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Bias of the maximum likelihood estimator of the generalized Rayleigh distributionLing, Xiao 29 August 2011 (has links)
We derive analytic expressions for the biases, to O(n^(-1)) of the maximum likelihood estimators of the parameters of the generalized Rayleigh distribution family. Using these expressions to bias-correct the estimators is found to be extremely effective in terms of bias reduction, and generally results in a small reduction in relative mean squared error. In general, the analytic bias-corrected estimators are also found to be superior to the alternative of bias-correction via the bootstrap. / Graduate
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A Generalization of the Rayleigh DistributionLemon, Ruth H. 01 May 1961 (has links)
This papers is divided into numbered sections. The equations are numbered anew in each section, and equation numbers are always enclosed in parentheses. Merely the equation number is given when referring to an equation in the same section as the references; otherwise the section number is prefixed. Thus equation (4) refers to the fourth equation of the same section as the reference, and equation (2.2) refers to the second equation of the second section.
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Feasibility Study of Small Scale Standalone Wind Turbine for Urban Area : Case study: KTH Main CampusGebrelibanos, Kalekirstos Gebremariam January 2013 (has links)
The recent worldwide economic crisis, climate change and global warming have emphasized that the need for low carbon emissions while also ensuring the economic feasibility. In this paper, wind power potential of ETD in KTH was investigated. The technical and economical feasibility of tower mounted small scale standalone wind turbine installation is conducted. The potential of wind power production was statistically analysed. The average wind speed data of four-season interval of one year period (2011) which its measurement was taken on the roof top of the ETDB, and this was adopted and analysed in order to find out the potential of wind power generation. The Rayleigh distribution probability was applied to calculate the wind speed distribution at KTH, by doing so the annual wind power potential at the area and annual energy production of the chosen wind turbine was estimated, after the selection of a proper wind turbine have been made upon the site conditions. Therefore, the study result shows that installation of the wind turbine at 24 meters hub height for this particular area will have a better performance of annual energy production, capacity factor, carbon savings and better economical value than the current turbine installed at 17 meters height at the ETD. The economic evaluation shows that the turbine can save an electricity bill of US$3661.05 per year and cover 1.84% of the electricity consumption of the ETD by reducing its respective CO2 emission from the electricity use at the department. Moreover, the payback period of the turbine installation with the inclusion of the green certificate is approximately 14 years which is more feasible if it is considered for small wind turbines too, which is already in practice for renewables including wind power in Sweden.
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Analysis of RISE's VIRC for Automotive EMC Immunity TestingLundberg, Andreas January 2021 (has links)
RCs (Reverberation Chambers) has historically been used mainly for aerospace and military purposes in EMC (Electromagnetic Compatibility) testing, but the interest also seems to increase in the automotive industry (the development of an international standard for vehicles is in progress). The vehicles of the future will most likely be electrified, wirelessly connected and autonomous, i.e., more control units, more communication systems, and more sensors, will be implemented in the vehicles requiring increased robustness against all possible electromagnetic interferences. EMC testing in an RC is a step in the direction of ensuring this robustness for the future vehicle platforms. Compared to a traditional EMC test method in a fully or semi-AC (Anechoic Chamber), testing in an RC has the advantage that the electromagnetic field will be isotropic, randomly polarized and homogeneous in a statistical sense, i.e., the exposed object will be surrounded by electromagnetic energy from all directions. It can be considered relatively expensive to build a brand new RC with motorized stirrers and associated measurement instrumentation, instead it would be desirable to perform immunity tests in a more cost-effective conductive fabric tent. The great advantage is the flexibility, the tent can be set up almost anywhere, even in already existing semi-ACs, such set-up is referred to as VIRC (Vibrating Intrinsic Reverberation Chamber). This thesis aims to develop a new test method in a VIRC environment. In order to achieve good RC conditions, the electromagnetic field must be statistically Rayleigh distributed. Furthermore, it is of great importance to avoid LoS (Line of Sight) between the antenna and the test object, and to achieve good stirring in the tent. Provided this can be achieved, there are still some challenges by testing in a tent. For example, the classical dwell time of two seconds for immunity testing in EMC is not possible to achieve in a VIRC environment. The validation in this thesis shows that the dwell time or the total exposure time in the tent might be enough to trigger possible malfunctions in today's modern high-speed communication vehicles. Furthermore, it is showed, testing in a VIRC gives good field uniformity and repeatability, and can trigger malfunctions that are not triggered in traditional EMC testing in semi-AC, i.e., ALSE (Absorber-Lined Shielded Enclosure) testing.
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Development of a Novel Method for Automotive On-board Transmitter EMC Immunity Testing / Utveckling av en Immunitetsmetod för Elektromagnetisk Kompatibilitetstestning vid Simulering av Strålningskälla i FordonHolm, Ludvig January 2023 (has links)
As the automotive industry advances through technology integration, components are designed to operate at increasingly higher frequencies. Consequently, there will be an increasing demand for automotive electromagnetic compatibility (EMC) testing. Testing and certification institutes, such as RISE Research Institutes of Sweden AB, thus face an urgent need to develop innovative solutions that can effectively address this growing demand. This master thesis work concerns one EMC test method in particular - the On-board Transmitter (OBT). This is a test which mainly serves to test the immunity of vehicles to electromagnetic disturbances originating from hand-held devices. The conventional test is performed in an anechoic chamber and the methodology requires a substantial amount of time. The intent with this work is thus to evaluate the potential of a novel OBT method where the concept of a reverberating chamber is applied inside the vehicle compartment. Initially, the conventional method was examined from two mock-ups of idealized cases, and it was observed that the electromagnetic field in the near-field region of the transmitter is highly erratic. It was also concluded that the test setup is particularly sensitive to the polarization of the transmitter. With these findings in mind, the accuracy of the conventional method was deemed questionable. Evaluation of the proposed Reverberating On-board Transmitter (ROBT) method proved that the electromagnetic environment inside the vehicle did not resemble a perfect reverberation chamber. Which was expected as the absorbing material such as seating and upholstery likely prevents a field distribution similar to that in a reverberation chamber. Still, the intent of the project was to find a test method superior to the conventional method and it can be stated that the ROBT method is an adequate option due to its capacity to expose the electronics to isotropic radiation. This was found from two measures which this thesis introduces: expected isotropicity eiso, a relative measure of the electric field components and DDoF, a quantification of the spatial distribution inside a reverberation chamber. / EMC VERifiering av Autonoma fordon i modväxlad kammare (EMCVERA)
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