Physical Sciences and Mathematics Commons^™

Hypertext Theory And Narrative, Eoin Kilfeather

Articles

No abstract provided.

Public Land: How Much Is Enough?, Dale A. Oesterle, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

59 p. ; 29 cm

On Applications Of Excess Level Processes To (N,D)-Policy Bulk Queueing Systems, Jewgeni H. Dshalalow

Mathematics and System Engineering Faculty Publications

The paper deals with queueing systems in which N- and D-policies are combined into one. This means that an idle or vacationing server will resume his service if the queueing or workload process crosses some specified fixed level N or D, respectively. For the proposed (N,D)-policy we study the queueing processes in models with and without server vacations, with compound Poisson input, and with generally distributed service and vacation periods. The analysis of the models is essentially based on fluctuation techniques for two-dimensional marked counting processes newly developed by the author. The results enable us to arrive at stationary distributions …

Exp For Windows, Version 4.0 A Software Review, Donn E. Miller-Harnish

Mathematics and System Engineering Faculty Publications

No abstract provided.

Formation Energies And Energy Levels Of Deep Defects In Narrow-Gap Semiconductors, James D. Patterson, Weigang Li

Aerospace, Physics, and Space Science Faculty Publications

We use a Green's function technique for deep defect energy level calculations in mercury cadmium telluride, mercury zinc telluride, and mercury zinc selenide. The formation energy is calculated from the difference between the total binding energy with an impurity cluster and with a perfect cluster. These alloys are among those that have been experimentally grown in microgravity aboard the Space Shuttle. To evaluate the quality of these crystals, it is necessary to characterize them, and one important aspect of this characterization is the study of deep defects which can limit carrier lifetime. Relaxation effects are calculated with molecular dynamics. The …

Behavior-Based Analogy-Making, Doug Blank

Computer Science Faculty Research and Scholarship

No abstract provided.

Analogy-Making: A Connectionist Exploration, Doug Blank

Computer Science Faculty Research and Scholarship

No abstract provided.

A Simple Model For Nonequilibrium Fluctuations In A Fluid, Alejandro Garcia, F. Baras, M. Malek Mansour

Faculty Publications

Presents a train model that shows the long-range spatial correlations of fluctuations in nonequilibrium fluid systems. Illustration of model through analysis of flat-car trains running on parallel tracks; Simulation of train model in computers; Theoretical analysis for fluctuations in the train model; Relationship between train model and the fluctuating hydrodynamic theory of fluids.

A Study Of The Development Of Mathematical Problem Solving In Relation To Cognitive Development, Margaret Cooper

Honors Theses, 1963-2015

No abstract provided.

A Library-Based Approach To Task Parallelism In A Data-Parallel Language, Ian Foster, David R. Kohr, Rakesh Krishnaiyer, Alok Choudhary

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

The data-parallel language High Performance Fortran (HPF) does not allow efficient expression of mixed task/data-parallel computations or the coupling of separately compiled data-parallel modules. In this paper, we show how these common parallel program structures can be represented, with only minor extensions to the HPF model, by using a coordination library based on the Message Passing Interface (MPI). This library allows data-parallel tasks to exchange distributed data structures using calls to simple communication functions. We present microbenchmark results that characterize the performance of this library and that quantify the impact of optimizations that allow reuse of communication schedules in common …

Array Decompositions For Nonuniform Computational Environments, Maher Kaddoura, Sanjay Ranka, Albert Wang

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

Two-dimensional arrays are useful in a large variety of scientific and engineering applications. Parallelization of these applications requires the decomposition of array elements among different machines. Several data-decomposition techniques have been studied in the literature for machines with uniform computational power. In this paper we develop new methods for decomposing arrays into a cluster of machines with nonuniform computational power. Simulation results show that our methods provide superior decomposition over naive schemes.

Hierarchical Growing Cell Structures, Vanco Burzevski, Chilukuri K. Mohan

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

We propose a hierarchical self-organizing neural network ("HiGS") with adaptive architecture and simple topological organization. This network combines features of Fritzke's Growing Cell Structures and traditional hierarchical clustering algorithms. The height and width of the tree structure depend on the user-specified level of error desired, and the weights in upper layers of the network do not change in later phases of the learning algorithm. Parameters such as node deletion rate are adaptively modified by the learning algorithm.

