Search results for: enhancement mode GaN power transistors

Authors: Farhad Imanshoar

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The regime or equilibrium geometry of alluvial rivers remains a topic of fundamental scientific and engineering interest. There are several approaches to analyze the problem, namely: empirical formulas, semi-theoretical methods and rational (extreme) procedures. However, none of them is widely accepted at present, due to lack of knowledge of some physical processes associated with channel formation and the simplification hypotheses imposed in order to reduce the high quantity of involved variables. The study presented in this paper shows a new approach to estimate stable width and depth of sand-bed rivers by using developed stream power equation (DSPE). At first, a new procedure based on theoretical analysis and by considering DSPE and ultimate sediment concentration were developed. Then, experimental data for regime condition in sand-bed rivers (flow depth, flow width, sediment feed rate for several cases) were gathered. Finally, the results of this research (regime equations) are compared with the field data and other regime equations. A good agreement was observed between the field data and the values resulted from developed regime equation.

Keywords: regime equations, developed stream power equation, sand-bed rivers, semi-theoretical methods

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Authors: Gyozo Molnar, Nancy Spencer-Cavaliere

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Research in the area of physical activity and sport, while becoming multidisciplinary, is still dominated by post-positivist approaches that have the tendency to position the researcher as an expert and the participant as subordinate thereby perpetuating an unequal balance of power. Despite physical activity’s and sport’s universal appeal, their historic practices have excluded particular groups of people who assumed lesser forms of human capital. Adapted physical activity (APA) is a field that has responded to those segregations with specific application and relevance to people with impairments. Nevertheless, to date, similar to physical activity and sport, research in APA is still dominated by post-positivist epistemology. Stemming from this, there is gradually growing criticism within the field related to the abundance of research ‘on’ people with impairments and lack of research ‘with’ and ‘by’ people with impairments. Furthermore, research questions in the field are most often pursued from a single axis of analysis and constructed by non-disabled researchers. Concurrently, while calls for interdisciplinary approaches to understanding disability are growing in popularity, there is also a clear need to take an intersectionality-informed research methodology to understanding physical activity and sport and power (im)balances therein. In other words, impairment needs to be considered in conjunction with other socially and politically constructed and historically embedded differences such as gender, race, class, etc. when analyzing physical activity and sport experiences for people with impairments. Moreover, it is reasonable to argue that non-disabled researchers must recognize and theorize ableism in its complicated intersectional manifestation to show the structural constraints that disabled scholars face in the field. Consequently, this presentation will offer an alternative approach that acknowledges and prioritizes the perspectives and experiences of people with impairments to expand the field of APA. As such, the importance of broadening epistemologies in APA and prioritizing an appreciation for multiple bits of knowledge of people with impairments through intersections of social locations (e.g., gender, race, class) will be considered.

Keywords: adapted physical activity, disability, intersectionality, post-positivist, power imbalances

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Authors: Stefano Frassinelli, Alessandro Niccolai, Riccardo E. Zich

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Diving is an important Olympic sport. In this sport, the effective performance of the athlete is related to his capability to interact correctly with the springboard. In fact, the elevation of the jump and the correctness of the dive are influenced by the vibrations of the board. In this paper, the vibrations of the springboard will be analyzed by means of typical tools for vibration analysis: Firstly, a modal analysis will be done on two different models of the springboard, then, these two model and another one will be analyzed with a time analysis, done integrating the equations of motion od deformable bodies. All these analyses will be compared with experimental data measured on a real springboard by means of a 6-axis accelerometer; these measurements are aimed to assess the models proposed. The acquired data will be analyzed both in frequency domain and in time domain.

Keywords: springboard analysis, modal analysis, time domain analysis, vibrations

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Authors: Zarina Chokparova, Ighor Uzhinsky

