Rozprawy doktorskie: „Electricity and electronics”

1

Bouffard, François. "Electricity market-clearing with stochastic security". Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100326.

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In this dissertation we formulate a short-term electricity market-clearing problem with stochastic security criteria. The proposed stochastic security criteria, snake use of probabilistic measures of the expected bald not served or of the loss-of-load probability associated with the random failures of pre-selected sets of generators, lines as well as load disturbances. We snow that by economically penalizing the operation of the market through the associated demand-side costs of involuntary load shedding, the reserve service requirements are determined implicity, thus removing the needs for specifing any a priori reserve requirements. Under this approach, the market-clearing problem gains in flexibility as it can balance file respective expected costs of: (i) the pre-contingency preventive security control actions that include unit commitment, generation and load dispatch as well as reserve scheduling; (ii) the post-contingency corrective actions that deploy reserves through further unit, commitment decisions and load and generation re-dispatch; and, (iii) any post-contingency involuntary load shedding decisions. Case studies illustrate that electricity market-clearing with stochastic security leads to non-negligible economic savings for society; while it can still ensure that consumers benefit from a secure supply of electricity given how they value load shedding.
We derive theoretical results pertaining to the prices of energy and security corresponding to the optimal schedules of the market-clearing process. The key result of this analysis establishes that involuntary load shedding is used after a contingency if and only if the expected marginal costs of scheduling reserves and deploying them are greater than the expected marginal costs of load shedding.
We then extend the model of electricity market-clearing with stochastic security by proposing a short-term electricity market-clearing formulation capable of accounting for non-dispatchable and intermittent power generation sources like wind power. We show how the electricity market-clearing model can take into account uncertainties in the next day/hours wind power generation predictions as well as those of the demand. Also, We demonstrate how the market-clearing formulation can integrate the scheduling of a large-scale centralized energy storage infrastructure.
Finally we define rigorously the concept of the set of umbrella, contingencies for security-constrained optimal power flow problems, a class of power system scheduling problems to which market-clearing with stochastic: security belongs. We propose an identification method to identify the members of this set by making use of the vector norms of the Lagrange multipliers associated with the post-contingency power balance relations. We suggest a heuristic contingency ranking rule based on those vector norms, and we argue that, the proposed identification rule and ranking method can be of use to system operators when specifying reduced sets of contingencies for security-constrained market-clearing problems.

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2

Kockar, Ivana. "Combined poolbilateral operation in electricity markets". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84274.

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This thesis develops a general combined pool/bilateral electricity market model that allows for the simultaneous dispatch of both pool and bilateral trades. The latter are usually negotiated privately among the generators and loads and result in long-term agreements of the order of days to months. The bilateral contracts can be firm or non-firm but in all cases they stand for physical rather than financial obligations to generate a certain amount of power at some bus and to consume it at some other specified point in the power network. The power consumed by the loads that does not come from bilateral contracts is supplied by the pool generation, and is traded in the so-called spot markets whose time horizons can range from a day to as close as one hour.
In this combined market model, all ancillary services including transmission losses and congestion management are supplied by the pool. The market clearing process identifying the scheduled generation levels and the nodal electricity prices (also known as locational marginal prices) is defined by the solution of an optimal power flow which minimizes the total offered generation cost plus any curtailment or non-curtailment costs. This optimization, which is performed centrally by a system operator, simultaneously satisfies the power balance at all the network buses while respecting the power flow limits in all lines including transmission losses. In particular, the market clearing process takes into consideration generation limits imposed by the bilateral contracts, a constraint which as this thesis demonstrates can have a profound impact on the market performance.
The performance of the combined pool/bilateral market is evaluated both technically and financially. The technical performance of a specific market is measured in terms of the pool and bilateral generation levels, by the degree of transmission congestion and by the transmission losses. The financial performance of individual market participants is based on the nodal prices, power transfer rates, as well as on the revenues and expenditures of both generators and loads.
Simulation results indicate that careful coordination of the pool and bilateral trades is essential as certain mixes can force out of merit generator operation, unnecessary transmission congestion, lower generation revenues, and higher consumer payments. This is particularly so if the bilateral contracts are firm.
In order to lessen the consequences of inefficient pool/bilateral mixes, a variation of the combined pool/bilateral market is also examined under which the participants may submit curtailment offers for their firm contracts and non-curtailment bids for their non-firm contracts. The market clearing procedure in this case determines the levels of generation, the nodal prices, as well as the levels of contract curtailment.
Finally, the Aumann-Shapley unbundling procedure is applied to the combined pool/bilateral model with firm contracts. This enables the decomposition of the generation levels into three different service components, namely pool generation, bilateral generation, as well as a generation term supplying ancillary services attributed to the bilateral trades. The unbundling procedure also calculates the corresponding costs associated with these "unbundled" services and allocates them among the different market participants. This service and cost unbundling process is then implemented into a Pay-as-Bid pricing mechanism and compared with the conventional marginal pricing.

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Falcey, Jonathan M. "Electricity Markets, Smart Grids and Smart Buildings". Thesis, University of Denver, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1536975.

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A smart grid is an electricity network that accommodates two-way power flows, and utilizes two-way communications and increased measurement, in order to provide more information to customers and aid in the development of a more efficient electricity market. The current electrical network is outdated and has many shortcomings relating to power flows, inefficient electricity markets, generation/supply balance, a lack of information for the consumer and insufficient consumer interaction with electricity markets. Many of these challenges can be addressed with a smart grid, but there remain significant barriers to the implementation of a smart grid.

This paper proposes a novel method for the development of a smart grid utilizing a bottom up approach (starting with smart buildings/campuses) with the goal of providing the framework and infrastructure necessary for a smart grid instead of the more traditional approach (installing many smart meters and hoping a smart grid emerges). This novel approach involves combining deterministic and statistical methods in order to accurately estimate building electricity use down to the device level. It provides model users with a cheaper alternative to energy audits and extensive sensor networks (the current methods of quantifying electrical use at this level) which increases their ability to modify energy consumption and respond to price signals

The results of this method are promising, but they are still preliminary. As a result, there is still room for improvement. On days when there were no missing or inaccurate data, this approach has R² of about 0.84, sometimes as high as 0.94 when compared to measured results. However, there were many days where missing data brought overall accuracy down significantly. In addition, the development and implementation of the calibration process is still underway and some functional additions must be made in order to maximize accuracy. The calibration process must be completed before a reliable accuracy can be determined.

While this work shows that a combination of a deterministic and statistical methods can accurately forecast building energy usage, the ability to produce accurate results is heavily dependent upon software availability, accurate data and the proper calibration of the model. Creating the software required for a smart building model is time consuming and expensive. Bad or missing data have significant negative impacts on the accuracy of the results and can be caused by a hodgepodge of equipment and communication protocols. Proper calibration of the model is essential to ensure that the device level estimations are sufficiently accurate. Any building model which is to be successful at creating a smart building must be able to overcome these challenges.

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Legbedji, Alexis Motto. "Price schedules coordination for electricity pool markets". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38456.

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We consider the optimal coordination of a class of mathematical programs with equilibrium constraints, which is formally interpreted as a resource-allocation problem. Many decomposition techniques were proposed to circumvent the difficulty of solving large systems with limited computer resources. The considerable improvement in computer architecture has allowed the solution of large-scale problems with increasing speed. Consequently, interest in decomposition techniques has waned. Nonetheless, there is an important class of applications for which decomposition techniques will still be relevant, among others, distributed systems---the Internet, perhaps, being the most conspicuous example---and competitive economic systems. Conceptually, a competitive economic system is a collection of agents that have similar or different objectives while sharing the same system resources. In theory, constructing a large-scale mathematical program and solving it centrally, using currently available computing power can optimize such systems of agents. In practice, however, because agents are self-interested and not willing to reveal some sensitive corporate data, one cannot solve these kinds of coordination problems by simply maximizing the sum of agent's objective functions with respect to their constraints. An iterative price decomposition or Lagrangian dual method is considered best suited because it can operate with limited information. A price-directed strategy, however, can only work successfully when coordinating or equilibrium prices exist, which is not generally the case when a weak duality is unavoidable. Showing when such prices exist and how to compute them is the main subject of this thesis. Among our results, we show that, if the Lagrangian function of a primal program is additively separable, price schedules coordination may be attained. The prices are Lagrange multipliers, and are also the decision variables of a dual program. In addition, we propose a new form of a

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Petoussis, Andreas G. "Supply function equilibrium analysis for electricity markets". Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/1054/.

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The research presented in this Thesis investigates the strategic behaviour of generating firms in bid-based electricity pool markets and the effects of control methods and network features on the electricity market outcome by utilising the AC network model to represent the electric grid. A market equilibrium algorithm has been implemented to represent the bi-level market problem for social welfare maximization from the system operator and utility assets optimisation from the strategic market participants, based on the primal-dual interior point method. The strategic interactions in the market are modelled using supply function equilibrium theory and the optimum strategies are determined by parameterization of the marginal cost functions of the generating units. The AC power network model explicitly represents the active and reactive power flows and various network components and control functions. The market analysis examines the relation between market power and AC networks, while the different parameterization methods for the supply function bids are also investigated. The first part of the market analysis focuses on the effects of particular characteristics of the AC network on the interactions between the strategic generating firms, which directly affect the electricity market outcome. In particular, the examined topics include the impact of transformer tap-ratio control, reactive power control, different locations for a new entry’s generating unit in the system, and introduction of photovoltaic solar power production in the pool market by considering its dependencyon the applied solar irradiance. The observations on the numerical results have shown that their impact on the market is significant and the employment of AC network representation is required for reliable market outcome predictions and for a better understanding of the strategic behaviour as it depends on the topology of the system. The analysis that examines the supply function parameterizations has shown that the resulting market solutions from the different parameterization methods can be very similar or differ substantially, depending on the presence and level of network congestion and on the size and complexity of the examined system. Furthermore, the convergence performance of the implemented market algorithm has been examined and proven to exhibit superior computational efficiency, being able to provide market solutions for large complex AC systems with multiple asymmetric firms, providing the opportunity for applications on practical electricity markets.

