The second law analysis is a powerful tool for assessing the performance of engines and has been employed for few decades now. Turbocharged diesel engines have been explored in much detail with the help of second law analyses. There is also a need to examine the turbocharged spark-ignition engines in greater detail using second law analyses as they are gaining popularity in high performance and conventional automobiles as well. A thermodynamic simulation was developed in order to investigate the effects of turbocharging on spark-ignition engines from second law perspective. The exergy values associated with the components of the turbocharger along with the engine components were quantified as a percentage of fuel exergy. The exergy balance values indicated that turbocharger does not add considerably to the overall irreversibilities and combustion irreversibility is still the major source of exergy destruction. A comprehensive parametric investigation was also performed to investigate the effects of compression ratio, intercooler effectiveness, etc. for the turbocharged spark-ignition engine over the entire load and speed range. The simulation studies helped in understanding the behavior of turbocharged sparkignition engine with these parameters. A simulation study was also performed to compare the turbocharged engine with the naturally aspirated spark-ignition engine. This study examined the engines for operating parameters like bmep and bsfc over the entire speed range and revealed that turbocharging offers higher bmep and lower bsfc values for most of the operating range. In an additional study, these engines were analyzed for the brake thermal efficiency values at part load. The results indicated that turbocharging offers marginally higher brake thermal efficiency at part loads.

As a most critical form of pre-silicon verification, transistor-level circuit simulation is an indispensable step before committing to an expensive manufacturing process. However, considering the nature of circuit simulation, it can be computationally expensive, especially for ever-larger transistor circuits with more complex device models. Therefore, it is becoming increasingly desirable to accelerate circuit simulation. On the other hand, the emergence of multi-core machines offers a promising solution to circuit simulation besides the known application of distributed-memory clustered computing platforms, which provides abundant hardware computing resources. This research addresses the limitations of traditional serial circuit simulations and proposes new techniques for both time-domain and frequency-domain parallel circuit simulations. For time-domain simulation, this dissertation presents a parallel transient simulation methodology. This new approach, called WavePipe, exploits coarse-grained application-level parallelism by simultaneously computing circuit solutions at multiple adjacent time points in a way resembling hardware pipelining. There are two embodiments in WavePipe: backward and forward pipelining schemes. While the former creates independent computing tasks that contribute to a larger future time step, the latter performs predictive computing along the forward direction. Unlike existing relaxation methods, WavePipe facilitates parallel circuit simulation without jeopardizing convergence and accuracy. As a coarse-grained parallel approach, it requires low parallel programming effort, furthermore it creates new avenues to have a full utilization of increasingly parallel hardware by going beyond conventional finer grained parallel device model evaluation and matrix solutions. This dissertation also exploits the recently developed explicit telescopic projective integration method for efficient parallel transient circuit simulation by addressing the stability limitation of explicit numerical integration. The new method allows the effective time step controlled by accuracy requirement instead of stability limitation. Therefore, it not only leads to noticeable efficiency improvement, but also lends itself to straightforward parallelization due to its explicit nature. For frequency-domain simulation, this dissertation presents a parallel harmonic balance approach, applicable to the steady-state and envelope-following analyses of both driven and autonomous circuits. The new approach is centered on a naturally-parallelizable preconditioning technique that speeds up the core computation in harmonic balance based analysis. The proposed method facilitates parallel computing via the use of domain knowledge and simplifies parallel programming compared with fine-grained strategies. As a result, favorable runtime speedups are achieved.

