Dissertations / Theses on the topic 'Design efficiency'

This dissertation explores the use of the efficiency performance measurement paradigm (EM), in terms of its concepts and applications, as an ex-ante mechanism to evaluate enterprise performance and inform enterprise design. The design of an enterprise is driven by decisions that include, but not limit to, which strategies to implement, how to allocate resources, how to shift operating patterns, and how to boost coordination among enterprises, among others. Up to date, EM has been mainly used as a descriptive mechanism, but the fundamental reason for measuring performance in an ex-post fashion, i.e., how well an enterprise does, is also valid in the context of design decisions, i.e., ex-ante evaluation. The contrast between the ex-post and ex-ante use of EM relates to the measurement purpose, i.e., why to measure. Ex-post measurement focuses on evaluating 'what happened' (non-disruptive) while ex-ante measurement emphasizes in informing design decisions exploring changes in current settings (more disruptive). Within this context and to achieve the purpose above, this dissertation is supported by theoretical insights and complemented with three empirical studies. The theoretical insights relate to facts that support, connect to, and challenge (i.e., facilitate or impede) the ex-ante use of EM for enterprise evaluation and informing enterprise design. Those insights are based on the efficiency performance measurement, organizational design and enterprise systems engineering literature. Meanwhile, the three empirical studies situate the application of EM as an ex-ante mechanism to inform evacuation management, bank branch management, and power plants. The theoretical and empirical results indicate that EM is well suited for both evaluating enterprise performance and informing design decisions. The main contribution of this dissertation to enterprise stakeholders is that EM can be not only used to answer how well the enterprise did, but also how well it could do if certain design decisions are taken.
Ph. D.

Industrialised housing has increased its Swedish market share the latest ten years from 2% to 15%. Prefabrication has developed into actual industrialisation, where factories produce not only elements for site assembly, but takes wholesale responsibility for the sales, design, factory production, and assembly of houses. A higher automation in housing production puts demands on the design department to become more efficient. Design is identified as a bottleneck to further increase the production rate. Information deliveries are not produced in the needed rate. With the change from drafting to modelling in building design, opportunities are given to work simultaneously for better efficiency. The focus on BIM-supported CAD-tools has lead ICT-developers to create systems that mainly support product modelling. But, in industrialised housing, support for process efficiency is just as important.In a case study at a Swedish industrialised housing company, during a three year period, interviews, observations and design activities at the company were recorded to study what components and functionality in the design support create business value. The results show that by defining design in stages with gates, by parallel planning of activities, and by using process visualisation methods, the efficiency increased about 41 % in information deliveries. Furthermore, the use of support systems has to create both internal value for efficiency in information deliveries and external value to meet and handle client requirements in a standardised way. By releasing time from project management activities to improvements and product development the focus on the product could increase. Product development theories with axiomatic design as the foundation for a support system combines product structures with BIM functionality and process support for planning, which secures quality between disciplines in a concurrent approach. Product life cycle management (PLM) is an umbrella that manages product development in a life-cycle perspective trough a defined framework that is applicable to industrialised housing design, both for software developers and industrialised builders.
Industriellt byggande har de senaste tio åren ökat sina marknadsandelar från 2% till 15% på den svenska bostadsmarknaden för flerfamiljshus. Prefabricering har utvecklats till industrialisering, där fabriker inte bara producerar komponenter för montering på byggplats, utan tar även helhetsansvar för försäljning, konstruktion, i fabrik och för montering av bostäder. Utvecklingen av en mer automatiserad produktion ställer högre krav på projekteringen. Som en definierad flaskhals måste tid frigöras från koordinering till kärnverksamhet för att skapa förbättringar och tillåta produktutveckling. Med förändringen från ritningsbaserad till modellbaserad byggprojektering, ges möjligheten att arbeta samtidigt för bättre effektivitet. Fokuseringen på BIM-stöd med CAD-verktyg har lett till att utvecklare skapar system som i huvudsak stödjer produktmodellering. För industriellt bostadsbyggande, är stöd för effektivitet i projekteringsprocessen lika viktig. Empiri har samlats genom intervjuer, observationer och dokumenterade aktiviteter i en fallstudie hos en svensk industriell bostadsbyggare för att analysera vilka komponenter och funktioner som ett stödsystem för projektering behöver för att skapa värde för företagen. Resultaten visar att en definition av projektering i steg med gater, aktiviteter för samplanering och användandet av metoder för att visualisera processen har ökat effektiviteten med omkring 41 % för informationsleveranser. Dessutom visar studien att stödsystem bör kunna skapa både internt värde för effektiva informationsleveranser och yttre värde för att möta och hantera kunders krav på ett standardiserat sätt. Ett stödsystem, baserat på produktutvecklingsteorier med axiomatisk design som grund, kan kombinera både produktstruktur med BIM- funktioner och processrelaterade funktioner för planering och därmed säkra kvaliteten mellan discipliner för samverkande arbete. Product life cycle management (PLM) är ett övergripande koncept för hantering av produktutveckling i ett livscykelperspektiv, vilket har ett definierat regelverk som är applicerbart på industriell byggprojektering, både för utvecklare av IT-system och för industriella husbyggare.
Godkänd; 2010; 20100914 (gusjan); LICENTIATSEMINARIUM Ämnesområde: Träbyggnad/Timber Structures Examinator: Docent lektor Helena Johnsson, Luleå tekniska universitet Diskutant: Tekn. Lic. Jerker Lessing, Tyréns, Malmö Tid: Onsdag den 20 oktober 2010 kl 10.00 Plats: F1031, Luleå tekniska universitet

Generators are widely used across the world as portable power units in case of power outages, used for emergency services and are also used in rural areas without access to electricity. The majority of commercially available generators use internal combustion engines designed as automobile engines with little or no optimization for use in generators. With operating conditions vastly different than that of automobile engines, they can be re-designed to operate much more efficiently as generator engines. The development objective here was to design a low cost, 1.6L, lean burn, internal combustion engine which minimizes heat losses, time losses and frictional losses to improve thermal efficiency. Various high swirl, high squish, easily CNC’d combustion chambers were created in the re-design process. A computer model was used to provide insight into the trade-off between time losses and heat losses. A maximum brake thermal efficiency of 37.2% was achieved.

The objective of the proposed research is to develop structural changes to the design and application of electromagnetic (EM) sensing models to more efficiently and accurately invert EM measurements to extract parameters for applications such as landmine detection. Two different acquisition modalities are addressed in this research: ground-penetrating radar (GPR) and electromagnetic induction (EMI) sensors. The models needed for practical three-dimensional (3D) spatial imaging typically become impractically large, with up to seven dimensions of parameters that need to be extracted. These parameters include, but are not limited to target type, 3D location, and 3D orientation. The new special structures for these models exploit properties such as shift invariance and tensor representation, which can be combined with strategic inversion techniques, including the Fast Fourier Transform and semidefinite programming. The structures dramatically reduce the amount of computation and can eliminate the need to store up to five dimensions of parameters while still accurately estimating them.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 193-200).
Parabolic trough collectors are a low cost implementation of concentrated solar power technology that focuses incident sunlight onto a tube filled with a heat transfer fluid. The efficiency and cost of the parabolic trough collector designs is influenced by structural stiffness, choice of materials, assembly tolerances, mirror cleanliness and wear. Current performance estimates of solar trough optical field efficiencies are 54.2% [1]. The goal of this research is to identify general methods and specific design concepts for achieving increased collector efficiency. This thesis has investigated improvements in the design of a parabolic trough module by looking first at the overall structural concept of the collector to reduce complexity while maintaining structural stability under wind loading conditions. In the process of evaluating the feasibility of one such concept, a monolithic reflector panel with a mirror film front surface, details related to the mirror surface efficiency were investigated. At the panel-structure to mirror interface, surface roughness of the underlying structural backing was studied to understand performance effects on the mirror film surface that would make one backing material potentially more suitable than another would. In this case it was found that three materials tested: gel-coated fiberglass, rolled aluminum, and rolled steel were all similarly effective when compared to a more expensive mirrored aluminum backing material. When looking at the integration of the larger structural changes with the factors that affect surface reflectivity of parabolic mirrors, it became apparent that contamination of the surfaces and cleaning were major factors in reduced module effectiveness. Given that the conceptual development of the structure is ongoing, research into contamination factors and potential cleaning solutions were considered in such a way that panel cleaning solutions could be integrated into the trough module design from the start. A vortex generator cleaning concept, which uses V-shaped extruded forms to create vortices over a mirror panel in the presence of flow over the surface, was tested as a passive cleaning solution.
by Stacy L. Figueredo.
Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.
Includes bibliographical references (p. 101-103).
The proposed research is a study of designing high-efficiency Mid-IR quantum cascade lasers (QCL). This thesis explores "injector-less" designs for achieving lower voltage defects and improving wall plug efficiencies through highly strain-balanced structures and minimized injector regions. This work contains experimental design work for testing and evaluating Mid-IR QCL performance, simulation work for verifying wavefunction and energy alignment, as well as, Monte Carlo transport simulations for evaluating designs, and finally measuring lasing and spontaneous emission performance for various designs.
by Allen Long Hsu.
S.M.

