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Solar thermal augmentation of the regenerative feed-heaters in a supercritical Rankine cycle with a coalfired boiler / W.L. van RooyVan Rooy, Willem January 2015 (has links)
Conventional concentrating solar power (CSP) plants typically have a very high levelised cost of
electricity (LCOE) compared with coal-fired power stations. To generate 1 kWh of electrical
energy from a conventional linear Fresnel CSP plant without a storage application, costs the
utility approximately R3,08 (Salvatore, 2014), whereas it costs R0,711 to generate the same
amount of energy by means of a highly efficient supercritical coal-fired power station, taking
carbon tax into consideration.
This high LCOE associated with linear Fresnel CSP technology is primarily due to the massive
capital investment required per kW installed to construct such a plant along with the relatively
low-capacity factors, because of the uncontrollable solar irradiation. It is expected that the
LCOE of a hybrid plant in which a concentrating solar thermal (CST) station is integrated with a
large-scale supercritical coal-fired power station, will be higher than that of a conventional
supercritical coal-fired power station, but much less than that of a conventional CSP plant. The
main aim of this study is to calculate and then compare the LCOE of a conventional supercritical
coal-fired power station with that of such a station integrated with a linear Fresnel CST field.
When the thermal energy generated in the receiver of a CST plant is converted into electrical
energy by using the highly efficient regenerative Rankine cycle of a large-scale coal-fired power
station, the total capital cost of the solar side of the integrated system will be reduced
significantly, compared with the two stations operating independently of one another for
common steam turbines, electrical generators and transformers, and transmission lines will be
utilised for the integrated plants.
The results obtained from the thermodynamic models indicate that if an additional heat
exchanger integration option for a 90 MW (peak thermal) fuel-saver solar-augmentation
scenario, where an annual average direct normal irradiation limit of 2 141 kWh/m2 is considered,
one can expect to produce approximately 4,6 GWh more electricity to the national grid annually
than with a normal coal-fired station. This increase in net electricity output is mainly due to the
compounded lowered auxiliary power consumption during high solar-irradiation conditions. It is
also found that the total annual thermal energy input required from burning pulverised coal is
reduced by 110,5 GWh, when approximately 176,5 GWh of solar energy is injected into the
coal-fired power station’s regenerative Rankine cycle for the duration of a year. Of the total
thermal energy supplied by the solar field, approximately 54,6 GWh is eventually converted into
electrical energy. Approximately 22 kT less coal will be required, which will result in 38,7 kT
less CO2 emissions and about 7,6 kT less ash production. This electricity generated from the thermal energy supplied by the solar field will produce
approximately R8,188m in additional revenue annually from the trade of renewable energy
certificates, while the reduced coal consumption will result in an annual fuel saving of about
R6,189m. By emitting less CO2 into the atmosphere, the annual carbon tax bill will be reduced
by R1,856m, and by supplying additional energy to the national grid, an additional income of
approximately R3,037m will be due to the power station. The annual operating and
maintenance cost increase resulting from the additional 171 000 m2 solar field, will be in the
region of R9,71m.
The cost of generating 1 kWh with the solar-augmented coal-fired power plant will only be
0,34 cents more expensive at R0,714/kWh than it would be to generate the same energy with a
normal supercritical coal-fired power station.
