• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 81
  • 39
  • 13
  • 11
  • 10
  • 6
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 183
  • 30
  • 27
  • 20
  • 20
  • 18
  • 16
  • 16
  • 16
  • 14
  • 12
  • 11
  • 11
  • 11
  • 10
  • 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

DD and WD costs : The development of a model for cutting costs in Dep. X

Hartvigson, Johannes, Cilingiroglu, Gunay, Palmén, Sara January 2008 (has links)
<p>This paper is an exploratory case study of a logistics cost problem at Dep. X, and the normative purpose is <strong>to develop a model for Dep. X to aid in solving the problem of large damage costs.</strong></p><p>Dep. X is the logistic department of a warehouse located in a midsized Swedish city. The warehouse is part of an international furniture chain that operates in more than 40 countries worldwide and has an annual turnover of 211 billion Swedish SEK. This company has a clear cost focus and therefore, it is very important for the different departments to keep costs at a minimum.</p><p>The problem that Dep. X is facing is related to damaged products, which can be further divided into Delivery Damages [DDs] (damages that are inflicted on products before the freight reaches the department) and Warehouse Damages [WDs] (damages that occur at the department). The warehouse has tried to solve the problem by forming a unit called ‘Cost hunters’. This group has some suspicions but has not yet found out the underlying reasons for the damaged goods. The thing that they know is that this is an unproportionally large cost for the warehouse, compared to other warehouses. In order for the researchers to investigate the cost issue, an abductive research strategy was used. The authors found out in an early stage of the research process that the problem was related to WDs and after a pre-study hypothesized four different problem areas to investigate:</p><ul type="disc"><li>Flaws in Communicating Knowledge</li><li>Flaws in Working Environment</li><li>Flaws in Motivation</li><li>Flaws Concerning Customers</li></ul><p>In order to establish whether or not these hypotheses were correct, a benchmarking study was conducted with a department under the same company, which was of basically the same size. Apart from the pre-study, a total of nine interviews were conducted; five at Dep. X and four at Dep. Y. The researchers also sent out surveys to both departments, conducted a damage levels study and had a meeting with a group manager at the distribution central in order to collect the needed information.</p><p>After data collection, the data were processed and analyzed, and the researchers came to the conclusion that the problem with high WDs at Dep. X was related to, firstly, flaws in communicating knowledge and flaws in the working environment. The two other problem areas, flaws in motivation and flaws concerning customers, were also to some extent related to WDs, but this impact was not considered enough to be a major cause. The authors finish the thesis by illustrating with a model how the problems seem to have arisen and by suggesting improvement areas to deal with in order to eliminate the cost issue.</p>
22

Quantum decoherence and time symmetry breaking : quantum-classical correspondence in non-adiabatic transitions /

Barsegov, Valeri Abulevich, January 2000 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 157-163). Available also in a digital version from Dissertation Abstracts.
23

Propiedades electrónicas y magnéticas en Polioxometalatos de Lindqvist y de Keggin.

