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The Vaidak Medical Imaging And Model Reconstruction Toolkit, Brian Bailey, Chanderjit Bajaj, Malcolm C. Fields Aug 1991

The Vaidak Medical Imaging And Model Reconstruction Toolkit, Brian Bailey, Chanderjit Bajaj, Malcolm C. Fields

Department of Computer Science Technical Reports

No abstract provided.


Suffix Trees Revisited: (Un)Expected Asymptotic Behaviors, Wojciech Szpankowski Aug 1991

Suffix Trees Revisited: (Un)Expected Asymptotic Behaviors, Wojciech Szpankowski

Department of Computer Science Technical Reports

No abstract provided.


Xs: A Hardware Independent Graphics And Windows Library, Vinod Anupam, Chanderjit L. Bajaj, Andrew Burnett, Malcolm C. Fields, Andrew V. Royappa Aug 1991

Xs: A Hardware Independent Graphics And Windows Library, Vinod Anupam, Chanderjit L. Bajaj, Andrew Burnett, Malcolm C. Fields, Andrew V. Royappa

Department of Computer Science Technical Reports

No abstract provided.


Computer Viruses And Ethics, Eugene H. Spafford Aug 1991

Computer Viruses And Ethics, Eugene H. Spafford

Department of Computer Science Technical Reports

No abstract provided.


C1 Smoothing Of Polyhedra With Implicit Surface Patches, Chanderjit L. Bajaj, Insung Ihm Aug 1991

C1 Smoothing Of Polyhedra With Implicit Surface Patches, Chanderjit L. Bajaj, Insung Ihm

Department of Computer Science Technical Reports

No abstract provided.


Using Algebraic Geometry For Multivariate Hermite Interpolation, Chanderjit L. Bajaj Aug 1991

Using Algebraic Geometry For Multivariate Hermite Interpolation, Chanderjit L. Bajaj

Department of Computer Science Technical Reports

No abstract provided.


On A Matrix Identity Connecting Iteration Operators Associated With A P-Cyclic Matrix, Apostolos Hadjidimos, Dimitrios Noutsoss Aug 1991

On A Matrix Identity Connecting Iteration Operators Associated With A P-Cyclic Matrix, Apostolos Hadjidimos, Dimitrios Noutsoss

Department of Computer Science Technical Reports

No abstract provided.


On Surface Design With Implicit Algebraic Surfaces (Ph.D. Thesis), Insung Ihm Aug 1991

On Surface Design With Implicit Algebraic Surfaces (Ph.D. Thesis), Insung Ihm

Department of Computer Science Technical Reports

No abstract provided.


Decompositions Of Polyhedra In Three Dimensions (Ph.D. Thesis), Tamal Krishna Dey Aug 1991

Decompositions Of Polyhedra In Three Dimensions (Ph.D. Thesis), Tamal Krishna Dey

Department of Computer Science Technical Reports

No abstract provided.


Formal Methods Of Real-Time Systems, Su-Mei Tsai, Bruce M. Mcmillin Aug 1991

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 Aug 1991

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 Aug 1991

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 Aug 1991

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 Aug 1991

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 Jul 1991

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 …


Collision Detection And Analysis In A Physically Based Simulation, William J. Bouma, George Vanĕček Jul 1991

Collision Detection And Analysis In A Physically Based Simulation, William J. Bouma, George Vanĕček

Department of Computer Science Technical Reports

No abstract provided.


Formal Generation Of Executable Assertions For A Fault-Tolerant Parallel Bitonic Sort, Hanan Lutfiyya, Bruce M. Mcmillin Jul 1991

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

Computer Science Technical Reports

No abstract provided.


Type Reconstruction For Coercion Polymorphism (Technical Summary), Ryan Stansifer, Dan Wetklow Jul 1991

Type Reconstruction For Coercion Polymorphism (Technical Summary), Ryan Stansifer, Dan Wetklow

Department of Computer Science Technical Reports

No abstract provided.


Selective Inheritance And Overriding In Statically-Typed Object-Oriented Languages, Ryan Stansifer, Dan Wetklow Jul 1991

Selective Inheritance And Overriding In Statically-Typed Object-Oriented Languages, Ryan Stansifer, Dan Wetklow

Department of Computer Science Technical Reports

No abstract provided.


Representation Requirements For Supporting Decision-Model Formulation, Tze-Yun Leong Jul 1991

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.


Multidimensional Digital Searching And Some New Parameters In Tries, Peter Kirschenhofer, Helmut Prodinger, Wojciech Szpankowski Jul 1991

Multidimensional Digital Searching And Some New Parameters In Tries, Peter Kirschenhofer, Helmut Prodinger, Wojciech Szpankowski

Department of Computer Science Technical Reports

No abstract provided.


The Complexity Of Local Stratification, Peter Cholak, Howard A. Blair Jul 1991

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 Jul 1991

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 Jul 1991

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 Jul 1991

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 Jul 1991

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 …


Composition, Superposition, And Encapsulation In The Formal Specification Of Distributed Systems, Kenneth J. Goldman Jul 1991

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 …


The Spectrum Simulation System: A Formal Approach To Distributed Algorithm Development Tools, Kenneth J. Goldman Jul 1991

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 …


An Access Protection Solution For Heavy Load Unfairness In Dqdb, Lakshmana N. Kumar, Andreas D. Bovopoulos Jul 1991

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 …


A Generic Multiplication Pipeline, Per Brinch Hansen Jul 1991

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.