Engineering Commons^™

Packet Routing In Networks With Long Wires, Ronald I. Greenberg, H.-C. Oh

Computer Science: Faculty Publications and Other Works

In this paper, we examine the packet routing problem for networks with wires of differing length. We consider this problem in a network independent context, in which routing time is expressed in terms of “congestion” and “dilation” measures for a set of packet paths. We give, for any constant ε > 0, a randomized on-line algorithm for routing any set of N packets in O((Clg^ε(Nd)+Dlg(Nd))/lglg(Nd)) time, where C is the maximum congestion and D is the length of the longest path, both taking wire delays into account, and d is the longest path in terms of number of wires. We also …

Interaction Of Profiled Light With Contrapropagating Acoustic Waves: Fourier Transform Approach, Partha P. Banerjee, Chen-Wen Tarn, Jaw-Jueh Liu

Electrical and Computer Engineering Faculty Publications

A straightforward Fourier-transform approach is employed to investigate acousto-optic interaction between an input optical beam with arbitrary profile and contrapropagating cw sound in the Bragg regime. The process can be analyzed in terms of the simultaneous scattering of light by the two sound waves in the interaction region. Analytic expressions for the equivalent transfer functions are obtained and the scattered light profiles are plotted.

The Effect Of Additives On The Nucleation And Growth Of Copper Onto Stainless Steel Cathodes, M. Sun, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

A potentiostatic technique has been used to study the effects of chloride ion, glue, and thiourea on the initial electrodeposition of copper. A stainless steel (AISI 304) rotating disc electrode (RDE) with an electrolyte containing 40 g/1 Cu²⁺ and 180 g/1 H₂SO₄ at 40 °C was employed. The current transients from the potential step measurements for the additive-free electrolyte could be fitted to a model that assumed progressive nucleation followed by growth of three-dimensional (3-D) centers under diffusion control. The growth mechanism and the type of nuclei were also confirmed by scanning electron microscopy (SEM) of …

Interval Estimation And Monte Carlo Simulation Of Digital Communication Systems, Kurt Louis Kosbar, T. F. Chang

Electrical and Computer Engineering Faculty Research & Creative Works

This work quantifies the accuracy of bit error rate (BER) estimates produced by Monte Carlo simulations by carefully applying confidence interval estimation techniques. Due to numerical difficulties, some previous work in this area has assumed that the BER statistic possessed a Gaussian distribution. This work demonstrates that in some important regions the estimate is decidedly non-Gaussian, and application of central limit theorem arguments can result in errors in excess of an order of magnitude. This work investigates the accuracy of common approximations and the feasibility of exact calculation of confidence intervals, and presents a novel polynomial class approximation. By combining …

Object-Oriented Modeling Of Communication Systems, Kurt Louis Kosbar, Kevin W. Schneider

Electrical and Computer Engineering Faculty Research & Creative Works

Conventional communication system simulation programs and packages are written using procedural programming languages. Newly developed, object-oriented languages offer the simulation designer significantly different options and structures. By exploiting these new techniques it is possible to significantly increase the flexibility and extensibility of the simulation package. This allows the system analyst to efficiently re-use complex simulation code and quickly and reliably reconfigure the simulation. In addition, a single object-oriented simulation can be used in all stages of the design process, from conceptual design through fabrication and testing. A final benefit of the object-oriented techniques is that the simulation code closely matches …

Conservative Confidence Intervals Of Importance Sampling Estimates, Kurt Louis Kosbar, T. F. Chang

Electrical and Computer Engineering Faculty Research & Creative Works

Confidence intervals (CI) are used to gauge the accuracy of bit error rate (BER) estimates produced by Monte Carlo (MC) simulations. This work attempts to objectively evaluate the performance of Important Sampling (IS) simulations by applying the same statistical analysis tool. While it is not possible to evaluate the minimum size CI for arbitrary IS estimates, it is possible to over-bound the interval using a technique called conservative confidence interval (CCI) estimation. This bounding procedure is applied to a simple IS biasing technique. While the IS estimate may be superior to the MC estimate, the CCI fails to support this …

Axial Load Capacity Of Sheeted Cold-Formed C And Z Members, Neil J. Glaser, Richard C. Kaehler, James M. Fisher

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.

