Dissertations / Theses on the topic 'Estimation of connection'

This work presents different novel gate drive unit (GDU) concepts for IGBT and reverse conducting IGBT (RC-IGBT). They have been experimentally tested with medium voltage class IGBT modules (1200...1700V/650…1400A) and a RC-IGBT module (1200V/200A). The switching behaviour of the RC-IGBT was investigated, and a new trigger pulse pattern to drive the RC-IGBT was developed, designed and implemented. The experimental results showed that the switching losses were reduced by 20% in the RC-IGBT compared to the switching losses of a standard diode. Two novel schemes are introduced to estimate the collector current through the IGBT, based on the measurement of the voltage across the internal stray inductance of the IGBT module. Furthermore, a GDU concept was derived to balance the on-state collector currents of parallel-connected IGBTs, reducing the current imbalance to 5%. Also, a new fast short circuit protection method (FSCP) for IGBT modules was developed, designed and implemented in another GDU, allowing turning-off the considered IGBT in less than 1μs, reducing the IGBT stress. Another scheme implemented in a GDU features an improved gate current switching profile of the IGBT, which reduces the switching losses by 25% compared to the standard switching method. In order to reduce the conduction losses, a GDU with an increased turn-on gate-emitter voltage (larger than 20 V) was investigated. In the investigated IGBT, the on-state losses were reduced by 18% when a gate-emitter voltage of 35V is used compared to when a gate-emitter voltage of 15V is used. All these new GDU concepts have been implemented with a simple and inexpensive electronic circuitry, which is an important feature for a possible industrial implementation.

Complex systems composed of many substructures include various structural joints connecting the substructures together. These mechanical connections play a significant role in predicting the dynamic characteristics of the assembled systems accurately. Therefore, equivalent dynamic models of joints that consist of stiffness and damping elements should be developed and the joint parameters should be determined for an accurate vibration analysis. Since it is difficult to estimate joint parameters accurately by using a pure analytical approach, it is a general practice to use experimental measurements to model joints connecting substructures. In this study an experimental identification method is suggested. In this approach the frequency response functions (FRFs) of substructures and the coupled structure are measured and FRF decoupling method is used to identify equivalent dynamic characteristics of bolted joints. Since rotational degrees of freedom (RDOF) in connection dynamics is very important, a structural joint is modeled with translational, rotational and cross-coupling stiffness and damping terms. FRF synthesis and finite-difference formulations are used for the estimation of unmeasured FRFs and RDOF related FRFs, respectively. The validity and application of the proposed method are demonstrated both numerically and experimentally. In simulation studies, simulated experimental values are used, and it is seen that the identification results are prone to high errors due to noise in measurement and the matrix inversions in the identification equations. In order to reduce the effect of noise, it is proposed to extract the joint properties by taking the average of the results obtained at several frequencies in the frequency regions sensitive to joint parameters. Yet, it is observed in practical applications that experimental errors combine with the measurement noise and the identification results still may not be so accurate. In order to solve this problem, an update algorithm is developed. In the approach proposed, the identified dynamic parameters are used as initial estimates and then optimum dynamic parameters representing the joint are obtained by using an optimization algorithm. The application of the proposed method is performed on a bolted assembly. It is shown with experimental studies that this method is very successful in identifying bolted joint parameters. The accuracy and applicability of the identification method suggested are illustrated by using a dynamically identified bolt in a new structure, and showing that the calculated FRFs in which identified joint parameters are used, match perfectly with the measured ones for the new structure. In this study, the effects of bolt size and quality of bolts, as well as the bolt torque on the joint properties are also studied by making a series of experiments and identifying the joint parameters for each case.

碩士<br>國立高雄第一科技大學<br>營建工程所<br>93<br>The sewer system is an important infrastructure for a modern country, and is evaluated as a critical index of world competitiveness in the international society. Sewer House Connection Construction (SHCC) plays an important role in the whole sewer system construction. It is found that there is almost no scheduling and planning work for the SHCC at all. To effectively estimate the construction duration of each alley, the basic productivity influencing factors and parameters have to be estimated first. The SHCC of 28 streets within the region of the 2nd Cannel of Kaohsiung city was selected as the subject to be observed and analyzed in this research. After several site visits the data were collected for different activities. Then the different data were converted to the final productivity that can be compared universally. The daily productivity and diaries was analyzed to explore the productivity influence factors of SHCC. Three conclusions of this research are listed as follows. 1. Productivity of front-lane: 0.18 wh/m3 (excavation); 3.12 wh/ea (hidden well); 3.08 wh/ea (connection-pipe); 0.28 wh/m (asphalt); 1.16 wh/m (formwork); 0.39 wh/m (grouting);1.03 wh/m (remove shoring). 2. Productivity of back-lane: 2.64 wh/m (bury-pipe); 2.01 wh/ea (connection-pipe); 2.02 wh/m (formwork); 0.76 wh/m (grouting); 0.67 wh/m (remove shoring). 3. Influence factors: most of them is related to environmental constrain, ex. Geology, width, illegal building…etc. Further studies on the work unit rate and conversion factor of household connection-pipe are needed to improve the model.

