Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network

Open Access. Powered by Scholars. Published by Universities.®

PDF

Missouri University of Science and Technology

Series

1995

Discipline
Keyword
Publication

Articles 1 - 30 of 129

Full-Text Articles in Entire DC Network

Design Guide For Cold-Formed Steel Trusses, Steel In Residential Construction Advisory Group Dec 1995

Design Guide For Cold-Formed Steel Trusses, Steel In Residential Construction Advisory Group

CCFSS Library (1939 - present)

No abstract provided.


The Effect Of Excitation Limits On Voltage Stability, Jyothi Ayyagari, Mariesa Crow Dec 1995

The Effect Of Excitation Limits On Voltage Stability, Jyothi Ayyagari, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Voltage collapse has been commonly associated with insufficient reactive power support. Steady state studies have related reactive power generation limitations to the sudden onset of voltage instability. This paper extends this approach to the dynamic case. The relationship between the dynamic models and steady state behavior is established. The dynamic model is then used to investigate the sudden change in system stability when the maximum excitation limit is reached. Several illustrative examples are analyzed. Corrective actions are proposed which will move the physical system away from the region of instability.


Calibration And Measurement Of Dielectric Properties Of Finite Thickness Composite Sheets With Open-Ended Coaxial Sensors, Stoyan I. Ganchev, Nasser N. Qaddoumi, Sasan Bakhtiari, R. Zoughi Dec 1995

Calibration And Measurement Of Dielectric Properties Of Finite Thickness Composite Sheets With Open-Ended Coaxial Sensors, Stoyan I. Ganchev, Nasser N. Qaddoumi, Sasan Bakhtiari, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

The application of open-ended coaxial sensors for dielectric measurement of finite thickness composite sheets is studied. Expressions for calculation of the complex aperture admittance for two geometries are presented. These expressions are used to calculate the dielectric constant of infinite half-space as well as finite thickness slabs. A more efficient method of such calculations, using a personal computer, for low to medium loss dielectrics is demonstrated. The question of when a dielectric layer may be considered as infinitely thick is also addressed, and examples are presented. A different calibration technique (compared to the conventional ones) is described and successfully implemented. …


Upper-Tropospheric Aerosol Sampled During Project Fire Ifo Ii, Donald E. Hagen, Josef Podzimek, Max B. Trueblood Dec 1995

Upper-Tropospheric Aerosol Sampled During Project Fire Ifo Ii, Donald E. Hagen, Josef Podzimek, Max B. Trueblood

Physics Faculty Research & Creative Works

Aerosols can play a role in the cloud formation process through the heterogeneous nucleation mechanism, and in turn, once formed, cirrus clouds can impact the ambient aerosol through scavenging and other collection mechanisms. University of Missouri aerosol sampling facilities were employed on aircraft for in situ collection and characterization of the particulates near cirrus cloud level. Tandem differential mobility analyzer and impactor techniques were used to measure aerosol size distribution, hydration capability, and particle composition information. Evidence of aerosol layering was observed near the tropospause, and there was a tendency toward depletion of the ambient aerosol at both ends of …


Size-Dependent Adsorption Models In Microporous Materials. 2. Comparison With Experimental Data, Manuela Giustiniani, Massimiliano Giona, Douglas K. Ludlow Nov 1995

Size-Dependent Adsorption Models In Microporous Materials. 2. Comparison With Experimental Data, Manuela Giustiniani, Massimiliano Giona, Douglas K. Ludlow

Chemical and Biochemical Engineering Faculty Research & Creative Works

In This Article, We Complete the Study of Size-Scaling Effects and of the Keller Model, presenting a Detailed Analysis of the Application of This Model to a Broad Range of Experimental Data on Microporous Materials (In Particular, Activated Carbon and Zeolites). Particular Attention is Focused on the Temperature Dependence of the Freundlich Exponents Αi, on the Functional Form of the Adsorption Energies, and on the Application of Keller Adsorption Isotherms in a Predictive Way to Generic Multicomponent Mixtures. © 1995, American Chemical Society. All Rights Reserved.


