Dissertations / Theses on the topic 'The current distribution'
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EL-Rashid, Jihad, and Youssef Tawk. "Current Distribution in High RF Power Transistors." Thesis, University of Gävle, Ämnesavdelningen för elektronik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-5735.
Full textTo obtain the power levels required from high RF power transistors, the size of the chip has often to be made so large that inductance of electrical connections inside the package cannot be neglected. This may have the effect that various parts of the transistor chip are not connected exactly parallel, i.e. drain and gate voltages and currents densities will not be the same on different parts of the chip. This may result in degraded output power and efficiency. The same effect may occur when more than one chip are connected in parallel in a transistor package to obtain even higher output power.Often the connections to the transistor package are approximated as a number of electrical point connections (normally three: gate, drain, source); meaning that each of them can be described by a single electrical potential and current. In reality, they may be large enough that voltage and current distributions have to be considered. These distributions will be affected by different mountings of the transistor and other connected components.In this work, the LDMOS power transistor MRF6S21140HR3 was modeled using the segmentation method in high frequency signal simulation HFSS which is a 3D Full-Wave Electromagnetic Field Simulation, and utilized the advanced design system ADS to find a parameterized lumped model. Both the electromagnetic and lumped models showed consistent results. Non-ideal parallel connection of sub-transistors on chip is very important, but further studies are needed for definite conclusion. It was verified through modeling that non ideal parallel connection of different chips in the package does have an effect; the effect however is quiet small which proves that the signal is slightly non-uniformly distributed between the three chips in the package. External connection to PCB (drain connection is considered in this work) can effectively be taken as a point connection to some approximation. The electrical behavior of the modeled transistor was studied through the design of a class B power amplifier in order to estimate the importance of performance degradation due to non-ideal parallel connections and how these non ideal connections degrade efficiency and output power. The modeled transistor can deliver a maximum output power of 147 watts and efficiency of 65%. We have also studied the current distribution between the three chips in a three stage class B power amplifier. Again, the difference in the current distribution between the three chips turned out to be quiet small. All these results are presented through this work. The final conclusion regarding the current distribution between multichips cannot be made just based on these simulation results. The next step should be aimed at considering other effects, the thermal effect for example, in order to know exactly whether it is uniformly or not uniformly distributed.
Smith, Daniel Allen. "Current distribution at varing frequencies in hybrid /." Connect to online version at Digital.Maag, 1999. http://hdl.handle.net/1989/4789.
Full textFerri, Matthew A. (Matthew Anthony). "Current distribution in cable-in conduit superconductors." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/28111.
Full textIncludes bibliographical references (p. 101-103).
by Matthew A. Ferri.
M.S.
Johnston, Martin David. "Current and field distribution in high temperature superconductors." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298870.
Full textWei, Xingguo. "Current distribution materials for solid oxide fuel cells." Thesis, Imperial College London, 2004. http://hdl.handle.net/10044/1/11527.
Full textGokgoz, Sinan. "A Stand-alone Induction Powered Current And Current Harmonics Measurement System For Distribution Lines." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614967/index.pdf.
Full textTidd, Chad N. "Hardware model of a shipboard Zonal Electrical Distribution System (ZEDS) Alternating Current/Direct Current (AC/DC)." Thesis, Cambridge Massachusetts Institute of Technolog, 2010. http://hdl.handle.net/10945/4936.
Full textApproved for public release; distribution is unlimited
A hardware model of a shipboard electrical distribution system based on aspects of the DDG 51 Flight IIA, Arleigh Burke class, 60Hz Alternating Current (AC) and the future direct current (DC), zonal electrical distribution system (ZEDS). These distribution boards were designed and built for the purpose of testing electrical system components at the Massachusetts Institute of Technology's Laboratory for Electromagnetic and Electronic Systems (LEES). Two 5 kW generators serve as electrical generation for the ZEDS benchtop emulator boards. The hardware models support experimentation with AC and DC ZEDS power loading and protection. The hardware models reflect the AC ZEDS architecture employed on the DDG-51 class destroyers. The emulator is a three phase electrical system with both port and starboard buses, a computer interface to control the generators and contactors or solid state relays through a graphic user interface (GUI). The system is capable of being configured and operated in a split plant, parallel or single generator plant configuration.
