Browsing by Subject "Computer simulation"
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Item A Windows-based application for predicting automobile engine heat rejection requirements(Texas Tech University, 2004-05) Williams, Andrew KThe ability to predict engine heat rejection rates quickly and efficiency provides automotive cooling system engineers the flexibility to alter designs without the time and costs of laboratory experimentation. The purpose of this research is to develop an analytical tool that predicts engine heat rejection to coolant rates using a physics-based methodology. Using Microsoft Visual C++ 6.0, an application has been developed that calculates the engine heat rejection rates for naturally aspirated gasoline engines and turbocharged diesel engines using a minimal amount of engine operating parameters. Standard engine power and heat transfer correlations can be used, or new correlations can be developed for a specific engine using dynamometer data input directly into the program. The final engine heat rejection rate predictions are presented to the user in both tabular and graphical formats. Completed engine heat rejection predictions provide engineers the opportunity to refine their cooling system designs, and thus reduce overall design time and cost.Item Adaptive finite element simulation of flow and transport applications on parallel computers(2007-05) Kirk, Benjamin Shelton, 1978-; Carey, Graham F.The field of molecular and atomic sensing has seen a vast growth over the last few decades. Yet many advances still remain to be made. This dissertation takes an in depth look at the two major aspects in a molecular sensing or signaling scaffold—namely the binding of a target followed by the transduction of an observable signal. Chapter 1 will deal with intermolecular binding forces in the form of a case study on electrophilic coordination to carbonyl compounds. Computational studies are performed to determine the optimal geometry of an electrophile interacting with a carbon acid to affect the greatest enhancement in the acidity at the α-carbon. We find that partial interaction through the π-system of the carbonyl and the resulting enolate affords the greatest acidity enhancement. Chapter 2 then switches to studies on the development of a novel signaling method for a molecular signaling assay. Two novel elements—transition metal catalytic signal amplification and peroxyoxalate chemiluminescence—are utilized to generate a signaling motif incorporating two new methodologies for signal generation. The first uses of catalytic signal amplification for the detection of small organic analytes and peroxyoxalate chemiluminescence for signal generation in a molecular recognition event are described. Finally, both elements are brought together in Chapter 3, which describes a mature ionophoric chemodosimeter with both highly sensitive binding and strong signal output. The use of a squaraine dye as a signaling unit for the detection of palladium(II) salts is described in which an aliphatic thiol acts as the theoretical “host” in a covalent displacement type assay. Palladium(II) and other transition metal detection is of importance both industrially and environmentally, and the assay described is sensitive to levels desired in both arenas.Item Adaptive finite element simulation of flow and transport applications on parallel computers(2007) Kirk, Benjamin Shelton; Carey, Graham F.Item An artificial neural network for wind-induced damage potential to nonengineered buildings(Texas Tech University, 1996-12) Sandri, PraveenExtreme winds such as hurricanes and tomadoes can be extremely destmctive and result in catastrophic property losses and loss of human lives. The need to predict damage and reduce loss of life and property is becoming more important with increasing urban sprawl. Artificial Neural Networks (ANNs) provide a novel approach for representing the wind-induced damage potential prediction model. Modeled loosely after the biological neural networks of the human brain, ANNs are generally used in situations where the interactions between the input and the output variable are too complicated for an analytical solution or where there is not suflficient understanding of the problem domain. Predicting wind-induced damage potential to nonengineered buildings is not a simple task because of the complexity of constmction and limited understanding of the wind efifects on buildings. This research concentrates on the investigation of the applicability of ANNs to wind-induced damage potential prediction and the corresponding implementation issues. Even after years of post disaster windstorm damage investigations consistent, complete and robust damage information is not available to train the ANN. Thus, synthetic data instead of observed building damage information is used. WIND-RITE*, a knowledge based expert system for grading individual buildings in windstorms is used to provide the necessary damage information for the synthetic data. This research shows that a feedforward multi-layer neural network with a modified backpropagation learning algorithm can be used effectively to model wind-induced damage potential predictions for nonengineered buildings. As few as four hundred building samples are suflficient to train the network to leam the underlying relationships between the features of the building and its corresponding building damage potential. During training the ANN model is able to leam the relationships between the input features and the resulting building damage grade eflfectively. It was also found that the ANN is able to predict reasonably for samples it has not seen before.Item An evaluation of simulation packages with animation(Texas Tech University, 1988-08) Latorraca, DomingoIt was the purpose of this research to consider four simulation software packages with animation capabilities for the microcomputer (SIMFACTORY'^, GPSS/PC*^^, SIMAN"^^ and XCELL+^^), study and submit