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Rukowicz, Stefan Frederick. "Comparative analysis of alternative fuels for bus transit." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 1.04 Mb., 208 p, 2006. http://proquest.umi.com/pqdlink?did=1163250441&Fmt=7&clientId=8331&RQT=309&VName=PQD.
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Sinuka, Yonwaba. "Performance testing of a diesel engine running on varying blends of jatropha oil, waste cooking oil and diesel fuel." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2436.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016.The high cost of fossil fuels and the fact that the world has arguably reached its peak oil production, has driven the need to seek alternative fuel sources. The main objective of the current study is to determine the performance of a laboratory-mounted diesel engine when fuelled with varying laboratory prepared biofuel and biodiesel and whether the advancement of the injection timing parameters will improve the engine power output and improve the smoke effect of these different fuel blends. The laboratory prepared biofuels used in this project range from 100% bio-fuel (BF100) to 50%, 30% and 10% biodiesel blends (BF50, BF30 and BF10, respectively). It should be noted that these blends are not commercially available, since they were blended in the laboratory specifically for these tests. The overall results of the study show that there is a distinct opportunity for using certain bio-fuel blends in specific applications as the power outputs are no more than one quarter less than that of base diesel. Concomitantly, the smoke opacity in all of the blends is lower than that of base diesel, which is a significant benefit in terms of their overall air emissions.
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Martinez, Heber. "High-temperatire phase transitions on RbH₂PO₄." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Lebo, Stephen J. Scott Robert M. "Lease vs. Purchase analysis of alternative fuel vehicles in the United States Marine Corps." Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Dec/09Dec%5FLebo_Scott.pdf.
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Thesis (M.S. in Management)--Naval Postgraduate School, December 2009.Thesis Advisor: Gates, William R. Second Reader: Summers, Donald E. "December 2009." Description based on title screen as viewed on January 26, 2010. Author(s) subject terms: lease, purchase, Alternative-fuel Vehicle (AFV), incremental costs, salvage values, General Services Administration (GSA), United States Marine Corps (USMC), light-duty vehicle. Includes bibliographical references (p. 61-63). Also available in print.
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Thiets, Robert Clyde. "A method for developing a Triple-Bottom-Line business case for the implementation of alternative fuels and technology." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/29659.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2008.Committee Chair: Bras, Bert; Committee Member: Jeter, Sheldon; Committee Member: McGinnis, Leon. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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McHenry, John Carl Izaak. "The Challenges of Biofuels in Ohio: From the Perspective of Small-Scale Producers." Ohio : Ohio University, 2008. http://www.ohiolink.edu/etd/view.cgi?ohiou1197926303.
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Postma, Marius. "Air-fuel ratio control in spark ignition internal combustion engines using switching LPV techniques." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/30499.
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The Three-Way Catalytic Converter (TWC) is a critical component for the mitigation of tailpipe emissions of modern Internal Combustion (IC) engines. Because the TWC operates effectively only when a stoichiometric ratio of air and fuel is combusted in the engine, accurate control of the air-fuel ratio is required. To track the desired ratio, a switching Linear Parameter Varying (LPV) air-fuel ratio feedback controller, scheduled based on engine speed and air flow, and providing guaranteed L2 performance, is introduced. The controller measures the air-fuel ratio in the exhaust flow using a Universal Exhaust Gas Oxygen (UEGO) sensor and adjusts the amount of fuel injected accordingly.
A detailed model of the air-fuel ratio control problem is developed to demonstrate the non-linear and parameter-dependent nature of the plant, as well as the presence of pure delays. The model’s dynamics vary considerably with engine speed and air flow. A simplified model, widely used in literature and known as a First Order Plus Dead Time (FOPDT) model, is then derived. It effectively captures the control problem using a model which is linear but parameter-varying with engine speed and air flow.
Large variation of the FOPDT model across the engine’s operating range has led to conservative LPV controllers in previous literature. For this reason, the operating range is divided into smaller subregions, and an individual LPV controller is designed for each subregion. The LPV controllers are then switched based on the current engine speed and air flow and are collectively referred to as a switching LPV controller. The controller design problem is expressed as a Linear Matrix Inequality (LMI ) convex optimization problem which can be efficiently solved using available LMI techniques.
Simulations are performed and the air-fuel ratio tracking performance of the switching LPV controller is compared with that of conventional controllers including, H∞ and LPV, as well as a novel adaptive controller. The switching LPV controller achieves improved performance over the complete operating range of the engine.
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Moon, Seung-Ryul. "Multiphase Isolated DC-DC Converters for Low-Voltage High-Power Fuel Cell Applications." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/32442.
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Fuel cells provide a clean and highly efficient energy source for power generation; however, in order to efficiently utilize the energy from fuel cells, a power conditioning system is required. Typical fuel cell systems for stand-alone and utility grid-tied stationary power applications are found mostly with low nominal output voltages around 24 V and 48 V, and power levels are found to be 3 to 10 kW [1][2]. A power conditioning system for such applications generally consists of a dc-dc converter and a dc-ac inverter, and the dc-dc converter for low-voltage, high-power fuel cells must deal with a high voltage step-up conversion ratio and high input currents. Although many dc-dc converters have been proposed, most deal with high input voltage systems that focus on step-down applications, and such dc-dc converters are not suitable for low-voltage, high-power fuel cell applications.
Multiphase isolated dc-dc converters offer several advantages that are very desirable in low-voltage, high-power fuel cell applications. First, a multiphase is constructed with paralleled phases, which increase power rating and current handling capability for high input current. Second, an interleaving control scheme produces a high operating frequency with a low switching frequency, and the high operating frequency reduces size of passive components. Thirdly, use of a transformer provides electrical isolation and a high conversion ratio. Lastly, several multiphase converters are capable of soft-switching operation, which increases converter efficiency.
This thesis examines two highly efficient, soft-switching dc-dc converters that are targeted for fuel cell applications. The thesis also describes the convertersâ basic operating principles and analyzes performance for low-voltage, high-power fuel cell applications. 5-kW prototypes for each converter are built and tested with a fuel cell simulator. Experimental switching waveforms and efficiency profiles are shown to support the described basic principles and the analysis. Major features and differences between these two converters are also discussed.Master of Science
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Swart, Dustin W. "The utilization of alternative fuels in the production of Portland cement." Auburn, Ala., 2007. http://repo.lib.auburn.edu/07M%20Theses/SWART_DUSTIN_26.pdf.
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Miwa, Hidekazu. "High-Efficiency Low-Voltage High-Current Power Stage Design Considerations for Fuel Cell Power Conditioning Systems." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/42519.
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Fuel cells typically produce low-voltage high-current output because their individual cell voltage is low, and it is nontrivial to balance for a high-voltage stack. In addition, the output voltage of fuel cells varies depending on load conditions. Due to the variable low voltage output, the energy produced by fuel cells typically requires power conditioning systems to transform the unregulated source energy into more useful energy format. When evaluating power conditioning systems, efficiency and reliability are critical. The power conditioning systems should be efficient in order to prevent excess waste of energy. Since loss is dissipated as heat, efficiency directly affects system reliability as well. High temperatures negatively affect system reliability. Components are much more likely to fail at high temperatures. In order to obtain excellent efficiency and system reliability, low-voltage high-current power conditioning systems should be carefully designed.
Low-voltage high-current systems require carefully designed PCB layouts and bus bars. The bus bar and PCB trace lengths should be minimized. Therefore, each needs to be designed with the other in mind. Excessive PCB and bus bar lengths can introduce parasitic inductances and resistances which are detrimental to system performance. In addition, thermal management is critical. High power systems must have sufficient cooling in order to maintain reliable operation.
