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Predicting drag polars for micro air vehicles /Luke, Mark Elden, January 2003 (has links) (PDF)
Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2003. / Includes bibliographical references (p. 67-69).
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End-wall flow of a surface-mounted obstacle on a convex humpAhmed, Hamza Hafez. Ahmed, Anwar, January 2009 (has links)
Thesis--Auburn University, 2009. / Abstract. Includes bibliographic references (p.70-72).
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Power system impacts of plug-in hybrid electric vehiclesRoe, Curtis Aaron. January 2009 (has links)
Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Dr. A. P. Meliopoulos; Committee Member: Dr. David Taylor; Committee Member: Dr. Ronald Harley; Committee Member: Dr. Shijie Deng. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Environmental exposure assessment of metals from reclaimed land in Halmstad harbour : Sweden Part of an environmental risk assessmentAssarsson, Karin January 2015 (has links)
The harbour land fill in Halmstad has been described in the news as one of the most polluted areas in Halland County based on the a survey from the Swedish environmental protection agency. In order to identify the extent and severity of the situation several environmental investigations have been performed in this area. This report is based on available data from investigations and environmental reports from WSP, Höganäs AB, HEM and Halmstad municipality. This investigation focus on an “Area C” within the land fill where the main land fill material is i.a. slag from a steel work, construction waste, dredge spoil, waste from glass production and a casting shop. Of these material the focus have been on the metal rich slag from the steel work and its possible environmental impact. The environmental exposure of Hg, Pb, Cd, Cr, Zn, Ni, Mo and V have been calculated as an annual load from Area C. Unfortunately the data available for this investigation has not been complete, e.g. slag concentration data with corresponding leachate data was only obtained for one year. The groundwater data and land fill metal concentrations have been measured only once. This made it impossible to investigate e.g. annual variations like ageing effects of the material or weather variations, variation in the properties of the deposed slag material and statistical significance in differences could not be calculated. Further characterisation of the land fill would be worthwhile in order to be able to draw some conclusions. Calculations of the environmental load has been performed based on concentration in the slag, the land fill, the leachate data of the slag and groundwater concentrations. A model has been developed to calculate the weighted land fill metal concentration. The partitioning coefficient, Kd; between soil and liquid has been calculated and used to estimate the environmental load. It was assumed that the groundwater data was the most reliable data, which indicated that the exposure may be higher than from common soil, especially for Pb and Mo. Relating the environmental exposure values with guideline values based on MKM (less sensitive land use)-land using HQ (hazard quotient) indicates a decreasing risk in the order Pb>V>Mo. However, the exposure is well below that from MKM soil which could be assumed, according to Swedish environmental protection agency guideline values, to be an acceptable exposure.
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Smart technology enabled residential building energy use and peak load reduction and their effects on occupant thermal comfortCetin, Kristen Sara 03 September 2015 (has links)
Residential buildings in the United States are responsible for the consumption of 38% of electricity, and for much of the fluctuations in the power demands on the electric grid, particularly in hot climates. Residential buildings are also where occupants spend nearly 69% of their time. As “smart” technologies, including electric grid-connected devices and home energy management systems are increasingly available and installed in buildings, this research focuses on the use of these technologies combined with available energy use data in accomplishing three main objectives. The research aims to: (a) better understand how residential buildings currently use electricity, (b) evaluate the use of these smart technologies and data to reduce buildings’ electricity use and their contribution to peak loads, and (c) develop a methodology to assess the impacts of these operational changes on occupant thermal comfort. Specifically this study focuses on two of the most significant electricity consumers in residential buildings: large appliances, including refrigerators, clothes washers, clothes dryers and dishwashers, and heating, ventilation and air conditioning (HVAC) systems. First, to develop an improved understanding of current electricity use patterns of large appliances and residential HVAC systems, this research analyzes a large set of field-collected data. This dataset includes highly granular electricity consumption information for residential buildings located in a hot and humid climate. The results show that refrigerators have the most reliable and consistent use, while the three user-dependent appliances varied more greatly among houses and by time-of-day. In addition, the daily use patterns of appliances vary in shape depending on a number of factors, particularly whether or not the