UNT Libraries - 102 Matching Results

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Implementation of Scalable Secure Multicasting

Description: A large number of applications like multi-player games, video conferencing, chat groups and network management are presently based on multicast communication. As the group communication model is being deployed for mainstream use, it is critical to provide security mechanisms that facilitate confidentiality, authenticity and integrity in group communications. Providing security in multicast communication requires addressing the problem of scalability in group key distribution. Scalability is a concern in group communication due to group membership dynamics. Joining and leaving of members requires the distribution of a new session key to all the existing members of the group. The two approaches to key management namely centralized and distributed approaches are reviewed. A hybrid solution is then provided, which represents a improved scalable and robust approach for a secure multicast framework. This framework then is implemented in an example application of a multicast news service.
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Date: August 2002
Creator: Vellanki, Ramakrishnaprasad

Developing a Test Bed for Interactive Narrative in Virtual Environments

Description: As Virtual Environments (VE) become a more commonly used method of interaction and presentation, supporting users as they navigate and interact with scenarios presented in VE will be a significant issue. A key step in understanding the needs of users in these situations will be observing them perform representative tasks in a fully developed environment. In this paper, we describe the development of a test bed for interactive narrative in a virtual environment. The test bed was specifically developed to present multiple, simultaneous sequences of events (scenarios or narratives) and to support user navigation through these scenarios. These capabilities will support the development of multiple users testing scenarios, allowing us to study and better understand the needs of users of narrative VEs.
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Date: August 2002
Creator: Mellacheruvu, Krishna

An Adaptive Linearization Method for a Constraint Satisfaction Problem in Semiconductor Device Design Optimization

Description: The device optimization is a very important element in semiconductor technology advancement. Its objective is to find a design point for a semiconductor device so that the optimized design goal meets all specified constraints. As in other engineering fields, a nonlinear optimizer is often used for design optimization. One major drawback of using a nonlinear optimizer is that it can only partially explore the design space and return a local optimal solution. This dissertation provides an adaptive optimization design methodology to allow the designer to explore the design space and obtain a globally optimal solution. One key element of our method is to quickly compute the set of all feasible solutions, also called the acceptability region. We described a polytope-based representation for the acceptability region and an adaptive linearization technique for device performance model approximation. These efficiency enhancements have enabled significant speed-up in estimating acceptability regions and allow acceptability regions to be estimated for a larger class of device design tasks. Our linearization technique also provides an efficient mechanism to guarantee the global accuracy of the computed acceptability region. To visualize the acceptability region, we study the orthogonal projection of high-dimensional convex polytopes and propose an output sensitive algorithm for projecting polytopes into two dimensions.
Date: May 1999
Creator: Chang, Chih-Hui, 1967-

A C Navigational System

Description: The C Navigational System (CNS) is a proposed programming environment for the C programming language. The introduction covers the major influences of programming environments and the components of a programming environment. The system is designed to support the design, coding and maintenance phases of software development. CNS provides multiple views to both the source and documentation for a programming project. User-defined and system-defined links allow the source and documentation to be hierarchically searched. CNS also creates a history list and function interface for each function in a module. The final chapter compares CNS and several other programming environments (Microscope, Rn, Cedar, PECAN, and Marvel).
Date: May 1989
Creator: Hammerquist, James D. (James Daniel)

Computer Graphics Primitives and the Scan-Line Algorithm

Description: This paper presents the scan-line algorithm which has been implemented on the Lisp Machine. The scan-line algorithm resides beneath a library of primitive software routines which draw more fundamental objects: lines, triangles and rectangles. This routine, implemented in microcode, applies the A(BC)*D approach to word boundary alignments in order to create an extremely fast, efficient, and general purpose drawing primitive. The scan-line algorithm improves on previous methodologies by limiting the number of CPU intensive instructions and by minimizing the number of words referenced. This paper will describe how to draw scan-lines and the constraints imposed upon the scan-line algorithm by the Lisp Machine's hardware and software.
Date: December 1988
Creator: Myjak, Michael D. (Michael David)

DRVBLD: a UNIX Device Driver Builder

Description: New peripheral devices are being developed at an ever increasing rate. Before such accessories can be used in the UNIX environment (UNIX is a trademark of Bell Laboratories), they must be able to communicate with the operating system. This involves writing a device driver for each device. In order to do this, very detailed knowledge is required of both the device to be integrated and the version of UNIX to which it will be attached. The process is long, detailed and prone to subtle problems and errors. This paper presents a menu-driven utility designed to simplify and accelerate the design and implementation of UNIX device drivers by freeing developers from many of the implementation specific low-level details.
Date: May 1992
Creator: Cano, Agustin F.