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Carbon dioxide emissions resulting from burning of the fossil fuels on large scales, such as oil industry or power plants, leads to a plenty of severe implications including global temperature raise, air pollution and other adverse impacts on the environment. Besides some precarious and costly ways for the alleviation of CO₂ emissions detriment in industrial scales (such as liquefaction of CO₂ and its deep-water treatment, application of adsorbents and membranes, which require careful consideration of drawback effects and their mitigation), one physically and commercially available technology for its capture and disposal is supersonic system for inertial extraction of CO₂ in after-combustion streams. Due to the flue gas with a carbon dioxide concentration of 10-15 volume percent being emitted from the combustion system, the waste stream represents a rather diluted condition at low pressure. The supersonic system induces a flue gas mixture stream to expand using a converge-and-diverge operating nozzle; the flow velocity increases to the supersonic ranges resulting in rapid drop of temperature and pressure. Thus, conversion of potential energy into the kinetic power causes a desublimation of CO₂. Solidified carbon dioxide can be sent to the separate vessel for further disposal. The major advantages of the current solution are its economic efficiency, physical stability, and compactness of the system, as well as needlessness of addition any chemical media. However, there are several challenges yet to be regarded to optimize the system: the way for increasing the size of separated CO₂ particles (as they are represented on a micrometers scale of effective diameter), reduction of the concomitant gas separated together with carbon dioxide and provision of CO₂ downstream flow purity. Moreover, determination of thermodynamic conditions of the vapor-solid mixture including specification of the valid and accurate equation of state remains to be an essential goal. Due to high speeds and temperatures reached during the process, the influence of the emitted heat should be considered, and the applicable solution model for the compressible flow need to be determined. In this report, a brief overview of the current technology status will be presented and a program for further evaluation of this approach is going to be proposed.

Keywords: CO₂ sequestration, converging diverging nozzle, fossil fuel power plant emissions, inertial CO₂ extraction, supersonic post-combustion carbon dioxide capture

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Authors: Michal Biały, Krzysztof Skiba, Zdzislaw Kaminski

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The research results of the influence of the adjustable mutual position of the propellers for getting optimal lift force on a specially designed bench. The bench consists of frame with electric motors and with attached propellers. Engines were arranged in a matrix of two columns and three rows. The distance between the columns averages from 0 to 20”, while the engine was placed at a height of 8”, 15.5” and 23.6”. By adjusting the tilt of an electric motor, an angle of the propeller in the range of 0° to 60°, by 15° was controlled. Propellers with a diameter of 8" and pitch of 4.5” were driven by brushless model engines Roxxy BL-Outrunner 2827/26 with a power of 110W (each). Rotational speed control of electric motors were realized parallel for all propellers. The speed adjustment was realized using an aggregate of radio-controlled regulators. Electric power supplied to the engines from zero to maximum power, by the setting for every 14W, was controlled by radio system. Measurement system was placed on a laboratory scale. The lift was measured and recorded by an electronic scale. The lift force for different configurations of propellers arrangement was recorded during the test. All propellers were driven in one rotational direction and in different directions when they were in the same pairs. Propellers were driven concurrently and contra-concurrently along one of the columns and along the selected rows. During the tests, except the lift, parameters such as: rotational speed of propellers, voltage and current to the electric engines were recorded. The main aim of the research was to show the influence of aerodynamic interference between the propellers to receive lift force depending on the drive configuration of individual propellers. The research has shown that, this interference exists. The increase of the lift force for a distance between columns above 26.6” was noticed during the driving propellers in different directions. The optimum tilt angle of the propeller was 45°. Furthermore there has been also approx. 12% increase of the lift for propellers driven alternately in column and contra-concurrently in relation to the contra-rotating drive in the row.

Keywords: aerodynamic, interference, lift force, propeller, propulsion system

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Authors: Jafar Khodagholizadeh

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In this talk, we study the tensor mode equation of perturbation in the presence of nonzero $-\Lambda$ as dark energy, whose dynamic nature depends on the Hubble parameter $ H$ and/or its time derivative. Dark energy, according to the total vacuum contribution, has little effect during the radiation-dominated era, but it reduces the squared amplitude of gravitational waves (GWs) up to $60\%$ for the wavelengths that enter the horizon during the matter-dominated era. Moreover, the observations bound on dark energy models, such as running vacuum model (RVM), generalized running vacuum model (GRVM), and generalized running vacuum subcase (GRVS), are effective in reducing the GWs’ amplitude. Although this effect is less for the wavelengths that enter the horizon at later times, this reduction is stable and permanent.