If one considers that a typical conventional linear Fresnel CSP plant (without storage) has an
LCOE of R3,08, the conclusion can be drawn that it is much more attractive to generate
electricity from thermal power supplied by a solar field, by utilising the highly efficient large-scale
components of a supercritical coal-fired power station, rather than to generate electricity from a
conventional linear Fresnel CSP plant. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015
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The Hybrid Pressurized Air Receiver (HPAR) for combined cycle solar thermal power plantsKretzschmar, Holger 04 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Concentrating solar power technology is a modern power generation technology
in which central receiver systems play a significant role. For this technology a
field of heliostats is used to reflect solar irradiation to the receiver located on
top of the tower. An extensive review has shown that contemporary receiver
designs face geometric complexities, lack of thermal efficiency as well as issues
with durability and cost. The purpose of this study is to develop a new receiver
concept that can potentially reduce these issues. A parametric analysis
was used to identify potential means of improvement based on an energy balance
approach including sensitivities involved with convection and radiation
heat transfer. Design criteria such as the use of headers to minimize pressure
drop was also investigated. Based on these findings the hybrid pressurized
air receiver was developed which is a combination of tubular and volumetric
receiver technologies. The fundamental idea of the receiver was investigated
by simulating the ray-tracing and coupled natural convection and radiation
heat transfer. The ray-tracing results have shown that the use of quartz glass
is a prospective solution to higher allowable flux densities, but with reflection
losses in the order of 7 %. The coupled natural convection heat transfer
simulation further revealed that the receiver concept effectively eliminates the
escape of buoyant plumes and radiative heat losses are minimized. Empirical
data was gathered from a medium flux concentrator and good agreement with
the numerical results was obtained. The thesis therefore concludes that the
research outcomes were met. Ongoing research aims to optimise the receiver
concept for a 5MW pilot plant. / AFRIKAANSE OPSOMMING: Gekonsentreerde sonkrag tegnologie is ’n moderne kragopwekkingstegnologie
waar sentrale ontvangersisteme ’n beduidende rol speel. Vir hierdie tegnologie
word ’n veld heliostate gebruik om sonstraling na die ontvanger wat aan
die bopunt van die toring geleë is te reflekteer. ’n Omvattende hersiening
het daarop gewys dat kontemporêre ontwerpe van die ontvangers ’n aantal
geometriese kompleksiteite, ’n tekort aan termiese doeltreffendheid sowel as
probleme in terme van duursaamheid en koste in die gesig staar. Die doel van
die studie is om ’n nuwe ontvangerskonsep te ontwikkel wat moontlik hierdie
probleme kan verminder. ’n Parametriese analise is gebruik om potensiële
maniere van verbetering aan te dui wat gebaseer is op ’n energiebalans benadering;
insluitend sensitiwiteite betrokke by konvektiewe en stralingswarmteoordrag.
Ontwerpkriteria soos die gebruik van spruitstukke om drukverliese
te minimaliseer is ook ondersoek. Gebaseer op hierdie bevindinge is die hibriede
saamgepersde-lug ontvanger ontwikkel. Laasgenoemde is ’n kombinasie
van buis- en volumetriese ontvangertegnologie. Die fundamentele idee van die
ontvanger is ondersoek deur straalberekening asook die gelyktydige natuurlike
konveksie en stralingswarmteoordrag te simuleer. Die straalberekeningsresultate
het getoon dat die gebruik van kwarts glas ’n moontlike oplossing is om
hoër stralingsintensiteit te bereik, maar met refleksieverliese in die orde van
7 %. Die gelyktydige natuurlike konveksie en stralingswarmteoordrag simulasie
het verder aan die lig gebring dat die ontvangerkonsep die ontsnapping
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Rock bed thermal storage for concentrating solar power plantsAllen, Kenneth Guy 04 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Concentrating solar power plants are a promising means of generating electricity. However, they are dependent on the sun as a source of energy, and require thermal storage to supply power on demand. At present thermal storage – usually molten salt – although functional, is expensive, and a cheaper solution is desired. It is proposed that sensible heat storage in a packed bed of rock, with air as heat transfer medium, is suitable at temperatures of 500 – 600 °C. To determine if this concept is technically feasible and economically competitive with existing storage, rock properties, packed bed pressure drop and thermal characteristics must be understood. This work addresses these topics.
No previously published data is available on thermal cycling resistance of South African rock, and there is limited data from other countries in the proposed temperature range for long-term thermal cycling, so samples were thermally cycled. There is rock which is suitable for thermal storage applications at temperatures of 500 – 600 °C. New maps of South Africa showing where potentially suitable rock is available were produced. Dolerite, found extensively in the Karoo, is particularly suitable.
