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Dissertations / Theses on the topic 'Electrical source analysis'
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Gursoy, Ekrem Niebur Dagmar. "Independent component analysis for harmonic source identification in electric power systems /." Philadelphia, Pa. : Drexel University, 2007. http://hdl.handle.net/1860/1781.
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Homer, Hannah S. "Stability Analysis of Negative Resistance-Based Source Combining Power Amplifiers." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1466.
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An investigation into the stability of negative resistance-based source combining power amplifiers is conducted in this thesis. Two different negative resistance-based source combining topologies, a series and parallel version, are considered. Stability is analyzed using a simple and intuitive broadband approach that leverages linear circuit stability criterion and two different linearization methods: linearization around the operating point and in the frequency domain. Using this strategy, it is shown that conditions for self-sustained oscillation exist for both topologies. For the series combining topology, self-sustained oscillation is prevented by means of injection locking.
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Shah, Shahil. "Small and Large Signal Impedance Modeling for Stability Analysis of Grid-connected Voltage Source Converters." Thesis, Rensselaer Polytechnic Institute, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10786614.
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Interactions between grid-connected converters and the networks at their terminals have resulted in stability and resonance problems in converter-based power systems, particularly in applications ranging from wind and PV farms to electric traction and HVDC transmission networks. Impedance-based modeling and analysis methods have found wide acceptance for the evaluation of these resonance problems.
This thesis presents small and large signal impedance modeling of grid-connected single and three phase voltage source converters (VSC) to enable the analysis of resonance conditions involving multiple frequency components, and both the ac and dc power systems at the VSC terminals. A modular impedance modeling approach is proposed by defining the VSC impedance as transfer matrix, which captures the frequency cross-coupling effects and also the coupling between the ac and dc power systems interfaced by the VSC. Ac and dc impedance models are developed for a VSC including the reflection of the network on the other side of the VSC. Signal-flow graphs for linear time-periodic (LTP) systems are proposed to streamline and visually describe the linearization of grid-connected converters including the frequency cross-coupling effects. Relationships between the impedance modeling in dq, sequence, and phasor domains are also developed. The phasor-domain impedance formulation links the impedance methods with the phasor-based state-space modeling approach generally used for bulk power systems. A large-signal impedance based method is developed for predicting the amplitude or severity of resonance under different grid conditions. The small-signal harmonic linearization method is extended for the large-signal impedance modeling of grid-connected converters. It is shown that the large-signal impedance of a converter is predominantly shaped by hard nonlinearities in the converter control system such as PWM saturation and limiters.
This thesis also deals with the problem of synchronizing a generator or microgrid with another power system. A VSC-based synchronizer is proposed for active phase synchronization and a distributed synchronization method is developed for microgrids.
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Renjit, Ajit Anbiah. "MODELING, ANALYSIS AND CONTROL OF MIXED SOURCE MICROGRID." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1450770774.
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Xu, Ling. "Modeling, Analysis and Control of Voltage-Source Converter in Microgrids and HVDC." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4967.
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The objective of this dissertation is to carry out dynamic modeling, analysis and control for Voltage-Source Converters (VSC). Two major applications of VSC will be investigated in this dissertation: microgrid application and High Voltage Direct Current (HVDC) application.
In microgrid applications, VSC is used to integrate distributed energy sources such as battery and provide system functions: such as real and reactive power regulation, voltage and frequency support during islanding condition, and abnormal system condition mitigation. In HVDC applications, VSC is used to interconnect dc systems with ac systems. The functions supplied by VSC are similar to that in microgrids. However, the transfer capability and stability in such kind of system are of major interests.
Therefore, Part I of this dissertation focuses on VSC's applications in microgrids. A battery's inverter can be operated in both grid-connected PQ regulation mode and voltage and frequency support mode during islanding condition. Transition scheme between these two control modes is firstly investigated to guarantee a smooth dynamic performance. Secondly, a coordinated control strategy between battery's and PV station's VSCs is developed to improve microgrid's power flow. Thirdly, power quality improvement through the battery's inverter is investigated. VSC's control and capability for microgrid operation at normal, transient, and abnormal conditions will be modeled and analyzed.
Part II of this dissertation focuses on VSC's applications in HVDC. The following topics are investigated in this dissertation: (i) how to design VSC-HVDC's controller using system identification method? (ii) How to coordinate VSCs in multi-terminal HVDC scenarios? And (iii) how to determine VSC-HVDC system's transfer capability based on stability limits? High-fidelity simulation technology is employed to tackle control validation while frequency domain impedance modeling technique is employed to develop analytical models for the systems. With linear system analysis tools such as Nyquist plots and Bode plots, stability limits and impacting factors of VSC-HVDC systems can be identified.
This dissertation led to four journal papers (two accepted, one request of revision, one to submit) and five conference papers. The major contributions of this dissertation include:
1) Developed VSC and microgrid models in high-fidelity simulation environment. Developed and validated VSC control schemes for variety of microgrid operations: normal, abnormal, and transient. The developed technologies can facilitate a battery to make up solar power, improve system dynamic performance during transients, and improve power quality.
2) Developed VSC-HVDC simulation models, including two-terminal HVDC and multi-terminal HVDC. Developed VSC-HVDC control schemes for two-terminal and multi-terminal systems. Developed analytical impedance models for VSC-HVDC systems and successfully carried out stability limit identification.
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Kathi, Lokesh. "Steady-State Analysis of PWM Z-Bridge Source DC-DC Converter." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1453223069.
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Ho, Benjamin 1978. "The portability of open source : b a structural analysis of the modularity of the Apache web server." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86463.
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Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (leaf 44).
by Benjamin Ho.
S.B.and M.Eng.
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Nalavolu, Praveen Reddy. "PERFORMANCE ANALYSIS OF SRCP IMAGE BASED SOUND SOURCE DETECTION ALGORITHMS." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/50.
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Steered Response Power based algorithms are widely used for finding sound source location using microphone array systems. SRCP-PHAT is one such algorithm that has a robust performance under noisy and reverberant conditions. The algorithm creates a likelihood function over the field of view. This thesis employs image processing methods on SRCP-PHAT images, to exploit the difference in power levels and pixel patterns to discriminate between sound source and background pixels. Hough Transform based ellipse detection is used to identify the sound source locations by finding the centers of elliptical edge pixel regions typical of source patterns. Monte Carlo simulations of an eight microphone perimeter array with single and multiple sound sources are used to simulate the test environment and area under receiver operating characteristic (ROCA) curve is used to analyze the algorithm performance. Performance was compared to a simpler algorithm involving Canny edge detection and image averaging and an algorithms based simply on the magnitude of local maxima in the SRCP image. Analysis shows that Canny edge detection based method performed better in the presence of coherent noise sources.
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Resch, Kevin (Kevin Scott). "An analysis of incentive strategies for single-source suppliers to drive cost reduction." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/66053.
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Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science; in conjunction with the Leaders for Global Operations Program at MIT, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 54-55).
An organization's decision on which aspects of its operations to outsource represents a key, strategic issue that should be based on maximizing performance throughout the entire value chain. In certain instances strategic outsourcing decisions make it ideal for firms to source from one particular supplier. Singlesource relationships, in particular, necessitate strategic contract development to ensure incentives are aligned throughout the value chain. Much of the existing research in contract development focuses on mitigating fluctuations in demand. Forecasting demand is highly uncertain and can lead to inefficiencies throughout the value chain that contracts can alleviate. However, the defense industry typically has low uncertainty in demand, which offers a unique environment to study contract development. This thesis focuses on contract development with certain demand through case studies in the defense industry. The essence of this thesis revolves around a strategic framework for developing contracts. This framework begins with a discussion of methods for performing a strategic analysis of suppliers. Next an overview of investigating supplier alternatives is provided. The framework then addresses the execution of a contract, which includes writing and negotiating the contract. Finally, contract maintenance is discussed, which includes contract validation as well as managing latent concerns. After the framework is laid out, four different single-source supplier relationships are analyzed. Each of these supplier relationships is investigated to understand the motivation for initiating these particular relationships. The four supplier case studies revolve around the issues of supplier investment costs, internal competition, commodity negotiations, and supplier power. After each case study, the pertinent aspects of the contract development framework are applied to the specific supplier relationship and conclusions are drawn.
by Kevin Resch.
S.M.
M.B.A.
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Namburi, Krishna Mohan Pavan Kumar. "A Novel Dithering Algorithm to Reduce Electro Magnetic Interference in Voltage Source Inverters." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1342106230.
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Alskran, Faleh A. "Dynamic modeling and analysis of the three-phase voltage source inverter under stand-alone and grid-tied modes." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18220.