A Magnetic, Neutron-Diffraction, And Mössbauer Spectral Study Of The Ce₂Fe₁₇₋ₓsiₓ Solid Solutions, D. P. Middleton, Sanjay R. Mishra, Gary J. Long, Oran Allan Pringle, Zhongbo Hu, William B. Yelon, Fernande Grandjean, K. H. J. Buschow Nov 1995

A Magnetic, Neutron-Diffraction, And Mössbauer Spectral Study Of The Ce₂Fe₁₇₋ₓsiₓ Solid Solutions, D. P. Middleton, Sanjay R. Mishra, Gary J. Long, Oran Allan Pringle, Zhongbo Hu, William B. Yelon, Fernande Grandjean, K. H. J. Buschow

Chemistry Faculty Research & Creative Works

The magnetic properties of a series of Ce2Fe17-xSix solid solutions with x equal to 0.0, 0.23, 0.4, 0.6, 0.8, 1.02, 1.98, and 3.20 have been studied by magnetic measurements, neutron diffraction, and Mössbauer spectroscopy. An x-ray-diffraction study indicates that the compounds adopt the rhombohedral Th2Zn 17-type structure. The substitution of silicon for iron in Ce 2Fe17 leads to a contraction of the a axis by 0.2%, an expansion of the c axis by 0.2%, and a consequent reduction of the unit-cell volume by about 0.2% per substituted silicon. Magnetization studies …


Diffusion In Inhomogeneous Polymer Membranes, Sameer Suresh Kasargod, Farhad Adib, Partho Neogi Oct 1995

Diffusion In Inhomogeneous Polymer Membranes, Sameer Suresh Kasargod, Farhad Adib, Partho Neogi

Chemical and Biochemical Engineering Faculty Research & Creative Works

The dual mode sorption solubility isotherms assume, and in instances Zimm-Lundberg analysis of the solubilities show, that glassy polymers are heterogeneous and that the distribution of the solute in the polymer is also inhomogeneous. under some conditions, the heterogeneities cannot be represented as holes. a mathematical model describing diffusion in inhomogeneous polymer membranes is presented using Cahn and Hilliard's gradient theory. the fractional mass uptake is found to be proportional to the fourth root of time rather than the square root, predicted by Fickian diffusion. This type of diffusion is classified as pseudo-Fickian. the model is compared with one experimental …


Coherent Excitation Of The Singlet-Triplet Mixed 1s4f State Of Helium, Jingbo Wang, J. F. Williams, Andris T. Stelbovics, John E. Furst, Don H. Madison Oct 1995

Coherent Excitation Of The Singlet-Triplet Mixed 1s4f State Of Helium, Jingbo Wang, J. F. Williams, Andris T. Stelbovics, John E. Furst, Don H. Madison

Physics Faculty Research & Creative Works

In this paper, we present a detailed theoretical description for the coherent electron-impact excitation, the subsequent time evolution, and the cascading decay process of the singlet-triplet mixed 1s4f state of helium. The excitation amplitude and phase of each sublevel of this state are related to measurable coincidence intensities and polarizations of the emitted photons. It is found that the intensity and polarization of the emitted photons are time modulated due to the singlet and triplet mixing in the 1s4f state.


Stop That Noise, Thomas Van Doren, Todd H. Hubing, Fei Sha, James L. Drewniak, David M. Hockanson Oct 1995

Stop That Noise, Thomas Van Doren, Todd H. Hubing, Fei Sha, James L. Drewniak, David M. Hockanson

Electrical and Computer Engineering Faculty Research & Creative Works

The authors discuss electromagnetic compatibility (EMC) and electromagnetic interference (EMI). After a brief look at the causes of EMI, they describe conductive coupling and electromagnetic radiative coupling. Career opportunities in EMC problem solving are looked at.