Keywords: gravitational waves, dark energy, GW's amplitude, all stage universe

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Authors: Mohammad Syahirin Aisha, Khairul Imran Sainan

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The PEM fuel cell is a device that generate electric by electrochemical reaction between hydrogen fuel and oxygen in the fuel cell stack. PEM fuel cell consists of an anode (hydrogen supply), a cathode (oxygen supply) and an electrolyte that allow charges move between the two positions of the fuel cell. The only product being developed after the reaction is water (H2O) and heat as the waste which does not emit greenhouse gasses. The performance of fuel cell affected by numerous parameters. This study is restricted to cathode parameters that affect fuel cell performance. At the anode side, the reactant is not going through any changes. Experiments with variation in air velocity (3m/s, 6m/s and 9m/s), temperature (10oC, 20oC, 35oC) and relative humidity (50%, 60%, and 70%) have been carried out. The experiments results are presented in the form of fuel cell stack power output over time, which demonstrate the impacts of the various air condition on the execution of the PEM fuel cell. In this study, the experimental analysis shows that with variation of air conditions, it gives different fuel cell performance behavior. The maximum power output of the experiment was measured at an ambient temperature of 25oC with relative humidity and 9m/s velocity of air.

Keywords: air-breathing PEM fuel cell, cathode side, performance, variation in air condition

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Authors: Ali Driouiche, Abdallah Hadfi

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During this work on scaling phenomenon observed in the irrigation water pipes in the agricultural region of Greater Agadir, a follow-up was carried out during a year of the physico-chemical quality of these waters. Sampling was conducted from 120 sampling points, well distributed in the study area and involved 120 water samples. The parameters measured for each sample are temperature, pH, conductivity, total hardness and the concentrations of the ions HCO₃₋, Ca²⁺, Mg²⁺, Na⁺, K⁺, SO₄₋, NO₃₋, Cl₋ and OH₋. Indeed, the monitoring of the physico-chemical quality shows that the total hardness varies between 20 and 65 °F and the complete alkalimetric title varies from 14 °F to 42 °F. For the kinetic study of the scaling power, an object of this work, 6 samples which have high hardness were selected from the 120 samples analyzed. This study was carried out using the controlled degassing method Laboratoire de Chimie et de Génie de l’Environnement (LCGE) where it was developed) and showed that the studied waters are calcifying. The germination time Tg varies between 16 and 34 minutes. The highlighting of new scale inhibitors to prevent the formation of scale in the pipelines of the agricultural sector of Greater Agadir will also be discussed.

Keywords: agadir, clogging pipes, localized irrigation, scaling power

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Authors: Rafiuddin

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Composite solid electrolyte of the salt and oxide type is an effective approach to improve the ionic conductivity in low and intermediate temperature regions. The conductivity enhancement in the composites occurs via interfaces. Because of their high ionic conduction, composite electrolytes have wide applications in different electrochemical devices such as solid-state batteries, solid oxide fuel cells, and electrochemical cells. In this work, a series of novel (1‒x) (CdI2‒Ag2CrO4)‒xAl2O3 composite solid electrolytes has been synthesized. The prepared materials were characterized by X‒ray diffraction, differential thermal analysis, and AC impedance spectroscopy. The impedance spectra show single semicircle representing the simultaneous contribution of grain and grain boundary. The conductivity increased with the increase of Al2O3 content and shows the maximum conductivity (σ= 0.0012 S cm‒1) for 30% of Al2O3 content at 30 ℃.

Keywords: composite solid electrolyte, X-ray diffraction, Impedance spectroscopy, ionic conductivity

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Authors: Ikram Slamani, Hicheme Ferdjani

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This study focuses on analyzing a Griffith crack situated at the center of an infinite strip. The problem is reformulated as a hyper-singular integral equation and solved numerically using second-order Chebyshev polynomials. The primary objective is to calculate the stress intensity factor in mode 1, denoted as K1. The obtained results reveal the influence of the strip width and crack length on the stress intensity factor, assuming stress-free edges. Additionally, a comparison is made with relevant literature to validate the findings.

