Dissertations / Theses on the topic 'Cost efficient powder'

Aquesta tesi es centra en la mitigació dels desequilibris deguts a l'envelliment dels sistemes fotovoltaics. La degradació de la corrent de curtcircuit s'ha considerat com el principal factor que afecta la producció d'energia de sistemes fotovoltaics a causa de l'envelliment. Encara que, en el passat, s'ha detectat la dispersió en corrent de curtcircuit actual i màxima, es va subestimar la pèrdua d'energia deguda a la dispersió. A més, la dispersió dels paràmetres de voltatge-corrent a nivell de mòdul s'ha considerat per a la mitigació dels desequilibris a nivell de submòdul, mentre que la potència recuperable a nivell de submòdul pot ser superior a la que s'ha estimat. Per tal de verificar el compliment de les dades del nivell del submòdul a les dades del nivell del mòdul, en aquesta investigació, s'han realitzat mesures a nivell de submòdul. Es mostra que l'estimació de pèrdua d'energia a causa de l'envelliment basat en dades de dispersió a nivell de mòdul, s'ha infravalorat i considerant que la millora de l'energia en temps de vida a nivell de submòdul és possible fins a un 4-6%. Per tal de mitigar el desequilibri per envelliment en el sistema fotovoltaic, es proposa un convertidor de guany d'unitat, bidireccional i aïllat de baixa potència. Es presenta el procediment de disseny i realització experimental del convertidor i del seu esquema de control. El transformador d'alta freqüència proporciona l'aïllament galvànic entre primària i secundària. A més, els inductors ressonants s'han integrat en el transformador, cosa que redueix la mida i el cost del convertidor. Els resultats experimentals mostren que les eficiències de transferència de potència superen el 90% per a càrregues entre 1 W i 8 W. Es verifica el rendiment del convertidor per a la mitigació de desajustos. Al laboratori, tres prototips s'han provat en un mòdul fotovoltaic seguint l'enfocament d'arquitectura DPP PV-IP. S'observa que aquests tres convertidors mitiguen les dispersions dels submoduls i proporcionen la màxima potència possible. També es discuteix l'impacte de la mitigació dels desequilibris per envelliment en el cost d'energia (LCOE).
Esta tesis se centra en la mitigación del desajuste debido al envejecimiento en los sistemas fotovoltaicos. La degradación de la corriente de cortocircuito se ha considerado el principal factor que afecta la producción de energía de los sistemas fotovoltaicos debido al envejecimiento. Aunque en el pasado se ha informado la dispersión en la corriente de cortocircuito y la corriente de potencia máxima, se ha subestimado la pérdida de energía debida a la dispersión. Además, se ha considerado la dispersión de los parámetros de voltaje-corriente a nivel de módulo para la mitigación de desajustes a nivel de submódulo, mientras que la potencia recuperable a nivel de submódulo puede ser mayor que la estimada. Para verificar la conformidad de los datos de nivel de submódulo a los datos de nivel de módulo, en esta investigación, las mediciones se han realizado a nivel de submódulo. Se muestra que la estimación de la pérdida de energía debido al envejecimiento basado en el nivel de módulo, los datos de dispersión han sido subestimados y, considerando los datos de desajuste de nivel de submódulos, la mejora de la vida útil de la energía puede ser de hasta 4-6%. Con el fin de mitigar los desequilibrios por envejecimiento en el sistema fotovoltaico, se propone un convertidor de ganancia unitaria,de baja potencia, aislado y bidireccional dc-dc. Se presenta el procedimiento de diseño y realización experimental del convertidor y su esquema de control. El transformador de alta frecuencia proporciona el aislamiento galvánico entre primario y secundario. Además, se han integrado inductores resonantes en el transformador, lo que reduce el tamaño y el coste del convertidor. Los resultados experimentales muestran una eficiencia de transferencia de potencia superior al 90% para cargas entre 1 W y 8 W. Se verifica el rendimiento del convertidor para la mitigación de desajustes. En el laboratorio, se han comprobado tres prototipos conectados con un módulo fotovoltaico siguiendo el enfoque de la arquitectura DPP PV-IP. Se observa que estos tres convertidores mitigan totalmente los desajustes entre los tres submódulos y proporcionan la máxima potencia posible. También se discute el impacto de la mitigación del desajuste por envejecimiento en el coste de la energia.
This thesis focused on mitigation of mismatch due to ageing in PV systems. Degradation of short circuit current has been considered the principle factor that affects the energy production of PV systems due to ageing. Although, dispersion in short circuit current and maximum power current has been reported in the past, the energy loss due to dispersion has been underestimated. Moreover, dispersion of voltage-current parameters at module level have been considered for mismatch mitigation at submodule level whereas the recoverable power at submodule level may higher than that has been estimated. In order verify the accordance of submodule level data to module level data, in this research, measurements have been done at submodule level. It is shown that estimation of energy loss due to ageing based on module level dispersion data has been underrated and considering submodule level mismatch data life time energy improvement an be possible up to 4-6 %. In order to mitigate the ageing mismatch in PV system, a dc-dc bidirectional isolated low power unity gain converter is proposed. Design procedure and experimental realization of the converter is presented. A control scheme that allows bidirectional power flow is also presented. High frequency ferrite ore transformer provides the galvanic isolation between primary and secondary. In addition, resonant inductors have been integrated in the transformer, which reduces the size and cost of the converter. Experimental results show power transfer efficiencies more than 90 % for loads between 1 W to 8 W. The performance of the converter for mismatch mitigation is verified. In the laboratory, three prototype converters are attached with a PV module following the DPP PV-IP architecture approach. It is observed that these three converters an fully mitigate mismatch among three submodules and provide maximum possible power. The impact of mitigation of ageing mismatch on levelized cost of energy (LCOE) is also discussed.

Cette thèse traite de la notion de compétitivité des unités industrielles par l’indicateur de l’efficience obtenu avec la méthode DEA. L’efficience des alumineries de l’industrie de l’aluminium primaire est analysée sur quatre années distinctes 2005, 2009, 2010 et 2012. Les résultats révèlent que ces unités sont globalement peu efficientes techniquement (inefficience de l’ordre de 1 à 5% selon la technologie utilisée et la région) ; leurs combinaisons productives semblent donc peu optimales. De plus, l’inefficience est davantage prononcée au niveau du coût et de l’allocation de leurs ressources en considérant les prix des inputs différents ou identiques d’une aluminerie à une autre. Tout ceci pourrait expliquer les fermetures enregistrées ces dernières années. Par ailleurs, nous avons montré que l’inefficience technique était expliquée par l’impact des variables explicatives âge, taille et le taux de change. Au travers d’un modèle VECM linéaire nous avons montré qu’il existe une relation de long terme entre la performance financière des grands constructeurs automobiles et le prix de l’aluminium allié. Ce résultat étant l’indicatif de l’interdépendance entre ces deux industries
This thesis deals with the concept of competitiveness of industrial units by the efficiency indicator obtained by DEA approach. We use a cross section data over four different years around 2009. The results show that these units are generally technically inefficient (inefficiency of the order of 1 to 5% by technology and region); their productive combination thus seems less than optimal. In addition, the inefficiency is more pronounced in the cost and allocation of resources by considering the inputs prices of an aluminum smelter in another. All this may explain the closures of recent years. We analyze the assessment of how external factors such as exchange rate, vintage and scale affect the smelters efficiency. Through a linear VECM model we have shown a long-term relationship between the financial performance of major car manufacturers and the price of aluminum alloy. This result is indicative of the interdependence between the two industries

This dissertation first develops a theoretical framework to enable the estimation of cost efficiency and conduct parameter without total cost data. By validating this framework using U.S. airline data, this dissertation shows the feasibility of the theoretical framework. Based on the estimates of marginal cost efficiency and conduct parameter, this dissertation also finds some support for the Quiet Life Hypothesis. In Chapter III, this dissertation analyzes the determinants for price dispersion, especially conduct parameter and cost efficiency. Generally speaking, we find negative relationship between conduct parameter and price dispersion and negative relationship between marginal cost efficiency and price dispersion. In Chapter IV, this thesis examines the dynamics that lead to high price dispersion. To be more specific, this thesis concentrates on advanced days purchased and load factor.

The kinetic energy in river streams, tidal currents, or other artificial water channels has been used as a feasible source of renewable power through different conversion systems. Thus, hydrokinetic energy conversion systems are attracting worldwide interest as another form of distributed alternative energy. Because these systems are still in early stages of development, the basic approaches need significant research. The main challenges are not only to have efficient systems, but also to convert energy more economically so that the cost-benefit analysis drives the growth of this alternative energy form. One way to view this analysis is in terms of the energy conversion efficiency per unit cost. This study presents a detailed assessment of a prototype hydrokinetic energy system along with power output costs. This experimental study was performed using commercial low-cost blades of 20 in diameter inside a tank with water flow speed up to 1.3 m/s. The work was divided into two stages: (a) a fixed-pitch blade configuration, using a radial permanent magnet generator (PMG), and (b) the same hydrokinetic turbine, with a variable-pitch blade and an axial-flux PMG. The results indicate that even though the efficiency of a simple blade configuration is not high, the power coefficient is in the range of other, more complicated designs/prototypes. Additionally, the low manufacturing and operation costs of this system offer an option for low-cost distributed power applications.

