest Mixing Length
Bohua Sun
Subject: Physical Sciences, Fluids & Plasmas Keywords: Turbulent flow; Poiseuille flow; Prandtl mixing length; high heels velocity profile; Reynolds number
The turbulent Poiseuille flow between two parallel plates is one of the simplest possible physical situations, and it has been studied intensively. In this paper, we propose a modified Prandtl-van Driest mixing length that satisfies both boundary conditions and wall damping effects. With our new formulations, we numerically solve the problem and, moreover, propose an approximate analytical solution of mean velocity. As applications of our solution, an approximate analytical friction coefficient of turbulent Poiseuille flow is proposed.
Application of Local Gauge Theories to Fluid Mechanics Part 1 - Fluid Mechanics as a Local Gauge Theory and Relation to Navier-Stokes Equations
Thomas Merz
Subject: Physical Sciences, Condensed Matter Physics Keywords: fluid dynamics; turbulent flow; stationary flow; SO(3) local gauge; quasiparticle; non-linearity
The problem of fluid dynamics can be greatly simplified if, for every point in space, the strain-rate tensor is diagonalized. This tensor is introduced into the Navier-Stokes equations via material law and divergence of the stress tensor. This article shows that local SO(3)xU(1) gauge fields can be used to locally diagonalize the diffusion components of the strain-rate tensor. The gauge fields resulting from the connection can be interpreted as convection components of the flow, they show properties of quasiparticles and can be interpreted as elementary vortices. Thus, the proposed approach not only offers new insights for the solution and situative simplification of the Navier-Stokes equations, it also uncovers hidden symmetries within the flow convection, allowing - depending on boundary conditions - further interpretation.
Effects of Combination Impeller on the Flow Field and External Performance of an Aero-fuel Centrifugal Pump
Jia Li, Xin Wang, Yue Wang, Wancheng Wang, Baibing Chen, Xiaolong Chen
Subject: Engineering, Energy & Fuel Technology Keywords: aero-fuel centrifugal pump; combination impeller; flow loss; flow characteristics; head and efficiency
Online: 9 January 2020 (05:22:18 CET)
Aero-fuel centrifugal pumps are important power plants in aero-engines. Unlike most of the existing centrifugal pumps, a combination impeller is integrated with the pump to improve its performance. First, the critical geometrical parameters of combination impeller and volute are given. Then, the effects of combination impeller on flow characteristics inside the impeller and volute are clarified by comparing simulation results with that of the conventional impeller, where the effectiveness of selected numerical method is validated by an acceptable agreement between simulation and experiment. Finally, the experiment is performed to test the external performance of studied pump. A significant feature of this study is that the flow characteristics are significantly ameliorated by reducing the flow losses emerged in impeller inlet, impeller outlet and volute tongue. Correspondingly, the head and efficiency of combination impeller are higher with comparison to conventional impeller. Consequently, it is a promising approach in ameliorating flow field and improving external performance by applying a combination impeller to an aero-fuel centrifugal pump.
Vortex Interactions Subjected to Deformation Flows: A Review
Konstantin V. Koshel, Eugene A. Ryzhov, Xavier J. Carton
Subject: Physical Sciences, Fluids & Plasmas Keywords: flow; deformation flow; point vortex; elliptic vortex; chaotic dynamics; parametric instability; stability islands
Deformation flows are flows incorporating shear, strain and rotational components. These flows are ubiquitous in the geophysical flows, such as the ocean and atmosphere. They appear near almost any salience, such as isolated coherent structures (vortices and jets), various fixed obstacles (submerged obstacles, continental boundaries). Fluid structures subject to such deformation flows may exhibit drastic changes in motion. In this review paper, we focus on the motion of a small number of coherent vortices embedded in deformation flows. Problems involving isolated one and two vortices are addressed. When considering a single-vortex problem, the main focus is on the evolution of the vortex boundary and its influence on the passive scalar motion. Two vortex problems are addressed with the use of point vortex models, and the resulting stirring patterns of neighbouring scalars are studied by a combination of numerical and analytical methods from the dynamical system theory. Many dynamical effects are reviewed with emphasis on the emergence of chaotic motion of the vortex phase trajectories and the scalars in their immediate vicinity.
Play, Flow and Wonder – Reassessing the Notion of Optimal Experience
Jesper Falck Legaard
Subject: Arts & Humanities, General Humanities Keywords: Play; Flow; Design; Wonder; Toys
Since its introduction almost 50 years ago, the concept of 'flow' has been descriptive of optimal experiences, also in relation to play. However, the explorative nature of play leads to some discrepancies between flow and the optimal experience of play. In this paper the differences between flow and play are explored, leading to proposing the state of 'wonder' (directed at exploration) as an alternative to 'flow'. From this perspective, the study further explores how we may design toys that enable meaningful experiences of play, identifying opportunities in designing for toys as the enablers of immersed experiences of wonder.
Solving the 'Two Times Problem' With an Information Gathering and Utilizing System (IGUS)
Ronanld P. Gruber, Carlos Montemayor, Richard A. Block
Subject: Physical Sciences, General & Theoretical Physics Keywords: IGUS; flow of time; passage
There is a long standing 'two times problem' in that a satisfactory reconciliation between the time of physics and that of psychology has not been realized. A partial solution to the past/present/future phenomenon has been successfully given by the Hartle information gathering and processing system (IGUS) view. That model IGUS robot is enhanced here for the entire 'two times problem' to deal with not only the temporal experiences of the flow of time but also those of manifest time. A dualistic robot is proposed which has a veridical system of temporal experiences that are compatible with various spacetime cosmologies. It also has an illusory system of corresponding temporal experiences. This dualistic IGUS robot was made possible by discovering temporal experience within the brain that correspond to those of physics. The dualistic theory suggests that the veridical system, as a result of evolution, begets the illusory system to enhance behavioral adaptation. Thus, there is just one fundamental physical time which the brain does, indeed, possess and then enhances with illusory counterparts. Therefore, there should no longer be a need to reify illusory temporal experiences as modern spacetime cosmologies tend to do. Physical time already resides within human time.
Effects of Sales, Receivables Turnover, and Cash Flow on Liquidity
Rusdiyanto Rusdiyanto, Dian Agustia, Soegeng Soetedjo, Dina Fitrisia Septiarini, Susetyorini Susetyorini, Umi Elan, Mochamad Syafii, Bustanul Ulum, Petrus Suparman, Dwi Inggarwati Rahayu, Dini kusumaningrum
Subject: Social Sciences, Accounting Keywords: sales; receivables; cash flow; liquidity
In this study, the author proposes to evaluate the effect of sales growth, Receivable Turnover and operating cash flow on the liquidity of PT. Unilever Indonesia Plc. The research method used is descriptive method with a quantitative approach. In this statement, the population used in this study is the financial statement data from PT. Unilever Indonesia Plc. from 2010 to 2018, the technique of determining the sampling uses Purposive Sampling. This research data uses secondary data from PT. Unilever Indonesia Plc financial statements from 2010 to 2018. All data sources were obtained from the website of the Indonesia Stock Exchange at https://www.idx.co.id, the company's website and Google search. Our analysis reveals that sales growth and accounts receivable turnover from PT. Unilever Indonesia Plc. has no influence on the liquidity of PT. Unilever Indonesia Plc, while operating cash flow has an influence on the Liquidity of PT Unilever Indonesia Plc. This means the ups and downs of the value of sales and accounts receivable turnover of a company has no influence on the liquidity of PT. Unilever Indonesia Plc, while operating cash flow has increased or decreased has an influence on the liquidity of PT Unilever Indonesia Plc. The value of sales growth, accounts receivable turnover and operating cash flow can explain the liquidity of PT Unilever Indonesia Plc. by 78%, while 22% is explained by other factors which are not included in this study.
Characterisation of Hydrological Response to Rainfall at Multi Spatio-Temporal Scales in Savannas of Semi-Arid Australia
Ben Jarihani, Roy C. Sidle, Rebecca Bartley, Christian H. Roth, Scott Wilkinson
Subject: Earth Sciences, Environmental Sciences Keywords: rainfall-runoff; rainfall variability; Hortonian overland flow; saturation overland flow; ground cover; Burdekin catchment
Rainfall is the main driver of hydrological processes in dryland environments and characterising the rainfall variability and processes of runoff generation are critical for understanding ecosystem function of catchments. Using remote sensing and in situ data sets, we assess the spatial and temporal variability of the rainfall, rainfall-runoff response, and effects of antecedent soil moisture and ground cover at different spatial scales on runoff coefficients in the Upper Burdekin catchment, northeast Australia, which is a major contributor of sediment and nutrients to the Great Barrier Reef. The high temporal and spatial variability of rainfall exerts significant controls on runoff generation processes. Rainfall amount and intensity are the primary runoff controls, and runoff coefficients for wet antecedent conditions were higher than for dry conditions. The majority of runoff occurred via surface runoff generation mechanisms, with subsurface runoff likely contributing little runoff due to the intense nature of rainfall events. At annual to seasonal temporal scales and for relatively large catchments, we could not detect a significant effect of ground cover on runoff. We conclude that in the range of moderate to large catchments (193 – 36,260 km2) runoff generation processes are sensitive to both antecedent soil moisture and ground cover. A higher runoff-ground cover correlation in drier months with sparse ground cover highlighted the critical role of cover at the onset of the wet season and how runoff generation is more sensitive to cover in drier months than in wetter months. The monthly water balance analysis indicates that runoff generation in wetter months (January and February) is partially influenced by saturation overland flow, most likely confined to saturated soils in riparian corridors, swales, and areas of shallow soil. By March and continuing through October, the soil 'bucket' progressively empties by evapotranspiration, and Hortonian overland flow becomes the dominant, if not exclusive, flow generation process. The results of this study can be used to better understand the rainfall-runoff relationships in dryland environments and subsequent exposure of coral reef ecosystems in Australia and elsewhere to terrestrial runoff.
In Vitro Investigation of Gas Embolism in Microfluidic Networks Mimicking Microvasculature
Mohammad Mahdi Mardanpour, Ayyappasamy Sudalaiyadum Perumal, Zahra Mahmoodi, Karine Baassiri, Gala Montiel Rubies, Kenneth M. LeDez, Dan V. Nicolau
Subject: Engineering, Biomedical & Chemical Engineering Keywords: gas embolism; microfluidics; microvasculature; flow pattern
Gas embolism is a medical condition leading to the blockage of blood flow in the microvasculature by gas bubbles. While reported as rare, gas embolism often has devastating, fatal physiological consequences. Despite this acute importance, the genesis and evolution of air bubbles in blood vessels under different physiological conditions, such as blood viscosity and blood flow rate, is still understudied, largely because of difficult experimentation and in situ visualization. The objective of this work was to study the gas embolism phenomenon in vitro, using a microfluidic system that mimicked the architecture of microvasculature. The microfluidic systems comprised linear channels with two different air inlet types, namely, T- and Y-junctions with three different widths (20 µm, 40 µm, and 60 µm), and a 30 µm width honeycombed network with three bifurcation angles (30°, 60°, and 90°). Three synthetic liquids equivalent to 0%, 20%, and 46% hematocrit that mimicked the physiological blood viscosity and hematocrit concentrations were used. Our results show that: (i) 20 µm and 40 µm width channels had an elevated risk of gas embolism due to wide fluctuations in the total slug sizes; (ii) the resistance to the flow of air bubbles increased with the increase in the equivalent concentration of hematocrit; (iii) gas bubbles causing blockages and dampening of the flow velocity were frequently observed in 20 µm channels, and lastly (iv) increased risk of gas embolism was observed in the honeycomb architecture with 60° and 30° bifurcations. This work suggests that in vitro experimentation using microfluidic devices with microvascular tissue-like structures opens the possibility of studying this medical condition with high reproducibility and impacts the fact-based medical guidelines for preventing or mitigating iatrogenic occurrences.
A Study of RANS Turbulence Models in Fully Turbulent Jets: A Perspective for CFD-DEM Simulations
Dustin Steven Weaver, Sanja Mišković
Subject: Engineering, General Engineering Keywords: Jet Flow; CFD; Turbulence; CFD-DEM
This paper presents an analysis of linear viscous stress Favre-Averaged turbulence models for computational fluid dynamics (CFD) of fully turbulent round jets with a long straight tube geometry in the near field. Although similar work has been performed in the past with very relevant solutions, considerations were not given for the issues and limitations involved with coupling between an Eulerian and Lagrangian phase, such as in fully two-way coupled CFD-DEM. These issues include limitations on solution domain, mesh cell size, wall modelling, and momentum coupling between the two phases in relation to the particles size. Therefore, within these considerations, solutions are provided to the Navier-Stokes equations with various turbulence models using a three-dimensional wedge long straight tube geometry for fully developed turbulence flow. Simulations are performed with a Reynolds number of 15000 and 50000 using two different tube diameters. It is found that a modified k−ε turbulence model achieved the most agreeable results for both the velocity and turbulent flow fields between these two flow regimes, while a modified k−ω SST/BSL also provided suitable results.