A Neural Network Configuration Compiler Based on the Adaptrode Neuronal Model

Description: A useful compiler has been designed that takes a high level neural network specification and constructs a low level configuration file explicitly specifying all network parameters and connections. The neural network model for which this compiler was designed is the adaptrode neuronal model, and the configuration file created can be used by the Adnet simulation engine to perform network experiments. The specification language is very flexible and provides a general framework from which almost any network wiring configuration may be created. While the compiler was created for the specialized adaptrode model, the wiring specification algorithms could also be used to specify the connections in other types of networks.
Date: December 1992
Creator: McMichael, Lonny D. (Lonny Dean)

The Object-Oriented Database Editor

Description: Because of an interest in object-oriented database systems, designers have created systems to store and manipulate specific sets of abstract data types that belong to the real world environment they represent. Unfortunately, the advantage of these systems is also a disadvantage since no single object-oriented database system can be used for all applications. This paper describes an object-oriented database management system called the Object-oriented Database Editor (ODE) which overcomes this disadvantage by allowing designers to create and execute an object-oriented database that represents any type of environment and then to store it and simulate that environment. As conditions within the environment change, the designer can use ODE to alter that environment without loss of data. ODE provides a flexible environment for the user; it is efficient; and it can run on a personal computer.
Date: December 1989
Creator: Coats, Sidney M. (Sidney Mark)

Linear Unification

Description: Efficient unification is considered within the context of logic programming. Unification is explained in terms of equivalence classes made up of terms, where there is a constraint that no equivalence class may contain more than one function term. It is demonstrated that several well-known "efficient" but nonlinear unification algorithms continually maintain the said constraint as a consequence of their choice of data structure for representing equivalence classes. The linearity of the Paterson-Wegman unification algorithm is shown largely to be a consequence of its use of unbounded lists of pointers for representing equivalences between terms, which allows it to avoid the nonlinearity of "union-find".
Date: December 1989
Creator: Wilbanks, John W. (John Winston)

A Top-Down Structured Programming Technique for Mini-Computers

Description: This paper reviews numerous theoretical results on control structures and demonstrates their practical examples. This study deals with the design of run-time support routines by using top-down structured programming technique. A number of examples are given as illustration of this method. In conclusion, structured programming has proved to be an important methodology for systematic program design and development.
Date: May 1978
Creator: Wu, Chin-yi Robert

FORTRAN Optimizations at the Source Code Level

Description: This paper discusses FORTRAN optimizations that the user can perform manually at the source code level to improve object code performance. It makes use of descriptive examples within the text of the paper for explanatory purposes. The paper defines key areas in writing a FORTRAN program and recommends ways to improve efficiency in these areas.
Date: August 1977
Creator: Barber, Willie D.

Execution Time Analysis through Software Monitors

Description: The analysis of an executing program and the isolation of critical code has been a problem since the first program was written. This thesis examines the process of program analysis through the use of a software monitoring system. Since there is a trend toward structured languages a subset of PL/I was developed t~o exhibit source statement monitoring and costing techniques. By filtering a PL/W program through a preorocessor which determines the cost of source statements and inserts monitoring code, a post-execution analysis of the program can be obtained. This analysis displays an estimated time cost for each source statements the number of times the statement w3s executed, and the product of these values. Additionally, a bar graph is printed in order to quickly locate very active code.
Date: December 1977
Creator: Whistler, Wayne C.