Many sources of loss exist for converters. For low-voltage high-current systems, conduction loss and switching loss may be significant. Other potential non-trivial sources of loss include magnetic losses, copper losses, contact and termination losses, skin effect losses, snubber losses, capacitor equivalent series resistance (ESR) losses, and body diode related losses. Many of the losses can be avoided by carefully designing the system. Therefore, in order to optimize efficiency, the designer should be aware of which components contribute significant amounts of loss. Loss analysis may be performed in order to determine the various sources of loss. The system efficiency can be improved by optimizing components that contribute the most loss.
This thesis surveys some potential topologies suitable for low-voltage high-current systems. One low-voltage high-current system in particular is analyzed in detail. The system is called the V6, which consists of six phase legs, and is arranged as a three full-bridge phase-shift modulated converter to step-up voltage for distributed generation applications. The V6 converter has current handling requirements of up to 120A. Basic operation and performance is analyzed for the V6 converter. The loss within the V6 converter is modeled and efficiency is estimated. Calculations are compared with experimental results. Efficiency improvement through parasitic loss reduction is proposed by analyzing the losses of the V6 converter. Substantial power savings are confirmed with prototypes and experimental results. Loss analysis is utilized in order to obtain high efficiency with the V6 converter. Considerations for greater current levels of up to 400A are also discussed. The greater current handling requirements create additional system issues. When considering such high current levels, parallel devices or modules are required. Power stage design, layout, and bus bar issues due to the high current nature of the system are discussed.Master of Science
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Sendich, Elizabeth Diane. "Modeling and analysis of the biorefinery integrated with the agricultural landscape." Diss., Connect to online resource - MSU authorized users, 2008.
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Felder, Frank Andrew. "Hedging natural gas price risk by electric utilities : a comparison of fuel switching to financial contracts." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/28123.
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Akkapeddi, Srikanth Schindler Anton K. "Alternative solid fuels for the production of Portland cement." Auburn, Ala., 2008. http://hdl.handle.net/10415/1432.
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Klein, Matthew. "Cap and trade or a carbon tax? how to reduce CO₂ emissions /." Diss., Connect to the thesis, 2009. http://hdl.handle.net/10066/3808.
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Song, Yu Jin. "Analysis and design of high frequency link power conversion systems for fuel cell power conditioning." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/2678.
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In this dissertation, new high frequency link power conversion systems for the fuel cell power conditioning are proposed to improve the performance and optimize the cost, size, and weight of the power conversion systems. The first study proposes a new soft switching technique for the phase-shift controlled bi-directional dc-dc converter. The described dc-dc converter employs a low profile high frequency transformer and two active full-bridge converters for bidirectional power flow capability. The proposed new soft switching technique guarantees soft switching over wide range from no load to full load without any additional circuit components. The load range for proposed soft switching technique is analyzed by mathematical approach with equivalent circuits and verified by experiments. The second study describes a boost converter cascaded high frequency link direct dc-ac converter suitable for fuel cell power sources. A new multi-loop control for a boost converter to reduce the low frequency input current harmonics drawn from the fuel cell is proposed, and a new PWM technique for the cycloconverter at the secondary to reject the low order harmonics in the output voltages is presented. The performance of the proposed scheme is verified by the various simulations and experiments, and their trade-offs are described in detail using mathematical evaluation approach. The third study proposes a current-fed high frequency link direct dc-ac converter suitable for residential fuel cell power systems. The high frequency full-bridge inverter at the primary generates sinusoidally PWM modulated current pulses with zero current switching (ZCS), and the cycloconverter at the secondary which consists of only two bidirectional switches and output filter capacitors produces sinusoidally modulated 60Hz split single phase output voltage waveforms with near zero current switching. The active harmonic filter connected to the input terminal compensates the low order input current harmonics drawn from the fuel cell without long-term energy storage devices such as batteries and super capacitors.
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Liu, Changrong. "A Novel High-Power High-Efficiency Three-Phase Phase-Shift DC/DC Converter for Fuel Cell Applications." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/26048.
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Fuel cells are a clean, high-efficiency source for power generation. This innovative technology is going to penetrate all aspects in our life, from utility distributed power, transportation applications, down to power sources for portable devices such as laptop computer and cell phones. To enable the usage of fuel cell, developing power converters dedicated for fuel cells becomes imminent.
Currently, the full-bridge converter is the dominating topology in high power dc/dc applications. Although multiphase converters have been proposed, most of them are dealing with high input-voltage systems, and their device characteristic is not suitable for a low voltage source such as a fuel cell. For a high power fuel cell system, high voltage conversion ratios and high input currents are the major obstacles to achieving high-efficiency power conversions. This dissertation proposes a novel 3-phase 6-leg dc/dc power converter with transformer isolation to overcome these obstacles. Major features of the proposed converter include: (1) Increase converter power rating by paralleling phases, not by paralleling multiple devices; (2) Double the output voltage by transformer delta-wye connection, thus lowering the turns-ratio; (3) Reduce the size of output filter and input dc bus capacitor with interleaved control; (4) Achieve Zero-Voltage Zero-Current Switching (ZVZCS) over a wide load range without auxiliary circuitry. High conversion efficiency above 96% is verified with different measurement approaches in experiments.
This dissertation also presents the power stage and control design for the proposed converter. Control design guideline is provided and the design result is confirmed with both simulation and hardware experiments. When using the fuel cell for stationary utility power applications, a low-frequency ripple interaction was identified among fuel cell, dc/dc converter and dc/ac inverter. This low frequency ripple tends to not only damage the fuel cell, but also reduce the source capability. This dissertation also investigates the mechanism of ripple current propagation and exploits the solutions. A linearized ac model is derived and used to explain the ripple propagation. An active ripple reduction technique by the use of the current loop control is proposed. This active current loop control does not add extra converters or expensive energy storage components. Rather, it allows a reduction in capacitance because the ripple current flowing into the capacitor is substantially reduced, and less capacitance can be used while maintaining a clean dc bus voltage. The design process and guideline for the proposed control is suggested, and the effectiveness of this active control is validated by both simulation and experimental results.Ph. D.
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Olarte, Mariefel Valenzuela. "Base-catalyzed depolymerization of lignin and hydrodeoxygenation of lignin model compounds for alternative fuel production." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39613.
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This study considered the potential use of lignin as possible renewable fuel and chemical feedstock source. Among the various polymers present in lignocellulosic biomass, the polyaromatic lignin is the one component that is most chemically similar to petroleum. However, it still contains a much larger amount of oxygen compared to crude oil. As such, two strategies were employed in this study: (1) studying the lignin depolymerization in the presence of high temperature and base catalysts; and, (2) employing hydrodeoxygenation as a means to decrease the O/C ratio in lignin-derived model compounds.
The base-catalyzed depolymerization (BCD) of organosolv lignin was done in a 500-mL Monel Parr reactor at temperatures ranging from 165°C to 350°C. Complete solubilization of lignin derivatives was possible in the presence of NaOH and KOH, except at 350°C. NMR experiments revealed formation of oxidized groups (carboxylic and hydroxyl groups) as well as alkyl groups. On the other hand, the use of NH4OH showed N incorporation. Identified and quantified DCM-soluble monomeric compounds were at most 6% of the starting material and are mainly phenolic. This study revealed the apparent susceptibility of syringyl units over guaiacyl units in BCD. This could in turn guide the choice of substrate on which base-catalyzed depolymerization could be applied.
