Search results for: low current density
11160 Seeking Compatibility between Green Infrastructure and Recentralization: The Case of Greater Toronto Area
Authors: Sara Saboonian, Pierre Filion
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There are two distinct planning approaches attempting to transform the North American suburb so as to reduce its adverse environmental impacts. The first one, the recentralization approach, proposes intensification, multi-functionality and more reliance on public transit and walking. It thus offers an alternative to the prevailing low-density, spatial specialization and automobile dependence of the North American suburb. The second approach concentrates instead on the provision of green infrastructure, which rely on natural systems rather than on highly engineered solutions to deal with the infrastructure needs of suburban areas. There are tensions between these two approaches as recentralization generally overlooks green infrastructure, which can be space consuming (as in the case of water retention systems), and thus conflicts with the intensification goals of recentralization. The research investigates three Canadian planned suburban centres in the Greater Toronto Area, where recentralization is the current planning practice, despite rising awareness of the benefits of green infrastructure. Methods include reviewing the literature on green infrastructure planning, a critical analysis of the Ontario provincial plans for recentralization, surveying residents’ preferences regarding alternative suburban development models, and interviewing officials who deal with the local planning of the three centres. The case studies expose the difficulties in creating planned suburban centres that accommodate green infrastructure while adhering to recentralization principles. Until now, planners have been mostly focussed on recentralization at the expense of green infrastructure. In this context, the frequent lack of compatibility between recentralization and the space requirements of green infrastructure explains the limited presence of such infrastructures in planned suburban centres. Finally, while much attention has been given in the planning discourse to the economic and lifestyle benefits of recentralization, much less has been made of the wide range of advantages of green infrastructure, which explains limited public mobilization over the development of green infrastructure networks. The paper will concentrate on ways of combining recentralization with green infrastructure strategies and identify the aspects of the two approaches that are most compatible with each other. The outcome of such blending will marry high density, public-transit oriented developments, which generate walkability and street-level animation, with the presence of green space, naturalized settings and reliance on renewable energy. The paper will advance a planning framework that will fuse green infrastructure with recentralization, thus ensuring the achievement of higher density and reduced reliance on the car along with the provision of critical ecosystem services throughout cities. This will support and enhance the objectives of both green infrastructure and recentralization.Keywords: environmental-based planning, green infrastructure, multi-functionality, recentralization
Procedia PDF Downloads 12811159 How the Current Opioid Crisis Differs from the Heroin Epidemic of the 1960s-1970s: An Analysis of Drugs and Demographics
Authors: Donna L. Roberts
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Heroin has appeared on the drug scene before. Yet the current opioid crisis differs in significant ways. In order to address the grave challenges, this epidemic poses, the unique precipitating and sustaining conditions must be thoroughly examined. This research explored the various aspects of the political, economic, and social conditions that created a 'perfect storm' for the evolution and maintenance of the current opioid crisis. Specifically, the epidemiology, demographics, and progression of addiction inherent in the current crisis were compared to the patterns of past opioid use. Additionally, the role of pharmaceutical companies and prescribing physicians, the nature and pharmaceutical properties of the available substances and the changing socioeconomic climate were considered. Results indicated that the current crisis differs significantly with respect to its evolution, magnitude, prevalence, and widespread societal effects. Precipitated by a proliferation of prescription medication and sustained by the availability of cheaper, more potent street drugs, including new versions of synthetic opioids, the current crisis presents unprecedented challenges affecting a wider and more diverse segment of society. The unique aspects of this epidemic demand unique approaches to addressing the problem. Understanding these differences is a key step in working toward a practical and enduring solution.Keywords: addiction, drug abuse, opioids, opioid crisis
Procedia PDF Downloads 14511158 Negative Sequence-Based Protection Techniques for Microgrid Connected Power Systems
Authors: Isabelle Snyder, Travis Smith
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Microgrid protection presents challenges to conventional protection techniques due to the low-induced fault current. Protection relays present in microgrid applications require a combination of settings groups to adjust based on the architecture of the microgrid in islanded and grid-connected modes. In a radial system where the microgrid is at the other end of the feeder, directional elements can be used to identify the direction of the fault current and switch settings groups accordingly (grid-connected or microgrid-connected). However, with multiple microgrid connections, this concept becomes more challenging, and the direction of the current alone is not sufficient to identify the source of the fault current contribution. ORNL has previously developed adaptive relaying schemes through other DOE-funded research projects that will be evaluated and used as a baseline for this research. The four protection techniques in this study are labeled as follows: (1) Adaptive Current only Protection System (ACPS), Intentional (2) Unbalanced Control for Protection Control (IUCPC), (3) Adaptive Protection System with Communication Controller (APSCC) (4) Adaptive Model-Driven Protective Relay (AMDPR).Keywords: adaptive relaying, microgrid protection, sequence components, islanding detection
Procedia PDF Downloads 8211157 A Generalization of Option Pricing with Discrete Dividends to Markets with Daily Price Limits
Authors: Jiahau Guo, Yihe Zhang
