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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.

Situation-aware routing for wireless mesh networks with mobile nodes

Kobo,Hlabishi January 2012 (has links)
No description available.


Hsieh, Chin-Nan 27 July 2001 (has links)


Chen, Yu-Lin 27 July 2001 (has links)

Situation-aware routing for wireless mesh networks with mobile nodes

Kobo,Hlabishi January 2012 (has links)
No description available.

Impact of network security on SDN controller performance

Kodzai, Carlton January 2020 (has links)
Internet Protocol network architectures are gradually evolving from legacy flat networks to new modern software defined networking approaches. This evolution is crucial as it provides the ideal supporting network structure, architecture and framework that supports the technologies that are also evolving in software-based systems like Network Functions Virtualization (NFV). The connectivity requirements resulting from this paradigm shift in technology is being driven by new bandwidth requirements emanating from the huge number of new use cases from 5G networks and Internet of things (IoT) future technologies. Network security remains a key critical requirement of these new modern network architectures to deliver a highly available, reliable service and guaranteed quality of service. Unprotected networks will usually experience service interruptions and cases of system non-availability due to network attacks such as denial-of services and virus attacks which can render key network components unusable or totally unavailable. With the centralized approach of the Software Defined Networking architecture, the SDN controller becomes a key network point that is susceptible to internal and external attacks from hackers and many forms of network breaches. It being the heart of the SDN network makes it a single point of failure and it is crucial that the security of the controller is guaranteed to avoid unnecessary irrecoverable loss of valuable production time, data and money. The SDN controller design should be guided by a robust security policy framework with a very sound remedy and business continuity plan in the event of any form of a security attack. Security designs and research work in SDN controllers have been done with focus on achieving the most reliable and scalable platforms through self-healing and replication processes. In this dissertation the research that was done proposed a security solution for the SDN controller and evaluated the impact of the security solution on the overall SDN controller performance. As part of the research work literature review of the SDN controller and related technology carried out. The SDN controller interfaces were analyzed and the security threats that attack interfaces were explored. With link to a robust security framework a security solution was used in the experiments that analyzed the attacks from the external network sources which focused on securing the southbound interface by use of a netfilter with iptables firewall on the SDN controller. The SDN controller was subjected to denial service attack packets and the impact of the mitigation action observed on the SDN controller resources. Given that the network security layer introduced an additional overhead on the SDN controller's processors the security feature negatively affected the controller performance. The impact of the security overhead will inform on the future designs and possibly achieve a trade-off point between the level of security of the network and overall system performance due to security policies. The research analyzed and determined the performance impact of this crucial design aspect and how the additional loading due to network security affected the SDN controller normal operation.

A Hybrid Data Acquisition Architecture on the CH-53K Program

Dehmelt, Chris 10 1900 (has links)
ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / As today's flight test programs need for sensor and bus data continue to increase, there has been associated requirements to provide modern system output products and support higher encoder data rates. The CH-53K Heavy Lift Replacement (HLR) Program is an example in which the instrumentation data requirements have increased significantly over previous helicopter programs and necessitated the introduction of new technologies and capabilities. The CH-53K Program utilizes a hybrid system architecture that combines the benefits of legacy PCM and modern networked system architectures. The system provides for maintaining the required system-wide synchronized sampling capabilities, while providing real-time data access and system control over a vehicle network. Serial Streaming Telemetry (SST)-to-vNET Adapters are employed to enable many of these capabilities. This paper describes the instrumentation requirements for the CH-53K program and the features, tools and performance of its data acquisition system - which addressed all requirements while minimizing the overall impact to the existing instrumentation infrastructure.

Vertical motion control of twin-hull vessels in regular head seas using a neural optimal controller

Kenevissi, Farhad January 2000 (has links)
No description available.

