• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 37
  • 26
  • 8
  • 4
  • 3
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 92
  • 92
  • 25
  • 21
  • 15
  • 12
  • 8
  • 8
  • 7
  • 6
  • 6
  • 6
  • 6
  • 6
  • 6
  • 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.
41

[en] NUMERICAL AND EXPERIMENTAL STUDY ON SATURATED AND NON-SATURATED SOIL PROBLEMS / [pt] ESTUDO NUMÉRICO E EXPERIMENTAL DE PROBLEMAS DE FLUXO SATURADO - NÃO SATURADO EM SOLOS

MARLENE SUSY TAPIA MORALES 10 September 2008 (has links)
[pt] O estudo de fluxo saturado - não saturado em solos exige o conhecimento das funções de relação, como a curva característica (q x h) e a curva de condutividade hidráulica (K x h). Para determinar estas relações o presente trabalho utiliza o modelo de van Genuchten- Mualem, o qual está implementado numa ferramenta numérica que permite a utilização da retroanálise como método para determinação dos parâmetros do modelo. O principal objetivo deste trabalho é a avaliação de um método que permita a estimativa dos parâmetros do modelo de van Genuchten-Mualem, a partir de dados coletados em campo ou laboratório para, então, realizar-se a análise de fluxo saturado - não saturado e a estimativa dos parametros de van Genuchtem-Mualem. Finalmente, a as condições de fluxo saturado - não saturado em duas encostas foram simuladas, em duas e três dimensões, a fim de verificar a variação de fluxo nestes casos. / [en] The study of saturated and non saturated flow in soils requires the knowledge of relation functions, as water retention curve (q vs. h) and hydraulic conductivity curve (K vs. h).In order to determine these relations, this research uses van Genuchten-Mualem`s model, which is implemented on a numerical based method. This tool allows the inverse solution as a method to determine the parameters of the model. The main objective of this research is the evaluation of a method which allows the estimative of the required parameters by the chosen model, determined based on field or laboratory data, so then, based on these parameters, saturated and non- saturated flow analysis were carried out and the estimative of parameters of van Genuchten-Mualem`s model. Finally, saturated and non-saturated simulations were made on two slopes. These simulations were followed by 2D and 3D models, in order to verify the flow variation on these cases.
42

Cellular Reactions and Behavioral Changes in Focal and Diffuse Traumatic Brain Injury : A Study in the Rat and Mouse

Ekmark Lewén, Sara January 2013 (has links)
Traumatic brain injury (TBI) is a severe condition and a major cause of death and disability. There is no pharmacological treatment available in clinical practice today and knowledge of brain injury mechanisms is of importance for development of neuroprotective drugs. The aims of the thesis were to get a better understanding of astrocyte reactions and immune responses, as well as behavioral changes after focal unilateral cortical contusion injury and diffuse bilateral central fluid percussion injury in rats and mice. In the focal injury models, the astrocyte reactions were generally restricted to the ipsilateral hemisphere. After diffuse TBI, vimentin and glial fibrillary acidic protein (GFAP) positive reactive astrocytes were bilaterally expressed in brain regions even distant from the injury site, including regions where axonal injury was seen. Early after diffuse TBI, there was a robust immune response, including activation of macrophages/microglia (Mac-2+) and infiltration of neutrophils (GR-1+) and T-cells (CD3+). In order to measure functional outcome, the recently established Multivariate Concentric Square Field™ (MCSF) test for complex behaviors, including risk taking and explorative strategies was used. The Morris water maze (MWM) was applied for testing learning and memory. The MCSF test revealed alterations in risk taking, risk assessment and exploratory behavior, in the mice subjected to focal injury whereas mice subjected to the diffuse injury showed a deviant stereotyped behavior. After focal injury mice showed a decreased ability to adapt to the arena in the second trial, when tested repeatedly in the MCSF test. Mice subjected to diffuse injury had an impaired memory but not learning, in the MWM test. Post-injury treatment with the anti-inflammatory anti-interleukin-1β (IgG2 a/k) antibody showed a positive effect on functional outcome in the diffuse injury model. Altogether, the results demonstrate that focal and diffuse TBI models produce differences in cellular reactions and behavioral outcome and that the immune response plays a key role in the pathology after brain injury.
43

