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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.
31

Pulsar scattering and the ionized interstellar medium

Geyer, Marisa January 2017 (has links)
Fifty years after the discovery of the first pulsating neutron star, the field of pulsar science has grown into a multidisciplinary research field, working to address a wide range of problems in astrophysics - from stellar evolution models to high precision tests of General Relativity to analysing the detailed structure of the Interstellar Medium in the Milky Way. Over 2500 Galactic pulsars have been discovered. The next generation telescopes, such as the Square Kilometre Array, promise to discover the complete observable Milky Way population, of several tens of thousands, over the next decade. These point sources in the sky have extreme properties, with matter densities comparable to that of an atomic nucleus, and surface magnetic fields a trillion times stronger than Earth's magnetic field. Observationally, the most valuable property is their rotational stability - allowing us to anticipate and sum their beamed radio emission, as the pulsar spins around its axis, on millisecond to second timescales. The detected radio wave signals carry with them information of the ionised interstellar medium (IISM) paths they traveled along. The imprints reveal that the pulsar signals we detect travel along multiple paths. While the bulk of the emitted signal propagates along a straight line, we also receive delayed emission scattered through small angles, back into our line of sight. This scattering is caused by fluctuations in the free electron densities of the IISM. The impact of these inhomogeneities is exaggerated at low observing frequencies, where averaged pulsar profiles are observed to be broadened, and showcase exponential scattering tails characterised by a scattering timescale &gcy;. Simple theoretical models predict a power law dependence of &gcy; on frequency, with a spectral index &alpha; = 4. Despite these predictions, my analysis of pulsar data in this thesis, reveal a more complex frequency dependence on &gcy;. I investigate the scattering characteristics of a set of pulsars observed by the Low Frequency Array (LOFAR), at 110~MHz to 190~MHz. These data are ideal datasets for accurate studies of pulsar scattering, providing broad frequency bands at low frequencies. I find anomalously low power law spectral indices, &alpha;, describing the frequency dependence of &gcy;. These indices are likely due to anisotropic scattering mechanisms or small scattering clouds in the IISM. To conduct effective data analysis, I develop scattering fitting techniques by first analysing IISM effects on simulated pulsar data. I investigate the effects of two different types of scattering mechanisms, isotropic and anisotropic scattering, and consider each of their particular frequency-dependent impacts on pulsar data. The work on simulated data provides a robust fitting technique for extracting scattering parameters and a framework for the interpretation of the LOFAR data used in this study. The fitting technique simultaneously models scattering effects and standard frequency-dependent pulse profile evolution. I present results for 13 pulsars with simple pulse shapes, and find that &gcy;, associated with scattering by a single thin screen, has a power law dependence on frequency with &alpha; ranging from 1.50 to 4.0. My results show that extremely anisotropic scattering can cause low &alpha; measurements. The anomalous scattering properties can also be caused by the presence of small scattering clumps in the IISM, as opposed to the conventionally modelled large scattering screens. Evidence for both anisotropic scattering and small scattering clouds with high electron densities come from other areas of research. Indications of the anisotropic nature of the local IISM mostly come from high resolution pulsar scintillation analyses, while evidence for high density scattering clouds is often based on extreme scattering events measured through quasar observations. My results suggest that these anomalous scattering properties are more prevalent than formerly thought, prompting us to reconsider the physical conditions of the IISM, where traditionally high electron densities are reserved for H<sub>II</sub> regions and anisotropy is not modelled. High quality, low frequency pulsar data, where anomalous propagation effects become measurable, are a valuable addition in assisting us to distinguish between the different physical mechanisms that can be at play. The more complex these IISM characteristics reveal themselves to be, the harder it will be to disentangle intrinsic profile emission from IISM propagation imprints. Successfully separating these effects, however, promises to improve our understanding of the intrinsic pulsar radio emission - a process that is still poorly understood.
32

Logotherapy and imagery work: the contribution of Boeschemeyer’s ‘Wertimagination’

