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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.
101

Modelling climate change and socio-economic impacts within three regions of Scotland, 1970-2100

Parnell, Alan Kenneth January 2004 (has links)
There is a consensus of scientific thought that humana ctivities are altering the gaseous composition of the atmosphere and leading to global climate change. This thesis addresses the question of how this global climate change will manifest itself at the regional level. In particular, a dynamic simulation model integrating both climate change and climatically sensitives ocio-economic activities will be developed. This model will explore the regional variations in both climate change and socio-economic activity. Three Local Authorities in Scotland were chosen for this study, Argyll on the west coast, Stirling inland and Fife on the east coast. This provides a west-east transect across central Scotland. Meteorological data, covering the period 1970-1998, was collected from twelve sites spread across these regions. These data were analysed in order to provide a climatic profile of each of the regions, and to identify any evidence of climate change in the form of trends in the data. Data relating to socio-economic factors was taken from a variety of sources. Mere possible this covered the same period in time as the climate data. Both sets of data were examined to determine evidence of climate sensitivity in the socioeconomic data using suitable statistical techniques. A simple, yet thermodynamically sound, dynamic climate model was developed and calibrated for each region using the data from the previous analysis. This model allowed increasing levels of atmospheric carbon dioxide (C02) to directly affect the mean surface temperature of the three regions. Precipitation changes from the UKCIP02 regional climate model were included This allowed seasonal temperature and precipitation totals to be simulated, on a regional basis, under different climate change scenarios. Simulations, calibrated on datafrom 1970-1998, were run forward to 2100. The climate results were similar to the outputfrom the UKCIP02 model. Six sectors of a socio-economic model were constructed population, employment, land use, water resources, housing and emissions. Where statistically significant relationships, between climatic and the local socio-economic variables were found, these were included in the model. Simulations for the period 1970-2100, were run under four different climate change scenarios, and that of constant climate, in order to assessth eir impact on the six sectors at the regional scale. The results indicate considerable regional variations in the impacts both of climate change and the associated climatically sensitive activities. Argyll in the west, for example, could benefit from increased tourism and the potential for agricultural expansion. If in-migration is allowed to offset labour shortages, then the west sees a reversal of the population decline of previous decades. Climate change has little impact on the economy of the inland and eastern regions. However, a problem does emerge with water resources in the east. Summer droughts are seen to increase in frequency, suggesting that both the costs and benefits of climate change will be unevenly distributed. The implications of these results for the management of change are then discussed along with future research needs.
102

Design optimisation of a transverse flux linear oscillating generator for resonant free-piston Stirling applications

