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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.
201

Consistency management in collaborative modelling and simulation

Ulriksson, Jenny January 2005 (has links)
<p>The aim of this thesis is to exploit the technological capabilities of computer supported collaborative work (CSCW) in the field of collaborative Modelling and Simulation (M&S). The thesis focuses on addressing two main problems: (i) providing flexible means of consistency management in collaborative M&S, and (ii) the ability of providing platform and application independent services for collaborative M&S.</p><p>In this work, some CSCW technologies and how some of the concepts can be incorporated in a distributed collaborative M&S environment, have been studied. An environment for component based simulation development and visualization, which provides support for collaborative M&S, has been designed. Some consistency policies that can be used in conjunction with distributed simulation and the High Level Architecture (HLA) have been investigated. Furthermore, the efficient utilization of HLA and XML in combination, as the foundation of a CSCW infrastructure has been proved. Two consistency policies were implemented utilizing HLA, a strict and an optimistic, in the distributed collaborative environment. Their performance was compared to the performance of a totally relaxed policy, in various collaboration situations.</p>
202

High consistency refining of mechanical pulps during varying refining conditions : High consistency refiner conditions effect on pulp quality

Muhic, Dino January 2008 (has links)
<p> </p><p>The correlation between pulp properties and operating conditions in high consistency (HC) refiners at Holmen Paper AB were studied. Two types of HC refiners were investigated: the Andritz RTS refiner at the Hallstavik Mill and the Sprout-Bauer Twin 60 refiner at the Braviken Mill. The objective of the study was to clarify the relationship between the pulp properties and refining conditions such as electrical energy input, housing- and feed- pressure and plate wear in high consistency refining.</p><p>The results of this project show that worn segments reduce the operating energy maximum input and the pulp and handsheet properties in negative aspects such as lower tensile- and tear index, and shorter average fibre length. Energy input is an important factor in the refining process and influence Canadian Standard Freeness and the tensile index as evident from the probability residuals. Housing pressure and feed pressure influence the pulp quality and should be adjusted in order to optimise the refining process, although the effect is not as great as for energy input or plate wear.</p><p>The results of the study indicate that Braviken Mill is operating at its optimum for the parameters measured in this project. Hallstaviks goal, to avoid fibre shortening and to obtain better tensile index, can be reached by making slight changes in pressure condition.</p><p> </p>
203

Mixture distributions with application to microarray data analysis

Lynch, O'Neil 01 June 2009 (has links)
The main goal in analyzing microarray data is to determine the genes that are differentially expressed across two types of tissue samples or samples obtained under two experimental conditions. In this dissertation we proposed two methods to determine differentially expressed genes. For the penalized normal mixture model (PMMM) to determine genes that are differentially expressed, we penalized both the variance and the mixing proportion parameters simultaneously. The variance parameter was penalized so that the log-likelihood will be bounded, while the mixing proportion parameter was penalized so that its estimates are not on the boundary of its parametric space. The null distribution of the likelihood ratio test statistic (LRTS) was simulated so that we could perform a hypothesis test for the number of components of the penalized normal mixture model. In addition to simulating the null distribution of the LRTS for the penalized normal mixture model, we showed that the maximum likelihood estimates were asymptotically normal, which is a first step that is necessary to prove the asymptotic null distribution of the LRTS. This result is a significant contribution to field of normal mixture model. The modified p-value approach for detecting differentially expressed genes was also discussed in this dissertation. The modified p-value approach was implemented so that a hypothesis test for the number of components can be conducted by using the modified likelihood ratio test. In the modified p-value approach we penalized the mixing proportion so that the estimates of the mixing proportion are not on the boundary of its parametric space. The null distribution of the (LRTS) was simulated so that the number of components of the uniform beta mixture model can be determined. Finally, for both modified methods, the penalized normal mixture model and the modified p-value approach were applied to simulated and real data.
204