This thesis investigated the design decisions and associated optimisation methods of a 1.3 GHz Multiple Beam Klystron (MBK) for use in the Compact Linear Collider (CLIC). In this regard refinements have been made both to the MBK design, and investigation and optimisation methods used. The high desired efficiency of 80% requires low perveance beams, to achieve the specification output power 20 beams are needed. The choice of cavity used in the interaction structure of a klystron has a large impact on its size and efficiency. To optimise this a number of possible cavity designs were produced and compared to confirm selection of the most appropriate. The fundamental mode (TM0, 1, 0) coaxial cavity was selected due to its superior R/Q of 130-210 W and suitability as a 2nd harmonic cavity. Although the dipole mode proved to be close in frequency to the operating mode (within ~ 50 MHz), raising concerns of stability issues in an MBK. A novel model was developed using standard wake field theory to investigate the effects of this mode the klystron’s stability. A strategy for shifting this mode using a coupled shifting gap was proposed and achieves a shift of 125 MHz, although the models findings suggest it is not a significant problem. Existing methods of calculating dipole and higher order modes proved time consuming thus impeded a fully investigation of stability issues. An extended method of moments model allows efficient calculation of monopole and higher order modes. The model’s basis functions are altered to represent a range of TM and TE modes with azimuthal variation, allowing their rapid and accurate calculation. Optimising the klystron interaction structure by hand to find a viable configuration revealed shortcomings in this standard approach, although the target efficiency was achieved. An algorithmic approach was deemed necessary to allow a full investigation within reasonable time limits. The field of evolutionary algorithms is presented and an evolutionary algorithm to automate the optimisation of klystron interaction structures was developed. A number of important related issues were dealt with and suitable interaction structures (optimised for efficiency, bandwidth, length and electron exit velocity) produced. Finally a design was proposed for both the input and output couplers which is inspired by a coupler used in a gyrotron. Unconventionally, the latter exits the tube axially avoiding the focusing solenoid, but excessive heating may preclude its use.

Eco-efficiency improvements in manufacturing is a controversial subject for researchers, practitioners as well as policy makers. The widely accepted definition of "doing more with less" is not accurate enough to guide the design of improvements that can deliver products in a sustainable way. The outcome of these challenges is evident through significant environmental performance variations across various levels of manufacturing operations. The study is driven by the complexity of manufacturing systems and sought to offer design support for practitioners that aim to improve eco-efficiency. A maturity model has been developed in this work that simulates the influence of manufacturing practices on eco-efficiency. The model takes the form of a maturity grid (PMGE) that overlooks practices at process, management systems and top-management levels and incorporates 15 dimensions of performance overall. Evidence shows that practices tend to evolve from reactive to proactive as manufacturing systems mature and embrace eco- efficiency as a systemic property. It was also found that mature companies achieve improvements in energy and resources by relying on existing internal capabilities. Tools to facilitate research and intervene with practitioners in real-life problems were developed and tested. The researcher combined research findings and tools into a maturity-based method (PMGEM) for eco-efficiency improvements. The method intends to help practitioners plan and design eco- efficiency improvements aligned to existing internal capabilities and adopt a more proactive behaviour to environmental challenges. PMGEM was ultimately applied in two case studies with ultimate goal to help practitioners resolve real-life challenges. The applications were positively commented and encourage further work in this field. The researcher envisages that methods such as PMGEM are deeply needed in manufacturing to support practitioners approach complex concepts such as eco-efficiency. Simplification and decomposition techniques with a clear intended use can facilitate the implementation of ambitious improvement strategies for sustainable development.

With the competitive challenge facing business today, the need to keep cost down and quality up is a matter of survival. One way in which wire manufacturers can meet this challenge is to possess a thorough understanding of deformation, friction and lubrication during the wire drawing process, and therefore to make good decisions regarding the selection and application of lubricants as well as the die design. Friction, lubrication and die design during wire drawing thus become the subject of this study. Although theoretical and experimental investigations have been being carried out ever since the establishment of wire drawing technology, many problems remain unsolved. It is therefore necessary to conduct further research on traditional and fundamental subjects such as the mechanics of deformation, friction, lubrication and die design in wire drawing. Drawing experiments were carried out on an existing bull-block under different cross-sectional area reductions, different speeds and different lubricants. The instrumentation to measure drawing load and drawing speed was set up and connected to the wire drawing machine, together with a data acquisition system. A die box connected to the existing die holder for using dry soap lubricant was designed and tested. The experimental results in terms of drawing stress vs percentage area reduction curves under different drawing conditions were analysed and compared. The effects on drawing stress of friction, lubrication, drawing speed and pressure die nozzle are discussed. In order to determine the flow stress of the material during deformation, tensile tests were performed on an Instron universal test machine, using the wires drawn under different area reductions. A polynomial function is used to correlate the flow stress of the material with the plastic strain, on which a general computer program has been written to find out the coefficients of the stress-strain function. The residual lubricant film on the steel wire after drawing was examined both radially and longitudinally using an SEM and optical microscope. The lubricant film on the drawn wire was clearly observed. Therefore, the micro-analysis by SEM provides a way of friction and lubrication assessment in wire drawing.

The widespread application of wireless services and the requirements of ubiquitous access have recently triggered rapidly booming energy consumption in wireless communications networks. Such escalation of energy consumption in wireless networks causes high operational expenditure from electricity bills for operators, unsatisfactory user experience due to limited battery capacity of wireless devices, and a large amount of greenhouse gas emission. Green radio (GR), which emphasizes both energy efficiency (EE) and spectral efficiency (SE), has been proposed as an effective solution and is becoming the mainstream for future wireless network design. Unfortunately, EE and SE do not always coincide and may even sometimes conflict. In this dissertation, we focus on energy-efficient transmission and resource allocation techniques for orthogonal frequency division multiple access (OFDMA) networks and the joint energy-efficient design of OFDMA and other promising wireless communications techniques, such as cognitive radio (CR) and two-way relay. Firstly, we investigate the principles of energy-efficient design for pure OFDMA networks. As the first step, we study the fundamental interrelationship between EE and SE in downlink OFDMA networks and analyze the impacts of channel gain and circuit power on the EE-SE relationship. We establish a general EE-SE optimization framework, where the overall EE, SE and per-user quality-of-service (QoS) are all considered. Under this framework, we find that EE is quasiconcave in SE and decreases with SE when SE is large enough. These findings are very helpful guidelines for designing energy- and spectral-efficient OFDMA. To facilitate the application of energy-efficient resource allocation, we then investigate the energy-efficient resource allocation in both downlink and uplink OFDMA networks. For the downlink transmission, the generalized EE is maximized while for the uplink case the minimum individual EE is maximized, both under prescribed per-user minimum data rate requirements. For both transmission scenarios, we first provide the optimal solution and then develop an computationally efficient suboptimal approach by exploring the inherent structure and property of the energy-efficient design. Then we study energy-efficient design in downlink OFDMA networks with effective capacity-based delay provisioning for delay-sensitive traffic. By integrating information theory with the concept of effective capacity, we formulate and solve an EE optimization problem with statistical delay provisioning. We also analyze the tradeoff between EE and delay, the relationship between spectral-efficient and energy-efficient designs, and the impact of system parameters, including circuit power and delay exponents, on the overall performance. Secondly, we consider joint energy-efficient design of OFDMA and CR and two-way relay, respectively, to further enhance the EE and SE of wireless networks. We study energy-efficient opportunistic spectrum access strategies for an OFDMA-based CR network with multiple secondary users (SUs). Both worst EE and average EE of the SUs are considered and optimized subject to constraints including maximum transmit power and maximum interference to primary user (PU) system. For both cases, we first find the optimal solution and then propose a low-complexity suboptimal alternative. The results show that the energy-efficient CR strategies significantly boost EE compared with the conventional spectral-efficient CR ones while the low-complexity suboptimal approaches can well balance the performance and complexity. Then we study energy-efficient resource allocation for OFDMA-based two-way relay, which aims at maximizing the aggregated EE utility while provisioning proportional fairness in EE among different terminal pairs. Different from most exist energy-efficient design, we consider a new circuit power model, where the dynamic circuit power is proportional to the number of active subcarrier. For low-complexity solution, we propose an EE-oriented sequential subchannel assignment policy and discover the sufficient condition for early termination of the sequential subchannel assignment without losing the EE optimality. It is found that the energy-efficient transmission does not necessarily make all the subcarriers active, which is another useful principle for practical energy-efficient system design.

