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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.
71

Multi-dimensional data analysis in electron microscopy

Ostasevicius, Tomas January 2017 (has links)
This thesis discusses various large multi-dimensional dataset analysis methods and their applications. Particular attention is paid to non-linear optimization analyses and general processing algorithms and frameworks when the datasets are significantly larger than the available computer memory. All new presented algorithms and frameworks were implemented in the HyperSpy analysis toolbox. A novel Smart Adaptive Multi-dimensional Fitting (SAMFire) algorithm is presented and applied across a range of scanning transmission electron microscope (STEM) experiments. As a result, the Stark effect in quantum disks was mapped in a cathodoluminescence STEM experiment, and fully quantifiable 3D atomic distributions of a complex boron nitride core-shell nanoparticle were reconstructed from an electron energy loss spectrum (EELS) tilt-series. The EELS analysis also led to the development of two new algorithms to extract EELS near-edge structure fingerprints from the original dataset. Both approaches do not rely on standards, are not limited to thin or constant thickness particles and do not require atomic resolution. A combination of the aforementioned fingerprinting techniques and SAMFire allows robust quantifiable EELS analysis of very large regions of interest. A very large dataset loading and processing framework, “LazySignal”, was developed and tested on scanning precession electron diffraction (SPED) data. A combination of SAMFire and LazySignal allowed efficient analysis of large diffraction datasets, successfully mapping strain across an extended (ca. 1 μm × 1 μm) region and classifying the strain fields around precipitate needles in an aluminium alloy.
72

Automating Fixture Setups Based on Point Cloud Data & CAD Model

January 2016 (has links)
abstract: Metal castings are selectively machined-based on dimensional control requirements. To ensure that all the finished surfaces are fully machined, each as-cast part needs to be measured and then adjusted optimally in its fixture. The topics of this thesis address two parts of this process: data translations and feature-fitting clouds of points measured on each cast part. For the first, a CAD model of the finished part is required to be communicated to the machine shop for performing various machining operations on the metal casting. The data flow must include GD&T specifications along with other special notes that may be required to communicate to the machinist. Current data exchange, among various digital applications, is limited to translation of only CAD geometry via STEP AP203. Therefore, an algorithm is developed in order to read, store and translate the data from a CAD file (for example SolidWorks, CREO) to a standard and machine readable format (ACIS format - *.sat). Second, the geometry of cast parts varies from piece to piece and hence fixture set-up parameters for each part must be adjusted individually. To predictively determine these adjustments, the datum surfaces, and to-be-machined surfaces are scanned individually and the point clouds reduced to feature fits. The scanned data are stored as separate point cloud files. The labels associated with the datum and to-be-machined (TBM) features are extracted from the *.sat file. These labels are further matched with the file name of the point cloud data to identify data for the respective features. The point cloud data and the CAD model are then used to fit the appropriate features (features at maximum material condition (MMC) for datums and features at least material condition (LMC) for TBM features) using the existing normative feature fitting (nFF) algorithm. Once the feature fitting is complete, a global datum reference frame (GDRF) is constructed based on the locating method that will be used to machine the part. The locating method is extracted from a fixture library that specifies the type of fixturing used to machine the part. All entities are transformed from its local coordinate system into the GDRF. The nominal geometry, fitted features, and the GD&T information are then stored in a neutral file format called the Constraint Tolerance Feature (CTF) Graph. The final outputs are then used to identify the locations of the critical features on each part and these are used to establish the adjustments for its setup prior to machining, in another module, not part of this thesis. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2016
73

Análise microestrutural e da resistência à fadiga de zircônia monolítica submetida a protocolos de ajuste simulado / Microstructural analysis and fatigue strength of monolithic zirconia simulating adjustment protocols

