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1
Alvarenga, Ana Paula Dornelles de. "Estudos de sistemas cristalinos e liquidos por meio de espalhamentos Raman e Brillouin em função da temperatura". Universidade de São Paulo, 1993. http://www.teses.usp.br/teses/disponiveis/43/43133/tde-27022014-110533/.
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Espalhamentos Raman e Brillouin foram usados no estudo de vários sistemas que apresentam questões em aberto no comportamento de suas propriedades físicas com a temperatura. Estudamos materiais de interesse geofísico, como o rutilo Ti02 e o espinélio MgAl204. Os resultados de espalhamento Raman no rutilo Ti02, a temperaturas de 1000 K, mostraram que as frequências dos fônons ópticos diminuem pouco com a temperatura. A ausência de um modo soft a estas altas temperaturas, confirma a estabilidade da stishovite, material de estrutura análoga ao rutilo TiO2, e que existe no manto terrestre. As constantes elásticas do espinélio MgAl204 foram medidas em função da temperatura, por meio de espalhamento Brillouin até 2100 K: estas foram as temperaturas mais altas já obtidas em experimentos de espalhamento Brillouin. A partir das constantes elásticas, calculamos parâmetros de importância geofísica, pois este material é estruturalmente análogo ao espinélio y-Mg2Si04, considerado o maior constituinte do manto inferior terrestre. O estudo de espalhamento Raman no material sintético c-BN, a temperaturas de 1600 K, mostrou que este material retém suas propriedades mecânicas a estas altas temperaturas, sendo indicado para aplicações onde estas condições são requeridas. Realizamos espalhamento Raman nos compostos GaI3, GaBr3,AlBr3 e AlCI3, com a finalidade de determinar suas estruturas perto de seus pontos de fusão. A estrutura dos líquidos foi determinada como sendo composta por moléculas diméricas, presentes também nos sólidos, com a excessão do composto AICI3. Neste composto, a mudança de estado sólido-líquido ocorre com uma brusca mudança estrutural, onde o sólido iônico transforma-se em um líquido de moléculas diméricas. As propriedades elásticas da água sob pressões negativas foram investigadas por meio de espalhamento Brillouin em microinclusões, naturais e sintéticas, de água e vapor de água em cristais de quartzo. Através do aquecimento, estas inclusões homogenizam a uma temperatura Th: no resfriamento a partir de Th, o sistema atinge um estado metaestável, interrompido pela nucleação da fase gasosa. Nossos experimentos geraram tensões da ordem de 100 MPa. O enxofre líquido foi estudado por espalhamento Brillouin, a temperaturas em torno da transição À. A interpretação dos espectros polarizados foi feita de acordo com o formalismo de Mori-Zwanzig, e não mostraram evidência da transição À. Os espectros despolarizados, por outro lado, mostraram uma pronunciada anomalia em torno da temperatura da transição .Raman and Brillouin scattering were used in the study of several systems which present open questions in their physical properties. under the effect of the temperature. Materials of geophysical interest were studied as rutile Ti02 and the spinel MgAh04. Results of Raman scattering from Rutile (Ti02) up to 1000 K show that the frequencies of the optical phonons decrease slowly with temperature, and do not show anomalies reported in previous work at lower. temperatures The absence of a soft mode at these high temperatures confirms the stability of stishovitte, a structural analog of Rutile (Ti02), wich exists in the Earth\'s mantle. The elastic constants of Spinel MgAh04 were measured using Brillouin scattering up to 2100 K: this is the highest temperature ever reported for a Brillouin scattering experiment. Parameters of geophysical importance were calculated, in an analog to y-Mg2Si04, believed to be the major constituent of the Earth\'s lower mantle. Raman scattering measurements on cubic boron nitride up to 1600 K, indicate that at high temperature this material retains its mechanical strength, and it is therefore suitable in applications where very high temperatures are involved. The vibrational properties of molten GaI3, GaBr3, AlBr3 and AlCI3. were determined by Raman scattering. The structure of these compounds in the molten state is a dimer represented by M2X6 consisting of two tetrahedra sharing a halide edge. In AlC13, the melting process leads to a drastic change in the structure. Using Brillouin scattering we have investigated the elastic properties of water under negative pressures. The samples were H20 liquid-vapor inclusions in -quartz which could be heated to their homogenization temperature; on cooling, negative pressures as high as 100 MPa were reached before a vapor bubble nucleated. The velocity of sound results obtained indicate that nucleation occurs long before reaching the mechanical instability region, where the bulk modulus is zero. Liquid Sulphur was studied by Brillouin scattering as a function of temperature trough the lambda transition. Mori-Zwanzig formalism was applied to fit the polarized spectra and they showed no evidence of a lambda transition. On the other hand the depolarized spectra exhibited marked changes near the lambda transition temperature.
2
Harbison, Brian K. "Temperature stabilization for negative bias temperature instability". Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Sep%5Harbison.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 2007.Thesis Advisor(s):lWeatherford, Todd R. ; Parker, Andrew A. "September 2007." Joint authors: Description based on title screen as viewed on October 22, 2007. Includes bibliographical references (p.59-60). Also available in print.
3
Hsu, Chuan-liang. "Influence of cooling rate on glass transition temperature and starch retrogradation during low temperature storage /". free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9924889.
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Bezerra, Jose Raniere Mazile Vidal. "Comportamento reologico da polpa de manga (Mangifera indica L-Keitt)". [s.n.], 2000. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255910.
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Orientador: Carlos Alberto GasparettoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Neste trabalho experimental foi determinado o comportamento reológico da polpa de manga variedade Keitt na faixa de temperatura de 10°C a 60°C. A polpa integral foi produzida em planta piloto e refinada num "finisher" com peneira de 1,6mm. Foram também utilizadas a polpa integral centrifugada e a integral despectinizada. As análises reológicas foram conduzidas num reômetro Haake Rotovisco RV-20 com geometrias de cilindros concêntricos e de placas paralelas. Os reogramas foram descritos pelos modelos de Ostwaldde-Waelle (Lei da Potência), Casson, Herschel-Bulkley e Mizrahi-Berk na faixa de taxa de deformação 50-900s-1 e todas as amostras apresentaram comportamento pseudoplástico. Os resultados obtidos mostraram que o sistema de cilindros concêntricos e de placas paralelas pq 45, com distância de 1,Omm, são os mais adequados à caracterização reológica das polpas ensaiadas. Os resultados também foram analisados em termos de viscosidade aparente, calculadas a partir do modelo de Mizrahi-Berk, através do qual foram ajustados os dados obtidos com cilindros concêntricos. O efeito da temperatura sobre os parâmetros reológicos que representam o índice de consistência (KM)foram ajustados, usando-se a equação de Arrhenius ln(KM) Al+Bl/T. Nos casos dos modelos de Mizrahi-Berk e Lei da Potência o índice de comportamento (nM)foi ajustado por uma função do tipo nM -A2+B2T. As polpas integral e despectinizada, a partir de 40°C, mostraram um aumento da viscosidade aparente
Abstract: Experiments were conducted in order to know the rheological behaviour ofmango pulp (Keitt) in the temperature range lO-60°C. Whole pulp was produced at pilot plant and refined in a finisher with 1.6mmmesh. Whole centrifuged and whole despectinized pulps were also analysed. Rheometry was conducted with a Haake-Rotovisco RV-20 system using both concentric cylinders and parallel plate. Rheograms were fitted with models by Ostwaldde-Waelle, Casson, Herschel-Bulkley and Mizrahi-Berk for the shear rate within the range 50-900s-1, showing pseudoplastic behaviour for alI pulps. Aparent viscosity were obtained from calculations using the Mizrahi-Berk fitted parameters in to data produced with concentric cylinders. Consistency index (KM)of the best fitted models were described in terms of temperature using Arrhenius equation ln(KM) Al+Bl/T and the flow behaviour index (nM)was fitted to nM A2+B2T. Whole and despectinized pulps showed an increase in apparent viscosity beyhond 40°C
Doutorado
Doutor em Engenharia de Alimentos
5
Gozzo, Angela Maria. "Comportamento reologico de chocolates ao leite sem fibras e enriquecido com fibras soluveis". [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255950.
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Orientador: Carlos Alberto GasparettoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Neste trabalho foi determinado o comportamento reológico de chocolate sem fibras e chocolate enriquecido com fibras solúveis. As amostras foram produzidas em planta piloto, aplicando-se a mesma formulação e processo para ambas as amostras, variando somente a quantidade de açúcar e fibras. As análises reológicas foram realizadas em um reômetro de cilindros concêntricos marca HAAKE Rotovisco RV-20, em temperaturas de 38, 40, 42, 45 e 50°C, na faixa de deformação de 0 a 250 s-1. Os pontos experimentais dos reogramas foram ajustados aos modelos reológicos de Casson, Bingham e Windhab e todos descreveram adequadamente o comportamento reológico dos chocolates. Os parâmetros ajustados pelos modelos de Bingham e de Windhab foram muito próximos, indicando que os termos adicionados ao modelo de Windhab não influenciaram no comportamento reológico das amostras. O melhor ajuste reológico foi obtido pelo modelo de Casson, apresentando coeficientes de correlação próximos a um (1.0) e uma diferença entre os valores experimentais e preditos pelo modelo próxima a zero. Para analisar o comportamento da tensão de cisalhamento em relação ao tempo, os experimentos foram realizados à taxas de deformação constantes (50, 100, 150, 200 e 250 s-1) para cada temperatura. Os resultados obtidos mostraram que a viscosidade plástica e a tensão residual são maiores para as amostras de chocolate enriquecido com fibras, as quais não apresentaram comportamento tixotrópico. O efeito da temperatura sobre os parâmetros reológicos foi descrito pelo modelo de Arrhenius, observou-se que a energia de ativação é maior para as amostras de chocolate enriquecidas com fibras
Abstract: The concern of this work was to determine the rheological behaviour of chocolate without fibers and chocolate enriched with soluble fibers. Those samples were produced at pilot plant, using the same recipe and process, varying sugar and fibers amount. The rheological analyses were realized in a HAAKE Rotovisco RV-20 system using concentric cylinders, at 38, 40, 42, 45 and 50°C for shear rate at 0 - 250 s-1. Rheograms were fitted according to the following models: Bingham, Casson e Windhab. The parameters adjusted by the Bingham and Windhab models were satisfactory, indicating that the terms added to the Windhab model, didn't have influence in the rheological behaviour of the samples. The best rheological adjustment was obtained by Casson model where the plastic viscosity decreased with temperature and the yield stress had a unsteady behaviour for both samples. The results showed that the plastic viscosity and the yield stress the largest for the chocolate enriched with fibers, which didn't present thixotropy behaviour. The Arrhenius model describe the temperature effect on rheology behaviour of samples. The results also showed that activation energy for enriched chocolate with soluble fibers is bigger than activation energy for chocolates without fibers
Mestrado
Mestre em Engenharia de Alimentos
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Stevan, Savić. "Кретање екстремних температура ваздуха на подручју Војводине у периоду 1951-2000". Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2009. https://www.cris.uns.ac.rs/record.jsf?recordId=16710&source=NDLTD&language=en.
