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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
521

Performance Evaluation Tools for Interconnection Network Design

Kolinska, Anna 08 April 1994 (has links)
A methodology is proposed for designing performance optimized computer systems. The methodology uses software tools created for performance monitoring and evaluation of parallel programs, replacing actual hardware with a simulator modeling the hardware under development. We claim that a software environment can help hardware designers to make decisions on the architectural design level. A simulator executes real programs and provides access to performance monitors from user's code. The performance monitoring system collects data traces when running the simulator and the performance analysis module extracts performance data of interest, that are later displayed with visualization tools. Key features of our methodology are "plug and play" simulation and modeling hardware/software interaction during the process of hardware design. The ability to use different simulators gives the user flexibility to configure the system for the required functionality, accuracy and simulation performance. Evaluation of hardware performance based on results obtained by modeling hardware/software interaction is crucial for designing performance optimized computer systems. We have developed a software system, based on our design methodology, for performance evaluation of multicomputer interconnection networks. The system, called the Parsim Common Environment (PCE), consists of an instrumented network simulator that executes assembly language instructions, and performance analysis and visualization modules. Using PCE we have investigated a specific network design example. The system helped us spot performance problems, explain why they happened and find the ways to solve them. The obtained results agreed with observations presented in the literature, hence validating our design methodology and the correctness of the software performance evaluation system for hardware designs. Using software tools a designer can easily check different design options and evaluate the obtained performance results without the overhead of building expensive prototypes. With our system, data analysis that required 10 man-hours to complete manually took just a couple of seconds on a Sparc-4 workstation. Without experimentation with the simulator and the performance evaluation environment one might build an expensive hardware prototype, expecting improved performance, and then be disappointed with poorer results than expected. Our tools help designers spot and solve performance problems at early stages of the hardware design process.
522

Multi-Scale Models to Simulate Interactions between Liquid and Thin Structures

Fei, Yun January 2019 (has links)
In this dissertation, we introduce a framework for simulating the dynamics between liquid and thin structures, including the effects of buoyancy, drag, capillary cohesion, dripping, and diffusion. After introducing related works, Part I begins with a discussion on the interactions between Newtonian fluid and fabrics. In this discussion, we treat both the fluid and the fabrics as continuum media; thus, the physical model is built from mixture theory. In Part II, we discuss the interactions between Newtonian fluid and hairs. To have more detailed dynamics, we no longer treat the hairs as continuum media. Instead, we treat them as discrete Kirchhoff rods. To deal with the thin layer of liquid that clings to the hairs, we augment each hair strand with a height field representation, through which we introduce a new reduced-dimensional flow model to solve the motion of liquid along the longitudinal direction of each hair. In addition, we develop a faithful model for the hairs' cohesion induced by surface tension, where a penalty force is applied to simulate the collision and cohesion between hairs. To enable the discrete strands interact with continuum-based, shear-dependent liquid, in Part III, we develop models that account for the volume change of the liquid as it passes through strands and the momentum exchange between the strands and the liquid. Accordingly, we extend the reduced-dimensional flow model to simulate liquid with elastoviscoplastic behavior. Furthermore, we use a constraint-based model to replace the penalty-force model to handle contact, which enables an accurate simulation of the frictional and adhesive effects between wet strands. We also present a principled method to preserve the total momentum of a strand and its surface flow, as well as an analytic plastic flow approach for Herschel-Bulkley fluid that enables stable semi-implicit integration at larger time steps. We demonstrate a wide range of effects, including the challenging animation scenarios involving splashing, wringing, and colliding of wet clothes, as well as flipping of hair, animals shaking, spinning roller brushes from car washes being dunked in water, and intricate hair coalescence effects. For complex liquids, we explore a series of challenging scenarios, including strands interacting with oil paint, mud, cream, melted chocolate, and pasta sauce.
523

Simulation model of a hospital biochemistry laboratory

Wall, Jan Peter. January 1974 (has links)
This thesis has 3 vols. The original Vol. 1 is included here. Vols 2&3 were never digitized but are available for consultation.
524

Thermal profiles in oxygen vacuum swing adsorption (VSA) : modelling, observations and optimisation

Wilson, Simon J. January 2001 (has links)
Abstract not available
525

Thermal profiles in oxygen vacuum swing adsorption (VSA)modelling, observations and optimisation

Wilson, Simon J January 2001 (has links)
Abstract not available
526

Estimating the inevitability of fast oscillations in model systems with two timescales

