Digital Commons Network^™

On Perfect Weighted Coverings With Small Radius, G. D. Cohen, S. N. Litsyn, H. F. Mattson Jr

Electrical Engineering and Computer Science - Technical Reports

We extend the results of our previous paper [8] to the nonlinear case: The Lloyd polynomial of the covering has at least R distinct roots among 1, ... , n, where R is the covering radius. We investigate PWC with diameter 1, finding a partial characterization. We complete an investigation begun in [8] on linear PMC with distance 1 and diameter 2.

A Comparison Of Load Balancing Algorithms For Parallel Computations, N. Mansouri, Geoffrey C. Fox

Electrical Engineering and Computer Science - Technical Reports

Three physical optimization methods are considered in this paper for load balancing parallel computations. These are simulated annealing, genetic algorithms, and neural networks. Some design choices and the inclusion of additional steps lead to new versions of the algorithms with different solution qualities and execution times. The performances of these versions are critically evaluated and compared for test cases with different topologies and sizes. Orthogonal recursive coordinate bisection is also included in the comparison as a typical simple deterministic method. Simulation results show that the algorithms have diverse properties. Hence, different algorithms can be applied to different problems and requirements. …

Parallel Genetic Algorithms With Application To Load Balancing For Parallel Computing, N. Mansouri, Geoffrey C. Fox

Electrical Engineering and Computer Science - Technical Reports

A new coarse grain parallel genetic algorithm (PGA) and a new implementation of a data-parallel GA are presented in this paper. They are based on models of natural evolution in which the population is formed of discontinuous or continuous subpopulations. In addition to simulating natural evolution, the intrinsic parallelism in the two PGA's minimizes the possibility of premature convergence that the implementation of classic GA's often encounters. Intrinsic parallelism also allows the evolution of fit genotypes in a smaller number of generations in the PGA's than in sequential GA's, leading to superlinear speed-ups. The PGA's have been implemented on a …

A Self-Organizing Binary Decision Tree For Incrementally Defined Rule-Based Systems, Douglas M. Campbell, Tony R. Martinez

Faculty Publications

This paper presents an adaptive self-organizing concurrent system (ASOCS) model for massively parallel processing of incrementally defined rule systems in such areas as adaptive logic, robotics, logical inference, and dynamic control. An ASOCS is an adaptive network composed of many simple computing elements operating asynchronously and in parallel. This paper focuses on adaptive algorithm 3 (AA3) and details its architecture and learning algorithm. It has advantages over previous ASOCS models in simplicity, implementability, and cost. An ASOCS can operate in either a data processing mode or a learning mode. During the data processing mode, an ASOCS acts as a parallel …

Visual Knowledge Query Language As A Front-End To Relational Systems, Keng Siau, Kok Phuang Tan, Hock Chuan Chan

Research Collection School Of Computing and Information Systems

Relational query languages like SQL and QUEL require the users to understand the complex database structure. This is a burden on end users, especially novice end users who access the database on a casual and infrequent basis. To alleviate the need to know the logical database organization, this paper proposes the use of a semantic data model, known as the Enhanced Entity-Relationship (EER) model, as a front-end to the relational systems. A formal, high-level Visual Knowledge Query Language (VKQL) has also been designed for this interface. This language provides for knowledge abstraction as the user communicates only domain knowledge with …

Reuse And Productivity In Integrated Computer-Aided Software Engineering: An Empirical Study, Rajiv D. Banker, Robert J. Kauffman

Research Collection School Of Computing and Information Systems

Growing competition in the investment banking industry has given rise to increasing demand for high functionality software applications that can be developed in a short period of time. Yet delivering such applications creates a bottleneck in software development activities. This dilemma can be addressed when firms shift to development methods that emphasize software reusability. This article examines the productivity implications of object and repository-based integrated computer-aided software engineering (ICASE) software development in the context of a major investment bank's information systems strategy. The strategy emphasizes software reusability. Our empirical results, based on data from 20 projects that delivered software for …

A Topological Model For Parallel Algorithm Design, Jeffrey A. Simmers

Theses and Dissertations

This research demonstrates that formal, mathematical analysis in theoretical computer science can be recast in terms of the topology of complete metric spaces, and also presents a methodical technique for developing formal specifications. This effort shows that the topology of complete metric spaces provides a tool that can be used to both recreate major results about computational models and also to develop new results about these models. Using the two computational models CSP and UNITY, this effort shows that the required mathematics needed to support this alternative to the traditional analysis of computational models can be readily supported by a …