A NOVEL LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH MEMBRANE EXCHANGERS AND VARIOUS HEAT SOURCES

2015 September 1900 (has links)
Liquid desiccant air conditioning (LDAC) has received much attention in recent years. This is mainly because LDAC systems are able to control latent loads in a more energy efficient way than conventional air conditioning systems. Although many research studies have been conducted on LDAC technologies, the following gaps in the scientific literature are addressed in this thesis: (1) carryover of desiccant droplets in air streams, (2) direct comparisons between different configurations of LDAC systems, (3) fundamentals of capacity matching in heat-pump LDAC systems, (4) optimal-control strategies for heat-pump LDAC systems, and (5) importance of transients in evaluating the performance of a LDAC system. Items (1) to (4) are addressed using TRNSYS simulations, and item (5) is addressed using data collected from a field test. The use of liquid-to-air membrane energy exchangers (LAMEEs) as dehumidifiers and regenerators in LDAC systems eliminate the desiccant droplets carryover problem in air streams. This is because LAMEE separate the air and solution streams using semi-permeable membranes, which allow the transfer of heat and moisture but do not allow the transfer of the liquid desiccant. A preliminary configuration for a membrane LDAC system, which uses LAMEEs as the dehumidifier and regenerator, is proposed and investigated under fixed operating conditions in this thesis. The influences of key design and operating parameters on the heat and mass transfer performances of the membrane LDAC system are evaluated. Results show that the membrane LDAC technology is able to effectively remove latent loads in applications that the humidity to be controlled. A comprehensive evaluation is conducted in this thesis for the thermal, economic and environmental performances of several configurations of membrane LDAC systems. The solution cooling load is covered using a cooling heat pump in all systems studied, while the solution heating load is covered using one of the following five different heating systems: (1) a gas boiler, (2) a heating heat pump, (3) a solar thermal system with gas boiler backup, (4) a solar thermal system with heat pump backup, and (5) the condenser of the solution cooling heating pump. Each of the membrane LDAC systems studied is evaluated with/without an energy recovery ventilator (ERV) installed in the air handling system. The influence of operating the ERV under balanced/unbalanced operating conditions is studied. It is found that the most economic membrane LDAC system is the one which uses the evaporator and condenser of the same heat pump to cover the solution cooling and heating loads, respectively (i.e. heat-pump membrane LDAC system). No clear guidance was found in the literature for sizing the evaporator and condenser in a heat-pump LDAC system to simultaneously meet the solution cooling and heating loads. When the heating and cooling provided by the heat pump exactly match the heating and cooling requirements of the solution, the system is “capacity matched”. A parametric study is conducted on a heat-pump membrane LDAC system to identify the influence of key operating and design parameters on achieving capacity matching. It is concluded that the solution inlet temperatures to the dehumidifier and regenerator are the most influential parameters on the moisture removal rate, capacity matching and coefficient of performance (COP). Three control strategies are developed for heat-pump membrane LDAC systems, where these strategies meet the latent loads and achieve one of the following three objectives: (1) meet the sensible loads, (2) achieve capacity matching, or (3) optimize the COP. Results show that the COP of a heat-pump LDAC system can be doubled by selecting the right combination of solution inlet temperatures to the regenerator and dehumidifier. The importance of transients in evaluating the performance of a LDAC system is addressed in the thesis using a data collected from a field test on a solar LDAC system. It is found that the sensible, latent and total cooling energy, and the total primary energy consumption of the LDAC system are changed by less than 10% during an entire test day when transients are considered. Thus, it can be concluded that steady-state models are reliable to evaluate the energy performances of LDAC systems.
44

Early Environment and Adolescent Ethanol Consumption : Effects on Endogenous Opioids and Behaviour in Rats

Daoura, Loudin January 2013 (has links)
Excessive and compulsive ethanol drinking is one of the most serious public health issues. Therefore, it is vital to increase the knowledge about risks and protection for alcohol use disorders (AUD) to optimize prevention and treatment strategies. Ethanol consumption commonly initiates during adolescence when extensive neuronal maturation and development also occurs. Early exposure to ethanol is a risk factor for AUD, but the effects of adolescent drinking and the basis for the individual susceptibility to AUD are not fully understood. The interactions between genotype and environmental factors determine the individual risk for AUD and this thesis aimed to examine the environmental impact. The specific aims were to investigate 1) how early-life conditions affect adolescent voluntary ethanol drinking, behavioural profiles, endogenous opioids and response to treatment with an opioid antagonist (naltrexone), and 2) whether alterations detected in the offspring may be mediated by variations in maternal behaviour. A rodent maternal separation (MS) model was used to mimic a protective and risk-inducing early-life environment, respectively, with the use of 15 min (MS15) or 360 min (MS360) of daily MS. The main findings were 1) the MS360, but not the MS15 rats, responded to naltrexone following adolescent ethanol drinking; all adolescent rats had a high voluntary ethanol intake independent of early environmental conditions whereas in the adult groups the MS360, but not the MS15 rats, increased their ethanol intake and preference over time; adolescent ethanol exposure resulted in higher dynorphin levels in hippocampus and higher Met-enkephalin-Arg6Phe7 in the amygdala, independently of rearing conditions, 2) behavioural profiling using the multivariate concentric square field™ test showed: the young MS360 rats had increased risk assessment and risk taking behaviour compared to the young MS15 rats; the young MS15 rats increased, whereas the young MS360 rats decreased, their risk assessment and risk taking behaviour over time; differences in pup-retrieval strategies where the MS360 dams retrieved some pups into a safe area but as compared to MS15 rats they left more pups in a risk area; increased risk assessment behaviour in the MS360 dams immediately after weaning. Taken together, early-life environmental conditions alter adult but not adolescent drinking, the response to naltrexone, and behaviour in dams and offspring. Adolescent rats consumed more ethanol independent of rearing conditions and displayed increased opioid levels in brain areas related to cognition and addiction.
45

