• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 19
  • 15
  • 11
  • 3
  • 1
  • 1
  • 1
  • Tagged with
  • 62
  • 62
  • 17
  • 11
  • 11
  • 9
  • 8
  • 8
  • 8
  • 8
  • 7
  • 7
  • 7
  • 6
  • 6
  • 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.
31

An Investigation into the Performance Evaluation of Connected Vehicle Applications: From Real-World Experiment to Parallel Simulation Paradigm

Ahmed, Md Salman 01 May 2017 (has links)
A novel system was developed that provides drivers lane merge advisories, using vehicle trajectories obtained through Dedicated Short Range Communication (DSRC). It was successfully tested on a freeway using three vehicles, then targeted for further testing, via simulation. The failure of contemporary simulators to effectively model large, complex urban transportation networks then motivated further research into distributed and parallel traffic simulation. An architecture for a closed-loop, parallel simulator was devised, using a new algorithm that accounts for boundary nodes, traffic signals, intersections, road lengths, traffic density, and counts of lanes; it partitions a sample, Tennessee road network more efficiently than tools like METIS, which increase interprocess communications (IPC) overhead by partitioning more transportation corridors. The simulator uses logarithmic accumulation to synchronize parallel simulations, further reducing IPC. Analyses suggest this eliminates up to one-third of IPC overhead incurred by a linear accumulation model.
32

Assist Principals' Perspectives on Professional Learning Conversations for Teacher Professional Growth

Kolosey, Connie 01 January 2011 (has links)
The purpose of this study was to discover, document, and describe the salient actions, events, beliefs, attitudes, social structures and processes related to professional learning conversations from the perspective of nine assistant principals (APs). The participants were elementary, middle and high school APs, three at each level. Using a modified critical incident technique through participant written response and two in depth interviews with each respondent, this study investigated the lived experiences of these APs related to the practice of professional learning conversations in their schools. The research questions focused on: (1) the participants' beliefs and attitudes about professional learning conversations, (2) their roles in facilitating these conversations, (3) their ability to identify elements of trust within the groups of teachers with whom they work and (4) their roles in building trust. The research literature is clear that teacher collaboration is a key factor in professional growth and self-efficacy, yet often the structure of the school day, a negative emotional environment, and a culture of teacher isolation prohibit meaningful teacher collaboration. Although faced with many obligations and directives, school administrators have considerable influence over the organizational structure within their individual schools. Furthermore, assistant principals often become the face of administration within their schools as they directly supervise teachers and APs are less studied than students, teacher or principals. How these individuals perceive and value professional learning conversations will likely impact the level of collaboration at their individual schools. The findings of this study indicate that professional learning conversations for teacher growth were more prevalent at the elementary school level, that trust may be more difficult to cultivate at the middle and high schools, and that protocols as structures for facilitating conversations and building trust were not widely in use. A better understanding of the opportunities and barriers schools face related to professional learning conversations as well as a better understanding of the dynamics of trust will assist district and school administrators to engage in a problem solving process for better collaboration. Ultimately, administrators have an opportunity and a responsibility to touch the hearts and minds of the individuals on the front line of the work - the teachers in the classrooms working with students. Without teacher confidence, hope, optimism, resilience and self-efficacy, no amount of financial incentive, cajoling, or sanction will improve student learning.
33

FITT : fault injection test tool to validate safety communication protocols / FITT : a fault injection tool to validate safety communication protocols / Uma ferramenta de injeção de falhas para validar protocolos de comunicação seguros

