Дисертації з теми "REDD+ Scheme"

Vehicles will use pseudonyms instead of relying on long-term certificates to provide security and privacy. Pseudonyms are short-term public key certificates that do not contain identity-linking information about the vehicle. However, there is a constant risk that authorised vehicles may send fake messages or behave selfishly, and this can affect the performance of the Vehicular Ad hoc NETwork (VANET). In this context, trust management is another important component of security services in VANETs, which provides a unified system for establishing a relationship between the nodes and helps by keeping record of the behaviour of the vehicles. Nevertheless, it is a challenging task to monitor the evolving pattern of the vehicular behaviour, since communication between the vehicles is anonymous. It is not easy to find a balanced solution that meets the requirements of security, privacy, and trust management in VANET. In view of this, we put forward a Preserving-Privacy Reputation Scheme (PPRS) applied to VANETs, in which a reputation server through a Roadside Unit receives feedback about the behaviour of the vehicles. The server updates and certifies the reputation of the vehicles by matching their anonymous identities with their real ones. Our scheme introduces geographical areas of security, in which the security of an area can be adapted to higher or lower levels depending on the reputation of the vehicles. In addition, complex reputation is examined, in which the reputation of a vehicle is linked to several behavioural factors. A further key area that is explored is the performance evaluation of PPRS which is conducted through a set of simulations in a grid scenario, based on an opportunistic message forwarding application. The results showed the effectiveness of PPRS in terms of assessing the behaviour of the vehicles and taking measures against the misbehaving vehicles. We used SUMO to simulate the mobility model; OMNET++ and Veins supported the simulation of the network model. In addition, Crypto++ was used to implement the elliptical curve cryptographic functions of signature and verification of messages, as recommended by the security standards. Finally, we employ a pseudonym changing strategy in which the reputation is discretised at two levels of reputation. The strategy was implemented in a realistic traffic simulation scenario, and was compared with the so called status and synchronous strategies through a serie of simulations. The results showed that the number of pseudonyms used in our strategy is lower than the strategies mentioned above, and maintains the rate of success of changing pseudonym achieved by the synchronous strategy.
Os veículos usarão pseudônimos em vez de certificados de longo prazo para fornecer segurança e privacidade. Os pseudônimos são certificados de chaves públicas de curto prazo que não contêm informação da identidade do veículo. No entanto, existe risco que veículos autorizados possam enviar mensagens falsas ou se comportar de maneira egoísta, e isso pode afetar o desempenho das redes veiculares (VANETs). Nesse contexto, o gerenciamento de confiança é um importante serviço de segurança nas VANETs, o qual fornece um sistema unificado para estabelecer relações entre os nós e ajuda a manter um registro do comportamento dos veículos. No entanto, é uma tarefa desafiante monitorar o padrão evolutivo do comportamento veicular, já que a comunicação entre os veículos é anônima. Não é uma tarefa fácil encontrar uma solução equilibrada que atenda aos requisitos de segurança, privacidade e gerenciamento de confiança em VANET. Em vista disso, apresentamos um Esquema de Reputação Preservando a Privacidade (ERPP) aplicado a VANETs, no qual um servidor de reputação através de uma unidade de acostamento recebe avaliações sobre o comportamento dos veículos. O servidor atualiza e certifica a reputação dos veículos relacionando seus identidades anônimas com as reais. ERPP introduz áreas geográficas de segurança, na qual a segurança de uma área pode ser adaptada a níveis mais elevados ou mais baixos dependendo da reputação dos veículos. Além, uma reputação complexa é examinada, na qual a reputação de um veículo está vinculada a vários fatores do comportamento. Uma outra área que é explorada é a avaliação de desempenho do ERPP o qual é conduzida através de simulações em um cenário urbano, com base na aplicação de encaminhamento oportunista de mensagens. Os resultados mostraram a eficácia do ERPP em termos de avaliar o comportamento dos veículos e tomar medidas contra os veículos mal comportados. Utilizamos SUMO para simular o modelo de mobilidade; OMNET++ e Veins suportaram o modelo de red; and Crypto++ foi usado para implementar as funções criptográficas de curvas elípticas de assinatura e verificação de mensagens como recomendam os padrões de segurança. Finalmente, empregamos uma estratégia de mudança de pseudônimo na qual a reputação é discretizada em dois níveis de reputação. A estratégia foi implementada em um cenário de simulação de tráfego realista e foi comparada com as estratégias nomeadas de estado e síncrona mediante simulações. Os resultados mostraram que o número de pseudônimos utilizados em nossa estratégia é menor que os esquemas mencionados, e mantém a taxa de sucesso de mudança de pseudônimo alcançada pela estratégia síncrona.