As cited in literature, the history of hospital design in both practice and theory is rife with proposals that lay claim to improving efficiency. The aim was to obtain not only lowest possible construction, maintenance and operational costs, but also highest possible patient satisfaction,comfort and privacy. Nested within this outlook, the design of hospital nursing units has claimed considerable priority. Significant in such an endeavour is timely feedback to the designer, especially as quantitative assessments of what has been achieved so far with respect to planimetric efficiency
i.e. utility value of built floor area, both in terms of its allocation to served, serving and circulation spaces and the relative proportions of these. Its particular focus was on the nursing units of public facilities in Tü
rkiye. The study was carried out on a random sample of hospitals operating under government jurisdictions. Sample size was roughly determined as 33%. The material consisted of production drawings. Data derived from these comprised planimetric measurements regarding their nursing units and of various germane ratios calculated. Analysis of variance, distributional aspects, scatter charts and t-tests were used to evaluate this data according to a number of relevant factors. Results for ratio of primary spaces to secondary spaces showed that there were significant differences by constructional area per bed, while other variables showed a central tendency that was independent of the factors considered. It was concluded that while the method used was appropriate to the assessment in question, further developments and investigations were needed to determine the causes underlying such differences.

High efficiency air blowers to meet future portable aerosol sampling applications were designed, fabricated, and evaluated. A Centrifugal blower was designed to achieve a flow rate of 100 L/min (1.67 x 10^-3 m^3/s) and a pressure rise of WC " 4 (1000 PA). Commercial computational fluid dynamics (CFD) software, FLUENT 6.1.22, was used extensively throughout the entire design cycle. The machine, Reynolds number (Re) , was around 10^5 suggesting a turbulent flow field. Renormalization Group (RNG) κ−ε turbulent model was used for FLUENT simulations. An existing design was scaled down to meet the design needs. Characteristic curves showing static pressure rise as a function of flow rate through the impeller were generated using FLUENT and these were validated through experiments. Experimentally measured efficiency (ηEXP) for the base-design was around 10%. This was attributed to the low efficiency of the D.C. motor used. CFD simulations, using the κ−ε turbulent model and standard wall function approach, over-predicted the pressure rise values and the percentage error was large. Enhanced wall function under-predicted the pressure rise but gave better agreement (less than 6% error) with experimental results. CFD predicted a blower scaled 70% in planar direction (XZ) and 28% in axial direction (Y) and running at 19200 rpm (70xz_28y@19.2k) as the most appropriate choice. The pressure rise is 1021 Pa at the design flow rate of 100 L/min. FLUENT predicts an efficiency value based on static head (ηFLU) as 53.3%. Efficiency value based on measured static pressure rise value and the electrical energy input to the motor (ηEXP) is 27.4%. This is almost a 2X improvement over the value that one gets with the hand held vacuum system blower.

Sediment pollution from construction sites has been of increasing concern since the impacts on nearby streams can be severe. Controlling erosion is the most effective approach to reducing sediment loads, but construction sites typically have large areas of exposed soil during the active phase of clearing and grading. As a result, sediment traps and basins are required to capture eroded sediment on most of these sites. The purpose of this research was to determine the trapping efficiencies of sediment basins of various designs installed on active construction sites. Five traps and one basin were monitored in the Piedmont of North Carolina, all on highway construction sites except one trap on a private development. Automatic samplers were installed to measure flow and to obtain representative samples during storm events. The basins were surveyed after storms to determine the change in volume after repeated surveys. Trapping efficiency was calculated from the sediment accumulation within the traps or basin and the amount of sediment discharged, the sum of which was the total sediment entering the device. Particle size distribution in the sediment deposits was also determined. Two standard traps with rock outlets were found to have 37% and 46% trapping efficiencies after three storm events. A standard trap with silt fence baffles was found to have 45% and 36% efficiency rates during two time periods. Two additional traps, which had been sized for a 25-year storm event, instead of the standard 10-year event, had retention efficiencies of 96% and 99%. A sediment basin with porous baffles and a skimmer outlet had a retention efficiency of 99.8%. One standard trap had particle size distributions for sand, silt, and clay of 34%, 36%, and 30% while a standard trap with a permanent pool had particle size distributions of 55%, 25%, and 20%. The standard trap with silt fence baffles had a distribution of 36%, 50%, and 14%. The 25-year traps had distributions of 75%, 18%, and 7%; and 55%, 20%, and 25%, respectively. The skimmer basin had a distribution of 62%, 28%, and 10%. The higher proportion of sand in the more efficient devices suggests that the less efficient traps are releasing significant amount of sand-size sediment. Larger basins and surface outlets clearly provide greater sediment trapping on construction sites.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 71).
The MIT Rapid Development Group designed and built an internal combustion hybrid recharging system for the REMUS 600 Autonomous Underwater Vehicle (AUV) in collaboration with the MIT Lincoln Laboratory. This power system will recharge the lithium ion battery pack of the REMUS 600 and allow the vehicle to travel for 40 consecutive 12-hour missions without returning to recharge. This study analyzes the optimization of time and fuel efficiency in systems of this type. First, the battery charging scheme for optimal time efficiency was investigated through theoretical simulation of the REMUS battery recharging, based on typical curves for lithium ion battery charging. Secondly, the optimal control system for optimizing fuel efficiency was found by examining behavior in several different engines and predicting behavior in MIT RDG hybrid system's engine. A system was developed to control the throttle of the engine while sensing the voltage coming out of a synchronous rectification bridge. This scheme keeps the throttle above 50% unless the power requirement of the charger drops suddenly. Finally, the control scheme was implemented in software, along with controls for engine starting and shutdown.
by Laura M. Ware.
S.B.

ABSTRACT Photobioreactor Design for Improved Energy Efficiency of Microalgae Production Alexander Burns The objective of this research was to investigate a new photobioreactor (PBR) design for microalgae production that retains the typical advantages of existing tubular PBRs while reducing power consumption by providing simultaneous culture circulation and gas exchange with airlift alone and no centrifugal recirculating pump. Traditional tubular PBR designs feature a compressed air supply and a centrifugal pump for culture circulation and gas exchange. Circulation and gas exchange in a closed-system PBR is necessary to keep the algae suspended and to provide sufficient mass transfer (mainly for the exchange of oxygen and carbon dioxide). In a traditional tubular PBR sparged air keeps the culture well mixed and strips out excess dissolved oxygen in an airlift-column unit, while the centrifugal pump circulates the culture in the tubular stage and decreases the amount of air bubbles traveling into this stage; where most of the photosynthesis occurs. The PBR design proposed herein does away with the usual centrifugal pump. The air blower performs both gas exchange in the airlift columns and system-wide circulation. This builds on a previous tubular PBR design that provides circulation and gas exchange by airlift alone, which was patented by Cathcart in 2011. However, the Cathcart patent does not provide data on mixing, gas exchange, energy consumption, flow regime or biomass productivity. The new design described here builds on the Cathcart design, but includes several unique design features, such as larger diffuser columns which provide airlift-induced flow for a series of vertical PBR tubes. To perform a power consumption v analysis, a pilot-scale prototype of the new PBR design was built and operated. The prototype PBR consisted of two airlift columns attached to 9 m of vertical serpentine tubing connected to the top and bottom by standard 90-degree PVC elbows in a U-bend fashion to each column to make a total working volume of 235 L. The airlift columns were about 1.5 m tall and 30.5 cm ID, while the serpentine tubes were about 0.9 m tall and 7.6 cm ID to make a total of five vertical tubes for every airlift column. Data collected for this prototype design suggest an average overall areal productivity (OAP) of 111 g m-2 d-1 (g biomass m-2 total land area with empty space day-1), an average illuminated surface productivity (ISP) of 14.3 g m-2 d-1 (g biomass m-2 reactor photo-stage day-1), an average volumetric productivity (VP) of 0.55 g L-1 d-1 (g biomass L-1 reactor working volume day-1), a specific power input in the range of 330 to 360 W m-3 (W power needed for culture circulation and gas exchange m-3 reactor working volume) and a specific biomass productivity (SBP) in the range of 17.6 to 19.1 mg kJ-1 (mg biomass kJ-1 energy needed for culture circulation and gas exchange) with Chlorella vulgaris as the model algae. The biomass productivity per energy input (SBP) of the new PBR design appears to be higher than that of similar designs currently described in the literature. Elimination of the centrifugal pump in a tubular PBR design is a concept worth further study for potential energy savings.

