Dissertations / Theses: 'Double efficiency'

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Muhic, Dino. "Improved energy efficiency in double disc chip refining." Licentiate thesis, Mittuniversitetet, Institutionen för naturvetenskap, teknik och matematik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-12979.

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The electrical energy consumption in thermomechanical pulping (TMP) is very high, in the range of 2 – 3 MWh/adt depending on process solution and on the product quality specifications for the paper product. Both pulpwood and energy prices have increased rapidly for some time. Due to this, the main focus of the research and development is on ways to reduce the electrical energy consumption in wood chip refining. As a step towards a more energy and cost ‐ effective refining process, Holmen Paper AB has invested in a new mechanical pulping process at its Braviken mill. In this case the primary refining stage consists of high consistency (HC) double disc refiners ‐ RGP68DD (machines with two counter rotating discs). Earlier studies on the refining conditions, such as intensity and temperature, have indicated that it should be possible to improve the energy efficiency in double disc refining while maintaining the functional pulp properties such as tensile index. The main goal of this project was to improve the energy efficiency in double disc chip refining with 150 kWh/adt to corresponding pulp properties as measured on pulp samples after refiner. In order to further improve the basic understanding of what happens to the wood fibre material when changing the process conditions, the morphological and ultrastructural changes of fibres were also studied. This part of the research work was performed in cooperation with the research program; Collaborative Research on the Ultrastructure of Wood Fibres (CRUW). This licentiate project is a part of a large development project where different techniques to improve the energy efficiency has been evaluated by means of mill scale trials at the Holmen Paper Braviken Mill. The high consistency double disc chip refining part of the project was financed by The Swedish Knowledge Foundation, Metso Paper and Holmen Paper, in cooperation with FSCN (Fiber Science & Communication Network) at Mid Sweden University. The trials were made on one of the TMP lines at the Holmen Paper Braviken mill with Norway spruce as raw material. The influence of increased specific refining energy on pulp properties were studied at different refining temperatures, refining intensity, pulp consistency and production rate. Results from these trials were later validated by means of long term trials. Intensity models and simulations for intensity changes by new segment design were made by Juha‐ Pekka Huhtanen from Tampere University of Technology, Finland. The results show that the specific energy consumption to same tensile index can be improved by means of increasing the refining pressure/temperature. The energy efficiency was improved by 80 ‐150 kWh/adt depending on load and the inlet‐ and housing pressure. The largest relative specific energy efficiency improvement was reached at low specific energy consumption levels. Similar fibre surface ultrastructure characteristics are gained by pulps with high pressure/temperature and low specific energy consumption compared to low pressure/temperature and high specific energy consumption pulps. High pressure/temperature and high specific energy consumption resulted in significantly increase in the delamination/internal fibrillation of pulp fibres. The surface ultrastructure of these fibres exhibited exposed S2 layer with long ribbontype fibrillation compared to pulps produced with lower temperature and lower specific energy consumption. When the refiner was operated at high pressure, the tensile index was preserved over the whole plate life. The specific light scattering coefficient increased with increasing pressure/temperature. A reason for this could be increased intensity caused by decreased plate gap. Increased intensity by means of refiner segment design changes resulted in large specific light scattering coefficient increase at similar tensile index, lower shives content, lower average fibre length and lower CSF at same specific energy consumption. The fresh steam consumption was reduced by the increased refiner ressure/temperature.
Den höga elenergiförbrukningen vid produktion av mekanisk massa har ställtkrav på mer forskning för att elenergieffektivisera raffineringsprocessen. Som ettsteg mot en mer energi‐ och kostnadseffektiv raffineringsprocess, har HolmenPaper AB investerat i en ny tillverkning av termomekanisk (TMP) massa vidBravikens pappersbruk. Dubbeldiskraffinörerna i den nya massalinjens primäraraffineringssteget studerades i detta projekt. Det finns goda indikationer på att enminskning av energiförbrukningen är möjlig genom att studerar och optimeraraffineringparametrar såsom intensitet och temperatur. Projektets huvudmål varatt energieffektivisera det primära dubbeldiskraffineringssteget med 150 kWh/adttill motsvarande massaegenskaper, så som dragstyrka, mätt på massa efterraffinör. Tillfälle gavs också till att studera morfologiska förändringar på fibrer föratt ytterligare förstå hur massa och fibrerna påverkas av dubbeldiskraffinering ochförändringar i raffineringssystemet.Detta licentiatprojekt är en del av ett större projekt där olika tekniker för attförbättra energieffektiviteten har utvärderats i industriell skala på Holmen PaperBravikens pappersbruk. Licentiatprojektet är finansierat av KK‐stiftelsen, MetsoPaper och Holmen Paper, i samarbete med Mittuniversitetet.Fullskaleförsök gjordes på en av TMP linjerna vid Bravikens pappersbruk, därgran används som råvara. Studien utfördes på dubbeldiskraffinörerna i detprimära raffineringssteget. Malkurvor, med ökande specifik raffineringsenergi,gjordes vid olika raffineringstemperaturer, intensitet, massakoncentration ochproduktion. Resultat som erhållits från malkurvorna bekräftades med längrestudier på raffinörerna. Intensitetsmodeller och simuleringar utfördes av Juha‐Pekka Huhtanen från Tampere University of Technology.De erhållna resultaten visar på att energiförbrukningen till ett visst dragindexkan minskas genom att öka raffineringstrycket/temperaturen. Medraffineringstryck menas inlopp och hustryck i raffinören. Energibesparingen är iintervallet 80‐150 kWh/adt. Den största förbättringen kan uppnås vid lågaenergiinsatser. Massor producerade med högt tryck och temperatur och lägrespecifik energiförbrukning uppvisar liknande ultrastrukturella ytegenskaper sommassor producerade med lågt tryck och temperatur och hög specifik energi. Högttryck och temperaturer med hög specifik energiinsats gav en signifikant förbättringav delaminering/intern fibrillering av massafibrer. Dessa fibrer uppvisadebildningar av långa band‐liknande fibriller från fibrernas S2 skikt, i jämförelse medmassor tillverkade med lägre tryck och temperatur och lägre specifik energi.5Om raffineringen genomförs vid högt tryck/temperatur bevaras dragindexunder hela segmentlivslängden.Den specifika ljusspridningskoefficienten påverkades positivt av ökat tryck ochtemperatur. En orsak till detta kan vara högre intensitet som orsakas av minskadmalspalt.Ökad intensitet genom förändrad segmentdesign leder till stora ökningar i denspecifika ljusspridningskoefficienten. Samtidigt uppnås samma dragindex, lägrespethalt, lägre genomsnittlig fiberlängd och CSF vid samma specifikaenergiförbrukning.Förbrukningen av färskångan sänktes vid tillämning av högre tryck ochtemperatur i raffinören.

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Cheng, HsienHui. "HIGH EFFICIENCY DOUBLE TWIST PANCHARATNAM PHASE OPTICAL BEAM DEFLECTORS." Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1437514337.

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Shabo, Jack, and William Schröder. "The Efficiency of Double-Decked Elevators : A comparison between single-decked and double-decked elevators in a skyscraper environment." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166475.

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The purpose of this study was to investigate the efficiency of double-decked elevators in a skyscraper environment. This was done by simulating elevator activity using different elevator types and elevator control algorithms. The results gained from the simulation suggested that double-decked elevators always provide better performance over using regular single-decked elevators. Some control algorithms proved to have up to ten times better efficiency compared to others using double-decked elevators.

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Li, Shang-Shiou. "A Protocol to Determine the Performance of South Facing Double Glass Façade System-A Preliminary Study of Active/Passive Double Glass Façade Systems." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/31802.

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This project proposes a protocol for experimentally determining the performance of a double glass envelope system. As a proof of concept, the protocol was applied to an experimental study of a south-facing, single story double glazed ventilated wall system. Two modular full-scale double glazed window models with naturally or mechanically assisted ventilation were constructed and monitored for a range of weather conditions. The goals of this investigation were to develop and apply the test protocol and to monitor and analyze the thermal performance of these two systems and to improve our understanding of the double façade system. Using this test protocol preliminary results show the average cavity heat removal rate is approximately 25% higher for the active system when compared to the naturally ventilated system. Also, the passive system has a higher temperature difference between the indoor glass surface and the indoor air than the active system. This experimental protocol can be further applied to determine other performance issues of the double envelope system.
Master of Science

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Zhang, Rui. "Smart Buildings| An Integrative Double Skin Facade Damper System for Safety and Energy Efficiency." Thesis, University of New Hampshire, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10688477.

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A smart building is an intelligent living space that elevates energy efficiency, comfort and safety. The word “smart” implies that the building would have a decision making system that can sense its conditions and reacts to them in an automatic and effective manner. Modem buildings contain many subsystems and, thus, to achieve automation, sophisticated sensing networks and robust control systems must be installed. The proposed research focuses on integrating several building systems—structural health monitoring (SHM), and structural and environmental controls—and explores synergy among them to improve efficiency and sustainability of buildings.

More specifically, an integrative, smart building system is developed by combining double skin façades and mass dampers in buildings to improve both safety and energy efficiency. Double skin façade systems protect and insulate buildings with two heavy glass layers between which air is allowed to flow for ventilation. By enabling movements in the outer façade skin, the façade can be used as a mass damper that reduces structural vibration and damage during earthquakes and wind storms. The added mobility also leads to innovative ways to control ventilation rate and improve energy efficiency by adjusting the gap size between the outer and inner skins.

In this dissertation research, the energy impact of the integrated system was first investigated. Then both passive and active structural control strategies were experimented and analyzed on a six-story shear building model. Results indicated the proposed system can significantly reduce structural response under the earthquakes excitations. In addition, the sensor networks and actuators introduced by the active structural control system were utilized for structural health monitoring purposes. The actuators provided harmonic excitations while the acceleration data were collected by the sensor networks to perform damage diagnosis.

Finally, since typical SHM systems require large networks of sensors that are costly to install, this dissertation research also examined using smartphones as alternative sensors. Using the aforementioned six-story experimental structure, a sensing system consisted of six smartphones was tested and proven effective in detecting structural damage. The experimental result demonstrates that further developments of smartphone SHM can lead to cost-effective and quick sensor deployments.

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Zhao, Zheng. "High Efficiency Single-stage Grid-tied PV Inverter for Renewable Energy System." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/27520.

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A single-phase grid connected transformerless photovoltaic (PV) inverter for residential application is presented. The inverter is derived from a boost cascaded with buck converter along with a line frequency unfolding circuit. Due to its novel operating modes, high efficiency can be achieved because there is only one switch operating at high frequency at a time, and the converter allows the use of power MOSFET and ultra-fast reverse recovery diode. This dissertation begins with theoretical analysis and modeling of this boost-buck converter based inverter. And the model indicates small boost inductance will leads to increase the resonant pole frequency and decrease the peak of Q, which help the system be controlled easier and more stable. Thus, interleaved multiple phases structure is proposed to have small equivalent inductance, meanwhile the ripple can be decreased, and the inductor size can be reduced as well. A two-phase interleaved inverter is then designed accordingly. The double-carrier modulation method is proposed based on the inverterâ s operation mode. The duty cycle for buck switch is always one if the inverter is running in boost mode. And the duty cycle for boost switches are always zero if the inverter is running in buck mode. Because of this, the carrier for boost mode is stacked on the top of the carrier for buck mode, as a result, there is no need to compare the input and output voltage to decide which mode the inverter should operate in. And the inverter operates smoothly between these two modes. Based on similar concept, three advanced modulation methods are proposed. One of them can help further improve the efficiency, and one of them can help increase the bandwidth and gain, and the last one takes the advantage of both. Based on similar concept, another three dual-mode double-carrier based SPWM inverters are proposed. With both step-up and step-down functions, this type of inverter can achieve high efficiency in a wide range because only one switch operates at the PWM frequency at a time. Finally, the simulation and experiment results are shown to verify the concept and the tested CEC (California Energy Commission) efficiency is 97.4%. It performs up to 2% more efficiently better than the conventional solution.
Ph. D.

