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A Numerical Study Of High-Speed Missile Configurations Using A Block- Structured Parallel Algorithm, Douglas C. Blake
A Numerical Study Of High-Speed Missile Configurations Using A Block- Structured Parallel Algorithm, Douglas C. Blake
Theses and Dissertations
A numerical analysis of the aerodynamic phenomena associated with the high-speed flight of a sharp-nosed, four-finned, high-fineness ratio missile using a block-structured, parallel computer algorithm is presented. The algorithm, PANS-3EM, utilizes a second-order-accurate, shock-capturing, Total Variation Diminishing scheme and incorporates a Baldwin-Lomax turbulence model. PANS-3EM allows for extreme flexibility in the choice of computational domain decomposition and computing machine of implementation. Developmental work consists of conceptualization and verification of the algorithm as well as parallel performance and scalability studies conducted on a variety of computing platforms. Using PANS-3EM, the aerodynamic characteristics of the missile are investigated. Drag and pitching moment …
On Image Segmentation Using Neural Networks And Fuzzy Sets., Ashish Ghosh Dr.
On Image Segmentation Using Neural Networks And Fuzzy Sets., Ashish Ghosh Dr.
Doctoral Theses
During the last five decades or even more a large number of researchers are trying to design intelligent systems to perform tasks at which human beings are more efficient at present. One of the most important behavioral tasks in which human beings show their expertise is image analysis or recognition; where a large amount of pictorial data is processed in a very small amount of time (called real time). Widespread attempts have been made to develop intelligent systems (under different names, like pattern recognition system, image under- standing system, computer vision system etc.) for pictorial pattern analysis and recognition. The …
Unified Bias Analysis Of Subspace-Based Doa Estimation Algorithms, Yang Lu
Unified Bias Analysis Of Subspace-Based Doa Estimation Algorithms, Yang Lu
Dissertations and Theses
This thesis presents the unified bias analysis of subspace-based DOA estimation algorithms in terms of physical parameters such as source separation, signal coherence, number of senors and snapshots. The analysis reveals the direct relationship between the performance of the DOA algorithms and signal measurement conditions. Insights into different algorithms are provided. Based upon previous first-order subspace perturbations, second-order subspace perturbations are developed which provide basis for bias analysis and unification. Simulations verifying the theoretical bias analysis are presented.
A New Approach To The Optimal Filtering Of Differential Phase Measurements Of Gps Signal In The Precision Survey, Shengan Wang
A New Approach To The Optimal Filtering Of Differential Phase Measurements Of Gps Signal In The Precision Survey, Shengan Wang
Dissertations and Theses
The Global Positioning System (GPS) has become popular research and application interests in surveying and many other areas. Nowadays, the accuracy of the Differential GPS can easily reach the order of a few meters. Yet, there are still many ways to exploit the GPS system signal carrier to improve the accuracy to less than meter level. In this thesis, a new approach to improve the accuracy to less than meter level is presented while the observer is in the dynamic situation. In order to reach the sub-meter accuracy, we measure on the carrier phase difference (The L1 carrier frequency is …
Designing And Simulating A Multistage Sampling Rate Conversion System Using A Set Of Pc Programs, David Joseph Hagerty
Designing And Simulating A Multistage Sampling Rate Conversion System Using A Set Of Pc Programs, David Joseph Hagerty
Dissertations and Theses
The thesis covers a series of PC programs that we have written that will enable users to easily design FIR linear phase lowpass digital filters and multistage sampling rate conversion systems. The first program is a rewrite of the McClellan-Parks computer program with some slight modifications. The second program uses an algorithm proposed by Rabiner that determines the length of a lowpass digital filter. Rabiner used a formula proposed by Herrmann et al. to initially estimate the filter length in his algorithm. The formula, however, assumes unity gain. We present a modification to the formula so that the gain of …
Performance Evaluation Of Distributed Mutual Exclusion Algorithms, Kenneth B Been
Performance Evaluation Of Distributed Mutual Exclusion Algorithms, Kenneth B Been
UNLV Retrospective Theses & Dissertations
In any system in which concurrent processes share resources, mutual exclusion refers to the problem of guaranteeing the integrity of those resources by restricting their use to one process at a time. Due the complex nature of distributed systems, distributed mutual exclusion algorithms are often not amenable to theoretical analysis for performance or even correctness. Experimental inquiries are therefore warranted. This thesis investigates seven well known distributed mutual exclusion algorithms in detail, and uses computer simulation to evaluate the performance and applicability of these various algorithms. Toward this end, a realistic and general model for evaluating distributed algorithms is proposed. …
Self-Stabilizing Deadlock Algorithms In Distributed Systems, Mitchell Elliott Flatebo
Self-Stabilizing Deadlock Algorithms In Distributed Systems, Mitchell Elliott Flatebo
UNLV Retrospective Theses & Dissertations