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Тема докторске дисертације је анализа екстремених температура ваздуха на подручју Војводине (северни део Србије), која се простире на површини од 21.506 km2. У анализи су коришћене временске серије са десет метеоролошких станица за временски период од 1951. до 2000. године. Укупно је анализирано осам параметара екстремних температура, и то: средње максималне и минималне, апсолутне максималне и минималне и дани са екстремним температурама (ледени, мразни, летњи и тропски). Истовремено, у истраживање су укључене и временске серије распона средњих максимума и минимума, као и распон средњих апсолутних максимума и минимума. Током рада анализирани су годишњи, сезонски и месечни низови претходно наведених параметара екстрема. У циљу добијања неопходних резултата, коришћено је више метода, као што су: Александерсонов тест, проста линеарна регресија, t-тест, Мен-Кендалов тест, коефицијент корелације, кластер анализа, анализа ројева тачака, хистограм и вишеструка линеарна регресија. Резултати хомогености месечних и сезонских временских серија, који су добијени коришћењем Александерсоновог теста, представљају прве резултате за простор Војводине и показују да је 26% испитиваних низова нехомогено, од којих је 11% подешено, односно хомогенизовано. Анализе параметара екстремних температура ваздуха показују тенденције пораста у последњих педесет година XX века. Посматрајући годишње низове, јављају се позитивни трендови код свих параметара (осим за ледене и мразне дане, где су трендови опадајући), међутим, једино се за средње минималне температуре може потврдити да имају сигнификантан пораст током испитиваног периода. Истовремено, зимски и пролећни трендови имају највишу тенденцију пораста, док су са друге стране јесењи трендови генерално опадајући. Анализом распона максималних и минималних температура, увидело се да максималне температуре генерално имају нешто већи пораст од минималних, а карактеристике оваквих флуктуација делимично су објашњене корелационом анализом са другим климатским елементима, који могу имати утицај на екстреме. Резултати су показали да високу корелациону повезаност (углавном преко 0,7), односно утицај на екстремне температуре имају инсолација, облачност, падавине и релативна влажност ваздуха. Интересантно је напоменути, да у већини радова који анализирају распоне максималних и минималних температура у појединим регионима, на нивоу континента или глобалном нивоу, указују на негативне трендове распона екстрема, међутим на простору Војводине годишњи распони имају благи позитиван тренд. Коришћењем вишеструке линеарне регресије, уочено је да показатељи атмосферске циркулације, односно NAO и AO индекси, објашњавају прилично висок проценат варијанси средњих и апсолутних максималних и минималних температура, током зимског, пролећног и летњег периода. Истовремено, узрок рапиднијег тренда пораста екстрема током последње декаде XX века, указује како на промене у осцилацијама других климатских елемената, тако и на промене доминације, односно учесталости појаве одређених типова атмосферске циркулације. Резултати у докторској дисертацији показују да деведесете године представљају најтоплију декаду на простору Војводине у оквиру испитиваног периода, што је највероватније повезано и са високим позитивним вредностима NAO индекса током исте декаде, које имају утицај на пораст зимских и пролећних вредности екстремних температура.Tema doktorske disertacije je analiza ekstremenih temperatura vazduha na području Vojvodine (severni deo Srbije), koja se prostire na površini od 21.506 km2. U analizi su korišćene vremenske serije sa deset meteoroloških stanica za vremenski period od 1951. do 2000. godine. Ukupno je analizirano osam parametara ekstremnih temperatura, i to: srednje maksimalne i minimalne, apsolutne maksimalne i minimalne i dani sa ekstremnim temperaturama (ledeni, mrazni, letnji i tropski). Istovremeno, u istraživanje su uključene i vremenske serije raspona srednjih maksimuma i minimuma, kao i raspon srednjih apsolutnih maksimuma i minimuma. Tokom rada analizirani su godišnji, sezonski i mesečni nizovi prethodno navedenih parametara ekstrema. U cilju dobijanja neophodnih rezultata, korišćeno je više metoda, kao što su: Aleksandersonov test, prosta linearna regresija, t-test, Men-Kendalov test, koeficijent korelacije, klaster analiza, analiza rojeva tačaka, histogram i višestruka linearna regresija. Rezultati homogenosti mesečnih i sezonskih vremenskih serija, koji su dobijeni korišćenjem Aleksandersonovog testa, predstavljaju prve rezultate za prostor Vojvodine i pokazuju da je 26% ispitivanih nizova nehomogeno, od kojih je 11% podešeno, odnosno homogenizovano. Analize parametara ekstremnih temperatura vazduha pokazuju tendencije porasta u poslednjih pedeset godina XX veka. Posmatrajući godišnje nizove, javljaju se pozitivni trendovi kod svih parametara (osim za ledene i mrazne dane, gde su trendovi opadajući), međutim, jedino se za srednje minimalne temperature može potvrditi da imaju signifikantan porast tokom ispitivanog perioda. Istovremeno, zimski i prolećni trendovi imaju najvišu tendenciju porasta, dok su sa druge strane jesenji trendovi generalno opadajući. Analizom raspona maksimalnih i minimalnih temperatura, uvidelo se da maksimalne temperature generalno imaju nešto veći porast od minimalnih, a karakteristike ovakvih fluktuacija delimično su objašnjene korelacionom analizom sa drugim klimatskim elementima, koji mogu imati uticaj na ekstreme. Rezultati su pokazali da visoku korelacionu povezanost (uglavnom preko 0,7), odnosno uticaj na ekstremne temperature imaju insolacija, oblačnost, padavine i relativna vlažnost vazduha. Interesantno je napomenuti, da u većini radova koji analiziraju raspone maksimalnih i minimalnih temperatura u pojedinim regionima, na nivou kontinenta ili globalnom nivou, ukazuju na negativne trendove raspona ekstrema, međutim na prostoru Vojvodine godišnji rasponi imaju blagi pozitivan trend. Korišćenjem višestruke linearne regresije, uočeno je da pokazatelji atmosferske cirkulacije, odnosno NAO i AO indeksi, objašnjavaju prilično visok procenat varijansi srednjih i apsolutnih maksimalnih i minimalnih temperatura, tokom zimskog, prolećnog i letnjeg perioda. Istovremeno, uzrok rapidnijeg trenda porasta ekstrema tokom poslednje dekade XX veka, ukazuje kako na promene u oscilacijama drugih klimatskih elemenata, tako i na promene dominacije, odnosno učestalosti pojave određenih tipova atmosferske cirkulacije. Rezultati u doktorskoj disertaciji pokazuju da devedesete godine predstavljaju najtopliju dekadu na prostoru Vojvodine u okviru ispitivanog perioda, što je najverovatnije povezano i sa visokim pozitivnim vrednostima NAO indeksa tokom iste dekade, koje imaju uticaj na porast zimskih i prolećnih vrednosti ekstremnih temperatura.
This doctoral thesis deals with extreme air temperatures in Vojvodina (northern part of Serbia), which covers the area of 21,506 km2. Data series at ten meteorological stations for the period 1951- 2000 were used in the analysis. The following eight parameters of extreme temperatures were analysed: mean maximum and minimum; absolute maximum and minimum; and extreme temperature days (freezing, frosty, summer and tropical). Concurrently, the temporal series of mean maximum and minimum range were included into the research, as well as the range of mean absolute maximum and minimum. Annual, seasonal and monthly ranges of the aforementioned extreme parameters were included in the analysis. Towards obtaining important results, several methods were employed, such as Alexandersson test, simple linear regression, T-test, Mann-Kendall test, cluster analysis, scatterplot, histogram and multiple linear regressions. The results of homogenous monthly and seasonal temporal series obtained by employing Alexandersson test, being the first of the kind for Vojvodina highlighted that there were 26% non-homogenous, out of which 11% adjusted, i.e. homogenised within the analysed series. The analyses of extreme air temperature parameters trends showed increase in the last fifty years of the 20th century. Observation of annual series indicated positive trends for all parameters (except for freezing and frosty days, when the trends decreased). However, only mean minimal temperatures confirmed significant increase in the analysed period. Concurrently, winter and spring trends showed the highest increase, whereas autumn trend showed general decrease. In the course of the analysis of maximum and minimum temperature ranges, it was perceived that maximum temperatures generally showed higher increase compared to minimum, whereas the fluctuation features were partially explained by correlation analysis with other climatic elements, which might have influenced extremes. The results approved that high correlation coefficient (mainly above 0.7), i.e. the impact on extremes was perceived with insolation, cloudiness, precipitation and relative air humidity. Interestingly enough, most of the papers researching the series of maximum and minimum temperatures in certain regions, either continental or global, indicate negative trends in ranges of extremes. On the other hand, in Vojvodina the annual ranges show a moderately positive trend. The multiple linear regression technique brought to the perception that atmospheric circulation indicators, i.e. NAO and AO indices, explained the distinctly high percentage of variances in mean and absolute maximum and minimum temperatures during winter, spring and summer period. Concurrently, the cause of rapid increase in extremes during the 1990s indicated both the changes in oscillations of other climatic elements and changes in domination, i.e. frequency of certain types of atmospheric circulation. The results obtained for the doctoral dissertation indicated that the 1990s were the warmest decade in Vojvodina for the analysed period. Most probably, it was associated with high positive values of NAO index for the period, which affected winter and spring values of extreme temperatures.
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Cieraad, Ellen. "Temperate oceanic treelines : low temperature effects on photosynthesis and growth". Thesis, Durham University, 2011. http://etheses.dur.ac.uk/3401/.
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Altitudinal treelines form where tree growth is limited by low growing season temperatures. However, exactly what aspects of temperature are critical remains unclear. Temperate New Zealand treelines are at a lower altitude than in comparable temperate regions elsewhere. Past studies have shown them to be warmer, and suggested that New Zealand montane trees are not capable of growing at cool temperatures. A detailed study at six sites showed that New Zealand treelines are not anomalously warm, but instead are within the global range of growing season soil temperature at treeline. The thermal environment in summer did not differ between abrupt and gradual treelines, but winters were much colder at the former. The consistency of mean daily minimum air temperature during the growing season at 20 oceanic treelines across the New Zealand archipelago suggests that thermal thresholds to tree growth are better described by minimum temperature, rather than often-used mean temperature. Extreme freezing temperatures are unlikely to control treeline position through dieback of adult trees, as the frost tolerance of trees of all species studied was in excess of the extreme minimum temperatures experienced at the New Zealand treeline. Overall, the proposition that an absence of hardy taxa in New Zealand has resulted in low treelines appears incorrect. In controlled environment experiments, the response of photosynthesis and growth to growing season temperatures differed between the six treeline species. Three species showed evidence of reduced growth activities at low temperature (carbon sink limitation), whereas one species showed reduced growth at low temperature because of limited carbon acquisition (carbon source limitation). Different measures of sink- and source activities provided support for both hypotheses for two other species. These results highlight species-specificity in the temperature response of photosynthesis and growth as well as the complexity in the interpretation of carbon sink and source limitation hypotheses. A combined approach in the field will be required to untangle the processes and thresholds that interact to determine tree growth and treeline positions.
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MELO, Jordanna Sousa de. "Análise de ondas de calor e de frio no Rio Grande do Sul por diferentes métodos". Universidade Federal de Campina Grande, 2017. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1421.
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Com o intuito de identificar e analisar as ondas de calor e de frio que ocorrem no Rio Grande do Sul foi utilizado quatro diferentes procedimentos em 13 estações meteorológicas, espacialmente distribuídas no Estado, entre os anos de 1961 a 2010. Foram consideradas ondas de calor e frio os períodos de cinco ou mais dias consecutivos de anomalias positivas e negativas de temperaturas máximas e mínimas, respectivamente. Calculou-se as médias climatológicas de temperaturas máximas e mínimas anual, estacional e diárias, e em seguida o número de ondas de calor e de frio para cada localidade, anual e sazonal pelos métodos Índice da Organização Meteorológica Mundial (IOMM), Índice Diário (ID), Índice Sazonal (IS) e RClimdex. Ao comparar os métodos verificou-se que o IOMM foi o que detectou o maior número de eventos, os métodos ID e IS praticamente não detectam ondas de calor no verão e de frio no inverno e o RClimdex mostrou-se incapaz de detectar a variabilidade internual de ondas de calor e frio no Rio Grande do Sul. Com relação às configurações espaciais das médias climatológicas das temperaturas do ar máximas e mínimas durante os dias de ondas de calor e frio, respectivamente, assim como os próprios números de dias de ondas calor e frio observou-se um gradiente do litoral para o interior e de sudeste para noroeste. De certa forma estas configurações é uma resposta aos efeitos da continentalidade, latitude e relevo. Quanto à associação da influencia dos eventos El Niño e La Niña no número de ondas de calor e frio observou-se que, em média, ocorrem um número maior de ondas de calor nos anos de El Niño e de frio nos anos de La Niña, entretanto, esta relação não é estatisticamente significativa. Portanto, não é possível afirmar categoricamente que em anos de El Niño tem-se um maior número de ondas de calor e nos de La Niña de frio.
In order to identify and analyze the heat and cold waves that occur in Rio Grande do Sul four different procedures were used in 13 meteorological stations, spatially distributed in the State, between 1961 and 2010. Heat waves were considered and periods of five or more consecutive days of positive and negative anomalies of maximum and minimum temperatures, respectively. The annual, seasonal and daily maximum and minimum climatic averages were calculated, followed by the number of heat and cold waves for each locality, annual and seasonal, using the World Meteorological Organization (IOMM), Daily Index (ID), Seasonal Index (IS) and RClimdex. When comparing the methods it was verified that the IOMM was the one that detected the greatest number of events, the ID and IS methods practically did not detect heat waves in summer and cold in the winter and RClimdex was unable to detect the internal variability of heat and cold waves in Rio Grande do Sul. Regarding the spatial configurations of the climatological means of the maximum and minimum air temperatures during the days of heat and cold waves, respectively, as well as the number of days of heat waves and cold it was observed a gradient of the coast inland and from southeast to northwest. In some ways these settings are a response to the effects of continental, latitude and relief. As for the association of the influence of the El Niño and La Niña events on the number of heat and cold waves, it was observed that, on average, a larger number of heat waves occur in the El Niño and cold years in La Niña, however, this relationship is not statistically significant. Therefore, it is not possible to state categorically that in El Niño years there is a greater number of heat waves and that of La Niña of cold.
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Herculano, Juliana Cardoso. "Comportamento da temperatura obtida por radar meteórico na região tropical durante o Ciclo Solar 23". Universidade Estadual da Paraíba, 2015. http://tede.bc.uepb.edu.br/tede/jspui/handle/tede/2286.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Temperature values around 90 km height were used to investigate a possible relationship between the variations of temperature and solar flux during the solar cycle 23. The temperature data were obtained from the meteoric signal decay time in Cachoeira Paulista (22.7 ° S, 45.0 ° W). To find a possible long-term trend and variations induced by solar activity in annual average temperatures, the data sets were analyzed by multiple linear regression. It was observed that over time the temperature obtained by the two methods show variations. The variation appears to be most pronounced for the temperatures obtained by the gradient method, in which the amplitudes are larger, as well as the respective standard deviations. To analyze the behavior of temperature during solar cycle 23, the seasonally adjusted annual averages, after eliminating the influence of solar activity, they were used and the linear trend was estimated. The average temperature calculated by the model pressure tends to increase about 0.035 K / year when the entire period of observation is considered. However, for the period between maximum and solar minimum the average annual temperature has a tendency of increase of 0.166 K / year. The results show that the annual average temperature of seasonally adjusted after removal of the effects due to solar flux obtained by the gradient method would be higher than the original period for the solar decline. It is noted that the annual temperature seasonally adjusted virtually no change when t he time trend is removed, which may indicate that the annual temperature deseasonalized obtained by the gradient method are strongly affected by the solar flux.