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Gu, Bin. "Power Converter and Control Design for High-Efficiency Electrolyte-Free Microinverters." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/25236.

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Microinverter has become a new trend for photovoltaic (PV) grid-tie systems due to its advantages which include greater energy harvest, simplified system installation, enhanced safety, and flexible expansion. Since an individual microinverter system is typically attached to the back of a PV module, it is desirable that it has a long lifespan that can match PV modules, which routinely warrant 25 years of operation. In order to increase the life expectancy and improve the long-term reliability, electrolytic capacitors must be avoided in microinverters because they have been identified as an unreliable component. One solution to avoid electrolytic capacitors in microinverters is using a two-stage architecture, where the high voltage direct current (DC) bus can work as a double line ripple buffer. For two-stage electrolyte-free microinverters, a high boost ratio dc-dc converter is required to increase the low PV module voltage to a high DC bus voltage required to run the inverter at the second stage. New high boost ratio dc-dc converter topologies using the hybrid transformer concept are presented in this dissertation. The proposed converters have improved magnetic and device utilization. Combine these features with the converter's reduced switching losses which results in a low cost, simple structure system with high efficiency. Using the California Energy Commission (CEC) efficiency standards a 250 W prototype was tested achieving an overall system efficiency of 97.3%. The power inversion stage of electrolyte-free microinverters requires a high efficiency grid-tie inverter. A transformerless inverter topology with low electro-magnetic interference (EMI) and leakage current is presented. It has the ability to use modern superjunction MOSFETs in conjunction with zero-reverse-recovery silicon carbide (SiC) diodes to achieve ultrahigh efficiency. The performance of the topology was experimentally verified with a tested CEC efficiency of 98.6%. Due to the relatively low energy density of film capacitors compared to electrolytic counterparts, less capacitance is used on the DC bus in order to lower the cost and reduce the volume of electrolyte-free microinverters. The reduced capacitance leads to high double line ripple voltage oscillation on DC bus. If the double line oscillation propagates back into the PV module, the maximum power point tracking (MPPT) performance would be compromised. A control method which prevents the double line oscillation from going to the PV modules, thus improving the MPPT performance was proposed. Finally, a control technique using a single microcontroller with low sampling frequency was presented to effectively eliminate electrolyte capacitors in two-stage microinverters without any added penalties. The effectiveness of this control technique was validated both by simulation and experimental results.
Ph. D.

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Gopinath, Nirmala Rakesh. "Improving the Security and Efficiency of Blockchain-based Cryptocurrencies." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-210721.

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In recent years, the desire for financial privacy and anonymity spurred the growth of electronic cash and cryptocurrencies. The introduction of decentralized cryptocurrencies, such as Bitcoin, accelerated their adoption in society. Since digital information is easier to reproduce, digital currencies are vulnerable to be spent more than once – this is called a double-spending attack. In order to prevent double-spending, Bitcoin records transactions in a tamper-resilient shared ledger called the blockchain. However, the time required to generate new blocks in the blockchain causes a delay in the transaction confirmation. This delay, typically around one hour in Bitcoin, is impractical for real world trade and limits the wide-spread use of blockchain-based cryptocurrencies. In this thesis, we propose a solution to prevent double-spending attacks and thus enable fast transaction confirmations using the security guarantees of Trusted Execution Environments (TEEs). We achieve this by enforcing sign-once semantics that prevent the payer from reusing designated signing keys to sign more than one transaction. We also provide a way for the payee to verify whether a specific signing key is subject to sign-once semantics. The payee, however still receives the funds later, once the transaction is verified similarly to existing credit card payments. In this way, our solution reduces transaction confirmation times of blockchain-based cryptocurrencies and is also compatible with existing deployments since it does not require any modifications to the base protocol, peers, or miners. We designed and implemented a proof-of-concept of our solution using Intel SGX technology and integrated it with Copay, a popular Bitcoin wallet from BitPay. This thesis also presents the security evaluation of our system along with other possible extensions and enhancements.
De senaste åren har begäran efter sekretess och anonymitet för ekonomisk transaktioner sporrat tillväxten av elektroniska kontanter och kryptovalutor. Introducerandet av decentraliserade kryptovalutor, som t.ex. Bitcoin, har accelereratibruktagningen av dylika valutasystem. Digitala valutor är dock sårbara för dubbelspenderande (eng.double spending) eftersom digital information är lättare attreproducera. För att förhindra dubbelspenderande bokför Bitcoin valutatrans-aktioner i en distribuerad databas, den så kallade blockkedjan (eng.blockchain), som kan motstå förvanskling av bokförda transaktioner. Tiden som krävs för attgenerera nya block i Bitcoins blockkedja leder dock till en fördröjningen företransaktioner som skapas i databasen kan bekräftas. Denna fördröjning, som oftas varar kring en timme, är opraktisk för handel i verkliga världen och begränsardärför den allmänna spridningen av blockkedgebaserade kryptovalutor. I denna avhandlingen föreslår vi en lösningen som hindrar dubbelspenderandegenom att utnyttja säkerhetsgarantier hos anförtrodda exekveringsmiljöer (eng.Trusted Execution Environments). Vi åstadkommer detta genom att hindra beta-laren från att återanvända specifika kryptografiska nycklar för att digitalt signera flera transaktioner. Vi möjligjör också ett sätt för mottagaren att bekräfta ifall en kryptografisk underteckningsnyckel är skyddad på ovannämnda sätt. Mottagaren erhåller dock betalningen först senare, likt existerande kreditkortsbetalningar. Vår lösningen förminskar transaktionstiden för Bitcoin-betalningar på ett sätt som är kompatibelt med existerande användningssätt eftersom lösningen inte kräver modifikationer i grundläggande Bitcoin-protokollet. Vi utvecklade en prototyp av vår lösning genom att utnyttja Intel SGX teknologi och integrerade prototypen med CoPay, en popular plånboksapplikation för Bitcoin utveckald av företaget BitPay. Vi presenterar även en utvärdering av säkerheten i vårt system och beskriver möjliga utökningar och förbättringar.

This thesis is part of Erasmus Mundus 2-Year Masters NordSecMob program.

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Orlov, Anton [Verfasser], and Harald [Akademischer Betreuer] Grethe. "Carbon taxation in Russia : prospects for a double dividend and improved energy efficiency / Anton Orlov. Betreuer: Harald Grethe." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2013. http://d-nb.info/1042502714/34.

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Agell, Blenda. "Effect of Antibacterial Mouthwash on Basal Metabolic Rate in Humans : A Randomized, Double-blinded, Cross-over Study." Thesis, Linnéuniversitetet, Institutionen för kemi och biomedicin (KOB), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-30774.

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The use of mouthwash is a common complement to oral care. However, the physiological implication of this use, besides of effects on oral hygiene, is poorly known. The research of the gut micro flora and its implications on the host is a very active area of research today. Many important connections between the gut micro flora and obesity and diabetes have been found. These billions of bacteria are part of the immune system, they produce essential vitamins and they make inaccessible polysaccharides more digestible to the host, just to mention a few of their symbiotic roles for the host. A less explored area is the micro flora in the oral cavity. On the back of the tongue, anaerobic bacteria can reduce dietary nitrate to nitrite which then further can be reduced to nitric oxide, NO. NO is important in several important biological functions, e.g. as a signal substance, vasoregulation, mucus production and antibacterial effects. Vegetables as beetroot and spinach are dietary sources with a high nitrate content. Also drinking water and processed meats can be of relevance. Nitrite is added to processed meat for the prevention of botulism but also adds taste and color. Experiments on humans indicate that mitochondrial efficiency increases after nitrate load, manifested as a decreased oxygen demand during physical exercise. This can also be relevant under conditions where the mitochondrial function is impaired, such as in diabetes and cardiovascular diseases. First a pilot study was made to evaluate the nitrate reducing effect from the antibacterial mouthwash. The mouthwash proved very effective. The concentrations of nitrate and nitrite in saliva was analyzed by HPLC and saliva from the antibacterial treatment showed greatly reduced concentrations of nitrite and high concentrations of nitrate. Saliva from placebo mouthwash showed high concentrations of nitrite and low concentrations of nitrate as expected. To study the importance of oral bacteria on metabolism, we performed a randomized, cross-over double-blinded study with 19 healthy males between 22-43 years. During two separate three-day periods they used an antibacterial and placebo mouthwash, respectively. On the fourth day their basal metabolic rate (BMR) was measured with an indirect calorimetric system. Moreover, samples from saliva, urine and blood were collected but these results are not included in this thesis. An earlier, unpublished study has demonstrated that nitrate administration reduces the basal metabolic rate. Accordingly, our aim was to study potential effects on the basal metabolic rate following reduction of the number of oral bacteria by aid of antibacterial mouthwash. Our hypothesis was that the reduced availability of nitrite would decrease the availability of NO in the body and manifest as an increased basal metabolic rate. The results from indirect calorimetry measurements showed no significant difference between placebo and antibacterial mouthwash, but there may be confounding factors. Further study is needed to assess the potential effects on host metabolism by these bacteria.

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Bergqvist, Martin. "Efficiency in Swedish Power Grids : A Two-Stage Double Bootstrap DEA Approach for Estimating the Effects from Environmental Variables." Thesis, Umeå universitet, Nationalekonomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-149852.

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This paper uses a two-stage Data Envelopment Analysis approach to model the technical efficiency among the ~150 local electricity grids in Sweden. The analysis sets out to capture their heterogeneous environment and firm characteristics that might affect their efficiency. A novel aspect in this paper is the inclusion of the shares of distributed power from Small- and Micro-Scale producers such as wind farms and solar panels as environmental variables. To draw inference on how the environmental and firm specific factors affect the firms operatingthe grids, a Double Bootstrap Approach is employed. This is accompanied and compared tomore naïve modelling approaches often used in the literature. The general findings in this paper are that Density, the Fraction of Wires underground and Small-Scale production is associated with higher efficiency as well as large geographical differences. The policy implications from this study are that the regulator should incentivise firms to increase their share of wires that are underground but it also presents a modelling framework for future studies of power grids and other regulated industries.

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North, Thomas B. "Liquid Nitrogen Propulsion Systems for Automotive Applications: Calculation of Mechanical Efficiency of a Dual, Double-acting Piston Propulsion System." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc6070/.