Joubert, Louis Hoogenhout 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The design optimisation of a linear oscillatory electric generator for application in freepiston Stirling engines is described in this thesis. A basic overview of free-piston Stirling engine technology is given by firstly providing a brief description of the operation of the heat engine. The applications of free-piston Stirling engines in industry are given and the proposed future applications are described. Different types of electrical machine designs from industry and academia are evaluated in a literature study. A classification structure is also proposed based on the magnetic flux variation within the designs. Based on the literature study, a transverse flux, single-phase, moving magnet, tubular topology was chosen for investigation. Athree dimensional finite element simulation was chosen as the most appropriatemethod to model the linear electrical machine. A commercial simulation package was called from a simulation script and the outputs from the finite element simulation were again used to calculate the electrical machine performance parameters using the instantaneous voltageand current values. A sequential quadratic programming algorithm was used to perform optimisation of the machine topologies, with the optimisation variables being dimensional parameters that describe the machine geometry and the goal of the optimisation to minimise the active mass of the machine, while maintaining preset minima for the output power and the efficiency. The machine was optimised for a number of different translator configurations and the different configurations were analysed and compared. It was found that a quasi-Halbach arrangement of the permanent magnets yielded the lowest overall active mass. A comparative study is also presented, where this quasi-Halbach variant is compared to a commercial machine. It was found that the linear machine design with a quasi-Halbach arrangement compares well with the commercial machine. A prototype and test bed was designed and constructed. Due to manufacuring difficulties however, the machine could not be completed in time for testing. / AFRIKAANSE OPSOMMING: Die ontwerpsoptimering van ’n lineêre ossillerende elektriese generator vir toepassing in vrysuier Stirling enjins word beskryf in hierdie tesis. ’n Basiese oorsig van vrysuier Stirling enjin tegnologie word gegee deur eerstens ’n kort beskrywing te gee van die werking van die hitte-enjin. Die aanwending van vrysuier Stirling enjins in industrie word gegee en voorgestelde toekomstige toepassings word beskryf. Verskillende tipes elektriese masjien ontwerpe vanuit die industrie en die akademie word geëvalueer in ’n literatuurstudie. ’n Klassifiseringstruktuur, gebaseer op die magnetiese vloedverandering in die ontwerpe, word ook voorgestel. ’n Transverse vloed, enkelfase, bewegende magneet, tubulêre topologie is gekies vir die ondersoek, gebaseer op die onder andere die literatuurstudie. ’n Drie-dimensionele eindige element simulasie is gekies as die mees geskikte metode om die lineêre elektriese masjien te modelleer. ’n Kommersiële simulasie pakket is deur middel van ’n simulasie skrip geroep en die uitsette vanaf die eindige element simulasie is weer gebruik om die werksverrigtingsparameters van die elektriese masjien te bereken deur gebruik te maak van die oomblikswaardes van die spanning en stroom. ’n Sekwensiële kwadratiese programmering algoritme is gebruik om optimering van die masjien topologieë te doen, met die dimensionele parameters wat die masjien geometrie beskryf as die optimeringsveranderlikes en doel van die optimering om die aktiewe massa van die masjien te minimeer, terwyl die uitsetdrywing en die benuttingsgraad by voorafgestelde minima gehou word. Die masjien is geoptimeer vir verskeie translator konfigurasies en die verskillende konfigurasies is geanaliseer en vergelyk. Dit is bevind dat ’n kwasi-Halbach skikking van die permanente magnete die laagste totale aktiewe massa gelewer het. ’n Vergelykende studie is ook aangebied, waar die kwasi-Halbach variant vergelyk is met ’n kommersiële masjien. Dit is bevind dat die lineêre masjien met die kwasi-Halbach skikking baie goed vergelyk met die kommersiële masjien. ’n Prototiepe masjien en toetsopstelling is ontwerp en aan mekaar gesit. Maar as gevolg van vervaardigbaarheids tekortkominge kon toetse op die prototiepe nie betyds gedoen word nie.
103

A neighbourhood through the viewfinder : an autodriven photo-elicitation of a housing estate undergoing renewal

Altenberger, Iris January 2013 (has links)
This thesis explores the ongoing regeneration of Raploch council housing estate, in Stirling, focusing on the lived experiences of the established residents who reside in the pre-regeneration council housing estate, or had family or historical links with the area, as well as new residents, who have moved into the new owner occupied houses that were built in the regeneration. Key informants who have worked in a professional capacity in the area were also consulted to broaden the perspective. The regeneration was a response to a long history of deprivation, segregation and stigmatisation, which led to the demolition of council housing on one side of a main road within the area. The demolition site was redeveloped by a partnership of private developers and a social housing provider. As a consequence of the regeneration there were various physical and social changes in the area, caused by the construction of new homes, as well as other changes to the built environment, and the influx of owner occupiers into the new housing. A visual research method, 'auto-driven photo elicitation', was utilised, which allowed an insight into these changes from a unique perspective. Participants made photos of the area, of places they wanted to discuss, which became the starting point of a subsequent interview process; allowing participants to focus on issues relevant to them. The findings showed that the participants attached a great importance to the history of this specific place, but also that there was segregation between the new residents and the established community. Further fragmentations, religious and historic territorial divisions, within the communities were visually reinforced by the regeneration process. The participants also attached great significance to the linguistic and semiotic landscape, which they interpreted in the context of this place.
104

The use of divergent series in history

Birca, Alina 01 January 2004 (has links)
In this thesis the author presents a history of non-convergent series which, in the past, played an important role in mathematics. Euler's formula, Stirling's series and Poincare's theory are examined to show the development of asymptotic series, a subdivision of divergent series.
105

Indikace tlaku ve válcích modelu Stirlingova motoru / Measurement of Stirling engine

Kovář, Michal January 2009 (has links)
This thesis describes the design chain to indicate the measuring cylinder Stirling engine. It describes the practical problems of measurement methodology and highlights the possible pitfalls of the measuring chain. For measuring the use of pre-existing model of gamma Stirling engine modification. It was carried out systematic measurement and evaluation of measured data. As a mathematical model for comparison with the measured data was used ideal cycle and Schmidt theory.
106