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Master of ScienceDepartment of Electrical and Computer Engineering
Behrooz Mirafzal
Increasing energy demand, rising oil prices, and environmental concerns have forced attention to alternative energy sources that are environmentally friendly and independent of fossil fuels. Renewable energy sources (RES) have become an attractive alternative to the traditional energy sources for electric power generation. However, one of the main challenges of RES adaption arises when connecting RES to the electric grid. Voltage source inverters (VSIs), typically, connect RES to the electric grid. Similar to any engineering system, detailed dynamic models of the VSIs are needed for design and analysis purposes. However, due to the non-linearity of VSIs, development of dynamic models that can accurately describe their behavior is a complex task. In this thesis, a detailed averaged-state-space model of the two-level three-phase space vector pulse width modulation VSI and its companion LCL filter is derived. Because VSIs can operate under stand-alone and grid-tied modes, two models were derived for each case. In the derived models, the VSI modulation index m and phase angle ϕ are initially considered constant. In practice, however, these parameters are considered the main control parameters. To model these parameters as control inputs, small-signal models of the VSI under stand-alone and grid-tied modes were derived. To verify the accuracy of the developed large-signal and small-signal models, Matlab/Simulink simulations were carried out. The simulation results were compared against the models results. Moreover, the models were verified through lab experiments. The developed models can be used as design and analysis tools. In addition, the developed models can be used as fast and efficient simulation tools for system studies, when the modeling of switching transients is not needed. Nowadays, the number of VSIs connected to the electric grid is growing exponentially. The amount of time and computation needed to simulate VSIs using simulation software packages can be significantly decreased by the use of the developed models.
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Diab, Ahmad. "Study of the nonlinear properties and propagation characteristics of the uterine electrical activity during pregnancy and labor." Thesis, Compiègne, 2014. http://www.theses.fr/2014COMP2140/document.
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L'EMG utérin appelé Electrohystérogramme (EHG) a été exploité depuis longtemps par ses caractéristiques temporelles, fréquentielles, et temps-fréquence, pour la prédiction de l'accouchement prématuré, tandis que l'étude de sa propagation est rare. Tous les résultats des études antérieures n'ont pas montré un potentiel satisfaisant pour une application clinique. L'objectif de cette thèse est l'analyse de la propagation ainsi que de la non-linéarité des signaux EHG pendant la grossesse et le travail en vue d'une application clinique. Une analyse monovariée a été faite pour étudier la non-linéarité et la sensibilité des méthodes aux différentes caractéristiques des signaux. Une analyse bivariée a ensuite été menée pour l‟étude de la propagation de l‟EHG, en mesurant le couplage entre les voies ainsi que la direction de couplage, ce qui est une nouveauté de notre thèse. Dans cette analyse, nous proposons une approche de filtrage-fenêtrage pour améliorer les méthodes d'estimation du couplage et de sa direction. Une autre nouveauté de cette thèse est l'implantation d'un outil de localisation de source d'EHG pour étudier la dynamique de l'utérus au niveau de la source, et non pas au niveau des électrodes comme fait dans les études précédentes. Les résultats montrent que les méthodes non linéaires sont plus capables que les méthodes linéaires, de classifier les contractions de grossesse et de travail. La méthode de réversibilité de temps est la moins sensible à la fréquence d'échantillonnage et au contenu fréquentiel du signal. Les résultats indiquent également une augmentation de couplage et une concentration des directions vers le col de l‟utérus, en allant de la grossesse vers le travail. En respectant la non-stationnarité des signaux EHG et en se libérant de l'effet de filtrage de la graisse, très variable durant la grossesse et entre les différentes femmes, notre méthode de filtrage-fenêtrage (segmentation et filtrage du signal EHG pour ne garder que la composant FWL), améliore les performances des méthodes de connectivité. L'intensité des sources localisées et leur nombre sont plus élevés durant le travail que durant la grossesse. Les sources localisées sont actives et propagées durant le travail alors que durant la grossesse elles restent faibles et localisées. Une amélioration de la matrice d'électrodes du protocole expérimental de rat a été effectuée par le développement d'une électrode à succion. Ce protocole pourra ensuite être utilisé pour la validation de nos méthodes et celle du modèle électrophysiologiqueThe uterine EMG -called Electrohysterogramme (EHG)- temporal, frequency, and time-frequency characteristics have been used for a long time for the prediction of preterm labor. However, the investigation of its propagation is rare. All the results of the previous studies did not show a satisfactory potential for clinical application. The objective of this thesis is the analysis of the propagation as well as of the nonlinear characteristics of EHG signals during pregnancy and labor for clinical application. A monovariate analysis was done to investigate the nonlinearity and the sensibility of methods to different characteristics of the signals. A bivariate analysis was then done for the investigation of the propagation of EHG by measuring the coupling between channels, as well as the direction of coupling, which is an innovative part of our thesis. In this analysis we propose a new approach to improve the coupling and direction estimation methods. Another innovation of this thesis is the implementation of a tool for EHG source localization to investigate the dynamic of the uterus at the source level, not at electrodes level as previously done. Results show that nonlinear methods are more able to classify pregnancy and labor contractions than linear ones, and that time reversibility method is the least sensitive to sampling frequency and frequency content of the signal. Results also indicate an increase in coupling and a concentration of coupling direction toward the cervix when going from pregnancy to labor. We also proposed to respect the nonstationarity of EHG signal and to recover the effect of variable fat filtering along pregnancy, by segmenting and filtering the EHG in its FWL component. This filtering-windowing approach permits to improve the performances of connectivity methods. Finally, the intensity of localized sources and their number is higher in labor than in pregnancy contractions. The identified sources are more active and more propagated in labor whereas in pregnancy they remain weak and local. An improvement in the electrode matrix of the rat experimental protocol has also been done by developing a suction electrode. This protocol can then be used for the validation of our methods and of the electrophysiological model
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Ruan, Wenbo. "Energy survey on replacing a direct electrical heating system with an alternative heating system." Thesis, Högskolan i Gävle, Energisystem, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-26915.
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With the ever-growing energy demand that world is currently going through and the danger of climate change around the corner, wagering in renewable energy seems to be the right path to create a more smart and green future. Sweden has put great effort on decreasing its dependency on oil, in fact in 2012 more than 50 % of its electricity came from the renewable source and has a plan in making it 100 % in 2040. However, when it comes to heating systems Sweden depends greatly on district heating, and situations which buildings are located outside the district heating system’s reach is not uncommon, hence for those buildings, other options such as solar power or heat pumps are considered. Many buildings located in Skutskär suffer from the problem stated above. The particular building analyzed in this thesis uses electrical radiator and furnace as sources of heat, which implies high energy uses and financial expenses. For this reason technical and financial analysis of using each alternative system for a single family house located in Skutskär had been done. Using solar powered system is deemed to be quite ineffective, as Sweden has poor solar radiation. In order to compensate the poor sun hours during the winter, 51 photovoltaic (PV) panels or 19 solar thermal panels would be required. This high initial investment needs long period of time in order to be profitable, 15 years for solar thermal system and 21 years for solar PV system. On the other hand, the results from the heat pumps are quite satisfactory, the fastest payback period is around 4 years. This is achieved by using air source heat pump (ASHP), the annual saving in this case is three times higher than using solar photovoltaic panels, making the usage of ASHP more attractive than any solar energy system. However, when annual saving is concerned, the ground source heat pump (GSHP) system is capable of generating even higher saving, but the initial investment is significantly higher, extending the payback period to 6 years.
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Kim, Youngchel. "On a Uniform Geometrical Theory of Diffraction based Complex Source Beam Diffraction by a Curved Wedge with Applications to Reflector Antenna Analysis." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1249419187.
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Vadali, Venkata Akshay Bhargav Krishna. "A Comparative Study of Signal Processing Methods for Fetal Phonocardiography Analysis." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7373.
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More than one million fetal deaths occur in the United States every year [1]. Monitoring the long-term heart rate variability provides a great amount of information about the fetal health condition which requires continuous monitoring of the fetal heart rate. All the existing technologies have either complex instrumentation or need a trained professional at all times or both. The existing technologies are proven to be impractical for continuous monitoring [2]. Hence, there is an increased interest towards noninvasive, continuous monitoring, and less expensive technologies like fetal phonocardiography.
Fetal Phonocardiography (FPCG) signal is obtained by placing an acoustic transducer on the abdomen of the mother. FPCG is rich in physiological bio-signals and can continuously monitor the fetal heart rate non-invasively. Despite its high diagnostic potential, it is still not being used as the secondary point of care. There are two challenges as to why it is still being considered as the secondary point of care; in the data acquisition system and the signal processing methodologies. The challenges pertaining to data acquisition systems are but not limited to sensor placement, maternal obesity and multiple heart rates. While, the challenges in the signal processing methodologies are dynamic nature of FPCG signal, multiple known and unknown signal components and SNR of the signal.
Hence, to improve the FPCG based care, challenges in FPCG signal processing methodologies have been addressed in this study. A comparative evaluation was presented on various advanced signal processing techniques to extract the bio-signals with fidelity. Advanced signal processing approaches, namely empirical mode decomposition, spectral subtraction, wavelet decomposition and adaptive filtering were used to extract the vital bio-signals. However, extracting these bio-signals with fidelity is a challenging task in the context of FPCG as all the bio signals and the unwanted artifacts overlap in both time and frequency. Additionally, the signal is corrupted by noise induced from the fetal and maternal movements as well the background and the sensor.
Empirical mode decomposition algorithm was efficient to denoise and extract the maternal and fetal heart sounds in a single step. Whereas, spectral subtraction was used to denoise the signal which was later subjected to wavelet decomposition to extract the signal of interest. On the other hand, adaptive filtering was used to estimate the fetal heart sound from a noisy FPCG where maternal heart sound was the reference input.
The extracted signals were validated by obtaining the frequency ranges computed by the Short Time Fourier Transform (STFT). It was observed that the bandwidths of extracted fetal heart sounds and maternal heart sounds were consistent with the existing gold standards. Furthermore, as a means of additional validation, the heart rates were calculated. Finally, the results obtained from all these methods were compared and contrasted qualitatively and quantitatively.
