Digital Commons Network^™

Conference On A Disk: A Successful Experiment In Hypermedia Publishing (Extended Abstract), M Cheyney, P Gloor, D B. Johnson, F Makedon, J Matthews, P Metaxas

Computer Science Technical Reports

Academic conferences are a long-standing and effective form of multimedia communication. Conference participants can transmit and recieve information through sight, speech, gesture, text, and touch. This same-time, same-place communication is sufficiently valuable to justify large investments in time and travel funds. Printed conference proceedings are attempts to recapture the value of a life conference, but they are limited by a fragmented and inefficient approach to the problem. We addressed this problem in the multimedia proceedings of the DAGS'92 conference. The recently published CD-ROM delibers text, graphic, audio, and video information as an integrated whole, with extensive provisions for random access …

Videoscheme: A Research, Authoring, And Teaching Tool For Multimedia, J Matthews, F Makedon, P Gloor

Computer Science Technical Reports

The availability of digital multimedia technology poses new challenges to researchers, authors, and educators, even as it creates new opportunities for rich communication. This paper suggests interactive computer programming as a fruitful approach to these challenges. VideoScheme, a prototype video programming environment, is described along with promising applications.

Quickest Paths: Faster Algorithms And Dynamization, Dimitrios Kagaris, Grammati E. Pantziou, Spyros Tragoudas, Christos D. Zaroliagis

Computer Science Technical Reports

Given a network $N=(V,E,{c},{l})$, where $G=(V,E)$, $|V|=n$ and $|E|=m$, is a directed graph, ${c}(e) > 0$ is the capacity and ${l}(e) \ge 0$ is the lead time (or delay) for each edge $e\in E$, the quickest path problem is to find a path for a given source--destination pair such that the total lead time plus the inverse of the minimum edge capacity of the path is minimal. The problem has applications to fast data transmissions in communication networks. The best previous algorithm for the single--pair quickest path problem runs in time $O(r m+r n \log n)$, where $r$ is the number …

Decoding Linear Block Codes Using A Priority-First Search: Performance Analysis And Suboptimal Version, Yunghsiang S. Han, Carlos R.P. Hartmann, Kishan Mehrotra

Electrical Engineering and Computer Science - Technical Reports

An efficient maximum-likelihood soft-decision decoding algorithm for linear block codes using a generalized Dijkstra's Algorithm was proposed by Han, Hartmann, and Chen. In this report we prove that this algorithm is efficient for most practical communication systems where the probability of error is less than 10-3 by finding an upper bound of the computation performance of the algorithm. A suboptimal decoding algorithm is also proposed. The performance of this suboptimal decoding algorithm is within 0.25 dB and 0.5 dB of the performance of an optimal decoding algorithm for the (104, 52) binary extended quadratic residue code and the (128, 64) …

Application Of Sequential Quadratic Programming To Large-Scale Structural Design Problems, Mark A. Abramson

Theses and Dissertations

Large-scale structural optimization problems are often difficult to solve with reasonable efficiency and accuracy. Such problems are often characterized by constraint functions which are not explicitly defined. Constraint and gradient functions are usually expensive to evaluate. An optimization approach which uses the NLPQL sequential quadratic programming algorithm of Schittkowski, integrated with the Automated Structural Optimization System ASTROS is tested. The traditional solution approach involves the formulation and solution of an explicitly defined approximate problem during each iteration. This approach is replaced by a simpler approach in which the approximate problem is eliminated. In the simpler approach, each finite element analysis …

A Simulation Approach To Granite Sentry System Analysis, Marilyn J. Bauer

Theses and Dissertations

This study demonstrated the use of simulation modelling to analyze Granite Sentry system performance. The availability simulation model constructed provides a number of system performance measures as a function of component MTBFs and MTTRs. Analysis of failure data prior to model construction supported the generally accepted use of exponentially distributed failure rates and lognormally distributed repair times.

