Acknowledgements

(d) What is the Price the consumers will sacrifice to acquire the product?

nership with the infrastructure of public health, at the time of the tests.

ing one's health in case of a positive diagnosis.

well as spontaneous manifestations of participants.

research into social marketing best practices [42].

time and Place, for the buyer?

74 Selected Issues in Global Health Communications

obtained?

4. Conclusion

(e) How can we communicate with our markets (Promote)?

In short, the price is the time available for the allocation of cognitive resources to get in contact, assimilate and share information, and also to face the fight against the fear; the fear of submitting oneself to medical tests, and to be prepared to eventually receive bad news regard-

Social media and other communication vehicles in the traditional media of the Federal Senate were used, as well as its internal information network, such as the Intranet, corporate emails and banners spread throughout the institution, in addition to events and artistic performances. (f) Which institutions are involved in the process of making the product available at the best

The internal infrastructure of the health service of the Federal Senate was provided, in part-

(g) How can we Probe and evaluate the campaign and how can feedback from the public be

Metrics for disclosure, visualization, and reviews of materials and postings were evaluated, as

According to Mowen and Minor, research can benefit society. "Finding ways to influence people to act more responsibly […] and applying research findings to develop treatment methods and preventive actions" is paramount, and the natural way to do this is through the

Considering the campaign analyzed in this chapter, besides the health communication informing about breast cancer, several other actions took place. A major effort was made in order to reach Brazilian citizens through the Senate's social media, as well as with an actual person-to-person contact, all these to try to make more people aware of the disease. For that, a close-targeted initiative was developed throughout the month of October: the outsourced female collaborators were invited to undergo an on-site medical consultation with the Senate mastologist doctors, and if the case required, the patient would be referred to a mammography exam carried out by the Public Health System (as a result of the partnership between the Senate and the Federal District Government). A total of 150 mammograms were performed. A disturbing fact is that most of the women who were reached by the initiative had never undergone a mammography before, which is an important exam to prevent breast cancer.

From the 150 patients assisted, 15 had an altered mammography result, and 4 of them had a

Although 150 people is a limited audience, the tests and the mammograms were just part of the campaign, which aimed to achieve, through advertising and journalistic information, the

diagnosis of breast cancer and were referred to a public hospital for treatment.

The authors would like to thank Mr. Mikhail Lopes and Mr. Eduardo Leão, from the Secretariat of Social Communication of the Federal Senate, for their valuable assistance in gathering metrics from the Senate's social media and from Intranet news, and of the Certified Translator Elisângela Tarouco for the context and grammar review.


**6.2 Cutting using LBM**

Cutting is an essential operation in any material removal processes. A relative motion between work piece and the laser beam is required to produce a twodimensional working plane where the material removal takes place. During relative motion of laser beam and work piece, a kerf is produced which removes the material in its path. Complex two-dimensional shapes can be cut from the flat work piece

**Figure 13.** *LBM for cutting operation.*

**Figure 14.**

*Three-dimensional LBM for (a) lathe operation and (b) milling operation.*

materials where mechanism of material removal is similar to drilling operation. In contrast to the drilling process, the erosion front is located at the front of line of laser beam as shown in **Figure 13**. However, the temperature field and erosion front is fixed based on the coordinate moves along with produced laser source that ensures steady state process. The erosion front molten material is flushed away using a gas jet during the cutting process.

## **6.3 Three-dimensional LBM**

Three-dimensional LBM uses two or more number of laser beams simultaneously focused to obtain an intersected volume for material removal. To precisely create such volumes with relative motions, highly accurate optical manipulating systems are therefore necessary. Recent systems equipped with optical scanning systems have high level of control over the motion of laser beams which enables efficient and effective machining operations. The material removal using these tools is referred as 3-dimensional (3D) laser material processing. In general, the 3D laser material processing is grouped into various categories such as laser beams along with 3D LBM, 5-axis heads along with 3D processing workstation and 3D remote laser processing. **Figure 14** illustrate the graphical picture of two-beam laser machining processes for lathe and milling operations. Each beam creates a groove like volume of material removal when they intersect with some incidence angle. The incidence angle may be changed and dynamically varied along with relative motion to get intricate shapes of machining.