Durante i prossimi anni, un gran numero di laboratori saranno impegnati in un programma di upgrade dei principali esperimenti al Large Hadron Collider (LHC), chiamato upgrade Fase-II. L’Istituto Nazionale di Fisica Nucleare (INFN) e il gruppo A Toroidal LHC Apparatus (ATLAS) di Bologna hanno sviluppato un prototipo di una nuova scheda chiamata PIxel detector high Luminosity UPgrade (PILUP), la quale é una possibile candidata per il rinnovamento del sistema Data AQuisition (DAQ) di ATLAS. Le principali caratteristiche di questa scheda sono il processore installato (dual-core ARM), la enorme larghezza di banda di comunicazione (fino a 60 Gbps tramite fibre ottiche) e la comunicazione con il PC tramite bus PCIe dedicato di seconda generazione. Durante il mio lavoro di tesi, ho disegnato e sviluppato un sistema di test pensato per valutare i componenti della scheda e una procedura di test automatizzata, controllata da remoto da un programma software, per valutare la qualitá delle connessioni veloci. I test dimostrano che la PiLUP soddisfa tutti i requisiti in termini di affidabilitá della trasmissione dati con alcune precisazioni. Sebbene la PiLUP é stata progettata per soddisfare un compito specifico, é altamente versatile e potrebbe adattarsi a diverse applicazioni: la piú importante é la capacitá di gestire la comunicazione con la scheda principale dell’upgrade DAQ di ATLAS, la Front-End LInk eXchange (FELIX), utilizzando diversi protocolli di comunicazione (GigaBit Transceiver e Full-Mode). Questo é stato il primo passo della collaborazione internazionale con il gruppo FELIX iniziato nel luglio 2017: i laboratori e gli istituti americani, olandesi, italiani, oltre al CERN, sono coinvolti in questa partnership, collaborando a soluzioni di nuove schede di lettura. Infine, un’altra applicazione della PiLUP é di utilizzarla come emulatore di diversi dispositivi, come il nuovo chip di lettura RD53A.

The aim of this research is to investigate the possible effects of text experiences on story retelling with young children. The subjects are 210 Lebanese children, whose native language is Arabic, learning to read in English through using foreign culture books, mainly American. It is the belief that, while learning to read in a second language, children are also introduced to a new culture. Therefore, a key question is how are we going to make this process easier and more enjoyable to children who are a) learning to read, b) in a foreign language, and c) about a distant culture. Based on previous work with schema theory, two story books are used in this study to detect any differences in comprehension levels between stories of varied cultural backgrounds. One story is based on the Spanish concept of bull-fighting which is assumed to be foreign to the children and the other is with a familiar Lebanese background. Subjects were divided into four groups: the first group worked with pictures and had a discussion prior to reading to build the target-culture schema; the second had the schema activities after reading the story; the third discussed the cultural topic both before and after reading; and the last was a control group which did not have schema activities. Results show that familiarity with a topic before reading the text promotes comprehension, retention, and retelling of a text. Proficiency in the foreign language seems to have a great effect on text understanding when information about the topic is made available. Implications are drawn and suggestions given for practical approaches to developing children's reading through tasks in Lebanese classrooms.

Doutoramento em Telecomunicações
Resumo em português não disponivel
The topic of this thesis is how to achieve e cient security against pollution attacks by exploiting the structure of network coding. There has recently been growing interest in using network coding techniques to increase the robustness and throughput of data networks, and reduce the delay in wireless networks, where a network coding-based scheme takes advantage of the additive nature of wireless signals by allowing two nodes to transmit simultaneously to the relay node. However, Network Coding (NC)-enabled wireless networks are susceptible to a severe security threat, known as data pollution attack, where a malicious node injects into the network polluted (i.e., corrupted) packets that prevent the destination nodes from decoding correctly. Due to recoding at the intermediate nodes, according to the core principle of NC, the polluted packets propagate quickly into other packets and corrupt bunches of legitimate packets leading to network resource waste. Hence, a lot of research e ort has been devoted to schemes against data pollution attacks. Homomorphic Message Authentication Code (MAC)-based schemes are a promising solution against data pollution attacks. However, most of them are susceptible to a new type of pollution attack, called tag pollution attack, where an adversary node randomly modi es tags appended to the end of the transmitted packets. Therefore, in this thesis, we rst propose a homomorphic message authentication code-based scheme, providing resistance against data pollution attacks and tag pollution attacks in XOR NC-enabled wireless networks. Moreover, we propose four homomorphic message authentication code-based schemes which provide resistance against data and tag pollution attacks in Random Linear Network Coding (RLNC). Our results show that our proposed schemes are more e cient compared to other competitive tag pollution immune schemes in terms of complexity, communication overhead and key storage overhead.

In this paper, we develop a scheme to recover a single erasure when using a Cartesian code,in the context of a distributed storage system. Particularly, we develop a scheme withconsiderations to minimize the associated bandwidth and maximize the associateddimension. The problem of recovering a missing node's data exactly in a distributedstorage system is known as theexact repair problem. Previous research has studied theexact repair problem for Reed-Solomon codes. We focus on Cartesian codes, and show wecan enact the recovery using a linear exact repair scheme framework, similar to the oneoutlined by Guruswami and Wooters in 2017.
Master of Science
Distributed storage systems are systems which store a single data file over multiple storage nodes. Each storage node has a certain storage efficiency, the "space" required to store the information on that node. The value of these systems, is their ability to safely store data for extended periods of time. We want to design distributed storage systems such that if one storage node fails, we can recover it from the data in the remaining nodes. Recovering a node from the data stored in the other nodes requires the nodes to communicate data with each other. Ideally, these systems are designed to minimize the bandwidth, the inter-nodal communication required to recover a lost node, as well as maximize the storage efficiency of each node. A great mathematical framework to build these distributed storage systems on is erasure codes. In this paper, we will specifically develop distributed storage systems that use Cartesian codes. We will show that in the right setting, these systems can have a very similar bandwidth to systems build from Reed-Solomon codes, without much loss in storage efficiency.