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This paper proposes solutions for pricing options on stocks paying discrete dividends in markets with daily price limits. We first extend the intraday density function of Guo and Chang (2020) to a multi-day one and use the framework of Haug et al. (2003) to value European options on stocks paying discrete dividends. Next, we adopt the fast Fourier transform (FFT) to derive accurate and efficient formulae for American options and further employ the three-point Richardson extrapolation to accelerate the computation. Finally, the accuracy of our proposed methods is verified by simulations.Keywords: daily price limit, discrete dividend, early exercise, fast Fourier transform, multi-day density function, Richardson extrapolation
Procedia PDF Downloads 15511156 Development and Characterization of Cathode Materials for Sodium-Metal Chloride Batteries
Authors: C. D’Urso, L. Frusteri, M. Samperi, G. Leonardi
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Solid metal halides are used as active cathode ingredients in the case of Na-NiCl2 batteries that require a fused secondary electrolyte, sodium tetrachloraluminate (NaAlCl4), to facilitate the movement of the Na+ ion into the cathode. The sodium-nickel chloride (Na - NiCl2) battery has been extensively investigated as a promising system for large-scale energy storage applications. The growth of Ni and NaCl particles in the cathodes is one of the most important factors that degrade the performance of the Na-NiCl2 battery. The larger the particles of active ingredients contained in the cathode, the smaller the active surface available for the electrochemical reaction. Therefore, the growth of Ni and NaCl particles can lead to an increase in cell polarization resulting from the reduced active area. A higher current density, a higher state of charge (SOC) at the end of the charge (EOC) and a lower Ni / NaCl ratio are the main parameters that result in the rapid growth of Ni particles. In light of these problems, cathode and chemistry Nano-materials with recognized and well-documented electrochemical functions have been studied and manufactured to simultaneously improve battery performance and develop less expensive and more performing, sustainable and environmentally friendly materials. Starting from the well-known cathodic material (Na-NiCl2), the new electrolytic materials have been prepared on the replacement of nickel with iron (10-90%substitution of Nichel with Iron), to obtain a new material with potential advantages compared to current battery technologies; for example,, (1) lower cost of cathode material compared to state of the art as well as (2) choices of cheaper materials (stainless steels could be used for cell components, including cathode current collectors and cell housings). The study on the particle size of the cathode and the physicochemical characterization of the cathode was carried out in the test cell using, where possible, the GITT method (galvanostatic technique of intermittent titration). Furthermore, the impact of temperature on the different cathode compositions of the positive electrode was studied. Especially the optimum operating temperature is an important parameter of the active material.Keywords: critical raw materials, energy storage, sodium metal halide, battery
Procedia PDF Downloads 9811155 Review of Various Designs and Development in Hydropower Turbines
Authors: Fatemeh Behrouzi, Adi Maimun, Mehdi Nakisa
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The growth of population, rising fossil fuel prices which the fossil fuels are limited and decreased day by day, pollution problem due to use of fossil fuels and electrical demand are important role to encourage of using the green energy and renewable technologies. Among different renewable energy technologies, hydro power generation (large and small scale) is the prime choice in terms of contribution to the world's electricity generation by using water current turbines. Nowadays, researchers focus on design and development of different kind of turbines to capture hydro-power electricity generation as clean and reliable energy. This article is review about statues of water current turbines carried out to generate electricity from hydro-kinetic energy especially places that they do not have electricity, but they have access to the current water.Keywords: water current turbine, renewable energy, hydro-power, mechanic
Procedia PDF Downloads 46611154 X-Ray and DFT Electrostatics Parameters Determination of a Coumarin Derivative Compound C17H13NO3
Authors: Y. Megrous, A. Chouaih, F. Hamzaoui
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The crystal structure of 4-Methyl-7-(salicylideneamino)coumarin C17H13NO3has been determined using X-ray diffraction to establish the configuration and stereochemistry of the molecule. This crystal is characterized by its nolinear activity. The molecular electron charge density distribution of the title compound is described accurately using the multipolar model of Hansen and Coppens. The net atomic charge and the molecular dipole moment in-crystal have been determined in order to understand the nature of inter-and intramolecular charge transfer. The study present the thermal motion and the structural analysis obtained from the least-square refinement on F2,this study has also allowed us to determine the electrostatic potential and therefore locate the electropositive part and the electronegative part in molecular scale of the title compound.Keywords: electron charge density, net atomic charge, molecular dipole moment, X-ray diffraction
Procedia PDF Downloads 44911153 Brake Force Distribution in Passenger Cars
Authors: Boukhris Lahouari, Bouchetara Mostefa
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The active safety of a vehicle is mainly influenced by the properties of the installed braking system. With the increase in road traffic density and travel speeds, increasingly stringent requirements are placed on the vehicle's behaviour during braking. The achievable decelerations are limited by the physical aspect characterized by the coefficient of friction between the tires and the ground. As a result, it follows that an optimized distribution of braking forces becomes necessary for a better use of friction coefficients. This objective could only be achieved if sufficient knowledge is available on the theory of vehicle dynamics during braking and on current standards for the approval of braking systems. These will facilitate the development of a braking force calculation algorithm that will enable an optimized distribution of braking forces to be achieved. Operating safety is conditioned by the requirements of efficiency, progressiveness, regularity or fidelity of a braking system without obviously neglecting the recommendations imposed by the legislator.Keywords: brake force distribution, distribution diagram, friction coefficient, brake by wire