Syringaldehyde was used as the starting material to study batch hydrodeoxygenation (HDO) using several non-cobalt/molybdenum based catalysts. A 50-ml Parr reactor was used, pressurized by 1000 psig of H2 and heated to 300°C. Nickel based catalysts (nickel phosphide, nickel oxide and nickel phosphate) as well as supported precious metals (Pt and Pd) were tested as HDO catalysts. Of the three O-containing functional groups of syringaldehyde, the aldehydic group was found to be the most susceptible. In the presence of the Al2O3-supported catalysts, the methyl groups liberated were found to be incorporated back into the aromatic ring, forming alkylated compounds.
In the last section of this dissertation, hydrothermally synthesized supported Ni on mesoporous silica (MCF) and acid catalysts (HY and H-Al-MCF) were used for probing the effect of bifunctional metal-acid catalysis on phenol hydrodeoxygenation/hydrogenation. Catalyst configurations were varied from the previously studied wet-impregnated Pt/HY catalyst. Based on a hypothesis that coking catalyzed by the acidic zeolite in the wet impregnated Pt/HY catalyst was the main cause of catalyst deactivation and decreased phenol conversion, separately synthesized metal and acid catalyst systems were tested. Complete phenol conversion was sustained for at least three times longer in a continuous flow reactor operated at 200°C and 0.79 MPa of flowing H2. The separation of the metal and acid sites generated a tunable system capable of producing cyclohexanol, cyclohexane or cyclohexene at very high selectivities, even achieving 99% selectivities for cyclohexane.
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Holmes, Erin J. "Growing ethanol an analysis of policy instrument selection in the fifty American states /." Diss., Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-02062009-084419.
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Ho, Kwai-fung Martha, and 何桂鳳. "A study on the efficiency and effectiveness of using alternative fuel vehicles to improve air quality in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31255498.
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Hassan, S. M. Nazmul. "Techno-Economic Study of CO2 Capture Process for Cement Plants." Thesis, University of Waterloo, 2005. http://hdl.handle.net/10012/925.
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Carbon dioxide is considered to be the major source of GHG responsible for global warming; man-made CO2 contributes approximately 63. 5% to all greenhouse gases. The cement industry is responsible for approximately 5% of global anthropogenic carbon dioxide emissions emitting nearly 900 kg of CO2 for every 1000 kg of cement produced! Amine absorption processes in particular the monoethanolamine (MEA) based process, is considered to be a viable technology for capturing CO2 from low-pressure flue gas streams because of its fast reaction rate with CO2 and low cost of raw materials compared to other amines. However, MEA absorption process is associated with high capital and operating costs because a significant amount of energy is required for solvent regeneration and severe operating problems such as corrosion, solvent loss and solvent degradation.
This research was motivated by the need to design size and cost analysis of CO2 capture process from cement industry. MEA based absorption process was used as a potential technique to model CO2 capture from cement plants. In this research four cases were considered all to reach a CO2 purity of 98% i) the plant operates at the highest capacity ii) the plant operates at average load iii) the plant operates at minimum operating capacity and iv) switching to a lower carbon content fuel at average plant load. A comparison among four cases were performed to determine the best operating conditions for capturing CO2 from cement plants. A sensitivity analysis of the economics to the lean loading and percent recovery were carried out as well as the different absorber and striper tray combinations.
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Zhang, Qingguo. "Lean blowoff characteristics of swirling H2/CO/CH4 Flames." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22641.
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This thesis describes an experimental investigation of lean blowoff for H2/CO/CH4 mixtures in a swirling combustor. This investigation consisted of three thrusts. The first thrust focused on correlations of the lean blowoff limits of H2/CO/CH4 mixtures under different test conditions. It was found that a classical Damköhler number approach with a diffusion correction could correlate blowoff sensitivities to fuel composition over a range of conditions.
The second part of this thesis describes the qualitative flame dynamics near blowoff by systematically characterizing the blowoff phenomenology as a function of hydrogen level in the fuel. These near blowoff dynamics are very complex, and are influenced by both fluid mechanics and chemical kinetics; in particular, the role of thermal expansion across the flame and extinction strain rate were suggested to be critical in describing these influences.
The third part of this thesis quantitatively analyzed strain characteristics in the vicinity of the attachment point of stable and near blowoff flames. Surprisingly, it was found that in this shear layer stabilized flame, flow deceleration is the key contributor to flame strain, with flow shear playing a relatively negligible role. Near the premixer exit, due to strong flow deceleration, the flame is negatively strained i.e., compressed. Moving downstream, the strain rate increases towards zero and then becomes positive, where flames are stretched. As the flame moves toward blowoff, holes begin to form in the flame sheet, with a progressively higher probability of occurrence as one moves downstream. It is suggested that new holes form with a more uniform probability, but that this behavior reflects the convection of flame holes downstream by the flow.
It has been shown in prior studies, and affirmed in this work, that flames approach blowoff by first passing through a transient phase manifested by local extinction events and the appearance of holes on the flame. A key conclusion of this work is that the onset of this boundary occurs at a nearly constant extinction strain rate. As such, it is suggested that Damköhler number scalings do not describe blowoff itself, but rather the occurrence of this first stage of blowoff. Given the correspondence between this first stage and the actual blowoff event, this explains the success of classical Damköhler number scalings in describing blowoff, such as shown in the first thrust of this thesis. The physics process associated with the actual blowoff event is still unclear and remains a key task for future work.
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Gupta, Kushagra. "Techno-economic analysis of implementing energy-efficiency and alternative fuels in Indonesia using OSeMOSYS." Thesis, KTH, Energiteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280820.
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Indonesia’s energy demand has been growing rapidly driven by increasing population, urbanization, and rapid economic growth. With increasing energy demand, the emissions associated with the energy sector continue to increase. With the gradual increase in demand and dominant share of fossil fuels in the energy mix, implementing the energy efficiency measures is crucial for Indonesia to achieve its energy and climate goals. From the policy perspective, National Energy plan of Indonesia aims to achieve higher levels of energy efficiency to reduce the overall energy intensity. Indonesia also has commitments to reduce greenhouse gas emissions and achieve SDG targets. This report reviews the current status of energy demand and energy efficiency in Indonesia and evaluates the potential of implementing energy efficiency measures and fuel switching options to achieve future low carbon energy future. Long term energy model of Indonesia is modelled using the open-source modelling tool OSeMOSYS. Different scenarios have been developed to investigate the outcome of implementing energy efficiency and fuel switching measures in the Residential, Commercial, and Transportation sectors. The results are presented in terms of reduction in total final energy use, greenhouse gas emissions, and local air pollution. Cost-Benefit analysis of the applied measures present their financial feasibility. With the deployment of efficient appliances, up to 30% electricity savings can be achieved in the residential and commercial sector. Vehicle electrification can contribute towards reduction in annual energy use by 48% by the end of modelling period. Measures in the residential and commercial sector directly contribute towards emission reductions. Vehicle electrification does not show proportionate reduction in emissions compared to energy use reduction due to high carbon intensity of the electricity grid. However, significant reduction in local air pollutants can be achieved. Cost benefit analysis shows that deployment of efficient appliances is financially feasible with maximum 2 years of payback period. On the other hand, successful deployment of electric vehicles will require tangible support from government due to its high price premium compared to conventional vehicles. Energy efficiency measures and fuel switching also contribute substantially to achieving Sustainable Development Goal 7.3. In conclusion, this study presents a set of technically and economically feasible energy system development options for Indonesia. From the modelling perspective, this study identifies