• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 72
  • 56
  • 21
  • 9
  • 6
  • 6
  • 3
  • 3
  • 3
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 201
  • 201
  • 67
  • 58
  • 57
  • 47
  • 36
  • 29
  • 28
  • 24
  • 22
  • 18
  • 17
  • 15
  • 15
  • 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.
21

Correlation Analysis of Calcium Signalling Networks in Living Cells

Nilsson, Erik January 2008 (has links)
<p>In living cells, calcium ions (Ca2+) play an important role as an intracellular second messenger. It mediates the regulation of cellular processes such as gene expression, initiation of vesicle fusion in synapses, is used in muscle contraction and is believed to play a fundamental role in synaptic plasticity as a molecular substrate for learning. The Ca2+ signals are created by the fact that the concentration of Ca2+ in the cytosol is four orders of magnitude lower than in the extracellular fluid as well as in cytoplasmic compartments such as the endoplasmic reticulum (ER). This enables fast increments in the cytosol concentration, which is regulated back to normal concentration by different mechanisms. In this project, the connection between Ca2+ signals of different cells was analysed using different correlation techniques: cross-correlation of continuous signals and digitalised signals. Therefore a software tool was developed in MATLAB, which takes Ca2+ recordings from time-lapse fluorescence microscopy as input and calculates the pair wise correlation for all cells. The software was tested by using previous data from experiments with embryonic stem cells from mouse (mES) and human (hES) as well as data from recordings done as part of the project. The study shows that the mathematical method of cross-correlation can successfully be applied to quantitative and qualititative analysis of Ca2+ signals. Furthermore, there exist strongly correlated cells in colonies of mES cells and hES cells. We suggest the synchronisation is achieved by physical coupling implicating a decrease of correlation as the distance increases for strong correlations. In addition, the lag used by the cross-correlation function (an effective phase shift) decreases as the correlation coefficient increases and increases as the intercellular distance increases for high correlation coefficients. Interestingly, the number of cells included in small scale clusters of strongly correlated cells is significantly larger for the differentiating mES cells than for the proliferating mÉS cells. In a broader perspective, the developed software might be usd in for instance analysis of cellular electrical activity and shows the relevance of applying methods from the exact sciences to biology.</p> / QC 20100708
22

Effects of heterogeneity distribution on hillslope stability during rainfalls

Cai, Jing-sen, Yan, E-chuan, Yeh, Tian-chyi Jim, Zha, Yuan-yuan 04 1900 (has links)
The objective of this study was to investigate the spatial relationship between the most likely distribution of saturated hydraulic conductivity (K-s) and the observed pressure head (P) distribution within a hillslope. The cross-correlation analysis method was used to investigate the effects of the variance of lnK(s), spatial structure anisotropy of lnK(s), and vertical infiltration flux (q) on P at some selected locations within the hillslope. The cross-correlation analysis shows that, in the unsaturated region with a uniform flux boundary, the dominant correlation between P and Ks is negative and mainly occurs around the observation location of P. A relatively high P value is located in a relatively low Ks zone, while a relatively low P value is located in a relatively high Ks zone. Generally speaking, P is positively correlated with q/Ks at the same location in the unsaturated region. In the saturated region, the spatial distribution of K-s can significantly affect the position and shape of the phreatic surface. We therefore conclude that heterogeneity can cause some parts of the hillslope to be sensitive to external hydraulic stimuli (e.g., rainfall and reservoir level change), and other parts of the hillslope to be insensitive. This is crucial to explaining why slopes with similar geometries would show different responses to the same hydraulic stimuli, which is significant to hillslope stability analysis. (C) 2016 Hohai University. Production and hosting by Elsevier B.V.
23

Application of two-dimensional correlation spectroscopy for monitoring the mechanism of reaction between phenyl glycidyl ether (PGE) and metaphenylene diamine (mPDA)

Hollock, Michael R. January 1900 (has links)
Master of Science / Department of Chemical Engineering / J.R. Schlup / The curing reaction for the amine epoxy resin system of phenyl glycidyl ether (PGE) with metaphenylene diamine (mPDA) was investigated using two-dimensional correlation spectroscopy in the near-infared region (2DNIR). Synchronous and asynchronous correlation maps were generated using 2Dshige© software. The characteristic NIR band assignments were made, including the identification of new peaks for the O-H combination band in the 4825-4750 cm[superscript]-1 region and the CH stretching vibration overtone at 6018 cm[superscript]-1. Finally, the data suggests the reaction proceeds as follows: the appearance of the OH groups and C-H backbone vibrations occurs before the primary amine reactions and epoxide rings disappear.
24

Determinação de zeros na matriz de transferência de sistemas MIMO baseada em análise de correlação. / Determination of transfer matrix zeros from MIMO systems based on correlation analysis.

