Dissertations / Theses on the topic 'Temperature rate'
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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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Mansfield, Jonathan Mark. "Reaction behaviour from temperature dynamics." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339552.
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Cook, Frederick Philip. "Characterization of UHMWPE Laminates for High Strain Rate Applications." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/30849.
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The research presented in this thesis represents an effort to characterize the properties of ultra-high molecular weight polyethylene (UHMWPE). As a composite of polymers, the properties of UHMWPE are time-dependent. It is desired by research sponsors to know the properties of the material at high strain rates, in order to simulate the use of these materials in computer models. Properties believed to be significant which are investigated in this research are the tensile properties of lamina and laminates, and the interlaminar shear properties of laminates. The efficacy of using time-temperature superposition to shift tensile properties of the composite is investigated, and a novel apparent shear strength test is proposed and demonstrated. The effects of processing the material at various temperatures and pressures are also investigated.Master of Science
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Tanner, Albert Buck. "Modeling temperature and strain rate history effects in OFHC CU." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17143.
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Lodemore, Marion. "The development of temperature and heart rate rhythms in babies." Thesis, University of Leicester, 1993. http://hdl.handle.net/2381/34139.
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Chan, Hoi Houng. "The cavitation properties of liquids : temperature and stressing rate effects." Thesis, Swansea University, 2009. https://cronfa.swan.ac.uk/Record/cronfa42968.
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Norman, Sven. "The temperature dependence of ectotherm consumption." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-64098.
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The effect of temperature on predator and herbivore consumption is an important factor for predicting the effects of climate warming on ecosystems. The Metabolic Theory of Ecology (MTE) describes the temperature dependence of biological and ecological rates and states that metabolism is the fundamental biological mechanism that governs most observed patterns in ecology. This statement has been criticized empirically for a number of organismal traits and systematic deviations have been found. Here, a meta-analysis is performed on published temperature responses of ectotherm consumption. The mean effect of temperature on consumption was higher than the mean value predicted by proponents of the MTE and was highly variable. Some of this variation is explained by habitat type, where the consumption rates of marine organisms displayed stronger temperature dependence than for terrestrial and freshwater organisms. The frequency distribution of temperature dependencies is right skewed for consumption. Here, this skewness is explained by a methodological artefact as values close to “no effect” are more unlikely to be sampled than others when fitting the Arrhenius equation. In conclusion, the assumptions of the MTE do not hold for rates of consumption and marine organisms display a stronger temperature dependence compared to terrestrial and freshwater organisms.
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Amoruso, Kenneth. "Independent control of a molten stream temperature and mass flow rate." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40008.
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Singh, Suniti. "High rate anaerobic treatment of LCFA-containing wastewater at low temperature." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC2042.
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La hausse des prix des carburants et les incitations favorisant le marché des énergies renouvelables poussent le marché mondial de l'eau et les technologies des eaux usées vers la digestion anaérobie. Les gains financiers résultant de la réduction de l'empreinte de l'usine et du transport des boues constituent également des moteurs économiques importants. La croissance efficace des méthanogènes est la clé de la fonctionnalité AD, pour laquelle les températures mésophiles (30-35 ° C) ou thermophiles (48-55 ° C) et pH 6,8-7,2 sont optimales. Le goulot d'étranglement dans la polyvalence de la mise en œuvre de la DA est son inefficacité à des températures plus basses. Comme un énorme morceau de biosphère est en permanence à moins de 5 ° C, le développement du DLTA fournirait une meilleure efficacité énergétique pour le traitement des eaux usées dans les régions tempéréesFats, oil and grease (FOG) is a significant constituent in numerous wastewaters such as those in dairy industry. The hydrolysis of FOG results in the production of long chain fatty acids (LCFA) which destabilize the anaerobic treatment process due to their physico-chemical and microbial toxicity effects. Harnessing the high methanogenic potential of FOG necessitates effective treatment of high LCFA loads, wherein the feasibility of LCFA treatment at low temperatures has been not investigated up to now. The aim of this thesis was to study the feasibility of high-rate anaerobic treatment of LCFA-rich wastewaters at low ambient temperatures using a dairy wastewater matrix.The screening of mesophilic inocula for treatment of mixed LCFA containing synthetic dairy wastewater (SDW) in batch studies showed that granular sludge inoculum achieved faster and higher methane yields (76-82% of theoretical yield) than the two municipal digestates (1-72%) at both 20 and 10°C. The LCFA degradative capacity in the granular sludge inoculum was attributed to the presence of β-oxidizing bacteria from the family Syntrophaceae (Syntrophus and uncultured taxa), the acetotrophic activity from Methanosaeta and putative syntrophic acetate oxidizing bacteria (SAOB). Continuous high-rate treatment of SDW was found to be feasible in expanded granular sludge bed (EGSB) reactors at 20°C (hydraulic retention time (HRT) 24 h, LCFA loading rate (OLR) 670 mgCOD-LCFA/L·d, 33% COD-LCFA) with a COD removal of 84–91% and methane yield of 44–51%. SDW feeding for longer than two months resulted in LCFA accumulation, which led to granular sludge flotation (36-57%) and disintegration. To counter the LCFA induced granular sludge disintegration and flotation, a novel reactor type, dynamic sludge chamber-fixed film (DSC-FF), was designed and achieved sCOD removal of 87-98% at HRTs from 12-72 h (LCFA loading rate 220-1333 mgCOD-LCFA/L·d) at 20°C. Moreover, even at the 12 h HRT, the unsaturated LCFAs (linoleate and oleate) were treated and only part of saturated LCFAs (stearate, palmitate) remained after treatment in the DSC-FF reactors. An increased methanogenic activity was established in the reactor sludges during reactor runs; evidenced by a higher acetotrophic activity in the granular sludge (from DSC), and a higher hydrogenotrophic activity in the biofilm (from FF) indicating development of distinct metabolic capabilities in the different reactor compartments. High throughput 16S rRNA sequencing showed that the relative abundance of the acetoclastic methanogen, Methanosaeta increased in EGSB reactors when fed with increased LCFA concentrations. The relative abundance of Methanosaeta increased also in the active microbiomes of granules (from DSC) and biofilm (from FF) during the 150-d reactor operation, demonstrating acetoclastic methanogenesis as the predominant methanogenesis pathway for SDW and LCFA degradation at 20°C. Microbial communities with a high β-oxidizing along with high methanogenic activity were developed during SDW treatment in DSC-FF reactors at 20°C. In DSC-FF reactors, the biofilm microbiome (from FF) had a prominent presence of the β-oxidizing bacteria Syntrophus and the hydrogenotrophic methanogen Methanospirillum; in comparison to the presence of the acetogenic bacteria - Syntrophobacter, Desulfobulbus, and Geobacter in the granular sludge microbiome, suggesting a role of these taxa at different trophic levels during LCFA degradation. In summary, this work demonstrated successful inoculum selection at low temperatures (10 and 20°C), and high-rate anaerobic LCFA degradation at 20°C using combined approaches of inoculum mixture and novel reactor design (here, DSC-FF). The key bacterial and archaeal taxa involved in the anaerobic conversion of LCFA to methane at 20°C were also deduced
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Ashton, Mark. "Behaviour of metals as a function of strain-rate and temperature." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/10449.
