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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.
1

Funds allocation in NPOs: the role of administrative cost ratios

Burkart, Christian, Wakolbinger, Tina, Toyasaki, Fuminori 27 June 2018 (has links) (PDF)
Performance measurement of Non-Profit Organizations (NPOs) is of increasing importance for aid agencies, policy-makers and donors. A widely used benchmark for measuring the efficiency of NPOs is the overhead cost ratio, consisting of the total money spent on administration and fundraising relative to the budget. Donors generally favor a lower overhead cost ratio as it ensures that more Money directly reaches beneficiaries. Unlike fundraising expenses, administrative costs do not contribute to advertising the actions of an NPO even though they account for a significant proportion of overhead cost. Reducing administrative expenses is a logical consequence from a financial viewpoint, but might negatively affect NPOs through the resulting administrative capacities. This phenomenon is known as "Nonprofit Starvation Cycle" This work provides an analytical framework for analyzing NPO decision making concerning administrative costs. The paper provides answers to important research questions on the optimal level of administrative spending, the influencing factors and the effects of available information on NPOs. The research shows that focusing on financial performance measurements can result in reduced utility created for NPOs. Less transparency often leads to increased utility for NPOs, but more transparency can increase NPOs' utility if the information available exceeds a certain threshold. Fluctuating donations are challenging for NPOs' planning and may Impact administrative capacities negatively.
2

Contribution au prognostic de pile à combustible PEMFC basé sur modèle semi-analytique / Contribution to PEM Fuel Cell prognostics based on a semi-analytical model

Lechartier, Élodie 27 June 2016 (has links)
Les préoccupations environnementales actuelles nous amènent à envisager des solutions alternatives, telles que la pile à combustible. Cette dernière malgré ses avantages présente des faiblesses qui ralentissent sa diffusion au sein de l'industrie, entre autres, sa trop courte durée de vie. Face à cette considération, nous proposons d'appliquer le PHM à la PEMFC. Il faut donc développer le pronostic puis considérer son insertion au sein d'un système industriel. Nous choisissons de baser l'approche proposée sur un modèle de comportement, tout en proposant de combler le manque de connaissance concernant le vieillissement de la pile par les données, ce qui nous permet amène à développer une approche hybride. Dans ces travaux, le modèle comportemental est étudié sur des durées de plus en plus grandes pour enfin proposer une prédiction de l'ordre du millier d'heure. Afin de prendre en compte une implantation au sein d'un système réel, une étude sur la généricité et applicabilité de l'approche est réalisée. Ainsi, ces travaux proposent une approche de pronostic hybride basée sur un modèle de comportement et étudie son insertion au sein d'un système réel. / The current environmental concerns lead us to consider alternative solutions. The fuel cell can be one of them with numerous advantages, it presents however weaknesses, especially, its life duration which is too short. Face to this issue, we offer to apply the PHM to the PEMFC. For that, it is necessary to develop the prognostics for this application and the possibility of the on-line implementation on an industrial system. It was chosen to base the approach on a behavioral model in which the knowledge gaps are completed with the use of data. So, the approach proposed here, is hybrid. In this work, the behavioral model is studied on laps of time longer in order to finally introduce a prediction of a thousand of hours. Then, the online implementation on a real system is considered with a genericity and an applicability study. This work proposes a hybrid prognostics approach based on a behavioral model and study its implementation on an industrial system.
3

A Decision Analytic Model Comparing Urokinase versus Recombinant Tissue Plasminogen Activator in the Treatment of Acute Peripheral Arterial Occlusions

