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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Ferramenta de simulação computacional de canal de propagação em ambiente celular baseado em modelos geométricos estatísticos. / Communication channel simulation tool based on geometrical and statistical model of macro cell environments.

Castilho, Sergio Duque 29 September 2006 (has links)
Este trabalho apresenta uma ferramenta de simulação computacional de canal de propagação para ambiente macro-celular baseada em modelos geométricos e no modelo estatístico apresentado no relatório COST 259 DCM. Para a implementação desta ferramenta é realizada, inicialmente, uma abordagem dos principais modelos de predição de perda por propagação, utilizados atualmente, assim como, um estudo dos modelos geométricos que fornecem as informações de distribuição de potência temporal e angular para diferentes tipos de distribuições estatísticas de espalhadores. A modelagem geométrica utiliza grupos independentes no qual os espalhadores são distribuídos com uma densidade Gaussiana. A utilização desta distribuição Gaussiana leva a distribuições de atraso e ângulo de chegada mais próximas dos resultados de medições do que o usando distribuição uniforme. A base geométrica define o conceito direcional e temporal. A base estatística define o número de grupo de espalhadores adicionais e suas localizações, quando estes existiram. Efeitos como: direção e potência de chegada de cada grupo de espalhadores, a presença ou não de visada direta entre transmissor e receptor a medida que a estação móvel percorre uma célula e a variação da polarização cruzada foram implementados nesse simulador. Desta forma, essa ferramenta computacional simula tanto a dispersão temporal, presente nos modelos de banda larga, como a dispersão angular, utilizadas em sistemas de comunicação móveis que exploram a diversidade espacial. / This work present a simulation tool for macro cell environment based on geometrical and statistical representation of the scatterers and on the COST 259 Directional Channel Model (DCM). A comprehensive review of the propagation prediction models for terrestrial wireless communication systems and geometric channel models, that provide, times of arrival (TOA) and the angle of arrival (AOA) for diferents statistics scatterers distribution is realized. This tool uses gaussianly distributed scatterers for each cluster. This distribution is naturally more realistic than the uniform distribution leading closer to experimental results. This geometrically based model simulates the TOA dispersion present in wide band channel models and the AOA dispersion necessary for systems that explore spatial diversity. This tool also incorporates the concept of line-of-sight and non-line-of-sight and its birth and death as the mobile station moves in a cell, as well as the appearance and disappearance of additional clusters of scatterers. The output provided by this simulation tool is comprised of all the complex amplitudes, delays and angles of arrival of all multipath components associated with each cluster of scatterers. Mean attenuation and slow fading effects are also incorporated to the model and fast fading appears as a consequence of the multipath interference.
42

Ferramenta de simulação computacional de canal de propagação em ambiente celular baseado em modelos geométricos estatísticos. / Communication channel simulation tool based on geometrical and statistical model of macro cell environments.

Sergio Duque Castilho 29 September 2006 (has links)
Este trabalho apresenta uma ferramenta de simulação computacional de canal de propagação para ambiente macro-celular baseada em modelos geométricos e no modelo estatístico apresentado no relatório COST 259 DCM. Para a implementação desta ferramenta é realizada, inicialmente, uma abordagem dos principais modelos de predição de perda por propagação, utilizados atualmente, assim como, um estudo dos modelos geométricos que fornecem as informações de distribuição de potência temporal e angular para diferentes tipos de distribuições estatísticas de espalhadores. A modelagem geométrica utiliza grupos independentes no qual os espalhadores são distribuídos com uma densidade Gaussiana. A utilização desta distribuição Gaussiana leva a distribuições de atraso e ângulo de chegada mais próximas dos resultados de medições do que o usando distribuição uniforme. A base geométrica define o conceito direcional e temporal. A base estatística define o número de grupo de espalhadores adicionais e suas localizações, quando estes existiram. Efeitos como: direção e potência de chegada de cada grupo de espalhadores, a presença ou não de visada direta entre transmissor e receptor a medida que a estação móvel percorre uma célula e a variação da polarização cruzada foram implementados nesse simulador. Desta forma, essa ferramenta computacional simula tanto a dispersão temporal, presente nos modelos de banda larga, como a dispersão angular, utilizadas em sistemas de comunicação móveis que exploram a diversidade espacial. / This work present a simulation tool for macro cell environment based on geometrical and statistical representation of the scatterers and on the COST 259 Directional Channel Model (DCM). A comprehensive review of the propagation prediction models for terrestrial wireless communication systems and geometric channel models, that provide, times of arrival (TOA) and the angle of arrival (AOA) for diferents statistics scatterers distribution is realized. This tool uses gaussianly distributed scatterers for each cluster. This distribution is naturally more realistic than the uniform distribution leading closer to experimental results. This geometrically based model simulates the TOA dispersion present in wide band channel models and the AOA dispersion necessary for systems that explore spatial diversity. This tool also incorporates the concept of line-of-sight and non-line-of-sight and its birth and death as the mobile station moves in a cell, as well as the appearance and disappearance of additional clusters of scatterers. The output provided by this simulation tool is comprised of all the complex amplitudes, delays and angles of arrival of all multipath components associated with each cluster of scatterers. Mean attenuation and slow fading effects are also incorporated to the model and fast fading appears as a consequence of the multipath interference.
43

