Dissertations / Theses on the topic 'Rising temperatures'
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Thundiyil, Karen A. 1976. "Rising temperatures and expanding megacities : improving air quality in Mexico City through Urban Heat Island mitigation." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29946.
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Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2003.Includes bibliographical references (leaves 57-60).
Mexico City exists as a city space pushed and pulled in multiple directions. Different scales and levels of spatial reference and planning have come together to produce a dynamic and contradictory place united by the identity of Mexico City. Unfortunately, the city faces a regional environmental dilemma stemming from its chronic air pollution problem. Many steps have been taken to reduce air pollution in the city and this study examines an additional air quality improvement strategy that has been implemented in other megacities. Singapore and Tokyo have supplemented their air pollution reduction programs with Urban Heat Island (UHI) mitigation plans. Across the globe, cities experience a phenomenon called the UHI effect where urban areas are several degrees warmer than neighboring suburban or rural areas. A cycle of consuming more energy for cooling purposes adds to greenhouse gas production from the additional power generation and then feeds back to the system with yet higher temperatures in the city. In addition, higher ambient temperatures help speed the formation of smog. This study examines what Tokyo and Singapore have done in terms of an UHI mitigation plan, analyzes what can be done to reduce the UHI effects in Mexico City to improve air quality and quantifies the effects of potential physical changes. Modest surface changes are modeled and predicted to reduce average temperature by more than a full Fahrenheit degree. A decrease in surface temperature can slow the formation of smog and can help mitigate the impacts of the Urban Heat Island effect.
by Karen A. Thundiyil.
M.C.P.
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Siebold, Magdalena [Verfasser], Andreas von [Akademischer Betreuer] Tiedemann, Hans-Joachim [Akademischer Betreuer] Weigel, and Johannes [Akademischer Betreuer] Isselstein. "Effects of rising air and soil temperatures on the life cycle of important pathogens in oilseed rape (Brassica napus L.) in Lower Saxony / Magdalena Siebold. Gutachter: Hans-Joachim Weigel ; Johannes Isselstein. Betreuer: Andreas von Tiedemann." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://d-nb.info/1044414227/34.
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Siebold, Magdalena Verfasser], Andreas von [Akademischer Betreuer] Tiedemann, Hans-Joachim [Akademischer Betreuer] [Weigel, and Johannes [Akademischer Betreuer] Isselstein. "Effects of rising air and soil temperatures on the life cycle of important pathogens in oilseed rape (Brassica napus L.) in Lower Saxony / Magdalena Siebold. Gutachter: Hans-Joachim Weigel ; Johannes Isselstein. Betreuer: Andreas von Tiedemann." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://nbn-resolving.de/urn:nbn:de:gbv:7-11858/00-1735-0000-0015-9AB2-2-8.
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Kornder, Niklas Alexander. "Using Regression-Based Effect Size Meta-Analysis to Investigate Coral Responses to Climate Change." NSUWorks, 2016. http://nsuworks.nova.edu/occ_stuetd/415.
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Attempts to quantify the effects of ocean acidification and warming (OAW) on scleractinian corals provide a growing body of response measurements. However, placing empirical results into an ecological context is challenging, owing to variations that reflect both natural heterogeneity and scientific bias. This study addresses the heterogeneity of climate change induced changes in coral recruitment and calcification. To discern scientific bias and identify drivers of the remaining heterogeneity, 100 publications were analyzed using a combination of weighted mixed effects meta-regression and factorial effect size meta‑analysis. A linear model was applied to quantify the variation caused by differing stress levels across studies. The least squares predictions were then used to standardize individual study outcomes and effect size meta-analysis was performed on original and standardized outcomes separately. On average, increased temperature significantly reduces larval survival, while ocean acidification impedes settlement and calcification. Coral resistance to OAW is likely governed by biological traits (genera and life cycle stage), environmental factors (abiotic variability) and experimental design (feeding regime, stressor magnitude, and exposure duration). Linear models suggest that calcification rates are driven by carbonate and bicarbonate concentrations, which act additively with warming. Standardizing outcomes to linear model predictions proved useful in discerning strong sources of scientific bias. The approach used in this study can improve modelling projections and inform policy and management on changes in coral community structure associated with the expected future intensification of OAW.
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Zuru, Abdullahi Abdu. "Evaluation of kinetic parameters and investigation of reaction mechanisms using rising temperature thermogravimetric technique." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315456.
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Magagula, Sifiso Innocent. "The effect of organic peroxides on the molecular composition of heterophasic ethylene-propylene impact copolymers." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97850.