them to specific tests which will determine the degree of flexibility, capability and applicability of these languages. These four packages were selected based on two factors; the first one was simply the availability of all four packages to the investigator. The second reason behind the selection of these packages was that GPSS/PC and SIMAN are popular and widely used; in contrast, SIMFACTORY and XCELL+ are not as common, but present great user friendliness. All four packages were submitted to the same tests to draw conclusions; these conclusions helped determine how these packages perform by comparing them with each other. The conclusion of the research was not which package is best. Rather, the desired results were the ability to determine the capabilities and limitations of each software package and assistance in determining which package is most appropriate for the particular needs of a potential user.Item Automobile traffic accident simulation using three-dimensional computer graphics(Texas Tech University, 1995-08) Zedan, Thoraya FaysalThe main purpose of this study is to develop graphics appropriate to an automobile accident simulator. The graphics implementation of the dynamics is to be developed to aid various and different observers, investigators or students in developing an understanding of the accident events. The simulator will be used to graphically display a traffic accident that occurred about a mile east of Farwell, Texas, on U.S. 60 at about 3:30 a.mu on January 21, 1994 [2, 15]. The accident resulted in the deaths of three young men. The development of the simulation will be acconq)hshed through the use of a mathematical model that simulates the effects of a collision between two vehicles. The mathematical model that is used in this simulation is based on physical laws, but is greatly simplified.Item Auxiliary power system for HEV(Texas Tech University, 2000-05) Alam, Md. ShahedulDriving the automobiles with a power generating unit other than an IC Engine is one of the main focus areas of present day Advanced Vehicle Engineering research. In this regard, the use of a fuel cell in combination with a power converter and motor as an alternative to the IC Engine as the primary power source for an automobile is very attractive. This thesis develops model of a series hybrid vehicle with a PEM fuel cell as its Auxiliary Power Unit (APU). Simulation using the model helps to provide an understanding of the interaction and flow of power. Moreover, electrical power sharing between the APU and the Electrical Storage System (ESS) is shown. Conclusions and scope of future work are also discussed.Item Bluetooth frequency hop prediction(Texas Tech University, 2002-05) Sandidge, John MThis project details the prediction of Bluetooth frequency hops. The main focus of this design is to promote coexistence with IEEE 802.1 lb using adaptive frequency hopping. This thesis reviews Bluetooth history, Bluetooth channel hopping, a model of a frequency hop predictor and simulation results of the model.Item Comparison of geometric visualization and finite difference method in analyzing the casting processes(Texas Tech University, 2001-05) Habib, Shah G. B.In this thesis, the capabilities of two analysis tools are discussed for two different casting processes - Permanent molding and High pressure die casting process. One of them is the easy-to-use pure geometry-based method and the other one is the more accurate and reliable tool based on the finite difference method. Both the tools have their own characteristics and capabilities. The geometry-based tool, CastView can produce the analysis result in just a few minutes, whereas the finite difference method based software. MAGMASoft gives the analysis result for the same model in a few hours. Sometimes, it may take a day or two, if the design is complex and the number of cycles for simulation is more than one. Despite the fact that, CastView uses only the part geometry itself to provide information about the part and its die casting features in visual and animated form, its primary advantage is that it requires virtually no setup and provides results very quickly. So a quick evaluation of the alternative parting and gating options can be checked considering the balance in the fill pattem and characteristics of the fill path. However, the simulation in MAGMASoft may take a longer time but results here are more accurate and reliable. We used two geometry models for two different casting methods to analyze the capabilities of these two tools. Techniques calculations of the distance to the gate from the various regions of the part and filling pattem are discussed in detail. The results found from the tools give us valuable information about the two methods such as their usefulness, efficiency, required skills, application areas etc. In this study we also tried to focus into the basic theories on which these two tools are based.Item Computational modeling of stimulated emission depletion microscopy in biological cells under one- and two-photon excitation(2014-12) Mark, Andrew Evan; Dunn, Andrew Kenneth, 1970-The finite-difference time-domain method is used to simulate the propagation of focused beams used for stimulated emission depletion (STED) microscopy as they scatter through layers of biological cells. Depletion beams that facilitate axial and lateral confinement of the fluorescence emission are modeled, and the effective point spread function of the system as a function of focal depth is assessed under one- and two-photon excitation. Results show that the lateral depletion beam retains a well-defined minimum up to the maximum simulation depth of 42 µm. In addition, the relative spatial shift between excitation and de-excitation beam foci is less than 44 nm for all simulated depths. PSF calculations suggest that sub-diffraction imaging is possible beyond the maximum simulated depth, as long as the fluorescence emission is detectable. However, strong