The Effect of Magnesium Supplementation on Endothelial Function: A Randomised Cross-Over Pilot Study
Jennifer Byrne, Caitriona Murphy, Jennifer B. Keogh, Peter M. Clifton
Subject: Medicine & Pharmacology, Allergology Keywords: magnesium; flow mediated dilatation; endothelial function
Evidence supports an association between low magnesium (Mg) intake and coronary heart disease and between Mg intake and endothelial function. The aim of this study was to assess the effect of one week of Mg supplementation on endothelial function, assessed by flow mediated dilatation (FMD). Nineteen healthy men and women completed this cross-over pilot study in which participants were randomised to take an over-the-counter magnesium supplement for one week or to follow their usual diet. Weight, FMD and blood pressure (BP) were taken on completion of each intervention and 24hour urine collections and blood samples were taken to assess compliance. Baseline serum Mg was within normal range for all participants. Urinary Mg and urinary magnesium-creatinine ratio (Mg/Cr) significantly increased between interventions, (p = 0.03, p = 0.005 respectively). No significant differences in FMD or BP were found between the interventions. A significant negative correlation was seen between age and FMD (r = -0.496, p = 0.031). When adjusted for age, saturated fat was negatively associated with FMD (p = 0.045). One week of Mg supplementation did not improve FMD in a healthy population.
Byrne Byrne, Caitriona Murphy, Jennifer B. Keogh, Peter M. Clifton
Online: 30 March 2021 (10:52:56 CEST)
The Acute Effect of Magnesium Supplementation on Endothelial Function: A Randomised Cross-Over Pilot Study
Caitriona Murphy, Jennifer Byrne, Jennifer B Keogh, Michelle L Headland, Peter M. Clifton
Magnesium (Mg) deficiency may be a catalyst in the process of endothelial dysfunction, an early event in the pathogenesis of atherosclerosis. The aim was to determine the acute effect of an oral Mg supplement compared to control on endothelieal function assessed by flow-mediated-dilatation (FMD). Nineteen participants (39 years, body mass index (BMI) 22.9kg/m2) completed this randomised cross-over study. Blood pressure (BP) and FMD were measured and blood samples taken before participants drank 200ml water with or without an over the counter Mg supplement (450mg and 300mg for men and women). Measurements were repeated at 60 and 120 minutes. There was a statistically significant two-way interaction between treatment and time on serum Mg (p = .037). A difference of -0.085mm in FMD was observed 60 minutes post drink in the control group compared to baseline FMD, and no difference was observed in the supplement group compared to baseline. Despite the non-significant interaction between treatment and time on FMD, the difference seen in the control group and the lack of change in the supplement group at 60 minutes post-drink suggests that Mg may attenuate the reduction in FMD post-prandially.
Microfluidic Preparation of 89Zr-Radiolabelled Proteins by Flow Photochemistry
Daniel F. Earley, Amaury Guillou, Dion van der Born, Alex J. Poot, Jason P. Holland
Subject: Chemistry, Analytical Chemistry Keywords: Flow Chemistry; Photochemistry; Radiochemistry; Protein Conjugation.
89Zr-radiolabelled proteins functionalised with desferrioxamine B are a cornerstone of diagnostic positron emission tomography. In the clinical setting, 89Zr-labelled proteins are produced manually. Here, we explore the potential of using a microfluidic photochemical flow reactor to prepare 89Zr-radiolabelled proteins. The light-induced functionalisation and 89Zr-radiolabelling of human serum albumin ([89Zr]ZrDFO-PEG3-Et-azepin-HSA) was achieved by flow photochemistry with a decay-corrected radiochemical yield (RCY) of 31.2±1.3% (n = 3) and radiochemical purity >90%. In comparison, a manual batch photoreactor synthesis produced the same radiotracer in a decay-corrected RCY of 59.6±3.6% (n = 3) with an equivalent RCP >90%. The results indicate that photoradiolabelling in flow is a feasible platform for the automated production of protein-based 89Zr-radiotracers, but further refinement of the apparatus, and optimisation of the method is required before the flow process is competitive with manual reactions.
Application of an Innovative Effluent Capture and Evacuation Device that Increases the Efficiency of Subsurface Flow Wetlands
Pedro Cisterna-Osorio, Gisela Silva-Vasquez, Mauricio Llanos-Baeza, Veronica Lazcano-Castro, Felipe Fuentes-Ortega
Subject: Earth Sciences, Environmental Sciences Keywords: Artificial Wetlands, Horizontal Wetland, Subsurface Flow
The objective of this work is to evaluate the impact of the innovative modifications made to the conventional effluent capture and discharge devices used in subsurface flow wetlands (SSFW). The main modifications developed consist on extending the influence of the capture and discharge device in such a way that the SSFW width and height are fully covered. This improved innovative device was applied and evaluated in two subsurface flow wetlands, one on a pilot scale and one on a real scale. To evaluate the impact of the innovative device with respect to conventional one in the operational functioning of subsurface flow wetlands, the elimination of chemical oxygen demand was measured and compared. The results show that for the innovative device, the COD removal was 10% higher than for the conventional device, confirming the validity and effectiveness of the modifications implemented in the effluent capture and discharge devices used in SSFW.
Model of Flow Resistance Coefficient for a Fragment of a Porous Material Deposit with Anisotropic Skeletal Structure
Grzegorz Wałowski
Subject: Engineering, Energy & Fuel Technology Keywords: flow resistance; gas; porous material; permeability
The hydrodynamic results obtained from the permeability of porous materials not only affect the assessment of the stream of the gas flow through those materials but they also refer to the loss of pressure energy in that flow. The direct measure of that loss is flow resistances.The results of experimental research upon the assessment of the flow resistances of porous materials with respect to gas flow. The research conducted applied to natural materials with an anisotropic gap-porous structure. The tests were carried out on a gas permeability measuring system, adapted to different shapes of porous material samples. The process issue of the total pressure drop on a porous deposit was considered in the Reynolds number category. The coefficient of flow resistance for anisotropic materials was defined and the value of this coefficient was compared to the gas stream and the total pressure drop on the porous bed was experimentally evaluated.
Experimental and Numerical Studies of Hydrodynamics of Gas Flow through Orthogonal Networks
Subject: Materials Science, Polymers & Plastics Keywords: Isotropic material; CFD; hydrodynamics; gas flow
Simulation programs contain Computational Fluid Dynamics - CFD codes and are a useful tool used for gas flow through porous materials. Conducting numerical simulations allows for detailed analysis of hydrodynamic phenomena. The results of numerical modeling should always be verifiable based on experimental data. Only their compliance with the results of experimental tests is a determinant of the correctness of the applied method. As part of the work, experimental studies of hydrodynamics of gas flow through an isotropic porous material were carried out and numerical simulation for material of the same shape was used. In the CFD modeling Kolmogorov's hypothesis for the transport of kinetic energy of turbulence k and transport of dissipation rate of kinetic energy of turbulence ε was used.
Increase Efficiency of Horizontal Subsurface Flow Wetlands by Means of Innovating of the Effluent Capture and Evacuation Device
Pedro Cisterna-Osorio, Gisela Silva-Vasquez, Mauricio Llanos-Baeza, Verónica Lazcano-Castro, Ignacio Fuentes-Ortega
Subject: Engineering, Biomedical & Chemical Engineering Keywords: artificial wetlands; horizontal wetland; subsurface flow
The aim of this work is to evaluate the impact of proposed modifications to conventional capturing and discharging effluents devices in Subsurface Flow Wetland (SSFW) systems. Main modifications proposed consist on extending the influence of the capture and discharge device in such a way that the SSFW width and height are fully covered. Additionally an SSFW prototype was built as pilot including the proposed modifications and the impact of the innovative device is measured based on the efficiency of the Chemical Oxygen Demand (COD) removal as compared to a traditionally built SSFW. The results show that for the innovative device, the COD removal was 10% higher than for the conventional device.
Analysis of the Behavior of Velocity Profiles in a Standard Elbow Fitting
Víctor Places Garzón, Bence Mátyás, Luis Fernando Toapanta
Subject: Engineering, Automotive Engineering Keywords: turbulence; CFD; incompressible flow; velocity profiles
In this paper, we studied and analyzed the behavior of velocity profiles and the distribution of pressures in a pipe connected to an accessory. In this case, it was a 90º elbow fitting in which water flows as an incompressible flow. This study was developed numerically through the fluent program of ANSYS. It is of practical interest in engineering because it is based on results regarding the internal structure of a model of incompressible flows. In the same way, it provides a basis for the proper design and implementation of velocity profiles within an elbow.In the agricultural industry, suitable systems can be implemented for crop irrigation in this way with the results obtained to improve the design in the fluid distribution system.We used a feasible κ-ε turbulence model because this model causes less turbulence than the standard κ-ε model. A mesh independence study was developed, in which it was observed that combining different densities of meshes for the same geometry causes some variables, so a fine meshing was used to carry out the study so that the results are as close to reality as possible.
Exact solutions for the axial pressure drop in isothermal channels with maxwell slip flow
Alex Christian Hoffmann, Stamatina Karakitsiou, Bodil Holst
Subject: Engineering, General Engineering Keywords: Maxwell slip flow; microchannels; pressure profile
Expressions for the axial pressure profiles in a cylindrical channel and between parallel plates or a rectangular channel with large aspect ratio, with Maxwell slip gas flow are derived from first principles. The resulting expressions, which only involve the inlet and outlet pressures and the channel dimensions, will be useful in modelling or simulations of channel flows at Knudsen numbers in the range 0.001–0.1, such as in MEMS and NEMS. The expression for a cylindrical channel is validated by deriving from it an expression for the channel mass flow, which is shown to agree with a known expression for the mass flow through cylindrical channels with Maxwell slip flow. The expression for flow between parallel plates is found to agree with the zeroth order relation derived by Arkilic et al. using perturbation analysis. The effect of the accommodation coefficient on the pressure profile in a cylindrical channel is shown.
Perturbative Accelerating Solutions of Relativistic Hydrodynamics
Bálint Kurgyis, Máté Csanád
Subject: Physical Sciences, Nuclear & High Energy Physics Keywords: relativistic hydrodynamics; solutions; Hubble flow; acceleration
In ultra-relativistic collisions of heavy ions, the strongly interacting Quark Gluon Plasma (sQGP) is created. The fluid nature of the sQGP was one of the important discoveries of high energy heavy ion physics in the last decades. Henceforth the explosion of this matter may be described by hydrodynamical models. Besides numerical simulations, it is important to study the analytic solutions of the equations of hydrodynamics, as these enable us to understand the connection of the final and initial states better. In this paper we present a perturbative, accelerating solution of relativistic hydrodynamics, on top of a known class of solutions describing Hubble-expansion. We describe the properties of this class of perturbative solutions, and investigate a few selected solutions in detail.
Wing Tip Drag Reduction at Nominal Take-Off Mach Number: An Approach to Local Active Flow Control with a Highly Robust Actuator System
Matthias Bauer, Thomas Grund, Wolfgang Nitsche, Vlad Ciobaca
Subject: Engineering, Other Keywords: flow control; leading edge; fluidic actuator
This paper discusses wind tunnel test results aimed at advancing active flow control technology to increase the aerodynamic efficiency of an aircraft during take-off. A model of the outer section of a representative civil airliner wing was equipped with two-stage fluidic actuators between the slat edge and wing tip, where mechanical high-lift devices fail to integrate. The experiments were conducted at a nominal take-off Mach number of M = 0.2. At this incidence velocity, separation on the wing section, accompanied by increased drag, is triggered by the strong slat edge vortex at high angles of attack. On the basis of global force measurements and local static pressure data, the effect of pulsed blowing on the complex flow is evaluated, considering various momentum coefficients and spanwise distributions of the actuation effort. It is shown that through local intensification of forcing, a momentum coefficient of less than cμ = 0.6% suffices to offset the stall by 2.4°, increase the maximum lift by more than 10%, and reduce the drag by 37% compared to the uncontrolled flow.
