A máxima fase estável do lactato (MFEL) é considerada uma intensidade critica em exercício dinâmico e sua intensidade é específica do grupo etário. No entanto, apesar da relação existente entre a intensidade de esforço e os ajustes cardiovasculares, metabólicos e ventilatórios durante o exercício resistido, a MFEL foi muito pouco estudada neste tipo de exercício. O objetivo do estudo foi verificar e comparar a existência de MFEL nos exercícios leg press (LP) e supino reto (SR) em dois grupos: jovens e idosos. Além disso, analisar o comportamento das variáveis ergoespirométricas (VE, VO2 e VCO2), lactacidemia, freqüência cardíaca (FC), pressão arterial (PA) e percepção subjetiva de esforço (PSE) na intensidade da MFEL. Foram avaliados 13 homens jovens (26,1 +/- 2,9 anos) e 11 idosos (68,9 +/- 4,0 anos) saudáveis e com experiência mínima de 6 meses em treinamento resistido, que passaram por teste de 1 repetição máxima (1RM), teste crescente para determinação do limiar anaeróbio (LAn) e mais três sessões para a determinação da MFEL. Todas as sessões foram realizadas no mesmo horário do dia, separadas por 48 a 72 horas de intervalo. O LAn, expresso em %1RM, foi significativamente superior no LP em relação ao SR para os dois grupos estudados (LP: 27,8 +/- 3,6 %1RM nos jovens e 27,9 +/- 5,0% 1RM nos idosos; SR: 24,0 +/- 3,0% 1RM nos jovens e 21,5 +/- 3,1% 1RM nos idosos). Não foram observadas diferenças estatisticamente significativas na intensidade do LAn entre os grupos em cada aparelho. A lactacidemia na intensidade do LAn foi significativamente inferior no LP (1,86 +/- 0,63 mmol/L nos jovens e 1,23 +/- 0,34 mmol/L nos idosos) em relação ao SR (2,08 +/- 0,41 mmol/L nos jovens e 1,91 +/- 0,40 mmol/L nos idosos). A intensidade da MFEL no grupo de jovens foi 29,2 +/- 6,7% 1RM no LP e 21,7 +/- 4,4% 1RM no SR. No grupo e idosos, a MFEL ocorreu a 30,9 +/- 4,9% 1RM no LP e 23,3 +/- 6,6% 1RM no SR. A MFEL ocorre em intensidade significativamente menor no aparelho SR para os dois grupos (p < ou = 0,05), sem diferenças estatisticamente significativas entre os grupos. Não houve diferença significativa entre as intensidades do LAn e da MFEL para os dois grupos nos dois aparelhos. Durante a realização do exercício na MFEL, ocorreu a estabilização dos parâmetros ergoespirométricos, FC, PA e PSE entre a série 9 e série 15. Estes resultados demonstram que é possível determinar MFEL nos exercícios LP e SR para as duas populações estudadas. A MFEL ocorre em intensidades superiores no exercício LP. A intensidade da MFEL, expressa em percentual de 1RM, é semelhante à intensidade do LAn. / The maximal lactate steady state (MLSS) is considered a critical intensity of dynamic exercise and its intensity is specific to the age group. However, despite the relationship between exercise intensity and cardiovascular, metabolic and ventilatory adjustments during resistance exercise, the MLSS was unknown in this type of exercise. The purpose of the study was to verify and to compare if there is a maximal lactate steady state (MLSS) for leg press (LP) and bench press (BP) exercises in two different groups: young and older people. Furthermore, to evaluate the ventilatory responses (VE, VO2 e VCO2, blood lactate concentration (BLC), heart rate (HR), blood pressure and rate of perceived exertion (RPE) to those exercises performed on MLSS intensity. 13 young men (26,1 +/- 2,9 years) and 11 elderly healthy men (68,9 +/- 4,0 years) with a minimal experience of 6 months of resistance training volunteered for the study. Volunteers underwent a 1 repetition maximum test (1RM), an incremental test to determine anaerobic threshold (AT) and three more sessions to determine MLSS. Session were performed on the same time of day and separated by a 48-72 h interval. AT intensity (%1RM) was significantly higher for LP than BP for the two groups studied (LP: 27,8 +/- 3,6% 1RM for young group and 27,9 +/- 5,0% 1RM for elderly; BP: 24,0 +/- 3,0%1RM for young group and 21,5 +/- 3,1%1RM for elderly). There was no significant difference between groups in the AT intensity. BLC on AT was significantly lower for LP (1,86 +/- 0,63 mmol/L for young group and 1,23 +/- 0,34 mmol/L for elderly) than BP (2,08 +/- 0,41 mmol/L for young and 1,91 +/- 0,40 mmol/L for elderly). MLSS intensity for young group was 29,2 +/- 6,7% 1RM in LP and 21,7 +/- 4,4% 1RM in BP. For elderly, MLSS was 30,9 +/- 4,9% 1RM in LP and 23,3 +/- 6,6% 1RM in BP. MLSS intensity was significantly lower in BP for both groups (p < or = 0,05), with no statistical differences between groups. There was no significant difference between AT and MLSS intensities on both groups. During exercise on MLSS, ventilatory parameters, HR, blood pressure and RPE stabilized between set 9 and set 15. These results show that it is possible to identify MLSS on the LP and BP exercises for both populations. MLSS intensity is higher in LP exercise, when compared to BP. MLSS intensity is similar to the AT intensity.