Keywords: center crack, Chebyshev polynomial, hyper singular integral equation, Griffith, infinite strip, stress intensity factor

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Authors: M. G. Murtaza, E. E. Tzirtzilakis, M. Ferdows

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Biomagnetic fluid dynamics is an interdisciplinary field comprising engineering, medicine, and biology. Bio fluid dynamics is directed towards finding and developing the solutions to some of the human body related diseases and disorders. This article describes the flow and heat transfer of two dimensional, steady, laminar, viscous and incompressible biomagnetic fluid over a non-linear stretching sheet in the presence of magnetic dipole. Our model is consistent with blood fluid namely biomagnetic fluid dynamics (BFD). This model based on the principles of ferrohydrodynamic (FHD). The temperature at the stretching surface is assumed to follow a power law variation, and stretching velocity is assumed to have a nonlinear form with signum function or sign function. The governing boundary layer equations with boundary conditions are simplified to couple higher order equations using usual transformations. Numerical solutions for the governing momentum and energy equations are obtained by efficient numerical techniques based on the common finite difference method with central differencing, on a tridiagonal matrix manipulation and on an iterative procedure. Computations are performed for a wide range of the governing parameters such as magnetic field parameter, power law exponent temperature parameter, and other involved parameters and the effect of these parameters on the velocity and temperature field is presented. It is observed that for different values of the magnetic parameter, the velocity distribution decreases while temperature distribution increases. Besides, the finite difference solutions results for skin-friction coefficient and rate of heat transfer are discussed. This study will have an important bearing on a high targeting efficiency, a high magnetic field is required in the targeted body compartment.

Keywords: biomagnetic fluid, FHD, MHD, nonlinear stretching sheet

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Authors: Zaid H. Yaseen, Jamel A. Orfi, Zeyad A. Alsuhaibani

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Solar power has a huge potential to be employed in the fields of electricity production, water desalination, and multi-generation. There are various types of solar collectors, and parabolic trough collectors (PTCs) are common among these types. In PTCs, a mirror is used to direct the incident radiation on an absorber tube to utilize the heat in power generation. In this work, a PTC covered with a glass tube is presented and analyzed. Results showed that temperatures of 510℃ for steam can be reached for certain parameters. The work also showed the viability of using Benzene as the working fluid in the absorber tube. Also, some analysis regarding changing the absorber’s tube diameter and the efficiency of the solar collector was demonstrated in this work. The effect of changing the heat transfer correlations for the convection phenomena of the working fluid was illustrated. In fact, two heat transfer correlations, the Dittus-Boelter and Gnielinski correlations, were used, and the outcomes showed a resemblance in the results for the maximum attainable temperature in the working fluid.

Keywords: absorber tube, glass tube, incident radiation, parabolic trough collector

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Authors: Saleh Nabiyev

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Renewable energy is becoming increasingly important in today's world due to its significant impact on the green economy, ecology, environment, and climate change. Renewable energy sources, such as solar and wind, are clean and sustainable, making them an ideal solution to reduce carbon emissions and mitigate the effects of climate change. The Karabakh region is located in the South Caucasus and covers an area of approximately 11,500 km². The region has a mountainous terrain, which can affect the availability of wind and solar resources. The Karabakh region has significant wind power potential, particularly in its mountainous areas where wind speeds are typically higher. According to a study conducted by the European Commission Joint Research Centre, the average wind speed in the Karabakh region is between 4 and 6 meters per second (m/s) at a height of 50 meters above ground level (AGL). However, wind speeds can be higher in some areas, reaching up to 10 m/s in some mountainous areas. The region also has significant solar power potential, with an average of 2,000 to 2,200 hours of sunshine per year. The region's high altitude and clear skies make it particularly suitable for the development of solar power projects. In this research, the application of satellite images, solar radiation, wind speed and direction, as well as various other materials to determine suitable areas for alternative energy sources, is investigated. The methodology for selecting suitable locations for solar and wind energy consists of four main parts: identification of factors, evaluation of factors, data preparation, and application of suitability analysis. At the end of the research, the territory of the Kalbajar and Lachin districts is suitable for wind energy. The southern plain part of Karabakh is highly evaluated in terms of solar energy potential, especially Jabrayil district. Generally, outcomes taken from this research are essential data for increasing of rational using natural resources, as well as combating climate change.