Repetition Frequency Stabilisation Of Passively Mode-Locked Semiconductor Lasers, R. J. Helkey, Dennis J. Derickson, A. Mar, J. G. Wasserbauer, J. E. Bowers, R. L. Thornton

Electrical Engineering

The repetition frequency of an external cavity mode-locked GaAs semiconductor diode laser has been stabilized by voltage controlled electrical feedback. The phase noise has been reduced by 40dB at 1 kHz offset from the carrier and timing jitter reduced from more than 30ps to 4ps. This technique can be used to stabilize millimetre-wave mode-locked lasers.

Separating Structure From Function In The Specification And Design Of Distributed Systems, Kenneth J. Goldman

All Computer Science and Engineering Research

A distributed system is viewed as a collection of functional components and a unifying structure that defines relationships among the components. In the paper, we advocate a particular approach to distributed system specification and design in which the structure of a distributed system is specified separately from the functional components. This permits one to reason about individual functional components in isolation, and encourages one to make explicit not only the input/output behavior of the functional components but also the logical placement of these components within the overall structure of the system. We describe a new software tool for the specification, …

Mode-Locking Of High-Power Resonant-Optical-Waveguide Diode Laser Arrays, Alan Mar, Dennis J. Derickson, Roger Helkey, John Bowers, Dan Botez

Electrical Engineering

We report the first mode-locked operation of a resonant optical waveguide (ROW semiconductor laser array. Pulsewidths as short as 23 ps and peak powers of over 1W are generated in a single-lobed beam.

Supercomputer-Based Spherical Scene Projector, Harold K. Brown, John G. Madry, Rufus H. Cofer, Samuel Peter Kozaitis

Electrical Engineering and Computer Science Faculty Publications

A multi-technology high performance computing system based on the Open Parallel Architecture Design Specification (OPADS) platform is being evaluated for use as a graphics engine for spherical scene projection. This system is designed to make available the massive quantities of real-time processing power needed to support complete real time scene generation and projection of complex dynamical maneuvers for applications such as scientific visualization and three dimensional database creation and interaction. A comparison is also provided between head mounted projection systems and walk-in spherical scene projection systems.

Bayesian Defeat Of Camouflage, Rufus H. Cofer

Electrical Engineering and Computer Science Faculty Publications

A new technique is shown for refining and reducing incoming camouflage data based upon the Bayesian paradigm. Innovation is displayed in use of a statistical conditioning sequence that avoids the need to form target features from the data. The result is a simplified and more accurate probabilistic indication of actual target presence. This probabilistic indication can then be incorporated into a variety of target detection scenarios or, alternately, to form the basis of a theoretically optimal Bayesian target detector. Numeric simulation is presented to show the effectiveness of the technique against simulated camouflage

Notice Of Meetings For Museum Committee In 1992, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

No abstract provided.

A New Preloaded Beam Geometric Stiffness Matrix With Full Rigid Body Capabilities, Paul A. Bosela, D. G. Fertis, F. J. Shaker

Civil and Environmental Engineering Faculty Publications

Space structures, such as the Space Station solar arrays, must be extremely light-weight, flexible structures. Accurate prediction of the natural frequencies and mode shapes is essential for determining the structural adequacy of components, and designing a controls system. The tension pre-load in the 'blanket' of photovoltaic solar collectors, and the free/free boundary conditions of a structure in space, causes serious reservations on the use of standard finite element techniques of solution. In particular, a phenomenon known as 'grounding, or false stiffening, of the stiffness matrix occurs during rigid body rotation. The authors have previously shown that the grounding phenomenon is …

Grounding Of Space Structures, Paul A. Bosela, D. G. Fertis, F. J. Shaker

Civil and Environmental Engineering Faculty Publications

Space structures, such as the Space Station solar arrays, must be extremely light-weight, flexible structures. Accurate prediction of the natural frequencies and mode shapes is essential for determining the structural adequacy of components, and designing a controls system. The tension pre-load in the 'blanket' of photovoltaic solar collectors, and the free/free boundary conditions of a structure in space, causes serious reservations on the use of standard finite element techniques of solution. In particular, a phenomenon known as 'grounding', or false stiffening, of the stiffness matrix occurs during rigid body rotation. This paper examines the grounding phenomenon in detail. Numerous stiffness …

Explanation Mode For Bayesian Automatic Object Recognition, Thomas L. Hazlett, Rufus H. Cofer, Harold K. Brown