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Five materials, copper (two versions), iron, and armour plate steel (two versions) have been tested at different strain-rates and temperatures. All tests were in compression. The materials were studied to provide experimental data for input into hydrocode models of armour behaviour by the Defence Research Agency, Fort Halstead. A wide selection of metals was examined so that comparisons could be drawn between modelling the behaviour of face centred and body centred cubic metals, and to carry out a broader investigation into how the results obtained were affected by the test methods. Experiments were performed at temperatures from -100°C to 20°C and mean plastic strain-rates from 10-3 to 103 S-l, using a Split Hopkinson Pressure Bar (SHPB) system for high strain-rates and a Hounsfield 50 kN machine for quasistatic conditions. The stress-strain behaviour of the materials as a function of temperature and strain-rate was then determined. The effects of interfacial friction on the measured compreSSlve properties of copper and the armour plate steels have been investigated. Since the coefficient of friction was the critical parameter, ring tests were carried out and the Avitzur analysis applied. In general, the coefficient of friction decreased with increasing strain-rate and temperature. The tested specimen's appearance indicated the same friction trends. Hydrocode modelling of the SHPB system produced corrections to the flow stress, to compensate for interfacial friction, that agree well with those predicted by the Avitzur analysis. Deformed finite element mesh plots analysed in conjunction with barrelled specimens have given a clearer insight into the mechanisms of interfacial friction. The Armstrong-Zerilli constitutive models have been applied to copper, iron and armour plate steel results corrected for thermal softening and specimen-platen interfacial friction. These models have been shown to provide a reasonable description of the materials' behaviour. The research investigation has shown that in order to obtain fundamental stressstrain behaviour of the materials, then corrections must be applied, which can be quite significant. These corrections must take into account the effects of material thermal softening and the specimen-platen interfacial friction.
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Goto, Masayoshi, Jun Moriizumi, Hiromi Yamazawa, Takao lida, and Weihai Zhuo. "Estimation of global radon exhalation rate distribution." American Institite of Physics, 2008. http://hdl.handle.net/2237/12041.
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Calmunger, Mattias. "High-Temperature Behaviour of Austenitic Alloys : Influence of Temperature and Strain Rate on Mechanical Properties and Microstructural Development." Licentiate thesis, Linköpings universitet, Konstruktionsmaterial, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-98242.
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The global increase in energy consumption and the global warming from greenhouse gas emission creates the need for more environmental friendly energy production processes. Biomass power plants with higher efficiency could generate more energy but also reduce the emission of greenhouse gases, e.g. CO2. Biomass is the largest global contributor to renewable energy and offers no net contribution of CO2 to the atmosphere. One way to increase the efficiency of the power plants is to increase temperature and pressure in the boiler parts of the power plant. The materials used for the future biomass power plants, with higher temperature and pressure, require improved properties, such as higher yield strength, creep strength and high-temperature corrosion resistance. Austenitic stainless steels and nickel-base alloys have shown good mechanical and chemical properties at the operation temperatures of today’s biomass power plants. However, the performance of austenitic stainless steels at the future elevated temperatures is not fully understood. The aim of this licentiate thesis is to increase our knowledge about the mechanical performance of austenitic stainless steels at the demanding conditions of the new generation power plants. This is done by using slow strain rate tensile deformation at elevated temperature and long term hightemperature ageing together with impact toughness testing. Microscopy is used to investigate deformation, damage and fracture behaviours during slow deformation and the long term influence of temperature on toughness in the microstructure of these austenitic alloys. Results show that the main deformation mechanisms are planar dislocation deformations, such as planar slip and slip bands. Intergranular fracture may occur due to precipitation in grain boundaries both in tensile deformed and impact toughness tested alloys. The shape and amount of σ-phase precipitates have been found to strongly influence the fracture behaviour of some of the austenitic stainless steels. In addition, ductility is affected differently by temperature depending on alloy tested and dynamic strain ageing may not always lead to a lower ductility.
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Parks, Olivia Waverly. "Effect of water temperature on cohesive soil erosion." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/49663.
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In light of increased stream temperatures due to urbanization and climate change, theeffect of water temperature on cohesive soil erosion should be explored. The objectives of this study are to: determine the effect of water temperature on the erosion rates of clay; determine how erosion rates vary with clay mineralogy; and, explore the relationship between zeta potential and erosion rate. Samples of kaolinite- and montmorillonite-sand mixtures, and vermiculite-dominated soil were placed in the wall of a recirculating flume channel using a vertical sample orientation. Erosion rate was measured under a range of shear stresses (0.1-20 Pa) for a period of five minutes per shear stress at water temperatures of 12, 20, and 27�"C. The zeta potential was determined for each clay type at the three testing temperatures and compared to mean erosion rates. The kaolinite erosion rate doubled when the temperature increased from 12 to 20�"C, and erosion of vermiculite samples tripled when the temperature increased from 20 to 27�"C. The montmorillonite samples generally eroded through mechanical failure rather than fluvial erosion, and the limited fluvial erosion of the montmorillonite-sand mixture was not correlated with water temperature. The data suggest correlation between zeta potential and erosion rate; however, due to the small sample size (n=3), statistically significant correlation was not indicated. Research should continue to explore the influence of water temperature on cohesive soil erosion to better understand the influence of clay mineralogy. Due to the high degree of variability in cohesive soil erosion, multiple replications should be used in future work. The vertical sample orientation enabled discrimination between fluvial erosion and mass wasting and is recommended for future studies.
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Van, Voorhies Wayne Alan. "The influence of metabolic rate, temperature and sex on life history parameters." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186564.
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My dissertation research focused on four major biological variables; metabolic rate, body size, sex, and death. I found that growth and metabolic rate are not significantly correlated in the fish Oreochromis hybrid. To study factors affecting body size I researched the causal mechanism of Bergmann size clines. This is the trend that organisms tend to increase in body size with increasing distance from the equator. I found that genetically identical nematode worms, Caenorhabditis elegans, grow almost 40% larger at 10°C than at 25°C. Since adult worm cell number is constant in these worms the larger worm size is probably due to increased cell size. This provides a simple developmental mechanism, cells grow larger at lower temperatures, for Bergmann size clines in ectotherms. This would provide a simple non-adaptive explanation for the general trend of increased body size in ectothermic animals with increasing latitude. Sex significantly decreases the average lifespan of wild type male C. elegans but does not significantly affect hermaphrodite lifespan. I compared lifespans in three groups of worms: (1) all males, (2) all hermaphrodites, (3) a mixed population of hermaphrodites and male worms. At 20°C unmated males have an average lifespan 33% greater than mated males. In contrast, lifespans of mated and unmated hermaphrodites were identical. This result contradicts theories concerning the relative cost of reproduction which predict that large oocytes should be much more costly to produce than small sperm. I examined the lifespan of worms with a mutation affecting sperm production to determine if sperm production, rather than the physical effort of mating, is the major factor reducing lifespan in mated male worms. Average lifespan of both mutant mated males and unmated hermaphrodites is about 65% longer than that of wild type worms. Mated spe-26 males have similar lifespans to their unmated counterparts. These surprising results indicate that sperm production rather than ooycte production or the physical effort of mating is a major factor reducing lifespan in C. elegans.