Interphase Mass Transfer From Bubbles, Drops, And Solid Spheres: Diffusional Transport Enhanced By External Chemical Reaction, Leonid S. Kleinman, X. B. Reed Oct 1995

Interphase Mass Transfer From Bubbles, Drops, And Solid Spheres: Diffusional Transport Enhanced By External Chemical Reaction, Leonid S. Kleinman, X. B. Reed

Chemical and Biochemical Engineering Faculty Research & Creative Works

Interphase mass transfer has been analyzed for a reactant being transferred from a sphere into a quiescent, infinite continuous phase where it undergoes a chemical reaction. Ranges of the diffusivity ratio D, the distribution coefficient H, and the Damköhler number Da have been delineated, within which the overall resistance to mass transfer may be reasonably ascribed to the sum of the individual resistances in each of the two phases. Outside these parameter ranges, the resistances for two decoupled mass transfer problems may not be added to give the overall resistance to the coupled mass transfer problem. An alternative procedure for …


Strength Of Flexural Members Using Structural Grade 80 Of A653 And Grade E Of A611 Steels, Shaojie Wu, Wei-Wen Yu, Roger A. Laboube Oct 1995

Strength Of Flexural Members Using Structural Grade 80 Of A653 And Grade E Of A611 Steels, Shaojie Wu, Wei-Wen Yu, Roger A. Laboube

CCFSS Library (1939 - present)

This first progress report reviews earlier research on ASTM A653 Structural Grade 80 steel (formerly ASTM A446 Grade E) and similar steels used for cold-formed structural members, and summarizes the results of the tension coupon tests recently carried out at the University of Missouri-Rolla. The review focuses on experimental study and structural performance of members made of such steels, including ultimate strength of structural members as affected by the increases in yield strength of base metal, reduction in ductility of base metal, thickness of base metal, flat width-to-thickness ratio of elements, type of deck profile, and base metal rolling direction. …


Perfusion Chromatography: Performance Of Periodic Countercurrent Column Operation And Its Comparison With Fixed-Bed Operation, G. A. Heeter, Athanasios I. Liapis Sep 1995

Perfusion Chromatography: Performance Of Periodic Countercurrent Column Operation And Its Comparison With Fixed-Bed Operation, G. A. Heeter, Athanasios I. Liapis

Chemical and Biochemical Engineering Faculty Research & Creative Works

Simulation studies using mathematical models that describe the single-component adsorption of bovine serum albumin into spherical bidisperse perfusive and spherical bidisperse purely diffusive anion-exchange porous adsorbent particles in a single-column fixed-bed system and in a two-column periodic countercurrent system in which the adsorbent is equally distributed over two beds are presented. The total length of the two-column periodic countercurrent system is equal to the length of the single-column fixed-bed system, and studies are performed for different values of the intraparticle Peclet number, Peintra, and of the microsphere diameter, dm. In the single-column fixed-bed system, the percentage utilization of the adsorptive …


Comparison Of Branching Ratio And Sum-Rule Analyses Of Magnetic Circular Dichroism In X-Ray-Absorption Spectroscopy, James G. Tobin, George Daniel Waddill, Alan F. Jankowski, Philip A. Sterne, David P. Pappas Sep 1995

Comparison Of Branching Ratio And Sum-Rule Analyses Of Magnetic Circular Dichroism In X-Ray-Absorption Spectroscopy, James G. Tobin, George Daniel Waddill, Alan F. Jankowski, Philip A. Sterne, David P. Pappas

Physics Faculty Research & Creative Works

Two localized picture methods of analyzing the magnetic circular dichroism in x-ray absorption will be applied to experimental results: the branching ratio (BR) and sum rule (SR) approaches. A derivation of the BR formulas and detailed comparison to the SR expressions will be made, including error estimations. The BR approach will be seen to be a limiting case form of the SR spin-moment expression and provide a simple picture of the underlying physics in magnetic x-ray circular dichroism absorption in 3d magnetic materials.


Q Dependence Of Self-Energy Effects Of The Plane Oxygen Vibration In Yba₂Cu₃O₇, Dmitry V. Reznik, Bernhard Keimer, Fatih Dogan, Ilhan A. Aksay Sep 1995

Q Dependence Of Self-Energy Effects Of The Plane Oxygen Vibration In Yba₂Cu₃O₇, Dmitry V. Reznik, Bernhard Keimer, Fatih Dogan, Ilhan A. Aksay

Materials Science and Engineering Faculty Research & Creative Works

We have measured the temperature dependence of the peak position and linewidth of the 42.5 meV phonon branch in a twinned single crystal of YBa2Cu3O7 as a function of wave vector q. In the 100/010 direction in the Brillouin zone, considerable softening and broadening occur below the superconducting transition temperature Tc at some values of q. We observe an order of magnitude smaller softening and no linewidth broadening for q in the 110/110 direction. Possible implications of these findings for the symmetry of the superconducting order parameter are discussed.


