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1994

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Articles 451 - 480 of 484

Full-Text Articles in Engineering

Buckling Of A Coating Bonded To A Round Bar Subjected To Axial Extension. Mech. Mater. 15 (1993) 131-138, C. W. Bert, Victor Birman Jan 1994

Buckling Of A Coating Bonded To A Round Bar Subjected To Axial Extension. Mech. Mater. 15 (1993) 131-138, C. W. Bert, Victor Birman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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On The Interface Stability Of A Neck Propagating In A Sheet Reinforced With Shape-Memory Fibers, C. Q. Ru, R. C. Batra Jan 1994

On The Interface Stability Of A Neck Propagating In A Sheet Reinforced With Shape-Memory Fibers, C. Q. Ru, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We propose a simple model of necking in a sheet reinforced with straight fibers made of a shape-memory alloy and examine conditions under which the interface between the necked and the unnecked region is morphologically stable. We use the Mullins and Sekerka (1963, J. Appl. Phys. 34, 323-330; 1964, J. Appl. Phys. 35, 444-450) method, established for studying the stability of a moving interface in a solidification problem, to investigate the interface stability of a propagating neck. It is found that the moving straight interface is morphologically stable for several typical cases even in the absence of surface-tension effects, and …

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On The Propagation Of A Shear Band In A Steel Tube, R. C. Batra, Xiangtong Zhang Jan 1994

On The Propagation Of A Shear Band In A Steel Tube, R. C. Batra, Xiangtong Zhang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Marchand and Duffy tested thin-walled steel tubes in a split Hopkinson torsion bar at a nominal strain-rate of approximately 1600/s and could not determine conclusively whether a shear band initiating at a point in the tube propagated around the circumference in one direction or in both directions. They estimated the speed of propagation to be 520 m/s in the former case and 260 m/s in the latter. Here we simulate their test numerically and find that the shear band propagates in both directions around the circumference of the tube. When the tube is twisted at a nominal strain-rate of 5000/s, …

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Threshold Characteristics Of Multimode Semiconductor Lasers, Lee W. Casperson, Mehdi Khoshnevissan Jan 1994

Threshold Characteristics Of Multimode Semiconductor Lasers, Lee W. Casperson, Mehdi Khoshnevissan

Electrical and Computer Engineering Faculty Publications and Presentations

The effects of spontaneous emission on the threshold characteristics of multimode laser oscillators with mixed line broadening are considered in detail. Most previous studies of multimode laser operation have emphasized the two limits of homogeneous and inhomogeneous broadening. With homogeneous broadening there is a tendency for oscillation in a single longitudinal mode, while in the inhomogeneous limit oscillation over much of the gain spectrum is expected. All practical lasers are somewhere between these limits, and this study explores the mode characteristics of lasers with mixed line broadening. Special attention is given to the important practical case of semiconductor diode lasers, …

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Fabrication Of 2-2 Connectivity Pzt/Thermoplastic Composites For High Frequency Linear Arrays, Wayne Huebner, Mary R. Reidmeyer, L. Busse, Jeffry W. Stevenson Jan 1994

Fabrication Of 2-2 Connectivity Pzt/Thermoplastic Composites For High Frequency Linear Arrays, Wayne Huebner, Mary R. Reidmeyer, L. Busse, Jeffry W. Stevenson

Materials Science and Engineering Faculty Research & Creative Works

An alternate approach for fabricating PZT/polymer composites with 2-2 connectivity with fine scales is described. Thin (less than or equal to 20 micrometers) sintered PZT plates and sheets of a thermoplastic polymer film (less than or equal to 10 micrometers) were bonded together via thermal processing. Stack sintering of tape cast PZT generated the necessary PZT plates, while tape cast polymers were used to control the thermoplastic thickness. Composite blocks were cut to required dimensions for linear arrays, electroded, and poled. Electromechanical properties were measured to evaluate the composites. The significance of this fabrication technique is that it is able …

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Processing And Characterization Of Samarium And Manganese Modified Lead Titanate Thin Film, Chen-Lung Fan, Wayne Huebner Jan 1994