attenuation of the fluorescence emission by the axial confinement beam may make this beam unsuitable for sub-diffraction imaging in scattering samples.Item Computational modeling of synthetic jets(Texas Tech University, 2004-12) Jeyisanker, KalyaniThis thesis presents a CFD model that employs a novel moving grid methodology to investigate the interaction of an isolated synthetic jet in a crossflow. The current moving grid methodology is said to be 'novel' in the sense of formulation of equations in strong conservative form on a general, nonorthogonal grid system with moving boundaries. In addition, it also conserves space. This moving grid methodology can be easily extended and applied to other problems involving moving boundaries in the system. In the current study, numerical simulation was performed to investigate a timedependent behavior of a simplified configuration, which includes a two-dimensional, single synthetic jet interaction with a turbulent boundary layer. A simple, uniform, nonstaggered Cartesian grid of 270x74 was used. To employ an unsteady boundary condition, a moving diaphragm was introduced to a side wall of the cavity. Unsteady, Reynolds-Averaged, Navier-Stokes equations were solved numerically by a finitevolume method and applied to study the flow. The two-dimensional computational fluid code, HEAD2D was equipped with the standard k-e model. Programs were developed in Fortran. Ensight® was used to visualize the flow patterns. The current study focuses on phase averaged velocity fields, which allows one to study the evolution of the synthetic jet essentially as a function of time. Results on several phase-averaged velocity profiles obtained with this novel moving grid methodology considerably agree with the trend of data obtained from experimental setup by NASA Langley Research Center [13].Item Computer simulation of laser-plasma interaction in a magnetic field.(Texas Tech University, 1975-05) Druce, Robert LeeNot availableItem Conformational dynamics of an unfolded biopolymer : theory and simulation(2012-12) Cheng, Ryan; Makarov, Dmitrii E.; Florin, Ernst-Ludwig; Elber, Ron; Henkelman, Graeme; Keatinge-Clay, Adrian T.The conformational dynamics of an unfolded biopolymer such as a polypeptide or DNA has attracted a significant amount of attention in the context of protein folding and the design of biomimetic technologies. To this end, recent advances in single-molecule experiments have allowed for biomolecules to be probed with an unprecedented level of detail, shedding light on their dynamics. Motivated by the need to interpret experimental data and to help guide future studies, we use concepts from polymer physics, computer simulations, and experimental data to study the timescales in which an unfolded biopolymer undergoes conformational rearrangement. First, we examine the end-to-end loop formation time in the experimentally relevant scenario where the dynamics are probed using a fluorescence probe and quencher. We show that the loop formation time in the experimentally relevant case is quantitatively dissimilar from the predictions of previous theoretical studies that neglect the quenching kinetics, which are often used to interpret experimental data. We additionally find that the loop formation times can be re-casted in a simple, universal dependence that is characteristic of random-coils. Furthermore, deviations from this universal dependence can be used as a sensitive tool for detecting structural order in unfolded biopolymers. We also consider a surface-tethered polymer chain and investigate the rate of a reaction between the free end and the surface. We explore this rate in the reaction-controlled limit and the diffusion-controlled limit, providing evidence for near-universal dependences of the rate in the respective limits. Next, we examine the transit time of end-to-end loop formation in a case study. We find that approximating the end-to-end dynamics as diffusion in a 1D potential of mean force fails dramatically to describe the transit time. Furthermore, we find that the transit time is uninfluenced by the average entropic force imposed by the polymer chain and is well described by a simple free-diffusion model. Finally, we explore the role of internal friction in the dynamics of an unfolded protein. Using simple polymer models that incorporate internal friction as an adjustable free parameter, we mimic typical single-molecule experiments that probe the unfolded state dynamics and make several experimentally verifiable predictions.Item Effect of non-randomness on random variates and discrete event simulation(Texas Tech University, 2004-05) Latchireddi, Seethapathi RaoRandom numbers and random variables are the most important aspect of simulation studies. Non-randomness is unavoidable with the use of digital computers to generate random numbers. In such a scenario it is important to understand how non-randomness would affect simulation modeling. A detailed understanding is expected to minimize inconsistencies of the results of use of pseudo random numbers. In this research the impact of typical non-randomness artificially duplicated into a random number generator on random variates and resulting use in discrete event simulation is discussed. Normal, exponential and triangular distributions are studied to understand the effect of non-randomness observed in RANDU type generator on random variate performance. A detailed analysis based on statistical tests is used for hypothesis testing and the findings are expected to help analyze how faulty random number generators used in early Monte Carlo simulations, dozens of research publications which are cited as reference to this day, along with its possible consequences in current research.Item Evaluation of a microcomputer based simulation designed to teach administration and scoring of the WISC-R(Texas Tech University, 1983-05) Foster, David LeeNot availableItem High-speed performance and power