Tidd, Chad N. (Chad Norman). "Hardware model of a shipboard zonal electrical distribution system (ZEDS) : alternating current/direct current (AC/DC)." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61908.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 91-92).
A hardware model of a shipboard electrical distribution system based on aspects of the DDG 51 Flight IIA, Arleigh Burke class, 60Hz Alternating Current (AC) and the future direct current (DC), zonal electrical distribution system (ZEDS). These distribution boards were designed and built for the purpose of testing electrical system components at the Massachusetts Institute of Technology's Laboratory for Electromagnetic and Electronic Systems (LEES). The combination of existing electrical generators and the newly created electrical distribution boards will provide a hereto unattained level of access for testing and evaluating a number of research topics currently being worked on at LEES. The level of reality inherent in this system will enable the user to refine experimental hardware and software in a safe and controlled environment. The user will benefit from a quicker product development process. Additionally, the ability to easily produce verifiable records to demonstrate the effectiveness/applicability of their individual experiments will help to progress research at LEES along the product development path. Two 5 kW generators serve as electrical generation for the ZEDS benchtop emulator boards. The hardware models support experimentation with AC and DC ZEDS power loading and protection. The hardware models reflect the AC ZEDS architecture employed on the DDG-51 class destroyers. The emulator is a three phase electrical system with both port and starboard buses, a computer interface to control the generators and contactors or solid state relays through a graphic user interface (GUI). The system is capable of being configured and operated in a split plant, parallel or single generator plant configuration.
by Chad N. Tidd.
S.M.in Engineering and Management
Nav.E.
Byrne, Philip. "Mathematical modelling and experimental simulation of chlorate and chlor-alkali cells." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3182.
Full textAjitkumar, Rohit. "An analysis of DC distribution systems." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39590.
Full textHofmann, Markus Hans [Verfasser]. "Current distribution in parallel-connected battery cells / Markus Hans Hofmann." München : Verlag Dr. Hut, 2020. http://d-nb.info/1222353199/34.
Full textMahmood, Humam S. "Modelling tertiary current distribution in electrodeposition cells with flowing electrolytes." Thesis, London South Bank University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618650.
Full textHellal, Abdelhafid. "An analytical study of back-to-back HVDC link in weak AC systems /." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65466.
Full textMoraes, Edison Pires de. "Distribuição de corrente entre semicondutores em retificadores de alta corrente - estudo de casos reais." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-29012009-114411/.
Full textThe industrial electrolytic processes to produce, aluminum, cooper, zinc, nickel, manganese, silicon carbide, chlorine and its derivative, require current values which greatly exceed the capability of single rectifying devices and paralleled combinations of semiconductors or equipments are necessary. This study evaluated through a comparative analyzes twenty rectifiers, with different busbar geometries, in order to verify the current distribution in paralleled devices. The differential of this study is the simultaneous measurement of currents in all semiconductors of each branch in order to obtain a real representation of the rectifiers current distribution.
Tsemekhman, Kiril. "Current distribution and density of states in the quantum hall effect /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/9737.
Full textTsemekhman, Vadim. "Charge relaxation, current distribution, and breakdown of the quantum Hall effect /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/9739.
Full textProctor-Williams, Kerry. "Dosage and Distribution in Morphosyntax Intervention: Current Evidence and Future Needs." Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etsu-works/1773.
Full textOmar, Kaashif A. M. "Electromagnetic flyer plate technology and development of a novel current distribution sensor." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/17740.
Full textLalander, Emilia, Mårten Grabbe, and Mats Leijon. "On the velocity distribution for hydro-kinetic energy conversion from tidal currents and rivers." Uppsala universitet, Elektricitetslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-195499.
Full textPerrot, Fabrice. "The effects of multi-current impulses on the low current bulk distribution in varistor materials, under continuous AC operation." Thesis, University of Brighton, 1995. https://research.brighton.ac.uk/en/studentTheses/0c2ff4b0-630d-41b1-8241-658d582ac6d5.
Full textIsik, Mehmet. "Thermally Stimulated Current Study Of Traps Distribution In Beta-tlins2 Layered Crystals." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609667/index.pdf.