Valores da temperatura em torno de 90 km de altura foram usados para investigar uma possível relação entre as variações da temperatura e o fluxo solar durante o ciclo solar 23. Os dados de temperatura foram obtidos a partir do tempo de decaimento do sinal meteórico em Cachoeira Paulista (22,7°S, 45,0°O). Para encontrar uma possível tendência de longo prazo e variações induzidas pela atividade solar nas médias anuais das temperaturas, as séries de dados foram submetidas à análise de regressão linear múltipla. Observou-se que ao longo do tempo as temperaturas obtidas através dos 2 métodos apresentam variações. A variação mostra-se mais notória para as temperaturas obtidas pelo método do gradiente, em que as amplitudes são maiores, assim como os respectivos desvios padrão. Para analisar o comportamento da temperatura durante o ciclo solar 23, as médias anuais dessazonalizadas, após a eliminação da influência da atividade solar, foram utilizadas e a tendência linear foi estimada. A temperatura média calculada pelo modelo de pressão tende a aumentar cerca de 0,035 K/ano quando todo o período de observação é considerado. Contudo, para o período compreendido entre máximo e o mínimo solar a temperatura média anual apresenta uma tendência de aumento de 0,166 K/ano. Os resultados mostram que as médias anuais das temperaturas dessazonalizadas após a remoção dos efeitos devido ao fluxo solar, obtidas pelo método do gradiente, seriam mais elevadas do que as originais para o período de declínio solar. Verifica-se que as temperaturas anuais dessazonalizadas praticamente não mudam quando a tendência temporal é removida, o que pode indicar que as temperaturas anuais dessazonalizadas obtidas pelo método do gradiente são fortemente afetadas pelo fluxo solar.
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Camillo, Luciano Mendes. "Estudo do ponto invariante com a temperatura (\"Zero Temperature Coefficient\") em transistores SOI Mosfet fabricados com tecnologia ultra-submicrométrica". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-05042011-155808/.
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Neste trabalho é apresentado um estudo do ponto ZTC (Zero Temperature Coefficient) em dispositivos SOI MOSFETs, funcionando em modo parcialmente (PD-SOI) e totalmente (FD-SOI) depletados. O estudo é realizado a partir de um modelo analítico simples, proposto para determinação da tensão de polarização da porta do transistor no ponto ZTC (VZTC), através dos modelos de primeira ordem das características da corrente de dreno (IDS) em função da tensão aplicada a porta (VGF) do transistor, considerando as regiões de operação linear e de saturação. Para a validação do modelo, os resultados obtidos são confrontados com dados experimentais, e foi obtido um bom ajuste dos valores, apesar das simplificações adotadas para o modelo proposto. Foi realizada uma análise para estudar o impacto no valor de VZTC com a variação no valor de parâmetros de referência, como a concentração de portadores (Naf) e a espessura do óxido de porta (toxf). O erro máximo observado em VZTC, impondo a variação nos parâmetros Naf e toxf, para os dispositivos PD é de 3,1% e 4,6% na região linear, respectivamente; e 3,5% e 7,2% na região de saturação, respectivamente. Para os dispositivos FD o erro máximo observado, devido a variação nos parâmetros Naf e toxf, foi de 11% e 10% operando no regime linear, respectivamente e 5,3% e 8,4% no regime de saturação, respectivamente. Através do modelo proposto foi realizado o estudo da estabilidade do ponto ZTC em função da variação da degradação da mobilidade com a temperatura (fator c), comprimento de canal (L) e a tensão de dreno (VDS) para os dispositivos supracitados. A analise da influência do fator c em VZTC mostrou-se mais importante nos dispositivos parcialmente depletados (PD). A tensão VZTC, para os dispositivos nMOS, apresentou um menor valor operando na região de saturação, e torna-se mais pronunciada essa diferença para dispositivos com menor comprimento de canal, para ambos os tipos de dispositivos. Observando a variação de VZTC com VDS, nota-se uma diminuição no valor de VZTC para altos valores de VDS, para os dois tipos de dispositivos estudados, n e pMOS. Os resultados do modelo proposto foram avaliados com dados experimentais de outras tecnologias SOI MOSFET. Também foi obtido um bom ajuste com os valores para as tecnologias GC-SOI e GC-GAA SOI, operando em regime linear e saturação.This paper presents a study of ZTC point (\"Zero Temperature Coefficient) in SOI MOSFETs devices, partially (PD-SOI) and fully (FD-SOI) depleted mode. The study is performed from a simple analytical model proposed for the determination of the gate bias voltage at ZTC point (VZTC) using the first-order models of the drain current (IDS) characteristics as a function of the gate voltage (VGF), operating in the linear and saturation regimes. To validate the model proposed results were compared with experimental data, and the analytical predictions are in very close agreement with experimental results in spite of the simplification used for the VZTC model proposed. Analysis was performed to study the impact on the VZTC value with the change in the parameters used as reference, such as Naf and toxf. The maximum error observed for the PD devices is 3.1% and 4.6% in the linear region and 3.5% and 7.2% in the saturation region, respectively. For FD devices the maximum error observed was 11% and 10% operating in the linear and 5.3% and 8.4% in the saturation regime. In order to verify the stability of the ZTC point as a function of the mobility degradation (c), channel length (L) and drain voltage (VDS), the proposed model was applied to the devices mentioned above. The VZTC changes in the temperature range investigated showed a temperature mobility degradation dependence and are more pronounced in PD devices. The VZTC voltage for nMOS devices presented a lower value operating in the saturation region than in the linear region, and this difference becomes more pronounced to devices with smaller channel length for both devices, n and pMOS. Analyzing the VZTC variation with drain voltage (VDS), showed a decrease in VZTC value for higher VDS, for both studied devices. The model proposed results were evaluated using experimental data from other SOI MOSFET technologies. And also we have obtained for the GC SOI and GC-GAA-SOI technologies a very close agreement, operating in both regions, linear and saturation.
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Wu, Xu. "Development of high temperature PEMFC and high temperature PEMWE". Thesis, University of Newcastle Upon Tyne, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555981.
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Polymer electrolyte membrane fuel cells (PEMFC) and polymer electrolyte membrane water electrolysers (PEMWE) are promising electrochemical energy conversion devices. This thesis describes research carried out on high temperature PEMFC and PEMWE. High temperature (> 100 QC) operation is one of the most topical research trends of PEMFC and PEMWE, because of the operational and kinetic advantages it can provide. In this research, an anhydrous solid electrolyte, Sb-doped SnP207 was prepared and characterized. The synthesis parameters, microstructure, and conductivity of Sb-doped SnP207 were studied. The Sbo.2Sno.gP207 exhibited good conductivity (0.01-0.l S cm") in the temperature range 100-300 QC, and was initially applied in PEMFCs at intermediate temperatures (200-300 QC). Research into development of polymer acid complex membranes for high temperature PEMFCs, including phosphoric acid and sulphuric acid - doped polybenzimidazole membranes, was also carried out. The maximum power density of high temperature PEMFCs achieved was 0.5-0.7 W cm-2. For high temperature PEMWEs, firstly, Sn and Ir stabilized RU02 nanopartic1es were synthesized and studied as catalysts for the oxygen evolution reaction (OER). Iro.7RUo.302 nanopartic1es were found to be the most stable and active catalysts for OER. Research to develop a catalysts coated membrane (CCM) method for PEMWE membrane electrode assembly (MEA) fabrication is described. A high performance PEMWE was developed by studying fabrication parameters of the CCM method and optimizing electrode compositions of MEAs. High temperature (> 1 00 QC) PEMWE was eventually realized, using a perfluorinated silica composite membrane. The voltage achieved at 1 A cm-2 current density of PEMWE was 1.51 V at 140 QC and 4 bar pressure. The final part of this thesis describes work on catalyst support materials, which are essential for reducing noble metal loading in PEMWEs. Although the costs of PEMFCs and PEMWEs are still high, which is due to noble metal catalysts and expensive membranes, high temperature operation (> 100 QC) can help both devices be more competitive for energy conversion applications.
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Moore, Jay Gershon. "Temperature measurement and transition detection using temperature-sensitive paint". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10988.
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Denis, Paul. "Muscle temperature transients and post-exercise esophageal temperature elevation". Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6309.
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The primary purpose of this research was to study esophageal temperature elevation and quadriceps and triceps intra-muscular temperature gradients during resting recovery from exercise. Eight physically active male participants and 24 +/- 4 years of age, rested in a buttocks supported upright posture for a 50 +/- 12.5 minutes in ambient conditions of 24.7 +/- 1.17°C and 24 +/- 4.6% relative humidity. Participants then performed a steady state cycle ergometry exercise at 70% VO2 max, until they reached until heat produced by exercise above metabolic rate accumulated to 1000 kJ. This was followed by 120 minutes of resting recovery. Active intra-muscular temperature was measured in the vastus medialis at four depths, with the tip of the probe being at 10 mm from the femur and deep femoral artery and the others sensor at 15, 30 and 45 mm from the tip of the probe. Pre-exercise resting esophageal temperature and quadriceps intra-muscular temperatures were 36.95 +/- 0.22°C (Tes), 36.31 +/- 0.39°C (Tmuq1), 36.10 +/- 0.50°C (Tmuq2), 35.75 +/- 0.84°C (Tmuq3) and 35.33 +/- 0.88°C (Tmuq4) respectively. Exercise resulted in a 0.94 +/- 0.32°C increase in esophageal temperature above pre-exercise resting values. End of exercise intra-muscular quadriceps temperatures were 38.81 +/- 0.42°C (T muq1), 38.61 +/- 0.60°C (Tmuq2), 38.13 +/- 0.75°C (Tmuq3) and 37.71 +/- 0.96°C (Tmuq4 ). Esophageal temperature remained significantly elevated from pre-exercise resting values for 10 minutes following exercise. These results indicate that post-exercise esophageal temperature elevation, following cycle ergometry exercise, is not dependent on a temperature gradient between esophageal temperature and deep muscle temperature from the previously active muscle. Further, a prolonged and sustained post-exercise esophageal temperature was not demonstrated following this cycle ergometry exercise.
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Cigas, Saulius. "Standaus apkrovimo ciklinių deformavimo parametrų nustatymas korozijai ir karščiui atsparaus plieno suvirintųjų sujungimų medžiagoms". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050613_152519-67955.
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Cigas S. Determination of low cycle straining parameters for weld metals of stainless steel: Master thesis of mechanical engineer / research advisor associate professor dr. R. Šniuolis; Šiauliai University, Technological Faculty, Mechanical Engineering Department.–Šiauliai, 2005.-68p.
Strain and stress change during the exploitation depend on the type of material (hardening, softening or cyclically stabile), that is chosen for the constructions in low cycle loading. If we know the type of the material, we can determine the possibility of its application in concrete exploitation conditions. Real working conditions of the most constructions are close to loading with limited strain (hard straining), because elastic and plastic deformation is met in the zones of crack and stress concentration, that are surrounded with elastically deformed material.
Analytical dependences between stress and strain in any semicycle k are expressed by summarized low cyclic stress strain curve. The low cycle loading curves parameters A, and are used for the computation of this curve. These parameters were obtained from the low cycle straining results. The other possible ways for the determination of parameters A, , and statistical methods for the evaluation of these parameters for weld metals of stainless steel at room temperature are presented in this work.
Cyclic characteristics A, and were determined by methods shown in this work. It was determined, that the values of cyclic strain and... [to full text]
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Pavanelli, Caio Augusto Malvestio [UNESP]. "Viabilidade técnica e econômica da larvicultura do camarão-da-amazônia, Macrobrachium amazonicum, em diferentes temperaturas". Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/86680.
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Universidade Estadual Paulista (UNESP)
Avaliou-se o efeito da temperatura da água no cultivo de larvas de Macrobrachium amazonicum. O delineamento experimental foi inteiramente casualizado, com quatro tratamentos (temperaturas) e quatro repetições. Foram realizados dois experimentos. No primeiro, a temperatura foi avaliada em um amplo espectro (20, 25, 30 e 35°C). No segundo, os tratamentos testados foram 26, 28, 30 e 32°C, definidos de acordo com os melhores resultados obtidos no experimento 1. Cada experimento foi desenvolvido em 16 tanques de larvicultura de 63 L contendo água na salinidade 12 e providos de filtro biológico, aeração e aquecimento controlado por termostatos digitais. A densidade de estocagem foi de 100 e 85 larvas/L nos experimentos 1 e 2, respectivamente. O desenvolvimento larval foi mais lento no cultivo em 20°C, seguido pelos cultivos em 25 e 26°C. Nessas temperaturas, a metamorfose não ocorreu ou foi inexpressiva no tempo de cultivo adotado (17 dias). A temperatura de 35°C apresentou mortalidade total das larvas no 13º dia de cultivo. Conclui-se que a larvicultura de M. amazonicum pode ser realizada em temperaturas que variam de 25 a 32°C. Porém, o cultivo em 30°C apresentou os melhores resultados, maximizando a produção de pós-larvas e minimizando o tempo de cultivo
We evaluated the effect of water temperature in the culture of larvae of Macrobrachium amazonicum. The experimental design was completely randomized with four treatments (temperatures) and four replications. Two experiments were conducted. At first, the temperature was evaluated in a broad spectrum (20, 25, 30 and 35°C). In the second, the treatments were 26, 28, 30 and 32°C, defined in accordance with best results obtained in Experiment 1. Each experiment was carried out in 16 hatchery tanks containing 63 L of water salinity at 12 and with a biological filter, aeration and heating controlled by digital thermostats. Stocking density was 100 and 85 larvae/L in experiments 1 and 2, respectively. Larval development was slower in culture at 20°C, followed by cultivation at 25 and 26 ° C. At these temperatures, the transformation did not occur or was negligible in the time of culture adopted (17 days). The temperature of 35°C showed a total mortality of larvae on day 13 of culture. It is concluded that the hatchery M. amazonicum can be performed at temperatures ranging from 25 to 32°C. However, culture at 30°C showed the best results, maximizing the production of post-larvae and minimizing the time of culture
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Terra, Maisa de Oliveira. "Efeitos de Temperatura Finita nas Versões Integrável e Não-Integrável do Modelo de Lipkin-Meshkov-Glick". Universidade de São Paulo, 1996. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-28022014-165420/.