Dobler, Rodrigo Jaureguy January 2016 (has links)
Protocolos de comunicação seguros são essenciais em ambientes de automação industrial, onde falhas não detectadas na comunicação de dispositivos podem provocar danos irreparáveis à vida ou ao meio-ambiente. Esses protocolos seguros devem ser desenvolvidos de acordo com alguma norma de segurança, como a IEC 61508. Segundo ela, faz parte do processo de implementação destes protocolos, a escolha de técnicas adequadas de validação, entre elas a injeção de falhas, a qual deve considerar um modelo de falhas apropriado ao ambiente de operação do protocolo. Geralmente, esses ambientes são caracterizados pela existência de diversas formas de interferência elétrica e eletromagnética, as quais podem causar falhas nos sistemas eletrônicos existentes. Nos sistemas de comunicação de dados, isto pode levar a destruição do sinal de dados e causar estados de operação equivocados nos dispositivos. Assim, é preciso utilizar uma técnica de injeção de falhas que permita simular os tipos de erros de comunicação que podem ocorrer nos ambientes industriais. Dessa forma, será possível verificar o comportamento dos mecanismos de tolerância falhas na presença de falhas e assegurar o seu correto funcionamento. Para esta finalidade, este trabalho apresenta o desenvolvimento do injetor de falhas FITT para validação de protocolos de comunicação seguros. Esta ferramenta foi desenvolvida para ser utilizada com o sistema operacional Linux. O injetor faz uso do PF_RING, um módulo para o Kernel do Linux, que é responsável por realizar a comunicação direta entre as interfaces de rede e o injetor de falhas. Assim os pacotes não precisam passar pelas estruturas do Kernel do Linux, evitando que atrasos adicionais sejam inseridos no processo de recebimento e envio de mensagens. As funções de falhas desenvolvidas seguem o modelo de falhas de comunicação descrito na norma IEC 61508. Esse modelo é composto pelos erros de repetição, perda, inserção, sequência incorreta, endereçamento, corrupção de dados, atraso, mascaramento e falhas de memória em switches. / Safe communication protocols are essential in industrial automation environments, where undetected failures in the communication of devices can cause irreparable damage to life or to the environment. These safe protocols must be developed according to some safety standard, like IEC 61508. According to it, part of the process of implementing these protocols is to select appropriate techniques for validation, including the fault injection, which should consider an appropriate fault model for the operating environment of the protocol. Generally, these environments are characterized by the existence of various forms of electric and electromagnetic interference, which can cause failures in existing electronic systems. In data communication systems, this can lead to the destruction of the data signal and cause erroneous operation states in the devices. Thus, it is necessary to use a fault injection technique that allows simulating the types of communication errors that may occur in industrial environments. So, it will be possible to verify the behavior of the fault tolerance mechanisms in the presence of failures and ensure its correct functioning. For this purpose, this work presents the development of FITT fault injector for validation of safety communication protocols. This tool was developed to be used with Linux operating system. The fault injector makes use of PF_RING, a module for the Linux Kernel and that is responsible to perform the direct communication between the network interfaces and the fault injector. Thus the packages do not need to go through the Linux Kernel structures, avoiding additional delays to be inserted into the process of receiving and sending messages. The developed fault injection functions follow the communication fault model described in the IEC61508 standard, composed by the errors of repetition, loss, insertion, incorrect sequence, addressing, data corruption, delay, masking and memory failures within switches. The fault injection tests applied with this model allow to properly validate the fault tolerance mechanisms of safety protocols.
34

GATE - Uma abordagem baseada em middleware para aplica??es interperceptivas envolvendo m?ltiplos dispositivos

Dantas, Rummenigge Rudson 18 January 2010 (has links)
Made available in DSpace on 2014-12-17T14:54:53Z (GMT). No. of bitstreams: 1 RummeniggeRD.pdf: 4734896 bytes, checksum: 7fd06946288490f84ee082f6f9ad36dd (MD5) Previous issue date: 2010-01-18 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In this work, we present the GATE, an approach based on middleware for interperceptive applications. Through the services offered by the GATE, we extension we extend the concept of Interperception for integration with several devices, including set-top box, mobile devices (cell phones), among others. Through this extension ensures the implementation of virtual environments in these devices. Thus, users who access the version of the computer environment may interact with those who access the same environment by other devices. This extension is just a part of the services provided by the GATE, that remerges as a new proposal for multi-user virtual environments creation. / Neste trabalho, apresentamos o GATE, uma abordagem baseada em middleware para aplica??es interperceptivas. Atrav?s dos servi?os oferecidos pelo GATE, estendemos o conceito da Interpercep??o para a integra??o com v?rios dispositivos, incluido set-top box, dispositivos m?veis (celulares), entre outros. Atrav?s desta extens?o garantimos a execu??o de ambientes virtuais nesses dispositivos. Assim, usu?rios que acessarem a vers?o do ambiente pelo computador poder?o interagir com aqueles que acessarem o mesmo ambiente por outros dispositivos. Essa extens?o ? apenas uma parte dos servi?os garantidos pelo GATE, surge como uma nova proposta para cria??o de ambientes virtuais multisu?rios.
35

