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Articles 12601 - 12630 of 12790

Full-Text Articles in Physical Sciences and Mathematics

The Washington University Multimedia System, William D. Richard, Jerome R. Cox Jr., Brian Gottlieb, Ken Krieger Jan 1993

The Washington University Multimedia System, William D. Richard, Jerome R. Cox Jr., Brian Gottlieb, Ken Krieger

All Computer Science and Engineering Research

The Washington University Multimedia System (MMS) is a complete multimedia system capable of transmitting and receiving video, audio, and radiological images, in addition to normal network traffic, over the Washingon University broadband ATM network. The MMS consists of an ATMizer and three multimedia subsystems. The ATMizer implements the host interface, the interface to the ATM network, and the interface to the three multimedia subsystems. The video sybsystem encodes and decodes JPEG compressed video using two hardware compression engines. The audio subsystem encodes and decodes CD-quality stereo audio. The high-speed radiological image subsystem reformats radiological image data transmitted by a dedicated …

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A Fault Tolerant Connectionist Architecture For Construction Of Logic Proofs, Gadi Pinkas Jan 1993

A Fault Tolerant Connectionist Architecture For Construction Of Logic Proofs, Gadi Pinkas

All Computer Science and Engineering Research

This chapter considers the problems of expressing logic and constructing proofs in fault tolerant connectionist networks that are based on energy minimalism. Given a first-order-logic knowledge base and a bound k, a symmetric network is constructed (like a Boltzman machine or a Hopfield network) that searches for a proof for a given query. If a resolution-based proof of length no longer than k exists, then the global minima of the energy function that is associated with the network represent such proofs. If no proof exist then the global minima indicate the lack of a proof. The network that is generated …

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Research Proposal: Preference Acquisition Through Reconciliation Of Inconsistencies, Nilesh L. Jain Jan 1993

Research Proposal: Preference Acquisition Through Reconciliation Of Inconsistencies, Nilesh L. Jain

All Computer Science and Engineering Research

The quality of performance of a decision-support system (or an expert system) is determined to a large extent by its underlying preference model (or knowledge base). The difficulties in preference and knowledge acquisition make them a major focus of current research in decision-support and expert systems. Researchers have used various concepts to develop promising acquisition techniques. One of the concepts used is knowledge maintenence where the knowledge base is changed in response to incorrect or inadequate performance by the expert system. This dissertation investigates a preference acquisition technique based on the reconciliation of inconsistencies between the preference model and the …

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Objective Evaluation Of Radiation Treatment Plans, Nilesh L. Jain, Michael G. Kahn Jan 1993

Objective Evaluation Of Radiation Treatment Plans, Nilesh L. Jain, Michael G. Kahn

All Computer Science and Engineering Research

The evaluation of radiation treatment plans involves making trade-offs among doses delivered to the tumor volumes and nearby normal tissues. Evaluating state-of-the-art three-dimensional (3D) plans is a difficult task because of the huge amount of planning data that needs to be deciphered. Multiattribute utility theory provides a methodology for specifying trade-offs and selecting the optimal plan from many competing lans. Using multiattribute utility theory, we are developing a clinically meaningful objective plan-evaluation model for 3D radiation treatment plans. Our model incorporates three of the factors involved in radiation treatment evaluation - treatment preferences of the radiation oncologist, clinical condition of …

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Teaching A Smarter Learner, Sally A. Goldman, H. David Mathias Jan 1993

Teaching A Smarter Learner, Sally A. Goldman, H. David Mathias

All Computer Science and Engineering Research

We introduce a formal model of teaching in which the teacher is tailored to a particular learner, yet the teaching protocol is designed so that no collusion is possible. Not surprisingly, such a model remedies the non-intuitive aspects of otehr models in which the teacher must successfully teach any consistent learner. We prove that any class that can be exactly identified by a deterministic polynomial-time algorithm with access to a very rich set of example-based queries is teachable by a computationally unbounded teacher and a polynomial-time learner. In addition, we present other general results relating this model of teaching to …

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Improving The Speed Of A Distributed Checkpointing Algorithm, Sachin Garg, Kenneth F. Wong Jan 1993

Improving The Speed Of A Distributed Checkpointing Algorithm, Sachin Garg, Kenneth F. Wong

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This paper shows how Koo and Toueg's distributed checkpointing algorithm can be modified so as to substantially reduce the average message volume. It attempts to avoid O(n{squared}) messages by using dependency knowledge to reduce the number of checkpoint request messages. Lemmas on consistency and termination are also included.

