Showing papers by "Missouri University of Science and Technology published in 1976"
TL;DR: The mixed alkali effect in glass refers to the large, orders of magnitude, changes in many properties when a second alkali oxide is added as discussed by the authors, such as electrical conductivity and loss, alkali diffusion, internal friction, viscosity and chemical durability.
Abstract: The mixed alkali effect in glass refers to the large, orders of magnitude, changes in many properties when a second alkali oxide is added. Properties most affected are those associated with alkali ion movement such as electrical conductivity and loss, alkali diffusion, internal friction, viscosity and chemical durability. The compositional dependence of these properties is briefly reviewed and examples are given of the relevance of the mixed alkali effect to the manufacture of commercial glasses. Also reviewed are various theories for this scientifically interesting effect.
719 citations
TL;DR: In this paper, a mathematical model for sound transmission into a stiffened cylindrical shell was presented for a typical narrow-bodied jet in cruising flight, where the stiffening effect of the ring frames and stringers was approximated by a'smeared-stiffener theory which includes the eccentricity of the stiffeners.
121 citations
TL;DR: In this paper, an investigation has been made to determine the effects that additions of glue and antimony have on the electrowinning of zinc from acid sulphate solutions, in particular, the zinc crystal growth and cathode current efficiencies were studied in an attempt to establish a correlation between morphology and the nature of the additives.
Abstract: An investigation has been made to determine the effects that additions of glue and antimony have on the electrowinning of zinc from acid sulphate solutions. In particular, the zinc crystal growth and cathode current efficiencies were studied in an attempt to establish a correlation between morphology and the nature of the additives. Operating conditions of 55 A ft−2#x002A; and 35°C were used for most of the experiments with electrolyte concentrations of approximately 55 gl−1 zinc and 150 gl−1 H2SO4. Additional runs were made at 40,75 and 100 Aft−2 at 30,40 and 50°C in order to verify certain trends. Primarily by means of scanning electron microscopy (SEM) techniques, it was possible to categorize deposit morphologies according to the type and concentration of the additives. The general effect of antimony was to refine the grain size and cause the basal plane platelets to lie parallel to the substrate. Glue also caused some refinement, but caused the platelets to become aligned perpendicular to the substrate. Level deposits were obtained in the latter case, which would effectively prevent dendritic growths. A relationship between the relative amounts of glue and antimony in solution and the current efficiency was also obtained.
80 citations
TL;DR: In this paper, the time evolution of the KLL Auger spectrum of carbon as a function of temperature is used to derive the kinetics of the surface diffusion and bulk-to-surface precipitation of carbon on polycrystalline nickel.
73 citations
TL;DR: In this article, the elastic magnetic neutron cross section from a single crystal of USb has been measured in the antiferromagnetic state (type-I ordering, T/sub N/ = 241.2 K) for all Bragg reflections with sintheta/lambda = kappa/4..pi.. < 0.811 A/sup -1/.
Abstract: The elastic magnetic neutron cross section from a single crystal of USb has been measured in the antiferromagnetic state (type-I ordering, T/sub N/ = 241.2 K) for all Bragg reflections with sintheta/lambda = kappa/4..pi.. < 0.811 A/sup -1/. By using the tensor-operator method, we have calculated the theoretical cross sections from a number of possible ground-state configurations and compared them with experiment. Excellent agreement is obtained for one model only; a 5f/sup 3/ ionic state (U/sup 3 +/) with a GAMMA/sup 1/8 crystal-field ground state. Such a crystal-field ground state implies that the fourth-order crystal-field potential V/sub 4/ is negative, which is the opposite sign to that found in the analogous 4f/sup 3/ neodymium compounds. By measuring the temperature dependence of the magnetic scattering as a function of kappa-arrow-right, the scattering vector, we have been able to estimate the magnitude of the crystal-field parameters as V/sub 4/ approx. = - 300 K, and V/sub 6/ - 15 K. The implications of this first unambiguous identification of the electronic ground state in a metallic actinide compound are discussed. (AIP)
67 citations
TL;DR: In this paper, a spectrum-fitting technique was used to extract cross-sections for the processes H/sup +/+ + H(1s) and H* from the energy-loss spectra of 15- to 200-keV protons by using a spectrum fitting technique.