Vibrations in timber floors : Dynamic properties and human perception

Jarnerö, Kirsi January 2014 (has links)
Springiness and vibrations of timber floors are familiar to many as a ‘live’ feelwhen walking on them, especially if living in single family housing with timberframework. Since the building regulations in Sweden changed to performancedependentrequirements in 1994 the use of timber in multifamily housing hasincreased. New timber building systems have been developed and increasedbearing capacity of floors has made it possible to build with longer spans. Thelow mass of timber floors makes them more sensitive to dynamic loading byhuman activities, such as walking, running and jumping, compared to heavyfloors e.g. concrete floors. To improve vibration performance it is possible tochange the structural properties of the floors by increasing mass, stiffness ordamping properties. The most practicable solution is to increase the stiffness.Improved damping is also highly effective, but is difficult estimate and designaccurately since it originates from many sources in the finished building. In thepresent thesis the effects on dynamic properties from increased stiffnesstransverse to the load bearing direction of a floor have been assessed from testsin laboratory. The effect on dynamic performance of a timber floor fromelastic/damping interlayers (polyurethane elastomers) installed in the junctionsbetween walls and floors have been assessed in laboratory and in situ. Also thechange in dynamic properties of an in situ floor has been investigated atdifferent stages of construction and compared with results from laboratory tests.The present criteria for design of timber floors with respect to vibrationperformance were developed at a time when timber floors were mainly used insingle-family housing. The traditional timber joist floors differ in structuralbehaviour from the new types of floors developed recently. The experiencedvibration annoyance by residents in single- and multifamily housing differs asthe source of vibration disturbance and those who become disturbed aredifferent. The changed conditions give cause for a review of present designcriteria. A laboratory and field study on vibration performance was conductedwith questionnaires and dynamic performance measurements. The subjectiveand objective results were correlated and indicators for vibration acceptabilityand annoyance were assessed and new vibration performance criteria andvibration performance classes were suggested.
46

Stanovení personality na základě zpětných odchytů u norníka rudého (\kur{Clethrionomys glareolus}) / Assessment of animal personality based on recaptures in bank vole (\kur{Clethrionomys glareolus})

ELEXHAUSEROVÁ, Anna January 2013 (has links)
The aim of this study was to investigate the personality of bank vole using recaptures. Some behavioural types were determined (for example shy and bold) and influence of some factors on animal personality was defined (especially the daytime). The rate of repeatability of behaviour was also specified and the dependence of behaviour change on number of days between two captures was defined. Last, two types of tests used for animal personality were compared, indicating the differences between them.
47

Vliv rychlosti postnatálního vývoje na formování personality v chování / Influence of developmental rate on behavioral personality forming

SCHMIDTMAJEROVÁ, Eva January 2014 (has links)
The aim of this thesis was to empirically examine one of the theories regarding the laws of intraspecific variability in animal behavior, which assumes that differences in behavior are directly related to individual differences in the rate of growth. One of our most common rodents, common vole (Microtus arvalis) was chosen as a model species, mainly because lots of previous studies on this species have demonstrated, among other things, presence of consistent differences in behavior.
48

Projeto de uma perfuratriz multifuncional para execução de estacas e desenvolvimento de um ensaio de campo que utiliza o sistema de monitoração eletrônica da perfuratriz / Design of a multifunctional drilling rig for the construction of piles and development of a field test using its electronic monitoring system