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Thesis (MSc)--Stellenbosch University, 2015.ENGLISH ABSTRACT: Heterophasic ethylene-propylene copolymers, also known as impact polypropylene (PP) copolymers (IPCs) or heterophasic copolymers (HECOs), are a unique group of polyolefins produced through the copolymerisation of ethylene and propylene, with the aim of improving the impact properties of the PP homopolymer at low temperatures. Therefore, this polymer comprises of a PP homopolymer matrix with a dispersed rubbery copolymer phase. Due to their unique properties, HECO polymers have become commercially important materials, with a wide range of applications. Therefore a fundamental understanding of the processes and chemistry that affects their final macroscopic properties needs to be expanded. The main focus of this investigation was to understand why specific organic peroxides influence or interact differently with the various phases of HECO polymers, in order to utilize their properties to obtain HECO polymers with optimal and desired properties. Two HECO polymers with different ethylene contents were fractionated into three fractions (30, 100 and 130 °C), using preparative temperature rising elution fractionation (P-TREF). Each individual TREF fraction was degraded with two different types of organic peroxides, and then characterised using four different analytical tools. The changes in the molecular structures of the different fractions were investigated by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The changes in comonomer sequence distributions were investigated by carbon 13 nuclear magnetic resonance spectroscopy (13C-NMR). Moreover, the degradation of the different fractions was investigated by high temperature size exclusion chromatography (HT-SEC). The investigation showed that the HECO polymers with different ethylene contents were uniquely altered. It was evident that the ethylene content influenced the degradation behaviour of the HECO polymers. The ability of the peroxide to affect certain regions of the HECO polymer more than others is highly dependent upon its miscibility with certain regions of the HECO polymers. The “visbreaking” efficiency of a specific organic peroxide appears to be primarily dependent on the number of “peroxy” groups it contains in its molecular structure. Stellenbosch University https://scholar.sun.ac.za
AFRIKAANSE OPSOMMING: Heterofase etileen-propileen ko-polimere, ook bekend as impak PP ko-polimere (IPCS) of heterofase ko-polimere (HECO), is 'n unieke groep poliolefiene geproduseer deur die ko-polimerisasie van etileen en propileen, met die doel op die verbetering in die impak eienskappe van die PP homopolimeer by lae temperature. Hierdie polimeer bestaan dus uit 'n PP homopolimeer matriks met 'n verspreide rubberagtige ko-polimeer fase. As gevolg van hul unieke eienskappe, is HECO polimere van kommersiële belang, met 'n wye verskeidenheid van toepassings. 'n Fundamentele begrip van die prosesse en chemie wat die finale makroskopiese eienskappe beïnvloed moet dus uitgebrei word. Die hooffokus van hierdie ondersoek was om te verstaan waarom spesifieke organiese peroksiede verskillende invloede en interaksies met die verskillende fases van HECO polimere het, om sodoende van hul eienskappe gebruik te maak om HECO polimere te verkry met optimale en gewenste eienskappe. Twee HECO polimere met verskillende etileen inhoud was gefraksioneer in drie fraksies (30, 100 en 130 °C), met behulp van preparatiewe temperatuur styging eluering fraksionering (P-TREF). Elke individuele TREF fraksie was gedegradeer met twee verskillende tipes organiese peroksiede en daarna gekarakteriseer deur vier verskillende analitiese metodes. Die veranderinge in molekulêre strukture van die verskillende fraksies was geondersoek met behulp van Fourier transform infrarooi spektroskopie (FTIR) en differensiële skandering kalorimetrie (DSC). Die veranderinge in ko-monomeer volgorde distribusie was bestudeer deur middel van kern magnetiese resonans spektroskopie (KMR). Verder was die degradasie van die verskillende fraksies met behulp van hoë temperatuur grootte uitsluitingschromatografie (HT-SEC) bestudeer. Die ondersoek het getoon dat die HECO polimere met verskillende etileen inhoud uniek gedegradeer was. Dus is dit duidelik genoeg dat die etileen inhoud die degradasie gedrag van die HECO polimere beïnvloed het. Die vermoë van die peroksied om sekere areas van die HECO polimeer meer as ander te beïnvloed is hoogs afhanklik van die mengbaarheid met sekere areas van die HECO polimere. Die "visbreking" doeltreffendheid van 'n spesifieke organiese peroksiede is meestal afhanklik van die aantal "peroksie" groepe in die molekulêre struktuur.
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Hailesilassie, Biruk. "Morphology Characterization of Foam Bitumen and Modeling for Low Temperature Asphalt Concrete." Doctoral thesis, KTH, Byggnadsmaterial, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-183105.
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Development of new asphalt technologies to reduce both energy consumption and CO2 production has attracted great interest in recent years. The use of foam bitumen, as one of them, is attractive due to the low investment and production cost. Formation and decay of foam bitumen is a highly dynamic temperature dependent process which makes characterization difficult. In this thesis, new experimental tools were developed and applied for characterizing the foam bitumen during the hot foaming process. One of the main goals of this study was to improve understanding and characterization of the foam bitumen formation and decay. X-ray radiography was used to study the formation and decay of foam bitumen in 2D representation. The results demonstrate that the morphology of bubble formation depends on the types of bitumen used. Moreover, theoretical investigation based on the 3D X-ray computed tomography scan dataset of bubble merging showed that the disjoining pressure increased as the gap between the bubbles in the surface layer (foam film) decreased with time and finally was ruptured. Examining the foam bitumen stream right at the nozzle revealed that foam bitumen at a very early stage contains fragmented pieces of irregular size rather resembling a liquid than foam. The result from thermogravimetric analysis demonstrated that residual water content depends on the initial water content, and was found to be between 38 wt% and 48 wt% of the initial water content of 4 wt% to 6 wt%. Moreover the influence of viscosity and surface tension on bubble shape and rise velocity of the bubbles using level-set method was implemented in finite element method. The modeling results were compared with bubble shape correlation map from literature. The results indicated that the bubble shapes are more dependent on the surface tension parameters than to the viscosity of the bitumen, whereas the bitumen viscosity is dominant for bubble rising velocity.QC 20160303
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Martin, M. J. "Models of the interactive effects of rising ozone, carbon dioxide and temperature on canopy carbon dioxide exchange and isoprene emission." Thesis, University of Essex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339238.
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De, Sassi Claudio. "Biotic interactions in a changing world: the role of feeding interactions in the response of multitrophic communities to rising temperature and nitrogen deposition." Thesis, University of Canterbury. School of Biological Sciences, 2012. http://hdl.handle.net/10092/6599.
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Global warming and increasing atmospheric nitrogen deposition are ranked as second and third most important global drivers of biodiversity loss. Widespread species losses have deep implications for the functioning of ecosystems, the delivery of essential ecosystem services and their resilience to future environmental perturbations.