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A dual, double-acting propulsion system is analyzed to determine how efficiently it can convert the potential energy available from liquid nitrogen into useful work. The two double-acting pistons (high- and low-pressure) were analyzed by using a Matlab-Simulink computer simulation to determine their respective mechanical efficiencies. The flow circuit for the entire system was analyzed by using flow circuit analysis software to determine pressure losses throughout the system at the required mass flow rates. The results of the piston simulation indicate that the two pistons analyzed are very efficient at transferring energy into useful work. The flow circuit analysis shows that the system can adequately maintain the mass flow rate requirements of the pistons but also identifies components that have a significant impact on the performance of the system. The results of the analysis indicate that the nitrogen propulsion system meets the intended goals of its designers.

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North, Thomas B. Plummer Mitty Charles. "Liquid nitrogen propulsion systems for automotive applications calculation of the mechanical efficiency of a dual, double-acting piston propulsion system /." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-6070.

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Milad, Muftah A. "UPS system : how current and future technologies can improve energy efficiency in data centres." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/14664.

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A data centre can consist of a large group of networked servers and associated power distribution, networking, and cooling equipment, all that application consumes enormous amounts of energy as a small city, which are driving to a significant increase in energy inefficiency problems in data centre, and high operational costs. Also the massive amounts of computation power contained in these systems results in many interesting distributed systems and resource management problems. In recent years, research and technologies in electrical engineering and computer science have made fast progress in various fields. One of the most important fields is the energy consumption in data centre. In recent years the energy consumption of electronic devices in data centre, as reported by. Choa, Limb and Kimb, nearly 30000000 kWh of power in a year, may consume by a large data centre and cost its operator around £3,000,000 for electricity alone. Some of the UK sites consume more than this. In the UK data centre the total power required are amid 2-3TWh per year. Energy is the largest single component of operating costs for data centres, varying from 25-60%. Agreeing to many types of research, one of the largest losses and causes of data centre energy inefficiency power distribution is from the uninterruptible power supply (UPS). So a detailed study characterized the efficiencies of various types of UPSs under a variety of operating conditions, proposed an efficiency label for UPSs, also investigate challenges related to data centre efficiency, and how all new technologies can be used to simplify deployment, improve resource efficiency, and saving cost. Data centre energy consumption is an important and increasing concern for data centre managers and operators. Inefficient UPS systems can contribute to this concern with 15 percent or more of utility input going to electrical waste within the UPS itself. For that reason, maximizing energy efficiencies, and reduce the power consumption in a data centre has become an important issue in saving costs and reducing carbon footprint, and it is necessary to reduce the operational costs. This study attempts to answer the question of how can future UPS topology and technology improve the efficiency and reduce the cost of data centre. In order to study the impact of different UPS technologies and their operating efficiencies. A model for a medium size data centre is developed, and load schedules and worked diagrams were created to examine in detail and test the components of each of the UPS system topologies. The electrical infrastructure topology to be adopted is configured to ‘2N’ and ‘N+1’ redundancy configuration for each UPS systems technologies, where ‘N’ stands for the number of UPS modules that are required to supply power to data centre. This work done at RED engineering designs company. They are professionals for designing and construction of a new Tier III and Tier IV data centres. The aim of this work is to provide data centre managers with a clearer understanding of key factors and considerations involved in selecting the right UPS to meet present and future requirements.

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Nguyen, Duy-Minh. "Commande intermittente de la machine à réluctance variable à double saillance." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS197/document.

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La commande intermittente a pour but principal d'augmenter le rendement de l'ensemble machine-convertisseur par une réduction des pertes. Dans le but de maintenir le couple moyen de la machine requis par la charge, cette commande augmente le couple de référence et éteint quelques phases pendant chaque période électrique ou chaque période mécanique. Par ce fait, elle réduit les pertes du convertisseur et les pertes ferromagnétiques de la machine. Elle dispose également d'une liberté de sélection des phases activées qui influence des fréquences générées du courant, de la force radiale et du couple. Par conséquent, cette stratégie de la commande intermittente, qui est appelée le glissement, peut éviter l'excitation de fréquences naturelles du stator, ou bien celles de la chaine cinématique. Elle a pour but de réduire les effets négatifs de la commande intermittente vis-à-vis de comportements vibratoire du stator et pulsatoire de la chaine cinématique qui sont respectivement à l'origine du bruit acoustique et des à-coups mécaniques. En fin, la commande intermittente est validée sur des cycles de conduite et peut économiser jusqu’à 5,17 % de l’énergie électrique consommée
The intermittent control aims to increase the efficiency of the machine-converter system by reducing the losses. In the purpose to maintain the average torque of the machine required by the load, this control increases the reference torque and turns off some phases during each electrical period or each mechanical period. By this fact, it reduces the converter losses and the ferromagnetic losses of the machine. It also has a freedom in the selection of the activated phases which influences the generated frequencies of the current, the radial force and the torque. Therefore, this strategy of the intermittent control, which is called sliding strategy, can avoid the excitation of the natural frequencies of the stator, or those of the drivetrain. It aims to reduce the negative effects of the intermittent control vis-à-vis the vibration of the stator and the pulsation of the drivetrain which are respectively at the origins of acoustic noise and mechanical jerks. Finally, the intermittent control is validated on driving cycles and can save up to 5.17 % of the consumed electrical energy

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Harouni, Zied. "Conception et caractérisation d’une Rectenna à double polarisation circulaire à 2.45 GHz." Thesis, Paris Est, 2011. http://www.theses.fr/2011PEST1026/document.

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Les travaux présentés dans ce mémoire s'inscrivent dans la thématique de la transmission d'énergie sans fil, appliquée à l'alimentation à distance de capteurs, de réseaux de capteurs et d'actionneurs à faible consommation. Cette étude porte sur la conception, la caractérisation, et la mesure d'un circuit Rectenna (Rectifying antenna) à double polarisation circulaire à 2.45 GHz, compact et à rendement de conversion RF-DC optimisé. Un outil d'analyse globale basé sur la méthode itérative a été développé et exploité pour valider la faisabilité de cette analyse. La diode Schottky a été modélisée en utilisant une impédance de surface. La rectenna à double polarisation circulaire, réalisée en technologie micro-ruban, a été validée expérimentalement. Elle est caractérisée par la rejection de la 2ème harmonique et une possibilité de recevoir les deux sens de polarisation LHCP et RHCP par l'intermédiaire de 2 accès. Le rendement mesuré avec une densité de puissance de 0.525 mW/cm² est de l'ordre de 63%, tandis que la tension DC obtenue aux bornes d'une charge optimale de 1.6 kohm est de 2.82 V
The work presented in this thesis is within the subject of wireless power transmission, power applied to the remote sensors, networks of sensors and actuators with low power consumption. This study focuses on the design, characterization, and measurement of a rectenna circuit (rectifying antenna) with dual circular polarization at 2.45 GHz, and optimisation of the conversion efficiency. A global analysis tool, based on the iterative method was developed and used to validate the feasibility of this concept by this method. The Schottky diode was modeled using surface impedance. The dual circular polarization rectenna with microstrip technology has been optimized and characterized experimentally operating at 2.45 GHz. It includes the property of harmonic rejections. Two accesses can receive either direction LHCP or RHCP sense. The conversion efficiency of 63% has been measured with a power density of 0.525 mW/cm². A DC voltage of 2.82V was measured across an optimum load of 1.6 kohm

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Dagiliūtė, Renata. "Analysis of changes in eco-efficiency of production and consumption in Lithuania during the 1990 – 2006 year period." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20081229_085241-15856.

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Sustainable production and consumption, as well as decoupling environmental impact from economy growth are one of the main goals for countries with transition economies. Lithuania, as other Central and Eastern Europe (CEE) countries experienced changes in political, social and economic life in relative short time after the collapse of Soviet Union. Because of an essentially reduced production, use of natural resources and environmental pollution decreased respectively. However, present pronounced growth of transition countries and demand for better quality of life could lead to the increase in material and energy consumption. Such increase would have two implications: firstly, increasing pressure on the environment and health in enlarged EU and could outweigh achievements in Western Europe, and secondly, such increase could impede to reach foreseen objectives to decouple resource consumption from economic growth. The aim of the research was to analyze the main trends of production and consumption and their environmental impact in Lithuania and to assess eco-efficiency of production and consumption and its main determinants. Research on eco-efficiency and the course of decoupling of environmental impact from economy growth in Lithuania is relatively rare and is mostly based on energy issues or covers only one sector. In this study, the eco-efficiency of production and consumption in Lithuania is analyzed jointly for the first time. For the better interpretation of ongoing... [to full text]
Darnios gamybos ir vartojimo siekimas, o tuo pačiu ir poveikio aplinkai atsiejimas nuo ekonomikos, yra vienas pagrindinių darnaus vystymosi tikslų pereinamosios ekonomikos šalims. Lietuva, kaip ir kitos posovietinės šalys, po Sovietų Sąjungos griūties paveldėjo imlų ištekliams ir neefektyvų ūkį. Ūkio restruktūrizavimas lėmė transformacinį ūkio nuosmukį ir jį sekusį išteklių naudojimo ir aplinkos teršimo sumažėjimą. Tačiau dabartinis spartus pereinamosios ekonomikos šalių, kurių dauguma jau tapo ES narėmis, augimas ir geresnės gyvenimo kokybės siekimas gali lemti didesnes medžiagų ir energijos sąnaudas, o tai savo ruožtu sąlygotų didėjantį poveikį aplinkai ir žmonių sveikatai išsiplėtusioje Europos Sąjungoje ir atsvertų kai kuriuos ES šalių senbuvių pasiekimus bei trukdytų pasiekti numatytus išteklių naudojimo atsiejimo nuo ekonomikos augimo tikslus. Darbo tikslas - išanalizuoti Lietuvos gamybos, vartojimo ir jų poveikio aplinkai kitimo tendencijas, ekologinio veiksmingumo pokyčius ir nustatyti jį lemiančius veiksnius. Ekologinio veiksmingumo bei poveikio aplinkai atsiejimo nuo ekonomikos augimo tyrimai Lietuvos mastu palyginti mažai vykdyti ir dažnai apsiriboja tik energetinių išteklių naudojimo veiksmingumo analize arba skirti tik atskiriems sektoriams. Darbe pateikiama dvigubo atsiejimo koncepcija, numatanti būtinybę atsieti gamtos išteklių naudojimą nuo ekonomikos augimo ir aplinkos teršimą nuo gamtos išteklių naudojimo bei sudaranti galimybes detaliau įvertinti... [toliau žr. visą tekstą]

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Rain, Xavier. "Contributions à la commande et à la conception des machines à réluctance variable à double saillance." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112170.