Optimising the throughput performance for wireless networks is one of the challenging tasks in the objectives of communication engineering, since wireless channels are prone to errors due to path losses, random noise, and fading phenomena. The transmission errors will be worse in a multihop scenario due to its accumulative effects. Network Coding (NC) is an elegant technique to improve the throughput performance of a communication network. There is the fact that the bit error rates over one modulation symbol of 16- and higher order- Quadrature Amplitude Modulation (QAM) scheme follow a certain pattern. The Scattered Random Network Coding (SRNC) system was proposed in the literature to exploit the error pattern of 16-QAM by using bit-scattering to improve the throughput of multihop network to which is being applied the Random Linear Network Coding (RLNC). This thesis aims to improve further the SRNC system by using Forward Error Correction (FEC) code; the proposed system is called Joint RLNC and FEC with interleaving. The first proposed system (System-I) uses Convolutional Code (CC) FEC. The performances analysis of System-I with various CC rates of 1/2, 1/3, 1/4, 1/6, and 1/8 was carried out using the developed simulation tools in MATLAB and compared to two benchmark systems: SRNC system (System-II) and RLNC system (System- III). The second proposed system (System-IV) uses Reed-Solomon (RS) FEC code. Performance evaluation of System IV was carried out and compared to three systems; System-I with 1/2 CC rate, System-II, and System-III. All simulations were carried out over three possible channel environments: 1) AWGN channel, 2) a Rayleigh fading channel, and 3) a Rician fading channel, where both fading channels are in series with the AWGN channel. The simulation results show that the proposed system improves the SRNC system. How much improvement gain can be achieved depends on the FEC type used and the channel environment.

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Schema Matching is the problem of finding semantic correspondences between elements from different schemas. This is a challenging problem, since the same concept is often represented by disparate elements in the schemas. The traditional instances of this problem involved a pair of schemas to be matched. However, recently there has been a increasing interest in matching several related schemas at once, a problem known as Schema Matching Networks, where the goal is to identify elements from several schemas that correspond to a single concept. We propose a family of methods for schema matching networks based on machine learning, which proved to be a competitive alternative for the traditional matching problem in several domains. To overcome the issue of requiring a large amount of training data, we also propose a bootstrapping procedure to automatically generate training data. In addition, we leverage constraints that arise in network scenarios to improve the quality of this data. We also propose a strategy for receiving user feedback to assert some of the matchings generated, and, relying on this feedback, improving the quality of the final result. Our experiments show that our methods can outperform baselines reaching F1-score up to 0.83.
Casamento de Esquemas é a tarefa de encontrar correpondências entre elementos de diferentes esquemas de bancos de dados. É um problema desafiador, uma vez que o mesmo conceito geralmente é representado de maneiras distintas nos esquemas.Tradicionalmente, a tarefa envolve um par de esquemas a serem mapeados. Entretanto, houve um crescimento na necessidade de mapear vários esquemas ao mesmo tempo, tarefa conhecida como Casamento de Esquemas em Rede, onde o objetivo é identificar elementos de vários esquemas que correspondem ao mesmo conceito. Este trabalho propõe uma famı́lia de métodos para o problema do casamento de esquemas em rede baseados em aprendizagem de máquina, que provou ser uma alternativa viável para o problema do casamento tradicional em diversos domı́nios. Para superar obstáculo de obter bastantes instâncias de treino, também é proposta uma técnica de bootstrapping para gerar treino automático. Além disso, o trabalho considera restrições de integridade que ajudam a nortear o processo de casamento em rede. Este trabalho também propõe uma estratégia para receber avaliações do usuário, com o propósito de melhorar o resultado final. Experimentos mostram que o método proposto supera outros métodos comparados alcançando valor F1 até 0.83 e sem utilizar muitas avaliações do usuário.

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CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
A necessidade de velocidades de conexão a internet cada vez maiores motivou a criação de um novo padrão, G.fast, para DSL (linha digital do assinante), de modo a prover performance semelhante a fibra usando par trançado de fios de cobre. Esta dissertação foca em dois prévios candidatos a esquemas de correção de erro, sendo eles codigos Reed-Solomon com modulaçao codificada em treliça (TCM), de padrões DSL anteriores, e códigos de verificação de paridade de baixa densidade (LDPC), do padrão G.hn para redes residenciais. O objetivo principal é comparar os dois esquemas, de modo a avaliar qual deles tem melhor performance, considerando métricas como poder de correção de erro e custo computacional. Embora o código selecionado para o G.fast já tenha sido RS+TCM, acredita-se que esta decisão foi tendenciosa, já que é sabido que códigos mais recentes como LDPC possuem maior poder correção.
The need for increasing internet connection speeds motivated the creation of a new standard, G.fast, for digital subscriber lines (DSL), in order to provide fiber-like performance using short twisted pair copper wires. This dissertation focuses in the two former candidate codes for the forward error correction (FEC) scheme, namely Reed-Solomon (RS) with trellis-coded modulation (TCM), from previous DSL standards, and low density parity check (LDPC) codes, from the G.hn standard for home networking. The main objective is to compare both schemes, in order to evaluate which of them performs better, considering metrics such as error correction performance and computational cost. Even though the selected code for G.fast was RS with TCM, it is believed that this choice was biased, as a more recent iterative code like LDPC is known to have a better error correction performance.

Proefschrift--Sociale wetenschappen--Utrecht--Rijksuniversiteit, 1985.
Mention parallèle de titre ou de responsabilité : Lösung aus dem Bann der Vernunft : eine Konfrontation zwischen der kultur- und wissenssoziologischen Auffassung von Max Scheler und Max Weber. Résumé en allemand. Bibliogr. p. 376-394. Index.