Wireless access networks today consume 0.5 percent of the global energy. Rapidly growing demand for new services and ubiqutious connectivity, will further increase the energy consumption. This situation imposes a big challenge for mobile operators not only due to soaring cost of energy, but also increasing concern for global warming and sustainable development. This thesis focuses on the energy efficiency issue at the system level and studies how to incorporate energy-awareness into the design of future wireless access networks. The main contributions have been given in the areas of energy efficiency assessment, architectural and operational solutions, and total cost of investment analysis. The precise evaluation of energy efficiency is the first essential step to determine optimized solutions where metrics and models constitute the two key elements.We show that maximizing energy efficiency is not always equivalent to minimizing energy consumption which is one of the main reasons behind the presented contradictory and disputable conclusions in the literature. Further we indicate that in order to avoid the debatable directions, energy efficient network design problems should be formulated with well defined coverage and capacity requirements. Moreover, we propose novel backhaul power consumption models considering various technology and architectural options relevant for urban and rural environments and show that backhaul will potentially become a bottleneck in future ultra-high capacity wireless access networks. Second, we focus on clean-slate network deployment solutions satisfying different quality of service requirements in a more energy efficient manner. We identify that the ratio between idle- and transmit power dependent power consumption of a base station as well as the network capacity requirement are the two key parameters that affect the energy-optimum design.While results show that macro cellular systems are the most energy efficient solution for moderate average traffic density, Hetnet solutions prevail homogeneous deployment due to their ability to increase the capacity with a relatively lower energy consumption and thus enable significant energy savings in medium and high capacity demand regions. Moreover, we investigate the energy saving potential of short-term energy aware management approach, i.e., cell DTX, taking advantage of low resource utilization in the current networks arising from strict QoS requirements. With the help of developed novel quantitative method, we show that Cell DTX brings striking reduction in energy consumption and further savings are achievable if the networks are designed taking into account the fact that network deployment and operation are closely related. Finally, we develop a general framework for investigating the main cost elements and for evaluating the viability of energy efficient solutions.We first reveal the strong positive impact of spectrum on both energy and infrastructure cost and further indicate that applying sustainable solutions might also bring total cost reduction, but the viability highly depends on unit cost values as well as the indirect cost benefits of energy efficiency. Results obtained in this dissertation might provide guidelines for the network designers to achieve future high-capacity and sustainable wireless access networks.

QC 20140505

Efficiency analysis in the public sector assesses the performance of municipal and government entities in their provision of services to the public. South Africa, in particular, has experienced a large degree of negative feedback with respect to the ability of the government and its municipal departments to provide basic services to citizens. This has led to a number of service delivery protests throughout the country. To remedy this, the ability of the municipality to provide basic services needs to be assessed in order for improvements to be made. A first step in this process would be to determine the efficiency with which municipalities are providing these services. This study focuses on a particular municipal service, namely electricity distribution. Primarily, the efficiency with which municipalities provide electricity to consumers is determined. This is achieved using the parametric cost frontier approach, which is appropriate since municipalities aim to reduce the costs incurred in distributing electricity. The municipalities are compared to a frontier (theoretical best practice) from which inferences on their performances can be made. Those municipalities whose performances are not optimal, deviate from the frontier. The deviations (errors) are then assumed to be caused by two factors, namely stochastic random noise and inefficiency. This composition accounts for effects for which municipalities cannot control (stochastic random noise) and those for which it can (inefficiency). The parametric nature of the cost frontier approach allows for distributional assumptions to be made on these factors. Stochastic random noise is always assumed to be normally distributed, while inefficiency is assumed to be one-sided and positively skewed.

付記する学位プログラム名: 京都大学卓越大学院プログラム「先端光・電子デバイス創成学」
京都大学
新制・課程博士
博士(情報学)
甲第23325号
情博第761号
京都大学大学院情報学研究科通信情報システム専攻
(主査)教授 小野寺 秀俊, 教授 大木 英司, 教授 佐藤 高史
学位規則第4条第1項該当
Doctor of Informatics
Kyoto University
DFAM

Demand for energy-saving variable speed drives in low-cost, high-volume appliances has increased due to energy and environmental concerns and hence the need to comply with new regulations. Switched reluctance motor (SRMs) have been considered by many as attractive alternatives for brush commutated motors or permanent magnet brushless dc motors (PMBDCMs) in such cost-sensitive applications. The SRMs' unique features such as simple and fault-tolerant structure and unidirectional flow of their phase currents endow them with the possibility of various configurations on both machine and converter topologies for different applications. In the present study, three different variable-speed motor drive systems are proposed, studied, and implemented for their deployment in low-cost, high-volume applications with the power rating of 1.5kW or less. Two different two-phase SRMs and three different power converters are employed to realize three different low-cost drive systems. The first drive system is realized using a novel converter requiring only a single-controllable switch and an asymmetric two-phase 8/4 SRM capable of self-starting and four-quadrant operation. The second drive system is realized using another novel converter requiring two controllable switches, that way to achieve better control and utilization of the asymmetric 8/4 motor. The target applications for both drive systems are low power, low performance drives such as fans, hand tools, small appliances, etc. The third system is realized using a high-speed two-phase 4/2 SRM and a split ac source converter, which is designed for high-speed applications such as vacuum cleaners, ultracentrifuges, etc. The control and design aspects for each drive system are studied. Selection of optimal firing angles and optimal number of winding turns are also investigated. All of the drive systems are first demonstrated on the position sensor-based speed-control scheme. To make the drive system even more cost-competitive, operation without the position sensor using the novel parameter insensitive sensorless control scheme is proposed and implemented. Concept, analysis, simulation, and experimental verification of the proposed sensorless scheme are discussed in detail.
Ph. D.

[EN] Modern data centers integrate a lot of computer and electronic devices. However, some reports state that the mean usage of a typical data center is around 50% of its peak capacity, and the mean usage of each server is between 10% and 50%. A lot of energy is destined to power on computer hardware that most of the time remains idle. Therefore, it would be possible to save energy simply by powering off those parts from the data center that are not actually used, and powering them on again as they are needed. Most data centers have computing clusters that are used for intensive computing, recently evolving towards an on-premises Cloud service model. Despite the use of low consuming components, higher energy savings can be achieved by dynamically adapting the system to the actual workload. The main approach in this case is the usage of energy saving criteria for scheduling the jobs or the virtual machines into the working nodes. The aim is to power off idle servers automatically. But it is necessary to schedule the power management of the servers in order to minimize the impact on the end users and their applications. The objective of this thesis is the elastic and efficient management of cluster infrastructures, with the aim of reducing the costs associated to idle components. This objective is addressed by automating the power management of the working nodes in a computing cluster, and also proactive stimulating the load distribution to achieve idle resources that could be powered off by means of memory overcommitment and live migration of virtual machines. Moreover, this automation is of interest for virtual clusters, as they also suffer from the same problems. While in physical clusters idle working nodes waste energy, in the case of virtual clusters that are built from virtual machines, the idle working nodes can waste money in commercial Clouds or computational resources in an on-premises Cloud.
[ES] En los Centros de Procesos de Datos (CPD) existe una gran concentración de dispositivos informáticos y de equipamiento electrónico. Sin embargo, algunos estudios han mostrado que la utilización media de los CPD está en torno al 50%, y que la utilización media de los servidores se encuentra entre el 10% y el 50%. Estos datos evidencian que existe una gran cantidad de energía destinada a alimentar equipamiento ocioso, y que podríamos conseguir un ahorro energético simplemente apagando los componentes que no se estén utilizando. En muchos CPD suele haber clusters de computadores que se utilizan para computación de altas prestaciones y para la creación de Clouds privados. Si bien se ha tratado de ahorrar energía utilizando componentes de bajo consumo, también es posible conseguirlo adaptando los sistemas a la carga de trabajo en cada momento. En los últimos años han surgido trabajos que investigan la aplicación de criterios energéticos a la hora de seleccionar en qué servidor, de entre los que forman un cluster, se debe ejecutar un trabajo o alojar una máquina virtual. En muchos casos se trata de conseguir equipos ociosos que puedan ser apagados, pero habitualmente se asume que dicho apagado se hace de forma automática, y que los equipos se encienden de nuevo cuando son necesarios. Sin embargo, es necesario hacer una planificación de encendido y apagado de máquinas para minimizar el impacto en el usuario final. En esta tesis nos planteamos la gestión elástica y eficiente de infrastructuras de cálculo tipo cluster, con el objetivo de reducir los costes asociados a los componentes ociosos. Para abordar este problema nos planteamos la automatización del encendido y apagado de máquinas en los clusters, así como la aplicación de técnicas de migración en vivo y de sobreaprovisionamiento de memoria para estimular la obtención de equipos ociosos que puedan ser apagados. Además, esta automatización es de interés para los clusters virtuales, puesto que también sufren el problema de los componentes ociosos, sólo que en este caso están compuestos por, en lugar de equipos físicos que gastan energía, por máquinas virtuales que gastan dinero en un proveedor Cloud comercial o recursos en un Cloud privado.
[CAT] En els Centres de Processament de Dades (CPD) hi ha una gran concentració de dispositius informàtics i d'equipament electrònic. No obstant això, alguns estudis han mostrat que la utilització mitjana dels CPD està entorn del 50%, i que la utilització mitjana dels servidors es troba entre el 10% i el 50%. Estes dades evidencien que hi ha una gran quantitat d'energia destinada a alimentar equipament ociós, i que podríem aconseguir un estalvi energètic simplement apagant els components que no s'estiguen utilitzant. En molts CPD sol haver-hi clusters de computadors que s'utilitzen per a computació d'altes prestacions i per a la creació de Clouds privats. Si bé s'ha tractat d'estalviar energia utilitzant components de baix consum, també és possible aconseguir-ho adaptant els sistemes a la càrrega de treball en cada moment. En els últims anys han sorgit treballs que investiguen l'aplicació de criteris energètics a l'hora de seleccionar en quin servidor, d'entre els que formen un cluster, s'ha d'executar un treball o allotjar una màquina virtual. En molts casos es tracta d'aconseguir equips ociosos que puguen ser apagats, però habitualment s'assumix que l'apagat es fa de forma automàtica, i que els equips s'encenen novament quan són necessaris. No obstant això, és necessari fer una planificació d'encesa i apagat de màquines per a minimitzar l'impacte en l'usuari final. En esta tesi ens plantegem la gestió elàstica i eficient d'infrastructuras de càlcul tipus cluster, amb l'objectiu de reduir els costos associats als components ociosos. Per a abordar este problema ens plantegem l'automatització de l'encesa i apagat de màquines en els clusters, així com l'aplicació de tècniques de migració en viu i de sobreaprovisionament de memòria per a estimular l'obtenció d'equips ociosos que puguen ser apagats. A més, esta automatització és d'interés per als clusters virtuals, ja que també patixen el problema dels components ociosos, encara que en este cas estan compostos per, en compte d'equips físics que gasten energia, per màquines virtuals que gasten diners en un proveïdor Cloud comercial o recursos en un Cloud privat.
Alfonso Laguna, CD. (2015). Efficient and elastic management of computing infrastructures [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/57187
TESIS