Olvey, Eleanor L. January 2006 (has links)
Class of 2006 Abstract / Objectives: To determine the cost-effectiveness of urokinase (UK) and alteplase (recombinant tissue plasminogen activator, rt-PA) when used intra-arterially for the treatment of acute peripheral arterial occlusions. Methods: A decision analytic model was constructed using TreeAge Pro 2005 Suite to determine the cost- effectiveness of these therapies. Data for costs and probabilities were collected from published literature, as well as other references. Average and incremental cost-effectiveness ratios were calculated with a 95% confidence interval. A two-dimensional (sampling plus trials) Monte Carlo analysis with 5,000 patients was performed, along with a sensitivity analysis of the costs and variables. The costs measured were direct medical costs from the perspective of the healthcare institution. The primary outcome variable assessed in this model was 30-day survival. Results: The Monte Carlo microsimulation indicated that average cost-effectiveness (C/E) ratio for rt-PA was $54,141 (95th CI: 44,647 to 62,832) per successful treatment, while the average C/E ratio for UK was $65,515 (95th CI: 56,286 to 76,135). The ICER for rt-PA versus UK as the baseline was calculated to be $284,170 per additional survival over 30 days (95th CI: 186,097 to 418,443). Neither strategy was dominant. Conclusions: This study found rt-PA to be less costly but also slightly less efficacious than UK for patients treated for acute arterial occlusions. Neither therapy was indicated to be dominant over the other in terms of 30-day survival. Further long-term outcome data is necessary to more extensively assess the benefits of each therapy.
4

Model kompozitního nosníku s piezoelektrickou vrstvou / Model of composite cantilever with piezoelectric layer

Hons, Richard January 2018 (has links)
This thesis deals with the generating electrical energy from vibrations from piezoelectric composite cantilever beam. A review of the piezoelectric materials is made. Then the analytical model of piezoelectric cantilever beam is presented, then the influence of parameters is inves-tigated. Case study with theoretic design of parameters on the specific source of vibration is also provided. Last part is the extension of model for the variable width of layers at cantilever
5

Um modelo analítico para estimar o consumo de energia de sistemas multi-camadas no nível de transação / An analytical model to estimate the energy consumption on multi-tier system at a fine-grained level

Ferreira, Alex Rabelo 25 April 2017 (has links)
Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2017-05-19T17:06:06Z No. of bitstreams: 2 Dissertação - Alex Rabelo Ferreira - 2017.pdf: 1520702 bytes, checksum: 4d6d16d4b1045c459e8d23fc2f6a4c69 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-05-22T10:41:24Z (GMT) No. of bitstreams: 2 Dissertação - Alex Rabelo Ferreira - 2017.pdf: 1520702 bytes, checksum: 4d6d16d4b1045c459e8d23fc2f6a4c69 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-05-22T10:41:24Z (GMT). No. of bitstreams: 2 Dissertação - Alex Rabelo Ferreira - 2017.pdf: 1520702 bytes, checksum: 4d6d16d4b1045c459e8d23fc2f6a4c69 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-04-25 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / In large-scale data centers, power management techniques such as Dynamic Voltage/Frequency Scaling (DVFS), virtual machine consolidation, and power-capping mechanisms promise impressive energy savings compared to traditional resource management strategies. Most of these techniques rely on coarse-grained monitoring of the workload behavior to apply their optimizations. However, coarse-grained monitoring and black box observations are not satisfactory for predicting the behavior of bursty workloads such as those observed in enterprise, Web servers. In this work, we propose an analytical model to estimate the energy consumption of multi-tier Web Systems. Differently from previous works, our model captures the consumption pattern at the level of fine-grained transactions and for each tier of the system. In addition, our model is based only on CPU utilization and server architectural parameters, which can be easily obtained in today’s production environments. We demonstrate the effectiveness of our model in a real-world experimentation environment, based on the TPC-W benchmark. Results show that our model is able to estimate the energy consumption for a Web system with an average relative error of 6.5% in the worst-case scenario, whereas more complex models of the literature present errors within the same order of magnitude. / Em grandes centros de dados, técnicas de gerenciamento de energia como Dynamic Voltage/Frequency Scaling (DVFS), consolidação de máquinas virtuais e mecanismos de limitação de energia prometem grande economia de energia quando comparados a métodos tradicionais de gerenciamento de recursos. A maioria dessas técnicas utilizam mecanismos caixas-pretas para monitorar o comportamento da carga de trabalho. Contudo, esse tipo de monitoramento não é satisfatório para prever os fenômenos de rajadas, comumente encontrados em serviços e aplicações Web. Neste trabalho, propomos um modelo analí- tico para estimar o consumo de energia de Sistemas Web multi-camadas. Diferentemente de outros trabalhos, nosso modelo captura o padrão de consumo desses sistemas na granularidade de transações e para cada camada do sistema. Além disso, nosso modelo se baseia apenas na utilização de CPU e em parâmetros arquiteturais do servidor, os quais podem ser facilmente obtidos nos ambientes de produção atuais. Demonstramos a efetividade do nosso modelo em um ambiente de experimentação real, baseado no benchmark TPC-W. Os resultados obtidos mostram que nosso modelo é capaz de estimar o consumo de energia para um sistema Web com um erro relativo médio de 6,5% para o pior cenário, enquanto modelos mais complexos da literatura apresentam erros com a mesma ordem de grandeza.
6