Abstract: Cross sections for the processes H/sup +/ + H(1s) ..-->.. H/sup +/ + H* (n = 2, 3, 4) have been extracted from the energy-loss spectra of 15- to 200-keV protons by using a spectrum-fitting technique. Absolute cross sections have been obtained by normalization of the spectra to the theoretical cross section through the use of the Born approximation at 200 keV. The cross-section curves are very similar in shape with maxima at 60 keV. The results have been compared with available theoretical calculations. The n = 2 and n = 3 cross-section measurements are in very good agreement in curve shape with Glauber-approximation calculations. (AIP)
63 citations
TL;DR: In this paper, the adaptive random search procedure is applied to the optimization of a variety of chemical engineering problems, including optimization of chemical processes by flow sheet simulation, where the independent variables are represented as random variables described by probability distributions.
Abstract: Random search procedures have recently been successfully applied to the optimization of a variety of chemical engineering problems, including optimization of chemical processes by flow sheet simulation. These procedures represent the independent variables as random variables described by probability distributions. The adaptive random search procedure centers the distribution for each variable about the best search point found and examines this region for a better point. Thus, this technique has the ability of continuously moving the search region toward the optimum, which is particularly advantageous in following constraints.
This study examines the efficiency of the adaptive random search technique as applied to six different problems, which have been previously solved by various other techniques.
48 citations
TL;DR: In this paper, it was shown that xenon isotopes in meteorites and in outer regions of the Sun contain debris from a supernova which exploded in the vicinity of the present Solar System.
Abstract: We suggest that xenon isotopes in meteorites and in outer regions of the Sun contain debris from a supernova which exploded in the vicinity of the present Solar System, and we conclude that xenon in the outer planets is enriched in this supernova debris.
46 citations
01 Dec 1976-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: A cyclic voltammetric technique has been developed for approximating the quantities of active chemical species present in zinc sulfate electrolytes as discussed by the authors, which can be used to compare with results obtained when various organic and inorganic additions were made.
Abstract: A cyclic voltammetric technique has been developed for approximating the quantities of active chemical species present in zinc sulfate electrolytes. The experimental apparatus consisted of a Pyrex “H” cell, an aluminum cathode encased in a Teflon holder, a carbon anode and a mercurous sulfate reference electrode. Voltammograms were obtained using industrial, purified neutral leach solution (Cominco Ltd., Trail, BC) acidified to give a final concentration of 0.77 M Zn++ and 1 M H2SO4. The polarization curves were then evaluated and used as reference standards to compare with results obtained when various organic and inorganic additions were made. The deposit morphologies obtained for short-time cathodic cycles were also studied with the aid of a Scanning Electron Microscope. Changes in concentrations of glue in the 5 to 10 ppm range and of antimony in the 5 to 10 ppb range were detected using the techniques described.
45 citations
43 citations
TL;DR: In this paper, numerical solutions of Navier-Stokes equations for separated flows around a circular cylinder at Reynolds numbers 40, 80, and 200 were obtained by using three finite-difference techniques.
Abstract: Numerical solutions of the Navier-Stokes equations were obtained for separated flows around a circular cylinder at Reynolds numbers 40, 80, and 200. The flowfields were obtained by using three finite-difference techniques. The implicit scheme solved by matrix factorizations gave the best accuracy and used the least computer time. The flow pattern in the recirculating region of a circular cylinder begins to oscillate as the Reynolds number exceeds 40. The calculated drag coefficients, separation angles, and Strouhal numbers were compared with available experimental data. Computational inaccuracy resulting from numerical approximations needs to be identified before a complicated flow phenomenon can be realistically analyzed.
TL;DR: Experimental and structural details are presented for the addition of bis -methoxy carbonyl carbene to a number of olefins employing homogeneous and heterogeneous catalyzed decompositions of dimethyl diazomalonate by copper and silver salts as mentioned in this paper.