Processing And Characterization Of Samarium And Manganese Modified Lead Titanate Thin Film, Chen-Lung Fan, Wayne Huebner

Materials Science and Engineering Faculty Research & Creative Works

Samarium and manganese modified lead titanate thin films were fabricated by spin-coating an amorphous citrate precursor. These films transformed into an oxide film upon heat treatment at 400 degrees Celcius or above. Relatively large area and crack-free thin films could be obtained by this process both easily and inexpensively. The rheological behavior of the precursor solution, as well as its thermal decomposition and phase development were studied by means of DSC/TGA and XRD. The thickness and grain size of the oxide film were examined by TEM and SEM.

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Data-Feedthrough Faults In Circuits Using Unclocked Storage Elements, Waleed K. Al-Assadi, D. Lu, A. P. Jayasumana, Y. K. Malaiya, C. Q. Tong Jan 1994

Data-Feedthrough Faults In Circuits Using Unclocked Storage Elements, Waleed K. Al-Assadi, D. Lu, A. P. Jayasumana, Y. K. Malaiya, C. Q. Tong

Electrical and Computer Engineering Faculty Research & Creative Works

Some faults in storage elements (SEs) do not manifest as stuck-at-0/1 faults. These include data-feedthrough faults that cause the SE cell to exhibit combinational behaviour. The authors investigate the implications of such faults on the behaviour of circuits using unclocked SEs. It is shown that effects of data-feedthrough faults at the behavioural level are different from those due to stuck-at faults, and therefore tests generated for the latter may be inadequate

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Microwave Diagnosis Of Rubber Compounds, Stoyan I. Ganchev, J. Bhattacharyya, Sasan Bakhtiari, Nasser N. Qaddoumi, Deborah Brandenburg, R. Zoughi Jan 1994

Microwave Diagnosis Of Rubber Compounds, Stoyan I. Ganchev, J. Bhattacharyya, Sasan Bakhtiari, Nasser N. Qaddoumi, Deborah Brandenburg, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

The results of a study investigating the dielectric properties of rubber compounds and their constituents in the frequency range of 5 to 24 GHz are presented. A completely filled short circuited waveguide technique was used to conduct these dielectric measurements. The influence of carbon black content in rubber was investigated for carefully prepared rubber samples. The results showed that for all frequencies, the dielectric constant increases as a function of increasing carbon black content. The variation of dielectric constant values decreases as frequency increases. The presence of curatives in uncured rubber samples was also detected, which indicates the sensitivity of …

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A Modular Approach To Numerical Em Modeling, Todd H. Hubing Jan 1994

A Modular Approach To Numerical Em Modeling, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

Discusses the components of numerical EM modelling codes. The authors go on to discuss a modular approach to EM software development which would allow developers to focus on one component at a time. The modular approach relies on standard format input and output files for each component (or module) of the code

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Structural Properties Of Mixtures Of Highly Asymmetrical Electrolytes And Uncharged Particles Using The Hypernetted Chain Approximation, Daniel Forciniti, Carol K. Hall Jan 1994

Structural Properties Of Mixtures Of Highly Asymmetrical Electrolytes And Uncharged Particles Using The Hypernetted Chain Approximation, Daniel Forciniti, Carol K. Hall

Chemical and Biochemical Engineering Faculty Research & Creative Works

We have solved the Ornstein-Zernike equation in the hypernetted chain (HNC) approximation for several mixtures of electrolytes and uncharged hard spheres. The mixtures that we studied range from a simple restricted primitive model plus hard spheres of the same size to highly asymmetric electrolytes plus hard spheres of different sizes. We monitored the radial distribution function and thermodynamic properties. We find that the presence of neutral particles changes the nature of the interaction between the charged particles. We also find a strong correlation between nonelectrostatic and electrostatic contributions to the free energy of the mixtures. Potential applications of this approach …

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Edge Strength Of Window Glass By Mechanical Test, Chris P. Pantelides, Gregory P. Sallee, Joseph E. Minor Jan 1994

Edge Strength Of Window Glass By Mechanical Test, Chris P. Pantelides, Gregory P. Sallee, Joseph E. Minor