Chun, Eliseo Pablo [UNESP] 03 February 2017 (has links)
Submitted by ELISEO CHUN (eliseo_87@hotmail.com) on 2017-04-04T10:50:28Z No. of bitstreams: 1 Eliseo Pablo Chun.pdf: 9088861 bytes, checksum: f60b63016ee4a5580ad6f0bdef8ef694 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-04-12T16:31:03Z (GMT) No. of bitstreams: 1 chun_ep_me_sjc.pdf: 9088861 bytes, checksum: f60b63016ee4a5580ad6f0bdef8ef694 (MD5) / Made available in DSpace on 2017-04-12T16:31:03Z (GMT). No. of bitstreams: 1 chun_ep_me_sjc.pdf: 9088861 bytes, checksum: f60b63016ee4a5580ad6f0bdef8ef694 (MD5) Previous issue date: 2017-02-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho foi investigar as propriedades microestruturais e a resistência à fadiga de amostras de zircônia parcialmente estabilizada por óxido de ítrio (Y-TZP) para uso em forma monolítica (Vita YZ HT, Vita Zahnfabrik, Alemanha) após diferentes protocolos de ajuste clínico simulado. 162 discos de Y-TZP HT (12 mm de diâmetro, 0,8 mm de altura) foram confeccionados e aleatoriamente divididos em 6 grupos de acordo com as simulações (n=27): S- Y-TZP sinterizada (sem desgaste, sem glaze); G- Y-TZP sinterizada (sem desgaste) e glazeada; PdG- ajuste simulado da Y-TZP com ponta diamantada seguido por aplicação de glaze; GPd- ajuste simulado com ponta diamantada da Y-TZP já glazeada; PdBdG- ajuste simulado com ponta diamantada, seguido por borracha diamantada e aplicação do glaze; GPdBd- ajuste simulado com ponta diamantada, seguido por borracha diamantada da Y-TZP já glazeada. Após teste monotônico sob flexão biaxial (n=3, célula de carga de 1000 kgf, velocidade de 1 mm/min), os espécimes restantes foram distribuídos na proporção 3:2:3 e testados sob fadiga acelerada (step stress) em três perfis de carregamento (leve, moderado e agressivo), variando-se os incrementos de carga e número de ciclos. Os espécimes representativos fraturados foram avaliados em estereomicroscopio e microscópio eletrônico de varredura (MEV) e as características microestruturais das superfícies obtidas com os diferentes protocolos foram analisadas quanto a difração de raios-X, rugosidade média (Ra), perfilometria e MEV. Os dados de sobrevivência ou fratura foram utilizados para cálculo do valor beta (β) de Weibull e da confiabilidade para missões de 300.000 e 600.000 ciclos a 200 N. Os espectros obtidos pela difração foram comparados com espectros padrão de bancos de dados. Os dados de Ra foram analisados estatisticamente por ANOVA 1 fator e teste de Tukey (ambos, a=5%). As imagens foram analisadas qualitativamente e descritas. Não houve alteração significativa na cristalografia da zircônia após as simulações de ajuste clínico. A zircônia HT não tratada (S) apresentou menor probabilidade de sobrevivência, após 600.000 ciclos a 200 N, em comparação com a Y-TZP HT desgastada com ponta diamantada e glazeada (PdG) e após o polimento final com borracha diamantada (GPdBd). Apesar dos protocolos de ajuste simulado não alterarem a cristalografia da zircônia, o polimento final com borracha diamantada (GPdBd) resultou em uma superfície mais homogênea em comparação com amostras glazeadas (G, PdG e PdBdG). O glaze se acumulou em “ilhas” sobre todas as superfícies analisadas. Concluiu-se que a Y-TZP HT tem maior probabilidade de sobrevivência quando glazeada após desgaste com ponta diamantada (PdG) ou com polimento finalizado por borrachas diamantadas (GPdBd). / The objective of this study was to investigate the microstructural properties and fatigue resistance of zirconia partially stabilized by yttrium oxide (Y-TZP) for use in monolithic form (Vita YZ HT, Vita Zahnfabrik, Germany) after different clinical adjustment protocols simulation. 162 disc of Y-TZP HT (12 mm diameter, 0.8 mm high) were made and randomly divided into 6 groups according to the adjustment protocol (n = 27): S- Y-TZP as sintered (without adjustment and glaze); G- glazed Y-TZP (without adjustment); PdG- Y-TZP with adjustment simulation procedure with diamond bur followed by glaze application; GPd- glazed Y-TZP followed by adjustment simulation procedure with diamond bur; PdBdG- Y-TZP with adjustment simulation procedure with diamond bur and polishing kit, followed by glaze application; GPdBd- glazed Y-TZP with adjustment simulation procedure with bur followed by polishing kit. After monotonic testing under biaxial flexure (n=3, 1000 kgf load cell, 1 mm/min speed), the remaining specimens were distributed into 3:2:3 ratio and tested under step-stress in three profiles (light, moderate and aggressive), varying the load, increments and number of cycles. The fractured representative specimens were evaluated in a stereomicroscope and scanning electron microscope (SEM) and the microstructural characteristics of the surfaces obtained with different protocols were analyzed by X-ray diffraction, mean roughness (Ra), profilometry and SEM. Survival or fracture data were used to calculate Weibull's beta (β) value and reliability for 300,000 and 600,000 cycles at 200 N. The spectra obtained by the diffraction were compared with standard spectra from databases. Ra data were statistically analyzed by 1-way ANOVA and Tukey’s test (both, a=5%). The images were analyzed and qualitatively described. There was no significant change in zirconia crystallography after the simulations of clinical adjustment. The untreated Y-TZP HT (S) presented a lower probability of survival after 600,000 cycles at 200 N, compared to Y-TZP HT adjusted with diamond bur and glazed (PdG). and after final polishing with polishing kit (GPdBd). Although the simulated adjustment protocols did not alter the crystallography of the Y-TZP HT, the final polishing with diamond rubber (GPdBd) resulted in a more homogeneous surface compared to glazed samples (G, PdG and PdBdG). The glaze was accumulated in "islands" on all analyzed surfaces. It could be concluded that Y-TZP HT is more likely to survive when glazed after diamond adjustments (PdG) or when it is finished with polishing kit (GPdBd).
74