Generating Machine Code for High-Level Programming Languages

Description: The purpose of this research was to investigate the generation of machine code from high-level programming language. The following steps were undertaken: 1) Choose a high-level programming language as the source language and a computer as the target computer. 2) Examine all stages during the compiling of a high-level programming language and all data sets involved in the compilation. 3) Discover the mechanism for generating machine code and the mechanism to generate more efficient machine code from the language. 3) Construct an algorithm for generating machine code for the target computer. The results suggest that compiler is best implemented in a high-level programming language, and that SCANNER and PARSER should be independent of target representations, if possible.
Date: December 1976
Creator: Chao, Chia-Huei

A Computer Algorithm for Synthetic Seismograms

Description: Synthetic seismograms are a computer-generated aid in the search for hydrocarbons. Heretofore the solution has been done by z-transforms. This thesis presents a solution based on the method of finite differences. The resulting algorithm is fast and compact. The method is applied to three variations of the problem, all three are reduced to the same approximating equation, which is shown to be optimal, in that grid refinement does not change it. Two types of algorithms are derived from the equation. The number of obvious multiplications, additions and subtractions of each is analyzed. Critical section of each requires one multiplication, two additions and two subtractions. Four sample synthetic seismograms are shown. Implementation of the new algorithm runs twice as fast as previous computer program.
Date: August 1977
Creator: Isaacson, James

An Interpreter for the Basic Programming Language

Description: In this thesis, the first chapter provides the general description of this interpreter. The second chapter contains a formal definition of the syntax of BASIC along with an introduction to the semantics. The third chapter contains the design of data structure. The fourth chapter contains the description of algorithms along with stages for testing the interpreter and the design of debug output. The stages and actions-are represented internally to the computer in tabular forms. For statement parsing working syntax equations are established. They serve as standards for the conversion of source statements into object pseudocodes. As the statement is parsed for legal form, pseudocodes for this statement are created. For pseudocode execution, pseudocodes are represented internally to the computer in tabular forms.
Date: May 1975
Creator: Chang, Min-Jye S.

Information Storage and Retrieval Systems

Description: This thesis describes the implementation of a general purpose personal information storage and retrieval system. Chapter one contains an introduction to information storage and retrieval. Chapter two contains a description of the features a useful personal information retrieval system should contain. This description forms the basis for the implementation of the personal information storage and retrieval system described in chapter three. The system is implemented in UCSD Pascal on an Apple II microcomputer.
Date: May 1983
Creator: Creech, Teresa Adams

A Design Approach for Digital Computer Peripheral Controllers, Case Study Design and Construction

Description: The purpose of this project was to describe a novel design approach for a digital computer peripheral controller, then design and construct a case study controller. This document consists of three chapters and an appendix. Chapter II presents the design approach chosen; a variation to a design presented by Charles R. Richards in an article published in Electronics magazine. Richards' approach consists of a finite state machine circuitry controlling all the functions of a controller. The variation to Richards' approach consists of considering the various logically independent processes which a controller carries out and assigning control of each process to a separate finite state machine. The appendix contains the documentation of the design and construction of the controller.
Date: May 1976
Creator: Cabrera, A. L.

SEM Predicting Success of Student Global Software Development Teams

Description: The extensive use of global teams to develop software has prompted researchers to investigate various factors that can enhance a team’s performance. While a significant body of research exists on global software teams, previous research has not fully explored the interrelationships and collective impact of various factors on team performance. This study explored a model that added the characteristics of a team’s culture, ability, communication frequencies, response rates, and linguistic categories to a central framework of team performance. Data was collected from two student software development projects that occurred between teams located in the United States, Panama, and Turkey. The data was obtained through online surveys and recorded postings of team activities that occurred throughout the global software development projects. Partial least squares path modeling (PLS-PM) was chosen as the analytic technique to test the model and identify the most influential factors. Individual factors associated with response rates and linguistic characteristics proved to significantly affect a team’s activity related to grade on the project, group cohesion, and the number of messages received and sent. Moreover, an examination of possible latent homogeneous segments in the model supported the existence of differences among groups based on leadership style. Teams with assigned leaders tended to have stronger relationships between linguistic characteristics and team performance factors, while teams with emergent leaders had stronger. Relationships between response rates and team performance factors. The contributions in this dissertation are three fold. 1) Novel analysis techniques using PLS-PM and clustering, 2) Use of new, quantifiable variables in analyzing team activity, 3) Identification of plausible causal indicators for team performance and analysis of the same.
Date: May 2015
Creator: Brooks, Ian Robert