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A mechanical test is described that can be used to measure the edge strength of annealed and heat-strengthened glass. The mechanical test apparatus stresses only one of the two edge-lines on the edge of a glass specimen. The testing concept employs the theory of unsymmetrical bending. The test device loads glass specimens in a manner that places tensile stresses on the tested edge-line while keeping the other edge-lines at zero stress or in compression. In annealed glass tests, the scored edge-line was found to be 20% weaker than the edge-line opposite the scored edge-line. Comparisons between the edge strengths of …

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Ai-Based Generation Of Production Engineering Labor Standards, Hulya Yazici, Colin Othniel Benjamin, James Mcglaughlin Jan 1994

Ai-Based Generation Of Production Engineering Labor Standards, Hulya Yazici, Colin Othniel Benjamin, James Mcglaughlin

Engineering Management and Systems Engineering Faculty Research & Creative Works

Increased automation of manufacturing is necessary to compete in today's worldwide markets. The role of artificial intelligence (AI) techniques for incorporating the automation with changing manufacturing environments needs to be investigated. Al techniques can assist in meeting the challenge of transforming shop floor production engineering data into appropriate production engineering labor standards in a timely, consistent, and cost-effective manner. Production heuristics can be incorporated into an expert system that can learn from the changing manufacturing environment. This paper presents a prototype expert system which transfers the knowledge of experienced methods engineers into a rule-based system to develop the appropriate job …

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Effectiveness Of A Multimedia Televised Distance Education Program For Engineering Majors, Bonnie Daily, Madison Daily Jan 1994

Effectiveness Of A Multimedia Televised Distance Education Program For Engineering Majors, Bonnie Daily, Madison Daily

Engineering Management and Systems Engineering Faculty Research & Creative Works

The University of Missouri‐Rolla, the state's, "technological university," has proposed a televised distance education program that would originate on the UMR campus and be delivered to community colleges and four‐year institutions within the state not now offering engineering. The program would include the use of computer‐integrated multimedia classrooms at both the home site and remote sites and would permit two‐way transmission of video, audio, and data. Student response units would also be used at both sites to permit immediate feedback from the students to the instructor. Due to the cost of this proposal, it was determined a pilot study would …

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Dominance Of The Thomas Mechanism For Electron Capture From Orientated Rydberg Atoms, Jee-Ching Wang, Ronald E. Olson Jan 1994

Dominance Of The Thomas Mechanism For Electron Capture From Orientated Rydberg Atoms, Jee-Ching Wang, Ronald E. Olson

Chemical and Biochemical Engineering Faculty Research & Creative Works

We investigate electron capture from initially oriented circular Rydberg atoms by proton impact at collision speeds comparable to the electron orbital speed. The Thomas double scattering mechanism is observed even at these low relative speeds. Furthermore, we find evidence for the dominance of a quasi Thomas capture mechanism in the form of not a single peak, but a double-peaked structure in the differential cross section when the plane of the circular orbit is nearly perpendicular to the incident direction of the projectile. © 1994 The American Physical Society.

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Doctoral Programs Computer Info Systems, Info Science, Info Sytems, Computer Science, Computing Technology In Education 1994, Nova Southeastern University Jan 1994

Doctoral Programs Computer Info Systems, Info Science, Info Sytems, Computer Science, Computing Technology In Education 1994, Nova Southeastern University

College of Engineering and Computing Course Catalogs

No abstract provided.

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Bachelor Of Science Degree In Computer Science, Nova Southeastern University Jan 1994

Bachelor Of Science Degree In Computer Science, Nova Southeastern University

College of Engineering and Computing Course Catalogs

No abstract provided.

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Reflection High-Energy Electron-Diffraction Study Of Surface Disorder And Anomalous Expansion Of Pb(100), D. Tang, H. E. Elsayed-Ali Jan 1994

Reflection High-Energy Electron-Diffraction Study Of Surface Disorder And Anomalous Expansion Of Pb(100), D. Tang, H. E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

The temperature-dependent surface structural behavior of Pb(100) is studied using reflection high-energy electron diffraction. Anomalous surface expansion for temperatures between room temperature to about 500 K is observed. A high density of surface vacancies appears at temperatures above ~ 500 K. © 1994 The American Physical Society.