FITT : fault injection test tool to validate safety communication protocols / FITT : a fault injection tool to validate safety communication protocols / Uma ferramenta de injeção de falhas para validar protocolos de comunicação seguros

Dobler, Rodrigo Jaureguy January 2016 (has links)
Protocolos de comunicação seguros são essenciais em ambientes de automação industrial, onde falhas não detectadas na comunicação de dispositivos podem provocar danos irreparáveis à vida ou ao meio-ambiente. Esses protocolos seguros devem ser desenvolvidos de acordo com alguma norma de segurança, como a IEC 61508. Segundo ela, faz parte do processo de implementação destes protocolos, a escolha de técnicas adequadas de validação, entre elas a injeção de falhas, a qual deve considerar um modelo de falhas apropriado ao ambiente de operação do protocolo. Geralmente, esses ambientes são caracterizados pela existência de diversas formas de interferência elétrica e eletromagnética, as quais podem causar falhas nos sistemas eletrônicos existentes. Nos sistemas de comunicação de dados, isto pode levar a destruição do sinal de dados e causar estados de operação equivocados nos dispositivos. Assim, é preciso utilizar uma técnica de injeção de falhas que permita simular os tipos de erros de comunicação que podem ocorrer nos ambientes industriais. Dessa forma, será possível verificar o comportamento dos mecanismos de tolerância falhas na presença de falhas e assegurar o seu correto funcionamento. Para esta finalidade, este trabalho apresenta o desenvolvimento do injetor de falhas FITT para validação de protocolos de comunicação seguros. Esta ferramenta foi desenvolvida para ser utilizada com o sistema operacional Linux. O injetor faz uso do PF_RING, um módulo para o Kernel do Linux, que é responsável por realizar a comunicação direta entre as interfaces de rede e o injetor de falhas. Assim os pacotes não precisam passar pelas estruturas do Kernel do Linux, evitando que atrasos adicionais sejam inseridos no processo de recebimento e envio de mensagens. As funções de falhas desenvolvidas seguem o modelo de falhas de comunicação descrito na norma IEC 61508. Esse modelo é composto pelos erros de repetição, perda, inserção, sequência incorreta, endereçamento, corrupção de dados, atraso, mascaramento e falhas de memória em switches. / Safe communication protocols are essential in industrial automation environments, where undetected failures in the communication of devices can cause irreparable damage to life or to the environment. These safe protocols must be developed according to some safety standard, like IEC 61508. According to it, part of the process of implementing these protocols is to select appropriate techniques for validation, including the fault injection, which should consider an appropriate fault model for the operating environment of the protocol. Generally, these environments are characterized by the existence of various forms of electric and electromagnetic interference, which can cause failures in existing electronic systems. In data communication systems, this can lead to the destruction of the data signal and cause erroneous operation states in the devices. Thus, it is necessary to use a fault injection technique that allows simulating the types of communication errors that may occur in industrial environments. So, it will be possible to verify the behavior of the fault tolerance mechanisms in the presence of failures and ensure its correct functioning. For this purpose, this work presents the development of FITT fault injector for validation of safety communication protocols. This tool was developed to be used with Linux operating system. The fault injector makes use of PF_RING, a module for the Linux Kernel and that is responsible to perform the direct communication between the network interfaces and the fault injector. Thus the packages do not need to go through the Linux Kernel structures, avoiding additional delays to be inserted into the process of receiving and sending messages. The developed fault injection functions follow the communication fault model described in the IEC61508 standard, composed by the errors of repetition, loss, insertion, incorrect sequence, addressing, data corruption, delay, masking and memory failures within switches. The fault injection tests applied with this model allow to properly validate the fault tolerance mechanisms of safety protocols.
36