Full textNasser, Hisham. "Thermally Stimulated Current Study Of Traps Distribution In Tlgases Layered Single Crystals." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611866/index.pdf.
Full text160 K with various heating rates between 0.6&ndash
1.2 K/s. Experimental evidence has been found for the presence of three electrons trapping centres with activation energies 12, 20, and 49 meV and one hole trapping centre located at 12 meV. Their capture cross-sections and concentrations were also determined. It is concluded that in these centres retrapping is negligible as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping. The optical properties of TlGaSeS layered single crystals have been investigated by measuring the transmission and the reflection in the wavelength region between 400 and 1100 nm. The optical indirect transitions with a band gap energy of 2.27 eV and direct transitions with a band gap energy of 2.58 eV were found by analyzing the absorption data at room temperature. The rate of change v of the indirect band gap with temperature was determined from the transmission measurements in the temperature range of 10&ndash
300 K. The oscillator and the dispersion energies, the oscillator strength, and the zero-frequency refractive index were also reported. The parameters of monoclinic unit cell and the chemical composition of TlGaSes crystals were found by X-ray powder diffraction and energy dispersive spectroscopic analysis, respectively.
Wurjantara, Wisnu. "Computation of current distribution in long elliptic conductors using Mathieu functions expansion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq28693.pdf.
Full textKing, Andrew Luke. "Iron distribution and phytoplankton iron limitation in the southern California Current System." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3306532.
Full textTitle from first page of PDF file (viewed June 16, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
Zainal, Abidin Ilham Mukriz. "Modelling and experimental investigation of eddy current distribution for angular defect characterisation." Thesis, University of Newcastle Upon Tyne, 2011. http://hdl.handle.net/10443/1308.
Full textPotter, Marcus Jason. "Parametric analysis of a solid polymer fuel cell using current distribution mapping." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/19470.
Full textFerri, Matthew A. (Matthew Anthony). "Current distribution and stability criteria for superconducting cables in transient magnetic fields." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10406.
Full textMotloung, Rethabile Frangenie. "Understanding current and potential distribution of Australian acacia species in southern Africa." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/79720.
Full textDissertation (MSc)--University of Pretoria, 2014.
National Research Foundation (NRF)
Zoology and Entomology
MSc (Zoology)
Unrestricted
Mushagala, Jimmy Matabaro. "Harmonic analysis and effectiveness of mitigation techniques applied to a bipolar HVDC system." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2461.
Full textHigh Voltage Direct Current (HVDC) transmission is a safe and efficient technology designed to deliver large amounts of electrical power over long distances with minimal losses and at low costs. HVDC links require converters and filters at both terminal stations. The core component of the HVDC system is the power converter that connects the DC and AC systems together. The conversion from AC to DC, and vice versa, is achieved mainly through electronic switches called thyristors. The thyristor-based Line Commutated Converter (LCC) is a mature and trusted technology for HVDC transmission throughout the world. HVDC converters are bidirectional and can function in either rectification (AC to DC) or inversion mode (DC to AC). This is achieved when the voltage polarity across the converter gets swapped by the controllers, because current cannot change its direction in thyristors. In this thesis an analytical model of the HVDC converters is developed in the frequency domain by modelling it in DIgSILENT. The objective is to study the harmonics induced to the AC side from HVDC converters. Therefore, it is important in the real world to understand the principles, what causes harmonics to be generated in HVDC and transferred to the HVAC system. The objective of this thesis is to investigate the effectiveness of mitigation techniques used, on how they reduce harmonics by keeping these harmonic levels within specified values admissible by international standards (e.g. IEEE, etc).
Fonseca, Marco Filipe Matos da. "Integrating wind generation in the distribution network." Master's thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/8187.