Procedia PDF Downloads 7311152 Metal Layer Based Vertical Hall Device in a Complementary Metal Oxide Semiconductor Process
Authors: Se-Mi Lim, Won-Jae Jung, Jin-Sup Kim, Jun-Seok Park, Hyung-Il Chae
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This paper presents a current-mode vertical hall device (VHD) structure using metal layers in a CMOS process. The proposed metal layer based vertical hall device (MLVHD) utilizes vertical connection among metal layers (from M1 to the top metal) to facilitate hall effect. The vertical metal structure unit flows a bias current Ibias from top to bottom, and an external magnetic field changes the current distribution by Lorentz force. The asymmetric current distribution can be detected by two differential-mode current outputs on each side at the bottom (M1), and each output sinks Ibias/2 ± Ihall. A single vertical metal structure generates only a small amount of hall effect of Ihall due to the short length from M1 to the top metal as well as the low conductivity of the metal, and a series connection between thousands of vertical structure units can solve the problem by providing NxIhall. The series connection between two units is another vertical metal structure flowing current in the opposite direction, and generates negative hall effect. To mitigate the negative hall effect from the series connection, the differential current outputs at the bottom (M1) from one unit merges on the top metal level of the other unit. The proposed MLVHD is simulated in a 3-dimensional model simulator in COMSOL Multiphysics, with 0.35 μm CMOS process parameters. The simulated MLVHD unit size is (W) 10 μm × (L) 6 μm × (D) 10 μm. In this paper, we use an MLVHD with 10 units; the overall hall device size is (W) 10 μm × (L)78 μm × (D) 10 μm. The COMSOL simulation result is as following: the maximum hall current is approximately 2 μA with a 12 μA bias current and 100mT magnetic field; This work was supported by Institute for Information & communications Technology Promotion(IITP) grant funded by the Korea government(MSIP) (No.R7117-16-0165, Development of Hall Effect Semiconductor for Smart Car and Device).Keywords: CMOS, vertical hall device, current mode, COMSOL
Procedia PDF Downloads 29611151 The Effect of Soil Reinforcement on Pullout Behaviour of Flat Under-Reamer Anchor Pile Placed in Sand
Authors: V. K. Arora, Amit Rastogi
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To understand the anchor pile behaviour and to predict the capacity of piles under uplift loading are important concerns in foundation analysis. Experimental model tests have been conducted on single anchor pile embedded in cohesionless soil and subjected to pure uplift loading. A gravel-filled geogrid layer was located around the enlarged pile base. The experimental tests were conducted on straight-shafted vertical steel piles with an outer diameter of 20 mm in a steel soil tank. The tested piles have embedment depth-to-diameter ratios (L/D) of 2, 3, and 4. The sand bed is prepared at three different values of density of 1.67, 1.59, and 1.50gm/cc. Single piles embedded in sandy soil were tested and the results are presented and analysed in this paper. The influences of pile embedment ratio, reinforcement, relative density of soil on the uplift capacity of piles were investigated. The study revealed that the behaviour of single piles under uplift loading depends mainly on both the pile embedment depth-to-diameter ratio and the soil density. It is believed that the experimental results presented in this study would be beneficial to the professional understanding of the soil–pile-uplift interaction problem.Keywords: flat under-reamer anchor pile, geogrid, pullout reinforcement, soil reinforcement
Procedia PDF Downloads 46211150 Contour Defects of Face with Hyperpigmentation
Authors: Afzaal Bashir, Sunaina Afzaal
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Background: Facial contour deformities associated with pigmentary changes are of major concern for plastic surgeons, both being important and difficult in treating such issues. No definite ideal treatment option is available to simultaneously address both the contour defect as well as related pigmentation. Objectives: The aim of the current study is to compare the long-term effects of conventional adipose tissue grafting and ex-vivo expanded Mesenchymal Stem Cells enriched adipose tissue grafting for the treatment of contour deformities with pigmentary changes on the face. Material and Methods: In this study, eighty (80) patients with contour deformities of the face with hyperpigmentation were recruited after informed consent. Two techniques i.e., conventional fat grafting (C-FG) and fat grafts enriched with expanded adipose stem cells (FG-ASCs), were used to address the pigmentation. Both techniques were explained to patients, and enrolled patients were divided into two groups i.e., C-FG and FG-ASCS, per patients’ choice and satisfaction. Patients of the FG-ASCs group were treated with fat grafts enriched with expanded adipose stem cells, while patients of the C-FGs group were treated with conventional fat grafting. Patients were followed for 12 months, and improvement in face pigmentation was assessed clinically as well as measured objectively. Patient satisfaction was also documented as highly satisfied, satisfied, and unsatisfied. Results: Mean age of patients was 24.42(±4.49), and 66 patients were females. The forehead was involved in 61.20% of cases, the cheek in 21.20% of cases, the chin in 11.20% of cases, and the nose in 6.20% of cases. In the GF-ASCs group, the integrated color density (ICD) was decreased (1.08×10⁶ ±4.64×10⁵) as compared to the C-FG group (2.80×10⁵±1.69×10⁵). Patients treated with fat grafts enriched with expanded adipose stem cells were significantly more satisfied as compared to patients treated with conventional fat grafting only. Conclusion: Mesenchymal stem cell-enriched autologous fat grafting is a preferred option for improving the contour deformities related to increased pigmentation of face skin.Keywords: hyperpigmentation, color density, enriched adipose tissue graft, fat grafting, contour deformities, Image J
Procedia PDF Downloads 10111149 Golf Industry in China: An Examination in the Reason behind Its Underdevelopment
Authors: Haoqiang Zhang