There is growing recognition that interactions between species play a crucial role in determining the response of ecosystems to global environmental changes. Moreover, evidence of synergistic effects between global change drivers has prompted numerous calls to integrate multiple drivers in ecological research. Nevertheless, empirical studies assessing the impacts of temperature and nitrogen on communities at multiple trophic levels are largely absent. This thesis explores the effects of temperature and nitrogen on a tri-trophic system comprising plants, herbivores and natural enemies. The first chapter shows impacts of the drivers on the composition and phenology of an herbivore community. The second chapter highlights changes in biomass under the treatments at three trophic levels. The third chapter explores, for the first time, the impacts of temperature and nitrogen on quantitative food webs. Finally, the last data chapter uses body size as an important species trait to gain insights on the mechanisms causing shifts in food web structure.
The key findings of this thesis were i) trophic interactions largely mediated the effects of both global change drivers ii) In particular, strong bottom-up effects determined the system response, with herbivores responding positively and consistently more so than plants and parasitoids in particular. However, iii) this contrasting response was not explained by a phenological mismatch. iv) Food-web structure responded to the changes in composition of herbivores and parasitoids, but shifts in interaction structure did not affect the resilience of the food. However, temperature and nitrogen impacted host-parasitoid food-web structure by altering the response of parasitoid species to host density and size structuring, which is likely to bear consequences on host-parasitoid co-evolution and future food-web architecture and stability. Finally, v) we found frequent, non-additive interactions between the global change drivers. We conclude that co-occurring temperature and nitrogen are likely to alter food-web structure and overall ecosystem balance, with increasing herbivore dominance likely to have important implications for ecosystem functioning and food-web persistence.
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Keulder, L. "The effect of molecular composition on the properties of linear low density polyethylene." Thesis, Stellenbosch : University of Stellenbosch, 2008. http://hdl.handle.net/10019.1/2929.
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Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2008.In this study linear low density polyethylene (LLDPE), a copolymer consisting of ethylene and 1-butene, was fractionated by the use of temperature rising elution fractionation (TREF). These fractions were then analyzed by crystallisation analysis fractionation, 13C NMR, high temperature size exclusion chromatography and DSC. The molecular distribution of the polymer was investigated. It was found that the polymer had a very broad distribution in its chemical composition. From these results it was also clear that the catalysts used for the polymerisation consist out of different active sites, producing chains with different molecular architecture. Subsequently the polymer was fractionated again by TREF and certain fractions were removed and the remaining material recombined. The removed fractions and recombined material were analyzed by 13C NMR, high temperature size exclusion chromatography, DSC and DMA. The results were compared with the bulk material and from this we could conclude the influence of the fractions removed on the material properties. This gave us more information on the influence of the chemical structure of the polymer on its mechanical properties. It was clear that by removing certain fractions with a certain chemical composition, the properties of the polymer are significantly influenced.
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Becker, Camila Coelho. "Data de plantio de gladíolo para comercialização em dois picos de consumo no clima atual e em climas futuros no Rio Grande do Sul utilizando o modelo." Universidade Federal de Santa Maria, 2017. http://repositorio.ufsm.br/handle/1/11354.
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Gladiola (Gladiolus x grandiflorus Hort.) is an important cut flower cultivated under field conditions. The air temperature is the main abiotic factor that drives their phenology, therefore the scheduling flowering of gladiola for target markets by defining the optimum planting date. The objective this study was determine the optimum planting date of gladiola aiming harvest spikes for selling on All Souls’ Day and Mother’s Day under current climate and in CMIP5 scenarios in the Rio Grande do Sul State. The PhenoGlad model was used for simulates the developmental stages of gladiola and plant injuries by heat and frost. For simulates the optimum planting date under current climate, input data in the model was minimum and maximum daily temperature of 55 years (1961-2015) from eighteen weather stations across the State. Once optimum planting date was simulated for each maturation group and weather station, with all years, the planting date was averaged for each El Niño Southern Oscillation (ENSO) phases to access the ENSO effect on the optimum planting date of gladiola. For simulates the optimum planting date under climate scenarios, input data in the model was minimum and maximum daily temperature of the 32 grid points in the State, for RCP2.6, RCP4.5 and RCP8.5 scenarios. The optimum planting date in the future period (2070-2098) was presented as anomalies (difference between the optimum planting date and average optimum planting date in the baseline period (1976-2005) for each grid point and maturation group. The percentage of years with damage was also presented as anomalies. The phenomenon ENSO affects the optimum planting date of gladiola for harvesting on All Souls’ Day. For this growing season, planting date was anticipated for La Niña years (low temperatures) and delayed for Very Strong El Niño (high temperatures). For Mother’s Day, only Very Strong El Niño events affect the development of the gladiola, but different of the growing season for All Souls’ Day, planting date was anticipated for Very Strong El Niño years, and delayed for others ENSO phases. As well as for Very Strong El Niño years, for harvesting on All Souls’ Day, the optimum planting date was delayed in the climate scenarios, due to shortening of the cycle on rising temperatures conditions. For Mother’s Day, the average air temperature exceeded the optimum temperature of the crop in the warmest regions of the State. In these regions, the anomalies of the optimum planting date were negatives because the development rate decreased, delaying flowering. The risk of injuries by heat is more severe in the growing season for harvesting on All Souls’ Day, mainly in the scenario RCP8.5 and warmest regions, where the anomalies reached +70% of years. This results will provide subsidies for the production expansion for others regions of the State in order to harvesting spikes for selling on All Souls’ Day and Mother’s Day.O gladíolo (Gladiolus x grandiflorus Hort.) é uma importante flor de corte cultivada a céu aberto. A temperatura do ar é o principal fator abiótico que dirige sua fenologia, portanto os agricultores agendam o florescimento de gladíolo para os picos de demanda, definindo a data ótima de plantio. O objetivo desse estudo foi determinar a data ótima de plantio de gladíolo visando colheita das espigas para comercialização no Dia de Finados e Dia