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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.
411

Modelling Issues in Three-state Progressive Processes

Kopciuk, Karen January 2001 (has links)
This dissertation focuses on several issues pertaining to three-state progressive stochastic processes. Casting survival data within a three-state framework is an effective way to incorporate intermediate events into an analysis. These events can yield valuable insights into treatment interventions and the natural history of a process, especially when the right censoring is heavy. Exploiting the uni-directional nature of these processes allows for more effective modelling of the types of incomplete data commonly encountered in practice, as well as time-dependent explanatory variables and different time scales. In Chapter 2, we extend the model developed by Frydman (1995) by incorporating explanatory variables and by permitting interval censoring for the time to the terminal event. The resulting model is quite general and combines features of the models proposed by Frydman (1995) and Kim <i>et al</i>. (1993). The decomposition theorem of Gu (1996) is used to show that all of the estimating equations arising from Frydman's log likelihood function are self-consistent. An AIDS data set analyzed by these authors is used to illustrate our regression approach. Estimating the standard errors of our regression model parameters, by adopting a piecewise constant approach for the baseline intensity parameters, is the focus of Chapter 3. We also develop data-driven algorithms which select changepoints for the intervals of support, based on the Akaike and Schwarz Information Criteria. A sensitivity study is conducted to evaluate these algorithms. The AIDS example is considered here once more; standard errors are estimated for several piecewise constant regression models selected by the model criteria. Our results indicate that for both the example and the sensitivity study, the resulting estimated standard errors of certain model parameters can be quite large. Chapter 4 evaluates the goodness-of-link function for the transition intensity between states 2 and 3 in the regression model we introduced in chapter 2. By embedding this hazard function in a one-parameter family of hazard functions, we can assess its dependence on the specific parametric form adopted. In a simulation study, the goodness-of-link parameter is estimated and its impact on the regression parameters is assessed. The logistic specification of the hazard function from state 2 to state 3 is appropriate for the discrete, parametric-based data sets considered, as well as for the AIDS data. We also investigate the uniqueness and consistency of the maximum likelihood estimates based on our regression model for these AIDS data. In Chapter 5 we consider the possible efficiency gains realized in estimating the survivor function when an intermediate auxiliary variable is incorporated into a time-to-event analysis. Both Markov and hybrid time scale frameworks are adopted in the resulting progressive three-state model. We consider three cases for the amount of information available about the auxiliary variable: the observation is completely unknown, known exactly, or known to be within an interval of time. In the Markov framework, our results suggest that observing subjects at just two time points provides as much information about the survivor function as knowing the exact time of the intermediate event. There was generally a greater loss of efficiency in the hybrid time setting. The final chapter identifies some directions for future research.
412

Modeling of Simultaneous Switching Noise in On-Chip and Package Power Distribution Networks Using Conformal Mapping, Finite Difference Time Domain and Cavity Resonator Methods

Mao, Jifeng 29 October 2004 (has links)
This thesis focused on modeling and simulation of simultaneous switching noise in packages as well as integrated circuits and the focus was mainly on the latter. Efficient and accurate methods have been developed for modeling the coupling due to SSN in multi-layered planes arising in electronic packages, extraction of the power grid in integrated circuits and simulation of the power supply noise in large size networks arising in power distribution network. These methods include conformal mapping, finite difference time domain and cavity resonator methods, using which the electrical performance of the power distribution system in a high speed electronic product can be predicted. The model developed for field penetration captured the effect of the magnetic field penetrating through planes in multi-layered packages. Analytical model for the extraction of the interconnect parasitics for a regular on-chip power grid has been presented. Complex image technique has been applied for modeling the dispersive interconnect on lossy silicon substrate. The Debye rational approximation has been used to approximate the RLGC parameters in order to simulate the frequency dependent elements in the time domain. The simulation of the entire network of the full-chip power grid has been carried out using the modified FDTD expressions. Several aspects of characterizing the generic on-chip power distribution network have been presented. The crossover capacitance has been evaluated using analytical model derived from conformal mapping. An analytical model has been proposed to extract parameters of on-chip multi-conductor transmission lines, which guarantees the stability and is applicable to general distribution of multi-conductor transmission lines. The above modeling procedures have been incorporated into a computer program, which generates the power grid model from the layout of chip power distribution networks automatically. Research on 3-D on-chip power distribution networks has been presented. The complex image technique has been extended from microstrip-type interconnects to stripline-type interconnects. Macromodel images have been derived with closed form expressions to capture the loss mechanism of the multiple conductive substrates. The effect of 3-D integration on switching noise has been illustrated in the time domain using examples.
413

