Engineering Commons^™

Anserlin. A Broad-Band, Low-Profile, Circularly Polarized Antenna, James L. Drewniak, P. E. Mayes

Electrical and Computer Engineering Faculty Research & Creative Works

A technique is presented for improving the performance of low-profile, circularly polarized (CP) radiating-line antennas. The essential elements of the technique pertain to establishing a single traveling wave on an annular sector of conducting strip that is positioned parallel and close to a large conducting surface. The antenna is named the annular sector, radiating-line (ANSERLIN) antenna. Using this technique, the impedance bandwidth becomes so large that it no longer has any bearing on the operating bandwidth. Instead, the pattern shape and axial ratio become the factors that limit the bandwidth. Both senses of circular polarization can be transmitted or received …

Pump Pulse Effects In Synchronously Pumped Mode-Locked Dye Lasers, Duncan Leo Macfarlane, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

We consider the role of the pump pulse in the output of a synchronously pumped mode-locked dye laser. Our theoretical formalism is a nonlinear dynamical model that includes semiclassical effects, dipole orientation, and intrband relaxation. In particular, we study the shortenting of the output pulse with decreasing pump pulse length and increasing pump level. Both of these predictions agree with experiments.

Spontaneous Coherent Pulsations In Standing-Wave Laser Oscillators: Frequency Characteristics, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

The output signal from a spontaneously pulsing laser must, by definition, consist of more than one frequency component. The experimental and theoretical study of the frequency components'associated with such a laser can provide valuable insights into the pulsation processes. The results of an investigation into the frequency characteristics of a spontaneously pulsing standing-wave laser are reported.

Thermal Performance Monitoring Results From The Residential Standards Demonstration Program, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

The Model Conservation Standards (MCS) were developed by the Northwest Power Planning Council in 1983. These standards were designed to save large amounts of space heating energy in new U.S. residential construction in the Pacific Northwest. Creation of the MCS resulted in a desire to demonstrate the actual savings of such energy efficiency standards. The Bonneville Power Administration sponsored the Residential Standards Demonstration Program (RSDP) in 1984 which resulted in the construction of 410 energy-efficient single-family homes in the four-state region. Typically these buildings incorporated design features such as high levels of insulation for attic, walls and floors, triple-glazed windows …

Numerical Representation Of Bodner Viscoplastic Constitutive Model, Faysal A. Kolkailah, Andrew J. Mcphate

Aerospace Engineering

Nonlinear analyses of structural components are normally carried out by finite element codes making Use of constitutive theories in which the material response is separated into the two important groups of phenomena known as rate‐dependent “creep” and rate‐independent “plasticity.” A number of viscoplastic constitutive theories in which creep and plasticity effects are combined into a unified plastic strain model have recently been proposed and are still undergoing active development. In this paper, the constitutive equations of the Bodner‐Partom model are used to present the time dependent, inelastic properties of Inconel 718 at 650 °C. This representation covers a wide range …

Acuta Enews February 1989, Vol. 18, No. 2

ACUTA Newsletters

In This Issue

President's Message

Party Line

Users Must Join The Standards Fray

Video Classroom

User Groups

Bits & Pieces

Convective Regimes In Reactive Fluid Media Due To The Interaction With Catalytic Surfaces, Hendrik J. Viljoen, Jorge E. Gatica, Vladimir Hlavacek

Papers in Reaction Kinetics

Reactive fluid media enclosed in a cavity with a catalytic surface are analyzed. Nonisothermal chemical reactions on this surface can lead to convective instabilities. A simplified model is developed by using a low-order truncation of a Fourier-type expansion and employing the Galerkin method. A linear stability analysis is presented and it is shown that, under certain conditions, the marginal curve for the onset of oscillatory instabilities can lie below that for monotonic ones. The stability of the convective modes is studied by nonlinear stability analysis and it is shown how they can evolve into periodic and nonperiodic motion patterns. Numerical …

Computing Concrete Pullout Strength, Faruq M. A. Siddiqui, Jan W. Beseler , '88

Engineering Faculty Works

No abstract provided.