Maestre Horcajo, Joan Miquel 06 October 2003 (has links)
Optimizaciones geométricas fueron llevadas a cabo con las formas cis y trans del anión [Nb2W4O19]4-. También fueron estudiadas para la forma cis varios isómeros del anión [Nb2W4O19H]3-, sugiriendo que el oxígeno enlazado a los dos átomos de Nb es el centro más básico. La determinación energética de las basicidades de los oxígenos en los hexametalatos fueron comparadas con la metodología de la distribución del potencial electrostático molecular, que es más económica computacionalmente. En el anión [V2W4O19]4-, el único OV2 fue identificado como el centro más básico. Aunque con el anión niobiotungstato, el centro más básico no soporta la carga negativa más alta.Cálculos basados en la teoría del funcional de la densidad ha sido llevados a cabo para investigar las propiedades electrónicas y magnéticas de los aniones &#61537;-Keggin: [XW12O40]n-, (M= W, Mo; X= AlIII, SiIV, PV, FeIII, CoII, CoIII) y [SiM11VO40]m- (M=Mo y W). La población atómica y la distribución de la densidad electrónica calculada en los clusters estudiados mantienen la hipótesis que un anión Keggin oxidado es un clatrato XO4n- en el interior de una caja neutra M12O36. El intervalo de energía entre la banda de orbitales ocupados, formalmente deslocalizados en los ligandos oxo, y los orbitales vacíos d metálicos, deslocalizados sobre la caja, se ha encontrado independiente del ion central. Sin embargo, la substitución de un W o un Mo por un V modifica la energía relativa del LUMO y por consiguiente induce importantes cambios en las propiedades redox del cluster. De acuerdo con la más reciente determinación de rayos X del [CoIIIW12O40]5- y con la simplicidad del espectro observado para este anión, los cálculos sugieren que tiene una ligera geometría distorsionada Td. Para el cluster derivado [CoW12O40]6- el cuadruplete correspondiente al anión encapsulando un CoII, se ha hallado 1 eV más estable que la especie formada por un CoIII y 1 e deslocalizado en la pseudoesfera de los tungstenos. La reducción monoelectrónica del [CoIIW12O40]6- y [FeIIIW12O40]5- lleva a la formación de las especies "blue" 1e [CoIIW12O40]7- y [FeIIIW12O40]6-. El cluster "blue" de hierro es considerablemente antiferromagnético, y está en completa concordancia con este resultado el estado de bajo espín calculado con la aproximación "Broken Symmetry ", siendo 196 cm-1 más bajo que la solución de alto espín. Por el contrario, el anión "blue" de cobalto tiene un bajo acoplamiento ferromagnético con una diferencia S-T de 20 cm-1.[PMo12O40(VO)2]5- es un cluster altamente reducido con ocho electrones metálicos d. La naturaleza de la localización-deslocalización de los electrones d metálicos es uno de los puntos de interés de los polioxoaniones reducidos. Hemos llevado a cabo cálculos DFT que sugieren que el estado de oxidación de los átomos V es +4 y los otros seis electrones metálicos están deslocalizados entre los doce átomos de Mo. Los cálculos también proponen la evidencia de que el anión [PMo12O40(VO)2]5- debería ser paramagnético. El entorno cristalino fue introducido en los cálculos por medio de dos modelos, incrementando la tendencia a tener electrones metálicos.Los multipletes derivados de varias configuraciones excitadas del [CoIIW12O40]6- fueron calculadas usando métodos DFT. De acuerdo con la interpretación experimental del espectro, los cálculos hallan que la primera gran banda corresponde a las transiciones d-d del Co, pero es de destacar que superpuestas a estas transiciones se encuentran las transiciones de tranferencia de carga del cobalto a los wolframios. Los cálculos también demuestran la importancia de las distorsiones Jahn-Teller en los estados excitados. Con la excepción de las consecuencias derivadas de una pequeña diferencia de los orbitales d del cobalto, el espectro d-d del [CoCl4]2- es similar al del complejo del anión de Keggin. Finalmente, la energía de la transición bielectrónica fue estimada por un procedimiento basado en la teoría del campo ligando. / Geometry optimizations were carried out for the cis and trans forms of [Nb2W4O19]4-. Several isomers of the [Nb2W4O19H]3- anion were also studied for the cis form, suggesting that the oxygen bonded to two Nb atoms is the most basic center. The energetic determination of the oxygen basicities in hexametalates was compared with the indirect and less computationally demanding methodology based upon molecular electrostatic potential distributions. In [V2W4O19]4-, the unique OV2 was identified as the most basic center. Although at variance with the niobotungstate anion, the most basic center does not support the highest net negative charge.Calculations based on density functional theory have been carried out to investigate the electronic and magnetic properties of the &#61537;-Keggin anions: [XW12O40]n-, (M= W, Mo; X= AlIII, SiIV, PV, FeIII, CoII, CoIII) and [SiM11VO40]m- (M=Mo and W). The atomic populations and the distribution of the electron density computed for the studied clusters support the hypothesis that an oxidized Keggin anion is an XO4n- clathrate inside a neutral M12O36 cage. The energy gap between the band of occupied orbitals, formally delocalized over the oxo ligands, and the unoccupied d-metal orbitals, delocalized over the addenda, has been found to be independent of the central ion. However, substitution of a W or a Mo by V modifies the relative energy of the LUMO and then induces important changes in the redox properties of the cluster. In agreement with the most recent X-ray determination of [CoIIIW12O40]5- and with the simplicity of the spectra observed for this anion the calculations suggest that was a slightly distorted Td geometru. For the parent cluster [CoW12O40]6- the quadruplet corresponding to the anion encapsulating a CoII was found to be 1 eV more stable than the species formed by a CoIII and 1 e delocalized over the sphere of tungstens. The one-electron reduction of [CoIIW12O40]6- and [FeIIIW12O40]5- leads to the formation of the 1 e blue species [CoIIW12O40]7- and [FeIIIW12O40]6-. The blue-iron cluster is considerably antiferromagnetic, and in full agreement with this behavior the low-spin state computed via a Broken Symmetry approch is 196 cm-1 lower than the high-spin solution. In contrast, the cobalt blue anion has a low ferromagnetic coupling with an S-T energy gap of +20 cm-1.[PMo12O40(VO)2]5- is a highly reduced cluster with eight d metal electrons. The localization-delocalization nature of d metal electrons is one of the points of interest in reduced polyoxoanions. We report DFT calculations wich suggest that the oxidation state of the V atoms is +4 and the other six metal electrons are delocalized between the 12 Mo atoms. The calculations also provide evidence that the anion [PMo12O40(VO)2]5- should be paramagnetic. The crystal environment, wich was included in the calculations by means of two models, increases the tendency to have metal electrons.Multiplet splittings for several excited configurations of [CoIIW12O40]6- were calculated using DFT methods. In agreement with the experimental interpretation of the spectrum the calculations found that the first strong band corresponds to Co d-d transitions, but it is worth noting that superposed to these transitions there are charge transfer transitions from cobalt to tungsten. The calculations also showed the importance of Jahn-Teller distortions in the excited states. With the exception of the consequences derived from a smaller splitting of d cobalt orbitals the d-d spectrum of [CoCl4]2- is similar to that of the more complex Keggin anion. Finally, the energy of the bielectronic transition 4A2&#61664;4T1(P) was estimated via an approximate procedure based on ligand field theory.
24