A proposed memory consistency model for Chapel

Srinivasa Murthy, Karthik, 1983- 20 December 2010 (has links)
A memory consistency model for a language defines the order of memory operations performed by each thread in a parallel execution. Such a constraint is necessary to prevent the compiler and hardware optimizations from reordering certain memory operations, since such reordering might lead to unintuitive results. In this thesis, we propose a memory consistency model for Chapel, a parallel programming language from Cray Inc. Our memory model for Chapel is based on the idea of multiresolution and aims to provide a migration path from a program that is easy to reason about to a program that has better performance efficiency. Our model allows a programmer to write a parallel program with sequential consistency semantics, and then migrate to a performance-oriented version by increasingly changing different parts of the program to follow relaxed semantics. Sequential semantics helps in reasoning about the correctness of the parallel program and is provided by the strict sequential consistency model in our proposed memory model. The performance-oriented versions can be obtained either by using the compiler sequential consistency model, which maintains the sequential semantics, or by the relaxed consistency model, which maintains consistency only at global synchronization points. Our proposed memory model for Chapel thus combines strict sequential consistency model, compiler sequential consistency model and relaxed consistency model. We analyze the performance of the three consistency models by implementing three applications: Barnes-Hut, FFT and Random-Access in Chapel, and the hybrid model of MPI and Pthread. We conclude the following: The strict sequential consistency model is the best model to determine algorithmic errors in the applications, though it leads to the worst performance; the relaxed consistency model gives the best performance among the three models, but relies on the programmer to enforce synchronization correctly; the performance of the compiler sequential model depends on accuracy of the dependence analysis performed by the compiler; the relative performance of the consistency models across Chapel and the hybrid programming model of MPI and Pthread are the same. This shows that our model is not tightly bound to Chapel and can be applied on other programming models/languages. / text
205

Persuasive Advertising : Consumers' views of and responses to the advertising of health-related products

Edin, Malin January 2012 (has links)
The problem that this thesis deals with is that the intense competition and increasing consumer power in the health industry calls for the operating companies to take consumers’ considerations into account when advertising their products. It is further suggested that consumers will be extra careful before buying health-related products due to their direct effect on their personal health. Thus, companies selling health-related products must gain an understanding of how consumers form their judgments of the advertisements for the same in order to be able to create persuasive and thus effective advertisements. The purpose of this thesis is to understand consumers’ views of different persuasion strategies used for advertising health-related products and how these affect their willingness to purchase the advertised product. This will be done as a means to provide the concerned companies with a basis for how to create positively perceived, yet effective, advertisements. In order to fulfill the purpose of this thesis a qualitative study was conducted through the use of focus groups. During the focus groups the participants were, among other things, encouraged to discuss their views of three different advertisements for health-related products. Each advertisement represented one persuasion strategy used in the advertising of health-related products. The gathered data was interpreted and analyzed by comparing it with theories from previous research. The study shows that consumers require extensive information and strong evidence behind the arguments provided in advertisements for health-related products. Advertisements that communicate consequences that correspond to consumers’ existing beliefs are likely to be positively perceived. Conversely, if the communicated consequences contradict consumers’ beliefs their responses are likely to be negative. Consumers that are more informed in regards to the products are more likely to critically judge the advertisements for the same. The likelihood that consumers’ attitudes will be reflected in their behavior increases along with the strength of their attitudes.
206

Evaluating Variance of the Model Credibility Index

Xiao, Yan 30 November 2007 (has links)
Model credibility index is defined to be a sample size under which the power of rejection equals 0.5. It applies goodness-of-fit testing thinking and uses a one-number summary statistic as an assessment tool in a false model world. The estimation of the model credibility index involves a bootstrap resampling technique. To assess the consistency of the estimator of model credibility index, we instead study the variance of the power achieved at a fixed sample size. An improved subsampling method is proposed to obtain an unbiased estimator of the variance of power. We present two examples to interpret the mechanics of building model credibility index and estimate its error in model selection. One example is two-way independent model by Pearson Chi-square test, and another example is multi-dimensional logistic regression model using likelihood ratio test.
207

Stability Selection of the Number of Clusters

Reizer, Gabriella v 18 April 2011 (has links)
Selecting the number of clusters is one of the greatest challenges in clustering analysis. In this thesis, we propose a variety of stability selection criteria based on cross validation for determining the number of clusters. Clustering stability measures the agreement of clusterings obtained by applying the same clustering algorithm on multiple independent and identically distributed samples. We propose to measure the clustering stability by the correlation between two clustering functions. These criteria are motivated by the concept of clustering instability proposed by Wang (2010), which is based on a form of clustering distance. In addition, the effectiveness and robustness of the proposed methods are numerically demonstrated on a variety of simulated and real world samples.
208