Keywords: GIS, remote sensing, suitability analysis, solar energy, wind energy

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Authors: Keri̇m Emre Öksüz, Şaduman Şen, Uğur Şen

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0.5 wt. % B2O3–doped Ba (Ti1-xZrx) O3, (x=0-0.4) lead-free nanoceramics were synthesized using the solid-state reaction method by adopting the ball milling technique. The influence of the substitution content on crystallographic structure, phase transition, microstructure and sintering behaviour of BT and BZT ceramics were investigated. XRD analysis at room temperature revealed a structural transformation from tetragonal to rhombohedral with enhancement of ZrO2 content in the barium titanate matrix. The scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to investigate microstructure and surface morphology of the sintered samples. The evolution of the Raman spectra was studied for various compositions, and the spectroscopic signature of the corresponding phase was determined. Scanning Electron Microscope (SEM) observations revealed enhanced microstructural uniformity and retarded grain growth with increasing Zr content.

Keywords: BaTiO3, barium-titanate-zirconate, nanoceramics, raman spectroscopy

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Authors: Charmaine Lamiel, Van Hoa Nguyen, Marjorie Baynosa, Jae-Jin Shim

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Electrochemical supercapacitors have attracted considerable attention because of their high potential as an efficient energy storage system. The combination of carbon-based material and transition metal oxides/sulfides are studied because they have long and improved cycle life as well as high energy and power densities. In this study, a hierarchical mesoporous carbon sphere/nickel cobalt sulfide (CS/Ni-Co-S) core/shell structure was synthesized using a facile hydrothermal method without any further sulfurization or post-heat treatment. The CS/Ni-Co-S core/shell microstructures exhibited a high capacitance of 724 F g−1 at 2 A g−1 in a 6 M KOH electrolyte. After 2000 charge-discharge cycles, it retained 86.1% of its original capacitance, with high Coulombic efficiency of 97.9%. The electrode exhibited a high energy density of 58.0 Wh kg−1 at an energy density of 1440 W kg−1, and high power density of 7200 W kg−1 at an energy density of 34.2 Wh kg−1. The successful synthesis was considered to be simple and cost-effective which supports the viability of this composite as an alternative activated material for high performance supercapacitors.

Keywords: carbon sphere, electrochemical, hydrothermal, nickel cobalt sulfide, supercapacitor

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Authors: Chur Hee Lee, Ju Sik Kwak, Seung Wan Kim

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This paper deals about economics and control of optimal placement of multi-terminal HVDC in Korea. Currently, No.1 and 2 HVDC are installed in Jeju and Mainland, Dangjin Godeok HVDC starts operation in 2020. Jeju No.3 HVDC also starts operation in 2022. HVDC systems in Korea are expanding. Also, super grid projects with China, Japan, and Russia are under consideration. In this situation, it is necessary to study how to install optimal HVDC in Korea and how to control it. After initializing the Optical Polwer Flow (OPF) procudure using lossless economic dispatch, grobal iteration will be set. And then, this will be formed as the Lagrangian function and linearizied. We will also analyze the advantages and disadvantages of each operation mode for optimal operating conditions of voltage and current complex HVDC in Korea.

Keywords: economics, HVDC, multi terminal, optimal

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Authors: Parul Sinha

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Electronic commerce facilitates increased choice and information on goods or services for consumers but at the same time it compounds the inequality of bargaining power many consumers face when contracting with sellers. Due to the ‘inequality of bargaining power’ experienced by consumers when contracting by electronic means with business sellers in different jurisdictions, it may be difficult to determine where either the consumer is domiciled or the place where the seller is situated or conducts its business. The question arises in such situation that if one party wants to sue the other, then where can one sue? Which court has jurisdiction to try international conflicts arising from electronic contracts concluded through the internet? Will the same rules applicable to conventional contracts apply? Or should other considerations be taken into account? In all these situations the degree of consumer protection in electronic contracts comes into picture. In the light of the above, the paper discusses the jurisdiction and choice of law rules applied in EU and United States. Further, the paper considers the current uncertainty plaguing questions of jurisdiction in India. Therefore, the jurisdiction and choice of law rules for electronic contracts must be applied consistently and provide an automatic, harmonised rule in favour of the consumer’s jurisdiction and law. Lastly, the paper suggests the need for a uniform law in order to achieve effective juridical protection.