Tshekatsheko ya Sebilwane bjalo ka thetokanegelo (Sepedi)

Mojalefa, M.J. (Mawatle Jeremiah), 1948- 02 May 2013 (has links)
In this thesis, Sebilwane is the subject of a narratological investigation. The point of departure of this study is based on the fact that a narratological text consists of three levels: the history, the composition, the usage of words which are recognisable in the style of the author. The epic-poem is not the subject of a verse-technical investigation and description. The narratological model is adapted to the aim of this study. The historical level regarded in principle as the original level prior to the material's exposure to a viewpoint and it is interpreted. The four narrative elements that are investigated are: the events, the characters/actors, time and place. In Sebilwane there are main events identified by the criteria of: (a) change, (b) cause, and (c) result. The characters/actors have been described and classified according to: (a) aim, (b) supporter, (c) patron, (d)helper and patron,and (e) opponent. In as far as historical time is concerned, it has been concluded that the events occurred: (a) in the remote past, and (b) stretched it to a 24 hour period. The actors/persons find themselves in a rural area which can be comparable to Botlokwa which is lying within the borders of Lebowa. The composition of the information which is given in the historical level, gives the shape of the author's aim. Here, what is important, are the functions which are described by the elements themselves. Then the idea of the theme comes clearly in this part and it is therefore identified as the main - and sub-theme. The third level concerns the usage of words; the information now gets a personal or subjective selection. Therefore, only a short passage is to be selected for stylistic analysis. The analytic model which is effected here is Kerkhoff's. AFRIKAANS : In hierdie verhandeling word Sebilwane aan 'n narratologiese ondersoek onderwerp. Die uitgangspunt van hierdie studie is dat 'n narratologiese teks uit drie lae bestaan: die geskiedenis, die samestelling, die verwoording wat in die styl van die outeur kenbaar is. Hierdie epiese gedig word nie verstegnies ondersoek en beskryf nie. Die narratologiese model is vir die doel van hierdie studie aangepas. Die geskiedenislaag word in beginsel as die oorspronklike laag beskou voordat die gegewens vanuit 'n bepaalde gesigspunt bekyk en weergegee word. Die vier vertelelemente wat ondersoek word, is die gebeurtenisse, die karakters/akteurs, tyd en plek. In Sebilwane is die kerngebeurtenisse geïdentifiseer deur die kriteria van (a) verandering, (b) oorsaak en (c) afloop. Die karakters/akteurs is beskryf en geklassifiseer volgens (a) doelstelling, (b) begunstigde, (c) begunstiger, (d) helper en (e) teëstaander. Wat die tyd betref, speel die gebeure (a) histories in die verre verlede af, en (b) strek dit oor 'n 24 uur tydperk. Die akteurs/mense bevind hulle in 'n landelike gebied wat waarskynlik Botlokwa is wat binne Lebowa geleë is. Die samestelling van die gegewens wat in die geskiedenislaag gegee is, gee aan die doestelling van die outeur gestalte. Daarvan gaan dit hier om die funksies wat aan die elemente toegesê word. Die begrip van die tema staan in hierdie gedeelte voorop, en daar word 'n hoof - en 'n subtema geïdentifiseer. / Dissertation (MA)--University of Pretoria, 1993. / African Languages / unrestricted
7