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Trainrec: A System For Training Feedforward & Simple Recurrent Networks Efficiently And Correctly, Barry L. Kalman, Stan C. Kwasny Jan 1993

Trainrec: A System For Training Feedforward & Simple Recurrent Networks Efficiently And Correctly, Barry L. Kalman, Stan C. Kwasny

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TRAINREC is a system for training feedforward and recurrent neural networks that incorporates several ideas. It uses the conjugate-gradient method which is demonstrably more efficient than traditional backward error propagation. We assume epoch-based training and derive a new error function having several desirable properties absent from the traditional sum-of-squared-error function. We argue for skip (shortcut) connections where appropriate and the preference for a sigmoidal yielding values over the [-1,1] interval. The input feature space is often over-analyzed, but by using singular value decomposition, input patterns can be conditioned for better learning often with a reduced number of input units. Recurrent …

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A Characterization Of The Computational Power Of Rule-Based Visualization, Kenneth C. Cox, Gruia-Catalin Roman Jan 1993

A Characterization Of The Computational Power Of Rule-Based Visualization, Kenneth C. Cox, Gruia-Catalin Roman

All Computer Science and Engineering Research

Declarative visualization is a paradigm in which the process of visualization is treated as a mapping from some domain (typically a program) to an image. One means of declaring such mappings is through the use of rules which specify the relationship between the domain and the image. This paper examines the computational power of such rule-based mappings. Computational power is measure using three separate criteria. The first of these uses the Chomsky hierarchy, in which computational power is treated as string-acceptance; with this criterion we are able to show that certain rule-based models are equivalent in power to Turing machines. …

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Logical Interference In Symmetric Connectionist Networks, Gadi Pinkas Jan 1993

Logical Interference In Symmetric Connectionist Networks, Gadi Pinkas

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This work delineates the relation between logic and symmetric neural networks. The motivation is two-fold: 1) to study the capabilities and limitations of connectionist networks with respect to knowledge representatoin; and 2) to develop a new kind of inference negine that is expressive, massively parallel, capable of coping with nonmonotonic or noisy knowledge and capable of learning. The thesis shows that propositional logic can be implemented efficiently in networks where hidden units allow the representation of arbitrary constraints. An inference engine is constructed which can obtain its knowledge either by compiling symbolic rules or by learning them inductively from examples. …

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A Comparison Study Of The Pen And The Mouse In Editing Graphic Diagrams, Ajay Apte, Takayuki Dan Kimura Jan 1993

A Comparison Study Of The Pen And The Mouse In Editing Graphic Diagrams, Ajay Apte, Takayuki Dan Kimura

All Computer Science and Engineering Research

We report the results of an experiment comparing the merits of the pen and the mouse as drawing devices. For this study a pen-based graphic diagram editor equipped with a shape recognition algorithm was developed on GO's PenPoint operating system. A commercially available drawing program on NeXT was used for mouse-based editing. Twelve CS students were chosen as subjects and asked to draw four different diagrams of similar complexity: two with a pen and the other two with a mouse. The diagrams are chosen from the categories of dataflow visual language, Petri nets, flowcharts, and state diagrams. The results indicate …

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A Taxonomy Of Program Visualization Systems, Gruia-Catalin Roman, Kenneth C. Cox Jan 1993

A Taxonomy Of Program Visualization Systems, Gruia-Catalin Roman, Kenneth C. Cox

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Program visualization may be viewed as a mapping from programs to graphical representations. This simple idea provides a formal framework for a new taxonomy of program visualization systems. The taxonomy is compared briefly against previous attempts to organize the program visualization field. The taxonomic principles and their motivation are explained in detail with reference to a number of existing systems, especially Balsa, Tango, and Pavane.

