• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 15
  • 5
  • 4
  • 3
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 40
  • 40
  • 10
  • 6
  • 6
  • 6
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Vliv stárnutí, ročního období a teploty na práh bolesti u laboratorního potkana / Effect of aging, season and temperature on pain threshold in laboratory rat

Vítková, Jana January 2013 (has links)
Every living creature meets with pain up to these days. Many researches are made in labour conditions, we try to find out how the pain works and how we can suppress it or how we can utilize it in our welfare. Our work is focused on the effect of aging, season, acclimatization and ambient temperature on thermal and mechanic pain threshold in laboratory rats. We were interested how these factors affect the results of the research. Adult male Wistar rats were used in all experiments. Thermal pain thresholds were measured by withdrawal reaction of three body sites: forelimbs, hind limbs and tail. Mechanic pain thresholds were measured by von Frey filaments and a skin temperature was measured by IR thermometer, both of three body sites. Our results demonstrate that : (i) aging have effect on nociceptive pain threshold; (ii) there is presence of cranio-caudal distribution of nociceptive sensitivity in aging and in changing of ambient temperature - forelimbs have lower latency than hind limbs; (iii) thermal pain threshold depends indirectly on ambient and skin temperature; (iv) there was no effect of repeated measurement on nociceptive thresholds of the three body sites; (v) hind limbs and tails are more sensitive to changes of ambient temperature than forepaws; (vi) mechanic pain threshold not change...
22

Truck tyre rolling resistance : Experimental testing and constitutive modelling of tyres

Hyttinen, Jukka January 2022 (has links)
Global warming sets a high demand to reduce the CO2 emissions of vehicles. In the European Union heavy-duty road transports account for 6 % of the total greenhouse gases and one of the main factors affecting these emissions is related to the rolling resistance of tyres. The optimal usage of tyres is an important part of solving these challenges, thereby it is important to understand the parameters affecting rolling resistance and the different compromises coupled to them. These compromises could be analysed using computational and experimental methods. To set out the groundwork necessary to minimise the energy consumption of trucks and assess the different parameters affecting tyre behaviour, the following studies have been conducted during this thesis. A framework to model and parametrise truck tyre rubber has been developed for finite element simulations. The presented parallel rheological material model utilises Mooney-Rivlin hyperelasticity, Prony series viscoelasticity, and perfectly plastic networks. A method to reduce tuneable parameters of the model, which significantly simplifies possible parameter studies, is presented. The model has been parametrised using test data from dynamic mechanical analysis of samples from a long haulage heavy truck tyre, and shows a good agreement with the test data. To test the suitability of the modelling technique for tyre simulations, the constitutive model is used in various tyre simulations using the arbitrary Lagrangian-Eulerian method. The material modelling technique is shown to work for static force-deflection as well as dynamic simulations estimating longitudinal force build-up with varying slip levels. Additionally, the modelling technique captures the uneven contact pressure in steady-state rolling, which indicates that the model could also be used in rolling resistance simulations. To study the change of ambient temperature on rolling resistance using experimental methods, a climate wind tunnel is used where the rolling resistance is quantified using a measurement drum. Tests were conducted between -30 °C and +25 °C, and a considerable ambient temperature dependency on rolling resistance was found. Moreover, temperature measurement inside a tyre shoulder is a good indicator for rolling resistance in a broad range of ambient temperatures. Finally, battery-electric long haulage truck driving range calculations are also conducted with varying rolling resistance and air density at different temperatures, showing a significant decrease of driving range with decreasing ambient temperature. / Den globala uppvärmningen ställer höga krav på att minska tunga fordons CO2-utsläpp. Tunga transporter står för 6 % av de totala växthusgaserna i Europeiska unionen och att fokusera på optimal användning av däck är en viktig del för att minska förorenande växthusgaser. Därför är det viktigt att förstå parametrar som påverkar rullmotståndet och olika kompromisser kopplade till dem. Dessa kompromisser skulle kunna analyseras med hjälp av beräkningsmetoder och experimentella metoder. För att lägga grunden för att minimera energiförbrukningen för lastbilar och bedöma olika parametrar som påverkar däckens beteende, har följande studier genomförts i denna avhandling. Ett ramverk för att modellera och parametrisera lastbilsdäcksgummi utvecklades för finita elementmetod-simuleringar. Den presenterade parallella reologiska materialmodellen använder Mooney-Rivlin hyperelasticitet, Prony-series viskoelasticitet och perfekt plastiska nätverk. En metod har utvecklats för att reducera antalet justerbara materialparametrar i modellen, vilket avsevärt förenklar möjliga parameterstudier. Modellen har parametriserats med hjälp av testdata från dynamisk mekanisk analys och visar en god överensstämmelse mellan testdata och simuleringar. Provstavarna skars ut från ett lastbilsdäck för tunga fordon. För att testa modelleringsteknikens lämplighet användes den konstitutiva modellen i olika däcksimuleringar. Materialmodelleringstekniken har visat sig fungera för statisk vertikalstyvhet såväl som dynamiska simuleringar som uppskattar longitudinell kraftgenerering med varierande slipnivåer och olika friktionskoefficienter. Modelleringstekniken fångar ojämnt kontakttryck vid stationär rullning, vilket indikerar att modellen även kan användas i simuleringar av rullmotstånd. För att studera omgivningstemperaturens inverkan på rullmotståndet med experimentella metoder användes en klimatvindtunnel. Tester utfördes mellan -30 °C och +25 °C och rullmotståndet bestämdes med en mättrumma. Ett avsevärt beroende av omgivningstemperaturen på rullmotståndet påvisades. Dessutom indikerade provningen att temperaturmätning inuti däckskuldran är en bra indikator för rullmotstånd i ett brett område av omgivningstemperaturer. Räckviddsberäkningar för en elektrisk fjärrtransportlastbil utfördes med varierande rullmotstånd och luftdensitet vid olika temperaturer, vilket visade en signifikant minskning av körräckvidden med sjunkande omgivningstemperatur. / <p>QC 220525</p>
23