The 5G technology has enabled performance-sensitive applications with low latency and high bandwidth requirements, which has put more low latency requirements on computing services. To answer this need, a small-scale data center called edge cloud is predicted to grow fast in the future. Due to its nature of being close to the end-users, the growth of edge clouds in the populated area may cause a problem with the existing power system. Besides this power system challenge, the edge cloud also requires a higher resource cost than the hyper-scale data center because of the economies of scale. In this thesis, four viable alternative power and cooling technologies are introduced to address those challenges. These four technologies are solar PV, Vertical Axis Wind Turbine (VAWT), Rear Door Heat Exchanger (RDHx), and immersion cooling. Detailed data of edge cloud are required to understand the contribution of these four technologies. However, due to the infancy state of edge cloud, those data are unavailable, and assumptions regarding data are made. Besides that, a cost model for an edge cloud is also required to show how significant the contribution of those alternative technologies is if compared to the total cost of ownership. In this thesis, the cost model for the edge cloud is extended for the alternative power and cooling system scenarios. Along with the assumed data of an edge cloud, sensitivity analysis is performed to determine whether the alternative power and cooling technologies can bring down the cost of edge cloud resources or not. Through the cost modeling, it was found out that VAWT and immersion cooling is not feasible for the particular assumed data center. On the other hand, solar PV can save 4.55% of data center electricity consumption (equal to 0.21% reduction of the total expense when calculated using the current electricity price). Furthermore, RDHx performed better with 22.73% of data center electricity expenses (equivalent to 8.35% of saving from total cost when calculated using the current electricity price).
5G-tekniken har möjliggjort prestandakänsliga applikationer med låg latens och höga bandbreddskrav, vilket har ställt högre krav på låg latens för datatjänster. För att möta detta behov förutspås ett småskaligt datacenter - edge cloud – växa i framtiden. På grund av dess användarnära natur kan tillväxten av edge clouds i tätområden orsaka problem med det befintliga kraftsystemet. Förutom denna kraftsystemutmaning kräver edge cloud också en högre resurskostnad än storskaliga datacenter på grund av skalfördelarna. I denna avhandling introduceras fyra alternativa energi- och kyltekniker för att hantera dessa utmaningar. Dessa fyra tekniker är solpanel, vertikalaxel vindturbin (VAWT), bakdörrvärmeväxlare (RDHx), och nedsänkningskylning. Detaljerad information om edge cloud erfordras för att förstå bidraget från dessa fyra tekniker. På grund av edge clouds tidiga stadium är all nödvändig data dock inte tillgänglig, vaför antaganden om görs. Förutom det krävs också en kostnadsmodell för edge cloud för att visa hur betydande bidraget från den alternativa tekniken är om den jämförs med den totala ägandekostnaden. I denna avhandling utökas kostnadsmodellen för edge cloud för de alternativa energi- och kylsystemscenarierna. Med antagen data för ett edge cloud genomförs en känslighetsanalys för att avgöra om alternativa energi- och kyltekniker kan sänka kostnaden för edge cloud-resurser eller inte. Kostnadsmodelleringen visar att VAWT och nedsänkningskylning inte är möjlig för det specifika antagna datacentret. Å andra sidan kan solpanel spara 4,55% av datacentrets elförbrukning (motsvarande 0,21% minskning av den totala kostnaden när den beräknas med det aktuella elpriset). Dessutom presterade RDHx bättre med 22,73% av datacenters elutgifter (motsvarande 8,35% av besparingen från totalkostnaden när den beräknas med det aktuella elpriset).

In this work two low cost, high efficiency, high power DC/DC converters are developed. The first converter is targeted for industrial laser applications. The converter is designed for a 400 volt input voltage and a 0-36V output voltage and 0-40A output with a maximum power output of 1500 watts at a cost less than $0.30 / watt. To achieve a high efficiency and low cost at this power level a zero-voltage switched full bridge converter is used. This technology increases the efficiency of the converter past 90% while reducing the size of the components. The converter was built and tested and achieved a 91.5% efficiency at full load. The total cost was $0.28 / watt. This converter met all the design goals while exceeding the cost goals. The second converter is targeted for residential fuel cell applications. This converter utilizes the technology developed for the industrial converter. This residential converter is designed for an input of 26-42 volts at 190 amps and an output of 400 volts and 12 amps at a power level of 5000 watts while maintaining a $40/kilowatt cost goal. To achieve the low cost and high efficiency design goals the converter uses several technologies in its construction. Like the converter for industrial applications this converter utilizes zero voltage switching full bridge converter. To compensate for the high input current a unique multiphase design was designed for the application. A unique parallel input / series output topology and three interleaved converters split the input current to increase the efficiency of the converter. This unique topology increases the switching frequency on the secondary side which reduces the side of the passive components, reducing cost. The converter was built and tested at a light load to verify its operation versus the theory. An estimated 96% efficiency at full load is possible using this topology. The total cost was $39 / kilowatt.

This study investigates three aspects important of performance for Zambia commercial banks. Specifically, the thesis addresses the aspect of cost efficiency and the factors that affect inefficiency performance. The study also empirically answers the policy question regarding the banks' exercise of market power and the low degree of competition. Using a richly assembled panel data set obtained from the Bank of Zambia on individual banks from 1998 to 2006, the thesis utilises theoretically sound methodologies in addressing these research questions. The results from the analysis reveal the following. Firstly, using stochastic frontier estimation approach, cost inefficiency was estimated to be 8 percent. This means that mismanagement of resources was an impediment to the efficiency performance. Nonetheless, we observed a reduction in cost inefficiency over time, with domestic private banks displaying remarkable improvement. A combination of bank-specific and exogenous factors deterred banks from attaining optimal cost efficiency. Notably, impaired loans, asset concentration and macroeconomic instability undermined the banks' ability to operate optimally. Regulatory factors did not exacerbate cost inefficiency. Secondly, Zambian banks operated in an oligopolistic set-up. Based on a methodology anchored in the New Empirical Industrial Organisation literature, the results of a competitive test showed that banks earned their revenue under conditions of monopolistic competition. This finding was buttressed by the estimated time varying Lerner Index, a measure of market power. The index showed that commercial banks set their prices above marginal cost by more than 50 percent. However, the degree of market power narrowed towards the end of the sample period. Market concentration, efficiency performance, diversity in revenue sources and regulatory intensity accounted for much of the banks' exercise of market power. On the other hand, the high proportion of interbank deposits, credit risk exposure and inflation dampened the banks' exercise of market power. To our knowledge, this study is the first of its kind in Zambia. Therefore, the results of the thesis have important policy implications. More significantly, since there is room for deepening the degree of competition and furthering efficiency gains, regulatory authorities should strengthen measures aimed at ameliorating risk problems in the banking industry in a bid to lower the banks' exercise of market power. The authorities should also accelerate should also accelerate efforts of reducing recourse to Treasury bills as a deficit financing tool in order to negate the banks' appetite for securities as a source of revenue. This can be done by placing more emphasis on the legal and institutional framework for resolving problem credit situations. This will intensify competition and propagate efficiency gains in the banking market. The authorities should also expeditiously tackle instability in the macroeconomic environment, particularly the high rate of inflation which hampered the banks' revenue performance and exacerbated the exercise of market power