Meyer-Prentice, Monika 14 September 2011 (has links)
In this qualitative, interpretive study a new and promising imagery technique, called Wertimagination (WIM®) [Value-Oriented Imagery] was researched. It was developed by the logotherapist Uwe Boeschemeyer in Germany. At the main focus of this study are the psychotherapeutic work experiences of logotherapists applying WIM®. Their perceptions with regard to Wertimagination’s potencies, limitations and its overall contribution to Logotherapy are explored. Eight semi-structured expert interviews were conducted with German logotherapists offering WIM® at their practice. The interview contents are analysed and compared with supplementing perspectives: with Wertimagination experiences reported by other (logo)therapists, by clients and by the developer of the method (Boeschemeyer), extracted from the existing body of literature. The results show that Value-Oriented Imagery by all three researched parties – (logo)therapists, clients and its developer – is experienced to be a high potential logotherapeutic, salutogenetic (resources-oriented) approach contributing inter alia towards a person’s inner meaning finding, selfacceptance and trust in life. / Psychology / M.A. (Psychology)
33

Detekce nápravy v systému vážení za jízdy / Axle detection in the weighing vehicle system

Mičulka, Martin January 2021 (has links)
This master's thesis deals with the Weight in Motion systems (WIM). The main goal is to create simulation software that detects dual tires assembly with respect to the angle with which the sensor is embedded into the road. Thesis also contains literature search of available solutions of weighing systems and the sensors which are used in these systems. Subsequently, the thesis contains software for recognizing simple assembly or dual tires assembly from real measured data. Software solutions were developed using programming language Python v3.7. All source codes were developed in PyCharm Community Edition 2020.
34

Melancholy and the Photo-Historical Approach in the Films of Wim Wenders

Baker, William Andrew 30 September 2021 (has links)
No description available.
35

Pesagem em movimento e caracterização do tráfego ferroviário com uso da técnica B-WIM / Weighing in motion and characterization of the rail traffic with using the technique B-WIM

CARVALHO NETO, José Alves de 26 February 2014 (has links)
Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2015-01-27T18:33:19Z No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Dissertacao_PesagemMovimentoCaracterizacao.pdf: 5817774 bytes, checksum: bffe4c7106d0747f52959b54504702a0 (MD5) / Rejected by Edisangela Bastos (edisangela@ufpa.br), reason: on 2015-01-29T18:13:44Z (GMT) / Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2015-01-30T17:50:00Z No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Dissertacao_PesagemMovimentoCaracterizacao.pdf: 5817774 bytes, checksum: bffe4c7106d0747f52959b54504702a0 (MD5) / Approved for entry into archive by Albirene Aires (albireneufpa@gmail.com) on 2015-02-02T12:06:43Z (GMT) No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Dissertacao_PesagemMovimentoCaracterizacao.pdf: 5817774 bytes, checksum: bffe4c7106d0747f52959b54504702a0 (MD5) / Made available in DSpace on 2015-02-02T12:06:43Z (GMT). No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Dissertacao_PesagemMovimentoCaracterizacao.pdf: 5817774 bytes, checksum: bffe4c7106d0747f52959b54504702a0 (MD5) Previous issue date: 2014 / Nesta dissertação é apresentado o desenvolvimento de algoritmos para aplicação do método Bridge-Weigh In Motion (B-WIM) para a pesagem em movimento de trens e para a caracterização do tráfego ferroviário, permitindo-se obter informações sobre a velocidade de passagem dos trens, número e espaçamento entre eixos. Os sistemas B-WIM a partir de uma simples instrumentação permitem determinar as cargas por eixo de veículos em movimento, eliminando o efeito dinâmico. Foram implementados os algoritmos para a determinação dos valores referentes a geometria do trem e das cargas, que foi validado a partir de um exemplo teórico, onde se simulou a passagem de um trem de características conhecidas sobre a ponte e as cargas por eixos foram determinadas com 100% de exatidão. Além disso, foi feito um exemplo numérico em elementos finitos, de um viaduto em concreto armado para aplicação do método, onde foi feita a determinação das cargas por eixo para diferentes velocidades de passagem do trem. A fim de reduzir o tempo de processamento nas análises do exemplo numérico, foi desenvolvido um algoritmo para a geração de cargas nodais no modelo numérico que reduziram o tempo de processamento em até 96% quando comparado com a análise de múltiplos passos (“Multi-Step”), que simula automaticamente a passagem do trem sobre a estrutura. Finalmente, o método foi testado em um caso real a partir de monitorações realizadas em um viaduto de concreto armado da Estrada de Ferro Carajás. Apesar de não ter sido possível a determinação das cargas por eixo da locomotiva, foi possível medir precisamente o peso bruto total da locomotiva quando se utilizou o modelo constitutivo de Collins & Mitchell (1991) para o concreto. / This Master’s Thesis presents the development of algorithms for application of Bridge- Weigh In Motion (B-WIM) for weighing moving trains and method for the characterization of rail traffic, allowing up to obtain information about the speed of passage of trains , number and axle spacing. The B-WIM systems from a simple instrumentation for determining the axle loads of moving vehicles, eliminating the dynamic effect. The algorithms for determining the values related the geometry of the train and axle loads were implemented, which was validated from a theoretical example, where we simulated the passage of a train of known characteristics over the bridge and axle loads were determined 100% accuracy. In addition, a numerical example was done in finite element method, of a reinforced concrete viaduct for application of the method, where was determine axle loads for different speeds of train passage. In order to reduce the processing time of the analysis in the numerical example, an algorithm for generating the numerical model nodal loads was implemented that have reduced processing time by 96% compared to the analysis of multi-step, which automatically simulates the passage of the train over the structure. Finally, the method was tested on a real case from monitoring tests realized on a reinforced concrete viaduct in the Carajás Railroad. Although it was not possible to determine the axle load locomotive, it was possible to measure accurately the gross weight of the locomotive when using the constitutive model of Collins and Mitchell (1991) for concrete.
36