碩士<br>國立臺灣科技大學<br>電機工程系<br>106<br>At the end of digital integrated circuit (IC) design flow, some nets may still be left open due to engineering change order (ECO). Resolving these opens could be quite challenging for some huge nets such as power ground nets because of a large number of obstacles and greatly distributed net components. Existing studies on multilayer obstacle-avoiding rectilinear Steiner trees may not be applicable to solve this problem because they assume the pins of an input net is a set of points, while the discrete net components in this problem can be regarded as a set of rectilinear pins. In this thesis, we develop an efficient open-net connector that can deal with rectilinear pins. The proposed algorithm flow minimizes the total connection cost based on precise estimation of the shortest distance between each pair of rectilinear net components with the presence of complex obstacles. Experimental results show that the proposed flow can outperform the top three teams of 2017 CAD Contest at ICCAD in terms of total connection cost or runtime efficiency.

碩士<br>國立臺北科技大學<br>製造科技研究所<br>97<br>In recent years, electronic products are in the trend of tiny and light weight. Therefore, the design space of the connector is becoming restricted. Geometric shapes of springs become more complicated and increase the difficulty of design and fatigue life analysis. Therefore, the purpose of this study is to study the stress distribution and fatigue life of such kind of connector springs. Commercial finite element software (ABAQUS) is used to analyze the stress and deformation responses and the stress life theory including mean stress effect like the Soderberg and Goodman equations are used to estimate the fatigue life of the connector springs designed. In this case study, stress and force analyses of the springs had been performed under three different compressive displacement of interest. And the normal forces obtained from analyses have a good agreement with those obtained from force–displacement tester used in industry. For fatigue life calculation, the results also show that the fatigue lives of springs under three different loadings from the Soderberg equation are within a factor of 0.45~0.81 compared to those obtained from experimental test. And the fatigue lives from Goodman equations are within a factor of 0.91~2.27. Therefore, in this case study, it is evident that fatigue life prediction from the Soderberg equation yields better results than the Goodman equations.

碩士<br>國立高雄第一科技大學<br>營建工程所<br>97<br>Estimating productivity of household connection activities is according to a multiple regression model nowadays. However, there are two shortcomings as follow: (1) The accuracy of linear equation does not perform algorithms as the non-linear one. (2) Using reaching 12 linear equations to estimate productivity of household connection is too complicated. In short, the purpose of this research is to develop one kind of neural network model in order to estimate productivity of household connection. This research describes a statistical model developed to forecast the productivity of household connection activities. The model is a non-linear multiple regression model, developed by observed and interviewed information on-site. Model coefficients in regard to influencing factors, and have set up six kinds of models of household connection productivity. The productivity of each type of household connection are: (1) Productivity of front-lane excavation is 0.95( wh/m). (2) Productivity of back-lane excavation is 2.48 (wh/m3). (3) Productivity of front-lane connection-pipe is 1.89 (wh/unit). (4) Productivity of back-lane connection-pipe is 0.61(wh/unit). (5) Productivity of front-lane recovery is 0.10 (wh/m). (6) Productivity of back-lane recovery is 0.17 (wh/m).