Friction factors were measured for beds of different particles to determine the importance of roughness, shape, and packing arrangement. Five sets of rock were also tested, giving a combined dataset broader than published in any previous study. Limitations of existing correlations are shown. The friction factor is highly dependent on particle shape and, in the case of asymmetric particles, packing method. The friction factor varied by up to 70 % for crushed rock depending on the direction in which it was poured into the test section, probably caused by the orientation of the asymmetric rock relative to the air flow direction. This has not been reported before for rock beds. New isothermal correlations using the volume equivalent particle diameter are given: they are within 15 % of the measurements. This work will allow a techno-economic evaluation of crushed rock beds using more accurate predictions of pumping power than could previously be made.
Thermal tests below 80 °C show that bed heat transfer is insensitive to particle shape or type. A heat transfer correlation for air in terms of the volume equivalent diameter was formulated and combined with the E-NTU method. The predicted bed outlet temperatures are within 5 °C of the measurements for tests at 530 °C, showing that the influence of thermal conduction and radiation can be reasonably negligible for a single charge/discharge cycle at mass fluxes around 0.2 kg/m2s.
A novel method for finding the optimum particle size and bed length is given: The Biot number is fixed, and the net income (income less bed cost) from a steam cycle supplied by heat from the bed is calculated. A simplified calculation using the method shows that the optimum particle size is approximately 20 mm for bed lengths of 6 – 7 m. Depending on the containment design and cost, the capital cost could be an order of magnitude lower than a nitrate salt system. / AFRIKAANSE OPSOMMING: Gekonsentreerde son-energie kragstasies is n belowende manier om elektrisiteit op te wek, maar hulle is afhanklik van die son as n bron van energie. Om drywing op aanvraag te voorsien moet hulle energie stoor. Tans is termiese stoor – gewoonlik gesmelte sout – hoewel funksioneel, duur, en n goedkoper oplossing word gesoek. Daar word voorgestel dat stoor van voelbare warmte-energie in n gepakte rotsbed met lug as warmteoordrag medium geskik is by temperature van 500 – 600 °C. Om te bepaal of dié konsep tegnies gangbaar en ekonomies mededingend met bestaande stoorstelsels is, moet rotseienskappe, gepakte bed drukval en hitteoordrag verstaan word. Hierdie werk spreek hierdie aspekte aan.
Geen voorheen gepubliseerde data is beskikbaar oor die termiese siklus weerstand van Suid-Afrikaanse rots nie, en daar is beperkte data van ander lande in die voorgestelde temperatuurbereik, dus is monsters onderwerp aan termiese siklusse. Daar bestaan rots wat geskik is vir termiese stoor toepassings by temperature van 500 – 600 °C. Nuwe kaarte van Suid-Afrika is opgestel om te wys waar potensieel geskikte rots beskikbaar is. Doleriet, wat wyd in die Karoo voor kom, blyk om veral geskik te wees.
Wrywingsfaktore is gemeet vir beddens van verskillende partikels om die belangrikheid van grofheid, vorm en pak-rangskikking te bepaal. Vyf rotsstelle is ook getoets, wat n saamgestelde datastel gee wyer as in enige gepubliseerde studie. Beperkings van bestaande korrelasies word aangetoon. Die wrywingsfaktor is hoogs sensitief vir partikelvorm en, in die geval van asimmetriese partikels, pakkings metode. Die wrywingsfaktor het met tot 70 % gevarieer vir gebreekte rots, afhanklik van die rigting waarin dit in die toetsseksie neergelê is. Dit is waarskynlik veroorsaak deur die oriëntasie van die asimmetriese rots relatief tot die lugvloei rigting, en is nie voorheen vir rotsbeddens gerapporteer nie. Nuwe isotermiese korrelasies wat gebruik maak van die volume-ekwivalente partikel deursnee word gegee: hulle voorspel binne 15 % van die gemete waardes. Hierdie werk sal n tegno-ekonomiese studie van rotsbeddens toelaat wat meer akkurate voorspellings van pompdrywing gebruik as voorheen moontlik was.