Advanced analytical model for the prognostic of industrial systems subject to fatigue / Modèle analytique avancé pour le pronostic des systèmes industriels soumis à la fatigue

Abou Jaoude, Abdo 07 December 2012 (has links)
La disponibilité élevée des systèmes technologiques comme l'aérospatial, la défense, la pétrochimie et l'automobile, est un but important des nouveaux développements de la technologie de conception des systèmes sachant que la défaillance onéreuse survient, en général, soudainement. Afin de rendre les stratégies classiques de maintenance plus efficaces et pour prendre en considération l'état et l'environnement évolutifs du produit, un nouveau modèle de pronostic analytique est développé en tant que complément des stratégies de maintenance existantes. Ce nouveau modèle est appliqué aux systèmes mécaniques soumis à la défaillance par fatigue sous charge cyclique répétitive. Sachant que l'effet de fatigue va initier des microfissures qui peuvent se propager soudainement et conduire à la défaillance. Ce modèle est basé sur des lois d'endommagement existantes dans la mécanique de la rupture comme la loi de propagation de fissures de Paris-Erdogan à côté de la loi de cumul de dommage de Palmgren-Miner. A partir d'un seuil prédéfini de dégradation DC, la durée de vie résiduelle (RUL) est estimée à l'aide de ce modèle de pronostic. Les dommages peuvent être cumulés linéairement (Loi de Palmgren-Miner) et aussi non linéairement afin de prendre en compte un comportement plus complexe des chargements et des matériaux. Le modèle de dégradation développé dans ce travail est basé sur une sommation d'une mesure de dommage D à la suite de chaque cycle de chargement. Quand cette mesure devient égale à un seuil prédéfini DC, le système est considéré dans l'état de panne. En plus, l'influence stochastique est incluse dans notre modèle pour le rendre plus précis et réaliste. / The high availability of technological systems like aerospace, defense, petro-chemistry and automobile, is an important goal of earlier recent developments in system design technology knowing that the expensive failure can generally occur suddenly. To make the classical strategies of maintenance more efficient and to take into account the evolving product state and environment, a new analytic prognostic model is developed as a complement of existent maintenance strategies. This new model is applied to mechanical systems that are subject to fatigue failure under repetitive cyclic loading. Knowing that, the fatigue effects will initiate micro-cracks that can propagate suddenly and lead to failure. This model is based on existing damage laws in fracture mechanics, such as the crack propagation law of Paris-Erdogan beside the damage accumulation law of Palmgren-Miner. From a predefined threshold of degradation DC, the Remaining Useful Lifetime (RUL) is estimated by this prognostic model. Damages can be assumed to be accumulated linearly (Palmgren-Miner's law) and also nonlinearly to take into consideration the more complex behavior of loading and materials. The degradation model developed in this work is based on the accumulation of a damage measurement D after each loading cycle. When this measure reaches the predefined threshold DC, the system is considered in wear out state. Furthermore, the stochastic influence is included to make the model more accurate and realistic.
8

Estudo comparativo entre modelos na análise local de tubos flexíveis. / Comparative study between modles in local analysis of flexible pipes.