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No presente trabalho usamos técnicas de física de muitos corpos não relativísticas para generalizar o limite clássico de sistemas quânticos de forma a incorporar misturas estatísticas. Efeitos de temperatura finita são estudados em detalhe no contexto das versões integrável e não integrável do modelo de Lipkin-Meshkov-Glick. Os dois aspectos mais notáveis de nossa análise são: o surgimento de um novo grau de liberdade essencialmente conectado a efeitos térmicos, ocorrendo a temperaturas suficientemente altas e uma caracterização quantitativa do efeito da temperatura no volume caótico do sistema. Mostra-se que os efeitos térmicos sistematicamente compensam a parte de interação da dinâmica. Este é o caso tanto no contexto da termodinâmica quanto da dinâmica a temperatura finita e acreditamos que seja verdadeiro em geral.In the present work we use techniques of nonrelativistic many body physics to generalize the classic limit of quantum systems in such a way as to incorporate statistical mixtures. Finite temperature effects are studied in detail in the context of the integrable and nonintegrable versions of the Lipkin-Meshkov-Glick Model. The most remarkable features of our analysis is twofold: the appearance of a new degree of freedom essentially connected to thermal effects i.e., for high enough temperatures and a quantitative characterization of the temperature on the chaotic volume of the system. Thermal effects can be shown to consistently counterbalance the interaction part of the dynamics. This is the case both in the context of thermodynamics and of the thermal dynamics of the system and we believe it to be true in general.
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Jacobi, Christoph, e Dierk Kürschner. "Mesopause region temperatures and plasma scale height estimations from VHF meteor radar and LF absolute reflection height measurements at Collm". Universitätsbibliothek Leipzig, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-219583.
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The change of ionospheric absolute reflection heights h of low-frequency (LF) radio waves at oblique incidence in the course of the day is measured at Collm Observatory (51.3°N, 13.0°E) using 1.8 kHz sideband phase comparisons between the sky-wave and the ground wave of a commercial 177 kHz transmitter (Zehlendorf, reflection point 52.1°N, 13.2°E). Plasma scale height estimates H are calculated from the decrease/increase of h in the morning/evening. The day-to-day variations of H are compared with those of daily mean temperatures at 90 km, measured with a VHF meteor radar (36.2 MHz) at Collm utilising the amplitude decay of meteor reflections. A good qualitative correspondence is found between the two data sets. Since mesospheric long-period temperature variations are generally accepted to be the signature of atmospheric planetary waves, this shows that LF reflection height measurements can be used for monitoring the dynamics of the upper middle atmosphere.
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Feller, Christa. "Avaliação da difusão térmica na dentina e cemento radicular quando da utilização do Endox ® in vitro". Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/23/23145/tde-04082006-093805/.
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O presente estudo teve por objetivo avaliar a difusão da temperatura desenvolvida na parede dentinária de raízes pelo uso de um aparelho eletrônico, recentemente lançado no mercado, denominado ENDOX® . É um sistema de tratamento endodôntico digital de eletrofulguração e que tem duas finalidades:- a) localizador apical por impedância, marcando o comprimento de trabalho no terço apical assinala quanto se está próximo da constrição apical; e, b) desinfecção do canal radicular por meio de corrente de alta freqüência (600 kHz), vaporizando o eventual conteúdo do canal, devido a fulguração eletrônica de alta intensidade e freqüência, em menos de um décimo de segundo. Foram utilizados 40 caninos escolhidos pela sua anatomia, ápices afilados e arredondados. Cada grupo de 20 dentes foi subdividido em dois variando a intensidade da radiofreqüência aplicada nos diversos pontos da raiz: terços cervical, médio, apical e ápice. A freqüência aplicada foi a recomendada pelo fabricante, 600 kHz por 1/10 de segundo chamada de padrão e com um aumento de intensidade de 20%, 720 kHz. Os resultados obtidos foram submetidos a tratamento estatístico com nível de significância de 5%, utilizando análise de variância (ANOVA) e teste de Tukey. A diferença de temperatura entre os tipos de raízes é de aproximadamente 1ºC quando se compara as afiladas com as arredondadas. Entre os terços radiculares há um aumento progressivo da temperatura de cervical para o ápice. As médias da diferença de temperatura em ºC foram avaliados de acordo com as interações entre formato, terços radiculares e intensidade de radiofreqüência. Nas condições do experimento verificou-se que a diferença entre as temperaturas iniciais e finais não gerou calor excessivo na superfície radicular, não havendo diferença estatística significante entre raízes arredondadas e afiladas. Há uma progressão das temperaturas médias do terço cervical até o ápice sendo significantes independentemente do formato das raízes e da radiofreqüência. Houve diferença estatística significante observada nas interações de terços, formato radicular e diferente intensidade de radiofreqüência, entre ápice e terço médio. Nas raízes afiladas com aumento de radiofreqüência há diferença entre todos os seus terços. Concluiu-se que, nas limitações do experimento in vitro, o aumento de temperatura variou em média 10ºC, independente do formato radicular e intensidade de freqüência, portanto dentro dos limites tolerados para a reparação óssea. É recomendável utilizar a intensidade de freqüência padrão para melhor controle da temperatura em níveis baixos.The present study aimed to evaluate the temperature diffusion on the dentin wall of root canals, using an electronic device recently placed in the market denominated ENDOX®. A digital electro fulguration system for endodontic therapy designed to reach two purposes:- a) defining the correct endodontic work length through an impedance apical locator; and, b) promote root canal disinfection, vaporizing root canal content in less then a decimal of a second by electronic fulguration of high intensity and frequency current (600 kHz). This study comprised 20 maxillary canines and 20 mandible canines, chosen for their apical taper or rounded anatomic characteristic. Each group of 20 teeth was then subdivided in two, varying the radiofrequency intensity applied on the diverse root points. Four different root areas were established for radiofrequency application: cervical third, medium third, apical third and the apex itself. Following the manufactures recommendation, the frequency applied, was the standard one, that is, 600 kHz for 1/10 of a second and with an increase of 20%, 720 kHz. The results were submitted to statistical treatment at 5%significance, variance analysis (ANOVA) and Tukey test. When comparing taper to rounded root types, the temperature difference between them was approximately 1°C. As to the radicular root thirds, progressive temperature increase was observed from cervical area to the apex. The average differences of temperature in °C were evaluated considering shape, radicular thirds, and radiofrequency intensity. Under the experiment condition, it was observed that the difference between initial and final temperature did not generate excessive heat on the root surface and also revealed no significant statistical difference between taper or round roots. There is a progressive rise of average temperatures from the cervical to the apical third that is significant, independently from root shape or radiofrequency. Significant statistical findings were noted involving the interaction of the root thirds, root shape and different radiofrequency intensity between the apex and the roots medium third area. An increase of radiofrequency on the taper root shapes caused differences in all its roots areas. It was concluded that, within the limitations of this in vitro experiment, the temperature rise varied in average 10ºC, independently of root shape and frequency intensity therefore, under tolerable limits for bone repair. The standard frequency intensity is recommended in order to control temperature at lower levels.
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Carriel, Orlando Aparecido. "Efeito das variações de temperatura relacionadas às mudanças climáticas globais sobre as respostas fotossintéticas de macrófitas aquáticas de ecossistemas lóticos tropicais". Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153323.
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Ao longo do tempo a temperatura média global teve grandes variações, devido principalmente à fenômenos naturais. Porém, a partir da revolução industrial diversas atividades antrópicas vêm causando uma significativa alteração na atmosfera terrestre, de modo que diversos gases, especialmente CO2, têm aumentado a sua concentração atmosférica e, como consequência, produzido elevação na temperatura do planeta. Essas mudanças climáticas, particularmente o aquecimento global, podem afetar os organismos de ambientes aquáticos continentais, incluindo os produtores primários (p.ex., macrófitas). Utilizando o método de evolução do oxigênio dissolvido (técnica dos frascos claros e escuros), a técnica da fluorescência da clorofila a e a técnica da concentração de clorofila a, avaliou-se o efeito do aumento de temperatura potencialmente produzido pelo aquecimento global, previsto em dois cenários futuros do Painel Intergovernamental de Mudanças Climáticas (IPCC), RCP 4.5 e RCP 8.5, sobre as respostas fotossintéticas de macrófitas aquáticas de ecossistemas lóticos tropicais. As temperaturas de controle foram determinadas, para as estações de inverno e verão, a partir da temperatura média de riachos da região onde as amostras de macrófitas foram coletadas e as temperaturas experimentais calculadas adicionando-se os aumentos previstos pelos cenários testados do IPCC. A resposta à simulação dos cenários do IPCC ocorreu de modo espécie-específico. Sendo que para a maioria das espécies investigadas não foram registrados efeitos negativos ou significativos sobre a fotossíntese, com algumas espécies demonstrando inclusive um aumento na produtividade primaria nos cenários experimentais do IPCC em relação ao controle.
Over time, the average global temperature had great variations, mainly due to natural phenomena. However, since the industrial revolution several anthropic activities have caused a significant change in the Earth's atmosphere, so that various gases, especially CO2, have increased their atmospheric concentration and, consequently, produced an increase in the planet's temperature. These climatic changes, particularly global warming, can affect organisms in continental aquatic environments, including primary producers (eg, macrophytes). Using the method of evolution of dissolved oxygen (light and dark jars technique), chlorophyll a fluorescence technique and chlorophyll a concentration technique, the effect of the temperature increase potentially produced by global warming, predicted in two scenarios future of the Intergovernmental Panel on Climate Change (IPCC), RCP 4.5 and RCP 8.5, on the photosynthetic responses of aquatic macrophytes from tropical lotic ecosystems. Control temperatures were determined for the winter and summer seasons from the average stream temperature of the region where the macrophyte samples were collected and the experimental temperatures calculated by adding the predicted increases in the IPCC tested scenarios. The response to the simulation of the IPCC scenarios occurred in a species-specific manner. For most of the species investigated, there were no negative or significant effects on photosynthesis, with some species even showing an increase in primary productivity in the experimental scenarios of the IPCC in relation to the control.
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Stübner, Konstanze. "Low-temperature thermochronology". Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2009. http://nbn-resolving.de/urn:nbn:de:bsz:105-6628348.
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Die Spaltspuren-Datierung als wesentliche Methode aus dem Bereich der Niedrigtemperatur-Thermochronologie basiert auf der Zählung und Messung geätzter Spuren unter dem Mikroskop. Für eine akkurate Altersbestimmung ist daher das Verständnis der Ätzung von größter Bedeutung. Ein atomistisches Modell und eine Monte-Carlo Computersimulation erklären Ätzgruben-Formen und deren Größenwachstum. Thermochronologie wird in zwei Fallstudien angewendet: eine umfassende Studie über die tektonische Entwicklung Zentralamerikas seit dem Paläozoikum zeigt, wie Geo- und Thermochronologie, Strukturgeologie und Petrologie zusammenarbeiten können, um >400 Ma einer komplexen tektonischen Geschichte zu enträtseln. Eine thermochronologische Studie im Pamir, Tadschikistan betont vor allem die Möglichkeiten, die sich aus der Anwendung der Thermochronologie auf dem Gebiet der Geomorphologie und Neotektonik eröffnen.
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Patterson, Peter A. "High temperature cyclones". Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75974.
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Gas-solids separation was studied in a 102 mm diameter conventional cyclone operated with air heated to temperatures between 300 K and 2 000 K. Cyclone pressure drops, fractional and overall collection efficiencies were measured as functions of temperature, gas throughput, dust loading and cyclone geometry. Alumina and silica of 100% less than 44 $ mu$m mass median diameter were used as test dusts. Inlet velocities ranged from 3 to 42 m/s and inlet dust loadings were between 0.3 and 235 g/m$ sp3$.Empirical models were derived to correlate the experimental results for the cyclone collection efficiency, pressure drop, tangential velocity and 50% cut size. The performance of the cyclones at very high temperatures was not significantly different from the room temperature behavior, provided that the effect of temperature on particle, gas and flow properties was adequately treated.
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Taylor, Diana Jacqueline Falcon. "Temperature insensitive microemulsions". Thesis, University of Hull, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310404.
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Rumbold, Steven T. "Stratospheric temperature trends". Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501338.
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The stratospheric temperature trend has only been measurable on a global scale since the late 1970's during the satellite era. In the global annual mean, the stratosphere demonstrates a cooling over this time. This cooling is much greater than the warming at the Earth's surface and is therefore an important signature of climate change. Although models agree with the observations in terms of the sign of the temperature trend, there is inconsistency in the magnitude. In addition to the overall trend, the stratospheric temperatures demonstrate many scales of variability. One possible cause of this variability is the change in flux from the Sun over the 11-year solar cycle. By use of realistic solar cycle flux perturbations, the solar maximum minus minimum annual mean result displays a peak response at the stratopause with a magnitude of 1.6 K, an equatorial middle stratosphere minimum and a second peak in the lower stratosphere. This is in agreement with a previous multiple regression analysis of the ERA-40 temperatures The result of this study appears different to a multiple regression of the solar cycle in satellite observations alone; however, when the results are degraded to the resolution of the satellite channels, the results are more similar and thus the broad weighting functions axe a large contributor to the discrepancy. The same modelling techniques are used to evaluate the temperature change associated with anthropogenic-induced carbon dioxide and ozone changes. A first order time-varying response is established and then weighted to each of the satellite channels. When compared to the observations, it is found that the addition of the solar cycle reduces the discrepancy compared to neglecting the solar response in most satellite channels. Additionally, the associated radiative forcings across the tropopause are also calculated.