Žemsiurbės „Watermaster Classic III“ darbo efektyvumo įvertinimas / Dredger's "Wattermaster Classic III" work efficiency rating

Valančius, Lukas 21 June 2013 (has links)
Magistriniame darbe pateikta literatūros analizė, tyrimų tikslas ir uždaviniai, tyrimo metodika, tyrimų rezultatai ir jų analizė, išvados. Nustatyta, kad Lietuvoje ežerams valyti naudojamų žemsiurbių pagrindinis trūkumas yra siurbiama skysta pulpa ir mažas jos transportavimo atstumas. Tyrimų tikslas yra įvertinti dažniausiai naudojamos žemsiurbės „Watermaster Classic III“ tinkamumą ežerų valymui Lietuvoje. Tiesioginiais matavimais, trijuose pjūviuose, buvo nustatyti vandens gyliai išvalytose Masčio ežero ir Pakruojo tvenkinio dalyse. Suspenduotų dalelių kiekiui vandenyje nustatyti, iš Masčio ežero buvo paimti buteliu – batometru vandens mėginiai (iš karto baigus siurbimą), tūriniu būdu išmatuotas žemsiurbės našumas. Išmatavus vandens gylius, buvo atlikta aprašomoji stastika, kurios metu buvo pasitelkta „Hydrotech” bei “Microsoft Excel”programinė įranga. Autorius savo jėgomis atliko visus tyrimus. Nustatyta, kad valant Masčio ežero dalį žemsiurbe „Watermaster Classic III“, valymo tolygumas atskiruose pjūviuose siekė 8,1–10,2 %, žymiai prastesnis nei palyginimui Pakruojo tvenkinio dalyje, valant žemsiurbe „3350MK“ (tolygumas sieke 2,9–3,2 %). Esant darbinei konsistencijai 3,7 %, žemsiurbės „Watermaster Classic III“ našumas už 433 m siekė 76 %. Suspenduotų dalelių kiekis tik pirmą dieną prie žemsiurbės buvo žymiai didesnis už foninį lygį, už 10–20 m foninio lygio, o vėliau visur tapo foninio lygmens. Žemsiurbės „Watermaster Classic III“ dienos darbo laiko panaudojimo... [toliau žr. visą tekstą] / This Master's thesis presents the analysis of the literature, the aim and tasks of researches, the methodology, results, analysis and conclusions of the research. It was found that the main drawbacks of dredges which are cleaning lakes in Lithuania are the liquid pulp pumped and its low transportation distance. The aim of this research is to evaluate the most commonly used dredges’ “Watermaster Classic III” suitability for cleaning lakes in Lithuania. The water depths in three sections cleaned in Mastis and Pakruojis lakes were determined by direct measurements, to identify the quantity of suspended particles in the water in Mastis lake (immediately after dredging) water samples were taken with bottle – bathometer and the efficiency of dredge was evaluated using volumetric method. After measuring water death the descriptive statistic was carried out using “Hydrotech“ and “Microsoft Excel” software. All researches were made by author itself. It was found that dredging part of the lake Mastis with “Watermaster Classic III” cleaning uniformity in separate sections was 8.1 to 10.2% while cleaning the part of lake Pakruojis with the dredge „3350MK“ uniformity was significantly lower (2,9 to 3,2 %). In 3.7 % operating consistency “Watermaster Classic III” performance at 433 m was 76 %. The quantity of suspended particles only the first day around the dredge was significantly higher than the background level – 10-20 m above it but later everywhere became equal to background level... [to full text]
209

