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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.
211

Imčių iš baigtinių visumų statistikos tikimybiniai skirstiniai / Probability distributions of samples statistics from finite populations

Pranskūnaitė, Arūnė 20 June 2012 (has links)
Nagrinėjama silpnai priklausomų atsitiktinių dydžių statistika. Šio magistrinio darbo tikslas, turimą sumą, suvesti į nepriklausomų atsitiktinių dydžių sumą, kuri leistų tolimesniam tyrimui, pritaikyti žinomas teoremas, skaičiavimus bei rezultatus iš nepriklausomų atsitiktinių dydžių teorijos. / We analyze of weakly dependent random variables statistics. The objective of this master thesis is to deduce sum to independent random variables sum, which will be useful for applaying known theorems, calculations and results from the theory in independent random variables.
212

Smėlio dalelių formos įtaka deformacinėms savybėms / Influence of grains shape for mechanical properties of sands

Šlečkuvienė , Agata 17 June 2013 (has links)
Baigiamajame magistro darbe nagrinėjama gruntų morfologinės struktūros įtaka jų suspaudžiamumui. Darbą sudaro teorinė ir praktinė dalys. Teorinėje dalyje detaliai aprašomas gruntų morfologinės struktūros nustatymo tyrimams taikytas metodas, aptariami jo trūkumai ir privalumai, pateikiamos visos morfologiniams parametrams apskaičiuoti taikytos formulės. Atlikta gruntų morfologinės struktūros įtakos suspaudžiamumui teorijos apžvalga. Trumpai paaiškinama, pagal kokius kriterijus bandymams buvo pasirenkami gruntai. Praktinėje dalyje aprašomi gruntų granuliometrinės sudėties, morfologinės struktūros nustatymo bei spūdumo bandymų rezultatai. Išsamiai aprašoma kiekvieno praktinės dalies eksperimento eiga, problemos, su kuriomis buvo susiduriama darbo metu. Atlikta gautų rezultatų analizė, kurioje aptariama morfologinės struktūros įtaka gruntų suspaudžiamumui. Pagal šią analizę formuluojamos išvados ir teikiami pasiūlymai tolesniam darbui bei gautų rezultatų patikslinimui. Darbą sudaro 6 pagrindinės dalys: įvadas, literatūros apžvalga, eksperimentiniai tyrimai, rezultatų analizė, bendros išvados ir priedai. Darbo apimtis – 75 p. teksto be priedų, 43 p. priedų, 37 literatūros šaltiniai, 33 paveikslai ir 15 lentelių. / The master thesis purpose is to determine the influence of particle shape on the mechanical properties of sand. The work consists of theoretical and practical parts. The theoretical part describes the applied method for evaluating morphometric characteristics of particles. Also the discussion of advantages and disadvantages of this method and overview of theory of influence of particle shape on soil compressibility were made. Finally the criteria for choosing soils for research was discussed. In practical part of this thesis the results of experimental investigations were introduced. Firstly the evaluating of soil grading and estimation of morphometric characteristic of its particles were made. In order to determine the influence of morphometric characteristic on sands compressibility the oedometer tests was performed. Also there are introduced detailed courses of all experimental investigations and problems which have been encountered during processes. After all experimental investigations the analysis of results were made. According to this analysis, conclusions and proposals for further work and clarification of the results were obtained. The thesis consists of six basic parts such as introduction, literature review, experimental researches, analysis of researches data, conclusions and proposals, accessories. The final work consists of 75 p. of text without appendixes, 43 p. of appendixes, 37 bibliographical entries. 33 pictures, 15tables.
213

Rational Points of Universal Curves in Positive Characteristics

Watanabe, Tatsunari January 2015 (has links)
<p>For the moduli stack $\mathcal{M}_{g,n/\mathbb{F}_p}$ of smooth curves of type $(g,n)$ over Spec $\mathbb{F}_p$ with the function field $K$, we show that if $g\geq3$, then the only $K$-rational points of the generic curve over $K$ are its $n$ tautological points. Furthermore, we show that if $g\geq 3$ and $n=0$, then Grothendieck's Section Conjecture holds for the generic curve over $K$. A primary tool used in this thesis is the theory of weighted completion developed by Richard Hain and Makoto Matsumoto.</p> / Dissertation
214

