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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Fluid field analysis on a flexible combustor for a hybrid Solar / Brayton system : A numerical study

JACQUEMARD, PAUL January 2020 (has links)
Recent improvements to concentrating solar dish systems lead to further focus on hybridization systems for small-scale power generation applications. Variability of the solar load creates new requirements for combustion systems. This thesis presents a CFD simulation of the air flow inside a new combustor design for the combination of an impinging air solar receiver and a MGT. The system consists of a LPP tubular combustor with radial main swirler and central pilot burner. Focus is made on the pressure loss at the downstream impinging cooling wall for appropriate flow distribution between reacting and bypass air. Heat transfer is not studied due to lack of time. A fully-hexahedral multi-zones mesh of the system without fuel injection has been generated with Ansys ICEM software, making use of its O-grid capabilities. A realizable k-epsilon model is used for turbulence modelling. Several impinging hole’s diameters are studied to find the right balance between the two streams. Streamlines are also observed to confirm the location of recirculation zones and recommend design improvements. / Nya förbättringar av koncentrerade solskålssystem leder till ytterligare fokus på hybridsystem för småskaliga applikationer för elproduktion. Ojämn solstrålning skapar nya krav på förbränningssystem. Detta examensarbete presenterar en CFD-simulering av luftflödet i en ny förbränningsdesign för en kombination av en solfångare med forcerad konvektionskylning och en mikrogasturbin (MGT). Systemet består av en LPP-rörbrännare med radiellt virvelsystem och central pilotbrännare. Studien fokuserar på tryckförlusten vid slaghålsväggen, som används för kylning vid förbränning, och lämplig flödesfördelning mellan reagerande- och förbigående flöde. Värmeöverföring studeras inte på grund av tidsbrist. Ett helt sexkantigt nät med flera zoner i systemet utan bränsleinsprutning har genererats med Ansys ICEM-programvara som använder O-nätfunktioner. En realiserbar k-epsilon-modell används för turbulensmodellering. Flera slaghålsdiametrar studeras för att hitta rätt balans mellan de två strömmarna. Även strömlinjer observeras för att bekräfta placeringen av återcirkulationszoner och kunna rekommendera förbättringar av designen.
2

Rozhraní pro průmyslovou HD kameru / Industrial HD camera interface

Juřica, Libor January 2015 (has links)
Master´s thesis deals with creating circuit for receiving data from industrial camera. IP Core is designing for FPGA. Theoretical part of the work describes SDI interface, analysis of relevant SMPTE standards and specification of data format. The thesis include general characteristics of multigigabit transceivers. Practical part include VHDL description of SDI receiver. Thesis presents simulations of created circuit, implementation for real application and measurement results for signal transmission over slip ring.
3

Upper Secondary Students' Assessment of Four Women Speaking Four Different Varieties of English

Sahlström, Camilla January 2006 (has links)
<p>Society exhibits a wide variety of different languages with various prominent features. At the same time as we honour diversity, however our civilisation is coloured with prejudice and preconceptions. Even if there is a rather liberal view on language use today, dialects and accents still carry positive and negative connotations for a majority of citizens. Research shows, that we are prejudiced and that we have predetermined ideas when it comes to certain language varieties.</p><p>In this study, I take up four varieties of Standard English: American, English, Australian and Scottish. I focus on the associations Swedish students make when it comes to these four language varieties and how this transforms into attitudes towards the speakers. A language attitude study is carried out by using a modified Matched Guise Test. I explain the difference between dialect and accent, as well as societal attitudes to language varieties and present some prominent linguists and their methods. Finally, I draw some conclusions by comparing my results to previous findings.</p>
4

Understanding Design Requirements for Building Reliable, Space-Based FPGA MGT Systems Based on Radiation Test Results