ways to implement demand side management measures in the energy supply modelling system OSeMOSYS.Indonesiens energibehov har ökat snabbt drivet av ökande befolkning, urbanisering och snabbekonomisk tillväxt. Med ökande energibehov fortsätter utsläppen i energisektorn att öka. Medden gradvisa ökningen i efterfrågan och den dominerande andelen fossila bränslen ienergimixen är genomförandet av energieffektivitetsåtgärderna avgörande för att Indonesienska uppnå sina energi- och klimatmål. Ur politiskt perspektiv syftar Indonesiens nationella energiplan till att uppnå högre nivåer av energieffektivitet för att minska den totala energiintensiteten. Indonesien har också åtaganden att minska utsläppen av växthusgaser och uppnå SDG-mål. Denna rapport granskar den aktuella statusen för efterfrågan på energi och energieffektivitet i Indonesien och utvärderar potentialen för att genomföra energieffektivitetsåtgärder och alternativ för bränsleomkoppling för att uppnå framtida energiförbrukning med låg koldioxid. Indonesiens långsiktiga energimodell modelleras med hjälp av open-sourcemodelleringsverktyget OSeMOSYS. Olika scenarier har utvecklats för att undersöka resultatet av genomförande av energieffektivitet och bränsleomkopplingsåtgärder inom bostads-, kommersiellt och transportsektorn. Resultaten presenteras i termer av minskning av den totalaslutliga energiförbrukningen, växthusgasutsläpp och lokal luftföroreningar. Kostnadsnyttoanalys av de tillämpade åtgärderna utgör deras ekonomiska genomförbarhet. Med användning av effektiva apparater kan upp till 30% elbesparing uppnås i bostads- och affärssektorn. Fordonselektrifiering kan bidra till minskning av den årliga energiförbrukningen med 48% i slutet av modelleringsperioden. Åtgärder inom bostads- och kommersiell sektor bidrar direkt till utsläppsminskningar. Fordonselektrifiering visar inte proportionell minskning av utsläpp jämfört med energiförbrukningen på grund av hög kolintensitet i elnätet. Emellertid kan en betydande minskning av lokala luftföroreningar uppnås. Kostnads för delningsanalys visar att distribution av effektiva apparater är ekonomiskt möjlig med maximalt 2 års återbetalningsperiod. Å andra sidan kommer framgångsrik distribution av elfordon att kräva konkret stöd från regeringen på grund av dess höga prispremie jämfört med konventionella fordon. Energi effektivitetsåtgärder och bränsleomkoppling bidrar också väsentligt till att uppnå mål för hållbar utveckling 7.3. Sammanfattningsvis presenterar denna studie en uppsättning tekniska och ekonomiskt genomförbara energisystemutvecklingsalternativ för Indonesien. Från modelleringsperspektivet identifierar denna studie sätt att implementera hanteringsåtgärder på efterfrågesidan i modelleringssystemet för energiförsörjning OSeMOSYS.
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Gordon, Reuven Eli. "Contention resolution and label switching in optical multiprotocol label switching networks." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98962.
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The last decade has witnessed an explosive growth in internet protocol, packet based traffic. Although long-haul fiber backbone networks provide capacities on the order of Tb/s, a bottleneck at the access network has arisen due to electronic domain signal processing. Recent developments in optical multiprotocol label switching (MPLS) access networks promise to remove this bottleneck and allow Gb/s capacities per user and satisfy foreseeable future bandwidth requirements.This thesis introduces an optical MPLS network where packet payloads are wavelength multiplexed and labels correspond to spectral optical code division multiple access codes. Using this network, we examine payload and label processing issues in nodes as packets transit through the core network. We develop a software package to model data traffic flow in a node, where reduced sets of realistic wavelength converters are used to mitigate payload wavelength contentions. Furthermore, we successfully demonstrate an all-photonic label switching system to convert (7,4) spectral m-sequence labels using commercially available optical components.
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Bertrand, Vincent. "The european union emission trading scheme and energy markets : economic and financial analysis." Phd thesis, Université de Franche-Comté, 2012. http://tel.archives-ouvertes.fr/tel-00930886.
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This thesis investigates relationships between the European Union Emission Trading Scheme (EU ETS) and energy markets. A special focus is given to fuel switching, the main shortterm abatement measure within the EU ETS. This consists in substituting Combined Cycle Gas Turbines (CCGTs) for hard-coal plants in off-peak power generation. Thereby coal plants run for shorter periods, which allows power producers to reduce their CO2 emissions. In Chapter 1, we outline different approaches explaining relationships between carbon and energy markets. We also review the literature relating to these issues. Next, we further describe the fuel switching process and, in particular, we analyze the influence of energy and environmental efficiency of thermal power plants (coal and gas) on fuel switching. In Chapter 2, we provide a theoretical analysis that shows how differences in the efficiency of CCGTs can rule interactions between gas and carbon prices. The main result shows that the allowance price becomes more sensitive to the gas price when the level of CO2 emissions increases. In Chapter 3, we examine interactions between carbon, coal, gas and electricity prices in an empirical study. Among the main results, we find that there is a significant link between carbon and gas prices in the long-run equilibrium.In Chapter 4, we analyze the cross-market price discovery process between gas and CO2 markets. We identified in previous chapters that there is a robust significant link between gas and CO2 markets. They are linked commodities, and their prices are affected by the same information. In an empirical analysis, we find that the carbon market is the leader in cross-market price discovery process.
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Han, Heesup. "Restaurant customers' emotional experiences and perceived switching barriers : a full-service restaurant setting." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/438.
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Simard, Marc. "Optical Switching Based on MEMS Micromotors." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95593.
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This thesis explores the design of an optical switch based on MEMS micromotors. A basic layout of the switch is presented and a scalability study is made. Micromotor designs were also studied and fabricated via the Multi-User MEMS Processes (MUMPs) foundry service. The resulting motors were tested to obtain both mechanical and optical measurements. From the results, it was shown that micromotors could be successfully built using the MUMPs process. Speeds ranged from 0 to 138 Hz, with activation voltages as low as 26 V. Successful motors had rotor sizes of 400 μm, with grating sizes of 80 μm in diameter. Optical efficiency (using non-optimized gratings) was found to be 3.5 % for one of the 1st orders .L'objectif de cette thèse est la conception d'un commutateur optique utilisant des micro moteurs en tant que mechanisme de redirection de la lumière. Une étude des concepts de bases ainsi que de la possibilité d'expansion à plusieurs ports du commutateurs est faite. De plus, l'étude de micromoteurs ainsi que leur implémentation via le procédé de fabrication MUMPs (Multi-User MEMS Processes) est faite. Les moteurs ont été testés afin d'en obtenir des résultats tant méchaniques qu'optics. Il a ainsi été démontré que la fabrication de micro moteurs fonctionnels via le procédé choisi est une solution viable. Des vitesses allant de 0 à 138Hz ont été démontrées, avec des voltages partant de 26 V. Les moteurs ayant le plus de succès avaint des rotor de 400 μm de diamètre, avec des éléments diffractifs de 80 μm de diamètre. L'efficacité de ces éléments diffractifs a été mesurée à 3.5 % (pour le 1er ordre). fr
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Shenoy, Sandeep P. (Sandeep Pundalika). "Switching activity in CMOS digital circuits." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=24071.
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In (48, 47) a pattern-independent method to estimate the switching activity of a CMOS circuit was presented. The technique relies on the use of abstract waveforms, described down to the level of individual transitions, which are propagated through the circuit. In order to improve the switching activity estimate so obtained, case analysis is undertaken on nodes with large fanout.The objective of this thesis is to develop and implement a method to further improve upon the switching activity estimate through consideration of reconvergent fanout regions in the circuit. The idea is to impose functional consistency upon the waveforms at the nodes of a subset of the circuit to obtain an exact count of the number of transitions and potentially the exact waveforms which give rise to that. The result is the same as if an exact simulation was performed, but the novelty here is in the technique. An exact simulation would have exponential complexity as all possible waveforms on the PIs to the sub-circuit would have to be enumerated. Branch and bound techniques are used here instead to execute a progressively limited analysis which avoids exponential complexity. Furthermore heuristics are used to speed up the algorithm.