Polytopes Arising from Binary Multi-way Contingency Tables and Characteristic Imsets for Bayesian Networks

Xi, Jing 01 January 2013 (has links)
The main theme of this dissertation is the study of polytopes arising from binary multi-way contingency tables and characteristic imsets for Bayesian networks. Firstly, we study on three-way tables whose entries are independent Bernoulli ran- dom variables with canonical parameters under no three-way interaction generalized linear models. Here, we use the sequential importance sampling (SIS) method with the conditional Poisson (CP) distribution to sample binary three-way tables with the sufficient statistics, i.e., all two-way marginal sums, fixed. Compared with Monte Carlo Markov Chain (MCMC) approach with a Markov basis (MB), SIS procedure has the advantage that it does not require expensive or prohibitive pre-computations. Note that this problem can also be considered as estimating the number of lattice points inside the polytope defined by the zero-one and two-way marginal constraints. The theorems in Chapter 2 give the parameters for the CP distribution on each column when it is sampled. In this chapter, we also present the algorithms, the simulation results, and the results for Samson’s monks data. Bayesian networks, a part of the family of probabilistic graphical models, are widely applied in many areas and much work has been done in model selections for Bayesian networks. The second part of this dissertation investigates the problem of finding the optimal graph by using characteristic imsets, where characteristic imsets are defined as 0-1 vector representations of Bayesian networks which are unique up to Markov equivalence. Characteristic imset polytopes are defined as the convex hull of all characteristic imsets we consider. It was proven that the problem of finding optimal Bayesian network for a specific dataset can be converted to a linear programming problem over the characteristic imset polytope [51]. In Chapter 3, we first consider characteristic imset polytopes for all diagnosis models and show that these polytopes are direct product of simplices. Then we give the combinatorial description of all edges and all facets of these polytopes. At the end of this chapter, we generalize these results to the characteristic imset polytopes for all Bayesian networks with a fixed underlying ordering of nodes. Chapter 4 includes discussion and future work on these two topics.
215

Job and home characteristics, negative work-home interaction and ill-health of employed females in South Africa / Zoe Roux

Roux, Zoe January 2007 (has links)
In the last few years, many more women than before have entered the labour force. Consequently, employed women are confronted with demanding aspects at work and at home and experience difficulty in combining obligations in both of these domains. The pressure of the demands in their work place and family lives combined with managing the responsibilities from their work and personal lives can have a negative impact on the health of employed females. The objective of this research was to investigate the effects of work characteristics, borne characteristics and negative work-home interaction on the ill-health of employed females in South Africa. An availability sample (N = 500) was taken from six provinces of South Africa, including the Eastern Cape, the Free State, Gauteng, KwaZulu Natal, the North West and Western Cape. A job characteristics questionnaire, a home characteristics questionnaire, the 'Survey Work-Home Interaction Nijmegen' (SWING), and an ill health questionnaire were administered. Exploratory factor analyses were used to determine the construct validity of the questionnaires, Cronbach alpha coefficients were used to determine the reliability, while multiple regression analyses were used to identify significant predictors of ill-health. The results indicated that physical ill health could be predicted by a lack of role clarity and pressures at home. Predictors of anxiety were work overload, a lack of support from colleagues, uncertain roles in the workplace, home pressure as well as negative Work-home interaction (WHI) and negative Home-work interaction (HWI). Fatigue was predicted by work pressure, work overload, a lack of autonomy at work, a lack of instrumental support at work, a lack of role clarity, pressure at home and negative WHI. Predicting factors of depression were found to be job insecurity, a lack of autonomy and clearly defined roles at work, pressure at home, a lack of autonomy at home as well as negative HWI. / Mini-dissertation (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2007.
216

High-resolution three-dimensional plume modeling with Eulerian atmospheric chemistry and transport models