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Asking Questions To Minimize Errors, Nader H. Bshouty, Sally A. Goldman, Thomas R. Hancock, Sleiman Matar Jan 1993

Asking Questions To Minimize Errors, Nader H. Bshouty, Sally A. Goldman, Thomas R. Hancock, Sleiman Matar

All Computer Science and Engineering Research

A number of efficient learning algorithms achieve exact identification of an unknown function from some clas using membership and equivalence queries. Using a standard transformation such algorithms can easily be converted to on-line learning algorithms that use membership queries. Under such a transformation the number of equivalence queries made by the query algorithm directly corresponds to the number of mistakes made by the on-line algorithm. In this paper we consider several of the natural classes known to be learnable in this setting, and investigate the minimum number of equivalence queries with accompanying counterexamples (or equivalently the minimum number of mistakes …

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Fril - A Fractal Intermediate Language, Ron Cytron, David Shields Jan 1993

Fril - A Fractal Intermediate Language, Ron Cytron, David Shields

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This document describes the motivation, language description, and experience using FrIL, an intermediate language for a compiler's "middle-end." FrIL has subbessfully supported a two-semester compiler construction sequence, where the first semester included code generation from a C-like language and the second semester included advanced data flow analysis and program transformation.

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The Pessimism Behind Optimistic Simulation, George Varghese, Roger D. Chamberlain, William E. Weihl Jan 1993

The Pessimism Behind Optimistic Simulation, George Varghese, Roger D. Chamberlain, William E. Weihl

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In this paper we make an analogy between the time that storage must be maintained in an optimistic simulation and the blocking time in a conservative simulation. By exploring this analogy, we design two new Global Virtual Time (GVT) protocols for Time Warp systems. The first simple protocol is based on the null message scheme proposed for clock advancement in some conservative approaches; this yields what we call Local Guaranteed Time. Our main contribution is a second new protocol that is inspired by Misra's circulating marker scheme for deadlock recovery in conservative simulations, and appears to have advantages over previous …

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A Study Of Dynamic Optimization Techniques: Lessons And Directions In Kernel Design, Calton Pu, Jonathan Walpole Jan 1993

A Study Of Dynamic Optimization Techniques: Lessons And Directions In Kernel Design, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

The Synthesis kernel [21,22,23,27,28] showed that dynamic code generation, software feedback, and fine-grain modular kernel organization are useful implementation techniques for improving the performance of operating system kernels. In addition, and perhaps more importantly, we discovered that there are strong interactions between the techniques. Hence, a careful and systematic combination of the techniques can be very powerful even though each one by itself may have serious limitations. By identifying these interactions we illustrate the problems of applying each technique in isolation to existing kernels. We also highlight the important common under-pinnings of the Synthesis experience and present our ideas on …

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Observation Of The Charmed Baryon C+ And Measurement Of The Isospin Mass Splittings Of The C, Crawford, G.; Et Al., M. Thulasidas Jan 1993

Observation Of The Charmed Baryon C+ And Measurement Of The Isospin Mass Splittings Of The C, Crawford, G.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.

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Rule-Maker's And Rule-Follower's Meaning, R. P. Loui Jan 1993

Rule-Maker's And Rule-Follower's Meaning, R. P. Loui

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No abstract provided.

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A Comparison Of Queueing, Cluster And Distributed Computing Systems, Joseph A. Kaplan, Michael L. Nelson Jan 1993

A Comparison Of Queueing, Cluster And Distributed Computing Systems, Joseph A. Kaplan, Michael L. Nelson

Computer Science Faculty Publications

Using workstation clusters for distributed computing has become popular with the proliferation of inexpensive, powerful workstations. Workstation clusters offer both a cost effective alternative to batch processing and an easy entry into parallel computing. However, a number of workstations on a network does not constitute a cluster. Cluster management software is necessary to harness the collective computing power. A variety of cluster management and queuing systems are compared: Distributed Queueing Systems (DQS), Condor, Load Leveler, Load Balancer, Load Sharing Facility (LSF - formerly Utopia), Distributed Job Manager (DJM), Computing in Distributed Networked Environments (CODINE), and NQS/Exec. The systems differ in …

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Intel Nx To Pvm 3.2 Message Passing Conversion Library, Trey Arthur, Michael L. Nelson Jan 1993

Intel Nx To Pvm 3.2 Message Passing Conversion Library, Trey Arthur, Michael L. Nelson

Computer Science Faculty Publications

NASA Langley Research Center has developed a library that allows Intel NX message passing codes to be executed under the more popular and widely supported Parallel Virtual Machine (PVM) message passing library. PVM was developed at Oak Ridge National Labs and has become the defacto standard for message passing. This library will allow the many programs that were developed on the Intel iPSC/860 or Intel Paragon in a Single Program Multiple Data (SPMD) design to be ported to the numerous architectures that PVM (version 3.2) supports. Also, the library adds global operations capability to PVM. A familiarity with Intel NX …