Distribution of Stress in Three-Dimensional Models of Human Coronary Atherosclerotic Plaque Based on Acrylic Histologic Sections

Lowder, Margaret Loraine 05 June 2007 (has links)
Each year in the United States over a million people experience a myocardial infarction. The majority of these attacks are caused by coronary artery plaque cap rupture with subsequent thrombus formation. Because rupture is a mechanical event and the tendency of a plaque to rupture is due in part to increases in the mechanical stresses in the fibrous cap, mechanical analyses are important to understanding plaque stability. Histology is the only method capable of identifying plaque features that are associated with vulnerability. Therefore, minimally distorted histologic sections should serve as a basis for constructing the models used in mechanical analyses. Further, because substantial longitudinal variations in geometry and mechanical properties often exist, models should be three-dimensional (3-D). Finally, given the complex geometries of atherosclerotic plaques and the fact that they are composed of different materials, the finite element (FE) method should be used to determine the distribution of stress under physiological loading. Until now, a critical need has existed to determine the distribution of stress in 3-D FE models of human coronary atherosclerotic plaques based on minimally distorted histologic sections. In this research study, a method to measure and correct for distortions caused by acrylic histologic processing was first created. The devised strain-based method yields a limited set of parameters needed for a first order correction. Thus, corrections can be easily implemented using FE methods. Next, a methodology to create 3-D finite FE models of human coronary atherosclerotic plaques based on stable acrylic histologic sections was developed. Models of plaques, ranging in disease severity, were generated using the developed methodology. Lastly, the distributions of stress in these models were obtained and the effects of some plaque features on stresses were determined. Results from this study confirm that morphological description of a plaque is not sufficient to predict plaque rupture. The findings suggest that in many cases the 3-D stress field within a plaque must be known in order to assess plaque stability. Finally, the results show that patient specific models must be developed if the 3-D stress field within a plaque is to be determined.
414

Selfhood and Relation:Samuel Beckett¡¦s Two Sets of Trilogy and Related Works

Chang, Li-mei 06 February 2010 (has links)
Beckett celebrates the solidity of selfhood and relation in his erosive texts against the grain. In light of this, this dissertation sets out with the intention to salvage the grains lost by Beckett¡¥s elliptic style with a focus on the device of inversion. In Three Novels, this device is employed to deal with world cultures, Irish landscapes and the looming relations, adumbrating a selfhood enriched by these select fragments. Also, the volatile self performs rites of rebirth with a voice as witness. Under the voice¡¥s narration and an un-specified hearing body, two births, one problematic the other immaculate, are at narthex: the former fading out the latter in. Thus, a selfhood is in transition. In Nohow On, a phosphorescent relation between one¡¥s plural selves and concerned others and between the artist and art denotes Beckett¡¥s ideas of relation to be interpersonal, aesthetical but inchoate. In an effort to explore the scale of inversion in the two trilogies, five aspects of Beckett are highlighted. First, his self-searching by fusing cultural elites and the distinct I into the voice of ¢wnot-I¡ü delivers an oracle about the everlasting soul rather than the ephemeral individual. Second, a kinetic I that acts against time, space and the superficial self indicates a dynamic and vigorous selfhood. Third, many incompatible things are juxtaposed and displaying their mutuality. By their examples, a new occasion and a new term of relation have been introduced. Fourth, aisling, an ancient Irish genre, characterizes Ill Seen Ill Said. It niches a deformed yet beloved hag and helps dissolve Beckett¡¥s trouble with May Beckett, to whom he is, simultaneously, son and lover. Last and not the least, a solipsistic Beckett negotiates the haunting others with virtuosities. His creative managements make others shine like stars in the artist¡¥s cosmos. Not until this constellational allocation of himself and his dear ones does Beckett¡¥s selfhood appear to be in plenum and cornucopia. Together, these five facets feature our author¡¥s triumph over the besieging void. Confronting the void, which Schopenhauer warns against yet Beckett embraces full-heartedly, becomes an opportunity to relate men, art and humor. While deploying selfhood and relation as the double agent to expose the very least things and persons he can¡¥t be without, Beckett accomplishes another task as well. Namely, he tames the void and makes it glow simultaneously. This ploy verifies Beckett¡¥s vow that an art, if not also the self, well done is a consecration to the void. For his capacities to contract laughter despite woes and his determination to have fun despite despair, our author that scrutinizes selfhood and relation with unblinking eyes is rhapsodic all in all.
415