Termiese toetse onder 80 °C wys dat die warmteoordrag nie baie sensitief is vir partikelvorm en -tipe nie. n Warmte-oordragskorrelasie vir lug in terme van die volume-ekwivalente deursnee is ontwikkel en met die E-NTU-metode gekombineer. Die voorspelde lug uitlaat temperatuur is binne 5 °C van die meting vir toetse by 530 °C. Dit wys dat termiese geleiding en straling redelikerwys buite rekening gelaat kan word vir n enkele laai/ontlaai siklus by massa vloeitempos van omtrent 0.2 kg/m2s.
n Oorspronklike metode vir die bepaling van die optimum partikelgrootte en bedlengte word gegee: Die Biot-getal is vas, en die netto inkomste (die inkomste minus die bed omkoste) van n stoomsiklus voorsien met warmte van die bed
word bereken. n Vereenvoudigde berekening wat die metode gebruik wys dat die optimum grootte en lengte ongeveer 20 mm en 6-7 m is. Afhangende van die behoueringsontwerp en koste, kan die kapitale koste n orde kleiner wees as dié van n gesmelte nitraatsout stelsel
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An integrated energy storage scheme for a dispatchable wind and solar powered energy systemGarrison, Jared Brett 23 August 2010 (has links)
Wind and solar technologies have experienced rapid market growth recently as a result of the growing interest for implementation of renewable energy. However, the intermittency of wind and solar power is a major obstacle to their broader use. The additional risks of unexpected interruptions and mismatch with demand have hindered the expansion of these two primary renewable resources.
The goal of this research is to analyze an integrated energy system that includes a novel configuration of wind and solar coupled with two storage methods to make both wind and solar sources dispatchable during peak demand, thereby enabling their broader use. Named DSWiSS for Dispatchable Solar Wind Storage System, the proposed system utilizes compressed air energy storage (CAES) that is driven from wind energy and thermal storage supplied by concentrating solar thermal power in order to achieve this desired dispatchability. Although DSWiSS mimics the operation of a typical CAES facility, the replacement of energy derived from fossil fuels with energy generated from renewable resources makes this system unique. While current CAES facilities use off peak electricity to power their compressors, this system uses power from wind turbines. Also, rather than using natural gas for heating of the compressed air before its expansion through a turbine, DSWiSS uses solar thermal energy and thermal storage.
For this research, two models were created; the first is a dynamic model of a 1.5 MW variable speed wind turbine, programmed in PSCAD/EMTDC, that utilizes rotor resistive control to maintain rated power output. This model simulates the dynamic response of the wind turbine to changing wind conditions as well as the nominal performance parameters at all wind speeds. The second model is a steady state thermodynamic simulation of the turbomachinery power unit in the DSWiSS facility. By assuming conditions similar to those of a currently operating CAES facility in McIntosh, Alabama, the model calculates the performance parameters of DSWiSS and estimates the relative energy input requirements. By combining these models with a levelized lifetime cost analysis estimates of the power system performance and the cost of energy for the DSWiSS facility were estimated. The combination of these components yielded an efficiency greater than 46% for the main power block and a nearly equal utilization of both renewable resources. It was also estimated that the overall system is only slightly more expensive per unit of electricity generated than the current technologies employed today, namely coal, nuclear, and natural gas, but is comparable to a stand-alone solar thermal facility. However, this economic analysis, though accurate with regard to the technologies chosen, will not be complete until cost values can be placed on some of the externalities associated with power generation such as fuel cost volatility, national security, and emissions. / text
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Cogénération héliothermodynamique avec concentrateur linéaire de Fresnel : modélisation de l’ensemble du procédé / Concentrating solar power based cogeneration with Linear Fresnel Collector : modelling of the whole processVeynandt, François 01 December 2011 (has links)