occupants work from home, which contrasts with common residential building energy modeling assumptions. For the all-air central HVAC systems studied, the average annual HVAC duty cycle was found to be approximately 20%, and varied significantly depending on the season, time of day, and type of residential building. Duty cycle was also correlated to monthly energy use. This information provides an improvement to previously assumed values in indoor air modeling studies. Overall, the work presented here enhances the knowledge of how the largest consumers of residential buildings, large appliances and HVAC, operate and use energy, and identifies influential factors that affect these use patterns. The methodologies developed can be applied to determine use patterns for other energy consuming devices and types of buildings, to further expand the body of knowledge in this area. Expanding on this knowledge of current energy use, smart large appliances and residential HVAC systems are investigated for use in reducing peak electric grid loads, and building energy use, respectively. This includes a combination of laboratory testing, field-collected data, and modeling. For appliance peak load reduction, refrigerators are found to have a good demand response potential, in part due to the nearly 100% of residential buildings that have one or more of these appliances, and the predictability of their energy consumption behavior. Dryers provide less consistent energy use across all homes, but have a higher individual peak power demand during afternoon and evening peak use times. These characteristics also make dryers also a good candidate for demand response. The study of continuous commissioning of HVAC systems using energy data found that both runtime and energy use are increased, and cooling capacity and efficiency are reduced due to the presence of faults or inefficiencies. The correction of these faults have an estimated 1.4% to 5.7% annual impact on a residential building’s electricity use in a cooling-dominated climate such as the one studied. Overall, appliance peak load reduction results are useful for utility companies and policy makers in identifying what smart appliance may provide the most peak energy reduction potential through demand response programs. The results of the HVAC study provides a methodology that can be used with energy use data, to determine if an HVAC system has the characteristics implying an inefficiency may be present, and to quantify the annual savings resulting from its correction. The final aspect of this research focuses on the development of a tool to enable an assessment the effect of operational changes of a building associated with energy and peak load reduction on occupant comfort. This is accomplished by developing a methodology that uses the response surface methodology (RSM), combined with building performance data as input, and uncertainly analysis. A second-order RSM model constructed using a full-factorial design was generally found to provide strong agreement to in and out-of-sample building simulation data when evaluating the Average Percent of People Dissatisfied (PPD[subscript avg]). This 5-step methodology was applied to assess occupant thermal comfort in a residential building due to a 1-hour demand response event and a time-of-use pricing rate schedule for a variety of residential building characteristics. This methodology provides a model that can quickly assess, over a continuous range of values for each of the studied design variables, the effect on occupant comfort. This may be useful for building designers and operators who wish to quickly assess the effect of a change in building operations on occupants. / text
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MILJÖCERTIFIERING MED MILJÖBYGGNAD : FÖRSLAG FÖR LÖSNING AV PROBLEMET MED UPPFYLLNAD AV KRAVEN PÅ DAGSLJUS OCH SOLVÄRMELAST / ENVIRONMENTAL CERTIFICATION WITH MILJÖBYGGNAD : PROPOSAL FOR SOLUTION OF THE PROBLEM WITH FULFILLMENT OF THE CLAIMS OF DAYLIGHT AND SOLAR HEAT LOADJohansson, Pontus, Alvarsson, Daniel January 2015 (has links)
Syfte: I dagens samhälle har det blivit mer intressant att bygga med en miljö-certifiering, detta leder till att byggentreprenörer ställs inför tekniska svårigheter vid både projektering och produktion för att kraven ska uppfyllas. I denna rapport kommer svårigheterna med solvärmelast och dagsljus behandlas då de kan vara ett problem. Målet med denna rapport är att ”Belysa hur kraven på dagsljus och solvärmelast enligt miljöcertifieringssystemet Miljöbyggnad kan lösas”. Metod: Kvalitativ data samlades in via intervjuer för att få svar på frågeställningarna. Intervjuerna genomfördes i huvudsak på plats hos respektive persons företag. En hög validitet uppnåddes genom att intervjufrågorna strukturerades och hade koppling till frågeställningar och mål. Reliabiliteten stärktes genom att intervjuerna spelades in och det gick att hitta samband mellan svaren. Resultat: Kravnivåerna i Miljöbyggnad är BBR:s krav i grunden för de flesta indikatorer vilket motsvarar BRONS-nivån i Miljöbyggnad. För indikatorn dagsljus skulle SILVER vara lite bättre än BRONS och för GULD krävs datorsimuleringar samt enkätundersökning eller egendeklaration. För Indikatorn solvärmelast finns inget grundkrav i BBR då det endast står att solvärmetillskottet ska begränsas. När kravnivåerna för solvärmelast togs fram användes persienner för att ta reda på rimliga nivåer. Det kan uppstå problem med att uppfylla kraven för solvärmelast och dagsljus om arkitekten