modeling(2010-05) Sunwoo, Dam; Chiou, Derek; Patt, Yale N.; Swartzlander, Earl E.; Pinagli, Keshav; Touba, Nur A.; Holt, James C.The high cost of designing, testing and manufacturing semiconductor chips makes simulation essential to predict performance and power throughout the design cycle of hardware components. However, standard detailed software performance/power simulators are too slow to finish real-life benchmarks within the design cycle. To compensate, reduced accuracy is often traded for improved simulator performance. This dissertation explores the FPGA-Accelerated Simulation Technologies (FAST) methodology that can dramatically improve simulation performance without sacrificing accuracy. Design trade-offs of the functional model partition of a FAST simulator are discussed and QUICK, an implementation of a FAST functional model that is designed to provide fast functional execution as well as the ability to rollback and execute down different paths is described. QUICK is general enough to be useful beyond FPGA-accelerated simulators and provides complex ISA (x86) and full-system support. A complete FAST simulator that combines QUICK with an FPGA-based timing model runs in the millions of x86 instructions per seconds, several orders of magnitude faster than software simulators of comparable accuracy capability, and boots unmodified Windows XP and Linux. Ideally, one could model power at the same speeds as performance modeling in a FAST simulator. However, traditional software-implemented power estimation techniques are very slow. PrEsto, a new power modeling methodology that automatically generates accurate power models that can efficiently fit and operate within FAST simulators, is proposed. Such models can dramatically improve the accuracy and performance of architectural power estimation. Improving high-accuracy simulator performance will open research directions that could not be explored economically in the past. The combination of simulation performance, accuracy, and power estimation capabilities extend the usefulness of such simulators, thus enabling the co-design of architecture, hardware implementation, operating systems, and software.Item Microcomputer simulations of mesoscale precipitation patterns(Texas Tech University, 1985-05) Novia, Robert DA microcomputer simulation of mesoscale precipitation patterns over the Texas South Plains was developed to investigate the variations in a Z-R relationship that are due to the imperfect correspondence between radar and raingage rainfall estimates. Synthetic rain cells were specified in a fashion that depicts the linear structure of squall lines, which account for a large percentage of the total Texas South Plains convective rainfall. The results indicate that gage-radar sampling differences inflict large errors on a Z-R relationship, particularly when gradients of precipitation rate are sharp and the temporal variations in cell strength are great. Raingage measurement variations within a radar bin, variations of radar reflectivity for a succession of bins, and the advection of the precipitation pattern were each found to have the potential to cause Z-R variations of over 30 mm/hr. Attempts to suggest observing system adjustments to diminish such variations were not successful. Evaluated gage-radar sampling differences in the vicinity of strong convection were found to have the potential to be the dominant cause of Z-R relationship variations and responsible for at least part of the difficulty associated with fitting a power law relationship to convective rainfall data.Item Modeling for control of an etch process in semiconductor fabrication(Texas Tech University, 1986-12) Wu, Feng-shangNot availableItem Modeling hybrid domains using process description language(Texas Tech University, 2004-12) Chintabathina, SandeepResearchers in the field of knowledge representation and logic programming are constantly trying to come up with better ways to represent knowledge. One of the recent attempts is to model dynamic domains. A dynamic domain consists of actions that are capable of changing the properties of objects in the domain, for example the blocks world domain. Such domains can be modeled by action theories - collection of statements in so called action languages specifically designed for this purpose. In this thesis we extend this work to allow for continuous processes properties of objects that change continuously with time. For example the height of a freely falling object. In order to do this we adopt an action language/logic programming approach. A new action language called process description language is introduced that will be useful to model systems that exhibit both continuous and discrete behavior (also called hybrid systems). An example of a hybrid domain is the domain consisting of a freely falling object. A freely falling object is in the state of falling, which is a discrete property that can be changed only by actions (also called fluent) while its height is a continuous process. The syntax, semantics, and translation of the statements of the language into rules of a logic program will be discussed. Examples of domains that can represented in this language will be given. In addition, some planning and diagnostic problems will be discussed. Finally, the language will be compared with other languages used for similar purposes.Item Online statistical modeling in reinforcement learning(Texas Tech University, 2004-05) Hooker, Julian AndrewSimulation against a model can greatly improve the learning rate of Reinforcement Learning. The Dyna algorithm uses both real experience and model learning to facilitate simulation. However, the model used in Dyna is fairly limited, yet still has some desirable properties. Examination of a few different known models can help bring to light ways of improving the Dyna model. Combining ideas from what is learned about these models should allow to a greatly improved model for Reinforcement Learning simulation.