Heuristics For Hospital Inventory Management, Thomas G. Hibson

Theses and Dissertations

This study investigated the reasoning strategies used by hospital logistics management experts and was conducted at the Wright-Patterson AFB (WPAFB) Medical Center. An expert system was developed to verify the captured strategies. The particular area of interest of this study was the reasoning strategies involved in the reconciliation of the Monthly Stock Status Report within the Medical Logistics Branch. A literature review revealed there were few guidelines as to when and what action to pursue when reconciling the Monthly Stock Status Report. Though there were no references in the literature on expert systems that dealt with this particular report, there …

Visual Knowledge Query Language As A Front-End To Relational Systems, Keng Siau, Kok Phuang Tan, Hock Chuan Chan

Research Collection School Of Computing and Information Systems

Relational query languages like SQL and QUEL require the users to understand the complex database structure. This is a burden on end users, especially novice end users who access the database on a casual and infrequent basis. To alleviate the need to know the logical database organization, this paper proposes the use of a semantic data model, known as the Enhanced Entity-Relationship (EER) model, as a front-end to the relational systems. A formal, high-level Visual Knowledge Query Language (VKQL) has also been designed for this interface. This language provides for knowledge abstraction as the user communicates only domain knowledge with …

Formal Methods Of Real-Time Systems, Su-Mei Tsai, Bruce M. Mcmillin

Computer Science Technical Reports

Formal aid in specification and verification techniques have become an accepted approach to achieving reliable software for life-critical real-time systems, in which testing may be impossible or too dangerous, since the real inputs to the systems come from the real world. Modelling, assertion languages, and proof systems are three major components that are employed to accomplish the confidence of safe real-time environments. This paper examines these currently available techniques that are used for safety analysis of real-time systems.

Application-Oriented Fault-Tolerant Parallel Branch & Bound, Aggie Sun, Bruce M. Mcmillin

Computer Science Technical Reports

An important aspect which is often overlooked in the software design cycle is the question of reliability. Many methodologies in the past have attempted to provide reliability efficiently but have never been successful at eliminating explicit time and space redundancy. The approach taken here is based on the Application-Oriented Fault Tolerance Paradigm which provides reliability by examining the behavior and properties of the application. This paper will demonstrate how fault detecting constraints are developed and incorporated using the Application-Oriented Fault Tolerance paradigm for the class of Branch and Bound algorithms. Branch and bound algorithms are a type of combinatorial search …

An Improved Algorithm For Neural Network Classification Of Imbalanced Training Sets, Rangachari Anand, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka

Electrical Engineering and Computer Science - Technical Reports

In this paper, we analyze the reason for the slow rate of convergence of net output error when using the backpropagation algorithm to train neural networks for a two-class problems in which the numbers of exemplars for the two classes differ greatly. This occurs because the negative gradient vector computed by backpropagation for an imbalanced training set does not point initially in a downhill direction for the class with the smaller number of exemplars. Consequently, in the initial iteration, the net error for the exemplars in this class increases significantly. The subsequent rate of convergence of the net error is …

Semi-Distributed Load Balancing For Massively Parallel Multicomputer Systems, Ishfaq Ahmad, Arif Ghafoor

Electrical Engineering and Computer Science - Technical Reports

This paper presents a semi-distributed approach, for load balancing in large parallel and distributed systems, which is different from the conventional centralized and fully distributed approaches. The proposed strategy uses a two-level hierarchical control by partitioning the interconnection structure of a distributed or multiprocessor system into independent symmetric regions (spheres) centered at some control points. The central points, called schedulers, optimally schedule tasks within their spheres and maintain state information with low overhead. We consider interconnection structures belonging to a number of families of distance transitive graphs for evaluation, and using their algebraic characteristics, show that identification of spheres and …

Explicit Clock Temporal Logic In Timing Constraints For Real-Time Systems, S. Ramanna, J. F. Peters Iii

Electrical Engineering and Computer Science - Technical Reports

A form of explicit clock temporal logic (called TLrt) useful in specifying timing constraints on controller actions, a real-time database (rtdb) items, and constraints in a real-time constraint base (rtcb), is presented. Timing as well as other forms of constraints are stored in the rtcb. A knowledge-based approach to ensure the integrity of information in an rtdb is given. The rtcb is realized as a logic program called Constrainer, which is a historyless integrity checker for a real-time database. The consistency and integrity issues for an rtcb and rtdb are investigated. The formal bases for a temporally complete rtdb and …

Multi Cast Routing In Unreliable Networks, Martina Schollmeyer, Bruce M. Mcmillin