Le concentrateur à réflecteur linéaire de Fresnel (LFR) est une technologie solaire thermodynamique en plein essor : petites applications industrielles (chaleur, froid, électricité) à centrales électriques (10-100 MWel). Ce travail de thèse établit un modèle global du procédé solaire, en régime permanent, pour un prédimensionnement du système. Le modèle comprend trois parties chaînées : (i) les transferts radiatifs dans le concentrateur optique, modélisés précisément par une méthode de Monte Carlo (environnement EDStar) ; (ii) les transferts thermiques dans le récepteur, évalués analytiquement (puissances, températures) ; (iii) le cycle thermodynamique, avec Thermoptim. L’application étudiée couple un concentrateur LFR à un moteur Ericsson. L’air est fluide caloporteur et de travail. Un prototype est en construction. L’hybridation et le stockage thermique sont des options clés. Un modèle systémique permettrait d’optimiser l’opération du procédé, en étudiant son comportement dynamique. / Linear Fresnel Reflector (LFR) is a promising Concentrating Solar Power technology. Research is booming and industrial applications are emerging. Applications range from small production units (heat, cold, electricity) to utility scale power plants (several tenths of MW). This PhD work establishes a global model of the solar process, in order to improve our knowledge of the system’s performances. It is a static model suited for a pre-design of the system. The model is chaining three parts. Radiative heat transfer in the optical concentrator is modelled by Monte Carlo statistical Method. The algorithm enables a detailed study of any geometrical configuration, especially through absorbed power flux maps on the receiver. The simulation tool is using the environment of development EDStar. The thermal model calculates analytically the useful thermal power, losses and temperature profiles along the receiver (glass cover, fluid, pipe...). The thermodynamic cycle is simulated analytically using the software Thermoptim. The studied application uses air as heat transfer and working fluid. Air directly feeds an Ericsson engine. The engine developed by LaTEP laboratory is promising for small scale cogeneration (1 to several tenths of kWel). The prototype Linear Fresnel Reflector built in Ecole des Mines d’Albi will enable experimental study of a solar process coupling an LFR concentrator and an Ericsson engine. The technology under study can feed a power plant or a cogeneration system in the industry, producing electricity and heat at 100 to 250°C. Hybridisation with an other energy source (biomass, gas...) and thermal storage (molten salt?) are key features to investigate. To optimise the operating strategy of the process, dynamic behaviour must be studied: a systemic or agent based model is a very relevant approach.
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Projeto e construção de um simulador solar concentrador. / Design and building of a solar simulator with radiation concentration.Rodrigues, Julia da Rosa Howat 06 May 2016 (has links)
Segundo o Atlas Brasileiro de Energia Solar, apesar das diferentes características climáticas observadas no Brasil, pode-se constatar que a média anual de irradiação solar global apresenta boa uniformidade e elevados índices por todo o país. Os valores desta grandeza em quase toda a extensão do território brasileiro (4200-6700 Wh/m2/dia) são superiores aos da maioria dos países da União Europeia, como Alemanha (900-1250 Wh/m2/dia), França (900-1650 Wh/m2/dia) e Espanha (1200-1850 Wh/m2/dia), onde projetos para aproveitamento de energia solar, alguns contando com fortes incentivos governamentais, são amplamente disseminados. Grande parte dos avanços científicos obtidos nos estudos sobre aproveitamento da energia solar se deve à utilização de simuladores solares compactos nos experimentos de longa duração. Ao substituir o Sol por fontes artificiais, como lâmpadas capazes de emitir radiação próxima à solar, os simuladores eliminam a dependência de fatores naturais como condições climáticas, horário do dia, intermitência e movimento de direção da radiação solar. O projeto proposto para esta dissertação de Mestrado teve como objetivo o domínio do processo de concepção e fabricação de um simulador solar concentrador formado por lâmpadas e um refletor ótico. Uma vez dominada a técnica, um modelo piloto de simulador solar foi construído e alguns testes executados para avaliar a qualidade do projeto, a resistência dos componentes e o fator de concentração do aparato. / According to the Brazilian Atlas of Solar Energy, despite the different climatic characteristics observed in Brazil, the annual average of global solar irradiation has good uniformity and high levels throughout the country. The values of global solar irradiation in almost the entire length of Brazil (4200-6700 Wh/m2/day) are higher than those observed in most European Union countries, like Germany (900-1250 Wh/m2/day), France (900-1650 Wh/m2/day) and Spain (1200-1850 Wh/m2/day), where projects for solar energy applications, some of them relying on strong government incentives, are widely disseminated. Several scientific and technological advances made in the study of solar energy applications are due to the use of compact solar simulators in long-term experiments. Replacing the Sun by artificial sources, such as arc lamps with radiation emission similar to the Sun spectrum, indoor simulators avoid the dependence on natural conditions such as the weather, the daytime, the sunlight intermittence and the directional change of the solar radiation. The project proposed for this dissertation aimed to master the design and manufacturing processes of a high-flux solar simulator consisting of arc lamps and an optical reflector. Once technique was understood, a solar simulation pilot model was built and some tests were performed to assess the project quality, the resistance of components and the apparatus concentration factor.
