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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.
181

Complexities Involving the Role of Gender and Setting on Provoked Interpersonal Violence: Comparing Analytical Approaches on Couple-Level Data

Kraft, Nikki H 11 August 2012 (has links)
Clark (2008) analyzed the role of provocation on dating partners’ level of aggression and found they were more aggressive in jealousy-provoking situations. Using the couple-level dataset collected by Clark, we examine the relationship of gender and setting on provoked interpersonal violence, and compare the accuracy of several analytical approaches on interpreting dyadic data. Results indicate some findings from Clark are extremely robust. For instance, consistent with previous findings, the significant role of provocation on aggression in a dating context is further supported in the current study (Bettencourt & Miller, 1996; Jacquin et al., 2006). Clark suggested gender symmetry in levels of aggression. However, results show a significant effect of gender, in that females were more passive aggressive than males. One implication of this study is that when analyzing dyadic data, a multi-level modeling (MLM) approach best represents the relationship between the outcome and predictors when compared to other analytical approaches.
182

The Impact of Race and Neighborhood on Child Maltreatment: A Multi-Level Discrete Time Hazard Analysis

Irwin, Mary Elizabeth (Molly) 07 October 2009 (has links)
No description available.
183

Race, Education, and Social Reproduction: A Study of Educational Careers in the United States

Merolla, David M. 09 April 2010 (has links)
No description available.
184

Watchdogs that do not Bite, Nets that do not Catch, and "Perps" Policing Themselves: Why Anti-Corruption Multi-Level Governance Efforts Fail in the Philippines.

Yllana, Grace R. 22 October 2013 (has links)
No description available.
185

Surface Integral Equation Methods for Multi-Scale and Wideband Problems

Wei, Jiangong January 2014 (has links)
No description available.
186

[en] INFLUENCE OF CIRCULAR ECONOMY ADOPTION IN EUROPEAN SME S PERFORMANCE / [pt] INFLUÊNCIA DA ADOÇÃO DA ECONOMIA CIRCULAR NO DESEMPENHO DAS PME EUROPEIAS

BRUNA OLIVEIRA ROSA 25 March 2024 (has links)
[pt] Este estudo fornece uma análise da relação entre as práticas da economia circular (EC) e o desempenho nas pequenas e médias empresas (PME) na Europa, seguindo uma abordagem multinível. O projeto de pesquisa descreve as etapas envolvidas para atingir esse objetivo. A primeira etapa (artigo 1) examina as tendências da pesquisa existente. Verificamos as variáveis utilizadas, o tipo de dados, o método de análise, o tipo de indústria, o porte da empresa, o tamanho da amostra e o tema ao qual o artigo pertence. Os resultados indicam que não existe um consenso claro sobre a melhor forma de medir e operacionalizar as práticas de EC e o desempenho das empresas, no entanto as variáveis identificadas podem ser utilizadas como guia para futuras pesquisas sobre EC e o desempenho das empresas. Na segunda etapa (artigo 2), investigamos como os indicadores de desempenho econômico, social e ambiental do país PME moderam a relação entre as práticas de EC e o desempenho da empresa. Em resumo, os resultados apoiam que o impacto financeiro da adoção da EC é positivo e é afetado pelo nível de desempenho nacional econômico e ambiental. A terceira etapa (artigo 3) tem como objetivo desenvolver e testar o modelo empírico que inclui moderação por nível meso. Examinamos a função dos intermediarios no envolvimento das PME nas atividades de EC bem como a presença de Redes de Simbiose Industrial (ISN) afeta o desempenho das PME. As conclusões afirmam que as ISN s podem impulsionar a adopção da EC e os intermediários podem ajudar as PME a superar os obstáculos da EC. / [en] This study provides an examination of the relationship between circular economy (CE) practices and firm performance in small and medium-sized enterprises (SMEs) in Europe, following a multi-level approach. The research project outlines the stages involved to reach this goal. The first stage (paper 1) examines the trends in the existing research. We verified the variables used, the type of data, the method of analysis, the type of industry, the size of the company, the size of the sample and the topic to which the article belongs. The results indicate that there is no clear consensus on the best way to measure and operationalize CE practices and firm performance, however the variables identified can be used as a guide for future research on CE and firm performance. The second stage (paper 2) we investigate how the economic, social, and environmental performance indicators of the SME country moderates the relationship between CE practices and firm performance. In summary, the results support that the financial impact of adopting CE is positive, and it is affected by the level of national economic and environmental performance. The third stage (paper 3) the aim is develop and test empirical model include moderation by meso-level. We examined the function of intermediaries in involving SMEs in CE activities, and how the presence of Industrial Symbiosis Networks (ISN) affects SMEs performance. The findings affirm that ISNs can boost CE adoption and intermediaries can assist SMEs in surmounting CE obstacles.
187