The pion-nucleon sigma term and the SU(3) Cloudy Bag Model / by Iain Jameson

Jameson, Iain January 1991 (has links)
Bibliography : leaves 135-146 / vii, 146 leaves ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1991
25

Investigation of single and multiple faults under varying load conditions using multiple sensor types to improve condition monitoring of induction machines.

Ahmed, Intesar January 2008 (has links)
Condition monitoring involves taking measurements on an induction motor while it is operating in order to detect faults. For this purpose normally a single sensor type, for example current is used to detect broken rotor bar using fault frequency components only under the full-load condition or a limited number of load cases. The correlations among the different types of sensors and their ability to diagnose single and multiple faults over a wide range of loads have not been the focused in previous research. Furthermore, to detect different faults in machines using any fault frequency components, it is important to investigate the variability in its amplitude to other effects apart from fault severity and load. This area has also often been neglected in the literature on condition monitoring. The stator current and axial flux have been widely used as suitable sensors for detecting different faults i.e. broken rotor bar and eccentricity faults in motors. Apart from detecting the broken rotor bar faults in generalized form, the use of instantaneous power signal has often been neglected in the literature condition monitoring. This thesis aims to improve machine condition monitoring and includes accurate and reliable detection of single and multiple faults (faults in the presence of other faults) in induction machines over a wide range of loads of rated output by using current, flux and instantaneous power as the best diagnostic medium. The research presents the following specific tasks: A comprehensive real database from non–invasive sensor measurements, i.e. vibration measurements, axial flux, 3-phase voltage, 3-phase current and speed measurements of induction motor is obtained by using laboratory testing on a large set of identical motors with different single and multiple faults. Means for introducing these faults of varying severity have been developed for this study. The collected data from the studied machines has been analysed using a custom-written analysis programme to detect the severity of different faults in the machines. This helps to improve the accuracy and reliability in detecting of single and multiple faults in motors using fault frequency components from current, axial flux and instantaneous power spectra. This research emphasises the importance of instantaneous power as a medium of detecting different single and multiple faults in induction motor under varying load conditions. This enables the possibility of obtaining accurate and reliable diagnostic medium to detect different faults existing in machines, which is vital in providing a new direction for future studies into condition monitoring. Another feature of this report is to check the variability in healthy motors due to: test repeatability, difference between nominally identical motors, and differences between the phases of the same motor. This has been achieved by conducting extensive series of laboratory tests to examine fault frequency amplitudes versus fault severity, load, and other factors such as test repeatability and machine phases. The information about the variations in the amplitudes of the fault frequency components is used to check the accuracy and reliability of the experimental set-up, which is necessary for the practical application of the results to reliably detect the different faults in the machines reliably. Finally, this study also considers the detection of eccentricity faults using fault frequency amplitudes as a function of average eccentricity, instead of as a function of load under different levels of loading. This has not been reported in previous studies. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1298314 / Thesis (Ph.D.)-- University of Adelaide, School of Electrical and Electronic Engineering, 2008
26