Massaro, Leandro Cuenca 02 June 2014 (has links)
O trabalho tem por objetivo avaliar diferentes métodos para identificar zeros na matriz de transferência de sistemas MIMO e propor um método novo baseado em análise de correlação. Estes métodos são utilizados durante a etapa de pré-identificação, a fim de se obter informações relevantes que possam ser utilizadas para se reduzir o tempo dos experimentos, diminuir a variabilidade dos parâmetros dos modelos e melhorar a eficácia dos modelos remanescentes. Estes métodos são aplicados a sistemas MIMO lineares, com dados coletados em malha aberta e em malha fechada. É avaliado o ganho obtido em relação à capacidade de predição dos modelos, a redução do tempo de identificação e o ganho de desempenho do controlador MPC que utiliza estes modelos. O trabalho conclui que a informação de zeros resulta em melhorias no tempo de identificação e no desempenho do controlador MPC. / This work aims to evaluate different methods to identify zeros in the transfer matrix of MIMO systems and to propose a new method based on correlation analysis. These methods are used during the pre-identification stage in order to identify relevant information that can be used to reduce the duration of the experiment, decrease model parameter variability and improve the accuracy of the remaining models. These methods are applied to MIMO linear systems, with data collected in open and closed-loop. The gains obtained in relation to the predictive ability of the models, the reduction of identification time and the performance gain of the MPC using these models are evaluated. This work concludes that the zero information results in improvements in identification time and in performance gain of the MPC controller.
25

Modelos de regressão log-gama generalizado com fração de cura / The generalized log-gama mixture model with covariates

Rizzato, Fernanda Bührer 08 February 2007 (has links)
Neste trabalho considera-se uma reparametrização no modelo log-gama generalizado para a inclusão de dados com sobreviventes de longa duração. Os modelos tentam estimar separadamente os efeitos das covariáveis na aceleração ou desaceleração no tempo e na fração de sobreviventes que é a proporção da população para o qual o evento não ocorre. A função logística é usada para o modelo de regressão com fração de cura. Os parâmetros do modelo, serão estimados através do método de máxima verossimilhança. Alguns métodos de influência, como a influência local e a influência local total de um indivíduo, serão introduzidos, calculados, analisados e discutidos. Finalmente, um conjunto de dados médicos será analisado sob o modelo log-gama generalizado com fração de cura. Uma análise de resíduos será executada para verificar a qualidade de ajuste do modelo. / In this work the generalized log-gama model is modified for possibility that long-term survivors are present in the data . The models attempt to estimate separately the effects of covariates on the accelaration/decelaration of the timing of a given event and surviving fraction; that is, the proportion of the population for which the event never occurs. The logistic function is used for the regression model of the surviving fraction. Inference for the model parameters is considered via maximum likelihood. Some influence methods, such as the local influence, total local influence of an individual are derived, analyzed and discussed. Finally, a data set from the medical area is analyzed under log-gama generalized mixture model. A residual analysis is performed in order to select an appropriate model.
26

Anomaly detection based on multiple streaming sensor data

Menglei, Min January 2019 (has links)
Today, the Internet of Things is widely used in various fields, such as factories, public facilities, and even homes. The use of the Internet of Things involves a large number of sensor devices that collect various types of data in real time, such as machine voltage, current, and temperature. These devices will generate a large amount of streaming sensor data. These data can be used to make the data analysis, which can discover hidden relation such as monitoring operating status of a machine, detecting anomalies and alerting the company in time to avoid significant losses. Therefore, the application of anomaly detection in the field of data mining is very extensive. This paper proposes an anomaly detection method based on multiple streaming sensor data and performs anomaly detection on three data sets which are from the real company. First, this project proposes the state transition detection algorithm, state classification algorithm, and the correlation analysis method based on frequency. Then two algorithms were implemented in Python, and then make the correlation analysis using the results from the system to find some possible meaningful relations which can be used in the anomaly detection. Finally, calculate the accuracy and time complexity of the system, and then evaluated its feasibility and scalability. From the evaluation result, it is concluded that the method
27