Floquet Description Of Multiphoton Processes In Li, D. I. Duncan, J. Greg Story, Thomas F. Gallagher Sep 1995

Floquet Description Of Multiphoton Processes In Li, D. I. Duncan, J. Greg Story, Thomas F. Gallagher

Physics Faculty Research & Creative Works

We have made several different types of measurements of the three-photon ionization of Li produced by 3-ps laser pulses and describe the results using a Floquet picture. Over the photon frequency range 15 000 to 15 800 cm-1, Li represents a strongly coupled three-state system with the 2s ground state coupled to the 2p and 3d states by one and two photons, respectively. Energy analysis of the photoelectrons allows the measurement of the intensity dependent shift of the 2s Floquet state during the laser pulse. The shift shows a strong frequency dependence that is not predicted by first-order …


A Fuzzy Based Load Model For Power System Direct Load Control, K. Bhattacharyya, Mariesa Crow Sep 1995

A Fuzzy Based Load Model For Power System Direct Load Control, K. Bhattacharyya, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Demand side management programs are strategies designed to alter the shape of the load curve. In order to successfully implement such a strategy, customer acceptance of the program is vital. It is thus desirable to design a model for direct load control which may accommodate customer preferences. This paper presents a methodology for optimizing both customer satisfaction and utility unit commitment savings, based on a fuzzy load model for the direct load control of appliances.


Polarized Light Emission In Kev He²⁺ + Na(3s) Collisions, S. Schippers, P. Boduch, J. Van Buchem, F. W. Bliek, R. Hoekstra, R. Morgenstem, Ronald E. Olson Aug 1995

Polarized Light Emission In Kev He²⁺ + Na(3s) Collisions, S. Schippers, P. Boduch, J. Van Buchem, F. W. Bliek, R. Hoekstra, R. Morgenstem, Ronald E. Olson

Physics Faculty Research & Creative Works

We investigated l- and m-distributions of He u (n = 4) states formed during 213.3 keV amu'1 He2+ + Na(3s) collisions by measuring profiles and the linear polarization of the He u (4→ 3) emission. We found that at these energies capture into He+(4f) dominates over capture into other He+(4i) states. Over the indicated energy range the polarization of the4He u (4 → 3) photon emission increases from 0.2 to 0.3 indicating a strong alignment of the captured projectile charge cloud along the intemuclear axis. Due to the non-zero nuclear spin the polarization is up to 10% lower when using3He2+ …


Electron Emission From Foils Induced By Heavy-Ion Collisions, R. A. Sparrow, Ronald E. Olson, D. Schneider Aug 1995

Electron Emission From Foils Induced By Heavy-Ion Collisions, R. A. Sparrow, Ronald E. Olson, D. Schneider

Physics Faculty Research & Creative Works

Absolute double differential yield per ion has been calculated for forward and backward electron emission produced by collisions of highly charged uranium ions with carbon foils of varying thicknesses. A Monte Carlo method has been developed which employs multiple ionization of the carbon and subsequent energy and angular straggling of freed electrons through the foil. A comparison with experimental double differential electron emission yields shows general agreement. Calculated total electron emission is in agreement with experiment at 44 fig cm-2 as well as the results of Rothard et el. In addition, the radial distribution of energy deposited by the electrons …


Polarized Light Emission In Kev He ²⁺+Na(3s) Collisions, S. Schippers, P. Boduch, J. Van Buchem, F. W. Bliek, R. Hoekstra, R. Morgenstern, Ronald E. Olson Aug 1995

Polarized Light Emission In Kev He ²⁺+Na(3s) Collisions, S. Schippers, P. Boduch, J. Van Buchem, F. W. Bliek, R. Hoekstra, R. Morgenstern, Ronald E. Olson