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Dans le domaine du véhicule électrique, la chaîne de traction allant de la batterie de stockage aux roues en passant par le moteur constitue le cœur du système. Elle bénéficie régulièrement d’innovations technologiques rendant ce véhicule de plus en plus attractif. Actuellement, les motorisations proposées par les constructeurs sont classiques, de type synchrone à rotor bobiné, à aimant permanent ou asynchrone. De conception éprouvée et dotées de lois de commande complexes et parfaitement maîtrisées, elles offrent de bonnes performances.Cependant, les industriels explorent de nouvelles motorisations moins conventionnelles permettant de réduire leur coût de fabrication, tout en maintenant les performances. Une des solutions possibles est la machine à réluctance variable à double saillance (MRVDS). En effet, elle est de conception simple et constituée de matériaux peu couteux. Son rotor complètement passif lui confère une très bonne robustesse et une vitesse de rotation élevée, nécessaire à une certaine compacité.Néanmoins, son pilotage est beaucoup plus complexe que pour les autres machines, elle est relativement bruyante et son couple présente des ondulations non négligeables.Nos travaux ont pour but de contribuer à l’amélioration des performances de la MRVDS du point de vue contrôle, caractéristiques de couple et efficacité énergétique sur une plage de vitesse importante. Ils ont alors été conduits selon deux axes : un axe commande et un axe conception.Afin de satisfaire un contrôle du couple le plus parfait possible, de nouveaux régulateurs de courant à la fois performants et relativement simples à implémenter sur cible logicielle ont été présenté dans un premier temps. Ensuite, nous avons proposé une implémentation partitionnée de la commande de la MRVDS sur cibles logicielle et matérielle. L’objectif est ici de conserver les performances de la commande dans le cas de l’utilisation d’un processeur économique, dont la période d’échantillonnage serait relativement importante, et tout particulièrement à haute vitesse. Une carte FPGA (Fied Programmable Gate Array) a alors été mise en œuvre.Pour améliorer les caractéristiques de couple en fonction de la vitesse ainsi que le rendement de l’ensemble moteur-convertisseur, une nouvelle structure de MRVDS non conventionnelle a été proposée. Elle est munie d’un bobinage auxiliaire créant une excitation magnétique dans chaque phase.Une étude a d’abord été menée à l’aide de simulations basées sur un nouveau modèle. Elle a permis de mettre en évidence les avantages d’une excitation par rapport à une MRVDS classique. Afin de valider les résultats, un prototype a ensuite été conçu, réalisé et expérimenté.Une part importante de ces travaux a ainsi été consacrée à la mise en œuvre de plateformes expérimentales et à la réalisation de nombreux essais permettant de valider les développements théoriques, tant du point de vue commande sur une MRVDS 8/6 que conception sur une MRVDS 6/4
For electric vehicles, traction from storage battery to the wheels through the engine is the heart of the system. It regularly enjoys technological innovations making this vehicle more attractive. Currently, machines offered by manufacturers are classic, synchronous and induction machines. With complex laws, they offer good performance.However, manufacturers are exploring new unconventional machines to reduce their manufacturing cost while maintaining performance. One possible solution is the switched reluctance machine (SRM). Indeed, its design is simple and made of inexpensive materials. Its rotor completely passive gives it a very good robustness and high rotational speed required for certain compactness. However, its operation is much more complex than for other machines, it is relatively noisy and has significant torque ripple.Our work contributes to the improvement of SRM’s performance in terms of control torque characteristics and global efficiency over a large range speed. They were driven on two axes: one control axis and one design axis.To satisfy a torque control as perfect as possible, new currents controller both efficient and relatively simple to implement on software target were first presented. Then we proposed a SRM's control implementation on hardware and software targets. The objective is to maintain the performances in the case of an important sampling period, especially at high speeds. So an FPGA circuit (Fied Programmable Gate Array) was used.To improve torque characteristics depending on the speed, and global efficiency, a new SRM structure has been proposed. It is provided with an auxiliary coil creating a magnetic excitation in each phase. A study was initially conducted using simulations based on a new model. It helped to highlight the benefits of excitement compared to a conventional SRM. To validate the results, a prototype was then designed, built and tested.An important part of this work has been devoted to the implementation of experimental platforms and implementation of numerous tests to validate the theoretical developments, both in terms of control on a 8/6 SRM and design on a 6/4 SRM

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Quincoses, Annette, and Malin Andersson. "Tidseffektivisering av inköpsprocessen på Mape Sweden AB." Thesis, Högskolan Väst, Avdelningen för maskinteknik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-7757.

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Detta examensarbete har genomförts på Mape Sweden AB med syfte att eliminera eller minska icke värdeskapande aktiviteter inom inköpsprocessen. Genom att undersöka hur fö-retaget arbetar med inköp och dess inköpsaktiviteter för verktyg och reservdelar är målet att hitta lösningar som innebär en tidseffektivisering av inköpsprocessen. Arbetet är av kvalitativ karaktär. Denna ansats valdes då gruppen ville få en förståelse över nuläget genom kvalitativa metoder. Metoderna som använts för att samla in data till arbetet var observationer och intervjuer, en litteraturstudie samt benchmarking på ett annat tillver-kande företag. För att ta fram förbättringsförslag till företaget utfördes ett spagettidiagram över förflyttningar. En tidsstudie genomfördes för att kunna jämföra tiderna innan och efter implementering av förbättringsförslagen. Vid analysen av nuläget framkom att olika typer av inköp görs av olika personer på företaget, vilket resulterar i att det inte finns ett standardiserat arbetssätt. Spagettidiagrammet över för-flyttningar vid godsuttag och godsmottagning visade att många förflyttningar görs och att ett stort antal av dem är onödiga. Genom denna information samt den information som erhållits från benchmarkingen tog gruppen fram förbättringsförslag. Förbättringsförslaget innebär för godsuttag att operatörerna själva skriver in sina uttag i affärssystemet SAP. För godsmottag-ningen var förbättringsförslagen att endast göra godsmottagning en gång per dag, att placera en hylla för ej lagerlagda verktyg och en hylla för förnödenheter i verktygsboden samt att ställa krav på leverantörerna att alltid ha med artikelnummer och lagerplats på följesedeln som medföljer alla leveranser. Vid införande av förbättringsförslagen kommer den totala tiden som läggs på godsuttag och godsmottagning minska från 6 timmar, 40 minuter och 23 sekunder till 1 timma och 58 mi-nuter, vilket motsvarar en minskning av tiden på 70 %. I framtiden rekommenderas att förbättringsförslagen även implementeras på andra typer av inköp inom företaget samt att företaget vidare undersöker fördelarna med verktygsskåp och skanningssystem.
This Bachelor's Thesis has been performed at Mape Sweden AB with the purpose of elimi-nate or reduce the non-value adding activities within the purchasing process. By examining the company's purchasing process for tools and spare parts, the goal is to find solutions that will entail time-efficiency in the purchasing process. The work in this thesis is of qualitative nature. This approach was chosen to obtain an un-derstanding of the current situation with qualitative methods. To collect data the group per-formed several observations and interviews, literature reviews and a benchmarking at a dif-ferent manufacturing company. To develop proposals for improvements to the company, a spaghetti diagram was conducted tracking all movements at goods-withdrawal and goods-receipt. A time study was conducted to compare the times before and after implementation of improvement proposals. The current situation analysis showed that purchases are made by different people resulting in that there is not a standardized approach. Spaghetti diagram of movements in goods-withdrawal and goods-receipt showed that there is numerous movements and some of them are unnecessary. Proposals for improvements was conducted based on the information from current situation analysis together with information obtained from benchmarking. The pro-posal for goods-withdrawal was that the workers themselves enter goods-withdrawal in the SAP-system. The proposals for goods-reception was to receive the goods once a day, place a shelf for non-stocked tools and a shelf for supplies in the tool shed as well as making demands on suppliers to always have the part number and stock location on the packing slip included with all deliveries. .When implementing the groups proposed improvements, the total time spent on goods-receiving and goods-withdrawal was reduced from 6 hours, 40 minutes and 23 seconds to 1 hour and 58 minutes, which represents a decrease of 70%. For future work the group recommend that the improvement proposals also be implemented on other types of purchases within the company and that the company further investigate the benefits of tool cabinet and scan-ning systems.

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Pompa, Federica. "Neutrino physics with the XENONnT experiment." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19448/.

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One of the most active fields in physics is the search for Dark Matter, for which the XENON Project is one of the main protagonists. The new XENONnT experiment will be operative starting from 2020 in the underground Laboratori Nazionali del Gran Sasso, under 3600 meters water equivalent of mountain rock shield. It is a multi-ton detector for direct search of Dark Matter, consisting of a double phase liquid-gas xenon TPC which contains 5.9 t of liquid xenon target mass, inserted in a Cryostat surrounded by a tank containing 700 t of Gd-loaded water, instrumented with PMTs for muon and neutron tagging. Its aim, as that of its precursor XENON1T, is to detect WIMPs elastic scattering off xenon nucleus through the measure of the light and charge observable signals produced by recoils in LXe. A new neutron Veto system, surrounding the outer Cryostat and instrumented with 120 additional PMTs, will contribute to reduce the neutron background in the TPC. Thanks to the large xenon target used, this experiment is sensitive also to all flavors of Supernova neutrinos. These can be detected through two different interactions channels: through coherent elastic scatters on xenon nuclei in the TPC and through interactions of electron antineutrinos with protons of water via inverse beta decay process. In the first part of this work, after a theoretical introduction to neutrino physics, I present the results of a Monte Carlo simulation to predict the XENONnT detection efficiencies for neutrino events as IBD interactions in the neutron and muon Vetoes. In the last part of the thesis, I investigate the XENONnT possibility to detect neutrinoless double beta decay of Xe-136 isotope, a Standard Model forbidden decay which can prove the Majorana nature of neutrinos. Starting from evaluation of the ER background rate from Cryostat and PMTs in the energy region where we expect to observe neutrinoless double beta decay, the sensitivity of XENONnT for this nuclear decay was estimated.

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Martel, Gilles. "Etude de l'effet photoréfractif dans la tellure de cadmium : application à l'interconnexion en espace libre par double miroir à conjugaison de phase." Rouen, 1996. http://www.theses.fr/1996ROUES076.

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Cette thèse traite des propriétés électroniques et optiques, ainsi que des applications en holographie dynamique (photoréfractivité) du tellure de cadmium et de ses alliages à base de zinc. La caractérisation s'est orientée vers l'alliage photoréfractif le plus prometteur : le Cd1-xZnxTe dopé V avec 0x%)4. La croissance retenue pour la réalisation de ces matériaux fut la méthode Bridgman verticale asymétrique. La caractérisation photoréfractive par la technique du mélange à deux ondes nous a permis de sélectionner les matériaux qui autorisent les rendements de diffraction les plus favorables à la conjugaison de phase. Nous avons pu mettre en évidence différents types de comportements photoréfractifs sous champ électrique externe nul, continu ou alternatif (jusqu'à 14 kV/cm). L'existence de ces différents comportements est assujetti à la présence ou non de zinc. Deux modelés considérés comme des extensions de la théorie photoréfractive classique, et dont la limite de validité fut précisément définie par les analyses spectroscopiques des défauts profonds dans un cristal (DLTS, DLOS, PICTS, ODMR, MCD, RPE, effet Hall, photoluminescence et absorption), ont été développés afin de proposer une explication claire des différents processus détectés. Parallèlement à cette étude sur la compréhension du matériau, un démonstrateur de commutateur optique reconfigurable a été développé entre fibres monomodes. Basé sur l'utilisation d'un double miroir à conjugaison de phase (DPCM), ce commutateur a été réalisé à la longueur d'onde de 1. 5 m. Des temps de reconfiguration (cycle effacement-écriture d'un réseau holographique de Bragg photoinscrit) de l'ordre de 10 millisecondes ont été mesurés pour ce démonstrateur à commutation lente. De nombreux problèmes dynamiques (instabilités, franges mobiles) ont été mis en évidence au sein de ce matériau en configuration DPCM et également en configuration miroir à conjugaison de phase en anneau (ring PCM). Une théorie basée sur les ondes couplées a permis de rendre compte de l'aspect fondamental et donc général de la dynamique (franges mobiles) qui existe au sein d'un grand nombre de miroirs à conjugaison de phase.