Garcia Menendez, Fernando 13 January 2014 (has links)
Eulerian chemical transport models are extensively used to steer environmental policy, forecast air quality and study atmospheric processes. However, the ability of these models to simulate concentrated atmospheric plumes, including fire-related smoke, may be limited. Wildland fires are important sources of air pollutants and can significantly affect air quality. Emissions released in wildfires and prescribed burns have been known to substantially increase the air pollution burden at urban locations across large regions. Air quality forecasts generated with numerical models can provide valuable information to environmental regulators and land managers about the potential impacts of fires. Eulerian models present an attractive framework to simulate the transport and transformation of fire emissions. Still, the limitations inherent to chemical transport models when applied to replicate smoke plumes must be identified and well understood to adequately interpret results and further improve the models' predictive skills. Here, a modeling framework centered on the Community Multiscale Air Quality modeling system (CMAQ) is used to simulate several fire episodes that occurred in the Southeastern U.S. and investigate the sensitivity of fine particulate matter concentration predictions to various model inputs and parameters. Significant sources of uncertainty in the model are identified and discussed, including the spatiotemporal allocation of fire emissions and meteorological drivers. In addition, special attention is given to model grid resolution. Adaptive grid modeling is explored as a strategy to simulate fire-related plumes. An adaptive version of CMAQ, capable of dynamically restructuring the grid on which solution fields are estimated and providing refinement at the regions where accuracy is most dependent on resolution, is presented. The fully adaptive three-dimensional modeling technique can be applied to reach unprecedented levels of grid resolution and provide insight into plume dynamics unattainable with static grid models. Through this work the capability of current chemical transport models to replicate fire-related air quality impacts is evaluated, key research needs to achieve effective simulations are identified, and numerical tools designed to improve model performance are developed.
217

The Effect of Temperature on the SWCC and Estimation of the SWCC from Moisture Profile under a Controlled Thermal Gradient

Roshani, Pedram 08 May 2014 (has links)
In many situations, the upper layers of soil above the ground water table are in a state of unsaturated condition. Although unsaturated soils are found throughout the world, they are predominant in arid or semi-arid regions. In these areas, the soil water characteristic curve (SWCC) which relates the water content to the matric suction could be used as key tool to implement the mechanics of unsaturated soils into the designs of geotechnical structures such as dams, embankments, pavements, canals, and foundations. Several experimental techniques are available for determining the SWCC in a laboratory environment. However, these experimental techniques are expensive, time consuming typically requiring days or weeks, depending on the soil type, and demanding intricate testing equipment. Due to these reasons, there has been a growing interest to find other means for estimating SWCC and encourage the adoption of unsaturated soils mechanics in geotechnical engineering practice. Several methods exist to indirectly estimate the SWCC from basic soil properties. Some may include statistical estimation of the water content at selected matric suction values, correlation of soil properties with the fitting parameters of an analytical equation that represents the SWCC, estimation of the SWCC using a physics-based conceptual model, and artificial intelligence methods such as neural networks or genetic programming. However, many studies have shown that environmental effects such as temperature, soil structure, initial water content, void ratio, stress history, compaction method, etc. can also affect the SWCC. This means that the estimation SWCC from set of conditions may not reliably predict the SWCC in other conditions. Due to this reason, it is crucial for engineers involved with unsaturated soils to take into account all the factors that influence the SWCC. The two key objectives of the present thesis are the development of a method based on first principles, using the capillary rise theory, to predict the variation of the SWCC as a function of temperature, as well as developing a technique for the prediction of the fixed parameters of a well-known function representing the SWCC based on basic soil properties together with the moisture profile of a soil column subjected to a known temperature gradient. A rational approach using capillary rise theory and the effect of temperature on surface tension and liquid density is developed to study the relation between temperature and the parameters of the Fredlund and Xing (1994) equation. Several tests, using a Tempe cell submerged in a controlled temperature bath, were performed to determine the SWCC of two coarse-grained soils at different temperatures. A good comparison between the predicted SWCC at different temperatures using the proposed model and the measured values from the Tempe cell test results is achieved. Within the scope of this thesis, a separate testing program was undertaken to indirectly estimate the SWCC of the same two coarse-grained soils from the measurement of their steady state soil-moisture profile while subjected to a fixed temperature differences. The water potential equation in the liquid and vapor phases is used to analyses the steady state flow conditions in the unsaturated soil. A good comparison is obtained for the SWCC estimated using this technique with the SWCC measured used a Tempe cell submerged in a controlled temperature bath. The results of this study indicate that knowledge of the moisture content of a soil specimen under a constant thermal gradient and basic soil properties can be used to estimate the SWCC of the soil at the desired temperature.
218