A heuristic tool for indoor radio-wave propagation prediction

Whitaker, Brian 03 November 2006 (has links)
Faculty of Engineering, School of Electrical and Information Engineering, MSc Dissertation / For the effective implementation of a wireless local area network (WLAN) within a building, a complete understanding of indoor signal propagation is required. This paper compares three empirical propagation prediction models with regards to efficiency and accuracy. To achieve this, a software prediction tool was developed using C++ which allows an end user to quickly draw a building floor plan using user specified drawing materials. It also has the ability to calculate the required empirical parameters from entered measurements but this was found to produce results similar to that when theoretical empirical parameters were used. The accuracy of the prediction tool was gauged by comparing its outputs, using the different empirical models, to measurements. In doing so it was determined that two of the models produced functional levels of accuracy in which 93% and 82% of the simulated results were within 15 and 10 dB of the measured results respectively for the most accurate of the models used. All three empirical models were found to have computational times low enough, less than 5 minutes for an average building, as to allow for interactive WLAN design.

Etude de la diversité métabolique dans l'espèce Escherichia coli : a l'aide de réseaux et de modèles du métabolisme à l'échelle de l'organisme / Metabolic diversity in Escherichia coli species : using metabolic networks and models at genome scale

Vieira, Gilles 05 December 2011 (has links)
Il existe plusieurs façons de concevoir l’étude des différences métaboliques chez les microorganismes. On peut s’intéresser à des variations des capacités métaboliques des organismes. Derrière cette analyse se cache niveau d’étude à l’échelle la cellule qui permet d’avoir une vue d’ensemble des capacités de croissance de l’organisme dans différentes conditions. Dans cette thèse, nous proposons une nouvelle stratégie de reconstruction de réseaux et de modèles du métabolisme à l’échelle globale. Cette stratégie s’applique à un nombre quelconque d’organismes à condition qu’ils soient de la même espèce et qu’il existe un réseau métabolique de référence de bonne qualité pour au moins l’un d’entre eux. Le point clé de cette stratégie repose sur l’utilisation et la propagation automatisée des connaissances déjà acquises sur les organismes étudiés. Nous avons appliqué cette stratégie pour reconstruire et étudier les réseaux métaboliques de 23 Escherichia coli et 6 Shigellas. Nous avons ensuite converti ces réseaux en modèles métaboliques pour explorer les capacités physiologiques des différentes souches. Nous avons comparé nos prédictions de croissance à des expériences de croissance ainsi qu’aux résultats du modèle de référence. Au final le travail réalisé propose une nouvelle stratégie de reconstruction de réseaux et de modèles du métabolisme à l’échelle de la cellule, qui permet d’étudier le lien entre l’évolution et les capacités métaboliques des organismes étudiés. / Metabolic differences in microorganisms can be focused on the variations in metabolic capacities. This analysis is at genome scale, and provides a global view of the organism’s growth capacities under various conditions. In this project, we propose a new strategy to reconstruct metabolic networks and models at genome scale. Our strategy can be applied to any number of organisms as long as they are members of the same species and a curated metabolic network for one of the strains of this species is already reconstructed. The keystone of the strategy is the automatic utilization and propagation of both specific knowledge of the species and general knowledge in metabolic databases. This strategy was applied, to study the metabolic network of 23 strains of Escherichia coli and 6 of Shigella. Next, we have converted these networks into metabolic models to explore the metabolic capacities of these organisms. We compared the growth predictions of the models to experimental growth observations and also to the reference model. Finally, the studies carried out for this thesis consist of a new strategy, which allows the reconstruction of metabolic networks and models at cell scale. The models give us the opportunity to study the link between evolution, genomes and metabolic capacities of these organisms.

Distributed DHCP for WMNs using IPv6

Molerón Bermudez, Daniel, Sánchez-Camacho Capilla, Sergio January 2007 (has links)
<p>In a Wireless Mesh Network (WMN) exists mobile nodes which have an</p><p>unpredictable behaviour, i.e. they can join, leave and free move around the</p><p>network. For this reason, a static network configuration is not proper for them. A</p><p>distributed Dynamic Host Configuration Protocol (DHCP) is needed due to the</p><p>unavailability of a centralized server in a network placed over a vast extension.</p><p>This report shows a Distributed DHCP for WMNs using IPv6 (Internet Protocol</p><p>version 6). It is fault tolerant, robust and durable. The algorithm was created using</p><p>counters Bloom filters as data structure. After, a complete simulation of the system</p><p>was done. The simulations showed that using 24 servers with 16Mbits of memory</p><p>each one is possible to manage around 9000000 clients without adding an excessive</p><p>network load. Therefore, the DDHCPv6 could be in a near future the host</p><p>configuration protocol in WMN.</p>

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