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Boyd, Laura E. "Heterogeneous electron transfer rate constants of ferrocene/ ferrocenium in room-temperature ionic liquids /." Full text available from ProQuest UM Digital Dissertations, 2009. http://0-proquest.umi.com.umiss.lib.olemiss.edu/pqdweb?index=0&did=1913291371&SrchMode=1&sid=2&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1278437152&clientId=22256.
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Reedy, Michael Wayne. "An approach to low temperature high strain rate superplasticity in aluminum alloy 2090." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26891.
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Ayoola, Babatunde Oluwole. "Laser-based measurement of heat release rate and temperature in turbulent premixed flames." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613703.
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Muradov, Khafiz. "Temperature modelling and real-time flow rate allocation in wells with advanced completion." Thesis, Heriot-Watt University, 2010. http://hdl.handle.net/10399/2405.
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Tyrrell, Jennie L. "The effect of water temperature on in-stream sediment concentration and transport rate." Thesis, Michigan Technological University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10004794.
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Global climate change may result in rising temperatures. As a result, ecological health and the human use of rivers may be impacted. The hydrologic cycle, watershed hydrology, and in-stream hydraulics are dynamic systems, influenced by human activities, natural events, and climate. Although known drivers like precipitation and stream velocity govern sediment processes, the effect of water temperature on sediment transport remains unclear. In-stream sediment movement could lead to blocked harbors, flooding, and degradation of vulnerable fish habitat. To better understand how fluctuations in water temperature affect sediment dynamics, six transport models were analyzed on the Niobrara River, with water temperatures ranging 1° to 40° C. The results indicate that as water warms sediment transport decreases, according to an inverse, non-linear law, with the highest reduction at colder water temperatures. The results given here can help predict changes in sediment transport for rivers with similar characteristics at various water temperatures.
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Abram, Christopher. "High repetition rate temperature and velocity imaging in turbulent flows using thermographic phosphors." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/29181.
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Turbulent flows involving heat transfer and chemical reactions are prevalent in a huge range of applications such as combustors and engines, boilers, and heating and cooling devices. Directly measuring important variables using laser-based techniques has significantly contributed to our understanding of the underlying flow physics. However, many flows of interest exhibit infrequent or oscillatory behaviour, such as flame extinction or instabilities in thermal boundary layers. Capturing the flow dynamics requires simultaneous, two-dimensional temperature and velocity measurements at sampling rates commensurate with turbulent timescales. Typically this means measuring many thousands of temperature and velocity fields per second, yet there are no high repetition rate diagnostics for temperature imaging in practical, oxygen-containing systems, with the essential capability of simultaneous velocity measurements. This thesis presents a novel laser-based imaging technique based on thermographic phosphor particles. There are a huge variety of thermographic phosphors, which are solid materials with luminescence properties that can be exploited for remote thermometry. Here, phosphor particles are seeded into the flow as a tracer. An appropriate phosphor must be selected, and the particle size chosen so that the particle temperature and velocity rapidly assume that of the surrounding fluid. The particles are probed using high-speed lasers and their luminescence and scattering signals are detected using high-speed cameras to measure the flow temperature and velocity at kHz repetition rates. The development of this method is described in detail. Using the thermographic phosphor BAM:Eu, examples of simultaneous time-resolved measurements are presented in turbulent air flows between 300 and 500 K, consisting of a heated jet (Re = 10,000) and also a flow behind a heated cylinder (Re = 700). The technique permits kHz-rate temperature imaging in oxygen-containing environments. These combined diagnostics currently provide a unique capability for the investigation of transient, coupled heat and mass transfer phenomena in turbulent flows of practical engineering importance. A second objective of this work is to improve the precision of the temperature measurement. The characterisation of a different thermographic phosphor with a high temperature sensitivity, zinc oxide (ZnO), is also reported. Temperature imaging using these tracer particles is demonstrated in a jet (Re = 2,000) heated to 363 K, with a temperature precision of 1%. This extends the capabilities of this versatile technique toward the study of flows with small temperature variations. Also, unlike the majority of phosphors previously investigated for thermometry, this phosphor is a semiconductor. Exploiting the temperature-dependent luminescence of this class of materials presents interesting new opportunities for remote temperature sensing.
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Vernerback, Claes. "Effect of incubation temperature on Atlantic salmon metabolism as indicated by ventilation rate." Thesis, Karlstads universitet, Institutionen för miljö- och livsvetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-44497.
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The global mean temperature is predicted to increase by up to 5 °C during this century. For fish, being ectotherms, temperature is one of the most important environmental factors, influencing them in a number of different ways, including effects on physiological traits, timing of life history events and behavior. Atlantic salmon has been shown to grow faster after being incubated at warmer temperatures. One possible explanation for this could be that the increased incubation temperature causes decreased metabolic rates. The aim of this project was to examine whether this is true. Atlantic salmon eggs were incubated in three different temperature regimes: natural temperature conditions, heated water and a mixed temperature treatment, where eggs were incubated in increased temperature until the beginning of January and after that subjected to natural temperature conditions. Ventilation rate, a proxy for metabolism, was measured for fish from each treatment group, as well as fish length and weight. The results revealed significantly lower ventilation rates of the fish from the heated temperature treatment, but not of the fish from the mixed temperature treatment. This suggests that an increased incubation temperature causes lowered rates of metabolism in Atlantic salmon, and that the change occurs later than early January. Because of differences in size and life stage between fish from the different groups however, the results are uncertain and call for further investigations. A lowered metabolic rate will affect the fish’s behavior. A further development might therefore be to study fish survival in the wild in relation to a fish’s metabolic rate.Jordens medeltemperatur beräknas öka med upp till 5 °C det här århundradet. För fiskar, som är ektotermer, är temperatur en av de viktigaste abiotiska faktorerna och påverkar dem på en mängd olika sätt, bland annat genom förändring av fysiologiska attribut, tidpunkter för steg i livscykeln och beteende. Lax har visats växa snabbare efter att ha blivit inkuberade i varmare vattentemperatur. En möjlig förklaring till det kan vara att en förhöjd inkuberingstemperatur orsakar en lägre metabolism. Det här projektet syftade till att undersöka om så är fallet. Ägg från lax inkuberades i tre olika temperaturförhållanden: naturliga temperaturförhållanden, förhöjd temperatur och en blandad temperaturbehandling, där ägg inkuberades i förhöjd temperatur till början av januari, varefter de utsattes för naturliga temperaturförhållanden. Gälslagsfrekvens, som fungerar som en indikator för metabolism, mättes på fisk från varje behandlingsgrupp, samt fiskarnas längd och vikt. Resultaten visade signifikant lägre gälslagsfrekvenser hos fiskarna från behandlingen med förhöjd temperatur, men inte hos fiskarna från behandlingen med blandad temperatur. Detta indikerar att en förhöjd inkuberingstemperatur orsakar en lägre metabolism hos lax, och att förändringen sker senare än tidiga januari. På grund av skillnader i storlek och livsstadier hos fiskarna från de olika grupperna är resultaten dock osäkra, vilket gör att ytterligare studier behövs. En lägre ämnesomsättning påverkar fiskars beteende. En uppföljning kan därför vara att studera fiskars överlevnad i det vilda i relation till deras metabolism.