To design a cyclone abatement system for particulate control, it is necessary to accurately estimate cyclone performance. In this cyclone study, new theoretical methods for computing travel distance, numbers of turns and cyclone pressure drop have been developed. The flow pattern and cyclone dimensions determine the travel distance in a cyclone. The number of turns was calculated based on this travel distance. The new theoretical analysis of cyclone pressure drop was tested against measured data at different inlet velocities and gave excellent agreement. The results show that cyclone pressure drop varies with the inlet velocity, but not with cyclone diameter. Particle motion in the cyclone outer vortex was analyzed to establish a force balance differential equation. Barth??s "static particle" theory, particle (with diameter of d50) collection probability is 50% when the forces acting on it are balanced, combined with the force balance equation was applied in the theoretical analyses for the models of cyclone cut-point and collection probability distribution in the cyclone outer vortex. Cyclone cut-points for different dusts were traced from measured cyclone overall collection efficiencies and the theoretical model for calculating cyclone overall efficiency. The cut-point correction models (K) for 1D3D and 2D2D cyclones were developed through regression fit from traced and theoretical cut-points. The regression results indicate that cut-points are more sensitive to mass median diameter (MMD) than to geometric standard deviation (GSD) of PSD. The theoretical overall efficiency model developed in this research can be used for cyclone total efficiency calculation with the corrected d50 and PSD. 1D3D and 2D2D cyclones were tested at Amarillo, Texas (an altitude of 1128 m / 3700 ft), to evaluate the effect of air density on cyclone performance. Two sets of inlet design velocities determined by the different air densities were used for the tests. Experimental results indicate that optimal cyclone design velocities, which are 16 m/s (3200 ft/min) for 1D3D cyclones and 15 m/s (3000 ft/min) for 2D2D cyclones, should be determined based on standard air density. It is important to consider the air density effect on cyclone performance in the design of cyclone abatement systems.

The goal of this design process was to achieve the most efficient propulsive system for the candidate autonomous underwater vehicle (AUV) as possible. A mathematical approach, using fundamental motor equations and derived quantities, was used to characterize and select an efficient brushless electric motor for the propulsion system. A program developed at MIT, Massachusetts Institute of Technology, called OpenProp versions 1 and 2.3 was utilized to design a custom propeller that maximizes the efficiency of the system. A brushless electric motor was selected for the candidate AUV based on a survey of available off the shelf motors and a mathematical characterization process. In parallel with the motor characterization a propeller design was optimized using OpenProp v1 to perform a parametric analysis. OpenProp v2.3 was then used to design a unique propeller for the selected motor. The propeller design resulted in a final propeller with an efficiency of 79.93%. The motor characterization process resulted in two candidate motors being selected, the NeuMotor 1925-3Y and NeuMotor 1521-10.5Y, for in house testing and evaluation. A total propulsive system efficiency of between 44% and 46% was achieved depending on which motor is selected for the final design.
Master of Science

Dissertação de Mestrado em Design, com a especialização em Design de Moda, apresentada na Faculdade de Arquitetura da Universidade de Lisboa para obtenção do grau de Mestre.
O foco desta pesquisa de design de moda são os métodos de ensino e a aprendizagem de "patternmaking". O propósito é estudar e observar alguns métodos correntes de ensino e retirar conclusões em termos de eficácia através dos resultados obtidos pelos alunos. A combinação de abordagens com intervenção ou sem intervenção de pesquisa qualitativa aqui proposta utilizará ferramentas como: (1) pesquisa literária (2) observação de aulas de "pattern making" de primeiro nível (para descrever e classificar os métodos de ensino usados pelos docentes de acordo com os resultados do desempenho dos alunos) e (3) entrevistas a estudantes e docentes (para identificar os seus antecedentes e experiências bem como as variáveis que contribuem para eficiência e deficiências identificadas nos processos de ensino). As entrevistas e observação conduzida vão permitir adquirir informação em tempo real, e como tal são de grande importância para este estudo. Igualmente relevante será a seleção e análise de literatura e documentação, que será um recurso permanente de informação. Esta pesquisa é um estudo documentado de três casos (um em Lisboa, Portugal e dois em Mumbai, na India) sobre métodos utilizados para o ensino e aprendizagem de pattern making, e retira as suas conclusões avaliando a sua eficiência.
ABSTRACT: The focus of this research in Fashion Design is the methods of teaching and learning pattern making. The purpose is to study and observe a few current methods and draw conclusions on their efficiency from the results obtained by the students. Combining non interventionist and interventionist approaches the qualitative research hereby proposed uses tools like (1) literature review, (2) observation of first level patternmaking classes (so as to describe and classify the methods used by the educators according to the students’ learning proficiency), and (3) interviews to students and educators (to identify their backgrounds and experiences as well as the variables that contribute for the efficiency or deficiencies of the observed methods). The conducted interviews and observation provide first hand information and are therefore of great importance in this study. Also relevant is the selection and review of literature, as it was a permanent source of information. This research is a documented study of three cases (one in Lisbon, Portugal and two in Mumbai, India.) on the methods that are being used for teaching and learning pattern making and concludes by evaluating their efficiency.
N/A

Product development requires that engineers have the ability to predict product performance. When product performance involves complex physics and natural phenomena, mathematical models are often insufficient to provide accurate predictions. Engineering companies compensate for this deficiency by testing prototypes to obtain empirical data that can be used in place of predictive models. The purpose of this work is to provide techniques and methods for efficient use of empirical methods in product development processes. Empirical methods involve the design and creation of prototype hardware and the testing of that hardware in controlled environments. Empirical methods represent a complete product development sub-cycle within the overall product development process. Empirical product development cycles can be expensive in both time and resources. Global economic pressures have caused companies to focus on improving the productivity of their product development cycles. A variety of techniques for improving the productivity of product development processes have been developed. These methods focus on structuring process steps and product artifacts for reuse and efficiency. However these methods have, to this point, largely ignored the product development sub-cycle of empirical design. The same techniques used on the overall product development processes can and should be applied to the empirical product development sub-cycle. This thesis focuses on applying methods of efficient and reusable product development processes on the empirical development sub-cycle. It also identifies how to efficiently link the empirical product development sub-cycle into the overall product development process. Specifically, empirical product development sub-cycles can be characterized by their purposes into three specific types: first, obtaining data for predictive model coefficients, boundary conditions and driving functions; second, validating an existing predictive model; and third, to provide the basis for predictions using interpolation and extrapolation of the empirical data when a predictive model does not exist. These three types of sub-cycles are structured as reusable processes in a standard form that can be used generally in product development. The roles of these three types of sub-cycles in the overall product development process are also established and the linkages defined. Finally, the techniques and methods provided for improving the efficiency of empirical methods in product development processes are demonstrated in a form that shows their benefits.

