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Selected Works

1992

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Articles 1 - 30 of 48

Full-Text Articles in Physical Sciences and Mathematics

The Elastic Moduli Of Simple Two-Dimensional Isotropic Composites: Computer Simulation And Effective Medium Theory, K. A. Snyder, E. J. Garboczi, Anthony Roy Day Dec 1992

The Elastic Moduli Of Simple Two-Dimensional Isotropic Composites: Computer Simulation And Effective Medium Theory, K. A. Snyder, E. J. Garboczi, Anthony Roy Day

Anthony Roy Day

An algorithm, combining digital-image with spring network techniques, has been developed that enables computation of the elastic moduli of random two-dimensional multiphase composites. This algorithm is used to study the case of isotropic, randomly centered, overlapping circular inclusions in an isotropic elastic matrix. The results of the algorithm for the few-inclusion limit, as well as the case where both phases have the same shear moduli, agree well with the exact results for these two problems. The case where the two phases have the same Poisson’s ratio, but different Young’s moduli, is also studied, and it is shown that the effective …

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Measurements Of Νw2 And R=Σl/Σt From Inelastic Electron-Aluminum Scattering Near X=1, P E. Bosted, A Lung, L Andivahis, L M. Stuart, J Alster, R G. Arnold, C C. Chang, F S. Dietrich, W Dodge, R Gearhart, J Gomez, K A. Griffioen, R S. Hicks, C E. Hyde-Wright, C Keppel, S E. Kuhn, J Lichtenstadt, R A. Miskimen, Gerald Alvin Peterson Dec 1992

Measurements Of Νw2 And R=Σl/Σt From Inelastic Electron-Aluminum Scattering Near X=1, P E. Bosted, A Lung, L Andivahis, L M. Stuart, J Alster, R G. Arnold, C C. Chang, F S. Dietrich, W Dodge, R Gearhart, J Gomez, K A. Griffioen, R S. Hicks, C E. Hyde-Wright, C Keppel, S E. Kuhn, J Lichtenstadt, R A. Miskimen, Gerald Alvin Peterson

Gerald Alvin Peterson

Cross sections for inclusive electron scattering from aluminum have been measured at both forward and backward angles in the kinematic region near x =1 and 1.75 & Q & 7 (GeV/c) . The forward-angle data are in good agreement with a recent calculation. Both the data and the calculation show scaling behavior for F2(g, Q~)=vs(g, Q2) at high Q for fixed values of the Nachtmann variable g. The ratio R =oL /trr has been extracted for 1.75 &Q &5 (GeV/c) and is found to decrease with Q2 to a value consistent with zero at the highest Q~.

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70. Obituary, Herman F. Mark, Otto Vogl Dec 1992

70. Obituary, Herman F. Mark, Otto Vogl

Otto Vogl

No abstract provided.

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Royal Institute Of Technology: Department Of Polymer Technology, Otto Vogl, Ann Christine Albertsson Dec 1992

Royal Institute Of Technology: Department Of Polymer Technology, Otto Vogl, Ann Christine Albertsson

Otto Vogl

No abstract provided.

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Π-Bond Strengths Of H2x=Yh2: X = Ge Or Sn, And Y = C, Si, Ge, Or Sn, Theresa L. Windus, Mark S. Gordon Nov 1992

Π-Bond Strengths Of H2x=Yh2: X = Ge Or Sn, And Y = C, Si, Ge, Or Sn, Theresa L. Windus, Mark S. Gordon

Mark S. Gordon

The molecular structures and 1r-bond strengths are determined using both MP2 and MCSCF + CI energies for a series of H2X=YH2 compounds, where X = Ge or Sn and Y = C, Si, Ge, or Sn. These strengths are estimated both by evaluating the rotation barriers and by investigating the appropriate thermochemical cycles. The results show that C > Si ,.., Ge > Sn in their ability to form The molecular structures and 1r-bond strengths are determined using both MP2 and MCSCF + CI energies for a series of H2X=YH2 compounds, where X = Ge or Sn and Y = C, Si, …

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Polymer Science In Finland, Otto Vogl, Johan J. Lindberg, Franciska Sundholm Nov 1992

Polymer Science In Finland, Otto Vogl, Johan J. Lindberg, Franciska Sundholm

Otto Vogl

No abstract provided.