A Unified Tiling Approach For Out-Of-Core Computations, Rajesh Bordawekar, Alok Choudhary, J. Ramanujam, Mahmut Kandemir

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

This paper describes a framework by which an out-of-core stencil program written in a data-parallel language can be translated into node programs in a distributed-memory message-passing machine with explicit I/O and communication. We focus on a technique called Data Space Tiling to group data elements into slabs that can fit into memories of processors. Methods to choose legal tile shapes under several constraints and deadlock-free scheduling of tiles are investigated. Our approach is unified in the sense that it can be applied to both FORALL loops and the loops that involve flow-dependences.

Shape Recognition Using Genetic Algorithms, Ender Ozcan, Chilukuri K. Mohan

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

Shape recognition is a challenging task when shapes overlap, forming noisy, occluded, partial shapes. This paper uses a genetic algorithm for matching input shapes with model shapes described in terms of features such as line segments and angles (extracted using traditional algorithms). The quality of matching is gauged using a measure derived from attributed shape grammars [12, 13]. Preliminary results, using shapes with about 30 features each, are extremely encouraging.

Characterization Of A Class Of Sigmoid Functions With Applications To Neural Networks, Anil Ravindran Menon, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

Sigmoid functions, whose graphs are “S-shaped” curves, appear in a great variety of contexts, such as the transfer functions in many neural networks. Their ubiquity is no accident; these curves are among the simplest non-linear curves, striking a graceful balance between linear and non-linear behavior. .. This paper undertakes a study of two classes of sigmoids: the simple sigmoids, defined to be odd, asymptotically bounded, completely monotone functions in one variable, and the Hyperbolic sigmoids, a proper subset of simple sigmoids and a natural generalization of the hyperbolic tangent. The class of hyperbolic sigmoids includes a surprising number of well …

Unsupervised Algorithms For Learning Emergent Spatio-Temporal Correlations, Chaitanya Tumuluri

Electrical Engineering and Computer Science - Technical Reports

Many applications require the extraction of spatiotemporal correlations among dynamically emergent features of non-stationary distributions. In such applications it is not possible to obtain an a priori analytical characterization of the emergent distribution. This paper extends the Growing Cell Structures (GCS) network and presents two novel (GIST and GEST) networks, which combine unsupervised feature-extraction and Hebbian learning, for tracking such emergent correlations. The networks were successfully tested on the challenging Data Mapping problem, using an execution driven simulation of their implementation in hardware. The results of the simulations show the successful use of the GIST and GEST networks for extracting …

Benchmarking The Computation And Communication Performance Of The Cm-5, Kivanc Dincer, Zeki Bozkus, Sanjay Ranka, Geoffrey C. Fox

Northeast Parallel Architecture Center

Thinking Machines' CM-5 machine is a distributed-memory, message-passing computer. In this paper we devise a performance benchmark for the base and vector units and the data communication networks of the CM-5 machine. We model the communication characteristics such as communication latency and bandwidths of point-to-point and global communication primitives. We show, on a simple Gaussian elimination code, that an accurate static performance estimation of parallel algorithms is possible by using those basic machine properties connected with computation, vectorization, communication, and synchronization. Furthermore, we describe the embedding of meshes or hypercubes on the CM-5 fat-tree topology and illustrate the performance results …

An Extended Two-Phase Method For Accessing Sections Of Out-Of-Core Arrays, Rajeev Thakur, Alok Choudhary

Electrical Engineering and Computer Science - All Scholarship

A number of applications on parallel computers deal with very large data sets that cannot fit in the main memory. In such applications, data must be stored in files on disks and fetched into memory during program execution. Parallel programs with large out-of-core arrays stored in files must read/write smaller sections of the arrays from/to files. In this paper, we describe a method for accessing sections of out-of-core arrays efficiently. Our method, the extended two phase method, uses collective I/O: Processors cooperate to combine several I/O requests into fewer larger granularity requests, reorder requests so that the file is accessed …

Efficient Algorithms For Array Redistribution, Rajeev Thakur, Alok Choudhary, J. Ramanujam

Electrical Engineering and Computer Science - All Scholarship

Dynamic redistribution of arrays is required very often in programs on distributed memory parallel computers. This paper presents efficient algorithms for redistribution between different cyclic(k) distributions, as defined in High Performance Fortran. We first propose special optimized algorithms for a cyclic(x) to cyclic(y) redistribution when x is a multiple of y, or y is a multiple of x. We then propose two algorithms, called the GCD method and the LCM method, for the general cyclic(x) to cyclic(y) redistribution when there is no particular relation between x and y. We have implemented these algorithms on the Intel Touchstone Delta, and find …

The Isomorphism Conjecture Fails Relative To A Random Oracle, Stuart A. Kurtz, Stephen R. Mahaney, James S. Royer