Power Density Optimization of SiC-based DC/AC Converter for High-Speed Electric Machine in More/All-electric Aircraft

Zhao, Xingchen 07 May 2024 (has links)
The increasing shift towards more electric or all electric aircraft urgently necessitates dc/ac converter systems with high power density. Silicon Carbide (SiC) devices, known for their superior performance over traditional silicon-based devices, facilitate this increase in power density. Nonetheless, achieving optimal power density faces challenges due to the unique requirements and conditions of aircraft applications. A primary obstacle is optimizing the topology and parameters of the dc/ac converter system to achieve high power density while adhering to the stringent aerospace EMI standard DO-160 and bearing current limitations. Electric aircraft demand unmatched reliability, necessitating strict control over EMI noise and bearing currents. These considerations significantly impact the selection of topology and parameters to maximize power density. This dissertation assesses how dc voltage, topology, and switching frequency affect component weight, seeking an optimal mix to enhance power density. The methodology and conclusions are validated through a 200-kW motor drive system designed for electric aircraft. Moreover, traditional dc/ac systems are burdened by the weight and space occupied by separate current sensors and short-circuit protection circuits. This work introduces two innovative current sensors that integrate device current sampling with the functionality of traditional shunt resistors, AC hall sensors, and short-circuit protection circuits, thus improving system density and bandwidth. The first sensor, a PCB-based Rogowski coil, integrates with the gate driver and commutation loops, enhancing power density despite challenges in managing CM noise. The second sensor utilizes parasitic inductance in the power loop, with an integrator circuit and an adaptive compensation algorithm correcting errors from parasitic resistance, ensuring high bandwidth accuracy without needing parasitic resistance information. Variable operation conditions from motors pose another challenge, potentially leading to oversized inverters due to uneven loss distribution among switching devices, exacerbated at extreme operating points like motor start-up. This dissertation investigates the loss distribution in multi-level T-Type neutral point clamped (NPC) topology and proposes a novel loss-balance modulation scheme. This scheme ensures even loss distribution across switches, independent of power factor and modulation index, and is applicable to T-type inverters of any level count. Finally, thermal management and insulation at high altitudes present significant challenges. While power devices may be cooled using conventional liquid cooling solutions, components like AC and EMI filters struggle with complex geometries that can create hot spots or high E-field points, complicating filter design for high current applications. A comprehensive design and optimization methodology based on planar heavy-copper PCB design is proposed. By utilizing flexible 2D or 3D E-field shaping and maximizing thermal transfer from copper to ambient, this methodology significantly improves power density and ensures effective heat dissipation and insulation at altitudes up to 50,000 feet. / Doctor of Philosophy / The increasing shift towards more electric or all electric aircraft urgently necessitates dc/ac converter systems with high power density. Silicon Carbide (SiC) devices, known for their superior performance over traditional silicon-based devices, facilitate this increase in power density. Nonetheless, achieving optimal power density faces challenges due to the unique requirements and conditions of aircraft applications. A primary obstacle is optimizing the topology and parameters of the dc/ac converter system to achieve high power density while adhering to the stringent aerospace EMI standard DO-160 and bearing current limitations. Electric aircraft demand unmatched reliability, necessitating strict control over EMI noise and bearing currents. These considerations significantly impact the selection of topology and parameters to maximize power density. This dissertation assesses how dc voltage, topology, and switching frequency affect component weight, seeking an optimal mix to enhance power density. The methodology and conclusions are validated through a 200-kW motor drive system designed for electric aircraft. Moreover, traditional dc/ac systems are burdened by the weight and space occupied by separate current sensors and short-circuit protection circuits. This work introduces two innovative current sensors that integrate device current sampling with the functionality of traditional shunt resistors, AC hall sensors, and short-circuit protection circuits, thus improving system density and bandwidth. The first sensor, a PCB-based Rogowski coil, integrates with the gate driver and commutation loops, enhancing power density despite challenges in managing CM noise. The second sensor utilizes parasitic inductance in the power loop, with an integrator circuit and an adaptive compensation algorithm correcting errors from parasitic resistance, ensuring high bandwidth accuracy without needing parasitic resistance information. Variable operation conditions from motors pose another challenge, potentially leading to oversized inverters due to uneven loss distribution among switching devices, exacerbated at extreme operating points like motor start-up. This dissertation investigates the loss distribution in multi-level T-Type neutral point clamped (NPC) topology and proposes a novel loss-balance modulation scheme. This scheme ensures even loss distribution across switches, independent of power factor and modulation index, and is applicable to T-type inverters of any level count. Finally, thermal management and insulation at high altitudes present significant challenges. While power devices may be cooled using conventional liquid cooling solutions, components like AC and EMI filters struggle with complex geometries that can create hot spots or high E-field points, complicating filter design for high current applications. A comprehensive design and optimization methodology based on planar heavy-copper PCB design is proposed. By utilizing flexible 2D or 3D E-field shaping and maximizing thermal transfer from copper to ambient, this methodology significantly improves power density and ensures effective heat dissipation and insulation at altitudes up to 50,000 feet.
188