das Mães no clima atual e em cenários climáticos do CMIP5 no Rio Grande do Sul. O modelo PhenoGlad foi usado para simular os estágios de desenvolvimento do gladíolo e danos nas plantas por calor e geada. Para simular a data ótima de plantio no clima atual, os dados de entrada no modelo foram temperatura mínima e máxima diária do ar de 55 anos (1961-2015) de dezoito estações meteorológicas distribuídas no estado. Uma vez que a data ótima de plantio foi simulada para cada grupo de maturação e estação meteorológica, com todos os anos, foi realizada a média da data ótima de plantio para cada fase do El Niño Oscilação Sul (ENOS) para acessar o efeito do fenômeno na data ótima de plantio de gladíolo. Para simular a data ótima de plantio nos cenários climáticos, os dados de entrada no modelo foram temperatura mínima e máxima diária do ar de 32 pontos distribuídos no estado, para os cenários RCP2.6, RCP4.5 and RCP8.5.A data ótima de plantio no período futuro (2070-2098) foi apresentada como anomalias (diferença entre a data ótima de plantio do período futuro e a média da data ótima de plantio do período baseline (1976-2005) para cada ponto e grupo de maturação. A porcentagem de anos que ocorreu danos também foi apresentada como anomalias. O fenômeno ENOS afeta a data ótima de plantio de gladíolo para colheita no Dia de Finados. Neste período de cultivo, a data de plantio foi antecipada em anos de La Niña (temperaturas baixas) e atrasada em anos de El Niño muito forte (temperaturas altas). Para o Dia das Mães, somente eventos de El Niño muito forte afetaram o desenvolvimento do gladíolo, mas diferente do período de cultivo de Finados, a data de plantio foi antecipada para anos de El Niño muito forte e atrasada para as demais fases do ENSO. Assim como para anos de El Niño muito forte no cultivo de Dia de Finados, a data ótima de plantio foi atrasada nos cenários climáticos devido ao encurtamento do ciclo em condições de aumento de temperatura. Para o período de cultivo de Dia das Mães, a temperatura média ultrapassou a temperatura ótima da cultura nas regiões mais quentes do estado. Nessas regiões, as anomalias de data de plantio foram negativas porque a taxa de desenvolvimento diminuiu, atrasando a floração. O risco de danos nas espigas por calor é maior no cultivo de Dia de Finados, principalmente no cenário RCP8.5 e nas regiões mais quentes, onde as anomalias atingiram +70% dos anos. Esses resultados proporcionarão subsídios para a expansão da produção de gladíolo para outras regiões do estado, visando colheita das hastes para comercialização no Dia de Finados e no Dia das Mães.
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Risius, Steffen [Verfasser], Andreas [Akademischer Betreuer] Dillmann, Andreas [Gutachter] Dillmann, and Martin [Gutachter] Rein. "Development of a time-resolved quantitative surface-temperature measurement technique and its application in short-duration wind tunnel testing / Steffen Risius ; Gutachter: Andreas Dillmann, Martin Rein ; Betreuer: Andreas Dillmann." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://d-nb.info/1163109029/34.
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Finnsdóttir, Rán. "Effects of sheep grazing on plants adapting to climate change and rising temperatures." Thesis, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-427081.
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Global warming is expected to affect the arctic harsher than other regions of the globe. Many plant species will face conditions that contradict their adaptations in a warming climate. Changes in habitat can lead to drastic changes in biodiversity as well as exerting a strong selective pressure for plants to evolve and adapt quickly. Herbivore grazing in the arctic also affects plant ecosystems e.g. by lowering biodiversity and changing species composition and may influence their response to warming. The aim of this study was to examine whether grazing influences plants’ adaptation to rising temperatures. Geothermally warmed areas have been used as in situ proxy systems for effects of warming climates on ecosystems. Grændalur, a geothermally warmed valley in southwest Iceland, was used as a study site to explore the effects of warming and grazing on ecosystems. Three soil temperature gradient transects were established there and each transect has six fenced-off plots, at different soil temperatures (ambient +0, +1, +3, +5, +10 and +20°C), and paired plots outside the fence that were grazed by sheep. Species richness, evenness, Shannon-Wiener and Simpson’s diversity, species cover, and composition as well as plant height were measured in these plots inside and outside the fence. In addition, flowering and vegetative Ranunculus acris (meadow buttercup) individuals were counted in each plot to assess grazing effects on flowering success. Grazing did not influence the plant community response to warming. Rising temperature decreased species richness and both Shannon-Wiener and Simpson’s diversity, and drove changes in community composition. Plant height increased with rising temperatures but decreased with grazing. Grazing also significantly reduced R. acris flowering. These results highlight the need for sustainable grazing management in Iceland, as well as the significance global warming has for plant communities.
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Siebold, Magdalena. "Effects of rising air and soil temperatures on the life cycle of important pathogens in oilseed rape (Brassica napus L.) in Lower Saxony." Thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-0015-9AB2-2.
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Ashforth, Dawn. "Potential interactive impacts of declining ambient calcium levels, reduced algal biomass, and rising summer water temperatures on Daphnia pulex : a laboratory study of multiple stressors /." 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR19705.
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Thesis (M.Sc.)--York University, 2006. Graduate Programme in Biology.Typescript. Includes bibliographical references (leaves 88-108). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR19705
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Huang, Yen-po, and 黃彥博. "Luminous Control Considerating with LED Temperature Rising." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/pu8r54.
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碩士國立臺灣科技大學
電機工程系
105
The high-quality vegetables can be steadily produced all the year round by artificial control in plant factory. And the environment parameters, like temperature, humidity illumination and concentrations of carbon dioxide, also are planned in it. In plant factory, the lighting system is a key component since lighting is very important for the healthy growth of plants. On the other hand, operating temperature affects the characteristics of LEDs. Light intensity and lifespan both decrease as the temperature increases; hence, it is important to take the temperature into account when designing LED driving circuits. In this thesis, a LED driving circuits with temperature compensation suitable for plant factory is proposed. The temperature compensation is realized using Raspberry Pi 3. When the operating temperature of LEDs reaches the threshold value, output current will start to decrease automatically. To validate the correctness of the presented system, an 7 W prototyping circuit is first built and experiments are carried out using this platform. According to the experimental results, the constructed system can maintain LEDs' stable operation, and the illumination level can be kept with 80%.