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Fernandez, Lorences Jose O. "Crystallinity changes in PET and Nylon 11 with strain, strain rate and temperature." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/32894.
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The mechanical properties of PET (widely used in bottles and synthetic fibres) and Nylon 11 (also used in the fabrication of synthetic fibres) were studied over several decades of strain rate at different temperatures in an effort to provide a more complete description of these materials behaviour. Processing techniques can be improved if such information is available. Tests were carried out using a conventional Hounsfield machine and two in-house-developed dropweight and a cross bow systems from 10°C to 200°C. The three systems enable true stress vs. true strain curves to be calculated.
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Klute, Robert Cragg. "Enantiomeric separations by HPLC : temperature, mobile phase, flow rate and retention mechanism studies /." This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-171241/.
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Wang, Wen Bo. "Cryopreservation of Nereis virens sars and Arenicola marina L. larvae : mechanisms and applications in aquaculture." Thesis, University of Newcastle upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245712.
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Dupaix, Rebecca B. (Rebecca Brown) 1976. "Temperature and rate dependent finite strain behavior of poly(ethylene terephthalate) and poly(ethylene terephthalate)-glycol above the glass transition temperature." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/7972.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.Includes bibliographical references (p. 333-348).
Poly(ethylene terephthalate) is widely used for consumer products such as drawn fibers, stretched films, and soda bottles. Much of its commercial success lies in the fact that it crystallizes at large strains during warm deformation processing. The imparted crystallinity increases its stiffness and strength, improves its dimensional stability, and increases its density. The crystallization process and the stress-strain behavior above the glass transition depend strongly on temperature, strain rate, strain magnitude, and strain state. A robust constitutive model to accurately account for this stress-strain behavior in the processing regime is highly desirable in order to predict and computationally design warm deformation processes to achieve desired end product geometries and properties. This thesis aims to better understand the material behavior above the glass transition temperature in the processing regime. It examines the strain rate, strain state, and temperature dependent mechanical behavior of two polymers: PET and PETG, an amorphous non-crystallizing copolymer of PET, in order to isolate the effects of crystallization on the stress-strain behavior. Experiments over a wide range of temperatures and strain rates were performed in uniaxial and plane strain compression. A constitutive model of the observed rate and temperature dependent stress-strain behavior was then developed. The model represents the material's resistance to deformation with two parallel elements: an intermolecular resistance to flow and a resistance due to molecular network interactions.
(cont.) The model predicts the temperature and rate dependence of many stress-strain features of PET and PETG very well, including the initial modulus, flow stress, initial hardening modulus, and dramatic strain hardening. The modeling results indicate that the large strain hardening behavior of both materials can only be captured by including a critical orientation parameter to halt the molecular relaxation process once the network achieves a specific level of molecular orientation. This suggests that much of the strain hardening in PET is due to molecular orientation and not to strain-induced crystallization. An example blow molding process is simulated to demonstrate the industrial applicability of the proposed model.
by Rebecca B. Dupaix.
Ph.D.
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Islam, Maeen Zakaria. "Influence of gender on heart rate and core temperature at critical wbgt for five clothing ensembles at three levels of metabolic rate." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001077.
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Gajic, Tijana. "Change in Thermal Metabolic Rate Reaction Norms of Daphnia in Response to Rearing Temperature." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23299.
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Temperature is an important environmental factor that affects the distribution of organisms. It affects the biochemical and physiological processes which are the basis of life. The metabolic cold adaptation (MCA) hypothesis predicts an increase in the metabolic rate of ectotherms from cold environments compared with their more temperate counterparts. This hypothesis is one of the most controversial in ecophysiology. MCA is an example of counter gradient variation, a geographical pattern of genotypes where genetic influences on a trait oppose environmental influences. Environmental gradients are common in nature and are considered to have major effects on intraspecific variation patterns. In this study, I tested the MCA hypothesis at an intraspecific level. As a study model I utilized the water flea, Daphnia magna. These are planktonic crustaceans, common in lakes and ponds, and have a wide geographical and thermal distribution. I tested the MCA hypothesis in a laboratory experiment in which oxygen consumption of water fleas reared at three different temperatures for one year (12 ? 35 generations), were measured at three different experimental temperatures. My results show that the animals from the coldest rearing temperature (10 °C) had the highest metabolism at all three experimental temperatures (10, 17 and 25 °C), compared with animals reared at higher temperatures (17 and 25 °C). Elevated metabolism in animals from cold environment is consistent with the metabolic cold adaptation hypothesis. The present study does however not provide conclusive evidence that clone-specific variation in thermal performance has a genetic basis. Organisms may adjust their thermal reaction norms as a response to the thermal regime in which they live through three mechanisms: acclimation, epigenetic effects and evolution, and these could not be distinguished in experimental design used here.
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Ali, Mohammed Ali Nasser. "Thermo-elastic-plastic analysis for elastic component under high temperature fatigue crack growth rate." Thesis, Sheffield Hallam University, 2013. http://shura.shu.ac.uk/19243/.
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The research project presents a fundamental understanding of the fatigue crack growth mechanisms of AISI 420 martensitic stainless steel, based on the comparison analysis between the theoretical and numerical modelling, incorporating research findings under isothermal fatigue loading for solid cylindrical specimen and the theoretical modelling with the numerical simulation for tubular specimen when subjected to cyclic mechanical loading superimposed by cyclic thermal shock. The experimental part of this research programme studied the fatigue stress-life data for three types of surface conditions specimen and the isothermal stress-controlled fatigue testing at 300 °C - 600 °C temperature range. It is observed that the highest strength is obtained for the polished specimen, while the machined specimen shows lower strength, and the lowest strength is the notched specimen due to the high effect of the stress concentration. The material behaviour at room and high temperatures shows an initial hardening, followed by slow extension until fully plastic saturation then followed by crack initiation and growth eventually reaching the failure of the specimen, resulting from the dynamic strain ageing occurred from the transformation of austenitic microstructure to martensite and also, the nucleation of precipitation at grain boundaries and the incremental temperature increase the fatigue crack growth rate with stress intensity factor however, the crack growth rate at 600 °C test temperature is less than 500 °C because of the creep-fatigue taking place. The theoretical modelling presents the crack growth analysis and stress and strain intensity factor approaches analysed in two case studies based on the addition of thermo-elastic-plastic stresses to the experimental fatigue applied loading. Case study one estimates the thermal stresses superimposed sinusoidal cyclic mechanical stress results in solid cylinder under isothermal fatigue simulation. Case study two estimates the transient thermal stresses superimposed on cyclic mechanical loading results in hollow cylinder under thermal shock in heating case and down shock cooling case. The combination of stress and strain intensity factor theoretical calculations with the experimental output recorded data shows a similar behaviour with increasing temperature, and there is a fair correlation between the profiles at the beginning and then divergence with increasing the crack length. The transient influence of high temperature in case two, giving a very high thermal shock stress as a heating or cooling effects, shifting up the combined stress, when applied a cyclic mechanical load in fraction of seconds, and the reputations of these shocks, causing a fast failure under high thermal shock stress superimposed with mechanical loading. Finally, the numerical modelling analyses three cases studied were solved due to the types of loading and types of specimen geometry by using finite element models constructed through the ANSYS Workbench version 13.0. The first case is a low cyclic fatigue case for a solid cylinder specimen simulated by applying a cyclic mechanical loading. The second is an isothermal fatigue case for solid cylinder specimen simulated by supplying different constant temperatures on the outer surface with cyclic mechanical loading, where the two cases are similar to the experimental tests and the third case, is a thermo-mechanical fatigue for a hollow cylinder model by simulating a thermal up-shock generated due to transient heating on the outer surface of the model or down shock cooling on the inner surface with the cyclic mechanical loading. The results show a good agreement with the experimental data in terms of alternative stress and life in the first case. In case two results show the strain intensity factor is increases with increasing temperature similar to the theoretical solution due to the influence of the modulus of elasticity and the difference in life estimation with the experimental output record is related to the input data made of theoretical physical properties and the experimental stress-life data.