O presente trabalho discute como uma mudança de paradigma econômico pode contribuir para uma economia ecologicamente responsável. Em linha com esse propósito num primeiro momento são apresentados os sinais da necessidade dessa mudança. Nessa primeira parte são apresentadas algumas das insuficiências das ferramentas econômicas tradicionais para uma harmonização com o meio ambiente. Num segundo momento são discutidas ideias alternativas para a abordagem da relação entre crescimento econômico e meio ambiente: economia e entropia, estado estacionário e prosperidade sem crescimento. Nessas discussões foi dada ênfase aos estudos dos economistas Nicholas Georgescu-Roegen, Herman Daly e Timothy Jackson. Na parte seguinte são discutidas as implicações éticas para o desenvolvimento de um modelo econômico ecologicamente responsável. Por fim, por meio do estudo da Comissão Stiglitz-Sen-Fitoussi, do Índice de Progresso Social e de Índices de Felicidade argumenta-se como novas medidas de desenvolvimento econômico, social e ambiental podem contribuir para um paradigma econômico ecologicamente responsável. / This study discuss how a change of economic paradigm could contribute to an environmentally responsible economy. In order to do this, at first, the signs of the need for this paradigm shift are presented. On this matter the shortcomings of traditional economic tools for harmonization with the environment are analysed. Secondly, alternative ideias to address the relationship between economic growth and the environment, such as economy and entropy, steady state, and prosperity without growth are discussed. In these discussions the studies of economists like Nicholas Georgescu-Roegen, Herman Daly and Timothy Jackson, are emphasized. In the next part of this study the ethical implications for the development of an environmentally responsible economic model are approached. Finally, through the study of the Stiglitz-Sen-Fitoussi Comssion, the Social Progress Index and Happiness Index, it is shown how new measures of economic, social and environmental development could contribute to an environmentally responsible economic paradigm.

The Monte Carlo method is, practically, the only approach capable of giving detail insight into complex neutron transport problems. In reactor physics, the method has been used mainly for determining the keff in criticality calculations. In the last decade, the continuously growing computer performance has allowed to apply the Monte Carlo method also on simple burnup simulations of nuclear systems. Nevertheless, due to its extensive computational demands the Monte Carlo method is still not used as commonly as deterministic methods. One of the reasons for the large computational demands of Monte Carlo criticality calculations is the necessity to carry out a number of inactive cycles to converge the fission source. This thesis presents a new concept of fission matrix based Monte Carlo criticality calculations where inactive cycles are not required. It is shown that the fission matrix is not sensitive to the errors in the fission source, and can be thus calculated by a Monte Carlo calculation without inactive cycles. All required results, including keff, are then derived via the final fission matrix. The confidence interval for the estimated keff can be conservatively derived from the variance in the fission matrix. This was confirmed by numerical test calculations of Whitesides's ``keff of the world problem'' model where other Monte Carlo methods fail to estimate the confidence interval correctly unless a large number of inactive cycles is simulated.   Another problem is that the existing Monte Carlo criticality codes are not well shaped for parallel computations; they cannot fully utilise the processing power of modern multi-processor computers and computer clusters. This thesis presents a new parallel computing scheme for Monte Carlo criticality calculations based on the fission matrix. The fission matrix is combined over a number of independent parallel simulations, and the final results are derived by means of the fission matrix. This scheme allows for a practically ideal parallel scaling since no communication among the parallel simulations is required, and no inactive cycles need to be simulated.   When the Monte Carlo criticality calculations are sufficiently fast, they will be more commonly applied on complex reactor physics problems, like non-linear steady-state calculations and fuel cycle calculations. This thesis develops an efficient method that introduces thermal-hydraulic and other feedbacks into the numerical model of a power reactor, allowing to carry out a non-linear Monte Carlo analysis of the reactor with steady-state core conditions. The thesis also shows that the major existing Monte Carlo burnup codes use unstable algorithms for coupling the neutronic and burnup calculations; therefore, they cannot be used for fuel cycle calculations. Nevertheless, stable coupling algorithms are known and can be implemented into the future Monte Carlo burnup codes. / QC 20100709