The Multi-tiered Future of Storage: Understanding Cost and Performance Trade-offs in Modern Storage Systems

Iqbal, Muhammad Safdar 19 September 2017 (has links)
In the last decade, the landscape of storage hardware and software has changed considerably. Storage hardware has diversified from hard disk drives and solid state drives to include persistent memory (PMEM) devices such as phase change memory (PCM) and Flash-backed DRAM. On the software side, the increasing adoption of cloud services for building and deploying consumer and enterprise applications is driving the use of cloud storage services. Cloud providers have responded by providing a plethora of choices of storage services, each of which have unique performance characteristics and pricing. We argue this variety represents an opportunity for modern storage systems, and it can be leveraged to improve operational costs of the systems. We propose that storage tiering is an effective technique for balancing operational or de- ployment costs and performance in such modern storage systems. We demonstrate this via three key techniques. First, THMCache, which leverages tiering to conserve the lifetime of PMEM devices, hence saving hardware upgrade costs. Second, CAST, which leverages tiering between multiple types of cloud storage to deliver higher utility (i.e. performance per unit of cost) for cloud tenants. Third, we propose a dynamic pricing scheme for cloud storage services, which leverages tiering to increase the cloud provider's profit or offset their management costs. / Master of Science / Storage and retrival of data is one of the key functions of any computer system. Improvements in hardware and software related to data storage can help computer users store (a) store the data faster, which makes for overall faster performance; and (b) increase the storage capacity, which helps store the increasing amount of data generated by modern computer users. Typically, most computers are equipped with either a hard disk drive (HDD) or, the newer and faster, solid state drive (SSD) for data storage. In the last decade however, the landscape of data storage hardware and software has advanced considerably. On the hardware side, several hardware makers are introducing persistent memory (PMEM) devices, which provide very high speed, high capacity storage at reasonable price points. On the software side, the increasing adoption of cloud services by software developers that are building and operating consumer and enterprise applications is driving the use of cloud storage services. These services allow the developers to store a large amount of data without having to manage any physical hardware, paying for the service on a usage-based pricing structure. However, every application’s speed and capacity needs are not the same; hence, cloud service providers have responded by providing a plethora of choices of storage services, each of which have unique performance characteristics and pricing. We argue this variety represents an opportunity for modern storage systems, and it can be leveraged to improve the operating costs of the systems. Storage tiering is a classical technique that involves partitioning the stored data and placing each partition in a different storage device. This lets the applications use mulitple devices at once, taking advantage of each’s sterngths and mitigating their weaknesses. We propose that storage tiering is a relevant and effective technique for balancing operational or deployment costs and performance in modern storage systems such as PMEM devices and cloud storage services. We demonstrate this via three key techniques. First, THMCACHE, which leverages tiering between multiple types of storage hardware to conserve the lifetime of PMEM devices, hence saving hardware upgrade costs. Second, CAST, which leverages tiering between multiple types of cloud storage services to deliver higher utility (i.e. performance per unit of cost) for software developers using these services. Third, we propose a dynamic pricing scheme for cloud storage services, which leverages tiering between multiple cloud storage services to increase the cloud service provider’s profit or offset their management costs.
189

Modelos y Algoritmos de Coordinación para la Planificación de Operaciones basadas en el concepto Stroke en Redes de Suministro distribuidas y con alternativas

