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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.
111

Invariant Procedures for Model Checking, Checking for Prior-Data Conflict and Bayesian Inference

Jang, Gun Ho 13 August 2010 (has links)
We consider a statistical theory as being invariant when the results of two statisticians' independent data analyses, based upon the same statistical theory and using effectively the same statistical ingredients, are the same. We discuss three aspects of invariant statistical theories. Both model checking and checking for prior-data conflict are assessments of single null hypothesis without any specific alternative hypothesis. Hence, we conduct these assessments using a measure of surprise based on a discrepancy statistic. For the discrete case, it is natural to use the probability of obtaining a data point that is less probable than the observed data. For the continuous case, the natural analog of this is not invariant under equivalent choices of discrepancies. A new method is developed to obtain an invariant assessment. This approach also allows several discrepancies to be combined into one discrepancy via a single P-value. Second, Bayesians developed many noninformative priors that are supposed to contain no information concerning the true parameter value. Any of these are data dependent or improper which can lead to a variety of difficulties. Gelman (2006) introduced the notion of the weak informativity as a comprimise between informative and noninformative priors without a precise definition. We give a precise definition of weak informativity using a measure of prior-data conflict that assesses whether or not a prior places its mass around the parameter values having relatively high likelihood. In particular, we say a prior Pi_2 is weakly informative relative to another prior Pi_1 whenever Pi_2 leads to fewer prior-data conflicts a priori than Pi_1. This leads to a precise quantitative measure of how much less informative a weakly informative prior is. In Bayesian data analysis, highest posterior density inference is a commonly used method. This approach is not invariant to the choice of dominating measure or reparametrizations. We explore properties of relative surprise inferences suggested by Evans (1997). Relative surprise inferences which compare the belief changes from a priori to a posteriori are invariant under reparametrizations. We mainly focus on the connection of relative surprise inferences to classical Bayesian decision theory as well as important optimalities.
112

Magiska ögonblick och förlorade möjligheter : En studie i möjligheterna att lära med utgångspunkt i elevernas förkunskaper, svårigheter med lärandeobjektet och variationen i det erbjudna lärandet. / Magical moments and missed opportunities : A study of opportunities to learn on basis of students' prior knowledge, difficulties of learning object and the variance of the offered learning

Andersson Bustad, Susanne January 2011 (has links)
This study is based on an interest in trying to understand what is needed to ensure that students actually learn in a learning object, in this study equations. Algebra is an area of mathematics in several studies proved to be a stumbling block for many students. Using letters in mathematis is difficult for most students according to research reports and it is also consistent with my own experince as a teacher. The purpose of this study was to seek answers to what in the lesson content and also during the interview that allowed the students to learn more about the learning object. Based on students' prior knowledge and the difficulties students might have with the learning object and the offer of learning, I try to get an answer to what might have contribut the students to developed knowledge of the learning object. This qualitative study is based on a variation theory perspective. The two students who participated in the study attended the same class in high school. By using the theory of variation patterns, it made it possible for me to describe how students learn new things about the learning object, equations. To gain insight into how the students solved the data and developed new knowledge, I had the lesson content and their statements in the interviews to help me understand the difficulties in solving the equtionatask and what in the lessons that have contributed to new knowledge. The results show that pupils' understanding and difficulties in learning objects are relevant to how they can perceive, discern and assimilate new knowledge. One student was able to experience learning from their prior knowledge and assimilate what he had to develop in the variety in the offer of learning. The offered learning did not give the second student the same opportunity. The results indicates that the knowledge of students' prior knowledge, the difficulties the learning object can create and students' own narrative, I argue on the basis of the study'sresults, it is important knowledge for every teacher to be aware of befor the presentation of the lesson if it will give every student opportunities to learn.
113

Behövs ett gemensamt patentsystem inom EU?