Nanoparticle Based Water Treatment Model in Squeezing Channel under Magnetic Field
Sergei Zuev, Zakir Hussain, Petr Kabalyants
Subject: Mathematics & Computer Science, Applied Mathematics Keywords: nano-fluid; nanoparticles removing; magnetohydrodynamics; stability of the flow; water treatment; exact solution; instability of the flow
The process of water treatment by nanoparticles is one of the most considerable subjects in the cross-field of hydrodynamics, chemistry and mathematics. This paper is dedicated to the case of the flows that appear when squeezing and stretching a spongy with a mix of water with nanoparticles and contaminants. It is assumed that fluid is homogeneous at the starting moment, the parameters of the nanoparticles and contaminants are known, and there is a constant non-homogeneous magnetic field applied to the system. The flow starts moving when the walls of the channel shift to each other. Exact and numerical solutions of the system of ordinary differential equations are used to receive the results. The article gives an answer to the question about stability of the flow and proposes the technique to evaluate the essential characteristics of the system to achieve the treatment process efficiency. The main result is that the considered system shows excellent treatment properties during some part of squeezing stage. This effect does not appear without magnetic field.
Transitional Channel Flow: A Minimal Stochastic Model
Paul Manneville, Masaki Shimizu
Subject: Physical Sciences, Acoustics Keywords: transition to/from turbulence; wall-bounded shear flow; plane Poiseuille flow; spatiotemporal intermittency; directed percolation; critical phenomena
In line with Pomeau's conjecture about the relevance of directed percolation (DP) to turbulence onset/decay in wall-bounded flows, we propose a minimal stochastic model dedicated to the interpretation of the spatially intermittent regimes observed in channel flow before its return to laminar flow. Numerical simulations show that a regime with bands obliquely drifting in two stream-wise symmetrical directions bifurcates into an asymmetrical regime, before ultimately decaying to laminar flow. The model is expressed in terms of a probabilistic cellular automaton evolving von Neumann neighbourhoods with probabilities educed from a close examination of simulation results. It implements band propagation and the two main local processes: longitudinal splitting involving bands with the same orientation, and transversal splitting giving birth to a daughter band with orientation opposite to that of its mother. The ultimate decay stage observed to display one-dimensional DP properties in a two-dimensional geometry is interpreted as resulting from the irrelevance of lateral spreading in the single-orientation regime. The model also reproduces the bifurcation restoring the symmetry upon variation of the probability attached to transversal splitting, which opens the way to a study of the critical properties of that bifurcation, in analogy with thermodynamic phase transitions.
Analytical Modeling of Fluid Flow in Hydrophobic, Rectangular Microchannels with General Navier-Slip Boundary Conditions
Navid Kashaninejad
Subject: Engineering, Mechanical Engineering Keywords: slip flow; navier-slip boundary condition; hydrophobic microchannels; analytical solutions; poiseuille number; velocity profile of poiseuille flow
Fluid mechanics of flow in hydrophobic, rectangular microchannels with finite aspect ratios is of paramount importance. In such microchannels, not only the effect of the side walls should be taken into account, but also the classical assumption of no-slip boundary condition (BC) is no longer valid at the solid-liquid interface. Accordingly, slip flow can occur in microchannels fabricated from surfaces with low wetting conditions, hydrophobic surfaces. Determining the interactions of liquid molecules adjacent to solid surface is still a challenging issue, and it is especially important in small scale domains. Herein, the fluid mechanics of flow through rectangular hydrophobic microchannels has been reconsidered by taking into account the general Navier-slip BCs at the solid-liquid interface. For fully developed incompressible flow in microchannels at low Reynolds number, partial differential equation (PDE) of the momentum equation simplifies to the classical Poisson equation. Accordingly, by analytically solving the Poisson equations with general Navier-slip BCs, the most general forms of velocity distributions, flow rate, friction factor and Poiseuille number have been obtained.
Polymer Flow in Porous Media
Arne Skauge, Nematollah Zamani, Jørgen G. Gausdal Jacobsen, Behruz S. Shaker Shiran, Badar Al-Shakry, Tormod Skauge
Subject: Engineering, Energy & Fuel Technology Keywords: polymer flow; polymer in-situ rheology in porous medium; theoretical analysis; experimental results, linear and radial flow
Polymer flooding is one of the most successful chemical EOR methods, and is primarily implemented to accelerate oil production by sweep improvement. However, other benefits have extended the utility of polymers. During the last decade, it has been evaluated for an increasing number of fields, both offshore and onshore. This is a consequence of improved polymer properties, which extends the use to HTHS (high temperature high salinity) conditions and of improved understanding of flow mechanisms such as for heavy oil mobilization. A key issue in understanding polymer performance is to control and predict in-situ porous medium rheology. The first part of this paper reviews recent developments in understanding polymer flow in porous medium. Especially, polymer in-situ rheology and injectivity is discussed. The second part of this paper reports polymer flow experiments using the most applied polymer for EOR processes, HPAM (partially hydrolyzed polyacrylamide). The experiments address high rate near-wellbore behavior (radial flow) as well as reservoir rate steady state flow (linear flow) and discuss differences observed in terms of flow conditions. In addition, impact of oil on polymer rheology was investigated, and compared to single-phase polymer flow in Bentheimer sandstone rock material. Presence of oil leads to a reduction in apparent viscosity.
Impact of Plug-in Electric Vehicles Integrated into Power Distribution System based on Voltage Dependent Power Flow
Yuttana Kongjeen, Krischonme Bhumkittipich
Subject: Engineering, Electrical & Electronic Engineering Keywords: load flow analysis; load voltage deviation; plug-in electric vehicles load; power-flow analysis; static load models
This paper proposes the impact of plug-in electric vehicles integrated into power distribution system based on voltage dependent control. The plug-in electric vehicles was modeled as the static load model in power distribution systems under balanced load condition. The power flow analysis is determined by using the basic parameters of the electrical network. The main point of this study are compare with voltage magnitude profiles, load voltage deviation, and total power losses of the electrical power system. There are investigating the affected from constant power load, constant current load, constant impedance load and plug-in electric vehicles load, respectively. The IEEE 33 bus test system is used to test the proposed method by assigning each load type to a balanced load in steady state and applied the solving methodology based on the bus injection to branch injection matric, branch current to bus voltage matrix, and current injection matrix to solve the power flow problem. The simulation results showed that the plug-in electric vehicles load had the lowest impact compared to other loads. The lowest plug-in values for the electric vehicle loads were 0.062, 119.67 kW and 79.31 kVar for the load voltage deviation, total active power loss and total reactive power loss, respectively. Therefore, this study can be verified that the plug-in electric vehicles load were affected to the lowest of the electrical power system in condition to same sizing and position. So that, in condition to the plug-in electric vehicles load added into the electrical power system with the conventional load type or complex load type could be considered that the affected from the plug-in electric vehicles load in next study.
Micro-Scale Flow Excitation under Imposition of Uniform Magnetic Field and Electrical Current
Guangye Xu, Kazuhiko Iwai
Subject: Materials Science, Metallurgy Keywords: mass transfer; micro-scale flow; diffusion; convection
Mass transfer is often the rate determining step for solid-liquid chemical reactions. Decrease of the concentration boundary layer thickness is essential to intensify the chemical reaction. Because the concentration boundary layer exists in the velocity boundary layer, force imposition in the concentration boundary layer by superimposing an electrical current and a magnetic field was proposed. Through, flow can be directly excited in the concentration boundary layer. The previous result indicates that by superimposing a DC current and a gradient magnetic field, the development of the concentration boundary layer was suppressed, because of a macro-scale flow excitation in the whole vessel. And by superimposing the gradient magnetic field with a modulate current, the development of the concentration boundary layer was further suppressed. This is because of the macro-scale flow enhancement and the excitation of a micro-scale flow near the solid-liquid interface. However, the mechanism for the micro-scale flow excitation has not been clarified. To clarify this, a uniform magnetic field was superimposed with the DC current or the modulate current. By this means, only the micro-scale flow was excited near the anode surface. The results found that the non-unform electromagnetic force distribution is the main reason for the micro-scale flow excitation.
Frequency Power Spectra of Global Quantities in Magnetoconvection
Sandip Das, Krishna Kumar
Subject: Keywords: Magnetoconvection; Turbulent flow; Power spectral densities (PSD)
We present the results of direct numerical simulations of power spectral densities for kinetic energy, convective entropy and heat flux for unsteady Rayleigh-Bénard magnetoconvection in the frequency space. For larger values of frequency, the power spectral densities for all the global quantities vary with frequency f as f−2. The scaling exponent is independent of Rayleigh number, Chandrasekhar's number and thermal Prandtl number.
Sliding Mode Control and Geometrization Conjecture in Seismology
Ligia Munteanu, Dan Dumitriu, Cornel Brisan, Mircea Bara, Veturia Chiroiu, Nicoleta Nedelcu, Cristian Rugina
Subject: Engineering, Automotive Engineering Keywords: Ricci flow; Ricci solitons; geodesics; seismic waves
The purpose of this paper is to study the sliding mode control as a Ricci flow process in the context of a three-story building structure subjected to seismic waves. The stability conditions result from two Lyapunov- functions, the first associated with slipping in a finite period of time, and the second with convergence of trajectories to the desired state. Simulation results show that the Ricci flow control leads to the minimization of the displacements of the floors. 3D Ricci solitons projection via a semi-conformal mapping to a surface is also studied.
What is in a Viral Stock: Perspectives and Current Limitations of Flow Virometry
Timothy K. Soh, Jens B. Bosse
Subject: Life Sciences, Biochemistry Keywords: HSV-1; HCMV; flow virometry; extracellular vesicles
Herpesviruses produce a plethora of pleomorphic and heterogeneous particle populations. The composition and biological role of these is not understood. Detailed analysis has been challenging due to the lack of multidimensional identification and purification methodologies. Fluorescence-activated cell sorting (FACS), originally developed to sort objects with at least ten thousand-fold larger volumes, has recently been applied to cellular exosomes as well as viral particles and has been dubbed nanoscale flow cytometry or "flow virometry". In comparison to other nanoparticles, herpesvirus concentrations can be measured with high precision using simple culturing methods. Here, we used this unique capability to evaluate a standard FACS sorter. We demonstrate that detection and separation capabilities were insufficient to distinguish infectious fluorescent viral populations from populations lacking fluorescence and infectivity. Moreover, fluorescent populations did not contain single virus particles but mostly aggregates. On top, analysis of viral samples by flow cytometry was confounded by swarm detection, as multiple objects are measured simultaneously and interpreted as a single object. Despite these technical difficulties, comparison of crude supernatant to gradient purified HCMV revealed that infectious virus is a minor proportion of the particles released from infected cells. Our data stress the need for a set of standardized controls and protocols when applying FACS to biological nanoparticles and highlights technical challenges that need to be solved before flow virometry can achieve its full potential.
An Approximate Solution to Prandtl's Equations for a Laminar Flow over an Infinite Horizontal Flat Plate
John Venetis
Subject: Physical Sciences, Mathematical Physics Keywords: boundary layer flow; flat plate; Prandtl's equations
In this paper, a further mathematical analysis of some previous results of the author's ongoing investigation regarding Prandtl's equations is accomplished. In particular, the objective of the present work is the performance of an approximate explicit solution to Prandtl's system of equations for a laminar, isothermal, incompressible and steady boundary layer flow of a Newtonian fluid, over an infinite horizontal flat plate.
Formulated Mathematical Model for Delayed Particle Flow in Cascaded Sub-Surface Water Reservoirs with Validation on River Flow
Ombaki Richard, Kerongo Joash, Okwoyo M. James
Subject: Mathematics & Computer Science, Applied Mathematics Keywords: Particle Flow, Sub-Surface Water, Reservoirs Pollution
Pollution of sub-surface water reservoirs mainly rivers and streams through contaminated water point sources (CWPS) was studied. The objective was to formulate a discrete time delay mathematical model which describes the dynamics of reservoir pollution using mixing-problem processes that involve single species contaminants such as nitrates, phosphorous and detergents. The concentration of pollutants was expressed as a function of the inflow and outflow rates using the principle for the conservation of mass. Systems of ODEs generated from principles of mixing problems were refined into a system of DDEs so that the concentration of pollutant leaving the reservoir at time would be determined at some earlier instant, for the delay. The formulated model is a mathematical discrete time delay model which would be used to describe the dynamics of sub-surface water reservoir pollution. The results from the validation of the model were analyzed to determine how time delays in the mixing processes affect the rate of particle movement in water reservoirs.