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Alipour, Philip Baback, and Muhammad Ali. "An Introduction and Evaluation of a Lossless Fuzzy Binary AND/OR Compressor." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-6141.

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We report a new lossless data compression algorithm (LDC) for implementing predictably-fixed compression values. The fuzzy binary and-or algorithm (FBAR), primarily aims to introduce a new model for regular and superdense coding in classical and quantum information theory. Classical coding on x86 machines would not suffice techniques for maximum LDCs generating fixed values of Cr >= 2:1. However, the current model is evaluated to serve multidimensional LDCs with fixed value generations, contrasting the popular methods used in probabilistic LDCs, such as Shannon entropy. The currently introduced entropy is of ‘fuzzy binary’ in a 4D hypercube bit flag model, with a product value of at least 50% compression. We have implemented the compression and simulated the decompression phase for lossless versions of FBAR logic. We further compared our algorithm with the results obtained by other compressors. Our statistical test shows that, the presented algorithm mutably and significantly competes with other LDC algorithms on both, temporal and spatial factors of compression. The current algorithm is a steppingstone to quantum information models solving complex negative entropies, giving double-efficient LDCs > 87.5% space savings.
Vi rapporterar en ny förlustfri komprimering algoritm (MUL) för att genomföra förutsägbart-fast komprimering värden. Den luddiga binär och-eller algoritm (FBAR), syftar bland annat att införa en ny modell för regelbunden och superdense kodning i klassiska och kvantmekaniska information teori. Klassiska kodning på x86-maskiner inte skulle räcka teknik för maximal LDC att skapa fasta värden av Cr >= 2:1. Men den nuvarande modellen utvärderas för att tjäna flerdimensionella LDC med fast värde generationer, där de populära metoder som används i probabilistiska LDC, såsom Shannon entropi. De närvarande in entropi är av "fuzzy binära" i en 4D blixtkub lite flagga modell, med en produkt värde av minst 50% komprimering. Vi har genomfört komprimering och simulerade den tryckfall fasen för förlustfri versioner av FBAR logik. Jämförde vi ytterligare vår algoritm med de resultat som andra kompressorer. Vår statistiska testet visar att den presenterade algoritmen mutably och betydligt konkurrerar med andra LDC algoritmer på båda, tidsmässiga och geografiska faktorer av kompression. Den nuvarande algoritmen är en steppingstone att kvantinformationsteknik modeller lösa komplexa negativa entropies, vilket ger dubbel-effektiva LDC> 87,5 besparingar utrymme.
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El, Ghouli Salim. "UTBB FDSOI mosfet dynamic behavior study and modeling for ultra-low power RF and mm-Wave IC Design." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAD015/document.

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Ce travail de recherche a été principalement motivé par les avantages importants apportés par la technologie UTBB FDSOI aux applications analogiques et RF de faible puissance. L'objectif principal est d'étudier le comportement dynamique du transistor MOSFET du type UTBB FDSOI et de proposer des modèles prédictifs et des recommandations pour la conception de circuits intégrés RF, en mettant un accent particulier sur le régime d'inversion modérée. Après une brève analyse des progrès réalisés au niveau des architectures du transistor MOSFET, un état de l’art de la modélisation du transistor MOSFET UTBB FDSOI est établi. Les principaux effets physiques impliqués dans le transistor à double grille avec une épaisseur du film de 7 nm sont passés en revue, en particulier l’impact de la grille arrière, à l’aide de mesures et de simulations TCAD. La caractéristique gm/ID en basse fréquence et la caractéristique ym/ID proposée pour la haute fréquence sont étudiées et utilisées dans une conception analogique efficace. Enfin, le modèle NQS haute fréquence proposé reproduit les mesures dans toutes les conditions de polarisation y compris l’inversion modérée jusqu’à 110 GHz
This research work has been motivated primarily by the significant advantages brought about by the UTBB FDSOI technology to the Low power Analog and RF applications. The main goal is to study the dynamic behavior of the UTBB FDSOI MOSFET in light of the recent technology advances and to propose predictive models and useful recommendations for RF IC design with particular emphasis on Moderate Inversion regime. After a brief review of progress in MOSFET architectures introduced in the semiconductor industry, a state-of-the-art UTBB FDSOI MOSFET modeling status is compiled. The main physical effects involved in the double gate transistor with a 7 nm thick film are reviewed, particularly the back gate impact, using measurements and TCAD. For better insight into the Weak Inversion and Moderate Inversion operations, both the low frequency gm/ID FoM and the proposed high frequency ym/ID FoM are studied and also used in an efficient first-cut analog design. Finally, a high frequency NQS model is developed and compared to DC and S-parameters measurements. The results show excellent agreement across all modes of operation including very low bias conditions and up to 110 GHz

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Chen, Ning. "Bandwidth Efficiency and Power Efficiency Issues for Wireless Transmissions." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10484.

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As wireless communication becomes an ever-more important and pervasive part of our everyday life, system capacity and quality of service issues are becoming more critical. In order to increase the system capacity and improve the quality of service, it is necessary that we pay closer attention to bandwidth and power efficiency issues. Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier modulation technique for high speed data transmission and is generally regarded as bandwidth efficient. However, OFDM signals suffer from high peak-to-average power ratios (PARs) which lead to power inefficiency in the RF portion of the transmitter. Moreover, in OFDM, the well-known pilot tone assisted modulation (PTAM) technique utilizes a number of dedicated training pilots to acquire the channel state information (CSI), resulting in somewhat reduced bandwidth efficiency. In this dissertation, we will address the above mentioned bandwidth and power efficiency issues in wireless transmissions. To avoid bandwidth efficiency loss due to dedicated training, we will first develop a superimposed training framework that can be used to track the frequency selective as well as the Doppler shift characteristics of a channel. Later on, we will propose a generalized superimposed training framework that allows improved channel estimates. To improve the power efficiency, we adopt the selected mapping (SLM) framework to reduce the PARs for both OFDM and forward link Code Division Multiple Access (CDMA). We first propose a dynamic SLM algorithm to greatly reduce the computational requirement of SLM without sacrificing its PAR reducing capability. We propose a number of blind SLM techniques for OFDM and for forward link CDMA; they require no side information and are easy to implement. Our proposed blind SLM technique for OFDM is a novel joint channel estimation and PAR reduction algorithm, for which bandwidth efficiency power efficiency - complexity - bit error rate tradeoffs are carefully considered.

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Ritz, Carolina, and Malin Mattsson-Mårn. "Utformningens betydelse för energiförbrukningen : En fallstudie av verksamhetsbyggnader." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Byggnadsteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-28281.

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Purpose: The building sector accounts for 40 % of the total energy consumption in Sweden today, and the largest proportion is consumed during the operating phase. From the year 2020 and onwards, all new buildings should be erected as zero-emissionbuildings. The building’s design can reduce energy demands, but the current legal requirements do not favour energy-efficient designs. This study focuses on the design’s importance for the energy efficiency of buildings, i.e., energy-saving design. The impact of specific measures is difficult to calculate due to the complexity of reality. This study aims to highlight the measures that could reduce energy consumption in commercial buildings. Method: In order to provide answers to the issues stated in the report and to achieve the objective of the study, case studies are being conducted investigating three commercial buildings where deliberate decisions were made to use energy-reducing measures. Results and conclusions are based on qualitative interviews and literature studies. Findings: The energy-reducing design measures found to be of most importance used in the studied buildings are the form factor, the window portion and the thermal storage capacity. Moreover, significant savings are possible by carefully consider how solar energy can be limited or used in the building. Generally, buildings tends to become more technical, therefore technical knowledge early in the process is important to reach a good result. Economic incentives and clear objectives with right focus are also important for optimizing a building’s energy performance. The wording and the requirement levels in the Swedish building regulations highly controls the construction of energy efficient buildings. Implications: This study shows how energy efficient design is made today and provides an indication of what can be done and what should be prioritized. By imposing requirements on consumed energy instead of bought, energy efficient design could be favoured. Furthermore, this study suggests that a balance between windows, façade and solar shading are important energy-reducing measures. Regardless of selected energyreducing measures, a good performance is essential. Finally, this study shows that a methodical use of existing knowledge and technology makes a difference. Limitations: A lifecycle approach provides an overall picture of a building’s energy consumption. However, this study is based on the energy consumption during the operating phase. The result of this study does not take economic or aesthetic factors into account. This study is a comparative case study and is based on few but carefully matched cases. The selected cases are commercial buildings where deliberate decisions were made to use energy-reducing measures.

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Faqiry, Mohammad. "Efficient double auction mechanisms in the energy grid with connected and islanded microgrids." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/35480.

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Doctor of Philosophy
Department of Electrical and Computer Engineering
Sanjoy Das
The future energy grid is expected to operate in a decentralized fashion as a network of autonomous microgrids that are coordinated by a Distribution System Operator (DSO), which should allocate energy to them in an efficient manner. Each microgrid operating in either islanded or grid-connected mode may be considered to manage its own resources. This can take place through auctions with individual units of the microgrid as the agents. This research proposes efficient auction mechanisms for the energy grid, with is-landed and connected microgrids. The microgrid level auction is carried out by means of an intermediate agent called an aggregator. The individual consumer and producer units are modeled as selfish agents. With the microgrid in islanded mode, two aggregator-level auction classes are analyzed: (i) price-heterogeneous, and (ii) price homogeneous. Under the price heterogeneity paradigm, this research extends earlier work on the well-known, single-sided Kelly mechanism to double auctions. As in Kelly auctions, the proposed algorithm implements the bidding without using any agent level private infor-mation (i.e. generation capacity and utility functions). The proposed auction is shown to be an efficient mechanism that maximizes the social welfare, i.e. the sum of the utilities of all the agents. Furthermore, the research considers the situation where a subset of agents act as a coalition to redistribute the allocated energy and price using any other specific fairness criterion. The price homogeneous double auction algorithm proposed in this research ad-dresses the problem of price-anticipation, where each agent tries to influence the equilibri-um price of energy by placing strategic bids. As a result of this behavior, the auction’s efficiency is lowered. This research proposes a novel approach that is implemented by the aggregator, called virtual bidding, where the efficiency can be asymptotically maximized, even in the presence of price anticipatory bidders. Next, an auction mechanism for the energy grid, with multiple connected mi-crogrids is considered. A globally efficient bi-level auction algorithm is proposed. At the upper-level, the algorithm takes into account physical grid constraints in allocating energy to the microgrids. It is implemented by the DSO as a linear objective quadratic constraint problem that allows price heterogeneity across the aggregators. In parallel, each aggrega-tor implements its own lower-level price homogeneous auction with virtual bidding. The research concludes with a preliminary study on extending the DSO level auc-tion to multi-period day-ahead scheduling. It takes into account storage units and conven-tional generators that are present in the grid by formulating the auction as a mixed inte-ger linear programming problem.

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27

Feher, Kamilo. "FQPSK Doubles Spectral Efficiency of Telemetry: Advances and Initial Air to Ground Flight Tests." International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/607395.

