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1997

Iowa State University

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Articles 1 - 14 of 14

Full-Text Articles in Engineering

Hydrodynamics Of Dispersed Liquid Droplets In Agitated Synthetic Fibrous Slurries, Theodore J. Heindel, Feler Bose, S. Mostafa Ghiaasiaan Nov 1997

Hydrodynamics Of Dispersed Liquid Droplets In Agitated Synthetic Fibrous Slurries, Theodore J. Heindel, Feler Bose, S. Mostafa Ghiaasiaan

Theodore J. Heindel

The hydrodynamic and liquid particle dispersion processes in agitated vessels containing dilute liquid−liquid dispersions, and dilute liquid dispersions in synthetic fibrous slurries, were experimentally studied. A transparent cylindrical vessel 25 cm in height and 15.5 cm in diameter equipped with a six-blade impeller, with geometric proportions representing the standard vessel configuration, was used. The steady-state size distributions of molten wax particles, which constituted 1% by weight of the mixture everywhere, in pure water, and in aqueous slurries with 0.1%, 0.5%, 0.8%, and 1.0% consistencies of nylon fibers, were measured using sampling and microscopic image analyses. The average nylon fiber length …

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Segregation Of Bismuth To Triple Junctions In Copper, K.-M. Yin, Alexander H. King, T.E. Hsieh, F.-R. Chen, J.J. Kai, L. Chang Sep 1997

Segregation Of Bismuth To Triple Junctions In Copper, K.-M. Yin, Alexander H. King, T.E. Hsieh, F.-R. Chen, J.J. Kai, L. Chang

Alexander H. King

Bismuth segregation in copper has been studied using energy-dispersive X-ray spectrometry (EDX) in a JEOL 2010F transmission electron microscope. In addition to the expected solute enrichment at grain boundaries, we have observed extremely high concentrations of bismuth at certain triple junctions, with significantly greater enrichment factors than in the adjacent grain boundaries. It is shown here that the triple junction segregation is a function of the parameters of the grain boundaries at the triple line, and existence of this type of segregation implies that the affected triple junctions embody excess free energy. At least one of the observed triple junctions …

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Vibrational Spectra In Ordered And Disordered Ni3al, Jeffrey D. Althoff, Dane Morgan, Didier De Fontaine, Mark Asta, S. M. Foiles, Duane D. Johnson Sep 1997

Vibrational Spectra In Ordered And Disordered Ni3al, Jeffrey D. Althoff, Dane Morgan, Didier De Fontaine, Mark Asta, S. M. Foiles, Duane D. Johnson

Duane D. Johnson

We calculate the vibrational density of states (DOS) and corresponding thermodynamic properties of L12 ordered and disordered Ni3Al in the quasiharmonic approximation using the embedded-atom method. Vibrational and thermodynamic properties, including vibrational entropy differences between ordered and disordered states, are found to be in good agreement with experiment. The DOS of the configurationally disordered alloy resembles a broadened version of the DOS of the L12 phase, not a one-atom per cell fcc DOS, and is shifted downward in frequency because the disordered state has a larger volume than the ordered phase. Calculations of the projected DOS indicate that high-frequency modes …

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The Lagrangian Spectral Relaxation Model Of The Scalar Dissipation In Homogeneous Turbulence, Rodney O. Fox Aug 1997

The Lagrangian Spectral Relaxation Model Of The Scalar Dissipation In Homogeneous Turbulence, Rodney O. Fox

Rodney O. Fox

Lagrangian pdf methods are employed to extend the spectral relaxation (SR) model of the scalar dissipation of an inert, passive scalar (1⩽Sc) in homogeneous turbulence. The Lagrangian spectral relaxation (LSR) model divides wavenumber space into a finite number (the total number depending on the Taylor-scale Reynolds numberRλ and the Schmidt number Sc) of wavenumber bands whose time constants are determined from the mean turbulent kinetic energy and instantaneous turbulent energy dissipation rate. The LSR model accounts for the evolution of the scalar spectrum (viz., pdf) from an arbitrary initial shape to its fully developed form. The effect of turbulent-frequencyfluctuations on …

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Use Of Ultimate Load Theories For Design Of Drilled Shaft Sound Wall Foundations, Matthew J. Helmers Jun 1997

