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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.
1

A Comparison of Multivariate Normal and Elliptical Estimation Methods in Structural Equation Models

Cheevatanarak, Suchittra 08 1900 (has links)
In the present study, parameter estimates, standard errors and chi-square statistics were compared using normal and elliptical estimation methods given three research conditions: population data contamination (10%, 20%, and 30%), sample size (100, 400, and 1000), and kurtosis (kappa =1,10, 20).
2

Estimation Methods for Determining Failure Rates of Component Families from Observed Failure Rates of Units and Yields of Component Families from Observed Yields of Units

Stitt, Lawrence Wesley 12 1900 (has links)
<p> In the field of communications electronic plug-in units operating together form a system. In the event of failure a plug-in unit can easily be replaced by another. Each unit consists of electronic components soldered onto a board in a particular pattern. A component may be either a single electronic part such as a transistor or a combination of single parts such as an integrated circuit. Electronic components with similar properties have been grouped into families. This reduces the number of parameters to be estimated from the observations available.</p> <p> The method of maximum likelihood is used to estimate the failure rates of component families. The number of unit failures and the number of units in use observed during measured periods of time and the component family makeup of the observed units are used to make the estimates.</p> <p> The probability of an electronic component from a given component from a given family being acceptable after the production process will be referred to as the component yield for that family. Similarly, the probability of a given type of unit being acceptable after the production process will be referred to as the yield for that type of unit. By taking the logarithms of the yields, the estimation problem can be reduced to the linear problem of estimating logarithms of component family yields. Using unit yields, the total number of each type of unit produced, and the component family makeup of those units produced, component family yields are estimated. The method of maximum likelihood is applied directly to the data and the method of weighted least squares is applied to the linearized problem.</p> / Thesis / Master of Science (MSc)
3

A novel method for information rich costing in CNC manufacture

Taiwo, Ayobamidele January 2013 (has links)
Reliable cost estimation is important for economic production, cost control and maintaining competitive advantage in manufacturing contract bidding. Therefore, estimating the manufacturing cost of a machined part is of critical importance in CNC manufacture. Computers aided systems the link to manufacturers CAD systems and databases have been used since the 1980’s to identify product cost and enable a company to evaluate resource utilisation. While the concept of an integrated costing system has made significant advances in integrating the design function with the cost estimation process, there are still major gaps in acquisition and application of detailed product data for generation of timely and reliable costing information feedback to engineers. Integrated costing systems are information intensive and require significant manufacturing data support. A major obstacle is the bespoke nature of the available cost relevant data and their storage in company specific database tailored to individual company practices. Thus there is need to consider standardisation of information from the design of component through to their process planning and manufacture. This will allow seamless exchange of detailed, cost relevant, information between other computers aided systems and costing systems to facilitate automatic and reliable cost information feedback. In this research a novel framework is specified and designed for enabling detailed product information that exists across CNC manufacturing, to be utilised for generation of reliable cost estimates. The standards based costing proposed in this thesis framework facilitates high-level integration of various CAx resources and increases the availability of product creation process (PCP) data that are applicable in costing process. A prototype implementation of the unified costing framework is utilised to demonstrate the capabilities of the framework. The demonstration is conducted using two industrially inspired prismatic test components where the components machining cycles were timed with a stop watch and the actual result compared with the prototype system estimated result to determine its reliability. The research shows that implementation of manufacturing standard that contain structured representation PCP information together with an effective data retrieval mechanism and computational algorithms can provide a standard compliant framework to realise an information rich (detailed) costing system. The potential of the proposed framework is not limited to enabling the use of detailed information that exist within manufacturing facility to generate cost information; it also provides a standard compliant approach for the development of future generations of costing systems.
4

Variabilidade espacial do solo em sistema plantio direto estabilizado / Spatial variability of soil in stabilized direct planting system

