• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1129
  • 665
  • 237
  • 168
  • 90
  • 59
  • 45
  • 32
  • 20
  • 16
  • 13
  • 13
  • 12
  • 11
  • 11
  • Tagged with
  • 3142
  • 628
  • 484
  • 266
  • 238
  • 202
  • 196
  • 173
  • 165
  • 162
  • 161
  • 146
  • 137
  • 135
  • 123
  • 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.
231

Issues in investment risk: a supply-side and demand-side analysis of the Australian managed fund industry.

Hallahan, Terrence Anthony, terry.hallahan@rmit.edu.au January 2006 (has links)
The investment management industry has proven to be a fertile ground for theoretical and empirical research over the past forty years, particularly in relation to the nature and quantification of risk. However, the dominance of the U.S. industry has meant that much of the academic research has focused on the U.S. market. This thesis investigates aspects of investment risk using alternative data to that used in much of the prior published research. This thesis contains an extensive analysis of aspects of risk related to both the demand side and the supply side of the managed funds market in Australia. Among the demand side characteristics, attitudes towards risk and their impact on asset allocation decisions will be an important determinant of investors' financial well-being, particularly in retirement. Accordingly, the first part of the thesis examines the financial risk tolerance of investors, exploring the relationship between subjective financial risk tolerance and a range of demographic characteristics that are widely used as a basis for heuristically derived estimates of investors' attitudes towards financial risk. The second part of the thesis contains an analysis of the supply side of the industry, focusing on risk-shifting behavior by investment fund managers. Since the time when performance and risk-shifting behavior of fund managers was first put under the spotlight 40 years ago, it is possible to identify an evolving strand in the research where performance assessment is examined within the framework of the principal-agent literature. One focus that has emerged in this literature is the adaption of the tournament model to the analysis of investment manager behavior, wherein it is hypothesized that fund managers who were interim losers were likely to increase fund volatility in the latter part of the assessment period to a greater extent than interim winners. Against this background, the second part of the thesis examines risk-shifting behavior by Australian fund managers. Both the ability of fund managers to time the market and the applicability of the tournament model of funds management to a segment of the Australian
232

Studies on dietary fibre: Analysis, epidemiological and physiological aspects.

Malik, Amirmuslim, mikewood@deakin.edu.au January 1986 (has links)
This thesis involves an investigation in three areas; first, a study of an enzymatic-gravimetric method for the analysis of dietary fibre; second, a survey of dietary fibre intake in an area of a developing country, and finally, some observations on the functional aspects of gel-forming dietary fibre in the rat. A simple and rapid enzymatic-gravimetric assay for both soluble and insoluble dietary fibre has been critically investigated. Reference samples were also analysed by a more comprehensive, enzymatic gas chromatographic method to allow testing of the relative accuracy of the enzymatic-gravimetric method. The enzymatic-gravimetric method was found to be highly reproducible but gave a slightly higher value for total dietary fibre than the more comprehensive method. This discrepancy is probably due to the presence of small quantities of resistant starch and protein residue which are recovered in the enzymatic-gravimetric method. In the enzymatic-gas chromatographic method, protein residue is not measured, and resistant starch is estimated, but not counted as dietary fibre. The enzymatic-gravimetric method was applied to the analysis of foods commonly consumed in the Padang region of West Sumatra in Indonesia, in order to estimate dietary fibre intake in the region. Daily intakes of usual foods were estimated by use of a 24-hour recall procedure aided by food photographs to assist in the estimation of portion size. Samples of approximately 60 of the most commonly consumed foods were collected and analysed for dietary fibre. These appear to be the first data which report values for dietary fibre in Indonesion foods and they represent a significant improvement upon the existing data on crude fibre content. Knowledge of the amounts of foods usually consumed and their dietary fibre content allowed an estimation of usual intakes of dietary fibre. Fibre intake was found to be lower than in the developing countries of Africa and was comparable to intakes measured in the U.K. This is the first study to show that in this part of South East Asia, a developing country area using polished rice as a staple food, dietary fibre intakes are as low as in Western countries. Low intakes of fibre are believed to be related to the prevalence of a range of diseases and, in this study, preliminary data on the rates of non-infective, chronic diseases were collected from the two main hospitals in West Sumatra. Chronic, non-infectious diseases such as inguinal hernia, appendicitis, haemorrhoids, diabetes mellitus, hypertension and malignant neoplasms of the rectum are relatively frequent in West Sumatra. While no firm conclusions can be drawn from these data, they do show the possibility of a relationship between low intakes of dietary fibre and the prevalence of these diseases, and suggest that further investigation is necessary. Some observations were made of the effect of gel-forming dietary fibre on stomach emptying and intestinal transit rate in the rat. Xanthan gum was added to iso-osmotic solutions to produce increased viscosity and phenol sulphonphthalein (phenol red) was used as a non-absorbable marker. Gavage feeding of solutions with a range of viscosities was used to study the effect of viscosity on the rate of stomach emptying and intestinal transit. Increased viscosity was observed to slow gastro-intestinal transit and this provides one mechanism by which dietary fibre of the gel-forming type ray improve glucose tolerance.
233