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Design And Implementation Of Fuzzy Logic Controllers. Thesis Final Report, 27 July 1992 - 1 January 1993, Osama A. Abihana, Oscar R. Gonzalez Jan 1993

Design And Implementation Of Fuzzy Logic Controllers. Thesis Final Report, 27 July 1992 - 1 January 1993, Osama A. Abihana, Oscar R. Gonzalez

Electrical & Computer Engineering Faculty Publications

The main objectives of our research are to present a self-contained overview of fuzzy sets and fuzzy logic, develop a methodology for control system design using fuzzy logic controllers, and to design and implement a fuzzy logic controller for a real system. We first present the fundamental concepts of fuzzy sets and fuzzy logic. Fuzzy sets and basic fuzzy operations are defined. In addition, for control systems, it is important to understand the concepts of linguistic values, term sets, fuzzy rule base, inference methods, and defuzzification methods. Second, we introduce a four-step fuzzy logic control system design procedure. The design …

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Efficient Accommodation Of May-Alias Information In Ssa Form, Ron Cytron, Reid Gershbein Dec 1992

Efficient Accommodation Of May-Alias Information In Ssa Form, Ron Cytron, Reid Gershbein

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We present an algorithm for incrementally including may-alias information into Static Single Assignment form by computing a sequence of increasingly precise (and correspondingly larger) partial SSA forms. Our experiments show significant speedup of our method over exhaustive use of may-alias information, as optimization problems converge well before most may-aliases are needed.

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Exact Dominance Without Search In Decision Trees, Nilesh L. Jain, Ronald P. Loui Dec 1992

Exact Dominance Without Search In Decision Trees, Nilesh L. Jain, Ronald P. Loui

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In order to improve understanding of how planning and decision analysis relate, we propose a hybrid model containing concepts from both. This model is comparable to [Hartman90], with slightly more detail. Dominance is simple concept in decision theory. In a restricted version of our model, we give conditions under which dominance can be detected without search: that is, it can be used as a pruning strategy to avoid growing large trees. This investigation follows the lead of [Wellman87]. The conditions seem hard to meet, but may nevertheless be useful in forward-chaining situations without focus, such as [Breese87]. It may be …

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Object-Oriented Analysis, Design, And Implementation Of The Saber Wargame, David S. Douglass Dec 1992

Object-Oriented Analysis, Design, And Implementation Of The Saber Wargame, David S. Douglass

Theses and Dissertations

Saber is a two-sided, air and land war game that simulates decisions made of commanders at the theater-level. It is being developed by the Air Force Institute of Technology for the Air Force Wargaming center at Maxwell AFB, Alabama. Saber models conventional, chemical, and nuclear warfare between aggregated air and land forces. It also portrays the effects of logistics, satellites, weather, terrain, and intelligence which add to the realism of the Saber war game. The Saber war game has three main components, the preprocessor. which is responsible for scenario development and pregame activities, the simulation. the guts of the war …

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A Vhdl Interpreter For Model-Based Diagnoses, David R. Griffin Dec 1992

A Vhdl Interpreter For Model-Based Diagnoses, David R. Griffin

Theses and Dissertations

Model-based reasoning permits diagnostic applications to be written without waiting for someone to become an 'expert' of the system. For model-based diagnostics, there must be a model to reason from. This thesis explores using a VHDL description of the system as that model. A system based around a VHDL interpreter was written specifically for a model-based diagnostic algorithm. Currently, the diagnostic system uses an algorithm by Dries. This algorithm was derived from Scarl's Full Consistency Algorithm. The system was designed to be modular so that different diagnostic techniques could be implemented. It is divided into three parts: a VHDL parser, …

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An Intelligent Real-Time System Architecture Implemented In Ada, Michael A. Whelan Dec 1992

An Intelligent Real-Time System Architecture Implemented In Ada, Michael A. Whelan

Theses and Dissertations

Conventional real-time systems are fully deterministic allowing for off-line, optimal, task scheduling under all circumstances. Real-time intelligent systems add non-deterministic task execution times and non- deterministic task sets for scheduling purposes. Non-deterministic task sets force intelligent real-time systems to trade-off execution time with solution quality during run-time and perform dynamic task scheduling. Four basic design considerations addressing those tradeoffs have been identified: control reasoning, focus of attention, parallelism, and algorithm efficacy. Non-real- time intelligent systems contain an environment sensor, a model of the environment, a reasoning process, and a large collection of procedural processes. Real-time intelligent systems add to these …