Identificação de impedâncias de sistemas de potência trifásicos por meio do método vector fitting / Three-phase power system impedance identification by using the vector fitting method

Costa, Tito Ricardo Vaz da 19 December 2013 (has links)
Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2013. / Submitted by Alaíde Gonçalves dos Santos (alaide@unb.br) on 2014-05-09T10:17:57Z No. of bitstreams: 1 2013_TitoRicardoVazdaCosta.pdf: 1644763 bytes, checksum: 9fa433c622de5e79882143d10503dbd9 (MD5) / Approved for entry into archive by Guimaraes Jacqueline(jacqueline.guimaraes@bce.unb.br) on 2014-07-02T13:56:30Z (GMT) No. of bitstreams: 1 2013_TitoRicardoVazdaCosta.pdf: 1644763 bytes, checksum: 9fa433c622de5e79882143d10503dbd9 (MD5) / Made available in DSpace on 2014-07-02T13:56:31Z (GMT). No. of bitstreams: 1 2013_TitoRicardoVazdaCosta.pdf: 1644763 bytes, checksum: 9fa433c622de5e79882143d10503dbd9 (MD5) / A presente dissertação propõe o cálculo de um modelo de equivalente dinâmico para sistemas de potência trifásicos, com quatro terminais, sendo três referentes às fases e um de referência. A técnica é apropriada para a obtenção de redes elétricas com o propósito de substituir uma determinada parte do sistema elétrico (rede externa), a qual admite-se ser de menor impacto para a área específica de estudos (rede interna). Para determinação do equivalente trifásico, são necessárias apenas duas impedâncias, pois estas são os parâmetros básicos de um circuito trifásico acoplado. O interesse nesse equivalente é somente no cálculo de impedâncias, pois a finalidade do estudo é avaliar o impacto da geração de harmônicos na área do sistema considerada interna, onde há a fonte. Uma impedância própria e uma mútua são obtidas por meio de ajuste de grandezas medidas na barra de fronteira que separa a área interna da externa. O ajuste no domínio da frequência é baseado na técnica Vector Fitting. Para validação dos resultados, são realizadas simulações em regime permanente e comparadas as tensões nas três fases da barra de fronteira. O resultado também é comprovado a partir de curvas de resposta em frequência das tensões na barra de fronteira. Em ambos os casos, obtiveram-se resultados satisfatórios com desvio quadrado médio entre os resultados considerando o sistema completo e com o equivalente. Resultados satisfatórios também foram observados em simulações com o sistema submetido a desequilíbrio de corrente entre as fases. Os testes para avaliação do desempenho da técnica foram realizados em um sistema de 9 barras, das quais duas delas integram a área interna. _______________________________________________________________________________________ ABSTRACT / This master thesis proposes the computation of a three-phase power system dynamic equivalent which has four terminals. Three of these ports are related to phases and one is the reference. The technique is appropriated for obtaining an electrical network for replacing a part of a given power system (known as external network). This part of the system has a level of importance less than a specific electrical network (internal area), since this latter one is the target of the studies. For determining the three-phase equivalent two impedances are calculated named as self and mutual impedances. These parameters are used to form a coupled circuit. The equivalent replaces an external full network connected to an internal network through a border bus. The self and mutual impedance terms are obtained by setting vector quantities measured on the boundary of the system bus. For setting we make use of the methodology based on Vector Fitting. Results are validated by performing time simulations at steady state and by comparing the voltages at the three phase border bus. Also, the results are confirmed through simulations considering frequency response data. In both cases, the performance for computing the dynamic equivalent is considered satisfactory. This is justified by verifying the very low mean square deviation between results for the complete and equivalent system. All experiments were carried out by considering a 9-bus power system which has two bus inside the study zone.
75