En aquesta tesi proposem dos esquemes de xarxa amb control d'admissió per al trànsit elàstic TCP amb mecanismes senzills. Ambdós esquemes són capaços de proporcionar throughputs diferents i aïllament entre fluxos, on un "flux" es defineix com una seqüència de paquets relacionats dins d'una connexió TCP. Quant a l'arquitectura, ambdós fan servir classes de paquets amb diferents prioritats de descart, i un control d'admissió implícit, edge-to-edge i basat en mesures. En el primer esquema, les mesures són per flux, mentre que en el segon, les mesures són per agregat. El primer esquema aconsegueix un bon rendiment fent servir una modificació especial de les fonts TCP, mentre que el segon aconsegueix un bon rendiment amb fonts TCP estàndard. Ambdós esquemes han estat avaluats satisfactòriament a través de simulació en diferents topologies de xarxa i càrregues de trànsit.
In this thesis we propose two network schemes with admission control for TCP elastic traffic using simple mechanisms. Both schemes are able to provide different throughputs and isolation between flows, where a flow is defined as a sequence of related packets within a TCP connection. Regarding to the architecture, both use packet classes with different discarding priorities and an admission control that is implicit, edge-to-edge and based on measurements. In the first scheme, measurements are per-flow, while in the second one, measurements are per-aggregate. The first scheme achieves a good performance using a special modification of TCP sources, while the second scheme achieves a good performance with standard TCP sources. Both schemes have been evauated succesfully through simulation in different network topologies and traffic loads.

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The heavy metals are used in many industrial processes and when discharged to the environment can cause harmful effects to human, plants and animals. The adsorption technology has been used as an effective methodology to remove metallic ions. The search for new adsorbents motivated the development of this research, accomplished with the purpose of removing Cr (III) from aqueous solutions. Diatomite, chitosan, Filtrol 24TM and active carbon were used as adsorbents. To modify the adsorbent surface was used a bicontinuous microemulsion composed by water (25%), kerosene (25%), saponified coconut oil (10%) and as co-surfactant isoamyl or butyl alcohols (40%). With the objective of developing the best operational conditions the research started with the surfactant synthesis and after that the pseudo-ternary diagrams were plotted. It was decided to use the system composed with isoamyl alcohol as co-surfactant due its smallest solubility in water. The methodology to impregnate the microemulsion on the adsorbents was developed and to prepare each sample was used 10 g of adsorbent and 20 mL of microemulsion. The effect of drying time and temperature was evaluated and the best results were obtained with T = 65 ?C and t = 48 h. After evaluating the efficiency of the tested adsorbents it was decided to use chitosan and diatomite. The influence of the agitation speed, granule size, heavy metal synthetic solution concentration, pH, contact time between adsorbent and metal solution, presence or not of NaCl and others metallic ions in the solution (copper and nickel) were evaluated. The adsorption isotherms were obtained and Freundlich and Langmuir models were tested. The last one correlated better the data. With the purpose to evaluate if using a surfactant solution would supply similar results, the adsorbent surface was modified with this solution. It was verified that the adsorbent impregnated with a microemulsion was more effective than the one with a surfactant solution, showing that the organic phase (kerosene) was important in the heavy metal removal process. It was studied the desorption process and verified that the concentrated minerals acids removed the chromium from the adsorbent surface better than others tested solutions. The treatment showed to be effective, being obtained an increase of approximately 10% in the chitosan s adsorption capacity (132 mg of Cr3+ / g adsorbent), that was already quite efficient, and for diatomite, that was not capable to remove the metal without the microemulsion treatment, it was obtained a capacity of 10 mg of Cr3+ / g adsorbent, checking the applied treatment effectiveness
Os metais pesados s?o utilizados em muitos processos industriais e, quando descartados ao meio ambiente, podem ocasionar efeitos prejudiciais aos seres vivos. O processo de adsor??o vem sendo utilizado como metodologia eficaz para a remo??o de ?ons met?licos. A busca por novos adsorventes motivou o desenvolvimento deste trabalho, realizado com o objetivo de remover Cr (III) de solu??es aquosas. Utilizou-se como adsorventes: diatomita, quitosana, Filtrol 24TM e carv?o ativo. Empregou-se como agente modificador dos adsorventes uma microemuls?o bicont?nua composta de ?gua (25 %), querosene (25 %), ?leo de coco saponificado (10 %) e cotensoativo (?lcool isoam?lico ou but?lico, 40 %). Com o objetivo de obter as melhores condi??es operacionais partiu-se da obten??o do tensoativo e obteve-se os diagramas pseudotern?rios. Resolveu-se empregar o sistema contendo o ?lcool isoam?lico devido sua menor solubilidade em ?gua. Desenvolveu-se a t?cnica de impregna??o da microemuls?o sobre os adsorventes e, para o preparo de cada amostra, empregou-se 10 g de adsorvente e 20 mL de microemuls?o. Avaliou-se o efeito do tempo de secagem e da temperatura, obtendo-se os melhores resultados com T = 65 ?C e t = 48 h. Ap?s avaliar a efici?ncia dos adsorventes testados resolveu-se utilizar a quitosana e a diatomita e avaliou-se a influ?ncia da velocidade de agita??o, granulometria, concentra??o, pH, presen?a de outros c?tions met?licos (cobre e n?quel) e NaCl na solu??o e o tempo de contato do adsorvente com a solu??o de metal. Obteve-se as isotermas de adsor??o e testou-se os modelos de Freundlich e Langmuir, que correlacionou melhor os dados. Com o prop?sito de verificar se o emprego de uma solu??o de tensoativo forneceria resultados semelhantes, tratou-se o adsorvente com esta solu??o e verificou-se que o adsorvente impregnado com a microemuls?o foi mais efetivo, comprovando que a fase org?nica (querosene) era importante para o processo. Estudou-se o processo de dessor??o e verificou-se que os ?cidos minerais concentrados eluiam melhor o cromo. O tratamento mostrou-se eficaz obtendo-se um aumento na capacidade de adsor??o de cromo de aproximadamente 10 % para a quitosana (132 mg de Cr3+/ g adsorvente), que j? era bastante eficiente, e, para a diatomita, que n?o era capaz de remover o metal, obteve-se uma capacidade de 10 mg de Cr3+/g adsorvente, comprovando a efic?cia do tratamento aplicado