LBM is successfully adapted in micromachining field due to its high flexibility to automation and high degree of radiance. Laser beam micromachining is capable of producing parts with sizes ranging from micro to sub-micro scales. It usually employs the pulsed lasers with an average power of less than 1 kW. The pulses of femtosecond duration are widely used for micromachining. Micromachining can be performed on wide range of materials such as metals, glasses, diamond and other difficult to machining materials. Laser-assisted manufacturing (LAM) is another technique helps to enhance the maximum productivity, quality with minimized machine tool vibrations, machining forces and tool wear. LAM is also an effective technique to machine brittle materials without cracks and failure. This hybrid machining process, laser beam is focused on the work piece just before the cutting tool engages. Scanning of laser initially heats up the work therefore helps in plastic deformation rather than brittle deformation during machining. The LAM processes are suitable for brittle and hard type of material such as ceramics, nickel alloys and the higher amount of silicon element material.

**99**

also has several limitations such as,

*Laser Machining*

**7. Advantages**

machining.

**8. Limitations**

*DOI: http://dx.doi.org/10.5772/intechopen.93779*

machining processes due to many advantages as follow:

therefore post processing can be eliminated.

no requirement of chemicals or solvents for machining.

damages, vibrations, frequent tooling requirements.

ity and conductivity can be machined.

• Degree of accuracy in machining complex geometry is high.

LBM is an excellent manufacturing technique to process wide ranges of difficult to machine materials especially ceramics and advanced composite materials. LBM technique is capable of machining intricate shapes that cannot be reached or processed by conventional machining processes. LBM is an alternate to conventional

• Due to precise machining capability, LBM can produce excellent surface finish

• LBM is a clean manufacturing technique due to less environment pollution and

• LBM can be easily automated for higher productivity and to achieve high speed

• It uses no cutting tool therefore no cutting forces involved during machining. This phenomenon helps to avoid heavy construction of machine tools, physical

• LBM depends on thermal and few optical properties of work material rather than mechanical properties such as hardness and brittleness. As a result, most of the materials with any degree of mechanical properties with lower diffusiv-

• Wide range of materials from plastics to diamond can be machined.

• Machining micro features with large aspect ratio is possible with LBM.

There are many issues and limitations associated with the aforementioned LBM technique. The major issues are produced accuracy, achieved surface quality and rate of material removal. The erosion front is the main factor decides the amount of material removal in LBM technique. In one-dimensional machining, the speed of propagation in erosion front in the straight line decides the rate of material removal. In another hand, the scanning speed plays a significant role in metal removal during the two-dimensional machining processes. Similarly, the laser scanning speed is produced the intersecting surfaces for volume formation and the decisive factor for material removal rate during the 3D machining processes. Controlling the LBM parameters for a balanced and effective machining is a real challenge faced by industries. Secondly, the dimensional accuracy is affected by the kerf shape of laser which leads to tapered holes instead of narrow holes. Surface quality is the other important aspect of machining, which is measured by surface roughness, formation of dross and the HAZ. Since LBM is completely thermal based machining process it

• Residual stresses caused due to HAZ are very less in LBM.