Developing a methodology to account for commercial motor vehicles using microscopic traffic simulation models

Schultz, Grant George 30 September 2004 (has links)
The collection and interpretation of data is a critical component of traffic and transportation engineering used to establish baseline performance measures and to forecast future conditions. One important source of traffic data is commercial motor vehicle (CMV) weight and classification data used as input to critical tasks in transportation design, operations, and planning. The evolution of Intelligent Transportation System (ITS) technologies has been providing transportation engineers and planners with an increased availability of CMV data. The primary sources of these data are automatic vehicle classification (AVC) and weigh-in-motion (WIM). Microscopic traffic simulation models have been used extensively to model the dynamic and stochastic nature of transportation systems including vehicle composition. One aspect of effective microscopic traffic simulation models that has received increased attention in recent years is the calibration of these models, which has traditionally been concerned with identifying the "best" parameter set from a range of acceptable values. Recent research has begun the process of automating the calibration process in an effort to accurately reflect the components of the transportation system being analyzed. The objective of this research is to develop a methodology in which the effects of CMVs can be included in the calibration of microscopic traffic simulation models. The research examines the ITS data available on weight and operating characteristics of CMVs and incorporates this data in the calibration of microscopic traffic simulation models. The research develops a methodology to model CMVs using microscopic traffic simulation models and then utilizes the output of these models to generate the data necessary to quantify the impacts of CMVs on infrastructure, travel time, and emissions. The research uses advanced statistical tools including principal component analysis (PCA) and recursive partitioning to identify relationships between data collection sites (i.e., WIM, AVC) such that the data collected at WIM sites can be utilized to estimate weight and length distributions at AVC sites. The research also examines methodologies to include the distribution or measures of central tendency and dispersion (i.e., mean, variance) into the calibration process. The approach is applied using the CORSIM model and calibrated utilizing an automated genetic algorithm methodology.
37

Developing a methodology to account for commercial motor vehicles using microscopic traffic simulation models