Traffic Signing For Local Areas, Herpicc

Indiana Local Technical Assistance Program (LTAP) Publications

One of the most important responsibilities of local street and highway departments is to provide the driving public with adequate, appropriate signs to permit safe travel over unfamiliar roads. Unfortunately, this responsibility is frequently neglected or, at best, under-emphasized. The most common excuse used to justify this neglect is inadequate funding, which is undoubtedly true. What is equally true, however, is that resurfacing roads and streets is more politically popular than re-signing them, even though resurfacing leads to increased speeds, which in turn can lead to increased accident experience on improperly or inadequately signed facilities.

This brief report is not …

Evaluation Of Irrigation Planning Decisions, Derrel L. Martin, James R. Gilley, Raymond J. Supalla

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A method is developed to determine optimal irrigation strategies for a single season using crop production functions which incorporate physically based coefficients. The relationship of yield to evapotranspiration is used to develop the yield-irrigation function. The physical parameters used in the production function can be determined from field measurements or various types of computer simulation. Using this approach, the optimal irrigated area and depth of water to apply can be related to prices, costs, and physical parameters. This produces a more general solution than commonly used production functions that depend on limited experimental results. The optimal irrigation depth and irrigated …

Measured Spectra Of The Hygroscopic Fraction Of Atmospheric Aerosol Particles, Darryl J. Alofs, Donald E. Hagen, Max B. Trueblood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The relation between dry diameter (X₀) and critical supersaturation (S_c) for atmospheric submicron aerosol particles is investigated using a long term air sampling program at Rolla, Missouri. The particles are passed through an electrostatic aerosol size classifier, and then through an isothermal haze chamber. Results are reported in terms of an apparent volume fraction of soluble material, ε_v defined such that for particles composed only of ammonium sulfate and water insoluble compounds, ε_v is the actual volume fraction of soluble material. The probability distribution of ε_v is found to be approximately Gaussian in …

The Greenhouse Effect, Florida Solar Energy Center, Ingrid Melody

FSEC Energy Research Center®

Use of conventional energy sources - in Florida and throughout the world - has produced a global problem known as "the greenhouse effect." While the scientific community does not always agree on the greenhouse effect's potential impacts on the planet, and while policy makers do not always agree on methods to ameliorate or adapt to it, most concur on at least a few points: The greenhouse effect does indeed exist and is primarily a result of our use of carbon-based energy supplies. The greenhouse effect is changing the planet's climate. The greenhouse effect presents circumstances unique in human history - …

The Fracture Toughness Of Ice In Contact With Salt Water, S. A. Sabol, E. M. Schulson

Dartmouth Scholarship

Experiments have established that the fracture toughness of fresh-water, bubbly ice is not affected by the presence of salt water. THIS note considers whether the resistance of ice to fast crack propagation, or the fracture toughness, is affected by water. The question arises because ice frequently breaks in the presence of water (icebergs, ice covers, and salt-water ice which contains brine-filled pores) and because surface energy, which is reduced upon wetting, is the primary barrier (Gold, 1963; Nixon and Schulson, 1987) to fast crack propagation. Earlier work along these Lines (Liu and Miller, 1979) was characterized by scatter and thus …

Theoretical Model For The Images Formed By A Spherical Particle In A Coherent Imaging System: Comparison, Scott Alan Schaub, D. R. Alexander, J. P. Barton

Department of Electrical and Computer Engineering: Faculty Publications

A simple theoretical model is presented that allows calculation of the image produced by a spherical absorbing particle illuminated by monochromatic, coherent laser light. Results presented in this paper are restricted to a singe-lens imaging system, although generalization to more complex imaging system configurations would be straightfoward. The method uses classic Lorenz-Mie scattering theory to obtain the electromagnetic field external to an absorbing spherical particle and a Fourier optics approach to calculate the intensities in the image plane. Experimental results evaluating focus characteristics are examined for 50 um diameter water droplets using an N2 laser imaging system in conjunction with …

A Psychophysical Comparison Of Two Methods For Adaptive Histogram Equalization, John B. Zimmerman, Steve B. Cousins, Mark E. Frisse, Karin M. Hartzell, Michael C. Kahn

All Computer Science and Engineering Research

Adaptive histogram equalization (ahe) is a method for adaptive contrast enhancement of digital images propped by Pizer et. Al.. It has the properties that it is an automatic, reproducible method for the simultaneous viewing of contrast within a digital image with a large dynamic range. Recent experiments have show that in specific cases, there is no significant difference in the ability of ahe and linear intensity windowing to display grey-scale contrast. More recently, Pizer et al. have proposed a variant of ahe which limits the allowed contrast enhancement of the image. The contrast-limited adaptive histogram equalization (clahe) produces images in …