A self-stabilizing system is a network of processors, which, when started from an arbitrary (and possibly illegal) initial state, always returns to a legal state in a finite number of steps. Self-stabilization is an evolving paradigm in fault-tolerant computing. This research will be the first time self-stabilization is used in the areas of deadlock detection and prevention. Traditional deadlock detection algorithms have a process initiate a probe. If that probe travels around the system and is received by the initiator, there is a cycle in the system, and deadlock is detected. In order to prevent deadlocks, algorithms usually rank nodes …
Formal Verification Of Distributed Deadlock Detection Algorithms, Brian Matt Johnston
Formal Verification Of Distributed Deadlock Detection Algorithms, Brian Matt Johnston
UNLV Retrospective Theses & Dissertations
The problem of distributed deadlock detection has undergone extensive study. Formal verification of deadlock detection algorithms in distributed systems is an area of research that has largely been ignored. Instead, most proposed distributed deadlock detection algorithms have used informal or intuitive arguments, simulation or just neglect the entire aspect of verification of correctness; As a consequence, many of these algorithms have been shown incorrect. This research will abstract the notion of deadlock in terms of a temporal logic of actions and discuss the invariant and eventuality properties. The contributions of this research are the development of a distributed deadlock detection …
Practical Algorithms For Image Compression And Surface Estimation, Matthew Y Au
Practical Algorithms For Image Compression And Surface Estimation, Matthew Y Au
UNLV Retrospective Theses & Dissertations
Practical Algorithms for Image Compression and Surface Estimation describes three algorithms for image compression and one algorithm for surface estimation that incorporates kriging and parametric cubic splines. Two of the image compression algorithms are innovative extensions of the Run Length Encoding image compression algorithm and the third is an image compression technique based on kriging. In general the modified Run Length Encoding algorithms yield a better compression ratio by a factor of two while retaining fast decompression of the image. The algorithm based on kriging achieves a compression ratio up to 250:1 and is unique in that the compressed image …
The Use Of Synthesized Images To Evaluate The Performance Of Ocr Devices And Algorithms, Frank Robert Jenkins
The Use Of Synthesized Images To Evaluate The Performance Of Ocr Devices And Algorithms, Frank Robert Jenkins
UNLV Retrospective Theses & Dissertations
This thesis will attempt to establish if synthesized images can be used to predict the performance of Optical Character Recognition (OCR) algorithms and devices. The value of this research lies in reducing the considerable costs associated with preparing test images for OCR research. The paper reports on a series of experiments in which synthesized images of text files in nine different fonts and sizes are input to eight commercial OCR devices. The method used to create the images is explained and a detailed analysis of the character and word confusion between the output and the true text files is presented. …
Algorithms For Automatic Parallelism, Optimization, And Optimal Processor Utilization, Katharine J Macke
Algorithms For Automatic Parallelism, Optimization, And Optimal Processor Utilization, Katharine J Macke
UNLV Retrospective Theses & Dissertations
In this thesis we first investigate the reaching definitions optimization. This compiler optimization collects and stores information about where a variable is defined and how long that definition of the variable stays alive before it is redefined. We compare the old iterative solution to a new algorithm that uses the partialout concept. The partialout solution decreases execution time by eliminating the multiple passes required in the iterative solution. Currently, compilers that find a data dependence between two statements in a loop do not parallelize the loop. Next we investigate automatic parallelism for these loops by breaking the loop into a …
Distributed Mutual Exclusion Algorithms, Paul Banta
Distributed Mutual Exclusion Algorithms, Paul Banta
UNLV Retrospective Theses & Dissertations
In this thesis we present three original algorithms which solve the distributed mutual exclusion problem. Two of the three solve the problem of allowing only one site at a time into the critical section. The third solves the more difficult problem of allowing a specific number of sites (k sites) into the critical section at a time; All three algorithms are "Token Based". That is, they make use of a token and token queue in order to guarantee mutual exclusion. Only the site that currently has the token is allowed to enter its critical section in the 1 mutual exclusion …
Ramsey Numbers Involving A Triangle: Theory And Algorithms, Xia Jin
Ramsey Numbers Involving A Triangle: Theory And Algorithms, Xia Jin
Theses
Ramsey theory studies the existence of highly regular patterns in large sets of objects. Given two graphs G and H, the Ramsey number R(G, H) is defined to be the smallest integer n such that any graph F with n or more vertices must contain G, or F must contain H. Albeit beautiful, the problem of determining Ramsey numbers is considered to be very difficult. We focus our attention on efficient algorithms for determining Ram sey numbers involving a triangle: R(K3 , G). With the help of theoretical tools, the search space is reduced by using different pruning techniques and …