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Liu, Xuezhi. "Combined analysis of electricity and heat networks". Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/57830/.

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The use of Combined Heat and Power (CHP) units, heat pumps and electric boilers increases the linkages between electricity and heat networks. In this thesis, a combined analysis was developed to investigate the performance of electricity and heat networks as an integrated whole. This was based on a model of electrical power flow and hydraulic and thermal circuits together with their coupling components (CHP units, heat pumps, electric boilers and circulation pumps). The flows of energy between the electricity and heat networks through the coupling components were taken into account. In the combined analysis, two calculation techniques were developed. These were the decomposed and integrated electrical-hydraulic-thermal calculation techniques in the forms of the power flow and simple optimal dispatch. Using the combined analysis, the variables of the electrical and heat networks were calculated. The results of the decomposed and integrated calculations were very close. The comparison showed that the integrated calculation requires fewer iterations than the decomposed calculation. A case study of Barry Island electricity and district heating networks was conducted. The case study examined how both electrical and heat demands in a self-sufficient system (no interconnection with external systems) were met using CHP units. A solution was demonstrated to deliver the electrical and heat energy from the CHP units to the consumers through electrical and heat networks. The combined analysis can be used for the design and operation of integrated heat and electricity systems for energy supply to buildings. This will increase the flexibility of the electricity and heat supply systems for facilitating the integration of intermittent renewable energy.

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7

Chua, Cheong Wei 1975. "A stochastic pool-based electricity market simulator /". Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31045.

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In Part I, two pool-based electricity market models are compared in terms of their economic impact on the market participants, the Lossless Economic Dispatch (LED) and the Optimal Power Flow (OPF). The OPF is shown to be economically more efficient, more accurate and more equitable to the participants.
In Part II, a stochastic electricity market simulator (SEMS) is designed using elements of Monte Carlo methods and game theory. Each generator is assumed to operate in a stochastic manner, according to a bid strategy composed of a set of pre-established bid instances and a corresponding set of bid probabilities. The Pool dispatches power and defines prices according to either the LED or OPF models from Part I. Generators can update their bidding strategies according to a profit performance index reflecting their degree of risk tolerance, Chicken (risk averse), Average, and Cowboy (risk taker). SEMS can predict issues such as unintended collusion, as well as to evaluate bidding strategies.

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El, Khatib Sameh. "Oligopolistic electricity markets under cap-and-trade and carbon tax". Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103522.

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Global warming is one of the most alarming phenomena facing our planet today. There is a general consensus among scientists that in order to slow down the heating of the Earth's oceans and atmosphere, human-induced greenhouse gases (GHG) should be regulated. Being a major GHG producer, the electricity industry's emissions should form part of any global emission regulation initiative. In this thesis we develop an original equilibrium model for a cap-and-trade emission regulation scheme, as well as one for a carbon tax-based scheme, both applied to an oligopolistic electricity market. The models account for the strategic behavior of power generating companies under emission regulation and explicitly illustrate how this behavior is influenced by the design of the scheme. Both models respect the electricity sector's emission targets over a commitment interval, typically a year, while accounting for the effect of these targets (and regulation scheme) on the hourly operation of electricity markets given hourly variations in system demand. Furthermore, in response to the global inclination to employ an auction-based approach to allocate emission permits under cap-and-trade, we develop a novel auction for commitment interval emission permits within the electricity sector, modeled as a tri-level mathematical problem with equilibrium constraints (MPEC). The resulting permit allocation is not only influenced by bids from power generating companies, but also maximizes social-welfare by accounting for the effect of this allocation on the strategic behavior of generating companies and on the hourly operation of electricity markets. Groundwork results suggest that both schemes have significantly varying effects on market power and profits, effects that contest some preconceived ideas about both regulation schemes. These results suggest that the carbon tax structure proposed in this thesis is the recommended emission regulation scheme for an oligopolistic electricity market.
Le réchauffement planétaire est un des phénomènes les plus alarmants des nos jours. Il existe un consensus entre les scientifiques qu'afin de ralentir le réchauffement des océans et de l'atmosphère, les émissions de gaz à effet de serre anthropique (GES) devraient être réglementées. Étant le secteur de l'électricité un grand producteur de GES, ses émissions devraient faire partie de toute initiative globale de réglementation. Dans cette thèse, nous concevons et vérifions deux régimes de réglementation des émissions dans le contexte des marchés de l'électricité, un fondé sur le plafonnement et l'échange (CAT) et l'autre sur la taxe carbone (CTX). En outre, nous comparons la capacité des deux régimes pour atteindre les objectifs de règlementation d'émissions sujets aux facteurs de difficulté susmentionnés. Sous CAT, tout d'abord nous remplaçons la conception d'un marché de l'électricité oligopolistique horaire typique par un marché conjoint d'électricité et d'échanges de permis d'émission. Ce double marché tient compte des manipulations du marché de la part des Gencos (Genco gaming) pour tirer parti des coûts de production horaires, des intensités d'émissions des générateurs, des allocations horaires de permis auto-réparties par les Gencos, du droit d'échange de permis avec le marché externe et de l'élasticité de la demande. En outre, sous CTX, nous remplaçons le marché de l'électricité horaire par une version qui inclut une pénalité basée sur une taxe carbone. Ici, la manipulation du marché par les Gencos tire parti des coûts de production horaires, des intensités d'émission des générateurs, de l'élasticité de la demande et de la pénalité imposée par la taxe carbone. En outre, sous CAT, nous développons deux nouvelles approches pour partager parmi les Gencos le plafond sur les émissions imposé sur le secteur de l'électricité pendant l'intervalle d'engagement spécifié: (a) Les Gencos reçoivent gratuitement les permis d'un planificateur social (SP). Ceci est basé sur la maximisation du bien être sociale (SW) pour l'intervalle d'engagement entier, tout en comptabilisant les effets de ces permis sur le fonctionnement horaire du marché double de l'électricité et des permis ; (b) Les Gencos sont accordés de permis sur la base d'une vente aux enchères où, en plus d'optimisant le SW, le SP accepte des soumissions des Gencos à fin d'influencer l'attribution des permis, et où les Gencos payent pour leurs permis au prix de compensation de la vente aux enchères. En revanche, au titre du régime CTX, il n'y a aucun plafond d'émissions explicite. Plutôt, le plafond souhaité est atteint implicitement à travers une pénalité fiscale horaire, dont les paramètres sont calculés en maximisant le SW sur l'intervalle d'engagement. Ce calcul représente l'effet du taux de carbon horaire qui en résulte de la maximisation sur la manipulation strategique du marché par les Gencos et sur l'équilibre correspondant du marché oligopolistique. Enfin, la thèse offre une comparaison analytique et numérique approfondie de CAT et CTX sous différents scénarios. Les résultats de base suggèrent que les deux approches ont des sensiblement différents effets sur le marché et les profits, des effets qui défient certaines idées préconçues sur le règlement d'émissions. Ces résultats suggèrent que, dans l'attente d'autres études, nous concluons que la structure de taxe carbone développée dans cette thèse est le régime de réglementation d'émissions recommandée pour un marché de l'électricité oligopolistique.

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Bennett, Steven. "Charge and momentum in quantum electromechanical systems". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95081.

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We address theoretical questions in quantum nanoelectromechanical systems. These are systems where a mechanical oscillator is coupled to a conductor in which single electrons or the quantum coherence of electrons plays an important role. The interplay of quantum electronics with the motion of a relatively macroscopic object provides a way to probe both the mechanics and the electronics with extraordinary sensitivity. We address three problems based on monitoring either the electronic or mechanical component to measure quantum properties of the coupled system. First, we study the full charge transfer statistics and correlations in a tunnel junction coupled to a mechanical oscillator, viewing the current measured through the junction as a detector of the oscillator position. We find several surprising results that are not obtained in a study of only the average and variance of tunneled charge. Even when the oscillator is weakly coupled to the tunnel junction, it can lead to highly non-Gaussian tunneling statistics; moreover, non-Gaussian correlations between the oscillator motion and transferred charge show that the backaction of tunneling electrons on the oscillator cannot be fully described as coupling the oscillator to an effective thermal bath. Second, we use a general scattering approach to study the backaction of a quantum point contact position detector on a mechanical oscillator. Our results remain valid far from the tunneling limit, an important experimental regime and where previous calculations of backaction break down. We obtain the backaction damping and heating directly in terms of the scattering matrix, and find that not only the transmission but also the scattering phases play an important role. Finally, we study a quantum dot capacitively coupled to an oscillating cantilever. In this case, the damping of the mechanical oscillator is monitored to measure quantum electronic properties of the dot. For weak electromechanical coupling, we f
Nous abordons des questions théoriques dans le domaine des systèmes quantiques nanoélectromécaniques. Ceux sont les systémes où un oscillateur mécanique est couplé à un conducteur dans lequel les électrons individuels ou la cohérence quantique des électrons joue un rôle important. L'interaction entre un dispositif électronique dans le régime quantique avec le mouvement d'un objet macroscopique fournit un moyen de sonder à la fois les degrés de liberté méchaniques et électroniques avec une sensibilité extraordinaire. Nous réglons trois problèmes basées sur la surveillance soit la composante électronique ou mécanique pour mesurer les propriétés quantiques du systéme couplé. D'abord, nous étudions les statistiques complète de transfert de charge et les corrélations dans une jonction tunnel couplé à un oscillateur mécanique, en traitant le courant mesuré à travers la jonction comme un détecteur de la position de l'oscillateur. Nous trouvons plusieurs résultats surprenants qui ne sont pas obtenus dans un étude de seulement la moyenne et la variance de la charge qui tunnel. Même lorsque l'oscillateur est faiblement couplé à la jonction tunnel, il peut produire des statistiques fortement non-Gaussian; d'ailleurs, les corrélations non-Gaussian entre le mouvement de l'oscillateur et la charge transférée montrent que le backaction associé avec l'effet tunnel des électrons sur l'oscillateur ne peut être entièrement décrit du point de vue du couplage de l'oscillateur à un bain thermique effectif. Deuxièmement, nous utilisons une approche générale pour étudier le backaction quantique sur un oscillateur mécanique causé par un détecteur de position, comprenant un point contact quantique. Nos résultats restent applicables loin de la limite de tunnel; un régime expérimental important et où les calculs précédents du backaction ne s'appliquent pas. Nous obtenons le backaction d'amortisseme

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Laroche, Dominique. "Coulomb drag in vertically-integrated one-dimensional quantum wires". Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121182.