The Effects of Cognitive Styles on Summarization of Expository Text

Mast, Cynda Overton 08 1900 (has links)
The study investigated the relationship among three cognitive styles and summarization abilities. Both summarization products and processes were examined. Summarizing products were scored and a canonical correlation analysis was performed to determine their relationship with three cognitive styles. Summarizing processes were examined by videotaping students as they provided think aloud protocols. Their processes were recorded on composing style sheets and analyzed qualitatively. Subjects were sixth-grade students in self-contained classes in a suburban school district. Summarizing products were collected over a two week period in the fall. Summarizing processes were collected over an eight week period in the spring of the same school year. The results of the summarizing products analysis suggest that cognitive styles are related to summarization abilities. Two canonical correlations among the two variable sets were statistically significant at the .05 level of significance (.33 and .29). The results further suggest that students who are field independent, reflective, and flexible in their attentional style may be more adept at organizing their ideas and using written mechanics while summarizing. Students who are impulsive and constricted in attentional style may exhibit strength in expressing their ideas while summarizing. Results of the summarizing processes analysis suggest that students of one cognitive style combination may exhibit different behaviors while summarizing than those of other cognitive style combinations. Students who are field independent, reflective, and flexible in their attentional style seem to display more mature, interactive behaviors while summarizing than their peers of other cognitive style combinations.
28

Vývoj poskytování hypotečních úvěrů českým domácnostem / Development of mortgage loans by czech households

Cislerová, Šárka January 2010 (has links)
This thesis focuses on analyzing the development of mortgage loans which were provided by Czech households. The first chapter is devoted to the theory of mortgage loans and their basic characteristics. In the second chapter I focus on credit risk. Its management, monitoring and reduction methods. The third chapter includes the causes of debt and the amount of elemental analysis based on macroeconomic variables of mortgage loans (mortgage loan rate, GDP, inflation, unemployment, gross wage). Proof of this dependence is part of the last chapter using regression and correlation analysis.
29

Determinação de zeros na matriz de transferência de sistemas MIMO baseada em análise de correlação. / Determination of transfer matrix zeros from MIMO systems based on correlation analysis.

Leandro Cuenca Massaro 02 June 2014 (has links)
O trabalho tem por objetivo avaliar diferentes métodos para identificar zeros na matriz de transferência de sistemas MIMO e propor um método novo baseado em análise de correlação. Estes métodos são utilizados durante a etapa de pré-identificação, a fim de se obter informações relevantes que possam ser utilizadas para se reduzir o tempo dos experimentos, diminuir a variabilidade dos parâmetros dos modelos e melhorar a eficácia dos modelos remanescentes. Estes métodos são aplicados a sistemas MIMO lineares, com dados coletados em malha aberta e em malha fechada. É avaliado o ganho obtido em relação à capacidade de predição dos modelos, a redução do tempo de identificação e o ganho de desempenho do controlador MPC que utiliza estes modelos. O trabalho conclui que a informação de zeros resulta em melhorias no tempo de identificação e no desempenho do controlador MPC. / This work aims to evaluate different methods to identify zeros in the transfer matrix of MIMO systems and to propose a new method based on correlation analysis. These methods are used during the pre-identification stage in order to identify relevant information that can be used to reduce the duration of the experiment, decrease model parameter variability and improve the accuracy of the remaining models. These methods are applied to MIMO linear systems, with data collected in open and closed-loop. The gains obtained in relation to the predictive ability of the models, the reduction of identification time and the performance gain of the MPC using these models are evaluated. This work concludes that the zero information results in improvements in identification time and in performance gain of the MPC controller.
30

Innovation generation in buyer-seller relationships

Roy, Subroto, University of Western Sydney, College of Law and Business, School of Marketing January 2001 (has links)
In recent years, a number of researchers have questioned the traditional notion of the producer as the sole generator of innovation in buyer seller relationships. Increasingly, innovation generation has been recognized as an outcome of interaction between a firm and various outside entities. According to this view, supplier involvement and alliances are a route to innovation generation. Clearly, business market relationships provide an important opportunity for interaction between buyer and seller. Despite this realization, only very limited research has focused on innovation generation in business-to-business relationships. To alleviate this important gap in literature, this thesis develops a conceptual model and hypotheses of innovation generation in business-to-buyer seller relationships. The research uses a combination of qualitative and quantitative techniques to examine the proposed theoretical model of innovation generation. A pilot case study is followed by development of and purification of measures using the IMP database on supplier customer interfirm relations in Europe and China. The hypotheses and model are tested using correlation and regression analysis. Results suggest that innovation generation is indeed facilitated by buyer seller interactions. Interaction also moderates the effect of other relationship and technology factors and type of innovation generated / Doctor of Philosophy (PhD) (Marketing)

Page generated in 0.0913 seconds