Rius Sorolla, Gregorio Vicente 07 January 2020 (has links)
[ES] Con la globalización de los mercados y el aumento de la competitividad, la coordinación se ha convertido en un punto estratégico en la gestión de la cadena de suministro. De hecho, cada actor de la cadena de suministro ya no debe tomar decisiones sin considerar todos los eslabones, sean proveedores, proveedores de proveedores o clientes y estos internos o externos a la organización. Las cadenas de suministro son cada vez más complejas y distribuidas, compuestas por múltiples organizaciones con diferentes objetivos y políticas. La coordinación se puede lograr utilizando uno de estos dos enfoques para la toma de decisiones coordinadas: centralizada o descentralizada con un mecanismo de coordinación. Pero, las empresas son reacias a compartir información, ya sea por la confidencialidad de los datos o porque los modelos centralizados resultantes son de gran complejidad que dificultan su manejo y actualización. Además, aquellas empresas que buscan tomar decisiones en tiempo real requieren de modelos ligeros y ágiles, que, con toda la información local y coordinada con el resto, permitan tomar decisiones rápidas. Las empresas interesadas en la coordinación descentralizada con un mecanismo de coordinación esperan obtener mejores resultados con respecto a la no coordinación, aunque deberían asumir tener peores resultados que con la coordinación centralizada. Para ello en esta tesis, se han estudiado los distintos mecanismos de coordinación para la toma de decisiones descentralizada, dentro de un entorno del procedimiento de horizontes rodantes y con herramienta de planificación y programación de las operaciones basada en el concepto de stroke, que extiende el concepto de lista de materiales más allá de las estructuras tradicionales. Estos permiten desarrollar la formulación de la programación matemática y los mecanismos de coordinación necesarios para resolver los problemas de planificación de operaciones. Esta tesis se presenta como una secuencia de capítulos, con el objeto de analizar y presentar la propuesta de mecanismo de coordinación distribuido con unos recursos compartidos. Los distintos capítulos han servido de base para la preparación de artículos científicos. Estos artículos han sido presentados en congresos de la materia y remitidos a revistas científicas. / [CA] Amb la globalització dels mercats i l'augment de la competitivitat, la coordinació s'ha convertit en un punt estratègic en la gestió de la cadena de subministrament. De fet, cada actor de la cadena de subministrament ja no ha de prendre decisions sense considerar totes les baules, siguen proveïdors, sub-proveïdors o clients i aquests interns o externs a l'organització. Les cadenes de subministrament són cada vegada més complexes i distribuïdes, compostes per múltiples organitzacions amb diferents objectius i polítiques. La coordinació es pot aconseguir utilitzant un d'aquests dos enfocaments per a la presa de decisions coordinades: centralitzat o descentralitzat amb un mecanisme de coordinació. Però, les empreses són poc inclinades a compartir informació, ja siga per la confidencialitat de les dades o perquè els models centralitzats resultants són de gran complexitat que dificulten el seu maneig i actualització. A més, aquelles empresa que busquen prendre decisions en temps real requereixen de models lleugers i àgils, que, amb tota la informació local i coordinada amb la resta, permeten prendre decisions ràpides. Les empreses interessades en la coordinació descentralitzada amb un mecanisme de coordinació esperen obtindre millors resultats respecte de la no coordinació encara que haurien d'assumir tindre pitjors resultats que amb la coordinació centralitzada. Per a això en aquesta tesi, s'han estudiat els diferents mecanismes de coordinació per a la presa de decisions descentralitzada, dins d'un entorn d'horitzons rodant i amb eines de planificació i programació de les operacions basada en el concepte de stroke, que estén el concepte de llista de materials més enllà de les estructures tradicionals. Aquests permeten desenvolupar la formulació de la programació matemàtica i els mecanismes de coordinació necessaris per a resoldre els problemes de planificació d'operacions. Aquesta tesi es presenta com una seqüència de capítols, a fi d'analitzar i presentar la proposta de mecanisme de coordinació distribuït amb uns recursos compartits. Els diferents capítols han servit de base per a la preparació d'articles científics. Aquests articles han sigut presentats en congressos de la matèria i remesos a revistes científiques. / [EN] With the globalization of markets and the increase of competitiveness, coordination has become a strategic point in the management of the supply chain. In fact, each actor in the supply chain must no longer make decisions without considering all the links, whether suppliers, sub-suppliers or customers and those internal or external to the organization. Supply chains are increasingly complex and distributed, composed of multiple organizations with different objectives and policies. Coordination can be achieved using one of these two approaches to coordinate decision making: centralized or decentralized with a coordination mechanism. However, companies are reluctant to share information, either because of the confidentiality of the data or because the resulting centralized models are of great complexity that make their management and update them. In addition, those companies that seek to make decisions in real time require lightweight and agile models, which, with all the local information and coordinated with the rest, allow quick decisions. Companies interested in decentralized coordination with a coordination mechanism expect to obtain better results regarding non-coordination although they should assume to have worse results than with centralized coordination. To this end, in this thesis, the different coordination mechanisms for decentralized decision making have been studied, within an environment of rolling horizons and with tools for planning and scheduling operations based on the concept of stroke, which extends the concept of list of materials beyond traditional structures. These allow to develop the formulation of the mathematical programming and the coordination mechanisms necessary to solve the operations planning problems. This thesis is presented as a sequence of chapters, in order to analyse and present the proposal of distributed coordination mechanism with shared resources. The different chapters have served as the basis for the preparation of scientific articles. These articles have been presented at congresses of the subject and submitted to scientific journals. / Rius Sorolla, GV. (2019). Modelos y Algoritmos de Coordinación para la Planificación de Operaciones basadas en el concepto Stroke en Redes de Suministro distribuidas y con alternativas [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/134017
190

Optimum design of reinforced concrete skeletal systems using non-linear programming techniques

Ceranic, Boris January 2000 (has links)
No description available.

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