In this study the phenomenon of compressible flow and heat transfer in a porous media is modeled based on fundamental principles. The conservation equations for the two phases are transformed by the method of volume averaging which is an analytic method used to unite the microscale and macroscale effects characteristic to porous media flows. Unique to this analysis is that the model is valid for oscillatory, cryogenic flows such as that occurring in a regenerative cryogenic refrigerator such as a Pulse Tube Cryocooler (PTC.) In a PTC the forced flow drive oscillations in the regenerator create Reynolds numbers high enough such that microscale inertial effects dominate the momentum equation. This phenomenon, known as the Forchheimer Effect, can be predicted and modeled based solely on fundamental principles and the method of volume averaging. The coefficients that characterize the Forchheimer momentum equation are determined experimentally. In addition to pressure gradients, heat transfer within a porous media occurs due to temperature gradients. Conduction within the solid and fluid phases is made evident by volume averaging, but the determination of the conductivity coefficients requires numerical experiments and is unique to the geometry and conductivities of the two phases. Convection between the two phases is the dominant mode of heat transfer within the porous media. Determination of the convective heat transfer coefficient for a porous media requires physical experiments. Heat transfer and pressure gradients in the porous media are always competing effects leading to a model which requires coupling of the momentum and energy equations. These competing effects are united with the concept of entropy generation which relies on the second law of thermodynamics. All real processes generate entropy, and the most efficient processes which balance pressure gradients and heat transfer generate minimum entropy. This concept of minimum entropy generation is unique. As a result, minimum entropy generation should always be used as the criteria for thermodynamic optimization of thermohydraulic systems.

Over the past three decades, coalbed methane (CBM) has moved from a mining hazard and novel unconventional resource to an important fossil fuel that accounts for approximately 10% of the U.S. natural gas production and reserves. The expansion of this industry required development of different drilling, completion and stimulation practices for CBM in specific North American basins, owing to the complex combinations of geologic settings and reservoir parameters encountered. These challenges led to many technology advances and to development of CBM drilling, completion and stimulation technology for specific geologic settings. The objectives of this study were to (1) determine which geologic parameters affect CBM drilling, completion and stimulation decisions, (2) identify to the engineering best practices for specific geologic settings, and (3) present these findings in decision charts or advisory systems that could be applied by industry professionals. To determine best drilling, completion and stimulation practices for CBM reservoirs, I reviewed literature and solicited opinions of industry experts through responses to a questionnaire. I identified thirteen geologic parameters (and their ranges of values) that are assessed when selecting CBM drilling, completion and stimulating applications. These are coal thickness, number of seams, areal extent, dip, depth, rank, gas content, formation pressure, permeability, water saturation, and compressive strength, as well as the vertical distribution of coal beds and distance from coal reservoirs to fracture barriers or aquifers. Next, I identified the optimum CBM drilling, completion and stimulating practices for specific combinations of these geologic parameters. The engineering best practices identified in this project may be applied to new or existing fields, to optimize gas reserves and project economics. I identified the best engineering practices for the different CBM basins in N.A and combined these results in the form of two decision charts that engineers may use to select best drilling and completion practices, as well as the optimal stimulation methods and fluids for specific geologic settings. The decision charts are presented in a Visual Basic Application software program to facilitate their use by engineers.

In this thesis, mixed finite element models of beams and plates bending are developed to include other variables (i.e., the membrane forces and shear forces) in addition to the bending moments and vertical deflection, and to see the effect of it on the nonlinear analysis. Models were developed based on the weighted residual method. The effect of inclusion of additional variables is compared with other mixed models to show the advantage of the one type of model over other models. For beam problems the Euler-Bernoulli beam theory and the Timoshenko beam theory are used. And for the plate problems the classical plate theory and the first-order shear deformation plate theory are used. Each newly developed model is examined and compared with other models to verify its performance under various boundary conditions. In the linear convergence study, solutions are compared with analytical solutions available and solutions of existing models. For non-linear equation solving direct method and Newton-Raphson method are used to find non-liner solutions. Then, converged solutions are compared with available solutions of the displacement models. Noticeable improvement in accuracy of force-like variables (i.e., shear resultant, membrane resultant and bending moments) at the boundary of elements can be achieved by using present mixed models in both linear and nonlinear analysis. Post processed data of newly developed mixed models show better accuracy than existing displacement based and mixed models in both of vertical displacement and force-like variables. Also present beam and plate finite element models allow use of relatively lower level of interpolation function without causing severe locking problems.

