With huge demands for potable water in regions lacking fresh water sources such as surface or ground water, various potential technologies have been explored for eliminating water shortage. Seawater emerged as a potential source and a major lifeline for such water-deprived areas. The development of seawater reverse osmosis (SWRO) technology proved to be a groundbreaking innovation, making it easier to extract pure water from seawater. Ever since its inception, SWRO technology has taken many leaps towards the development of energy efficient and high yielding systems. The reduction in energy consumption of desalination plants that were based on the SWRO technology emerged as a major driver of the technology revolution in this field. The improvement of membrane life and salt rejection, increase in recovery, and decrease in energy consumption has been the primary criteria for sifting through available technologies for incorporation in desalination plants. Many developments have, ever since, occurred in this direction. The membrane life has multiplied and the Total Dissolved Solids in the product are now as low as 100 mg/L. In addition, recoveries of 40-50% have been achieved. By recycling energy, many SWRO desalination plants have significantly lowered their total energy consumption. With the help of energy recovery devices (ERDs), it is now possible to decrease power consumption and increase efficiency of the seawater reverse osmosis desalination plant. The first large-scale municipal SWRO plant was installed in 1980 in Jeddah, Saudi Arabia. This plant consumed 8 kilowatt-hours energy per cubic meter of water produced. This consumed energy was less than half of what was usually consumed by other conventional distillation processes. However, the SWRO desalination technology has one disadvantage. The seawater, which is to be desalinated, is pressurized with the help of high-pressure pumps. A large amount of energy is consumed during this process. Once the desalination is complete, the remaining reject water has to be eliminated as waste. Since the brine reject produced in this process has a high pressure, simply dumping it back into the sea is a waste of energy. This pressure can be reused and thus, the energy could be recycled. This idea led to the innovation of energy recovery devices (ERDs) that prevent the wastage of energy in the SWRO process. The hydraulic energy in the highly pressurized reject brine can be re-used with the help of ERDs, and energy consumption can thus be reduced by significant high amounts. The development of ERDs helped in the set-up and operation of large-scale SWRO plants, and facilitated the economic viability of the desalination process. The energy requirements of conventional SWRO plants are presently as low as 1.6 kWh/m3, making the process more cost effective and energy efficient than other technologies. About 80% of the total cost of desalinated water is due to energy consumption and capital amortization. The remaining costs are associated with other maintenance operations such as replacement of membranes and other components, labor associated costs etc. Since energy consumption is the main determinant of final costs of the product, increasing energy efficiency of the plants is of primary concern. This paper deals with various energy recovery devices such as the Francis turbine, Pelton wheel, turbocharger, Recuperator, DWEER and Pressure Exchanger, used in SWRO desalination plants along with case studies associated with each of these. Special focus is given to the energy efficiency and costs associated with these devices. A brief discussion of the devices that are currently under investigation is also provided in the conclusion. An analysis of isobaric versus centrifugal devices is also conducted in this work. A comparison between the energy recovery turbine (ERT) manufactured by Pump Engineering Inc. (PEI) and the pressure exchanger (PX) manufactured by Energy Recovery Inc. (ERI) energy recovery systems is performed using collected data from provided water analyses and respective manufacturers' device specifications. The different configurations used for this comparison were applied to the Jeddah SWRO desalination plant for a total productivity of 240,000 m³/day. As a result of this analysis, the specific energy consumption of the ERT and PX configurations were 2.66 kWh/m3 and 2.50 kWh/m3 respectively. Analysis shows however that although the PX configuration achieved the best specific energy consumption, the ERT was favored over it due to its lower capital and maintenance costs. Therefore, the final conclusion of this work, in this special case, is that the ERT configuration is more economical than the PX configuration.