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MUBEEN, SAAD. "EVALUATION OF SOURCE ROUTING FOR MESH TOPOLOGY NETWORK ON CHIP PLATFORMS." Thesis, Jönköping University, JTH, Computer and Electrical Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-9591.
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Network on Chip is a scalable and flexible communication infrastructure for the design of core based System on Chip. Communication performance of a NoC depends heavily on the routing algorithm. Deterministic and adaptive distributed routing algorithms have been advocated in all the current NoC architectural proposals. In this thesis we make a case for the use of source routing for NoCs, especially for regular topologies like mesh. The advantages of source routing include in-order packet delivery; faster and simpler router design; and possibility of mixing non-minimal paths in a mainly minimal routing. We propose a method to compute paths for various communications in such a way that traffic congestion is avoided while ensuring deadlock free routing. We also propose an efficient scheme to encode the paths.
We developed a tool in Matlab that computes paths for source routing for both general and application specific communications. Depending upon the type of traffic, this tool computes paths for source routing by selecting best routing algorithm out of many routing algorithms. The tool uses a constructive path improvement algorithm to compute paths that give more uniform link load distribution. It also generates different types of traffics. We also developed a simulator capable of simulating source routing for mesh topology NoC. The experiments and simulations which we performed were successful and the results show that the advantages of source routing especially lower packet latency more than compensate its disadvantages. The results also demonstrate that source routing can be a good routing candidate for practical core based SoCs design using network on chip communication infrastructure.
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Satheeskumar, Aravind. "Open Source Model of the Nordic Power System for EU Project Spine." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-286815.
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Decision problems in operation and planning of power systems often rely on large-scale models and data sets. Lack of historical power flow data due to regulatory restrictions often limits researchers to study the system with aggregated network models. Aggregated data from the electricity market operators (Nordpool in the Nordics) and the Transmission System Operator (TSO) (from ENTSO-E) are openly available, and can be used to study the power flow and exchanges between different regions but do not directly provide information about intra-region flows. This project builds upon the Nordic 490 system, a previously built model of the Nordic power system. The main objective of this work is to improve the existing open source power flow model of the Nordic power system, in order to become in turn available for the multi-energy modelling and simulation software Spine. The N490 model generates a model of the Nordic power system consisting of various nodes/buses which represent substations at different voltage levels. Then, it distributes the aggregated production, consumption and power exchange data from Nordpool to the various buses. In this project, different possible improvements are evaluated for the model, aiming at estimating a set of network parameters that minimize the errors between the calculated inter-region flows and the ones from the open data repositories. The different improvements which are evaluated are the following. Firstly, the load distribution is modified and reassigned to match the regional electricity consumption. The generators and wind farms are then reallocated to different bus based on their bidding region and proximity to the bus. The databases are improved and the power balance relation modified. Transmission line parameters are then investigated, first to standard recommended values and then by solving an optimisation problem formulated to extract the parameters from the market data. Finally, the model is also tested with wind and solar generation modelled as a generator rather than as a negative load.Beslutsproblem gällande drift och planering av kraftsystemet baseras ofta på storskaliga modeller och datamängder. Bristen på historiska data gällande effektflöden beror på säkerhetsrestriktioner vilket begränsar forskare till att enbart studera aggregerade nätverksmodeller. Det finns tillgängliga aggregerade data från den nordiska elmarknadsplatsen Nordpool och organisationen ENTSO-E som kan användas för att studera effektflöden mellan olika regioner, dock finns det inte direkta data för flöden inom regionerna. Det här projektet bygger på det nordiska 490-systemet, en tidigare byggd modell av det nordiska kraftsystemet. Huvudsyftet med detta arbete är att förbättra den existerande effektflödesmodellen av det nordiska kraftsystemet, för att i sin tur bli tillgänglig för multienergimodelleringar och simuleringsprogramvaran Spine. N490-modellen genererar en modell för det nordiska kraftsystemet som innehåller olika noder som presenterar ställverk med olika spänningsnivåer och modellen ger också aggregerade data för produktion, konsumtion och effektutbyte mellan de olika noderna från Nordpool. I detta projekt utvärderades olika möjliga förbättringar för modellen som syftar till att uppskatta nätverkets parametrar som kan minimera felen mellan beräkningar av flöde inom regionen och data från öppna datalagringskällor. Följande förbättringar gjordes: Först har lastens fördelning modifierats och ändrats för att matcha den regionala elkonsumtionen. Generatorer och vindkraftsparker allokerades till olika noder baserad på elhandelsområden och närhet till noderna. Databasen förbättrades för att erhålla en bättre effektbalans per område. Kraftledningarnas parametrar ändrades först till rekommenderade standardvärden, vilka sedan förbättrades genom att formulera ett optimeringsproblem för att extrahera parametrarna från markandsdata. Slutligen testades modellen genom att presentera vind- och sol-produktion som generatorer istället för som negativ förbrukning.
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Wahid, Ferdus. "Analysis Of A Wave Power System With Passive And Active Rectification." Thesis, Uppsala universitet, Institutionen för elektroteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-425722.
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Wave energy converter (WEC) harnesses energy from the ocean to produce electrical power. The electrical power produced by the WEC is fluctuating and is not maximized as well, due to the varying ocean conditions. As a consequence, without any intermediate power conversion stage, the output power from the WEC can not be fed into the grid. To feed WEC output power into the grid, a two-stage power conversion topology is used, where the WEC output power is first converted into DCpower through rectification, and then a DC-AC converter (inverter) is used to supply AC power into the grid. The main motive of this research is to extract maximum electrical power from the WEC by active rectification and smoothing the power fluctuation of the wave energy converter through a hybrid energy storage system consisting of battery and flywheel. This research also illustrates active and reactive power injection to the grid according to load demand through a voltage source inverter.
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Unnikrishnan, Harikrishnan. "AUDIO SCENE SEGEMENTATION USING A MICROPHONE ARRAY AND AUDITORY FEATURES." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/622.
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Auditory stream denotes the abstract effect a source creates in the mind of the listener. An auditory scene consists of many streams, which the listener uses to analyze and understand the environment. Computer analyses that attempt to mimic human analysis of a scene must first perform Audio Scene Segmentation (ASS). ASS find applications in surveillance, automatic speech recognition and human computer interfaces. Microphone arrays can be employed for extracting streams corresponding to spatially separated sources. However, when a source moves to a new location during a period of silence, such a system loses track of the source. This results in multiple spatially localized streams for the same source. This thesis proposes to identify local streams associated with the same source using auditory features extracted from the beamformed signal. ASS using the spatial cues is first performed. Then auditory features are extracted and segments are linked together based on similarity of the feature vector. An experiment was carried out with two simultaneous speakers. A classifier is used to classify the localized streams as belonging to one speaker or the other. The best performance was achieved when pitch appended with Gammatone Frequency Cepstral Coefficeints (GFCC) was used as the feature vector. An accuracy of 96.2% was achieved.
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Brady, James Michael. "Real-Time Beamformer Development and Analysis of Weak Signal Detection with Interference Mitigation for Phased-Array Feed Radio Astronomy." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/5644.
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In recent years, the Brigham Young University (BYU) Radio Astronomy Systems group has developed phased-array feeds and the data acquisition processing systems necessary to perform radio astronomy observations. This thesis describes the development and testing of a real-time digital beamforming system that reduces both the time required to process phased-array feed data and the disk space used to record this data compared to post-processing beamforming systems. A real-data experiment is also discussed in this thesis, which focuses on some of the data post-processing required for one of BYU's data acquisition systems.Radio-frequency interference mitigation techniques for phased-array feed radio astronomy have been studied for several years, but the effect that these techniques have on weak-signal detection is not well understood. This thesis provides analysis of a simulated weak-source observation for the Green Bank 20-meter telescope and BYU 19 element phasedarray feed with radio-frequency interference present. Interference mitigation techniques are shown to reduce the detectability of weak sources compared with the no interference case, but it is also shown that a weak source can be detected that would otherwise be masked by interference.
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Jimenez, Saldana Cristhian Carim. "Large Scale Analysis of Massive Deployment of Converter-based Generation equipped with Grid- forming Strategies." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-292690.