A Topology-Aware Collision Resolution Algorithm, Lewis Barnett Iii

Department of Math & Statistics Technical Report Series

A new collision resolution algorithm called the Space Division Multiple Access protocol (SDMA) is presented. SDMA gains a performance advantage over similar protocols by using information about the positions of stations on the network. The protocol can operate asynchrononsly on a broadcast bus, allowing variable sized packet traffic. Through simulation the protocol is demonstrated to have better performance than Ethernet and the Capetanakis Tree protocol, a similar collision resolution protocol, under some traffic conditions. In particular, under heavy loads, SDMA displays better average throughput and lower variance of delay than Ethernet. The protocol demonstrates a performance bias based on the …

Edge Weight Reduction Problems In Directed Acyclic Graphs, Susanne E. Hambrusch, Hung-Yi Tu

Department of Computer Science Technical Reports

No abstract provided.

A Study Of Distributed Transaction Processing In Wide Area Network, Bharat Bhargava, Yongguang Zhang

Department of Computer Science Technical Reports

No abstract provided.

Writing, Supporting, And Evaluating Tripwire: A Publically Available Security Tool, Gene H. Kim, Eugene H. Spafford

Department of Computer Science Technical Reports

No abstract provided.

A Geometric Approach To Molecular Docking And Similarity, Chandrajit Bajaj, Fausto Bernardini, Kokichi Sugihara

Department of Computer Science Technical Reports

No abstract provided.

Thread Migration On Heterogeneous Systems Via Compile-Time Transformations, Janche Sang, Geoffrey W. Peters, Vernon J. Rego

Department of Computer Science Technical Reports

No abstract provided.

The Parallel Envelope, M.G. Rossmann, M. A. Cornea-Hasegan, D. C. Marinsecu, Z. Zhang, Robert E. Lynch, J. Muckelbauer, R. Mckenna, S. Munshi, J-B. Dai

Department of Computer Science Technical Reports

No abstract provided.

Pdelab: An Object-Oriented Framework For Building Problem Solving Environments For Pde Based Applications, Sanjiva Weerawarana, Elias N. Houstis, John. R. Rice, Ann Christine Catlin, Cheryl L. Crabill, Chi Ching Chui

Department of Computer Science Technical Reports

No abstract provided.

Automating Output Size And Reuse Metrics In A Repository-Based Computer-Aided Software Engineering (Case) Environment, R. D. Banker, Robert J. Kauffman, C. Wright, D. Zweig

Research Collection School Of Computing and Information Systems

Measurement of software development productivity is needed in order to control software costs, but it is discouragingly labor-intensive and expensive. Computer-aided software engineering (CASE) technologies-especially repository-based, integrated CASE-have the potential to support the automation of this measurement. We discuss the conceptual basis for the development of automated analyzers for function point and software reuse measurement for object-based CASE. Both analyzers take advantage of the existence of a representation of the application system that is stored within an object repository, and that contains the necessary information about the application system. We also discuss metrics for software reuse measurement, including reuse leverage, …

Dyadic Wavelet Features For Isolated Word Speaker Dependent Speech Recognition, Stephen Ainge

Theses and Dissertations

This research examines the use of dyadic wavelet features for the recognition of speaker dependent isolated word speech. The features were generated using three different wavelet filters-Daubechies 4 coefficient (Db4), Daubechies 20 coefficient (Db20) and a 31 coefficient cubic spline and three different window lengths-15ms, 8ms and 4ms. The accuracy of the standard and over-sampled dyadic wavelet methods were compared. The over-sampled dyadic wavelet method using the Db4 scaling function, with a maximum accuracy of 65.5, was found to be the most accurate of the wavelet methods tested. The accuracy of this over-sampled dyadic Db4 wavelet method was compared to …