**Author details**

Sally S. Lloyd1 , Edward J. Steele1 and Roger L. Dawkins1,2,3\*

\*Address all correspondence to<EMAIL_ADDRESS>
1 CY O'Connor ERADE Village Foundation, 24 Genomics Rise, Piara Waters, Western Australia, Australia

2 School of Veterinary and Biomedical Sciences, Division of Health Sciences, Murdoch University, Murdoch, Western Australia, Australia

3 Faculty of Medicine and Dentistry, University of Western Australia, Nedlands, Western Australia, Australia


**1. Introduction**

In recent years, power converters have played an important role in power electronics technology for different applications, such as renewable energy systems, electric vehicles, pulsed power generation, and biomedical. Power converters in power electronics are becoming essential for generating electrical power energy in various ways. Voltage source and current source inverters are well-known as the conventional topologies to convert a DC source to an AC source. For single-phase current source inverters, DC-side low-frequency power oscillation is an inherent limitation. Various active power decoupling circuits for single-phase current source converters are reviewed in [1]. During the last decade, the multilevel inverter has become very popular in medium and high-power applications, with some advantages, such as the reduced power dissipation of switching elements, low harmonics, and low electromagnetic interferences (EMIs). An overview of the multi-level inverter topologies is presented in [2]. The development of the advanced power converters is necessary for the various applications. This special issue focuses on the development of novel power converter topologies in power electronics.

#### **2. The Current Research Trends**

Each of the 28 articles collected in this special issue proposes a solution to a specific problem related to the power converter topologies. The impedance source inverters (ISIs) overcome the limitation of the conventional inverters, because they can operate in single-stage power conversion with buck-boost voltage and shoot-through immunity. In Reference [3], a three-phase cascaded active ISI is proposed to reduce the number of passive elements. A common ground Z-source SEPIC inverter is proposed in [4] to eliminate leakage current. In order to increase the voltage gain, a multiplier cell technique is applied to the quasi-switched boost inverter with low input current ripple [5]. The applications of the ISI for grid connection [6] and photovoltaic [7] are presented.

New concepts of pulse-width modulation (PWM) control techniques and control theories for the inverters are another focus of this issue. A modified model predictive power control for grid-connected T-type inverter with reduced computational complexity is presented in [8]. A robust two-layer model predictive control for three-level inverter is shown in [9]. Current source AC-side clamped inverter for leakage current reduction in grid-connected photovoltaic (PV) system is shown in [10]. A control design of the LCL filter [11] and PWM method [12] for single-phase inverter are carried out. The space vector modulation technique is applied to the quasi-switch boost t-type inverter for common mode voltage elimination [13]. In addition, the PWM techniques for five-level inverter are presented in [14,15], with a minimal number of commutations. The inverter topology for the DC motor is presented in [16].

In addition to the research in the inverter topologies, this issue has collected important research on isolated [17,18] and non-isolated [19–22] DC-DC power converters and rectifiers [23,24]. In Reference [17], a comparative evaluation of some wide-range soft-switching full-bridge modular multilevel DC–DC converters is discussed. To realize the functions of reduced primary current loss

and balanced voltage and current, a DC-DC converter with the series/parallel connection on the high-voltage/low-voltage side is presented in [18]. A bipolar bidirectional DC/DC converter and its interleaved-complementary modulation scheme are introduced in [19]. A multiple three-phase low-voltage and high-current permanent magnet synchronous generation system is proposed in [20] for 5 V/10 kA DC power supply. In Reference [21], a new technique for enlarging the stable range of peak-current-mode-controlled DC-DC converters is presented. In Reference [22], a combination of the one-comparator counter-based PWM control with pulse frequency modulation (PFM) control is presented for buck DC-DC converter. A power-based space vector modulation technique for a matrix rectifier is proposed in [23], where the modulation index and applied phase are calculated, based on the active and reactive power of the rectifier for intuitive power factor control. In Reference [24], a modeling method is introduced to establish a parametric-conducted emission model of a switching model power supply chip through a developed vector fitting algorithm.