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Understanding the physics taking place in coupled one-dimensional systemsis one of the many challenges of modern day condensed matter physics and nanoelectronics. While experimental studies in coupled quantum wires have recently confirmed some of the most striking predictions of Luttinger liquid theory such as spin-charge separation and charge partitioning, much remains to be done prior a complete understanding of one-dimensional physical phenomenons is achieved, especially in the field of one-dimensional Coulomb drag. In this thesis, I report our experimental study of one-dimensional Coulomb drag between quantum wires coupled at the nanoscale. The quantum wires are coupled in a vertical geometry, allowing the wires to be separated by a hard barrier only 15 nm wide and providing us with the possibility to study Coulomb drag in a regime never achieved previously. Our study of the 1D subband dependency of Coulomb drag shows an oscillation of the drag resistance (RD) with 1D subband occupancy. Peaks in the drag signal are observed concomitant with the opening of 1D subbands in either wire, regardless of 1D subband alignment between the wires, and a novel high electronic density re-entrant negative regime for RD is observed. These findings are not fully understood within the current theoretical momentum-transfer models for Coulomb drag between quantum wires. However, some of the predictions of a charge-fluctuation induced model for 1D Coulomb drag in mesoscopic circuits are consistent with our observations and raise questions as to whether mesoscopic physics play an important role in one-dimensional Coulomb drag. The temperature dependence of the drag resistance is also presented in the one-dimensional regime where both wires have no more than a single 1D subband occupied. As the temperature is reduced below the Fermi temperature TF , a decrease in RD and a subsequent upturn is observed in three different devices at T* ∼ 1.6 K, flagging a regime where RD increases with decreasing T (verified down to ∼ 75 mK). This upturn in the drag resistance andthe diverging drag resistance at the lowest temperatures is consistent with expectations from Tomonaga-Luttinger liquid models of 1D quantum wires ,potentially validates models including forward scattering corrections and is a strong sign that interaction effects and momentum-transfer play an important role in one-dimensional Coulomb drag. A crucial step for the future of electronic nano-devices is the development of doped shallow two-dimensional electron gases (2DEGs). In an effort towards this goal, we have also studied scattering mechanisms in shallow 2DEGs in parallel to our Coulomb drag experiment. In this endeavor, we achieved the fabrication of 2DEGs as shallow as 60 nm deep with a mobility in excess of 1×10^5 cm^2/ V · s and determined that scattering of intentional remote charged impurities is the dominant scattering mechanism in samples 130 nm deep and shallower.
La compréhension de la physique prenant place dans les sysèmes unidimensionels couplés est un des nombreux défis auxquels la physique de la matière condensée moderne et la nano-électronique sont confrontées. En dépit du fait que certaines études portant sur des fils quantiques couplés aient confirmé certaines des prédictions les plus fascinantes de la théorie des liquides de Luttinger tels que la séparation des spins et des charges ainsi que la partition des charges, beaucoup reste à faire avant qu'une compréhension complète des phénomènes prenant naissance dans les systèmes unidimensionels ne soit atteinte, surtout en ce qui a trait à la traînée de Coulomb unidimensionnelle. Dans cette thèse, nous rapportons l'étude expérimentale de la traînée de Coulomb unidimensionnelle entre des fils quantiques couplés à l'échelle nanométrique. Les fils quantiques sont couplés dans une géométrie verticale permettant aux fils d'être séparés par une barrière large de seulement 15 nm, nous donnant ainsi l'occasion d'étudier la traînée de Coulomb dans un régime jamais exploré auparavant. Les résultats de notre étude de la dépendance de la traînée de Coulomb avec le niveau d'occupation des sous-bandes unidimensionnelles des fils quantiques montrent une oscillation de la résistance de la traînée de Coulomb (RD) en fonction du nombre de sous-couches occupées dans les fils quantiques. Des maximums dans RD sont observés simultanément à l'ouverture de sous-bandes unidimensionnelles dans l'un ou l'autre des fils et un nouveau régime de RD négatif et résurgent est observé à haute densité. Ces observations ne sont pas complètement expliquées par les modèles actuels expliquant la traînée de Coulomb par un transfer de quantité de mouvement. Toutefois, certaines prédictions des modèles expliquant l'émergence de la traînée de Coulomb unidimensionnelle par un échange de fluctuations sont en accord avec nos résultats et soulèvent des doutes à savoir si la physique mésoscopique joue un role dans l'émergence de la traînée de Coulomb unidimensionnelle. La dépendence en température de la résistance de la traînée de Coulomb est également présentée dans le régime unidimentionel où les fils ont au plus une seule sous-bande de populée. Alors que la température est abaissée sous la température de Fermi, une diminution de RD est observée, suivie d'un renversement de cette tendence. Ce renversement est observé dans trois dispositifs distincts à une température T* ∼ 1.6 K et marque une transition vers un régime où RD augmente alors que la température diminue (mesuré jusqu'à ∼75 mK). La présence de ce renversement et d'une divergence de RD à basse température est en accord avec les prédictions de la théorie des liquides de Tomonoga-Luttinger pour des fils quantiques unidimentionels, confirment potentiellement les modèles incluant des corrections pour des faibles valeurs de transfer de quantité de mouvement et suggèrent fortement que les interactions et le transfer de quantité de mouvement sont importants dans l'émergence de la traînée de Coulomb unidimensionnelle. Une étape cruciale pour le futur développement de nano-dispositifs électroniques est la création de puits quantiques peu profonds et dopés. Dans l'espoir d'atteindre cet objectif, nous avons étudié les mécanismes de diffusion dans des puits quantiques peu profonds en parallèle à notre étude de la traînée de Coulomb unidimensionnelle. Au cours de cet effort, nous sommes parvenus à fabriquer des puits quantiques situés seulement 60 nm sous la surface avec une mobilité supérieure à 1 × 10^5 cm^2/ V · s et nous avons déterminé que ladiffusion par les impuretés ionisées volontairement insérées dans la structure est le mode de diffusion dominant dans les puits quantiques profonds de moins de 130 nm.

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Baertlein, Brian Allen. "Frequency response of E polarized sources over a lossy earth in the presence of two-dimensional shielding structures". Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184605.

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Electromagnetic shielding by thin, perfectly conducting, two dimensional cylindrical shells over a lossy earth is investigated. The temporal frequency response of the exterior field due to a line source within the shell is computed for a shell described by a three sided, rectilinear structure whose opening faces the earth. The formulation allows shells of arbitrary cross-sectional shape to be analyzed. The earth is modeled as a homogeneous half-space with a planar boundary and frequency dependent electromagnetic properties. Two solution techniques are presented. In the first, the induced current is obtained through a numerical solution of the electric field integral equation (EFIE) at many discrete frequencies. It is found that the applicability of this formulation is limited since in the case of effective shielding, fields calculated from the EFIE are very sensitive to numerical errors. In the second technique the EFIE is again solved for the currents induced on the shell. The induced currents are used to calculate the electric field in the aperture which is used to solve a combined-source integral equation (CSIE) for the external fields. It is found that the CSIE does not suffer from the numerical ill-conditioning that plagues the EFIE, and is well behaved at all frequencies. Numerical results are presented which indicate that the shell-earth combination is very effective in shielding the internal source. Interior modes are weakly transmitted to the interior for the case of a purely dielectric earth. For a lossy half-space the resonances of the closed shell are enhanced. The related topic of scattering by perfectly conducting objects over a lossy earth is addressed. Numerical formulations for the solution of the integral equations are presented which deal with several troublesome aspects of the problem, including the incorporation of the correct edge singularities.

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12

Wang, Jing. "A study of demand-side reserve offers in joint energyreserve electricity markets". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19601.

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This thesis proposes and studies an electricity market model that includes demand-side reserve offers. The energy and reserves from both supply and demand side are scheduled and dispatched in a joint auction through a mixed-integer optimization program. Among the advantages of this more general electricity market, due to the extra flexibility introduced by the demand-side reserve offers, the consumers' profits increase while themarket power of the generators is reduced. The behavior of this type of market is simulated and analyzed on the 24-bus IEEE Reliability Test System using the mixed-integer linear program, CPLEX.

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Okonkwo, Christopher Ndubuisi. "Electricity Sector Reform: Sourcing and Cost Management of Electricity for Steel Manufacturing in Nigeria". ScholarWorks, 2016. https://scholarworks.waldenu.edu/dissertations/3056.

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In 2014, Lazard levelized cost of energy analysis model priced diesel powered systems at $0.225 – $0.404/KWh and a range of $0.165 – $0.242/KWh for gas-powered systems. The model gave a range of $0.28 – $0.33/kWh for diesel and a range of $0.14/kWh – $0.16/kW for gas ﬁred. Nigeria has an abundance of gas reserves, but heavy gas ﬂaring by oil companies perpetuates power failure across Nigeria. What has resulted is an unreliable electricity infrastructure and a high cost of alternative energy. The Electricity Power Sector Reform Act of 2005 started the reform process. Guided by decision theory, the purpose of this multiple case study was to understand the perceptions of business leaders at the steel manufacturing businesses on how the use of multiple supply sources of electricity might lead to survival, growth, and profitability. The study’s population consisted of 10 steel manufacturing companies in the Southwest region of Nigeria. The data were collected via semistructured interviews with the leaders who source energy, a review of archival records, and observations of company officials placing orders from multiple sources. The van Kaam method of data analysis generated 5 themes: cost of generating electricity and the investment in alternative sources of energy, erratic power supply and its impact on the steel production industry, quality of power supply relative to the capacity and its impact on profits, electricity factor in the steel production process, and use of multiple sources. These findings may contribute to social change by increasing employment opportunities for members of the local community, who will have an enhanced understanding about steel and seize entrepreneurial opportunities.