The aim of this study was to investigate the communicative orientation of classroom interaction in Japanese language lessons that are conducted in the virtual environment of synchronous (real-time) telematics. Specifically, the study examined Japanese telematics classrooms in upper primary and junior secondary schools in Western Australia. This study focused on whether the interaction in the classes studied, evident in the virtual learning mode of telematics was facilitative of second language (L2) acquisition. The form of telematics used in this study was synchronous communication between teacher and students using telephone and computer links, sometimes also referred to as "audiographics". Telematics may also include the use of other communication technologies, such as live interactive television (LIT) however this was not available to all sites in the current study so it was not investigated. The aim of this study is articulated through the research questions: 1. What is the nature of the communicative orientation in upper primary and junior secondary Japanese language classrooms in telematics mode? 2. ls the interaction observed in Japanese language telematics classrooms of the type that promotes L2 acquisition? The first question seeks to identify the relative emphasis placed on interaction and form-focused interaction in the telematics classroom context. The second question identifies whether the features of interaction that SLA researchers suggest promote L2 acquisition are evident in the telematics context. This study uses the term interaction to refer to the type of human-human communicative interaction occurring in L2 telematics classes via the computer/technology that is facilitated by a number of key communicative features of interaction drawn from the second language acquisition (SLA) research. Interactivity on the other hand is used to refer to the human-computer engagement which is technologically facilitated. Subjects in the study were three telematics teachers, with distributed classes across several student receival sites. The study examined descriptive process data collected from Japanese telematics classes in Western Australia via audio and video recordings. The study engaged in a descriptive inquiry using Classroom-Centred Research (CCR) methodology. CCR as a methodology provides evidence about the nature and influence of language instruction and classroom interaction have on L2 acquisition. This study used multi-methods of data collection via four stages: teacher questionnaire, classroom observations of interactions, teacher focus group discussion and follow-up interviews conducted later in the study to confirm the findings. The major analytical tool used was the current version of the Communicative Orientation of Language Teaching (COLT) Observation (1995). The use of this scheme stems from its ability to bring together all of the communicative variables to capture features deemed theoretically and empirically relevant to the L2 classroom. The COLT Observation Scheme also provides a framework for comparing features of discourse in classrooms with features of natural language acquisition considered to be facilitative of L2 acquisition. In this way the extent to which an instructional treatment may be characterised as communicatively orientated can be measured. Both Part A and Part B of the scheme were used. The features and categories in Part A are primarily derived from pedagogical issues identified in the literature on communicative language teaching (CL T). Features and categories in Part B reflect issues in first and second language acquisition. The only modification was an additional investigation of how form was used in the telematics lessons. Although recent studies have recommended improvements to telematics delivery, no other known study has specifically investigated whether the interaction evident in the delivery of Japanese via telematics is of the type that promotes successful L2 acquisition. Through the use of the COLT Observation Scheme, this study was able to capture and measure features of L2 classroom interaction in these telematics environments. The results indicate that there were a number of internal and external variables that influenced the nature of the communicative orientation of telematics classes in this study. In terms of the communicative features of interaction identified in the COLT Observation Scheme as predictors of successful L2 acquisition, a number of these were not strongly evident in the results, for example, use of the target language, interaction in group work, use of extended text, use of authentic resources and student-made materials, reaction to message and clarification request. Pedagogic factors impinging on the communicative orientation of the telematics environment included the highly teacher-centred nature of the telematics context. The use of the computer as a controlling device and the only visual connection also moved teachers further towards a more directive delivery style and greater dependence on using the L 1. Given the recent support for the incorporation of some focus on form into a communicative curriculum, the supplementary focus on form data revealed how the electronic nature of telematics delivery influenced how form was taught and the overuse in some cases of vocabulary games, drilling, substitution and repetition. There was also little evidence of students initiating discourse, negotiating activities or requesting clarification. Students engaged in mainly minimal rather than extended text thus limiting opportunities to experiment with the L2. The communicative orientation of L2 telematics classes in this study was also impacted upon by a number of external factors, such as noise, technical breakdowns and inadequate learning environments at receival sites. The impact of the absence of a two-way human visual connection led to teachers using a more directive style of teaching where "silences" were often filled with teacher talk. Teachers identified this limitation as also limiting opportunities for students to obtain comprehensible input. However, teachers developed useful compensation strategies to overcome some of these limitations such as, using colour on the computer screen and tone of voice to highlight salient features. They also introduced games that promoted interaction between sites. Whilst this study has revealed that some of the communicative features of interaction are evident, a greater number of these features need to become more prominent or more communicative. As well as targeting the technological orientation of the delivery method by adding a human visual connection, this would also involve the careful incorporation of the features that are characteristic of a more communicative approach to L2 acquisition. This study has contributed to the fields of SLA and virtual delivery in a number of ways. It has added to the existing literature base through interfacing the SLA literature with the telematics literature. It has also contributed to a new methodology by taking an existing methodology and methods and applying them to the virtual L2 telematics classroom, in particular, the use of the COLT Observation Scheme in a virtual context. A contribution this study has made to language teaching through telematics lies in a mapping framework that has evolved from the study that aims to bring the type of interaction that occurs in SLA, communicative interaction and telematics closer together. Further research needs to determine how interaction can be more effectively promoted m the telematics and virtual learning environments. It is anticipated that this study will encourage other researchers to further investigate the benefits of a more communicatively orientated intervention which will ultimately lead to positive L2 learning outcomes for all students in telematics environments and the broader virtual learning contexts.