Duarte, Sara de Jesus 10 April 2015 (has links)
A homogeneidade do solo em sistema de plantio direto, é um assunto questionável, pois alguns autores têm considerado que, com o passar do tempo, há aumento da homogeneidade do solo, outros têm verificado a redução. A hipótese deste trabalho é que em sistema de plantio direto consolidado existe correlação e dependência espacial dos atributos físicos-hídrico do solo e do desenvolvimento vegetativo da soja, sendo a cokrigagem colocalizada interpolador mais representativo destas correlações. O objetivo foi avaliar a variabilidade espacial de atributos físicos do solo e do desenvolvimento vegetativo da soja em sistema de plantio direto, adotado há mais de 19 anos. O trabalho foi desenvolvido na fazenda-escola da Universidade Estadual de Ponta Grossa - Paraná. A área de estudo tem como cultura a soja e está inserida em um relevo cuja declividade máxima, no sentido da pendente, é de aproximadamente 10 %. Nesta área, foram avaliados atributos físicos e hídrico do solo, como: densidade do solo (Ds), granulometria (areia e argila) e condutividade hidráulica saturada (Kfs). Avaliou-se, ainda, atributos de planta: altura da planta, estádio reprodutivo e stand. Para tais avaliações, foi demarcado um grid com espaçamento 10 x 10 metros, onde as avaliações foram realizadas em cada ponto. A análise dos dados foi efetuada por geoestatística, utilizando o pacote de programas GEOSTAT, para todas as variáveis que apresentaram dependência espacial. Foi obtido mapa de krigagem, e para todas as que apresentaram correlação, mapas de cokrigagem e cokrigagem colocalizada. A precisão de tais mapas foi obtida por meio dos menores valores de variância e a raiz quadrada do erro médio (RMSE). Verificou-se existência de dependência espacial na área em estudo, sendo a declividade um dos fatores responsáveis pela variação e o outro fator pode ser atribuído ao manejo uniforme adotado na área. Existiu correlação direta e positiva entre Kfs e areia e negativa com argila. Os atributos que influenciaram positivamente o desenvolvimento da planta foram a Kfs e, negativamente, a densidade do solo (Ds). Quanto aos métodos de estimação, o que obteve o mapa mais representativo da condição real, para a maioria das variáveis estudadas, foi a cokrigagem colocalizada. Apenas para a correlação argila x areia não houve ganho no uso da cokrigagem colocalizada, por isso, a cokrigagem ordinária foi a mais indicada. / The homogeneity of the soil in no-tilled system is being a highly controversial question, as some authors have claimed that there is an increasing in the soil homogeneity over time, while others have proven it to be reduced. The hypothesis is that in established no-tillage system is no correlation and spatial dependence of the physical-hydric soil properties and soybean vegetative development, cokriging-located interpolator being most representative of these correlations The objective was to evaluate the spatial variability of the soil physical attributes and soybean vegetative growth along 19-years of no-tillage system. The study was carried out at the farm-school from the Universidade Estadual de Ponta Grossa - Paraná. The area was cultivated with soybean in a topossequence with a maximum slope of10 %. In this area, were evaluated physical and hydrical soil properties, e.g. soil bulk density (Ds), soil texture (sand and clay) and saturated hydraulic conductivity (Kfs). It was also evaluated plant characteristics such as plant height, reproductive stage and standFor these assessments, it was delimited a 10 x 10 meters grid, where the assessments were carried out in each point. The data analysis was performed using a specific geostatistic software GEOSTAT, for all spatial-dependent variables. A kriging map was obtained from the results, and for all those correlated variables cokriging maps and cokriging-located have been also performed. The maps accuracy were achieved from the smallest values of variance and square root of the mean error (RMSE). The results indicated the existence of spatial dependence in the study area with the slope and soil management the mainly dependent factors, wherein in the latter the spatial variability is disregarded. Kfs was direct and positively correlated with sand, and a negatively with clay. The soil attribute that influenced positively the plant development was Kfs, whilst the bulk density (Ds) influenced negatively. With regard to the estimative methods, cokriging-located produced the most accurate and representative map of the real conditions for most of the variables. The low correlation between sandy and clay fractions makes the ordinary cokriging is being more appropiate than the cokriging-located.
5

Métodos da máxima verossimilhança e máxima verossimilhança restrita na estimação de parâmetros do modelo de variabilidade espacial

Simonato, Karin Luciano Brizola 17 December 2009 (has links)
Made available in DSpace on 2017-07-10T19:24:47Z (GMT). No. of bitstreams: 1 Karin Simonato.pdf: 773791 bytes, checksum: 926da058b64b38776604ccf6ba8e2c2f (MD5) Previous issue date: 2009-12-17 / The objective of this paper is the construction of thematic maps of the soil chemical properties and soybean productivity of an area located in the West of Parana State, in the city of Cascavel, where 83 samples of 12 parameters of chemical properties of soil and productivity were collected. It was also performed the exploratory analysis of the collected data and spatial analysis to estimate parameters through the maximum likelihood and restricted maximum likelihood methods, and, subsequently, the construction of thematic maps of these properties took place, using the two methods. The methods are validated by the method of cross validation, so that one can choose the most suitable for constructing the map of the variables studied. Through the maps, we have the history of the property where the data were collected and allows analysis and should help the making of decisions by the producer. / O presente trabalho teve como objetivo a construção de mapas temáticos das propriedades químicas do solo e da produtividade de soja de uma área localizada no oeste do Paraná, no município de Cascavel, onde foram coletadas 83 amostras de 12 parâmetros de propriedades químicas do solo e um de produtividade. Foram realizadas a análise exploratória dos dados amostrados e posteriormente a análise espacial, para que fosse possível estimar parâmetros através dos métodos de máxima verossimilhança e máxima verossimilhança restrita e, posteriormente, se fez a construção dos mapas temáticos de cada uma das propriedades, através do método mais adequado. Os métodos foram validados pelo método da validação cruzada. Através dos mapas, temos o histórico da propriedade onde foram coletados os dados e, assim, se podem fazer análises para a tomada de decisões por parte do produtor.
6