Assessment Of Squirrel-Caused Power Outages, J. Chris Hamilton, Ron J. Johnson, Ronald M. Case, Michael W. Riley

School of Natural Resources: Faculty Publications

Squirrel-caused power outages in Lincoln and Omaha, Nebraska, were evaluated by examining company power outage reports and by consulting with power company representatives. Reports showed that squirrel-caused outages at pole-mounted transformers were most prevalent during May, June, and October (48% of total) and between 1 and 4 h after sunrise (38%), patterns that coincide with squirrel dispersal or morning activity periods. In Lincoln, 1980 and 1981, squirrels caused 177 outages per year, which was 24% of all outages and 90% of animal-caused outages. Estimated minimum annual costs were $23 364 for repairs, public relations, and lost revenue while meters were …

The Planar Singular Solutions Of Stokes And Laplace Equations And Their Application To Transport Processes Near Porous Surfaces, Ashok S. Sangani, S. Behl

Biomedical and Chemical Engineering - All Scholarship

The planar singular solutions of Stokes and Laplace equations are derived and applied to a number of transport problems associated with porous surfaces. The velocity, pressure, concentration, and temperature slip coefficients are determined exactly for the semi-infinite periodic arrays of spheres and these are compared with the predictions of two approximate continuum theories formulated by Brinkman [Appl. Sci. Res. Sect. A I, 27 (1947)] and Chang and Acrivos [J. Appl. Phys. 59, 375 (1986)] to assess the utility of such theories in accurately predicting various overall properties related to the porous surfaces. It is found that in general these theories …

Steel Deck Institute Design Manual For Composite Decks, Form Decks, Roof Decks, And Cellular Deck Floor Systems With Electrical Distribution, Steel Deck Institute

Steel Deck Institute (SDI) Specifications and Manuals (1939 - present)

No abstract provided.

Design Of Automotive Structural Components Using High Strength Sheet Steels The Effect Of Strain Rate On Mechanical Properties Of Sheet Steels, Maher Kassar, Wei-Wen Yu

CCFSS Library (1939 - present)

INTRODUCTION During recent years, automotive manufacturers have produced lighter vehicles for the purpose of achieving fuel economy. To accomplish the construction of such automobiles, high strength sheet steels with various yield strengths up to 190 ksi have been used for auto parts and structural components 1-9. In order to provide some technical assistance for the design of such high strength steels, the first edition of the "Guide for Preliminary Design of Sheet Steel Automotive Structural Components" was issued by American Iron and Steel Institute (AISI) in February 1981. 10 The use of the Guide was discussed by Errera at the …

Review Of Radial Dose Measurement Technique And Data, Matesh N. Varma

United States Department of Energy: Publications

Radial dose is the average energy deposited in a short length of cylindrical shell formed between radii r and r + dr, per unit mass. Here, r is the distance perpendicular to the trajectory of an incident charged particle. Radial dose profiles as a function of radial distance for charged particles have been used to interpret radiobiological data. This article reviews the technique for measuring radial dose distributions and the available data.

Integrating Scheduling And Control Functions In Computer Integrated Manufacturing Using Artificial Intelligence, Luis Carlos Rabelo, Sema E. Alptekin

Industrial and Manufacturing Engineering

Proper integration of scheduling and control in Flexible Manufacturing Systems will make available the required level of decision-making capacity to provide a flexibly-automated, efficient, and quality manufacturing process. To achieve this level of integration, the developments in computer technology and sophisticated techniques of artificial intelligence (AI) should be applied to such FMS functions as scheduling. In this paper, we present an Intelligent Scheduling System for FMS under development that makes use of the integration of two AI technologies. These two AI technologies — Neural Networks and Expert Systems — provide the intelligence that the scheduling function requires in order to …

Cyclic Lateral Loading Of A Large-Scale Pile Group, Shamsher Prakash, K. Sreerama, Sally Prakash

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

No abstract provided.