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Firth, S. "Low temperature photochemistry". Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378979.
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Craig, Jean Vivienne. "Measuring children's temperature". Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439593.
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Black, Victoria J. "High temperature supercapacitors". Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12490.
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The scientific objective of this research program was to determine the feasibility of manufacturing an ionic liquid-based supercapacitor that could operate at temperatures up to 220 °C. A secondary objective was to determine the compatibility of ionic liquids with other cell components (e.g. current collectors) at high temperature and, if required, consider means of mitigating any problems. The industrial motivation for the present work was to develop a supercapacitor capable of working in the harsh environment of deep offshore boreholes. If successful, this technology would allow down-hole telemetry under conditions of mechanical vibration and high temperature. The obstacles, however, were many. All supercapacitor components had to be stable against thermal decomposition up to T ≥ 220 °C. Volatile components had to be eliminated. If possible, the finished device should be able to withstand voltages greater than 4 V, in order to maximise the amount of stored energy. The internal resistance should be as low as possible. Side reactions, particularly faradaic reactions, should be eliminated or suppressed. All liquid components should be gelled to minimise leakage in the event of cell damage. Finally, any emergent problems should be identified.
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Previdello, Bruno Alarcon Fernandes. "Oxidação de etanol em temperaturas elevadas". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-11032010-101652/.
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Atualmente existe um grande interesse mundial na substituição de produtos obtidos a partir do petróleo para o desenvolvimento de novos materiais a partir de fontes renováveis. Neste contexto, o estudo de células a combustível (Fuel Cell) tem recebido destaque em pesquisas tecnológicas. O uso de células a combustível como membrana trocadora de prótons (PEMFC) é uma das mais promissoras. A célula a combustível é um sistema eletroquímico que transforma diretamente energia química a partir de um combustível (hidrogênio, gás natural, etanol, etc.) em energia elétrica. No entanto, as células a combustível do tipo PEM são usualmente alimentadas com hidrogênio como combustível, o qual apresenta dificuldades devido a sua produção, armazenamento e transporte. Como uma alternativa para o hidrogênio, a oxidação eletroquímica direta de moléculas orgânicas pequenas, como o etanol, tem sido amplamente investigada. Além do mais, o uso de etanol diretamente aplicado em células a combustível mostra algumas vantagens, por apresentarem na forma liquida e ter densidade de energia teórica elevada (8,0 kWh Kg-1). No entanto, o maior problema de células a combustível de etanol resulta na produção de produtos paralelos, como o ácido acético e acetaldeído como produto final, além do CO2 que é o produto da oxidação completa do álcool, diminuindo a eficiência do processo. O objetivo deste trabalho é estudar a eletro-oxidação de etanol em Pt policristalina em solução ácida usando técnica como voltametria cíclica e cronoamperometria como técnicas eletroquímicas no intervalo de temperatura de 25 à 180°C. Particularmente, o desempenho de ligas catalisadoras de Pt com outros metais (PtRh, Pt3Ru2, e PtSn) foram comparados. A dependência da temperatura com a corrente para a eletro-oxidação de etanol a partir de curvas cronoamperométricas para a Pt policristalina e ligas catalisadoras foram medidas em potencial constante de 500 e 650 mV vs EDH. Os resultados mostraram que para a liga PtSn no potencial de 500 mV a corrente em 180°C é de aproximadamente trezentas vezes maior do que a 25°C e sete vezes maior que os outros materiais à 180°C, para a reação de oxidação. A partir dos valores das correntes de cronoamperométricas foi calculado a energia de ativação aparente (Ea) para a Pt policristalina e as ligas PtRh, Pt3Ru2 e PtSn.In the present days there is a great world interest in substituting products obtained from petroleum applied in energy conversion by developing new materials from renewable resources. In this context, the study of fuel cells has received growing attention in technology researches. The use of fuel cells such as proton exchange membrane fuel cells (PEMFC) have been shown to be one of the most promising devices. Fuel cell is an electrochemical system, which transforms directly chemical energy of a fuel (hydrogen, natural gas, ethanol, etc.) into electric energy. However, the fuel cell is based on hydrogen, which presents difficulties concerning its production, storage and transportation. As an alternative to hydrogen, the direct electrochemical oxidation of small organic molecules, such as ethanol, has been investigated widely. Moreover, the use of ethanol in a direct alcohol fuel cell shows some advantages, it is liquid and their theoretical mass energy density is rather high (8,0 kWh Kg-1). However, the major problem of direct ethanol fuel cell results in acetic acid and acetaldehyde as an -end-product?, which competes with complete oxidation of the alcohol to CO2, decreasing the efficiency of the latter process. Based on these observations, the aim of this work is the study of the electro-oxidation of ethanol on polycrystalline Pt in acid solution using cyclic voltammetry and chronoamperometry as techniques, at temperatures ranging from 25 to 180°C. Particularly, the performances of platinum based electro-catalysts with other metals (PtRh, Pt3Ru2 and PtSn) were compared. The temperature dependence of the current for ethanol electro-oxidation from chronoamperometric curves for polycrystalline Pt and catalysts alloys were measured at constant potentials of 500 and 650 mV. The results showed that for the PtSn catalyst at 500 mV and 180°C the current is approximately three hundred times higher than that at 25°C and seven times higher than the other materials investigated at 180°C, for the same oxidation reaction. The apparent activation energies (Ea) values were experimentally determined through the current values from chronoamperometric curves for polycrystalline Pt and PtRh, Pt3Ru2 and PtSn catalysts.
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Lima, Ana Rebeca Castro. "Investigação sobre o efeito da temperatura na produção de calor em cabras da raça Saanen e Anglo-Nubiana /". Jaboticabal, 2017. http://hdl.handle.net/11449/151782.
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Orientador: Kléber Tomás de ResendeCoorientador: Marcia Helena Machado da Rocha Fernandes
Banca: Luiz Gustavo Ribeiro Pereira
Banca: Edney Pereira da Silva
Banca: Heraldo Cesar Gonçalves
Banca: Renato Luís Furlan
Resumo: Objetivou-se com o presente estudo determinar a influência da temperatura ambiente sobre o metabolismo basal e a partição de energia em cabras Saanen e Anglo-Nubiana. Dois experimentos foram conduzidos utilizando-se seis cabras da raça Saanen e seis cabras da raça Anglo-Nubiana, em mantença, a partir da técnica da calorimetria indireta de circuito aberto, com máscaras faciais. No experimento 1, após um período de alimentação de 3 dias, os animais foram submetidos a jejum e a medição das trocas gasosas foi realizada durante 30 min a 0, 12, 20, 36, 44, 60 e 68 horas após jejum. A produção de metano foi igual a zero após 31 horas de jejum para cabras Saanen e 40 horas para as Anglo-Nubiana. Os resultados sugerem que o período ideal para medir a produção de calor em jejum (PCJ) deve ser entre 40 horas e 60 horas de jejum para cabras em mantença. No experimento 2, as cabras foram submetidas a três diferentes temperaturas: 10 ºC ± 0,23; 20 ºC ±0,41 e 35 ºC ±1,05. Após um período de alimentação de 4 dias, os animais foram submetidos a jejum por 60 horas e a medição da troca gasosa foi realizada a partir da metodologia da calorimetria indireta utilizando as máscaras faciais durante 30 min em cada animal aleatoriamente. Para ambas as raças, houve uma diminuição linear na ingestão de matéria seca (MS) e matéria orgânica (MO; P<0,10) a medida que a temperatura aumentou de 10 para 35ºC. A digestibilidade aparente da MS, da MO, da proteína bruta e da fibra em detergente neutro apresentara... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The aim of this study was to determine the influence of the ambient temperature on the basal metabolism and the energy partition in Saanen and Anglo-Nubian goats. Two experiments were carried out using six Saanen goats and six Anglo-Nubian goats, in maintenance, using the indirect calorimetry technique with open-circuit facemask respirometry. In experiment 1, after a three-day feed period, the animals were fasted and gas exchange measurements were performed for 30 min at 0, 12, 20, 36, 44, 60 and 68 hours after fasting. Methane production approached zero after 31 hours of fasting for Saanen goats and 40 hours for Anglo-Nubian goats. The results suggest that the period for measuring fasting heat production (FHP) should be between 40 hours and 60 hours of fasting for maintenance goats. In experiment 2, goats were submitted to three different temperatures: 10 ºC ± 0.23, 20 ºC ± 0.41 and at 35 ºC ± 1.05. After a feeding period of four days, goats were fasted for 60 hours and gas exchange measurement was performed for 30 min in each animal randomly. For both breeds, dry matter (DM) and organic matter intake (MO; P <0.10) decrease linearly as the temperature increased from 10 to 35ºC. The apparent digestibility of DM, OM, crude protein and neutral detergent fiber presented quadratic behavior (P <0.10), with the lowest values at 20ºC. At 35ºC, the crude protein digestibility of Anglo-Nubian goats was higher than that of Saanen goats. Respiratory rate (RR) and respiratory volume increased with increasing ambient temperature. At 35ºC, both RR and respiratory volume of Saanen goats were higher than that of Anglo-Nubian goats. The diet metabolizability and metabolizable energy of Saanen goats, at 35ºC, were lower than those of the Anglo-Nubian goats. In both breeds, for each 1ºC of variation below 20ºC there w... (Complete abstract click electronic access below)
Doutor
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Martyniuk, Mariusz. "Low-temperature micro-opto-electro-mechanical technologies for temperature sensitive substrates". University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0042.
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[Truncated abstract] The salient feature of next generation infrared (IR) on-chip integrated sensors is likely to be sensitivity in a narrow wavelength band that is tuneable over a selected range of the IR spectrum. It is proposed that this can be achieved by the integration of present-day HgCdTe IR detectors with thin-film based microelectro- mechanical systems (MEMS) optical mirror technology. Narrow-band sensitivity is obtained by optical resonance phenomena within a Fabry-Perot (FP) cavity, that is created by two Bragg reflectors and is monolithically integrated with an HgCdTe IR detector. Electrostatic actuation of the thin-film membrane supported Bragg reflector is the means of providing wavelength discrimination of the incident IR photons which, for example, could be used for target discrimination or detection of various chemical/biological species via identification of narrow spectral features . . . The outcomes from this thesis have been incorporated into a monolithic integrated technology comprising low-temperature MEMS and HgCdTe IR detector technology. The integrated technology has been shown to be viable, and successful prototypes have been fabricated. Structural properties of the SiNx, SiOx, and Ge layers encompassed in the suspended IR reflector have allowed for IR photon detection in a narrow wavelength band with full-width at halfmaximum of ∼100nm that is tunable over a wavelength range from 2.2 to 1.85μm using a maximum tuning voltage of only 7.5V. Although the thesis objectives have been focused on a specific application related to multi-spectral IR detection technology as a demonstration vehicle, the findings of this thesis are directly applicable to any MEMS technologies that are to be merged with temperaturesensitive substrates/materials.
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kumar, Amit. "TEMPERATURE INSIDE THE LANDFILL: EFFECTS OF LIQUID INJECTION AND AMBIENT TEMPERATURE". Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2231.
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This study represents an analysis of comprehensive temperature and moisture content data collected from the anaerobic portion of a bioreactor landfill at the New River Regional Landfill, Florida, USA. The main focus of the study was the analysis of effects of the liquid injection on the temperature inside the landfill. When the leachate or groundwater at lower temperature than the landfilled waste is injected into the landfill, it has an initial cooling effect on the waste until the biological activity, enhanced by the additional moisture, releases heat. This cooling effect was tested in the study to determine whether it could be used to track moisture arrival as an alternative to moisture sensors. First of all, this hypothesis of cooling effect was tested at the injection wells by correlating temperature drops at the injection wells with known injection events. Then the temperature drop events were identified at monitoring locations where temperature and moisture sensors were co-located. The identification step at the monitoring wells was more difficult than in the case of the injection wells because the cooling effect at the injection well is more pronounced than at the monitoring sites, located 7.62 m away from the point of injection. From the analysis it was found out that, overall, the temperature drop at monitoring locations brought about by the injected liquid is a good criterion for tracking the moisture arrival, however only at the first arrival of moisture. Of all of the cases studied, temperature was able to indicate the moisture arrival for 85% of the times at the first injection as opposed to 36% overall. The difference was attributed to the stimulation of biological activity and subsequent heating of the injected liquid as it moves through the waste. Another focus of the research was the estimation of the waste quantity (volume) wetted from the injection. It was assumed that complete mixing takes places between injected liquid and the moisture already present in the waste and that the temperature of the injected liquid is the ambient temperature. According to the results, there was a significant gap between the expected and the actual wetted volume. The waste volume actually wetted was < 1% to 9% of the total waste volume expected to be wetted. Also studied was the effect of ambient temperature on the waste temperature. It was observed that the ambient temperature has no effect on the global temperature inside a bioreactor landfill even at a shallow depth of 4.6 m. While analyzing the trend of waste temperature inside the landfill, liquid injection was found to lead to an increase in temperature.M.S.Env.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engr MSEnvE
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Marsh, M. G. "The effect of a temperature gradient on high temperature fretting wear". Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267625.