Design of a Finite-Impulse Response filter generator / Konstruktion av en FIR filter generator

Broddfelt, Michel January 2003 (has links)
<p>In this thesis a FIR filter generator has been designed. The program generates FIR filters in the form of VHDL-files. Four different filter structures have been implemented in the generator, Direct Form (DF), Differential Coefficients Method (DCM), polyphase filters and (2-by-2) filters. </p><p>The focus of the thesis was to implement filter structures that create FIR filters with as low power consumption and area as possible. </p><p>The generaterator has been implemented i C++. The C++ program creates text-files with VHDL-code. The user must then compile and synthesize the VHDL-files. The program uses an text-file with the filter coefficients as input.</p>
44

Design of a Finite-Impulse Response filter generator / Konstruktion av en FIR filter generator

Broddfelt, Michel January 2003 (has links)
In this thesis a FIR filter generator has been designed. The program generates FIR filters in the form of VHDL-files. Four different filter structures have been implemented in the generator, Direct Form (DF), Differential Coefficients Method (DCM), polyphase filters and (2-by-2) filters. The focus of the thesis was to implement filter structures that create FIR filters with as low power consumption and area as possible. The generaterator has been implemented i C++. The C++ program creates text-files with VHDL-code. The user must then compile and synthesize the VHDL-files. The program uses an text-file with the filter coefficients as input.
45

Study on the Biological Treatment of Air-borne VOCs by Sieve-plate Absorption Tower Combined with Activated Sludge Aeration Tank