Robust, High-Speed Network Design for Large-Scale Multiprocessing

DeHon, Andre 01 September 1993 (has links)
As multiprocessor system size scales upward, two important aspects of multiprocessor systems will generally get worse rather than better: (1) interprocessor communication latency will increase and (2) the probability that some component in the system will fail will increase. These problems can prevent us from realizing the potential benefits of large-scale multiprocessing. In this report we consider the problem of designing networks which simultaneously minimize communication latency while maximizing fault tolerance. Using a synergy of techniques including connection topologies, routing protocols, signalling techniques, and packaging technologies we assemble integrated, system-level solutions to this network design problem.
234

Interface and Size Effects on TiN-based Nanostructured Thin Films

Kim, Ickchan 2011 May 1900 (has links)
Titanium nitride coatings have been widely applied and studied as high temperature diffusion barrier for silicon devices in microelectronics, wear resistant coatings in turbine blade materials, and materials for future high temperature nuclear reactors. In order to enhance the material property, superlattices is one of artificially engineered protective coatings, such as AlN/TiN and TaN/TiN multilayered films. Epitaxial cubic multilayer films, TaN/TiN and AlN/TiN nanolayers were grown on Si(001) by Pulsed Laser Deposition (PLD) with various nanolayer thicknesses and number of interfaces. Microstructural studies include X-ray diffraction (XRD), transmission electron microscopy (TEM), and high resolution TEM with ion-irradiation experiments. Electrical, mechanical and thermal property studies were conducted for the interface and size effects on the nanolayers by using nanoindentation and Transient Thermo-Reflectance (TTR) methods. The microstructural and hardness study on TaN/TiN films with ion irradiation (12 keV and 50 keV He ) suggest no obvious microstructural or mechanical behavior change due to ion irradiation. In addition, titanium nitride that serves as effective diffusion barrier to prevent the inter-diffusion between the nuclear fuel and the cladding material was studied in order to enhance the lifetime of the fuels and the reliability of the fuel claddings. The TiN has good adhesion with the stainless steel and higher hardness than that of bulk TiN on the stainless steel. Thermal conductivity test demonstrates that thin TiN film has compatible thermal conductivity as the MA957 and HT-9 bars. The size effect on electrical resistivity is dominant in both of the epitaxial cubic and the polycrystalline TiN thin films in the thickness ranged from ~60 nm down to ~35nm. In the TaN/TiN multilayer, the grain scattering effect on resistivity is dominant rather than interface influence on the resistivity with comparing epitaxial cubic phase and polycrystalline phase. The microstructure and hardness studies of the AlN/TiN multilayer films with He implantation present that the suppression of amorphization in AlN layers and the reduction of radiation-induced softening were achieved in all nanolayer films. Radiation tolerance was found to be size dependent and the layer thickness leading to the highest radiation tolerance was around 10 nm. In addition, the embedded epitaxial cubic AlN with cladding TiN nanolayers showed higher effective thermal conductivity than that of AlN single layer as well as the embedded polycrystalline AlN in the thickness ranged from 10 nm down to 2 nm. It confirms a suppressed size effect, which reduces the amount of decrease in through-plane thermal conductivity.
235

Two Approaches to Evaluate Drought Tolerance in Maize: Seedling Stress Response and Epicuticular Wax Accumulation