Full textOne of the current challenges the electricity grid has is to actively connect future generation to its network without the need to fully reinforce it. This dissertation will study the use of dynamic ratings on overhead lines to increase its capacity and thus defer major investment on infrastructure reinforcement. The amount of current an overhead line can withstand in a given time is defined by the distance towards the ground, which is proportional to the conductor´s temperature, which is given by a static rating stated in the P27 standard – “Current Rating Guide for High Voltage Overhead Lines Operating in the UK Distribution System”. This rating changes from season to season and depends on specific values for ambient temperature, wind speed, wind direction and the probability that in a year the conductor exceeds its design temperature. This standard is seen as being very restrictive and a limiting factor on overhead line capacity for both future generation connections and demand. Wind speed and direction are extremely important on the cooling of overhead lines and in times of strong winds the conductor cools down, allowing extra amount of current to flow through it. By using real time weather data, it´s possible to obtain the maximum current that can flow in an overhead line for a specific operating temperature and assess the amount of headroom possible given by the difference between the static ratings and the new dynamic ratings is assessed. A view on the extra amount of energy produced, as well as CO2 emission savings and profit will also be presented, giving a practical result by applying dynamic ratings.
Hölling, Matthias. "Adaptive current and voltage measurement device for low voltage distribution in power nets /." [S.l.] : [s.n.], 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13985.
Full textOlesen, Ole Berdiin. "Smarter Fault Localization in Distribution Systems : A Self-Sustained Sensor for Current Measurement." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-27227.
Full textWang, Hongjie. "Design and Control of Series Resonant Converters for DC Current Power Distribution Applications." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7160.
Full textPillar, Stanley C. "Distribution and population dynamics of Euphausia lucens (Euphausiacea) in the southern Benguela current." Doctoral thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/8406.
Full textThe thesis first reviews the research on zooplankton ecology in the Benguela system and then evaluates the contribution of euphausiids to the zooplankton biomass of the southern Benguela region. The study further investigates the population dynamics and maintenance of the dominant euphausiid, Euphausia lucens, principally in the St Helena Bay region because of its importance as a recruitment area for the pelagic fishery.
Hall, David Eric. "Transient thermal models for overhead current-carrying hardware." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/17133.
Full textHigier, Andrew Michael. "An In-Situ and Ex-Situ Investigation of Current Density Variations in a Proton Exchange Membrane Fuel Cell." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/373.
Full textCrego, Ramiro Daniel. "Modeling the distribution of meadows in arid and semi-arid Patagonia, Argentina: assessing current distribution and predicting response to climate change." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/1001.
Full textZhang, Lu. "Development of LCL DC/DC transformer and fault current limiting LCL VSC converter for high power DC networks." Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=211240.
Full textAntaloae, C. C. "Feasibility of high frequency alternating current power distribution for the automobile auxiliary electrical system." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/6792.
Full textVestgöte, Karl. "Quantum Key Distribution - current state of the technology and prospects in the near future." Thesis, Linköping University, Department of Electrical Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17579.
Full textThe thesis presents the basics of Quantum Key Distribution, a survey of the present techniques, a look at the possible future, and finally a comparison to the alternative technique of using public key or manual distribution of keys.
Techniques to integrate QKD with the existing telecom fiber infrastructure have been studied, and so has the EU-funded project SECOQC.
Last the security and efficiency of QKD have been examined, with focus on what level of security that is required, existing security solutions have been used as a comparison.
Mehra, Arun 1967. "An approximate method for determining the frequency dependent current distribution in a ground plane." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278176.
Full textBehlman, Nicholas James. "Electron Energy Distribution Measurements in the Plume Region of a Low Current Hollow Cathode." Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-theses/72.
Full textMokhlesi, Javad, and Saman Lohrasebi. "The Current State and Future Trends in The Use of Pallets in Distribution Systems." Thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-19689.
Full textBotes, Lizeth. "Taxonomy, distribution and toxicity of dinoflagellate species in the southern Benguela current, South Africa." Doctoral thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/6236.
Full textThe threat of harmful algal blooms with their attendant problems, exists throughout the Benguela region. In the southern Benguela upwelling system, water discolorations, referred to as 'red tides', are common and usually attributed to dinoflagellate species. The first aim of the thesis was to investigate the taxonomy of gymnodinioid species in the southern Benguela current. In order to investigate the morphology of the southern Benguela isolates, a simple and rapid scanning electron microscope preparative technique was developed. In the course of these studies, a new genus and new species were identified and described.