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71. Otto Vogl, David A. Tirrell Nov 1992

71. Otto Vogl, David A. Tirrell

Otto Vogl

No abstract provided.

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Climatology Of Surface-Based Inversions In The North American Arctic, Raymond S. Bradley, Frank T. Keimig Oct 1992

Climatology Of Surface-Based Inversions In The North American Arctic, Raymond S. Bradley, Frank T. Keimig

Raymond S Bradley

The annual cycle of surface-based inversions at nine Arctic weather stations is examined, based on a 20-year set of daily 1200 UT significant level radiosonde data. All stations are at or near the coast. Inversions in winter months are primarily the result of strongly negative net radiation at the surface, whereas in summer, inversionsmore commonly result from near-surface cooling of warm air muses. Inversion frequency is at a maximum inwinter (generally >70% of days) when inversions range from -400 to -850 m in thickness. Inversion thickness and strength (temperature change across the inversion) are strongly related to surface temperature. Inversions …

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Uncatalyzed Peptide Bond Formation In The Gas Phase, Jan H. Jensen, Kim K. Balgridge, Mark S. Gordon Oct 1992

Uncatalyzed Peptide Bond Formation In The Gas Phase, Jan H. Jensen, Kim K. Balgridge, Mark S. Gordon

Mark S. Gordon

Several levels of electronic structure theory are used to analyze the formation of a peptide bond between two glycine molecules. Both a stepwise and concerted mechanism were considered. The energetic requirements for the stepwise and concerted mechanisms are essentially the same within the expected accuracy of the methods used. A simpler model system comprised of formic acid and ammonia is found to provide a good representation of the essential features of dipeptide formation. Total electron densities and localized molecular orbitals are used to interpret the mechanisms.

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Iupac Conference On “New Polymers”, Kyoto, Japan, Otto Vogl, Yoshiki Chujo Oct 1992

Iupac Conference On “New Polymers”, Kyoto, Japan, Otto Vogl, Yoshiki Chujo

Otto Vogl

No abstract provided.

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Can The Kindergarten Diagnostic Instrument Be Used To Identify Children Who Will Qualify For A Reading Intervention Program?, John Fraas, Cynthia Frick Sep 1992

Can The Kindergarten Diagnostic Instrument Be Used To Identify Children Who Will Qualify For A Reading Intervention Program?, John Fraas, Cynthia Frick

John W. Fraas

No abstract provided.

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Strategies Tor Designing A High-Valent Transition-Metal Silylidene Complex, Thomas R. Cundiari, Mark S. Gordon Sep 1992

Strategies Tor Designing A High-Valent Transition-Metal Silylidene Complex, Thomas R. Cundiari, Mark S. Gordon

Mark S. Gordon

The electronic structure of complexes arising from the formation of a double bond between a silylene ligand (Si(R)R') and a high-valent transition-metal fragment have been investigated using ab initio wave functions including the effects of electron correlation. Using the analogy of carbon, these complexes may be referred to as Scbrock-type silylenes or silylidenes. A prime motivation for this work is that complexes of this type, unlike their carbon analogues, have so far eluded attempts at experimental characterization. Several conclusions are reached as a result of these calculations. (a) The inclusion of electron correlation is necessary to adequately describe the MSi …

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Second Pacific Polymer Conference In Otsu, Shiga, Japan, Otto Vogl, Tatsuki Kitayama, Koichi Hatada Sep 1992

Second Pacific Polymer Conference In Otsu, Shiga, Japan, Otto Vogl, Tatsuki Kitayama, Koichi Hatada

Otto Vogl

No abstract provided.