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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California
FQPSK is the abbreviation for Feher Quadrature Phase Shift Keying (FQPSK) patented systems [1]. Digcom, Inc. licensed FQPSK products demonstrated significant spectral saving and RF power efficient robust BER performance advantages. These bit rate agile modems and Non Linearly Amplified (NLA) transceivers, DSP and hardware implementations, and in some instances “software-radios” (20kb/s to more than 100Mb/s) and RF frequency agile (from 150MHz to more than 40GHz) developments and systems have recently been demonstrated and deployed. The spectral efficiency, i.e., data throughput capability of the 1st generation of FQPSK, as demonstrated in initial Advanced Range Telemetry (ARTM) flight tests, approximately doubles while 2nd generation “FQPSK-2” systems have the potential to quadruple the spectral efficiency of operational PCM/FM telemetry systems and be backward compatible with the 1st generation of FQPSK technologies. It is also demonstrated that the spectral efficiency advantage of FQPSK over that of NLA power efficient GMSK, OQPSK and QPSK modulated transceivers is in the 50% to 300% range and that the potential spectral efficiency advantage of FQPSK-2 over GMSK [1] is in the 200% to 500% range. Based on extensive multi-year studies of alternative solutions for spectral and RF power efficient, robust BER performance systems, several commercial US and international organizations, AIAA, CCSDS, NASA, ESA, CCSDS and various programs of the US Department of Defense (DoD) concluded that FQPSK offers the most spectrally efficient high performance-high speed proven technology solutions and recommended FQPSK standardization for several data links. Initial DoD-ARTM Program Office Air-to-Ground L-band and S-band jet airborne telemetry Test and Evaluation (T&E) data, obtained during the summer of 1998 are briefly highlighted. These include simultaneosly tested FQPSK and PCM/FM. In these tests the following ARTM objectives have been demonstrated: (a) FQPSK approximately doubles the spectral efficiency of currently operational PCM/FM; (b) The Data Link Performance of these two systems is comparable. The American Institute of Aeronautics and Astronautics (AIAA) draft modulation standard recommended to the DoD, NASA and CCSDS, was approved by the AIAA [23]. The AIAA standard recommends “that FQPSK modulation be immediately adopted as the interim increment–1 standard.”

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28

Courty, Alexis. "Architecture d'amplificateur de puissance linéaire et à haut rendement en technologie GaN de type Doherty numérique." Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0067/document.

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Les fortes capacités actuelles et envisagées des futurs liens satellites de communication pour la 5G conduisent les signaux traités dans les charges utiles à présenter simultanément d'importantes variations d'amplitude (PAPR>10dB) et de très larges bandes passantes instantanées (BW>1GHz). A l'intérieur du sous-système d'émission hyperfréquence, le fonctionnement du module d'amplification de puissance se trouve très contraint par les formes d'ondes véhiculées, il se présente comme l'un des postes de consommation énergétique des plus importants, et ayant le plus d'impact sur l'intégrité du signal émis. Dans ce contexte, les fonctions dédiées au traitement numérique des signaux et couramment implémentées par le processeur numérique (telles que le filtrage, la canalisation, et éventuellement la démodulation et la régénération des signaux bande de base) embarquées dans les charges utiles, représentent une solution à fort potentiel qui permettrait de relâcher les contraintes reportées sur la fonction d'amplification de puissance afin de gérer au mieux la ressource électrique allouée. Ces travaux de thèse proposent d'étudier les potentialités d'amélioration du fonctionnement en rendement et linéarité d'un amplificateur de type Doherty à double entrée de gamme 20W en technologie GaN et fonctionnant en bande C. La combinaison des signaux de puissance sur la charge RF est optimisée par une distribution optimale des signaux en amplitude et phase à l'entrée par des moyens numériques de génération. Dans un premier temps une méthodologie de conception large bande d'un amplificateur Doherty est introduite et validée par la conception d'un démonstrateur en bande C. Dans un second temps, l'outil expérimental permettant l'extraction des lois optimales de distribution d'amplitude et de phase RF est présenté en détail, et la caractérisation expérimentale du dispositif en double entrée est réalisée puis comparée aux simulations. Finalement, en perspective à ces travaux, une étude préliminaire des potentialités de l'architecture Doherty à double entrée pour la gestion d’une désadaptation de la charge de sortie (gestion de TOS) est menée et des résultats sont mis en avant
The high capabilities of current and future 5G communication satellite links lead the processed signals in the payloads to simultaneously exhibit large amplitude variations (PAPR>10dB) and wide instantaneous bandwidths (BW>1GHz). Within the microwave transmission subsystem, the operation of the power amplification stage is highly constrained by the transmitted waveforms, it is one of the most energy-consuming module of the payload affecting as well the integrity of the transmitted signal. In this context, the functions dedicated to digital signal processing and currently implemented by the digital processor (such as filtering, channeling, and possibly the demodulation and regeneration of baseband signals) embedded in the payloads, represent a potential solution that would reduce the constraints reported on the power amplification function and help to manage the allocated power ressource. This work proposes a study on the capability of dual input power amplifier architectures in order to manage the efficiency-linearity trade-off over a wide bandwidth. This study is carried out on a 20W GaN Doherty demonstrator operating in C band. The combination of the output signals on the RF load is managed by an optimal amplitude and phase distribution that is digitally controlled at the input. Firstly, a wideband design methodology of Doherty amplifier is introduced and validated on a C band demonstrator. In a second time the experimental tool allowing the extraction of amplitude and phase input distributions is presented, the dual input characterization is achieved and compared with simulation results. Finally, in perspective of this work, a preliminary study of the capabilities of the digital Doherty for the management of an output load mismatch (VSWR management) is carried out and the results are put forward

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29

Skrzypczak, Alexandre, Alain Thomas, and Guillaume Duponchel. "Paradigms Optimization for a C-Band COFDM Telemetry with High Bit Efficiency." International Foundation for Telemetering, 2013. http://hdl.handle.net/10150/579655.

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ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV
Systems using single carrier modulations for flight test transmissions perfectly fit noisy and time selective channels. However, the densification of the airport environment now makes the aero channel also frequency selective due to multiple reflections on surrounding buildings, especially while taxiing and taking off. Obviously, this has a direct consequence on hardware resources and user data rates. In such a context, COFDM represents an appealing solution thanks to its inherent robustness to multipath fading channels. But a direct application of an off-the-shelf COFDM standard is not straightforward as these standards are designed for specific channels whose characteristics are quite different from the aero one. That is why we made an experiment at Toulouse-Blagnac airport to jointly sound the channel and qualify a COFDM waveform. This paper then describes the construction of the waveform and the results of the channel sounding. From this, different standard paradigms are compared.

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30

Hwang, Sung Jun. "Communication over Doubly Selective Channels: Efficient Equalization and Max-Diversity Precoding." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1261506237.

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31

Guan, Bo. "DESIGN AND CONTROL OF A HIGH-EFFICIENCY DOUBLY-FED BRUSHLESS MACHINE FOR POWER GENERATION APPLICATIONS." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406240037.

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32

Presas, Suzette Marie. "Microwave frequency doubler integrated with miniaturized planar antennas." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002614.

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33

Pachai, Kannu Arun. "Communications over noncoherent doubly selective channels." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1173887288.

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34

Sika, Glebehlo Lazare. "Impact des allocations en ressources sur l'efficacité des écoles primaires en Côte d'Ivoire." Thesis, Dijon, 2011. http://www.theses.fr/2011DIJOE001/document.

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La qualité de l’enseignement primaire en Côte d’Ivoire s’est fortement dégradée au cours de ces trois dernières décennies. Cette situation est la résultante d’une gestion approximative du système éducatif, qui se caractérise par une insuffisance de support pédagogique, une mauvaise allocation des ressources, un encombrement des salles de classe (42 élèves par enseignants au primaire) et un déficit d’enseignants qualifiés et bien formés. En outre, le conflit militaro-politique de septembre 2002 n’a guère amélioré cet état de choses, bien au contraire, il n’a fait que détériorer davantage la situation. Ainsi, la présente thèse s’est fixée comme objectifs d’analyser, d’une part l’influence des dotations en ressources sur l’efficacité des écoles primaires en Côte d’Ivoire sur la base d’une enquête sur les compétences réalisée par le Ministère de l’Education Nationale et d’autre part, d’examiner l’impact du conflit militaro-politique de septembre 2002 sur la demande d’éducation en s’appuyant sur les données des enquêtes MICS-2000 et 2006 réalisées auprès des ménages. Pour ce faire, une classification des écoles selon leur dotation en ressources s’est faite, ensuite, au moyen de la méthode de l’enveloppe des données (DEA, méthode non paramétrique), une frontière d’efficience est construite pour mettre en exergue les spécificités des écoles et enfin une estimation économétrique (modèle Tobit sur les données censurées) est mise en œuvre pour déceler les facteurs influençant la formation des scores d’efficacité. Il ressort des analyses qu’une augmentation de la quantité des ressources allouées à une école n’est pas gage de sa performance car les facteurs d’efficacités ne résident pas dans les dotations en quantité, mais plutôt dans les dotations en qualité c'est-à-dire les valeurs et caractéristiques intrinsèques aux personnes et matériaux mises à la disposition des écoles, ceci fait dans un souci d’adéquation aux besoins spécifiques des écoles et d’équité. Par ailleurs, à partir d’une méthodologie combinant à la fois l’estimation par les doubles différences, l’estimation par les triples différences et la correction par les contrôles de robustesse, elle aboutit aux résultats selon lesquels, les taux d’accès et d’achèvement aux grades un à six du primaire ont baissé du fait de la crise. En effet, les proportions d’enfants qui achèvent les grades 1 et 2 ont baissé de 25 % et celles des enfants qui achèvent les grades 3, 4 et 5 ont diminué respectivement de 22 %, 16 % et 4 %
The quality of primary education in Côte d'Ivoire has deteriorated sharply over the past three decades. This situation is the result of an approximate management of the education system, which is characterized by a lack of educational support, a misallocation of resources, a congestion of classrooms (42 students for a teacher in primary school) and a lack of skilled and well trained teachers. In addition, the military-political conflict in September 2002 did not allow to improve this situation; on the contrary, it has further deteriorated the situation. Thus, the aim of this thesis is first to analyze the influence of resource endowments on the effectiveness of primary schools in Cote d'Ivoire on the basis of a survey on the competence conducted by the Ministry of Education. Secondly, it examines the impact of military-political conflict in September 2002 on the demand for education based on data from the MICS-2000 and 2006 household surveys. To do this, a classification of schools according to their resource endowment was made, then, using the method of data envelopment analysis (DEA nonparametric method), an efficiency frontier is constructed to highlight the specificities of schools and finally an econometric estimation (Tobit model censored data) is implemented to identify factors influencing the formation of effectiveness scores. The analysis shows that increasing the amount of resources allocated to a school does not guarantee its performance as the efficiency factors are not resident in endowment quantity, but rather in the endowment quality, that is the values and characteristics intrinsic to people and materials available to schools, this fact in order to fit the specific needs of schools and fairness. Furthermore, using a methodology combining both double differences estimation, the triple differences estimation and correction by the robustness checks, we find that the rate of access and completed grades of primary school s one to six of primary school declined because of the crisis. Indeed, the proportions of children completing levels 1 and 2 have fallen by 25% and those of children completing levels 3, 4 and 5 have decreased by 22%, 16% and 4% respectively

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35

Notaro, Vincent. "Mixing Analysis of Like Doublet Injectors in High Pressure Environments for Gelled Propellant Simulants." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406821648.

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36

Merrifield, David Bruce. "Control of the Doubly Salient Permanent Magnet Switched Reluctance Motor." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/76988.