Various power converter topologies for different applications, such as wireless power transfer [25,26], battery charging [27,28], static synchronous compensator (STATCOM) [29], and gate driver [30] are presented in this issue. In Reference [24], an inductive power transfer (IPT) system with three-bridge switching compensation topology is proposed, to achieve the load-independent constant current (CC) and load-independent constant voltage (CV) outputs. In Reference [25], a generalized fractional-order wireless power transmission is established for medium and long-range wireless power transmission. A fast-charging balancing circuit for LiFePO4 battery is proposed in [26], to address the voltage imbalanced problem of a lithium battery string. In Reference [27], an add-on type pulse charger is introduced, to shorten the charging time of a lithium ion battery. In Reference [28], an individual phase full-power testing method for high-power STATCOM is presented with reconfiguration the port connection of three-phase STATCOM. In Reference [30], an intelligent control method for suppressing electromagnetic interference (EMI) sources in the fast switching power converters is proposed, with a combination of open-loop and closed-loop methods.

#### **3. Future Trends**

The future research in the advanced power converter topologies will continue to find the solutions in applications of current power electronics for different disciplines. New power converters will be investigated to enhance or replace the current converter topologies. A new growing interest is the integration of impedance-source converters for renewable energy system applications.

**Author Contributions:** M.-K.N. worked during the whole editorial process of the special issue entitled "Power Converters in Power Electronics", published in the MDPI journal *Electronics*. M.-K.N. drafted, reviewed, edited, and finalized this editorial summary. Author has read and agreed to the published version of the manuscript.

**Acknowledgments:** I thank all the authors who submitted excellent research works to this Special Issue. I also thank Xiaoqiang Guo from Yanshan University, China for his contribution as a technical program committee member. I am very grateful to all reviewers for their evaluations of the merits and quality of the articles and valuable comments to improve the articles in this issue. I would also like to thank the editorial board and staff of MDPI journal *Electronics* for the opportunity to guest-edit this Special Issue.

**Conflicts of Interest:** The author declares no conflict of interest.


*3.2. Sensors*

An EEG sensor produced by Muse [36] and a Grove GSR sensor produced by Seeed [37] were used in this study (Figure 2). The upper section of Figure 2 shows the EEG sensor, which has four electrodes. According to the instructions from the EEG sensor manufacturer, the electrodes are located at the positions FP1, FP2, TP9, and TP10 of the head [36]. The mapping of head locations was defined by Jasper [38], and it is used in neuroscience. The EEG data were captured with four electrodes; however, only the data from FP1 and FP2 were utilized. This is because TP9 and TP10 were not attached well on the participants' heads during the data collection, which caused instability in the output data from these electrodes. The EEG sensor captured raw EEG at a 220 Hz sampling rate and provided power spectral density (PSD) values for each electrode. According to the sensor manufacturer, the types of PSD data were absolute band power (ABP), relative band power, and others [36]. The sampling rate of these data was 10 Hz. To calculate ABP, we applied the fast Fourier transform algorithm. We calculated PSD by the following EEG frequency bands [36]:

The lower section of Figure 2 illustrates the Grove GSR sensor that was used in this study, along with the finger band electrodes. These electrodes were attached to the index and middle fingers of the participants. The GSR sensor captures micro voltages (MV) between the fingers using the attached electrodes. Furthermore, the sensor calculates skin resistance (SR) utilizing the MV input in ohms. The formula for calculating SR using MV is provided by the sensor manufacturer [37], and is replicated in Equation (1). The sensor was connected to an Arduino Uno device, and the captured data were transmitted to a computer at a 192 Hz sampling rate:

$$SR = ((1024 + 2 \ast MV) \ast 10,000) / (512 - MV). \tag{1}$$

**Figure 2.** (**a**) EEG sensor, and (**b**) GSR sensor.

## *3.3. Protocol*

Figure 3 presents the protocol of data collection. In the introduction stage, the participants were presented a page showing a consent form of the experiment. The information on the consent form stated that we would use the collected data only anonymously for academic purposes. Furthermore, the participants were instructed that they could stop the experiment anytime when they feel uncomfortable.