Electrical Engineering and Computer Science - All Scholarship

Berman and Hartmanis [BH77] conjectured that there is a polynomialtime computable isomorphism between any two languages complete for NP with respect to polynomial-time computable many-one (Karp) reductions. Joseph and Young [JY85] gave a structural definition of a class of NP-complete sets---the k-creative sets---and defined a class of sets (the K k f 's) that are necessarily k-creative. They went on to conjecture that certain of these K k f 's are not isomorphic to the standard NP-complete sets. Clearly, the Berman--Hartmanis and Joseph--Young conjectures cannot both be correct. We introduce a family of strong one-way functions, the scrambling functions. If …

Every Polynomial-Time 1-Degree Collapses Iff P = Pspace, Stephen A. Fenner, Stuart A. Kurtz, James S. Royer

Electrical Engineering and Computer Science - All Scholarship

A set A is m-reducible (or Karp-reducible) to B iff there is a polynomial-time computable function f such that, for all x, x ∈ A <--> f (x) ∈ B. Two sets are: (a) 1-equivalent iff each is m-reducible to the other by one-one reductions; (b) p-invertible equivalent iff each is m-reducible to the other by one-one, polynomial-time invertible reductions; and (c) p-isomorphic iff there is an m-reduction from one set to the other that is one-one, onto, and polynomial-time invertible. In this paper we show the following characterization. Theorem : The following are equivalent: (a) P = PSPACE. (b) Every …

Compile-Time Performance Prediction Of Hpf/Fortran 90d, Manish Parashar, Salim Hariri

Electrical Engineering and Computer Science - All Scholarship

In this paper we present an interpretive approach for accurate and cost-effective performance prediction in a high performance computing environment, and describe the design of a compile-time HPF/Fortran 90D performance prediction framework based on this approach. The performance prediction framework has been implemented as a part of the HPF/Fortran 90D application development environment that integrates it with a HPF/Fortran 90D compiler and a functional interpreter. The current implementation of the environment framework is targeted to the iPSC/860 hypercube multicomputer system. A set of benchmarking kernels and application codes have been used to validate the accuracy, utility, and usability of the …

Hierarchical Control Flow Graph Models, Douglas G. Fritz, Robert G. Sargent

Electrical Engineering and Computer Science - All Scholarship

Hierarchical Control Flow Graph Models define a modeling paradigm for discrete event simulation modeling based upon hierarchical extensions to Control Flow Graph Models. Conceptually, models consist of a set of encapsulated, concurrently operating model components that interact solely via message passing. The primary objectives of Hierarchical Control Flow Graph Models are: (1) to facilitate model development by making it easier to develop, maintain, and reuse models and model elements, and (2) to support the flexible and efficient execution of models. Hierarchical Control Flow Graph Models use two complementary types of hierarchical model specification structures, one to specify components and their …

Spieltheorie, Alexander Chocholaty, Pascal Hitzler

Computer Science and Engineering Faculty Publications

No abstract provided.

Hydrogeology, Hydrogeochemistry, And Spoil Settlement At A Large Mine-Spoil Area In Eastern Kentucky: Star Fire Tract, David R. Wunsch, James S. Dinger, Page B. Taylor, Daniel I. Carey, C. Douglas R. Graham

Report of Investigations--KGS

An applied research program at the Star Fire surface mine in eastern Kentucky, owned and operated by Cypress-AMAX Coal Co., defined spoil characteristics to develop and monitor water resources, which will help identify a reliable water supply for future property development. Water stored in the mine spoil may provide a usable ground-water supply, and the spoil could also be engineered to provide base flow to surfacewater reservoirs.

Ground-water recharge enters the spoil by way of sinking streams, ground-water flow from bedrock in contact with the mine spoil, and a specially designed infiltration basin. Ground water discharges predominantly from springs and …

Compositional Reasoning Is Not Possible In Determining The Solvability Of Consensus, Prasad Jayanti

Computer Science Technical Reports

Consensus, which requires processes with different input values to eventually agree on one of these values, is a fundamental problem in fault-tolerant computing. We study this problem in the context of asynchronous shared-memory systems. In our model, shared-memory consists of a sequence of cells and supports a specific set of operations. Prior research on consensus focussed on its solvability in shared-memories supporting specific operations. In this paper, we investigate the following general question: Let OP1 and OP2 be any two sets of operations such that each set includes read and write operations. Suppose there is no consensus protocol for N …

Front Matter

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

Back Cover

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

Editorial Board & Iowa Academy Of Science Officers And Directors

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

Checklist Of Instructions For Authors

Journal of the Iowa Academy of Science: JIAS

No abstract provided.