Gilmar Wilian Barreto 14 November 2014 (has links)
Esta tese apresenta, o projeto de uma perfuratriz que permite a execução de cinco tipos de fundação profunda, e o desenvolvimento de um ensaio de campo que possibilita avaliar as resistências por atrito lateral desenvolvidas entre o instrumento envolvido pelo solo escavado e o terreno natural. A perfuratriz foi projetada para executar estacas dos tipos hélice contínua monitorada, escavadas com trado mecânico, hélice segmentada monitorada, raiz e hollow-auger. As estacas dos tipos hélice contínua monitorada e as escavadas com trado mecânico são muito utilizadas no Brasil; as estacas raiz e hollow-auger são utilizadas em situações especiais e a estaca hélice segmentada monitorada é mais recente, mas sua aplicação tem tido um crescimento importante nos últimos dez anos. Para a perfuratriz multifuncional são apresentados cálculos e desenhos básicos dos principais conjuntos. Para a nova investigação de campo, denominada FDT - Full Displacement Test, é apresentado um desenvolvimento teórico com base no princípio universal da conservação de energia que, em termos práticos, resulta na obtenção da parcela de atrito lateral, denominado atrito lateral unitário equivalente (fse). Os resultados obtidos a partir dos dados aquisitados pelo sistema de monitoramento eletrônico da perfuratriz apresentaram-se concordantes entre si, indicando a possibilidade de praticamente se conseguir a repetibilidade do ensaio. Entre os diversos ensaios realizados, foi dada ênfase aos ensaios realizados no campo experimental de Fundações e Geotecnia da Faculdade de Engenharia Agrícola FEAGRI, da Universidade de Campinas - UNICAMP e foram feitas correlações com as resistências obtidas nas provas de carga estáticas realizadas no local por Albuquerque (2001), a partir dos ajustes feitos para o nível instrumentado na profundidade de 11,70 m para o qual foi determinado um fator (G2), para cada tipo de estaca ensaiada (escavada, hélice contínua e ômega). A partir dos ajustes feitos para o nível 11,70 m foram feitas previsões de capacidade de carga por atrito lateral para os outros níveis instrumentados (5,00 m; 11,10 m e 12,00 m), sendo que os resultados apresentaram-se concordantes. / This thesis presents the design of a drilling rig that allows the execution of five types of deep foundation, and the development of a field test that allows measuring the skin friction resistance developed between the instrument involved by the excavated ground and the natural soil. The drilling rig was designed to make continuous flight auger, bored pile, continuous flight auger with segmented auger, root pile and hollow-auger pile. The continuous flight auger and bored piles are widely used in Brazil; the root pile and hollow-auger pile are used for in special conditions, and the continuous flight auger with segmented auger, is although more recent, but its application has had increased application grown in over the last ten years. For the multifunctional drilling rig, calculations and basic designs of the main sets are presented. For the new field test denominated FDT - Full Displacement Test, a theoretical development based on the universal principle of energy conservation was made carried out resulting and the result, in practical terms, was to obtain in the attainment of the skin friction defined in this thesis as equivalent unit skin friction (fse). The results obtained from the data acquired by the electronic monitoring system of drilling rigs were consistent among themselves, indicating the possibility of practically achieve the repeatability of the test. Among the various tests performed, emphasis was given to tests in the experimental field of foundations and geotechnics, of the College of Agricultural Engineering FEAGRI, Campinas University UNICAMP, and were correlated to the skin friction resistance obtained from the static load tests performed on site by Albuquerque (2001), based on the adjustments done to the instrumented level depth of 11.70 m, for which a factor (G2) was given in each type tested (bored, C.F.A and omega). From the adjustments made to the 11,70 m level, load-bearing capacity of skin friction predictions were made for other instrumented levels (5.00 m; 11.10 m and 12.00 m) presenting consistent results.
49

Comparação das respostas fisiológicas entre dois testes de carga constante: cicloergômetro e degrau / Comparison of the physiological responses between two constant load tests: cyclo ergometer and step