A biblical approach to Christian marriage and the broken family

Yoo, Hong Sun, January 1998 (has links)
Thesis (Th. M.)--Gordon-Conwell Theological Seminary, South Hamilton, Mass., 1998. / Abstract and vita. Includes bibliographical references (leaves 110-116).
27

Silent wounds of the family

Alais, Georgina. January 2008 (has links)
Thesis (MArch(Prof)) -- University of Pretoria, 2008. / Includes bibliographical references.
28

Caos e termalização na teoria de Yang-Mills com quebra espontânea de simetria

Woitek Junior, Marcio [UNESP] 27 September 2011 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:25:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-09-27Bitstream added on 2014-06-13T19:12:27Z : No. of bitstreams: 1 woitekjunior_m_me_ift.pdf: 9022411 bytes, checksum: 88726cc3ceec91a0d503f0b0557e5add (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Uma das características mais importantes das teorias de gauge não-Abelianas é a não-linearidade das equações de campo clássicas. Mostra-se no contexto da teoria de Yang-Mills que essa característica pode fazer com que o campo de gauge apresente comportamento caótico. Isso pode acontecer mesmo quando estivermos considerando a dinâmica do campo na ausência de fontes, isto é, o vácuo da teoria de Yang-Mills. Discutimos a relação entre os comportamentos caótico e ergódico. Em seguida, introduzimos a formulação de Berdichevsky da Mecânica Estatística Clássica para sistemas dinâmicos Hamiltonianos que são ergódicos e possuem poucos graus de liberdade. A Mecânica Estatística de Berdichevsky é usada para estudar a situação mais simples numa teoria de gauge não-Abeliana onde as variáveis de campo são caóticas e o espaço de fase correspondente tem a propriedade geométrica necessária. Mostramos que, para os propósitos desse estudo, um par de campos escalares complexos deve ser incluído no problema. Mais precisamente, analisamos o modelo de Higgs não-Abeliano; a Lagrangiana da teoria considerada possui uma simetria SU(2). A transição de uma descrição dinâmica do sistema de YangMills-Higgs (fora do equilíbrio termodinâmico) para uma descrição termodinâmica (quando ele atingiu o equilíbrio) é investigada numericamente. Mostra-se que depois de um tempo suficientemente longo as soluções numéricas se comportam de tal maneira que o sistema pode ser descrito de um jeito mais simples através de grandezas como a temperatura, calculadas de acordo com as prescriçõees da Mecânica Estatística de equilíbrio. Estas são previstas analiticamente para comparção com os resultados numéricos... / One of the most important features of non-Abelian gauge theories is the non-linearity of the classical field equations. In the context of Yang-Mills theory it is shown that this feature can cause the gauge field to show chaotic behavior. That can happen even when we are considering the field dynamics in the absence of sources, i.e., the vacuum of the Yang-Mills theory. We discuss the connection between chaotic and ergodic behaviors. Then we introduce Berdichevsky’s formulation of Classical Statistical Mechanics for Hamiltonian dynamical systems that are both ergodic and low-dimensional. Berdichevsky’s theory of Statistical Mechanics is used to study the simplest situation in a non-Abelian gauge theory where the field variables are chaotic and the corresponding phase space has the necessary geometric property. We show that, for the purposes of this study, a pair of complex scalar fields must be introduced in the problem. More precisely, we analyse the so-called non-Abelian Higgs model; the Lagrangian of the theory we are considering has a SU(2) symmetry. The transition from a non-equilibrium dynamical description of the Yang-Mills-Higgs system to a thermodynamical description when it reaches equilibrium is numerically investigated. It is shown that after a sufficiently long time the numerical solutions behave in such a manner that the system can be described by quantities like the temperature, determined in accordance with the prescriptions of equilibrium Statistical Mechanics. These are predicted analytically for comparison with the numerical results. It is verified that there is agreement between analytical and numerical predictions so that the thermalization of the Yang-Mills-Higgs system can be explained with the aid of Berdichevsky’s Statistical Mechanics. A dynamical approach to the study... (Complete abstract click electronic access below)
29

Modelos para estimar as exigências de lisina digestível para poedeiras comerciais