Analýza Stirlingova oběhu / Analysis of Stirling cycle

Hazda, Jakub January 2015 (has links)
This paper deals with the thermodynamic cycle of Striling engine. Analysis of the ideal cycle, Schmidt analysis and second-order method with loss correction by PROSA 2.4 software is applied. The results are compared with experimental data of two model engines.
107

Produktion av el och värme med stirlingmotorer från deponigas : På Blåbergets avfallsanläggning

Salomonsson, Gustav January 2022 (has links)
Sundsvall Energi har ansvaret för den gamla deponin på Blåbergets avfallsanläggning strax västerut från Sundsvall. Mellan slutet av 1960-talet fram till och med 2008 har ca 2 miljoner ton avfall deponerats. Från denna deponi har det under en längre tid producerats stora mängder deponigas. Deponigasen har tidigare använts i en hetvattenpanna vid Nacksta och tillfört värme till fjärrvärmesystemet. På grund av ineffektiv drift och minskande metaninnehåll i deponigasen stoppades transporten av deponigas till Nacksta 2013. Därefter har deponigasen enbart använts för fackling vilket innebär att deponigasen förbränns i en gasfackla. Enligt bestämmelser måste deponigas behandlas och användas för exempelvis energiutvinning eftersom innehållet i deponigasen har en kraftig växthuseffekt då gasen består av ca 40–60 % metan och 30–50 % koldioxid. Metan har en 28 gånger högre potential för global uppvärmning jämfört med koldioxid över en 100-årsperiod. I detta examensarbete har syftet varit att undersöka vilka möjligheter som finns för att ta vara på deponigasens energiinnehåll och därmed föreslå ett tekniskt alternativ gentemot enbart fackling av deponigasen. Dessutom har arbetet som syfte att beskriva den miljömässiga- och ekonomiska nyttan. Arbetet har utförts genom att energiinnehållet har tagits fram genom formler och antaganden samt att värmebehovet och uppskattningen av investeringskostnaden tagits fram. Nuvärdesmetoden och PayOffmetoden använts i samband ekonomiberäkningen i arbetet. Värmebehovet på anläggningen fick styra över hur mycket effekt som värmekällan bör ha för att klara högsta årsbehovet. Examensarbetet resulterade i att det mest lämpliga teknikalternativet, nämligen Stirlingmotorn, användes i detta arbete. På grund av ogynnsamma förutsättningar för att täcka värmebehovet på anläggningen har antagandet gjorts att den producerade värmen i stället gör miljönytta genom att tillföra värme till en av lakvattendammarna. Den producerade elen beräknades ha en täckningsgrad på ca 19 % av totala energiförbrukningen på anläggningen. Lönsamhetskalkylerna visar att lönsamheten för en eventuell investering blir ogynnsam vid låga elpriser samt vid låga metanhalter. Dock blir lönsamheten lämpligare vid höga elpriser och lägre investeringskostnader. Dessutom kunde det konstateras att lönsamheten blir betydligt gynnsammare om värmeproduktionen skulle ha nyttiggjorts samtidigt som elproduktionen. / Sundsvall Energi is responsible for taking care of the old landfill at  Blåberget waste facility west of Sundsvall. Between the end of the 1960s to year 2008, about 2 million tons of waste were deposit at the landfill. Large amounts of landfill gas have been produced at this landfill over the years. The landfill gas has previously been burned in a boiler at Nacksta and therefore added some heat to the district heating system. Due to inefficiency and declining methane content in the landfill gas, the distribution of landfill gas to Nacksta ended in 2013. Since then, the landfill gas has only been torched at the landfill site. Since the landfill gas has a strong greenhouse effect and due to regulations, the landfill gas must be treated and used for, as an example, energy utilization. Methane has a 28 times higher contribution risk to global warming compared to carbon dioxide over a 100-year period. In this project, the purpose has been to investigate what opportunities there are to utilize the energy content in the landfill gas and by that suggest an alternative instead of just torching the landfill gas. Additionally, the further purpose with the project is to describe the  environmental and economic benefits of the solution. The work has been done by determine the energy content by using formulas and assumptions. In addition, the heat demand for the landfill site as well as the estimation of investment cost was determined. The NPV and the Pay-Off was used in the economic calculations. The heat demand of the landfill site was the deciding factor of how much power the technical alternative should have to meet the highest annual heat demand. The project resulted in the fact that the most suitable technical alternative, namely the Stirling engine, became the technical choice in this work. Due to unfavorable conditions for the heat production from the Stirling engines at the plant, the assumption was made that the produced heat instead got  to supply heat to one of the leachate ponds. The electricity produced was calculated to meet around 19% of the total energy consumption at the landfill site. The economical estimates showed that the profitability of an eventual investment becomes unfavorable at low electricity prices and at low methane contents. However, the investment becomes far more profitable at high electricity prices and at lower investment costs. In addition, the results showed that profitability would be far more favorable if the produced heat had been utilized for property heating simultaneously as the electricity got produced.
108