Meeks, Meghyn 14 March 2013 (has links)
We wanted to develop rapid and cost-effective drought tolerance screening methods for mass amounts of germplasm. In 2009 and 2010, we evaluated sixty-two maize inbred lines and their hybrid testcross progeny using seedling stress response and epicuticular wax accumulation as predictors of drought tolerance. The seedling screening method measured germination, survival and recovery percentages after a series of drought cycles in a greenhouse environment. Eight inbred lines had significantly (P < 0.05) lower germination than the mean estimate, but hybrid testcrosses were not significantly different. The second-to-last day of survival cycle and the second day of recovery cycle best explained genotypic differences for inbred lines and hybrid testcrosses respectively. One inbred line performed well as both an inbred line and hybrid testcross, but poor correlation over the sample set (R2 = 0.0097) was observed. Flag leaves taken at flowering from plants under full and limited irrigation regimes were sampled for epicuticular wax. Extracted wax weight for genotypes was compared as a percentage of leaf weight (percent wxlfwt) and leaf area (percent wxwta). Eleven genotypes had above average percent wxlfwt as both inbred lines and hybrid testcrosses. Thirteen genotypes had above average percent wxwta as either inbred lines or hybrid testcrosses. Irrigation treatment was not significant (P > 0.05). Heritability of percent wxlfwt was 0.17 (inbred lines) and 0.58 (hybrid testcrosses). Heritability of percent wxwta was 0.41 (inbred lines) and 0.59 (hybrid testcrosses). Correlations (R2) for percent wxlfwt and percent wxwta were 0.19 and 0.03, respectively. Heritability of grams of grain per ear and total grain yield was highest in hybrid testcrosses, with no correlation between inbreds and hybrids. The developed seedling screening method easily allowed visible drought tolerance observations in inbred lines and hybrid testcrosses but does not seem heritable in our germplasm. Epicuticular wax weight is not an ideal primary trait to evaluate for drought tolerance, but may be a good candidate to observe as a secondary trait in relation to grain yield production in hybrids. Results from this research best supports breeder selection of hybrid germplasm using seedling drought tolerance in conjunction with epicuticular wax.
236

Otherworld - Giving Applications a Chance to Survive OS Kernel Crashes

Depoutovitch, Alexandre 06 January 2012 (has links)
The default behavior of all commodity operating systems today is to restart the system when a critical error is encountered in the kernel. This terminates all running applications with an attendant loss of "work in progress" that is non-persistent. Our thesis is that an operating system kernel is simply a component of a larger software system, which is logically well isolated from other components, such as applications, and therefore it should be possible to reboot the kernel without terminating everything else running on the same system. In order to prove this thesis, we designed and implemented a new mechanism, called Otherworld, that microreboots the operating system kernel when a critical error is encountered in the kernel, and it does so without clobbering the state of the running applications. After the kernel microreboot, Otherworld attempts to resurrect the applications that were running at the time of failure. It does so by restoring the application memory spaces, open files and other resources. In the default case it then continues executing the processes from the point at which they were interrupted by the failure. Optionally, applications can have user-level recovery procedures registered with the kernel, in which case Otherworld passes control to these procedures after having restored their process state. Recovery procedures might check the integrity of application data and restore resources Otherworld was not able to restore. We implemented Otherworld in Linux, but we believe that the technique can be applied to all commodity operating systems. In an extensive set of experiments on real-world applications (MySQL, Apache/PHP, Joe, vi), we show that Otherworld is capable of successfully microrebooting the kernel and restoring the applications in over 97\% of the cases. In the default case, Otherworld adds negligible overhead to normal execution. In an enhanced mode, Otherworld can provide extra application memory protection with overhead of between 4% and 12%.
237

Otherworld - Giving Applications a Chance to Survive OS Kernel Crashes

Depoutovitch, Alexandre 06 January 2012 (has links)
The default behavior of all commodity operating systems today is to restart the system when a critical error is encountered in the kernel. This terminates all running applications with an attendant loss of "work in progress" that is non-persistent. Our thesis is that an operating system kernel is simply a component of a larger software system, which is logically well isolated from other components, such as applications, and therefore it should be possible to reboot the kernel without terminating everything else running on the same system. In order to prove this thesis, we designed and implemented a new mechanism, called Otherworld, that microreboots the operating system kernel when a critical error is encountered in the kernel, and it does so without clobbering the state of the running applications. After the kernel microreboot, Otherworld attempts to resurrect the applications that were running at the time of failure. It does so by restoring the application memory spaces, open files and other resources. In the default case it then continues executing the processes from the point at which they were interrupted by the failure. Optionally, applications can have user-level recovery procedures registered with the kernel, in which case Otherworld passes control to these procedures after having restored their process state. Recovery procedures might check the integrity of application data and restore resources Otherworld was not able to restore. We implemented Otherworld in Linux, but we believe that the technique can be applied to all commodity operating systems. In an extensive set of experiments on real-world applications (MySQL, Apache/PHP, Joe, vi), we show that Otherworld is capable of successfully microrebooting the kernel and restoring the applications in over 97\% of the cases. In the default case, Otherworld adds negligible overhead to normal execution. In an enhanced mode, Otherworld can provide extra application memory protection with overhead of between 4% and 12%.
238