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Estudo das aferências imunorreativas ao hormônio concentrador de melanina (MCH) do núcleo accumbens, no rato Long-Evans (Rattus norvegicus). / Study of melanin-concentrating hormone (MCH) immunoreactive inputs of nucleus acumbens, in rats Long-Evans (Rattus norvegicus) .Haemmerle, Carlos Alexandre dos Santos 14 September 2010 (has links)
O MCH é um neuropeptídeo sintetizado preferencialmente no hipotálamo que exibe projeções para todo o neuroeixo, podendo modular vários processos fisiológicos, como a ingestão aguda de alimento. Um alvo de suas projeções é o núcleo accumbens (Acb), componente do estriado ventral envolvido na recompensa de estímulos hedônicos. Nossa contribuição visa mapear as células imunorreativas (ir) ao MCH responsáveis pelas aferências do Acb, onde também investigamos aposições entre os sistemas MCH, GABA e ChAT. Utilizaram-se os métodos de simples e duplas imunoperoxidases e combinação de imunofluorescência e captação de traçadores retrógrados. A maior densidade de fibras ir-MCH ocupa a parte shell do Acb (AcbSh); as aferências ir-MCH partem, por exemplo, da área hipotalâmica lateral e área perifornicial. Controles anterógrados foram obtidos a partir da LHA. Observaram-se aposições entre terminais ir-MCH e células ir-GABA e ir-ChAT, no AcbSh. Assim, sugere-se que os territórios hipotalâmicos que contém MCH inervem o AcbSh e contatem outros sistemas neuroquímicos no Acb. / MCH is a neuropeptide synthesized preferentially in the hypothalamus that shows projections throughout neuraxis, and may modulate various physiological processes such as food intake. One target of its projections is the nucleus accumbens (Acb), a component of the striatum involved in reward of hedonic stimuli. Our contribution aims to map immunoreactive (ir) cells responsible for the MCH inputs of the Acb, and to investigate appositions between MCH fibers, GABA and ChAT cells. We used the single and double immunoperoxidase methods and immunofluorescence combined with retrograde tracer. The highest density of fiber MCH-ir occupies the shell part of the Acb (AcbSh); MCH-ir inputs are mainly from lateral hypothalamic and perifornical areas. Anterograde controls were obtained from the LHA. We have founded appositions between MCH-ir terminals and GABA- and ChAT-ir cells at AcbSh. Thus, is suggested that hypothalamic areas containing MCH innervate the AcbSh and contact other neurochemical systems systems in the Acb.
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Integrais concentradas na fronteira e aplicações para problemas elípticos semilineares / Concentrating integrals and applications for semilinear elliptic problemsNogueira, Ariadne 09 August 2017 (has links)
Neste trabalho estudamos propriedades de integrais concentradas, ou seja, integrais cujo integrando atua apenas em uma vizinhança do domínio em questão. Tais termos são utilizados para conhecer o comportamento do integrando em regiões cuja medida de Lebesgue se aproxima de zero quando um parâmetro tende a zero. Ilustraremos estes resultados abstratos através de duas aplicações, ambas em domínios Lipschitz de R2, onde adicionamos um termo de concentração em problemas semilineares elípticos: domínio com fronteira oscilante que tende a um domínio limite fixo; e domínio do tipo fino com fronteira oscilante. Em ambos os casos, provamos a semicontinuidade superior e inferior da família de soluções dos problemas. / In this work we study concentrating integrals properties, in other words, we analyze integrals which function that is been integrated acts only in a neighborhood of the boundary of the domain. Such terms are use to know the behaviour of the integrand in regions which Lebesgue measure tends to zero when a parameter goes to zero. We will illustrate these abstract results through two applications, both in Lipschitz domains of R2, where we add a concentration term in semi linear elliptic problems: oscillating boundary domain which tends to a fixed limit domain; and a thin domain with a oscillatory boundary. In both cases we prove the upper and lower semicontinuity of the family of solutions from these problems.