Spin Network Evaluation and the Asymptotic Behavior

Jayasooriya Arachchilage, Dinush Lanka Panditharathna 01 September 2020 (has links)
AN ABSTRACT OF THE DISSERTATION OFDinush Lanka Panditharathna Jayasooriya Arachchilage, forthe Doctor of Philosophy degree in MATHEMATICS, presented on June 22, 2020 at SouthernIllinois University Carbondale.TITLE: SPIN NETWORK EVALUATION AND THE ASYMPTOTIC BEHAVIORMAJOR PROFESSOR: Dr. Jerzy KocikGraphically, a spin network is a trivalent graph with weights on each edge. At anyof the vertices, the sum of all three weights is even and the sum of any two weights isgreater than or equal to the remaining weight. If the spin network has no free ends, thenwe can evaluate the spin network. Here, we propose a method to evaluate some basic spinnetworks using the idea of Stirling triangle.Tangent circles with integer curvatures are a natural source to make a spin network.In particular, there are spin networks corresponding the Apollonian circle packing and theFord circle packing. We obtain the recurrence relations using the Descartes circle theoremand we evaluate the Apollonian spin network and the Ford circle spin network. We alsodiscuss the asymptotic behavior of the Ford circle spin network.
109

Bounding the Number of Graphs Containing Very Long Induced Paths

Butler, Steven Kay 07 February 2003 (has links) (PDF)
Induced graphs are used to describe the structure of a graph, one such type of induced graph that has been studied are long paths. In this thesis we show a way to represent such graphs in terms of an array with two colors and a labeled graph. Using this representation and the techniques of Polya counting we will then be able to get upper and lower bounds for graphs containing a long path as an induced subgraph. In particular, if we let P(n,k) be the number of graphs on n+k vertices which contains P_n, a path on n vertices, as an induced subgraph then using our upper and lower bounds for P(n,k) we will show that for any fixed value of k that P(n,k)~2^(nk+k_C_2)/(2k!).
110

[en] NUMERICAL SIMULATION OF A ROTARY STIRLING ENGINE / [pt] SIMULAÇÃO NUMÉRICA DE UM MOTOR STIRLING ROTATIVO

CARLO CESAR DRUMOND 25 May 2017 (has links)
[pt] O presente trabalho estuda um motor de deslocamento positivo Stirling rotativo. Dois modelos de simulação para este motor Stirling rotativo são desenvolvidos. O primeiro modelo utiliza o método isotérmico, mediante o qual a câmara de expansão/compressão do motor está à mesma temperatura do reservatório térmico com que troca calor. O segundo modelo utiliza o método de volumes de controle, no qual o motor é dividido em cinco volumes de controle: as câmaras de expansão e compressão, o aquecedor, o resfriador e o compartimento rotativo. Para cada volume de controle aplicam-se as equações de conservação de massa e energia e de equações de estado do gás. O sistema de equações diferenciais ordinárias resultantes do segundo modelo, é integrado, permitindo obter-se a variação no ângulo do eixo para todas as variáveis termodinâmicas do motor (pressão, temperatura, etc.). Dadas as condições de operação e a geometria do motor rotativo em estudo, os modelos preveem resultados globais e transientes ângulo a ângulo. Os resultados dos modelos são confrontados com resultados teóricos disponíveis na literatura. / [en] The present work studies a positive displacement rotary Stirling engine. Two simulation models for this rotary Stirling engine are developed. The first model applies the isothermal method, in which the gas at the engine expansion / compression chamber has the same temperatures of the thermal reservoir. The second model uses the control volume method, in which the engine is divided into five control volumes: the expansion and compression chambers, the heater, the chiller and the rotary chamber. For each control volume the equations of conservation of mass and energy and the equation of state, are applied. The system of ordinary differential equations resulting from the second model is integrated allowing to obtain the variation in the axis angle for all thermodynamic variables of the motor (pressure, temperature, etc.). Given the operating conditions and geometry of the rotating motor under study, the models provide global and transient results from angle to angle. Results from two models are confronted with theoretical results available in the literature.

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