Chang, Hsiao-Yu 24 October 2005 (has links)
Bioprocesses for air pollution control can generally be categorized as bioscrubber, biofilter, and biotrickling filter systems. These processes have been proven to be economical and effective for control of volatile organic compounds (VOCs) with concentrations of <1,000 mg C m-3 in gas streams. First, an activated sludge aeration tank (W x L x H = 40 x 40 x 300 cm) with a set of 2 mm orifice air spargers was utilized to treat gas-borne VOCs (toluene, p-xylene, and dichloromethane) in air streams. The effects of liquid depth (Z), aeration intensity (G/A), the overall mass transfer rate of oxygen in clean water (KLaO2), the Henry¡¦s law constant of the tested VOC (H), and the influent gaseous VOC concentration (C0) on the efficiency of removal of VOCs were examined and compared with a literature-cited model. Results show that the measured VOC removal efficiencies and those predicted by the model were comparable at a G/A of 3.75 ¡V 11.25 m3 m-2 hr-1 and C0 of around 1,000 ¡V 6,000 mg m-3. Experimental data also indicate that the designed gas treatment reactor with KLaO2 = 5 ¡V 15 hr-1, could achieve > 85% removal of VOCs with H = 0.24 ¡V 0.25 at an aerated liquid depth of 1 m, and > 95% removal of dichloromethane with H = 0.13 at a 1 m liquid depth. The model predicts that, for gas treatment in common activated sludge tanks, with KLaO2 = 5 ¡V 10 hr-1, depth = 3 ¡V 4.5 m, G/A = 9 ¡V 18 m3 m-2 hr-1, > 92% VOC removal can be achieved with operating parameters of Z of 3.0 m and KLaVOC/(G/A) of about 0.28 m-1, for VOCs with H < 0.3, such as most oxygen-containing hydrocarbons with low molecular weights, and benzene, toluene, ethylbenzene, and dichloromethane. Second, an activated sludge aeration tank and a sieve-plate column with six sieve plates were utilized to treat gas-borne VOCs in air streams. The tank was used for the biodegradation of the absorbed VOCs from the column which utilized the activated mixed liquor drawn from the tank as a scrubbing liquor. This research proposed a model for VOC absorption to a down-flow activated sludge liquor in a sieve-plate column. The experimental setup consisted of a pilot-scale activated-sludge tank and a sieve-plate tower, as demonstrated. The sieve-plate tower was constructed from a 25 x 25 x 162 cm (W x L x H) acrylic column with six custom-made sieve plates. Each plate has 382 holes which are 3 mm in diameter arranged on a square pitch. The holes give an open area of 3.82% of the whole plate area for gas flow. Two 25 mm-i.d. down-comer pipes were also equipped to allow for the downflow of the activated sludge liquor. Ports were provided at the column inlet, outlet, and each plate for gas and liquid sampling. Experiments were conducted and the model verified based on the results of tests on the removal efficiencies of isopropyl alcohol (IPA), toluene and p-xylene in the system operated at a range of influent VOC concentrations, air application rates, and liquid/gas flow ratios (L/G). The model developed by a material balance for the gaseous- and liquid-VOC over each plate of the column was developed and experimentally verified in this study. Superficial gas velocity over the column plate (U), number of plates (N), volumetric liquid-phase VOC-transfer coefficient (KLaVOC), aerated liquid depth over the plate (Z), volumetric liquid/gas flow-rate ratio (L/G), dimensionless Henry¡¦s law coefficient of the VOC to be absorbed (H), VOC content of the influent scrubbing liquor (xN+1), and the biodegradation rate constant of the VOC in the activated sludge mixed liquor (k) are among the affecting parameters to the effectiveness of the VOC removal. Model application by the model for effects of affecting parameters on the VOC removal effectiveness indicates that L/G, plate number N, biodegradation rate constant k, Henry¡¦s law constant of VOC H are among the important ones. A L/GH of greater than 2 and N of around 6 are enough for the effective (>90%) removal of the influent VOCs with H < 0.01 if no biodegradation occurred in the column. However, a N of over 16 is required for the influent VOCs with H of around 0.2. Biodegradation with a rate constant of around 100 hr-1 in the column greatly improves the column performance.
46

A Dementia Care Mapping (DCM) data warehouse as a resource for improving the quality of dementia care : exploring requirements for secondary use of DCM data using a user-driven approach and discussing their implications for a data warehouse

Khalid, Shehla January 2016 (has links)
The secondary use of Dementia Care Mapping (DCM) data, if that data were held in a data warehouse, could contribute to global efforts in monitoring and improving dementia care quality. This qualitative study identifies requirements for the secondary use of DCM data within a data warehouse using a user-driven approach. The thesis critically analyses various technical methodologies and then argues the use and further demonstrates the applicability of a modified grounded theory as a user-driven methodology for a data warehouse. Interviews were conducted with 29 DCM researchers, trainers and practitioners in three phases. 19 interviews were face to face with the others on Skype and telephone with an average length of individual interview 45-60 minutes. The interview data was systematically analysed using open, axial and selective coding techniques and constant comparison methods. The study data highlighted benchmarking, mappers’ support and research as three perceived potential secondary uses of DCM data within a data warehouse. DCM researchers identified concerns regarding the quality and security of DCM data for secondary uses, which led to identifying the requirements for additional provenance, ethical and contextual data to be included in a warehouse alongside DCM data to meet requirements for secondary uses of this data for research. The study data was also used to extrapolate three main factors such as an individual mapper, the organization and an electronic data management that can influence the quality and availability of DCM data for secondary uses. The study makes further recommendations for designing a future DCM data warehouse.
47