With the increase in the world energy demand and environmental incentives, renewable energy sources (RES) need to determine their place as some of the primary power sources in future power systems. However, due to uncertain energy production, renewable energy sources cause unbalance in the power system due to the unsynchronized supply and electricity demand. The intermittent power production causes undesired power fluctuation, affecting the power quality and reliability of the power source. Energy storage is one solution that is debated to increase the reliability of renewable energy production. This thesis aims to model and simulate hybrid energy storage system (HESS), constructed of hydrogen and ultracapacitor energy storage, to investigate different operation strategies for everyday use and crises. The two different energy storage technologies complement each other, where hydrogen fuel cells can produce power for long periods of time while the ultracapacitor can quickly maintain the balance of production and consumption of electricity for a short instance. The HESS showed promising results for emergency power supply and supported service operation strategies. In case of a power shortage, the HESS could cover for the disconnected production. The ultracapacitor proved to be a suitable component due to its ability to support the shortcomings of a hydrogen energy storage system. Moreover, the HESS could meet the requirements to deliver support services. However, further studies have to be done to investigate how the HESS can deliver multiple support services to increase profit and help maintain the power system's balance and security.

Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Rohatgi, Ajeet; Committee Co-Chair: Begovic, Miroslav; Committee Member: Gaylord, Thomas; Committee Member: Harley, Ronald; Committee Member: Jarrett, Christopher; Committee Member: Kippelen, Bernard

Stand-alone hybrid energy systems are an attractive option for remote communities without a connection to a main power grid. However, the intermittent nature of solar and other renewable sources adversely affects the reliability with which these systems respond to load demands. Hybridisation, achieved by combining renewables with combustion-based supplementary prime movers, improves the ability to meet electric load requirements. In addition, the waste heat generated from backup Internal Combustion Engines or Micro Gas Turbines can be used to satisfy local heating and cooling loads. As a result, there is an expectation that the overall efficiency and Greenhouse Gas Emissions of stand-alone systems can be significantly improved through waste heat recovery. The aims of this PhD project are to identify how incremental increases to the hardware complexity of hybridised stand-alone energy systems affect their cost, efficiency, and CO2 footprint. The research analyses a range of systems, from those designed to meet only power requirements to others satisfying power and heating (Combined Heat and Power), or power plus both heating and cooling (Combined Cooling, Heating, and Power). The majority of methods used focus on MATLAB-based Genetic Algorithms (GAs). The modelling deployed finds the optimal selection of hardware configurations which satisfy single- or multi-objective functions (i.e. Cost of Energy, energy efficiency, and exergy efficiency). This is done in the context of highly dynamic meteorological (e.g. solar irradiation) and load data (i.e. electric, heating, and cooling). Results indicate that the type of supplementary prime movers (ICEs or MGT) and their minimum starting thresholds have insignificant effects on COE but have some effects on Renewable Penetration (RP), Life Cycle Emissions (LCE), CO2 emissions, and waste heat generation when the system is sized meeting electric load only. However, the transient start-up time of supplementary prime movers and temporal resolution have no significant effects on sizing optimisation. The type of Power Management Strategies (Following Electric Load-FEL, and Following Electric and Following Thermal Load- FEL/FTL) affect overall Combined Heating and Power (CHP) efficiency and meeting thermal demand through recovered heat for a system meeting electric and heating load with response to a specific load meeting reliability (Loss of Power Supply Probability-LPSP). However, the PMS has marginal effects on COE. The Electric to Thermal Load Ratio (ETLR) has no effects on COE for PV/Batt/ICE but strongly affects PV/Batt/MGT-based hybridised CHP systems. The higher thermal than the electric loads lead to higher efficiency and better environmental footprint. Results from this study also indicate that for a stand-alone hybridised system operating under FEL/FTL type PMS, the power only system has lower cost compared to the CHP and the Combined Cooling, Heating, and Power (CCHP) systems. This occurs at the expense of overall energy and exergy efficiencies. Additionally, the relative magnitude of heating and cooling loads have insignificant effects on COE for PV/Batt/ICE-based system configurations, however this substantially affects PV/Batt/MGT-based hybridised CCHP systems. Although there are no significant changes in the overall energy efficiency of CCHP systems in relation to variations to heating and cooling loads, systems with higher heating demand than cooling demand lead to better environmental benefits and renewable penetration at the cost of Duty Factor. Results also reveal that the choice of objective functions do not affect the system optimisation significantly.

A comparison between a traditional fixed high voltage direct current energy transmission system and a mobile transmission system utilizing vanadium redox flow batteries has been conducted in this degree work.  The purpose of this comparison was to evaluate if a mobile energy transmission system could be competitive in terms of energy efficiency and cost-effectiveness for use in offshore wind power applications. A literary study was made to fully grasp the various technologies and to create empirical ground of which cost estimation methods and energy calculations could be derived. A specific scenario was designed to compare the two transmission systems with the same conditions. To perform the comparison, a model was designed and simulated in MATLAB. The results from the model showed that the flow battery system fell behind in energy efficiency with a total energy loss of 33.3 % compared to the 11.7 % of the traditional system, future efficiency estimations landed it at a more competitive 17.5 %. The techno-economic results proved that a mobile flow battery system would be up to nine times more expensive in comparison to a traditional transmission system, with the best-case scenario resulting in it being roughly two times more expensive. The main cause of this was found out to be the expensive energy subsystem, specifically the electrolyte, used in the flow battery system. Several environmental risks arise when using a flow battery system with this electrolyte as well which could harm marine life severely. In conclusion; with further development and cost reductions, a case could be made for the advantages of a truly mobile energy transmission system. Specifically, in terms of the pure flexibility and mobility of the system, allowing it to circumvent certain complications. The mobility of the system gives the possibility of selling energy where the spot prices are at their highest, providing a higher revenue potential compared to a traditional fixed system. As for now though, it is simply too expensive to be a viable solution.

Smart cameras operate mostly in sleep mode, which is light load for power supplies. Typical buck converter applications have low efficiency under the light load condition, primarily from their power stage and control being optimized for heavy load. The battery life of a smart camera can be extended through improvement of the light load efficiency of the buck converter. This thesis research investigated the first stage converter of a car black box to provide power to a microprocessor, camera, and several other peripherals. The input voltage of the converter is 12 V, and the output voltage is 5 V with the load range being 20 mA (100 mW) to 1000 mA (5000 mW). The primary design objective of the converter is to improve light load efficiency. A 3-level buck converter and its control scheme proposed by Reusch were adopted for the converter in this thesis. A 3-level buck converter has two more MOSFETs and one more capacitor than a synchronous buck converter. Q1 and Q2 are considered the top MOSFETs, while Q3 and Q4 are the synchronous ones. The extra capacitor is used as a second power source to supply the load, which is connected between the source of Q1 and the drain of Q2 and the source of Q3 and the drain of Q4. The methods considered to improve light load efficiency are: PFM (pulse frequency modulation) control scheme with DCM (discontinuous conduction mode) and use of Schottky diodes in lieu of the synchronous MOSFETs, Q3 and Q4. The 3-level buck converter operates in CCM for heavy load above 330 mA and DCM for light load below 330 mA. The first method uses a COT (constant on-time) valley current mode controller that has a built in inductor current zero-crossing detector. COT is used to implement PFM, while the zero-crossing detector allows for DCM. The increase in efficiency comes from reducing the switching frequency as the load decreases by minimizing switching and gate driving loss. The second method uses an external current sense amplifier and a comparator to detect when to shut down the gate drivers for Q3 and Q4. Schottky diodes in parallel with Q3 and Q4 carry the load current when the MOSFETs are off. This increases the efficiency through a reduction in switching loss, gate driving loss, and gate driver power consumption. The proposed converter is prototyped using discrete components. LTC3833 is used as the COT valley current mode controller, which is the center of the control scheme. The efficiency of the 3-level buck converter was measured and ranges from 82% to 95% at 100 mW and 5000 mW, respectively. The transient response of the converter shows no overshoot due to a 500 mA load step up or down, and the output voltage ripple is 30 mV. The majority of the loss comes from the external components, which include a D FF (D flip-flop), AND gate, OR gate, current sense chip, comparator, and four gate drivers. The proposed converter was compared to two off-the-shelf synchronous buck converters. The proposed converter has good efficiency and performance when compared to the other converters, despite the fact that the converter is realized using discrete components.
Master of Science