Teleaudiology: Clinical Outcomes from Adults with Hearing Loss

Fedt, Lauren Alexandra, Fedt, Lauren Alexandra January 2017 (has links)
Outside of major metropolitan areas, Arizona has limited options for hearing healthcare. The Arizona Affordable Hearing Aid Task Force proposed the development of a statewide program to provide low-cost hearing aids and audiologic care to low-income residents. The purpose of this review was to determine the status of the literature on the clinical outcomes of teleaudiology services for evaluations and hearing aid fittings which could be used to serve inhabitants of rural counties and address the goals of the Task Force. A literature search was performed to identify articles with original research in teleaudiology in the areas of evaluation and treatment and yielded 234 results. After exclusion criteria were applied, there were 15 articles for review; 10 articles focused on audiological evaluation and 5 articles focused on verification, validation, and counseling for hearing aid fittings. Evaluation-related articles showed that pure-tone air conduction testing was generally within the ± 5 dB acceptable range of variability, with little evidence on bone conduction or speech testing reliability. Studies reporting real-ear measurements with probe microphones were shown to yield similar results in traditional and teleaudiology fitting sessions and validation measures documented similar or better outcomes from teleaudiology fittings. Based on the literature, it is concluded that the use of teleaudiology is feasible for hearing aid fittings and counseling in rural areas, if associated barriers related to costs and limitations related to the availability of technology are overcome.
76

Costs and effectiveness of hearing aid rehabilitation in the elderly

Vuorialho, A. (Arja) 17 October 2006 (has links)
Abstract Hearing aid (HA) rehabilitation was studied in northern Finland. The costs of HA fitting were examined at two hospitals, Kainuu Central Hospital and Oulu University Hospital. The patients were visited and interviewed at their home and use of HAs was charted. The benefit of HAs was evaluated using generic and disease-specific questionnaires. The effect of follow-up counselling of HA users on HA use and on the benefit of HAs was studied. The proportion of all HA possessors that are regular users has clearly increased during the past twenty years, and the number of non-users, in particular, has decreased significantly. Only 5.3% of first fitted HAs were not in use in 2001. The costs of HA fitting in 2000 were approximately € 900. There was not much difference in the costs between Kainuu Central Hospital and Oulu University Hospital. The price of a HA accounted for somewhat less than half of the total hospital costs, and the costs of the audiology personnel made up roughly a third of the overall costs. Emotional problems of HA users were significant before HA fitting, but six months after HA fitting the number of patients who felt handicapped by their hearing problems had decreased significantly. This could be seen in the results of both the social and the emotional items of the disease-specific health-related quality-of-life (HRQOL) measure, the short version of the Hearing Handicap Inventory for the Elderly (HHIE-S). The benefit could not, however, be shown with the generic HRQOL instrument, the EuroQol questionnaire (EQ-5D), which apparently lacks sensitivity for measuring changes brought about by audiological intervention. Follow-up counselling of HA users can significantly increase HA use and decrease the number of non-users. It can also significantly increase the users' handling skills. The cost of follow-up counselling is approximately € 83 per fitted HA, which is an 8.7% increment to the calculated cost of fitting a HA.
77

