Digital Commons Network^™

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 …

Converting Binary Thresholds Networks Into Equivalent Symmetric Networks, Gadi Pinkas

All Computer Science and Engineering Research

We give algorithms to convert any network of binary threshold units (that does not oscillate) into an equivalent network with symmetric weight matrix (like Hopfield networks [Hopfield 82] or Boltzmann machines [Hinton, Sejnowski 88]). The motivation for the transformation is dual: a) to demonstrate the expressive power of symmetric networks; i.e. binary threshold networks (that do not oscillate) are subsumed in the energy minimization paradigm; 2) to use network modules (developed for the spreading activation paradigm for example), within the energy minimization paradigm. Thus optimization [Tank, Hopfield 88] and approximation of hard problems can be combined with efficient modules, that …

An Access Protection Solution For Heavy Load Unfairness In Dqdb, Lakshmana N. Kumar, Andreas D. Bovopoulos

All Computer Science and Engineering Research

This paper discusses the unfairness issue arising in a 802.6 DQDB network at high loads-- when the traffic demand to a bus exceeds the capacity of that bus. As per the 802.6 protocol, at heavy loads, the end nodes along a bus experience longer delays than the other nodes. The origin and remedy of this heavy load unfairness is discussed. An access control scheme is proposed as a solution. The comparison of the proposed scheme with 802.6 protocol is presented. The simulation results and performance characteristics are discussed under several types of loads. With symmetric load conditions under the proposed …

The Spectrum Simulation System: A Formal Approach To Distributed Algorithm Development Tools, Kenneth J. Goldman

All Computer Science and Engineering Research

We present the Spectrum Simulation System, a new research tool for the design and study of distributed algorithms. Based on the formal Input/Output Automation model of Lynch and Tuttle, Spectrum allows one to express distributed algorithms as collections of I/O automata and simulate them directly in terms of the semantics of that model. This permits integration of algorithm specification, design, debugging, analysis, and proof of correctness within a single formal framework that is natural for describing distributed algorithms. Spectrum provides a language for expressing algorithms as I/O automata, a simulator for generating algorithm executions, and a graphics interface for constructing …

Rapid Display Of Radiographic Images, Jerome R. Cox Jr., Stephen M. Moore, Robert A. Whitman, G. James Blaine, R. Gilbert Jost, L. Magnus Karlsson, Thomas L. Monsees, Gregory L. Hansen, Timothy C. David

All Computer Science and Engineering Research

The requirements for the rapid display of radiographic images exceed the capabilities of widely available display, computer and communication technologies. Computed radiography captures data with a resolution of about four megapixels. Large format displays are available that can present over four megapixels. One megapixel displays are practical for use in combination with large format displays and in areas where the viewing task does not require primary diagnosis. This paper describes an electronic radiology system that approximates the highest quality systems, but through the use of several interesting techniques allows the possibility of its widespread installation throughout hospitals. The techniques uses …

Composition, Superposition, And Encapsulation In The Formal Specification Of Distributed Systems, Kenneth J. Goldman

All Computer Science and Engineering Research

Composition, superposition, and encapsulation are important techniques that work well together for designing large distributed software systems. Composition is a symmetric operator that allows system components to communicate with each other across module boundaries. Superposition is an asymmetric relationship that allows one system component to observe the state of another. Encapsulation is the ability to define the reason about the behavior of a module in terms of a well-defined boundary between that module and its environment, while hiding the internal operations of that module. In this paper, the I/O automation model of Lynch and Tuttle is extended to permit superposition …

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 …

A Robust Approach To Human-Computer Interface Design Using The Taguchi Method, Billie Mitchell Reed

Engineering Management & Systems Engineering Theses & Dissertations

The application of Dr. Genichi Taguchi's approach for design optimization, called Robust Design, to the design of human-computer interface software is investigated. The Taguchi Method is used to select a near optimum set of interface design alternatives to improve user acceptance of the resulting interface software product with minimum sensitivity to uncontrollable noise caused by human behavioral characteristics.