[en] DESIGN OF INTELIGENT COMMUNICATION PROCESSORS FOR MICROCOMPUTER NETWORKS / [pt] PROJETO DE CANAIS INTELIGENTES DE COMUNICAÇÃO PARA REDES DE COMPUTADORES DE PEQUENO PORTE

EDMUNDO ALBUQUERQUE DE SOUZA E SILVA 03 January 2008 (has links)
[pt] Com o advento dos microprocessadores e a crescente diminuição do preço dos circuitos integrados LSI (Large Scale Integration) houve um aumento da utilização de computadores de pequeno porte para a realização de tarefas locais e especificas. Tornou-se, então, economicamente viável a utilização, em número cada vez maior, de redes interligando computadores de pequeno porte. O presente trabalho contém um estudo dos diversos problemas decorrentes do projeto de redes natureza, apresentando soluções adequadas a cada caso. / [en] Theappearance of microprocessors and the lowering costs LSI (Large Scale Integration) technology brought and increaase in the use of low-size computers for dedicated applications. So, it became economically feasible to interconnect such low-size computers, creating a network. A study of various problems arising from the design of such networks is presented, as well as adequated solutions for each case.
37

Etude des méthodes d'ordonnancement sur les réseaux de capteurs sans fil. / Study on Scheduling over Wireless Sensor Networks.

Alghamdi, Bandar 06 November 2015 (has links)
Les Wireless Body Area (WBAN) sont une technologie de réseau sans fil basée sur les radio-fréquences qui consiste à interconnecter sur, autour ou dans le corps humain de minuscules dispositifs pouvant effectuer des mesures (capteurs). Ces réseaux sont considérés comme les plus critiques dans les réseaux de capteurs sans fil. Ils sont basés sur des architectures de réseaux auto-organisés. Chacun des capteurs corporels reçoit ou envoie des paquets du ou au coordinateur du réseau. Ce dernier est responsable de l'ordonnancement des tâches pour l'ensemble des noeuds fils. L'ordonnancement dans les WBAN nécessite un mécanisme dynamique et adaptatif pour gérer les cas d'urgence qui peuvent se produire et permet ainsi d'améliorer les paramètres les plus importants comme la qualité de la transmission, le temps de réponse, le débit, le taux de paquets délivres, etc.Dans ces travaux de thèse, nous avons proposé trois techniques d'ordonnancement qui sont : la méthode semi-dynamique; la méthode dynamique et la méthode basée sur la priorité. De plus, une étude sur les plateformes WBAN est présentée. Dans cette étude, nous avons proposé une classification et une évaluation qualitative des plateformes déjà existantes. Nous avons aussi étudier les modèles de mobilité en proposant une architecture permettant de les décrire. Nous avons aussi mis en place une procédure de diagnostique afin de détecter rapidement des maladies épidémiques dangereuses. Par la suite, ces différentes propositions ont été validées en utilisant deux méthodes afin de vérifier leur faisabilité. Ces méthodes sont la simulation avec OPNET et l'implémentation réelle sur des capteurs TelosB et TinyOS. / The Wireless Body Area Network (WBAN) is the most critical field when considering Wireless Sensor Networks (WSN). It must be a self-organizing network architecture, meaning that it should be able to efficiently manage all network architecture requirements. The WBAN usually contains at least two or more body sensors. Each body sensor sends packets to or receives packets from the Personal Area Network Coordinator (PANC). The PANC is responsible for scheduling its child nodes' tasks. Scheduling tasks in the WBAN requires a dynamic and an adaptive process in order to handle cases of emergency that can occur with a given patient. To improve the most important parameters of a WBAN, such as quality link, response time, throughput, the duty-cycle, and packet delivery, we propose three scheduling processes: the semi-dynamic, dynamic, and priority-based dynamic scheduling approaches.In this thesis, we propose three task scheduling techniques, Semi-Dynamic Scheduling (SDS), Efficient Dynamic Scheduling (EDS) and High Priority Scheduling (HPS) approaches. Moreover, a comprehensive study has been performed for the WBAN platforms by classifying and evaluating them. We also investigate the mobility model for the WBANs by designing an architecture that describe this model. In addition, we detail a diagnosis procedure by using classification methods in order to solve very sensitive epidemic diseases. Then, our proposals have been validated using two techniques to check out the feasibility of our proposals. These techniques are simulation scenarios using the well-known network simulator OPNET and real implementations over TelosB motes under the TinyOS system.
38