Power amplifiers (PAs) are one of the most crucial elements in wireless standards becasue they are the most power hungry subsystems. These elements have to face an important issue, which is the power efficiency, a fact related with the output back-off (OBO). But the OBO depends on the kind of modulated signal, in proportion to the modulated signal peak-to-average power ratio (PAPR). The higuer is the data rate, the higer is the OBO, and consequently the lower is the efficiency. A low efficiency of PAs causes the waste of energy as heat. Furthermore, the trade-off between linearity and efficiency in PAs is another major issue. To cope with the undesired circumstances producing efficiency degradation, the Doherty power amplifier (DPA) is one of the useful techniques which provide high efficiency for high PAPR of modern communication signals. Nevertheless, the limited bandwidth (BW) of this kind of PAs (about 10% of fractional bandwidth) and its importance (in modern wireless systems such as LTE, WiMAX, Wi-Fi and satellite systems) have encouraged the researchers to improve this drawback in recent years. Some typical BW limiting factors effect on the performance of DPAs: i) quarter-wave length transformers, ii) phase compensation networks in/output matching circuits, iii) offset lines and device non-idealities; The quarter-wave length transformers performs as an inverter impedance in the load modulation technique of DPAs. The future objective in designing DPAs is to decrease the impact of these issues. In this context, this PhD-thesis is focused on improving fractional bandwidth of DPAs using the new methods that are related to impedance transformers instead of impedance inverters in the load modulation technique. This study is twofold. First, it is presented a novel DPA where a wideband GaN DPA in the 2.5 GHz band with an asymmetrical Wilkinson splitter. The impedance transformer of the proposed architecture is based on a matching network including a tapered line with multi-section transformer in the main stage. The BW of this DPA has ranged from 1.8 to 2.7 GHz. Plus, the obtained power efficiency (drain) is higher than 33% in the whole BW at both maximum and OBO power levels. Second, based on the benefits of the Klopfenstein taper, a promising DPA design is proposed where a Klopfenstein taper replaces the tapered line. In fact, this substitution results on reducing the reflection coefficient of the transformer. From a practical prototype realization of this novel Doherty-like PA in the 2.25 GHz band, this modification has demonstrated that the resulting DPA BW is increased in comparison to the conventional topology while keeping the efficiency figures. Moreover, this study also shows that the Klopfenstein taper based design allows an easy tuning of the group delay through the output reactance of the taper, resulting in a more straightforward adjustments than other recently published designs where the quarter-wave transformer is replaced by multi-section transmission lines (hybrid or similar). Experimental results have shown 43-54% of drain efficiency at 42 dBm output power, in the range of 1.7 to 2.75 GHz. Concretely, the results presented in this novel Doherty-like PA implies an specific load modulation technique that uses the mixed Klopfenstein tapered line together with a multi-section transformer in order to obtain high bandwidth with the usual efficiency in DPAs.
Los amplificadores de potencia (PAs) son uno de los elementos más importantes para los transmisores inalámbricos desde el punto de vista del consumo energético. Un aspecto muy importante es su eficiencia energética, un concepto relacionado con el back-off de salida (OBO), que a su vez viene condicionadpo por el PAPR de la señal modulada a amplificar. Una baja eficiencia de los PA hace que la pérdida de energía se manifieste en forma de calor. De hecho, esta cuestión conduce al incremento de los costes y tamaño, esto último por los radiadores. Además, el compromiso entre la linealidad y la eficiencia en los PA es otro problema importante. Para hacer frente a las circunstancias que producen la degradación de la eficiencia, el amplificador de potencia tipo Doherty (DPA) es una de las técnicas más útiles que proporcionan una buena eficiencia incluso para los altos PAPR comunes en señales de comunicación modernos. Sin embargo, el limitado ancho de banda (BW) de este tipo de PA (alrededor del 10% del ancho de banda fraccional) y su importancia (en los sistemas inalámbricos modernos, tales como LTE, WiMAX, Wi-Fi y sistemas de satélites) han animado a los investigadores para mejorar este inconveniente en los últimos años. Algunos aspectos típicos que limitan el BW en los DPA son: i) transformadores de longitud de cuarto de onda, ii) redes de compensación de fase y circuitos de adaptación de salida, iii) compensación de las líneas y los dispositivos no ideales. Los transformadores de cuarto de onda actuan como un inversor de impedancia en la técnica de modulación de carga de la DPA "("load modulation"). Concretamente, el objetivo futuro de diseño de DPA es disminuir el impacto de estos problemas. En este contexto, esta tesis doctoral se centra en mejorar el ancho de banda fraccional de DPA utilizando los nuevos métodos que están relacionados con el uso de transformadores de impedancias en vez de inversores en el subcircuito de modulación de carga. Este estudio tiene dos niveles. En primer lugar, se presenta una novedosa estructura del DPA de banda ancha usándose dispositivos de GaN en la banda de 2,5 GHz con un divisor Wilkinson asimétrico. El transformador de impedancias de la arquitectura propuesta se basa en una red de adaptación, incluyendo una línea cónica con múltiples secciones del transformador en la etapa principal. El BW de este DPA ha sido de 1,8 a 2,7 GHz. Además, se obtiene una eficiencia de drenador de más del 33% en todo el BW, tanto a nivel de potencia máxima como a nivel del OBO. En segundo lugar, aprovechando los beneficios de un adaptador de Klopfenstein, se propone un nuevo diseño del DPA. Con la sustitución de la lina conica por el Klopfenstein se reduce el coeficiente de reflexión de transformador de impedancias. Sobre un prototipo práctico de esta nueva estructura del Doherty, en la banda de 2,25 GHz, se ha demostrado que el BW resultante se incrementa en comparación con la topología convencional mientras se mantienen las cifras de eficiencia. Por otra parte, en este estudio se demuestra que el diseño basado en el Klopfenstein permite una afinación fácil del retardo de grupo a través de la reactancia de salida del taper, lo que resulta en un ajuste más sencillo que otros diseños publicados recientemente en el que el transformador de cuarto de onda se sustituye por multi-líneas de transmisión de la sección (híbridos o similar). Los resultados experimentales han mostrado un 43-54% de eficiencia de drenador sobre 42 dBm de potencia de salida, en el intervalo de 1,7 a 2,75 GHz. Concretamente, los resultados presentados en esta nueva estructura tipo-Doherty implican una técnica de modulación de carga que utiliza una combinación de un Klopfenstein junto con un transformador de múltiples secciones con el fin de obtener un alto ancho de banda con la eficiencia habitual en DPAs.
Els amplificadors de potència (PA) són un dels elements més importants per els sistemes ràdio ja que sone ls principals consumidors d'energía. Un aspecte molt important és l'eficiència de l'amplificador, aspecte relacionat amb el back-off de sortida (OBO) que a la seva vegada ve condicionat pel PAPR del senyal modulat. Una baixa eficiència dels PA fa que la pèrdua d'energia en manifesti en forma de calor. De fet, aquesta qüestió porta a l'increment dels costos i grandària, degut als dissipadors de calor. A més, el compromís entre la linealitat i l'eficiència en els PA es un altre problema important. Per fer front a les circumstàncies que porten a la degradació de l'eficiència, l'amplificador de potència Doherty (DPA) és una de les tècniques més útils i que proporcionen una bona eficiència per als alts PAPR comuns en senyals de comunicació moderns. No obstant això, l'ample de banda limitat (BW) d'aquest tipus de PA (al voltant del 10% de l'ample de banda fraccional) i la seva importància (en els sistemes moderns, com ara LTE, WiMAX, Wi-Fi i sistemes de satèl·lits) han animat els investigadors per millorar aquest inconvenient en els últims anys. Alguns aspectes tipicament limitadors del BW en els DPA son: i) transformadors de longitud d'quart d'ona, ii) xarxes de compensació de fase en circuits / adaptacions de sortida, iii) compensació de les línies i els dispositius no ideals. Els transformadors de quart d'ona s'utilitzen com a inversors d'impedàncies en la tècnica de modulació de càrrega del DPA ("load modulation"). Concretament, l'objectiu futur de disseny d'DPA és disminuir l'impacte d'aquests problemes. En aquest context, aquesta tesi doctoral es centra en millorar l'ample de banda fraccional dels DPA utilitzant nous mètodes que estan relacionats amb l'ús de transformadors d'impedàncies, en comptes d'inversors, en el subcircuit de modulació de càrrega. Aquest treball té dos nivells. En primer lloc, es presenta un DPA novedós que fa servir dispositus GaN DPA a la banda de 2,5 GHz amb un divisor Wilkinson asimètric. El transformador d'impedàncies de l'arquitectura proposada es basa en una xarxa d'adaptació, incloent una línia cònica amb múltiples seccions del transformador en l'etapa principal. El BW d'aquest DPA ha mostrat ser d'1,8 a a 2,7 GHz. A més, s'obté una eficiència de drenador de més del 33% en tot el BW, tant a nivell de potència màxima com de OBO. En segon lloc, sobre la base dels beneficis del adaptador de Klopfenstein, un proposa un nou disseny on un Klopfenstein substitueix la anterior línia cònica. Aquesta substitució repercuteix en la reducció del coeficient de reflexió de transformador d'impedàncies.Des d'una realització pràctica (prototipus) d'aquest nou amplificador tipus Doherty a la banda de 2,25 GHz, s'ha demostrat que el BW resultant s'incrementa en comparació amb la topologia convencional mentre es mantenen les xifres d'eficiència. D'altra banda, en aquest estudi es demostra que el disseny basat en el Klopfenstein permet una afinació fàcil del retard de grup a través de la reactància de sortida de la forma cònica, el que resulta en un ajust més senzill que altres dissenys publicats recentment en què el transformador de quart d'ona es substitueix per multi-línies de transmissió de la secció (híbrids o similar). Els resultats experimentals han mostrat un 43-54% d'eficiència de drenador en 42 dBm de potència de sortida, en l'interval de 1,7-2,75 GHz. Concretament, els resultats presentats en aquest nou amplificador tipus Doherty impliquen una tècnica de modulació de càrrega específic que utilitza una combinació del Klopfenstein juntament amb un transformador de múltiples seccions per tal d'obtenir un alt ample de banda amb la usual eficiència en DPAs.