Model Fitting for Electric Arc Furnace Refining

Rathaba, Letsane Paul 10 June 2005 (has links)
The dissertation forms part of an ongoing project for the modelling and eventual control of an electric arc furnace (EAF) process. The main motivation behind such a project is the potential benefits that can result from automation of a process that has largely been operator controlled, often with results that leave sufficient room for improvement. Previous work in the project has resulted in the development of a generic model of the process. A later study concentrated on the control of the EAF where economic factors were taken into account. Simulation results from both studies clearly demonstrate the benefits that can accrue from successful implementation of process control. A major drawback to the practical implementation of the results is the lack of a model that is proven to be an accurate depiction of the specific plant where control is to be applied. Furthermore, the accuracy of any process model can only be verified against actual process data. There lies the raison d'etre for this dissertation: to take the existing model from the simulation environment to the real process. The main objective is to obtain a model that is able to mimic a selected set of process outputs. This is commonly a problem of system identification (SID): to select an appropriate model then fit the model to plant input/output data until the model response is similar to the plant under the same inputs (and initial conditions). The model fitting is carried out on an existing EAF model primarily by estimation of the model parameters for the EAF refining stage. Therefore the contribution of this dissertation is a model that is able to depict the EAF refining stage with reasonable accuracy. An important aspect of model fitting is experiment design. This deals with the selection of inputs and outputs that must be measured in order to estimate the desired parameters. This constitutes the problem of identifiability: what possibilities exist for estimating parameters using available I/O data or, what additional data is necessary to estimate desired parameters. In the dissertation an analysis is carried out to determine which parameters are estimable from available data. For parameters that are not estimable recommendations are made about additional measurements required to remedy the situation. Additional modelling is carried out to adapt the model to the particular process. This includes modelling to incorporate the oxyfuel subsystem, the bath oxygen content, water cooling and the effect of foaming on the arc efficiency. / Dissertation (MEng (Electronic Engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted
78

Depth Map Compression Based on Platelet Coding and Quadratic Curve Fitting

Wang, Han January 2012 (has links)
Due to the fast development in 3D technology during recent decades, many approaches in 3D representation technologies have been proposed worldwide. In order to get an accurate information to render a 3D representation, more data need to be recorded compared to normal video sequence. In this case, how to find an efficient way to transmit the 3D representation data becomes an important part in the whole 3D representation technology. Recent years, many coding schemes based on the principle of encoding the depth have been proposed. Compared to the traditional multiview coding schemes, those new proposed schemes can achieve higher compression efficiency. Due to the development of depth capturing technology, the accuracy and quality of the reconstructed depth image also get improved. In this thesis we propose an efficient depth data compression scheme for 3D images. Our proposed depth data compression scheme is platelet based coding using Lagrangian optimization, quadtree decomposition and quadratic curve fitting. We study and improve the original platelet based coding scheme and achieve a compression improvement of 1-2 dB compared to the original platelet based scheme. The experimental results illustrate the improvement provided by our scheme. The quality of the reconstructed results of our proposed curve fitting based platelet coding scheme are better than that of the original scheme.
79

Growth Curve Analysis and Change-Points Detection in Extremes

Meng, Rui 15 May 2016 (has links)
The thesis consists of two coherent projects. The first project presents the results of evaluating salinity tolerance in barley using growth curve analysis where different growth trajectories are observed within barley families. The study of salinity tolerance in plants is crucial to understanding plant growth and productivity. Because fully-automated smarthouses with conveyor systems allow non-destructive and high-throughput phenotyping of large number of plants, it is now possible to apply advanced statistical tools to analyze daily measurements and to study salinity tolerance. To compare different growth patterns of barley variates, we use functional data analysis techniques to analyze the daily projected shoot areas. In particular, we apply the curve registration method to align all the curves from the same barley family in order to summarize the family-wise features. We also illustrate how to use statistical modeling to account for spatial variation in microclimate in smarthouses and for temporal variation across runs, which is crucial for identifying traits of the barley variates. In our analysis, we show that the concentrations of sodium and potassium in leaves are negatively correlated, and their interactions are associated with the degree of salinity tolerance. The second project studies change-points detection methods in extremes when multiple time series data are available. Motived by the scientific question of whether the chances to experience extreme weather are different in different seasons of a year, we develop a change-points detection model to study changes in extremes or in the tail of a distribution. Most of existing models identify seasons from multiple yearly time series assuming a season or a change-point location remains exactly the same across years. In this work, we propose a random effect model that allows the change-point to vary from year to year, following a given distribution. Both parametric and nonparametric methods are developed for detecting single and multiple change-points, and their performance is compared by simulation studies. The proposed method is illustrated using sea surface temperature data and the tail distributions before and after the change-point from two models, with and without random effects are compared.
80

Automatická optická kontrola slícování kompletních vozidel / Automatic visual check of mating complete cars

Bureš, Jan January 2008 (has links)
This diploma thesis deals with concept of automatic inspection workplace for fitting car at assembly inspection line at TPCA as a car manufacture company. Theoretic part is focused on the assembly inspection at TPCA and also presents a current optical inspection at the industry with regard to the topic of this thesis. Practical part contains analysis of the current condition and workplace concept of automatic inspection and measuring method of complete car. Thereafter it brings the technical and economical contributions for this company when my concept implemented.

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