Tesis (Doctor en Matemática)--Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física, 2011.<br>En esta tesis se proponen principalmente dos tipos de aplicaciones biomédicas para las cuales hemos empleado diferentes herramientas matemáticas y por lo cual el trabajo está dividido en dos partes. En la primera parte nos hemos abocado a la detección de tumores. El objetivo aquí fue estimar la localización, tamaño y parámetros térmicos asociados a un tumor utilizando como información perfiles de temperaturas medidos sobre la superficie corporal. En la segunda parte del trabajo, el objetivo fue desarrollar un algoritmo capaz de extraer, de una gran base de datos, información que reside de manera implícita en estos. Dicha información es previamente desconocida y puede resultar útil para describir el proceso o fenómeno que está bajo análisis o estudio. En particular, aquí se aplicó para la clasificación de distintos tipos de tumores usando como base de datos niveles de expresión genética.<br>In this thesis we propose two main areas of study, so the work is divided into two parts. The first one is related with tumor location and estimation of parameters related with tumor regions and the second part is concerned with the development of an algorithm for tumor classification from gene expression levels. In the first situation the goal is to estimate position, size and thermal parameters of a tumor using temperature profiles that have been measured on the top boundary of the domain using a thermography camera. From the mathematical point of view the study of these problems imply to pose and analyze inverse problems and also to develop numerical methods to solve it. In a first stage, we use partial differential equations to model heat transfer in living tissue, more precisely we consider the stationary Pennes equation with mixed boundary conditions. For this elliptical equation we have proved existence and uniqueness of the solution and to solve this direct problem a finite difference scheme of second order is considered. Then, to solve the inverse problems these problems were reformulated as optimization problems and to solve these new problems two different methodologies will be presented. The first one, is based on the use of the Patter Search algorithm. This is a direct search algorithm, so it does not make use of derivatives and therefore is very easy to implement. The second methodology that we present makes use of the information provided by the derivative of the function to minimize with respect to the different variables to be estimated. To calculate this derivative we consider some sensitivity analysis tools. In the second part of the work, the goal is to build an algorithm capable to extract, from a large database, useful information that resides implicitly. This information is previously unknown and may be useful to describe the process or phenomenon that is under analysis or study. In particular, here we are interested in classify different types of tumors using gene expression levels. The proposed methodology is based on three main ingredients: 1)the blurring of distinctions between training and testing populations, through the soft assignment of the latter to classes, in an expectation-maximization framework, 2) a procedure for density estimation through a descent flow, that transforms the original distribution into an isotropic Gaussian distribution and 3) a measure of the clustering capability of a set of variables, which leads to an effective procedure for variable selection. The methodology is particularly useful in situations where there are relatively few observations for a phenomenon that is described by a large amount of variables, and no a priori knowledge that strongly links a small subset of these variables to the classification sought. According to the results obtained the methodologies proposed in the first part of this work can be considered as a potential tool to locate tumor regions, like nodular melanomas, as well as to estimate parameters associated with them that could be useful and important to study the tumor evolution after a treatment procedure. The same conclusion applies to the methodology developed in the second part in order to diagnose, prevent and treat different diseases based on gene expression levels.<br>Juan Pablo Agnelli.<br>Estimación de parámetros asociados a tumores -- Modelo matemático -- Problemas inversos -- Introducción al análisis de sensibilidad -- Clasificación y agrupamiento de datos -- Estimación de densidades -- Elección de varialbes y evaluación del agrupamiento -- Ejemplos clínicos : clasificación de tumores.

This work presents different novel gate drive unit (GDU) concepts for IGBT and reverse conducting IGBT (RC-IGBT). They have been experimentally tested with medium voltage class IGBT modules (1200...1700V/650…1400A) and a RC-IGBT module (1200V/200A). The switching behaviour of the RC-IGBT was investigated, and a new trigger pulse pattern to drive the RC-IGBT was developed, designed and implemented. The experimental results showed that the switching losses were reduced by 20% in the RC-IGBT compared to the switching losses of a standard diode. Two novel schemes are introduced to estimate the collector current through the IGBT, based on the measurement of the voltage across the internal stray inductance of the IGBT module. Furthermore, a GDU concept was derived to balance the on-state collector currents of parallel-connected IGBTs, reducing the current imbalance to 5%. Also, a new fast short circuit protection method (FSCP) for IGBT modules was developed, designed and implemented in another GDU, allowing turning-off the considered IGBT in less than 1μs, reducing the IGBT stress. Another scheme implemented in a GDU features an improved gate current switching profile of the IGBT, which reduces the switching losses by 25% compared to the standard switching method. In order to reduce the conduction losses, a GDU with an increased turn-on gate-emitter voltage (larger than 20 V) was investigated. In the investigated IGBT, the on-state losses were reduced by 18% when a gate-emitter voltage of 35V is used compared to when a gate-emitter voltage of 15V is used. All these new GDU concepts have been implemented with a simple and inexpensive electronic circuitry, which is an important feature for a possible industrial implementation.

碩士<br>國立中山大學<br>應用數學研究所<br>84<br>In this paper, two topics of the Self-Exciting Threshold Autoregressive(SETAR) model are studied. First we discuss the asymptotic order of |(n+1)F_{n+1}(r^_{n+1})-(n+1)F_{n +1}( r^_{n})|, where F_{n}(.) is the empirical distribution of the precess, and r^_{n} is the least squares estimator of the threshold based on n observations. Secondary, for SETAR (2;0,0;d=1) model, we derived the relationship between the highest frequencies of the spectrum and the periods of limit cycles of its skeleton model.