This study set up the hypothesis that branches are shaped so as to maximise total photosynthetically active radiation interception per unit of assimilate expended in branch structural material. Measurements of branch geometry, combined with computer modelling were used to develop a deeper understanding of form-function relations. The thesis seeks to discover whether light interception (as a measure of benefit) per unit invested material (as a cost) is maximised in natural branches by the optimisation of allocation of structural material among the shoots of branches. Thus a cost-benefit analysis paradigm is applied to the problem of structural carbon allocation among shoots. Topology of branches has been regarded as an invariant property of branch age, so providing an appropriate constraint. A topological classification scheme was devised for branch elements (links and shoots) so that form-function relations could be resolved. Geometric attributes of 125 individual branches from trees of Picea sitchensis Bong. (Carr.) were analysed to find evidence for form-function relationships. Multivariate differences in geometric design among genotypes were not considered sufficient to motivate form optimisation through a breeding program. Within branch shoot length distribution was related to position in the topology which may be a reflection of light interception potential. Diameters of branch elements were proportional to lengths, but proportionality constants varied with topological position. An allocation model based on mechanical design of shoots was more successful in explaining shoot allometry than one based on the pipe model. The mechanical load safety factor varied among branch elements according to their expected potential for light interception. Hydraulic (pine model) design of branches reinforced the pattern of distribution in mechanical safety factors. This provides possible support for the theory of shoot autonomy. It is concluded that tree branches are likely a result of competing optimisation goals acting within genetic and ontogenic constraints and that shoot size may be related to the potential for competition for light interception, with shoots that show greater potential taking a disproportionate share of resources within the branch.

With the rapid growth of housing development in China, energy inefficiency in domestic architectures is becoming a crucial problem for the nation's sustainable development. At present, the average energy consumption of housings in North China cities is three times that in developed countries. The energy conservation regulation introduced by the government requires 65% heating energy saving in dwellings compared with the 1980's standard. However most of the current buildings cannot meet that regulation the problem is mainly due to the lack of detailed technology and construction requirements, and difficulties in relation to enforcement. The main aim of this research is to investigate the potential of using environmental design strategies to increase the energy efficiency of residential architectures in North China cities while provide reasonable comfort conditions. Literature review, on-site observations, field experiments and computer simulation were used. The field experiments were conducted in five flats in Tianjin and Xi'an cities to assess their thermal performance. Thermal simulations by using the building energy model HTB2 were employed to analysis these designs, and what improvements can be reasonably achieved, in line with China's targets for reducing housing energy demand by adapting certain environmental design strategies. The findings of this work showed that with the adaptation of environmental design strategies, significant improvements of energy efficiency of residential buildings in North China cities can be achieved and considerable portion of energy can be saved. The most effective parameter in heating reduction is improve thermal insulation, having 50mm and 100mm polystyrene insulation achieved reductions of 26.5% and 38.8‰ respectively. Reduce the infiltration rate is the second most effective method, limit the air change rate to 0.5 ach reduced 21.6% of the heating demand from the existing condition. The parameters that reduce most cooling demand are having a reasonable window area and night time controlled ventilation the reduction rate is around 23% and 13% respectively. Moreover, combining appropriate design parameters will maximise their effectiveness in energy reduction. Having parameters including appropriate glazing ratio, improve insulation of the building envelope, reduce infiltration etc. will enable case studies to match the 65% saving regulations straightforward and the cooling load was also substantially reduced. Moreover, by following further modification suggestions, the energy reduction rate reached 90%. Considerable reduction in energy use and carbon emission can be achieved in North China cities and other places experiencing similar climates, by adapting the suggested design strategies. The findings of this research could help the decision-makers and architects to improve thermal performance and energy efficiency of both existing housings and future designs.

Thesis (Honors paper)--Florida State University, 2009.
Advisor: Dr. Christopher Reenock, Florida State University, College of Social Sciences, Dept. of Political Science. Includes bibliographical references.

碩士
亞洲大學
光電與通訊學系碩士班
100
This paper proposed a bootstrapped type high-efficient charge pump circuit based on the Dickson charge pump in order to get a high output power and pump-efficiency. By using bootstrapped technique, it can increase both of pump-efficiency and power-efficiency. The proposed bootstrapped based charge pump can avoid the threshold voltage drop in conventional Dickson charge pump circuits and enable them to generate a higher output voltage. Simulation by using HSpice level 3 model shows that for conventional Dickson charge pump, it convert the input low DC-voltage (Vin=1.5V) up to 3.8 times of it (VOUT=5.77V), the pump efficiency was 76.93%. Our work, however, can convert the low input DC-voltage (Vin=1.5V) up near to 4.8 times of it (VOUT=7.07V), the pump efficiency can reaches up to 94.2%. The newly proposed bootstrapped based Dickson charge pump circuit is suitable for various low to high voltage applications for power saving.

碩士
國立臺灣海洋大學
輪機工程系
101
In order to restrict the carbon emission of the cargo vessel in the world, the International Maritime Organization (IMO) has already listed Ship Energy Efficiency Management Plan (SEEMP) as the mandatory implementation of the project. To execute this project effectively, the result of related parameters includes density of air、difference temperature between inlet/outlet of the turbine、turbocharger RPM、difference pressure between inlet/outlet of the air cooler、Engine room temperature、compression pressure、difference pressure between compression pressure / high maximum pressure、Main Engine torque、Main Engine operation point which can display the crucial energy of the mainframe individually. We have to definitely know the current situation about the energy efficiency of the ship, so that we can work out the plan which can manage the energy efficiency of it. In this study, the researcher used National instrument LabVIEW to plan Ship Energy Efficiency Management system graphically. In the program, it can automatically derive from the current observation records, which are displayed with related parameters. With the data, we look forward to managing the energy efficiency of the ship effectively.

碩士
國立臺灣大學
電信工程學研究所
95
In this thesis, we propose a general mathematic model under infinite traffic load for various multiple access protocols and aim at the designing of optimization of energy efficiency. We generally model the ALOHA, Non-persistent and 1-persistent CSMA, and GRAP protocols using embedded Markov chain to obtain the performances of throughput, delay and energy efficiency. However, the infinite traffic loads implicit express the independence of backoff time and aggregate arrival rate. We loosen this independence of backlogged users and propose the prototype of unified MAC protocol which shows the correlation of protocol and backoff mechanism. In intuition, increase average backoff time increases the delay as well. In the mean while, it decrease the aggregate arrival rate which result in less retransmission times. This tradeoff leads us to consider the optimal energy efficiency by adjusting backoff time. Thus, we propose optimal tree protocol based on the unified tree protocol by adjusting dynamic backoff time. We also figure out that energy efficiency and delay are based on the general form which we called weighted time. They are only different in parameters setting. Nevertheless, according to unlike assumptions of system constrain, the optimization criterion is also distinct. We show the optimal energy efficiency under general constrain by numerical result.