TL;DR: In this article, the existence of two paths to the title processes which arise from a common intermediate is demonstrated. But neither of these paths contain N2, although it is felt that a cupro-cyclobutane intermediate is the most probable intermediate before product partitioning.
TL;DR: In this article, the Hanle effect was used to measure the lifetime of the first $ 2 P{\frac{3}{2}}$ state of Mgu, Cau, Znu, Sru, Cdu, and Bau.
Abstract: Radiative lifetimes of the first $^{2}P_{\frac{3}{2}}$ state of Mgu, Cau, Znu, Sru, Cdu, and Bau are reported as measured by the Hanle effect in a fast-flowing helium afterglow. They are, respectively, 3.65(0.12), 6.61(0.30), 2.4(0.3), 6.64(0.10), 2.86(0.25), 6.78(0.40) in units of ${10}^{\ensuremath{-}9}$ sec. The ions in the afterglow are created by Penning ionization of the neutral metal atoms, thus providing a steady-state, field-free region for observation. Comparisons are made with measurements by other methods, and discrepancies are discussed.
TL;DR: In this paper, it was shown that a simple tensile load produces a simple extension provided the empirical inequalities (Truesdell and Noll [1], eqn. 51.27) hold.
Abstract: It is shown that a simple tensile load produces a simple extension provided the empirical inequalities (Truesdell and Noll [1], eqn. 51.27) hold.
TL;DR: The subject of homogeneous metal-salt-catalyzed carbenoid reactions has received surprisingly little attention and the major studies, originating in only a few research groups, have only appeared during the last ten years as discussed by the authors.
TL;DR: In this paper, partial rate data for the decomposition of diazo acetic ester and dimethyl diazomalonate, in the presence of soluble copper salts and cyclohexene, revealed the existence of two paths to carbene dimer formation.
TL;DR: In this paper, the Hanle method was used to measure the radiative lifetime of the 17992-,25068-,28857-, 37414-, 40564-, and 44017-${\mathrm{cm}}^{\ensuremath{-}1}$ neutral levels and the 30392-${mm{cm}) ion level of Yb in a fast-flowing He system.
Abstract: The radiative lifetimes of the 17992-,25068-,28857-, 37414-, 40564-, and 44017-${\mathrm{cm}}^{\ensuremath{-}1}$ neutral levels and the 30392-${\mathrm{cm}}^{\ensuremath{-}1}$ ion level of Yb have been measured by the Hanle method in a fast-flowing He system. The lifetimes (in units of ${10}^{\ensuremath{-}9}$ sec) were found to be 820(20), 5.12(0.12), 14.4(0.4), 77.4(6.0), 9.32(0.6), 39.1(3.5), and 5.8(0.6), respectively. In a flowing system with He as a buffer gas the alignment depolarization cross sections with Yb were obtained and are reported here for the first time. They are (in units of ${10}^{\ensuremath{-}15}$ ${\mathrm{cm}}^{2}$) 5.0(1.0), 5.9(1.0), 5.9(1.2), 17.9(2.0), 28.2(3.0), 5.16(4.0), and 7.2(2.5), respectively.
TL;DR: In this paper, the propagation distance of surface electromagnetic waves on a copper-cuprous oxide-air system was measured using two prism couplers, for oxide thickness between 20 A and 2000 A, and wavelengths from 9.2 μm to 10.8 μm.
TL;DR: In this article, the problem of indentation by a rigid cylinder of a thermovisco-elastic layer bonded to a uniformly rotating rigid cylinder was studied by the finite element method and various approximations necessary to reduce the problem to one of tractable size were discussed in some detail.