Effective Parallel Algorithm Animation, Paul W. Chase

Theses and Dissertations

The AFIT Algorithm Animation Research Facility AAARF was developed by the Air Force Institute of Technology AFIT as a teaching aid for data structures and algorithm design. In particular, an extensive set of performance animations has been developed for the Intel iPSC Hypercube parallel processing system. This research focuses in part on developing animation support for discrete event simulation, mission routing, and evolutionary algorithms based on abstract representations of parallel algorithm behavior. The effort also builds extensions to the AAARF system and examines direction for further research. An innovative adaptable application-specific animation construction environment has been designed and implemented. The …

Clustering Techniques In Speaker Recognition, Douglas N. Prescott

Theses and Dissertations

This thesis presents a comparison based on identification rate, of three clustering techniques applied to cepstral features for speaker identification. LBG vector quantization as developed by Linde, Buzo and Gray; is used to provide benchmark performance for comparison with Fuzzy clustering (based on the unsupervised fuzzy partition-optimal number of classes, UFP-ONC algorithm by Gath and Geva) and an Artificial Neural Network, the Multilayer Perceptron. Cepstral features from the TIMIT, King and AFIT93 corpus speaker databases are used to produce speaker-identification classifiers using each of the clustering algorithms. The experiment reported evaluates the speaker identification performance using the 20-dimensional cepstral features …

Assessing The Vulnerability Of Multi-Commodity Networks With Failing Components, Alan R. Robinson

Theses and Dissertations

This research proposes an analytical approach for assessing flow disturbance, or compromise, based on limited sampling of arc flow information in multi-commodity, or multiple origin-destination O-D, networks with failing arcs. There were three objectives established for this research. The first objective was to bound the expected flow, given the arcs fail with certain probabilities, which was accomplished by reviewing current approaches for single-commodity networks and extending the results to the multi-commodity case. The second objective was to determine the best placement of flow monitors to obtain the most accurate estimates of O-D pair volumes. This was accomplished using a multi-criteria …

The Effective Use Of Animation In Simulation Model Validation, Christopher L. Swider

Theses and Dissertations

This study examined two animation displays moving icons, bar graphs at two presentation speeds to determine how each of these factors affected the animations ability to communicate violations of model assumptions. Subjects viewed animation displays individually and in combination at each presentation speed. Eight problem scenarios were presented to evaluate each animations ability to communicate violations of different assumptions. Each animations communication ability was measured subjectively and objectively. Subjective measures in the form of pairwise comparisons were used to calculate normalized preference ratings for each animation. objective measures included problem identification accuracy and problem time. Subjective results indicated that moving …

Adaptive Execution Of Data Parallel Computations On Networks Of Heterogeneous Workstations, Robert Prouty, Steve Otto, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Parallel environments consisting of a network of heterogeneous workstations introduce an inherently dynamic environment that differs from multicomputers. Workstations are usually considered “shared” resources while multicomputers provide dedicated processing power. The number of workstations available for use is continually changing; the parallel machine presented by the network is in effect continually reconfiguring itself. Application programs must effectively adapt to the changing number of processing nodes while maintaining computational efficiency. This paper examines methods for adapting to this dynamic environment within the framework of explicit message passing under the data parallel programming model. We present four requirements which we feel a …

A Reduction Semantics For Array Expressions:The Psi Compiler, L. Mullin, S. Thibault

Computer Science Technical Reports

No abstract provided.

Formal Verification Of Distributed Deadlock Detection Algorithm Using A Time-Dependent Proof Technique, Pei-Yu Li, Bruce Mcmillin

Computer Science Technical Reports

A large number of published distributed deadlock detection/resolution algorithms are found to be incorrect because they have used informal approaches to prove the correctness of their algorithms. In this paper, we present a formal approach for the correctness proof and give an example of the proof. In this proposed approach, a formal model of distributed deadlock is presented with a local-time deadlock specification for correctness verification. With the formal model, we have an insight into the definition of deadlock in local views which is used to show the existence of a real deadlock. A rigorous proof to show the equivalence …

Using Tickets To Enforce The Serializability Of Multidatabase Transactions, Dimitrios Georgakopoulos, Marek Rusinkiewicz, Amit P. Sheth