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14

El, Khatib Sameh. "An iterative approach to negotiating bilateral contracts in mixed pool/bilateral electricity markets /". Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82482.

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In mixed pool/bilateral electricity markets, participants can sign bilateral contracts several weeks or months in advance of the pool market-clearing. Any uncommitted generator capacity may be sold to the pool and any remaining un-serviced demand is met through the pool, both at the pool spot price.
In this thesis, in contrast to financial rights, we consider only physical bilateral contracts, where the generator and load are obliged to produce and consume power levels at least equal to the stipulated bilateral amount.
Bilateral contracts have the advantage that they satisfy at least part of the needs of both buyers and sellers at a predictable price instead of relying solely on the uncertain real-time spot price at the pool market-clearing time. However the risk of signing a bilateral contract is that it commits the partners to a price that may be disadvantageous compared to the pool spot price. Thus, if the spot price turns out to be lower than the bilateral price, then the seller comes out ahead while the buyer loses compared to the alternative of having traded solely in the real-time market. Conversely, if the spot price turns out to be higher than the bilateral price, then the seller loses out while the buyer benefits compared to having traded solely in the real-time market.
Here we propose a systematic bilateral negotiating approach between a generator and load in mixed pool/bilateral markets. Under this approach the generator and load respond rationally to a stream of bilateral bids/counter-bids and offers/counter-offers considering their respective expected benefits while accounting for the risks incurred by the uncertainty of pool spot price prediction. This negotiating approach is tested numerically and shown to be a valuable and practical tool in arriving at a mutually beneficial and risk-tolerable bilateral contract.

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15

Gomez, Quiles Catalina. "Price and resource-related risk of the wind power business in electricity markets". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32554.

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A generalized mathematical model is developed that allows the quantification of the economic risk of the investment in a wind farm under the two most common revenue options defined by how the output of the wind farm is paid to the owner: a) at a pre-established fixed-rate or, b) at the hourly electricity market prices. Sensitivities are also characterized in order to determine the influence of various market and resource-related parameters on the variability of the annual revenue and the corresponding economic risk. Particular to the fixed-rate revenue option, the developed model allows the owner of the wind farm to determine the minimum necessary rate to meet a pre-established risk-return requirement. The model is validated using actual wind power output and electricity market datasets. Understanding the sources of risk in any investment is crucial for the development of proper hedging strategies.
Dans ce travail, un modèle mathématique généralisée est développé qui permet la quantification du risque économique de l'investissement dans un parc éolien dans le cadre des deux options de rémunération les plus communes, définies par la manière dont la production du parc éolien est rémunérée au propriétaire : a) à un tarif fixe pré-établi ou, b) au prix horaire du marché d'électricité. Des sensibilités sont aussi caractérisées afin de déterminer l'influence de divers paramètres reliés au marché d'électricité et à la ressource éolienne sur la variabilité des recettes annuelles et ses risques économiques. Dans l'option de recette à tarif fixe, le modèle développé permet au propriétaire du parc éolien de déterminer le tarif minimal nécessaire pour répondre à une exigence de risque pré-établie. Le modèle est validé en utilisant des données réelles de production d'énergie éolienne et du marché d'électricité. La connaissance des sources de risque dans un investissement est cruciale pour la conception des stratégies de couverture propres.

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Drysdale, Brian. "Demand side management : flexible demand in the GB domestic electricity sector". Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/69859/.

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In order to meet greenhouse gas emissions targets, the Great Britain (GB) future electricity supply will include a higher fraction of non-dispatchable generation, increasing opportunities for demand side management (DSM) to maintain a supply/demand balance. Domestic electricity demand is approximately a third of total GB demand and has the potential to provide a significant demand side resource. An optimization model of UK electricity generation has been developed with an objective function to minimize total system cost (£m/year). The models show that dispatchable output falls from 77% of total output in 2012 to 69% in 2020, 41% in 2030 and 28% in 2050, supporting the need for increased levels of future DSM. Domestic demand has been categorised to identify flexible loads (electric space and water heating, cold appliances and wet appliances), and projected to 2030. Annual flexible demand in 2030 amounts to 64.3TWh though the amount of practically available demand varies significantly on a diurnal, weekly and seasonal basis. Daily load profiles show practically available demand on two sample days at three sample time points (05:00, 08:00 and 17:30) varies between 838MW and 6,150MW. Access to flexible demand for DSM purposes is dependent on the active involvement of domestic consumers and/or their acceptance of appliance automation. Analysis of a major quantitative survey and qualitative workshop dataset shows that 49% of respondents don’t think very much or not at all about their electricity use. This has implications for the effectiveness of DSM measures which rely on consumers to actively modify behaviour in response to a signal. Whilst appliance automation can be a practical solution to realising demand side potential, many consumers are reluctant to allow remote access. Consumers are motivated by financial incentives though the low value of individual appliance consumption limits the effectiveness of solely financial incentives. A range of incentives would be required to encourage a wide cross-section of consumers to engage with their electricity consumption.

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Vita, Vasiliki. "Electricity distribution networks' analysis, with particular references to distributed generation and protection". Thesis, City University London, 2016. http://openaccess.city.ac.uk/15180/.

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Electric power systems have served well the consumers need for continuous, uninterrupted power supply of good quality and at the minimum possible cost. However, nowadays, the worldwide increasing demand on electric power, coupled with governmental policy changes towards “green” energy and emissions reduction have led to significant changes in the electric power generation. These changes have introduced many serious issues and problems to the electric power systems and although they have been efficiently addressed in the past years, now they need to be restudied and reanalysed taking into consideration all new developments. Distributed generation (DG), constitutes one of the most important developments in modern electric power systems and introduced many benefits as well as drawbacks. DG units are connected to the electric power system near load centres, thus, directly to the distribution network. DG units are larger in number than the more massive conventional power stations and are linked to the introduction of bidirectional power flow. As a result, the configuration of the traditional electric power systems and the networks’ operation have been prominently altered over the last years as soon as DG was introduced into the electric network. This progress has offered many challenges that need to be addressed such as those in terms of control and protection of electric power systems and particularly of distribution networks. The current PhD Thesis attempts to offer a contribution to the electricity distribution networks’ studies with particular reference to distributed generation and protection. In particular, the problems and the issues arising from the installation of DG units in distribution networks are studied. Research on the methods for improving voltage profiles and for reducing real and reactive power losses in distribution networks caused by DGs installation is conducted. Moreover, a decision making algorithm is developed and proposed for selecting the optimum size and location of DG in distribution networks. Furthermore, a new technique based on syntactic pattern recognition for the identification of power system signals used by protective relays is developed in an effort to contribute in the deterrence and reduction of faults. Finally, extensive studies in a distribution network have been conducted, with and without DGs, which aimed to identify the influence of several important parameters in the network’s lightning performance and with its main goal the limitation of lightning faults.

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Eskandari, Torbaghan Mehran. "A risk based approach for trading renewable electricity". Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6537/.

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Growing energy demand and climate change due to increasing CO2 emissions are two major global issues. The development of Supergrids, which involves connecting national energy supply grids together via interconnections, has been proposed as a measure to overcome these challenges. Supergrids arguably aid the implementation of other measures such as managing demand and development of renewable sources of energy, whilst it has its own benefits, perhaps, the most important one being its economic efficiency in comparison with generating electricity. A key challenge for developing Supergrids is finding the most suitable countries with which to make an interconnection. This doctoral research aims to develop a risk-based theoretical framework for selecting the most appropriate country (ies) with which to make grid interconnections and trade renewable electricity. Quantitative risk analysis technique is used to compare candidate countries by taking into the account the various risks associated with the construction and maintenance of interconnections. The risks include: social, technical, economic, environment and political aspects. The framework is demonstrated using the UK as a case study.

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19

Frem, Bassam. "The effects of demand uncertainty on strategic gaming in the merit-order electricity pool market". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86969.

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In a merit-order electricity pool market, generating companies (Gencos) game with their offered incremental cost to meet the electricity demand and earn bigger market shares and higher profits. However when the demand is treated as a random variable instead of as a known constant, these Genco gaming strategies become more complex.
After a brief introduction of electricity markets and gaming, the effects of demand uncertainty on strategic gaming are studied in two parts: (1) Demand modelled as a discrete random variable (2) Demand modelled as a continuous random variable.
In the first part, we proposed an algorithm, the discrete stochastic strategy (DSS) algorithm that generates a strategic set of offers from the perspective of the Gencos' profits. The DSS offers were tested and compared to the deterministic Nash equilibrium (NE) offers based on the predicted demand. This comparison, based on the expected Genco profits, showed the DSS to be a better strategy in a probabilistic sense than the deterministic NE.
In the second part, we presented three gaming strategies: (1) Deterministic NE (2) No-Risk (3) Risk-Taking. The strategies were then tested and their profit performances were compared using two assessment tools: (a) Expected value and standard deviation (b) Inverse cumulative distribution. We concluded that despite yielding higher profit performance under the right conjectures, Risk-Taking strategies are very sensitive to incorrect conjectures on the competitors' gaming decisions. As such, despite its lower profit performance, the No-Risk strategy was deemed preferable.
Dans le marché d'électricité mutuel, gouverné par l'ordre de mérite, les compagnies de production (Gencos) jouent avec leurs coûts différentiels offerts pour gagner une plus grande part du marché ainsi qu'un profit plus élevé, tout en satisfaisant la demande des consommateurs. Toutefois, lorsque la demande est considérée comme une variable aléatoire au lieu d'une constante définie, les stratégies de jeu des Gencos deviennent beaucoup plus difficiles à gérer.
Après une introduction sur les marchés d'électricité et la théorie des jeux, nous étudions les effets de l'incertitude de la demande sur les stratégies de jeu en deux parties : (1) la demande est traitée comme une variable aléatoire discrète (2) la demande est traitée comme une variable aléatoire continue.
Dans la première partie nous proposons un algorithme, l'algorithme de la stratégie stochastique discrète (DSS) qui nous donne un ensemble d'offres stratégiques visant de meilleurs profits pour les Gencos. Les offres calculées par l'algorithme DSS ont été testées et comparées aux offres de l'algorithme d'équilibre Nash (NE) non-stochastique, basé sur la demande prévue. Utilisant les résultats de cette comparaison où on évalue l'espérance mathématique des profits des Gencos, nous avons conclu que la stratégie DSS donne un meilleur rendement stochastique que celle du NE non-stochastique
Dans la deuxième partie de l'étude nous avons présenté trois stratégies de jeu : (1) Le NE non-stochastique (2) Sans-Risque (3) Avec-Risque. Les stratégies ont été testées et leurs performances vis-à-vis des profits des Gencos furent comparées utilisant deux outils d'évaluation : (a) Espérance mathématique et écart-type (b) Fonction de répartition inverse. Nous avons conclus que, malgré leurs performances plus élevées vis-à-vis des profits aves les conjectures correctes, les stratégies Avec-Risque sont très sensibles aux erreurs dans les conjectures à propos des décisions de jeu des concurrents. De ce fait, même avec une performance moins favorable, la stratégie Sans-Risque fut considérée préférable.