Electrical Engineering and Computer Science Faculty Publications

One of the more useful techniques to emerge from AI is the provision of an explanation modality used by the researcher to understand and subsequently tune the reasoning of an expert system. Such a capability, missing in the arena of statistical object recognition, is not that difficult to provide. Long standing results show that the paradigm of Bayesian object recognition is truly optimal in a minimum probability of error sense. To a large degree, the Bayesian paradigm achieves optimality through adroit fusion of a wide range of lower informational data sources to give a higher quality decision - a very …

Automatic Recognition Of Tool Wear On A Face Mill Using A Mechanistic Modeling Approach, Daniel Waldorf, Shiv G. Kapoor, Richard E. Devor

Industrial and Manufacturing Engineering

A strategy is developed for identifying cutting tool wear on a face mill by automatically recognizing wear patterns in the cutting force signal. The strategy uses a mechanistic model development to predict forces on a lathe under conditions of wear and extends that model to account for the multiple inserts of a face mill. The extended wear model is then verified through experimentation over the life of the inserts. The predicted force signals are employed to train linear discriminant functions to identify the wear state of the process in a manner suitable for on-line application.

The Management Of Replicated Data, Hsueh-Chi Shih, C. Y. Ho, S. Alptekin

Computer Science Technical Reports

Data replication, which has the benefits of improving system availability and read performance, proved to be indispensable to many database applications. In a replicated database, the one-copy serializability of transaction executions can be ensured by employing a replica control mechanism on top of the traditional concurrency control mechanism. This work contains two replica control algorithms and a read-only transaction processing algorithm. Both replica control algorithms handle multiple site, communication and partitioning failures. The replica control algorithms achieve read operation efficiency by always translating a logical read operation into one local physical read operation and by taking advantage of the locality …

Diffraction In The Binary Encounter Electron Peak Observed In Collisions Of 0.6 Mev Amu⁻¹ I7+, I23+ And Au11+ Projectiles With He And Ar, W. Wolff, J. L. Shinpaugh, H. E. Wolff, Ronald E. Olson, Jee-Ching Wang, S. Lencinas, D. Piscevic, R. Herrmann, H. Schmidt-Böcking

Physics Faculty Research & Creative Works

Relative double differential cross sections for electron emission from collisions of 0.6 MeV amu^-1I⁷⁺and I²³⁺ projectiles with Ar and Au¹¹⁺projectiles with He were measured for electron energies from 100 eV to 2000 eV and for angles from 0° to 50°. Experimentally observed sudden shifts of the position of the binary encounter peak were interpreted as resulting from quantum interference in the scattering of target electrons from the partially stripped projectile ion. To this end calculations for the elastic scattering of free electrons initially at rest in the laboratory reference frame from the screened …

Methanotrophic Bacteria For Nutrient Removal From Wastewater: Attached Film System, William J. Jewell, Yarrow M. Nelson, Mark S. Wilson

Civil and Environmental Engineering

It was hypothesized that nutrient removal from wastewater could be achieved by using methane oxidizing bacteria (methanotrophs). Because methane is inexpensive. it can be used as an energy source to encourage bacterial growth to assimilate nitrogen and phosphorus and other trace elements. This initial feasibility study used synthetic nutrient mixtures and secondary sewage effluent as feed to a laboratory-scale methanotrophic attached-film expanded bed (MAFEB) reactor operated at 35°C and 20°C. The MAFEB system operated successfully at low nutrient concentrations under a variety of nutrient-limited conditions. Using a synthetic nutrient mixture with a nitrogen:phosphorus feed ratio (w/w) …

On The Creep Deformation Of A Cast Near Gamma Tial Alloy Ti-48al-1nb, R. W. Hayes, B. London

Materials Engineering

The steady-state creep deformation behavior of a cast two phase gamma TiAl alloy having the composition Ti---48Al---1Nb (at.%) has been studied. Tension creep tests using the stress increment technique (θθ2θ3) were conducted over the temperature range of 704–850°C at constant initial applied stress level of 103.4–241.3 MPa. The activation energy for creep over the temperature and stress regime of this study varied 317.5 kJ/mol (137.8 MPa) up to 341.0 kJ/mol (206.8 MPa) with an average value of 326.4 kJ/mol. This is well within the range of values previously measured for gamma TiAl alloys where creep controlled by volume diffusion has …

The Calendar - September 1992, Nova University

The Calendar

No abstract provided.