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Gaughan, John Beckley. "Respiration rate and rectal temperature responses of feedlot cattle in dynamic, thermally challenging environments /." St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16104.pdf.
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Coll, Ferrari María Teresa. "Effect of austenitising temperature and cooling rate on microstructures of hot-work tool steels." Licentiate thesis, Högskolan Väst, Avd för tillverkningsprocesser, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-8614.
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The average size of hot-work tools has gradually increased over the past years.This affects the effective temperature cycle tools experience during hardening,as large dimensions prevent uniform and rapid cooling, and thereby the resulting microstructures and properties. In order to avoid the formation of coarse structures or cracking during heat treatment it has become common practise to lower the austenitising temperature below that recommended by the steel manufacturer.In this work, therefore, the effects of austenitising at temperatures lower thancommonly recommended are investigated. Three 5% Cr hot-work tool steelsalloyed with Mo and V were heat treated, resulting microstructures andtempering carbides were studied and transformation characteristics determined for different austenitising temperatures and different cooling rates. The temperatures and cooling rates have been chosen to be representative for heat treatments of different sizes of tools. Bainite rather than martensite formed during slow cooling regardless of austenitising temperature. A lowered austenitising temperature produced largeramounts of both bainite and retained austenite while a higher caused graingrowth. Carbon partitioning during the bainitic transformation resulted in anincrease of the carbon content in the retained austenite of at least 0.3 wt.%. The austenitising temperature influences also the type and amount of tempering carbides that precipitate, which affects the properties of the steel. Higher austenitising temperatures favour the precipitation of MC carbides during tempering. The Mo rich M2C type carbides were proven to be more prone to coarsening during service at 560°C-600°C, while V rich MC carbides preserve their fine distribution. A best practice heat treatment needs to balance the increase of grain size with increasing austenitising temperatures, with the possibility to form more tempering carbides. Higher austenitising temperatures also give less retained austenite, which can affect dimensional stability and toughness negatively after tempering
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Fallis, Wendy M. "Core and bladder temperature gradient in critically ill adults : urine flow rate as a factor /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/7315.
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Conceição, Maristela Neves da. "Avaliação da influência do sombreamento artificial no desenvolvimento de novilhas leiteiras em pastagens." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/11/11131/tde-18112008-142644/.
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Este estudo teve como objetivo avaliar e quantificar o efeito do sombreamento artificial proporcionado por diferentes tipos de materiais de cobertura sobre a fisiologia, o comportamento e o desenvolvimento de novilhas leiteiras, em ambiente de pastagens. A pesquisa foi realizada no período de 08/01/2007 à 30/04/2007. A área experimental foi dividida em 16 parcelas adjacentes e iguais com 84 m² cada. Foram comparados a testemunha (sem sombra) com três tipos de cobertura: telhas de fibrocimento sem cimento amianto, telhas galvanizadas e tela de polipropileno 80% As dimensões dos abrigos foram 2m x 4m e 4m de altura (4m² de sombra.animal-1), sem paredes laterais. Foram utilizadas 16 novilhas Holandesas e 16 Hol x Jersey com idade e peso iniciais de 17,2 ± 5,6 meses e 265,3 ± 66,9kg, respectivamente, pareadas em função da uniformidade de peso e idade. As novilhas permaneciam em piquetes de capim elefante (Penissetum purpureum) durante a noite e após as 9:00h eram conduzidas para as parcelas. A tgn foi registrada por minidatalogger conectado a globo negro para cálculo de CTR e ITGU em cada parcela. As variáveis meteorológicas foram obtidas no posto agrometeorológico da ESALQ/USP. Semanalmente foram registradas FR, TR e TP. As observações comportamentais foram realizadas em dias não consecutivos por 24 horas pelo método focal. As pesagens dos animais foram realizadas mensalmente. As condições ambientais durante o período da pesquisa foram caracterizadas como estressantes para novilhas. A análise física dos materiais (tgn, CTR e ITGU) indicou diferença entre os materiais de cobertura (P<0,05) sendo a telhas de fibrocimento sem amianto a mais confortável termicamente, seguida da telha galvanizada e da tela. Os valores de FR foram menores sob as telhas de fibrocimento (P<0,05) e semelhantes entre telha galvanizada e tela (P>0,05), os valores de TR não apresentaram diferença entre tratamentos somente entre horários e para a TP houve diferença (P<0,05) entre o tratamento fibrocimento e a testemunha, porém não houve entre os demais (P>0,05). A FR apresentou as respostas mais imediatas às alterações ambientais. Houve correlação da TR com a FR e a TP. Não foram observadas alterações comportamentais entre os tratamentos, os animais ficaram sob as sombras nas horas mais quentes do dia, preferencialmente em pé, o comportamento diário seguiu os padrões conhecidos para bovinos. O ganho de peso não foi alterado pelos tratamentos. A análise de custo indicou a cobertura de fibrocimento como a mais indicada para a construção de abrigos considerando-se os resultados encontrados. A pesquisa indicou haver melhora no bem estar térmico das novilhas, porém, não conseguiu determinar ganhos efetivos na utilização da sombra.The objective of the present study was to evaluate and quantify the effect of artificial shade given by different types of roofing materials on the physiology, behavior and development of dairy heifers in a pasture environment. The present study took place from January 8, 2007 to April 30, 2007. The experimental area was divided into 16 equal, adjacent plots with 84 m2. Three roofing treatments (fiber-cement roofing tiles without amianthus, galvanized roofing tiles and 80% polypropylene screen) were compared to a control (no shade). Shelter structures had no lateral walls and measured 2m x 4m x 4m height (4m² shaded per animal). Animals consisted of 16 Holstein heifers and 16 Holstein x Jersey heifers with initial age and weight being 17.2 ± 5.6 months and 265.3 ± 66.9 kg, respectively. Animals were equally distributed among the treatments according to weight and age. At night, heifers were kept in fields with Pennisetum purpureum, also known as elephant grass. After 9:00 am, animals were taken to the experimental plots. Black globe thermometer temperature (tbg) was measured using a mini-datalogger connected to a black globe. Values were then used to calculate Radiant Thermic Load (RTL) and Black Globe Humidity Index (BGHI) of each plot. Meteorological variables were obtained from the agricultural-meteorological post at the ESALQ/USP. Respiration rate (RR), rectal temperature (RT) and skin temperature (ST) were registered weekly. Behavioral observations were recorded every other day using the focal method. Animals were weighed monthly. Environmental conditions during the research period were characterized as stressful for the heifers. Physical analysis of the material (tbg, RTL and BGHI) indicated the roofing treatments to be significantly different (P<0.05), with the fiber-cement roofing tiles without amianthus to be the most comfortable regarding temperature, followed by the galvanized roofing tiles and the 80% polypropylene screens. Respiration rate was lower under the fiber-cement roofing tiles (P<0.05) and similar under the galvanized tiles and polypropylene screen (P>0.05). RR values were lower under the fiber-cement tiles (P<0.05) and similar under the galvanized roofing tiles and polypropylene screen (P>0.05). There were no significant differences in RT values among treatments; however, a difference was found among data collection times. Concerning ST, fiber-cement tiles were significantly different from the control (P<0.05). On the other hand, there were no significant differences regarding ST among the other treatments (P>0.05). RR presented the most immediate response to environmental alterations. RT presented correlation with RR and ST. No behavioral alterations were observed among the treatments. Daily behavior followed known bovine patterns. Weight gain was not altered by the treatments. A cost analysis indicated fibercement roofing tiles to be better for shelter construction. The present study also indicated improved heifer thermal well-being; however, no effective gains could be determined from shade use.