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Golf is usually defined as “a sport for the wealthy” in China. With relatively few people playing golf and having only two professional golf players nationwide, China is lagging in adopting golf as a sport. The current research used a literature review to examine the political and educational reasons behind this phenomenon. In addition, the current study compared the sports education system between U.S. and China and showed its significant role in adopting sports like golf. Lastly, the current research proposed hypothetical solutions from the educational and societal perspective on how to make China adopt golf as a global sport.Keywords: golf education, golf in China, sports economics, sports education
Procedia PDF Downloads 6811148 Fiber Release from Fabrics with Various Weave Parameters and Finishing Treatments during Washing and Their Marine Biodegradation
Authors: Seoyoun Kim, Chunghee Park
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Microplastics have recently become an issue due to their potentially harmful effects on the marine environment and the human body. The purpose of this study is to investigate the correlation of fiber emissions during the home laundering with the fabric parameters such as yarn density, warp/weft density, and weave structure. Also, the effect of finishing treatments such as reactive dyeing, water-repellent finish, peach skin finish on fiber emissions was evaluated. Furthermore, we studied the biodegradability of fibers in the marine environment compared to those in soil burial and the impact of finishing treatment on the biodegradability. Biodegradability was evaluated by measuring BOD values and tensile strength reduction. The results showed that more fibers were released in the thicker yarn, lower weave density. Also, a weave structure which has less compactness, released more fibers. Peach skin finish with microfibers exposed on the surface caused more fiber release, whereas water-repellent finish reduced the fiber emission. In addition, the biodegradability of the fabrics submerged in the marine environment were lower compared with those buried in the soil. Also, the water-repellent fabric was less biodegradable than the untreated one. Further research is suggested considering the fabrics with various chemical components or geometry and their fouling behavior in the marine environment.Keywords: biodegradation, fibers, microplastic, pollution
Procedia PDF Downloads 13111147 In-Situ Quasistatic Compression and Microstructural Characterization of Aluminium Foams of Different Cell Topology
Authors: M. A. Islam, P. J. Hazell, J. P. Escobedo, M. Saadatfar
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Quasistatic compression and micro structural characterization of closed cell aluminium foams of different pore size and cell distributions has been carried out. Metallic foams have good potential for lightweight structures for impact and blast mitigation and therefore it is important to find out the optimized foam structure (i.e. cell size, shape, relative density, and distribution) to maximize energy absorption. In this paper, we present results for two different aluminium metal foams of density 0.5 g/cc and 0.7 g/cc respectively that have been tested in quasi-static compression. The influence of cell geometry and cell topology on quasistatic compression behavior has been investigated using computed tomography (micro-CT) analysis. The compression behavior and micro structural characterization will be presented.Keywords: metal foams, micro-CT, cell topology, quasistatic compression
Procedia PDF Downloads 45011146 Carbon Nanotube Field Effect Transistor - a Review
Authors: P. Geetha, R. S. D. Wahida Banu
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The crowning advances in Silicon based electronic technology have dominated the computation world for the past decades. The captivating performance of Si devices lies in sustainable scaling down of the physical dimensions, by that increasing device density and improved performance. But, the fundamental limitations due to physical, technological, economical, and manufacture features restrict further miniaturization of Si based devices. The pit falls are due to scaling down of the devices such as process variation, short channel effects, high leakage currents, and reliability concerns. To fix the above-said problems, it is needed either to follow a new concept that will manage the current hitches or to support the available concept with different materials. The new concept is to design spintronics, quantum computation or two terminal molecular devices. Otherwise, presently used well known three terminal devices can be modified with different materials that suits to address the scaling down difficulties. The first approach will occupy in the far future since it needs considerable effort; the second path is a bright light towards the travel. Modelling paves way to know not only the current-voltage characteristics but also the performance of new devices. So, it is desirable to model a new device of suitable gate control and project the its abilities towards capability of handling high current, high power, high frequency, short delay, and high velocity with excellent electronic and optical properties. Carbon nanotube became a thriving material to replace silicon in nano devices. A well-planned optimized utilization of the carbon material leads to many more advantages. The unique nature of this organic material allows the recent developments in almost all fields of applications from an automobile industry to medical science, especially in electronics field-on which the automation industry depends. More research works were being done in this area. This paper reviews the carbon nanotube field effect transistor with various gate configurations, number of channel element, CNT wall configurations and different modelling techniques.Keywords: array of channels, carbon nanotube field effect transistor, double gate transistor, gate wrap around transistor, modelling, multi-walled CNT, single-walled CNT
Procedia PDF Downloads 31511145 Minimizing Vehicular Traffic via Integrated Land Use Development: A Heuristic Optimization Approach
Authors: Babu Veeregowda, Rongfang Liu