Arithmetic Computations and Memory Management Using a Binary Tree Encoding af Natural Numbers

Description: Two applications of a binary tree data type based on a simple pairing function (a bijection between natural numbers and pairs of natural numbers) are explored. First, the tree is used to encode natural numbers, and algorithms that perform basic arithmetic computations are presented along with formal proofs of their correctness. Second, using this "canonical" representation as a base type, algorithms for encoding and decoding additional isomorphic data types of other mathematical constructs (sets, sequences, etc.) are also developed. An experimental application to a memory management system is constructed and explored using these isomorphic types. A practical analysis of this system's runtime complexity and space savings are provided, along with a proof of concept framework for both applications of the binary tree type, in the Java programming language.
Date: December 2011
Creator: Haraburda, David

Dynamic Resource Management in RSVP- Controlled Unicast Networks

Description: Resources are said to be fragmented in the network when they are available in non-contiguous blocks, and calls are dropped as they may not end sufficient resources. Hence, available resources may remain unutilized. In this thesis, the effect of resource fragmentation (RF) on RSVP-controlled networks was studied and new algorithms were proposed to reduce the effect of RF. In order to minimize the effect of RF, resources in the network are dynamically redistributed on different paths to make them available in contiguous blocks. Extra protocol messages are introduced to facilitate resource redistribution in the network. The Dynamic Resource Redistribution (DRR) algorithm when used in conjunction with RSVP, not only increased the number of calls accommodated into the network but also increased the overall resource utilization of the network. Issues such as how many resources need to be redistributed and of which call(s), and how these choices affect the redistribution process were investigated. Further, various simulation experiments were conducted to study the performance of the DRR algorithm on different network topologies with varying traffic characteristics.
Date: December 2001
Creator: Iyengar Prasanna, Venkatesan

Temporally Correct Algorithms for Transaction Concurrency Control in Distributed Databases

Description: Many activities are comprised of temporally dependent events that must be executed in a specific chronological order. Supportive software applications must preserve these temporal dependencies. Whenever the processing of this type of an application includes transactions submitted to a database that is shared with other such applications, the transaction concurrency control mechanisms within the database must also preserve the temporal dependencies. A basis for preserving temporal dependencies is established by using (within the applications and databases) real-time timestamps to identify and order events and transactions. The use of optimistic approaches to transaction concurrency control can be undesirable in such situations, as they allow incorrect results for database read operations. Although the incorrectness is detected prior to transaction committal and the corresponding transaction(s) restarted, the impact on the application or entity that submitted the transaction can be too costly. Three transaction concurrency control algorithms are proposed in this dissertation. These algorithms are based on timestamp ordering, and are designed to preserve temporal dependencies existing among data-dependent transactions. The algorithms produce execution schedules that are equivalent to temporally ordered serial schedules, where the temporal order is established by the transactions' start times. The algorithms provide this equivalence while supporting currency to the extent out-of-order commits and reads. With respect to the stated concern with optimistic approaches, two of the proposed algorithms are risk-free and return to read operations only committed data-item values. Risk with the third algorithm is greatly reduced by its conservative bias. All three algorithms avoid deadlock while providing risk-free or reduced-risk operation. The performance of the algorithms is determined analytically and with experimentation. Experiments are performed using functional database management system models that implement the proposed algorithms and the well-known Conservative Multiversion Timestamp Ordering algorithm.
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Date: May 2001
Creator: Tuck, Terry W.

Practical Cursive Script Recognition

Description: This research focused on the off-line cursive script recognition application. The problem is very large and difficult and there is much room for improvement in every aspect of the problem. Many different aspects of this problem were explored in pursuit of solutions to create a more practical and usable off-line cursive script recognizer than is currently available.
Date: August 1995
Creator: Carroll, Johnny Glen, 1953-

Convexity-Preserving Scattered Data Interpolation

Description: Surface fitting methods play an important role in many scientific fields as well as in computer aided geometric design. The problem treated here is that of constructing a smooth surface that interpolates data values associated with scattered nodes in the plane. The data is said to be convex if there exists a convex interpolant. The problem of convexity-preserving interpolation is to determine if the data is convex, and construct a convex interpolant if it exists.
Date: December 1995
Creator: Leung, Nim Keung