Control of Laminar Boundary-Layer Separation Using Steady and Harmonic Vortex Generator Jets
Aria Alimi, Olaf Wünsch
Subject: Engineering, Mechanical Engineering Keywords: laminar separation; flow control; vortex generator jets
Online: 29 October 2018 (11:55:12 CET)
Active flow control of canonical laminar separation bubbles by steady and harmonic vortex generator jets (VGJs) was investigated using direct numerical simulations. Both control strategies were found to be effective in controlling the laminar boundary-layer separation. However, the present results indicate that using the same blowing amplitude, harmonic VGJs were more effective and efficient in reducing the separated region than the steady VGJs considering the fact that the harmonic VGJs use less momentum than the steady case. For steady VGJs, longitudinal structures formed immediately downstream of injection location led to formation of hairpin-type vortices causing an earlier transition to turbulence. Symmetric hairpin vortices were shown to develop downstream of the forcing location for the harmonic VGJs as well. However, the increased control effectiveness for harmonic VGJs flow control strategy is attributed to the fact that shear-layer instability mechanism was exploited. As a result, disturbances introduced by VGJs were strongly amplified leading to development of large-scale coherent structures, which are very effective in increasing the momentum exchange, thus, limiting the separated region.
Carbohydrate Intake Does Not Counter the Post-Exercise Decrease in Natural Killer Cell Cytotoxicity
Laurel M. Wentz, David C. Nieman, Jennifer E. McBride, Nicholas D. Gillitt, Leonard L. Williams, Renaud F. Warin
Subject: Life Sciences, Immunology Keywords: immunity; leukocyte; lymphocyte; flow cytometry; glucose; exercise
Using a randomized, crossover approach, cyclists (N = 20, overnight fasted) engaged in three 75-km time trials while ingesting water (WAT) or carbohydrate (0.2 g/kg every 15 minutes) from bananas (BAN) or a 6% sugar beverage (SUG). Blood samples were collected pre-exercise and 0 h-, 1.5 h-, and 21 h-post-exercise, and analyzed for NK cytotoxicity activity (NKCA) using pure NK cell populations. The two carbohydrate trials (BAN, SUG) compared to WAT were associated with higher post-exercise glucose, and lower cortisol, total blood leukocyte, neutrophil, and NK cell counts (interaction effects, P < 0.001). The immediate post-exercise increase in NK cell counts was higher in WAT (78%) compared to BAN (32%) and SUG (15%) trials (P ≤ 0.017). The 1.5 h post-exercise decrease in NK cell counts did not differ after WAT (−46%), BAN (−46%), and SUG (−51%) trials. The pattern of change in post-exercise NKCA differed between trials (P < 0.001). The 1.5 h post-exercise decreases in NKCA were 23%, 29%, and 33% in the WAT, BAN, and SUG trials, respectively, but trial contrasts did not differ significantly. Carbohydrate ingestion from BAN or SUG attenuated immediate-post-exercise increases in leukocyte, neutrophil, and NK cell counts, but did not counter the 1.5-h decreases in NK cell counts and NKCA.
A Comprehensive Attack Flow Model and Security Analysis for Wi-Fi and WPA3
Christopher P. Kohlios, Thaier Hayajneh
Subject: Mathematics & Computer Science, Information Technology & Data Management Keywords: WPA3; WiFi; attack flow; security analysis; WLAN
The presence of wireless communication grows undeniably more prevalent each year. Since the introduction of the IEEE 802.11 standard for Wireless Local Area Networks (WLAN) in 1997, technologies have progressed to provide wireless accessibility to industries and consumers with growing ease and convenience. As the usage of personal devices, such as phones and watches, that connect to the Internet through Wi-Fi increases, wireless attacks on users are becoming more critical. This paper provides a novel attack model to offer an organized and comprehensive view of the possible attacks on WiFi latest security standards. All exiting attacks will be investigated, with emphasis on more recent attacks, such as the KRACK and PMKID Dictionary attacks. This paper will then analyze the technology offered in the new Wi-Fi Protected Access III (WPA3) security scheme and provide a comprehensive security analysis and discussion to determine whether it has addressed the vulnerabilities of its predecessor. An interesting finding of this paper is that WPA3 still lacks to address all the issues existed in WPA2 and explore other mitigations for future research.
Similarities and Differences in Optimization of Water- and Gas- Distribution Pipeline Networks
Dejan Brkić
Subject: Engineering, Other Keywords: Flow friction, Pipeline networks, Waterworks, Natural gas
Accent is on determination of appropriate friction factor of the pipes and on selection of the representative equation for water or natural gas flow which is valuable for existing conditions in the looped network of pipelines. Note that in a municipal gas pipeline, natural gas can be treated as incompressible fluid (liquid) i.e. as water or oil. Even under this circumstance, calculation of water pipelines cannot be literary copied and applied for calculation of gas pipelines. Inappropriate friction factor, equally as e.g. inappropriate usage of water flow equations for calculation of gas networks can lead to inaccurate final results. Few iterative methods for determining the optimal hydraulic solution of water- and gas- looped pipeline networks, such as, Hardy Cross, modified Hardy Cross, node-loop method, node and M.M. Andrijashev method, will be shown. Speed of convergence will be compared and discussed using a simple network with three loops.
Analysis of the Process Parameter Influence in Laser Cladding of 316L Stainless Steel
Piera Alvarez, M. Ángeles Montealegre, Jose F. Pulido-Jiménez, Jon I. Arrizubieta
Subject: Materials Science, Surfaces, Coatings & Films Keywords: laser cladding; powder flow; 316L stainless steel
Laser Cladding is one of the leading processes within Additive Manufacturing technologies, a fact which has concentrated an important amount of effort on its development. In regard to the latter, the current study aims to summarize the influence of the most relevant process parameters in the laser cladding processing of single and compound volumes (solid forms) made from AISI 316L stainless steel powders and using a coaxial nozzle for deposition. Process speed, applied laser power and powder flow are considered to be the main variables affecting laser cladding in single clads, meanwhile overlap percentage and overlapping strategy become also relevant when dealing with multiple clads. By means of setting appropriate values of each process parameter, the main goal of this paper is to develop a processing window in which a good metallurgical bond between the delivered powder and substrate is obtained, trying simultaneously to maintain processing times in their lowest value possible. Conventional metallography techniques were performed on the cross sections of the laser tracks to measure the effective dimensions of clads for dilution analysis, height and width for the values of overlap between contiguous clads and layers, and also to analyze them for physical defects such as porosity and cracks. The resulting solid piece was 8 mm high at 800 mm/min.
Application of SWAT (Soil and Water Assessment Tool) to the Abay River Basin of Ethiopia: The Case of Didessa Sub Basin
Timketa Adula Duguma
Subject: Engineering, Civil Engineering Keywords: Didessa sub basin; SWAT; simulated stream flow
Abstract: In this study the semi-distributed model SWAT (Soil and Water Assessment Tool), were applied to evaluate stream flow of Didessa sub basin, which is one of the major sub basins in Abay river basin of Ethiopia. The study evaluated the quality of observed meteorological and hydrological data, established SWAT hydrological model, identified the most sensitive parameters, evaluated the best distribution for flow and developed peak flow for major tributary in the sub basin. The result indicated that the SWAT model developed for the sub basin evaluated at multi hydro-gauging stations and its performance certain with the statistical measures, coefficient about determination (R2) and also Nash coefficient (NS) with values ranging 0.62 to 0.8 and 0.6 to 0.8 respectively at daily time scale. The values of R2 and NS increases at monthly time scale and found ranging 0.75 to 0.92 and 0.71 to 0.91 respectively. Sensitivity analysis is performed to identify parameters those were most sensitive for the sub basin. CN2, GWQMN, CH_K, ALPHA_BNK and LAT_TIME are the most sensitive parameters in the sub basin. Finally, the peak flow for 2-10000 returns periods were determined after the best probability distribution is identified in EasyFit computer program.
How Terminal Potentials Determine the Energy Flow in Electric Circuits
Minsu Oh
Subject: Engineering, Electrical & Electronic Engineering Keywords: energy flow in circuits, electromagnetic fields, electromagnetic theories, Kraus and Carver's method, Poynting theorem, Poynting vectors, power flow.
In electric circuits, energy is delivered by electromagnetic fields through the space, as suggested by Kraus and Carver. They provide insights by showing electric/magnetic fields and Poynting vector directions around a DC circuit. In this work, the energy flow mechanism by Kraus and Carver is further studied theoretically for arbitrary terminal potentials of a DC power source.
One-Log Call Iterative Solution of the Colebrook Equation for Flow Friction Based on Padé Polynomials
Subject: Engineering, Other Keywords: Colebrook equation; Colebrook-White; flow friction; iterative procedure; logarithms; Padé polynomials; hydraulic resistances; turbulent flow; pipes; computational burden
The eighty years old empirical Colebrook function widely used as an informal standard for hydraulic resistance relates implicitly the unknown flow friction factor , with the known Reynolds number and the known relative roughness of a pipe inner surface ; . It is based on logarithmic law in the form that captures the unknown flow friction factor in a way from which it cannot be extracted analytically. As an alternative to the explicit approximations or to the iterative procedures that require at least a few evaluations of computationally expensive logarithmic function or non-integer powers, this paper offers an accurate and computationally cheap iterative algorithm based on Padé polynomials with only one -call in total for the whole procedure (expensive -calls are substituted with Padé polynomials in each iteration with the exception of the first). The proposed modification is computationally less demanding compared with the standard approaches of engineering practice, but does not influence the accuracy or the number of iterations required to reach the final balanced solution.
Modeling and Simulation of Passenger Flow Distribution in Urban Rail Transit Hub Platform
Long Gao, Limin Jia
Subject: Mathematics & Computer Science, Computational Mathematics Keywords: passenger flow distribution model; simulation design; performance evaluation; passenger flow volume; service level; urban rail transit hub platform
Urban rail transit hub platform is the most important area for passenger flow distribution. In order to calculate passenger flow volume in platform and evaluate platform service level during rush hours, this paper presents a method for modeling and simulation of passenger flow distribution in platform. Passenger flow distribution model (PFDM) is proposed based on the basic analysis and the superposition principle of passenger flow. Simulation design for PFDM is proposed by Anylogic, which contains simulation process and simulation model. Experiment results show that PFDM and simulation design are effective and accordant with the reality scenario, and the simulation precision is comparatively ideal. This research could provide a beneficial reference for train scheduling and operation management under the viewpoint of traffic safety and service level.
Unified Friction Formulation from Laminar to Fully Rough Turbulent Flow
Dejan Brkić, Pavel Praks
Subject: Engineering, Mechanical Engineering Keywords: Turbulent flow; Laminar flow; Pipes; Friction factor; Hydraulics; Monotonic roughness, Inflectional roughness; Smooth curve contact; Moody diagram; Hydraulic resistance.
This paper gives a new unified formula for the Newtonian fluids valid for all pipe flow regimes from laminar to the fully rough turbulent. It includes laminar, unstable sharp jump from laminar to turbulent, and all types of the turbulent regimes: smooth turbulent regime, partial non-fully developed turbulent and fully developed rough turbulent regime. The formula follows the inflectional form of curves as suggested in Nikuradse's experiment rather than monotonic shape proposed by Colebrook and White. The composition of the proposed unified formula consists of switching functions and of the interchangeable formulas for laminar, smooth turbulent and fully rough turbulent flow. The proposed switching functions provide a smooth and a computationally cheap transition among hydraulic regimes. Thus, the here presented formulation represents a coherent hydraulic model suitable for engineering use. The model is compared to existing literature models, and shows smooth and computationally cheap transitions among hydraulic regimes.
A Review on Electrohydrodynamic (EHD) Pump
Yanhong Peng, Dongze Li, Xiaoyan Yang, Zisu Ma, Zebing Mao
Subject: Engineering, Electrical & Electronic Engineering Keywords: functional fluidic pumps; electrohydrodynamic pumps; flow delivery; robotics
In recent years, functional fluidic electrohydrodynamic (EHD) pumps have attracted considerable attention due to their remarkable features, such as simple structure, quiet operation, and energy-efficient utilization. EHD liquid pumps can be used in various industrial applications, like flow transfer, thermal management, and actuator drive. In this paper, the author reviewed EHD liquid pump research in these specific aspects: the first observation of the EHD effect, its mathematical modeling, and the choice of pump structure, electrode configuration, and working medium. Based on the review, a summary of the development and latest research on EHD pumps can be provided for the readers.