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The permanent magnet switched reluctance motor (PMSRM) is hybrid dc motor which has the potential to be more effect than the switched reluctance (SRM) and permanent magnet (PM) motors. The PMSRM has a both a salient rotor and stator with permanent magnets placed directly onto the face of common pole stators. The PMSRM is wound like the SRM and can be controlled by the same family of converters. The addition of permanent magnets creates nonlinearities in both the governing electrical and mechanical equations which differentiate the PMSRM from all other classes of electric motors. The primary goal of this thesis is to develop a cohesive and comprehensive control strategy for the PMSRM so as to demonstrate its operation and highlight its efficiency. The control of the PMSRM starts with understanding its region of operation and the underlying torque production of the motor. The selection of operating region is followed by a both linear and nonlinear electrical modeling of the motor and the design of current controllers for the PMSRM. The electromechanical model of the motor is dynamically simulated with the addition of a closed loop speed controller. The speed controller is extended to add an efficiency searching algorithm which finds the operating condition with the highest efficiency online.
Master of Science

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37

Sheng, Lin Yu, and 林育生. "Development and analysis of high-efficiency double-layer solar module." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/71622632448928083409.

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碩士
國立高雄應用科技大學
模具工程系碩士班
101
Solar modules are power generators placed outdoors for an extensive length of time with a shelf life of more than 20 years, where the power output varies with light intensity and module temperature. This study aims to research solar modules that generate more power with limited area. First, through adjusting the gap between solar cells, illuminance characteristics of light passing through the gap is investigated; then, by changing the encapsulating material of the surface and back sheet, a new type of solar module is researched. Double-layer module power generating efficiency is examined through a double-layer design. This study uses three solar module designs, modules with solar cell gaps of 1mm, 2mm, and 3mm, to investigate the illuminance characteristics of light passing through the gap. Three surface material and four back sheet material are used to create 12 sets of modules for testing, where the three encapsulation surface materials used are Dupont’s ETFE film, PET film, and diffusion film; the four back sheet materials used are APE, CPE, TPE, and TPT. The module with the best power generating efficiency is then mounted with a silicon thin-film solar cell on the back to produce the double-layer solar module used for testing in this study. Study results show that the power generation for modules with cell gaps of 3mm is higher than those with cell gaps of 1mm by 6.688%. Under standard testing conditions, the module with best results used the diffusion film as the surface encapsulating material and TPE as the back sheet material. The generated power for this module is 7.14% higher than before the encapsulation. Also, after comparing the electrical characteristics of the 12 modules, the TPT-ETFE module has the lowest temperature coefficient, whereas the TPE-ETFE module has the highest. The difference between the temperature coefficient for the two modules is 0.0298%/℃ under open-circuit voltage and 0.0081%/℃ under short-circuit voltage; the difference reaches 0.1132%/℃ when maximum power is generated. Actual outdoor testing results show that under maximum sunlight, the temperature of the TPE-diffusion film module is 4.9℃ lower than that of the TPE-PET module, resulting in a 2.058%/℃ higher power generation. Actual outdoor testing of the double-layer solar module shows that compared to other standard modules with the same coverage area, this module has a 16.85% higher power generation, indicating that the development of this type of module is necessary for Taiwan, whose usable area is limited.

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38

Cheng, Wei-Chung, and 鄭惟中. "Fabrication of Double-Doped High Efficiency White Organic Light-Emitting Diodes." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/59711235559257033637.

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碩士
義守大學
電子工程學系碩士班
94
In general, FIrpic is used as sensitizer to invert the energy transfer between triplet and singlet. By that, we can get high efficiency organic light-emitting diodes. In this study, we dopanted fluorescent materials of DCM2 in blue phosphorescent emissive layer (CBP : FIrpic), and compare its different characteristics of luminance, efficiency, EL peak and CIE, respectively. We found the external quantum efficiency to find the optical thin film thickness and compare different red fluorescent material. And we found the optical structure is ITO/m-MTDATA(15 nm)/NPB(40 nm)/CBP (91.4 wt.%) : FIrpic (8 wt.%) : DCM2 (0.6 wt.%)(35 nm)/TPBi(40 nm)/LiF(0.7 nm)/Al(200 nm).At 4.17mA/cm2 , the OLED exhibited the luminous efficiency of 16 cd/A, the power efficiency of 5 lm/W, and CIE is (0.36,0.39), respectively. In the second, we use CuPC as a material of high extinction coefficient to deaden green and red light. It can adjust CIE coordinateto (0.33,0.35). And we change the different Hole Injection Layer thickness to improve luminous efficiency . Finally, the device has high luminous efficiency of 14.2cd/A at 4.17 mA/cm2.

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39

Chiu, Chuan-Huan, and 丘全煥. "High-Efficiency Phosphorescent Orange Organic Light-Emitting Diode with Double Emission Layers." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/77295875854012966056.

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40

Liu, Yen-Ting, and 劉彥廷. "The Efficiency of Bouyancy Ventilation in Double Metal Walls with Model Experiments." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/434pzb.

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碩士
國立宜蘭大學
土木工程學系碩士班
106
The global average temperature has been increasing with the increase of greenhouse gas emissions in recent years, resulting mostly in the use of air conditioners in indoor spaces for a long time. The indoor temperature is increased especially in the building with an external metal wall and the indoor environment is not suitable for living in the summer. This study hopes to find ways to reduce the use of air conditioners and to reduce the temperature rise in the room. In this study, the experimental model house was used to simulate the thermal environment of the metal wall building after heating. The experimental model house adopts a double-wall thermal buoyancy ventilation system. Since the double-layer wall has openings, the air layer between the double walls is heated and allow the heated air to flow out in the upward direction. The bottom opening allows the cool air to flow into the double walls, forming a solar chimney-like effect and reduce the inner wall temperature. By changing the thickness of the air layer, the length of the chimney, the height of the air inlet of the double walls, various factors are investigated to explore the thermal condition of the inner wall and the indoor environment to find the optimum double-wall thermal buoyancy ventilation system. The experimental results show that the thickness of the air layer is 0.02 m has the largest air flow when the chimney length both of 0.8 m and 0.5 m; The generated air flow rate of the chimney length 0.8 m is greater than the chimney length of 0.5 m. In terms of the height of the air inlet, since the parameters changed in this experiment are not significant, there is no obvious change in the air flow. The inner wall temperature of the double-wall building has significant difference from the temperature of the outer wall, the effect is better when the thickness of the air layer is larger. Thus the heat transfer from the wall to the indoor environment decrease. The increased indoor temperature of the double-wall building is less than the single-wall building that result in a cool indoor environment, the effect is better when the thickness of the air layer is larger. The experimental temperature is compared with the simulated temperature without significant difference.

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41

dewi, cynthia permata, and 辛西雅. "Double Skin Facade Strategy in Reducing Cooling Energy Demand for Energy Efficiency." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/u2h2gt.

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碩士
國立中央大學
營建管理研究所
101
雙層帷幕外牆是目前建築物外牆設計方法之一，此方法可直接提供舒適之室內溫度，以改善冷暖氣之能源消耗。本研究主要目的在於探討在潮溼與悶熱的台灣環境裡，運用自然通風與雙層帷幕外牆之設計，降低既有建築物室內冷卻之能源消耗。本研究運用DesignBuilderEnergyPlus作為模擬工具，分別針對兩棟台灣國立中央大學之既有校舍進行雙層外牆間之空隙與外牆材料變異之模擬，並研究參數改變後之能源差異。第一個模擬情境，僅就單層外牆與雙層外牆之最高受熱面進行數據蒐集與差異探討；第二個模擬情境，假設建築物所有外牆皆採用雙層外牆之設計之差異。在兩個情境模擬下，案例一顯示當採用1.2公尺之空隙設計與Low-E玻璃時，分別可節省31.28% 與34.69%之建築物室內冷卻能耗；案例二之結果亦顯示採用1.2公尺之空隙設計與Low-E (Low Emissivity) 玻璃，是能源效率最高之組合，分別可節省了11.94% 與21.26%之冷卻能耗。而在不同的模擬情境或參數改變下，案例一與案例二分別至少改善8.5MWh及15.33MWh之能耗。此模擬之結果顯示，即使在潮溼與炎熱的台灣夏季，雙層帷幕外牆設計仍具備一定之效能，亦可作為未來台灣建築物節約能源策略之一。

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42

Chung-YuChien and 簡崇育. "High-efficiency Optical Wavelength Conversion Based on Double Λ Four-wave Mixing." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/747gv8.

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43

Chen, Chin-Wei, and 陳慶偉. "A Study of Efficiency of a double-layer Roof in Collecting Solar Energy." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/50939924775909556565.

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碩士
義守大學
機械與自動化工程學系碩士班
98
The purpose of this study is to investigate the efficiency of a double-layer roof in collecting solar energy in the applications to the areas such as relief of building air-conditioning loads. The experimental apparatus were arranged to evaluate the effects of absorbing solar energy. The flow channel is basically formed by an aluminum plate on top of a plywood plate. The geometric configurations in which the effects of absorbing energy is analyzed include: a bare uncovered aluminum plate, a glass-covered aluminum plate, a glass-covered-black-painted aluminum plate, a plate with variable lengths, a flow channel with stuffed material (in the light of enhancement of heat conduction), and a flow channel with variable slanted angles. The experimental results show that the efficiency varies from 0.6 % to 11 % for the geometric configurations mentioned above. An additional study was carried out using CFD simulation to investigate the effects of fins on the aluminum plate. It shows that due to a vastly enhanced heat conduction the efficiency can reach 21.7 % if 50 fins are installed in the channel. The study shows that a double-layer roof can efficiently absorb solar energy and substantially reduce building air-conditioning loads.

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44

Lai, Mu-Jen, and 賴穆人. "Study of Efficiency Droop in InGaN-Based Double-Heterostructure Blue Light-Emitting Diodes." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/03604131557292984608.

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博士
長庚大學
電子工程學系
99
In this thesis, the study of efficiency droop in InGaN-based double-heterostructure (DH) blue light-emitting diodes (LED) were grown on (0001) sapphire substrates by atmosphere-pressure MOCVD (AP-MOCVD) in a Taiyo Nippon Sanso reactor system. The external quantum efficiency (EQE) is improved by 89.3% at a current density of 200 A/cm2 by inserting a 20-nm-thick p-type AlGaN as the electron blocking layer (EBL) replaces the p-type AlGaN/GaN superlattice EBL. It is suggested that the interface states created between the DH active region and EBL might be responsible for the effective level through the other suggested mechanisms besides the Auger loss. It also has shown that the use of a thinner p-type AlGaN EBL in an InGaN-based DH LED can shift the peak EQE to occur at a higher current density and improve the EQE at a further high current density. It is suggested that the improvement of EQE might be attributed to the reduction of Auger loss due to a slight leakage of electron occurred at a critical injection level. Besides, the use of a thicker active region in InGaN-based DH LEDs can shift the peak EQE to occur at a higher current density and improve the EQE droop phenomenon at a further high current density. The result is consistent with the proposal of the efficiency droop is caused by the mechanism of Auger loss. Furthermore, the EQE and efficiency droop in wide-well InGaN/GaN DH LEDs with a trapezoidal-shaped well are significantly improved in the measurement ranges above 135 A/cm2. The result indicates that other than the reduction of Auger loss, the efficiency droop is improved at a higher current density might be due to the higher internal quantum efficiency. Additional experiment shows that the EQE of a thicker gradient-composition InGaN layer inserted under or above the v wide InGaN well is improved by 28.9% and 21.4% over that of samples with a symmetrically trapezoidal-shaped InGaN-based active region at a current density of 260.8 A/cm2. It is suggested that the improvement of EQE might be attributed to the higher confined efficiency of injection carriers due to the increased overlap of electron and hole wave functions. Moreover, the EQE and efficiency droop was improved by inserting an AlGaN barrier between the n-type GaN layer and the InGaN well in wide-well InGaN DH LEDs. It is suggested that the mechanism is attributed to an electron decelerating effect that enlarges the effective active region. Besides, efficiency droop in wide-well InGaN DH LEDs has been investigated by inserting an extra InGaN quantum well into the p-type side as the electron leakage test structure. The LED with a test structure exhibits an improvement of efficiency droop in the measurement range of 83.4 to 521 A/cm2. These results suggest that the electron leakage significantly decreases the peak EQE and shifts the start point of efficiency drop to a higher current density. Additionally, the injection efficiency of holes probably dominates the mechanism of efficiency droop rather than electron leakage in the wide-well InGaN DH LEDs.