All living creatures, despite their profound diversity, share a common architectural building block: the cell. Cells are the basic functional units of life, yet are themselves comprised of numerous components with distinct mechanical characteristics. It is well established that cells have the ability to sense and respond to externally applied forces. However, the detailed mechanism of mechanosensation is still not clearly understood, and is an active area of research involving experimental and theoretical works. Mathematical modeling of the mechanical stimulus correlating to different experimental stimulation procedures forms the first step to understanding the mechanosensation in cellular system. In this thesis, a continuum -based computational model of living cells that explicitly incorporate the material properties of various cellular components are developed. In the constitutive modeling of cell, the continuum standard linear solid viscoelastic model (SLS), its natural extension for large scale deformation standard Neo-Hookean solid viscoelastic model (SnHS) as well as polymer mechanics- based dynamic shear modulus model was introduced. Finite element simulations of three widely used experiments- atomic force microscopy (AFM), magnetic twisting cytometry (MTC) and micropipette aspiration in the quantification of cell properties were carried out to verify the developed constitutive model. From the results of AFM finite element simulation, it was observed that the force-deformation and strain-relaxation curves obtained fit the experimental results very well. The influences of cytoplasm shear modulus which varies due to the formation of stress fiber, and cortex shear modulus which alters with the actin filament concentration factors and load frequency were systematically studied. Similarly, in magnetic twisting cytometry (MTC) simulation, the role of cytoplasm material properties, constant/sinusoidal forcing rates and various frequencies on the overall mechanical response of a cell was obtained. Numerical results are validated against experiments results. Micropipette aspiration simulation was also carried out in which the typical creep deformation test was carried out to study the viscoelastic behavior of the cell. Based on the results from finite element simulation, the effect of pipette radius, effect of cortex shear modulus and effect of pressure rate have been derived for the interpretation of the mechanical parameters from the micropipette aspiration.

Between 1850 and 1922, agriculturalists built 1,700 kilometers of levees to convert 250,000 hectares of tidal marsh to farmland where the San Joaquin and Sacramento Rivers enter the San Francisco Bay (the Delta). Drained, farmed and isolated from the water channels, the organic soils behind the levees subsided to elevations as low as 8 meters below sea level, turning "levees" into "dams" that hold back water constantly. Engineers built water transfer projects in the mid-20th century, transferring water from the south Delta to 25 million Californians who now rely on the "dams" accidentally converted into supply channels. In 1972, however, a levee failure caused a salt-water intrusion into the Delta, raising the prominence of the polemic Peripheral Canal which, if built would replace the levees in the trans-Delta water transport role. Levee failures in 2004 (the Delta) and 2005 (New Orleans) have re-ignited the debate, fueled by comments made by public officials who warned that the Delta levees posed more risk of failure than did the pre-Katina Louisiana levees. This background motivates two research questions: What are the social perspectives regarding levee failures of the experts managing the Delta; and what is the history of levee failures that might support their perspectives? The research employed Q-Method to identify and describe four social perspectives: Delta Sustainers, Abandon the Levees, Levee Pragmatists, and Multi-Purpose Levee Advocates. A critical element underlying differences among the perspectives revolved around the perceived history of failures of Delta levees. This dissertation employed semi-structured interviews, archival record searches, and historic map and aerial photograph comparisons to compile a history of 265 levee failures since 1868, many of which are referenced to location, segment, and levee type. In addition, the dissertation compiled a list of emergency repairs and successful flood-fights. The history of failures indicates that important levees of the Delta have performed significantly better than previously identified. Sharing these social perspectives and research results among the key actors addressing Delta issues may lead to improved consensus decisions.

In this thesis, we integrate the particular solutions of singularly perturbed partial differential equations into radial basis collocation method to solve two kinds of boundary layer problem.

In this thesis, we consider the inverse Toeplitz eigenvalue problem which recover a real symmetric Toeplitz with desired eigenvalues. First some lower dimensional cases are solved by algebraic methods. This gives more insight on the inverse problem. Next, we explore the geometric meaning of real symmetric Toeplitz matrices. For high dimensional cases, numerical are unavoidable. From our numerical experiments, Newton-like methods are very effective for this problem.

Using a numerical method to simulate the Metal-Organic Chemical Vapor Deposition (MOCVD). A study of the GaN films were growth on sapphire substrates, and a new design method which The position of carrier gas inlets and outlets, the gas in inlets by a showerhead reactor, the modified susceptor. The purpose of this research is to maintain deposited GaN film thickness variation range by controlling those parameters which may affect the deposition.

Listeria monocytogens can be found widely in nature. It can grow at refrigeration temperature, low pH, and high salt. The disease that it caused a fatality rate of 20% or higher makes L. monocytogens to be a famous foodborn pathogen. After a number of recent foodborn outbreaks, it has been demonstrated that this bacterium poses a significant health risk and has attracted the attention of the food safety professionals and public health officers. This thesis introduces the general characteristics of this bacterium, including its physiological and biochemical traits, virulent factors, infection routes, symptoms, therapy, and epidemiology. This thesis is also especially emphasized on the introduction and comparison of the differences, the advantages, as well as the disadvantages between the traditional and rapid diagnosis methods. According to the US FDA Bacterial Analytical Manual, the rapid tests had been classified into three classes: miniaturized biochemical kits, immunochemical kits, and genetic kits. The principles, formats, techniques, commercial products and its production companies of each diagnosis methods are also incorporated in this thesis. The advantages and disadvantages of these methods and their applications have been assessed. Finally, we also evaluated the market of the traditional methods being used and the rapid tests in the world, including the US, and European Union. In conclusion, the diagnosis of this important bacterium both by rapid methods or newly developed biochip and sensor will continue to grow in the future.

Proposing a math model and using enthalpy method to solve the temperature and flow field distribution around the bubble. Find the influence for different coefficients.