Keywords: electronic commerce, electronic contracts, jurisdiction, consumer protection

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Authors: S. Houcine Habib, B. Elkhalil Hachi, Mohamed Guesmi, Mohamed Haboussi

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In this paper, dynamic fracture behaviors of cracked orthotropic structure are modeled using extended finite element method (X-FEM). In this approach, the finite element method model is first created and then enriched by special orthotropic crack tip enrichments and Heaviside functions in the framework of partition of unity. The mixed mode stress intensity factor (SIF) is computed using the interaction integral technique based on J-integral in order to predict cracking behavior of the structure. The developments of these procedures are programmed and introduced in a self-software platform code. To assess the accuracy of the developed code, results obtained by the proposed method are compared with those of literature.

Keywords: X-FEM, composites, stress intensity factor, crack, dynamic orthotropic behavior

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Authors: Auwal Nata'ala

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The Information and Communication Technology (ICT) has had impacts in almost every area human endeavor. From business, industries, banks to none profit organizations. ICT has simplified business process such as sorting, summarizing, coding, updating and generating a report in a real-time processing mode. However, the use of these ICT facilities such as computer and internet has also brought unintended consequences of criminal activities such as spamming, credit card frauds, ATM frauds, phishing, identity theft, denial of services and other related cyber crimes. This study sought to examined cyber-crime and its impact on the banking institution in Nigeria. It also examined the existing policy framework and assessed the success of the institutional countermeasures in combating cyber crime in the banking industry. This paper X-ray’s cyber crimes, policies issues and provides insight from a Nigeria perspective.

Keywords: cyber crimes, e-banking, policies, ICT

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Authors: Ahmed Mateen, Zhu Qingsheng, Muhammad Awais, Muhammad Yahya Saeed

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This paper targets the rising factor of entrepreneurship innovation, which lacks in Pakistan as compared to the other countries or the regions like China, India, and Malaysia, etc. This is an exploratory and explanatory study. Major aspects have identified as the direction for the policymakers while highlighting the issues in true spirit. IT needs to be considered not only as a technology but also as itself growing as a new community. IT management processes are complex and broad, so generally requires extensive attention to the collective aspects of human variables, capital and technology. In addition, projects tend to have a special set of critical success factors, and if these are processed and given attention, it will improve the chances of successful implementation. This is only possible with state of the art intelligent decision support systems and accumulating IT staff to some extent in decision processes. This paper explores this issue carefully and discusses six issues to observe the implemented strength and possible enhancement.

Keywords: security and defense forces, IT-incentives, big IT-players, IT-entrepreneurial-culture

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Authors: Jutta Hämmerle-Uhl, Georg Penn, Gerhard Pötzelsberger, Andreas Uhl

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Iris codes contain bits with different entropy. This work investigates different strategies to reduce the size of iris code templates with the aim of reducing storage requirements and computational demand in the matching process. Besides simple sub-sampling schemes, also a binary multi-resolution representation as used in the JBIG hierarchical coding mode is assessed. We find that iris code template size can be reduced significantly while maintaining recognition accuracy. Besides, we propose a two stage identification approach, using small-sized iris code templates in a pre-selection satge, and full resolution templates for final identification, which shows promising recognition behaviour.

Keywords: iris recognition, compact iris code, fast matching, best bits, pre-selection identification, two-stage identification

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Authors: Alpha Matthew

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The Composites of Al-Doped K₂CO₃ activated coconut husk carbon, Al₀.₁:(K₂CO₃C)₀.₉ and AI₀.₃:(K₂CO₃C)₀.₇, were prepared using the hydrothermal method and drop casting deposition technique. The electrochemical performance of the Al-doped K₂CO₃ activated coconut husk carbon composite as a promising anode material for lithium-ion batteries was characterised by cyclic voltammetry analysis, electrochemical impedance spectroscopy, and galvanostatic charge discharge analysis. The charges that are retained in the anode material during charging showed a linear decline in charge capacity as the charging current intensity increased. Ionic polarisation was the reason for the observed drop in the charge and discharge capabilities at the current density of 5 A/g. Having greater specific capacitance and energy density, the composite Al₀.₁:(K₂CO₃C)₀.₉ is a better anode material for electrochemical applications compared to AI₀.₃:(K₂CO₃C)₀.₇, also its comparatively higher power density at a scan rate of 5 mV/s is mostly explained by its lower equivalent series resistance.

