31 |
Identification and Adaptive Control of a Coordinate Measuring MachinePettersson, Ulf January 2004 (has links)
<p>Important factors in manufacturing are quality and cost. Measuring machines play an important role for these fields. In order to meet higher demands on cost and accuracy, measuring machines can be constructed with weaker materials and increased mechanical flexibilities, and therefore there is a need to include the flexibilities in measuring machine models to obtain good performance. </p><p>The core theme in this thesis is modeling and idenfication of the physical parameters of drive mechanisms of a Brown&Sharpe Inc. Global A coordinate measuring machine. The approximation made is that the drive mechanisms can be described by a mass connected by springs, dampers and gear changes. It has been found that a one-spring model gives a reasonably good description of the studied CMM drive mechanism. The physical parameters of this model are identified using off-line algorithms. The algorithms are based on prediction error methods. For the off-line identification the MATLAB System Identification Toolbox and the bond graph representation is used. </p><p>The chosen model is then used for control. Traditional control and a Model-reference Adaptive System is derived and studied with the aim to increase the damping of CMM drive mechanisms. It is found that the adaptive system has very good disturbance rejection and can correct for drastic model errors. Another impact is that the damping of the studied drive mechanism can be increased with at least a factor of nine.</p>
|
32 |
Identification and Adaptive Control of a Coordinate Measuring MachinePettersson, Ulf January 2004 (has links)
Important factors in manufacturing are quality and cost. Measuring machines play an important role for these fields. In order to meet higher demands on cost and accuracy, measuring machines can be constructed with weaker materials and increased mechanical flexibilities, and therefore there is a need to include the flexibilities in measuring machine models to obtain good performance. The core theme in this thesis is modeling and idenfication of the physical parameters of drive mechanisms of a Brown&Sharpe Inc. Global A coordinate measuring machine. The approximation made is that the drive mechanisms can be described by a mass connected by springs, dampers and gear changes. It has been found that a one-spring model gives a reasonably good description of the studied CMM drive mechanism. The physical parameters of this model are identified using off-line algorithms. The algorithms are based on prediction error methods. For the off-line identification the MATLAB System Identification Toolbox and the bond graph representation is used. The chosen model is then used for control. Traditional control and a Model-reference Adaptive System is derived and studied with the aim to increase the damping of CMM drive mechanisms. It is found that the adaptive system has very good disturbance rejection and can correct for drastic model errors. Another impact is that the damping of the studied drive mechanism can be increased with at least a factor of nine.
|
33 |
Optimización de los procesos de tecnologías de información en un terminal marítimoVargas Vilchez, Victor Loel, Gómez Condori, Christian Franklin 19 March 2013 (has links)
No description available.
|
34 |
Implementación del nivel II del CMMIAntón Calvay, Hernán Aarón, Carbajal Valverde, Jorge Luis 19 March 2013 (has links)
No description available.
|
35 |
Implementación del nivel 1 y 2 del MoProSoft en Net FactoryZumaeta Liza, Helen Fiorela 19 March 2013 (has links)
No description available.
|
36 |
Application Of Statistical Process Control To Software Development Processes Via Control ChartsSargut, Kamil Umut 01 January 2003 (has links) (PDF)
The application of Statistical Process Control (SPC) to software processes has
been a challenging issue for software engineers and researchers. Although SPC is
suggested for providing process control and achieving higher process maturity
levels, there are very few resources that describe success stories, implementation
details, and implemented guidelines for applying SPC to specific metrics.
In this thesis the findings of a case study that is performed for investigating the
applicability of SPC to software metrics in an emergent CMM Level 3 software
organization are presented. As being one of the basic and most sophisticated tools
of SPC, control charts are used for the analysis. The difficulties in application of
Statistical Process Control to a CMM Level 3 organization are observed by using
the existing data of defect density, rework percentage, productivity and review
performance metrics and relevant suggestions are provided for dealing with them.