Brandänge, Martin January 2010 (has links)
Under slutet av 1800-talet kom Pariskonventionen att förändra synen på patentoch en era av multilateralt samarbete kom att inledas.Med anledning av utvecklingen på den europeiska patentmarknaden har sedanmitten av 1900-talet betydande harmoniserande förändringar genomförts. Ettgemensamt patentsystem inom EU har dock ännu inte blivit verklighet.Svensk patenträtt har över tiden kommit att närma sig den europeiska, vilket är ettexempel på det arbete som pågår inom Europa. Inom den svenska rätten är Patentlagenav stor betydelse då internationella avtalsbestämmelser kommit att inkorporerasi denna lag.Även om ett nordiskt samarbete funnits sedan länge är det den europeiska patentkonventionentillsammans med det europeiska patentkontoret som utgjort det mestbetydelsefulla resultatet av samarbetet inom den europeiska patenträtten. I slutetav år 2009 nåddes en politisk överenskommelse gällande ett gemenskapspatentoch en gemensam patentdomstol inom EU. Huruvida denna överenskommelsekommer att utmynna i något nytt patent eller någon ny patentdomstol är dockännu oklart. Bland annat väntas ett avgörande från EG-domstolen.Det har argumenterats för att ett nytt patentsystem skulle kunna innebära ett merkostnadseffektivt och smidigt patentsystem inom EU. Samtidigt försvåras fråganslösning av de många olika viljor som finns då ett så övergripande samarbete är förhanden. Språkliga problem har varit betydande och komplicerat debatten.Vilka för- och nackdelar som skulle kunna följa av ett nytt patentsystem behandlasi denna uppsats för att svara på frågan om det verkligen behövs ett gemensamtpatentsystem inom EU. Trots de svårigheter som omgärdar frågan ställer sigmånga av de europeiska länderna positivt till ett ökat samarbete. Exakt hur dettasamarbete ska se ut har dock varit den stora frågan.Enligt min uppfattning finns det behov av ytterligare samarbete och fler förbättringarinom den europeiska patenträtten.
114

Factor Models to Describe Linear and Non-linear Structure in High Dimensional Gene Expression Data

Mayrink, Vinicius Diniz January 2011 (has links)
<p>An important problem in the analysis of gene expression data is the identification of groups of features that are coherently expressed. For example, one often wishes to know whether a group of genes, clustered because of correlation in one data set, is still highly co-expressed in another data set. For some microarray platforms there are many, relatively short, probes for each gene of interest. In this case, it is possible that a given probe is not measuring its targeted transcript, but rather a different gene with a similar region (called cross-hybridization). Similarly, the incorrect mapping of short nucleotide sequences to a target gene is a common issue related to the young technology producing RNA-Seq data. The expression pattern across samples is a valuable source of information, which can be used to address distinct problems through the application of factor models. Our first study is focused on the identification of the presence/absence status of a gene in a sample. We compare our factor model to state-of-the-art detection methods; the results suggest superior performance of the factor analysis for detecting transcripts. In the second study, we apply factor models to investigate gene modules (groups of coherently expressed genes). Variation in the number of copies of regions of the genome is a well known and important feature of most cancers. Copy number alteration is detected for a group of genes in breast cancer; our goal is to examine this abnormality in the same chromosomal region for other types of tumors (Ovarian, Lung and Brain). In the third application, the expression pattern related to RNA-Seq count data is evaluated through a factor model based on the Poisson distribution. Here, the presence/absence of coherent patterns is closely associated with the number of incorrect read mappings. The final study of this dissertation is dedicated to the analysis of multi-factor models with linear and non-linear structure of interactions between latent factors. The interaction terms can have important implications in the model; they represent relationships between genes which cannot be captured in an ordinary analysis.</p> / Dissertation
115

Shape Reconstruction with Topological Priors

Zheng, Ying January 2012 (has links)
<p>We show topological priors play an important role in solving the inverse problem of shape reconstruction. We classify the applications into 1D, 2D, and 3D cases:</p><p>In 1D, we show that the persistent extrema of the curvature function of a closed curve are useful for shape simplication. In 2D, we study how to label a scene into multiple tiers to approximate the actual scene layout. We use the number of extrema as a topological prior to bound the complexity of the shape of tiers and study 2D labeling under symmetry shape priors. In 3D, we recover the detailed 3D root shape using multiple 2D images. Three novel ideas are presented. First, we propose the use of harmonic images for background subtraction. Second, we develop the regularized visual hull to preserve the details of an example image in reconstruction. Third, we enforce the topological connectedness by an ecient algorithm that is inspired by the recent development of persistent homology.</p><p>Computational efficiency is emphasized throughout the thesis. We show that 1D topological persistence can be computed in O(n) time on a closed curve of n nodes. For 2D tiered labeling, we give an approximation algorithm to compute it in O(nK) time for K tiers on an image of n pixels. For 3D root reconstruction, we accelerate the computation using oct-trees and minimal spanning trees. With these ingredients, it takes only a few seconds to reconstruct a detailed root shape from 40 images of resolution 1600*1200 on a laptop.</p> / Dissertation
116