Kno.e.sis Publications

To enforce global serializability in a multidatabase environment the multidatabase transaction manager must take into account the indirect (transitive) conflicts between multidatabase transactions caused by local transactions. Such conflicts are difficult to resolve because the behavior or even the existence of local transactions is not known to the multidatabase system. To overcome these difficulties, we propose to incorporate additional data manipulation operations in the subtransactions of each multidatabase transaction. We show that if these operations create direct conflicts between subtransactions at each participating local database system, indirect conflicts can be resolved even if the multidatabase system is not aware of …

Cooperating Brokers To Support Cooperative Work, Vinod Anupam, Chandrajit Bajaj, Peinan Zhang

Department of Computer Science Technical Reports

No abstract provided.

Comet: A Synthetic Benchmark For Message-Passing Architectures, Nalini Ganapati, Steve Otto, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Rapid advances in hardware technology have led to wide diversity in parallel computer architectures. This diversity makes it difficult to evaluate or compare the performance of different parallel computers. Existing benchmarks tend either to be too architecture-specific, or too high-level. Both problems can result in benchmarks that not only provide insufficient information on the performance characteristics of the computer being tested, but are also difficult to port. New benchmarking approaches are needed for new architectural classes, particularly distributed-memory, message-passing computers. This paper focuses on benchmarking distributed-memory message-passing computers. A synthetic benchmark called CoMet (COmmunication METrics), is presented. CoMet is based …

Graphical Oodb Modeling For Medical Information Standards (Gommis), Jiping Liu

Theses

The graphical representation of database schemata has been a useful tool for the designer and users of database systems. Such a tool for OODB schemata should incorporate a wide variety of symbols which cover most concepts of existing Object-Oriented Database (OODB), so it is sufficient to support a diverse group of object-oriented data models.

In this paper we created a. graphical representation, using the OOdini system and language, of the European Prestandard for Medical Informatics on Message Exchange of Laboratory Information. This European Prestandard describes a standardized format for messages to be exchanged between a. health care provider and a …

Implementation Of An Automatic Mapping Tool For Massively Parallel Computing, Ajitha Gadangi

Theses

In this thesis, an implementation of a generic technique for fine grain mapping of portable parallel algorithms onto multiprocessor architectures is presented. The implemented mapping algorithm is a component of Cluster-M. Cluster-M is a novel parallel programming tool which facilitates the design and mapping of portable softwares onto various parallel systems. The other components of Cluster-M are the Specifications and the Representations. Using the Specifications, machine independent parallel algorithms are presented in a "clustered" fashion specifying the concurrent computations and communications at every step of the overall execution. The Representations, on the other hand, are a form of clustering the …

Concurrent Use Of Two Programming Tools For Heterogeneous Supercomputers, Javier G. Vasquez

Theses

In this thesis, a demostration of the heterogeneous use of two programming paradigms for heterogeneous computing called Cluster-M and HAsC is presented. Both paradigms can efficiently support heterogeneous networks by preserving a level of abstraction which does not include any architecture mapping details. Furthermore, they are both machine independent and hence are scalable. Unlike, almost all existing heterogeneous orchestration tools which are MIMD based, HAsC is based on the fundamental concepts of SIMD associative computing. HAsC models a heterogeneous network as a coarse grained associative computer and is designed to optimize the execution of problems with large ratios of computations …

Authentication For Mobile Computing, Andreas Keppler

Theses

Host mobility is becoming an increasingly important feature with the recent arrival of laptop and palmtop computers, the development of wireless network interfaces and the implementation of global networks. Unfortunately, this mobile environment is also much more vulnerable to penetration by intruders. A possible means of protection can be authentication. This guarantees the identity of a communication peer.

This thesis studies the constraints imposed on the mobile environment with respect to authentication. It compares the two prevailing authentication mechanisms, Kerberos and SPX, and tries to make suggestions of how a mechanism can be adapted to the mobile environment.