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To mitigate the carbon footprint and the need to fulfil the energy goals in terms of sustainability, it is required to deploy a large integration of green energies. Therefore, in the previous and the coming years, there will be a high research and technological interest in the high penetration of converter-based generation. With the replacement and integration of power converters into the bulk power grid, new challenges and issues must be faced to maintain the system´s stability and reliability in terms of procedures for the transmission system operators. The main objective of this thesis project is to analyze and to implement the current- limiting techniques implemented in voltage source converters, which are equipped with grid-forming functionalities so that these electronic devices are safeguarded during a severe transient event as three-phase short-circuit and remain connected to the grid during the fault scenario. The model of the voltage source converter with grid-forming strategies is described as well as the grid-forming strategies (droop control, virtual synchronous machine (VSM) and dispatchable virtual oscillator control (dVOC)) utilized in the outer loop. The low-inertia and zero-inertia system in the IEEE 9-Bus test system were exhibited to be resilient towards 3-phase fault events, and their behavior shows neither significant oscillations during and after the incident of the fault nor noticeable difference in their performance regarding the location. In this test system model, the current-limiting techniques were validated and analyzed results display good effectiveness for the current and frequency. The Hydro-Québec network model was employed to have a more practical approach in the behavior of the current limitation strategies in the power converters in a real power system. The fault location and the percentage of participation of the voltage source converters in the energy generation were the two main scenarios, in which the proposed control strategies for restricting the current work but simultaneously, it is required an appropriate control to keep the system´s stability.För att minska koldioxidutsläppet och uppnå energimålen med avseende på hållbarhet krävs integrering av hållbara energikällor. Därmed, under de föregående och kommande åren kommer stort fokus riktas mot forskning kring ökad penetration av kraftelektronikomriktare i kraftsystemet. När kraftelektronikomriktare ersätter traditionella generationsenheter uppkommer nya utmaningar och problem som behöver lösas för att upprätthålla systemets stabilitet och pålitlighet med avseende på tillvägagångssätt för systemansvariga för överföringssystemet. Avhandlingens huvudmål är att analysera och implementera strömbegränsande metoder för kraftelektronikomriktare av typen voltage source converters med en nätformande (”grid- forming”) funktionalitet. Strömbegränsaren ska säkerställa att kraftelektronikomriktaren skyddas under allvarliga transienta händelser och att kraftelektronikomriktaren förblir ansluten till nätet under händelsen. Modellen av kraftelektronikomriktaren med nätformande egenskaper är beskrivna tillsammans med nätformande kontrollstrategier, virtuella synkronmaskniner (VSM) och användande av avsändande virtuell oscillerande kontroll i den yttre slingan. Den låga trögheten och noll-tröghetssystemet i IEEE 9-Bus test-system visade sig vara motståndskraftig mot trefasfel eftersom testsystemets beteende visade varken signifikanta oscillationer under och efter felet eller märkbar förändring i dess prestanda beroende på var felet inträffade. I denna testsystemsmodell var strömbegränsande tekniker validerade och de analyserande resultaten visade på god effektivitet för strömmen och för frekvensen. Hydro-Québec nätverks-modellen användes för att få en mer praktisk inriktning med hänsyn till beteendet hos strömbegränsarna där olika strategier har använts. Felpositionen och andelen av kraftelektronikomriktare i energigenereringen var två huvudsakliga scenarion, där de föreslagna kontrollstrategierna för att begränsa strömmen fungerade men kräver samtidigt att en lämplig kontroll för att behålla systemets stabilitet.
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Krupenia, Stas Simon. "An event related potential (ERP) study of symptomatic and asymptomatic adults with attention deficit hyperactivity disorder (ADHD)." University of Western Australia. School of Psychology, 2003. http://theses.library.uwa.edu.au/adt-WU2003.0035.
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This study recorded Event Related Potentials (ERPs) during completion of a Continuous Performance Task (CPT) in order to identify the contribution of response inhibition, working memory, and response monitoring to the pattern of hyperactive and impulsive and inattentive behaviour observed in patients with Attention Deficit Hyperactive Disorder (ADHD). Four ERP components, Nogo N2, Nogo P3, Go P3, and the ERN were examined and compared using a symptomatic and asymptomatic ADHD sample, and a healthy control group. The Nogo N2 had the expected frontal scalp distribution and was affected by changes to inhibitory demands. It was also suggested that this component was not wholly determined by inhibitory processing and may have been influenced by differing presentation rates of the Go stimulus, a template matching process or an in-depth response strategy. Source localisation analysis suggested a right frontal generator for this component. The Nogo P3 had the expected central distribution and had equal amplitude for those participants that were more efficient at inhibiting behaviours compared to those participants that were less efficient inhibitors. Contrary to expectations, the Nogo P3 was not affected by increasing the inhibitory demands of the task and was suggested as being a less reliable indicator of response inhibition in the present study. The Go P3 had the expected centro-parietal distribution, and appeared to provide a reliable index of working memory. Response inhibition and working memory were not impaired in the sample of symptomatic and asymptomatic ADHD adults used in this study. The symptomatic group elicited a slightly enhanced ERN compared to the asymptomatic and control groups, indicating that deficits in response monitoring may contribute to the pattern of problematic behaviour observed in people with ADHD.
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Fischer, de Toledo Paulo. "Modelling and control of a line-commutated HVDC transmission system interacting with a VSC STATCOM." Doctoral thesis, KTH, Elektriska maskiner och effektelektronik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4492.
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The interaction of an HVDC converter with the connected power system is of complex nature. An accurate model of the converter is required to study these interactions. The use of analytical small-signal converter models provides useful insight and understanding of the interaction of the HVDC system and the connected system components. In this thesis analytical models of the HVDC converters are developed in the frequency-domain by calculating different transfer functions for small superimposed oscillations of voltage, current, and control signals. The objective is to study the dynamic proprieties of the combined AC-DC interaction and the interaction between different HVDC converters with small signal analysis. It is well known that the classical Bode/Nyquist/Nichols control theory provides a good tool for this purpose if transfer functions that thoroughly describe the 'plant' or the 'process' are available. Thus, there is a need for such a frequency-domain model. Experience and theoretical calculation have shown that voltage/power stability is a very important issue for an HVDC transmission link based on conventional line-commutated thyristor-controlled converters connected to an AC system with low short circuit capacity. The lower the short circuit capacity of the connected AC system as compared with the power rating of the HVDC converter, the more problems related to voltage/power stability are expected. Low-order harmonic resonance is another issue of concern when line-commutated HVDC converters are connected to a weak AC system. This resonance appears due to the presence of filters and shunt capacitors together with the AC network impedance. With a weak AC system connected to the HVDC converter, the system impedances interact through the converter and create resonances on both the AC- and DC-sides of the converter. In general, these resonance conditions may impose limitations on the design of the HVDC controllers. In order to improve the performance of the HVDC transmission system when it is connected to a weak AC system network, a reactive compensator with a voltage source converter has been closely connected to the inverter bus. In this thesis it is shown that the voltage source converter, with an appropriate control strategy, will behave like a rotating synchronous condenser and can be used in a similar way for the dynamic compensation of power transmission systems, providing voltage support and increasing the transient stability of the converter.QC 20100708
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Jarushi, Ali Milad. "Analysis and modelling of energy source combinations for electric vehicles." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/analysis-and-modelling-of-energy-source-combinations-for-electric-vehicles(3674cf1a-b471-492f-8f6d-a3afb1039998).html.
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The objective of this research is to develop suitable models to simulate and analyse Electrical Vehicle (EV) power-trains to identify and improve some of the deficiencies of EVs and investigate new system architectures. Although some electro-chemical batteries improvements have lately been achieved in specific-energy, the power density is still low. Therefore, an efficient, cost-effective and high power density support unit could facilitate EV competitiveness compared to conventional internal combustion engine powered vehicles in the near future. The Na-Ni-Cl2, or ZEBRA battery as it is most commonly known, has good energy and power densities; it is very promising electro-chemical battery candidate for EV's. The thesis presents a detail simulation model for the ZEBRA technology and investigates its application in an EV power-train with regard to state-of-charge and voltage transients. Unlike other battery systems, the ZEBRA technology can sustain about 5-10% of failed cells. While this is advantageous in single series string or single battery operation it is problematic when higher numbers of batteries are connected in parallel. The simulation model is used to investigate faulted operation of parallel battery configurations. A non-linear capacitance versus voltage function is implemented for the supercapacitor model which yields good energy and terminal voltage predictions when the supercapacitor is cycled over dynamic regimes common to EV applications. A thermal model is also included. Multiple energy source systems are modelled and studied in the form of an energy dense ZEBRA battery connected in parallel with a power dense supercapacitor system. The combination is shown to increase available power, reduce the maximum power demanded from the battery and decrease battery internal power loss. Consequently, battery life would be increased and more energy would be recovered from regenerative braking, enhancing the energy conversion efficiency of the power-train.A combination of ICE and ZEBRA battery is implemented as a range extender for London taxi driving from Manchester to London. The hybridisation ratio of the system is discussed and applied to fulfil the requirement with minimum emissions. This study offers a suitable model for different energy sources, and then optimises the vehicle energy storage combination to realize its full potential. The developed model is used to assess different energy source combinations in order to achieve an energy efficient combination that provides an improved vehicle performance, and, importantly, to understand the energy source interconnection issues in terms of energy flow and circuit transients.
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Chetlur, Adithya Prashanth. "A Novel Framework to Determine Physiological Signals From Blood Flow Dynamics." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7610.
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Centers for Disease Control and Prevention (CDC) estimate that more than 11.2 million people require critical and emergency care in the United States per year. Optimizing and improving patient morbidity and mortality outcomes are the primary objectives of monitoring in critical and emergency care. Patients in need of critical or emergency care in general are at a risk of single or multiple organ failures occurring due to a traumatic injury, a surgical event, or an underlying pathology that results in severe patient hemodynamic instability. Hence, continuous monitoring of fundamental cardiovascular hemodynamic parameters, such as heart rate, respiratory rate, blood pressure, blood oxygenation and core temperature, is essential to accomplish diagnostics in critical and emergency care. Today’s standard of care measures these critical parameters using multiple monitoring technologies.