In addition a simple greedy algorithm has been developed and implemented to identify the sub-circuits where application of the above described technique would have the best results. The greedy algorithm represents only a preliminary step, and further work needs to be done on a more comprehensive circuit partitioning technique.
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Kang, Wen. "A line and load independent zero voltage switching dc/dc full bridge converter topology." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ59307.pdf.
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Evéquoz, Claude. "Message delay models of packet-switching networks." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74223.
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The prediction of mean end-to-end delay of multiple packet messages is the focus of this thesis. The models established are of great importance to network designers as they provide the basis for meeting user requirements for time delays and for network throughput.Two distinct models are developed depending upon the traffic load requested by network users. The first model considers traffic conditions in which the traffic demand heavily loads the computer network. Mean end-to-end message delays are computed by assuming the existence of product form solution of the obtained closed queueing network model. Heuristics are developed and are validated via simulation to render the computation feasible and to extend the solution method to non product form networks.
Under light traffic conditions, clusters of packets resulting from message segmentation may enter the computer network. To this end, algorithms are developed to determine the network performance measures of closed queueing networks in which bulk transitions are possible. A second message delay model is then developed to take into account the clustered arrival of packets to the network. All models and heuristics are validated via simulation.
Finally, the appropriate length of the packets into which a message should be segmented is addressed. The performance tradeoff between message delay and throughput is discussed. Boundaries delimiting the packet size to meet user requirements are established for delay and throughput.
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Gall, Jonathan Henrik. "Zero-Voltage-Switching PWM Full-Bridge Converter for Onboard Charging of Battery of Electric Vehicles." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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This thesis gives a description of working principles of a Phase-Shifted Full-Bride PWM ZVS converter using a Full-Wave rectifying output as well as a Double Current Rectifier. After a description of each topology and some differences between the two topologies, a hybrid solution is presented. The hybrid configuration is a combined FW and DCR, in an interleaved connection. By the opening and closing of a switch that is located between the two output stages, either a DCR-DCR or DCR-FW rectifying output stage is used for the converter. This allows for dynamic turns ratio of the step-up transformer of the converter, as well as reduced primary and secondary side currents.
The voltage for when to switch between the two output configurations is derived analytically. Simulations carried out in LTSpice to verify the analytical results and the hypothesis of reduced currents and losses are presented in the end.
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Haliplii, Rostislav. "Hedging in alternative aarkets." Thesis, Paris 1, 2020. http://www.theses.fr/2020PA01E059.
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La recherche faisant l'objet de cette thèse se concentre sur deux marchés alternatifs: les cryptomonnaies et les produits pétroliers. La plupart des marchés alternatifs sont loin d'être efficaces, et cela génère beaucoup de défis en termes de modélisation. Les modèles basés sur des distributions gaussiennes sont toujours le choix le plus populaire pour les analystes financiers quantitatifs et sont mis en œuvre même sur des marchés qui sont loin d'être efficients. Un cadre de modélisation solide pour l'alternative des actifs doit partir d'une distribution non gaussienne. Par conséquent, tout au long de cette thèse, le thème général de toutes les simulations et estimations est l'utilisation de l'hyperbolique généralisée distributions. Cette approche a une double justification. D'une part, il est essentiel pour développer un cadre quantitatif tranchant au-delà de l'univers gaussien, tester les performances du nouveau modèle dans des situations réelles. D'autre part, les marchés faisant l'objet de cette recherche (produits pétroliers et crypte-monnaies) n'ont ni les fondamentaux ni le comportement empirique qui pourraient justifier la modélisation traditionnelleThe research making the object of this thesis focuses on two alternative markets: cryptocurrencies and oil-distillates. Most alternative markets are far from being efficient, and this generates a lot of challenges in terms of modelling. Models based on Gaussian distributions are still the most popular choice for quantitative analysts and are implemented even in markets which are far from being efficient. A sound modelling framework for alternative assets should start from non-Gaussian distribution. Therefore, throughout this thesis, the overarching theme for ail simulations and estimations is the use of generalized hyperbolic distributions. This approach has a two-edged justification. On the one hand, it is critical to developing a fully-edged quantitative framework beyond the Gaussian universe, thereby testing the performance of the new mode! in real-life situations. On the other hand, the markets making the object of this research (oil distillates and crypto-currencies) have neither the fundamentals nor the empirical behaviour that could justify traditional modelling
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Gagnon, Stéphane. "Virtual hardware based ATM switching node test system." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23260.
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As Asynchronous Transfer Mode (ATM) emerges as the best technology for suitably integrating the various traffic classes of present and future broadband integrated services digital networks, testing methods and equipments associated with this technology have to be devised. The high bandwidth of ATM as well as its flexibility in terms of supported traffic types prevent the use of conventional approaches to network technology testing. Particularly, the conformance assessment of ATM switching nodes becomes a very challenging task because of their complex functionality and the sophisticated performance issues involved. This thesis presents a design and implementation of an ATM switching node test system based on static RAM type Field-Programmable Gate Array (FPGA) technology. Real-time reprogrammability of the FPGA technology used results in a high functionality virtual hardware system requiring very few hardware components. The test system features the high performance Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH) fibre protocols as the physical link for the connection to the switching nodes under test.
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Rutherford, Olivia Ines. "Splice switching small molecules as inducers of apoptosis." Thesis, University of Strathclyde, 2018. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=30918.
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One of the most important post-transcriptional processes that occurs during the transcription of DNA to RNA is alternative splicing. Alternative splicing is a highly regulated process that occurs during gene expression and is the basis for the large protein diversity that is achieved in eukaryotes. It allows multiple protein isoforms to be formed from one pre-mRNA sequence. Although alternative splicing is necessary to provide protein diversity, aberrant splicing can also lead to diseases such as cancer. Recently, there has been an interest in the ability of small molecules to exogenously modulate alternative splicing as therapeutics for aberrant splicing diseases. The ellipticine analogue GQC-05 has been found to have splice switching capabilities towards the apoptotic oncogene Bcl-x, however the mode of action of GQC-05 is not understood. This thesis describes efforts made to elucidate the mode of action of GQC-05 by synthesising a library of ellipticine derivatives for testing in a range of biochemical assays to evaluate their ability to bind and stabilise Bcl-x. The background to alternative RNA splicing and the aberrant splicing process that can lead to diseases such as cancer is introduced in Chapter 1. The importance of the oncogene Bcl-x and the current limitations in targeting it therapeutically are also presented. Chapter 2 investigates current literature methods to prepare 9-methoxyellipticine. However it is found that these methods do not provide a modular framework in which to systematically alter the ellipticine structure. Chapter 3 describes the development of a one-pot, sequential, palladium cross-coupling methodology to construct the backbone of the natural product ellipticine. This methodology has been further extended to synthesise a range of ellipticine analogues with modular changes throughout the structure. Chapter 4 examines the ability of the ellipticine derivatives synthesised to stabilise a putative Gquadruplex structure within Bcl-x through the use of UV melting assays. The ligands have also been investigated for their ability to stabilise a range of competitor DNA structures with the help of FRET melting assays. The interaction of GQC-05 with the putative Bcl-x G-quadruplex has also initially been examined using NMR spectroscopy. And finally, the ellipticine derivatives have been tested in Bcl-x in vitro splicing assays to determine whether they are capable of exerting the same splicing modulation on Bcl-x as their parent compound GQC-05.
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Chudý, Andrej. "DC/DC měniče pro průmyslové napájecí zdroje." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442795.