The Study in entrepreneurial process to influence of the entrepreneurial team ¡GA case of Taiwan cultural and creative industry

Chen, Heng-chin 14 February 2011 (has links)
Develops the cultural and creative industry is the main policy of the Taiwan government in recent years. Entrepreneurial as cultural creative industry in different stages, what an opportunity, resources and entrepreneurial team to influence an entrepreneurial activity, this is a main topic discussing in this research. This research topic¡¦s is focus on an opportunities, resources and entrepreneurial team. To perform a new business that should existence the natures both of dynamic and complexity. Furthermore, to had sort out three issues within internal factors, this expect to awareness what the differences between with opportunity, resources and entrepreneurial team through this research as well as tries to understand the entrepreneurial team how to respond it when opportunity and resources change in the different entrepreneurial processes. And other, this research had been analyzed an entrepreneurial team how to influence by these factors. The results obtain from research that social culture, industrial environment and technological progress still influencing in the first stage of entrepreneurial processes obviously. Under the social culture's vicissitude, people's life accomplishment had been promoted; the most of people are pursue to balancing between the life and culture. Thus, this makes the industrial environment have to the change, in other, the traditional creators should out of box as well, and establish a model of culture creativity. Entrepreneurial processes within gestation stage, it had emphasis the entrepreneurial team's composition and characteristic. Prior knowledge and shared values have influence obviously in this stage. It can be explain that entrepreneurial team's composition has complementary or similar in the prior knowledge. Let the members of entrepreneurial team no matter can complement one another in the communication or the specialty. Because they can be share their values with other into the team members, to conduct and policy-making standard. It should reduce the nonessential conflict. Finally, entrepreneurial processes within infancy stage that can explanation as the competitive advantages of entrepreneur from intangible assets. Intangible assets are from philosophy, annotation technique and style of creator. In this way, creator's intangible asset is not the tangible asset or the organizational capability can substitute.
117

Daily Time Step Simulation with a Priority Order Based Surface Water Allocation Model

Hoffpauir, Richard James 2010 December 1900 (has links)
Surface water availability models often use monthly simulation time steps for reasons of data availability, model parameter parsimony, and reduced computational time. Representing realistic streamflow variability, however, requires modeling time steps with sub-monthly or daily temporal resolution. Adding daily time step simulation capability to the Water Rights Analysis Package (WRAP) and the Texas Water Availability Modeling (WAM) System is a growing area of need and interest in water rights permitting, water supply planning, and environmental protection. This research consisted of the following tasks: 1. Key modeling issues are identified that are relevant to daily time step modeling, but are otherwise not considered with monthly simulations. These key modeling issues include disaggregating monthly naturalized flows into daily flows, routing changes to flow through the stream network, reducing impacts to water availability in a priority order based water right system through the use of streamflow forecasting, distributing water right targets from monthly to daily amounts, and integrating flood control reservoir operations into the existing conservation reservoir modeling framework. 2. Two new programs for WRAP are developed to address the key daily time step modeling issues. The new programs include a pre-processor program, DAY, and a daily simulation program, SIMD. 3. A case study of the Brazos River Basin WAM is presented using daily time steps with SIMD. The purpose of the case study is to present an implementation of the daily modeling capabilities. 4. The case study simulation results are used as a basis to draw conclusions regarding monthly versus daily simulation outcomes. The research, as presented through the Brazos River Basin WAM case study, illustrated that incorporating realistic daily streamflow variability into the simulation of a priority order based water allocation system can substantially affect the results obtained for time series of critical period reservoir storage contents, the determination of long-term water right reliability, and the distribution of unappropriated and regulated flows. The modeling capabilities developed by this research advance the state of water availability modeling with sub-monthly time steps by addressing the key modeling issues related to streamflow variability and routing.
118