Physics Faculty Research & Creative Works

We investigated l- and m-distributions of He Pi (n=4) states formed during 2-13.3 keV amu -1 He 2++Na(3s) collisions by measuring profiles and the linear polarization of the He Pi (4 to 3) emission. We found that at these energies capture into He +(4f) dominates over capture into other He +(4l) states. Over the indicated energy range the polarization of the 4He Pi (4 to 3) photon emission increases from 0.2 to 0.3 indicating a strong alignment of the captured projectile charge cloud along the internuclear axis. Due to the non-zero nuclear spin the polarization is up to 10% lower …


Ccfss Technical Bulletin August 1995, Wei-Wen Yu Center For Cold-Formed Steel Structures Aug 1995

Ccfss Technical Bulletin August 1995, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Technical Bulletins (1993 - 2020)

No abstract provided.


Instability Of The R³Xs¹ Vacuum In Low-Energy Effective String Theory, Mariano Cadoni, Marco Cavaglia Aug 1995

Instability Of The R³Xs¹ Vacuum In Low-Energy Effective String Theory, Mariano Cadoni, Marco Cavaglia

Physics Faculty Research & Creative Works

We present and discuss a Euclidean solution of the low-energy effective string action that can be interpreted as a semiclassical decay process of the ground state of the theory.


An Experimental Investigation Of 4-Layer Printed Circuit Board Decoupling, Todd H. Hubing, Thomas Van Doren, Fei Sha, James L. Drewniak, Michael J. Wilhelm Aug 1995

An Experimental Investigation Of 4-Layer Printed Circuit Board Decoupling, Todd H. Hubing, Thomas Van Doren, Fei Sha, James L. Drewniak, Michael J. Wilhelm

Electrical and Computer Engineering Faculty Research & Creative Works

This paper examines the measured power bus impedance of fully populated 4-layer printed circuit boards with internal power and ground planes. Three boards provided by two leading computer companies were evaluated. Each of the state-of-the-art high-speed boards used in this study employed surface-mount decoupling capacitors to reduce noise on the power bus. The boards were measured with and without some or all of their decoupling capacitance. The effectiveness of the decoupling capacitors as a function of location and frequency and the relationship between board impedance and power bus noise was explored. The behavior of 4-layer boards is shown to be …


Ccfss News August 1995, Wei-Wen Yu Center For Cold-Formed Steel Structures Aug 1995

Ccfss News August 1995, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Newsletters (1999 - 2008)

No abstract provided.


Integrating Electromagnetic Compatibility Laboratory Exercises Into Undergraduate Electromagnetics, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Fei Sha Aug 1995

Integrating Electromagnetic Compatibility Laboratory Exercises Into Undergraduate Electromagnetics, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Fei Sha

Electrical and Computer Engineering Faculty Research & Creative Works

A state-of-the art high-frequency laboratory is being developed for pursuing laboratory exercises in EMC. These exercises are being integrated into three undergraduate electromagnetics courses. Two of the courses are a required introductory sequence. The laboratory exercises are designed to stimulate students interest, motivate them to learn concepts, and provide them with exposure to practical EMC applications. Laboratory exercises are also an integral part of an EMC elective course. This paper describes the laboratory development and discusses experiments that can be integrated into these three courses for teaching fundamental electromagnetics as well as EMC.


Fdtd Modeling Of Thin Wires For Simulating Common-Mode Radiation From Structures With Attached Cables, David M. Hockanson, James L. Drewniak, Todd H. Hubing, Thomas Van Doren Aug 1995

Fdtd Modeling Of Thin Wires For Simulating Common-Mode Radiation From Structures With Attached Cables, David M. Hockanson, James L. Drewniak, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

The analysis of shielding enclosures is complicated by the existence of apertures and cables. The finite-difference time-domain (FDTD) method can model shielding enclosures with complex geometries, but has difficulty modeling wires and cables of arbitrary radii. Modeling the wire by setting the axial component of the electric field to zero in the FDTD results in a wire with a radius determined by the mesh discretisation. Neglecting wire radius in applications such as electromagnetic interference (EMI) or printed circuit board modeling may result in gross errors because near field quantities are typically sensitive to wire thickness. Taflove (1990) developed a wire …