Asymmetric synthesis has become an important tool to prepare enantiomerically pure compounds because it avoids the wasteful discarding of the undesired enantiomer. Combinatorial libraries allow for much faster screening for new and better asymmetric catalysts/auxiliaries, but they generate a large number of samples whose enantiomeric excess (ee) cannot be determined rapidly. This bottleneck currently limits the applicability of such approaches. We propose here the use of faster optical techniques for the determination of ee using common instrumentation, such as UV-vis spectrophotometers, and circular dichroism (CD) spectrophotometers. Our methods are easily transitioned to the microwell format commonly used in parallel/combinatorial chemistry endeavors, just by using common microplate readers: this allows for an even more rapid analysis of samples and a seamless integration in a high-throughput workflow. We have shown that enantioselective indicator displacement assays can be developed to determine ee in a high-throughput fashion utilizing either a UV-vis spectrophotometer or a 96-well plate reader. Two chiral receptors and a commercial pH indicator were used to enantioselectively discriminate α-amino acids by monitoring the degree of indicator displacement. The two receptors were able to enantioselectively discriminate 13 of the 17 analyzed α-amino acids and accurately determine ee values of independent test samples with the use of ee calibration curves. Moreover, a sample of valine was synthesized through an asymmetric reaction, whose ee was then determined with our assay and compared to chiral HPLC and 1H NMR chiral shift reagent analysis, with excellent correlation. An artificial neural network was also successfully employed in the analyses, as an alternative to ee calibration curves. Both techniques consistently produced results accurate enough for preliminary determination of ee in a rapid manner, allowing for high throughput screening (HTS) of asymmetric reactions. The use of circular dichroism spectroscopy with chiral BINAP was also explored to enantioselectively discriminate α-chiral ketones. The ketones were derivatized with pyridyl hydrazines to produce hydrazones, which were then bound to enantiomerically pure [Cu(I)(BINAP)]+, forming diastereomeric complexes with differential steric interactions leading to different degrees of twist in the BINAP moiety and characteristic signatures in the CD spectrum, as a function of sample ee. / text

The research described here is part of a multi-university project on “Performance-based Seismic Design Methods and Tools for Reinforced Masonry Shear-Wall Structures.” Within the context of that project, the objective of the research described in this dissertation was to develop and validate a specific displacement-based seismic design methodology for masonry structures. Experimental work consisted of reversed cyclic loading tests of reinforced masonry wall segments with different boundary conditions, aspect ratios, axial loads, and reinforcement detailing. Analytical work consisted of developing analytical models for in-plane concrete masonry shear wall segments; calibrating those models using reversed cyclic test data; and using those models to successfully predict the nonlinear seismic response of two full-scale, multi-story reinforced masonry specimens tested on the shake-table at the University of California at San Diego. Design work consisted of the force-based and displacement based design of those specimens. Based on the results, provisions for displacement-based seismic design are proposed for inclusion in United States design codes. / text

Although many fracture models are based on two-dimensional plane strain approximations, accurately predicting fracture propagation geometry requires accounting for the three-dimensional aspects of fractures. In this study, we implemented 3-D displacement discontinuity (DD) boundary element modeling to investigate the following intrinsically 3-D natural or hydraulic fracture propagation problems: the effect of fracture height on lateral propagation of vertical natural fractures, joint development in the vicinity of normal faults, and hydraulic fracture height growth and non-planar propagation paths. Fracture propagation is controlled by stress intensity factor (SIF) and its determination plays a central role in LEFM. The DD modeling is used to evaluate SIF in Mode I, II and III at the tip of an arbitrarily-shaped embedded crack by using crack-tip element displacement discontinuity. We examine the accuracy of SIF calculation is for rectangular, penny-shaped, and elliptical planar cracks. Using the aforementioned model for lateral propagation of overlapping fractures shows that the curving path of overlapping fractures is strongly influenced by the spacing-to-height ratio of fractures, as well as the differential stress magnitude. We show that the angle of intersection between two non-coincident but parallel en-echelon fractures depends strongly on the fracture height-to-spacing ratio, with intersection angles being asymptotic for "tall" fractures (large height-to-spacing ratios) and nearly orthogonal for "short" fractures. Stress perturbation around normal faults is three-dimensionally heterogeneous. That perturbation can result in joint development at the vicinity of normal faults. We examine the geometrical relationship between genetically related normal faults and joints in various geologic environments by considering a published case study of fault-related joints in the Arches National Park region, Utah. The results show that joint orientation is dependent on vertical position with respect to the normal fault, the spacing-to-height ratio of sub-parallel normal faults, and Poisson's ratio of the media. Our calculations represent a more physically reasonable match to measured field data than previously published, and we also identify a new mechanism to explain the driving stress for opening mode fracture propagation upon burial of quasi-elastic rocks. Hydraulic fractures may not necessarily start perpendicular to the minimum horizontal remote stress. We use the developed fracture propagation model to explain abnormality in the geometry of fracturing from misaligned horizontal wellbores. Results show that the misalignment causes non-planar lateral propagation and restriction in fracture height and fracture width in wellbore part. / text