Though it is possible to measure all the fundamental cardiovascular hemodynamic parameters using the blood flow dynamics, its use is currently only limited to measuring continuous blood pressure. No other comparable studies in the literature were successful in quantifying other critical parameters from the blood flow dynamics for a few reasons. First, the blood flow dynamics exhibit a complicated and sensitive dynamic pressure field. Existing blood flow based data acquisition systems are unable to detect these sensitive variations in the pressure field. Further, the pressure field is also influenced by the presence of background acoustic interference, resulting in a noisy pressure profile. Thus in order to extract critical parameters from this dynamic pressure field with fidelity, there is need for an integrated framework that is composed of a highly sensitive data acquisition system and advanced signal processing. In addition, existing state-of-the-art technologies require expensive instrumentation and complex infrastructure. The information sensed using these multiple monitoring technologies is integrated and visualized using a clinical information system. This process of integration and visualization creates the need for functional interoperability within the multiple monitoring technologies. Limited functional interoperability not only results in diagnostic errors but also their complexity makes it impossible to use such technologies to accomplish monitoring in low resource settings. These multiple monitoring technologies are neither portable nor scalable, in addition to inducing extreme patient discomfort. For these reasons, existing monitoring technologies do not efficiently meet the monitoring and diagnostic requirements of critical and emergency care.
In order to address the challenges presented by existing blood flow based data acquisition systems and other monitoring systems, a point of care monitoring device was developed to provide multiple critical parameters by means of uniquely measuring a physiological process. To demonstrate the usability of this novel catheter multiscope, a feasibility study was performed using an animal model. The corresponding results are presented in this dissertation. The developed measurement system first acquires the dynamics of blood flow through a minimally invasive catheter. Then, a signal processing framework is developed to characterize the blood flow dynamics and to provide critical parameters such as heart rate, respiratory rate, and blood pressure. The framework used to extract the physiological data corresponding to the acoustic field of the blood flow consisted of a noise cancellation technique and a wavelet based source separation. The preliminary results of the acoustic field of the blood flow revealed the presence of acoustic heart and respiratory pulses. A unique and novel framework was also developed to extract continuous blood pressure from the pressure field of the blood flow. Finally, the computed heart and respiratory rates, systolic and diastolic pressures were benchmarked with actual values measured using conventional devices to validate the measurements of the catheter multiscope.
In summary, the results of the feasibility study showed that the novel catheter multiscope can provide critical parameters such as heart rate, respiratory rate and blood pressure with clinical accuracy. In addition, this dissertation also highlights the diagnostic potential of the developed catheter multiscope by presenting preliminary results of proof of concept studies performed for application case studies such as sinus rhythm pattern recognition and fetal monitoring through phonocardiography.
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Bobrowski, Christoph. "Quellenlokalisation laserevozierter zerebraler Potentiale durch die Brain-electric-source-Analysis (BESA)." [S.l.] : [s.n.], 1998. http://www.sub.uni-hamburg.de/disse/177/index.htm.
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Savas, Zafer. "Real-time Detection And Tracking Of Human Eyes In Video Sequences." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606459/index.pdf.
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Robust, non-intrusive human eye detection problem has been a fundamental and challenging problem for computer vision area. Not only it is a problem of its own, it can be used to ease the problem of finding the locations of other facial features for recognition tasks and human-computer interaction purposes as well. Many previous works have the capability of determining the locations of the human eyes but the main task in this thesis is not only a vision system with eye detection capabilityOur aim is to design a real-time, robust, scale-invariant eye tracker system with human eye movement indication property using the movements of eye pupil. Our eye tracker algorithm is implemented using the Continuously Adaptive Mean Shift (CAMSHIFT) algorithm proposed by Bradski and the EigenFace method proposed by Turk &
Pentland. Previous works for scale invariant object detection using Eigenface method are mostly dependent on limited number of user predefined scales which causes speed problems
so in order to avoid this problem an adaptive eigenface method using the information extracted from CAMSHIFT algorithm is implemented to have a fast and scale invariant eye tracking. First of all
human face in the input image captured by the camera is detected using the CAMSHIFT algorithm which tracks the outline of an irregular shaped object that may change size and shape during the tracking process based on the color of the object. Face area is passed through a number of preprocessing steps such as color space conversion and thresholding to obtain better results during the eye search process. After these preprocessing steps, search areas for left and right eyes are determined using the geometrical properties of the human face and in order to locate each eye indivually the training images are resized by the width information supplied by the CAMSHIFT algortihm. Search regions for left and right eyes are individually passed to the eye detection algortihm to determine the exact locations of each eye. After the detection of eyes, eye areas are individually passed to the pupil detection and eye area detection algorithms which are based on the Active Contours method to indicate the pupil and eye area. Finally, by comparing the geometrical locations of pupil with the eye area, human gaze information is extracted. As a result of this thesis a software named &ldquo
TrackEye&rdquo
with an user interface having indicators for the location of eye areas and pupils, various output screens for human computer interaction and controls for allowing to test the effects of color space conversions and thresholding types during object tracking has been built.
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Afroozi, Milani Mohammad. "Non-linear analysis of optical and microwave sources." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6675/.
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Due to the ever increasing need for better and more capable communication systems, a large quantity of research is focused on the design and simulation of different sections of communication systems including the communication sources. Due to the massive cost of the fabrication involved in designing new communication sources, the accurate modelling and design of these sources using Computer Aided Design is of great interest. In this thesis fundamentals of laser modelling and nonlinear microwave antenna design; followed by reviewing the most important works carried out by other researchers in these fields. The thesis continues by introducing a proposed, accurate model of the Vertical Cavity Surface Emitting Laser (VCSEL). The proposed model integrates the effects of the matching network as well as the parasitics, due to the VCSEL chip and the packaging mounting and the intrinsic VCSEL noise sources. Further in this thesis, a nonlinear Composite Right/Left Handed frequency doubler Leaky Wave Antenna is designed which is capable of transmitting a signal in a direction that can be varied continuously from backfire to endfire, by varying the input frequency to the structure. The novelty of the proposed design is in the inclusion of nonlinear elements in the CRLH structure and also in the use of a quasi-lumped approach when designing the distributed structure. Finally, in this thesis a novel method of combining harmonic balance and EM analysis for the design and optimisation of nonlinear active antennas is developed. This method responds to the restriction of the CAD software in conveniently combining the analysis of nonlinear active antennas with advanced EM simulations such as radiation patterns. The proposed method enables the advanced EM analysis at the harmonic frequencies, generated within the nonlinear microwave structures when the structure is exited at the fundamental frequency, to be combined with full electromagnetic simulators.
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Dailey, R. Gordon Jr. "An analysis of renewable energy technologies for electric utilities in Georgia." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/28922.
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Malkowski, Susan Kate. "MAGNETIC SHIELDING STUDIES FOR THE NEUTRON ELECTRIC DIPOLE MOMENT EXPERIMENT AT THE SPALLATION NEUTRON SOURCE." UKnowledge, 2011. http://uknowledge.uky.edu/physastron_etds/1.
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The neutron Electric Dipole Moment Experiment at the Spallation Neutron Source requires an overall magnetic shielding factor of order 105 to attenuate external background magnetic fields. At present, the shielding design includes an external (room-temperature) multi-layer μ-metal magnetic shield, a cryogenic (4 Kelvin) Pb superconducting shield, and a cryogenic (4 Kelvin) ferromagnetic shield composed of Metglas ribbon. This research determined how to construct a Metglas shield using minimal material that produced axial and transverse shielding factors of ~267 and ~1500. In addition, the μ-metal and Metglas shields were modeled using finite element analysis. The FEA model includes external coils and their effect on the residual magnetic fields. This study will help with the design of the shielding.
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Falk, Lissel Linus. "Pass-by noise contribution analysis of electric vehicles." Thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159271.
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In the modern urban lifestyle, more and more people are exposed to noise pollution in form of traffic noise. As a response to this, the automotive OEMs (Original Equipment Manufacturer) are put under pressure to reduce the emitted noise from vehicles. To be able to meet the upcoming, stricter regulations, the automotive OEMs seeks new techniques to be able to front load the pass-by noise engineering in the vehicle development process and to identify and understand the different sources that contributes to the exterior noise.Earlier exterior sources ranking using ASQ (Airborn Source Quantification) with an energetic approach during pass-by noise test has yielded very good and reliable results for an ICE (Internal Combustion Engine) vehicle.In this Master Thesis, two exterior source ranking methods have been tested and evaluated for an electric vehicle during in-room pass-by noise test. The two methods were: ASQ and OPA (Operational Path Analysis). In total, five models were built from the two methods and each model was evaluated for, in total, three driving conditions corresponding to the current ISO362-1:2007 and the proposed, revised version.The results show that the ASQ models are not capable to correctly estimate the engine contribution due to its high tonality. Moreover, it was seen that the energetic ASQ model is very sensitive to small changes. Both ASQ models underestimated the tire noise.The OPA model on the other hand managed to estimate the total contribution very well. Both the engine contribution and the tire contributions are well estimated. Nevertheless, OPA as method has several weaknesses and building an OPA model is not a straightforward task. Its weaknesses and the process to reach a final OPA model are discussed in this thesis.It was seen that one of the most crucial steps in an OPA model is to have clean references to get meaningful results. A MIMO-FIR filter was therefore used to filter out engine harmonics from the tire references. Its principles and importance for the end results are also discussed.Included is also an overview of the basic principles in TPA (Transfer Path Analysis), ASQ, OPA and in room pass by noise test as well as a description of the test campaign.