Finally the analysis results are summarized and a guideline is prepared for
software companies who want to utilize control charts by using their existing
metric data.
|
37 |
Standardization of CMM Algorithms and Development of Inspection Maps for Geometric TolerancesJanuary 2011 (has links)
abstract: The essence of this research is the reconciliation and standardization of feature fitting algorithms used in Coordinate Measuring Machine (CMM) software and the development of Inspection Maps (i-Maps) for representing geometric tolerances in the inspection stage based on these standardized algorithms. The i-Map is a hypothetical point-space that represents the substitute feature evaluated for an actual part in the inspection stage. The first step in this research is to investigate the algorithms used for evaluating substitute features in current CMM software. For this, a survey of feature fitting algorithms available in the literature was performed and then a case study was done to reverse engineer the feature fitting algorithms used in commercial CMM software. The experiments proved that algorithms based on least squares technique are mostly used for GD&T; inspection and this wrong choice of fitting algorithm results in errors and deficiency in the inspection process. Based on the results, a standardization of fitting algorithms is proposed in light of the definition provided in the ASME Y14.5 standard and an interpretation of manual inspection practices. Standardized algorithms for evaluating substitute features from CMM data, consistent with the ASME Y14.5 standard and manual inspection practices for each tolerance type applicable to planar features are developed. Second, these standardized algorithms developed for substitute feature fitting are then used to develop i-Maps for size, orientation and flatness tolerances that apply to their respective feature types. Third, a methodology for Statistical Process Control (SPC) using the I-Maps is proposed by direct fitting of i-Maps into the parent T-Maps. Different methods of computing i-Maps, namely, finding mean, computing the convex hull and principal component analysis are explored. The control limits for the process are derived from inspection samples and a framework for statistical control of the process is developed. This also includes computation of basic SPC and process capability metrics. / Dissertation/Thesis / M.S. Mechanical Engineering 2011
|
38 |
Decomposição de coeficientes trigonométricos para a redução de área e potência em arquiteturas FFT híbridas na base 2 / Trigonometric coefficients decomposition for area and power reduction in hybrid radix-2 FFT architecturesGhissoni, Sidinei January 2012 (has links)
A crescente utilização de equipamentos móveis que empregam a transformada rápida de Fourier (FFT) nas operações de sinal digital pode ter seu uso restrito devido ao comprometimento da durabilidade da bateria e de suas dimensões. Estas possíveis limitações de uso fazem crescer a necessidade do desenvolvimento de técnicas que visam à otimização nos três requisitos básicos de projeto digital: dissipação de potência, área e atraso. Para tanto, é abordado neste trabalho um método que realiza a implementação de arquiteturas FFT com ênfase na otimização através da decomposição dos coeficientes trigonométricos. No cálculo da FFT, as borboletas desempenham um papel central, uma vez que permitem o cálculo de termos complexos. Neste cálculo, que envolve multiplicações dos dados de entrada com coeficientes trigonométricos apropriados, a otimização das borboletas pode contribuir diretamente para a redução de potência e área. Na técnica proposta são analisados quais são os coeficientes trigonométricos existentes na arquitetura FFT utilizada como base e a escolha para decomposição será o que apresentar o menor custo de implementação em hardware. A decomposição de um coeficiente deve garantir a reconstituição de todos os demais coeficientes necessários para a implementação de toda a arquitetura FFT. Assim, a decomposição diminui o número de coeficientes necessários para reconstruir a FFT original. O conjunto dos novos coeficientes gerados são implementados com apenas somadores\subtratores e deslocamentos através de Multiplicação de Matrizes Constantes (CMM – Constant Matrix Multiplication), associados a um sistema de controle com multiplexadores que controlam o caminho para a correta operação da FFT. As implementações dos circuitos somadores/subtratores são realizadas com métrica no nível de portas lógicas, visando menor atraso e dissipação de potência para topologias com somadores dos tipos CSA (Carry Save Adder) e Ripple carry. Os resultados apresentados pelo método proposto, quando comparados com soluções da literatura, são significativamente satisfatórios, pois minimizaram a dissipação de potência e área em 30% e 24% respectivamente. Os resultados apresentam também a redução de componentes somadores necessários para a implementação de arquiteturas FFTs. / The increasing use of mobile devices using the Fast Fourier Transform (FFT) operations in digital signal may have its use restricted due compromising the durability of the battery and its dimensions. These possible limitations on usage makes grow the need to develop techniques aimed at optimizing the three basic requirements of digital design: power dissipation, area and delay. Therefore, this thesis discusses a method that performs the FFT implementation of architectures with emphasis on optimization through decomposition of twiddle factors (trigonometric coefficients). In the FFT the butterflies play a key role, since it allows the computation of complex terms. In this calculation, which involves multiplications of input data with appropriate twiddle factors, optimization of the butterflies can contribute directly to the reduction in power and area. In the proposed technique are analyzed what are the twiddle factors existing in FFT architecture used as a basis and to choose the decomposition that provide the lowest cost hardware implementation. The decomposition of coefficient to must ensure the rebuilding of all the other twiddle factors necessary for the implementation of the architecture FFT. Thus, the decomposition decreases the number of twiddle factors needed to reconstruct the original FFT. The new sets of coefficients generated are implemented with only adders\subtracters and shifting through of Constants Matrix Multiplication (CMM). A control system of multiplexers makes the way for the correct operation of the FFT. The implementations of the circuits arithmetic adders/subtracters are performed at the gate level, seeking lower delay and power consumption for topologies with adders types of CSA (Carry Save Adder) and Ripple carry. The results presented by the proposed method, compared with literature solutions are significantly satisfactory, since minimized power dissipation and area as well as reduced component adders required for implementation architectures FFTs.