Constrained capacity of MIMO Rayleigh fading channels

He, Wenyan 2011 May 1900 (has links)
In this thesis channel capacity of a special type of multiple-input multiple-output (MIMO) Rayleigh fading channels is studied, where the transmitters are subject to a finite phase-shift keying (PSK) input alphabet. The constraint on the input alphabet makes an analytical solution for the capacity beyond reach. However we are able to simplify the final expression, which requires a single expectation and thus can be evaluated easily through simulation. To facilitate simulations, analytical expressions are derived for the eigenvalues and eigenvectors of a covariance matrix involved in the simplified capacity expression. The simplified expression is used to provide some good approximations to the capacity at low signal-to-noise ratios (SNRs). Involved in derivation of the capacity is the capacity-achieving input distribution. It is proved that a uniform prior distribution is capacity achieving. We also show that it is the only capacity-achieving distribution for our channel model. On top of that we generalize the uniqueness case for an input distribution to a broader range of channels.
119

Bayesian Inference In Anova Models

Ozbozkurt, Pelin 01 January 2010 (has links) (PDF)
Estimation of location and scale parameters from a random sample of size n is of paramount importance in Statistics. An estimator is called fully efficient if it attains the Cramer-Rao minimum variance bound besides being unbiased. The method that yields such estimators, at any rate for large n, is the method of modified maximum likelihood estimation. Apparently, such estimators cannot be made more efficient by using sample based classical methods. That makes room for Bayesian method of estimation which engages prior distributions and likelihood functions. A formal combination of the prior knowledge and the sample information is called posterior distribution. The posterior distribution is maximized with respect to the unknown parameter(s). That gives HPD (highest probability density) estimator(s). Locating the maximum of the posterior distribution is, however, enormously difficult (computationally and analytically) in most situations. To alleviate these difficulties, we use modified likelihood function in the posterior distribution instead of the likelihood function. We derived the HPD estimators of location and scale parameters of distributions in the family of Generalized Logistic. We have extended the work to experimental design, one way ANOVA. We have obtained the HPD estimators of the block effects and the scale parameter (in the distribution of errors) / they have beautiful algebraic forms. We have shown that they are highly efficient. We have given real life examples to illustrate the usefulness of our results. Thus, the enormous computational and analytical difficulties with the traditional Bayesian method of estimation are circumvented at any rate in the context of experimental design.
120

Behövs ett gemensamt patentsystem inom EU?

Brandänge, Martin January 2010 (has links)
<p>Under slutet av 1800-talet kom Pariskonventionen att förändra synen på patentoch en era av multilateralt samarbete kom att inledas.Med anledning av utvecklingen på den europeiska patentmarknaden har sedanmitten av 1900-talet betydande harmoniserande förändringar genomförts. Ettgemensamt patentsystem inom EU har dock ännu inte blivit verklighet.Svensk patenträtt har över tiden kommit att närma sig den europeiska, vilket är ettexempel på det arbete som pågår inom Europa. Inom den svenska rätten är Patentlagenav stor betydelse då internationella avtalsbestämmelser kommit att inkorporerasi denna lag.Även om ett nordiskt samarbete funnits sedan länge är det den europeiska patentkonventionentillsammans med det europeiska patentkontoret som utgjort det mestbetydelsefulla resultatet av samarbetet inom den europeiska patenträtten. I slutetav år 2009 nåddes en politisk överenskommelse gällande ett gemenskapspatentoch en gemensam patentdomstol inom EU. Huruvida denna överenskommelsekommer att utmynna i något nytt patent eller någon ny patentdomstol är dockännu oklart. Bland annat väntas ett avgörande från EG-domstolen.Det har argumenterats för att ett nytt patentsystem skulle kunna innebära ett merkostnadseffektivt och smidigt patentsystem inom EU. Samtidigt försvåras fråganslösning av de många olika viljor som finns då ett så övergripande samarbete är förhanden. Språkliga problem har varit betydande och komplicerat debatten.Vilka för- och nackdelar som skulle kunna följa av ett nytt patentsystem behandlasi denna uppsats för att svara på frågan om det verkligen behövs ett gemensamtpatentsystem inom EU. Trots de svårigheter som omgärdar frågan ställer sigmånga av de europeiska länderna positivt till ett ökat samarbete. Exakt hur dettasamarbete ska se ut har dock varit den stora frågan.Enligt min uppfattning finns det behov av ytterligare samarbete och fler förbättringarinom den europeiska patenträtten.</p>

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