Computer Science Technical Reports

The efficient routing of messages in a multicomputer interconnection network is the key to the performance of such a network. Multicast communication refers to the delivery of a message from a source node to several destination nodes. Although multicast is highly desirable for many applications, it is not directly supported in most multicomputer architectures. This paper examines existing algorithms for multicast routing in multicomputer networks and groups them into a number of categories such as multicast trees, multicast paths, multicast stars, etc. These algorithms are evaluated in terms of deadlock handling, adaptability and suitability for wormhole routing. Wormhole routing is …

Formal Generation Of Executable Assertions For A Fault-Tolerant Parallel Bitonic Sort, Hanan Lutfiyya, Bruce M. Mcmillin

Computer Science Technical Reports

No abstract provided.

Representation Requirements For Supporting Decision-Model Formulation, Tze-Yun Leong

Research Collection School Of Computing and Information Systems

This paper outlines a methodology for analyzing the representational support for knowledge-based decision-modeling in a broad domain. A relevant set of inference patterns and knowledge types are identified. By comparing the analysis results to existing representations, some insights are gained into a design approach for integrating categorical and uncertain knowledge in a context sensitive manner.

The Complexity Of Local Stratification, Peter Cholak, Howard A. Blair

Electrical Engineering and Computer Science - Technical Reports

The class of locally stratified logic programs is shown to be Π11-complete by the construction of a reducibility of the class of infinitely branching nondeterministic finite register machines.nondeterministic finite register machines.

Fault-Tolerant Load Management For Real-Time Distributed Computer Systems, Arif Ghafoor, Ishfaq Ahmad

Electrical Engineering and Computer Science - Technical Reports

This paper presents a fault-tolerant scheme applicable to any decentralized load balancing algorithms used in soft real-time distributed systems. Using the theory of distance-transitive graphs for representing topologies of these systems, the proposed strategy partitions these systems into independent symmetric regions (spheres) centered at some control points. These central points, called fault-control points, provide a two-level task redundancy and efficiently re-distribute the load of failed nodes within their spheres. Using the algebraic characteristics of these topologies, it is shown that the identification of spheres and fault-control points is, in general, is an NP-complete problem. An efficient solution for this problem …

Nonlinear System Identification Using Recurrent Networks, Hyungkeun Lee, Y. Park, Kishan Mehrotra, Sanjay Ranka

Electrical Engineering and Computer Science - Technical Reports

This paper presents empirical results on the application of neural networks to system identification and inverse system identification. Recurrent and Feedforward network models are used to build an emulator of a simple nonlinear gantry crane system, and for the inverse dynamics of the system. Recurrent networks were observed to perform slightly better than feedforward networks for these problems.

Constructing Real-Time Systems From Temporal I/O Automata, J. F. Peters Iii, S. Ramanna

Electrical Engineering and Computer Science - Technical Reports

A new class of communicating automata called Temporal Input/Output Automata (TAi/os) is introduced. A TAi/o is a predicate automaton used to specify real-time systems. The specification provided by a TAi/o includes state predicates with proof expressions and abstract program syntax as attributes. An abstract program is extracted during a constructive proof of the specification using the proof expressions. A TAi/o specification also includes hard, real-time constraints on program behavior. The predictability of deterministic, temporally complete TAi/o is investigated. The formulation of real-time system transductions and transduction rules for TAi/os in explicit clock temporal logic is given. An illustration of the …

A Generic Multiplication Pipeline, Per Brinch Hansen

Electrical Engineering and Computer Science - Technical Reports

This paper illustrates the benefits of developing generic algorithms for parallel programming paradigms which can be adapted to different applications. We consider a combinatorial problem called tuple multiplication. This paradigm includes matrix multiplication and the all-pairs shortest paths problem as special cases. We develop a generic pipeline for tuple multiplication. From the generic algorithm we derive pipelines for matrix multiplication and shortest paths computation by making substitutions of data types and functions. The performance of the matrix multiplication pipeline is analyzed and measured on a Computing Surface.

Fast Symmetric Graph Drawing: Theory And Realization, R. T. Pacheco, J. B. Manning

Computer Science Technical Reports

This thesis explores the computational techniques necessary to efficiently realize certain optimal algorithms for the production of drawings which exhibit maximum axial and rotational symmetries of abstract graphs.

The problem of geometric symmetry detection for general graphs has been shown to be NP-complete. However, optimal algorithms have recently been established for the detection of symmetry in trees, outerplanar graphs, and embedded planar graphs. This thesis focuses on the utilization of these algorithms to efficiently produce maximally symmetric drawings of graphs from the classes of symmetric trees and outerplanar graphs.