RADIC: a powerful fault-tolerant architecture

Amancio Duarte, Angelo 28 June 2007 (has links)
La tolerancia a fallos se ha convertido en un requerimiento importante para los ingenieros informáticos y los desarrolladores de software, debido a que la ocurrencia de fallos aumenta el coste de explotación de un computador paralelo. Por otro lado, las actividades realizadas por el mecanismo de tolerancia de fallo reducen las prestaciones del sistema desde el punto de vista del usuario. Esta tesis presenta una arquitectura tolerante a fallos para computadores paralelos, denominada RADIC (Redundant Array of Distributed Fault Tolerance Controllers,), que es simultáneamente transparente, descentralizada, flexible y escalable. RADIC es una arquitectura tolerante a fallos que se basa un controlador distribuido para manejar los fallos. Dicho controlador se basa en procesos dedicados, que comparten los recursos del usuario en el computador paralelo. Para validar el funcionamiento de la arquitectura RADIC, se realizó una implementación que sigue el estándar MPI-1 y que contiene los elementos de la arquitectura. Dicha implementación, denominada RADICMPI, permite verificar la funcionalidad de RADIC en situaciones sin fallo o bajo condiciones de fallo. Las pruebas se han realizado utilizando un inyector de fallos, involucrado en el código de RADICMPI, de manera que permite todas las condiciones necesarias para validar la operación del controlador distribuido de RADIC. También se utilizó la misma implementación para estudiar las consecuencias de usar RADIC en un ambiente real. Esto permitió evaluar la operación de la arquitectura en situaciones prácticas, y estudiar la influencia de los parámetros de RADIC sobre el funcionamiento del sistema. Los resultados probaron que la arquitectura de RADIC funciona correctamente y que es flexible, escalable, transparente y descentralizada. Además, RADIC estableció una arquitectura de tolerancia a fallos para sistemas basados en paso de mensajes. / Fault tolerance has become a major issue for computer engineers and software developers because the occurrence of faults increases the cost of using a parallel computer. On the other hand, the activities performed by the fault tolerance mechanism reduce the performance of the system from the user point of view. This thesis presents RADIC (Redundant Array of Distributed Independent Fault Tolerance Controllers,) a fault-tolerant architecture to parallel computers, which is simultaneously transparent, decentralized, flexible and scalable. RADIC is a fault-tolerant architecture that implements a fully distributed controller to manage faults. Such controller rests on dedicated processes, which share the user's resources in the parallel computer. In order to validate the operation of RADIC, we created RADICMPI, a message-passing implementation that includes the elements of the RADIC architecture and complies with the MPI-1 standard. RADICMPI served for to verifying the functionality of RADIC in scenarios with and without failures in the parallel computer. For the tests, we implemented a fault injector in RADICMPI in order to create the scenarios required to validate the operation of the RADIC distributed controller. We also used RADICMPI to study the practical aspects of using RADIC in a real environment. This allowed us to evaluate the operation of our architecture in practical situations, and to study the influence of the RADIC parameters over the system performance. The results proved that the RADIC architecture operated correctly and that it is flexible, scalable, transparent and decentralized. Furthermore, RADIC established a powerful fault-tolerant architecture model for message-passing systems.
239

Multipath Fault-tolerant Routing Policies to deal with Dynamic Link Failures in High Speed Interconnection Networks