A Novel Physiologically Based Algorithm (PBA) for Fast CFD Computation of Flow Fractional Reserve (FFR) in Coronary Artery Trees
Sholpan Sumbekova, Xiaohui Su, Yong Zhao
Subject: Medicine & Pharmacology, Cardiology Keywords: FFR; Blood Flow Simulation; SimVascular; coronal stenosis; cCTA
A novel physiologically based algorithm (PBA) for fast CFD computation of Flow Fractional Reserve (FFR) in Coronary Artery Trees (CATs) is proposed and developed, which, unlike traditional methods, is based on the extension of the Murray's law for blood vessels at the outlets and extra inlet conditions prescribed alternatively and iteratively. The PBA is then implemented in both SimVascular and Ansys CFD for testing and validation. For validation purpose, 3D models of CATs are built by using their CT images and computational meshes generated for mesh convergence study. Results obtained are then compared with Invasive Coronary Angiographic (ICA) data for validation and evaluation of its accuracy and computational efficiency. It is found that discrepancies between experimental and calculated values of pressure and flow rate at the inlet were less than 0.1% at the end of the 10th round of iteration or less. Further validation shows that the difference between estimated and experimental FFR agree with each other with a maximum difference of 1.62% after convergence is achieved. The PBA is found to be a robust patient-specific and physiologically sound method that can be a good alternative to the existing Lumped Parameter Model (LPM) which is based on empirical scaling correlations using limited population-averaged data and requires nonlinear iterative computation for convergence.
Effect of the Trip-Length Distribution on Network-Level Traffic Dynamics: Exact and Statistical Results
Jorge Laval
Subject: Engineering, Civil Engineering Keywords: Traffic flow, Macroscopic Fundamental diagram, Aggregated network models
This paper presents additional results of the generalized bathtub model for urban networks, including a simpler derivation and exact solutions for uniformly distributed trip lengths. It is shown that in steady state this trip-based model is equivalent to the more parsimonious accumulation-based model, and that the trip-length distribution has merely a transient effect on traffic dynamics, which converge to the same point in the macroscopic fundamental diagram (MFD). To understand the statistical properties of the system, a queueing approximation method is proposed to compute the network accumulation variance. It is found that (i) the accumulation variance is much larger than predicted by traditional queueing models, due to the nonlinear dynamics imposed by the MFD, (ii) the trip-length distribution has no effect on the accumulation variance, indicating that the proposed formula for the variance might be universal, (iii) the system exhibits critical behavior near the capacity state where the variance diverges to infinity. This indicates that the tools from critical phenomena and phase transitions might be useful to understand congestion in cities.
Comparative Analysis of Atterberg Limits, Liquidity Index, Flow Index and Undrained Shear Strength Behavior in Binary Clay Mixtures
Eyyüb Karakan
Subject: Engineering, Civil Engineering Keywords: atterberg limits; fallcone; Casagrande; flow index; clay mineralogy.
In geotechnical engineering applications, it is very important to obtain the undrained shear strength of remolded soils accurately and reliably. This study aims to obtain a trustworthy solution to determine the undrained shear strength of remolded clay mixtures using Atterberg limit test results in various states of consistency. An experimental study was carried out involving a wide range of clay mixtures of varying plasticity and geological origin. In the analyses, the variation of the remolded undrained shear strength depending on the cone penetration depth, water content, flow index, liquidity index and log liquidity index were investigated. In the study, the highest undrained shear strength of 100% Na-montmorillonite (NaM) was obtained at 171.89 kPa at 56.60% water content, while the lowest undrained shear strength was obtained for 100% Sepiolite (S), 9.28 kPa at 31.65% water content. The results of this study revealed that the shear strength is significantly affected by soil conditions, rather than dominant clay mineral. Besides, it was observed that the undrained shear strength at the plastic limit was approximately 30-35 times greater than that at liquid limit. The equations of liquid limit-flow index and plasticity index- flow index were proposed. It was concluded that the interdependence between undrained shear strength, liquidity index, log liquidity index, and flow index is not unique due to the different physical and chemical properties of clays.
Local Morphology and Internal Architecture of the Kawajiricho 2018 Debris-flow Deposit (Hiroshima, Japan)
Christopher Gomez, Kenta Imai, Anggri Muhammad Setiawan, Danang Sri Hadmoko, Junun Sartohadi, Aditya Saputra, Balazs Bradak
Subject: Earth Sciences, Environmental Sciences Keywords: Debris-flow; Hazard; Ground Penetrating Radar; Mountain hazards
Debris-flows are recurrent events on mountain- and hill- slopes, and they have been the object of numerous field investigations and sampling, however most of this work reposes on imagery and outcrop analysis, in such a way that there are still only a handful of studies investigating the internal architecture of these events' deposits. In the present contribution, we aims at underneath the internal structure of a portion of a debris-flow deposit that was accessible in the aftermath of the 2018 heavy-rainfall debris-flows in Hiroshima Japan. Using a Ramac Pro-Ex GPR with 500 MHz and 800 MHz antenna, a set of longitudinal and transversal transects was used to characterize the deposit. The results demonstrated that a set of subhorizontal layers have filled the valley, and interacting with local terrace edges, these layers have piled up and overcome the obstacle. Across the valleys, a set of trough suggest the presence of channels that were also filled during the event. Finally, in the channel post-event, a set of radargram "cross-bedded units" shows that the final deposition in the channel was of a more dilute flow, typical of a Newtonian flow. This set of units was not to be found at the surface of the post-event pseudo-surface, suggesting that the flow ended as a debris-flow on this surface, and that it is only when the flow dug the final channel that the nature of the flow returned from debris-flow to Newtonian flow.
Structural Analysis of Fluid Flow in Complex Biological Systems
Robert Eisenberg
Subject: Biology, Physiology Keywords: Fluid flow; conservation laws; Bidomain model; glymphatic system
Biology is about structure. Structures within structures. Organs within animals, tissues within organs, cells within tissues, and molecules, often proteins within cells. The structures are so complex that they can only be described by numbers. No numbers are of more importance than those that describe proteins. The numbers that describe coordinates of its atoms, often determined by Patterson functions (which are inverse Fourier Transforms of intensities) of crystal diffraction. Without these numbers, structural biology would hardly exist. Without numbers, engineering would not exist. Numbers are surely needed by the engineers who produce the x-rays diffracting from atoms of protein crystals. Devices of engineering have function. They are built to implement equations. Engineering devices use structures to implement equations, when power is supplied at the right places, that produces appropriate flows. Flows are the essence of life. Equilibrium means death in most living systems. Flows in biological structures are hard to analyze because we do not know input output equations in advance. Sometimes we do not know their function. Flows, forces, and structures of life (like those of engineering) are related by field equations of conservation laws, partial differential equations, constrained by location and properties of structures. Constraints are boundary conditions located on the complicated domain of biological structure. Dealing with this complexity is simplified if one systematically analyzes structure using the most general field theory known, electricity described by the Maxwell equations, without significant known error. Currents are involved because flows of biology usually involve migration of charges, convection of water and solutes, diffusion of ions that form the plasma of life, and their interactions. Interactions can dominate function. Here I show how a few complex structures can be understood in engineering detail. This approach may be useful in dealing with biological and medical issues in many other cases. In one limited case—the clearance of a toxic waste (potassium ions) from the optic nerve—this approach seems to have succeeded.
Cancer Immunotherapy Biomarkers of Response and Toxicity; Current Limitations and Future Promise
Brian Richard Healey Bird, Ken Nally, Karine Ronan, Gerard Clarke, Sylvie Amu, Anna S. Almeida, Richard Flavin, Stephen Finn
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: cancer; immunotherapy; biomarker; microenvironment; microbiome; flow cytometry; cytokine
Immune Checkpoint Inhibitors are monoclonal antibodies that are used to treat over one in three cancer patients. While they have changed the natural history of disease, prolonging life and preserving quality of life, they are highly active in less than 40% of patients, even in the most responsive malignancies such as melanoma, and cause significant autoimmune side effects. Licenced biomarkers include tumour Programmed Death Ligand 1 expression by immunohistochemistry, microsatellite instability, and Tumour Mutational Burden, none of which are particularly sensitive or specific. Emerging tumour and immune tissue biomarkers such as novel immunohistochemistry scores, tumour, stromal and immune cell gene expression profiling, and liquid biomarkers such as systemic inflammatory markers, kynurenine/tryptophan ratio, circulating immune cells, cytokines and DNA are discussed in this review. We also examine the influence of the faecal microbiome on treatment outcome and its use as a biomarker of response and toxicity.
Estimation of Lane-Level Traffic Flow by Using Deep Learning Technique
Chieh-Min Liu, Jyh-Ching Juang
Subject: Mathematics & Computer Science, Algebra & Number Theory Keywords: traffic flow; object detection; object tracking; deep learning
This paper proposes a neural network which fuses the data received from a camera system on a gantry, to detect moving objects and calculate relative position and velocity of the vehicles traveling on a freeway, this information is used to estimate the traffic flow. To estimate the traffic flow at both microscopic and macroscopic view, this paper used YOLO v4 and DeepSORT for vehicle detection and tracking, then counting the number of vehicles pass through the freeway by drawing virtual lines and hot zones, also counting the velocity of each vehicles. The information is then pass to the traffic control center, in order to monitoring and control traffic flow on freeways, and analyzing freeway conditions.
Hot-Air Extermination of Insects: The Only Sustainable Method for Historical Timber Constructions
Jaroslav Solar, Petr Alexa
Subject: Engineering, Automotive Engineering Keywords: wooden structures; wood-borer; thermal flow; listed buildings
Wood-borer extermination by a dry heat clean-up is the essential method from the point of view of sustainability of historical wooden structures like trusses and ceilings in heritage-listed buildings. The wooden components are heated by a hot air of temperature about 100°C until the temperature in the centre of the wooden structures reaches 55°C to kill the wood-borers. In this article we review the method and present solution of the heat equation for structural wooden components. We also suggest an approximate formula that enables to estimate the necessary heating time for different cross sections of wooden components and can be used in technical application of the method.
Microwave Extraction vs. Other Techniques for Industrial Scale Cannabis Extraction
Marilena Radoiu, Harmandeep Kaur, Anna Bakowska-Barczak, Steven Splinter
Subject: Chemistry, Applied Chemistry Keywords: cannabis; THC; CBD; microwave assisted extraction; continuous flow
Cannabis is a flowering plant that has long been used for medicinal, therapeutic, and recreational purposes. Cannabis contains more than 500 different compounds, including a unique class of terpeno-phenolic compounds known as cannabinoids; Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are the most prevalent cannabinoids and have been associated with the therapeutic and medicinal properties of the cannabis plant. In this paper, continuous flow microwave assisted extraction (MAE) is presented and compared with other methods for commercial cannabis extraction. The practical issues of each extraction method are discussed. The main advantages of MAE are: continuous-flow method which allows for higher volumes of biomass to be processed in less time than existing extraction methods, improved extraction efficiency leading to increased final product yields, improved extract consistency and quality because the process does not require stopping and restarting material flows, and ease of scale-up to industrial scale without the use of pressurised batch vessels. Moreover, due to the flexibility of changing the operation conditions, MAE eliminates additional steps required in most extraction methods, such as biomass decarboxylation, winterisation, which typically adds at least a half day to the extraction process. Another factor that sets MAE apart is the ability to achieve high extraction efficiency even at the industrial scale. Whereas the typical recovery of active compounds using supercritical CO¬2 remains around 70-80%, via MAE up to 95% of the active compounds from cannabis biomass can be recovered at the industrial scale.
Speciation in Stickleback Facilitated by Admixture – Where is the Evidence?
Daniel Berner
Subject: Biology, Animal Sciences & Zoology Keywords: evolutionary genomics; Gasterosteus aculeatus; gene flow; hybridization; phylogeny
Where genetic variation promoting speciation originates is a crucial question in evolutionary genomics. In a recent article, Marques et al. (2019) seek to address this question in lake and stream threespine stickleback fish from the Lake Constance (hereafter LC) basin in Central Europe. Based on population genetic methods, they conclude that incipient speciation between lake and stream stickleback was facilitated by the mixing of genetic variation from old lineages evolved in isolation (i.e., admixture following secondary contact). In this comment, I discuss conceptual and methodological problems and unrecognized conflicts with existing evidence that cast doubt on Marques et al.'s conclusion.