The construction of symmetric tree drawings is presented first. Following a …

Fast Parallel Algorithms For Basic Problems, Zhaofang Wen

Computer Science Theses & Dissertations

Parallel processing is one of the most active research areas these days. We are interested in one aspect of parallel processing, i.e. the design and analysis of parallel algorithms. Here, we focus on non-numerical parallel algorithms for basic combinatorial problems, such as data structures, selection, searching, merging and sorting. The purposes of studying these types of problems are to obtain basic building blocks which will be useful in solving complex problems, and to develop fundamental algorithmic techniques.

In this thesis, we study the following problems: priority queues, multiple search and multiple selection, and reconstruction of a binary tree from its …

Smili-Visualization Of Asynchronous Massively Parallel Programs, Rashi Khanna, Bruce M. Mcmillin

Computer Science Technical Reports

A visualization model has been developed to analyse the performance of a massively parallel algorithm. Most visualization tools that have been developed so far for performance analysis are based generally on individual processor information and communication patterns (eg. processor load, message traffic etc.). These tools, however, are inadequate for massively parallel computations. It is difficult to comprehend the visual information for many processors. The model, SMil...l (Scientific visualization in Multicomputing for Interpretation of Large amounts of Information), addresses this problem by using abstract representations to attain a composite picture which gives better insight to the behavior of the algorithm. Chernoff's …

Comparison Of Three Axiomatic Systems For Csp, Hanan Lutfiyya, Bruce M. Mcmillin

Computer Science Technical Reports

Currently software engineering practices use relatively few formal methods. However, formal methods can be used to find errors earlier in the software cycle and hence reduce software cost. One useful formal method is program verification. The axiomatic approach to program verification uses assertions to characterize properties of program variables and relationships between them at various stages of program execution. In order to verify these assertions, axioms or inference rules are needed for each statement as well as some statement-independent inference rules. The message passing and nondeterminism of a distributed programming language present special difficulties. This paper examines and compares three …

Smili-Visualization Of Asynchronous Massively Parallel Programs, Rashi Khanna, Bruce M. Mcmillin

Computer Science Technical Reports

A visualization model has been developed to analyse the performance of a massively parallel algorithm. Most visualization tools that have been developed so far for performance analysis are based generally on individual processor information and communication patterns (eg. processor load, message traffic etc.). These tools, however, are inadequate for massively parallel computations. It is difficult to comprehend the visual information for many processors. The model, SMil...l (Scientific visualization in Multicomputing for Interpretation of Large amounts of Information), addresses this problem by using abstract representations to attain a composite picture which gives better insight to the behavior of the algorithm. Chernoff's …

Comparison Of Three Axiomatic Systems For Csp, Hanan Lutfiyya, Bruce M. Mcmillin

Computer Science Technical Reports

Currently software engineering practices use relatively few formal methods. However, formal methods can be used to find errors earlier in the software cycle and hence reduce software cost. One useful formal method is program verification. The axiomatic approach to program verification uses assertions to characterize properties of program variables and relationships between them at various stages of program execution. In order to verify these assertions, axioms or inference rules are needed for each statement as well as some statement-independent inference rules. The message passing and nondeterminism of a distributed programming language present special difficulties. This paper examines and compares three …

A Sixteen-Valued Algorithm For Test Generation In Combinational Circuits, Akhtar Uz Zaman, M. Ali, Carlos R.P. Hartmann

Electrical Engineering and Computer Science - Technical Reports

A 16-valued logic system for testing combinational circuits is presented. This logic system has been used to develop SIMPLE, an efficient test generation algorithm for single stuck-at faults. The proposed scheme for testing stuck-at faults is based on imposing all the constraints that must be satisfied in order to sensitize a path from a fault site to a primary output. Consequently all deterministic implications are fully considered prior to the enumeration process. The resulting ability to identify inconsistencies prior to enumeration improves the possibility of quicker identification of redundant faults. In order to prune the search space we have introduced …

A Variable-Free Logic For Mass Terms, William C. Purdy

Electrical Engineering and Computer Science - Technical Reports

This paper presents a logic appropriate for mass terms, that is, a logic that does not presuppose interpretation in discrete models. Models may range from atomistic to atomless. This logic is a generalization of the author's work on natural language reasoning. The following claims are made for this logic. First, absence of variables makes it simpler than more conventional formalizations based on predicate logic. Second, capability to deal effectively with discrete terms, and in particular with singular terms, can be added to the logic, making it possible to reason about discrete entities and mass entities in a uniform manner. Third, …