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This diploma thesis deals with design and comparison of selected DC/DC converters, where the better of them is practically realized. The first part of the diploma thesis is focused on the general analysis of DC/DC power converters. The following part is theoretical analysis focused on the first selected topology – step-up converter. The second analysed topology is forward converter with full bridge on the primary side. The theoretical analysis also includes a description of synchronous rectifier, the differences between hard and soft switching, and the types of secondary rectifiers. Another part specializes in the detailed calculation of main components of selected converters and their subsequent power dimensioning. Both designed topologies are compared according to the required aspects. The selected better topology is supplemented by the design of control circuits and an auxiliary power supply. Practical realization of converter and commissioning follows. The diploma thesis ends with verification measurements on the realized converter and their subsequent analysis.
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Maksimcev, Mirko D. "Energy considerations in power system damping by reactorcapacitor switching." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23370.
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Flexible AC transmission systems (FACTS) technology is an emerging new technology which can be efficiently used in power system damping. Objectives of this study are the considerations of the energy flow involved in power system damping by functional switching of series capacitors and/or reactors. The principal questions are how the energy transiently flows through the network and what is its impact on damping of mechanical oscillations.The analytical studies (covered in Chapter 1) reveal that the magnetic and electrostatic energy are constantly stored in the reactive components of the transmission system. The energy stored in a series compensated line is greater than the energy stored in an uncompensated line of equal transmission capability. The transient energy flow caused by characteristic switching in transmission systems is studied analytically in Chapter 2. Switching of an additional line or switching of series capacitors initiates transient charging/discharging of the line towards its new steady-state energy level which is always associated with losses. Power transfer characteristics of the systems which are equivalent in steady-state operation (parallel lines vs. an equivalent series compensated line) have quite different transient power transfer characteristics. These differences are related to different stored energies in such systems. System sources participate in all transient energy flow phenomena.
The impact of series compensation switching upon the mechanical oscillation damping was demonstrated by simulations presented in Chapter 3. Thyristor switched variable series compensation (VSC) is simulated in order to verify the conclusions of the analytical studies regarding the charging/discharging energy of the line.
The switching of reactive power components for the purpose of power system oscillation damping involves significant energy impulses in and out of the machines. Therefore, stability studies have to be performed by simulation which involves detailed representation of electromagnetic phenomena (EMTP for example).
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Alghamdi, Mohammad. "A spurious-free switching buck converter for portable applications." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107737.
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DC–DC buck converters are essential to extending the standby time and maximizing the battery life of portable electronic devices. In a portable environment, load conditions vary drastically from heavy-load to light-load levels, depending on whether the device is in active or standby mode. These devices run in standby mode most of the time. The output spectrum of DC–DC buck converters in such an environment must also be spurious-free (i.e. of low tonal content) for them to be able to supply sensitive circuits, such as ICs in mobile communication systems. Among the various buck-converter architectures, switching converters offer the highest power conversion efficiency over a wide range of conversion ratios. Increasing the switching frequency of the buck converter enables the use of compact off-chip components and enhances the converter's integrability. However, operating at high switching frequencies increases switching losses and reduces the power conversion efficiency, especially at light loads. The ultimate goal in designing a switching buck converter is to resolve the conflict between operation at a high switching frequency and efficient power conversion, while maintaining a regulated output-voltage with low tonal content. This thesis proposes a spurious-free switching buck converter with enhanced light-load efficiency for use in noise-sensitive portable electronic devices. The proposed converter achieves low output noise by using a delta-sigma-modulator controller. Its light-load efficiency is enhanced by: 1) scaling the switching frequency of the buck converter (i.e. the sampling frequency of its delta-sigma-modulator controller) according to the load current; 2) switching its operation from continuous conduction mode (CCM) to discontinuous conduction mode (DCM) at light loads; and 3) using a new low-power current-sensing circuit. The delta-sigma modulator is designed with an input-feedforward architecture, which enables the switching frequency of its controller to be scaled without disturbing the stability of the feedback loop of the buck converter, and also reduces the controller quiescent current. The proposed switching buck converter was fabricated in a 0.13-µm digital CMOS process with a maximum switching frequency of 10 MHz, enabling the use of compact off-chip components. The results measured demonstrate that this buck converter achieves a spurious-free output with a noise floor below - 60 dBm and voltage ripples below 70 mV across its full loading range (2 mA to 800 mA). Furthermore, it achieves a power efficiency of greater than 70% over this entire range, with a peak efficiency of 95.12%.Les convertisseurs Buck DC–DC sont indispensables afin de maximi le temps de veille ainsi que la durée de vie de la batterie des appareils électroniques portatifs. Dans un environnement portatif, selon le mode actif ou de veille de l'appareil, les conditions de charge varient fortement de niveau lourd vers le niveau léger de charge. Ce type d'appareil fonctionne la plupart du temps en mode veille. Dans un tel environnement, le spectre sortant de convertisseurs Buck DC–DC doit être sans parasite (c'est-à-dire avoir un contenu tonal faible), pour permettre d'alimenter les circuits sensibles comme les circuits intégrés dans les systèmes de la communication mobile.Parmi les différentes architectures de convertisseur Buck, les convertisseurs de commutation ont la meilleure efficacité de transformation de puissance, sur une gamme plus étendue de taux de transformation. L'accroissement de la fréquence de la commutation du convertisseur Buck, permet l'utilisation de composants hors-puce compacts ainsi que l'amélioration de l'intégrabilité du convertisseur. Cependant, l'exploitation à une fréquence élevée de commutation, augmente les pertes de commutation et réduit également l'efficacité de la transformation de la puissance surtout à des charges légères. Le but final de la conception d'un convertisseur Buck de commutation est de résoudre le conflit entre le fonctionnement à une fréquence élevée de commutation et une transformation de la puissance efficace, tout en conservant une tension de sortie régulée avec un contenu tonal faible.Cette thèse propose un convertisseur Buck de commutation sans parasite avec une efficacité améliorée pour des charges légères en vue d'une utilisation dans les appareils électroniques portables sensibles au bruit. Le convertisseur proposé réalise un faible bruit sortant en utilisant un contrôleur modulateur delta-sigma. L'efficacité à charge légère est augmentée par: 1) le changement de la fréquence de la commutation du convertisseur Buck (i.e. la fréquence d'échantillonnage du contrôleur modulateur delta-sigma) selon le courant de charge; 2) le passage du mode de la conduction continue (MCC) au mode de la conduction discontinue (MCD) pour les charges légères; et 3) l'utilisation d'un nouveau circuit de détection de courant à faible puissance. Le modulateur delta-sigma est conçu avec une architecture d'entrée par anticipation (input-feedforward) qui permet le changement de la fréquence de commutation de contrôleur, sans perturber la stabilité de la boucle de rétroaction du convertisseur Buck et également la reduction du courant de mise en veille du contrôleur.Le convertisseur Buck de commutation proposé a été fabriqué dans un procédé de CMOS numérique de 0.13-µm avec une fréquence maximale de commutation de 10 MHz. Ce qui permet l'utilisation des composants hors-puce compacts. Les résultats mesurés montrent que ce convertisseur Buck atteint une sortie sans parasite avec un seuil de bruit inférieur à 60 dBm et une ondulation de tension au dessous de 70 mV à travers la gamme complète du charge (2 mA à 800mA). Par ailleurs, il atteint une efficacité de puissance de plus de 70% sur cette gamme, avec une efficacité de pointe de 95,12%.
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Smecher, Graeme. "Discrete-time crossing-point estimation for switching power converters." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115995.