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Qadrdan, Meysam. "Modelling of an integrated gas and electricity network with significant wind capacity". Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/24178/.

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The large scale integration of wind generation capacity into an electricity network poses technical as well as economic challenges. In this research, three major challenges introduced by wind including non-correlated power output from geographically dispersed wind farms, wind variability and wind uncertainty were studied. In order to address each of the aforementioned challenges an appropriate modelling approach and case studies were used. The impacts of power output from dispersed wind farms on the Great Britain transmission reinforcement were studied using an optimal DC load flow combined with a power generation model. It was shown that Western and Eastern HVDC links play a crucial role to bypass the Scotland to England transmission bottleneck. The impacts of wind variability on the GB gas and electricity network were investigated through application of the Combined gas and Electricity Network (CGEN) Model. Additional gas storage capacity was shown to be an efficient option to compensate for wind variability. Two-stage and multi-stage stochastic programming models were developed to examine the impact of wind forecast uncertainty on the GB electricity and gas networks. Stochastic modelling approaches were shown to be efficient methods for scheduling and operating the system under wind uncertainty. The key contributions of this thesis are the investigation of the impacts of wind generation variability on the gas network, and development of twostage and multi-stage stochastic programming models of integrated gas and electricity network.

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Ren, Yongjun 1970. "A comparison of pool cost and consumer payment minimization in electricity markets /". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32972.

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This thesis deals with market rules that define the price and the generation schedule in electricity markets. The research has focused on three approaches: Pool Cost Minimization (PCM) with marginal pricing, Consumer Payment Minimization (CPM), and mixed Pool Cost/Consumer Payment Minimization (PCM/CPM). Each method is examined from the perspective of the solution characteristics and the relevant economic principle, together with numerical examples. Especially in the CPM method, several fundamental theoretical results are obtained regarding the nature of the minimum consumer payment and the corresponding generation schedule. In addition, some generator bidding strategies are studied with respect to PCM and CPM so as to identify how Gencos can obtain a competitive advantage.

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Smith, Neil Ronald. "USING ELECTRON BEAM LITHOGRAPHY TO MAKE ELECTRODES FOR SINGLE MOLECULE ELECTRONICTS". Miami University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=miami1123213432.

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23

Gerrits, Brian D. "An analysis of competencies required in electricity and electronics by automotive technicians in the Chippewa Valley". Online version, 2008. http://www.uwstout.edu/lib/thesis/2008/2008gerritsb.pdf.

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Howells, Bryn. "Studies of spin-orbit coupling phenomena in magnetic semiconductors". Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/29005/.

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Hard disk drives (HDDs) have been the dominant secondary memory device in computing for over 50 years, while more recently magnetoresistive random access memory (MRAM) has emerged as a candidate for primary computing memory. Both HDDs and MRAM store information in the polarity of a magnetic layer, which is written and read by non relativistic mechanisms. There is now gathering interesting in using relativistic mechanisms whose origins lie with spin-orbit coupling (SOC) for MRAM writing because of potential benefits in terms of scalability, device design, and efficiency. This thesis investigates the fundamental physics of SOC phenomena that can write (spin-orbit torque (SOT), Neel order SOT) or read (anisotropic magnetoresistance (AMR), magnetic gating) the magnetic state by the application of electrical current. These phenomena are studied in ferromagnetic and antiferromagnetic semiconducting materials that offer a relevant electrical conductivity for integration into commercial electronic devices. Effective magnetic fields which parametrise the SOT phenomenon are measured in the diluted magnetic semiconductor (Ga,Mn)As using a technique based upon experimental planar Hall effect measurements and analytical fitting with a free energy equation for coherent magnetization rotation. It is found that effective magnetic fields which originate from Dresselhaus SOC increase in magnitude with increasing temperature, whereas those originating from Rashba SO have no significant temperature dependence within experimental uncertainty. The size of the measured effective fields per unit of current density, as well as the ratio of Dresselhaus to Rashba effective field magnitudes averaged over all temperatures are comparable to previous experimental measurements. Sb-based diluted magnetic semiconductors (Ga,Mn (As0.9,Sb0.1) and (Ga,Mn)Sb are characterised by magnetic and transport measurements. The Curie temperature (Tc) of (Ga,Mn)(As0.9,Sb0.1) increases from 28K to 55K upon sample annealing. The Tc of as-grown (Ga,Mn)Sb is found to be 34K, and in contrast to (Ga,Mn)(As0.9,Sb0.1) does not change upon annealing, indicating a lack of interstitial Mn in (Ga,Mn)Sb. Field rotation transport measurements for current along various crystalline directions reveal significant crystalline and non crystalline contributions to the AMR of both as-grown and annealed (Ga,Mn)(As0.9,Sb0.1). An anomalous temperature dependence of the AMR of the annealed (Ga,Mn (As0.9,Sb0.1) sample for current along the [110] crystalline direction is accounted for by considering the relative sizes of the individual AMR contributions as a function of temperature. Results are shown of an attempt to vary the current flow through a non-magnetic GaAs/AlGaAs 2D electron gas (2DEG) by changing the magnetization orientation of an electrically insulated Fe gate layer. Such magnetic gating of electrical current is based upon the principle that, as a result of SOC, the electrochemical potential of a ferromagnet is anisotropic with respect to its magnetization orientation. The magnetic gating experiment proved to be unsuccessful due to an AMR-like signal arising in field rotation measurements of 2DEG samples both with and without the gate layer. The origins of this AMR-like signal are unknown, and it cannot not be accounted for by fitting analysis.

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Freeman, Adam Alexander. "Magnetic X-ray spectroscopy studies of dilute magnetic semiconductors". Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10839/.

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Dilute magnetic semiconductors are an important family of materials that have many potential applications in spintronics; (Ga,Mn)As, (In,Ga,Mn)As and (Ga,Mn)N are of major interest. This thesis investigates dierent aspects of these, using the synchrotron radiation techniques of x-ray magnetic circular dichroism (XMCD) and x-ray magnetic linear dichroism (XMLD), supported by superconducting quantum interference device (SQUID) magnetometry and magnetotransport measurements. A large anisotropic XMLD signal is observed for the Mn L-edge in (Ga,Mn)As. In unannealed (Ga,Mn)As, an apparently reduced Mn magnetic moment is commonly observed. It is thought to be related to compensation of both carriers and magnetic moment, caused by interstitial Mn. This issue is investigated using combined data from XMCD, XMLD and SQUID magnetometry. The findings suggest that substitutional and interstitial Mn form `non-magnetic' pairs which do not have a preferred spin orientation. (Ga,Mn)N is studied by x-ray absorption and field-dependent XMCD at the Mn L-edge. Two distinct Mn congurations are identified: Mn2+ is prevalent towards the surface with nearly paramagnetic behaviour, while a weakly ferromagnetic Mn2+/Mn3+ mixed valence exists within the bulk. The weak ferromagnetism, often observed in (Ga,Mn)N, is attributed to coupling between the impurities by the double exchange mechanism. Finally, XMCD is used to measure the orbital polarization of As 4p states of (III,Mn)As materials. These states correspond to those of the holes involved in the itinerant exchange interaction in ferromagnetic semiconductors. The coupling between the localized d states of the magnetic impurities and the valence band p states of the host is demonstrated by an anisotropy in the orbital moment of these states. This is experimental confirmation of the origin of the magnetocrystalline anisotropy in dilute magnetic semiconductors.

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Powell, Ross E. L. "Optical studies of cubic III-nitride structures". Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/14471/.