Hydraulic spool valves are found in most hydraulic circuits in which flow is to be modulated. Therefore their dynamic performance is critical to the overall performance of the circuit. Fundamental to this performance is the presence of flow reaction forces which act on the spool. These forces can result in the necessity of using two stage devices to drive the spool and in some cases have been directly linked to valve and circuit instabilities. As such, a great deal of research and design has concentrated on ways to reduce or compensate for flow forces. In one particular series of studies conducted on flow divider valves, it was established that a rim machined into the land of the spool reduced the flow dividing error by approximately 70-80%, and it was deduced that the main contribution to this error was flow forces. Direct verification of the claim regarding flow force reduction was not achieved and hence was the motivation for this particular study. <p> This thesis will consider the reaction (flow) force associated with a conventional spool land and one with a rim machined into it, and a modified form of the rimmed land referred to as a sharp edge tapered rim spool land. The rim and the sharp edge tapered rim were specially designed geometrical changes to the lands of the standard spool in order to reduce the large steady state flow forces (SSFF) inherent in the standard spool valve. In order to analyze the flow field inside the interior passages of the valve, three configurations of the spool were considered for orifice openings of 0.375, 0.5, 0.75 and 1.05 mm. Computational Fluid Dynamics (CFD) analysis was used to describe the fluid mechanics associated with the steady state flow forces as it provided a detailed structure of the flow through the valve, and to identify the flow mechanism whereby flow forces are reduced by the machining of a rim and tapered rim on the land of the spool. For all openings of the spool, the sharp tapered rim valve provides the largest reduction in SSFF. It was also observed that for all cases studied, the inflow SSFFs were smaller than for the outflow conditions. <p>The prediction of the steady state flow force on the rim spool was investigated in a flow divider valve configuration, and the results from the CFD analysis indicated a reduction by approximately 70%.

Hydraulic spool valves are found in most hydraulic circuits in which flow is to be modulated. Therefore their dynamic performance is critical to the overall performance of the circuit. Fundamental to this performance is the presence of flow reaction forces which act on the spool. These forces can result in the necessity of using two stage devices to drive the spool and in some cases have been directly linked to valve and circuit instabilities. As such, a great deal of research and design has concentrated on ways to reduce or compensate for flow forces. In one particular series of studies conducted on flow divider valves, it was established that a rim machined into the land of the spool reduced the flow dividing error by approximately 70-80%, and it was deduced that the main contribution to this error was flow forces. Direct verification of the claim regarding flow force reduction was not achieved and hence was the motivation for this particular study. <p> This thesis will consider the reaction (flow) force associated with a conventional spool land and one with a rim machined into it, and a modified form of the rimmed land referred to as a sharp edge tapered rim spool land. The rim and the sharp edge tapered rim were specially designed geometrical changes to the lands of the standard spool in order to reduce the large steady state flow forces (SSFF) inherent in the standard spool valve. In order to analyze the flow field inside the interior passages of the valve, three configurations of the spool were considered for orifice openings of 0.375, 0.5, 0.75 and 1.05 mm. Computational Fluid Dynamics (CFD) analysis was used to describe the fluid mechanics associated with the steady state flow forces as it provided a detailed structure of the flow through the valve, and to identify the flow mechanism whereby flow forces are reduced by the machining of a rim and tapered rim on the land of the spool. For all openings of the spool, the sharp tapered rim valve provides the largest reduction in SSFF. It was also observed that for all cases studied, the inflow SSFFs were smaller than for the outflow conditions. <p>The prediction of the steady state flow force on the rim spool was investigated in a flow divider valve configuration, and the results from the CFD analysis indicated a reduction by approximately 70%.