Verma, Manish. "A comprehensive overview, behavioral model and simulation of a Fault Current Limiter." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/33841.
Full textMaster of Science
Pokrovskiy, S., I. Rudnev, A. Podlivaev, and M. Osipov. "Method and Experimental Setup for the Study of the Local Current Distribution in Conducting Micro-and Nanostructures." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35220.
Full textVerdin, Baptiste. "Etude d'électrodes grande surface d'électrolyseurs PEM : inhomogénéités de fonctionnement et intégration de catalyseurs innovants." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS036/document.
Full textHydrogen production from PEM water electrolysis will take a great place in the energy landscape for RES storage. This scale shift requires a significant increase of the nominal power, and therefore an increase in size and a gain in the current density. Optimal operation (in terms of efficiency and lifetime) can be obtained only if the distribution of current lines over the electrode surface is adequately homogeneous. In this thesis, we have used for the first time a specific tool for the in-situ mapping of current and temperature in a large surface area PEM single cell. A customized S++® measuring plate, adapted to our application, has been implemented in a 250cm² PEM single cell. Electromechanical characterization of the cell has put into evidence the link between the field of clamping force and the local current density. We have shown that an optimal mechanical compression is not sufficient to homogenize current distribution. We have demonstrated that the cell design, in particular the fluid distribution, plays a major role in current distribution inhomogeneities, which recurrently form between the center and the periphery of the cell. We have also shown that during dynamic operation, current lines tend to concentrate at the center of the cell as a consequence of spatially differentiated ageing. We have developed an electrode structure that facilitates the global re-homogenization of current lines and additionally shows an increased durability. In parallel, we have developed a numerical model to calculate the distribution of current lines within the thickness of catalytic layers as a function of the geometry of the PTL. We have found that overvoltages play a major role in current distribution, and that the cathode is prone to more heterogeneities. We propose to densify the catalyst layers for a better current repartition and a lesser differentiated ageing. Key findings from single cell tests have been confirmed on a commercial stack
Blasi, Bronson Richard. "DC microgrids: review and applications." Kansas State University, 2013. http://hdl.handle.net/2097/16823.
Full textDepartment of Architectural Engineering and Construction Science
Fred Hasler
This paper discusses a brief history of electricity, specifically alternating current (AC) and direct current (DC), and how the current standard of AC distribution has been reached. DC power was first produced in 1800, but the shift to AC occurred in the 1880’s with the advent of the transformer. Because the decisions for distribution were made over 100 years ago, it could be time to rethink the standards of power distribution. Compared to traditional AC distribution, DC microgrids are significantly more energy efficient when implemented with distributed generation. Distributed generation, or on-site generation from photovoltaic panels, wind turbines, fuel cells, or microturbines, is more efficient when the power is transmitted by DC. DC generation, paired with the growing DC load profile, increases energy savings by utilizing DC architecture and eliminating wasteful conversions. Energy savings would result from a lower grid strain and more efficient utilization of the utility grid. DC distribution results in a more reliable electrical service due to short transmission distances, high service reliability when paired with on-site generation, and efficient storage. Occupant safety is a perceived concern with DC microgrids due to the lack of knowledge and familiarity in regards to these systems. However, with proper regulation and design standards, building occupants never encounter voltage higher than 24VDC, which is significantly safer than existing 120VAC in the United States. DC Microgrids have several disadvantages such as higher initial cost due, in part, to unfamiliarity of the system as well as a general lack of code recognition and efficiency metric recognition leading to difficult certification and code compliance. Case studies are cited in this paper to demonstrate energy reduction possibilities due to the lack of modeling ability in current energy analysis programs and demonstrated energy savings of approximately 20%. It was concluded that continued advancement in code development will come from pressure to increase energy efficiency. This pressure, paired with the standardization of a 24VDC plug and socket, will cause substantial increases in DC microgrid usage in the next 10 years.
Yu, Jianghui. "DC Fault Current Analysis and Control for Modular Multilevel Converters." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/78054.
Full textMaster of Science
Monzon, Jorge Emilio. "Current density distribution versus frequency and current for metal electrodes." 1986. http://catalog.hathitrust.org/api/volumes/oclc/14923364.html.
Full textTypescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 11-13).