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Kerrigan, Brannon Michael. "System Design of a High-Temperature Downhole Transceiver." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/85006.
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The oil and gas industry, aerospace, and automotive industries are constantly pushing technology beyond their current operational boundaries, spurring the need for extreme environment electronics. The oil and gas industry, in particular, is the oldest and largest market for high-temperature electronics, where the operating environment can extend up to 260 degrees Celsius. The electronics currently employed in this field are only rated to 200 degrees Celsius, but with the rise of wideband gap technologies, this could be extended to 250 degrees Celsius or more without the needed for active or passive cooling. This reduces the complexity, weight, and cost of the system while improving reliability. In addition, current downhole telemetry data rates are insufficient for supporting more sophisticated and higher resolution well-logging sensors. Increasing the data rates can also save the industry significant amount of time by decreasing the amount of well-logging excersions and by increasing the logging speed.
Previous work done by this research group saw the prototyping of a high bit rate transceiver operating at 230 MHz - 300 MHz and 230 degrees Celsius; however, at these frequencies, the system could not meet size requirements. Thus, a new high-temperature high data rate transceiver design using the 2.4 GHz - 2.5 GHz ISM band is proposed to miniaturize the design and to allow for IC implementation. The transceiver was designed to meet the minimum specifications necessary to give designers flexibility between power consumption and performance. The performance of the design is simulated using AWR design environment software, which shows the system can support a downlink data rate up to 68 Mbps and an uplink data rate up to 170 Mbps across 10 channels. The effects temperature has on the system performance is also evaluated in the simulation.Master of Science
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Forster, Claire E. "Dehydration in Southern Toads (Anaxyrus terrestris): Metabolic Costs and Effects of Temperature Selection." Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/scripps_theses/161.
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Southern toads (Anaxyrus terrestris) are ectothermic terrestrial amphibians. As such they are sensitive to thermal and hydric variability. The interactive effect of hydration state and body temperature is not well understood. The aim of this study is to determine if the costs of dehydration vary at different temperatures and if so, whether toads will select different temperatures to minimize these costs. Costs of dehydration were evaluated by measuring metabolic rate at 100% and 85% hydration state, at 30 and 20 oC. Temperature selection of toads at 100% and 85% hydration state was measured using a thermal gradient. Body temperature, but not hydration state, was determined to have a significant effect on metabolic rate. No significant difference in temperature selection was found between toads at 100% and 85% hydration state. Thus, thermoregulatory behavior as influenced by hydration state could not be predicted in Anaxyrus terrestris.
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Niklison, Alina Maria. "INFLUENCE OF EMBRYONIC METABOLIC RATE AND INCUBATION TEMPERATURE ON INCUBATION LENGTH VARIATION IN NEOTROPICAL PASSERINES." The University of Montana, 2008. http://etd.lib.umt.edu/theses/available/etd-12212007-143823/.
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Variation in embryonic developmental periods influences fitness, but causes of interspecific variation are poorly understood. Allometry, for example, does not explain variation in incubation periods among neotropical passerines. Incubation temperature can explain some variation in developmental periods, but substantial variation remains unexplained. Here we examine two previously untested alternatives. Adult metabolic rates differ among species and similar differences among embryos may explain some variation in embryonic development rates; higher metabolism may allow faster cellular proliferation. Alternatively, metabolic rates are temperature dependent, and metabolic rates might respond differentially to temperature among species and compensate for differing incubation temperatures. These alternatives are untested across any taxa. Therefore, we examined them in tropical Venezuela by measuring embryonic metabolism at four temperatures in 15 passerine species with incubation periods ranging from 12 to 27 days. Embryonic metabolic rates responses to temperature were different among species even at constant embryonic age. Furthermore, species with lower average daily incubation temperature are less sensitive to changes in temperature than species with higher average incubation temperatures. Differences in embryonic mass specific metabolic rate among species explained a significant amount of variation in incubation periods after correcting for incubation temperature. Thus, differences in the rate of living as manifested through metabolism can influence developmental trajectories and deserve greater attention.
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Sammonds, Peter Robert. "Triaxial deformation experiments on natural sea ice as a function of temperature and strain rate." Thesis, University College London (University of London), 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241922.
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Vallejo, Mauricio. "Noradrenergic tuning, not simple rate effects, produces temperature-sensitivity of the respiratory network in bullfrogs." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1527181646566301.
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Yuan, Bing. "Variable Temperature Rate Coefficient Studies through a Coaxial Molecular Beam Radiofrequency Ring Electrode Ion Trap." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/242471.
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The dissertation focuses on the temperature dependent rate coefficient measurement of reactions in the interstellar medium using a coaxial molecular beam ring electrode ion trap apparatus. The first chapter introduces the previous studies of ion-molecule reactions in the ISM, the types of instruments mainly used in the reaction rate coefficient study, the former research on the ring electrode ion trap and the gas phase reaction mechanisms. Compare to other instruments, our molecular beam - ring electrode ion trap is extremely good at ion cooling and temperature control for both ions and neutral molecules. Chapter two describes each part of the instrument used in detail. Ions produced by electron impact in the ion source chamber, are mass filtered and then reach the ring electrode ion trap. In the trap, ions collide with molecules in the molecular beam where reaction takes place. When the reaction is done, all the ions remained in the trap (the reactant and product ions) come out and move to the detector. The molecular beam terminates at residual gas analyzer which is used for the number density calibration. The third chapter shows how the temperature of ions and molecules are controlled separately in order to find the reaction mechanism. Ions are cooled by the pulsed He buffer in the ring electrode trap and a chopped beam is used to make sure the ions are cooled to the desired low temperature when the reaction takes place. Chapters four to six describe the three reactions being studied using this instrument: N₂⁺ + H₂O charge transfer reaction, H₃O⁺ + C₂H₄ proton transfer reaction and H3O⁺ + (C₂H₂)₂/C₂H₂ dimer reaction. The temperature dependent rate coefficient data of these reactions are explained by the average dipole orientation theory, statistical theory and Colussi's acetylene dimer model, respectively. Two temperatures are defined and applied in the experimental rate coefficients analysis: ion-molecule center of mass collision temperature and the reaction statistical temperature which is based on the numbers of degrees of freedom of both reactants.