Design alternatives for interaction with personal micro-computers are identified. Several important and representative alternatives are chosen as design parameters for the Taguchi matrix experiment. A noise field with three human behavioral characteristics as noise factors were chosen as a representative noise array. …

An Nc Algorithm For Scheduling Unit-Time Jobs With Arbitrary Release Times And Deadlines, Greg N. Frederickson, Susan H. Rodger

Department of Computer Science Technical Reports

No abstract provided.

Philco: Some Recollections Of The Philco Transac S-2000, Saul Rosen

Department of Computer Science Technical Reports

No abstract provided.

Porting Ncube Packages To Ipsc/860 And Ipsc/2 Hypercubes, Jingwen Wang, Mo Mu

Department of Computer Science Technical Reports

No abstract provided.

Ambivalent Data Structures For Dynamic 2-Edge-Connectivity And K Smallest Spanning Trees, Greg N. Frederickson

Department of Computer Science Technical Reports

No abstract provided.

Negotiating And Supporting Interdependent Data In Very Large Federated Database Systems, Ahmed K. Elmagarmid, James G. Mullen

Department of Computer Science Technical Reports

No abstract provided.

Design And Implementation Of A Distributed System With Dynamic Resource Allocation Based Upon Bidding Schemes, Dan C. Marinescu, Kenneth Wenstrup, Patrick Davis

Department of Computer Science Technical Reports

No abstract provided.

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 …

Performance Experiments And Optimizations Of Pde Sparse Solvers On Hypercubes,, Mo Mu, John R. Rice, Jingwen Wang

Department of Computer Science Technical Reports

No abstract provided.

Fundamental Techniques For Geometric And Solid Modeling, Christoph M. Hoffmann, George Vanĕček

Department of Computer Science Technical Reports

No abstract provided.

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 …

Corrigendum To "Taxonomies Of Model-Theoretically Defined Topological Properties", Paul Bankston

Mathematics, Statistics and Computer Science Faculty Research and Publications

An error has been found in the cited paper; namely, Theorem 3.1 is false.

Dna Mapping Algorithms: Abstract Data Types - Concepts And Implementation, Will Gillett, Liz Hanks

All Computer Science and Engineering Research

The conceptual aspects of and the implementation details of a set of self-identifying abstract data types (ADT) are described. Each of the ADTs constitutes a specific class of object, upon which a set of well-defined access functions is available. The intent of these ADTs is to supply a paradigm in which a class of object is available for manipulation, but in which the underlying implementation is hidden from the application programmer. Specific ADTs are the described in some detail. The tagged architecture used to achieve the self-identifying property of the ADTs is presented, and a set of required system-backbone access …

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, …

Hidden Markov Model For Visual Guidance Of Robot Motion In Dynamic Environment, Qiuming Zhu

Computer Science Faculty Publications

Models and control strategies for dynamic obstacle avoidance in visual guidance of mobile robot are presented. Characteristics that distinguish the visual computation and motion-control requirements in dynamic environments from that in static environments are discussed. Objectives of the vision and motion planning are formulated as: 1) finding a collision-free trajectory that takes account of any possible motions of obstacles in the local environment; 2) such a trajectory should be consistent with a global goal or plan of the motion; and 3) the robot should move at as high a speed as possible, subject to its kinematic constraints. A stochastic motion-control …

Time Delay Neural Networks And Speech Recognition: Context Independence Of Stops In Different Vowel Environments, Gregory Andrew Makowski

Masters Theses

A series of speech recognition experiments was conducted to investigate time-dynamic speech recognition of stop consonants invariant of vowel environment using data from six talkers. The speech preprocessing was based on previous studies investigating acoustic characteristics which correlate to the place of articulation (Blumstein and Stevens 1979). The place of articulation features were statistically abstracted using four moments and the energy level of the speech sample.

Both statistical and neural network pattern recognition methods were used. Statistical methods included linear and quadratic discriminant functions, maximum likelihood estimator (MLE) and K-nearest neighbors (KNN). The neural network approach used was Time Delay …