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Water Vapor Permeability And Mechanical Properties Of Grain Protein-Based Films As Effected By Mixtures Of Polyethylene Glycol Amd Glycerin Plasticizers, H. J. Park, J. M. Bunn, Curtis L. Weller, P. J. Vergano, R. F. Testin Jan 1994

Water Vapor Permeability And Mechanical Properties Of Grain Protein-Based Films As Effected By Mixtures Of Polyethylene Glycol Amd Glycerin Plasticizers, H. J. Park, J. M. Bunn, Curtis L. Weller, P. J. Vergano, R. F. Testin

Biological Systems Engineering: Papers and Publications

Grain protein-based films containing mixtures of glycerin and polyethylene glycol (PEG) as plasticizers were prepared and evaluated for water vapor permeability (WVP), tensile strength (TS), and elongation (E). Changes in mechanical properties during storage were also studied. The PEG produced opposite trends in E of wheat gluten and corn-zein films. The TS of wheat gluten films increased and E of the films decreased as the ratio of glycerin/PEG decreased. Corn-zein films containing only glycerin were very brittle (E of 4%), and E of the films improved to 94% when the ratio of mL PEG/g protein was 0.39. The WVP of …

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Tillage And Planting System, Stalk Chopper, And Knife Applicator Influences On Corn Residue Cover, David P. Shelton, Stephen D. Kachman, Elbert C. Dickey, K.T. Fairbanks, Paul J. Jasa Jan 1994

Tillage And Planting System, Stalk Chopper, And Knife Applicator Influences On Corn Residue Cover, David P. Shelton, Stephen D. Kachman, Elbert C. Dickey, K.T. Fairbanks, Paul J. Jasa

Biological Systems Engineering: Papers and Publications

Percent corn (Zea mays L.) residue cover remaining on the soil surface after planting was measured for 11 tillage and planting systems that included combinations of the use, and timing, of a stalk chopper and/or a knife-type fertilizer applicator. Tillage, as well as use of a stalk chopper or knife applicator, significantly reduced residue cover. Only 27 of the 69 stalk chopper/knife applicator/tillage and planting system treatment combinations that were evaluated could be classified as conservation tillage by having at least 30% residue cover remaining after planting.

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Monte Carlo Calculation Of Effective Diffusivities In Two- And Three-Dimensional Heterogeneous Materials Of Variable Structure, Mark R. Riley, Fernando J. Muzzio, Helen M. Buettner, Sebastian C. Reyes Jan 1994

Monte Carlo Calculation Of Effective Diffusivities In Two- And Three-Dimensional Heterogeneous Materials Of Variable Structure, Mark R. Riley, Fernando J. Muzzio, Helen M. Buettner, Sebastian C. Reyes

Biological Systems Engineering: Papers and Publications

A Monte Carlo technique that simulates tracer diffusion in multiphase materials of arbitrary complexity has been developed. Effective diffusivities are calculated for structures consisting of either overlapping or nonoverlapping inclusions with diffusivity Dc, distributed in a continuous phase with diffusivity D0>Dc. Two-dimensional simulations for various values of D0/Dc generate normalized diffusivities that correspond closely to their three-dimensional counterparts; they nearly collapse to a common curve when a simple scaling relation is applied.

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Darcy-Weisbach Roughness Coefficients For Selected Crops, John E. Gilley, E. R. Kottwitz Jan 1994

Darcy-Weisbach Roughness Coefficients For Selected Crops, John E. Gilley, E. R. Kottwitz

Biological Systems Engineering: Papers and Publications

Total hydraulic resistance on an upland agricultural site may be influenced by several factors including standing vegetation. In this laboratory study, Darcy-Weisbach roughness coefficients were measured for corn, cotton, sorghum, soybeans, sunflower, and wheat vegetation. Experimental variables used in this investigation in addition to crop type included plant population, row spacing, row orientation, and flow rate. For some of the experimental tests, a single row of vegetation was oriented within a flume parallel to the principal flow direction. For the remainder of the tests, rows of vegetation were placed perpendicular to the flow using row spacings and plant populations recommended …