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Mittal, Shawn. "Computational Analysis and Design of the Electrothermal Energetic Plasma Source Concept." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/52705.
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Electrothermal (ET) Plasma Technology has been used for many decades in a wide variety of scientific and industrial applications. Due to its numerous applications and configurations, ET plasma sources can be used in everything from small scale space propulsion thrusters to large scale material deposition systems for use in a manufacturing setting. The sheer number of different types of ET sources means that there is always additional scientific research and characterization studies that can be done to either explore new concepts or improve existing designs.
The focus of this work is to explore a novel electrothermal energetic plasma source (ETEPS) that uses energetic gas as the working fluid in order to harness the combustion and ionization energy of the subsequently formed energetic plasma. The goal of the work is to use computer code and engineering methods in order to successfully characterize the capabilities of the ETEPS concept and to then design a prototype which will be used for further study.
This thesis details the background of ET plasma physics, the ETEPS concept physics, and the computational and design work done in order to demonstrate the feasibility of using the ETEPS source in two roles: space thrusters and electrothermal plasma guns.Master of Science
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Ghanian, Nariman, Esfahani William Mohammad Farhang, and Muhammad Touqeer Ul Hassan. "Electrical energy analysis in nine countries of Europe, with focus on wind power and other renewable energy sources." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-689.
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This thesis has been written for the Bachelor degree in Electrical Engineering held at Blekinge Tekniska Högskola Karlskrona, Sweden. The basis of this thesis is a statistical analysis of the electrical energy situation with emphasis on contribution of wind power and other renewable energy in electricity production in the European area and key countries. The main parameters, which considered in this thesis are electricity production and consumption, installed capacity trends and also the operation of renewable sources, especially wind power in gross electricity generation. Meanwhile, the whole date and materials are based on real values and investigated from the latest publications of governments and energy agencies of European union and key countries. The target of European renewable energy is that the member countries must achieve at least 20 percent of final energy consumption from renewable energy by 2020. Germany, United Kingdom, Spain and France and Portugal are members of the highest consumers of electricity in the Europe and still the main source of electrical production in these countries are fossil fuels, the main challenge is that they should start to shutting down the traditional power plant and improve the infrastructure for installing the renewable electrical capacity instead. According to the statistics, many of the European countries such as United Kingdom, Germany, Spain, Denmark and Sweden have started up to use the renewable energy to produce the electrical energy, but their governments have special keen eye for investment in the wind energy sector. Wind power grew sharply during the past decades in Europe and becoming vital every coming day in comparison to other renewable energy, since the low cost of electricity can be granted through a small investment and relies on the wind blowing compared to the conventional electricity generation sources. The diagrams demonstrate the wind power has a main portion to producing the electrical energy and every year a considerable amount of installed capacity is added to the total electrical grid. In addition, the expansion of renewable energy to achieve the high percent of electrical production requires the improvement of infrastructure such as ecological research and high coordination between different organizations. Also, the electrical generation cannot be constant, and in winter the overall consumption and demand for electricity increases all over Europe. The exploitation of some renewable sources such as solar and wind power for electrical production can have fluctuation due to the weather condition and wind speed, which can affect the overall generation to the electrical grid. Therefore, the balancing of several renewable sources in different seasons, needs the unique power management for reliable electrical production. In this trend, Norway is a successful country in Europe that uses over 90 percent of renewable sources for total electrical generation. The thesis has covered these challenges and how they are overcoming these issues.
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Scholes, Richard Burton 1968. "Analysis of derivative MUSIC with two correlated or uncorrelated sources and its extension to a planar array." Thesis, The University of Arizona, 1996. http://hdl.handle.net/10150/278617.
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This thesis presents a novel spatial spectrum estimation technique, ∂-MUSIC, for discriminating between two closely spaced sources which are highly correlated. The ∂-MUSIC algorithm is tested, modified, and compared to the MUSIC algorithm using a point source simulation. Various power levels, samples sizes and angle separations are used on a linear and a planar array for correlated and uncorrelated sources. The algorithm is found to be relatively insensitive to correlation and can separate targets to one-half of the angular separation threshold of ∂-MUSIC. The ∂-MUSIC algorithm is tested using a simulation that generated terrain scattered interference representative of a propagation scenario involving multiple paths. The simulation shows that ∂-MUSIC is able to resolve the direct path and image at less than one-fourth of a beam width, with a ten degree angle to the surface, whereas MUSIC finds a single angle which is biased toward the image.
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Xu, Yang. "Performance Analysis of Point Source Model with Coincident Phase Centers in FDTD." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-theses/214.
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The Finite Difference Time Domain (FDTD) Method has been a powerful tool in numerical simulation of electromagnetic (EM) problems for decades. In recent years, it has also been applied to biomedical research to investigate the interaction between EM waves and biological tissues. In Wireless Body Area Networks (WBANs) studies, to better understand the localization problem within the body, an accurate source/receiver model must be investigated. However, the traditional source models in FDTD involve effective volume and may cause error in near field arbitrary direction. This thesis reviews the basic mathematical and numerical foundation of the Finite Difference Time Domain method and the material properties needed when modeling a human body in FDTD. Then Coincident Phase Centers (CPCs) point sources models have been introduced which provide nearly the same accuracy at the distances as small as 3 unit cells from the phase center. Simultaneously, this model outperforms the usual sources in the near field when an arbitrary direction of the electric or magnetic dipole moment is required.
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Li, Sujuan. "Evaluating ambient fine particulate matter source regions in the Ohio River Valley Region." Ohio : Ohio University, 2003. http://www.ohiolink.edu/etd/view.cgi?ohiou1070550479.
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Elrayyah, Ali Y. "Modeling and Control of Microgrid-Connected Photo-Voltaic Sources (MCPV)." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1384345552.
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Hassan, Mahmoud. "Analysis of the propagation of uterine electrical activity applied to predict preterm labor : prédiction de menaces d'accouchement prématuré." Compiègne, 2011. http://www.theses.fr/2011COMP1948.
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Les contractions utérines sont contrôlées par deux phénomènes physiologiques: l'excitabilité cellulaire et la propagation de l'activité électrique utérine probablement liées aux hautes et basses fréquences de l'electrohysterograme (EHG) respectivement. Toutes les études précédentes ont porté sur l'extraction de paramètres de la partie haute fréquence et n'ont pas montré un potentiel satisfait pour l'application clinique. L'objectif de cette thèse est l'analyse de propagation de l'EHG pendant la grossesse et le travail dans la vue de l'extraction des outils pour une application clinique. Une des nouveautés de la thèse est l'enregistrement multicanaux à l'aide d'une matrice d'électrodes 4x4 posée sur l'abdomen de la femme. Analyse monovariés visait à étudier les caractéristiques non linéaires des signaux EHG, analyses bivariées et multivariées ont été effectuées pour analyser la propagation des signaux EHG par la détection de la connectivité entre les signaux. Une augmentation de la non-linéarité associée par une synchronisation en amplitude et de désynchronisation en phase a été détectée. Les résultats indiquent plus de propagation au cours du travail que la grossesse et une augmentation de cette propagation avec les semaines de gestations. Les résultats montrent le potentiel élevé de paramètres de propagation dans le point de vue clinique tel que la détection du travail et de prédiction du travail prématuré. Finalement, nous avons proposé une nouvelle combinaison entre Séparation Aveugles de Sources et la Décomposition en Modes Empiriques pour débruiter les signaux EHG monopolaires comme un moyen possible d'augmenter le taux de classification de signaux grossesse et l'accouchementUterine contractions are essentially controlled by two physiological phenomena: cell excitability and propagation of uterine electrical activity probably related to high and low frequencies of uterine electromyogram, called electrohysterogram -EHG-, respectively. All previous studies have been focused on extracting parameters from the high frequency part and did not show a satisfied potential for clinical application. The objective of this thesis is the analysis of the propagation EHG signals of during pregnancy and labor in the view of extracting tool for clinical application. A novelty of our thesis is the multichannel recordings by using 4x4 electrodes matrix posed on the woman abdomen. Monovariate analysis was aimed to investigate the nonlinear characteristics of EHG signals. Bivariate and multivariate analyses have been done to analyze the propagation of the EHG signals by detecting the connectivity between the signals. An increase of the nonlinearity associated by amplitude synchronization and phase desynchronization were detected. Results indicate a highest EHG propagation during labor than pregnancy and an increase of this propagation with the week of gestations. The results show the high potential of propagation’s parameters in clinical point of view such as labor detection and then preterm labor prediction. We proposed novel combination of Blind Source Separation and empirical mode decomposition to denoise monopolar EHG as a possible way to increase the classification rate of pregnancy and labor
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Ray, Mike C. T. "Solar Data Analysis." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1078.
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The solar industry has grown considerably in the last few years. This larger scale has introduced more problems as well as possibilities. One of those possibilities is analyzing the data coming from the sites that are now being monitored, and using the information to answer a variety of questions.
We have four questions which are of prime importance identified in this thesis:
1. Can data from customers be trusted?
2. Can we use data from existing sites to determine which sites need the most improvement?
3. Can we implement a location-based algorithm to reduce the amount of false positives for performance, or other alarms?
4. Can we improve upon the current predicted power algorithm?
We find that not only can we answer these questions definitively, but the improvements found are of significant value. Each of these items represents an important question that either directly or indirectly translates into increased revenue and engineering improvements for the solar industry as a whole.
