Manufacturers of feedwater heaters (FWHs) are obliged to disclose a specification sheet to the client that describes their FWH design. However, the client is unable to verify the performance of this FWH design without comparing it to the results that are predicted by a thermal model. An additional limitation is that the manufacturer will only disclose the minimum number of design parameters. The purpose of this study was to develop a thermal model that can predict the performance of a FWH. The model requires the minimum design input data to predict the performance parameters that may be compared to values predicted by the vendor. A FWH in a regenerative water-steam Rankine cycle achieves heat transfer to the feedwater by condensing steam on the shell side. This is called a single zone FWH. The tube plate type FWH is the most common type of FWH referenced in literature but the following variations may exist: • The Eskom fleet consist of both tube plate and header type FWHs. • FWHs may be orientated vertically or horizontally. Internal shrouded regions, that define it as a 2 or 3 zone FWH, may be present in the FWH. The length of the drains cooler (DC) zone may either be identified as long or short. A general model was required to capture all these design variations. Plant visits were arranged with engineers at several power stations to obtain the minimum input data and to confirm that these FWH design variations existed within the Eskom fleet. The model was based on existing tube plate models found in literature. It was then extended to accommodate the FWH variations mentioned above. A further improvement was made by including an additional heat transfer sub-zone that removes excess superheat in the condensing (COND) zone. The vendor does not disclose the correlations used to predict the film heat transfer coefficients (h) in their design. Therefore, the user is granted the option of selecting a correlation from a list of popular correlations, specific to a heat transfer mode. Note that the uncertainty associated with this thermal model is affected by the uncertainty of each correlation selected in the model.

Most network devices need to obtain specific packet header fields belonging to different network protocol headers for correct functionality. This work aims to create an efficient unit capable of application-specific packet header analysis and data extraction. The proposed unit deals with protocols used on L2, L3, and L4 layers of ISO/OSI model including tunneled protocols; it is possible to specify protocols which are to be supported. Data analysis is based on right linear grammar transformed to finite automaton. Hardware acceleration has to be exploited in order to achieve data processing of all traffic exchanged over high-speed networks. Using FPGA technology it is possible to achieve both fast and configurable data processing. The designed unit is able to process data on up to 40 Gbps networks. On-the-fly configuration of extracted header fields is supported.

No description available.

Inlet headers in the primary heat transport system(PHTS) of CANDU type reactors, are used to collect the coolant coming from the steam generators and distribute them into the reactor core via several feeders. During a postulated loss of coolant accident (LOCA), depressurization and vapor supplement into the core may occur, which results a deterioration in the heat transfer from fuel to the coolant. When a depressurization occurs, &ldquo / Emergency Coolant Injection(ECI)&rdquo / system in the PHTS in CANDU reactors, is automatically become active and supply coolant is fed into the reactor core via the inlet header and feeders. . This study is focused on the experimental and computational investigation of the ECI effect during a LOCA in a CANDU inlet header. The experiments were carried out in METU Two-Phase Flow Test Facility which consists of a scaled CANDU inlet header having 5 connected feeders. The same tests were simulated with a one dimensional two-fluid computer code, CATHENA, developed by Atomic Energy of Canada Limited(AECL). The average void fraction and the two phase mass flowrate data measured in the experiments are compared with the results obtained from CATHENA simulation. Although a few mismatched points exist, the results coming from two different studies are mostly matching reasonably. Lack of three-dimensional modeling for headers in CATHENA and experimental errors are thought to be the reasons for these dismatches.

Wireless broadband technologies provide ubiquitous broadband access to wireless users, enabling services that were available only to wireline users. At the same time, with the steady growth of real-time streaming applications such as video on demand (VoD), voice over IP (VoIP), massive online gaming, and so forth, the IEEE 802.16 standard (commonly known as WiMAX) has emerged as one of the strongest contenders to provide such kind of broadband wireless access services. WiMAX has specified some advanced lard features at physical (PHY) layer techniques and media access control (MAC) layer protocols, which adopted many Quality of Service (QoS) scheduling algorithms, resource allocation, Hybrid ARQ and so on. Moreover, forward error correction (FEC) and automatic repeat request (ARQ) techniques have already specified in the standard and they are used to support real-time streaming services in all kind of channel conditions. Inside this thesis, we propose an efficient fast feedback algorithm and buffer congestion control improvement scheme for data streaming over WiMAX networks. Two reserved bits in Generic MAC header (GMH) of each MPDU in WiMAX systems are utilized. The first reserved bit is used as a trigger in fast feedback strategy to add more robust coding and choose better feedback channel when the feedback message does not arrive properly within its cycle time trip (CTT) or after timeout. The second reserved bit is used to inform the base station about the serving subscriber stations¡¦ buffers states when their buffers are above the predefine-threshold value. Increasing number of retrieval of the feedback message, which means we can increase restore-bit-error probabilities within each frame, and then the throughput performance shall increase as well. In addition, by having each subscriber stations or service station¡¦s buffer states knowledge, the BS will be able to provide extra bandwidth allocation to the SSs more efficiency and accuracy. Keywords: WiMAX, PHY, MAC, Hybrid ARQ, QoS, Generic MAC header, CTT, Fast Feedback, Buffer Congestion Control Improvement, Real-Time streaming.