Preliminary analysis of the potential energy saving achievable with a predictive control strategy of a heat pump for a single family house

Braida, Giacomo, Tomasetig, Roberto January 2018 (has links)
The present work reports a study related to the potential improvement of the energy performances of a heat pump based heating system for a Swedish single-family house. The analysis is focused on the design of new rule-based control strategies which employ perfect predictions of weather forecast and human behaviour information. In particular, the considered signals are the outdoor temperature, the solar radiation, the internal gain due to inhabitants’ activities and the Domestic Hot Water (DHW) consumption. The study is performed by means of the TRNSYS® simulation software in which the model of the heating system is implemented. More specifically, it is composed by a Ground Source Heat Pump (GSHP) unit, a stratified storage tank of three hundred litres and the building element. The performances of the developed control logics are evaluated using a degree-minute on/off controller as reference case. The results show that the improved control logics yield to an increase of the energy efficiency of the system as well as an enhancement of the indoor and DHW temperatures stability. / EffSys Expand P18: Smart Cotnrol Strategies for Heat Pump Systems
24

Weather data for heat pump system control improvement: analysis of instantaneous and forecasted measurements and evaluation of potential energy savings

Monteggia, Mattia January 2018 (has links)
The present work deals with a study related to the analysis of weather data for heat pump system control improvement based on both instantaneous and forecasted measurements. In particular, the analysis is firstly focused on the comparison of multiple weather sources for the assessment of weather forecast uncertainties, based on the evaluation of errors in prediction with respect to measured values. Afterwards, the results are compared with the ones related to persistent predictions methods that assumes the state of the atmosphere to be stationary over the considered time interval. The development and testing of a new preliminary “predictive” control logic is also performed, thanks to TRNSYS numerical simulations, considering a typical Swedish single-family house located in Stockholm, with the aim of optimizing the operation of a heat pump heating system based on solar radiation prediction to yield energy and cost savings. With the crucial points of accuracy and precision by which the local weather processes can be predicted, the same TRNSYS model is run accounting for perfect predictions and solar radiation forecasted values. From this perspective, given the fact that forecast of solar radiation are usually absent within most of the weather forecast datasets, a deep analysis is also performed on hourly measurements of solar radiation to define a simple and effective methods to calculate hourly solar radiation predictions. The results show that, when a short-time horizon is considered, persistent predictions allow to provide forecasts with a sufficient accuracy, whereas, when longer horizon time are considered, significantly higher errors are calculated when persistent prediction techniques are adopted. Independently of the uncertainties considered for weather forecasts, the improved control logics demonstrated a potential for energy savings and improvements in indoor temperature stability when compared with a reference case of variable speed compressor with PID controller. / EffSys Expand P18: Smart Cotnrol Strategies for Heat Pump Systems
25

Black Guillemots as indicators of change in the near-shore Arctic marine ecosystem

Harter, B. Britten 14 September 2007 (has links)
This study attempted to explain an apparent inverse relationship between pack ice proximity and breeding success of Black Guillemots (Cepphus grylle) on Cooper Island, a barrier island in the western Beaufort Sea near Barrow, AK. I elucidated the first linear relationship between energy density and body size for the elusive Arctic Cod (Boreogadus saida). I discovered and ground-truthed the existence of previously unknown guillemot foraging habitat on small 50 m2 ice floes distant from the pack ice. I developed new daily metrics for quantifying the provisioning to linear (8 d – 18 d) and Post-Linear (19 d – fledge) chicks. I found daily consensus between Linear and Post-Linear chicks about the level of provisioning at the colony. Finally, I explained those daily changes with significant correlations with wind speed and direction. / October 2007
26