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Shan, Chun-wu, and 單淳武. "Temperature Rising Analysis and Simulation of a Microspeaker." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/12670265810715763119.
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Su, Chia-Yi, and 蘇家毅. "Study on Dynamic Temperature Rising Characteristics of High Speed Rotating Bolt." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/5u4n26.
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碩士國立勤益科技大學
機械工程系
106
Precision locked nut is an indispensable part of the ball screw and the precision high rotating spindle. If the ball screw or the precision high rotating spindle bearing is not subject to axial force preloading, the ball in the bearing will slide so that the bearing inner ring track and the outer ring track will cause greater friction. However, the high temperature will generate under long-time rotation or high-speed rotation; the temperature rise will affect the overall precision and life of the machine tools or special machine. When the precision locked nut was locked on the bearing by a proper axial force preload, the balls in the bearing will roll between the inner ring track and the outer ring track of the bearing so that is reduce the sliding friction and causing a lesser temperature rise. Machine tools or special machines will cause vibration during heavy cutting and the bearing temperature to rising, after a long period of vibration, the tightening force of the precision lock nut may be reduced, which indirectly affects the bearing's pre-axial force. The temperature rise will reduce the axial force of the ball screw or the precision high rotating spindle. An experiment is simulate by simulating a real dynamic testing machine, and the characteristic equation of temperature rise prediction was established. In addition, Taguchi method design experiments are conduct to investigate the installation of precision lock nut under different conditions, to reduce the effect of temperature rising on the reduction of axial force. In this study, the quality characteristics are axial ratio of temperature rise, temperature after bearing testing, axial displacement, ratio of axial force and ratio of anti-loosening torque. The control factors are the fit clearance of the thread, the viscosity of the lubricant, and the bearing contact angle. The best quality characteristics were obtain through the Taguchi method.
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LIU, SHI-HAO, and 劉士豪. "Electrical Protection Against Abnormal Temperature Rising by Using Temperature Monitoring Device-A Case Study of Tracking." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/sawnw5.
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碩士嘉南藥理大學
職業安全衛生系
105
In order to reduce the incidence rate of electric fire effectively, the study aims to investigate how to effectively control the continuously abnormal temperature rise that may cause to electric fire when deposit electric conduction occurs. By examining the domestic laws and regulations, recent patent-related inventions, and relevant literature studies, and coordinating with the experiment of deposit electric conduction, investigation of control as well as warning effectiveness of the temperature control device with forewarning and protecting function when deposit electric conduction occurs is conducted in this study. By reviewing the domestic laws and regulation, it is found that regulations about prevention measurement for deposit electric conduction is very rare; in other words, the study discovers that there is room for improvement to the domestic laws and regulations of electrical safety. The objective of the study is firstly to investigate the optimum temperature control of deposit electric conduction that is caused by the dust and then to proceed the simulation experiment of deposit electric conduction by applying dust as the medium in order to discuss the phenomenon of deposit electric conduction; following with application of the temperature control device with forewarning and protecting function to control the abnormal temperature rise in the circuits. In accordance with the experiment method of Japan JIS C 8303 on the plug and socket heating-up, and after analysis and investigation on the control temperature points under various condition of deposit electric conduction, the study discovers that the electrolyte can easily cause to vigorous reaction to the deposit electric conduction while the other water-content mediums reacted under the mild condition; the temperature of the system is also heated up by gradual heat accumulation. Although the plug and socket are not under burning condition, the heat may cause to fire while the combustible materials in the surroundings start to burn. The response time of the vigorous deposit electric conduction is short, however, it may melt the materials of the plug and socket which may easily lead to the short-circuit of the wires in the long term. Consequently, it is important to clean the plug and socket regularly and coordinate with effective warning as well as protecting device for secure and safe life.The results of this research could serve as references for the design as well as the manufacturing-related protection installment for the industry in order to not only set up the accurate methods to prevent from deposit electric conduction but also correct the habits of using the electrical appliances.
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LUO, SHIH-HSIUNG, and 羅世雄. "Applying Taguchi method on the research for factors of connector temperature rising." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/08043525688475895194.
Full textAbstract:
碩士國立臺灣科技大學
管理研究所
99
For a long time, the industries of computer, communication and consumer electronic are the core industries in Taiwan; they are usually categorized as 3C industry. Harnesses / connectors are very important parts used in 3C products; hence, harness / connector industry is very important in Taiwan. Most of harness / connector makers in Taiwan are SMEs (small and medium enterprises). These makers have limited sources and business capacities usually. They shall enhance their own competitive capacities to face challenges in supply chain. Requirements of customer are getting more rigid, the progress is a challenge to SMEs. Taguchi method is an excellent tool of DOE (Design of experiment); it can effectively and efficiently help SMEs to design and improve products to meet customer requirements. Temperature rising test is used to evaluate connector safety, the key factors of temperature rising for harness / connector are also very important when connector/ harness applicators to design power circuit into their products. Connector / harness makers shall find out the key factors of the temperature rising, and reduce the rising in design and they may provide recommendations to their customers. Unfortunately, it is pretty difficult to apply regular DOE for the test since there are many factors and the test is time-consuming, furthermore, making samples for the test is not easy as well. This study applies Taguchi method to find out key temperature rising factors of connectors / harness. According to the study result, the key factors are (1) current, (2) wire AWG, (3) wire length and (4) hole position. Besides, this study generalizes a helpful procedure to apply Taguchi method for harness / connector makers.