The Informationization of the People's Liberation Army,1991 ¡V 2010

Wang, An-kuo 07 January 2011 (has links)
Followinf the year of 1991, with the extensive application in the military field of new and high technology, focusing on information technology, it is a common choice for main countries in the world to build an Informationization army to promote the ability to win an information war in the future. Military information construction has already become the focus topic of military theory innovation and military practice and also an important observation indicator to assess national defense construction and military strength development all over the world. Under this background, Jiang Zemin proposed a national defence and military modernization cross-centennial ¡§three step¡¨ development strategy to promote military information construction in an all-round way and hope to build up an information-based army in 2050. The construction achievement of the first step strategy from 1991 to 2010 is a key factor to the success or failure of PLA building up an Informationization army in 2050. The main study focus and range of this dissertation is PRC's first step national defence and military modernization construction based on cross-centennial ¡§three steps¡¨ development strategy. By studying military thinking logic and law building, including fighting, building, training, we are going to observe and understand the military information construction outcome from 1991 to 2010 of PRC and assess and analyze the prospect of PLA military information construction, the domestic and foreign challenge that they may face, and its impacts on surrounding countries.
416

A Sensorless Driver with Current Feedback for Three-Phase Brushless DC Fan Motor

Lin, Shih-Wei 18 October 2010 (has links)
The design and implementation of speed control driver which is applied to three-phase brushless DC fan motor are presented in this thesis. In the back-EMF detection circuit, we use digital filter circuits to obtain commutation to overcome the switch noises which are generated by high frequency PWM, without using traditional capacitor filter circuits which need more volume for additional external capacitor. Because the problems of high frequency magnetizing vibration and dispensable power consumption are generated by open-loop fixed frequency PWM speed control approach, closed-loop speed feedback control methods and closed-loop current feedback control methods are adopted to achieve high efficiency and low vibration of the fan motor drivers.
417

From A Source of Wisdom to a Consumed Other--Imaging China in Modern Japan's Evolving Narratives on the "Records of the Three Kingdoms"

Tung, Hue-Jen 28 July 2011 (has links)
In the history of Japanese society spread of the Three Kingdoms story, mainly the integration of China's " Records of Three Kingdoms" and " Romance of the Three Kingdoms" the two different meanings of the text.Prior to the Meiji Restoration in Japan, the "Records of Three Kingdoms" is the record of the past history of China Ministry of history books, "Romance of the Three Kingdoms" is the "Three Kingdoms" and popular version, to explain the "Three Kingdoms" in content.Both in terms of Chinese society may be different meaning of the text, but Japanese society is concerned, the difference may be only a difference in narrative to convey the message and meaning are the same, is the story of the history of recorded foreign text.The purpose of this study is to explore Japanese society in a different era, the "Romance of the Three Kingdoms", after the translation or interpretation, they demonstrate the significance of changes in China's image. Edo period of Japanese society has entered the peace, the general public began to have the ability to make contact with the consumer culture of the goods, "Three Kingdoms" in the space environment, such as the Japanese study Chinese history and culture of reference. When the Meiji Restoration, Japan was the impact of Western culture, a change in the past the Chinese learning attitude. "Three Kingdoms" has become the object of Japanese society, one study of Chinese. After World War I's high economic growth in Japan, the Japanese appear to read popular, and the commercialization of culture phenomenon. Mr Eiichi Yoshikawa Lynch's "Three Kingdoms" that reflects Japanese society, the rise of popular culture and Japanese society as a whole into the era of mass consumption. At this time the "Three Kingdoms" is regarded as China's history textbooks from the thinking, culture change has become a popular consumer goods. Japanese popular culture after World War II, the content, although generally extend the pre-war American popular culture with this combination of traditional Japanese social and moral of the model, and then updated by the development of the media, while for a number of performance, that is, Japanese comics one of them. 1970s, Yokoyama "Three Kingdoms" a Japanese comic book which, on behalf of a Chinese theme of the works. Further developed with China's image and culture related creation.
418