Black Guillemots as indicators of change in the near-shore Arctic marine ecosystem

Harter, B. Britten 14 September 2007 (has links)
This study attempted to explain an apparent inverse relationship between pack ice proximity and breeding success of Black Guillemots (Cepphus grylle) on Cooper Island, a barrier island in the western Beaufort Sea near Barrow, AK. I elucidated the first linear relationship between energy density and body size for the elusive Arctic Cod (Boreogadus saida). I discovered and ground-truthed the existence of previously unknown guillemot foraging habitat on small 50 m2 ice floes distant from the pack ice. I developed new daily metrics for quantifying the provisioning to linear (8 d – 18 d) and Post-Linear (19 d – fledge) chicks. I found daily consensus between Linear and Post-Linear chicks about the level of provisioning at the colony. Finally, I explained those daily changes with significant correlations with wind speed and direction.
27

Black Guillemots as indicators of change in the near-shore Arctic marine ecosystem

Harter, B. Britten 14 September 2007 (has links)
This study attempted to explain an apparent inverse relationship between pack ice proximity and breeding success of Black Guillemots (Cepphus grylle) on Cooper Island, a barrier island in the western Beaufort Sea near Barrow, AK. I elucidated the first linear relationship between energy density and body size for the elusive Arctic Cod (Boreogadus saida). I discovered and ground-truthed the existence of previously unknown guillemot foraging habitat on small 50 m2 ice floes distant from the pack ice. I developed new daily metrics for quantifying the provisioning to linear (8 d – 18 d) and Post-Linear (19 d – fledge) chicks. I found daily consensus between Linear and Post-Linear chicks about the level of provisioning at the colony. Finally, I explained those daily changes with significant correlations with wind speed and direction.
28

Inteligentní komponenty chytré domácnosti - SmartFlat / SmartFlat peripherials

Chytil, Jiří January 2016 (has links)
The theme of this thesis is the design of peripheral devices of a smart home SmartFlat and the design of communication interface for this system. Designed units are the humidity and temperature measuring unit, the unit of security and the smart socket unit for remote control, power measurement and power control. All units are designed for wired communicaton and also for wireless communication with control unit.
29

Mécanismes moléculaires de la perception de la température ambiante chez les plantes / Molecular mechanisms of temperature sensing in plants