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In a number of electrical engineering problems, so-called "crossing points" -- the instants at which two continuous-time signals cross each other -- are of interest. Often, particularly in applications using a Digital Signal Processor (DSP), only periodic samples along with a partial statistical characterization of the signals are available. In this situation, we are faced with the following problem: Given limited information about these signals, how can we efficiently and accurately estimate their crossing points?For example, an audio amplifier typically receives its input from a digital source decoded into regular samples (e.g. from MP3, DVD, or CD audio), or obtained from a continuous-time signal using an analog-to-digital converter (ADC). In a switching amplifier based on Pulse-Width Modulation (PWM) or Click Modulation (CM), a signal derived from the sampled audio is compared against a deterministic reference waveform; the crossing points of these signals control a switching power stage. Crossing-point estimates must be accurate in order to preserve audio quality. They must also be simple to calculate, in order to minimize processing requirements and delays.
We consider estimating the crossing points of a known function and a Gaussian random process, given uniformly-spaced, noisy samples of the random process for which the second-order statistics are assumed to be known. We derive the Maximum A-Posteriori (MAP) estimator, along with a Minimum Mean-Squared Error (MMSE) estimator which we show to be a computationally efficient approximation to the MAP estimator.
We also derive the Cramer-Rao bound (CRB) on estimator variance for the problem, which allows practical estimators to be evaluated against a best-case performance limit. We investigate several comparison estimators chosen from the literature. The structure of the MMSE estimator and comparison estimators is shown to be very similar, making the difference in computational expense between each technique largely dependent on the cost of evaluating various (generally non-linear) functions.
Simulations for both Pulse-Width and Click Modulation scenarios show the MMSE estimator performs very near to the Cramer-Rao bound and outperforms the alternative estimators selected from the literature.
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Nieminen, Leena. "Modelling metabolic switching in the differentiating bacterium Streptomyces coelicolor." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=19536.
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Streptomyces are filamentous bacteria that are commonly found in soil ecosystems. During their complex life cycle Streptomyces produce many useful bioactive secondary metabolites. During growth in liquid cultures, filamentous, multicellular growth of Streptomyces can result in inefficient industrial antibiotic fermentations. Streptomyces form large heterogeneous aggregates in liquid culture where the morphology and metabolism of hyphae are influenced by external oxygen and nutrient profiles within a pellet. Understanding the features and emergent properties of these could significantly aid improvement of industrial-scale processes. This thesis studies the heterogeneous nature of hyphal growth by constructing a discrete-continuum hybrid stochastic differential equation model of filamentous growth and pellet formation. The model requires relatively few values for parameterisation of which many can be derived from experiments. The model is experimentally validated and tested, through analysis of growth curve data, coupled with manual and automated image analysis. Using enhanced green fluorescent protein fusions it was possible to study the spatio-temporal localization of proteins in key cellular processes inside pellets and relate these to pellet behaviour. The model delivers realistic simulations of Streptomyces pellet formation and is able to predict features, such as the density of hyphae, the number of tips and the location of metabolic switch within a pellet in response to external nutrient supply, which are almost impossible to do in all but the smallest aggregates. Using the antibiotic-producing soil bacterium Streptomyces as a model we have developed a flexible mathematical model platform. The model is scalable and will find utility and application in a range of branched biological networks such as fungal hyphal networks, plant root growth and angiogenesis.
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Collins, Sean 1979. "Investigation of switching characteristics of nanomagnets via magnetic force microscopy." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82208.
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Magnetic quantum cellular automata (MQCA) have been proposed as an alternate computing architecture. Single domain magnetic particles represent "1" or "0"; their stray field interaction controls the propagation and manipulation of information. An inherent requirement for an MQCA system is to know the conditions under which nanomagnets switch between the purely "up" (1) and the purely "down" (0) state, and to control this reproducibly.As a first step to study this, arrays of two types of permalloy particles were designed, simulated, fabricated and imaged, and their switching distributions ascertained. Individual particles were "peanut"-shaped, to investigate the effect of a shape anisotropy for an elliptical particle. Particles had long axes of 750 nm and 250 nm, but had identical aspect ratios.
Particles were simulated with a public domain software package, Object Oriented Micromagnetic Framework (OOMMF), fabricated by electron beam lithography with standard lift-off techniques in the fabrication facility in Sherbrooke, Canada, and imaged in vacuum using a custom built magnetic force microscope in constant height mode with an in plane, in-situ magnetic field. Ensemble hysteresis loops were obtained as was the average switching fields for both arrays.
The 750 nm particles were found experimentally to have a two-step switching process. The first switch occurred at 60 +/- 16 Oe and the second at 130 +/- 56 Oe. These results were nominally better than those obtained in a previous study on similarly sized ellipses.
Simulations on the 250 nm particles predicted that particles of that size would have the single domain configuration as their virgin state, and would have a one-step switching process. The switching field of a typical particle was calculated to be 550 +/- 30 Oe. This was confirmed experimentally, where the switching field distribution had its peak at 490 +/- 40 Oe. Thus, theory and experiment are in agreement, within error.
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Marck, Michael J. "A study of switching behaviours in the B2B service sector." Thesis, University of Strathclyde, 2008. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23960.
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The marketing literature has argued the value of retaing customers and stated that loyal clients are more likely to focus on long-term benefits and engage in cooperative actions benefical to both partners (Lam et al., 2004). There is abundant quantitative research on B2C loyalty, but limited qualitative research for B2B loyalty within the services sector. This research has filled the gaps and contributes to the study of B2B switching by analysing the behaviours of the client, 'switched to', and 'switched from' service providers. The sample consisted of Canadian staffing agencies because this sector experiences frequent switching and is a critical component of the service economy with global sales of, $192.6 billion in 2006 (The Economist, 2007). This industry is undergoing tremendous changes that will affect the ways companies manage their recruiting and human resources needs. It was found the key switching factors are a loss of trust, inability to listen to clients' needs and f ailure to deliver a quality core service. The research also investigated the constructs necessary to form and sustain B2B relationships - trust, commitment, loyalty and risk. This study confirmed that trust is 'the blood line' of retaining relationships and any breaches of trust resulted in switching. Contrary to previous B2C switching studies (Keaveney, 1995) apathy, pricing and inconvenience were not significant switching factors while it was affirmed that there are noteworthy differences between B2C and B2B switching factors. The study contributes to marketing theory and practitioners by identifying key switching behaviours within the B2B service industry. It explores the constructs necessary to nurture B2B relationships while mitigating the chances of client switching. The staffing agency sector is particularly interesting for academic research, as it is currently being affected by significant growth which poses drastic challenges for business managers to sustain an ever-increasing competitive environment.
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Oshaben, Edward J. "DC-DC Power Converter Design for Application in Welding Power Source for the Retail Market." Cleveland State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=csu1296178360.
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Evequoz, Claude. "On the choice of packet size in computer communication networks." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66158.
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Shalmon, Michael S. "Queues and packet multiplexing networks." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=71999.
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This thesis has to do with certain fundamental queues that are well established as models for delay in simple packet-switching concentrators and networks. We first revisit the single server queue with Poisson arrivals and general independent service times. We then work out a complete delay analysis for a traffic concentrating tandem network of queues with deterministic service and batch Poisson sources connected to every node; this is the most comprehensive analysis available for a network which is not of Jackson type. We also show how to (partially) extend the analysis to a concentrating tree network, and to an arrival process somewhat more general that batch Poisson.The two parts of the thesis have a close methodological relationship. Our contribution in both cases is to rederive certain known results, and to produce a variety of new ones, using techniques that are essentially qualitative. Our particular view of the stochastic processes in question is guided by a very special queue discipline, namely Last Come First Served preemptive resume; by identifying certain structural features of the sample paths, one can read, almost without calculation, a host of statistics of common interest. The LCFS preemptive resume discipline also enables us: (i) to strengthen the connection between the single server queue with general independent service times and interarrival times, and the fluctuation theory of random walks; (ii) to strengthen the connection between the queue with Poisson arrivals and branching processes.