In this dissertation, we consider analytic and numeric approaches to the solution of probabilistic steady-state problems with specific applications in simulation and queueing theory. Our first objective on steady-state simulations is to develop new estimators for the variance parameter of a selected output process that have better performance than certain existing variance estimators in the literature. To complete our analysis of these new variance estimators, called linear combinations of overlapping variance estimators, we do the following: establish theoretical asymptotic properties of the new estimators; test the theoretical results on a battery of examples to see how the new estimators perform in practice; and use the estimators for confidence interval estimation for both the mean and the variance parameter. Our theoretical and empirical results indicate the new estimators' potential for improvements in accuracy and computational efficiency. Our second objective on steady-state simulations is to derive the expected values of various competing estimators for the variance parameter. In this research, we do the following: formulate the machinery to calculate the exact expected value of a given estimator for the variance parameter; calculate the exact expected values of various variance estimators in the literature; compute these expected values for certain stochastic processes with complicated covariance functions; and derive expressions for the mean squared error of the estimators studied herein. We find that certain standardized time series estimators outperform their competitors as the sample size becomes large. Our research on queueing theory focuses on pricing of the service provided to individual customers in a queueing system. We find sensitivity results that enable efficient computational procedures for dynamic pricing decisions for maximizing the long-run average reward in a queueing facility with the following properties: there are a fixed number of servers, each with the same constant service rate; the system has a fixed finite capacity; the price charged to a customer entering the system depends on the number of customers in the system; and the customer arrival rate depends on the current price of the service. We show that the sensitivity results considered significantly reduce the computational requirements for finding the optimal pricing policies.

The extreme operating conditions in deepwater drilling lead to serious relative problems. The knowledge of subsea temperatures is of prime interest to petroleum engineers and geo-technologists alike. Petroleum engineers are interested in subsea temperatures to better understand geo-mechanisms; such as diagenesis of sediments, formation of hydrocarbons, genesis and emplacement of magmatic formation of mineral deposits, and crustal deformations. Petroleum engineers are interested in studies of subsurface heat flows. The knowledge of subsurface temperature to properly design the drilling and completion programs and to facilitate accurate log interpretation is necessary. For petroleum engineers, this knowledge is valuable in the proper exploitation of hydrocarbon resources. This research analyzed the thermal process in drilling or completion process. The research presented two analytical methods to determine temperature profile for onshore drilling and numerical methods for offshore drilling during circulating fluid down the drillstring and for the annulus. Finite difference discretization was also introduced to predict the temperature for steady-state in conventional riser drilling and riserless drilling. This research provided a powerful tool for the thermal analysis of wellbore and rheology design of fluid with Visual Basic and Matlab simulators.