Symmetric Self-Electro-Optic Effect Device: Optical Set-Reset Latch, Differential Logic Gate, And Differential Modulator/Detector, Anthony L. Lentine, Harvard S. Hinton, David A. B. Miller, Jill E. Henry, J. E. Cunningham, Leo M. F. Chirovsky

Electrical and Computer Engineering Faculty Publications

The symmetric self-electrooptic-effect device (S-SEED), a structure consisting of two p-i-n diodes electrically connected in series and acting as an optically bistable set-reset latch, is discussed. Applications and extensions of this device are also discussed. The devices do not require the critical biasing that is common to most optically bistable devices and thus is more useful for system applications. They have been optically cascaded in a photonic ring counter and have been used to perform different NOR, OR, NAND, and AND logic functions. Using the same device, a differential modulator that generates a set of complementary output beams with a …

Viscous Cross-Waves: An Analytical Treatment, Andrew J. Bernoff, L. P. Kwok, Seth Lichter

All HMC Faculty Publications and Research

Viscous effects on the excitation of cross‐waves in a semi‐infinite box of finite depth and width are considered. A formalism using matched asymptotic expansions and an improved method of computing the solvability condition is used to derive the relative contributions of the free‐surface, sidewall, bottom, and wavemaker viscous boundary layers. This analysis yields an expression for the damping coefficient previously incorporated on heuristic grounds. In addition, three new contributions are found: a viscous detuning of the resonant frequency, a slow spatial variation in the coupling to the progressive wave, and a viscous correction to the wavemaker boundary condition. The wavemaker …

Ua66/9 The Birth Of Engineering Technology, Boyce Tate, Wku Engineering

WKU Administration Documents

A history of Engineering Technology at WKU.

Energetic Electron Tracks And Dna Strand Breaks, A. Chatterjee, W. R. Holley

United States Department of Energy: Publications

A theoretical model with no adjustable parameters is presented to evaluate the strand break yields for incident electrons between 100 eV and 1 MeV. Indirect mechanisms as well as direct mechanisms are included for the production of strand breaks. The model includes the following features: (i) multiple scattering of low energy electrons; (ii) decay of hydroxyl radicals in an aqueous solution containing Tris buffer; (iii) Monte Carlo simulation of the motion of hydroxyl radicals for interaction with the DNA sites; and (iv) stochastic aspects of the direct ionization on the DNA sites and the use of oscillator strength of a …

The Katz Cell-Survival Model And Beams Of Heavy Charged Particles, Stanley B. Curtis

United States Department of Energy: Publications

In this paper, we describe how the Katz cell-survival model has been used to predict survival along the central axis of the dose vs depth curve of beams of heavy charged particles. Unmodified beams with sharp Bragg peaks as well as ridge-filter-modulated beams with spread Bragg peaks have been studied. The analysis in terms of this model leads to the definition of two coefficients, "ion kill" and "gamma kill", which characterize the radiation quality of the beams. In this way, the relative importance of the primary lind secondary (fragmentation) contributions can be assessed easily.

Setting the model parameter m equal …

Physical Aspects Of Charged Particle Track Structure, R. H. Ritchie, R. N. Hamm, J. E. Turner, H. A. Wright, J. C. Ashley, G. J. Banks

United States Department of Energy: Publications

A plasmon generated by a swift charged particle constitutes a coherent excitation about the particle track. We discuss the physics of the plasmon in condensed matter and its effects on electron transport in liquid water. Criteria for the existence of the plasmon III a given substance, Its characteristics when generated by a swift charged particle, its representation in impact parameter space, and its decay into localized excitations are described. We describe how plasmon excitation and decay are implemented in our Monte Carlo code, OREC, and how track structure calculations are affected by this mode.

Subsurface Transport Of Contaminants, John E. Mccarthy, John M. Zachara

United States Department of Energy: Publications

Contaminants originating from human activities have entered the subsurface environment through waste disposal practices, spills, and land application of chemicals. The establishment of effective disposal and isolation procedures for chemical wastes, the protection of public health, and the amelioration of subsurface contamination rely on the ability to predict the velocity at which contaminants move through the vadose (unsaturated) and saturated zones. However, attempts to describe and predict contaminant transport cannot succeed if major pathways and mechanisms for transport are not defined.

Most approaches to describing and predicting the movement of contaminants treat groundwater as a two-phase system in which contaminants …

Generalized Model For The Optical Absorption Edge In A-Si:H, T. Datta, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

We have reanalyzed the published optical absorption coefficient data for a-Si:H and introduced a divergence temperature, a new concept in the physics of these materials.