Keywords: coconut carbon husk, power density, energy density, battery, anode electrode

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Authors: Anil S. Khopkar, Umesh N. Soni

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Surge voltage arises in the system either by switching operations of heavy load or by natural lightning. Surge voltages cause significant failure of power system equipment if adequate protection is not provided. A Surge Arrester is a device connected to a power system to protect the equipment against surge voltages. To protect the transformers against surge voltages, metal oxide surge arresters (MOSA) are connected across each terminal. Basic Insulation Level (BIL) has been defined in national and international standards of transformers based on their voltage rating. While designing transformer insulation, the BIL of the transformer, Surge arrester ratings and its operating voltage have to be considered. However, the performance of transformer insulation largely depends on the ratings of the surge arrester connected, the location of the surge arrester, the margin considered in the insulation design, the quantity of surge voltage strike, etc. This paper demonstrates the role of Surge arresters in the protection of transformers against over-voltage, transformer insulation design, optimum location of surge arresters and their connection lead length, Insulation coordination for transformer, protection margin in BIL and methods of protection of transformers against surge voltages, in detail.

Keywords: surge voltage, surge arresters, insulation coordination, protection margin

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Authors: Parviz Almasi

Abstract:

Ethylene is produced as a gaseous growth regulator in all plants and their constructive parts such as roots, stems, leaves, flowers and fruits. It is considered a multifunctional phytohormone that regulates both growths including flowering, fruit ripening, inhibition of root growth, and senescence such as senescence of leaves and flowers and etc. In addition, exposure to external ethylene is caused some changes that are often undesirable and harmful. Some flowers are more sensitive to others and when exposed to ethylene; their aging process is hastened. 1-MCP is an exogenous and endogenous ethylene action inhibitor, which binds to the ethylene receptors in the plants and prevents ethylene-dependent reactions. The binding affinity of 1- MCP for the receptors is about 10 times more than ethylene. Hence, 1-MCP can be a potential candidate for controlling of ethylene injury in horticultural crops. This review integrates knowledge of ethylene biosynthesis in the plants and also a mode of action of 1-MCP in preventing of ethylene injury.

Keywords: ethylene injury, biosynthesis, ethylene sensitivity, 1-MCP

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Authors: Harish Aryal, Roger Hague, Daniel Sotelo, Felipe Astete Salinas

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This paper presents a comparative study of different coolants, materials, and temperatures that can affect the effectiveness of heat exchangers that are used in small modular reactors. The corrugated plate heat exchangers were chosen out of different plate options for testing purposes because of their ease of access and better performance than other existing heat exchangers in recent years. SolidWorks enables us to see various results between water coolants and helium coolants acting upon different types of conducting metals, which were selected from different fluids that ultimately satisfied accessibility requirements and were compatible with the software. Though not every element, material, fluid, or method was used in the testing phase, their purpose is to help further research that is to come since the innovation of nuclear power is the future. The tests that were performed are to help better understand the constant necessities that are seen in heat exchangers and through every adjustment see what the breaking points or improvements in the machine are. Depending on consumers and researchers, the results may give further feedback as to show why different types of materials and fluids would be preferred and why it is necessary to keep failures to improve future research.

Keywords: heat exchangers, Solidworks, coolants, small modular reactors, nuclear power, nanofluids, Nusselt number, friction factor, Reynolds number

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Authors: Vladimir V. Nikulin, Bekmurza H. Aitchanov, Olimzhon A. Baimuratov

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Quantum communication technology takes advantage of the intrinsic properties of laser carriers, such as very high data rates and low power requirements, to offer unprecedented data security. Quantum processes at the physical layer of encryption are used for signal encryption with very competitive performance characteristics. The ultimate range of applications for QC systems spans from fiber-based to free-space links and from secure banking operations to mobile airborne and space-borne networking where they are subjected to channel distortions. Under practical conditions, the channel can alter the optical wave front characteristics, including its phase. In addition, phase noise of the communication source and photo-detection noises alter the signal to bring additional ambiguity into the measurement process. If quantized values of photons are used to encrypt the signal, exploitation of quantum communication links becomes extremely difficult. In this paper, we present the results of analysis and simulation studies of the effects of noise on phase estimation for quantum systems with different number of encryption bases and operating at different power levels.