Coulomb Gap At Finite Temperatures, Masoud Sarvestani, Michael Schreiber, Thomas Vojta Aug 1995

Coulomb Gap At Finite Temperatures, Masoud Sarvestani, Michael Schreiber, Thomas Vojta

Physics Faculty Research & Creative Works

The Coulomb glass, a model of interacting localized electrons in a random potential, exhibits a soft gap, the Coulomb gap, in the single-particle density of states (DOS) g(ε,T) close to the chemical potential µ. In this paper we investigate the Coulomb gap at finite temperatures T by means of a Monte Carlo method. We find that the Coulomb gap fills with increasing temperature. In contrast to previous results the temperature dependence is, however, much stronger than g(µ,T)~TD-1 as predicted analytically. It can be described by power laws with the exponents 1.75 ± 0.1 for the two-dimensional model and 2.7 …


A Comparison Of Fdtd Algorithms For Subcellular Modeling Of Slots In Shielding Enclosures, Kuang-Ping Ma, James L. Drewniak Aug 1995

A Comparison Of Fdtd Algorithms For Subcellular Modeling Of Slots In Shielding Enclosures, Kuang-Ping Ma, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

Thin slot modeling for the finite-difference time-domain (PDTD) method is investigated. Two subcellular algorithms for modeling thin slots with the FDTD method are compared for application to shielding enclosures in EMC. The stability of the algorithms is investigated, and comparisons between the two methods for slots in planes, and slots in loaded cavities are also made.


Correlation Between Sequoia Type Pollen And Lower Oligocene Transgressive Deposits In The Eastern Gulf Coast, Francisca Oboh-Ikuenobe, Lisa M. Reeves Morris Aug 1995

Correlation Between Sequoia Type Pollen And Lower Oligocene Transgressive Deposits In The Eastern Gulf Coast, Francisca Oboh-Ikuenobe, Lisa M. Reeves Morris

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Two taxodiaceous conifer pollen species form the dominant components among sporomorphs of the Lower Oligocene Vicksburg Group in the eastern Gulf Coast. The two species, Sequoiapollenites lapillipites and Sequoiapollenites sp. 1, are very prominent in the Mint Spring Marl and Marianna Limestone at two localities in SE Mississippi and SW Alabama. These two lithostratigraphic units constitute the transgressive systems tract of the Tejas A Gulf Coast (TAGC)-4.4 sequence. Thus, the concentration of these two Sequoia type pollen species may be used as a marker for these transgressive deposits in the eastern Gulf Coast.


Diagnosing And Modeling Common-Mode Radiation From Printed Circuit Boards With Attached Cables, James L. Drewniak, Fei Sha, Todd H. Hubing, Thomas Van Doren, J. Shaw Aug 1995

Diagnosing And Modeling Common-Mode Radiation From Printed Circuit Boards With Attached Cables, James L. Drewniak, Fei Sha, Todd H. Hubing, Thomas Van Doren, J. Shaw

Electrical and Computer Engineering Faculty Research & Creative Works

A procedure for diagnosing and modeling radiation from printed circuit boards with attached cables is presented through a case study of a production model electronic control unit. Procedures for determining EMI antennas, IC sources, and mechanisms by which noise is coupled from the IC source to the antenna are suggested.


Study Of Interconnect Vias By The Discrete Surface Integral Method, Hao Shi, James L. Drewniak Aug 1995

Study Of Interconnect Vias By The Discrete Surface Integral Method, Hao Shi, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A non-orthogonal time-domain full-wave solver, is developed based on the Discrete Surface Integral (DSI) technique. Closed form expressions are derived for the coefficients used in the leap-frog computation scheme so that the DSI technique can be implemented as a generalized finite-difference procedure. This procedure is employed to investigate the propagation characteristics of a typical interconnect via in printed circuits. The numerically calculated scattering parameters show consistent behavior with measured results. A square via with equal area is also evaluated.