Métodos da máxima verossimilhança e máxima verossimilhança restrita na estimação de parâmetros do modelo de variabilidade espacial

Simonato, Karin Luciano Brizola 17 December 2009 (has links)
Made available in DSpace on 2017-05-12T14:48:10Z (GMT). No. of bitstreams: 1 Karin Simonato.pdf: 773791 bytes, checksum: 926da058b64b38776604ccf6ba8e2c2f (MD5) Previous issue date: 2009-12-17 / The objective of this paper is the construction of thematic maps of the soil chemical properties and soybean productivity of an area located in the West of Parana State, in the city of Cascavel, where 83 samples of 12 parameters of chemical properties of soil and productivity were collected. It was also performed the exploratory analysis of the collected data and spatial analysis to estimate parameters through the maximum likelihood and restricted maximum likelihood methods, and, subsequently, the construction of thematic maps of these properties took place, using the two methods. The methods are validated by the method of cross validation, so that one can choose the most suitable for constructing the map of the variables studied. Through the maps, we have the history of the property where the data were collected and allows analysis and should help the making of decisions by the producer. / O presente trabalho teve como objetivo a construção de mapas temáticos das propriedades químicas do solo e da produtividade de soja de uma área localizada no oeste do Paraná, no município de Cascavel, onde foram coletadas 83 amostras de 12 parâmetros de propriedades químicas do solo e um de produtividade. Foram realizadas a análise exploratória dos dados amostrados e posteriormente a análise espacial, para que fosse possível estimar parâmetros através dos métodos de máxima verossimilhança e máxima verossimilhança restrita e, posteriormente, se fez a construção dos mapas temáticos de cada uma das propriedades, através do método mais adequado. Os métodos foram validados pelo método da validação cruzada. Através dos mapas, temos o histórico da propriedade onde foram coletados os dados e, assim, se podem fazer análises para a tomada de decisões por parte do produtor.
7

Global Positioning in Harsh Environments

Resch, Bernd, Romirer-Maierhofer, Peter January 2005 (has links)
<p>As global location systems offer only restricted availability, they are not suitable for a world- </p><p>wide tracking application without extensions. This thesis contains a goods-tracking solution, </p><p>which can be considered globally working in contrast to formerly developed technologies. For </p><p>the creation of an innovative approach, an evaluation of the previous efforts has to be made. </p><p>As a result of this assessment, a newly developed solution is presented in this thesis that uses </p><p>the Global Positioning System (GPS) in connection with the database correlation method </p><p>involving Global System for Mobile Communications (GSM) fingerprints. The database </p><p>entries are generated automatically by measuring numerous GSM parameters such as Cell </p><p>Identity and signal strength involving handsets of several different providers and the real </p><p>reference position obtained via a high sensitivity GPS receiver.</p>
8

Parameter estimation methods based on binary observations - Application to Micro-Electromechanical Systems (MEMS)

Jafaridinani, Kian 09 July 2012 (has links) (PDF)
While the characteristic dimensions of electronic systems scale down to micro- or nano-world, their performance is greatly influenced. Micro-fabrication process or variations of the operating situation such as temperature, humidity or pressure are usual cause of dispersion. Therefore, it seems essential to co-integrate self-testing or self-adjustment routines for these microdevices. For this feature, most existing system parameter estimation methods are based on the implementation of high-resolution digital measurements of the system's output. Thus, long design time and large silicon areas are needed, which increases the cost of the micro-fabricated devices. The parameter estimation problems based on binary outputs can be introduced as alternative self-test identification methods, requiring only a 1-bit Analog-to-Digital Converter (ADC) and a 1-bit Digital-to-Analog Converter (DAC).In this thesis, we propose a novel recursive identification method to the problem of system parameter estimation from binary observations. An online identification algorithm with low-storage requirements and small computational complexity is derived. We prove the asymptotic convergence of this method under some assumptions. We show by Monte Carlo simulations that these assumptions do not necessarily have to be met in practice in order to obtain an appropriate performance of the method. Furthermore, we present the first experimental application of this method dedicated to the self-test of integrated micro-electro-mechanical systems (MEMS). The proposed online Built-In Self-Test method is very amenable to integration for the self-testing of systems relying on resistive sensors and actuators, because it requires low memory storage, only a 1-bit ADC and a 1-bit DAC which can be easily implemented in a small silicon area with minimal energy consumption.
9

