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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.
131

Quality control for integrated GNSS and inertial navigation systems

Hewitson, Steve, Surveying & Spatial Information Systems, Faculty of Engineering, UNSW January 2006 (has links)
The availability of GPS signals is a major limitation for many existing and potential applications. Fortunately, with the development of Galileo by the European Commission (EC) and European Space Agency (ESA) and new funding for the restoration of the Russian GLONASS announced by the Russian Federation the future for satellite based positioning and navigation applications is extremely promising. This research primarily investigates the benefits of GNSS interoperability and GNSS/INS integration to Receiver Autonomous Integrity Monitoring (RAIM) from a geometrical perspective. In addition to these investigations, issues regarding multiple outlier detection and identification are examined and integrity procedures addressing these issues are proposed. Moreover, it has been shown how the same RAIM algorithms can be effectively applied to the various static and kinematic navigation architectures used in this research.
132

Övervakningens effekt på individen : Kopplingen till fenomenet social önskvärdhet

Wall, Magnus, Sundgren, Patrik January 2008 (has links)
<p>Att göra det som förväntas av en, att inte sticka ut, leder i samband med en tilltagande övervakning till en ökad konformitet. En av anledningarna till detta skall vara individens drift att passa in, att vara socialt önskvärd. Detta var ett grundantagande inför den experimentella hypotesprövning som ligger till grund för aktuell studie. Även liknande studier i ämnet har bekräftat detta antagande vilket framgått av litteraturgenomgången inför studien. Urvalet var ett tillgänglighetsurval bestående av högskolestudenter i olika åldrar och av olika kön. Uppnådda resultat var inte de förväntade vilket i sig är intressant och torde kunna leda in den framtida forskningen på nya fält.</p>
133

Evaluation of Cryptographic Packages

Raheem, Muhammad January 2009 (has links)
<p>The widespread use of computer technology for information handling resulted in the need for higher data protection.The usage of high profile cryptographic protocols and algorithms do not always necessarily guarantee high security. They are needed to be used according to the needs of the organization depending upon certain characteristics and available resources.The communication system in a cryptographic environment may become vulnerable to attacks if the cryptographic packages don’t meet their intended goals.</p><p>This master’s thesis is targeted towards the goal of evaluating contemporary cryptographic algorithms and protocols collectively named as cryptographic packages as per security needs of the organization with the available resources.</p><p>The results have shown that there certainly is a need for careful evaluations of cryptographic packages given with available resources otherwise it could turn into creating more severe problems such as network bottlenecks, information and identity loss, non trustable environment and computational infeasibilities resulting in huge response times. In contrast, choosing the right package with right security parameters can lead to a secure and best performance communication environment.</p>
134

Methodology to quantify leaks in aerosol sampling system components

Vijayaraghavan, Vishnu Karthik 15 November 2004 (has links)
Filter holders and continuous air monitors (CAMs) are used extensively in the nuclear industry. It is important to minimize leakage in these devices and in recognition of this consideration, a limit on leakage for sampling systems is specified in ANSI/HPS N13.1-1999; however the protocol given in the standard is really germane to measurement of significant leakage, e.g., several percent of the sampling flow rate. In the present study, a technique for quantifying leakage was developed and that approach was used to measure the sealing integrity of a CAM and two kinds of filter holders. The methodology involves use of sulfur hexafluoride as a tracer gas with the device being tested operated under dynamic flow conditions. The leak rates in these devices were determined in the pressure range from 2.49 kPa (10 In. H2O) vacuum to 2.49 kPa (10 In. H2O) pressure at a typical flow rate of 56.6 L/min (2 cfm). For the two filter holders, the leak rates were less than 0.007% of the nominal flow rate. The leak rate in the CAM was less than 0.2% of the nominal flow rate. These values are well within the limit prescribed in the ANSI standard, which is 5% of the nominal flow rate. Therefore the limit listed in the ANSI standard should be reconsidered as lower values can be achieved, and the methodology presented herein can be used to quantify lower leakage values in sample collectors and analyzers. A theoretical analysis was also done to determine the nature of flow through the leaks and the amount of flow contribution by the different possible mechanisms of flow through leaks.
135

Grid Fault management techniques: the case of a Grid environment with malicious entities