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MacDonald, Timothy A. (Timothy Alan) 1974. "Electrical characterization of high temperature superconductors as a function of temperature". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/60136.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2000.Includes bibliographical references (p. 151-153).
The critical currents of silver sheathed multifilamentary Bi 2Sr 2Ca2 Cu3010 (BSCCO- 2223/Ag) tapes at temperatures ranging from 77 K to 110 K were measured using a typical four-terminal technique for two different BSCCO-2223/Ag tapes manufactured by Vacuumschmelze (VAC). The critical currents for the two VAC samples were measured as a function of magnetic field strength. The critical current of each sample was well described by the generalized Kim model. The critical current was also measured as a function of angle of the magnetic field with respect to the plane of the tapes, in all cases perpendicular to the transport current flow. Both samples displayed a high sensitivity to the magnetic field orientation with the largest critical currents measured when the magnetic field was in-plane with the broad face of the tapes. The current ramp rate effect on the critical current was investigated and showed no significant effect on the critical current measurements for ramp speeds between 6 A/min and 120 A/min. The energy dissipation or AC losses as a function of peak AC magnetic field, magnetic field sweep frequency, and transport current for a VAC sample and a sample manufactured by IGC - Advanced Superconductors (IGC) were measured at 77 K. The losses were measured using a pick up coil with a lock-in amplifier to measure the magnetization of the superconducting samples. The AC losses of both samples displayed complete electromagnetic coupling of the superconducting filaments at magnetic sweep frequencies of approximately 0.1 Hz. These results are consistent with results measured at magnetic field sweep frequencies of 60 Hz.
by Timothy A. MacDonald.
S.M.
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Burgoon, Penny Wung. "Temperature sensitivity and temperature compensation of neurons in the suprachiasmatic nucleus /". The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487947908403649.
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Smarra, Devin A. "Low Temperature Co-Fired Ceramic (LTCC) Substrate for High Temperature Microelectronics". University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1493386231571894.
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Wolf, Kevin, André Ehrlich e Manfred Wendisch. "Temperature profiles from airborne pyrgeometer measurements of broadband terrestrial radiation". Universität Leipzig, 2016. https://ul.qucosa.de/id/qucosa%3A16702.
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Profiles of broadband terrestrial radiation from airborne pyrgeometer measurements aboard research aircraft Polar 5 obtained during the VERDI campaign in 2012 were used to derive vertical temperature profiles. The retrievals were performed utilizing radiative transfer simulations by libRadtran (Mayer and Kylling, 2005). Manually changing the temperature of the input file for the simulations resulting calculated profiles of terrestrial irradiance were compared with measured profiles and iterated until best agreement. The selected test case shows the possibility of this technique and reveals several possible improvements. The algorithm has to be optimized to adapt the modelling temperature profile automatically using least-square error minimization between measured and modelled irradiance profiles. Additionally the vertical resolution has to be increased to consider small-scale variations. Using humidity and pressure profiles from ground-based observations and nearby radiosoundings significantly improves the retrieved temperature profiles.Vertikalprofile der breitbandigen terrestrischen Strahlung von flugzeuggetragenen Pyrgeometermessungen an Bord des Forschungsflugzeuges Polar 5 während der VERDI Kampagne in 2012 wurden genutzt, um Vertikalprofile der Temperatur abzuleiten. Das Retrieval erfolgte mit Hilfe von Strahlungstransfersimulationen unter der Verwendungung von libRadtran (Mayer and Kylling, 2005). Dazu wurde die Temperatur der Modellatmosphäre variert, bis eine bestmögliche Übereinstimmung von gemessenem und modellierten Irradianzprofil erzielt wurde. Der ausgesuchte Testfall zeigt das Potential dieser Technik und mögliche Verbessungsansätze. So muss der verwendete Algorithmus automatisiert werden, indem das modellierte Strahlungsprofil mit Hilfe eines Iterationsverfahrens und der Methode der kleinsten Fehlerquadrate an das gemessene Profil angepasst wird. Zusätzlich ist eine Erhöhung der vertikalen Auflösung von 50 m auf 10 m Schritte nötig, um kleinskalige Fluktuationen zu berücksichtigen. Die Verwendung von bodengebundenen Beobachtungen und nahegelegenen Radiosondenaufstiegen in der Modellatmosphäre führt zu einer weiteren signifikanten Verbesserung der abgeleiteten Temperaturprofile.
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Simões, Débora de Souza. "Ambiente físico e meteorológico para análise do risco de geada". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/132123.
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A geada é um fenômeno meteorológico adverso que causa perdas severas ao setor agrícola, em especial no Sul do Brasil. A baixa distribuição espacial da rede de estações meteorológicas dificulta o monitoramento e a previsão do fenômeno. O propósito principal desta tese foi o desenvolvimento de um modelo matemático para quantificar de forma direta e simples a probabilidade do risco de ocorrência de geada tendo como base em dados de fácil obtenção como altitude, latitude, continentalidade e temperatura do ar. O modelo criado, denominado Risco Geral de Geada (RGG), foi idealizado a partir de dois riscos básicos, o risco geográfico e o risco advindo da temperatura mínima do local, ambos com o mesma contribuição para a ocorrência de geada. O risco geográfico de geada (RGeo) foi obtido a partir do somatório dos riscos atribuídos aos fatores geográficos altitude, latitude e continentalidade. Cada um destes fatores contribui de forma diferente para a formação da geada e suas contribuições foram estimadas a partir de um modelo de regressão linear múltipla para a estimativa da temperatura mínima do ar climatológica de inverno no Rio Grande do Sul. No risco de geada associado à temperatura mínima (RTmín) foi feita a atribuição de riscos em um intervalo de temperatura entre 0 e 6°C. O modelo final obtido, válido apenas para o Rio Grande do Sul, foi testado com dados coletados em estações meteorológicas de superfície da mesorregião do Sudeste Rio-grandense, localizadas em Encruzilhada do Sul, Rio Grande e Santa Vitória do Palmar. Dados de temperatura mínima do ar nos meses de junho, julho e agosto, coletados entre os anos de 1961 e 2015, comprovaram a utilidade do modelo RGG para a definição da probabilidade do risco de ocorrência de geada, mesmo diante de incertezas atribuídas a outros fatores não descritos no modelo. Na região de teste também foi avaliada a qualidade de dados orbitais de temperatura da superfície terrestre (TST), obtidos do produto MDY11A1 da passagem noturna do sensor MODIS/AQUA, na detecção de temperaturas baixas relacionadas com a ocorrência de geada. A frequência de dias com TST inferiores a 3°C mostrou coerência tanto com os dados observados em estação meteorológica, quanto com o risco determinado pelo RGG. A coerência entre os resultados obtidos do modelo RGG e os dados reais observados em superfície e obtidos por satélite torna o modelo útil na descrição da probabilidade do risco de ocorrência de geada sobre o Rio Grande do Sul.Frost is an adverse meteorological phenomenon that causes severe losses to the agricultural sector, especially in Southern Brazil. Low spatial distribution of the network of meteorological stations hinders monitoring and forecast phenomenon. The main purpose of this thesis was to develop a mathematical model to measure directly and easily the probability of the risk of frost based on readily available data such as altitude, latitude, continentality and air temperature. The model, called Frost General Risk (RGG), was designed from two basic risk, geographic risk and risk arising out of the local minimum temperature, both with the same contribution to the occurrence of frost. The geographical risk of frost (RGeo) was obtained from the sum of the risks attributed to geographical factors altitude, latitude and continental influence. Each of these factors contributes differently to the formation of frost and their contributions were estimated from a multiple linear regression model to estimate the minimum air temperature winter climatological in Rio Grande do Sul. In the frost risk associated with minimum temperature (RTmín) assigning risk was taken in a temperature range between 0 and 6° C. The final model obtained, valid only for the Rio Grande do Sul, has been tested with data collected from weather stations surface of the middle region of Sudeste Rio-grandense, located in Encruzilhada do Sul, Rio Grande and Santa Vitória do Palmar. Minimum temperature, the air in the months of june, july and august, collected between 1961 and 2015, have proved the usefulness of the model RGG to define the probability of the risk of frost, even in the face of uncertainty attributed to other factors not described in the model. In the test region was also evaluated the quality of satellite data of the land surface temperature (LST), the product obtained MDY11A1 the night passage of MODIS / AQUA sensor to detect low temperatures related to the occurrence of frost. The frequency of days with LST below 3° C showed much consistency with the observed data in weather station, and with the particular risk for the RGG. Consistency between the results obtained from the RGG model and the actual data observed in surface and from satellites makes the model useful in describing the probability of the risk of frost on the Rio Grande do Sul.
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Bleisteiner, Marcus, Markus Barth, Armin Raabe e P. Holstein. "Tomografische Rekonstruktion der Raumtemperaturverteilung aus einer Raumimpulsantwort". Universität Leipzig, 2015. https://ul.qucosa.de/id/qucosa%3A16698.
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Temperature can be estimated by acoustic propagation time measurements along known sound paths. By using a multitude of known sound paths in combination with a tomographic reconstruction technique a spatial and temporal resolution of the temperature field can be achieved. Based on it, this article focuses on an experimental method in order to determine the spatially differentiated development of room temperature with only one loudspeaker and one microphone. The theory of geometrical room acoustics is being used to identify sound paths under consideration of reflections. The propagation time along a specific sound path is derived from the room impulse response. Temporal variances in room impulse response can be attributed primarily to a change in air temperature and airflow. It is shown that in the absence of airflow a three-dimensional acoustic monitoring of the room temperature can be realized with a fairly limited use of hardware.Die Temperatur kann mithilfe von akustischen Laufzeitmessungen auf definierten Schallstrecken ermittelt werden. Der Einsatz multipler Schallstrecken, in Verbindung mit einem tomografischen Rekonstruktionsverfahren, erlaubt eine räumliche Auflösung der genannten klimatologischen Größe. Aufbauend darauf, befasst sich dieser Artikel mit einer experimentellen Methode zur Erfassung der räumlich und zeitlich aufgelösten Entwicklung der Raumtemperatur mit lediglich einem Lautsprecher und einem Mikrofon. Die Theorie der geometrischen Raumakustik wird genutzt, um Schallstrecken, unter der Berücksichtigung von Reflexionen, zu identifizieren. Die zu den Ausbreitungswegen gehörenden Laufzeiten werden aus einer gemessenen Raumimpulsantwort abgeleitet. Zeitliche Varianzen in Raumimpulsantworten sind in erster Linie auf die Veränderung der Lufttemperatur und von Strömungsverhältnissen zurückzuführen. Es wird gezeigt, dass bei Abwesenheit von Raumluftströmungen, eine dreidimensionale, akustische Überwachung der Raumtemperatur mit einem sehr geringen Einsatz an Messtechnik realisiert werden kann.
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Ocampo, Chuquipul Karla Dalila, e Romero Katherine Luz Del Pilar Zevallos. "Análisis y evaluación de factores que determinan el desarrollo del servicio de transporte en frío de productos alimenticios perecederos en un operador logístico". Bachelor's thesis, Universidad Ricardo Palma, 2015. http://cybertesis.urp.edu.pe/handle/urp/1295.
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La presente tesis tiene como propósito principal elaborar un análisis y evaluación de los factores más importantes que determinan el desarrollo del servicio de transporte de productos alimenticios perecederos en un operador logístico en la cadena de frío, en función a las necesidades del cliente y al correcto funcionamiento del servicio; con la finalidad de que la empresa se consolide como operador logístico, brindando los servicios de almacenamiento, consolidación de mercadería, transporte y distribución.
A partir de una entrevista con el gerente general y el coordinador de transporte se pudo comprender el origen de diversos problemas que vienen afectando al servicio de transporte, siendo este la falta de un análisis de factores que intervienen en la operatividad del servicio.
Antes del análisis de dichos factores, se realizó una revisión bibliográfica de los antecedentes y las bases teóricas referentes al tema. A partir de ello se concluyó que existen muy pocos antecedentes en el Perú de estudios referentes al servicio de transporte de productos alimenticios perecederos y de la cadena de frío. Sin embargo, se encontraron estudios referentes a la cadena de frío en países como Venezuela, Colombia, Estados Unidos y otros países, lo cual nos dio a entender que la gestión de la cadena frío se encuentra más desarrollada en el extranjero. En base a esto, se elaboraron propuestas de mejora con las bases teóricas revisadas, registros de información brindados por la empresa e información adicional recopilada de los clientes.
This thesis has as a main purpose preparing an analysis and evaluation of the most important factors determining the development of the service of transporting perishable foodstuffs into a logistics operator in a cold chain, according to the needs of the client and the proper functioning of the operations of the system; the company will obtain a strong base in the branch of the logistics department, providing storage services, consolidation of goods, transport and distribution.
From an interview with the general manager and the transportation coordinator, it can be understood that the lack of an analysis in the logistics department is the origin of the diverse problems that are affecting the transport service.
Before the analysis of these factors, a literature review of the history and theoretical basis concerning the issue was made. From this it was concluded, that there are very few precedents in Peru, relating to the studies of the transportation of perishable food products and cold chain. However, studies on the operational refrigeration in countries such as Venezuela, Colombia, United States and other countries, gave us information to understand that the management of the cold chain is more developed abroad. Based on the studies made proposals to improve the theoretical foundations were revised, and records of information were provided to develop the logistics process in Peru.
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Jacobi, Christoph, Nadja Samtleben e Gunter Stober. "Meteor radar observations of mesopause region long-period temperature oscillations". Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-212263.