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Aljadid, Abdolmonem Ibrahim. "Control and protection analysis for power distribution in a distributed generation system." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2192.
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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology.Distributed Generation systems based on renewable energy sources, such as wind or solar are mostly intermittent sources, due to their dependency on the weather, whereas those based on other primary energy sources are non-intermittent. All of them are specially designed to be integrated into distribution systems, in order to improve the power demand of consumers. In the last few decades of the twentieth century, several different factors have played a key role in increasing interest in systems. Distributed Generation (DG) is gaining more and more attention worldwide as an alternative to large-scale central generating stations. The aim of this research project is to investigate the contribution of distributed generation in fault current level in a power distribution system. The simulation results indicate that DG can have a positive or negative impact, on the fault current level in distribution network systems. The DG location and size affect the fault level. The second aim of this research was to suggest a model-based method for design, and implementation of a protection scheme for power distribution systems, by establish algorithms in a hardware environment. The overcurrent relay was chosen for the model development because it is considered a simple and popular protection scheme, and it is a common scheme in relaying applications. The proposed relay model was tested for fault conditions applied on a simple power system in different scenarios. The overcurrent relay model was implemented in MATLAB/Simulink, by using MATLAB programming languages and the SimPowerSystem (SPS) Tool. MATLAB/SIMULINK software is applicable to the modelling of generation, transmission, distribution and industrial grids, and the analysis of the interactions of these grids. This software provides a library of standard electrical components or models such as transformers, machines, and transmission lines. Therefore, the modelling and simulations are executed using MATLAB/Simulink version 2014b
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Musoni, Nkusi Emmanuel. "Analysis of the effect of renewable generation on the power quality of the grid, modelling and analysis of harmonic and voltage distortion." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2805.
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Thesis (Master of Engineering in Electrical Engineering)--Cape Peninsula University of Technology, 2018.As the electric energy demand grows, there is a significant increase in the penetration of renewable generation (RG) in the existing electrical grid network. Interconnecting of renewable generation technologies to an existing distribution system has proven to provide various benefits such as meeting the growing load demand and its contribution to energy system decarbonisation, long-term energy security and expansion of energy access to new energy consumers in the developing urban and rural areas. However, the aim of this thesis is to conduct a study on the impacts of renewable generation on the power quality of electrical grid. Therefore, this work aims at assessing the potential effects of Distributed Generation (DG) on the operation of electric power system by modelling of harmonics and voltage distortion. With different types of renewable generation available at present, it is believed that some designs contribute significantly to electrical network’s Power Quality (PQ). After the analysis of harmonic currents (chapter 6 and 7 of this thesis) introduced by renewable generation technologies, their negative impact on the power quality of the grid is seen to be apparent at point of connection (POC) but only within controlled limits. Analytical method for modeling of harmonic interactions between the grid and aggregated distributed generation technologies are investigated using DIgSILENT Power Factory software and the results obtained are discussed.
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Gupta, Gunjan. "An analysis and improvement of selected features of power quality of grid-tied alternative energy systems." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2696.
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Thesis (PhD (Electrical Engineering))--Cape Peninsula University of Technology, 2018.Electrical energy can be easily used and converted to other forms of energy for various applications. Technological advancement increases the dependency on electricity to a great extent. Various internal and external factors are responsible for the bad quality of power in power systems. The performance of the system is greatly affected by the presence of harmonics, as well as voltage and frequency variations, which leads to the malfunctioning of the device and decline of power quality and supply at load side. The reactive power compensation is carried out for better power quality. The literature survey is done to find the best and efficient scheme for reactive power compensation and mitigation of various power quality problems. The devices which are used to measure various power quality factors are discussed. Various mitigating schemes are surveyed in order to compensate reactive power and to improve the power quality at the distribution end. The integration of the most widely used renewable energy, wind energy in the distribution system creates technical issues like stability of the grid, harmonic distortion, voltage regulation, active and reactive power compensation etc. which are restricted to IEC and IEEE standards. One of the topics this thesis addresses is regulation in the reactive power generated along with voltage regulation by using an effective power electronics device known as a STATCOM. The main power quality factors like overvoltage and voltage flickers are mitigated by establishing STATCOMs in small wind farms. The wind farms are equipped with three wind turbines. These three wind turbines found in the wind farm can be operated together or one after another with an introduced delay. A glitch in even a little piece of a power grid can result in loss of efficiency, income and at times even life. In this manner, it is basic to outline a system which can distinguish the faults of the power system and take a faster response to recover it back to required reactive power. Two devices STATCOM and D-STATCOM are used for this purpose in this thesis. The D-STATCOM circuit and operating principle are also discussed in thesis. Different topologies of D-STATCOM discussed with their benefits and shortcomings. The voltage, current and hybrid technologies of D-STATCOM are also discussed.
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You, Keping Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "A new bidirectional AC-DC converter using matrix converter and Z-source converter topologies." Awarded by:University of New South Wales, 2007. http://handle.unsw.edu.au/1959.4/37450.
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This thesis proposes a new bidirectional three-phase AC-DC power converter using matrix converter and Z-source inverter topologies. Advantages of the AC-DC matrix converter are the inherently controllable power factor, the tight DC voltage regulation, the wide bandwidth with quick response to load variation, the single-stage buck-voltage AC-to-DC power conversion; advantages of the z-source inverter are the increased reliability by allowing the shoot-through between upper and lower power switches of one inverter leg, insensitivity to DC bus voltage due to the extra freedom of controlling DC-link voltage. The proposed Matrix-Z-source converter (MZC) marries up both advantages of AC-DC matrix converter and Z-source inverter. It can achieve voltage-boost DC-AC inversion capable of variable voltage variable frequency (VVVF) AC output; it can achieve voltage-buck AC-DC rectification capable of inherent control over AC current phase angle and DC output regulation with a (VVVF) AC source supply. Both foresaid performance in DC-AC inversion and AC-DC rectification can be implemented in a simple open-loop control manner. Three constraints of VSI, in the bidirectional AC-DC power conversion, are the peak AC voltages are always less than DC-link voltage, closed-loop control has to be employed when DC regulation and/or AC current phase angle control are required, and AC voltage is sensitive to the variation of the DC-link voltage in DC-AC inversion. The voltage-boost inversion and/or voltage-buck rectification of MZC overcomes the first constraint; thus MZC enables the AC machine voltage increased higher than DC-link voltage hence advantages of running AC machine at relatively high voltages are enabled. The direct DC voltage regulation and inherent AC-current-phase-angle control of MZC overcomes the second constraint in an open-loop manner; hence a simplified system design is obtained with sufficient room for the further improvement by closed-loop control schemes. The extra freedom in controlling DC-link voltage of MZC overcomes the third constraint hence a DC source voltage adaptable inverter is obtained. This thesis focuses on the study of the feasibility of the proposed MZC through theoretical analysis and experimental verification. At first, the proposed MZC is conceptually constructed by examining the quadrant operation of AC-DC matrix converter and Z-source inverter. After the examination of the operating principles of both AC-DC matrix converter and Z-source inverter, the configuration of MZC is then proposed. The MZC has two operating modes: DC-AC inversion and AC-DC rectification. Circuit analysis for both operating modes shows that the new topology does not impose critical conflict in circuit design or extra restriction in parameterization. On the contrary, one version of the proposed MZC can make full advantage of Z-source network components in both operating modes, i.e. a pair of Z-source inductor and capacitor can be used as low-pass filter in AC-DC rectification. The modulation strategy, average modeling of system, and features of critical variables for circuit design of the proposed MZC were examined for each operating mode. Simulations of the proposed MZC and its experimental verification have been presented. Analytical models of conduction and switching losses of the power-switch network in different operating mode have shown that the losses in the MZC compare favorably with conventional VSI for a range of power factor and modulation indices.
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Sabala, Ryan J. "Satellite Attitude Determination Using Laser Communication Systems." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1218636153.
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Khan, Amir Ali. "Séparation de sources thermométriques." Phd thesis, Grenoble INPG, 2009. http://tel.archives-ouvertes.fr/tel-00477455.
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Ce travail de thèse aborde un problème de la détection des fuites d'eau dans des digues en terre. L'écoulement préférentiel, un indicateur de destruction interne, résulte dans une anomalie thermique. Les capteurs DTS basés sur la fibre optique offrent une solution efficace pour les mesures spatio-temporelles de température. Les données thermométriques sont influencées par différents facteurs comme la réponse du sol, les variations saisonnières, l'environnement géomécanique, etc. Afin d'écarter des phénomènes comme les précipitations, nous proposons un critère basé sur le skewness et le kurtosis. La détection des fuites étant formulée comme un problème de séparation de sources, nous présentons un système basé sur la SVD et l'ICA pour séparer les informations utiles liées aux fuites des autres facteurs. Dans le cas où le nombre d'acquisitions en temps est limité, nous proposons un détecteur de singularités exploitant les dissimilarités entre les mesures journalières de température aux différentes distances.
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Moghadasiriseh, Amirhasan. "Analysis and Modeling of Advanced Power Control and Protection Requirements for Integrating Renewable Energy Sources in Smart Grid." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2469.