Acuta Enews Septmber 1992, Vol. 21, No. 9

ACUTA Newsletters

In This Issue

Merging technologies to compete

President's column

Award, election winners

Innovation spurs productivity

Conference evaluations

Welcome to new members

Field Calibration Of A Transient Model For Broiler Misting, Richard S. Gates, Douglas G. Overhults, Robert W. Bottcher, Shu Hui Zhang

Biosystems and Agricultural Engineering Faculty Publications

A transient model to predict temperature within a tunnel ventilated broiler house during misting is developed. The model is calibrated with field data to obtain steady-state constants; transient predictions are compared to measured temperatures during cyclic misting for two different size birds. Measured temperatures during cyclic misting are shown to swing between steady-state asymptotes predicted from the model. Transient response of the model was faster than measured temperature data, in part due to temperature sensor dynamic response. The model predicts the length-wise temperature profile within the building during misting, and can be used to investigate alternate misting strategies and designs. …

1992 Safety Belt Usage Survey And Evaluation Of Effectiveness In Kentucky, Kenneth R. Agent

Kentucky Transportation Center Research Report

The objective of the survey was to establish 1992 safety belt and child safety seat usage rates in Kentucky. Data were collected at 100 sites and combined based on vehicle miles travelled for a given type of highway, rural or urban location, and county population category. Also included in this report is an analysis of accident records evaluating the effectiveness of safety belts.

Statewide usage rates were 41 percent for drivers and front-seat passengers (over 19 years of age) and 62 percent for children under four years of age (front and rear seats). Driver usage rates increased in 1992 compared …

Analysis Of Traffic Accident Data In Kentucky (1987-1991), Kenneth R. Agent, Jerry G. Pigman

Kentucky Transportation Center Research Report

This report includes an analysis of traffic accident data in Kentucky tor the years of 1987-1991. A primary objective of this study was to determine average accident statistics for Kentucky highways. Average and critical number and rates of accidents were calculated for various types of highways in rural and urban areas. These data can be used in Kentucky's procedure to identify locations that have abnormal rates or numbers of accidents.

Another objective of this study was to provide data which can be used in the preparation of the problem identification portion of Kentucky's Annual Highway Safety Plan. County and city …

Heterogeneity Of Intergranular Damage In Copper Crept In Plane-Strain Tension, Brent L. Adams, David P. Field

Faculty Publications

The authors wish to acknowledge support of this work by the Office of Basic Energy Sciences of the U. S. Department of Energy. An interface damage function (IDF), which statistically describes the area fraction of interface damage as a function of up to eight parameters defining crystallite interfaces, was determined for commercial purity copper specimens crept in plane strain tension. The IDF was determined from stereological parameters measured on plane sections cut through damaged specimens. The eight-dimensional space of the function was investigated by analyzing two-dimensional projections of the complete domain. Certain special interfaces were observed to damage preferentially. A …

Implementation Of Back-Propagation Neural Networks With Matlab, Jamshid Nazari, Okan K. Ersoy

Department of Electrical and Computer Engineering Technical Reports

The artificial neural network back propagation algorithm is implemented in Matlab language. This implementation is compared with several other software packages. The effect of reducing the number of iterations in the performance of the algorithm iai studied. The speed of the back propagation program, mkckpmp, written in Matlab language is compared with the speed of several other back propagation programs which are written in the C language. The speed of the Matlab program mbackpmp is, also compared with the C program quickpmp which is a variant of the back propagation algorithm. It is shown that the Matlab program mbackpmp is …

Minimum Separation For Single-Layer Channel Routing, Ronald I. Greenberg, F. Miller Maley

Computer Science: Faculty Publications and Other Works

We present a linear-time algorithm for determining the minimum height of a single-layer routing channel. The algorithm handles single-sided connections and multiterminal nets. It yields a simple routability test for single-layer switchboxes, correcting an error in the literature.

Product Distributions In The Co2-Nh3-H2o System From Liquid Conductivity Measurements, James E. Pelkie, P. John Concannon, David B. Manley, Bruce E. Poling

Chemical and Biochemical Engineering Faculty Research & Creative Works

The objective of this work was to illustrate how liquid conductivity measurements could be used to provide information about the extent of ionization and the amounts of the various ionic products that are formed in the liquid phase in the CO₂-NH₃-H₂O system. To accomplish this, pressures and liquid-phase conductivities for the CO₂-NH₃-H₂O system were measured at 25 °C and over a range of pressures and concentrations. In order to acquire the desired information from bulk conductivity measurements, calibration curves were established from measurements with several potassium salts. These …