Fractured reservoirs are generally simulated using Warren and Root26 dual-porosity (DP) approach. The main assumption of this approach is that the geometry of fractures are uniformly distributed and interconnected in reservoirs. This may be true for many cases of naturally fractured reservoirs. However, for a large scale and disconnected fractured reservoirs, DP is often not applicable. Due to the latter case, it is necessary to have more sophisticated simulation studies which allow the fracture to be geometry explicitly represented into the static model using Discrete Fracture Network (DFN) approach. Most work on DFN grid model up to recently has been done with Delaunay tessellations. This research proposes an alternative technique to discretize the two-dimensional DFN using Voronoi diagrams, nevertheless applying the same DFN principles outlined in previous work. Through complicated procedures to generate DFN model, grid system based on Voronoi polygons has been developed. The procedure will force Voronoi edges follow the exact geometry of fractures. Furthermore, implementing the Voronoi diagrams allows the use of fewer polygons than the traditional Local Grid Refinement (LGR). And most importantly, due to the nature of the Voronoi polygons or locally orthogonal grids, the transmissibility calculations can be simplified and are more accurate than corner point formulation for non-square grid blocks. Finally, the main and most important goal of this study is to develop a black-oil Control Volume Finite Difference (CVFD) reservoir simulator that allows us to model DFN more realistically. One of the features of the developed simulator is the capability to model individual fractures with non-uniform aperture distribution, such as log-normally distributed apertures as shown using X-Ray CT scanner measurements. Prior to using the DFN simulator to model reservoirs with fractures and their apertures distribution, the simulator was validated against commercial simulators. The simulator provides results in close agreement with those of a reference finite-difference simulator in cases where direct comparisons are possible. Several simulations of synthetic DFN were presented to demonstrate the robustness of the Voronoi diagrams to represent fracture networks and its aperture distributions. In summary, the simulation of the DFN using the proposed approaches is capable to model both fractured and unfractured systems. However, the DFN model with Voronoi grids requires more efforts on building the grid model compared to other methods. Numerically, simulations of fractured systems are very challenging.

This thesis introduces a quasi-dynamic building simulation methodology which complements existing building simulators by allowing transient models of HVAC (heating, ventilating and air-conditioning) systems to be created in an analogous way to their design and simulated in a computationally efficient manner. The methodology represents a system as interconnected, object-oriented sub-models known as components. Fluids and their local properties are modeled using discrete, incompressible objects known as packets. System wide pressure and flow rates are modeled similar to electrical circuit models. Transferring packets between components emulates fluid flow, while the system wide fluid circuit formed by the components' interconnections determines system wide pressures and flow rates. A tool named PAQS, after the PAacketized Quasi-dynamic Simulation methodology, was built to demonstrate the described methodology. Validation tests of PAQS found that its steady state energy use predictions differed less than 3% from a comparable steady state model. PAQS was also able to correctly model the transient behavior of a dynamic linear analytical system.

In contrast to traditional conjugated polymer, the non-conjugated polycyanate network represents an interesting example to work with. Close packings among the phenylene and s-triazine rings in polycyanate may introduce £k-£k interaction and thereby, induce light emission. There is an important relationship between molecular packing and photo-luminescence properties. To clarify it, we also add aromatic fluorophore to hopefully alter the packing situation and from the response, further evaluation can be made. Detailed molecular packing in the network polycyanate can be evaluated by the molecular simulation technique. The simulation results for the pure polycyanate show that the most-likely inter-ring distance is 3 ~ 5

Abstract The steady thermocapillary motion in shallow enclosures is studied. Two different configurations, imposed heat flux and differentially heated side walls, are considered. A numerical simulation of the problem in the imposed heat flux case is made. The Pressure Correction Method is used to treat the pressure velocity coupling, in particular, the SIMPLER approximation. The discretization is made using central differences along with an appropriate non-uniform grid.

This dissertation intends to provide new tuning techniques for several simple cubic equations of state (EOS) to improve their accuracy in calculating fluid phase equilibrium. It also provides graphical tools to predict some phase equilibrium phenomena from activity coefficient models. Finally, it presents simulation results for a new gas-to-liquids process. Saturation Properties for Fluids: By deriving a new identity linking the heat of vaporization for pure components to the EOS, we are able to find new expressions for the two constants a & b in the EOS. These new expressions then allow tuning of both constants a and b to experimental saturation properties at subcritical temperatures. These new tuning procedures prove effective to the point where the simpler Redlich-Kwong EOS provides better results with our procedure than does the usually superior Peng-Robinson EOS with conventional procedures. Activity Coefficient Models: This dissertation shows the flexibility of four activity coefficient models in the prediction of three fluid phase equilibrium phenomena. From these models we successfully developed new graphs that allow one to identify the presence of any of the three phenomena by visual inspection without performing a complex calculation as seen in current texts. Remote Natural Gas: This dissertation presents simulation results of a new gas-to-liquids process which converts natural gas to liquid transportation fuels. Based on the assumption of adiabatic reactions, our simulation results show that methane conversion increases with higher reaction temperature and longer residence times. Hydrogen can both inhibit methane decomposition and reduce coke formation. The rich components in the natural gas are found to decompose very fast and they have a vast quenching effect on the whole reactions. Recycling of unreacted methane also increases overall methane conversion. Finally, our simulator provides very close prediction of the experimental results from a pilot plant. Thus, we conclude that the simulation work is basically successful in fulfilling the goal of this research.