One essential component of global efforts on climate change mitigation is the incentive-based mechanism that seeks to Reduce Emissions from Deforestation and Forest Degradation and also enhances forest carbon stocks through sustainable forest management in developing countries (the REDD+ scheme). There are other potential co-benefits associated with the REDD+ scheme which include biodiversity conservation, poverty alleviation and enhancement of rural livelihoods. A clear challenge for the REDD+ scheme is that if its implementation should be deemed as successful, the various drivers of deforestation should be addressed whereas the rights of local or forest fringe communities to forest resources should concurrently not be compromised. This research uses Ghana as a case to explore the implications of the introduction of the REDD+ scheme for forest fringe communities. The study employs land tenure and benefit sharing issues as the conceptual framework to answer the research question: ‘How should a national REDD+ scheme for Ghana be designed to maximise benefits to forest fringe communities?’ The study is based on a review of relevant literature including government documents and academic literature as well as interviews with ten key informants from the REDD+ Steering Committee of Ghana, NGOs, land administrators, academia and the forest fringe communities. The findings of the research indicate that Ghana’s land tenure arrangement is pluralistic and unclear involving both customary and statutory arrangements. Additionally, statutory provisions for sharing of benefits from forest resources in Ghana generally exclude forest fringe communities. Consequently, the rights of forest fringe communities in Ghana have not been fully recognised in the management of forest resources. However, under the REDD+ scheme preparatory process, Ghana has engaged forest fringe communities as key stakeholders for the scheme in general and for specific components such as the development of a benefit sharing framework for the scheme. This paper suggests that the participatory approach adopted in the REDD+ readiness phase of Ghana could build genuine support from forest fringe communities if there is strong political will to initiate reforms in the forestry sector that will legally recognise the rights of forest fringe communities and thereby make these communities shareholders of the scheme.

碩士
國立東華大學
資訊工程學系
93
Recently, Denial of Service attack (DOS) and Distributed Denial of Service attack (DDOS) have drawn many attentions from human. Attackers send a huge number of attack packets with spoofed source address to the victim and consume its resources to let it work incompetently. Besides, the attackers usually use the spoofed IP source address to disguise their position. Therefore, it is difficult to trace the source of the attacks and make the attackers to be responsible for their behaviors. For this situation, several techniques about determination of IP have been developed recently. One of these based on probabilistic samples of transited packets is Probabilistic Packet Marking (PPM) proposed by Stefan Savage. PPM has three major advantages: it does not need additional packets to deliver marked information; the marked procedure in the routers is fast; it is compatibility with the present network. However, this approach needs many marked packets to reconstruct the attack path and needs many times of reconstructing the correct marked packet. The PPM uses the identification field in the IP header to store the address information which makes the minimal effects for the present network. Besides, in order to put the address information into the limited space, PPM divides each address information into eight fragments and deliver them separately. Therefore, the victim can use the hash function to check the correctness of the reconstructing address information. This reconstructing procedure needs many marked packets that may costs much. In this paper, we present a new scheme, Reed-Solomon Code Marking Scheme. It is an enhancement of PPM and can traceback the origin of spoofed IP packets. In the reconstructing procedure of PPM, the incorrect combinations of the marked information are always dropped. Therefore, we apply the error-correcting code to improve the PPM. The RS code is non-binary BCH code with error-correcting ability. Hence, we can correct the errors of the fragments. Here in, we apply a suitable RS code to improve the PPM. Therefore, our scheme can use fewer marked packets to reconstruct the attack path and less time to reconstruct correct packets.

碩士
國立臺灣科技大學
資訊工程系
101
The access speed of flash-based storage devices is much faster than traditional hard disk (especially random reads), the SSD, which composed by NAND flash, is more popular in the few years. In the SSD, FTL(Flash Translation Layer)plays a key role for performance, which is mainly responsible for (1)Translate the logical address to the physical address, (2)Garbage collection, and based on the characteristics of the FLASH,it's also need to maintain (3)Wear-leveling, to extend the lifetime of the SSD. This paper focus on Improvement of access speed(more accurate, read speed). Most of related researchers analyze the write mechanism, modify it to decrease the response time, and use cache memory to service read requests. But in our idea, some workloads' pattern show different characteristics for read. Some data is often read and rarely updated. In the overall, number of reads is much larger than writes. Besides, the design of some FTL and not adding parallel processing considerations, and most of the SSD using multi-channel architecture and support some advanced commands now. By adding the considerations, we can more improve the performance. This paper uses the common multi-channel architecture for the target hardware, and considers the concept of parallel and advanced commands. Without increasing too much overhead to modify the the existing FTL mechanism to enhance the performance of read-domain workloads.

