Showing papers by "Missouri University of Science and Technology published in 1969"
TL;DR: The atomic positions in perovskitic BiFeO3 were determined using X-ray single crystal diffraction and neutron powder diffraction as discussed by the authors, and the space group is R3c, the rhombohedral unit cell containing 2 formula units of BiO3.
563 citations
TL;DR: In this article, a theoretical development of the Navier-Stokes equation through analysis of the dimensionless form of Navier Stokes equation is presented, which shows that energy losses at high-flow velocities in porous medium are a result of convective acceleration effects not turbulent effects.
Abstract: Many investigators are concerned about the validity of the Forchheimer equation which represents the relationship between the velocity of flow and pressure gradient in porous media. A theoretical development of this equation through analysis of the dimensionless form of the Navier-Stokes equation is presented. It shows that energy losses at high-flow velocities in porous medium are a result of convective acceleration effects not turbulent effects. In addition, two dimensionless terms representing the flow behavior are defined and evaluated. It is shown that a constant could be used to represent the geometric properties of the medium and that a characteristic length representative of the flow exist. Both of these quantities are easily evaluated through hydraulic measurements of gradients and flow velocities. Experimental data from many sources were used to evaluate the theoretical results.
157 citations
TL;DR: In this paper, the internal friction of silicate glasses containing mixtures of Li-Na, Li-K, Li Rb, Li C, Li N, K-Rb, Na Rb and Na C was measured from -180° to 500°C at a frequency of 0.4 Hz.
Abstract: The internal friction of silicate glasses containing mixtures of Li-Na, Li-K, Li-Rb, Li-Cs, Na-K, Na-Rb, Na-Cs, and K-Rb was measured from -180° to 500°C at a frequency of 0.4 Hz. Values for the density, index of refraction, and dynamic shear modulus are also reported. With small additions of a second alkali, a new internal friction peak was observed in addition to the two peaks originally present in the glasses containing only one alkali. The magnitude of this new peak was especially sensitive to small amounts (less than 1 mol%) of a second alkali. Activation energies are given for the alkali peak in Li-Cs glasses and for the new internal friction peak in Li-Na glasses.
132 citations
TL;DR: The atomic positions in perovskitic PbZr x Ti 1− x O 3 were determined for x = 0.9 and X-ray and neutron diffraction.
130 citations
TL;DR: In this article, the nucleation rate of droplets from water vapor in a helium atmosphere was measured with an expansion cloud chamber as a function of temperature, supersaturation, and sensitive time.
77 citations
TL;DR: In this article, rates of evaporation and mass transfer of water vapor from a heated salt solution through a water repellent porous membrane to a cooled water condensate were investigated.
Abstract: This study concerns rates of evaporation and mass transfer of water vapor from a heated salt solution through a water repellent porous membrane to a cooled water condensate. This transfer is a result of temperature differences and corresponding vapor pressure differences across the membrane. Three groups of experiments were carried out which indicate that the major factor influencing the rates of transfer is diffusion through a stagnant gas in the membrane pores. However, an equation considering film heat transfer coefficients, membrane thermal conductivity, and an empiricial correction based on temperature driving force appears to be necessary for representing all the data. The empirical correction appears to be related to internal condensation and possibly diffusion along surfaces.
46 citations
TL;DR: In this article, the internal friction of R2O·Al2O3·6SiO2 glasses was measured from-180° to 700°C at 0.4 Hz.
Abstract: The internal friction of R2O·Al2O3·6SiO2 glasses was measured from-180° to 700°C at 0.4 Hz. Glasses containing Li2O or Na2O exhibited only the one internal friction peak characteristic of the stress-induced movement of the alkali ions. Substitution of a second alkali resulted in two significant changes in the internal friction: (1) a rapid reduction in the magnitude of the original alkali peak and (2) the appearance of a new internal friction peak whose magnitude was especially sensitive to the concentration of the second alkali. Each combination of two alkali ions resulted in a new peak, with peaks being observed for the combinations Li-Na, Na-K, and Li-K. A mechanical damping spectrum is predicted for aluminosilicate glasses containing more than two alkali ions.