Choy, Vivian K.Y, 1971- January 2001 (has links)
Abstract not available
527

Efficient simulation of space-time coded and turbo coded systems

Nguyen, Kim Chi, University of Western Sydney, College of Health and Science, School of Engineering January 2007 (has links)
The two main goals of this research are to study the implementation aspects of space-time turbo trellis codes (ST Turbo TC) and to develop efficient simulation methods for space-time and turbo coded systems using the importance sampling (IS) technique. The design of ST Turbo TC for improving the bandwidth efficiency and the reliability of wireless communication networks, which is based on the turbo structure, has been proposed in the literature. To achieve memory savings and reduce the decoding delay, this thesis proposes a simplified ST Turbo TC decoder using a sliding window (SW) technique. Different window sizes are employed and investigated. Through computer simulation, the optimum window sizes are determined for various system configurations. The effect of finite word length representation on the performance of ST Turbo TC is then studied. Simulation results show that ST Turbo TC is feasible for finite word length representation without significant degradation in the frame error rate performance. The optimum word length configurations are defined for all quantities external and internal to the ST Turbo TC decoder. For complex communication systems such as space-time codes and turbo codes, computer simulation is in fact the useful approach to obtain the estimated performance. To overcome the lengthy run-time requirements of the conventional Monte-Carlo (MC) method, this thesis introduces importance sampling simulation methods that accurately estimate the performances of turbo codes and space-time codes including orthogonal space-time block codes (OSTBC) and concatenated OSTBC. It is demonstrated that the proposed methods require much smaller sample sizes to achieve the same accuracy required by a conventional MC estimator. / Doctor of Philosophy (PhD)
528

Towards development of a quality cost model for automotive stamping.

de Ruyter, Adam, mikewood@deakin.edu.au January 2002 (has links)
The current work used discrete event simulation techniques to model the economics of quality within an actual automotive stamping plant. Automotive stamping is a complex, capital intensive process requiring part-specific tooling and specialised machinery. Quality control and quality improvement is difficult in the stamping environment due to the general lack of process understanding and the large number to interacting variables. These factors have prevented the widespread use of statistical process control. In this work, a model of the quality control techniques used at the Ford Geelong Stamping plant is developed and indirectly validated against results from production. To date, most discrete event models are of systems where the quality control process is clearly defined by the rules of statistical process control. However, the quality control technique used within the stamping plant is for the operator to perform a 100% visual inspection while unloading the finished panels. In the developed model, control is enacted after a cumulative count of defective items is observed, thereby approximating the operator who allows a number of defective panels to accumulate before resetting the line. Analysis of this model found that the cost sensitivity to inspection error is dependent upon the level of control and that the level of control determines line utilisation. Additional analysis of this model demonstrated that additional inspection processes would lead to more stable cost structures but these structures many not necessarily be lower cost. The model was subsequently applied to investigate the economics of quality improvement. The quality problem of panel blemishes, induced by slivers (small metal fragments), was chosen as a case stuffy. Errors of 20-30% were observed during direct validation of the cost model and it was concluded that the use of discrete event simulation models for applications requiring high accuracy would not be possible unless the production system was of low complexity. However, the model could be used to evaluate the sensitivity of input factors and investigating the effects of a number of potential improvement opportunities. Therefore, the research concluded that it is possible to use discrete event simulation to determine the quality economics of an actual stamping plant. However, limitations imposed by inability of the model to consider a number of external factors, such as continuous improvement, operator working conditions or wear and the lack of reliable quality data, result in low cost accuracy. Despite this, it still can be demonstrated that discrete event simulation has significant benefits over the alternate modelling methods.
529

Stochastic processing for enhancement of artificial insect vision / by Gregory P. Harmer.

Harmer, Gregory Peter January 2001 (has links)
"November, 2001" / Includes bibliographical references (leaves 229-246) / xxiv, 254 leaves : ill. (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 2002
530

Steady-state analysis techniques for coupled device and circuit simulation

Hu, Yutao 28 May 2004 (has links)
The focus of this work is on the steady-state analysis of RE circuits using a coupled device and circuit simulator. Efficient coupling algorithms for both the time-domain shooting method and the frequency-domain harmonic balance method have been developed. A modified Newton shooting method considerably improves the efficiency and reliability of the time-domain analysis. Three different implementation approaches of the harmonic balance method for coupled device and circuit simulation are investigated and implemented. These include the quasi-static, non-quasi-static, and modified-Volterra-series approaches. Comparisons of simulation and performance results identify the strengths and weakness of these approaches in terms of accuracy and efficiency. / Graduation date: 2005

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