Semiconductor technology scaling resulted in a considerable reduction in the transistor cost and an astonishing enhancement in the performance of VLSI (very large scale integration) systems. These nanoscale technologies have facilitated integration of large SRAMs which are now very popular for both processors and system-on-chip (SOC) designs. The density of SRAM array had a quadratic increase with each generation of CMOS technology. However, these nanoscale technologies unveiled few significant challenges to the design of high performance and low power embedded memories. First, process variation has become more significant in these technologies which threaten reliability of sensing circuitry. In order to alleviate this problem, we need to have larger signal swings on the bitlines (BLs) which degrade speed as well as power dissipation. The second challenge is due to the variation in the cell current which will reduce the worst case cell current. Since this cell current is responsible for discharging BLs, this problem will translate to longer activation time for the wordlines (WLs). The longer the WL pulse width is, the more likely is the cell to be unstable. A long WL pulse width can also degrade noise margin. Furthermore, as a result of continuous increase in the size of SRAMs, the BL capacitance has increased significantly which will deteriorate speed as well as power dissipation. The aforementioned problems require additional techniques and treatment such as read-assist techniques to insure fast, low power and reliable read operation in nanoscaled SRAMs. In this research we address these concerns and propose a read-assist sense amplifier (SA) in 65nm CMOS technology that expedites the process of developing differential voltage to be sensed by sense amplifier while reducing voltage swing on the BLs which will result in increased sensing speed, lower power and shorter WL activation time. A complete comparison is made between the proposed scheme, conventional SA and a state of the art design which shows speed improvement and power reduction of 56.1% and 25.9%, respectively over the conventional scheme at the expense of negligible area overhead. Also, the proposed scheme enables us to reduce cell VDD for having the same sensing speed which results in considerable reduction in leakage power dissipation.

碩士
國立交通大學
資訊工程系
90
The Random Early Detection (RED) mechanism is a well-known active queue management mechanism that was related to congestion control. And the RED mechanism has been recommended to be deployed in the Internet router. However, the RED mechanism cannot protect well-behaved flows (i.e. TCP-compatible flows) against the high-bandwidth misbehaving flows, these include flows that do not use congestion avoidance mechanism and flows with poorly implemented TCP protocol, during periods of congestion. We proposed a new mechanism to improve RED’s functionality to deal with the high-bandwidth misbehaving flows. The simulation results show that our proposed mechanism can successfully identify and penalize the high-bandwidth misbehaving flows. Besides, from those simulation results, we could find that our proposed mechanism can achieve approximate fairness among all competing flows.

碩士
國立臺灣科技大學
電子工程系
100
Fountain codes have been widely discussed recently. The main characteristic is that the number of encoded packets is not fixed before the transmission. LT code is the first practical type of fountain code; it can achieve great performance and reach low coding and encoding complexities. Since LT codes act well on erasure channel, one might consider whether it can be applied on noisy channel. Because the inter-symbol interference (ISI), the packets may be contaminated. The detrimental effect of error propagation in LT hard decoding may occur. Belief propagation algorithm is a solution to avoid situation like this. However, the simulation results of the bit error rate turn out to be quite high. We need to come up with some method to improve the performance. In this thesis, we create a new type of codes called "Hybrid Fountain Codes" by combining Reed-Solomon codes and LT codes. Under Reed-Solomon codes' correcting ability, errors can be corrected easily and Tanner graph can be updated. By passing information, renewing Tanner graph and removing connections, complexities can be reduced dramatically. The calculation of LLR is an important issue. We have to extract LLR value of both source packets and encoded packets so hard decision can be made. The combination of both hard and soft decision value is also important. Sometimes we have to combine encoded packets' soft decision with source packets' hard decision and vice versa. In this thesis, we derive unified computations for combining hard and soft decisions at the source nodes and encoded nodes. Sometimes the LLR value may be too large to deal with, so the approximate formula is also derived. The main advantage of this scheme is that the bit error rate can approach zero and total iteration times can be lower as compared to LT soft decoding only.

碩士
國立臺灣科技大學
電子工程系
100
The WiMAX network provides high speed internet multimedia service and supports a variety of types of Qos.Thus, it is important to allocate bandwidth to different class of traffic effectively in this network. The resource must be allocated effectively to guarantee the delay of real-time traffic. An algorithm named Enhance RED-based Scheduling is proposed in this paper to improve the performance of RED-based Scheduling algorithm. In RED-based Scheduling algorithm, the packet number of each queue is found to decide the scheduled bandwidth. In this way, a queue with smaller packets tends to have larger scheduled bandwidth than it needs. It is only applicable to queues with the same packet size. Also, when the number of packets exceeds the second threshold, the deficit counter (DC) is fixed in RED-based Scheduling algorithm. Then, the connection with heavier load will have larger delay time than that with smaller load although they may be the same class. Thus, we byte length of each queue is used to decide the DC value in this paper. Also, the DC will depend on the length of queue if one queue exceeds the second threshold.

碩士
國立雲林科技大學
電機工程系碩士班
92
Design and analysis of read/write scheme for magnetic random access memory (MRAM) are the main subjects in this study. MRAM are a high speed、high density、low voltage and nonvolatile memories, it will become a future mainstream memory technology. Read/write scheme for MRAM has tow structures: the 1T1MTJ structure and the XPC structure. The former memory cells include a bit line, a write word line, a read word line, a magnetic tunnel junction(MTJ) and a transistor; this structure is complicate but read and write are simple. The latter memory cells consist of only a bit line, a word line and a MTJ. It’s simple; however, it’s difficult to read and write. In this paper, read/write scheme designed with TSMC 0.18μm CMOS SP5M technology and resistance values of the MTJs are 10kΩ and 15kΩ (the MR ratio is 50%).