Use Of Ultimate Load Theories For Design Of Drilled Shaft Sound Wall Foundations, Matthew J. Helmers

Matthew J. Helmers

A study was performed to investigate the factors that affect the accuracy of the procedures used by the Virginia Department of Transportation for design of drilled shaft sound wall foundations. Field load tests were performed on eight inch and nine inch diameter drilled shafts, and the results were compared to theoretical solutions for ultimate lateral load capacity. Standard Penetration Tests were run in the field and laboratory strength tests were performed on the soils from the test sites. It was found that published correlations between blow count and friction angle for sands and gravels can be used to estimate friction …

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Best-Value Contracting Criteria, Douglas D. Gransberg, Michael A. Ellicott Jun 1997

Best-Value Contracting Criteria, Douglas D. Gransberg, Michael A. Ellicott

Douglas D. Gransberg

Best-value procurements focus on selecting the contractor with the offer most advantageous to the government, when price and other factors are considered. Best-value procurements allow government contracting services to evaluate offers on the basis of total procurement costs, construction quality issues, completion dates, additional features and technical innovations. More importantly, they force the early development of detailed project and procurement plans and create solicitations that contain accurate source-selection criteria. This combination of early planning and quality-based contracting yields significant benefits in construction timeliness, cost containment and customer satisfaction.

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Attitude About Engineering Survey, Fall 1995 And 1996: A Study Of Confidence By Gender, Hugh Fuller, Susan C. Grant, Kristine C. Lawyer, Richard L. Porter, Sarah A. Rajala Jun 1997

Attitude About Engineering Survey, Fall 1995 And 1996: A Study Of Confidence By Gender, Hugh Fuller, Susan C. Grant, Kristine C. Lawyer, Richard L. Porter, Sarah A. Rajala

Sarah A. Rajala

One of the primary goals of the North Carolina State University College of Engineering (COE) is to enroll the best undergraduate students possible. One factor hampering the achievement of this goal is the lack of interest of many female high school students in the traditionally male-dominated field of engineering. With no special recruiting activities aimed at informing young women about the field of engineering and recruiting them to our campus, the results are not surprising: even though women represent forty percent of the undergraduate enrollment at the University, they represent just under twenty percent in the COE. In order to …

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Relevant Design Experiences For Agricultural And Biosystems Engineers: Team Focus Through Competition, D. Raj Raman, Ronald E. Yoder Jun 1997

Relevant Design Experiences For Agricultural And Biosystems Engineers: Team Focus Through Competition, D. Raj Raman, Ronald E. Yoder

D. Raj Raman

The multitude of specializations within biosystems engineering makes traditional capstone design courses, which typically focus on a single topic, less relevant. In our department, our year-long capstone design experience involves machine component design. While this experience is useful to students in all concentrations, ideally, students concentrating on biological-, food-, and soil and water-engineering will have a capstone design experience that integrates their unique technical capabilities. New capstone courses should also enhance the broader skills of undergraduate engineers, including teamwork, time and resource management, oral and written communication, and integrated computer skills. However, a variety of issues militate against simply adding …

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The Evolution Of An Introductory Biological Engineering Course: Design Is The Endpoint!, D. Raj Raman Jun 1997

The Evolution Of An Introductory Biological Engineering Course: Design Is The Endpoint!, D. Raj Raman

D. Raj Raman

Four the past four years, I have taught the sophomore level course, Agricultural Engineering 243 Material and Energy Flows in Biological Systems each spring semester. During the first offering, I used the lecture method to transmit information, and homework assignments and exams to reinforce skills and test comprehension. The greatest weakness of this technique seemed the lack of hands-on experience which I gave my students, and their subsequent lack of physical intuition. Enhancing their physical intuition drove the first curricular revision—using in-class demonstrations and simulations of key physical and biological processes. This technique did not work as well as expected, …

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Experimental And Theoretical Investigations Of Order-Disorder In Cu2almn, Duane D. Johnson, M. Asta, J. J. Hoyt, B. C. Chakoumakos, S. T. Misture, J. D. Althoff, R. Mccormack May 1997

Experimental And Theoretical Investigations Of Order-Disorder In Cu2almn, Duane D. Johnson, M. Asta, J. J. Hoyt, B. C. Chakoumakos, S. T. Misture, J. D. Althoff, R. Mccormack

Duane D. Johnson

A combination of X-ray and neutron powder diffraction has been used to measure the two long range order parameters vs. temperature below the disorder-B2 transition in the ternary alloy Cu2 AlMn. The results indicate that at temperatures just below the critical point the Al + Mn sublattice is enriched in Al. First-principles calculations based on only the atomic numbers of Cu, Mn and Al support the experimentally-observed preference of Al for the Al + Mn sublattice, and reveal the interplay between the constituent binary systems that gives rise to this behavior.