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The current traffic impact assessment methodology and environmental quality review process for approval of land development project are conventional, stagnant, and one-dimensional. The environmental review policy and procedure lacks in providing the direction to regulate or seek alternative land uses and sizes that exploits the existing or surrounding elements of built environment (‘4 D’s’ of development – Density, Diversity, Design, and Distance to Transit) or smart growth principles which influence the travel behavior and have a significant effect in reducing vehicular traffic. Additionally, environmental review policy does not give directions on how to incorporate urban planning into the development in ways such as incorporating non-motorized roadway elements such as sidewalks, bus shelters, and access to community facilities. This research developed a methodology to optimize the mix of land uses and sizes using the heuristic optimization process to minimize the auto dependency development and to meet the interests of key stakeholders. A case study of Willets Point Mixed Use Development in Queens, New York, was used to assess the benefits of the methodology. The approved Willets Point Mixed Use project was based on maximum envelop of size and land use type allowed by current conventional urban renewal plans. This paper will also evaluate the parking accumulation for various land uses to explore the potential for shared parking to further optimize the mix of land uses and sizes. This research is very timely and useful to many stakeholders interested in understanding the benefits of integrated land uses and its development.Keywords: traffic impact, mixed use, optimization, trip generation
Procedia PDF Downloads 20611144 Performance Evaluation of Routing Protocols in Vehicular Adhoc Networks
Authors: Salman Naseer, Usman Zafar, Iqra Zafar
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This study explores the implication of Vehicular Adhoc Network (VANET) - in the rural and urban scenarios that is one domain of Mobile Adhoc Network (MANET). VANET provides wireless communication between vehicle to vehicle and also roadside units. The Federal Commission Committee of United States of American has been allocated 75 MHz of the spectrum band in the 5.9 GHz frequency range for dedicated short-range communications (DSRC) that are specifically designed to enhance any road safety applications and entertainment/information applications. There are several vehicular related projects viz; California path, car 2 car communication consortium, the ETSI, and IEEE 1609 working group that have already been conducted to improve the overall road safety or traffic management. After the critical literature review, the selection of routing protocols is determined, and its performance was well thought-out in the urban and rural scenarios. Numerous routing protocols for VANET are applied to carry out current research. Its evaluation was conceded with the help of selected protocols through simulation via performance metric i.e. throughput and packet drop. Excel and Google graph API tools are used for plotting the graphs after the simulation results in order to compare the selected routing protocols which result with each other. In addition, the sum of the output from each scenario was computed to undoubtedly present the divergence in results. The findings of the current study present that DSR gives enhanced performance for low packet drop and high throughput as compared to AODV and DSDV in an urban congested area and in rural environments. On the other hand, in low-density area, VANET AODV gives better results as compared to DSR. The worth of the current study may be judged as the information exchanged between vehicles is useful for comfort, safety, and entertainment. Furthermore, the communication system performance depends on the way routing is done in the network and moreover, the routing of the data based on protocols implement in the network. The above-presented results lead to policy implication and develop our understanding of the broader spectrum of VANET.Keywords: AODV, DSDV, DSR, Adhoc network
Procedia PDF Downloads 27711143 Design and Performance Evaluation of Synchronous Reluctance Machine (SynRM)
Authors: Hadi Aghazadeh, Mohammadreza Naeimi, Seyed Ebrahim Afjei, Alireza Siadatan
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Torque ripple, maximum torque and high efficiency are important issues in synchronous reluctance machine (SynRM). This paper presents a view on design of a high efficiency, low torque ripple and high torque density SynRM. To achieve this goal SynRM parameters is calculated (such as insulation ratios in the d-and q-axes and the rotor slot pitch), while the torque ripple can be minimized by determining the best rotor slot pitch in the d-axis. The presented analytical-finite element method (FEM) approach gives the optimum distribution of air gap and iron portion for the maximizing torque density with minimum torque ripple.Keywords: torque ripple, efficiency, insulation ratio, FEM, synchronous reluctance machine (SynRM), induction motor (IM)
Procedia PDF Downloads 21611142 Complete Enumeration Approach for Calculation of Residual Entropy for Diluted Spin Ice
Authors: Yuriy A. Shevchenko, Konstantin V. Nefedev
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We consider the antiferromagnetic systems of Ising spins located at the sites of the hexagonal, triangular and pyrochlore lattices. Such systems can be diluted to a certain concentration level by randomly replacing the magnetic spins with nonmagnetic ones. Quite recently we studied density of states (DOS) was calculated by the Wang-Landau method. Based on the obtained data, we calculated the dependence of the residual entropy (entropy at a temperature tending to zero) on the dilution concentration for quite large systems (more than 2000 spins). In the current study, we obtained the same data for small systems (less than 20 spins) by a complete search of all possible magnetic configurations and compared the result with the result for large systems. The shape of the curve remains unchanged in both cases, but the specific values of the residual entropy are different because of the finite size effect.Keywords: entropy, pyrochlore, spin ice, Wang-Landau algorithm
Procedia PDF Downloads 25811141 Structural, Electronic and Optical Properties of LiₓNa1-ₓH for Hydrogen Storage
Authors: B. Bahloul
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This study investigates the structural, electronic, and optical properties of LiH and NaH compounds, as well as their ternary mixed crystals LiₓNa1-ₓH, adopting a face-centered cubic structure with space group Fm-3m (number 225). The structural and electronic characteristics are examined using density functional theory (DFT), while empirical methods, specifically the modified Moss relation, are employed for analyzing optical properties. The exchange-correlation potential is determined through the generalized gradient approximation (PBEsol-GGA) within the density functional theory (DFT) framework, utilizing the projected augmented wave pseudopotentials (PAW) approach. The Quantum Espresso code is employed for conducting these calculations. The calculated lattice parameters at equilibrium volume and the bulk modulus for x=0 and x=1 exhibit good agreement with existing literature data. Additionally, the LiₓNa1-ₓH alloys are identified as having a direct band gap.Keywords: DFT, structural, electronic, optical properties