inte har tillräcklig kunskap om Miljöbyggnad. Placering av byggnader och fönster är också problematiskt eftersom byggnader inte bör ligga för nära varandra för att tillräckligt med dagsljus ska komma in i byggnaden. Mycket fönster i söderriktning kan innebära mycket solinstrålning vilket kan ge problem med att klara solvärmelasten. De lösningar som denna rapport har fått fram är att det ska finnas en dialog mellan ansvariga i projekten för att hitta pareto-optimala lösningar. Det går att sänka kravet på en indikator och höja kravet på en annan för att sammanlagt få det byggnadsbetyg som önskas. Solvärmelastens krav kan lösas med hjälp av olika sorters solskydd. Det går även att ändra fönstrets typ, storlek eller antal. Konsekvenser: Den slutsats som går att dra efter att arbetet blivit färdigställt, är att fönster påverkar indikatorerna solvärmelast och dagsljus mest. För att båda de kraven ska bli uppfyllda och få ett högt betyg, är det lämpligt att använda solskydd för att minska solvärmelasten. En rekommendation är också att beställarens arkitekt detaljberäknar indikatorerna innan förfrågningsunderlaget går ut, då det oftast är i början av byggprocessen som de större problemen kan undvikas. Begränsningar: Arbetet begränsas till att behandla indikatorerna solvärmelast och dagsljus i miljöcertifieringssystemet Miljöbyggnad. Lösningar för kravnivåerna detaljstuderas inte. Undersökningsstrategin begränsas till att bara innehålla en kvalitativ metod. Nyckelord: Dagsljus, Fönster, Miljöbyggnad, Solvärmelast / Purpose: Society has become more interested in building with an environmental certification system, which leads to that building engineers are facing technical difficulties in both planning and production to meet the requirements. This thesis addresses the technical difficulties with solar heat load and daylight in the environmental certification system Miljöbyggnad. The purpose of this thesis is to “Illustrate how the demands of daylight and solar heat load in Miljöbyggnad can be solved”. Method: Qualitative data were collected through interviews to obtain answers concering the issues. The interviews essentially took place at each person’s company. High validity was achieved by the interview questions that were structured and linked to the issues and the purpose of this thesis. To increase the reliability, interviews were recorded and it was possible to find correlations between the answers. Findings: The BRONZE level in Miljöbyggnad is basically BBR:s requirements for most of the indicators. The SILVER level for the indicator daylight were supposed to be better than BRONZE and GOLD requires simulations and pleased residents. It is not possible to find requirements for solar heat load in BBR. When the requirements for this indicator in Miljöbyggnad was set, sun-blinds were used. There may be problems in meeting the requirements for solar heat load and daylight if the architects do not have the sufficient knowledge of Miljöbyggnad. The placement of buildings and windows are also problematic because the distance between the buildings can affect daylight problems. If there are a lot of windows in the south direction, the solar gain may cause difficulty to solve the requirements for solar heat load. The solutions this thesis submits are, to have a dialogue between the involving people in the projects to find pareto-optimal solutions. It is possible to reduce the require-ments for one indicator and raise the requirements for another to get the total building-rating as required. The requirements for solar heat load can be solved by using different kinds of shading devices. It is possible to change the type of windows, size of the windows and the amounts of windows. Implications: The conclusions are that the windows affect the indicators solar heat load and daylight very much. To solve the requirements and get a high rating on both indicators, it is appropriate to use any kind of shading devices. We also recommend that the architect calculates the indicators in detail before the tender document is ready, to avoid major problems. Limitations: To limit the extensive work it was necessary to focus on the indicators solar heat load and daylight in the environmental certification system Miljöbyggnad. The solutions for the indicators levels were not studied in details. The investigation method was limited to only use qualitative interviews. Keywords: Daylight, Miljöbyggnad, Solar heat load, Windows
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Market power, cost efficiency and pricing strategies of domestic airline industryWang, Ran 21 September 2015 (has links)
This dissertation first develops a theoretical framework to enable the estimation of cost efficiency and conduct parameter without total cost data. By validating this framework using U.S. airline data, this dissertation shows the feasibility of the theoretical framework. Based on the estimates of marginal cost efficiency and conduct parameter, this dissertation also finds some support for the Quiet Life Hypothesis. In Chapter III, this dissertation analyzes the determinants for price dispersion, especially conduct parameter and cost efficiency. Generally speaking, we find negative relationship between conduct parameter and price dispersion and negative relationship between marginal cost efficiency and price dispersion. In Chapter IV, this thesis examines the dynamics that lead to high price dispersion. To be more specific, this thesis concentrates on advanced days purchased and load factor.