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Tremblay, Eric J. "Electro-optic beam scanning in domain inverted LiTaO₂ for fast optical switching." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80148.
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This thesis investigates the design, simulation, fabrication and testing of electro-optic beam scanners in domain inverted LiTaO3 . To build these devices, a process of fabrication was developed including the construction of an electro-optic poling station for ferroelectric domain inversion of LiTaO3. This fabrication process was used to construct electro-optic prism beam scanners, which were designed and simulated to provide voltage controlled deflection of a collimated laser beam at 1310nm. Two electro-optic scanners were tested yielding linear deflection up to 1.064° and 0.986° at 1500V; agreeing well with simulation. Both scanners were found to have insertion losses of 1.7 dB and 2.3 dB in the off and on states respectively, and crosstalk of -25 dB. Degradation of performance was measured as a function of polarization extinction ratio, polarization misalignment, and applied voltage. Both devices are found to exhibit performance well suited for the construction of 1 x 2 fiber optic switches.
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Intep, Somkid. "Stochastic differential equations with switching and numerical simulation for gene regulation networks." Thesis, University of Strathclyde, 2010. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=14354.
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Sun, Wai-choi Sunny. "A feasibility study of switching from the diesel to petrol light road transport to improve the urban air quality in Hong Kong /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B14723153.
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Shahi, Sandeep Kaur. "The synthesis and testing of fast switching, novel conjugated polymers for electrochromic applications." Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28503.
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Modern technology is an essential aspect of our everyday lifestyle being vitally important to lighting, mobile phones, laptops, toys etc. The majority of these gadgets concentrate on visual electronic displays as a key selling feature. Hence, industry is in constant competition to excel while delivering new consumer demands of higher colouration efficiency, faster response times, inexpensive yet robust hardware, flexible displays and with the possibility of incorporating electronics into textiles. Traditionally, inorganic small molecules were extensively used for optical displays devices such as cathode ray tubes, liquid crystal displays, light emitting diiodes [sic] and plasma screens. However, in the past decade, significant progress in polymer electrochromism has shown many organic electroactive polymers to have the potential to satisfy the above consumer demands. Electrochromic materials (EC) have the ability to undergo a reversible colour transformation switch upon electrochemical doping, such as colour bleaching transformations. Herein, this thesis discusses how organic chemistry facilitates the advantage of structurally modifying monomeric heterocyclics to fine tune materials with interesting optical and physical properties. The polymeric form of an teraryl monomer containing a 1,4-dithiin-furan illustrated superior switching performances and electrochromic properties when compared to its parent poly 3,4-ethylene dioxythiophene (PEDOT). Poly(dithienylfuran) films displayed fast switching and reversible colour transformation at high colour contrast (CE = 212 cm2 C-1 cf. 183 cm2 C_1 for PEDOT at 95% optical switch). Formerly overlooked furan materials in organic electronics was revisted here, in which a polyfuran substituted at the 2,3-positions with an S-alkylated dithiin unit, was studied. The employment of the dithiin moiety provides intrinsic additional electroactivity, as well as a functional handle for substitution with alkyl groups, enhancing the processability of the polymer. The new polymer is compared with the closely related and well-established literature compounds PEDOT and PEDTT as well-studied, highly chalcogenated polythiophenes. The electrochromism phenomenon is not only of importance for visual optical displays but also has the potential for extended application in telecommunications with electromagnetic responses into the near infra-red (NIR) region. Herein, describe a series of symmetric and asymmetric chalcogenated azomethine monomers, robustly exherting electrochemical activity within the NIR.
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Casadei, Erik. "Progetto di un convertitore full-bridge phase-shifted isolato a commutazione risonante." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10676/.
Full textAbstract:
L'evoluzione della tecnologia allo stato solido e il fiorire di nuove applicazioni determinano una forte spinta verso la miniaturizzazione dei convertitori elettronici di potenza.
Questa riduzione di pesi ed ingombri è particolarmente sentita anche in quei convertitori di media potenza che necessitano di un trasformatore d'isolamento. In quest'ambito assume importante rilievo l'utilizzo di una architettura circuitale a ponte intero e di tecniche in grado di spingere la frequenza di commutazione il più in alto possibile.
Questa tesi si propone quindi di studiare a fondo il funzionamento dei convertitori DC/DC isolati di tipo Full-Bridge e pilotati con la tecnica di modulazione Phase-Shifted che ben si presta all'impiego di commutazioni risonanti del tipo Zero-Voltage-Switching.
L'analisi teorica sarà corroborata da simulazioni condotte su LTspice e sarà orientata all'individuazione di una metodologia di progetto generale per questo tipo di convertitori.
Al fine di formalizzare meglio il progetto si è individuata una possibile applicazione nell'alimentazione di un DC-bus per telecomunicazioni (48 Volt DC sostenuti da batterie) a partire da una fonte di energia fotovoltaica quale una stringa di pannelli operanti con tensioni variabili da 120 a 180 Volt DC.
Per questo particolare tipo di applicazione in discesa può avere senso l'impiego di un rettificatore del tipo a duplicazione di corrente, che quindi si provvederà a studiare e ad implementare a secondario del trasformatore d'isolamento.
Infine particolare cura sarà dedicata alla parte di controllo che si ha intenzione di integrare all'interno di LTspice così da riuscire a simulare il comportamento dinamico del convertitore e verificare quanto predetto in via teorica mediante l'impiego della procedura che utilizza il K-Factor per la realizzazione della rete compensatrice.
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Nicoladis, Elena. "Code-mixing in young bilingual children." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28864.
Full textAbstract:
This thesis examined several possible explanations for young bilingual children's code-mixing: the unitary language system (ULS) hypothesis, parental rates of code-mixing, parental discourse strategies in response to children's code-mixing, and children's language dominance. These explanations were examined in six French-English bilingual children, observed between the ages of 18 and 30 months. They were observed separately in interaction with each of their parents. The results showed that the ULS hypothesis cannot explain children's language use. Similarly, parental input could not explain children's code-mixing. In contrast, children's dominance was shown to be the best explanation of their code-mixing. It was suggested that bilingual children are particularly likely to code-mix when they do not know a translation equivalent. These results suggest that bilingual children's code-mixing is largely due to performance factors rather than underlying competence.
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Tseng, Kuo-Wei, and 曾國瑋. "On the Conceptual Design of Fuel-Electric Hybrid Systems with Mechanical Switching Devices." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/65230494005609002577.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
98
At present the operations of the general hybrid power system requires a complex electronic control system and devices, in order to accomplish a variety of functions. This study is to develop a conceptual design for the control system of the hybrid power system, expecting to develop mechanical control system with simple mechanical components. Take advantage of this study of systematic design, made simple with the feasibility of a mechanical control device. This study first will develop functional power graph extend to functional power and control graph, which can clear the control connections between the control system and hybrid power system. Then establish control system logic table, which can simplify the control operations of each components, make the concept design of the control system systematically done easier. Then, for the fuel-electric hybrid system, approaching the conceptual design of mechanical control system with the mechanical control unit composed of simple mechanical and electronic components and the proper control system logic table. Finally, make the particular design and description of the fuel-electric hybrid system with mechanical switching devices with a scooter. And to validate the fuel-electric hybrid system with mechanical switching devices with the analysis of energy efficiency and emissions, which resulting by the numerical analysis software ADVISOR with the ECE-40 driving cycle.