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The 33rd Iupac Congress, Budapest, August 17-22, 1991, Otto Vogl, Koichi Hatada Aug 1992

The 33rd Iupac Congress, Budapest, August 17-22, 1991, Otto Vogl, Koichi Hatada

Otto Vogl

No abstract provided.

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Tenth International Symposium On Cationic Polymerization And Related Processes, Otto Vogl, Gyorgy Deak Jul 1992

Tenth International Symposium On Cationic Polymerization And Related Processes, Otto Vogl, Gyorgy Deak

Otto Vogl

No abstract provided.

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Measurement Of The Electric And Magnetic Form Factors Of The Proton From Q2 1.75 To 8.83 (Gev/C)2, P E. Bosted, L Clogher, A Lung, R G. Arnold, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson Jun 1992

Measurement Of The Electric And Magnetic Form Factors Of The Proton From Q2 1.75 To 8.83 (Gev/C)2, P E. Bosted, L Clogher, A Lung, R G. Arnold, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson

Gerald Alvin Peterson

The proton elastic electric and magnetic form factors, GEM and G’bfP(Q2), have been separately measured in the range Q” =1.75 to 8.83 (GeV/c)2, more than doubling the Q3 range of previous data. Scaled by the dipole fit, Go(Q2), the results for Gnlp(Q2)//+G~(Q2) d ecrease smoothly from 1.05 to 0.91, while G~p(Q~)lcdQ~) is consistent with unity. Comparisons are made to QCD Sum L-eRule, diquark, constituent quark, and VMD models, none of whic,h agree with all of the new data. The ratio Q2F2/Fl approaches a constant value for Q2 > 3 ( GeV/c)2. --p;. .- -- 2

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Can Small-Area Analysis Detect Variation In Surgery Rates? The Power Of Small-Area Variation Analysis., Paula Diehr Jun 1992

Can Small-Area Analysis Detect Variation In Surgery Rates? The Power Of Small-Area Variation Analysis., Paula Diehr

Paula Diehr

A variety of statistical methods can be used in small-area analysis to test whether there is more variation than would be expected by chance alone. However, the power of these methods to detect existing variation has never been studied. The authors used data regarding back surgery in Washington State to suggest several types of variation that might exist (alternative hypotheses), and then used computer simulation to determine the power, or the probability of detecting this variation. The chi-square test had the highest power of all methods considered against most alternative hypotheses. Power is higher if there are no multiple admissions, …

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Applications Of Harmonic Functions To Robotics, Christopher Connolly, Roderic Grupen May 1992

Applications Of Harmonic Functions To Robotics, Christopher Connolly, Roderic Grupen

Roderic Grupen

Harmonic functions are solutions to Laplace's Equation. As noted in a previous paper, they can be used to advantage for potential-field path planning, since they do not exhibit spurious local minima. In this paper, harmonic functions are shown to have a number of other properties (including completeness) which are essential to robotics applications. These properties strongly recommend harmonic functions as a mechanism for robot control.

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Spatial Variation Of A Short-Lived Intermediate Chemical Species In A Couette Reactor, R. Dennis Vigil, Q. Ouyang, Harry L. Swinney Apr 1992

Spatial Variation Of A Short-Lived Intermediate Chemical Species In A Couette Reactor, R. Dennis Vigil, Q. Ouyang, Harry L. Swinney

R. Dennis Vigil

We have conducted experiments and simulations of the spatial variation of a short-lived intermediate species (triiodide) in the autocatalytic oxidation of arsenite by iodate in a reactor that is essentially one dimensional-the Couette reactor. (This reactor consists of two concentric cylinders with the inner one rotating and the outer one at rest; reagents are continuously fed and removed at each end in such a way that there is no net axial flux and there are opposing arsenite and iodate gradients.) The predictions ?f a one-dim~ns~onal . reaction-diffusion model which has no adjustable parameters, are In good qualItative (and, In some …