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Transformation Of Tnt By Aquatic Plants And Plant Tissue Cultures, Joseph B. Hughes, Jacqueline V. Shanks, Mindy Vanderford, John Lauritzen, Rajiv Bhadra Jan 1997

Transformation Of Tnt By Aquatic Plants And Plant Tissue Cultures, Joseph B. Hughes, Jacqueline V. Shanks, Mindy Vanderford, John Lauritzen, Rajiv Bhadra

Jacqueline V. Shanks

The ability of plants to uptake and transform 2,4,6-trinitrotoluene (TNT) was investigated using the aquatic plant Myriophyllum spicatum, axenic Myriophyllum aquaticum, and Catharanthus roseus hairy root cultures. Studies demonstrate that Myriophyllum, with or without its periphyton, and C. roseus transform TNT. Low concentrations of aminated nitrotoluenes (2-amino-4,6- dinitrotoluene and 4-amino-2,6-dinitrotoluene) were observed in the extracellular medium and tissue extracts. Primary products of transformation were not identified, and mineralization was not observed. Mass balances demonstrate that a large percentage of the unknown TNT transformation products were associated with the plant. This fraction could be at least partially recovered from the plant …

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Theory Of Thin-Skin Eddy-Current Interaction With Surface Cracks, Nicola Harfield, John R. Bowler Jan 1997

Theory Of Thin-Skin Eddy-Current Interaction With Surface Cracks, Nicola Harfield, John R. Bowler

Nicola Bowler

Eddy-current non-destructive evaluation is commonly performed at relatively high frequencies at which the skin depths are significantly smaller than the dimensions of a typical crack. A thin-skin analysis of eddy currents is presented in which the electromagnetic fields on the crack faces are described in terms of a potential which obeys a two-dimensional Laplace equation. Solutions of this equation for defects in both magnetic and non-magnetic materials are determined by applying thin-skin boundary conditions at the crack perimeter. The impedance change of an eddy-current coil due to the defect is then calculated by numerical evaluation of one-dimensional integrals over the …

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Sensors For Site-Specific Management, Stuart J. Birrell, J. W. Hummel, K. A. Sudduth Jan 1997

Sensors For Site-Specific Management, Stuart J. Birrell, J. W. Hummel, K. A. Sudduth

Stuart J. Birrell

Site-specific management (SSM, also known as precision farming, precision agriculture, prescription farming, etc.) is a management strategy that seeks to address within-field variability and to optimize inputs such as pesticides and fertilizers on a point-by-point basis within a field. By reducing over-application and under-application of nutrients and pesticides, this strategy has the potential to improve profitability for the producer and also to reduce the threat of groundwater or surface water contamination from agrichemicals. SSM is being adopted by innovative producers across the country. Agricultural equipment manufacturers, farm input suppliers, and a host of other businesses are working along with publicsector …

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An Insect-Based Detector Of Bovine Manure Odors, D. Raj Raman, Reid R. Gerhardt Jan 1997

An Insect-Based Detector Of Bovine Manure Odors, D. Raj Raman, Reid R. Gerhardt

D. Raj Raman

We designed, constructed, and tested a single-stream insect odormeter for the measurement of bovine manure odors. The biosensing element in the odormeter is a group of six gravid face flies (Musca autumnalis DeGeer) in a 360 mL chamber. A microphone, mounted above the chamber, senses sounds made by the flies’ activity. The microphone signal is processed by an analog root-mean-square power-measuring circuit connected to a computer data acquisition system. The apparatus allows electronic measurement of insect activity. Initial experiments demonstrate the feasibility of this system for odor detection (yes/no). Kinetic experiments show that a dose-response curve can be produced by …

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