Ellsworth, Kevin M. 20 March 2012 (has links) (PDF)
Space-based computing applications often demand reliable, high-bandwidth communication systems. FPGAs with Mulit-Gigabit Transceivers (MGTs) provide an effective platform for such systems, but it is important that system designers understand the possible susceptibilities MGTs present to the system. Previous work has provided a foundation for understanding the susceptibility of raw FPGA MGTs but has fallen short of testing MGTs as part of a larger system. This work focuses on answering the questions MGT system designers need to know in order to build a reliable space-based MGT system. Two radiation tests were performed with a test architecture built on the Aurora protocol. These tests were specifically designed to discover system susceptibilities, and effective mechanisms for upset detection, recovery, and recovery detection. Test results reveal that the Aurora protocol serves as an effective basis for simple point-to-point communication for space-based systems but that some additional logic is necessary for high reliability. Particularly, additional upset detection and recovery mechanisms are necessary as well as additional status indicators. These additions are minimal, however, and not all are necessary depending on system requirements. The most susceptible part of the MGT system is the MGT tile components on the RX data path. Upsets to these components most often results in data corruption only and do not affect system operation or disrupt the communication link. Most other upsets which do disrupt normal system operation can be recovered automatically by the Aurora protocol with built-in mechanisms. Only 1% of observed events in testing required additional recovery mechanisms not supplied by Aurora. In addition to test data results, this work also provides suggestions for system designers based on various system requirements and a proposed MGT system design based on the Aurora protocol. The proposed system serves as an example to illustrate how test data can be used to guide the system design and determine system availability. With this knowledge designers are able to build reliable MGT systems for a variety of space-based systems.
5

Single Event Mitigation for Aurora Protocol Based MGT FPGA Designs in Space Environments

Harding, Alexander Stanley 17 June 2014 (has links) (PDF)
This work has extended an existing Aurora protocol for high-speed serial I/O between FPGAs to provide greater fault recovery in the presence of high-energy radiation. To improve on the Aurora protocol, additional resets that affect larger portions of the system were used. Detection for additional error modes that occurred but were not detected by the Aurora protocol was designed. Radiation testing was performed on the Aurora protocol with the additional mitigation hardware. The test gathered large amounts of data on the various error modes of the Aurora protocol and how the additional mitigation circuitry affected the system. The test results showed that the addition of the recovery circuitry greatly enhanced the Aurora protocol's ability to recover from errors. The recovery circuit recovered from all but 0.01% of errors that the Aurora protocol could not. The recovery circuit further increased the availability of the transmission link by proactively applying resets at much shorter intervals than used in previous testing. This quick recovery caused the recovery mechanism to fix some errors that may have recovered automatically with enough time. However, the system still showed an increase in performance, and unrecoverable errors were reduced 100x. The estimated unrecoverable error rate of the system is 5.9E-07 in geosynchronous orbit. The bit error rate of the enhanced system was 8.47754E-015, an order of magnitude improvement.
6

Upper Secondary Students' Assessment of Four Women Speaking Four Different Varieties of English

Sahlström, Camilla January 2006 (has links)
Society exhibits a wide variety of different languages with various prominent features. At the same time as we honour diversity, however our civilisation is coloured with prejudice and preconceptions. Even if there is a rather liberal view on language use today, dialects and accents still carry positive and negative connotations for a majority of citizens. Research shows, that we are prejudiced and that we have predetermined ideas when it comes to certain language varieties. In this study, I take up four varieties of Standard English: American, English, Australian and Scottish. I focus on the associations Swedish students make when it comes to these four language varieties and how this transforms into attitudes towards the speakers. A language attitude study is carried out by using a modified Matched Guise Test. I explain the difference between dialect and accent, as well as societal attitudes to language varieties and present some prominent linguists and their methods. Finally, I draw some conclusions by comparing my results to previous findings.
7