Keywords: encryption, phase distortion, quantum communication, quantum noise

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Authors: Vishweshwar V. Dixit

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Kannudi is a reference editor introducing a method of input for Kannada, called OHOK!, that is, Ottu Hāku Ottu Koḍu!. This is especially suited for pressure-sensitive input devices, though the current online implementation uses the regular mechanical keyboard. OHOK! has three possible modes, namely, sva-ottu (self-conjunct), kandante (as you see), and andante (as you say). It may be noted that kandante mode does not follow the phonetic order. However, this model may work well for those who are inclined to visualize as they type rather than vocalize the sounds. Kannudi also demonstrates how domain knowledge can be effectively used to potentially increase speed, accuracy, and user-friendliness. For example, selection of a default vowel, automatic shunyification, and arkification. Also implemented are four types of Deletes that are necessary for phono-syllabic languages like Kannada.

Keywords: kannada, conjunct, reference editor, pressure input

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Authors: Okezie A. Ihugba

Abstract:

The bounds testing ARDL (2, 2, 2, 2, 0) technique to cointegration was used in this study to investigate the effect of energy consumption and energy loss on Nigeria's manufacturing sector from 1981 to 2020. The model was created to determine the relationship between these three variables while also accounting for interactions with control variables such as inflation and commercial bank loans to the manufacturing sector. When the dependent variables are energy consumption and energy loss, the bounds tests show that the variables of interest are bound together in the long run. Because electricity consumption is a critical factor in determining manufacturing value-added in Nigeria, some intriguing observations were made. According to the findings, the relationship between LELC and LMVA is statistically significant. According to the findings, electricity consumption reduces manufacturing value-added. The target variable (energy loss) is statistically significant and has a positive sign. In Nigeria, a 1% reduction in energy loss increases manufacturing value-added by 36% in the first lag and 35% in the second. According to the study, the government should speed up the ongoing renovation of existing power plants across the country, as well as the construction of new gas-fired power plants. This will address a number of issues, including overpricing of electricity as a result of grid failure.

Keywords: L60, Q43, H81, C52, E31, ARDL, cointegration, Nigeria's manufacturing

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Authors: Thomas Yeboah

Abstract:

In recent times, micro-finance programmes targeting women have become the central means of donor poverty alleviation strategies. In view of the renewed focus on post-Millennium Development Goals (MDGs) poverty reduction strategies, there is the likelihood that funding might increase in the next coming decades to support different initiatives by donor agencies. In this paper, we critically examine the role of microfinance in shaping gender relations and empowerment outcomes of women. It is widely argued that providing and reaching out to women with credit methodologies serves as a means of increasing women’s bargaining power and challenging existing gender subordination thereby releasing them from power structures which dominate their lives. This paper cautions this view and instead show that the mainstream argument surrounding microfinance and gender empowerment is much complex than what the popular rhetoric preaches. Drawing on empirical cases on microfinance literature, we argue that lack of systematic strategy to incorporate men and the wider socio-cultural dynamics within which women’s lives are embedded radically constraints the empowerment potential of microcredit programmes and in some context may lead to unintended consequences for women.

Keywords: microfinance, empowerment, women, men, gender relations

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Authors: Megha Rao, Søren H. Jensen, Xiufu Sun, Anke Hagen, Mogens B. Mogensen

Abstract:

Solid oxide electrolysis cells have an immense potential in converting CO₂ and H₂O into syngas during co-electrolysis operation. The produced syngas can be further converted into hydrocarbons. This kind of technology is called power-to-gas or power-to-liquid. To produce hydrocarbons via this route, durability of the cells is still a challenge, which needs to be further investigated in order to improve the cells. In this work, various nickel-yttria stabilized zirconia (Ni-YSZ) fuel electrode supported or YSZ electrolyte supported cells, cerium gadolinium oxide (CGO) barrier layer, and an oxygen electrode are investigated for durability under co-electrolysis conditions in both galvanostatic and potentiostatic conditions. While changing the gas on the oxygen electrode, keeping the fuel electrode gas composition constant, a change in the gas concentration arc was observed by impedance spectroscopy. Measurements of open circuit potential revealed the presence of leaks in the setup. It is speculated that the change in concentration impedance may be related to the leaks. Furthermore, the cells were also tested under pressurized conditions to find an inter-play between the leak rate and the pressure. A mathematical modeling together with electrochemical and microscopy analysis is presented.

Keywords: co-electrolysis, durability, leaks, gas concentration arc

Procedia PDF Downloads 148