Preprint CONCEPT PAPER | doi:10.20944/preprints202004.0381.v1
Hydroxychloroquine for the Treatment of COVID-19: Evidence, Possible Mode of Action and Industrial Supply of the Drug
Mario Pagliaro, Francesco Meneguzzo
Subject: Life Sciences, Virology Keywords: hydroxychloroquine; COVID-19; immunomodulator; cytokine storm; flow chemistry
Hydroxychloroquine, a known antiviral metabolite of chloroquine, is increasingly used along with antibiotic azithromycin for the treatment of COVID-19 infection. In about one month India, the world's largest manufacturer, delivered hydroxychloroquine for treating COVID-19 to over 50 countries. The therapy is being used across the world both for patients staying at home at the early phase of symptoms, as well as for patients hospitalized. We summarize achievements as of late April 2020, review possible modes of action and suggest avenues for the quick scale-up of production of hydroxychloroquine.
The Energetics of the an ExB Propulsor That Avoids the Hidden Momentum Pitfall
Remi Cornwall
Subject: Physical Sciences, General & Theoretical Physics Keywords: momenergy; static Poynting vector flow; zeropoint; ion propulsion
This paper updates earlier thoughts by the author on a putative electromagnetic propulsion system, to perform a more detailed energy balance. The previous paper demonstrated how momentum could be dumped to the ground state of the electromagnetic field but a claim was left somewhat hanging at the end of the previous paper, that the work done in changing the craft's velocity would effectively shift the centre of mass of the field - although that would be an infinitesimal shift in practice. The craft must always supply work to change velocity, such as by an accelerate/de-accelerate cycle and superficially this looks to violate the conservation of energy; we prove that this isn't so.
Heterogeneous Catalysis Under Flow for the 21st Century Fine Chemical Industry
Rosaria Ciriminna, Mario Pagliaro, Rafael Luque
Subject: Chemistry, Organic Chemistry Keywords: heterogeneous catalysis, flow chemistry, green chemistry, fine chemicals
Due to metal leaching and poor catalyst stability, the chemical industry's fine chemical and pharmaceutical sectors have been historically reluctant to use supported transition metal catalysts to manufacture fine chemicals and active pharmaceutical ingredients. With the advent of new generation supported metal catalysts and flow chemistry, we argue in this study, this situation is poised to quickly change. Alongside heterogenized metal nanoparticles, both single-site molecular and single-atom catalyst will become ubiquitous. This study offers a critical outlook taking into account both technical and economic aspects.
Assimilation of Synthetic SWOT River Depths in a Regional Hydrometeorological Model
Vincent Häfliger, Eric Martin, Aaron Boone, Sophie Ricci, Sylvain Biancamaria
Subject: Earth Sciences, Other Keywords: overland flow, satellite altimetry, hydrological modelling, data assimilation
The Surface Water and Ocean Topography (SWOT) mission, to be launched in 2021, will provide water surface elevations, slopes, and river width measurements for rivers wider than 100 m. In this study, synthetic SWOT data are assimilated in a regional hydrometeorological model in order to improve the dynamics of continental waters over the Garonne catchment, one of the major French catchments. The aim of this paper is to demonstrate that the sequential assimilation of SWOT-like river depths allows the correction of river bed roughness coefficients and thus simulated river depths. An extended Kalman Filter is implemented and the data assimilation strategy was applied to four experiments of gradually increasing complexity regarding observation and model error over the 1995-2000 period. With respect to a "true" river state, assimilating river depths allows the proper retrieval of constant and spatially distributed roughness coefficients with a root mean square error of 1 m1/3 s-1, and the estimation of associated river depths. It was also shown that river depth differences can be assimilated, resulting in a higher root mean square error for roughness coefficients with respect to the true river state. The last study shows how one can take into account more realistic sources of SWOT error measurements, in particular the importance of the estimation of the tropospheric water content in the process.
A Long Short-term Traffic Flow Prediction Method Optimized by Cluster Computing
Boyi Liu, Jieren Cheng, Qiang Liu, Xiangyan Tang
Subject: Engineering, Electrical & Electronic Engineering Keywords: traffic flow forecasting; cluster computing; LSTM neural networks
Accurate and fast traffic flow forecasting is vital in intelligent transportation system because many of the advanced features in intelligent transportation systems are based on it. However, existing methods have poor performance regarding accuracy and computational efficiency in long-term traffic flow forecasting under big data. Hence, we propose an improved Long short-term memory (LSTM) Network and its cluster computing implementation in this paper to address the above challenge. We propose a singular point probability LSTM (SDLSTM) algorithm. The method discards the units of the network according to the singular point probability during the training process and amends the SDLSTM by Autoregressive Integrated Moving Average Model (ARIMA) to achieve the accurate prediction of 24-hour traffic flow data. Furthermore, the paper designs a scheme for implementing this method through cluster computing to shorten the calculation time and improve the system's operating speed. Theoretical analysis and experimental results show that SDLSTM gains a higher accuracy rate and better stability in the long-term traffic flow forecasting compared with previous methods.
Continuous High-Flow System to Trap and Separate Magnetic Particles from Liquid Mixtures
Georgios Banis, Maria Elisavet Kouli, Evangelos Hristoforou, Angelo Ferraro
Subject: Engineering, Other Keywords: Bio-separation, magnetic separation, magnetic particles, continuous-flow
Bio-separation of natural molecules as well as clinical compounds has been constantly developed in last decades. Several techniques are available but the majority of them presents drawbacks such us impossibility to be applied for industrial purposes. The main limitations for the scaling up are high costs and the fact that the devices work with microfluid dynamics. Nevertheless, magnetic bio-separation is considered the most prone to be used for large scale applications. Herein, we propose a simple magnetic separation method that is not based on microfluid dynamics, can work in a continuous- and high-flow rate and can be easily automated in order to be used for standard separation purposes. It is based on the use of an anisotropic flexible ferric magnetic strip, Teflon hoses and a pumping device. We show the modelling of the separation process along with an experimental test on iron oxide magnetic particles. The results showed that it is possible to remove, and separately collect, more than 92% of magnetic particles from a liquid solution of 100 ml in roughly 15 minutes.
Numerical Investigations of Blade Shape Effects on the Flow Characteristics in a Stirred Dead-End Membrane Bioreactor
Xu-Qu Hu, Xing-Yi Wang, Xiu-Cheng Lei, Xiang Qiu, Lin-Feng Chen
Subject: Engineering, Biomedical & Chemical Engineering Keywords: turbulent flow; stirred flows; membrane fouling; membrane bioreactor
Numerical simulations of turbulent flows in a stirred dead-end membrane bioreactor are performed by the RNG k-ε model based on finite volume method using Fluent codes. Comparisons of numerical and experimental results confirm the reliability and feasibility of the constructed model. Flow structures such as wake flows and circulation loops in stirred flows were well simulated. An increase of stirring speed is proposed to use to minimize the low velocity region. The single vane stirrer is found to be beneficial for biological separations. Results reveal that the increase of vane number can enhance the mixing effect in flow domains. However, a circular disk stirrer goes against the formation of vertical circulations. The six-vane stirrer is found to be able to provide a uniform distribution of high shear stress.
Closed-form expression for the dynamic dispersion coefficient in Hagen-Poiseuille flow
Lichun Wang, M. Bayani Cardenas
Subject: Earth Sciences, Environmental Sciences Keywords: solute transport, dispersion, hagen-poiseuille flow, non-fickian
We present an exact expression for the upscaled dynamic dispersion coefficient (D) for one-dimensional transport by Hagen-Poiseuille flow which is the basis for modeling transport in porous media idealized as capillary tubes. The theoretical model is validated by comparing the breakthrough curves (BTCs) from a 1D advection-dispersion model with dynamic D to that from direct numerical solutions utilizing a 2D advection-diffusion model. Both Taylor dispersion theory and our new theory are good predictors of D at lower Peclet Number (Pe) regime, but gradually fail to capture most parts of BTCs as Pe increases. However, our model generally predicts the mixing and spreading of solutes better than Taylor's theory since it covers all transport regimes from molecular diffusion, through anomalous transport, and to Taylor dispersion. The model accurately predicts D based on the early part of BTCs even at relatively high Pe regime (~62) where the Taylor's theory fails. Furthermore, the model allows for calculation of the time scale that separates Fickian from non-Fickian transport. Therefore, our model can readily be used to calculate dispersion through short tubes of arbitrary radii such as the pore throats in a pore network model.
Development of SWAT-PADDY for Simulating Lowland Paddy Fields
Ryota Tsuchiya, Tasuku Kato, Jaehak Jeong
Subject: Earth Sciences, Environmental Sciences Keywords: SWAT; model development; paddy fields; irrigation; return flow
The consumption of rice, which recently increases globally, leads to requirement for planning sustainable water management for paddy cultivation. In this research, SWAT model was modified to evaluate sustainability of paddy cultivation. Modifications to simulate paddy cultivation are 1) to equip with a new water balance model of impounded fields, 2) to add an irrigation management option for paddy fields, which is characterized by flood irrigation managed by farmers on a daily basis, 3) to consider puddling operation that influences water quality and infiltration rate of soil. The enhanced model, named SWAT-PADDY, was applied to an agricultural watershed in Japan as a case study. The modified model succeeded in representing paddy cultivation in the study area. However, SWAT-PADDY underestimated base flow in irrigation period. The cause of this is inferred that the modified model doesn't represent return flow of excess withdrawal of river water. In conclusion, addition of the models of impoundment and management practices in paddy fields to SWAT improved field scale simulation of water balance and irrigation in paddy fields. However, further improvement of the model on irrigation return flow process is needed to better predict hydrology of watersheds dominated by paddy irrigation.
Techno-Economic Modeling and Analysis of Redox Flow Battery Systems
Jens Noack, Lars Wietschel, Nataliya Roznyatovskaya, Karsten Pinkwart, Jens Tübke
Subject: Engineering, Energy & Fuel Technology Keywords: redox flow battery; techno-economic analysis; materials; cost
A techno-economic model was developed to investigate the influence of components on the system costs of redox flow batteries. Sensitivity analyses were carried out based on a example of a 10 kW/120 kWh vanadium redox flow battery system and the costs of the individual components were analyzed. Particular consideration was given to the influence of material costs and resistances of bipolar plates and energy storage media as well as voltages and electric currents. Based on the developed model it was possible to formulate statements about the targeted optimization of existing battery systems and general aspects for future developments of redox flow batteries.
Electrode Cooling Effect on Out-of-Phase Electrothermal Streaming in Rotating Electric Fields
Weiyu Liu, Yukun Ren, Ye Tao, Xiaoming Chen, Qisheng Wu
Subject: Physical Sciences, Fluids & Plasmas Keywords: electrothermal flow; rotating electric field; out-of-phase smeared structural polarization; electrode cooling; external natural convection; co-field flow rotation
In this work, we focus on investigating electrothermal flow in a rotating electric field (ROT-ETF), with primary attention paid to the horizontal traveling-wave electrothermal (TWET) vortex induced at the center of the electric field. The frequency-dependent flow profiles in the microdevice are analyzed using different heat transfer models. Accordingly, we address in particular the importance of electrode cooling in ROT-ETF as metal electrodes of high thermal conductivity while substrate material of low heat dissipation capability are employed to develop such microfluidic chips. Under this circumstance, cooling of electrode array due to external natural convection on millimeter-scale electrode pads for external wire connection occurs and makes the internal temperature maxima shift from the electrode plane to a bit of distance right above the cross-shaped interelectrode gaps, giving rise to reversal of flow rotation from a typical repulsion-type to attraction-type induction vortex, which is in good accordance with our experimental observations of co-field TWET streaming at frequencies on the order of reciprocal charge relaxation time of the bulk fluid. These results point out a way to make a correct interpretation of out-of-phase electrothermal streaming behavior, which holds great potential for handing high-conductivity analytes in modern microfluidic systems.
Mediators of Regional Kidney Perfusion during Surgical Pneumoperitoneum Creation and the Risk of Acute Kidney Injury – A Review of Basic Physiology
Csaba Kopitkó, László Medve, Tibor Gondos, Karim Magdy Mohamed Soliman, Tibor Fülöp
Subject: Medicine & Pharmacology, General Medical Research Keywords: acute kidney injury; intra-abdominal pressure; oxidative stress; renal cortical blood flow; renal medullar blood flow; renal lymphatic drainage; venous congestion
Acute kidney injury (AKI), especially if recurring represents a risk factor for future chronic kidney disease. In intensive care units, increased intraabdominal pressure is well-recognized as a significant contributor of AKI. However, the importance of transiently increased intra-abdominal pressures procedures is less commonly appreciated during laparoscopic surgery, the use of which has rapidly increased over the last few decades. Unlike the well-known autoregulation of the renal cortical circulation, medulla perfusion is modulated via partially independent regulatory mechanisms and strongly impacted by changes in venous and lymphatic pressures. In our review paper, we will provide a comprehensive overview of this evolving topic, covering a broad range from basic pathophysiology up to and including current clinical relevance. Key regulators of oxidative stress such as ischemia-reperfusion injury, the activation of inflammatory response and humoral changes interacting with procedural pneumoperitoneum formation and AKI risk will be recounted. Moreover, we present an in-depth review of the interaction of pneumoperitoneum formation with general anesthetic agents and animal models of congestive heart failure. A better understanding of the relationship between pneumoperitoneum formation and renal perfusion will support basic and clinical research, leading to improved clinical care and collaboration among specialists.