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Meteor radar observations of mesosphere/lower thermosphere (MLT) daily temperatures have been performed at Collm, Germany since August 2004. The data have been analyzed with respect to long-period oscillations at time scales of 2–30 days. The results reveal that oscillations with periods of up to 6 days are more frequently observed during summer, while those with longer periods have larger amplitudes during winter. The oscillations may be considered as the signature of planetary waves. The results are compared with analyses from radar wind measurements. Moreover, the temperature oscillations show considerable year-to-year variability. In particular, amplitudes of the quasi 5-day oscillation have increased during the last decade, and the quasi 10-day oscillations are larger if the equatorial stratospheric winds are eastward.
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Williams, Michael Eric. "Ab-initio elastic and thermodynamic properties of high-temperature cubic intermetallics at finite temperatures". [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2779.
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Vasic, Aleksander Z. "High temperature properties and heat transfer phenomena for steam at temperatures up to 5000K". Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/9641.
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Thermodynamic and transport properties and heat phenomena for steam in a high temperature region were examined. First, a set of computer subroutines was developed -the Fraction code, for generating molar fractions of a dissociating steam and gas mixture for a given pressure and temperature. Second, a set of computer subroutines was developed for the computation of all possible combinations of binary diffusion coefficients and of the diffusion coefficient for the component through a gas mixture. Third, steam properties may be evaluated for an ideal gas mixture which includes no effect of chemical reactions-frozed state, or for a non-ideal solution at equilibrium state which includes maximal effects of chemical reactions-effective properties at equilibrium state. A set of computer subroutines was developed-the Frozen Properties code, for evaluating dissociated steam frozen properties for a given pressure and temperature. A computer code, UODH2O (University of Ottawa Dissociation H$\sb2$O code), was developed using a look-up table and interpolation technique to generate effective properties at pressure from 0.01 to 100.00MPa and temperature from 1000 to 5726.85$\sp\circ$C. Based on the semi-empirical model by Nesterenko et al. (1967 a) for dissociated nitrogen tetroxide (N$\sb2$O$\sb4$#2NO$\sb2$ a two-component gas mixture), a method was developed to determine the Nusselt number of a chemically reacting (dissociated) fluid flow. (Abstract shortened by UMI.)
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Jelena, Purać. "Molekularne osnove otpornosti polarnih insekata na niske temperature". Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2009. https://www.cris.uns.ac.rs/record.jsf?recordId=82067&source=NDLTD&language=en.
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Sposobnost insekata da se prilagode različitim ekološkim uslovima je veoma dobrodokumentovana; oni predstavljaju najrasprostranjeniju grupu životinja na planeti, sa vrstama koje naseljavaju različita kopnena i vodena staništa, od tropskih predela do polova. Razumevanje mehanizama koji omogućavaju insektima da prežive ekstremne temperature i zadrže vitalne funkcije tokom dugog perioda dormancije je kao model sistem od interesa za mnoge naučne oblasti. Na osnovu načina na koji preživljavaju temperature ispod 0ºC insekte možemo podeliti u tri grupe: i) insekti koji tolerišu formiranje leda u ekstraćelijskom prostoru,ii) insekti koji ne tolerišu zamrzavanje i moraju da ga izbegnu, a to čine superhlađenjem svojih telesnih tečnosti i iii) insekti koji preživljavaju zahvaljujući gubitku vode kroz permeabilnu kutikulu, što je nazvano krioprotektivna dehidratacija. Zajednička odlika organizama sa različitim mehanizmima adaptacije na niske temperature je setbiohemijskih jedinjenja čija se fiziološka funkcija razlikuje u zavisnosti da li organizam pripada grupi koja toleriše ili ne toleriše zamrzavanje. To su nukleatori kristalizacije leda, krio/anhidroprotektanti i antifriz proteini.Cilj ovih istraživanja je bio ispitivanje molekularne osnove otpornosti na niske temperature dve vrste polarnih kolembola Onychiurus arcticus i Cryptopygus antarcticus kombinujući fiziološki, biohemijski i molekularno biološki pristup. Ispitivane vrste izbegavaju zamrzavanje svojih telesnih tečnosti primenjujući različite strategije preživljavanja. Za antarktičku vrstu C. antarcticus karakteristična je brza promena tačke superhlađenja, kao i njena bimodalna distribucija tokom leta, kada neke jedinke mrznu na višim temperaturama (manje otporne na hladnoću), a druga na nižim (otpornije na hladnoću). Ova bimodalna distribucija tačke superhlađenja je dobro dokumentovana, ali slabo razjašnjena na molekularnom nivou. Druga, arktička vrsta O. arcticus koristi strategiju preživljavanja zimskih temperature koje idu i do -25ºC nazvanu krioprotektivna dehidratacija. Na ovaj način, količina slobodne vode u telu se značajno redukuje, a akumulira se trehaloza koja deluje kao krio/anhidroprotektant. Iako je krioprotektivna dehidratacija opisana i kod drugih vrstainsekata, molekularni mehanizmi koji se nalaze u osnovi ovog fenomena su veoma slabo razjašnjeni.Za karakterizaciju genoma generisano je 16379 EST sekvenci za O. arcticus i 1180 za C. antarcticus. To su ujedno i prvi javno dostupni podaci u bazama podataka o genomima ove dve vrste koji predstavljaju značajnu osnovu za komparativne genomske analize. Činjenica da kod obe analizirane vrste, oko 60% EST sekvenci nije pokazalo statistički značajnu sličnost sa proteinima iz baza podataka ukazuje na specifičan patern genske ekspresije kao adaptivni odgovor ispitivanih vrsta na niske temperature.Sa ciljem da se identifikuju geni uključeni u preživljavanje niskih temperatura konstruisani su mikroereji, za O. arcticus štampanjem 6912 cDNK u duplikatu, a za C. antarcticus štampanjem 672 cDNK u duplikatu.. Analizom sekvenci identifikovanih putem homologije sa dostupnm bazama podataka kod C. antarcticusuočen je jasan trend povećane ekspresije gena koji kodiraju strukturne proteine u grupi koja je otporna na hladnoću. Ove strukturne proteine uglavnom čine kutikularni proteini, što je u skladu sa rezultatima nedavnih istraživanja kod kolembola, da je presvlačenje proces tokom kog se snižava tačka superhlađenja, odnosno da varijacije u tački superhlađenja mogu nastati kao posledica endogenih fizioloških procesa tokom presvlačenja. Kod O. arcticus analizom EST sekvenci i mikroereja identifikovani supotencijalni geni i biohemijski putevi povezani sa krioprotektivnom dehidratacijom, a istakli bi gene uključene u metabolizam ugljenih hidrata, gene za akvaporine, proteine toplotnog stresa, LEA proteine i enzime antioksidativne zaštite.The ability of insects to adapt to diverse ecological conditions iswell documented; they are the most diverse fauna on earth, with different species occupying arange of terrestrial and aquatic habitats from the tropics to the poles. Understanding the mechanisms by which insects survive such extreme temperatures and retain viability for longperiods in the dormant state is of great interest to many scientific fields. Insects have evolved three main strategies to survive sub-zero temperatures: i) freeze tolerance, ii) freeze avoidance and iii) cryoprotective dehydration. The main biochemical compounds involved in surviving sub-zero temperatures are same for different strategies but their physiological role is different. They include: ice nucleating agents (INAs), cryo/ anhydroprotectants, and antifreeze proteins (AFPs). The aim of this study was to determine molecular adaptations to extreme cold environments, combining physiology, biochemistry and molecular biology pproaches, in thePolar Collembola: Cryptopygus antarcticus and Onychiurus arcticus. Both species are freeze avoiding but employ different strategies for surviving low temperatures. The Antarctic springtail C. antarcticusis capable of rapid cold hardening with a bi-modal distribution of super cooling points (SCP) with high (less cold-hardened) and low (more cold-hardened) groups of animals present even during the growing season in summer. This bimodal distribution has been well documented, but is poorly understood. The Arctic springtail O. arcticusemploys the strategy known as cryoprotective dehydration to survive winter temperatures as low as -25ºC. With this technique, the amount ofavailable water in the body is reduced to almost zero and also there is an accumulation of trehalose, which acts as a cryo/anhydroprotectant. Although cryoprotective dehydration has been described in other insects, the molecular mechanisms behind this phenomenon are poorly understood.A total of 16,379 EST clones were generated for O. arcticus and 1180 for C. antarcticus. This represents the first publicly available sequence data for this two species providing useful data for comparative genomic analysis. The fact that around 60% of the clones for both species showed no sequence similarity to annotated genes in the datasets, suggests a specific pattern of gene expression in these species as adaptation to low temperatures.Two microarrays were constructed to identify genes involved in surviving low temperatures, one for C. antarcticus by printing 672 clones in duplicate and the other for O. arcticus by printing 6912 clones in duplicate. An analysis of those where putative function could be inferred via database homology, in C. antarcticus there was aclear pattern of up-regulation of structural proteins being associated with the cold tolerant group. These structural proteins mainly comprised cuticle proteins and provide support for the recenttheory that summer SCP variation within Collembola species could be a consequence of moulting, with moulting population having lowered SCPs. In O. arcticus EST and microarrayanalysis revealed clones and biochemical pathways associated with cryoprotective dehydration with a particular reference to genes involved in carbohydrate metabolism, aquaporin genes, heat shock proteins, LEA proteins and antioxidant enzymes.
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Trezza, Beatriz Maria. "O efeito da exposição ao calor sobre o desempenho cognitivo de idosos: um estudo controlado". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/5/5144/tde-13052015-084847/.
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Introdução: Concomitante ao processo de envelhecimento populacional, estão ocorrendo mudanças climáticas, sendo a principal delas o aquecimento global. O envelhecimento leva a mudanças tanto nos mecanismos de termorregulação quanto no desempenho cognitivo. Embora inúmeros estudos tenham avaliado o efeito do calor sobre a cognição de adultos jovens, este é um tema praticamente inexplorado na população geriátrica. Objetivos: Avaliar o efeito da exposição ao calor sobre o desempenho cognitivo de idosos saudáveis e identificar fatores que expliquem as variações na susceptibilidade ao estresse térmico nesta população. Casuística e Métodos: 68 idosos com bom desempenho físico e cognitivo realizaram uma bateria de testes neuropsicológicos em duas condições ambientais: 24oC (controle) e 32oC (calor). Através de cinco testes selecionados da Bateria Neuropsicológica Automatizada de Testes de Cambridge (CANTAB), foram avaliados diferentes aspectos do desempenho cognitivo com foco principal em memória, atenção e velocidade de processamento. Um escore composto global de desempenho cognitivo foi criado usando a medida mais representativa de cada um desses testes. Antes e após cada uma das sessões de testes, foram aferidos o peso corporal, a temperatura axilar, a temperatura auricular, a frequência cardíaca e a pressão arterial. Por meio da análise de variância para medidas repetidas (ANOVA), verificou-se a interação entre o efeito da temperatura na cognição (avaliada pelo escore composto global) e características sociodemográficas (idade, sexo, educação, cor), frequência de exercício físico e umidade relativa registrada durante o protocolo de exposição ao calor. Adicionalmente, foi também desenvolvido um modelo de regressão linear multivariada a fim de identificar variáveis independentes que explicariam a susceptibilidade ao estresse pelo calor. Resultados: A idade média da amostra foi de 73,28 anos. 42,9% dos indivíduos relataram praticar atividade física quatro ou mais vezes por semana. As temperaturas auriculares e axilares aumentaram significativamente após a exposição ao calor, sendo que as diferenças médias encontradas foram de 0,55 e 0,43oC respectivamente. Não foram observadas diferenças significativas entre quaisquer medidas individuais de desempenho ou no escore composto global quando comparamos o desempenho cognitivo sob as duas temperaturas experimentais. Na análise de interação, somente os níveis de umidade registrados durante o protocolo de exposição ao calor e a frequência da prática de exercícios modificaram significativamente o efeito da temperatura sobre o desempenho cognitivo. Os sujeitos expostos a maior umidade relativa do ar no protocolo de calor e os voluntários menos ativos apresentaram piora no desempenho cognitivo na sessão a 32oC. Estes achados foram confirmados num modelo de regressão linear totalmente ajustado. Conclusão: A análise principal mostrou que o desempenho cognitivo de idosos com boa funcionalidade não sofreu efeito deletério da exposição ao calor. No entanto, os voluntários expostos ao calor mais úmido e aqueles que relataram menor frequência de exercício físico apresentaram pior desempenho na sessão de calor que na de controle. As variáveis sócio-demográficas como idade, gênero, escolaridade e cor não tiveram influência na susceptibilidade ao estresse térmicoIntroduction: Concomitantly to the process of population aging, major climate changes are taking place, among which global warming is regarded as the most important. Aging leads to changes in temperature control mechanisms and is associated with a subtle and progressive decline in cognitive functions. Although a great deal of studies have evaluated the effect of heat on the cognitive performance of young adults, to the best of our knowledge, no studies have directly investigated the effects of warm environments on the cognitive functioning of older adults. Objectives: To evaluate the effect of heat exposure on the cognitive performance of healthy older adults and to identify factors that would explain variations in susceptibility to heat stress in that population. Methods: 68 older adults with both good physical and cognitive performance were requested to take a series of neuropsychological tests under two environmental conditions: at 24oC and 32oC. Five tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) were administered to measure different aspects of cognitive functioning while focusing on memory, attention and processing speed. A global composite score of cognitive performance was created, using the most representative measures of each one of those five tests. Before and after each session, measures of auxiliary temperature, tympanic temperature, blood pressure, heart rate, and body weight were obtained. Interaction analysis was carried out using repeated measures analysis of variance (ANOVA) in order to check whether the effect of temperature on cognition, assessed by the global composite score, was modified by sociodemographic characteristics (age, gender, education, race), frequency of physical activity or relative humidity registered during the heat protocol. In addition, a multiple linear regression model has been fitted to identify independent variables that would explain susceptibility to heat stress Results: The mean age of the sample was 73.28 years and 42.9% of the participants reported performing physical activities at least four times a week. Tympanic and auxiliary temperatures increased significantly after the heat exposure with increases of 0.55 and 0.43oC, respectively. No significant differences were observed among any individual measures or the composite score, when comparing the cognitive performance under the two experimental temperatures. In the interaction analysis, only the humidity levels during the heat exposure protocol and the frequency of physical activities significantly modified the effects of temperature on cognitive performance. Participants exposed to higher relative air humidity during the heat protocol and the less active ones have presented worse cognitive performance in the session at 32oC. Those findings have been confirmed by a totally adjusted linear regression model. Conclusion: The main analysis has shown that the cognitive performance of older healthy adults has not had deleterious effect of heat exposure. Nevertheless, the volunteers exposed to more humid heat and those who have reported lower frequency of physical exercises have shown worse performance during the heat session than in the control session. The sociodemographic variables such as age, gender, education and race have not had any influence over susceptibility to heat stress
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Rashidi, Mohammadi Abdolreza. "MEMS pressure, temperature and conductivity sensors for high temperature and harsh environments". Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/33783.