Zarza, Gonzalo Alberto 08 July 2011 (has links)
Les xarxes d'interconnexió tenen com un dels seus objectius principals comunicar i enllaçar els nodes de processament dels sistemes de còmput d'altes prestacions. En aquest context, les fallades de xarxa tenen un impacte considerablement alt, ja que la majoria dels algorismes d'encaminament no van ser dissenyats per tolerar aquestes anomalies. A causa d'això, fins i tot una única fallada d'enllaç té la capacitat d'embussar missatges a la xarxa, provocant situacions de bloqueig o, encara pitjor, és capaç d'impedir la correcta finalització de les aplicacions que es trobin en execució en el sistema de còmput. En aquesta tesi presentem polítiques d'encaminament tolerants a fallades basades en els conceptes d'adaptabilitat i evitació de bloquejos, dissenyades per a xarxes afectades per un gran nombre de fallades d'enllaços. Es presenten dues contribucions al llarg de la tesi, a saber: un mètode d'encaminament tolerant a fallades multicamí, i una tècnica nova i escalable d'evitació de bloquejos. La primera de les contribucions de la tesi és un algorisme d'encaminament adaptatiu multicamí, anomenat Fault-tolerant Distributed Routing Balancing (FT-DRB), que permet explotar la redundància de camins de comunicació de les topologies de xarxa actuals, a fi de proveir tolerància a fallades a les xarxes d'interconnexió. La segona contribució de la tesi és la tècnica escalable d'evitació de bloquejos Non-blocking Adaptive Cycles (NAC). Aquesta tècnica va ser específicament dissenyada per funcionar en xarxes d'interconnexió que presentin un gran nombre de fallades d'enllaços. Aquesta tècnica va ser dissenyada i implementada amb la finalitat de servir al mètode d'encaminament descrit anteriorment, FT-DRB. / Las redes de interconexión tienen como uno de sus objetivos principales comunicar y enlazar los nodos de procesamiento de los sistemas de cómputo de altas prestaciones. En este contexto, los fallos de red tienen un impacto considerablemente alto, ya que la mayoría de los algoritmos de encaminamiento no fueron diseñados para tolerar dichas anomalías. Debido a esto, incluso un único fallo de en un enlace tiene la capacidad de atascar mensajes en la red, provocando situaciones de bloqueo o, peor aún, es capaz de impedir la correcta finalización de las aplicaciones que se encuentren en ejecución en el sistema de cómputo. En esta tesis presentamos políticas de encaminamiento tolerantes a fallos basadas en los conceptos de adaptabilidad y evitación de bloqueos, diseñadas para redes de comunicación afectadas por un gran número de fallos de enlaces. Se presentan dos contribuciones a lo largo de la tesis, a saber: un método de encaminamiento tolerante a fallos multicamino, y una novedosa y escalable técnica de evitación de bloqueos. La primera de las contribuciones de la tesis es un algoritmo de encaminamiento adaptativo multicamino, denominado Fault-tolerant Distributed Routing Balancing (FT-DRB), que permite explotar la redundancia de caminos de comunicación de las topologías de red actuales, a fin de proveer tolerancia a fallos a las redes de interconexión. La segunda contribución de la tesis es la técnica escalable de evitación de bloqueos Non-blocking Adaptive Cycles (NAC). Dicha técnica fue específicamente diseñada para funcionar en redes de interconexión que presenten un gran número de fallos de enlaces. Esta técnica fue diseñada e implementada con la finalidad de servir al método de encaminamiento descrito anteriormente, FT-DRB. / Interconnection networks communicate and link together the processing units of modern high-performance computing systems. In this context, network faults have an extremely high impact since most routing algorithms have not been designed to tolerate faults. Because of this, as few as one single link failure may stall messages in the network, leading to deadlock configurations or, even worse, prevent the finalization of applications running on computing systems. In this thesis we present fault-tolerant routing policies based on concepts of adaptability and deadlock freedom, capable of serving interconnection networks affected by a large number of link failures. Two contributions are presented throughout this thesis, namely: a multipath fault-tolerant routing method, and a novel and scalable deadlock avoidance technique. The first contribution of this thesis is the adaptive multipath routing method Fault-tolerant Distributed Routing Balancing (FT-DRB). This method has been designed to exploit the communication path redundancy available in many network topologies, allowing interconnection networks to perform in the presence of a large number of faults. The second contribution is the scalable deadlock avoidance technique Non-blocking Adaptive Cycles (NAC), specifically designed for interconnection networks suffering from a large number of failures. This technique has been designed and implemented with the aim of ensuring freedom from deadlocks in the proposed fault-tolerant routing method FT-DRB.
240

Analyzing IP/MPLS as Fault Tolerant Network Architecture

Kebria, Muhammad Roohan January 2012 (has links)
MPLS is a widely used technology in the service providers and enterprise networks across the globe. MPLS-enabled infrastructure has the ability to transport any type of payload (ATM, Frame Relay and Ethernet) over it, subsequently providing a multipurpose architecture. An incoming packet is classified only once as it enters into the MPLS domain and gets assigned label information; thereafter all decision processes along a specified path is based upon the attached label rather than destination IP addresses. As network applications are becoming mission critical, the requirements for fault tolerant networks are increasing, as a basic requirement for carrying sensitive traffic. Fault tolerance mechanisms as provided by an IP/MPLS network helps in providing end to end “Quality of Service” within a domain, by better handling blackouts and brownouts. This thesis work reflects how MPLS increases the capability of deployed IP infrastructure to transport traffic in-between end devices with unexpected failures in place. It also focuses on how MPLS converts a packet switched network into a circuit switched network, while retaining the characteristics of packet switched technology. A new mechanism for MPLS fault tolerance is proposed.

Page generated in 0.3643 seconds