Working Paper TECHNICAL NOTE
Application of Flow-Virometry for Large-Scale Screening of COVID 19 Cases
Niraja Soni, Puja Pai, Raja Krishna Kumar G., Venkatesh Prasad, Santanu Dasgupta, Bhaskar Bhadra
Subject: Biology, Anatomy & Morphology Keywords: COVID-19; Severe acute respiratory syndrome (SARS); SAR-CoV-2; flow cytometry; flow virometry; viral particles; herpes simplex virus; HSV; nanoparticles
The coronavirus disease caused by SARS-CoV-2 (known as COVID 19) is highly contagious and has spread rapidly over 200 countries over last three months. WHO suggested urgent escalation in testing, isolation and contact tracing, as the "backbone" of managing the pandemic. Globally, the detection of SARS-CoV-2 in patients are done by RT-PCR and blood antibody-based testing. In addition to the existing processes, flow-cytometry could be used as a high-throughput and efficient diagnostic method for detection of COVID 19. The suspected COVID 19 samples can be analyzed using 'Indirect flow cytometry', with the specific primary antibody and fluorescent tagged secondary antibodies. The fluorescence signal can distinguish the infected v/s non-infected samples. In the present article, we have summarized the applications of Flow virometry to study various viruses and have proposed possible application in the detection of COVID 19.
Risk Factors of Cannula-associated Arterial Thrombosis following Extracorporeal Membrane Oxygenation support: A Retrospective Study
Ngan Hoang Kim Trieu, Xuan Thi Phan, Linh Thanh Tran, Huy Minh Pham, Dai Quang Huynh, Tuan Manh Nguyen, Anh Tuan Mai, Quan Quoc Minh Du, Bach Xuan Nguyen, Thao Thi Ngoc Pham
Subject: Medicine & Pharmacology, Cardiology Keywords: extracorporeal membrane oxygenation; cannula-associated arterial thrombosis; flow rate.
Introduction: Hemostatic dysfunction during extracorporeal membrane oxygenation (ECMO) due to blood-circuit interaction and the consequences of shear stress by flow rates lead to rapid activation of the coagulation cascade and thrombus formation in the ECMO system and blood vessels. In this study, we aimed to identify the incidence and risk factors for cannula-associated arterial thrombosis (CaAT) post-decannulation. Methods: A retrospective study of patients undergoing arterial cannula removal following ECMO. We evaluated the incidence of CaAT and compared clinical characteristics, pre-ECMO severity, and daily hemostasis parameters in patients with and without CaAT. Multivariate analysis revealed the risk factors for CaAT. Results: Forty-seven patients requiring venoarterial ECMO or hybrid methods were recruited to be screened for thrombosis. The median SOFA score was 11 (8-13). CaAT occurred in 29 patients (61.7%), with thrombosis in the superficial femoral artery accounting for 51.7%. Limb ischemia complications in the group with CaAT was 17.2%. In multivariate analysis, an ECMO flow rate of 100 mL/min was determined to be the independent factor for CaAT with an OR of 0.84 (95% CI, 0.73–0.95, p=0.008). Conclusion: In patients successfully weaned from ECMO, the incidence of CaAT was 61.7%. Our study found that a low-flow rate of ECMO was an independent risk factor for CaAT.
Antiparasitic effect of Farnesol against Leishmania major: a rationale from in vitro and in silico investigations
Harshita Sharma, Rakesh Sehgal, Nishant Shekhar, Upninder Kaur, Bikash Medhi
Subject: Life Sciences, Microbiology Keywords: Leishmania major; Sesquiterpene; in silico; in vitro; Flow Cytometry
Leishmaniasis is a vector-borne parasitic infection caused by the bite of female Phlebotomine sandflies. World Health Organization (WHO) estimates 100,000 cases to be reported annually on a global scale, moreover, 13 million people were infected between 2010 and 2015 worldwide. Treatment of leishmaniasis by conventional synthetic compounds is met by challenges pertaining to adverse effects which call for the discovery of newer anti-leishmanial molecules. This study was performed to evaluate the effect and modes of action of a sesquiterpene alcoholic molecule Farnesol on Leishmania major, the causative agent of Zoonotic Cutaneous leishmaniasis. The cytotoxic effect of Farnesol against L. major promastigotes, amastigotes and macrophages was assessed by MTT test and counting. The IC50 on promastigotes by Farnesol on L. major was evaluated by flow cytometry. In the findings, Promastigotes were reduced at 167 µM/mL & the mean numbers of L. major amastigotes in macrophages were significantly decreased in exposure to Farnesol at 172 µM/ml. In addition, Farnesol demonstrated no cytotoxicity on macrophages as the IC50 value was 945 µM/ml; it induced significant apoptosis dose-dependent on L. major promastigotes. In silico protein-ligand binding analyses indicated the effect of Farnesol in perturbation of the ergosterol synthesis pathway of Leishmania with attributes suggesting inhibition of Lanosterol-α-demethylase, the terminal enzyme of ergosterol synthesis machinery. Findings from flow cytometry reveal the role of farnesol in apoptosis-induced killing in promastigotes. Farnesol was effective at very lower concentrations when compared to Paromomycin. Further studies are crucial to evaluate the therapeutic potentials of Farnesol alone and in combination with other conventional drugs using clinical settings.
Development of a Novel Anti-CD44 Variant 4 Monoclonal Antibody, C44Mab-108
Hiroyuki Suzuki, Tomohiro Tanaka, Teizo Asano, Nohara Goto, Mika K. Kaneko, Yukinari Kato
Subject: Medicine & Pharmacology, Pathology & Pathobiology Keywords: CD44; CD44 variant 4; monoclonal antibody; flow cytometry; immunohistochemistry
CD44 has been known as a marker of tumor initiating cells, and plays pro-tumorigenic functions in many cancers. The splicing variants play critical roles in malignant progression of cancers by promoting the stemness, cancer cell invasion or metastasis, and resistance to chemo- and radiotherapy. To understand each CD44 variant (CD44v) function is essential to know the property of cancers and establishment of the therapy. However, the function of the variant 4-encoded region has not to be elucidated. Therefore, specific monoclonal antibodies (mAbs) against the variant 4 are indispensable for basic research, tumor diagnosis, and therapy. In this study, we established anti-CD44 variant 4 (CD44v4) monoclonal antibodies (mAbs) by immunizing mice with a peptide containing the variant 4-encoded region. We next performed flow cytometry, western blotting, and immunohistochemistry to characterized them. One of the established clones (C44Mab-108; IgG1, kappa) reacted with CD44v3-10-overexpressed Chinese hamster ovary-K1 cells (CHO/CD44v3-10). The KD of C44Mab-108 for CHO/CD44 v3-10 was 3.4 × 10−7 M. In western blot analysis, C44Mab-108 detected CD44v3-10 in the lysate of CHO/CD44v3-10 cells. Furthermore, C44Mab-108 stained formalin-fixed paraffin-embedded oral squamous carcinoma tissues in immunohistochemistry. These results indicated that C44Mab-108 is useful to detect CD44v4 in various applications.
ALCAM: A Novel Surface Marker on EpCAMlow Circulating Tumor Cells
Harrys Kishore Charles Jacob, Rossana Signorelli, Teresa Maidana Giret, Oliver Umland, Marco Hadisurya, Shweta Lavania, Charles Richard John Lalith, Ashley Nicole Middleton, Belinda Minucci Boone, Ayse Burcu Ergonul, Weiguo Andy Tao, Haleh Amirian, Anton Iliuk, Aliya Mahmood Khan, Robert Alexander Diaz, Daniel Bilbao Cortes, Monica Tulia Garcia-Buitrago
Subject: Biology, Other Keywords: Biomarkers; Pancreatic Cancer; CTC; Surfaceome; Protemics; Flow Cytometry; ALCAM
Background: Current strategies in circulating tumor cell (CTC) isolation in pancreatic cancer heavily rely on the EpCAM and cytokeratin cell status. EpCAM is generally not considered as a good marker given its transitory change during Epithelial to Mesenchymal Transition (EMT) or reverse EMT. There is a need to identify other surface markers to capture the complete repertoire of PDAC CTCs. The primary objective of the study is to characterize alternate surface bi-omarkers to EpCAM on CTCs that express low or negligible levels of surface EpCAM in pancre-atic cancer patients. Methods: Flow cytometry and surface mass spectrometry were used to iden-tify proteins expressed on the surface of PDAC CTCs in culture. CTCs were grown under condi-tions of attachment and in co-culture with naïve neutrophils. Putative biomarkers were then validated in GEMMs and patient samples. Results: Surface proteomic profiling of CTCs identi-fied several novel protein biomarkers. ALCAM was identified as a novel robust marker in GEMM models and in patient samples. Conclusions: We identified several novel surface bi-omarkers on CTCs expressed under differing conditions of culture. ALCAM was validated and identified as a novel alternate surface marker on EpCAMlow CTCs.
Closed Form Solution of Plane-Parallel Turbulent Flow Along an Unbounded Plane Surface
Subject: Physical Sciences, Fluids & Plasmas Keywords: turbulent flow; Prandtl mixing length; Reynolds number; boundary layer
A century-old scientific conundrum is solved in this paper. The Prandtl mixing length modelled plane boundary turbulent flow is described by: $\frac{du^+}{d{y^+} }+\kappa^2{y^+} ^2\left( \frac{du^+}{d{y^+} }\right)^2=1$, together with boundary condition $ {y^+} =0:\, u^+=0$. Only an approximate solution to this nonlinear ordinary differential equation (ODE) has been sought so far, however, the exact solution to this ODE has not been obtained. By introducing a transformation, $2\kappa y^+=\sinh \xi$, I successfully find the exact solution of the ODE as follows: $u^+=\frac{1}{\kappa}\ln(2\kappa {y^+} +\sqrt{1+4\kappa^2{y^+} ^2})-\frac{2{y^+} }{1+\sqrt{1+4\kappa^2{y^+} ^2}}$.
Aerodynamic Shape and Drag Scaling Laws of Flexible Fibre in Flowing Medium
Bohua Sun, Xiao-Lin Guo
Subject: Physical Sciences, Applied Physics Keywords: flexible fibre; flow medium; aerodynamic shape; drag; scaling laws
The study of a flexible body immersed in a flowing medium is one of best way to find its aerodynamic shape. This Letter revisited the problem first studied by Alben, Shelley and Zhang (Nature 420, 479-481, 2002). The aerodynamic shape of the fibre is found by simpler approach and universal drag scaling laws of the flexible fibre in flowing medium are proposed by using dimensional analysis. The Alben scaling laws is being generalized and confirmed to be universal. Our study show that the Alben number is a measurement of maximum curvature of the fibre forced by dynamic pressure. A complete Maple code is provided for finding aerodynamic shape of the fibre in the flowing medium.
Living Cell's Feeling of Holes: The Mathematics of Cavities in Biophysical Structures
Arturo Tozzi
Subject: Life Sciences, Biophysics Keywords: nanovesicles; flow; homology; vortex; Betti number; Borsuk–Ulam theorem
Mechanical properties such as shape, volume and size affect the dynamics of biological systems. Most of the current methodological approaches are inclined to remove the existence of holes and impurities from systems' description, regarding them as routes toward mechanical failure. On the contrary, we suggest that the occurrence of holes might be of utmost functional importance, allowing reversible transformations of cellular structures. The focus here is on the widespread occurrence of intracytoplasmic holes, that deeply modifies the topology of living cells and provides researchers with novel operational tools to investigate intracellular dynamics. We take as example the prokaryotic gas vesicles, i.e., intracellular cavities filled with gases spreading from the nearby medium. The mechanical and topological cellular properties dictated by intracytoplasmic holes are investigated, focusing on the physical constraints imposed by their very existence. For instance, the presence of gas vesicles breaks the cytoplasmic homogeneity, leading to inhomogeneity in functional activities and modifications in intracellular flows. Also, a topological approach to cytoplasmic holes suggests novel physiological roles for gas vesicles. For example, the gas vesicles' ability to increase/decrease cellular volumes provides a mechanism that counteracts the detrimental effects of the surface/volume ratio. In conclusion, a structural/methodological approach based on the occurrence of holes testifies once again how the simple biophysical structure alone can dictate the function.