Schultz, Grant George 30 September 2004 (has links)
The collection and interpretation of data is a critical component of traffic and transportation engineering used to establish baseline performance measures and to forecast future conditions. One important source of traffic data is commercial motor vehicle (CMV) weight and classification data used as input to critical tasks in transportation design, operations, and planning. The evolution of Intelligent Transportation System (ITS) technologies has been providing transportation engineers and planners with an increased availability of CMV data. The primary sources of these data are automatic vehicle classification (AVC) and weigh-in-motion (WIM). Microscopic traffic simulation models have been used extensively to model the dynamic and stochastic nature of transportation systems including vehicle composition. One aspect of effective microscopic traffic simulation models that has received increased attention in recent years is the calibration of these models, which has traditionally been concerned with identifying the "best" parameter set from a range of acceptable values. Recent research has begun the process of automating the calibration process in an effort to accurately reflect the components of the transportation system being analyzed. The objective of this research is to develop a methodology in which the effects of CMVs can be included in the calibration of microscopic traffic simulation models. The research examines the ITS data available on weight and operating characteristics of CMVs and incorporates this data in the calibration of microscopic traffic simulation models. The research develops a methodology to model CMVs using microscopic traffic simulation models and then utilizes the output of these models to generate the data necessary to quantify the impacts of CMVs on infrastructure, travel time, and emissions. The research uses advanced statistical tools including principal component analysis (PCA) and recursive partitioning to identify relationships between data collection sites (i.e., WIM, AVC) such that the data collected at WIM sites can be utilized to estimate weight and length distributions at AVC sites. The research also examines methodologies to include the distribution or measures of central tendency and dispersion (i.e., mean, variance) into the calibration process. The approach is applied using the CORSIM model and calibrated utilizing an automated genetic algorithm methodology.
38

Logotherapy with Boeschemeyer's value-oriented imagery in multicultural contexts

Meyer-Prentice, Monika 12 November 2013 (has links)
In this qualitative, interpretive, multi-perspective study a new and promising salutogenic imagery approach developed in Germany, called Value-Oriented Imagery (Wertimagination/WIM®) was researched in regard to its applicability in multicultural (non-European) contexts. A second question researched was whether specific cultural or regional “dialects” would be encountered in the universal inner picture language of persons from other (non-European) cultural backgrounds than the one the approach was developed within. A WIM® study with eighteen participants from African South African, Asian South African and European South African cultural backgrounds was conducted in Johannesburg in 2011 and 2012. The results were analysed and compared with WIM® work experiences from Germany. Subsequently the results of the comparison were discussed in three WIM® expert interviews: with Uwe Boeschemeyer, Stephan Peeck and Andreas Boeschemeyer. The main outcome of this research study is that Value-Oriented Imagery can be seen as a rewarding contribution to South African multicultural (logo)therapy/ counselling contexts. Only minor cultural and regional “dialects” occurred in the universal inner symbols of the RSA study participants, such as the occurrence of more water features, especially waterfalls, and more spontaneous, unintended Healthy Inner Child encounters. The present study suggests that work with Value- Oriented Imagery could make a valuable contribution within any cultural and multicultural (logo)therapy/counselling context. / Psychology / D. Litt. et Phil. (Psychology)
39

Logotherapy with Boeschemeyer's value-oriented imagery in multicultural contexts

Meyer-Prentice, Monika 03 1900 (has links)
In this qualitative, interpretive, multi-perspective study a new and promising salutogenic imagery approach developed in Germany, called Value-Oriented Imagery (Wertimagination/WIM®) was researched in regard to its applicability in multicultural (non-European) contexts. A second question researched was whether specific cultural or regional “dialects” would be encountered in the universal inner picture language of persons from other (non-European) cultural backgrounds than the one the approach was developed within. A WIM® study with eighteen participants from African South African, Asian South African and European South African cultural backgrounds was conducted in Johannesburg in 2011 and 2012. The results were analysed and compared with WIM® work experiences from Germany. Subsequently the results of the comparison were discussed in three WIM® expert interviews: with Uwe Boeschemeyer, Stephan Peeck and Andreas Boeschemeyer. The main outcome of this research study is that Value-Oriented Imagery can be seen as a rewarding contribution to South African multicultural (logo)therapy/ counselling contexts. Only minor cultural and regional “dialects” occurred in the universal inner symbols of the RSA study participants, such as the occurrence of more water features, especially waterfalls, and more spontaneous, unintended Healthy Inner Child encounters. The present study suggests that work with Value- Oriented Imagery could make a valuable contribution within any cultural and multicultural (logo)therapy/counselling context. / Psychology / D. Litt. et Phil. (Psychology)

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