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Fan, Yu-Jun, and 范淯竣. "Two Solutions for the Solar Module Efficiency Degradation due to Temperature Rising." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/8h94dt.
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碩士崑山科技大學
光電工程研究所
106
In order to solve the solar module efficiency degradation due to temperature rise, two solutions are proposed in this paper. This paper demonstrates two solutions for improving the PV modules efficiency degradation due to temperature rise. One is to use water spraying toward the module back to cool down the module temperature. The other is to attach curved copper hollow tube on the module back and let the water circulate within it where a water pump is used to push the water, and the module temperature is decreased due to heat exchange. In the first solution, the cooling mechanism is activated when the monitored temperature of the module is over 40℃. The microcontroller will release the solenoid valve, and the water from high water tower will start to circulate in the copper tube. The potential energy of the water will be transferred into the kinetic energy from which the water can flow in the copper tube. Measured data shows that the power efficiency degradation may decrease from 9.66% down to 5.24%. The microcontroller just consumes only 0.1W to release the valve. Related to the second solution, traditional solar heating water system uses the solar radiation to heat the water in the vacuum tube, and the heat convection occurs between the vacuum tube and the upper heat water tank so that we have hot water in tank for bathing in night. In the second solution, the solar radiation is absorbed by PV modules first, about 20% energy is transformed into electricity, and some other energy is to increase the modules temperature. Now, we attach the copper hollow tube onto the modules back, the temperature of the circulating water will be increased by heat conduction. Through thermal convection, the hot water will be stored in the upper hot water tank. Consequently, we got not so hot water like traditional system, but we have decreased the module temperature and increased the electro-optical transformation efficiency. The 1.68% efficiency improvement is not obvious, but water temperature can rise up to 39.94℃ for bathing at PM 1:00, when the air temperature is 27.5℃.
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Lin, Chih-Long, and 林志龍. "The Mobility of the White Organic Light Emitting Diode Affected by Temperature Rising." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/62fp9u.
Full textAbstract:
碩士國立臺北科技大學
光電工程系研究所
99
This thesis research is to experimentally investigate the minority carrier mobility of a white organic light-emitting diode (WOLED) under the influence of temperature rising by using modified transient electroluminescence (TEL) measurement. Our investigating results reveal that the mobility of a WOLED is 3.58x10-5(cm2/Vs) in average at room temperature and around 5.63x10-4 (cm2/Vs) in average as measured in 30, 35, and 40oC respectively. It is also indicated that the mobility data increases from 2.15x10-4 to 9.37x10-4 (cm2/Vs) as the measured WOLED is maintained in 30, 35, and 40oC for 40 minutes.
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FU, JIUN-HAU, and 傅軍皓. "The Influence of Brake Disc Hole Size on Temperature-Rising and Brake Force." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/6qsn99.
Full textAbstract:
碩士南臺科技大學
機械工程系
104
Abstract In this study, In this study, the cooling effect of ventilated disc with different hole size on the contact surface, and the brake performance at various working temperature are explored, in which the complete-planar (original) disc is as a benchmark. Using an experimental way, the brake force test and disc temperature-rising test are respectively performed, in which a passenger car is used as an object. In these tests, besides the original ventilated disc, the discs with different diameters of drilled holes on the surface are respectively 3, 4, 5, 6 mm etc. are all chosen as the variable. And, the brake pads which contact with these discs are used at the same. In the brake force measurement test, the influence of both disc hole size and preset operating temperature on the brake performance is evaluated. In the disc temperature-rising test, the change of temperature rise is recorded at a constant pedal force condition. It is obtained from these tests that the hole size of the brake disc has a certain degree of influence on the braking performance and the heating rate. It can be seen that the disc with larger hole size gives the lining larger shear force, thus the brake force is larger among these hole-drilled discs. However, compared with complete-planar disc, the hole-drilled discs lead to smaller brake force. Maybe, there is a larger contact area between brake pads and disc, and the effect influenced by the factor, contact area is a little larger than the factor, disc with drilling hole. Furthermore, in the temperature rising tests, both vehicle speed and disc hole size will affect the heating rate. The disc with larger hole will increase the heating rate due to smaller heat capacity, but it has larger cooling area correspondingly, it can effectively delay the heating rate. It is noted that when the vehicle runs at high speed, the heat convection between disc and air is stronger and can effectively reduce the temperature rise. Keywords: friction coefficient, brake, disc, temperature.
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(Paul), Hai Pin Kuo, and 郭海濱. "The Research of Three Phase Induction Motor with Interval Over Loading Temperature Rising Characteristic." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/9htmw3.
Full textAbstract:
碩士崑山科技大學
機械工程研究所
96
The maximum output efficiency of three phase induction motor is normally designed at 75% to 125% of loading rate. Because under such condition the motor’s constant loss is equal to the loading loss, and the maximum power factor efficiency is at 125% to 150% of the loading rate. When we need to use such motor, especially big capacity ones, in interval power supply environment, we suffer from high cost and low efficiency when the loading is not fully occupied. Therefore, use the 150% of loading rate to get the maximum output efficiency will be more economy of scale and save the energy than use a bigger motor but lighter loading in demand. This thesis introduces a new method to apply to this condition. The method is loading an over load of rate to gain the temperature approach the maximum isolated temperature according to its degree of cooper wire. Then unloading and loading again repeatedly to create a stable constant interval to form a periodic table. From the experiment it has proven using this method will never overheat the isolated temperature. And compared the way use the time chart that offered by the periodic table with loading and unloading repeated in condition of interval from beginning can save energy about 46% and 51% less experiment time. Without the time chart from the periodic table will waste more energy and experiment time because the time chart can’t be predicted in advance
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Shen, Po-Tse, and 沈柏澤. "A Study of the Temperature Rising and Thermal Deformation on Triaxial CNC Machine Tools." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8p9sc6.