This research investigated whether 4D construction model effectively helps project participants on construction sites in detecting time-space conflicts in the schedule. Previous researchers on construction space management typically modeled space requirements for equipment and paths for material and focused primarily on static or dynamic layout planning. Some researchers regarded time-space conflicts as an essential aspect of construction space management. They demonstrated the use of 4D modules in time-space conflict analysis. Although these 4D prototypes have been successful in tackling time-space conflict analysis, they have been validated with only post-hoc analysis of construction projects. Also, various currently commercially available 4D visualization softwares do not take into account the workspace required during the construction of a component unless space is modeled as a separate component into the CAD application. Therefore, without modeling space as a component in the 3D model it is necessary to assess whether 4D visualization can be effectively used on construction sites to detect time-space conflicts in the schedule. In order to fulfill the research goal an experiment was conducted. A 4D construction model of an ongoing project was developed. Project participants were introduced to two different graphic representations of the schedule; namely, an overlay drawing - the conventional method used on site to detect conflicts and the 4D construction model. Analysis of the results compared the performance of the participants in detecting time-space conflicts in the schedule using the two methods. The experiment produced empirical evidence that a 4D construction model may be effective on construction sites in detecting time-space conflicts in the schedule.

In this study, large scale rainfall simulation was used to evaluate runoff generation from canopy and intercanopy areas within an ashe juniper woodland of the Edwards Plateau. One 3 x 12 m site was established beneath the canopy of mature ashe juniper trees and two sites were established in intercanopy areas. At the base of each plot a trench was constructed for capturing and monitoring shallow subsurface flow. Rainfall simulations on the juniper site produced little surface runoff even though rainfall intensity exceeded 145mm/hour on some occasions. A total of 82.6% of the water applied to the juniper dominated site was accounted for as shallow subsurface flow. The dynamic nature of shallow subsurface flow indicate this process is driven chiefly by macropore flow. On the intercanopy site, 12.67% of the water left the site as surface runoff and ≤3% left as shallow subsurface flow. Large root channels and conduits, which were not present on the intercanopy site, within the soil may promote shallow subsurface flow beneath the juniper canopy. This study is the first to document and suggest shallow subsurface flow occurs on Texas rangelands. The results of this experiment indicate shallow subsurface flow is an important mode of runoff generation on the Edwards Plateau.

Teapot Dome field is located 35 miles north of Casper, Wyoming in Natrona County. This field has been selected by the U.S. Department of Energy to implement a field-size CO2 storage project. With a projected storage of 2.6 million tons of carbon dioxide a year under fully operational conditions in 2006, the multiple-partner Teapot Dome project could be one of the world's largest CO2 storage sites. CO2 injection has been used for decades to improve oil recovery from depleted hydrocarbon reservoirs. In the CO2 sequestration technique, the aim is to "co-optimize" CO2 storage and oil recovery. In order to achieve the goal of CO2 sequestration, this study uses reservoir simulation to predict the amount of CO2 that can be stored in the Tensleep Formation and the amount of oil that can be produced as a side benefit of CO2 injection. This research discusses the effects of using different reservoir fluid models from EOS regression and fracture permeability in dual porosity models on enhanced oil recovery and CO2 storage in the Tensleep Formation. Oil and gas production behavior obtained from the fluid models were completely different. Fully compositional and pseudo-miscible black oil fluid models were tested in a quarter of a five spot pattern. Compositional fluid model is more convenient for enhanced oil recovery evaluation. Detailed reservoir characterization was performed to represent the complex characteristics of the reservoir. A 3D black oil reservoir simulation model was used to evaluate the effects of fractures in reservoir fluids production. Single porosity simulation model results were compared with those from the dual porosity model. Based on the results obtained from each simulation model, it has been concluded that the pseudo-miscible model can not be used to represent the CO2 injection process in Teapot Dome. Dual porosity models with variable fracture permeability provided a better reproduction of oil and water rates in the highly fractured Tensleep Formation.