This thesis consists of two different research problems. In the first one, the heat transfer characteristic of wavy fin assembly with dehumidification is carried out. In general, fin tube heat exchangers are employed in a wide variety of engineering applications, such as cooling coils for air conditioning, air pre-heaters in power plants and for heat dissipation from engine coolants in automobile radiators. In these heat exchangers, a heat transfer fluid such as water, oil, or refrigerant, flows through a parallel tube bank, while a second heat transfer fluid, such as air, is directed across the tubes. Since the principal resistance is much greater on the air side than on the tube side, enhanced surfaces in the form of wavy fins are used in air-cooled heat exchangers to improve the overall heat transfer performance. In heating, ventilation, and air conditioning systems (HVAC), the air stream is cooled and dehumidified as it passes through the cooling coils, circulating the refrigerant. Heat and mass transfer take place when the coil surface temperature in most cooling coils is below the dew point temperature of the air being cooled. This thesis presents a simplified analysis of combined heat and mass transfer in wavy-finned cooling coils by considering condensing water film resistance for a fully wet fin in dehumidifier coil operation during air condition. The effects of variation of the cold fluid temperature (-5˚C - 5˚C), air side temperature (25˚C - 35˚C), and relative humidity (50% - 70%) on the dimensionless temperature distribution and the augmentation factor are investigated and compared with those under dry conditions. In addition, comparison of the wavy fin with straight radial or rectangular fin under the same conditions were investigated and the results show that the wavy fin has better heat dissipation because of the greater area. The results demonstrate that the overall fin efficiency is dependent on the relative humidity of the surrounding air and the total surface area of the fin. In addition, the findings of the present work are in good agreement with experimental data. The second problem investigated is the heat transfer analysis of confined liquid jet impingement on various surfaces. The objective of this computational study is to characterize the convective heat transfer of a confined liquid jet impinging on a curved surface of a solid body, while the body is being supplied with a uniform heat flux at its opposite flat surface. Both convex and concave configurations of the curved surface are investigated. The confinement plate has the same shape as the curved surface. Calculations were done for various solid materials, namely copper, aluminum, Constantan, and silicon; at two-dimensional jet. For this research, Reynolds numbers ranging from 750 to 2000 for various nozzle widths channel spacing, radii of curvature, and base thicknesses of the solid body, were used. Results are presented in terms of dimensionless solid-fluid interface temperature, heat transfer coefficient, and local and average Nusselt numbers. The increments of Reynolds numbers increase local Nusselt numbers over the entire solid-fluid interface. Decreasing the nozzle width, channel spacing, plate thickness or curved surface radius of curvature all enhanced the local Nusselt number. Results show that a convex surface is more effective compared to a flat or concave surface. Numerical simulation results are validated by comparing them with experimental data for flat and concave surfaces.

Biochemical reactions make up most of the activity in a cell. There is inherent stochasticity in the kinetic behavior of biochemical reactions which in turn governs the fate of various cellular processes. In this work, the precision of a method for dimensionality reduction for stochastic modeling of biochemical reactions is evaluated. Further, a method of stochastic simulation of reaction kinetics is implemented in case of a specific biochemical network involved in maintenance of long-term potentiation (LTP), the basic substrate for learning and memory formation. The dimensionality reduction method diverges significantly from a full stochastic model in prediction the variance of the fluctuations. The application of the stochastic simulation method to LTP modeling was used to find qualitative dependence of stochastic fluctuations on reaction volume and model parameters. / text

A liquid-to-air membrane energy exchanger (LAMEE) is a novel flat-plate membrane-based energy exchanger where heat and moisture transfer between air and solution streams occurs through a semi-permeable membrane. The LAMEE consists of many air and solution flow channels, each separated by a membrane. A small-scale single-panel LAMEE consists of a single pair of neighboring air and solution channels. This PhD thesis focuses on developing, testing and modeling the small-scale single-panel LAMEE, and investigating the similarity between the small-scale LAMEE and a full-scale LAMEE. This PhD thesis presents a methodology to investigate similarity between small-scale and full-scale energy exchangers. A single-panel energy exchanger test (SPEET) facility is developed and built to measure the performance of the small-scale single-panel LAMEE under different test conditions. Also, the small-scale LAMEE is numerically modeled by solving coupled heat and mass transfer equations for the air, solution and membrane of the LAMEE. The effects of membrane vapor diffusion resistance and enhanced air side convective heat transfer coefficient are numerically investigated. The numerical model of the small-scale LAMEE is validated with the experimental data for summer test conditions, and effectiveness values agree within ±4% in most cases. Moreover, the effects of different heat and mass transfer directions, and salt solution types and concentrations are experimentally and numerically investigated. The results show that the LAMEE effectiveness is strongly affected by the heat and mass transfer directions but negligibly affected by salt solution type and concentration. The solution-side effectiveness for liquid-to-air membrane energy exchangers is introduced in this thesis for the first time. The results show that the solution-side effectiveness should be used to evaluate the sensible and total effectiveness of LAMEE regenerators. Finally, the similarity between the small-scale and full-scale LAMEEs is investigated experimentally and numerically. The results show that the small-scale LAMEE effectiveness results can be used to predict the performance of a full-scale LAMEE within ±2% to ±4% in most cases.