Full textAbstract:
碩士國立高雄第一科技大學
電機工程研究所碩士班
105
In this age of advanced industrial, the issue of temperature change and thermal deformation of the CNC machine tool gradually attention. This study establishes a temperature estimation model, which can estimate the temperature of 51 locations of the CNC machine tools. As a result, the temperature sensor settings could be reduced. Moreover, as long as we have the working conditions, this model will be able to obtain the temperature change of the CNC machine tools before processing. At the same time, the estimated temperature is substituted into the thermal deformation model of this study to get the thermal deformation error before cutting. For increasing the accuracy of the thermal deformation model, the temperatue estimation of tool and workpiece and the components of the warpage of base will added into it.
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Tzou, Ching-Laing, and 鄒慶莨. "Temperature Rising Forecasting with the Varying Loading and Sensitivity Analysis of Distribution Main Transformer." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/97242704312335639281.
Full textAbstract:
碩士和春技術學院
電機工程研究所
96
Expectation the voltage rating, current rating and so on, the inside temperature limitation is the key role to the continues operation of the electrical equipment. It is integrated the temperature measurement with infrared rays, logger and database to form the automated data collection system. To measure the loadings, harmonics, transformer’s inside temperature and so on with the 22.8kV in the underground systems. Using the MATLAB construct the ANN network to forecast the inside temperature of distribution systems. With the three types of different input variables for 6, 11 and temperature sensitivity to construct different ANN structures for forecasting of distribution transformers. Base on the similar curve to distinguish for weekday, weekend and Sunday three-day types. And according to the loadings rising or reducing tendency are divided three different periods for peak, half-peak and off-peak periods to construct three different ANN structures. By the training data fed into the ANN to form the converged networks. With the designed recall data input the converged networks to find the input variables sensitivity. To combine the input variables sensitivity and relative input data difference can reach the inside temperature forecasting of the distribution system. With test results, the weekday the relative error of peak period is 0.802%, half-peak is 1.081%, and the off-peak is 0.783%, the weekday average relative error is 0.821% that improved ANN method causes the error to be small effectively and make the accuracy to be highly. Consideration the total harmonic voltage and harmonic current will influence the reduction rate of distribution transformer capacity. With the results, on weekday in peak period P is 0.9 P.U., Ithd is 8 P.U., Vthd is 1 P.U. and PF is 1, the distribution transformer capacity eduction rate is 24.02%. With PF is 0.91, the distribution transformer capacity reduction rate is 26.62%. And PF is 0.87, the distribution transformer capacity reduction rate is 25.88%.
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Huang, Ting-Zhang, and 黃亭章. "Thermal Network Analysis for Bearing Chamber of Vertical Motor and Estimation of Temperature Rising for Bearings." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/53445075297576486748.
Full textAbstract:
碩士中原大學
機械工程研究所
94
In this study, the method of predicting temperature distribution has been established in the design of cooling system for the bearing chamber to decrease the bearing temperature. The bearing chamber is assumed to two-dimension symmetrical model which is assumed symmetrical about vertical axis and is divided into different parts based on heat conduction of structure, frictional heat of bearing, boundary condition, forced air cooling, cooling pipe and heat exchange. The representative nodes were set in each part and the temperature distribution of bearing chamber are obtained by using thermal network method to perform analysis of heat equilibrium. The temperature of bearing chamber is varied with the friction-induced heat which is influenced by the friction momentum and viscosity of lubrication oil. Therefore, this thesis utilizes the Newton-Raphson method to determine the temperature of bearing chamber. The value of viscosity depended on temperature varying can be yielded by substituting initial temperatures into the transform formula of the lubrication oil. Then, the friction momentum can also be yielded to compute heat generation according to the value of viscosity obtained. Finally, the heat generation is substituted into the equations of thermal equilibrium iteratively to progress convergent analysis until iterative errors are small enough and satisfied the precision demand. The thermal deformations of a bearing are induced due to the heat generation from friction and magnet in motor. Also, lower performance of bearing is yielded since the distribution of temperature is not uniform. Consequently, the cooling systems including fan and pipe are adopted in this thesis to decrease temperature rising in the bearing chamber. Furthermore, the life of a motor can be extended due to discarding considerable heat by increasing flow quantity from cooling systems.
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Lu, Chien-Ming, and 盧建銘. "Effect of Sintering Rising Temperature Slope in Wick Manufactured for Loop Heat Pipe with Flat Evaporator." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/70701179540159460535.
Full textAbstract:
碩士中華科技大學
飛機系統工程研究所在職專班
102
Loop heat pipe (LHP), which are generally and widely used with cylindrical evaporators, have a great potential for applications of spacecrafts and electronic cooling due to the advantages of high transfer capacity, low thermal resistance and long transport distances. However, the cylindrical evaporators of loop heat pipes cannot work on a flat thermo-contact surface without saddle. The saddle not only creates an extra thermal resistance but also makes evaporators less isothermal. To avoid the above disadvantages, we adopt the flat evaporators of loop heat pipe. This investigation examines the effect of the effect of the sintering temperature curve in manufacturing nickel powder capillary structure (wick) for a loop heat pipe (LHP) with flat evaporator. The sintering temperature curve is composed of three regions: a region of increasing temperature, a region of constant temperature, and a region of decreasing temperature. The most important region is the increasing temperature region, as the rate of temperature increase directly affects the performance of the wick.When the slope of the region of increasing temperature is 0.8 (equivalent to 8℃/min), the structure of the manufactured wick is complete, with the best heat transfer performance result. Experimental resultsshowed that the optimal heat transfer performance is 160W, the minimal total thermal resistance is approximately 0.43℃/W, and the heat flux is 17W/cm2; the optimal wick manufactured has an effective pore radius of 5.2 μm, a permeability of 8.5×10-13m2, and a porosity of 64%.