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Creating And Manipulating Formalized Software Architectures To Support A Domain-Oriented Application Composition System, Cynthia G. Anderson Dec 1992

Creating And Manipulating Formalized Software Architectures To Support A Domain-Oriented Application Composition System, Cynthia G. Anderson

Theses and Dissertations

This research investigated technology which enables sophisticated users to specify, generate, and maintain application software in domain-oriented terms. To realize this new technology, a development environment, called Architect, was designed and implemented. Using canonical formal specifications of domain objects, Architect rapidly composes these specifications into a software application and executes a prototype of that application as a means to demonstrate its correctness before any programming language specific code is generated. Architect depends upon the existence of a formal object base (or domain model) which was investigated by another student in related research. The research described in this thesis relied on …

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Formalizing, Validating, And Verifying Real-Time System Requirements With Reacto And Vhdl, Frank C. Young Dec 1992

Formalizing, Validating, And Verifying Real-Time System Requirements With Reacto And Vhdl, Frank C. Young

Theses and Dissertations

We develop a methodology for formalizing, verifying, and validating the requirements specification of real-time systems based on a graphical and formal hierarchical Finite State Machine (FSM) language Reacto. We define a means to quantify time and express real-time constraints in Reacto and a transformation from Reacto to the Very High Speed Integrated Circuit (VHSIC) hardware Description Language (VHDL). Reacto's high level abstractions, graphical nature, and theorem prover produce efficient, accurate, and easily understood specifications. We use VHDL's event driven simulation capability, concurrency, and temporal operators to thoroughly examine temporal dependencies between the state machine transitions, and to increase simulation power …

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Solution To A Multicriteria Aircraft Routing Problem Utilizing Parallel Search Techniques, James J. Grimm Iii Dec 1992

Solution To A Multicriteria Aircraft Routing Problem Utilizing Parallel Search Techniques, James J. Grimm Iii

Theses and Dissertations

Pilots select routes based on factors such as threats, fuel, time on target, distance, and refueling points. This is a time consuming task. This thesis presents the software engineering synthesis of a software tool, based on a parallelized A* search algorithm, to select routes. For simplicity only threats and distance are used. A centralized open list is used with one processor managing the list while the other processors perform the node expansions. This decomposition result in a dynamically load balanced system. A number of parameters are changed to study their impact on the execution time. The use of a branch …

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Generalization And Parallelization Of Messy Genetic Algorithms And Communication In Parallel Genetic Algorithms, Laurence D. Merkle Dec 1992

Generalization And Parallelization Of Messy Genetic Algorithms And Communication In Parallel Genetic Algorithms, Laurence D. Merkle

Theses and Dissertations

Genetic algorithms (GA) are highly parallelizable, robust semi- optimization algorithms of polynomial complexity. The most commonly implemented GAs are 'simple' GAs (SGAs). Reproduction, crossover, and mutation operate on solution populations. Deceptive and GA-hard problems are provably difficult for simple GAs. Messy GAs (MGA) are designed to overcome these limitations. The MGA is generalized to solve permutation type optimization problems. Its performance is compared to another MGA's, an SGA's, and a permutation SGA's. Against a fully deceptive problem the generalized MGA (GMGA) consistently performs better than the simple GA. Against an NP-complete permutation problem, the GMGA performs better than the other …

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The Programmers' Playground: I/O Abstraction For Heterogeneous Distributed Systems, Kenneth J. Goldman, Michael D. Anderson Nov 1992

The Programmers' Playground: I/O Abstraction For Heterogeneous Distributed Systems, Kenneth J. Goldman, Michael D. Anderson

All Computer Science and Engineering Research

A new high-level approach to interprocess communication in heterogeneous distributed systems in introduced, This approach, called I/O Abstraction, allows one to write each functional component of a distributed system as an encapsulated program that acts upon a set of local data structures, some of which may be published for external use. The functional components are separately configured by establishing logical connections among the published data structures. In order to illustrate this approach, we describe the The Programmers' Playground, a high-level language "veneer" and protocol designed to support I/O abstraction in heterogeneous computing environment. Support for communication among programs written in …

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