23 citations
TL;DR: In this paper, the anomalous properties of water condensed in quartz capillaries from incompletely saturated vapour in the absence of air exhibits anomalous property. But, the authors point out that anomalous water occurs only on areas free of a wetting film, indicating an influence of the quartz surface.
Abstract: DERJAGUIN1 reported that water condensed in quartz capillaries from incompletely saturated vapour in the absence of air exhibits anomalous properties. Condensation of anomalous water occurs only on areas free of a wetting film, indicating an influence of the quartz surface. Compared with normal water, anomalous water has a lower vapour pressure, a density of 1.2–1.3 g cm−3, fifteen times greater viscosity, and one and a half times the thermal expansion coefficient2. The equilibrium vapour pressure is independent of the capillary diameter, indicating that the anomalous properties are a result of a modification in structure of the liquid phase rather than a purely surface phenomenon.
18 citations
15 citations
TL;DR: In this article, an analysis of the strongly coupled heat and mass transfer processes which result from sublimation of mass from the walls of a duct into a flowing gas, the latent heat being provided solely by convective transfer from the gas, is performed.
Abstract: An analysis is performed of the strongly coupled heat and mass transfer processes which result from sublimation of mass from the walls of a duct into a flowing gas, the latent heat being provided solely by convective transfer from the gas. The flow is assumed to be laminar and hydrodynamically developed. Results are given for the streamward variations of the bulk and wall temperatures and mass fractions, of the heat and mass transfer rates, and of the local heat transfer coefficient. Representative temperature and mass fraction profiles are also presented. Entrance lengths characterizing the near approach to fully developed conditions are tabulated. Comparisons are made of the present results (based on a parabolic velocity profile) with those based on a slug flow velocity profile. A subsidiary analysis using the Levěque model is also performed and the results compared with those of the principal solution.
12 citations
TL;DR: In this article, a Reynolds type heating experiment on neutron irradiated silicates from Toluca indicates that the high temperatures sites began to retain radiogenic 129Xe when the 129I127I ratio was (1.4±0.4) × 10−3.
TL;DR: In this paper, a closed form solution to the integral momentum equation is obtained by the method of characteristics to determine boundary layer thickness, entrance length, velocity profile, and pressure gradient.
Abstract: Suddenly started laminar flow in the entrance region of a circular tube, with constant inlet velocity, is investigated analytically by using integral momentum approach. A closed form solution to the integral momentum equation is obtained by the method of characteristics to determine boundary layer thickness, entrance length, velocity profile, and pressure gradient.
TL;DR: In this paper, the entropy of the mixed state of type-II superconductors with low entropy was studied for the alloys, and it was shown that the entropy depends only on temperature, and that the temperature dependence increases linearly with $B$ from its value for the superconducting state until it drops discontinuously to its normal state value at ${H}_{c2}$.
Abstract: The entropy of the mixed state of type-II superconductors with low $\ensuremath{\kappa}(\ensuremath{\sim}1)$ is studied for the alloys ${\mathrm{Pb}}_{0.96}$${\mathrm{Tl}}_{0.04}$ and ${\mathrm{In}}_{0.88}$${\mathrm{Sn}}_{0.12}$. The current theories are reviewed for approximations valid near ${H}_{c1}$ and near ${H}_{c2}$. The experiments show for the most reversible sample (${\mathrm{Pb}}_{0.96}$${\mathrm{Tl}}_{0.04}$) that ${(\frac{\ensuremath{\partial}S}{\ensuremath{\partial}B})}_{T}$ of the mixed state depends only on temperature, and that ${(\frac{\ensuremath{\partial}S}{\ensuremath{\partial}T})}_{B}$ increases linearly with $B$ from its value for the superconducting state until it drops discontinuously to its normal state value at ${H}_{c2}$. There is no abrupt increase in the specific heat at constant magnetic induction near ${H}_{c1}$ as is observed in the specific heat at constant applied magnetic field. A method of determining the thermodynamic critical field of an irreversible sample without assuming a parabolic form is discussed and applied to the data. The thermodynamic critical field determined in this way is used to calculate ${\ensuremath{\kappa}}_{1}$ and ${\ensuremath{\kappa}}_{2}$. The parameters are very nearly equal for ${\mathrm{Pb}}_{0.96}$${\mathrm{Tl}}_{0.04}$ with a temperature dependence of ${(1+{t}^{2})}^{\frac{\ensuremath{-}1}{2}}$. Measurements of ${(\frac{\ensuremath{\partial}S}{\ensuremath{\partial}B})}_{T}$ are also reported on the type-I superconductors Sn and Pb. The conclusion, as expected, is that ${(\frac{\ensuremath{\partial}S}{\ensuremath{\partial}B})}_{T}$ in the intermediate state depends on the temperature only.