Numerical simulation for flow induced vibration of three circular cylinders with various arrangement

Lin, Yu-Hsuan 02 August 2011 (has links)
The present study aims to explore dynamical behavior of the fluid- elastic vibration of a single cylinder and three cylinders in shear flow by numerical simulations. This paper investigates the effects of the shear parameter, mass ratio, and spacing(P/D) on fluid-elastic vibration of the cylinders. Continuity equation and momentum equations are solved alternatively using a CFD package, Fluent 6.3.26. Dynamic meshing techniques together with the cylinder motion equations are employed in the simulation. Under different flow conditions, flow types, and cylinder motion models, lock-in and fluid-elastic vibration are studied. The results show that motion and flow types of a single cylinder in uniform flow are in agreement with the previous studies in literatures. In shear flow, however, as the shear parameter increases, the fluid-elastic vibration of the cylinder is induced, and thus amplitude of the cylinder increases considerably. Further, three cylinders in the shear flow are studied. Three cylinders arrangements (classified as side-by-side, tandem ,and stagger) and the distance between cylinders are the factors to cause fluid-elastic vibration. Compared with the single cylinder motion, three cylinders motion¡¦s critical flow velocity is smaller than that of the single cylinder motion, which means two cylinders motion are more subject to fluid-elastic vibration.
419

Prediction for the Domain of RNA with Support Vector Machine

Liu, Chu-Kai 01 September 2011 (has links)
The three-domain system is a biological classification of RNA. In bioinformatics, predicting the domain of RNA is helpful in the research of DNA and protein. By reviewing the related literatures, we notice that many researches are conducted for domain prediction with only the primary structure. However, compared with the primary structure, the secondary structure of an RNA contains more discriminative information. Therefore, we propose an SVM-based prediction algorithm that considers both the features of primary and secondary structures. In our experiment, we adopt 1606 RNA sequences from RNase P, 5S ribosomal RNA and snoRNA databases. The experimental results show that our algorithm achieves 96.39%, 95.70%, and 95.46% accuracies by combining three softwares of secondary structure prediction, pknotsRG, NUPACK, and RNAstructure, respectively. Thus, our method is a new effective approach for predicting the domain of an RNA sequence. The software implementation of our method, named RDP (RNA Domain Prediction), is available on the Web http://bio.cse.nsysu.edu.tw/RDP/.
420

Imaging and Computational Methods for Exploring Sub-cellular Anatomy

Mayerich, David 16 January 2010 (has links)
The ability to create large-scale high-resolution models of biological tissue provides an excellent opportunity for expanding our understanding of tissue structure and function. This is particularly important for brain tissue, where the majority of function occurs at the cellular and sub-cellular level. However, reconstructing tissue at sub-cellular resolution is a complex problem that requires new methods for imaging and data analysis. In this dissertation, I describe a prototype microscopy technique that can image large volumes of tissue at sub-cellular resolution. This method, known as Knife-Edge Scanning Microscopy (KESM), has an extremely high data rate and can capture large tissue samples in a reasonable time frame. We can therefore image complete systems of cells, such as whole small animal organs, in a matter of days. I then describe algorithms that I have developed to cope with large and complex data sets. These include methods for improving image quality, tracing filament networks, and constructing high-resolution anatomical models. These methods are highly parallel and designed to allow users to segment and visualize structures that are unique to high-throughput microscopy data. The resulting models of large-scale tissue structure provide much more detail than those created using standard imaging and segmentation techniques.

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