Venturini, Katiani Silva [UNESP] 19 September 2011 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:27:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-09-19Bitstream added on 2014-06-13T20:36:04Z : No. of bitstreams: 1 venturini_ks_me_jabo.pdf: 745934 bytes, checksum: 1fe3bdca04c6feb5d07d43cf26fdaece (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O experimento teve por objetivo estimar exigências em lisina digestível para poedeiras utilizando a metodologia dose-resposta e fatorial (modelo de “Reading”). Foram utilizadas 384 aves da linhagem Dekalb White. O delineamento utilizado foi o inteiramente casualizado, constituído de oito tratamentos, seis repetições, com oito aves por unidade experimental. As respostas para produção, massa de ovos, conversão alimentar por massa e dúzia de ovos foram ajustadas de acordo com o consumo de lisina pelos modelos broken line e polinomial quadrático por cada período experimental (28 dias). A partir das resposta de lisina para os coeficientes de massa de ovos e peso corporal, foi proposto modelos fatoriais para cada período experimental. Para avaliar a aplicabilidade dos modelos foi gerada uma simulação aleatória com 5000 individuos. A exigência estimada de lisina de acordo com a combinação do modelo broken line e quadrático para massa de ovos, no primeiro (33-36 semanas), segundo (37-40 semanas), terceiro (41-44 semanas) e quarto (45-48 semanas) período foram respectivamente, 632; 718; 699 e 684 mg/ave/dia. Enquanto na conversão alimentar por massa de ovos estimou-se 606; 552; 594 e 577 mg/ave/dia para o primeiro, segundo, terceiro e quarto período respectivamente. A conversão alimentar por dúzia de ovos forneceu a estimativa de consumo de lisina de 575; 577; 590 e 564 mg/ave/dia, respectivamente para o primeiro, segundo, terceiro e quarto período experimental. As estimativas médias de lisina encontradas pelo modelo de “Reading” para o primeiro, segundo, terceiro e quarto período foram respectivamente 495; 598; 565 e 575 mg/ave/dia. O nível ótimo econômico para o primeiro, segundo, terceiro e quarto período, respectivamente foi de 590, 778, 601 e 715 mg/ave/dia / The experiment aimed at estimating lysine requirements for laying hens using the methodology and factorial dose-response model (Reading). 384 birds were used Dekalb strain of White. The design was completely randomized, consisting of eight treatments, six replicates of eight birds each. The answers to production, egg mass, feed conversion per dozen eggs and mass were adjusted according to the consumption of lysine by the broken line model and quadratic polynomial for each experimental period (28 days). From the response of lysine to the coefficients of egg mass and body weight, was proposed factor models for each trial. To evaluate the applicability of a simulation model was generated with 5000 random individuals. The estimated lysine requirement according to the combination of the broken line and quadratic model for egg mass in the first (33-36 weeks), second (37-40 weeks), third (41-44 weeks) and fourth (45 - 48 weeks) period were respectively 632, 718, 699 and 684 mg / bird / day. While feed conversion per egg mass was estimated 606, 552, 594 and 577 mg/bird/day for the first, second, third and fourth quarter respectively. Feed per dozen eggs provided the estimate of lysine intake of 575, 577, 590 and 564 mg/bird/day, respectively for first, second, third and fourth trial. The average estimates of lysine found by the model of Reading for the first, second, third and fourth period were respectively 495, 598, 565 and 575 mg/bird/day. The economic optimum level for the first, second, third and fourth period, respectively was 590, 778, 601 and 715 mg/bird/day
30

Use of recycled broken bricks as Partial Replacement Coarse Aggregate for the Manufacturing of Sustainable Concrete

Pinchi, S., Pinchi, S., Ramírez, J., Rodríguez, J., Eyzaguirre, C. 28 February 2020 (has links)
The bricks are one of the primary materials required for construction of homes that no used completely when executes all the walls due, the excess purchase, the cutting to be settle, the breaking for their transfer and its fixed dimensions; this situation requires monitoring on work site the order, cleanliness and accidents. A common practice is these bricks and/or waste are included in the clearing construction before being deposited or eliminated in dumps or sanitary landfills, with their early clogging and shortening them to ther design lifespan. An important alternative to reduce this waste, is to recycle them and reuse them as a concrete component material, due to their high absorption percentage that allows them to keep the water inside of them and then use it in the cement hydration process as internal curing of the concrete. In the present investigation, the effect of crushed clay brick as a replacement for coarse aggregate in concrete processing is studied. The results indicate that with 21 % replacement brick, the plastic contraction decreases, and the compressive strength and flexural strength increase.

Page generated in 0.0207 seconds