碩士
義守大學
電子工程學系
92
This study shall change the technique that conventional antennas are used on cars. Using the method that is used in the making of micro-strip antennas to make small spiral antennas, the usage of conventional whip antenna is changed, achieving the purpose of area minimizing. This study is focused on making car-use mobile communications antennas with frequency between 0.170 and 0.172 GHZ (VHF), Making spiral antennas with the method used to make micro-strip antennas to change the form of conventional car-use antennas. Making antennas for different shapes, and actually place them on commercial communications division for cars, to discuss their frequency, radiation rate and their antenna Gain. The spiral antenna is the focused of this research. The making of the antenna begins after simulation has been done. The antenna will be placed on the school’s network analyzer to make preliminary measurements. It is then installed onto a car-use mobile antenna device, following by observation on the loss of frequency from the receiving point of the antenna to the connecting devices, and the location of the car at which the antenna is installed, and the comparison on the analytic differences between the pre-installed whip antenna and the spiral antenna.

碩士
國立臺灣科技大學
電機工程系
105
This thesis aims to design single-phase power factor correction function of the boost converter and resonant DC converter. The resonant converter allows the power transistors to operate at zero-voltage switching to reduce switching loss and increase the operating frequency of the converter. The latter will reduce the sizes of the resonant inductor, transformer as well as resonant capacitor, and thereby improve the efficiency. In addition, parameters for the magnetic component transformer and the external resonant inductor are designed to reduce core and copper losses. Meanwhile, synchronous rectifier instead of diode rectifier is used to reduce the forward bias voltage loss of the diode in the secondary side of the transformer, resulting in the improvement of the overall converter efficiency. In order to design the resonant capacitance and inductance, as well as the magnetization inductance and the turn-ratio of the transformer, the normalized frequency response graph of voltage gain is drawn to check the operation of the converter. Besides, LLC controller is introduced for minimum frequency limitation to avoid converter instability. The proposed resonant converter and control circuit are built for the output of 500W rated power, 24V DC with input voltage range of 90V to 264V. The switching frequency of the power factor corrector is 65kHz, while the switching frequency of the resonant DC power converter is from 75kHz to 350kHz. Experimental results show that the power factor and overall efficiency of the single-phase power supply are above 0.98 and 89.5%, respectively. In short, the feasibility of the proposed converter is verified experimentally.

碩士
國立中正大學
雲端計算與物聯網數位學習碩士在職專班
107
In recent years, the industrial structure has gradually changed through economic development. Enterprises have continuously changed their industries towards diversified development. In the face of the ever-changing market demand, they hope to flexibly use the adjustment structure in human resources, and employ flexible labor to adopt atypical work patterns. It is expected to reduce long-term fixed costs and recruit candidates. In the three-way relationship between businesses, dispatch agencies and dispatched employment, dispatch agencies as communication bridges for information transfer will help send businesses and dispatch employees to find suitable labor contracts. How to reduce the time spent by the two parties in finalizing the interview, and clearly know that the notices at each stage save time and quickly find suitable candidates during the interview. This study introduces the MVC Framework to propose an application development framework to solve the above problems, and then proposes to build and apply the EInterview platform, use Java with the Spring MVC Framework, and use JSF as a program application interface to assist in development, data content, graphics and services. The logic cutting reaches the code structure loose and difficult to manage and can be reused to improve the program performance. The whole development process from system design to system implementation provides a service for each company to send a mutual appointment interview time to reduce the time. The overall interview process is waiting for notice, hoping to effectively improve the time for finding suitable service contracts for both parties.

碩士
國立中正大學
電機工程所
93
This thesis proposes a high step-up and a high step-down soft switching converters. With conventional PWM hard switching converters, there exist many drawbacks, such as high component stress, high loss at switching transition and serious EMI problems, which will limit their operation frequency and performance. According to reference, a family of soft-switching cells (SSCs) have been introduced. When SSCs combined with the conventional PWM converters, both main and auxiliary switches can achieve claming action and soft-switching features. In this thesis, synthesis process is reviewed. Based on the synthesis process, several families of new converter topologies can be generated. By introducing SSCs to the coupled-inductor converters, the soft-switching features can be achieved and the energy trapped in the leakage inductor can be also recovered. With the coupled inductors, active switches in the converter can sustain proper duty cycles while operated in high step-up or high step-down ratio, and component stress can be reduced significantly. Based on operation principles, detailed analysis and design procedure of the converters with SSCs are presented. Measured results have verified the feasibility of the discussed soft-switching converters.

碩士
國立清華大學
資訊工程學系
94
To design an energy efficiency real-time system, it relates to chose appropriate applications running concurrently under the energy budget constraint from different application families. An application family is a set of software having common assets and sharing architectural properties. For low power design, each member in the same family is designed to deliver different quality with different energy consumption. Many software implementation strategies are available to provide different quality level. For example, programmers can configure the parameters of the compiler to generate a set of codes for the same application. That is, for the same application, we can generate a version of codes with high performance instructions, and another one with low performance instructions but consume less energy to meet specific energy budget. They are all regarded as members of the same application family. To satisfy the energy and timing constraint of the real-time system, we should chose a appropriate application from each application family. Since to choose the optimal combination of tasks from application families under timing and energy constraints is NP-hard, we propose a pseudo-polynomial time algorithm to find an optimal solution for the frame base task set and a heuristic algorithm for the general cases. Furthermore, if we consider the energy consumption of devices when applying real-time Dynamic Power Management (RT-DPM) policy, it becomes a more difficult problem. So, we propose another energy estimation equation to help the designers to estimate the energy consumption of a task when applying RT-DPM. After combing the heuristic algorithm and the energy estimation equation , the time complexity to find the solution of the problem when applying RT-DPM can be reduced significantly. Based on this algorithm, we developed a tool to provide constructive instructions in tuning system parameters for meeting a specific energy budget. We use an intelligent home case study to demonstrate its role in the low power design cycle. The experiment results shows that the tool can significantly reduce the design cycle of a low-power real-time embedded system.

碩士
亞東技術學院
資訊與通訊工程研究所
99
The past decade has seen a phenomenal growth in wireless communications. Wireless technology is permeating business and personal communications are across the globe, and the demand is driving the availability and performance to the new levels. WiFi(Wireless Fidelity) is the most common communication standard. In this research, which design coaxial sleeve dipole antenna array and the sleeve dipole antenna array by print circuit board for IEEE 802.11a/b/g, which operate frequencies are 2.45 GHz and 5.8 GHz. and the sleeve dipole antenna array by print circuit board can combine reflector to increase directivity. The sleeve dipole antenna array by print circuit board is linear antenna array , when antenna elements more and more, the taper efficiency is very important, so this thesis, will optimize of taper efficiency to get best directivity. The simulations are done by using GEMS, a parallelized FDTD (Finite-Difference Time-Domain) code In this thesis, the planar inverted F antenna is designed for HSDPA. High-Speed Downlink Packet Access (HSDPA) is an enhanced 3G (third generation) mobile telephony communications protocol in the High-Speed Packet Access (HSPA) family, also called 3.5 G, which the operate frequencies are 850 MHz, 1900 MHz and 2100 MHz, however, the space is very important in communication system, so the planar inverted-F antenna will be designed to achieve multi-band and small size requirements.

While concentrator photovoltaic cells have shown significant improvements in efficiency in the past ten years, once these cells are integrated into concentrating optics, connected to a power conditioning system and deployed in the field, the overall module efficiency drops to only 34 to 36%. This efficiency is impressive compared to conventional flat plate modules, but it is far short of the theoretical limits for solar energy conversion. Designing a system capable of achieving ultra high efficiency of 50% or greater cannot be achieved by refinement and iteration of current design approaches.

This thesis takes a systems approach to designing a photovoltaic system capable of 50% efficient performance using conventional diode-based solar cells. The effort began with an exploration of the limiting efficiency of spectrum splitting ensembles with 2 to 20 sub cells in different electrical configurations. Incorporating realistic non-ideal performance with the computationally simple detailed balance approach resulted in practical limits that are useful to identify specific cell performance requirements. This effort quantified the relative benefit of additional cells and concentration for system efficiency, which will help in designing practical optical systems.