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An evaluation of a finite element analysisAnderson, Clifford E. (Clifford Eric), 1946- January 1971 (has links)
No description available.
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Autonomous suspended load operations via trajectory optimization and variational integratorsDe La Torre, Gerardo 21 September 2015 (has links)
Advances in machine autonomy hold great promise in advancing technology, economic markets, and general societal well-being. For example, the progression of unmanned air systems (UAS) research has demonstrated the effectiveness and reliability of these autonomous systems in performing complex tasks. UAS have shown to not only outperformed human pilots in some tasks, but have also made novel applications not possible for human pilots practical. Nevertheless, human pilots are still favored when performing specific challenging tasks. For example, transportation of suspended (sometimes called slung or sling) loads requires highly skilled pilots and has only been performed by UAS in highly controlled environments.
The presented work begins to bridge this autonomy gap by proposing a trajectory optimization framework for operations involving autonomous rotorcraft with suspended loads. The framework generates optimized vehicle trajectories that are used by existing guidance, navigation, and control systems and estimates the state of the non-instrumented load using a downward facing camera. Data collected from several simulation studies and a flight test demonstrates the proposed framework is able to produce effective guidance during autonomous suspended load operations. In addition, variational integrators are extensively studied in this dissertation. The derivation of a stochastic variational integrator is presented. It is shown that the presented stochastic variational integrator significantly improves the performance of the stochastic differential dynamical programming and the extended Kalman filter algorithms. A variational integrator for the propagation of polynomial chaos expansion coefficients is also presented. As a result, the expectation and variance of the trajectory of an uncertain system can be accurately predicted.
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Performance Benchmarking of Fast Multipole MethodsAl-Harthi, Noha A. 06 1900 (has links)
The current trends in computer architecture are shifting towards smaller byte/flop ratios, while available parallelism is increasing at all levels of granularity – vector length, core count, and MPI process. Intel’s Xeon Phi coprocessor, NVIDIA’s Kepler GPU, and IBM’s BlueGene/Q all have a Byte/flop ratio close to 0.2, which makes it very difficult for most algorithms to extract a high percentage of the theoretical peak flop/s from these architectures. Popular algorithms in scientific computing such as FFT are continuously evolving to keep up with this trend in hardware. In the meantime it is also necessary to invest in novel algorithms that are more suitable for computer architectures of the future.
The fast multipole method (FMM) was originally developed as a fast algorithm for ap- proximating the N-body interactions that appear in astrophysics, molecular dynamics, and vortex based fluid dynamics simulations. The FMM possesses have a unique combination of being an efficient O(N) algorithm, while having an operational intensity that is higher than a matrix-matrix multiplication. In fact, the FMM can reduce the requirement of Byte/flop to around 0.01, which means that it will remain compute bound until 2020 even if the cur- rent trend in microprocessors continues. Despite these advantages, there have not been any benchmarks of FMM codes on modern architectures such as Xeon Phi, Kepler, and Blue- Gene/Q.
This study aims to provide a comprehensive benchmark of a state of the art FMM code “exaFMM” on the latest architectures, in hopes of providing a useful reference for deciding when the FMM will become useful as the computational engine in a given application code. It may also serve as a warning to certain problem size domains areas where the FMM will exhibit insignificant performance improvements. Such issues depend strongly on the asymptotic constants rather than the asymptotics themselves, and therefore are strongly implementation and hardware dependent. The primary objective of this study is to provide these constants on various computer architectures.
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