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Khan, Amnah Sehar. "Electromechanical response of bulk PZT 95/5 and associated polymers across temperature and strain rate." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/48495.
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Piezoelectricity is the ability of certain, non-conductive, materials to generate an electrical charge when pressure is applied to them. The voltage produced is directly proportional to the applied stress. The amount of charge generated can depend on, for example, the applied strain rate or the temperature. Due to this ability, piezoceramics, such as PZT ceramics, find use in many different applications, primarily as sensors or actuators. Sensors work by detecting pressure, mechanically deforming and thus producing a voltage. Actuators, on the other hand, mechanically deform upon application of an electric field. To develop a better understanding of the piezoelectric ceramic lead zirconate titanate (PZT) 95/5, a range of studies including varying temperatures, porosities, and strain rates have been conducted. The effects on the voltage output and failure of poled PZT samples of different porosities have been investigated using different compressive strain rates (10^-4 – 10^4 s^-1), reached with quasi-static loading equipment, drop-weight towers, and Split Hopkinson Pressure Bars (SHPBs). The main cylindrical specimens were of 4.4 mm diameter, thickness 0.8 - 4.4 mm, and density 7.3 - 8.3 g cm^-3. The temperature range of -20°C to +80°C was achieved using purpose-built environmental chambers. The resulting stress-strain relationships are compared; all the samples ultimately displaying a brittle response at failure [1]. To support this work, ideal geometric specimen sizes were identified for the different types of loading experiment, by carrying out a range of strain-rate compression experiments on well-studied materials such as aluminium and copper. In addition, different experimental platforms were successfully developed in order to reach non-ambient temperatures in the Split Hopkinson Pressure Bar experiments. Finally, as piezoceramics, when used in real world applications, are often coated in protective layers of polymer, several different types of industrial polymer have been characterised across the full range of strain rates and temperatures.
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Yatham, Venkata Krishna Reddy. "Study of Nitrogen Removal Rate and Trouble shooting of Pilot plant (ITEST)." Thesis, KTH, Mark- och vattenteknik (flyttat 20130630), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171806.
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This paper is about improving the efficiency of nitrogen and other organic nutrient removal from activated sewage treatment by adopting an innovative technology. The work is to study the changes in nitrogen removal in pilot-scale experiments with the ITEST unit. The report also describes the various sources contributing to the eutrophication of the sea and water, caused by an increase in nutrient levels in different water bodies. Ineffective treatment of sewage contributes to the eutrophication. In the Baltic regions the temperature will be zero (0) or less than zero degree-centigrade during winter season. It results in decreased or fall in temperatures of incoming water to wastewater treatment plants. The temperature is an important parameter for sewage/wastewater treatment processes. Bacteriological nitrification and denitrification is an effective process for removing nitrogen from wastewater. From various research works and articles, it can be found that 23 + / - 2 °C, is the optimum temperature for nitrification and denitrification processes. So, the main aim is to study the effect of maintaining the incoming wastewater temperature by use of heat exchangers on incoming water to an activated sludge process line in pilot plant scale. In the pilot plant there were two testing lines; one line with heating system and the second line without heating system. A temperature of 19 to 20 °C was maintained in the influent to testing line. The nitrogen removal rates were compared between the two lines during the test period of approximately more than 8 months. Other biological activities in the treatment process were also compared between the two lines.
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Larour, Patrick [Verfasser]. "Strain rate sensitivity of automotive sheet steels: influence of plastic strain, strain rate, temperature, microstructure, bake hardening and pre-strain / vorgelegt von Patrick Larour." Aachen : Shaker, 2010. http://d-nb.info/1007085649/34.
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McIntyre, Dennis O. "The effect of temperature on uptake rate constants, depuration rate constants, and bioconcentration factors (BCF) for six organochlorines in the aquatic insect, Chironomus riparius /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487596807823978.
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Wan, Margaret. "Assessment of occupational heat strain." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001661.
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Wilson, Dwayne. "Ability of Physiological Strain Index to Discriminate Between Sustainable and Unsustainable Heat Stress." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6981.
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Introduction: Assessment of heat strain is an alternative approach to assessing heat stress exposures. Two common measures of heat strain are body core temperature (TC) and heart rate (HR). In this study TC was assessed by rectal temperature (Tre). Physiological Strain Index (PSI) was developed to combine both Tre and HR into one metric. Data collected from progressive heat stress trials were used to (1) demonstrate that PSI can distinguish between Sustainable and Unsustainable heat stress; (2) suggest values for PSI that demonstrate a sustainable level of heat stress; and (3) determine if clothing or metabolic rate were effect modifiers.
Methods: Two previous progressive heat stress studies included 494 trials with 988 pairs of Sustainable and Unsustainable exposures over a range of relative humidity (rh), metabolic rates (M) and clothing using 29 participants. To assess the discrimination ability of PSI, conditional logistic regression and logistic regression were used. The accuracy of PSI was assessed using Receiver Operating Characteristic curves (ROC).
Results: The present study found that primary (Tre, HR, and Tsk) and derived (PSI and ΔTre-sk) HSMs can accurately predict Unsustainable heat stress exposures based on AUCs that ranged from 0.73 to 0.86. Skin temperature had the highest AUC (0.86) with PSI in the mid-range (0.79).
The values of the HSMs associated with a predicted probability of 0.25 were considered as screening values (PSI < 2.6, ΔTre-sk > 1.9 °C, Tre < 37.5, HR < 109, and Tsk < 35.8). The value of using any one of these individual indicators is that they act as a screening tool to decide if an exposure assessment is needed.
Metabolic rate was found to be a confounder for all the HSMs except for RTsk. It was not statistically significant for HSMs derived models (PSI and ΔTre-sk). And its effect modification was not significant in any model.
Conclusions: Based on the ROC curve, PSI can accurately predict Unsustainable heat stress exposures (AUC 0.79). HR alone has a similar capacity to distinguish Unsustainable exposures (AUC 0.78) under relatively constant exposure (metabolic rate and environment) for an hour or so. Screening limits with high sensitivity, however, have low thresholds. This limits the utility of these heat strain metrics. To the extent that the observed strain is low, there is good evidence that the exposure is Sustainable.
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Malindi, Phumzile. "Electrocardiogram, heart rate and temperature monitoring system." Thesis, 2000. http://hdl.handle.net/10321/1812.