博士
國立臺北科技大學
電機工程系研究所
98
In this paper , a matrix-analytic approach is applied to analyse both the long-term and short term drop behavior of a router with a Random-Early-Detection scheme .The bursty natural of packet drop is examined by means of conditional statistics with respected to alternating congested and non-congested periods. All of the four related performance measures are derived by conditional statistics, including the long-term drop probability and the three short-term measures comprising average length of a congested period, average length of a non-congested period, and the conditional packet drop probability during a congested period. In discrete-time system, the packets arrival traffic is modeled by discrete-time batch Markovian process（D-BMAP）. We constructed a D-MAP/M/1/K queuing model. In continuous-time system,A matrix-analytic approach is applied to explore the per-stream loss behavior of the multimedia traffic under RED scheme. And constructed aΣMAP/M/1/K queuing model for the RED mechanism with multimedia traffic which follows a continuous-time Markovian arrival process (MAP). These performance measures describe the quality of service provided by the router to particular multimedia traffic streams in presence of background multimedia traffic.

碩士
臺灣大學
音樂學研究所
98
The model Beijing opera during the Cultural Revuotioin can be regarded as an elaborate means of establishing a personality cult through artistic performances. The lead character in such operas serves not only as a mouthpiece for political ideals, but also glorifies the communist party and Chairman Mao through a quasi-“shamanism” process. Based on relevant theories and analyses of audio-visual material, this thesis explores the political use of music in model Beijing operas. In light of myth theories, it is found that the shamanism position of the lead character can be established in a given text. Music analysis of several lead’s lyrical arias suggests that musical schema shifts can reinforce its shamanism element, and the hypothesis of the existence of a “mystical experience” in these arias is further examined through experiments. In light of schema shift, this study also investigates the evolution and changes in seven model Beijing operas, arguing that a “singing school” of Beijing opera served to break through inflexible modes.

This project examines a new and growing form of international development fundraising, which constructs and packages development as a product of consumption in order to achieve its goals of awareness and fundraising. These efforts involve the use of a new set of marketing tools, technologies, languages, and tactics to encourage the sale of the development cause. The commodification of development activities within fundraising efforts ultimately poses an important quandary in terms of the effects that such ventures have upon public engagement and reception of international development. As such, this thesis explores the implications of such efforts for social justice in terms of the ways in which people’s perceptions of their own involvement and the causes of which they are a part are shifted. In order to more closely analyze such activities, the organizations (RED) and Kiva were chosen to act as case studies of both corporate and non-for-profit endeavours.

碩士
國立臺灣大學
電子工程學研究所
103
In this thesis, a 400mV 4.76pJ/Access 11.6MHz 1Kb SRAM is implemented in TSMC 90nm 1P9M CMOS process. Due to single-ended access, the proposed 7T SRAM cell consumes less power compared to the traditional 6T SRAM cell. With the feedback-loop-cutting scheme and the read-separated scheme, the proposed 7T SRAM cell possesses better write margin (WM) and read static noise margin (RSNM). To achieve PVT variation tolerance, the write and read detecting scheme is implemented by the single row repeat (SRR) circuit and the single column repeat (SCR) circuit without compromising the total power consumption. Measurement results of a test chip show that the proposed SRAM system consumes low energy from 1.0V to 0.4V, and agree with the post-simulation results. Finally, these schemes achieve the stable and low-energy consumption SRAM, which can be used in energy-constraint applications.

Investment managers are entrusted with clients assets and should act with due care and diligence when dealing with it. The regulation of investment managers does not preclude the possibility that they can defraud their clients. The question posed by this research is whether the regulator can as part of its risk-based supervision methodology apply a fraud auditing approach to identify possible investment fraud schemes. The regulatory mandate and powers to pro-actively detect fraud is considered as well as the changes required to the regulator’s methodologies.
Dissertation (MPhil)--University of Pretoria, 2011.
Accounting
unrestricted

No
Errors in the interpretation of diagnostic images in the emergency department are a persistent problem internationally. To address this issue, a number of risk reduction strategies have been suggested but only radiographer abnormality detection schemes (RADS) have been widely implemented in the UK. This study considers the variation in RADS operation and communication in light of technological advances and changes in service operation. A postal survey of all NHS hospitals operating either an Emergency Department or Minor Injury Unit and a diagnostic imaging (radiology) department (n = 510) was undertaken between July and August 2011. The questionnaire was designed to elicit information on emergency service provision and details of RADS. 325 questionnaires were returned (n = 325/510; 63.7%). The majority of sites (n = 288/325; 88.6%) operated a RADS with the majority (n = 227/288; 78.8%) employing a visual ‘flagging’ system as the only method of communication although symbols used were inconsistent and contradictory across sites. 61 sites communicated radiographer findings through a written proforma (paper or electronic) but this was run in conjunction with a flagging system at 50 sites. The majority of sites did not have guidance on the scope or operation of the ‘flagging’ or written communication system in use. RADS is an established clinical intervention to reduce errors in diagnostic image interpretation within the emergency setting. The lack of standardisation in communication processes and practices alongside the rapid adoption of technology has increased the potential for error and miscommunication.