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Moisture Adsorption By Grain Protein Films, A. Gennadios, Curtis L. Weller Jan 1994

Moisture Adsorption By Grain Protein Films, A. Gennadios, Curtis L. Weller

Biological Systems Engineering: Papers and Publications

Grain protein films plasticized with glycerol were prepared from corn zein (CZ), wheat gluten (WG), and a 2.3:1 mixture of wheat gluten and soy protein isolate (WG/SPI). Moisture adsorption curves of the three types of protein films at 25° C and within an approximate water activity range of 0.11 to 0.84 were obtained using a static gravimetric method. The Smith, Oswin, Halsey, and Guggenheim-Anderson-de Boer (GAB) models were applied to collected data. For all protein films, the GAB model showed the best fit over the entire studied water activity range yielding mean deviation modulus values (P) of 4.69, 3.44, and …

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Preventing Pesticide Contamination Of Groundwater While Maximizing Irrigated Crop Yield, Richard C. Peralta, M. A. Hegazy, G. Musharrafieh Jan 1994

Preventing Pesticide Contamination Of Groundwater While Maximizing Irrigated Crop Yield, Richard C. Peralta, M. A. Hegazy, G. Musharrafieh

Civil and Environmental Engineering Faculty Publications

A simulation/optimization model is developed for maximizing irrigated crop yield while avoiding unacceptable pesticide leaching. The optimization model is designed to help managers prevent non-point source contamination of shallow groundwater aquifers. It computes optimal irrigation amounts for given soil, crop, chemical, and weather data and irrigation frequencies. It directly computes the minimum irrigated crop yield reduction needed to prevent groundwater contamination. Constraint equations used in the model maintain a layered soil moisture volume balance; describe percolation, downward unsaturated zone solute transport and pesticide degradation; and limit the amount of pesticide reaching groundwater. Constraints are linear, piecewise linear, nonlinear, and exponential. …

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Optimizing Irrigation Management For Pollution Control And Sustainable Crop Yield, Ghassan R. Musharrafieh, Richard C. Peralta, Ronald J. Hanks, Lynn M. Dudley Jan 1994

Optimizing Irrigation Management For Pollution Control And Sustainable Crop Yield, Ghassan R. Musharrafieh, Richard C. Peralta, Ronald J. Hanks, Lynn M. Dudley

Civil and Environmental Engineering Faculty Publications

Irrigation strategies which maximize crop yield while maintaining target salt concentration in the root zone and/or prevent salt from leaching to the groundwater are computed using a nonlinear, one dimensional, simulation/optimization management model. The included constraint equations maintain a water volume balance and salt transport in the unsaturated zone. Utilized are implicit finite difference forms of the nonlinear, unsteady, unsaturated water flow equation (Richards's equation), and the diffusion-convection solute transport equation. Other constraints include nonlinear functions describing the hydraulic properties of the medium (hydraulic conductivity as a function of matric potential, volumetric water content as a function of matric potential, …

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Introducing Uncertainty Of Aquifer Parameters Into An Optimization Model, Robert L. Ward, Richard C. Peralta Jan 1994

Introducing Uncertainty Of Aquifer Parameters Into An Optimization Model, Robert L. Ward, Richard C. Peralta

Civil and Environmental Engineering Faculty Publications

A stochastic analysis is made for a previously described groundwater contaminant management model {Peralta and Ward, 1988). The stochastic model is based on incorporating uncertainty of the aquifer parameters transmissivity and effective porosity into the model. This is accomplished by finding the partial derivative of drawdown with respect to each of these parameters using a Taylor series expansion approximation of the Theis equation. Input that is required for the stochastic version is the mean of the transmissivity and effective porosity, the coefficient of variation of the transmissivity and effective porosity, and a reliability level (0%-100%) . The reliability is a …

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Transform Method Of Processing For Speckle Strain-Rate Measurements, Donald D. Duncan, Sean J. Kirkpatrick, F. Fausten Mark, Lawrence W. Hunter Jan 1994