Process Simulations of Small Scale Biomass Power Plant

Godswill, Uchechukwu Megwai January 2014 (has links)
Power generation from biomass based renewable energy technologies is a promising option in retrofitting our dependence in conventional power generation processes. The development of any society is not possible without sustainable energy and access to energy creates that environment that allows the world to thrive. Electricity access especially in developing regions of the world is of particular interest. This work provides results on electricity efficiency, the economic feasibility and environmental impact of biomass based power technologies in small scale setting using Aspen Plus software. The power generation processes analysed on standalone basis include - micro gas turbine, gas turbine, steam turbine, Stirling engine and internal combustion engine. Some of the processes are optimized in the design to suit the specific climate and available wood waste stream in Nigeria is considered in this work. Simulation results indicate that gas engines power technologies gave a better electric performance of more than 30% with its integration with biomass gasification technology in production of fuel gas. The stirling engine power technology shows a good prospect despite its yet to be commercial status. The modification of the engine (removal regenerator) gives a better electric efficiency. Also result shows that internal combustion engine process emits more of nitric oxides compared to other technologies which create doubts over its environmental compatibility. Economic studies show that for small scale power generation, internal combustion engines and stirling engines are economic feasible. Also, steam turbine and gas turbine illustrate why they are mostly applied in medium/large scale biomass power generation specially recommended to regions where more biomass resource are produced. The micro gas turbine power technology can also be applied in small scale despite its high total investment capital. Furthermore, the study shows that about from 1.8 million tonnes per year of saw dust (wood waste) produced from lumber industries in Nigeria, about 1.3 TWh of electricity can be generated from 1000 MW power plant. Power generation via the utilization of biomass prove to be a possible path to Nigeria’s economic, social and environmental sustainability but the extent to which this can achieved is strongly dependent institutional framework, investment, incentives and information policies. / Program: Masterutbildning i energi- och materialåtervinning
8

Intervention Strategies to Decrease Discipline Issues in an Urban pre-K-8 Public School

Mason, Wendy 01 January 2015 (has links)
Intervention Strategies to Decrease Discipline Issues in an Urban pre-K-8 Public School by Wendy A. Mason MEd, Walden University, 2005 BA, Kean University, 1979 Doctoral Study Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Education Walden University October 2015 The educational problem addressed in this study was the lack of empirically grounded evidence of the intervention strategies an urban school in the northeast region of the United States used to decrease school discipline problems. The purpose of this qualitative case study was to identify, explore, and understand the strategies used by school personnel to decrease discipline problems. The conceptual framework was anchored in social learning and communities of practice theories. The research questions focused on identifying the types of student discipline problems, the strategies developed and deployed to decrease the discipline problems, and the outcomes of the strategies. Semi-structured interviews were conducted with 12 participants: 1 administrator, 10 teachers, and 1 counselor. Archival documents such as incident reports, discipline referral forms, the school's year-end report, and district suspensions reports were also examined for discipline patterns. Data analysis strategies included transcribing interview data, identifying patterns, and data triangulation. Results indicated that disrespect, noncompliant behavior, willful disobedience, fighting, and bullying were major discipline problems at the school. A multiplicity of strategies such as in-school and out-of-school suspension and character education effectively decreased discipline issues. Recommendations include a regular review of prevention strategies to determine which strategies are effective at reducing discipline. Positive social change implications include implementing invention strategies that create safe learning environments for students and staff in which all students can achieve academic success that leads to timely graduation and productive and responsible citizenship in the communities in which students live.
9

Vícekanálový převodník digitálního videosignálu HD-SDI / Multichannel HD-SDI digital video signal converter

Kučera, Stanislav January 2014 (has links)
This master’s thesis deals with the design of six channel SD, HD and 3G HD-SDI digital video signal converter to 10-Gigabit Ethernet. In the introductory part, the conception of designed device is formulated. The theoretical background is provided in four chapters, where main standards and design rules related to digital electronics’ design are analyzed. The emphasis is placed on signal integrity at high-speed interconnects. There mostly practical examples, calculations and simulations are utilized. The design part contains thorough description of main subsystems’ design, implementation of FPGA, SDI input channels and 10-Gigabit Ethernet PHY. In the final part, the first tests and measurements of the build prototype are summarized. As an example, the comparison of signal integrity simulation to measurement is provided.

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