Akimana, Rachel 01 October 2008 (has links)
La tolérance et la gestion des fautes dans les grilles de données/calcul est d’une importance capitale. En effet, comme dans tout autre système distribué, les composants d’une grille sont susceptibles de tomber en panne à tout moment. Mais le risque de panne croît avec la taille du système, et est donc plus exacerbé dans un système de grille. En plus, tout en essayant de mettre à profit les ressources offertes par la grille, les applications tournant sur celle-ci sont de plus en plus complexes (ex. impliquent des interactions complexes, prennent des jours d’exécution), ce qui les rend plus vulnérables aux fautes. Le plus difficile dans la gestion des fautes dans une grille, c’est qu’il est difficile de savoir si une faute qui survient sur une entité de la grille est induite malicieusement ou accidentellement. Dans notre travail de thèse, nous utilisons le terme faute, au sens large, pour faire référence à tout étant inattendu qui survient sur tout composant de la grille. Certains de ces états provoquent des comportements aussi inattendus et perceptibles au niveau de la grille tandis que d’autres passent inaperçues. De plus, certaines de ces fautes sont le résultat d’une action malveillante alors que d’autres surviennent accidentellement ou instantanément. Dans ce travail de thèse, nous avons traité le cas de ces fautes induites malicieusement, et qui généralement passent inaperçues. Nous avons considéré en particulier le problème de la confidentialité et de l’intégrité des données stockées à long-terme sur la grille. L’étude de la confidentialité des données a été faite en deux temps dont la première partie concerne la confidentialité des données actives. Dans cette partie, nous avons considéré une application liée à la recherche des similitudes d’une séquence d’ADN dans une base de données contenant des séquences d’ADN et stockée sur la grille. Pour cela, nous avons proposé une méthode qui permet d’effectuer la comparaison sur un composant distant, mais tout en gardant confidentielle la séquence qui fait l’objet de la comparaison. Concernant les données passives, nous avons proposé une méthode de partage des données confidentielles et chiffrés sur la grille. En rapport avec l’intégrité des données, nous avons considéré le cas des données anonymes dans le cadre de l’intégrité des données passives. Pour les données actives, nous avons considéré le problème de la corruption des jobs exécutés sur la grille. Pour chacune des cas, nous avons proposé des mécanismes permettant de vérifier l’authenticité des données utilisées ou produites par ces applications.
136

Övervakningens effekt på individen : Kopplingen till fenomenet social önskvärdhet

Wall, Magnus, Sundgren, Patrik January 2008 (has links)
Att göra det som förväntas av en, att inte sticka ut, leder i samband med en tilltagande övervakning till en ökad konformitet. En av anledningarna till detta skall vara individens drift att passa in, att vara socialt önskvärd. Detta var ett grundantagande inför den experimentella hypotesprövning som ligger till grund för aktuell studie. Även liknande studier i ämnet har bekräftat detta antagande vilket framgått av litteraturgenomgången inför studien. Urvalet var ett tillgänglighetsurval bestående av högskolestudenter i olika åldrar och av olika kön. Uppnådda resultat var inte de förväntade vilket i sig är intressant och torde kunna leda in den framtida forskningen på nya fält.
137

Maintaining Integrity Constraints in Semantic Web

Fang, Ming 10 May 2013 (has links)
As an expressive knowledge representation language for Semantic Web, Web Ontology Language (OWL) plays an important role in areas like science and commerce. The problem of maintaining integrity constraints arises because OWL employs the Open World Assumption (OWA) as well as the Non-Unique Name Assumption (NUNA). These assumptions are typically suitable for representing knowledge distributed across the Web, where the complete knowledge about a domain cannot be assumed, but make it challenging to use OWL itself for closed world integrity constraint validation. Integrity constraints (ICs) on ontologies have to be enforced; otherwise conflicting results would be derivable from the same knowledge base (KB). The current trends of incorporating ICs into OWL are based on its query language SPARQL, alternative semantics, or logic programming. These methods usually suffer from limited types of constraints they can handle, and/or inherited computational expensiveness. This dissertation presents a comprehensive and efficient approach to maintaining integrity constraints. The design enforces data consistency throughout the OWL life cycle, including the processes of OWL generation, maintenance, and interactions with other ontologies. For OWL generation, the Paraconsistent model is used to maintain integrity constraints during the relational database to OWL translation process. Then a new rule-based language with set extension is introduced as a platform to allow users to specify constraints, along with a demonstration of 18 commonly used constraints written in this language. In addition, a new constraint maintenance system, called Jena2Drools, is proposed and implemented, to show its effectiveness and efficiency. To further handle inconsistencies among multiple distributed ontologies, this work constructs a framework to break down global constraints into several sub-constraints for efficient parallel validation.
138