|
39 |
O impacto do cmm / cmmi na qualidade do software: um estudo sobre a percepção dos profissionais de ticSousa, Sandra Cristina Catarino January 2009 (has links)
p. 1 - 119 / Submitted by Santiago Fabio (fabio.ssantiago@hotmail.com) on 2013-01-16T21:07:26Z
No. of bitstreams: 1
ddddddd88.pdf: 358295 bytes, checksum: 08b0fc127bbc330b70652af8ce82b292 (MD5) / Made available in DSpace on 2013-01-16T21:07:26Z (GMT). No. of bitstreams: 1
ddddddd88.pdf: 358295 bytes, checksum: 08b0fc127bbc330b70652af8ce82b292 (MD5)
Previous issue date: 2009 / Diante de diversos estudos que relacionam a qualidade do software à qualidade do
processo que o gera e da crescente pressão do mercado de TIC (Tecnologia da
Informação e Comunicação) pela criação de produtos qualidade com prazos e
custos cada vez menores, as empresas produtoras de software passaram a investir
na utilização de processos no desenvolvimento de softwares. Diversos padrões e
modelos de qualidade foram criados e difundidos com foco na definição de
processos, dentre eles os modelos de maturidade da capacidade CMM (Capability
Maturity Model) e CMMI (Capability Maturity Model Integration), criados pelo SEI
(Software Engineering Institute), que tiveram uma grande aceitação mundial. Em
face desta realidade, a SUNAC/SDR (Superintendência de Negócio, Administração
Tributária e Comércio Exterior/Salvador), regional do SERPRO (Serviço Federal de
Processamento de Dados), conquistou em 2003 o nível dois do CMM e desde então
trabalha no aperfeiçoamento do processo de desenvolvimento de software para
atingir níveis superiores do modelo CMMI. A presente pesquisa explicita a percepção
dos profissionais da SUNAC/SDR, que trabalharam nesta unidade no intervalo de
]2003 - 2008], sobre como a utilização dos modelos CMM / CMMI afeta a qualidade
dos produtos gerados ao longo do ciclo de vida de desenvolvimento de software.
Verificou-se que os profissionais perceberam a importância de utilizar um processo
de desenvolvimento para a melhoria dos produtos gerados. Além disso, perceberam
que houve melhoria nos produtos desenvolvidos por eles e também no produto final
entregue ao cliente após a implantação do processo. / Salvador
|
40 |
Development towards a focus variation based micro-co-ordinate measuring machineHiersemenzel, Florine January 2014 (has links)
The increasing number of small and fragile parts that are being manufactured using micromachining technology has raised the demand for co-ordinate measurement machines (CMM) that can measure on a micro- and millimetric scale without contacting the part, thus avoiding damage to the surface of the part. These instruments are expected to measure on a micro- and millimetric scale with a measuring uncertainty in the nanometre range. A number of techniques used for contactless surface measurements exist, such as the focus variation (FV) technique, which have the ability to perform measurements on the micro- and millimetric scale in a short amount of time. These instruments may have the potential to be implemented in a non-contact micro-CMM platform.
|
Page generated in 0.042 seconds