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Chen, Yung-Han, and 陳永翰. "The Study of a Precision Humidity and Rising Temperature Control System for the Chamber under No Load Condition." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/36908456482554504083.
Full textAbstract:
碩士逢甲大學
自動控制工程所
98
In this study, the characteristics of moist air in the chamber are estimated, and an optimal control path for energy saving is scheduled for precision humidity control under rising temperature. The system is different from the ordinary temperature-humidity PID control system. It directly controls the required water vapor and the heat energy to give more precise humidity control and energy-saving for the chamber under no load condition. To reach this goal, a precision humidifier is designed as well. The result shows that the system can not only have the good effect about precision humidity control but save energy and water to 86% and 87% at humidity and raising temperature.
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Hsueh, Ynug-Chun, and 薛永浚. "Morphology and electrical properties of Ga2O3 films prepared under different temperature rising scheme by rtheotaxial growth and thermal oxidation." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/30741281078015857505.
Full textAbstract:
碩士國立成功大學
化學工程學系碩博士班
94
Abstract A large number of gas sensors are used with the progress of science and technology, the concern about living security and the consciousness of environmental protection. Among them, gallium oxide has the character of semiconductor and is stable under high temperature. Therefore, it is applied to detect the reducing gas frequently in recent years. This study uses rtheotaxial growth and thermal oxidation to prepare the gas sensor of gallium oxide. We probe into superficial morphology and influence of sensor properties in gallium oxide thin film that prepares under different preparing conditions, including the change of deposition rates, atmosphere of temperature rising, oxidation time, oxidation atmosphere and oxidation temperature. The experimental result shows, when deposition rates is quick, the particles on the surface of thin film gets bigger and smoother, but the sensitivity is worse. Not only the morphology of the surface but also the electrical properties change significantly with different atmosphere of temperature rising. Rising oxidizing temperature and increasing oxidizing time have just a little effect on superficial morphology of the thin films, but the process makes its electrical properties trend towards the P type. Each gallium oxide thin film prepared in different deposition rate has its own optimal operation temperature. Both the response time and the recovery time shorten as the operation temperature rises. Its sensitivity also increases with the rise for the concentration of ethanol.
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Lemordant, Léo. "Interactions between Vegetation and Water Cycle In the Context of Rising Atmospheric Carbon Dioxide Concentration: Processes and Impacts on Extreme Temperature." Thesis, 2019. https://doi.org/10.7916/D8156116.
Full textAbstract:
Predicting how increasing atmospheric carbon dioxide concentration will affect the hydrologic cycle is of utmost importance for water resource management, ecological systems and for human life and activities. A typical perspective is that the water cycle will mostly be altered by atmospheric effects of climate change, precipitation and radiation, and that the land surface will adjust accordingly. Terrestrial processes can however feedback significantly on the hydrologic changes themselves. Vegetation is indeed at the center of the carbon, water and energy nexus.
This work investigates the processes, the timing and the geography of these feedbacks. Using Earth System Models simulations from the Coupled Model Intercomparison Project, Phase 5 (CMIP5), with decoupled surface (vegetation physiology) and atmospheric (radiative) responses to increased atmospheric carbon dioxide concentration, we first evaluate the individual contribution of precipitation, radiation and physiological forcings for several key hydrological variables. Over the largest fraction of the globe the physiological response indeed not only impacts, but also dominates the change in the continental hydrologic cycle compared to either radiative or precipitation changes due to increased atmospheric carbon dioxide concentration. It is however complicated to draw any conclusion for the soil moisture as it exhibits a particularly nonlinear response.
The physiological feedbacks are especially important for extreme temperature events. The 2003 European heat wave is an interesting and crucial case study, as extreme heat waves are anticipated to become more frequent and more severe with increasing atmospheric carbon dioxide concentration. The soil moisture and land-atmosphere feedbacks were responsible for the severity of this episode unique for this region. Instead of focusing on statistical change, we use the framework of Regional Climate Modeling to simulate this specific event under higher levels of surface atmospheric carbon dioxide concentration and to assess how this heat wave could be altered by land-atmosphere interactions in the future. Increased atmospheric carbon dioxide concentration modifies the seasonality of the water cycle through stomatal regulation and increased leaf area. As a result, the water saved during the growing season through higher water use efficiency mitigates summer dryness and the heat wave impact. Land-atmosphere interactions and carbon dioxide fertilization together synergistically contribute to increased summer transpiration if rainfall does not change. This, in turn, alters the surface energy budget and decreases sensible heat flux, mitigating air temperature rise during extreme heat periods.
This soil moisture feedback, which is mediated and enabled by the vegetation on a seasonal scale is a European example of the impacts the vegetation could have in an atmosphere enriched in carbon dioxide. We again use Earth System Models to systematically and statistically investigate the influence of the vegetation feedbacks on the global and regional changes of extreme temperatures. Physiological effects typically contribute to the increase of the annual daily maximum temperature with increasing atmospheric carbon dioxide concentration, accounting for around 15% of the full trend by the end of the XXIth Century. Except in Northern latitudes, the annual daily maximum temperature increases at a faster pace than the mean temperature, which is reinforced by vegetation feedbacks in Europe but reduced in North America.
This work highlights the key role of vegetation in influencing future terrestrial hydrologic responses. Accurate representation of the response to higher atmospheric carbon dioxide concentration levels, and of the coupling between the carbon and water cycles are therefore critical to forecasting seasonal climate, water cycle dynamics and to enhance the accuracy of extreme event prediction under future climates in various regions of the globe.
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Yang, Shi Ren, and 楊世仁. "Variation of heat transfer coefficient on an oscillating circular cylinder during temperature-rising process with water vapor condensation in humid air flow." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/15225954756160881785.
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