Efforts to improve the quality of the solar cells themselves focused on the development of tunable lattice constant epitaxial templates. Initially intended to enable lattice matched multijunction solar cells, these templates would enable increased flexibility in band gap selection for spectrum splitting ensembles and enhanced radiative quality relative to metamorphic growth. The III-V material family is commonly used for multijunction solar cells both for its high radiative quality and for the ease of integrating multiple band gaps into one monolithic growth. The band gap flexibility is limited by the lattice constant of available growth templates. The virtual substrate consists of a thin III-V film with the desired lattice constant. The film is grown strained on an available wafer substrate, but the thickness is below the dislocation nucleation threshold. By removing the film from the growth substrate, allowing the strain to relax elastically, and bonding it to a supportive handle, a template with the desired lattice constant is formed. Experimental efforts towards this structure and initial proof of concept are presented.

Cells with high radiative quality present the opportunity to recover a large amount of their radiative losses if they are incorporated in an ensemble that couples emission from one cell to another. This effect is well known, but has been explored previously in the context of sub cells that independently operate at their maximum power point. This analysis explicitly accounts for the system interaction and identifies ways to enhance overall performance by operating some cells in an ensemble at voltages that reduce the power converted in the individual cell. Series connected multijunctions, which by their nature facilitate strong optical coupling between sub-cells, are reoptimized with substantial performance benefit.

Photovoltaic efficiency is usually measured relative to a standard incident spectrum to allow comparison between systems. Deployed in the field systems may differ in energy production due to sensitivity to changes in the spectrum. The series connection constraint in particular causes system efficiency to decrease as the incident spectrum deviates from the standard spectral composition. This thesis performs a case study comparing performance of systems over a year at a particular location to identify the energy production penalty caused by series connection relative to independent electrical connection.

碩士
朝陽科技大學
精密機械暨水下機電技術整合產業碩士專班
104
Abstract In today's gas water heaters have become general household essential goods. Gas water heater as the name implies, is a combustible gas and air are mixed in the way, after entering the burner gas mixing in the combustion chamber for combustion heaters, heat conversion achieved. In the case of today's emphasis on economic, security and environmental protection, in order to achieve better performance, lower cost, safety and reduce pollution, the development trend of today. This study will focus on a particular core heating gas water heater, burner and combustion chamber design incomplete combustion caused by poor design improvement process will be assisted by scientific simulation software to explore and improve gas water heater caused by bad design incomplete combustion problems. Keywords: Gas water heaters, Gas mixed with air, Fluid mechanics

碩士
國立臺灣大學
電機工程學研究所
96
The LLC resonant converter has the merit of fixed duty cycle operation. A combination of parasitic components, which includes the MOSFET output capacitance and the leakage inductance of the isolation transformer, produces a resonant action and reduces drain-source voltage prior to turn-on. Moreover, the switching loss is reduced relatively.Therefore, high efficiency operation of system is achieved.An experimental prototype of 115~264Vac input, 19V/4.73A output, the resonant converter full load efficient reaches 95.31%. The subject of this thesis is to analyze and design a LLC resonant converter. The LLC resonant converter allows zero voltage turn-on of switches while retaining the merits of simple circuit designed and low stresses accompanied with variable frequency control. The LLC resonant converter uses parasitic components to resonate. Therefore, additional resonant components are not required. Moreover, the switching stresses are reduced by using of the zero voltage switching (ZVS) resonant technique.

碩士
國立中央大學
電機工程研究所
91
With the current expansion of the wireless communication industry,system integration has become a major trend to meet hallenges.Microwave circuits are used within RF section of wireless communication system.The power amplifier is controlled by the size,cost,and performance of the RF section,hence the power amplifier plays an important role in the wireless communication system. This thesis is major to design high efficiency and linearization MMIC (monolithic microwave integrated circuit)power amplifier.In the high efficiency MMIC power amplifier,the paper demonstrated the 1.8GHz class E power amplifier.In addition,it is shown to use active elements (InGaP/GaAs HBT)’s base-collect junction and combine a parallel capacitance to form active bias.Active bias replace resistance bias without power consumption.This design is 5.2GHz two stage power amplifier to improve the nonlinear factor of power amplifier─gain compression.Then using network analyzer (HP-8510C) and Maury ATN load-pull system to measure all microwave power amplifiers.The measurements include S parameter, power gain,output power,PAE,IM3,and ACPR and analyze the results further. The measured result of 1.8 GHz power amplifier is as followed:(1) small signal S11 = -11.4 dB，S21 = 24.2 dB，S22 = -5.52 dB.(2) power gain= 24.2 dB,maximum output power=15.5 dBm,maximum PAE=39.4%,OIP3=22 dBm,ACPR=-30 dBc The measured result of 5.2 GHz active bias power amplifier is compared to the resistance bias class A power amplifier.The result is improvement of gain compression of 2 dBm input and improvement of OIP3 of 0.8 dBm.

碩士
聖約翰科技大學
電子工程系碩士班
97
For the fast growing of electric products, the consumer electronic products are designed toward the direction of tiny and portable. Audio amplifiers are mass needed in these products. The major demands of the consumer products, for example, are: power dissipation, product volume, and heat radiation. The most important design parameter of these is power efficiency. Increasing the power efficiency, it not only lasts the Class-D amplifier battery lives, but also operates in an extra low operating temperature. This paper designs Class-D amplifies based on self-tuning master-slave architecture and sliding mode control architecture. They are implemented with TSMC 0.35um 2P4M CMOS process. By using double triangle-wave generators and double feedback circuits in self-tuning mater-slave architecture, the efficiency of Class-D amplifier is increased and the total harmonic distortion (THD) is decreased. The chip size is 1.575mm x 1.575mm. The measure results show that when the input voltage is 0.6V, the power dissipation is 204mW, and the power efficiency is 89%. Second, the sliding mode control Class-D amplifier is using the sliding mode control modulation and bridge-configured architecture. The chip size is 1.575mm x 1.575mm. The simulation results show that when the input voltage is 0.6V, the power dissipation is 2.13W, and the power efficiency is 90.2%.

Started as a base for the calculation sheet, but this report eventually lead to a comparison between two engines of two axle drive and another two with three axle drive. However this was only to prove the results and calculation reliability. In this comparison and set of results major and principal characteristics from the engines are seen. In addition, a set of upgradable characteristics are considered and even highlighted i the beginning of the report in the Theoretical Considerations. In spite of all the limitations of no-dimensional method, it was possible to have a set of promising results, even considering the basic set of calculation in it mix.

Thermal energy storage (TES) is an advanced technology for storing thermal energy that can mitigate environmental impacts and facilitate more efficient and clean energy systems. Thermochemical TES is an emerging method with the potential for high energy density storage. Where space is limited, therefore, thermochemical TES has the highest potential to achieve the required compact TES. Principles of thermochemical TES are presented and thermochemical TES is critically assessed and compared with other TES types. The integration of TES systems with heating, ventilating and air conditioning (HVAC) applications is examined and reviewed accounting for various factors, and recent advances are discussed. Thermodynamics assessments are presented for general closed and open thermochemical TES systems. Exergy and energy analyses are applied to assess and compare the efficiencies of the overall thermochemical TES cycle and its charging, storing and discharging processes. Examples using experimental data are presented to illustrate the analyses. Some important factors related to design concepts of thermochemical TES systems are considered and preliminary design conditions for them are investigated. Parametric studies are carried out for the thermochemical storage systems to investigate the effects of selected parameters on the efficiency and behavior of thermochemical storage systems.
UOIT

碩士
大葉大學
工業工程與科技管理學系碩士在職專班
97
Sustainable energy is one of the important energy policies for every country in the 21th century. As the nucleon is an energy adopted by few countries to generate electric power, the fossil fuel is the main energy utilized by most of countries or even uses both energies to provide electric power. However, the fossil fuel usages not only have resulted in widespread environmental contaminations but also should concern its limited storage. That is, the price is getting higher due to decreased storage. Thus, instead of exploring new energy, how to promote the power conversion efficiency of renewable energy is becoming a critical issue. Especially, in order to achieve the highest power conversion efficiency, the better the power conversion system, the better the energy conversion. Consequently, this study attempts to explore the utilization of ZVT-BOOST in the solar system. The most important feature is that this ZVT-BOOST can decrease the power loss by use of the switch control. This design not only can increase the power efficiency and helps the solar energy produces the highest efficiency. Accordingly, the ultimate goal of energy efficiency and carbon reduction is achieved.