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The properties of cubic nitrides grown by molecular beam epitaxy (MBE) on GaAs (001) have been studied using optical and electrical techniques. The aim of these studies was the improvement of the growth techniques in order to improve the quality of grown nitrides intended for bulk substrate and optoelectronic device applications. We have also characterised hexagonal nanocolumn structures incorporating indium. Firstly, bulk films of cubic AlxGa1-xN with aluminium fractions (x) spanning the entire composition range were tested using time-integrated and time-resolved photoluminescence (PL) plus reflectivity measurements. Strong PL emission was recorded from the samples, with improved intensity for higher aluminium concentrations. Temperature dependent and time-resolved PL showed the increasing role of carrier localisation at larger AlN fractions. The reflectivity results showed a near-steady increase in the bandgap energy with increasing AlN content. Alternative interpretations that did and did not involve a transition from direct-gap to indirect-gap behaviour in cubic AlxGa1-xN were considered. We next looked at cubic AlxGa1-xN/GaN/AlxGa1-xN single quantum well (QW) structures with varying AlN content in the barrier regions. The PL studies indicated that carrier escape from the QWs and non-radiative recombination at layer interfaces were limiting factors for strong well emission. Higher AlN concentration in the barriers appeared to exacerbate these problems. The doping of cubic GaN with silicon (n-type) and magnesium (p-type) was also studied. For Mg-doped GaN, a strong blue band emission was noted in the PL spectrum, which became more intense at higher doping levels. The Mg-doped GaN layers had low conductivity and their mobility could not be measured due to strong compensation effects. The cubic film had similar time-resolved PL properties for the blue band emission compared to hexagonal Mg:GaN. These results suggested that the blue band was the result of recombination between a shallow Mg acceptor and deep donor, believed to be a complex including a nitrogen vacancy and an Mg atom. This complex was also associated with the compensation effect seen in the electrical measurements. With the Si-doped cubic GaN, we observed PL spectra that were consistent with other sources. Thicker layers of GaN:Si did not have measurable mobility. This was likely caused by the rough surface structure that was imaged using a scanning electron microscope. The thin layer had a very smooth surface in comparison. The mobility of sub-micron thickness layers with a carrier concentrations of n = 2.0×1018cm-3 and n = 9.0×1017cm-3 were μ = 3.9cm2/Vs and μ = 9.5cm2/Vs respectively. The mobility values and structural issues indicated that growth improvements were needed to reduce scattering defects. In addition to cubic structures, we have considered nanocolumn growth of InGaN and InN. InxGa1-xN nanocolumns were grown on Si (111) by MBE with a nominal indium concentration of x = 0.5. PL emission was obtained from samples grown at higher temperature, but overall intensity was low. A second set of samples, where nanocolumn growth was followed by growth of a continuous coalesced film exhibited much stronger PL emission, which was attributed to the elimination of a phase separated core-shell structure in the nanocolumns. Next, a coalesced InxGa1-xN structure with vertically varying indium fraction was characterised. PL readings showed evidence of successful concentration grading. Finally, the PL spectra of coalesced InN layers were recorded, for which a specialised infrared PL system needed to be used. The results highlighted how increased growth temperature and indium flux can improve PL properties. For the binary alloy however, coalescence growth can decrease PL intensity compared to the nanocolumns stage.

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Spencer, G. S. "EEG-fMRI : novel methods for gradient artefact correction". Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/29370/.

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The general aim of the work detailed in this thesis is to improve the quality of electroencepholography (EEG) recordings acquired simultaneously with functional magnetic resonance imaging (fMRI) data. Simultaneous EEG-fMRI recordings offer significant advantages over the isolated use of each modality for measuring brain function. The high temporal resolution associated with EEG complements the high spatial resolution provided by fMRI. However, combining the two modalities can have significant effects on the overall data quality. The gradient artefact (GA), which is induced on the EEG cables by the time varying magnetic fields associated with fMRI sequences, can be particularly problematic to correct for in experiments containing any subject movement. In this thesis, two novel, movement-invariant methods are introduced for correcting the GA. The first method is named the gradient model fit (GMF) and relies upon the assumption that the GA can be modelled as a linear combination of basis components, where the relative weighting of each component varies dependent upon subject position. By modelling these underlying components, it is possible to characterise and remove the GA, which is particularly beneficial in the presence of subject movement. The second method named the difference model subtraction (DMS) relies on the assumption that the GA varies linearly for small changes in subject position. By modelling the change in GA for a basis set of likely head movements, it was shown to be possible to combine DMS with standard GA correction methods to improve the attenuation of the GA for data acquired during subject movement. Both methods showed a significant improvement over the existing GA correction techniques, particularly for experiments containing subject movement. These methods are therefore relevant to any experimenter interested in working with subject groups such as children or patients where movement is likely to occur.

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Cheney, Glenn P. (Glenn Peter) Carleton University Dissertation Engineering Electrical. "All-optical gain switching of erbium-doped fibre amplifiers". Ottawa, 1992.

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29

Cousins, Richard. "Fabrication and measurement of nanomechanical resonators". Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39302/.

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Over the past years there has been great progression in the field of micro- and nanomechanics with devices with higher and higher Q factors being created. This has been made possible thanks to a combination of advances in fabrication techniques and an increase in understanding as to what causes dissipation in nanometre scale structures. This understanding of dissipation mechanisms is still incomplete however. While lots of work has been done investigating mechanisms such as thermoelastic dissipation and dissipation due to two level systems (TLS) within the standard tunnelling model (STM) a full understanding has not been forthcoming. The increase in the quality of nanomechanical systems has allowed them to be coupled to optical or microwave cavities allowing the position of the mechanical system to be measured with near quantum limited accuracy. This thesis looks at both these streams of research within nanomechanics. It looks at the fabrication of silicon nitride torsional resonators that can have either their flexural or torsional modes preferentially actuated via a piezoelectric drive. It was found for a single paddle resonator that the room temperature Q factor of the flexural mode was 2870±70 and for the torsional mode was 5050±220. It was shown that while thermoelastic damping was reduced in the torsional mode it was still present meaning that we could not use the model for a simple beam to describe thermoelastic damping for a paddle resonator. The properties of an nanomechanical beam fabricated from a single crystal of aluminium were also investigated. It was found that at 1.5 K it had an unloaded Q factor of 36900 which is at least 2 times larger then any other group has reported. We also used our knowledge of high stress silicon nitride membranes to design a system that could couple an aluminium on silicon nitride membrane to a LCR circuit. Calculations show that this would have a coupling constant, g, of over 1000 putting it well within the regime where ground state cooling and quantum limited measurements are possible.

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30

Olanrewaju, Oluwabamise. "Impact of the European gas network on the operation of Great Britain's gas and electricity networks". Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/100254/.

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Recent events of natural gas supply disruption in Europe have led to severe consequences of supply shortages to some European Member States. As the United Kingdom increasingly depend on imported gas supply from different sources including Continental Europe, the effect of gas supply disruption in Europe on UK’s gas consumers is in question. This thesis investigated the effect of gas supply disruptions in Europe on the operation of the Great Britain’s gas and electricity network using a set of modelling tools. An optimisation model of the European gas network was developed to assess the resilience of the European gas network to the loss of gas supply through the Ukraine transit pipelines to Europe. The results showed that unserved gas demand occurred in South East Europe. It was shown that additional interconnector capacities of selected pipelines and higher storage withdrawal rate in South East Europe minimised unserved gas demand in South East Europe. A soft-link coupling of the European Gas Network model (EGN) and the Combined Gas and Electricity Network model (CGEN) was developed and used to examine the effect of a 90-day loss of Ukraine transit capacity in Europe on the operation of GB gas and electricity network at a period of limited LNG supply to Europe. The result showed that in a high gas demand situation, industrial customers would experience some amount of unserved gas demand. The effectiveness of the mitigation options to prevent or mitigate unserved gas in GB was analysed using the EGN-CGEN model. Then a cost-benefit assessment tool was used to rank the mitigation options according to the net benefit of reducing the cost of unserved gas demand in GB. It was shown that diversification of gas supply sources and routes in Europe would deliver significant security of supply benefit to GB gas and electricity network.

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31

Aguirre, Gerardo 1960. "Methodologies for modeling radiated emissions from printed circuit boards and packaged electronic systems". Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282256.

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A two-step methodology for predicting the radiated fields from lines radiating in the presence of conductor-backed substrates is presented. The method employs the use of transmission line theory to find the current distributions on the lines forming the interconnects of a circuit. These currents are used to evaluate the far-fields of the circuit through the use of dipole theory and superposition. The method was tested and validated by comparison to full-wave models. Investigations established that radiation from common-mode currents, which are not accounted for by the circuit analysis, are found to be dominated by the radiation due to differential mode currents, and thus EMI prediction based on the two-step methodology is found to have good engineering accuracy. A full-wave method based on the Finite-Difference Time-Domain (FDTD) is presented for the evaluation of radiation from structures of such geometrical complexity that the transmission line model is not applicable. The Perfectly Matched Layer truncation scheme is implemented in the FDTD and investigated for radiating structures found in printed circuit boards (PCBs). Proximity effects of the PML dictate careful attention to the proper implementation of this absorbing boundary condition. Also, the FDTD subcell model for thin wires is investigated for modelling thin microstrip interconnect lines. To evaluate the far-fields from radiating structures found in multilayer electronic packages, a novel near-to-far field transform at a single frequency is developed and implemented for sources in stratified medium. This transform is validated and investigated with regard to PML and structure proximity. The near-to-far field transform is also implemented in a methodology for obtaining the radiated emissions from a radiating structure. This methodology is used to address important concerns regarding the grounding of heat sinks, "floating" conducting planes, and the electromagnetic behavior of split ground planes.

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32

Cutshall, Ryan T. "Achieving wide bandwidth electrically small antennas using internal non-foster elements". Thesis, The University of Arizona, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1544745.

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Electromagnetic equations pertaining to electrically small dipole antennas and electrically small monopole antennas with small circular ground planes are reviewed. Two electrically small antenna designs are analyzed numerically and the results are compared. The first is a frequency agile version of the two-dimensional (2D) planar Egyptian axe dipole (EAD) antenna. The second is its three-dimensional (3D) counterpart. The frequency agile performance characteristics of both the 2D and 3D EAD designs are studied and compared. The potential for non-Foster augmentation to achieve large instantaneous fractional impedance bandwidths is detailed for each antenna. In addition, details are given on how to run frequency agile simulations in both ANSYS HFSS and Agilent's ADS. Details are also provided on how to generate an antenna's non-Foster |S₁₁| and radiation efficiency curves using HFSS, and how to generate an antenna's non-Foster |S₁₁| curve using ADS.

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33

Hafed, Mohamed M. "Analog and mixed-signal test methods using on-chip embedded test cores". Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38487.