Global Positioning in Harsh Environments

Resch, Bernd, Romirer-Maierhofer, Peter January 2005 (has links)
As global location systems offer only restricted availability, they are not suitable for a world- wide tracking application without extensions. This thesis contains a goods-tracking solution, which can be considered globally working in contrast to formerly developed technologies. For the creation of an innovative approach, an evaluation of the previous efforts has to be made. As a result of this assessment, a newly developed solution is presented in this thesis that uses the Global Positioning System (GPS) in connection with the database correlation method involving Global System for Mobile Communications (GSM) fingerprints. The database entries are generated automatically by measuring numerous GSM parameters such as Cell Identity and signal strength involving handsets of several different providers and the real reference position obtained via a high sensitivity GPS receiver.
10

Atsargų valdymo strategija / Strategy of inventory management

Urlikienė, Renata 04 February 2009 (has links)
Finansų rinkų programos Verslo nuosavybės ekonomikos specializacijos magistro baigiamojo darbo tema yra aktuali, nes atsargų valdymas, efektyvus atsargų valdymo proceso organizavimas yra aktualus kiekvienai įmonei, užsiimančiai gamybine ar prekybine veikla. Atsargos – vienas iš įmonės veiksnių jos pelningai veiklai palaikyti. Atsargų valdymas yra jų optimalaus kiekio paieška bei tinkamiausio santykio tarp naudos ir išlaidų išlaikymas. Tyrimo objektas – atsargų valdymas. Pagrindinis šio darbo tikslas – nustatyti, kokia įtaką įmonės pelningumui daro efektyvus atsargų valdymas. Tikslui pasiekti buvo iškelti šie uždaviniai: 1. susipažinti su atsargų rūšimis; 2. atsargų poreikio nustatymas; 3. apibrėžti pagrindinius atsargų įkainojimo metodus; 4. atlikti atsargų panaudojimo efektyvumo analizę. Tyrimo metodika. Darbe naudota mokslinės, ekonominės literatūros analizė apie atsargų valdymą ir su juo susijusias problemas, turto panaudojimo efektyvumo koeficientų analizė. Šiuo darbu norime pagrįsti hipotezę, kad efektyvus atsargų valdymas padidintų įmonės pinigų srautus, kas leistų juos panaudoti verslo plėtrai ar veiklos procesų efektyvumui gerinti. Pirmoje darbo dalyje išanalizavime, kas tai yra atsargos, išnagrinėjome atsargų rūšis ir jų klasifikavimą. Atsargos – trumpalaikis turtas (žaliavos ir komplektavimo gaminiai, nebaigta gamyba, pagamint produkcija bei pirktos prekės, skirtos perparduoti), kurį įmonė sunaudoja pajamoms uždirbti per vienus metus arba per vieną įmonės... [toliau žr. visą tekstą] / Master‘s work in business property economics is actual, because the inventory management, the effective inventory organizing is actual for each producing and trade company. Inventory is one from the most important factors for profitable activity of company. Inventory management is the most suitable relation between the profit and expenses. The object is inventory management. The aim of this article is to research the effective inventory management influence for company’s profitableness. To reach this goal we resolved such tasks as: 1. Become acquainted with qualities of inventory; 2. To define the basic estimation methods; 3. To carry out the analyze of the effective inventory employment. In this article we want to ground the hypothesis that effective inventory management increase profit of company. In the first part we have analyzed the inventory qualities and classification. Inventory is the short-term assets (raw materials and consumables, work in progress, finished products and goods for resale), which company used for receipts earn during one year. Raw materials and consumables, work in progress and finished products are the inventory of producing company. And the goods for resale are the inventory of trade company. In the second part we analyzed the basic estimation methods. The choosing of the estimation methods is one from the most important factors for profitable activity of company, which could influence the sale cost price. For the calculating of used in production... [to full text]

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