Maranhão, Flamínio Alves Fávero 26 August 2011 (has links)
Este trabalho apresenta um estudo comparativo entre resultados obtidos através de um modelo analítico-numérico, um modelo em elementos finitos e resultados experimentais na análise estrutural local de tubos flexíveis utilizados na explotação de petróleo. Em particular, o modelo em elementos finitos proposto considera efeitos de não-linearidade decorrentes do contato e das forcas de atrito entre as camadas concêntricas do tubo, de forma a reproduzir curvas de histerese típicas obtidas em ensaios em escala real. Tais curvas não podem ser obtidas pelos modelos simplificados tradicionais, de maneira que sua obtenção por modelos em elementos finitos traz novas informações sobre o comportamento estrutural dos dutos Tomando como base e elemento motivacional os resultados de ensaios experimentais de um tubo flexível de 2,5, realizados no Instituto de Pesquisas Tecnológicas de São Paulo, são estudados um modelo analítico e um modelo em elementos finitos, ambos representando o tubo ensaiado experimentalmente, de maneira a apontar, de forma qualitativa e quantitativa, quais são os pontos fortes e fracos de cada abordagem. O modelo analítico-numérico simplificado, obtido de um campo de deslocamentos compatível com os carregamentos axissimétricos aplicados e de um conjunto de equações que envolvem equilíbrio de forcas e equações constitutivas lineares, é capaz de fornecer rapidamente valores aproximados para a rigidez axial do conjunto, bem como uma estimativa das tensões médias atuantes em cada uma das camadas que compõem o tubo flexível, considerando ainda a possibilidade de afastamento entre as camadas. O modelo em elementos finitos é composto somente por elementos sólidos e considera a presença de atrito entre as camadas. As simulações não lineares, executadas pelo MSC.Marc, permitiram recuperar as curvas de histerese para os vários casos estudados, bem como a distribuição de tensões ao longo do comprimento e da seção transversal dos tendões. / This work presents a comparative study among an analytical-numerical model, a finite element model and experimental results related to the local structural analysis of flexible risers used in oil exploitation. In particular, the proposed finite element model considers nonlinearity effects caused by the contact and frictional forces between the concentric layers of the riser so that typical hysteresis curves obtained in full scale experiments could be reproduced. These curves can not be obtained by traditional simplified models, so that their reproduction by finite element models brings new information about the local structural behavior of risers. Based on and motivated by the results of experiments of a 2.5 flexible riser carried out at IPT, the São Paulo Technological Research Institute, an analytical model and a finite element model a are proposed, both of them representing the flexible riser tested experimentally, in order to point out, in a qualitative and quantitative way, the strengths and weaknesses of each approach. The simplified analytical-numerical model, obtained from a displacement field, consistent with the axisymmetric loads applied to the pipe, and from a set of equations involving equilibrium and linear constitutive equations, is able to quickly provide approximate values for the riser equivalent axial stiffness, as well as estimates for the average stresses acting in each of the layers that make up the flexible riser. Besides, the possibility of gap formation between the layers is also considered. The finite element model is composed entirely of solid elements and considers the presence of friction between the layers. The nonlinear simulations, using the MSC.Marc finite element package, allowed the reproduction of hysteresis curves for the several studied cases, as well as the stresses distribution along the length and cross section of the armour layers.
9

Modélisations multi-physiques de la génération piezoélectrique à l'aide de nanofils d'oxyde de zinc / Multiphysics modelling of the piezoelectric generation in zinc oxyde nanowires

Graton, Olivier 03 October 2012 (has links)
Les progrès réalisés dans les processus de fabrication ont mené vers un contrôle accru des dimensions et de la composition chimique des nanostructures, permettant l’émergence de nouveaux dispositifs appelés Nanosystèmes ElectroMécaniques ou NEMS. Outre leurs propriétés physiques originales, leurs dimensions réduites leurs confèrent un fonctionnement peu coûteux en énergie Ainsi, l’utilisation de l’environnement de tels dispositifs comme source d’énergie est possible. Afin de préserver les avantages liés aux dimensions des NEMS, le système de récupération d’énergie doit présenter un volume réduit. Dans ce contexte, nous étudions les nanoffis de ZnO comme éléments actifs de micro et nanosystèmes de récupération d’énergie à travers deux modèles physiques de nanofils. L’originalité de ces deux modèles vient de la prise en compte du couplage entre les propriétés piezoélectriques et les propriétés semiconductrices du ZnO et de ses effets dans la conversion électromécanique de l’énergie. / Recent progresses in manufacturing processes allow a better control of dimensions and chemical composition of nanostructures, This leads to the emergence of a new family of devices known as Nano ElectroMechanical Systems or NEMS. These devices show novel physical properties and functional characteristics due to their reduced size. Besides, their operating power consumption are tiny, making the use of their environment as energy source highly attractive. The design of a generator that scavenge the surrounding energy of the NEMS is quite a challenge; indeed, such a microharvester should be small enough to ensure that the dimensions of the whole autonomous device are still acceptable. in that context, we investigate ZnO nanowires as active elements of piezoelectric nano and microgenerator. We have specially developed two models of nanowire that take into account of the piezoelectric-semiconducting coupling to appreciate its effects on the electromechanical conversion of energy.
10