A unique all-optical 1x2 self-routed switch is introduced. This switch routes an optical packet from one input to one of two possible outputs. The header and payload are transmitted separately in the system, and the header bits are processed in parallel thus increasing the switching speed as well as reducing the amount of buffering required for the payload. A 1x2 switching operation is analysed and a switching ratio of up to 14dB is obtained. The objective of the research was to investigate a unique all-optical switch. The switch works by processing the optical bits in a header packet which contains the destination address for a payload packet. After the destination address is processed the optical payload packet gets switched to one of two outputs depending on the result of the optical header processing. All-optical packet switching in the optical time domain was accomplished by making use of all-optical parallel processing of an optical packet header. This was demonstrated in experiments in which a three bit parallel processing all-optical switching node was designed, simulated and used to successfully demonstrate the concept. The measure of success that was used in the simulated experiments was the output switching ratio, which is the ratio between the peak optical power of a high bit at the first output and the peak optical power of a high bit at the second output. In all experimental results the worst case scenario was looked at, which means that if there was any discrepancy in the peak value of the output power then the measurement’s minimum/maximum value was used that resulted in a minimum value for the switching ratio. The research resulted in an optical processing technique which took an optical bit sequence and delivered a single output result which was then used to switch an optical payload packet. The packet switch node had two optical fibre inputs and two optical fibre outputs. The one input fibre carried the header packet and the other input fibre carried the payload packet. The aim was to switch the payload packet to one of the two output fibres depending on the bit sequence within the header packet. Also only one unique address (header bit sequence) caused the payload packet to exit via one of the outputs and all the other possible addresses caused the payload packet to exit via the other output. The physical configuration of the all-optical switches in the parallel processing structure of the switching node determined for which unique address the payload packet would exit via a different output than when the address was any of the other possible combinations of sequences. Only three Gaussian shaped bits were used in the header packet at a data rate of 10 Gbps and three Gaussian shaped bits in the payload packet at a data rate of 40 Gbps, but in theory more bits can be used in the payload packet at a decreased bit length to increase throughput. More bits can also be used in the header packet to increase the number of addresses that can be reached. In the simulated experiments it was found that the payload packet would under most circumstances exit both outputs, and at one output it would be much larger than at the other output (where it was normally found to be suppressed when compared to the other output’s optical power). The biggest advantage of this method of packet-switching is that it occurs all-optically, meaning that there is no optical to electronic back to optical conversions taking place in order to do header processing. All of the header processing is done optically. One of the disadvantages is that the current proposed structure of the all-optical switching node uses a Cross-Gain Modulator (XGM) switch which is rather expensive because of the Semiconductor Optical Amplifier (SOA). In this method of packet-switching the length of the payload packet cannot exceed the length of one bit of the header packet. This is because the header processing output is only one header bit length long and this output is used to switch the payload packet. Thus any section of the payload packet that is outside this header processing output window will not be switched correctly / Dissertation (MEng (Electronic Engineering))--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / unrestricted

Cílem této práce je návrh a implementace řešení transparentního šifrování pro platformu Microsoft Windows. Řešení by mělo být propojitelné s produktem prevence proti úniku dat (DLP) a rozšiřovat jej. K implementaci byl využit framework Microsoft File System Minifilter Driver, s jehož pomocí je možné sledovat a upravovat přístup k jednotlivým souborům na externích zařízeních nebo discích za běhu systému. Soubory jsou zabezpečeny na pozadí tak, aby uživatel nebyl neovlivněn při práci. Ovladač zajišťuje, že uživatel vždy pracuje s rozšifrovanými daty. Dále bude také vyvinuta externí aplikace, která umožňuje uživateli přistoupit k zašifrovaným datům, aniž by musel být v síti, kde DLP produkt běží.

This thesis particularly deals with design and implementation of FPGA unit, which performs hardware acclerated header field extraction of network packets. By utilizing NetCOPE platform it is proposed flexible and effective high-peformance solution for high-speed networks. A theoretical part presents a classical protocol model and an analysis of the Internet traffic. Main part of the thesis is further focused on key issues in hardware packet preprocessing, such as packet classification and deep packet inspection. The author of this thesis also discusses possible technology platforms, which can be utilized to acceleration of network applications.