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A robust method has been developed for the test and characterization of analog and mixed-signal integrated circuits. The method relies on a compact, robust, and easily synthesized integrated test core capable of emulating the function of external automatic test equipment. The core consists of a 2 x N memory whose contents are periodically circulated, a coarse analog filter, and a voltage comparator. One half of the circular memory is used to generate analog signals without the need for multi-bit digital-to-analog converters. The second half is used to generate extremely accurate DC levels, the latter being programmed using a clever software encoding technique that relies on some form of sigma-delta modulation. The DC levels, in combination with the comparator, enable multi-bit digitization using a progressive multiple conversion pass procedure. In order to accommodate broadband circuit phenomena, a delayed-clock sub-sampling mechanism is also employed, in which the digitizer sample clock is consistently delayed over multiple runs of the periodic test signal. One method of delaying the clock is to use a voltage-controlled delay line tuned by a delay-locked loop. The timing resolution of this approach is determined by the value of the consistent clock delay and not its period.
A divide-and-conquer approach to the test of deeply embedded analog integrated circuits using the proposed test core is described. Multiple test configurations are presented that can span a wide range of phenomena to be tested both internally to the integrated circuit and externally through I/O interfaces. The applicability of these configurations to increasing test parallelism both at the core and die levels is investigated. Performance limits of the proposed test core are also derived by drawing a comparison to conventional circuits used for data-conversion applications. The same fundamental limitations on integrated circuit performance are shown to affect the test core electronics, although test-specific requirements, such as forcing periodicity and the reliance on software signal processing, help further enhance on-chip measurement accuracy and repeatability. Finally, several successful experimental prototypes that demonstrate the viability of the proposed approach are presented. The prototypes range from concept proving test core integrated circuits to ones containing multiple simultaneously operated test cores and completely embedded circuits under test. In total, several hundred different test cores have been demonstrated, which is further testimony to the practicality of the proposed techniques.

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34

Cao, Hong 1974. "Electrical wavelength tuning in single and multi-wavelength, mode-locked semiconductor fiber ring lasers". Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82474.

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The explosive growth in the information technology industry requires high-performance optical sources. In recent years, wavelength-tunable optical pulse sources are of interest for applications in optical instrumentation, communications, and sensing. This thesis demonstrates and analyzes the generation of wavelength tunable, picosecond pulses from mode-locked semiconductor fiber ring lasers. One structure using an intracavity electro-optic modulator and the other an injected optical control signal, are investigated and experimentally characterized. A single or superimposed linearly chirped fiber Bragg gratings are used to provide wavelength selectivity, tunability, and multi-wavelength operation. The semiconductor optical amplifier as the gain media makes it possible to obtain stable simultaneous oscillation of several wavelengths at any wavelength band with very small channel spacing. We have successfully generated picosecond pulses at one or two wavelengths over the reflection bandwidth(s) of the grating(s) by simply changing the modulation frequency.

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35

Badaye, Massoud. "Investigation and improvement of a Z-pinch plasma X-ray source". Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39468.

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A thorough investigation of a pulsed plasma x-ray source is presented with the intent of improving its design and maximizing its x-ray emission efficiency. In this approach a hollow gas column is puffed in the z-pinch diode by magnetically ionizing and compressing an inert gas in an annular plenum. This gas column is preionized by the radiation coming out from the plasma in the plenum and pinched by a fast electrical discharge.
It is shown that the system can be improved considerably by modifying the gas puff design. Three gas puffs developed in this work are optimized for x-ray emission from argon, krypton, and neon gases. In the optimized conditions the output x-ray energies of 0.5 J from Ar-K shell, 2 J from Kr-L shell, and more than 2 J from Ne-K shell are obtained.
The implosion dynamics is studied with different gases under varying conditions. The average implosion velocity, the final pinch diameter, the current waveform, and the emitted x-ray energy are measured. The pinched plasma parameters such as temperature, density, and the average ionic state are estimated using the corona model calculations, and the pinched current waveforms. The spectrum of the neon radiation clearly shows the characteristic H-like and He-like lines. The neon spectrum is used to estimate the plasma temperature.
The dynamic performance of the magnetically induced compression gas puff is studied carefully. A special ion probe was developed for studying the dynamic parameters of the gas puff. The ion measurements with the probe have led to the characterization of the gas puff performance under varying operating conditions. It is shown that ions are generated through photoionization of the injected gas by the UV light emitted from the inside of the gas puff plenum through the nozzle. It is found that the jet velocity and ion density can be in excess of $3 times10 sp3$ m/s and $2 times10 sp{14}$ cm$ sp{-3}$, respectively.
A theoretical model is developed to simulate the plasma evolution in the gas puff. This model uses the magneto hydrodynamic (MHD) equations solved by the finite difference method. The magnetic field in the vacuum is calculated using the Laplace equation and self consistent boundary conditions. The model predicts the evolution of plasma variables such as density, temperature, velocity, and magnetic field. It also calculates the variation of the total mass flow rate, optical output, and the ionic signal. The simulation results are shown to compare favourably with the experimental measurements.

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36

Lee, Koon Hung 1976. "Low-voltage integrated RF CMOS modules and frontends for 5GHz RF applications". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79245.

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As the demand for wireless communications increases, high speed and low cost electronics are desired. Traditionally, RF circuits are implemented using high performance technologies such as GaAs or SiGe in order to minimize noise and achieve high gain. However, those high performance processes are incompatible with mainstream digital circuitry, which are usually implemented in CMOS technologies.
In this thesis, an RF receiver frontend which consists of a differential low noise amplifier, active mixers, passive mixers, and a quadrature voltage-controlled oscillator, for 5 GHz applications are designed and manufactured in a digital CMOS process, in order to demonstrate the RF potential of CMOS processes. We explore the use of simple circuit topologies and common packaging to build CMOS receivers that can operate from IV supplies and lower, while providing reasonable image rejection without the use of any special image rejection filters. In addition, a high image rejection receiver is explored after designing it based on good and simple frequency planning.
Apart from inductors and capacitors, transformers are very useful passive components in RF applications. For example, transformers can act as on-chip single-ended to differential converters. In this thesis, a comprehensive study of transformer modeling is presented and discussed. A modeling program has been developed, and its accuracy verified through measurements of several transformer prototypes fabricated in a variety of state-of-the-art CMOS technologies. The program allows the generation of compact lumped transformer models to be used in circuit simulation.

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37

Wang, Tongyu 1973. "The fast calculation of magnetic field using the local refinement method /". Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80150.

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The speed of the Finite Element Method (FEM) is an obstacle to the fast calculation of magnetic fields. A fast Local Refinement Method (LRM) using the first-order FEM is presented for quickly tracking the magnetic field changes while electromagnetic models have small changes made to their shape. This method resolves the potentials in the local mesh or submesh extracted from the whole mesh, with a boundary condition that is calculated by the initial solution based on the whole mesh. Instead of being re-meshed in the local area, the extracted submesh is coarsened and reshaped by the LRM to speed up the calculation time by sharply decreasing the time used for building the S matrix and solving the matrix equation Ax = b. The new potentials in the submesh are, with an acceptable error, embedded back into the whole problem to update the magnetic fields which provide designers or users with a fast visual feedback to their adjustment.

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38

Alon, Leeor. "Radio-frequency energy quantification in magnetic resonance imaging". Thesis, New York University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3635076.

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Mapping of radio frequency (RF) energy deposition has been challenging for 50+ years, especially, when scanning patients in the magnetic resonance imaging (MRI) environment. As result, electromagnetic simulation software is often used for estimating the specific absorption rate (SAR), the rate of RF energy deposition in tissue. The thesis work presents challenges associated with aligning information provided by electromagnetic simulation and MRI experiments. As result of the limitations of simulations, experimental methods for the quantification of SAR were established. A system for quantification of the total RF energy deposition was developed for parallel transmit MRI (a system that uses multiple antennas to excite and image the body). The system is capable of monitoring and predicting channel-by-channel RF energy deposition, whole body SAR and capable of tracking potential hardware failures that occur in the transmit chain and may cause the deposition of excessive energy into patients. Similarly, we demonstrated that local RF power deposition can be mapped and predicted for parallel transmit systems based on a series of MRI temperature mapping acquisitions. Resulting from the work, we developed tools for optimal reconstruction temperature maps from MRI acquisitions. The tools developed for temperature mapping paved the way for utilizing MRI as a diagnostic tool for evaluation of RF/microwave emitting device safety. Quantification of the RF energy was demonstrated for both MRI compatible and non-MRI-compatible devices (such as cell phones), while having the advantage of being noninvasive, of providing millimeter resolution and high accuracy.

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39

Kong, Yung 1967. "Particle contamination in sulfur-hexafluoride/argon plasma etching process". Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277919.

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Process generated particle contamination on unpatterned silicon wafers etched in an SF6/argon plasma using a Tegal MCR-1 etcher in the plasma triode-1 mode was characterized using response surface methodology. Particle deposition was observed to be a predictable function of plasma parameter space, which can be determined by relatively few statistically designed experiments. A model of particle deposition as a function of 13.56 MHz chamber electrode rf power, chamber pressure, gas flow rate, etch time and 100 kHz wafer electrode power was constructed. It is found that particle deposition depends linearly on etch time and both 13.56 MHz and 100 kHz power. In addition, particle deposition increased with gas flow rate at low flow rate, reaches a maximum, then decreased as flow rate increased further. Moreover, there was no observable effect on particle deposition due to pressure variation in the pressure range explored. Auger chemical analysis showed that the particles contained elemental sulfur, fluorine, silicon, aluminum, carbon and oxygen. Most particles were typically less than 2 μm in diameter.

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40

Mechaik, Mehdi Mohamad 1963. "Surface wave propagation on a perforated ground plane with dielectric coating". Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277877.

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In this thesis, the surface wave propagation along a periodically perforated conducting ground plane with dielectric coating has been studied for frequencies low enough for the ground plane to be approximated accurately by two bonded wire arrays. The field components have been obtained by using the z-directed electric and magnetic Hertz potentials which greatly simplify the application of the boundary conditions at the interfaces. The application of the appropriate boundary conditions on both sides of the plane of the wire mesh has resulted in a doubly infinite system of equations which, when truncated, can be solved for the wire currents and the propagation characteristics of the surface wave supported by the perforated ground plane. The plane is then modeled by a tensor impedance matrix relating the tangential components of the electric field to the components of the current density in the plane of the mesh. It has been shown that the surface wave propagation constant and the impedance matrix do not significantly depend on the direction of propagation for electrically small wire spacings. For such cases, it is shown that the components of the electric field can be directly related to the second order derivatives of the components of the current density flowing along the perforated ground plane.