Camera Based Navigation : Matching between Sensor reference and Video image

Olgemar, Markus January 2008 (has links)
an Internal Navigational System and a Global Navigational Satellite System (GNSS). In navigational warfare the GNSS can be jammed, therefore are a third navigational system is needed. The system that has been tried in this thesis is camera based navigation. Through a video camera and a sensor reference the position is determined. This thesis will process the matching between the sensor reference and the video image. Two methods have been implemented: normalized cross correlation and position determination through a homography. Normalized cross correlation creates a correlation matrix. The other method uses point correspondences between the images to determine a homography between the images. And through the homography obtain a position. The more point correspondences the better the position determination will be. The results have been quite good. The methods have got the right position when the Euler angles of the UAV have been known. Normalized cross correlation has been the best method of the tested methods.
48

Reversibles und irreversibles Photobleichen an einzelnen Molekülen und im Ensemble

Brabandt, Jörg 06 October 2006 (has links)
Im Rahmen der Diplomarbeit wurde das Bleichverhalten der organischen Fluoreszenzfarbstoffe Rhodamin 6G und DCM untersucht. Dazu wurden Absorptionsmessungen sowie spektroskopische und mirkoskopische Verfahren angewandt. Es konnte auf Ensembleebene sowie durch Statistiken für einzelne Moleküle gezeigt werden, dass ein reversibler und eine irreversibler Anteil des Bleichens existieren und sich diese Experimentell voneinander trennen lassen.
49

A Dementia Care Mapping (DCM) data warehouse as a resource for improving the quality of dementia care. Exploring requirements for secondary use of DCM data using a user-driven approach and discussing their implications for a data warehouse

Khalid, Shehla January 2016 (has links)
The secondary use of Dementia Care Mapping (DCM) data, if that data were held in a data warehouse, could contribute to global efforts in monitoring and improving dementia care quality. This qualitative study identifies requirements for the secondary use of DCM data within a data warehouse using a user-driven approach. The thesis critically analyses various technical methodologies and then argues the use and further demonstrates the applicability of a modified grounded theory as a user-driven methodology for a data warehouse. Interviews were conducted with 29 DCM researchers, trainers and practitioners in three phases. 19 interviews were face to face with the others on Skype and telephone with an average length of individual interview 45-60 minutes. The interview data was systematically analysed using open, axial and selective coding techniques and constant comparison methods. The study data highlighted benchmarking, mappers’ support and research as three perceived potential secondary uses of DCM data within a data warehouse. DCM researchers identified concerns regarding the quality and security of DCM data for secondary uses, which led to identifying the requirements for additional provenance, ethical and contextual data to be included in a warehouse alongside DCM data to meet requirements for secondary uses of this data for research. The study data was also used to extrapolate three main factors such as an individual mapper, the organization and an electronic data management that can influence the quality and availability of DCM data for secondary uses. The study makes further recommendations for designing a future DCM data warehouse.
50

Fragmentation in Proton-Nucleus Reactions from 100 to 1400 MeV

Jäderström, Henrik January 2008 (has links)
The heaviest fragments, recoils, have been studied in proton and deuteron induced 28Si reactions and proton-20Ne reactions at 100-300 MeV per nucleon. Inclusive charge and angular distributions and coincidences between He nuclei and recoils have been compared to two theoretical models, Dubna Cascade Model and JAERI Quantum Molecular Dynamics. The overall agreement was good for the reactions with 28Si, however the angular distributions of He fragments could not be reproduced. For the 20Ne reactions the recoil angular distributions were only reproduced for large angles. There was a significant underestimation at small angles and low recoil charge. α-clustering in the bombarding nucleus is a possible explanation for the deviations. In the 100 MeV per nucleon reactions all assumptions of the models may not be valid and the agreement was worst for these reactions. In proton-natXe reactions intermediate mass fragments have been studied from 200 to 1400 MeV. Slow ramping was used to scan the energy. Charge distributions and a caloric curve have been compared to Cascade Fragmentation Evaporation Model. Charge distributions showed good agreement for fragments with Z&lt;8 but the heavier fragments were underestimated.

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