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The present work had as an objective to evaluate the viability of the use of biogas proceeding from the activities of bovine culture of milk and swine culture in sets motor generator and motor bomb to the irrigation in agricultural properties. The experiment was done in the city of Toledo/PR, in two different properties, one with its activities directed to the bovine culture of milk with 130 animals in a regimen of confinement and the other property with its activities directed to the swine culture, working as a pig producer unit with a breeding of 1,000 breeders. Both of the properties use biodigestors to the treatment of the generated effluents and they have as byproducts the biogas and the biofertilizer. To establish the consumption of biogas per HP/hour it was used a compressor to supply a bag named gas-tank. With the amount of biogas known inside the gas-tank, it was connected to the engines, which remained working until the consumption of all the biogas. To the biogas from the bovine culture the consumption was of 0,981 m3/HP/hour to the set of motor bomb and of 2,77 m3/HP/hour to the set of motor generator, while that for the biogas from swine culture the consumption was of 1,113 m3 /HP/hour and 0,791 m3/HP/hour to motor generator and motor bomb respectively. The efficiency to the power production was of 4.14% to the biogas from bovines and of 10,3% to the biogas from swines. Considering the time of amortization of 10 years, the cost of the biogas was of R$ 0,229 / m3 for bovines and of 0,063 / m3 for swines. The cost of the electrical power generated is related to the applying of the capacity of the plan and to the cost of biogas, to the biogas from the bovine culture the cost of the generated power was of R$ 465,07/MWh and to the biogas from swine culture the cost was of R$ 90,86/MWh, considering that both of the plans be operating fir 10 hours a day. The time of return for the investment depends on the initial investment and on the price of the electric power charged by the power company, with a tariff of R$ 300,00/MWh operating the generation system for four hours a day and considering the economy generated with the irrigation system, the time of return found was of 4.3 and 6.7 years to bovines and swines respectively. Besides that, the biofertilizer generated from bovines can fertilize 37 hectares a year and the biofertilizer generated from swines can fertilize 480 hectares a year. Despite the low levels of efficiency to power generation, the time of investment return is reasonable and it can become shorter if the economy generated by the use of the biofertilizer is considered.
O presente trabalho teve por objetivo avaliar a viabilidade do uso do biogás proveniente das atividades de bovinocultura de leite e suinocultura em conjuntos motor gerador e motor bomba para irrigação em propriedades rurais. O experimento foi realizado no município de Toledo/PR, em duas propriedades, uma com as atividades voltadas para bovinocultura de leite com 130 cabeças em regime de confinamento e outra com as atividades voltadas a suinocultura trabalhando como unidade produtora de leitões com um plantel de 1.000 matrizes. Ambas as propriedades utilizam biodigestores para tratamento dos efluentes gerados e tem como subprodutos o biogás e o biofertilizante. Para determinar o consumo de biogás por HP/hora foi utilizado um compressor para abastecer uma bolsa denominada de gasômetro. Com a quantidade de biogás conhecida dentro do gasômetro o mesmo foi conectado aos motores que permaneceram em funcionamento até consumir todo biogás. Para o biogás da bovinocultura o consumo foi de 0,981m³/HP/hora para o conjunto motor bomba e de 2,77m³/HP/hora para o conjunto motor gerador, enquanto que para o biogás de suinocultura o consumo foi de 1,113m³/HP/hora e 0,791m³/HP/hora para gerador e bomba respectivamente. A eficiência para produção de energia foi de 4,14% para o biogás de bovinos e de 10,3% para o biogás de suínos. Considerando o tempo de amortização de 10 anos o custo do biogás foi de R$ 0,229 por m³ para bovinos e de R$ 0,063 por m³ para suínos. O custo da energia elétrica gerada está em função do aproveitamento da capacidade da planta e do custo do biogás, para o biogás da bovinocultura o custo da energia gerada foi de R$ 465,07 por MWh e para o biogás de suinocultura o custo foi de R$ 90,86 por MWh considerando que ambas as plantas estejam operando durante 10 horas diárias. O tempo de retorno do investimento depende do investimento inicial e do valor da tarifa de energia elétrica cobrada pela concessionária, com uma tarifa de R$ 300,00 por MWh operando o sistema de geração por 4 horas diárias e considerando a economia gerada com o sistema de irrigação o tempo de retorno encontrado foi de 4,3 e 6,7 anos para bovinos e suínos respectivamente. Além disso, o biofertilizante gerado pelos bovinos pode fertilizar 37 ha/ano e o gerado pelos suínos 480 ha/ano. Apesar dos baixos níveis de eficiência para geração de energia o tempo de retorno do investimento é razoável e pode se tornar menor se for considerada a economia gerada pelo uso do biofertilizante.

Over that past three decades, power sector reform has been a key pillar of policy agendas in more than half of the countries across the world. This thesis specifically concerns the empirical investigation of the economic performance of the international electricity generation industry. Drawing on the stochastic frontier analysis techniques, the thesis considers the influence of reform as exogenous factors in shifting frontier technology as well as shaping inefficiency function directly -determinants and heteroscedasticity variables. The first essay uses an extensive panel dataset of 91 countries over the period 1980 to 2010 to measure the impact of deregulation on efficiency and total productivity growth using stochastic input distance frontier (SIDF). Three specific issues are addressed in the first essay: (1) the relationship between deregulation and technical efficiency, (2) the extent of the rank correlation of the country intercepts with deregulation via their position on the frontier, (3) the trend of total factor productivity and its components. We establish a positive impact of deregulation on efficiency and some compelling evidence suggesting that the country intercepts equally account for the influence of deregulation aside efficiency. In particular, the technical efficiency index from the first paper reveals that most OECD European countries are consistently efficient. Building on this finding, the second essay investigates the performance in term of cost efficiency for electricity generation in OECD power sector while accounting for the impact of electricity market product regulatory indicators. Empirical models are developed for the cost function as a translog form and analysed using panel data of 25 countries during the period 1980 to 2009. We show that it is necessary to model latent country-specific heterogeneity in addition to time-varying inefficiency. The estimated economies of scale are adjusted to take account of the importance of the quasi-fixed capital input in determining cost behaviour, and adjusted economies of scale are verified for the OECD generation sector. The findings suggest there is a significant impact of electricity market regulatory indicators on cost. Cost complementarity between generation and emissions found to be significant, indicating the possibility of reducing emissions without necessarily reducing electricity generation. Finally, the third essay examines the performance of electric power industry s using consistent state-level electricity generation dataset for the US contiguous states from 1998-2014. We estimate stochastic production frontier for five competing models in order to identify the determinants of technical inefficiency and marginal effects. We find evidence of positive impacts of deregulation on technical efficiency across the models estimated. Our preferred model shows that deregulated states are more efficient in electricity generation than non-deregulated states. The result of the marginal effects shows that deregulation has a positive and monotonic effect on the technical efficiency.

Within a production machine, various electromechanical and pneumatic structures can be used for drive tasks. As these drive technologies can often replace each other, the energy efficiency, performance and TCO of pneumatic drives must be permanently enhanced to remain competitive. There is a large number of known measures for the reducing their energy consumption, e.g. minimizing of filling volumes, energy saving circuits etc. However, these measures are mainly considered separately and the possible overall energy saving effect resulting from their combination is rarely taken into account. The main goal of this paper is therefore to explore the possible combinations of pneumatic energy saving measures and their cumulative saving effect. Due to the fact that some measures are mutually exclusive (e.g. a general pressure reduction in properly sized drive), each combination should be considered separately. To evaluate their efficiency plausibly, a comprehensive assessment is required that contains both the total cost of ownership analysis (TCO) and a mechanical properties assessment. The presented comprehensive approach of the task analysis can serve as example of how an optimal drive configuration for the specific task can be found, thus creating a basis for solving constructive challenges in designing of pneumatic automation systems.