Abstract: SUMMARY The coupled thermomechanical behaviour of a layer of thermorheologically simple material bonded to a uniformly rotating rigid cylinder and indented by another rigid cylinder is studied by the finite element method. The various approximations necessary to reduce the problem to one of tractable size and the computational methods used are discussed in some detail. The complete thermal, deformation and stress fields may be computed. Some results, computed for a grid using 'rectangular' elements, presented graphically include the temperature distribution, the stress distribution near the bond surface, the contact pressure distribution and the asymmetric surface deformation of the rubberlike laver. In this paper we study the problem of the indentation, by a rigid cylinder, of a thermovisco- elastic layer bonded to a uniformly rotating rigid cylinder. Such a situation occurs in various industrial settings, e.g. the paper and pulp industry where both cylinders are of comparable diameters. Other industrial applications may involve quite different geometries. The approach presented here is applicable to all possible geometries. A schematic diagram of the system studied is shown in Figure 1. We assume that sufficient time has elapsed since the start up of the operation for the transient effects to become negligible and consequently we study the steady-state problem where the rubber-like layer has a constant angular velocity of.Q revolutions per sec. We briefly review the earlier work done on other aspects of the present problem. The analytic elastostatic1.2 and elastodynamic3 studies as well as the elastostatic numerical4 studies show that stresses at the bond surface decay to nearly zero values at points far from the contact region. In addition, the effects of the frictional force at the contact surface, for moderate values of the coefficient of friction, are not significant.2 Furthermore, dynamic forces do not cause any asym- metry in the deformation3 and numerical calculations, not included in Reference 3, show that the effect of these forces on the stress distribution is negligible for practical geometries and angular velocities.
TL;DR: In this paper, a nonlinear mathematical programming method of feasible directions is used to minimize the weight of the structure subject to the aforementioned linear and nonlinear constraints, including damping, the PΔ effect, static girder loads, static column loads and girder shears transferred to the columns.
Abstract: A method to optimize the weight of plane frames subjected to dynamic loads is presented. Various considerations for rigid frame design include damping, the PΔ effect, static girder loads, static column loads and girder shears transferred to the columns. A finite difference approach is presente to evaluate a shock spectrum which is used in conjunction with modal superposition to obtain the peak upper bound dynamic displacements and stresses for multistory and multibay frames. The displacement method is used for the structural matrix formulation from which the optimization process is shown in relation to the change of the design variables in the condensed stiffness matrix. A direct, nonlinear mathematical programming method of feasible directions is used to minimize the weight of the structure subject to the aforementioned linear and nonlinear constraints. Several applications of the proposed method are presented to show the design process related to the active constraints and the significant effects of various considerations on optimum design.
TL;DR: In this paper, a finite element approach has been developed to simulate bit penetration from bit-rock interaction to chip formation, and the simulation results of the blunt point bit are in reasonable agreement with penetration experiments on Limestone.
TL;DR: In this article, the mean square amplitudes (MSA) and mean square velocities (MSV) of thermal vibrations have been calculated for the (001) surface of LiF, MgO, NaF, NaCl, NaI, RbF, and RbCl, using shell models.
TL;DR: In this article, the authors show that dispersion curves alone present an inadequate summary of the data and extend this result to other materials and show that the dispersion curve alone can be insufficient.
Abstract: Surface-electromagnetic-wave dispersion curves are usually calculated using a simple equation derived from Maxwell's equations and boundary conditions. When complex dielectric functions are used for the two media, the component of the propagation vector along the surface, ${k}_{x}$, becomes infinite as the frequency approaches the surface polariton frequency ${\ensuremath{\omega}}_{s}$ if $\ensuremath{\omega}$ is considered complex and ${k}_{x}$ is real. On the other hand, if ${k}_{x}$ is considered complex and $\ensuremath{\omega}$ real, the dispersion curves bend back toward smaller ${k}_{x}$ as $\ensuremath{\omega}$ approaches ${\ensuremath{\omega}}_{s}$. We have previously demonstrated that both types of behavior can be obtained from attenuated-total-reflection measurements of silver. We now extend this result to other materials and show that dispersion curves alone present an inadequate summary of the data.
TL;DR: In this paper, the influence of a liquid crystal on the Van der Waals potential for the coalescence of emulsion droplets was calculated, and it was shown that liquid crystals are more stable than liquid crystals.
Abstract: The influence of a liquid crystal on the Van der Waals potential for the coalescence of emulsion droplets was calculated.
TL;DR: In this article, a method of modeling a system of roof bolts is presented, which is then applied in the determination of the state of stress due to bolt tightening, and the analysis showed that the grout annulus transferred nearly all of the bolt load 3nto the rock within a distance of 12 hole diameters from the point of bolt load application.