Synthesis, Characterization And Electrical Properties Of Diazophenylene And Diazodiphenylene Bridged Co, Ni, Cu, Ce, And Er Phthalocyanine Polymers

Alkan, Cemil 01 September 2004 (has links) (PDF)
SYNTHESIS, CHARACTERIZATION, AND ELECTRICAL PROPERTIES OF DIAZOPHENYLENE AND DIAZODIPHENYLENE BRIDGED Co, Ni, Cu, Ce, AND Er PHTHALOCYANINE POLYMERS Alkan, Cemil M. Sc., Department of Polymer Science and Technology Supervisor: Prof.Dr. Leyla Aras Co- Supervisor: Prof.Dr. G&uuml / ng&ouml / r G&uuml / nd&uuml / z September 2004, 112 pages In this research, diazophenylene and diazodiphenylene bridged metal-phthalocyanine polymers were produced from diazonium salt of diaminophenylene/bensidin and pre-synthesized tetraamino metal phthalocyanines. Tetraamino metal phthalocyanine complexes of Co, Ni, Cu, Ce, and Er were obtained by reducing tetranitro metal phthalocyanine complexes synthesized from 3-nitrophthalic anhydride, urea, metal salt, and ammonium molybdate catalyst. Complexes and polymers were characterized by Fourier Transform Infrared Radiation (FTIR) and UV-Visible spectroscopies. X-Ray analysis showed that there were short range orientations in the polymers. Thermal analysis of the complexes and the polymers were done by differential scanning calorimetry and thermal gravimetric analysis at a heating rate of 10&amp / #61616 / Cmin&amp / #61485 / 1 under nitrogen atmosphere. Ash analysis was performed to determine the metal content of the polymers. Viscosity and ebullioscopy measurements of the soluble part of the polymers were carried out in THF at 25&amp / #61616 / C. Scanning electron microscopy were used for morphology investigations of the polymers. Four probe conductivity measurements showed that electrical conductivity of the polymers increased according to the metallic conductivity of the metal at the center of the phthalocyanine units. When doped with iodine, the polymer samples showed 104 fold increase in their conductivities. Current-Voltage (I-V) measurements showed that the polymers were optically sensitive and semiconductors. Electrochemical analysis of the soluble part of the polymers were determined in tributylamine perchlorite+dichloromethane mixture utilizing cyclic voltammetry (CV).
219

Evaluation of a neural network classifier for pancreatic masses based on CT findings

池田, 充, Ikeda, Mitsuru, 伊藤, 茂樹, Ito, Shigeki, 石垣, 武男, Ishigaki, Takeo, Yamauchi, Kazunobu, 山内, 一信 05 1900 (has links)
No description available.
220

Personlig motivation i agil projektledning : En fallstudie på Kambi Sports Solutions AB

Vaarala, Robert, Svernell, Johan January 2013 (has links)
Syftet med studien är att undersöka huruvida det är mer eller mindre motiverande för anställda inom mjukvaruindustrin att jobba enligt agila utvecklingsmetoder än enligt traditionella utvecklingsmetoder. Undersökningen har gjorts med teoretisk utgångspunkt från motivationsskapande variabler ur de kontemporära motivationsteorierna Self Determination Theory samt Job Characteristic model. Som en ansats till att besvara frågeställningen har en kvalitativ fallstudie genomförts på företaget Kambi Sport Solutions AB. Kambi Sport Solutions AB har under de senaste åren genomfört en organisationsförändring där traditionella projektledningsmetoder ersatts av agila projektledningsmetoder. Studiens empiri visar med stöd ur motivationsteori att övergången till agila metoder signifikant påverkat individens motivation positivt. Framförallt som en följd av en högre grad av självbestämmande, kunskapsvariation, identitet i och betydelse av arbetsuppgiften, autonomi samt feedback.

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