Os estudos sobre o ensino da tradução no Brasil ainda oferecem muito espaço para discussões. Valendo-se disso, este trabalho traz como um de seus objetivos uma breve reflexão sobre a sala de aula e sugere um possível método de ensino de tradução baseado na análise de material produzido por tradutores-aprendizes. A intenção é que, por meio da Linguística de Corpus, consigamos observar o processo de construção do texto de chegada pela ótica do aluno, nos mesmos moldes que o fazemos ao analisar material produzido por aprendizes de idiomas. Para tanto, compilamos um corpus de aprendizes de tradução, constituído por oito textos originais e cerca de 100 traduções para cada um deles. Alinhar tantas traduções referentes a um original de modo a permitir análises não foi tarefa fácil. A estratégia empregada para superar tal dificuldade foi o desenvolvimento de uma metodologia específica de alinhamento tendo como ferramenta planilhas eletrônicas. Tal metodologia tornou-se o foco central desta pesquisa. A utilização de fórmulas para a manipulação de dados textuais na planilha eletrônica resultou em um corpus alinhado, com todos os textos de partida e suas referidas traduções com cabeçalhos e com todas as linhas etiquetadas. Esse procedimento possibilitou a organização de um corpus para ser analisado tanto no editor de planilhas eletrônicas quando em programas como AntConc e WordSmith Tools. Além disso, também apresentamos a planilha eletrônica como uma ferramenta didática para ser usada nas aulas de prática de tradução. / Studies on the teaching of translation in Brazil still offer room for discussions. Having that in mind, one of the goals of this research aims at fostering a brief reflection upon the classroom and proposes a teaching method based on the analyses of material produced by translation learners. We show that Corpus Linguistics can be used to analyze student translations in the same way we do when we analyze material produced by language learners. For that purpose, we compiled a corpus of translations produced by learners, consisting of eight source texts in English and about 800 translations into Portuguese, approximately 100 for each text. Aligning so many translations to their original texts to favor analyses was not a simple task. Such difficulties were overcome by the development of a methodology for alignment, which became the central focus of this research. By utilizing formulas to deal with textual data in spreadsheets resulted in an aligned corpus containing source texts and their referring translations with headers and all lines tagged. Such procedure allowed us to come up with a corpus to be analyzed in both the spreadsheet editor and in programs such as AntConc and WordSmith Tools. In addition to that, we also introduced the spreadsheets as a didactic tool to be used in translation practice classes.

Os estudos sobre o ensino da tradução no Brasil ainda oferecem muito espaço para discussões. Valendo-se disso, este trabalho traz como um de seus objetivos uma breve reflexão sobre a sala de aula e sugere um possível método de ensino de tradução baseado na análise de material produzido por tradutores-aprendizes. A intenção é que, por meio da Linguística de Corpus, consigamos observar o processo de construção do texto de chegada pela ótica do aluno, nos mesmos moldes que o fazemos ao analisar material produzido por aprendizes de idiomas. Para tanto, compilamos um corpus de aprendizes de tradução, constituído por oito textos originais e cerca de 100 traduções para cada um deles. Alinhar tantas traduções referentes a um original de modo a permitir análises não foi tarefa fácil. A estratégia empregada para superar tal dificuldade foi o desenvolvimento de uma metodologia específica de alinhamento tendo como ferramenta planilhas eletrônicas. Tal metodologia tornou-se o foco central desta pesquisa. A utilização de fórmulas para a manipulação de dados textuais na planilha eletrônica resultou em um corpus alinhado, com todos os textos de partida e suas referidas traduções com cabeçalhos e com todas as linhas etiquetadas. Esse procedimento possibilitou a organização de um corpus para ser analisado tanto no editor de planilhas eletrônicas quando em programas como AntConc e WordSmith Tools. Além disso, também apresentamos a planilha eletrônica como uma ferramenta didática para ser usada nas aulas de prática de tradução. / Studies on the teaching of translation in Brazil still offer room for discussions. Having that in mind, one of the goals of this research aims at fostering a brief reflection upon the classroom and proposes a teaching method based on the analyses of material produced by translation learners. We show that Corpus Linguistics can be used to analyze student translations in the same way we do when we analyze material produced by language learners. For that purpose, we compiled a corpus of translations produced by learners, consisting of eight source texts in English and about 800 translations into Portuguese, approximately 100 for each text. Aligning so many translations to their original texts to favor analyses was not a simple task. Such difficulties were overcome by the development of a methodology for alignment, which became the central focus of this research. By utilizing formulas to deal with textual data in spreadsheets resulted in an aligned corpus containing source texts and their referring translations with headers and all lines tagged. Such procedure allowed us to come up with a corpus to be analyzed in both the spreadsheet editor and in programs such as AntConc and WordSmith Tools. In addition to that, we also introduced the spreadsheets as a didactic tool to be used in translation practice classes.