Procedia PDF Downloads 6011140 Mapping Soils from Terrain Features: The Case of Nech SAR National Park of Ethiopia
Authors: Shetie Gatew
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Current soil maps of Ethiopia do not represent accurately the soils of Nech Sar National Park. In the framework of studies on the ecology of the park, we prepared a soil map based on field observations and a digital terrain model derived from SRTM data with a 30-m resolution. The landscape comprises volcanic cones, lava and basalt outflows, undulating plains, horsts, alluvial plains and river deltas. SOTER-like terrain mapping units were identified. First, the DTM was classified into 128 terrain classes defined by slope gradient (4 classes), relief intensity (4 classes), potential drainage density (2 classes), and hypsometry (4 classes). A soil-landscape relation between the terrain mapping units and WRB soil units was established based on 34 soil profile pits. Based on this relation, the terrain mapping units were either merged or split to represent a comprehensive soil and terrain map. The soil map indicates that Leptosols (30 %), Cambisols (26%), Andosols (21%), Fluvisols (12 %), and Vertisols (9%) are the most widespread Reference Soil Groups of the park. In contrast, the harmonized soil map of Africa derived from the FAO soil map of the world indicates that Luvisols (70%), Vertisols (14%) and Fluvisols (16%) would be the most common Reference Soil Groups. However, these latter mapping units are not consistent with the topography, nor did we find such extensive areas occupied by Luvisols during the field survey. This case study shows that with the now freely available SRTM data, it is possible to improve current soil information layers with relatively limited resources, even in a complex terrain like Nech Sar National Park.Keywords: andosols, cambisols, digital elevation model, leptosols, soil-landscaps relation
Procedia PDF Downloads 9611139 A Remote Sensing Approach to Calculate Population Using Roads Network Data in Lebanon
Authors: Kamel Allaw, Jocelyne Adjizian Gerard, Makram Chehayeb, Nada Badaro Saliba
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In developing countries, such as Lebanon, the demographic data are hardly available due to the absence of the mechanization of population system. The aim of this study is to evaluate, using only remote sensing data, the correlations between the number of population and the characteristics of roads network (length of primary roads, length of secondary roads, total length of roads, density and percentage of roads and the number of intersections). In order to find the influence of the different factors on the demographic data, we studied the degree of correlation between each factor and the number of population. The results of this study have shown a strong correlation between the number of population and the density of roads and the number of intersections.Keywords: population, road network, statistical correlations, remote sensing
Procedia PDF Downloads 15211138 Investigation of the Brake Force Distribution in Passenger Cars
Authors: Boukhris Lahouari, Bouchetara Mostefa
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The active safety of a vehicle is mainly influenced by the properties of the installed braking system. With the increase in road traffic density and travel speeds, increasingly stringent requirements are placed on the vehicle's behaviour during braking. The achievable decelerations are limited by the physical aspect characterized by the coefficient of friction between the tires and the ground. As a result, it follows that an optimized distribution of braking forces becomes necessary for a better use of friction coefficients. This objective could only be achieved if sufficient knowledge is available on the theory of vehicle dynamics during braking and on current standards for the approval of braking systems. This will facilitate the development of a braking force calculation algorithm that will enable an optimized distribution of braking forces to be achieved. Operating safety is conditioned by the requirements of efficiency, progressiveness, regularity or fidelity of a braking system without obviously neglecting the recommendations imposed by the legislator.Keywords: brake force distribution, distribution diagram, friction coefficient, brake by wire
Procedia PDF Downloads 7411137 Experimental Measurement of Equatorial Ring Current Generated by Magnetoplasma Sail in Three-Dimensional Spatial Coordinate
Authors: Masato Koizumi, Yuya Oshio, Ikkoh Funaki
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Magnetoplasma Sail (MPS) is a future spacecraft propulsion that generates high levels of thrust by inducing an artificial magnetosphere to capture and deflect solar wind charged particles in order to transfer momentum to the spacecraft. By injecting plasma in the spacecraft’s magnetic field region, the ring current azimuthally drifts on the equatorial plane about the dipole magnetic field generated by the current flowing through the solenoid attached on board the spacecraft. This ring current results in magnetosphere inflation which improves the thrust performance of MPS spacecraft. In this present study, the ring current was experimentally measured using three Rogowski Current Probes positioned in a circular array about the laboratory model of MPS spacecraft. This investigation aims to determine the detailed structure of ring current through physical experimentation performed under two different magnetic field strengths engendered by varying the applied voltage on the solenoid with 300 V and 600 V. The expected outcome was that the three current probes would detect the same current since all three probes were positioned at equal radial distance of 63 mm from the center of the solenoid. Although experimental results were numerically implausible due to probable procedural error, the trends of the results revealed three pieces of perceptive evidence of the ring current behavior. The first aspect is that the drift direction of the ring current depended on the strength of the applied magnetic field. The second aspect is that the diamagnetic current developed at a radial distance not occupied by the three current probes under the presence of solar wind. The third aspect is that the ring current distribution varied along the circumferential path about the spacecraft’s magnetic field. Although this study yielded experimental evidence that differed from the original hypothesis, the three key findings of this study