The Effects of Orientation and Width of Space Between Buildings on Ventilation of High-Rise Areas
Seyedeh Azadeh Aghajanzadeh, Seyed Morteza Hosseini, Mojtaba Lorzangeneh, Mohsen Taban
Subject: Engineering, Other Keywords: High-rise Building; Urban Ventilation; Wind Flow; CFD; Babolsar
In recent years, excessive heat in the urban texture has become the main problem in the humid and calm wind city of Babolsar with high density, especially in high-rise areas. Therefore, in order to create comfort in this region, it is necessary to establish and continue the wind circulation in space with an environmentally compatible and optimal configuration. The study applies combination of literature, field measurement, experimental validation of CFD simulation output, and comparative analysis. After field measurement and validation of FLOW-3D simulation software (V11.2.2), the relationship between these parameters (height, the width of passages, enclosure between buildings, and buildings' orientation) will be studied which affects the wind's velocity and direction. The factors of the buildings' orientation and enclosure based on the passages' width have opposite reactions in the direction of the prevailing wind especially from perpendicular side. In this study, two effective factors are on wind velocity: 1- The orientation of the buildings towards the wind flow by creating permeability 2- Reducing the enclosure by increasing the width of the passage's perpendicular to the wind flow (w '= 3w, E' = 0.33E). According to the theoretical and practical study, first, the creation of permeability in the body of the block and the separation of buildings instead of aggregation has been studied, and then reducing the confinement of streets perpendicular to the wind flow has been discussed as effective solutions to improve the wind velocity and circulation between the urban environment.
Superb Microvascular Imaging as a Novel Tool for the Assessment of Blood Flow Velocity in Patients with Systemic Sclerosis: A Single-Center Feasibility Study
Jan-Gerd Rademacher, Rosa Marie Buschfort, Thomas Asendorf, Viktor Korendovych, Björn Tampe, Peter Korsten
Subject: Medicine & Pharmacology, Other Keywords: Systemic Sclerosis; Raynaud's phenomenon; ultrasound; microvascular imaging; blood flow
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Systemic sclerosis is an autoimmune disease characterized by organ fibrosis and vasculopathy. Almost all patients suffer from Raynaud's phenomenon (RP). Currently, several imaging techniques are available; nailfold video capillaroscopy (NVC) is the most widely available, but flow quantification is not possible with NVC. Novel imaging techniques are of interest in this population. We performed a single-center feasibility study using Micro Vascular Imaging (MVI) as a novel imaging technique for flow quantification of small fingertip vessels. We compared a group of 20 healthy controls (HCs) with 20 Systemic Sclerosis (SSc) patients. In HCs, flow measurements assessed with MVI were statistically significantly higher in individual fingers and combined for all fingers (p&lt;0.0001). As a cut-off value to discriminate HCs from SSc, a peak systolic (PS) flow velocity of &lt;6.9 cm/s and an end-diastolic (ED) flow velocity of &lt;2.68 cm/s was determined. Test characteristics for PS flow velocity showed moderate sensitivity (0.69, 95% CI 0.58-0.78) but high specificity (0.88, 95% CI 0.79-0.93). Similar test characteristics for ED flow velocity were obtained. The optimal cut-off point was estimated at &lt;2.68 cm/s, sensitivity was moderate (0.65, 95% CI 0.53-0.75), specificity was 0.80 (95% CI 0.70-0.87). Here, we present the first study on the use of MVI to assess blood flow in the fingertips with high specificity in SSc patients. Future studies need to investigate correlations with the risk for organ complications, such as digital ulcers or pulmonary arterial hypertension.
Autologous Gradient Formation Under Differential Interstitial Fluid Flow Environments
Caleb Stine, Jennifer Munson
Subject: Engineering, Biomedical & Chemical Engineering Keywords: interstitial flow; glioma; chemotaxis; autologous; computational; gradient; CXCL12; migration
Fluid flow and chemokine gradients play a large part in not only regulating homeostatic processes in the brain, but also in pathologic conditions by directing cell migration. Tumor cells in particular are superior at invading into the brain resulting in tumor recurrence. One mechanism that governs cellular invasion is autologous chemotaxis, whereby pericellular chemokine gradients form due to interstitial fluid flow (IFF) leading cells to migrate up the gradient. Glioma cells have been shown to specifically use CXCL12 to increase their invasion under heightened interstitial flow. Computational modeling of this gradient offers better insight into the extent of its development around single cells, yet very few conditions have been modelled. In this paper, a computational model is developed to investigate how a CXCL12 gradient may form around a tumor cell and what conditions are necessary to affect its formation. Through finite element analysis using COMSOL and coupled convection-diffusion/mass transport equations, we show that velocity (IFF magnitude) has the largest parametric effect on gradient formation, multidirectional fluid flow causes gradient formation in the direction of the resultant which is governed by IFF magnitude, common treatments and flow patterns have a spatiotemporal effect on pericellular gradients, exogenous background concentrations can abrogate the autologous effect depending on how close the cell is to the source, that there is a minimal distance away from the tumor border required for a single cell to establish an autologous gradient, and finally that the development of a gradient formation is highly dependent on specific cell morphology.
Pre-Computation of Image Features for the Classification of Dynamic Properties in Waves
Ryan Smith, Frederic Dias, Gabriele Facciolo, Brendan Murphy
Subject: Earth Sciences, Oceanography Keywords: breaking waves; optical flow; convolutional neural networks; image classification
The use of convolutional neural networks (CNNs) in image classification has become the standard method of approaching computer vision problems. Here we apply pre-trained networks to classify images of non-breaking, plunging and spilling breaking waves. The CNNs are used as basic feature extractors and a classifier is then trained on top of these networks. The dynamic nature of breaking waves is exploited by using image sequences to gain extra information and improve the classification results. We also see improved classification performance in using pre-computed image features such as the optical flow between image pairs. The inclusion of the dynamic information improves the classification between breaking wave classes. We also provide corrections to the methodology from the article from which the data originates to achieve a more accurate assessment of performance.
Self-Organized Criticality of Traffic Flow: There is Nothing Sweet about the Sweet Spot
Subject: Engineering, Civil Engineering Keywords: traffic flow; kinematic wave model; self-organized criticality; fractals; complexity; catastrophe theory; non-equilibrium critical phenomena
This paper shows that the kinematic wave model exhibits self-organized criticality when initialized with random initial conditions around the critical density. A direct consequence is that conventional traffic management strategies seeking to maximize the flow may be detrimental as they make the system more unpredictable and more prone to collapse. Other implications for traffic flow in the capacity state are discussed, such as: \item jam sizes obey a power-law distribution with exponents 1/2, implying that both its mean and variance diverge to infinity, and therefore traditional statistical methods fail for prediction and control, \item the tendency to be at the critical state is an intrinsic property of traffic flow driven by our desire to travel at the maximum possible speed, \item traffic flow in the critical region is chaotic in that it is highly sensitive to initial conditions, \item aggregate measures of performance are proportional to the area under a Brownian excursion, and therefore are given by different scalings of the Airy distribution, \item traffic in the time-space diagram forms self-affine fractals where the basic unit is a triangle, in the shape of the fundamental diagram, containing 3 traffic states: voids, capacity and jams. This fractal nature of traffic flow calls for analysis methods currently not used in our field.
Cytological and Molecular Characterization for Ploidy Determination in Yams (Dioscorea spp.)
Cobes Gatarira, Alžběta Němečková, Denisa Šimoníková, Rajneesh Paliwal, Asrat Asfaw, Michael Abberton, Badara Gueye, Robert Asiedu, Jana Čížková, Eva Hřibová, Jaroslav Doležel, David Dekoeyer, Victor O. Adetimirin, Ranjana Bhattacharjee
Subject: Biology, Anatomy & Morphology Keywords: Dioscorea spp.; flow cytometry; chromosome counting; ploidy level; DArTseq
Yam (Dioscorea spp.) is a monocotyledonous herbaceous vine plant grown in the tropics and subtropics. It is a multi-species plant with varied intra- and interspecific ploidy levels. Of the 600 species, 11 are cultivated staple supporting the livelihood of over 300 million people. The paucity of information on ploidy and the genomic constitution is a significant challenge to the crop's genetic improvement through crossbreeding. The objective of this study was to investigate the ploidy levels of 236 accessions across six cultivated and two wild species using chromosome counting, flow cytometry and genotyping-based ploidy determination methods. Results obtained from chromosome counting and genotyping-based ploidy determination were in agreement. In majority of the accessions, chromosome counting and flow cytometry were congruent, allowing future rapid screening of ploidy levels using flow cytometry. Among cultivated accessions, 168 (71%) were diploid, 50 (21%) were triploid, and 12 (5%) were tetraploid. Two wild species included in the study were diploids. Resolution of ploidy level in yams offers opportunities for implementing successful breeding programmes through intra- and inter-specific hybridization.
Impacts of Deformed Bed Topography on Hydrodynamics in a Near-Bank Vegetated Channel: A Numerical Study
Daoxudong Liu, Wenjun Li
Subject: Engineering, Automotive Engineering Keywords: Near-bank patch; Deformed bed topography; Flow adjustment; Hydrodynamics
Understanding how the deformed bed topography induced by near-bank vegetation impacts the hydrodynamics is significant for understanding the maintenance condition of bed morphology and further fluvial evolution. This issue has rarely been addressed by current studies. This study with a 2D hydro-morphological model investigates the hydrodynamics over flat and deformed beds with a near-bank vegetation patch. By varying the patch density, the generalized results show that the hydrodynamics for the deformed bed differs a lot from those for the flat bed. It is found that deformed bed topography leads to an apparent decrease in longitudinal velocity and bed shear stress in the open region and longitudinal surface gradient for the entire vegetated reach. However, the transverse flow motion and transverse surface gradient in the region of the leading edge and trailing edge is enhanced or maintained, suggesting the strengthening of secondary flows. Interestingly, the deformed bed topography tends to alleviate the turbulent effect caused by the junction-interface horizontal coherent vortices, indicating that the turbulence-induced flow mixing is highly inhibited by the deformed bed. Alternatively, the enhanced secondary flows might provide compensation for the flow mixing for the deformed bed, confirmed by a faster recovery of the redistributed water discharge for the vegetated and open regions to the normal value (50%). The interior flow adjustment through the patch for the deformed bed requires a shorter distance, which links the vegetative drag length with a logarithmic relation. The tilting bed topographic effect in the open region to accelerate the flow may account for the faster flow adjustment.
Ischemia-Reperfusion Intervention: From Enhancements in Exercise Performance to Accelerates Performance Recovery - A Systematic Review and Meta-Analysis
Rhaí André Arriel, Jéssica Ferreira Rodrigues, Hiago Leandro Rodrigues de Souza, Anderson Meireles, Luís Filipi Moutinho Leitão, Antonio Crisafulli, Moacir Marocolo
Subject: Medicine & Pharmacology, Allergology Keywords: Intermittent occlusion; Blood flow occlusion; Sports; Ergogenic; Ischemic postconditioning
It has been demonstrated that brief cycles of ischemia followed by reperfusion (IR) applied before exercise can improve performance and, IR intervention, applied immediately after exercise (post-exercise ischemic conditioning – PEIC) exerts a potential ergogenic effect to accelerate recovery. Thus, the purpose of this systematic review with meta-analysis was to identify the effects of PEIC on exercise performance, recovery and the responses of associated physiological parameters, such as creatine kinase, perceived recovery and muscle soreness, over 24 h after its application. From 3281 studies, six involving 106 subjects fulfilled the inclusion criteria. Compared to sham (cuff administration with low pressure) and control interventions (no cuff administration), PEIC led to faster performance recovery (p=0.004; ES=-0.49) and lower increase in creatine kinase (p&lt;0.001; ES=-0.71) and muscle soreness (p&lt;0.001; ES=-0.89) over 24 h. The effectiveness of this intervention is more pronounced in subjects with low/moderate fitness level and at least a total time of 10 min of ischemia (e.g. 2 cycles of 5 min) is necessary to promote positive effects.