Model based simulation of broaching operation: cutting mechanics, surface integrity, and process optimization

Hosseini, Sayyed Ali 01 April 2013 (has links)
Machining operations are widely used to produce parts with different shapes and complicated profiles. As a machining operation, broaching is commonly used for the machining of a broad range of complex internal and external profiles either circular or non-circular such as holes, keyways, guide ways, and slots on turbine discs having fir-tree shape. Broaching is performed by pushing or pulling a tapered tool through the workpiece to remove the unwanted material and produce the required profile. Broaching is also acknowledged because of its high productivity and attainable surface quality in comparison to the other machining processes. The objective of this thesis is to simulate the broaching operation and use the results to present a methodology for optimum design of the broaching tools. In the course of the presented thesis, a new B-spline based geometric model is developed for broaching cutting edges followed by model validation using 3D ACIS modeller. To study the mechanics of cutting and generated cutting forces during broaching operation, an energy based force model is presented which can predict the cutting forces based on the power spent in the cutting system. An experimental investigation is conducted in order to confirm the estimated forces. The integrity of the broached surface is also investigated by focusing on surface roughness, subsurface microhardness, and subsurface microstructure as three major parameters of surface integrity. An optimization procedure for broaching tools design is presented in this thesis. A mathematical representation of broaching tooth geometry is also presented which is used to simulate the tooth as a cantilevered beam subjected to a distributed load. The beam is solved considering the given design constraints to achieve optimum geometric parameters for maximum durability and performance. / UOIT
139

Trust in e-Mentoring Relationships

Walabe, Eman 05 March 2013 (has links)
The role of trust in traditional face-to-face mentoring has already been investigated in several research studies. However, to our knowledge, very few studies have examined how trust is established in electronic-mentoring relationships. The purpose of the current study is to examine by means of the Mayer et al. (1995) model how e-mentees perceive a prospective e-mentor's trustworthiness and how these perceptions influence the decision to be mentored by a particular e-mentor. A sample comprised of 253 undergraduate and graduate students from the Telfer School of Management at the University of Ottawa participated as potential mentees by completing a survey after having reviewed the selected e-mentor’s profile. The survey employed quantitative and qualitative measurements to assess the mentee's perception of the prospective e-mentor’s level of trustworthiness. In the quantitative section, both the Behavioural Trust Inventory (Gillespie, 2003) and the Factors of Perceived Trustworthiness (Mayer et al., 1999) were measured. The Behavioural Trust Inventory was designed to measure the extent to which a mentee is willing to be vulnerable in e-mentoring relationships. The Factors of Perceived Trustworthiness (ability, benevolence and integrity) were designed to measure these three attributes’ contributions to the extent to which the mentees perceived the e-mentor as being trustworthy. The factorial structure (confirmatory factor analysis) and internal consistency (Cronbach’s alpha) of the constructs were examined. Structural equation modeling was conducted to test the fit of the models (Behavioural Trust Inventory and Mayer et al.) to an e-mentoring context. In the qualitative section, the indicators of trustworthiness were collected by means of an open-ended question and were analyzed by means of content analysis. The results of the quantitative analysis revealed that the models (the Behavioural Trust Inventory and the Factors of Perceived Trustworthiness) have an adequate fit with the e-mentoring model after accounting for some correlated error terms. The results of the qualitative analysis identified some other attributes (apart from ability, benevolence and integrity groups) have an influence on the extent to which the mentees perceived the e-mentor as being trustworthy. The main finding is that the Mayer et al. (1995) model appears to be a suitable device for the measurement of trust in e-mentoring relationships at the initiation phase.
140

On-chip Power Grid Verification with Reduced Order Modeling

Goyal, Ankit 31 December 2010 (has links)
To ensure the robustness of an integrated circuit design, its power distribution network (PDN) must be validated beforehand against any voltage drop on VDD nets. However, due to the increasing size of PDNs, it is becoming difficult to verify them in a reasonable amount of time. Lately, much work has been done to develop Model Order Reduction (MOR) techniques to reduce the size of power grids but their focus is more on simulation. In verification, we are concerned about the safety of nodes, including the ones which have been eliminated in the reduction process. This work proposes a novel approach to systematically reduce the power grid and accurately compute an upper bound on the voltage drops at power grid nodes which are retained. Furthermore, a criterion for the safety of nodes which are removed is established based on the safety of other nearby nodes and a user specified margin.

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