have informed two critical MPS design solutions that will potentially improve thrust performance. The first design solution is the positioning of the plasma injection point. Based on the implication of the first of the three aspects of ring current behavior, the plasma injection point must be located at a distance instead of at close proximity from the MPS Solenoid for the ring current to drift in the direction that will result in magnetosphere inflation. The second design solution, predicated by the third aspect of ring current behavior, is the symmetrical configuration of plasma injection points. In this study, an asymmetrical configuration of plasma injection points using one plasma source resulted in a non-uniform distribution of ring current along the azimuthal path. This distorts the geometry of the inflated magnetosphere which minimizes the deflection area for the solar wind. Therefore, to realize a ring current that best provides the maximum possible inflated magnetosphere, multiple plasma sources must be spaced evenly apart for the plasma to be injected evenly along its azimuthal path.Keywords: Magnetoplasma Sail, magnetosphere inflation, ring current, spacecraft propulsion
Procedia PDF Downloads 30411136 Modelling and Simulating CO2 Electro-Reduction to Formic Acid Using Microfluidic Electrolytic Cells: The Influence of Bi-Sn Catalyst and 1-Ethyl-3-Methyl Imidazolium Tetra-Fluoroborate Electrolyte on Cell Performance
Authors: Akan C. Offong, E. J. Anthony, Vasilije Manovic
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A modified steady-state numerical model is developed for the electrochemical reduction of CO2 to formic acid. The numerical model achieves a CD (current density) (~60 mA/cm2), FE-faradaic efficiency (~98%) and conversion (~80%) for CO2 electro-reduction to formic acid in a microfluidic cell. The model integrates charge and species transport, mass conservation, and momentum with electrochemistry. Specifically, the influences of Bi-Sn based nanoparticle catalyst (on the cathode surface) at different mole fractions and 1-ethyl-3-methyl imidazolium tetra-fluoroborate ([EMIM][BF4]) electrolyte, on CD, FE and CO2 conversion to formic acid is studied. The reaction is carried out at a constant concentration of electrolyte (85% v/v., [EMIM][BF4]). Based on the mass transfer characteristics analysis (concentration contours), mole ratio 0.5:0.5 Bi-Sn catalyst displays the highest CO2 mole consumption in the cathode gas channel. After validating with experimental data (polarisation curves) from literature, extensive simulations reveal performance measure: CD, FE and CO2 conversion. Increasing the negative cathode potential increases the current densities for both formic acid and H2 formations. However, H2 formations are minimal as a result of insufficient hydrogen ions in the ionic liquid electrolyte. Moreover, the limited hydrogen ions have a negative effect on formic acid CD. As CO2 flow rate increases, CD, FE and CO2 conversion increases.Keywords: carbon dioxide, electro-chemical reduction, ionic liquids, microfluidics, modelling
Procedia PDF Downloads 13911135 First-Principles Density Functional Study of Nitrogen-Doped P-Type ZnO
Authors: Abdusalam Gsiea, Ramadan Al-habashi, Mohamed Atumi, Khaled Atmimi
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We present a theoretical investigation on the structural, electronic properties and vibrational mode of nitrogen impurities in ZnO. The atomic structures, formation and transition energies and vibrational modes of (NO3)i interstitial or NO4 substituting on an oxygen site ZnO were computed using ab initio total energy methods. Based on Local density functional theory, our calculations are in agreement with one interpretation of bound-excition photoluminescence for N-doped ZnO. First-principles calculations show that (NO3)i defects interstitial or NO4 substituting on an Oxygen site in ZnO are important suitable impurity for p-type doping in ZnO. However, many experimental efforts have not resulted in reproducible p-type material with N2 and N2O doping. by means of first-principle pseudo-potential calculation we find that the use of NO or NO2 with O gas might help the experimental research to resolve the challenge of achieving p-type ZnO.Keywords: DFF, nitrogen, p-type, ZnO
Procedia PDF Downloads 45611134 Effects of Hydrogen-Ion Irritation on the Microstructure and Hardness of Fe-0.2wt.%V Alloy
Authors: Jing Zhang, Yongqin Chang, Yongwei Wang, Xiaolin Li, Shaoning Jiang, Farong Wan, Yi Long
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Microstructural and hardening changes of Fe-0.2wt.%V alloy and pure Fe irradiated with 100 keV hydrogen ions at room temperature were investigated. It was found that dislocation density varies dramatically after irradiation, ranging from dislocation free to dense areas with tangled and complex dislocation configuration. As the irradiated Fe-0.2wt.%V samples were annealed at 773 K, the irradiation-induced dislocation loops disappear, while many small precipitates with enriched C distribute in the matrix. Some large precipitates with enriched V were also observed. The hardness of Fe-0.2wt.%V alloy and pure Fe increases after irradiation, which ascribes to the formation of dislocation loops in the irradiated specimens. Compared with pure Fe, the size of the irradiation-introduced dislocation loops in Fe-0.2wt.%V alloy decreases and the density increases, the change of the hardness also decreases.Keywords: irradiation, Fe-0.2wt.%V alloy, microstructures, hardness
Procedia PDF Downloads 37811133 Associations between Metabolic Syndrome and Bone Mineral Density and Trabecular Bone Score in Postmenopausal Women with Non-Vertebral Fractures
Authors: Vladyslav Povoroznyuk, Larysa Martynyuk, Iryna Syzonenko, Liliya Martynyuk