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45

Su, Wei-Chun, and 蘇暐畯. "Efficiency of Information Aggregation in Double Auction Market: The Application of Agent-Based Modeling." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/42223228419480988795.

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碩士
淡江大學
產業經濟學系碩士班
100
Zero-Intelligence agents constructs a simple political simulation of market in this paper. Agent-based model based on real political tendencies under the effect of different segregations in the cities and counties of Taiwan. The simulation results compared with the contract of the election for the president of Taiwan, forecasted by XFuture, to observe the market bias. As the simulation, the efficiency of the artificial market is confirmed. The model can match the opinion on the prediction market systematic bias and mistakes approved by Forsythe, et al (1999).As the view of Forsythe, et al (1999), the market involves the wishful thinking effect and the false consensus effect. In addition, the simulation results, the political tendencies in Taiwan, matches the contract of the election for the president of Taiwan forecasted by XFuture.

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46

Hung-TsungHsu and 許弘宗. "Efficiency enhancement for double pipe turbulent convective heat exchangers with staggered oval inner section." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/qw38zk.

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碩士
國立成功大學
機械工程學系
106
Heat exchangers are one of the most commonly used heat transfer devices in many industries or daily life equipment. Among all the heat exchangers，double pipe heat exchangers have specific role and are widely used in oil refinements or chemical industries. Due to the low cost of manufacturing and easy to cooperate with other engineering design. The performance improvement has been a matter of interest for engineers. Numerical simulations of air/water forced convection in an alternating horizontal or vertical oval pipe as inner section double-piped heat exchangers are investigated. In comparison with double circular pipe heat exchangers, the goal is to enhance the total heat transfer efficiency in turbulent flow. Next，we compare the difference between parallel flow and counter flow. Staggered oval tube constructs 8 vortexes in radial directions. The influences of these secondary flow are explained by the field synergy principle，the entransy dissipation rate 、 thermal resistance and performance evaluation criteria are also calculated to evaluate the overall heat transfer ability. The average Nusselt number and the friction factor both increase with increasing Reynolds number. The thermal resistance of oval pipe is lower than circular pipe，but the difference and the performance evaluation criteria both decrease as Reynolds number increases. Furthermore，the results show that counter flow is more efficient than parallel flow.

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47

黃建隆. "Simulation Analysis of Optimal Thermal Efficiency of R134A Refrigerant for Double Tube Heat Exchanger." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/buage4.

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博士
國立高雄科技大學
機械工程系
107
Heat exchangers have always been important devices for advancements and developments in industrial and commercial activities. In industrial production, heat exchangers have a wide scope of applications and are a type of universal technological equipment designed to achieve heat transfer between materials. In this study, COMSOL simulation software was employed and continuity equations, momentum equations, kinetic equations, turbulent models, and appropriate boundary conditions were adopted to investigate the heat transfer characteristics of fluids in helical-coil and U-shaped double tube heat exchangers. In the T7 helical-coil double tube heat exchanger with R134A refrigerant at the tube end, convergence was not attained as the change in thermal efficiency was 0.002; however, in the T7 helical-coil double tube heat exchanger with R134A refrigerant at the shell end, convergence was attained as the change in thermal efficiency was 0.001. This configuration had the best heat transfer efficiency for helical-coil double tube heat exchangers. When the T1 to T8 helical-coil double tube heat exchangers had an equal number of turns, the working fluid R134A had a higher heat transfer efficiency when it was placed at the shell end than when it was placed at the tube end. Therefore, it is suitable for high-temperature R134A refrigerant to flow through the exterior (shell-side) which covers the cooling fluid flowing through the interior (tube-side), so as to achieve a higher heat transfer efficiency. In the S7 U-shaped double tube heat exchanger with R134A refrigerant at the shell end, convergence was attained as the change in thermal efficiency was 0.0011. This configuration had the best heat transfer efficiency for U-shaped double tube heat exchangers. For an equal number of segments in the S1 to S8 U-shaped double tube heat exchangers, the working fluid R134A had a higher heat transfer efficiency when it was placed at the shell end than when it was placed at the tube end. Therefore, it is suitable for high-temperature R134A refrigerant to be flowed through the exterior (shell-side) which covers the cooling fluid flowing through the interior (tube-side), so as to achieve a higher heat transfer efficiency. The U-shaped double tube heat exchangers had better heat transfer efficiencies. At equal heat transfer areas of 823.74 cm2 and at equal numbers of turns/segments (six), the S6 U-shaped double tube heat exchanger enhanced its heat transfer efficiency by 0.002. In other words, it achieved a heat transfer efficiency of 0.9927, which was slightly greater (by 0.0007) than the T7 helical-coil double tube exchanger’s heat transfer efficiency, which was 0.9920. However, the S6 exchanger’s total heat-transfer area was 137.29 cm2 less and the material cost was comparably lower; hence, the S6 U-shaped double tube heat exchanger was the optimal type of heat exchanger in this study.

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48

Lai, Yun-Jr, and 賴昀志. "Improved Current Efficiency of White Hybrid Fluorescent and Phosphorescent OLED with Double-Emission Layers." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/6rqwx7.

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碩士
國立虎尾科技大學
光電與材料科技研究所
100
In this study, yellow phosphorescent organic light-emitting diode based on using phosphorescent bipolar host material (EPH-31) and phosphor dopant (EPY-01) was successfully fabricated at first. Through utilizing the thickness of emitting layer (EML), the charge carrier balance was achieved when thickness of EML was 60 nm. The current efficiency of 38.1 cd/A at 20 mA/cm2 can be obtained. After that, phosphorescent hybrid white organic light-emitting diode (HWOLED) was tried to fabricate by adding a fluorescent blue EML to previous yellow EML. But the HWOLED was unable located in the white light range of CIE coordinate. So it is necessary to change an orange dopant that aid to fabricate the HWOLED. Thermal stability bipolor fluorescent material (UBH-15) with fluorescent dopant (EB-502) as blue fluorescent EML(B-EML) along with (EPH-31) with orange dopant (Os(bpftz)2(PPh2Me)2 as orange phosphorescent EML(O-EML) was used. And then device based on this structure was compared with another bipolar phosphorescent host (26DczPPy). When using 26DczPPy as host material, the HWOLED obtained color stability due to barrier from each B-EML and O-EML energy band. So that carrier can be confine in the interface of two EMLs. Consequently, driving voltage increased from 8 V to 12 V, CIE coordinates only shifted from (0.37,0.37) to (0.35,0.36). There is a big barrier(1.25 eV) due to the difference of HOMO level between 26DczPPy and Os result in the difficultcy of energy-transfer. Performance only reached current efficiency of 12 cd/A. When using EPH-31 as host, the difference of LUMO energy level between EPH-31 and ETL(3TPYMB) was very large (0.95 eV), led electron moving hardly into EML. To solve this problem, co-doping 3TPYMB into EPH-31 structure was used, electron can move easily into EML. Current efficiency of device increased from15.1 cd/A to 17.2 cd/A. Finally, the HWOLED fabrication by utilizing energy-transfer mechanism, using low yellow doping concentration was shown the best current efficiency of 18 cd/A and CIE coordinate is (0.41,0.43).

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49

Gao, Ming-Hong, and 高銘鴻. "Improved power efficiency of white phosphorescent organic light-emitting diode with double-emission layers." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/4845v3.

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碩士
國立虎尾科技大學
光電與材料科技研究所
98
Highly-efficiency white phosphorescent organic light emitting diode (PHOLED) can be achieved by using thin double-emission layers and doping red phosphor on interface between two emission layers. In this study, we utilizes double emitting layers (D-EMLs) structure to enlarge exciton generation zone of devices for the purpose of reducing thickness of emitting layer (EML) and driving voltage for blue PHOLEDs. In experiment, TCTA and 26DCzPPY are used as host material of D-EMLs. Through utilizing the difference on hole mobility of materials in D-EMLs, in combination with doping concentration of FIrpic, recombination zone will be controlled to be at interface between TCTA and 26DCzPPY. In addition, a hole transport-type host material (TCTA) was inserted between HTL and EML as hole buffer layer. The balanced charge carrier can be achieved by adjusting thickness of TCTA to control the amount of hole due to the lower mobility of TCTA than that of hole transport layer (TAPC), and further increased the luminance efficiency. Experimental results had showed that for the blue OLED with brightness of 1000 cd/m2, the driving voltage was 4.4 V, luminance efficiency 35 cd/A, and power efficiency reached 25 lm/W. Finally, the orange-red-emitting phosphor (Os(fptz)2 (PPh2Me)2) was doped at the interface of two emission layers. By using the ability of hole trapping in Os(fptz)2(PPh2Me)2, the holes were trapped in the interface of the double-emission layers, avoided the color-shift of the white OLED device. Experimental results had showed that for the white OLED with brightness of 1000 cd/m2, the driving voltage was 4.9 V, luminance efficiency 35 cd/A, and power efficiency reached 22 lm/W.

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50

Khanh, Mai Phu, and 梅富慶. "Energy Efficiency of Double-Glazed Windows and Their Effects on Window-to-Wall Ratio." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/98953422563714871502.

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碩士
國立臺灣大學
土木工程學研究所
101
Glass is always an important building material, especially in modern era in which the amount of high building has been significantly increased for several decades. However, the use of single-glazed windows has been generating the rise of building energy consumption. Thus, double-glazed window or insulated glazing was invented to minimize heating and cooling loads of building which is a major consumer of energy. This product has been commonly used in cold, hot and arid climate for several decades. This study discusses the effects of double-glazed windows on building’s energy efficiency and their effects on different window to wall ratio in hot humid climate. Five insulated glasses include clear glass; tinted glass; clear reflective glass; low emissivity (low-e) glass and low-e spectral selective glass are examined by DesignBuilder software in a hypothetical building in Taipei to choose appropriate glass units for building in term of reducing energy consumption while changing the window to wall ratio. Afterwards, building energy analysis will be assessed in each double-glazed window unit to investigate the energy efficiency of each one. Subsequently, these assessments will be used to determine energy efficiency of double-glazed units in an exist building located in Taipei.

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