In the stage for showing non-boredom videos, a cinematic trailer of Blizzard's Starcraft 2: Heart of the Swarm, and a Korean comedy video clip were used to evoke non-boredom. These video clips were chosen to entertain the participants so that they would not become bored. To evoke boredom, a looping video was played in which a small circle moved slowly tracing the boundary of a bigger circle. Furthermore, to neutralize the emotion state of the participants, a cloud image from the International Affective Picture System [39] was shown for 30 seconds before showing each video stimulus. When the participants watched the videos, they were instructed to stop watching (by pressing a button) at any time they chose. Thus, each participant's data length was different, with the shortest watching time being 7.13 s.

The data collection consisted of two sessions. The sessions were otherwise identical except for the non-boredom video stimulus (i.e., the game trailer and the comedy show clip). The reason for carrying out data collection in two sessions was to get a content-independent classification result. In other words, we wanted to see whether the change of non-boredom video has an effect on the classification. After watching the video stimuli, the participants answered a questionnaire to measure the strength of boredom that they felt. The questionnaire had two questions: one for the boredom video, and another for the non-boredom video. The questionnaires were designed to be answered on a 5-point scale, and the range of the scale was from "None" to "Very much."

**Figure 3.** Protocol of data collection.

#### **4. Machine Learning Methods**

In this section, we describe the procedure for feature extraction and machine learning techniques for analyzing the collected data to classify boredom.

#### *4.1. Window Size*

As explained in Section 3.3, each participant's data length was different because they were instructed to stop the video stimuli playback at the time they chose. The shortest data length was 7.13 s, thus only the last 7 s of each participant's data were extracted to build the models. With the window size of 7 s, the number of samples was 56. Other window sizes, such as 1 s and 0.5 s, were also tested; however, these potentially caused overfitting because two or more samples would be generated from the same data with the same label.


**3. Millennial variations of the Sun-Earth distance**

The observations of solar irradiance and magnetic field baseline oscillations with the period of about 2100–2200 years are believed to be imposed on the Sun by the gravitational effects of Neptune and Saturn causing SIM [30, 46]. In this section we carry out the investigation of Sun-Earth distance variations over a millennial scale in an attempt to establish if they follow or deviate from Kepler's laws.

#### **3.1 Ephemeris of the Sun-Earth distances in 600–2600**

Let us now explore the daily Sun-Earth (S-E) distances over the two millennia (600–2600) derived from the ephemeris of VASOP87 - Variations Seculaires des Orbites Planetaires [47] *http* : *==neoprogrammics:com=vsop*87*=planetarydistancetables=:* Note that the VSOP87 data up to 6 digits after the decimal coma coincide with the widely used JPL ephemeris [48].

The daily Sun-Earth distances for every month of the three years for each millennium: M1 (600, 1100, 1600) and M2 (1700, 2020, 2600) are presented in **Figure 5** (January–June) and 6 (July–December) for the millenniums M1 (600– 1600) (left column) and millennium for M2 (1600–2600 (right column). The Sun-Earth distances change rather differently over the two millennia M1 and M2 from what one would expect from the elliptic motion of the Earth about the Sun where the perihelion (shortest distance) and aphelion (longest distance) occur on the semi-major axis of the ellipse and the distances are defined by Kepler's third law (see **Figure 15** and Eq. (6) in Appendix A).

However, instead of it, one can observe a significant reduction of the Sun-Earth distances in January–June (**Figure 5**) and their increase in July–December (**Figure 6**). Furthermore, the maximal differences, or differences between the S-E distances at the start and end of each millennium considered presented in **Figure 7**, reveal these maximal differences reaching 0.005 au in April–May (**Figure 5**) in millennium M1 and up to 0.011 au in April–May in millennium M2. These are followed by significant increases of the S-E distances in August–December shown in **Figures 6** and **7**. Moreover, the daily double differences, e.g. the differences between the maximal differences of the S-E daily distances in M1 and M2, taken from **Figure 7**, plotted in **Figure 8** demonstrate that in March–June there is a large reduction of the S-E distances in M2 compared to M1.