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Kraft pulp digesters have been used to convert wood chips into pulp for manufacturing a wide variety of paper products. Inside a kraft digester, chemical reactions remove lignin from their wood matrix in a caustic environment (pH~13.5, 170°C, 2MPa). Data on actual internal operating conditions in a kraft digester is needed to optimize kraft digester operation and obtain maximum production quality. Currently, this information is limited to selected static locations on the periphery of the digester. The objective of this thesis is to develop miniature temperature, pressure, and liquid conductivity sensors for use in autonomous flow-following SmartChips to measure kraft process variables within the digester during their passage through the process.
Combined capacitive pressure and temperature sensors were fabricated by bonding silicon and Pyrex chips using a new polymeric gap-controlling layer and a high temperature adhesive. A simple chip bonding technique involving insertion of the adhesive into the gap between two chips was developed. A silicon dioxide layer and a thin layer of Parylene were deposited to passivate the pressure sensor diaphragm against the caustic environment in kraft digesters. The sensors were characterized at both high temperatures and pressures and no signs of corrosion could be identified on the sensors.
Integrated piezoresistive pressure and temperature sensors consisting of a square silicon diaphragm and high resistance piezoresistors were developed. A new Parylene and silicone conformal coating process were developed to passivate the pressure sensors against the caustic environment. The sensors were characterized up to 2MPa and 180°C in an environmental chamber. The sensors’ resistances were measured before and after testing in a kraft pulping cycle and showed no change in their values. SEM pictures and topographical surface analyses were also performed before and after pulp liquor exposure and showed no observable changes.
Combined liquid conductivity and temperature sensor packages consisting of a platinum resistance temperature detector (RTD) and a four-electrode conductivity sensor formed by stainless steel electrodes and installed on a polyetheretherketone (PEEK) enclosure were developed. The sensors were characterized up to 180°C at NaOH concentrations of 10-100g/l in the presence of wood chips and survived with no signs of corrosion.
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Burger, Marco. "Prediction of the temperature distribution in asphalt pavement samples". Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50422.
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Thesis (MScEng)--Stellenbosch University, 2005.ENGLISH ABSTRACT: The convection heat transfer coefficient between an infinite, horizontal surface and the natural environment is determined experimentally. It is shown that, during daytime, heat is transferred due to natural and forced convection, while during nighttime heat is transferred due to conduction and forced convection. Equations that correlate the daytime and nighttime convective heat transfer coefficients respectively, are presented. The results are compared with values obtained by other investigators. The equations for the convection heat transfer coefficient are then used to predict the surface temperature and the temperature at depth of asphalt pavement samples using a simulation model. It is found that there is good agreement between the measured and the predicted asphalt pavement sample temperatures.
AFRIKAANSE OPSOMMING: Die konveksie warmteoordrags-koëffisiënt tuseen 'n oneindige, horisontale oppervlak en die natuurlike omgewing is eksperimenteel bepaal. Daar word getoon dat warmte, tydens die dag, oorgedra word deur natuurlike en geforseerde konveksie, terwyl warmte tydens die nag oorgedra word deur geleiding en geforseerde konveksie. Die resultate word vergelyk met die resultate van ander navorsers. Vergelykings wat die konveksie warmteoordrags-koëffisiënt gedurende die dag en nag onderskeidelik korreleer word voorgestel. Die vergelykings vir die konveksie warmteoordrags-koëffisiënt word dan gebruik in 'n simulasiemodel om die oppervlaktemperatuur en die temperatuur onder die oppervlakte van asfalt-padoppervlakmonsters te voorspel.
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Hernandez, Sinuhe. "High Temperature Wear Processes". Licentiate thesis, Luleå tekniska universitet, Maskinelement, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16827.
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Moving machine assemblies are increasingly exposed to extreme operating conditions involving high temperatures owing to demands on higher power densities, high performance/efficiency and extreme environments. The changes in surface and near surface properties of contacting surfaces caused by exposure to high temperature and deformation govern the occurrence of friction, wear and material transfer of the tribological system. However, these changes have not been thoroughly investigated. In order to enable development of new products and processes, there is a need for new knowledge pertaining to tribological phenomena occurring at elevated temperatures.One of the most commonly used engineering materials is steel as it offers a good compromise between performance and cost even at high temperatures. For example, prehardened (quenched and tempered) tool steels are commonly used in hot forming dies can also be employed in other technological applications involving elevated temperatures. Although the research pertaining to hot stamping, and high temperature tribology in general, has significantly grown during the last years there are still knowledge gaps that need to be bridged. Adhesion and abrasion have been identified as the most dominant wear mechanisms in high temperature tribological systems but the detailed understanding of the mechanisms is still inadequate.The objective of this work is therefore to obtain a deeper understanding of the tribological phenomena associated with adhesion and abrasion that takes place at high temperatures. Unidirectional sliding wear tests have been conducted in order to investigate the influence of contact pressure and temperature on the wear and friction characteristics of tool steel and boron steel pair. Tribological studies involving boron steel, tool steels and heat-treated high-Si steels in a three body abrasive environment were also carried out with a view to explore the effect of temperature on the wear rate, wear mechanisms and to correlate this with material properties like hot hardness and toughness.The results from the unidirectional sliding tests showed that the frictional behaviour of tool steel and boron steel is load and temperature dependent. In general the friction coefficient decreases as both temperature and load are increased as a result of the formation of oxide layers. At temperatures above 200 °C, the compaction and sintering of these layers led to the formation of a wear protective glaze layer. Consequently, the wear rate for both materials decreased at elevated temperatures. Additionally, a friction and wear mechanisms map was developed for the investigated materials.In the case of abrasive wear tests, the results showed that the main wear mechanism presented for each material varied with temperature. In general, a transition from micro-ploughing to a combination of micro-cutting and micro-ploughing was present. The tool steels and boron steel showed a decrease in wear rate in the range of 100 to 400 °C compared to that at room temperature. This was attributed to the toughness in case of the tool steel and the formation of a protective tribolayers for the boron steel. Above 400 °C the wear rate increased for these three materials mainly due to the recovery and recrystallization processes. The wear rate of the high-Si steels increased with testing temperature. At 500 °C, these steels had the same hardness and the differences in wear were attributed to the changes in the material toughness.Godkänd; 2014; 20140408 (sinher); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Sinuhe Hernandez Ämne: Maskinelement/Machine Elements Uppsats: High Temperature Wear Processes Examinator: Professor Braham Prakash, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: Assoc. Prof. Ph.D; Head, Metallic Materials and Tech. Dept. Bojan Podgornik, Institute of Metals and Technology, Ljubljana, Slovenia Tid: Fredag den 16 maj 2014 kl 10.00 Plats: E231, Luleå tekniska universitet
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Wülfert, Florian. "Temperature-robust multivariate calibration". [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/76379.
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Sangwan, Veena. "Temperature sensing in plants". Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37831.
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It is now well established that cold-triggered calcium influx mediates cold-induced gene expression and development of freezing tolerance (cold acclimation). In this thesis, cold signaling events both upstream and downstream of calcium influx were examined.First, it was shown that the studies on calcium mediation of cold acclimation in alfalfa cell suspension cultures could be applied to intact seedlings of Arabidopsis. Calcium chelators and channel blockers caused a strong reduction in the cold-induced accumulation of kin1 and kin2 transcripts, suggesting that calcium influx was an essential event during cold signaling and that the source of calcium for this influx was largely the calcium-rich cell wall. Evidence suggesting the involvement of calcium-dependent protein kinases (CDPKs) was also obtained.
Second, the nature of events upstream of calcium influx was explored. For this study, transgenic Brassica napus seedlings possessing both the endogenous cold-inducible BN115 gene and the coding part of beta-glucuronidase (GUS) gene placed under the control of the BN115 promoter were used. Thus cold-activation of the BN115 promoter drove the expression of both BN115 at the transcriptional level and the GUS enzyme activity at the translational level. Cold-activation of BN115 was inhibited by chemicals which cause membrane fluidization, cytoskeletal stabilization and inhibition of Ca2+ influx, and mimicked at 25°C by chemicals causing membrane rigidification, cytoskeletal destabilization and Ca2+ influx. Inhibitors of protein and lipid kinases prevented cold-activation of BN115, but inhibition of protein phosphatases activated BN115 at 25°C.
Third, given the increasing importance of mitogen-activated protein kinases (MAPKs) in signal transduction, the nature of molecular mechanisms that lead to cold-activation of a previously reported MAPK, SAMK, was investigated. During this study, the first plant MAPK activated by heat shock was discovered and named HAMK (Heat-shock-activated MAPK). It was shown that cold-activation of SAMK is mediated by cold-induced membrane rigidification, whereas the heat shock-activation of HAMK occurs through heat shock-induced membrane fluidization. Whereas activation of both SAMK and HAMK is blocked by an actin microfilament stabilizer, it is mimicked at 25°C by chemical destabilizers of microtubules or actin microfilaments. All of these events are inhibited by blocking the influx of extracellular Ca 2+. Cold-activation of SAMK and heat-activation of HAMK was prevented by treatment of cells with inhibitors of CDPKs. Thus, cold and heat shock are sensed by structural changes in the plasma membrane, which transduces the signal via cytoskeletal rearrangements to the opening of calcium channels, leading to Ca2+ influx, activation of CDPKs and activation of distinct MAPK cascades.
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Bateman, Rodney William. "Cryogenic temperature sensor investigation". Thesis, Birkbeck (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313794.
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RABE, CLAUDIO. "TEMPERATURE EFFECTS ON SOILS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1998. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1521@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORO presente trabalho apresenta um estudo do comportamento mecânico de um solo argiloso e um solo residual, submetidos a ensaios com temperaturas entre 20ºC e 70ºC. O programa experimental envolveu ensaios de caracterização (limites de Atterberg), ensaios de adensamento com carregamento incremental (SIC), triaxiais não drenados (CIU) e de cisalhamento direto. Para a realização dos ensaios de limites de Atterberg, as amostras foram previamente aquecidas em estufa. Para a realização dos ensaios de adensamento, triaxiais e de cisalhamento direto, foram desenvolvidos sistemas de aquecimento, controle e distribuição térmica, para garantir ao corpo de prova uma uniformidade da temperatura preestabelecida. Uma metodologia de calibração do sistema de aquecimento foi desenvolvida para se determinar o tempo necessário para o equilíbrio térmico dos solos. Houve também a preocupação com a calibração prévia dos instrumentos eletrônicos da prensa triaxial (transdutores e célula de carga) na temperatura dos ensaios. Na faixa de temperatura estudada, o preaquecimento não têm influência nos resultados de limites do solo argiloso. Os ensaios de adensamento revelaram que o aquecimento leva a um aumento da compressibilidade do solo, assim como um aumento da velocidade de adensamento. Nos ensaios triaxiais, observou-se que o aumento da temperatura causa um aumento da resistência dos materiais, além de reduzir o excesso de poropressões gerado durante o cisalhamento não drenado. Os ensaios de cisalhamento direto confirmaram a tendência de aumento da resistência observada nos ensaios triaxiais, além de indicar uma redução da deformabilidade volumétrica durante o cisalhamento.
The subject matter of this thesis is the study of the mechanical behavior of clay and residual soils subjected to a series of tests with temperatures ranging from 20 to 70ºC. The experimental program consisted of Atterberg limits, consolidation tests with incremental loading (SIC), triaxial consolidated undrained tests (CIU) and direct shear tests on both soil types under saturated conditions. Samples for Atterberg limit tests have been pre-heated in oven to the specified temperature. Heating control and thermal distribution systems have been specially developed for insuring an homogeneous temperature throughout the consolidation, triaxial and direct shear tests. The thermal balance times for the two soils were achieved by means of a calibration method developed for the heating system. Transducers and load cell calibration were carefully calibrated acording to the temperature range for the testing program. It may be concluded that pre-heating to temperatures below 70ºC has no influence on the Atterberg limits results for both soils. Consolidation tests have shown that heating on samples leads to an increase in compressibility and also on the coefficient of consolidation. From the triaxial tests it was observed that an increase in temperature leads to an increase in strength and to smaller excess porepressures during undrained shear tests. The increase in shear strenght with temperature observed on triaxial tests was also confirmed by direct shear tests. These effects were more significant in clay than in residual soil.