Dispersion has been shown to degrade miscibility in miscible displacements by lowering the concentration of the injected solute at the displacement fronts. Dispersion can also improve oil recovery by increasing sweep efficiency. Either way, dispersion is an important factor in understanding miscible displacement performance. Conventionally, dispersion is measured in the laboratory by fitting the solution of one-dimensional convection-dispersion equation (CDE) to the effluent concentration from a core flood. However dispersion is anisotropic and mixing occurs in both longitudinal and transverse directions. This dissertation uses the analytical solution of the two-dimensional CDE to simultaneously determine longitudinal and transverse dispersion. The two-dimensional analytical solution for an instantaneous finite volume source is used to investigate anisotropic mixing in miscible displacements. We conclude that transverse mixing becomes significant with large a concentration gradient in the transverse direction and significant local variation in flow directions owing to heterogeneity. We also utilized simulation models similar to Blackwell's (1962) experiments to determine transverse dispersion. This model coupled with the analytical solution for two-dimensional CDE for continuous injection source is used to determine longitudinal and transverse dispersivity for the flow medium. The validated model is used to investigate the effect of heterogeneity and other first contact miscible (FCM) scaling groups on dispersion. We derive the dimensionless scaling groups that affect FCM displacements and determine their impact on dispersion. Experimental design is used to determine the impact and interactions of significant scaling groups and generate a response surface function for dispersion based on the scaling groups. The level of heterogeneity is found to most significantly impact longitudinal dispersion, while transverse dispersion is most significantly impacted by the dispersion number. Finally, a mathematical procedure is developed to use the estimated dispersivities to determine a-priori the maximum grid-block size to maintain an equivalent level of dispersion between fine-scale and upscaled coarse models. Non-uniform coarsening schemes is recommended and validated for reservoir models with sets of different permeability distributions. Comparable sweep and recovery are observed when the procedure was extended to multi-contact miscible (MCM) displacements. / text

Determining the presence of an analyte of interest, and finding the enantiomeric purity of chiral molecules are challenging tasks. This work in molecular recognition is carried out routinely by many different researchers, including both academic as well as industrial research groups. The following dissertation presents original research directed toward two different areas of interest to the molecular recognition community: enantioselective sensing in solution, and sensing at a defined interfacial environment. This work begins with a review of the non-chromatographic ways that the enantiomeric purity of chiral carboxylic acids is determined, presented in Chapter 1. Carboxylic acids are important functional groups, both for organic synthesis as well as pharmaceutical drug development. Chapter 2 presents efforts that have been made to rapidly assess both the enantiomeric purity and identity of chiral carboxylic acids, utilizing the technique of exciton-coupled circular dichroism (ECCD). A twist is imparted on a complex, and can be correlated with the absolute configuration of the stereocenter. The enantiomeric composition can be rapidly determined. After creating the assay, the focus of the work shifted toward applying this system to new classes of analytes. Chapter 3 covers chemo- and enantioselective differentiation of [mathematical symbol]-amino acids, and continues to discuss the expansion to [mathematical symbol]-homoamino acids. Then a synthetic substrates was tested, and a series of reactions screened to determine if any enantioselectivity had been imparted by a Baeyer-Villiger oxidation. Finally, the enantiomeric composition of a biaryl atropisomer, a compound lacking a stereocenter, was determined. The signal produced from this assay is at a relatively short wavelength, and efforts were undertaken to push this signal to longer wavelength. Chapter 4 is a compendium of the lessons that were learned upon attempting to create a self-assembled sensing system. The final chapter details work that was done in collaboration with Professor Katsuhiko Ariga at the National Institute of Materials Science in Tsukuba, Japan. In this chapter, an indicator displacement assay was carried out for the first time at the air-water interface. This contribution opens the door for sensing to be carried out at defined regions, rather than free in bulk solution. / text