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Ion Composition Of The Topside Equatorial Ionosphere During Solar Minimum, S. A. Gonzales, Bela G. Fejer, R. A. Heelis, W. B. Hanson Apr 1992

Ion Composition Of The Topside Equatorial Ionosphere During Solar Minimum, S. A. Gonzales, Bela G. Fejer, R. A. Heelis, W. B. Hanson

Bela G. Fejer

We have used observations from both the Bennett ion mass spectrometer and the retarding potential analyzer on board the Atmosphere Explorer E satellite to study the longitudinally averaged O+, H+, and He+ concentrations from 150 to 1100 km in the equatorial ionosphere during the 1975–1976 solar minimum. Our results suggest that the ion mass spectrometer measurements need to be increased by a factor of 2.15 to agree with the densities from the retarding potential analyzer and with ground-based measurements. The peak H+ concentrations are about 2.5×104 cm−3 during the day and 104 cm−3 at night and vary little with season. …

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A Binomial Test Of Model Fit, John Fraas, Isadore Newman Mar 1992

A Binomial Test Of Model Fit, John Fraas, Isadore Newman

John W. Fraas

No abstract provided.

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Pinski Et Al. Reply, F. J. Pinski, B. Ginatempo, Duane D. Johnson, J. B. Staunton, G. M. Stocks, B. L. Gyorffy Mar 1992

Pinski Et Al. Reply, F. J. Pinski, B. Ginatempo, Duane D. Johnson, J. B. Staunton, G. M. Stocks, B. L. Gyorffy

Duane D. Johnson

With our calculations [I], we uncovered the electronic mechanism responsible for inducing atomic short-range order (SRO) in the disordered solid solution of NiPt as it is cooled. Usually, but not always, SRO, whether derived theoretically or measured experimentally, indicates the nature of the long-rangeordered (LRO) state that will stabilize at low temperature. Our calculation of the atomic SRO, while agreeing with experiments [2], neglected the relativistic effects in the electronic structure. Lu, Wei, and Zunger (LWZ) [3,4], on the other hand, have calculated the L lo-ordered alloy formation energy and find that only when relativistic effects are included is the …

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Hypercoordination In Group Iv Mh5 And Mh5- Systems, Marshall T. Carroll, Mark S. Gordon, Theresa L. Windus Mar 1992

Hypercoordination In Group Iv Mh5 And Mh5- Systems, Marshall T. Carroll, Mark S. Gordon, Theresa L. Windus

Mark S. Gordon

The energetics and bonding of the group IV hypervalent MH5 and MH5- D3h structures (M = C, Si, Ge, Sn) are examined in this paper. Ab initio all-electron calculations are used to predict the energies and geometries of the systems. The resulting electron densities are analyzed using the topological theory of atoms in molecules. It is found that the anion energetically is more stable than the neutral radical for M = Si, Ge, and Sn but not for M = C. Further distinguishing carbon from the other members of the group is the fact that the CH bond mostly is …

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Experimental And Theoretical Evidence In Support Of An Intermediate Complex In The Insertion Reaction Of Silylene Into Silane, R. Becerra, H. M. Frey, B. P. Mason, R. Walsh, Mark S. Gordon Mar 1992

Experimental And Theoretical Evidence In Support Of An Intermediate Complex In The Insertion Reaction Of Silylene Into Silane, R. Becerra, H. M. Frey, B. P. Mason, R. Walsh, Mark S. Gordon

Mark S. Gordon

The reaction between silylene, SiH2, and silane, SiH4, viz. SiH2 + SiH4 - Si2H6 (1) may reasonably be considered the prototype Si-H insertion process of silicon hydride chemistry. This reaction, which is also the second step in the thermolysis of silane1 leading ultimately to solid silicon and silicon hydride deposition, is known to be fast. Experimental measurements of the rate constant2-4 show the reaction to proceed at close to the collisional limit. Theoretical calculations of the energy surface for the decomposition of Si2H6 show that it possesses no energy barrier at the threshold of dissociation,5 which suggests a zero barrier …