Nayak, Aditya 28 March 2019 (has links)
La température ambiante joue un rôle direct dans le fonctionnement et le développement de la plante. L'augmentation des températures ambiantes mondiales pose un défi important aux espèces de plantes sauvages et cultivées. La plupart des espèces de plantes ajustent leur cycle de reproduction et leur développement pour optimiser leur survie et leur forme par temps ambiant élevé (Barnabás et al., 2008; Fitter et Fitter, 2002; Willis et al., 2008). Ces adaptations conduisent généralement à des hypocotyles allongés, à une réduction du nombre de feuilles au moment de la floraison, à une transition accélérée des phases de croissance végétative à reproductive, à une réduction du nombre de graines, à des gousses plus petites et à une diminution de la surface foliaire. Face au changement climatique rapide, en particulier à l'augmentation de la température permissive à la croissance ambiante, il est urgent de régler la thermoréponse des usines pour adapter les installations aux changements climatiques et garantir la production alimentaire future.L'expression de PIF4 est contrôlée par le complexe du soir (EC), un complexe à 3 protéines comprenant ELF3, ELF4 et LUX, en fonction de la température. La CE est capable de réprimer l'expression de PIF4 en se liant à des motifs spécifiques sur le promoteur de PIF4 à une température de croissance ambiante inférieure. Cependant, cette répression de l'expression de PIF4 est éliminée à une température ambiante de croissance plus élevée, ce qui entraîne un vieillissement prématuré des plantes.RésultatsLes trois protéines de la CE ont été produites en utilisant une stratégie d’expression différente, ELF4 et LUX dans E. coli, et ELF3 dans des cellules d’insecte. Les méthodes de purification des protéines et les tampons ont été optimisés pour obtenir des ELF3 et LUX stables. Une chromatographie d'exclusion de taille a été réalisée pour vérifier les états oligomères des protéines. LUX étant la seule protéine de la CE à posséder un domaine de liaison à l'ADN connu, elle a été utilisée pour effectuer des tests de déplacement de la mobilité afin de comprendre l'affinité de liaison de LUX pour ses motifs ADN cibles obtenus à partir de tests de puces de liaison de protéines. D'après les tests de décalage de mobilité, il a été observé que le domaine de liaison à l'ADN (DBD) seul pouvait se lier aux motifs d'ADN de son substrat à des concentrations molaires nano alors qu'une quantité de protéine excédentaire de 10 fois était nécessaire pour que la longueur totale de LUX obtienne la même quantité de liaison. Des pistes de cristallisation à haut débit ont été réalisées pour LUX et LUX-DBD pleine longueur avec deux motifs de liaison différents. Aucun cristal n'a été obtenu pour le LUX complet, alors que des cristaux ont été obtenus pour le LUX DBD avec les deux motifs d'ADN. La structure de LUX DBD en complexe avec ses motifs cibles a été résolue par diffraction aux rayons X. À partir de la structure Crystal, il a été constaté que LUX DBD avait adopté une structure à 3 hélices, la seconde hélice étant responsable de la lecture de la base. Fait intéressant, il a été observé qu'un résidu d'arginine présent au niveau de l'hélice n-terminale servait de pince pour interagir avec le motif ADN cible.En utilisant les tests de mutagenèse dirigée et de décalage de mobilité, il a été confirmé que cette arginine présente à la position 146 de la protéine est essentielle pour déterminer l'affinité. Il a été constaté que l'affinité de liaison était réduite d'un facteur 5 lorsque cet acide aminé était modifié. En outre pour comprendre son effet in planta. Les lignes de lux mutantes ont été complétées par une longueur totale de type sauvage et une version substituée par Arg14Ala de la longueur totale de LUX. Grâce à ces expériences, nous avons pu montrer que la complémentation complète du mutant R146A n’était pas observée, alors que la version de type sauvage était capable de compléter complètement le phénotype du mutant / Ambient temperature plays a direct role in plant functioning and development. Increase in global ambient temperatures poses a significant challenge to wild and cultivated plant species. Most plant species adjust reproductive timing and development to optimize survival and fitness in higher ambient temperatures (Barnabás et al., 2008; Fitter and Fitter, 2002; Willis et al., 2008). These adaptations generally lead to elongated hypocotyls, fewer leaves at time of flowering, accelerated transition from vegetative to reproductive growth phases, fewer seeds, smaller seed pods and decreased leaf area. In the face of rapid climate change, specifically increased ambient growth permissive temperatures, tuning plant thermoresponse is urgently needed to engineer plants for adaptation to climate change and for securing future food production.PIF4 expression is controlled by evening complex (EC), a 3 protein complex comprising of ELF3, ELF4 and LUX, in a temperature dependent manner. The EC is able to repress PIF4 expression by binding to specific motifs at the promoter of PIF4 at lower ambient growth temperature. However this repression of PIF4 expression is removed at higher ambient growth temperature leading to premature ageing of plantsResultsAll three proteins of EC were produced using different expression strategy, ELF4 and LUX in E. coli while ELF3 in insect cells. Protein purification methods and buffers were optimized to obtain stable ELF3 ELF4 and LUX. Size exclusion chromatography was done to verify oligomeric states of the proteins. Since LUX is the only protein in the EC which has known DNA binding domain, it was used for doing mobility shift assays to understand the binding affinity of LUX for its target DNA Motifs which were obtained from protein binding microarrays assays. From the mobility shift assays, it was observed that the DNA binding domain (DBD) alone could bind to its substrate DNA motifs at Nano molar concentrations while 10 fold excesses amount of protein was required for the full length LUX to obtain same amount of binding. High throughput crystallization trails were carried out for full length LUX and LUX- DBD with two different binding motifs. No crystals were obtained for full length LUX while Crystals were obtained for LUX DBD with both the DNA Motifs. Structure for LUX DBD in complex with its target motifs were solved through X-Ray diffraction. Using site directed mutagenesis and Mobility shift assays it was confirmed that this Arginine present at the 146 position of the protein is critical for determining affinity. It was found that the binding affinity was reduced by a factor of 5 when this amino acid was changed. Further to understand its effect in planta.. With this experiments we were able to show that with the R146A mutant full complementation wasn’t observed while the wildtype version was able to completely complement the mutant phenotype.To understand temperature based dynamics of the complex, ELF3, which is the most intrinsically disordered protein of the three proteins that constitute the complex, was studied for structural variation through CD spectroscopy and DLS experiments. From these experiments it was found that ELF3 attains a β-sheet like confirmation at higher temperature while a more globular confirmation at lower temperatures. It was found that this activity of ELF is reversible allowing for flexibility of the whole complex. We found that there were prion like domains in ELF3 protein which were primarily responsible for transition to β-sheet structure at higher temperature.In Order to engineer plants that could survive at higher ambient temperature, we decided to mutate promoter elements of PIF4 through CRISPR/Cas9 to obtain plants that can survive higher temperature.
30

Changes in a pollinator food web in the face of climate change: effects of physiological limitations and species interactions

Seidel, Melissa E. 07 August 2019 (has links)
No description available.

Page generated in 0.1126 seconds