Transform Method Of Processing For Speckle Strain-Rate Measurements, Donald D. Duncan, Sean J. Kirkpatrick, F. Fausten Mark, Lawrence W. Hunter

Electrical and Computer Engineering Faculty Publications and Presentations

We have developed a highly sensitive method for measuring thermal expansion, mechanical strain, and creep rates. We use the well-known technique of observing laser speckle with a pair of linear array cameras, but we employ a data-processing approach based on a two-dimensional transform of the speckle histories from each camera. This technique can effect large gauge sizes, which are important in the assessment of the spatial statistics of creep. Further, the algorithm provides simultaneous global estimates of the strain rates at both small- and large-scale sizes. This feature may be of value in the investigation of materials with different short- …

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Programmable Analog Array Circuit, Marek Perkowski, Edmund Pierzchala Jan 1994

Programmable Analog Array Circuit, Marek Perkowski, Edmund Pierzchala

Electrical and Computer Engineering Faculty Publications and Presentations

There is disclosed a programmable analog or mixed analog/ digital circuit. More particularly, this invention provides a circuit architecture that is ?exible for a programmable electronic hardWare device or for an analog circuit Whose input and output signals are analog or multi-valued in nature, and primarily continuous in time. There is further disclosed a design for a current-mode integrator and sample-and-hold circuit, based upon Miller effect.

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Use Of Waste Foundry Sand In Highway Construction : Final Report, Sayeed Javed Jan 1994

Use Of Waste Foundry Sand In Highway Construction : Final Report, Sayeed Javed

JTRP Technical Reports

The promulgation of environmental regulations, both at the federal and state level, have resulted in increased control over both the hazardous and nonhazardous wastes generated in the foundry industry. The increased regulation action has in many cases resulted in foundry wastes being disposed in highly engineered and often times costly land disposal facilities. Beneficial reuse represents an alternative to disposal and the associated problems of diminished landfill capacity and increased tipping fees. This study contains: synthesis of all available information and laboratory results for different beneficial uses of waste foundry sand. Among the different beneficial uses, waste foundry sand as …

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Estimating Statewide Vehicle Miles Traveled In Indiana : Draft Final Report, Robert Kwasi Kumapley, Jon D. Fricker Jan 1994

Estimating Statewide Vehicle Miles Traveled In Indiana : Draft Final Report, Robert Kwasi Kumapley, Jon D. Fricker

JTRP Technical Reports

Two cross classification models have been developed in this study for use in the estimation of statewide VMT in Indiana. This is to provide INDOT with an independent source of improved statewide VMT estimates based on driver behavior to supplement the estimates obtained from the traffic count based HPMS method. The models are calibrated to produce VMT estimates for all functional classes in the state network, including combined statewide VMT estimates for functional classes that are not part of the state highway system. The results obtained in the model evaluation process indicate that the models are well calibrated. Model-generated VMT …

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Neutron-Scattering Study Of Librations And Intramolecular Phonons In Rb_{2.6}K_{0.4}C_{60}, D. Reznik, W. A. Kamitakahara, D. A. Neumann, J. R. D. Copley, J. E. Fischer, Robert M. Strongin, M. A. Cichy, Amos B. Smith Iii Jan 1994

Neutron-Scattering Study Of Librations And Intramolecular Phonons In Rb_{2.6}K_{0.4}C_{60}, D. Reznik, W. A. Kamitakahara, D. A. Neumann, J. R. D. Copley, J. E. Fischer, Robert M. Strongin, M. A. Cichy, Amos B. Smith Iii

Chemistry Faculty Publications and Presentations

We report the results of inelastic neutron-scattering measurements on Rb2.6K0.4C60. Librational modes were observed as broad peaks with maxima between 4.1 and 4.7 meV, as the temperature is lowered from 300 to 12 K. As in K3C60, no change in the width or position of the librational peak was observed when the sample was cooled through the superconducting transition. Thus any coupling of the librations to electronic states is small. The magnitude of the orientational potential barrier was estimated from the librational peak frequency. A flat background observed in the …

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