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Tem Observations Of The Mechanism Of Delamination Of Chromium Films From Silicon Substrates, D. Goyal, Alexander H. King Feb 1992

Tem Observations Of The Mechanism Of Delamination Of Chromium Films From Silicon Substrates, D. Goyal, Alexander H. King

Alexander H. King

We have observed the complete delamination of polycrystalline chromium films from single crystal silicon substrates during deposition due to the formation of high internal stresses. These intrinsic stresses can give rise to interfacial defects which assist in the separation of the film from the substrate. Stresses in the film are balanced by stresses in the substrate, which cause mechanical failure in the substrate near the interface. Extensive arrays of dislocations and cracking of the substrate have been observed. We find that the delamination of the films from the substrate is initiated by the formation of damage in the substrate, rather …

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Multi-Ball Collisions, Terry L. Smith, Jay S. Huebner Jan 1992

Multi-Ball Collisions, Terry L. Smith, Jay S. Huebner

Terry L. Smith

Explanation to use the "double-ball" demonstration as a model for the supernova core bounce.

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Combination Of Orthogonality And Simplex Method For Solving Linear Programming, G.R. Jahanshahloo, S. Abbasbandy Jan 1992

Combination Of Orthogonality And Simplex Method For Solving Linear Programming, G.R. Jahanshahloo, S. Abbasbandy

Saeid Abbasbandy

For obtaining an optimal solution in L.P. combination of orthogonality and simplex method is used. It seems that the number of iteration is reduced.

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Micro And Macromorphology Of Recycled Fiber And Wood, Douglas D. Stokke Jan 1992

Micro And Macromorphology Of Recycled Fiber And Wood, Douglas D. Stokke

Douglas D. Stokke

Wood is a major industrial raw material, with U.S. consumption approaching that of aluminum, plastics, cement, and steel combined. Partially as a result of the magnitude of wood and wood products in use, these products constitute a substantial portion of the solid waste stream. In order to reduce the amount of wood and wood fiber disposed in landfills, efforts to recycle these materials into useful products such as structural composites are needed. The success of such conversion depends in part on knowledge of the morphological characteristics of various sources of secondary wood and wood fibers, and the influence of wood …

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Theoretical Investigatlons Of Olefin Metathesis Catalysts, Thomas R. Cundiari, Mark S. Gordon Jan 1992

Theoretical Investigatlons Of Olefin Metathesis Catalysts, Thomas R. Cundiari, Mark S. Gordon

Mark S. Gordon

An ab initio analysis of the electronic structure of high-valent, transition-metal alkylidenes as models for olefm metathesis catalysts is presented. The catalyst models studied fall into three categories: "new" metathesis catalyst models-tetrahedral M(0Hh(XH)(CH2) complexes; "old" metathesis catalyst models-tetrahedral MCMY)(CH2) complexes and alkylidene-substituted Mo metathesis catalysts, Mo( OHMNH)(=C(H)Z). The effect on the bonding caused by modification of either the metal, ligands, or alkylidene substituents is considered. For the new models the minimum energy structures result from maximum metal d1rligand p11' bonding and minimum competition among the ligands for the same d11' AO. Rotation about the MC axis increases this competition. The …

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Nature Of The Transition Metal-Silicon Double Bond, Thomas R. Cundiari, Mark S. Gordon Jan 1992

Nature Of The Transition Metal-Silicon Double Bond, Thomas R. Cundiari, Mark S. Gordon

Mark S. Gordon

The nature of the metal-silicon double bond is investigated using ab initio wavefunctions. Electron correlation is specifically included in the calculations at the FORS-MCSCF (full optimized reaction space multiconfiguration self-consistent field) level of theory. Silylene complexes of the form MSiH2 +,containing metals from the first transition series (M = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni), are chosen for this study. An analysis of the bonding and electronic structure among the silylene complexes is presented. The silylene complexes are compared to representative car bene analogues, MCH2 +, and to CrGeH2 + and CrSnH2+.

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