Rodrigues Junior, José Carlos 15 December 2017 (has links)
Submitted by Nadir Basilio (nadirsb@uninove.br) on 2018-07-19T17:29:15Z No. of bitstreams: 1 José Carlos Rodrigues Junior.pdf: 971813 bytes, checksum: 62c2be1a3750c4ab8d2efb12f062e157 (MD5) / Made available in DSpace on 2018-07-19T17:29:15Z (GMT). No. of bitstreams: 1 José Carlos Rodrigues Junior.pdf: 971813 bytes, checksum: 62c2be1a3750c4ab8d2efb12f062e157 (MD5) Previous issue date: 2017-12-15 / Introduction: The six-minute walk test (TC6) and shuttle walk test (SWT) are widely used for the assessment of functional capacity in patients with chronic obstructive pulmonary disease (COPD), however their execution may be limited by physical space. In this context, the step test has the facility of being able to be applied in any environment, including the home. However, there are no studies in the literature with constant load tests using the step and its physiological responses. Objectives: 1) to compare the physiological responses between the constant load tests on the cycle ergometer and the endurance step test 2) to establish the determinants of the performance obtained in the TDE, 3) to test the reproducibility of the TDE. Method: 19 patients with COPD performed spirometry, incremental and constant load test on cycle ergometer, bioimpedance to obtain muscle mass and incremental step test (TDI), responded to the Modified Medical Research Council modified dyspnea scale (MRCm) and the Saint George's Respiratory Questionnaire (SGRQ). Leg length was also evaluated and a maximal repetition test was performed. The TDE was performed with 80% of the number of steps obtained in the TDI. This should last for three to eight minutes. If the test time was less than three minutes, the TDE was again performed with 70% of the number of TDI steps. If the TDE was greater than eight minutes, the TDE was performed with a 90% load. Results: there was no difference between the metabolic and ventilatory responses between the TDE and the constant load test in cycle ergometer. No correlation was found between the performance of the TDE with the degree of airway obstruction, mass and quadriceps muscle strength. The time of TDE 90% was shown to be better reproducible compared to TDE 80%. Conclusion: the endurance step test provokes metabolic and ventilatory responses equated to the constant load test on cycle ergometer. / Introdução: O teste de caminhada de seis minutos (TC6) e o shuttle walk test (SWT) são vastamente utilizados para a avaliação da capacidade funcional em pacientes com doença pulmonar obstrutiva crônica (DPOC), entretanto sua execução pode ser limitada pelo espaço físico. Nesse contexto, o teste do degrau possui a facilidade de poder ser aplicado em qualquer ambiente, inclusive o domiciliar. Entretanto, não há na literatura estudos com testes de carga constante utilizando o degrau e suas respostas fisiológicas. Objetivos: 1) comparar as respostas fisiológicas entre os testes de carga constante no cicloergômetro e no teste do degrau endurance (TDE) 2) estabelecer os determinantes do desempenho obtido no TDE, 3) testar a reprodutibilidade do TDE. Método: 19 pacientes com diagnóstico de DPOC realizaram espirometria, teste incremental e de carga constante em cicloergômetro, bioimpedância para obtenção da massa muscular e o teste do degrau incremental (TDI), responderam à escala de dispneia Medical Research Council modificada (MRCm) modificada, e ao Saint George’s Respiratory Questionnaire (SGRQ). Também foi avaliado o comprimento de perna e realizado o teste de uma repetição máxima. O TDE foi realizado com 80% do número de degraus obtido no TDI. Este deverá ter uma duração de três a oito minutos. Caso o tempo do teste fosse menor do que três minutos, o TDE foi novamente realizado com 70% do número de degraus do TDI. Caso o TDE fosse superior a oito minutos, o TDE foi realizado com a carga de 90%. Resultados: não houve diferença entre as respostas metabólicas e ventilatórias entre o TDE e o teste de carga constante em ciclo ergômetro. Não foi encontrada correlação entre o desempenho do TDE com o grau de obstrução de vias aéreas, massa e força muscular de quadríceps. O tempo do TDE 90% mostrou-se com melhor reprodutibilidade, em comparação ao TDE 80%. Conclusão: o teste do degrau endurance provoca respostas metabólicas e ventilatórias equiparadas ao teste de carga constante em cicloergômetro.
50

Delay at bicycle passages and bicycle crossings

Ge, Fei January 2022 (has links)
In September 2014, a new regulation was proposed in Sweden, which indicates aset of rules of giving way under different types of bicycle intersections. Meanwhile,new definitions were endued to bicycle passages and bicycle crossings. After thepriority of cyclists is guaranteed at bicycle crossings, potential delay for motorvehicles in the mainstream should not be ignored as well.Therefore, inspired by the previous study from Movea, this thesis project is goingto focus on unsupervised bicycle passages and bicycle crossings, with the aim ofassessing and inspecting the impacts of different bicycle intersections on vehicledelays.The relationship between delay and flows at bicycle intersections has beenresearched in detail. Initially, an empirical study has been carried out on the basisof data from field measurements. In addition, a microscopic traffic simulationmodel has been constructed for the analysis of theoretical situations. The delay isproved to have a linear relationship with vehicle flow and bicycle flow. However,the linear relationship based on field data turns out to be different from the onefrom simulation output.

Page generated in 0.0493 seconds