Робота виконана в Тернопільському національному технічному університеті імені Івана Пулюя Міністерства освіти і науки України, м. Тернопіль. Захист відбудеться 25 грудня 2014 року на засіданні спеціалізованої вченої ради К. 58.052.04. у Тернопільському національному технічному університеті імені Івана Пулюя за адресою: 46008, Україна, м. Тернопіль вул. Білогірська, 50. З дисертацією можна ознайомитись у бібліотеці Тернопільського національного технічного університету імені Івана Пулюя за адресою: 46001, м. Тернопіль, вул. Руська, 56.
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.07 – світлотехніка та джерела світла. Тернопільський наці-ональний технічний університет імені Івана Пулюя, Тернопіль 2014. Дисертація присвячена розвитку науково-технічних основ оцінки енерго-ефективності джерел світла та освітлювальних установок, побудованих на їх основі. Доведено, що найбільш достовірним методом оцінки енергоефективності джерел світла, незалежно від фізичних принципів їхньої дії, є метод, оснований на оцінці енергоефективності за питомою вартістю одиниці світлової енергії, ви-робленої джерелом світла за середню тривалість його світіння. Запропоновано аналітичний вираз для розрахунку економії електричної енергії для будь-яких функціональних залежностей регулювання світлового по-току джерел світла. Доведено, що динаміка перехідного процесу спаду світло-вого потоку напівпровідникових джерел світла від моменту ввімкнення до пе-реходу в усталений режим, а також протягом експлуатації в межах середньої тривалості світіння, з достатньої для практики точністю описується різницею падаючої і зростаючої експоненціальних функцій з різними сталими часу та сталими інтегрування. Доведено, що одночасне зменшення діаметру розрядної трубки і струму, що протікає через люмінесцентну лампу, призводить до суттєвого зростання відносних значень напруги на лампі, обмежуючи можливості виготовлення по-тужних ЛЛ для електричних мереж промислової частоти напругою 220-240 В. Запропоновано концепцію конструювання безблискісних світлодіодних світильників. Доведено, що автомобільні дороги найкраще освітлювати золоти-сто-жовтим світлом РЛВТ типу ДНаТ, а пішохідні переходи додатково ще й спеціалізованими світлодіодними освітлювальними приладами.
Диссертация на соискание ученой степени кандидата технических наук по специальности 05.09.07 – светотехника и источники света. – Тернопольский национальный технический университет имени Ивана Пулюя, Тернополь, 2014. Диссертация посвящена развитию научно-технических основ оценки эне- ргоэффективности источников света и осветительных установок, построенных на их основе. Доказано, что наиболее достоверным методом оценки энергоэф- фективности источников света, независимо от физически принципов их работы, является метод, основанный на оценке энергоэффективности по удельной стои- мости единицы световой энергии, выработанной источником света за среднюю продолжительность его свечения. Разработана математическая модель для расчета достоверних значений экономии электрической энергии для любых функциональных зависимостей регулирования светового потока источников света. Доказано, что динамика пе- реходного процесса спада светового потока полупроводниковых источников света от момента включения до перехода в установившийся режим, а также в течение эксплуатации в пределах средней продолжительности свечения, с до- статочной для практики точностью описывается разницей спадающей и возрас- тающей экспоненциальных функций с различными по величине постоянными времени и постоянными интегрирования. Доказано, что одновременное уменьшение диаметра разрядной трубки и тока через люминесцентную лампу приводит к существенному росту относи- тельных значений напряжения на лампе, ограничивая возможности изготовле- ния мощных ЛЛ для электрических сетей промышленной частоты напряжением 220-230 В. 19 Предложена концепция конструирования безблесткостных светодиодных светильников. Доказано, что автомобильные дороги лучше всего освещать зо- лотисто-желтым светом РЛВД типа ДНаТ, а пешеходные переходы дополни- тельно еще и специализированными светодиодными осветительными прибора- ми.
Thesis for a Candidate Degree in Technical Sciences, Speciality 05.09.07 – Light Engineering and Light Sources. – Ternopil Ivan Pul'uj State Technical University, Ternopil, 2014. The thesis deals with the development of scientific and technical bases of assessment of light sources and lighting settings’ energy efficiency manufactured on their basis. It has been proved that the most reliable, comprehensive and scientifically sound evaluation method of energy efficiency of light sources regardless of physical principles of their functioning is the method based on the assessment of energy efficiency by the specific cost per unit of light energy produced by a light source within an average duration of its luminescence. That is caused by the fact that in estimating there has been taken into account the maximum possible number of available parameters (the cost of light sources and the minimum of start-control devices necessary for them, the power of light sources, luminous efficiency of a light sources set plus start-control devices and an average duration of glow) which influence energy efficiency in the greatest degree. There has been developed a mathematical model for calculating realistic values of electrical еnergy savings for any functional dependencies of luminous flux light sources regulation, taking into account the power losses in electromagnetic ballast chokes. It has been proved that the dynamics of the transition process of semiconductor light sources’ luminous flux decrease from the moment of switching to the moment of transition into a steady mode, as well as within an average duration of glow, is described (with accuracy sufficient for practical purposes) by the difference of decreasing and increasing exponential functions of constants of time and integration of various magnitude, which made it possible: a) to evaluate the contribution of each transient thermal resistance (light emitting diode-radiator, radiator-environment) to the process of the excessive heat transfer from a driver and LEDs to the environment; b) to suggest a method of determining an optimal value of nominal current generated on the basis of LED lighting products in terms of providing a necessary magnitude of an average duration of glow; c) to determine the amount of light energy generated within any pre-specified period of time. 20 Based on the analysis and generalization of the obtained and published experi- mental data there has been constructed an mathematical model of electrical and lighting parameters of semiconductor light sources in the form of system equations, which made it possible to determine their energy efficiency in the process of luminous flux regulation. There has been introduced the concept of spatial pulsations of the luminous flux which made it possible: a) to formulate the requirements for the rational distribution in rooms of two and four lamp fixtures made under a split phase scheme for the network power frequency of 50 Hz; b) to explain the causes for the increase (decrease) of the luminous flux pulsation coefficient of white light from heat and discharge light sources in passing through bulbs of coloured light sources or coloured filters. It has been proved that a simultaneous decrease of the discharge tube diameter and the current through a fluorescent lamp leads to a significant increase in the relative values of voltage in a lamp (due to the increase of the potential gradient in a positive pillar of discharge) limiting the possibility of manufacturing not only powerful low-pressure discharge lamps, but also the increase of the luminous efficiency and operation in a chain of an industrial network with electromagnetic start-control devices. There has been set forward the concept of designing anti-glare light emitting diodes luminaires based on multicomponentness, namely the transition from general to zonal lighting, from the category of "lamp" to the category of "lighting apparatus", from powerful to small and medium-power LEDs with light beams redirection by means of reflective systems and secondary optical lens to avoid hyper-brightness cells formation. It has been proved that highways are better illuminated by golden-yellow light of high intensity discharge lamps of the high-pressure sodium vapor type while pedestrian crossings – by additional specialized LED lighting fixtures that would operate only in the periods when at a pedestrian crossing area there will be both vehicles and pedestrians (a pedestrian), which will make it possible not only to increase the energy efficiency of lighting settings, but also to reduce the number of traffic accidents involving pedestrians. It has been found out that for light sources with continuously declining dependency of energy efficiency the regulation of the luminous flux in terms of the normalized specific cost per unit of light energy produced by a light source in the process of dimming the best mode of exploitation is the on-off one based on the usage of presence sensors.

The diploma thesis on „Optimizing of shopping center energy demands“ deals with the reduce of the energy demand of the shopping center. The theoretical part describes the possibilities of reducing the energy intensity in terms of renewable resources, the potential of renewable resources. In practical part the energy audit of the existing building is designed, then the possibilities of reducing the energy intensity of the building, the budget and expressed return on investment by means of the net present value, the internal rate of return and simple payback period.

Dans le chapitre 1, j’examine les résultats des fusions entre producteurs européens d’énergie en termes d’efficacité. Je calcule l’éco-efficacité en utilisant l’analyse de l’enveloppement des données et l’indice de productivité Malmquist-Luenberger. Je trouve que les fusions horizontales nationales, qui sont soigneusement réglementées, n’ont pas d’impact. Les fusions horizontales transfrontalières nuisent à l’éco-efficacité à court terme mais la stimulent deux ans après l’achèvement. Les fusions verticales nuisent à l’éco-efficacité. Je présente des suggestions de politiques concernant la réglementation des fusions. Le chapitre 2 est un travail conjoint avec Julian Hinz. Nous enquêtons sur les effets de l’embargo russe auto-imposé sur les importations de produits alimentaires en provenance des pays occidentaux. Nous construisons un modèle ricardien avec des liens sectoriels, des échanges de biens intermédiaires et une hétérogénéité sectorielle dans la production. L’étalonnage du modèle avec des données réelles permet de simuler les résultats de l’embargo en termes de changements de bien-être et de prix. Nous quantifions en outre l’impact sur les prix à la consommation en Russie à l’aide de la méthode des doubles différences. Le chapitre 3 est basé sur un article co-écrit avec Cristina Herghelegiu. Nous enquêtons sur l’utilisation des conditions commerciales internationales (Incoterms). Ce sont les schémas prédéfinis de la répartition des coûts et des risques entre les acheteurs et les vendeurs. Nous nous appuyons sur un ensemble de données très détaillées sur les exportations russes durant la période 2012-2015. Nous constatons que les grandes entreprises sont plus susceptibles d’assumer des responsabilités. Les gros acheteurs assument plus de responsabilités, quelle que soit la taille du vendeur, alors que les gros vendeurs le font uniquement lorsque leur partenaire est petit. C’est plus probable que les risques et les coûts sont sur les acheteurs dans les transactions de biens intermédiaires et de biens d’équipement
In Chapter 1 I investigate firm-level efficiency outcomes of mergers between the European energy producers. I compute eco-efficiency using data envelopment analysis and the Malmquist-Luenberger productivity index. I find that carefully regulated domestic horizontal mergers do not have a statistically significant impact. Cross-border horizontal mergers hamper eco-efficiency in the short run but stimulate it two years after completion. Vertical mergers are detrimental to eco-efficiency. I put forward policy suggestions regarding the regulation of mergers. Chapter 2 is joint work with Julian Hinz. We investigate the effects of self-imposed Russian embargo on food import from Western countries. We build a Ricardian model with sectoral linkages, trade in intermediate goods and sectoral heterogeneity in production. The calibration of the model with real data allows to simulate the outcomes of embargo in terms of changes in welfare and prices. We further quantify the impact on consumer prices in Russia with the difference-in-differences estimator. Chapter 3 is based on a paper co-written with Cristina Herghelegiu. We investigate the use of International Commercial Terms. They are pre-defined schemes of repartition of costs and risks between buyers and sellers, which serve to mitigate the uncertainty. We rely on a highly detailed dataset on Russian exports over the 2012-2015 period. We find that big firms are more likely to take on responsibilities. Big buyers bear more responsibilities regardless of the seller size, whereas big sellers do so only when their partner is small. Risks and costs are more likely on buyers in transactions of intermediate and capital goods