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Um problema semilinear elíptico em domínio fino com termos de reações concentradas na fronteira / Semilinear elliptic equations in thin domains with reaction terms concentrating on boundaryManjate, Salvador Rafael 02 September 2015 (has links)
Analisamos o comportamento assintótico de uma família de equilíbrios de uma equação de reação-difusão com a condição de Neumann homegênea definido num domínio fino bidimensional com termos de reação concentradas em uma vizinhança oscilante da fronteira. Assumimos que o domínio e portanto a vizinhança oscilante se degeneram em um intervalo quando o parâmetro positivo tende a zero. O objetivo principal foi mostrar que essa família de soluções, converge para uma equação limite unidimensional, que captura a geometria e o comportamento assintótico dos conjuntos abertos onde o problema é estabelecido. De fato mostramos a continuidade da família de equilíbrios / In this work we analyze the behavior of a family of stead state solutions of a semilinear reaction-diffusion equation with homogeneous Neumann boundary condition, posed in a two-dimensional thin domain with reaction term concentrated in an narrow oscillating neighborhood. Indeed, we assume that the domain of definition of the solutions degenerates into an interval as a small parameter $\\epsilon$ goes to zero. Our main result is that this family of solutions converge to the solution of a one-dimensional limit equation capturing the geometry and oscillatory behaviour of the open sets where the problem is estabilished.
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Efeitos do treinamento físico intenso e da restrição alimentar sobre a ação da leptina mediada pelo hormônio concentrador de melanina no eixo reprodutor de ratas. / Effects of intense physical training and food restriction on the action of leptin mediated by melanin concentrating hormone in the reproductive axis in female rats.Silva, Renata Juliana da 14 October 2011 (has links)
Avaliamos o efeito do treinamento físico intenso e da restrição alimentar no eixo reprodutor e na expressão do RNAm do MCH em ratas fêmeas. Utilizamos ratas fêmeas sedentárias alimentadas (SA), sedentárias com restrição alimentar, treinadas alimentadas (TA) e treinadas com restrição alimentar. O grupo TR entrou em anestro a partir da quarta semana de experimento. Os grupos restritos apresentaram redução de peso corporal, ovários, úteros e tecido adiposo branco, comparados aos alimentados. Houve redução sérica de leptina nos grupos SR e TR. Os grupos TA, SR e TR apresentaram cistos ovarianos. A expressão do RNAm do ppMCH na área incerto-hipotalâmica (IHy) foi menor nos animais TR, SR e nos animais alimentados em proestro, e na área hipotalâmica lateral (LHA) foi maior nos animais em restrição alimentar e nos animais alimentados em proestro. Conclui-se que a leptina exerce forte influencia no eixo reprodutor feminino, tal ação parece ter envolvimento do MCH, sobretudo o proveniente da IHy, uma vez que o MCH da LHA tem relação com o estímulo a busca de alimento. / We evaluated the effect of intense physical training and food restriction on the reproductive axis and MCH mRNA expression in female rats. We used female rats fed sedentary (SF), food-restricted sedentary, trained fed (TF) and trained with food restriction. The group entered anestrus TR from the fourth week of the experiment. The restricted groups had reduced body weight, ovary, uterus and white adipose tissue, compared to the fed. There was a reduction of serum leptin in the SR and TR groups. The TF groups, SR and TR had ovarian cysts. The expression of mRNA ppMCH incerto-hypothalamic area (IHy) was lower in TR animals, SR and animals fed on proestrus, and the lateral hypothalamic area (LHA) were higher in animals on restricted food and animal feeding in proestrus. It is concluded that leptin exerts a strong influence on female reproductive axis, such action appears to have involvement of MCH, especially from the IHy, since the MCH of the LHA is related to the motivational behavior associated to the search for food.
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