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Medical, social, and economic relevance of osteoporosis is caused by reducing quality of life, increasing disability and mortality of the patients as a result of fractures due to the low-energy trauma. This study is aimed to examine the associations of metabolic syndrome components, bone mineral density (BMD) and trabecular bone score (TBS) in menopausal women with non-vertebral fractures. 1161 menopausal women aged 50-79 year-old were examined and divided into three groups: A included 419 women with increased body weight (BMI - 25.0-29.9 kg/m2), B – 442 females with obesity (BMI >29.9 kg/m2)i and C – 300 women with metabolic syndrome (diagnosis according to IDF criteria, 2005). BMD of lumbar spine (L1-L4), femoral neck, total body and forearm was investigated with usage of dual-energy X-ray absorptiometry. The bone quality indexes were measured according to Med-Imaps installation. All analyses were performed using Statistical Package 6.0. BMD of lumbar spine (L1-L4), femoral neck, total body, and ultradistal radius was significant higher in women with obesity and metabolic syndrome compared to the pre-obese ones (p<0.001). TBS was significantly higher in women with increased body weight compared to obese and metabolic syndrome patients. Analysis showed significant positive correlation between waist circumference, triglycerides level and BMD of lumbar spine and femur. Significant negative association between serum HDL level and BMD of investigated sites was established. The TBS (L1-L4) indexes positively correlated with HDL (high-density lipoprotein) level. Despite the fact that BMD indexes were better in women with metabolic syndrome, the frequency of non-vertebral fractures was significantly higher in this group of patients.Keywords: bone mineral density, trabecular bone score, metabolic syndrome, fracture
Procedia PDF Downloads 19911132 Producing and Mechanical Testing of Urea-Formaldehyde Resin Foams Reinforced by Waste Phosphogypsum
Authors: Krasimira Georgieva, Yordan Denev
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Many of thermosetting resins have application only in filled state, reinforced with different mineral fillers. The co-filling of polymers with mineral filler and gases creates a possibility for production of polymer composites materials with low density. This processing leads to forming of new materials – gas-filled plastics (polymer foams). The properties of these materials are determined mainly by the shape and size of internal structural elements (pores). The interactions on the phase boundaries have influence on the materials properties too. In the present work, the gas-filled urea-formaldehyde resins were reinforced by waste phosphogypsum. The waste phosphogypsum (CaSO4.2H2O) is a solid by-product in wet phosphoric acid production processes. The values of the interactions polymer-filler were increased by using two modifying agents: polyvinyl acetate for polymer matrix and sodium metasilicate for filler. Technological methods for gas-filling and recipes of urea-formaldehyde based materials with apparent density 20-120 kg/m3 were developed. The heat conductivity of the samples is between 0.024 and 0.029 W/moK. Tensile analyses were carried out at 10 and 50% deformation and show values 0.01-0.14 MPa and 0.01-0.09 MPa, respectively. The apparent density of obtained materials is between 20 and 92 kg/m3. The changes in the tensile properties and density of these materials according to sodium metasilicate content were studied too. The mechanism of phosphogypsum adsorption modification was studied using methods of FT-IR spectroscopy. The structure of the gas-filled urea-formaldehyde resins was described by results of electron scanning microscopy at three different magnification ratios – x50, x150 and x 500. The aim of present work is to study the possibility of the usage of phosphogypsum as mineral filler for urea-formaldehyde resins and development of a technology for the production of gas-filled reinforced polymer composite materials. The structure and the properties of obtained composite materials are suitable for thermal and sound insulation applications.Keywords: urea formaldehyde resins, gas-filled thermostes, phosphogypsum, mechanical properties
Procedia PDF Downloads 10011131 Density Interaction in Determinate and Indeterminate Faba Bean Types
Authors: M. Abd El Hamid Ezzat
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Two field trials were conducted to study the effect of plant densities i.e., 190, 222, 266, 330 and 440 10³ plants ha⁻¹ on morphological characters, physiological and yield attributes of two faba bean types viz. determinate (FLIP-87 -117 strain) and indeterminate (c.v. Giza-461). The results showed that the indeterminate plants significantly surpassed the determinate plants in plant height at 75 and 90 days from sowing, number of leaves at all growth stages and dry matter accumulation at 45 and 90 days from sowing. Determinate plants possessed greater number of side branches than that of the indeterminate plants, but it was only significant at 90 days from sowing. Greater number of flowers were produced by the indeterminate plants than that of the determinate plants at 75 and 90 days from sowing, and although shedding was obvious in both types, it was greater in the determinate plants as compared with the indeterminate one at 90 days from sowing. Increasing plant density resulted in reductions in number of leaves, branches flowers and dry matter accumulation per plant of both faba bean types. However, plant height criteria took a reversible magnitude. Moreover, under all rates of plant densities the indeterminate type plants surpassed the determinate plants in all growth characters studied except for number of branches per plant at 90 days from sowing. The indeterminate plant leaves significantly contained greater concentrations of photosynthetic pigments i.e., chl. a, b and carotenoids than those found in the determinate plant leaves. Also, the data showed significant reduction in photosynthetic pigments concentration as planting density increases. Light extinction coefficient (K) values reached their maximum level at 60 days from sowing, then it declined sharply at 75 days from sowing. The data showed that the illumination inside the determinate faba bean canopies was better than the indeterminate plants. (K) values tended to increase as planting density increases, meanwhile, significant interactions were reported between faba bean type as planting density on (K) at all growth stages. Both of determinate and indeterminate faba bean plant leaves reached their maximum expansion at 75 days from sowing reflecting the highest LAI values, then their declined in the subsequent growth stage. The indeterminate faba bean plants significantly surpassed the determinate plants in LAI up to 75 days from sowing. Growth analysis showed that NAR, RGR and CGR reached their maximum rates at (60-75 days growth stage). Faba bean types did not differ significantly in NAR at the early growth stage. The indeterminate plants were able to grow faster with significant CGR values than the determinate plants. The indeterminate faba bean plants surpassed the determinate ones in number of seeds/pod and per plant, 100-seed weight, seed yield per plant and per hectare at all rates of plant density. Seed yield increased with increasing plant densities of both types. The highest seed yield was attained for both types 440 103 plants ha⁻¹.Keywords: determinate, indeterminate faba bean, Physiological attributes, yield attributes
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