博士
國立交通大學
資訊科學與工程研究所
106
In this dissertation, two-dimensional (2-D) VLSI digital filter architectures possessing various symmetries in the filter magnitude response are studied for the first time. For this purpose, Type-1, Type-2, and Type-3 power-efficient and cost-effective 2-D magnitude symmetry filter architectures possessing diagonal, four-fold rotational, quadrantal, and octagonal symmetries with reduced number of multipliers are given. For each Type (1-3), four structures incorporating each of the above symmetries are presented. In all 12 single symmetry structures are studied. Further, two power-efficient and cost-effective multimode 2-D symmetry filters are given. By combining the identities of four each of the Type-1 and Type-3 symmetry filter structures, the proposed Type-1 and Type-3 multimode 2-D symmetry filters can provide four different operation modes: diagonal symmetry mode (DSM), four-fold rotational symmetry mode (FRSM), quadrantal symmetry mode (QSM), and octagonal symmetry mode (OSM). Besides, the symmetry filter architectures using delta operator are also proposed for better numerical accuracy and lower coefficient sensitivity in narrow-band filter designs. According to ASIC implementation flow, Synopsys Design Compiler is employed to synthesize the Type-1 2-D filter designs in RTL level and Cadence SOC Encounter is adopted for placement and routing (P&R) in TSMC 0.18um. The power dissipation implementation result is measured via Synopsys PrimePower. The Type-1 diagonal, four-fold rotational, quadrantal, and octagonal symmetry filter structures can attain power savings of 16.77%, 36.30%, 22.90%, and 37.73% with respect to that of the conventional 2-D filter design without symmetry. On the other hand, the Type-1 DSM, FRSM, QSM, and OSM modes can reduce power consumption by 11.01%, 31.42%, 17.53%, and 35.26% compared with that of the conventional 2-D filter design. The Type-1 multimode filter can result in 63.25% area reduction compared with the sum of the areas of the four individual Type-1 symmetry filter structures. Besides, we also provide Type-2 and Type-3 symmetry filter architectures with different structures and shorter critical paths.

Many embedded applications implement block ciphers and sorting and searching algorithms which use multiple loop iterations for computation. These applications often demand low power operation. The power consumption of designs varies with the implementation choices made by designers. The sequential implementation of loop operations consumes minimal area, but latency and clock power are high. Alternatively, loop unrolling causes high glitch power. In this work, we propose a low area overhead approach for unrolling loop iterations that exhibits reduced glitch power. A latch based glitch filter is introduced that reduces the propagation of glitches from one iteration to next. We explore the optimal number of filters to be inserted for different applications that give a good balance between area and power. We also implement partial unrolling with glitch filters. This approach consumes less area while still giving energy savings comparable to the fully unrolled implementation. Our approach is targeted to Xilinx and Altera FPGAs. We simulate different implementation choices and compare energy results to evaluate the savings. We demonstrate our approach on SIMON-128 and AES-256 block ciphers and a sorting algorithm. We prototype our design on Xilinx Artix-7 and Altera Cyclone-IV-GX FPGA development boards and measure the actual power savings. Results show up-to 90% dynamic energy reduction in Xilinx designs, and 97% reduction in Altera designs with our glitch filtering approach due to glitch power reduction.

碩士
國立臺灣科技大學
企業管理系
101
Traditional industrial economics assume that highly oligopolistic industry firms were able to gained excess profits due to firm collusion（Bain, 1951, 1956）. The efficiency hypothesis（Demsetz, 1973, 1974）argues that the excess Economic rents gained by the highly oligopolistic industry firms were due to the higher efficiency of large firms. However, the highly oligopoly market firms may have better cost efficiency, but they may also abuse market power（Martin, 2006, pp.148-149）. This paper used the industry econometric model developed by Azzam（1997）to evaluate the potential market power and cost efficiency that the cement industries in Taiwan may have. This study used the data collected from January of 2001 to December of 2011 from the cement industries in Taiwan. Empirical results indicated that if the market concentration increases by 1%, the firms will be able to increase the market price by 0.49% due to the increased in market power. However, at the same time, this phenomenon will cause a 0.48% decrease in market price due to the increased in cost efficiency. Therefore, the overall conclusion is, with 1% increase in market concentration will only increases the market price by 0.01%.

碩士
朝陽科技大學
資訊工程系碩士班
93
In designing an embedded system, three issues -- hardware cost, system performance, and power consumption -- have to be taken carefully into consideration. We present an embedded system design which is cost-efficient and which considers performance and power consumption based on the frequency with which instructions are executed. We use the locality of running programs to optimize the use of memory space, system performance, and power consumption; that is, we compress infrequently executed codes to save the use of memory space but compress (encode) frequently executed codes to power consumption and maximize performance. According to the locality of executed programs, 90% execution time is used by 10% of the static object codes. As a result, we compress 90% of the static object codes to obtain our main data compression ratio to reduce the use of memory space. However, performance and power consumption are relevant to execution process, so we compress 10% of the frequently executed object codes to improve both performance and power consumption by reducing the number of memory access times. We encode the frequently executed instructions as shorter code words and then we pack continuous code words into a pseudo instruction. Once the decompression engine fetches one pseudo instruction, it can extract multiple instructions. Therefore, memory access can be efficiently reduced because of space locality. We also propose a multiple look ahead table method that solves the problem of big codeword sizes. This problem arises due to the reduction in instructions from one-time memory access which occurs because the great amount of frequently executed instructions. From our simulation results, our method with one 256-instruction reference table does not increase the compression ratio, and the ratio of the power consumption can be reduced by about 47.23% than compressing all instructions. However, when one 512-instruction reference table is used, the ratio of the power consumption is reduced by 37.25% only. When two reference tables that contain 256 instructions in each table are used, the power consumption can be improved by 49.36%; that is, using two 256-instruction reference table makes 12.11% less power consumption than using one 512-instruction reference table. According to the simulation results, our proposed methods based on the frequencies of executed instructions result in low power consumption, performance improvement and reduced memory space.

Light bulbs play an indispensable role in our lives as they provide unhindered ability to see the world even during the night. Efficiency of light bulbs is becoming increasingly important, and through this experiment, light bulb efficiencies are analyzed from measurements of relative light intensity and power input of various bulbs. Furthermore, this report is aimed to increase awareness of the efficiency advantage in fluorescent bulbs and to encourage their usage in the interest of conserving energy.

碩士
國立中興大學
精密工程學系所
104
This study focused on using chemical selective etching (CSE) to fabricate GaAs thin-film solar cells and discussed their characteristics. Additionally, the technique of the recyclable GaAs substrate was developed and realized. This was not only able to obtain a high efficiency solar cell, but also reduce the fabrication cost. All GaAs solar cells were applied to mobile power packs for comparing their device performance. Under CSE process, the AlAs was regarded as a sacrificial layer, which was be etched to assist in the separation of the solar cell epilayer from GaAs substrate. Then the GaAs substrate could be recycled for the next usage as a growth template. The finishing time of completely separating the whole epilayer from four-inch GaAs cell was about 6-10 hours. Thin film solar cells can be transferred to Ni substrate with high thermal dissipation and light weight by means of CSE process. On the other hand, the recycled GaAs substrate was cleaned by the mixture solution of hydrogen peroxide and ammonia and the mixture solution of phosphoric acid and hydrochloric acid, and then it could be reused for the solar cell epitaxial growth by metal-organic chemical vapor deposition. Afterwards, this thin film solar cell was coated with the n-type electrode and an anti-reflective layer to increase the optical path for enhancing the photocurrent. This thesis composed three parts. First of all, the influences of different skills including bending and unbending temporary substrates on the characteristics of solar cells were discussed. In the second part, four different areas of solar cells were designed, such as 0.03 cm2, 0.25 cm2, 0.64 cm2, and 1 cm2, respectively. In addition, the effects of distinct materials of anti-reflective layers and two kinds of base layer thicknesses on the characteristics of devices were also explored. Finally, the GaAs-based solar cells were actually used to fabricate a module of portable power source. Furthermore, the performance of the portable power source constructed by GaAs-based solar cell was compared with that built by commercial Si-based solar cells.