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Dissertation submitted in compliance with the requirements for Masters Degree in Technology in the Department of Electrical Engineering, Technikon Natal, 2000.The purpose of this study is the development of an affordable computer-based electrocardiogram, heart rate and temperature monitoring system, that would complement those that are available on the market and contribute to the reduction of the shortage of these medical instruments in South African hospitals and clinics. Electrocardiogram (ECG) refers to the graph that results from time versus voltage in a patient's chest. It reflects the rhythmic activity of the heart. For this reason the electrocardiogram has a diagnostic value that can be used by medical personnel to examine the biological (hence, clinical) behavior of the heart. The electrocardiogram can also be used to get the heart rate. This thesis explained how to acquire ECG signals from the patient and also how to achieve a cheaper way of providing galvanic isolation, which is required for sensors that are attached to the human body. It also explains computer interfacing using the parallel port and computer-based processing of these ECG signals to determine the instantaneous value of the heart rate and also to reduce the interference that contaminates these signals. In reducing interference, the performance of traditional IIR notch and adaptive filters, as noise cancelers, has been analyzed and compared. Least Mean Squares (LMS) and Normalized Least Mean Squares (NLMS) algorithms are the two algorithms that were considered in this study for adaptive noise canceling and their performance is evaluated and is compared based on their convergence rate, complexity and noise reduction.
M
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Chou, Zi-Yan, and 周子晏. "Effect of temperature on heart rate and respiratory rate of the Macrobrachium rosenbergii." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/57d37r.
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碩士國立宜蘭大學
生物機電工程學系碩士班
107
Climate change in recent years is a formidable challenge for Aquaculture. Macrobrachium rosenbergii is a high-value aquatic product. It is a poikilotherm, so the change in ambient temperature has a direct impact on the physiological status of Macrobrachium rosenbergii, this is also related to the optimal temperature range for it to survive and the tolerance limits. This study will measure the heart rate and the swinging rate of scaphognathite in the freely moving Macrobrachium rosenbergii at different temperature ranges, to understand the relationship between temperature changes and their physiological regulation. The ECG signals were get with an electrode embedded in the posterior edge of the heart and measuring the swing of scaphognathite by using an electrode embedded in the operculum. The experiment was divided into two parts, namely the temperature rising experiment and the cooling experiment. The Macrobrachium rosenbergii continued to heat up at 23 ° C and died (about 38 ° C), and after 28 ° C rest, the temperature was continuously cooled to death (about 10 ° C). The results showed that the heart rate and respiration rate change was linearly correlated with the increase/decrease of temperature. The limitation of heart rate was the rate at 33°C degrees and the respiration rate was the rate at 37°C degrees; The extreme low lethal temperature is 10°C degrees for heart rate. The high temperature is estimated because the heart rate increases to the limit and cannot effectively supply the blood required for metabolism, resulting in death at high temperatures. Low temperatures may result in systemic hypoxia and death due to slow heart rate and breathing.
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"Locally averaged temperature dissipation rate in turbulent convection." 2000. http://library.cuhk.edu.hk/record=b5895812.
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Kwok Chun-yin.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.
Includes bibliographical references (leaves [121]-122).
Abstracts in English and Chinese.
Chapter 1 --- Introduction --- p.1
Chapter 2 --- Experimental data --- p.7
Chapter 2.1 --- Turbulent Convection using Helium --- p.7
Chapter 2.2 --- Turbulent Convection using water --- p.8
Chapter 3 --- Probability Distribution and Scaling behavior --- p.9
Chapter 3.1 --- PDF of YT --- p.9
Chapter 3.1.1 --- Helium Convection --- p.10
Chapter 3.1.2 --- Water Convection --- p.26
Chapter 3.1.3 --- Comparison between helium data and Water data --- p.34
Chapter 3.2 --- T -dependence of the moments of XT --- p.39
Chapter 3.2.1 --- Helium Convection --- p.39
Chapter 3.2.2 --- Water Convection --- p.47
Chapter 4 --- Hierarchical Moment Relation --- p.50
Chapter 4.1 --- Method of Analysis --- p.50
Chapter 4.2 --- Results and Discussion --- p.53
Chapter 4.2.1 --- Helium Convection --- p.53
Chapter 4.2.2 --- Water Convection --- p.81
Chapter 5 --- Discussion and Conclusion --- p.95
Chapter 5.1 --- Passive Scalar --- p.96
Chapter 5.2 --- Comparison between Turbulent Convection and Passive Scalar --- p.99
Chapter 5.3 --- Scaling behavior for length scale above and below the Bolgiano scale for turbulent convection using Helium gas --- p.100
Chapter 5.4 --- Conclusions --- p.107
Chapter A --- The lognormal model --- p.108
Chapter B --- Definition of XT --- p.110
Chapter C --- Reasons for analysis of (xTp) for p≤ 12 --- p.112
Chapter D --- Functional form of μp implied by the hierarchical relation --- p.119
Bibliography --- p.122
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HAN, KAI-LIN, and 韓凱霖. "Chip design of a high conversion rate time-domain temperature sensor with temperature compensated oscillator." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/9tq797.
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碩士國立臺北科技大學
電子工程系
107
With the advancement of integrated circuit technology, increasing number of electronic instruments are designed with high circuit density. In this situation, overheat is a very important issue, so we need a temperature sensor for thermal management. In this thesis, we proposed a high conversion rate time-domain temperature sensor with temperature compensated self-oscillation, which uses a time-amplified temperature-dependent delay line to perform the delay. Compared with the traditional temperature delay line, the time-amplified temperature-dependent delay line can greatly reduce the power consumption and the number of transistors used. We also added a temperature compensated oscillator to provide a high-frequency signal for the temperature sensor and to reduce the costs of the instruments and their noise contribution to the circuit. This chip has been implemented in the TSMC 0.18μm 1P6M CMOS technology, and the supply voltage is 1.2 V. The oscillator frequency is 602 MHz. At a conversion rate of 146 kHz, the energy consumption per conversion is 9.83 nJ. The core area of chip is 0.149 mm2. The temperature measurement range is from 20 to 80 oC with a resolution of 0.48 oC/bit and a measurement error between -0.61 and 0.46 oC. Based on the simulation results, the oscillation frequency is close to the required system frequency. During the actual measurement, the temperature sensor had high conversion rate and resolution and outputted correct digital codes, making it suitable for thermal management in SoCs.
49
Cho, Ching-Wen, and 卓靜玟. "A Study on the High Temperature Oxidation Rate of Heat." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/18475124751182727273.
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碩士國立成功大學
材料科學(工程)研究所
83
The purpose of this study was to evaluate the high temperatureof AISI 304L SS, AISI 304L SS(S) (solution treatment), Nitronic205 duplex SS. Thermogravimetric nalyses (TGA) were conducted at temperatures var The experimental results of TGA showed that all the above alloysbolic oxidation kinetics. The oxidation rates of the alloysfollowing order: SAF 2205 duplex SS, AISI 304L SS, AISI 304L SS(S) and Nitronic
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Chen, Ching-Yuan, and 陳清源. "The Effect of Temperature and Strain Rate on Carbon Steel." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/20528597221474643251.
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