Anonymity With Authenticity

Swaroop, D 12 1900 (has links) (PDF)
Cryptography is science of secure message transmission. Cryptanalysis is involved with breaking these encrypted messages. Both cryptography and cryptanalysis constitute together to form cryptology. Anonymity means namelessness i.e., the quality or state of being unknown while authenticity translates to the quality or condition of being authentic or genuine. Anonymity and authenticity are two different embodiments of personal secrecy. Modern power has increased in its capacity to designate individuals, due to which they find it inconvenient to continue communicating, remaining anonymous. In this thesis we are going to describe an anonymous system which consists of a number of entities which are anonymous and are communicating with each other without revealing their identity and at the same time maintaining their authenticity such that an anonymous entity(sayE1)will be able to verify that, the message it received from another anonymous entity(sayE2)subsequent to an initial message from E2, are in fact from E2 itself. Later when E2 tries to recommend a similar communication to E1 with another anonymous entity E3 in the system, E1 must be able to verify that recommendation, without E2 losing its authenticity of its communication with E1 to E3. This thesis is divided into four chapters. The first chapter is an introduction to cryptography, symmetric key cryptography and public key cryptography. It also summarizes the contribution of this thesis. The second chapter gives various protocol for the above problem ’Anonymity with Authenticity’ along with its extension. Totally six protocols are proposed for the above problem. In third chapter all these six protocols are realized using four different schemes, where each scheme has its own pros and cons. The fourth and final chapter concludes with a note on what possible factors these four different realization schemes need to be chosen and other possible realization schemes.
39

Exploiting Semantic for the Automatic Reverse Engineering of Communication Protocols. / Exploitation de la sémantique pour la rétro-conception automatisée de protocoles de communication.

Bossert, Georges 17 December 2014 (has links)
Cette thèse propose une approche pratique pour la rétro-conception automatisée de protocoles de communication non-documentés. Les travaux existants dans ce domaine ne permettent qu'un apprentissage incomplet des spécifications ou exigent trop de stimulation de l'implémentation du protocol cible avec le risque d'être vaincu par des techniques de contre-inférence. Cette thèse adresse ces problématiques en s'appuyant sur la sémantique du protocole cible pour améliorer la qualité, la rapidité et la furtivité du processus d'inférence. Nous appliquons cette approche à la rétro-conception des deux principaux aspects de la définition d'un protocole à savoir l'inférence de sa syntaxe et de sa grammaire. Nous proposons un outil open-source, appelé Netzob, qui implémente nos contributions pour aider les experts en sécurité dans leur lutte contre les dernières menaces informatiques. Selons nos recherches, Netzob apparait comme l'outil publié le plus avancé pour la rétro-conception et la simulation de protocoles de communications non-documentés. / This thesis exposes a practical approach for the automatic reverse engineering of undocumented communication protocols. Current work in the field of automated protocol reverse engineering either infer incomplete protocol specifications or require too many stimulation of the targeted implementation with the risk of being defeated by counter-inference techniques. We propose to tackle these issues by leveraging the semantic of the protocol to improve the quality, the speed and the stealthiness of the inference process. This work covers the two main aspects of the protocol reverse engineering, the inference of its syntactical definition and of its grammatical definition. We propose an open-source tool, called Netzob, that implements our work to help security experts in their work against latest cyber-threats. We claim Netzob is the most advanced published tool that tackles issues related to the reverse engineering and the simulation of undocumented protocols.
40

Dopad bezpečnosti IIoT na proaktivní údržbu firemních aktiv / Impact of IIoT security on proactive maintenance of company's assets

Chomyšyn, Maxim January 2020 (has links)
This work examines possible safety risks associated with the operation of IIoT technologies in industrial production. The content of this document is an analysis of used IIoT technologies, their purpose and method of implementation into production processes and the company's technology strategy. The outcome of this analysis will serve to develop possible risk scenarios and their associated impacts. Finally, I recommend possible changes that either eliminate these risks completely or at least minimize them.

Page generated in 0.1067 seconds