Maximum spacing methods and limit theorems for statistics based on spacings

Ekström, Magnus January 1997 (has links)
The maximum spacing (MSP) method, introduced by Cheng and Amin (1983) and independently by Ranneby (1984), is a general estimation method for continuous univariate distributions. The MSP method, which is closely related to the maximum likelihood (ML) method, can be derived from an approximation based on simple spacings of the Kullback-Leibler information. It is known to give consistent and asymptotically efficient estimates under general conditions and works also in situations where the ML method fails, e.g. for the three parameter Weibull model. In this thesis it is proved under general conditions that MSP estimates of parameters in the Euclidian metric are strongly consistent. The ideas behind the MSP method are extended and a class of estimation methods is introduced. These methods, called generalized MSP methods, are derived from approxima­tions based on sum-functions of rath order spacings of certain information mea­sures, i.e. the ^-divergences introduced by Csiszår (1963). It is shown under general conditions that generalized MSP methods give consistent estimates. In particular, it is proved that generalized MSP methods give L1 consistent esti­mates in any family of distributions with unimodal densities, without any further conditions on the distributions. Other properties such as distributional robust­ness are also discussed. Several limit theorems for sum-functions of rath order spacings are given, for ra fixed as well as for the case when ra is allowed to in­crease to infinity with the sample size. These results provide a strongly consistent nonparametric estimator of entropy, as well as a characterization of the uniform distribution. Further, it is shown that Cressie's (1976) goodness of fit test is strongly consistent against all continuous alternatives. / digitalisering@umu
210

Kūno kultūros mokytojų vidinės darnos, subjektyvios sveikatos ir gyvenimo būdo vertinimas pagal socialinius demografinius aspektus / Teacher‘s of physical education consistency internal, subjective health and lifestyle evaluation social demographic aspects

Klimaitė, Viktorija 06 September 2013 (has links)
Tyrimo objektas – vidinė darna, subjektyvus sveikatos ir gyvenimo būdo vertinimas. Tyrimo tikslas: Nustatyti kūno kultūros mokytojų vidinę darną, subjektyvų sveikatos ir gyvenimo būdo vertinimą pagal socialinius demografinius aspektus. Tyrimo uždaviniai: Ištirti kūno kultūros mokytojų vidinę darną pagal socialinius demografinius aspektus. Nustatyti kūno kultūros mokytojų subjektyvia sveikatą pagal socialinius demografinius aspektus. Nustatyti kūno kultūros mokytojų vidinę darną pagal gyvenimo būdą. Rezultatai: Nagrinėjant tyrime dalyvavusių pedagogų atsakymus apie jų gyvenimo būdą, nustatyti statistiškai reikšmingi vidinės darnos skirtumai tarp, dažnai ir retai ar visai nevartojančiųjų alkoholio. Rūkančių ir nerūkančių respondentų grupėse statistiškai reikšmingų skirtumų nestebima. Dažnai ir retai arba visai nevartojančių alkoholio respondentų grupėse, lyginant vidinės darnos ir jos komponentų vidurkius, nustatytas statistiškai reikšmingas prasmingumo jausmo komponento skirtumas. Galima daryti prielaidą, kad nevartojantys arba mažai vartojantys alkoholį pedagogai tiki, kad gyvenimas prasmingas. „Šio tyrimo metu nustatyta, kad blogiau besijaučiantys tirtieji pedagogai turi žemesnius vidinės darnos bei visų jos komponentų rodiklius. Šie rezultatai atitinka C. Hakansson ir kt. (2003) duomenis, kad subjektyviai vertinama gera sveikata yra susijusi su aukšta vidine darna, ir priešingai, subjektyviai vertinama bloga sveikata yra susijusi su žema vidine darna, depresija, įtampa... [toliau žr. visą tekstą] / Investigative object – sense of coherence, subjective health and lifestyle assessment. Investigative idea – identify physical education teachers to determine the internal consistency, a subjective assessment of the health and lifestyle assessment in the demographic aspects. Investigative proposition: 1. Investigative teacher‘s of physical education consistency internal by aspects to demographic socials 2. Identify teacher‘s of physical education subjective health by social, demographic aspects. 3. Identify teacher‘s of physical education consistency internal by lifestyle. Results: Examining teacher‘s answers about their lifestyle in investigate, determine consistency internal significant consistency internal statistic differencees by often and rarely doesn‘t use alcohol. Statistic diference a significal is not smoke and doesn‘t smoke groups to respondents. Respondents group not drink alcohol often or rare, compare consitency internal and average this components, identifical components by significal sence. Can say that teachers which not drink alcohol believe that life is sensible. Time to this investigative identify, the worse feel teachers to visited have consistency internal lower and all indicators by this components. This result match (C Hakansson 2003) infornation, good health assessed subjective is related with high consistency internal and different when good health assessed subjective is related with low consistency internal like depression, stress. (citation... [to full text]

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