Estudo comparativo entre modelos na análise local de tubos flexíveis. / Comparative study between modles in local analysis of flexible pipes.

Flamínio Alves Fávero Maranhão 26 August 2011 (has links)
Este trabalho apresenta um estudo comparativo entre resultados obtidos através de um modelo analítico-numérico, um modelo em elementos finitos e resultados experimentais na análise estrutural local de tubos flexíveis utilizados na explotação de petróleo. Em particular, o modelo em elementos finitos proposto considera efeitos de não-linearidade decorrentes do contato e das forcas de atrito entre as camadas concêntricas do tubo, de forma a reproduzir curvas de histerese típicas obtidas em ensaios em escala real. Tais curvas não podem ser obtidas pelos modelos simplificados tradicionais, de maneira que sua obtenção por modelos em elementos finitos traz novas informações sobre o comportamento estrutural dos dutos Tomando como base e elemento motivacional os resultados de ensaios experimentais de um tubo flexível de 2,5, realizados no Instituto de Pesquisas Tecnológicas de São Paulo, são estudados um modelo analítico e um modelo em elementos finitos, ambos representando o tubo ensaiado experimentalmente, de maneira a apontar, de forma qualitativa e quantitativa, quais são os pontos fortes e fracos de cada abordagem. O modelo analítico-numérico simplificado, obtido de um campo de deslocamentos compatível com os carregamentos axissimétricos aplicados e de um conjunto de equações que envolvem equilíbrio de forcas e equações constitutivas lineares, é capaz de fornecer rapidamente valores aproximados para a rigidez axial do conjunto, bem como uma estimativa das tensões médias atuantes em cada uma das camadas que compõem o tubo flexível, considerando ainda a possibilidade de afastamento entre as camadas. O modelo em elementos finitos é composto somente por elementos sólidos e considera a presença de atrito entre as camadas. As simulações não lineares, executadas pelo MSC.Marc, permitiram recuperar as curvas de histerese para os vários casos estudados, bem como a distribuição de tensões ao longo do comprimento e da seção transversal dos tendões. / This work presents a comparative study among an analytical-numerical model, a finite element model and experimental results related to the local structural analysis of flexible risers used in oil exploitation. In particular, the proposed finite element model considers nonlinearity effects caused by the contact and frictional forces between the concentric layers of the riser so that typical hysteresis curves obtained in full scale experiments could be reproduced. These curves can not be obtained by traditional simplified models, so that their reproduction by finite element models brings new information about the local structural behavior of risers. Based on and motivated by the results of experiments of a 2.5 flexible riser carried out at IPT, the São Paulo Technological Research Institute, an analytical model and a finite element model a are proposed, both of them representing the flexible riser tested experimentally, in order to point out, in a qualitative and quantitative way, the strengths and weaknesses of each approach. The simplified analytical-numerical model, obtained from a displacement field, consistent with the axisymmetric loads applied to the pipe, and from a set of equations involving equilibrium and linear constitutive equations, is able to quickly provide approximate values for the riser equivalent axial stiffness, as well as estimates for the average stresses acting in each of the layers that make up the flexible riser. Besides, the possibility of gap formation between the layers is also considered. The finite element model is composed entirely of solid elements and considers the presence of friction between the layers. The nonlinear simulations, using the MSC.Marc finite element package, allowed the reproduction of hysteresis curves for the several studied cases, as well as the stresses distribution along the length and cross section of the armour layers.

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