In order to evaluate if these changes are symmetric, let us present the mean monthly S-E distance variations during each sample year considered plotted in **Figure 9**. This, in fact, reveals that in M1 the increases/decreases of the S-E distances (left plot) are nearly symmetric over each year and centred about the summer solstice in June and winter solstice in December while in the millennium M2 the

**Figure 5.**

*2600.*

**35**

*Variations of the sun-earth distances (in astronomical units, au) versus days of the month (X-axis) in January– June for three sample years in the millennium M1 (600–1600) (left) and M2 (1600–2600) (right). Left column: Blue - year 600, red 1100 and green 1600; right column: Blue - year 1700, red - 2020 and grey -*

*Millennial Oscillations of Solar Irradiance and Magnetic Field in 600–2600*

*DOI: http://dx.doi.org/10.5772/intechopen.96450*


**5. Application**

Silicon materials are used in components of electronic devices. It is also used to make solar cells [9–13] and parts for computer circuits [14]. Solar cell is a device

**3**

**Author details**

Batna, Algeria

Beddiaf Zaidi\* and Slimen Belghit

provided the original work is properly cited.

\*Address all correspondence to<EMAIL_ADDRESS>
*Introductory Chapter: Silicon*

*DOI: http://dx.doi.org/10.5772/intechopen.85802*

that converts sun light into electrical energy [15–23]. A rectifier is an electrical device that converts alternating current to direct current. The most important silicon alloys are those made with Fe, Al, and Cu. When silicon is produced, in fact,

scrap iron and metal are sometimes added to the furnace [24, 25].

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Department of Physics, Faculty of Material Sciences, University of Batna 1,

*Introductory Chapter: Silicon DOI: http://dx.doi.org/10.5772/intechopen.85802*

*Silicon Materials*

**4. Silicon thin film**

**Figure 1.**

nation of these materials [2–5]:

2.Microcrystalline silicon

3.Polycrystalline silicon (poly-Si).

*E(k) for the conduction and valence bands of silicon.*

*Grain size range depending on the type of the silicon [6–8].*

Silicon thin-film cells are mainly deposited by chemical vapor deposition (typically plasma-enhanced, PE-CVD) from silane gas and hydrogen gas. Depending on the deposition parameters, these silicon thin films can be based on one or a combi-

These silicon thin film materials can be characterized by their grain sizes ranging from none (amorphous) to large silicon (~100 μm) for polysilicon. The crystalline silicon thin films present dangling bonds, which result in deep defects (energy levels in band gap) as well as deformation of the conduction and valence bands. The solar cells made from thin films tend to have lower energy conversion efficiency than

**Type of silicon Abbreviation Crystal size Deposition method** Single-crystal silicon Sc-Si >10 cm Czochralski, Float zone Multicrystalline silicon Mc-Si 1 mm–10 cm Cast, sheet, ribbon Polycrystalline silicon Poly-Si 1 μm–1 mm Chemical-vapor deposition (at high

Microcrystalline silicon μc-Si 10 nm–1 μm Ex.: Plasma deposition (at low temperature < 600°C) Nanocrystalline silicon nc-Si 1–10 nm

Silicon materials are used in components of electronic devices. It is also used to make solar cells [9–13] and parts for computer circuits [14]. Solar cell is a device

temperature ≥ 1000°C)

1.Amorphous silicon (a-Si or a-Si:H) or polymorphous silicon

silicon bulk but are also less expensive to produce (**Table 1**).

**2**

**5. Application**

**Table 1.**

that converts sun light into electrical energy [15–23]. A rectifier is an electrical device that converts alternating current to direct current. The most important silicon alloys are those made with Fe, Al, and Cu. When silicon is produced, in fact, scrap iron and metal are sometimes added to the furnace [24, 25].