碩士
國立交通大學
管理科學研究所
82
@　 衡量電廠營運效率的方法很多，而研究單位發電成本，即發出一瓩小 時電的成本，作為評估依據堪稱最具體，但限於電力系統營運之特性，若 僅以電廠實際成本為研究範圍，則失之主觀，故在100%可用率下發電量所 計算出之可用成本來衡量應較具代表性，因此將單位發電成本再細分為基 本成本、不可用成本及調度成本做為探討電廠營運效率的依據，以利於分 析及解釋個別電廠單位發電成本之增減。 @　 本研究之方法是從生產面 考量，總生產力為總產出對總投入之比值，此比值愈高表示效率愈好，單 位發電成本為總投入對總產出之比值，亦即在同一期間電廠之營業費用與 發電量之比值，是總生產力的倒數，故此比值愈低代表效率愈好，並依會 計成本法的資料，經由投入項與產出項之適當調整及12個月移動平均數法 的處理，建立單位發電成本趨勢模型，再將所選用電廠之相關資料代入模 型中以計算出各項成本，並以可成本為因變數，可用率、淨廠效率及不含 燃料費之營業費用為自變數，且加入虛擬變數來建立多元線性迴歸模型， 用以解說可用成本變動的影響因素及其對燃油燃煤間影響之差異程度，亦 即影響電廠營運效率的因素及其差異程度，做為電廠營運的參考。 @　 評估模型建立後，本論文特以台電公司HH廠及HT廠作實証研究，以多元線 性迴歸方法處理該模型所得之可用成本資料，得迴歸函數之估計式為 CAB = 212.602 - 0.2265 AVA-2.8887 EFF + 0.161 EXP-14.327 DUMMY- 0.1901 DAVA. 發現在相同的條件下(即可用率、淨廠效率及不含燃料費之 營業費用相同)，燃油比燃煤電廠之可用成本為高且有顯著的差異，又可 用成本受可用率的影響將因燃油或燃煤電廠而有顯著差異，即可用率每增 加一單位其影響可用成本之差異為 0.19分/每度。淨廠效率及不含燃料費 之營業費用對可用成本的影響，燃油或燃煤電廠間沒有顯著差異。

This Master of Laws dissertation is a treatise of “The efficacy of Alternative Dispute Resolution (ADR) in labour disputes: a critical comparative analysis of Botswana, South Africa (RSA) and Zimbabwe.” Alternative Dispute Resolution hereinafter referred to as (“ADR”) has attracted so much research ado worldwide with policy makers alive to its possibilities in so far as it ought to shed off the burden of the courts in handling disputes. Courts are considered inundated with unresolved cases taking many years to finalise. ADR is therefore touted, not only the panacea, but the cheaper, efficient and effective alternative to normal court process. This study was saddled with the common challenges of definition, scope and methodology as does most scientific studies, especially to locate the concept ADR in the plethora of views from prominent exponent-s of the discipline. This study labored on the considered view that ADR is essentially an ‘out of court settlement approach to dispensing with disputes involving an attempt by disputants to rope in an impartial third party to aid finality to the respective wrangle. The lack of a methodological approach to treat this subject matter, made this study more challenging. The study had to therefore rely on a hypothetical model developed after gleaning through various scholarly views 1 that sought to treat the subject of ADR efficacy in labour dispute resolution. The study contented with the strongly held view 2 that ADR is an efficacious approach in resolving disputes outside the court system. As to whether this was the case in Botswana, RSA and Zimbabwe in so far as labour dispute resolution is concerned was the major challenge this study was seized with? A model was formulated which envisaged that efficaciousness of ADR may be achieved if three conditions or criteria are present within a jurisdiction, namely (1) ADR Background Conditions that comprise (a) adequate legislative and political support; (b) Supportive institutional and cultural norms, (c) adequate and competent manpower, (d) sufficient funding support, and (e) power-parity of disputants; (2) ADR Program Design comprising of (a) Planning and preparation and (b) Operations and implementation and finally (3) ADR Measures (a) Client satisfaction; (b) Time efficient; (c) Cost saving and (d) Settlement & enforcement. This study measured the situations obtaining in the three countries using these three-pronged criteria. In all three measures3 this study found that although all the three countries still have a long way before their ADR became as efficacious as would be reasonably possible, RSA has made many strides such as legislative enactments immediately upon attaining independence that sought to address the injustices of the past and thereby installing structures for enforcing industrial democracy 4, while Botswana and Zimbabwe took 5 years 5 and over 10 years 6 respectively after attaining independence. RSA established an independent body for dispensing with labour dispute settlement7 while Botswana8 and Zimbabwe 9 are still reluctant to do so, relying rather on their labour ministries often marinated in bureaucratic bottlenecks hence stalling efficacy of ADR. While RSA makes effort to provide adequate and competent manpower because of sufficient funding, Botswana and Zimbabwe still struggle to dispense with disputes under their labour departments who are either inadequately skilled or also accused of favouritism in the case of Zimbabwe.10 All the three countries are regarded as unequal societies which tends to sway the power-parity of disputants with capitalists still wielding unbridled powers in dispute outcomes. South Africa enacted section 143 to the Labour Relations Act 11 which empowers the Director of CCMA to certify an arbitral award, giving it the same force as an order of the Magistrate Court. This has cut off the time and administrative burden of having to register an arbitral award with the court so as to obtain writs of executions and enforce it, a practice which is still prevalent in Zimbabwe. The Department of Labour in South Africa has made funding available to the CCMA to assist employees who are not in a financial position to enforce awards in their favour.12 The funding is aimed at employees who are too indigent to afford the costs of enforcement.13 These employees are deemed to be: (a) Employees who earn below the earnings threshold (currently at R205 433.30 per annum) – proof of income will be required by the CCMA. There is no record regarding enforcement or ease of enforcement of ADR outcomes in Botswana and Zimbabwe or at least this study is aware of. The governments of Botswana and Zimbabwe have been accused of using a heavy hand in determining wages, the right to strike and often curtailing union power through declaring certain sectors essential services. RSA’s Commission for Conciliation, Mediation and Arbitration hereinafter after referred to as (the “CCMA”)14 runs an electronic system of case management by which cases are screened and assigned commissioners whereas Zimbabwe and Botswana still rely on manual systems often inefficiently managed especially when it comes to allocating matters to ADR interventionists.15 In Zimbabwe the challenge of resources is acute often the Labour Officers lacking a simple photocopier and postage stamps to dispense with administration of disputes. This dissertation found that Botswana and Zimbabwe lack publicly available information from which to infer the efficaciousness of ADR practices therein. Measuring client satisfaction, efficiency and cost effectiveness, enforcement and settlement has not been tackled with ease, which was different when it came to RSA. This study argues that RSA’s ADR is efficacious rated at 75% attainment of settlement of disputes, despite accusations of failing to offer disputants options and job retention at the end of ADR intervention. Botswana and Zimbabwe on the measures raised above are not yet close to achieving efficaciousness based on the above criteria. The challenges need to be addressed to ensure that in all three measures ADR affords Botswana, RSA and Zimbabwe disputants a cheaper, efficient and effective alternative to dispensing with labour disputes. This study concluded with recommendations arising from the three measures ADR Background Conditions; ADR Program Design and (3) ADR Measures could be implemented towards achieving an efficacious ADR regime for the three countries and beyond.
Mercantile Law
LL.M.

We consider a class of periodic preventive maintenance (PM) optimization problems, for a single piece of equipment that deteriorates with time or use, and can be repaired upon failure, through corrective maintenance (CM). We develop analytical and simulation-based optimization models that seek an optimal periodic PM policy, which minimizes the sum of the expected total cost of PMs and the risk-averse cost of CMs, over a finite planning horizon. In the simulation-based models, we assume that both types of maintenance actions are imperfect, whereas our analytical models consider imperfect PMs with minimal CMs. The effectiveness of maintenance actions is modeled using age reduction factors. For a repairable unit of equipment, its virtual age, and not its calendar age, determines the associated failure rate. Therefore, two sets of parameters, one describing the effectiveness of maintenance actions, and the other that defines the underlying failure rate of a piece of equipment, are critical to our models. Under a given maintenance policy, the two sets of parameters and a virtual-age-based age-reduction model, completely define the failure process of a piece of equipment. In practice, the true failure rate, and exact quality of the maintenance actions, cannot be determined, and are often estimated from the equipment failure history. We use a Bayesian approach to parameter estimation, under which a random-walk-based Gibbs sampler provides posterior estimates for the parameters of interest. Our posterior estimates for a few datasets from the literature, are consistent with published results. Furthermore, our computational results successfully demonstrate that our Gibbs sampler is arguably the obvious choice over a general rejection sampling-based parameter estimation method, for this class of problems. We present a general simulation-based periodic PM optimization model, which uses the posterior estimates to simulate the number of operational equipment failures, under a given periodic PM policy. Optimal periodic PM policies, under the classical maximum likelihood (ML) and Bayesian estimates are obtained for a few datasets. Limitations of the ML approach are revealed for a dataset from the literature, in which the use of ML estimates of the parameters, in the maintenance optimization model, fails to capture a trivial optimal PM policy. Finally, we introduce a single-stage and a two-stage formulation of the risk-averse periodic PM optimization model, with imperfect PMs and minimal CMs. Such models apply to a class of complex equipment with many parts, operational failures of which are addressed by replacing or repairing a few parts, thereby not affecting the failure rate of the equipment under consideration. For general values of PM age reduction factors, we provide sufficient conditions to establish the convexity of the first and second moments of the number of failures, and the risk-averse expected total maintenance cost, over a finite planning horizon. For increasing Weibull rates and a general class of increasing and convex failure rates, we show that these convexity results are independent of the PM age reduction factors. In general, the optimal periodic PM policy under the single-stage model is no better than the optimal two-stage policy. But if PMs are assumed perfect, then we establish that the single-stage and the two-stage optimization models are equivalent.
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