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41

Assi, Fadi Ismail 1963. "Electromagnetic wave scattering by a sphere on a layered substrate". Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277882.

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The problem of electromagnetic scattering by a sphere on a layered substrate is treated and numerical results are presented. Initially, the Rayleigh limit, where the sphere radius is small compared to the wavelength, is considered. Closed-form expressions for the far-zone scattered fields are derived from the radiation of the induced dipoles in the sphere in the presence of the substrate, and these incorporate in a rather explicit manner the various parameters of the problem. The general case, where the ratio sphere radius/wavelength is arbitrary, is also considered. A rigorous formulation is used based on the Mie solution for the scattering by a sphere in a homogeneous medium and an extension of Weyl's method for dipole radiation in the presence of a flat surface. Numerical results obtained using the rigorous formulation for electrically small spheres are in very good agreement with those obtained using the Rayleigh approximate method.

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42

McFarland, Robert Bynum 1964. "Calculation of transmission line parameters for multiconductor lines in a multi-dielectric medium". Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278111.

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A method for computing the per-unit-length capacitance matrix and the inductance matrix for multiconductor transmission lines in a multi-dielectric medium is presented. The multi-dielectric medium consists of both planar and non-planar dielectric regions. The formulation is based on an integral equation method for the free charge distribution on conductor surfaces and the polarization charge distribution on the non-planar dielectric interfaces. The kernel of the integral equation is a space domain Green's function for a layered medium. The numerical solution is obtained by the method of moments.

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43

Vrahas, Antonios Costa 1967. "Bit error rate computations for both noise and intersymbol interference considerations in optical communications". Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/278277.

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Bit error rate computation for optical communication systems incorporating equalizers and under both noise and intersymbol interference (ISI) is discussed. An accurate method based on a saddlepoint approximation is used for the computation. Previous work based on saddlepoint approximation has considered only the use of basic integration-and-dump detection. When ISI is strong, this simple detection method is unsatisfactory. Instead, a raised-cosine filtering is often used to achieve minimal ISI. This thesis considers both integration-and-dump and raised-cosine equalizers. The use of equalizers other than integration-and-dump complicates the computation because of the complexity of the moment generating function involved. Two different input pulses are considered to study the effect of ISI. Results show that when intersymbol interference is strong, the use of raised-cosine equalizers can reduce intersymbol interference and improve the performance of the system significantly.

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44

Kipple, Allison Denise. "Fundamental investigations of double-negative (DNG) metamaterials including applications for antenna systems". Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280716.

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The postulated characteristics of double-negative (DNG) materials--i.e., materials with simultaneously negative permittivity and negative permeability (ε < 0, μ < 0)--and recent attempts to realize those characteristics with synthetic metamaterials are briefly reviewed. Investigations into the causality of signal propagation in a DNG medium are then presented. Previous research in this topic is examined, and it is verified that a DNG medium must be dispersive in order to be causal. An accurate time-domain description of propagation in a DNG medium is shown to be elusive due to the presence of dispersion, though approximate solutions and recommendations for future analytical research are provided. The results of numerical investigations into this topic are then discussed, and the anticipated combination of causal signal transmission and a negative phase shift are observed in the numerical data. Potential applications of DNG metamaterials to antenna systems are then presented. A DNG shell is observed to reduce the intrinsic reactance sensed by an infinitesimal electric dipole, thereby increasing the dipole's radiated power. Analytical expressions for the fields in the dipole--DNG shell system are derived, and numerical results for a variety of DNG shell configurations are discussed. The presence of a DNG shell is shown to increase the dipole's radiated power by orders of magnitude in some cases. A circuit model of the dipole--DNG shell system is additionally presented and used to interpret the system's physical behavior. The scattering properties of nested metamaterial shells are then analyzed. Various layering combinations of DNG, double-positive (DPS) and single-negative (SNG) shells are observed to produce resonant scattering of an incident, fundamental radial transverse-magnetic (TMᵣ) wave. Reciprocity between the metamaterial configurations that exhibit TMᵣ scattering resonances and those shown to maximize the power radiated by the infinitesimal electric dipole is demonstrated. Several additional metamaterial configurations are shown to produce both resonant TMᵣ scattering and resonant dipole radiation. A resonant configuration with one epsilon-negative (ENG) shell is especially appealing due to its manufacturability. The effects of a DNG layer on the creeping waves scattered by a small metal sphere are also discussed as a minor yet curious offshoot to the scattering analyses.

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45

Malhis, Luai Mohammed 1964. "Development and application of an efficient method for the solution of stochastic activity networks with deterministic activities". Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282098.

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Modeling and evaluation of communication and computing systems is an important undertaking. In many cases, large-scale systems are designed in an ad-hoc manner, with validation (or disappointment regarding) system performance coming only after an implementation is made. This does not need to be the case. Modern modeling tools and techniques can yield accurate performance predictions that can be used in the design process. Stochastic activity networks (SANs), stochastic Petri nets (SPNs) and analytic solution methods permit specification and fast solution of many complex system models. To enhance the modeling power of SANs (SPNs), new steady-state analysis methods have been proposed for SAN (SPN) models that include non-exponential activities (transitions). The underlying stochastic process is a Markov regenerative process (MRP) when at most one non-exponential activity (transition) is enabled in each marking. Time-efficient algorithms for constructing the Markov regenerative process have been developed. However, the space required to solve such models is often extremely large. This largeness is due to the large number of transitions in the MRP. Traditional analysis methods require all these transitions be stored in memory for efficient computation. If the size of available memory is smaller than that needed to store these transitions, a time-efficient computation is impossible using these methods. To use this class of SANs to model real systems, the space complexity of MRP analysis algorithms must be reduced. In this thesis, we propose a new steady-state analysis method that is time and space efficient. The new method takes advantage of the structure of the underlying process to reduce both computation time and required memory. The performance of the proposed method is compared to existing methods using several SAN examples. In addition, the ability to model real systems using SANs that include exponential and deterministic activities is demonstrated by modeling and evaluating the performability of a group communication protocol, called Psync. In particular, we study message stabilization time (the time required for messages to arrive at all hosts) under a wide variety of workload and message loss probabilities. We then use this information to suggest a modification to Psync to reduce message stabilizing time. Another important issue we consider is the dependability modeling and evaluation of fault-tolerant parallel and distributed systems. Because of the inherent component redundancy in such systems, the state space size of the underlying stochastic process is often very large. Reduced base model construction techniques that take advantage of symmetries in the structure of such systems have the potential to avoid this state space growth. We investigate this claim, by considering the application of SANs together with reduced base model construction for the dependability modeling and evaluation of three different systems: a fault-tolerant parallel computing system, a distributed database architecture, and a multiprocessor shared-memory system.

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46

Jose, Anita Ann. "Economic evaluation of small wind generation ownership under different electricity pricing scenarios". Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/7075.

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Master of Science
Department of Electrical and Computer Engineering
Anil Pahwa
With the Smart Grid trend setting in, various techniques to make the existing grid smarter are being considered. The price of electricity is one of the major factors, which affects the electric utility as well as the numerous consumers connected to the grid. Therefore deciding the right price of electricity for the time of day would be an important decision to make. Consumers’ response to this change in price will impact peak demand as well as their own annual energy bill. Owning a small wind generator under the Critical Peak Pricing (CPP) and Time of Use (TOU) price-based demand response programs could be a viable option. Economic evaluation of owning a small wind generator under the two pricing schemes, namely Critical Peak Pricing (CPP) and Time of Use (TOU), is the main focus of this research. Analysis shows that adopting either of the pricing schemes will not change the annual energy bill for the consumer. Taking into account the installed cost of the turbine, it may not be significantly economical for a residential homeowner to own a small wind turbine with either of the pricing schemes in effect under the conditions assumed.

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47

Novacki, Stanley M. "A development system for the bus monitor unit for the DATAC digital data bus". Ohio : Ohio University, 1987. http://www.ohiolink.edu/etd/view.cgi?ohiou1183056290.

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Sheikh, Muntasir Mohammad. "Scattering from a thin wire excited by a perpendicular line current". Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284935.

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In many applications it is necessary to determine coupling from a line current source to a nearby wire. Applications include current coupling in high-speed interconnects and wire interaction with a charged particle beam. A common physical configuration occurs when the source and wire are perpendicular to each other. In this dissertation, we investigate the scattered field and coupled current that result from such a configuration. We solve the problem for three different sources: a dipole, an array of dipoles, and a continuous line current. We detail the solution for the line current source where we obtain the scattered field by numerical integration, the far-zone approximation using steepest descents, and the excited current by numerical integration. We also show that the solution of an infinite number of phased dipoles approaches the continuous line source excitation. For the continuous line source case, we assume an infinite traveling wave line current. We also assume that the current magnitude and phase are not affected by the existence of the nearby wire. The current travels with a speed less than the speed of light in the surrounding medium. The wire is infinitely long and infinitesimally thin, and is located a distance d from the line source. We solve for the scattered field both numerically and approximately using steepest descents. We then add corrections to the saddle point approximation through two different approaches. We also solve numerically for the coupled current on the wire. Finally, we produce plots that allow us to compare the levels of the field with and without the wire present. Our problem could serve as a prelude to investigation of a traveling wave of current and an array of parallel wires. However, such a problem is quite different since the physical configuration would then allow the presence of guided waves.

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49

Lindberg, Erik, i Lukas Magnusson. "WEC Back-to-back Topology". Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-351912.

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50

Rodrigo, Deepal. "Optimal operational strategies for a day-ahead electricity market in the presence of market power using multi-objective evolutionary algorithm". Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/389.

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