Successful creations of multiple hydraulic fractures in horizontal wells are critical for economic development of unconventional reservoirs. The recent advances in diagnostic techniques suggest that multi-fracturing stimulation in unconventional reservoirs has often caused complex fracture geometry. The most important factors that might be responsible for the fracture complexity are fracture interaction and the intersection of the hydraulic and natural fracture. The complexity of fracture geometry results in significant uncertainty in fracturing treatment designs and production optimization. Modeling complex fracture propagation can provide a vital link between fracture geometry and stimulation treatments and play a significant role in economically developing unconventional reservoirs. In this research, a novel fracture propagation model was developed to simulate complex hydraulic fracture propagation in unconventional reservoirs. The model coupled rock deformation with fluid flow in the fractures and the horizontal wellbore. A Simplified Three Dimensional Displacement Discontinuity Method (S3D DDM) was proposed to describe rock deformation, calculating fracture opening and shearing as well as fracture interaction. This simplified 3D method is much more accurate than faster pseudo-3D methods for describing multiple fracture propagation but requires significantly less computational effort than fully three-dimensional methods. The mechanical interaction can enhance opening or induce closing of certain crack elements or non-planar propagation. Fluid flow in the fracture and the associated pressure drop were based on the lubrication theory. Fluid flow in the horizontal wellbore was treated as an electrical circuit network to compute the partition of flow rate between multiple fractures and maintain pressure compatibility between the horizontal wellbore and multiple fractures. Iteratively and fully coupled procedures were employed to couple rock deformation and fluid flow by the Newton-Raphson method and the Picard iteration method. The numerical model was applied to understand physical mechanisms of complex fracture geometry and offer insights for operators to design fracturing treatments and optimize the production. Modeling results suggested that non-planar fracture geometry could be generated by an initial fracture with an angle deviating from the direction of the maximum horizontal stress, or by multiple fracture propagation in closed spacing. Stress shadow effects are induced by opening fractures and affect multiple fracture propagation. For closely spaced multiple fractures growing simultaneously, width of the interior fractures are usually significantly restricted, and length of the exterior fractures are much longer than that of the interior fractures. The exterior fractures receive most of fluid and dominate propagation, resulting in immature development of the interior fractures. Natural fractures could further complicate fracture geometry. When a hydraulic fracture encounters a natural fracture and propagates along the pre-existing path of the natural fracture, fracture width on the natural fracture segment will be restricted and injection pressure will increase, as a result of stress shadow effects from hydraulic fracture segments and additional closing stresses from in-situ stress field. When multiple fractures propagate in naturally fracture reservoirs, complex fracture networks could be induced, which are affected by perforation cluster spacing, differential stress and natural fracture patterns. Combination of our numerical model and diagnostic methods (e.g. Microseismicity, DTS and DAS) is an effective approach to accurately characterize the complex fracture geometry. Furthermore, the physics-based complex fracture geometry provided by our model can be imported into reservoir simulation models for production analysis. / text

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Despite the importance of single particle motion in biological systems, systematic inference approaches to analyze particle trajectories and evaluate competing motion models are lacking. An automated approach for robust evaluation of motion models that does not require manual intervention is highly desirable to enable analysis of datasets from high-throughput imaging technologies that contain hundreds or thousands of trajectories of biological particles, such as membrane receptors, vesicles, chromosomes or kinetochores, mRNA particles, or whole cells in developing embryos. Bayesian inference is a general theoretical framework for performing such model comparisons that has proven successful in handling noise and experimental limitations in other biological applications. The inherent Bayesian penalty on model complexity, which avoids overfitting, is particularly important for particle trajectory analysis given the highly stochastic nature of particle diffusion. This thesis presents two complementary approaches for analyzing particle motion using Bayesian inference. The first method, MSD-Bayes, discriminates a wide range of motion models--including diffusion, directed motion, anomalous and confined diffusion--based on mean- square displacement analysis of a set of particle trajectories, while the second method, HMM-Bayes, identifies dynamic switching between diffusive and directed motion along individual trajectories using hidden Markov models. These approaches are validated on biological particle trajectory datasets from a wide range of experimental systems, demonstrating their broad applicability to research in cell biology.

At broad scales, community ecologists study how biogeographic factors like environmental dissimilarity and geographic distance influence community assembly and composition. At small scales, community ecologists study how one or several species interact to determine habitat partitioning and coexistence. In this dissertation, I present studies at both scales. Chapter One investigates community assembly across the Caribbean, Central, and South American radiations of Anolis lizards and Eleutherodactylid frogs to test whether oceanic islands are unique in their assembly processes. Such uniqueness is suggested by high levels of endemism on islands; however, comparable levels of endemism can be found in mainland communities. I modeled the rate of species turnover between mainland communities, with respect to geographic distance and environmental dissimilarity, and then used the mainland model to predict turnover among islands. Turnover among island communities was significantly higher than predicted from the mainland model, confirming the long-held but untested assumption that island assemblages accumulate biodiversity differently than their mainland counterparts. Chapter Two reviews the evidence for ecological character displacement (ECD), an evolutionary process whereby two resource competitors diverge from one another in phenotype and resource use, facilitating coexistence in a community. I find that, despite current scientific opinion, the evidence for ECD is equivocal; most cases of ECD pattern fail to rule out processes alternative to resource competition that could create the same pattern. I conclude that better evidence may come from real time tests of ECD. Chapters Three and Four describe just such a test in small island populations of Anolis carolinensis. In Chapter Three, I find that small island populations of A. carolinensis that have come into sympatry with a novel competitor, the invasive A. sagrei, shift their habitat use to become more arboreal, compared to allopatric populations. Consistent with prediction, individuals from sympatric populations have larger toepads with additional adhesive scales - a common adaptation to arboreality in Anolis. In Chapter Four, I describe a common garden experiment that finds that the observed toepad divergence is an evolved response, suggesting rates of divergence for toepad area and scale number on par with well known examples of contemporary evolution.