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Attempts to reduce greenhouse gas emissions are promising with the recent dramatic increase of installed renewable energy sources (RES) capacity. Integration of large intermittent renewable resources affects smart grid systems in several significant ways, such as transient and voltage stability, existing protection scheme, and power leveling and energy balancing. To protect the grid from threats related to these issues, utilities impose rigorous technical requirements, more importantly, focusing on fault ride through requirements and active/reactive power responses following disturbances. This dissertation is aimed at developing and verifying the advanced and algorithmic methods for specification of protection schemes, reactive power capability and power control requirements for interconnection of the RESs to the smart grid systems. The first findings of this dissertation verified that the integration of large RESs become more promising from the energy-saving, and downsizing perspective by introducing a resistive superconducting fault current limiter (SFCL) as a self-healing equipment. The proposed SFCL decreased the activation of the conventional control scheme for the wind power plant (WPP), such as dc braking chopper and fast pitch angle control systems, thereby increased the reliability of the system.
A static synchronous compensator (STATCOM) has been proposed to assist with the uninterrupted operation of the doubly-fed induction generators (DFIGs)-based WTs during grid disturbances. The key motivation of this study was to design a new computational intelligence technique based on a multi-objective optimization problem (MOP), for the online coordinated reactive power control between the DFIG and the STATCOM in order to improve the low voltage ride-through (LVRT) capability of the WT during the fault, and to smooth low-frequency oscillations of the active power during the recovery. Furthermore, the application of a three-phase single-stage module-integrated converter (MIC) incorporated into a grid-tied photovoltaic (PV) system was investigated in this dissertation. A new current control scheme based on multivariable PI controller, with a faster dynamic and superior axis decoupling capability compared with the conventional PI control method, was developed and experimentally evaluated for three-phase PV MIC system. Finally, a study was conducted based on the framework of stochastic game theory to enable a power system to dynamically survive concurrent severe multi-failure events, before such failures turn into a full blown cascading failure. This effort provides reliable strategies in the form of insightful guidelines on how to deploy limited budgets for protecting critical components of the smart grid systems.
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Acquaviva, Valerie. "ANALYSE DE l'INTEGRATION DES SYSTEMES ENERGETIQUES A SOURCES RENOUVELABLES DANS LES RESEAUX ELECTRIQUES INSULAIRES." Phd thesis, Université Pascal Paoli, 2009. http://tel.archives-ouvertes.fr/tel-00605573.
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L'objectif de ce mémoire est d'analyser le potentiel des installations photovoltaïques connectées au réseau électrique insulaire. Notre étude porte sur trois types de systèmes : l'intégration de centrales PV dans le réseau électrique, l'utilisation de système PV en toiture pour réduire les chutes de tension en bout de ligne et un système à vocation expérimentale. La première partie offre une analyse détaillée de l'apport du photovoltaïque dans le réseau de distribution d'électricité corse. La simultanéité entre la charge et la puissance fournie par une centrale PV y est étudiée ainsi que le taux de disponibilité effectif plus communément appelé TDE. La deuxième partie du mémoire est consacrée au secteur résidentiel et plus particulièrement au renforcement des bouts de lignes électriques via la solution photovoltaïque. En effet, de nombreux foyers connaissent aujourd'hui encore des problèmes de chutes de tension. Pour assurer à l'usager un confort maximal nous avons donc choisi cette solution car l'île possède un ensoleillement remarquable et que la population est de plus en plus sensibilisée à ce type d'énergie. Enfin, le troisième et dernier chapitre représente la partie expérimentale de cette thèse. Elle concerne la modélisation d'un système photovoltaïque de 850 Wc connecté au réseau électrique et situé sur le site universitaire de Vignola. Le suivi et le monitoring ont été assurés depuis sa mise en service en 2000. Une étude des performances et de l'interaction entre le réseau et l'onduleur ont mis en évidence les problèmes de productions liés aux fluctuations du réseau. Des modifications nécessaires des paramètres de l'onduleur ont conduits à des performances très satisfaisantes. . Ce travail qui constitue une étude très large de l'intégration de systèmes PV dans le réseau insulaire corse à travers des applications variées devra être complété par une étude du secteur administratifs et surtout d'une étude plus poussée de la relation réseau/système PV.
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Diop-Ngom, Fatou. "Source de particules neutres monocinétiques : diagnostics spécifiques et étude physique d'une source de Hall en plasma d'argon ou en mixture xénon-argon." Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2025/document.
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Des années 50 à nos jours, la propulsion électrique n'a cessé d'évoluer afin de s'imposer dans le domaine de la propulsion spatiale. Les Propulseurs à effet Hall (PEH) sont principalement utilisés pour des missions de correction de trajectoire ou de maintien en orbite des satellites. Ils délivrent des faisceaux d'ions à forte densité de courant et à faible énergie, ce qui en font de bons candidats potentiels pour d'autres applications comme la microélectronique ou encore les traitements de surfaces. Le xénon est l'ergol le plus utilisé en raison de sa masse élevée et de son faible énergie d'ionisation. Cependant son coût élevé et la difficulté d’approvisionnement motivent la recherche d'alternatives pour le fonctionnement des MEH. C'est dans ce cadre que cette thèse s'est inscrite avec l'idée d'un développement d'une source de faible puissance fonctionnelle en argon. L'amorçage d'une telle décharge n'étant pas immédiat, une démarche progressive qui passe par des décharges de mélange de gaz a été adoptée. Les décharges Xe-Ar se sont révélées très intéressantes pour la compréhension des mécanismes physiques qui régissent les PEH. La caractérisation en vitesse des ions Xe II (par Fluorescence Induite par Laser) associée à l'analyse en énergie par RPA a permis de remonter à des informations utiles sur les zones d'ionisation et d'accélération. Une technique originale de résolution temporelle du RPA basée sur une interruption rapide de la décharge ou sur les oscillations naturelles du courant de décharge, a été développée et a permis l'identification et la quantification des différentes espèces présentes dans le jet d'ions. Grâce aux résultats de l'étude paramétrique des décharges de mélange Xe-Ar, une décharge d'argon pur a pu être amorcée et caractérisée pour la première fois dans un PEH de faible puissanceSince the 50s, electric propulsion has improved in order to establish itself on space propulsion field. The Hall Effect Thruster (HET) are mainly used for trajectory correction or satellites orbit maintaining. The HET provide high current densities and low energy ion beam that making it a good candidate for other applications such as microelectronics or surface treatments. Xenon propellant is most commonly used due to its high atomic mass and its low ionization energy. However, the high cost and difficult supply of xenon, leads to looking for alternative propellant for HET operation. In this context, this PhD thesis had as goal the development of a functional Argon low power source. Argon discharge ignition is not immediate, that why a progressive approach which involves gas mixture discharges was adopted. The Xe-Ar discharge gives very interesting results for the understanding of physical mechanisms governing HET. The characterization of Xe II ions velocity (Laser Induced Fluorescence) associated to the energy analysis by RPA have provided access to useful information on ionization and acceleration areas. An original time resolved RPA technique, based on an ultra-fast discharge interruption or on the discharge current oscillations, has been developed. This technique allows the identification and the quantification of different species present in the ion beam. Thanks to the discharge Xe-Ar study, a pure argon discharge could be initiated and characterized for the first time in a low power HET
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Antonakakis, Marios [Verfasser], Carsten H. [Akademischer Betreuer] Wolters, Michalis Akademischer Betreuer] Zervakis, and Jens [Gutachter] [Haueisen. "The effect of experimental and modeling parameters on combined EEG/MEG source analysis and transcranial electric stimulation optimization of somatosensory and epilepsy activity / Marios Antonakakis ; Gutachter: Jens Haueisen ; Carsten H. Wolters, Michalis Zervakis." Ilmenau : TU Ilmenau, 2021. http://d-nb.info/1239049455/34.
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Gisbert, Rémy. "Optimisation d'une source d'ions à décharge luminsescente pour spectromètre de masse." Grenoble 1, 1992. http://www.theses.fr/1992GRE10118.
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La source d'ions a decharge luminescente en mode continu est utilisee en spectrometrie de masse car elle permet d'obtenir un signal intense, stable et peu discriminatoire. Nous avons etudie les differentes fonctions remplies par cette source (atomisation de l'echantillon et ionisation des produits re-emis) pour analyser son fonctionnement et l'optimiser. L'etude des processus successifs (etablissement et fonctionnement de l'auto-entretien, atomisation par pulverisation de l'echantillon, ionisation des atomes emis dans la decharge) nous a permis de montrer l'importance des parametres suivants: conditions de l'auto-entretien, energie et nature des particules incidentes sur l'echantillon, influence de la pression et de la geometrie de la cellule sur la diffusion des produits de pulverisation. Nous avons developpe des modeles pour simuler le comportement en sensibilite des courants d'ions des especes majeures et definir les conditions d'optimisation du signal. En appliquant ces conclusions, nous avons concu et realise une nouvelle cellule a echantillon plat. Les gains en sensibilite obtenus permettent d'abaisser le seuil des limites de detection de plus d'un ordre de grandeur pour une vitesse d'erosion en profondeur sensiblement reduite, gage d'une meilleure resolution en profondeur pour l'analyse des couches minces. Par ailleurs, nous avons montre l'interet et la faisabilite de la decharge luminescente en mode radiofrequence pour l'analyse des echantillons isolants sur vg9000