TL;DR: In this article, the effect of halide anions on the anodic dissolution of polycrystalline Be at various c.d.s has been studied in aqueous solutions.
TL;DR: N,N-Dimethyltryptamine is also converted to indole-3-acetic acid but the branched-chain secondary amines β-methyl- and β-ethylt Kryptophan are not metabolized.
TL;DR: In this paper, a combination of experimental and analytical methods is used to determine the velocity of fluid in a starting flow process in a circular tube, and the developing pressure gradient, measured experimentally in the fully developed region, is expressed as a function of time.
Abstract: A combination of experimental and analytical methods is used to determine the velocity of fluid in a starting flow process in a circular tube. The developing pressure gradient, measured experimentally in the fully developed region, is expressed as a function of time and is used in the solution of Navier-Stockes equations for axial flow in a circular tube. Expressions for velocity in time and space and the average discharge are obtained by Laplace's transformation technique. The velocity profiles and discharge under time-dependent pressure gradient are compared with those under constant pressure gradient. Significant differences between the velocities are found during the flow establishment, and the assumption of constant pressure gradient in the period of flow establishment, as considered in a number of studies, appears to be unsatisfactory.
TL;DR: In this article, the moments of a Noncentral t and Noncentral F distribution were discussed, and the authors proposed a noncentral t-distribution with noncentral f distribution.
Abstract: (1969). Moments of a Noncentral t and Noncentral F-distribution. The American Statistician: Vol. 23, No. 4, pp. 33-34.
TL;DR: In this paper, the anamolous behavior of neutron-induced defect clusters in the high field space charge region of silicon p-n junctions was investigated and an electric field strength dependence for the defect clusters was found.
Abstract: The anamolous behavior of neutron-induced defect clusters in the high field space-charge region of silicon p-n junctions is investigated. The space-charge region recombination current variation with neutron fluence and the junction electric field strength present during irradiation is examined and an electric field strength dependence for the defect clusters is found to exist. The space-charge region rate of volume damage introduction is observed to be a function of both neutron fluence and the junction electric field strength present during irradiation. An empirical expresion for the dependence of the rate of volume damage introduction on fluence and junction field strength present during irradiation is developed. Possible mechanisms for the observed field dependence are discussed.
TL;DR: In this article, an analysis of xenon in two olivine-hypersthene chondrites showed that radiogenic xenon-129 resides in both the chondrules and in the matrix material.
01 Jan 1969
TL;DR: In this article, the isotope effect of carbon diffusion in dilute iron silicon alloys containing 28 Si and 30 Si has been measured below room temperature using the disaccommodation technique.
TL;DR: In this paper, the effect of Cr3+ concentration in an MgO crystal lattice on the crystal field splitting energy, 10 Dq, and on other electronic transitions was studied.
Abstract: The effect of Cr3+ concentration in an MgO crystal lattice on the crystal field splitting energy, 10 Dq, and on other electronic transitions was studied. Optical reflectance spectra showed a linear increase in 10 Dq with increasing Cr3+ concentration up to the limit of solid solubility. The Racah parameter, B, decreased and the energy of the 4T1g→4A2g transition increased with increasing Cr3+ concentration. The increase in 10 Dq was related to the decrease in lattice parameter.
TL;DR: In this article, it was found that layers of tungsten carbide form on Tungsten wires processed under ultra-high vacuum and the carbide is formed from carbon impurities in the volume of material.
Abstract: It has been found that layers of tungsten carbide form on tungsten wires processed under ultra-high vacuum. The carbide is formed from carbon impurities in the volume of material.
01 Jan 1969
TL;DR: In this article, the authors studied the anodie behavior of mo1ybdenum in alkaline so1utions, pH 9.5, and found that the anodic behavior of the material is similar to that of graphite.
Abstract: The purpose of this investigation was to study the anodie behavior of mo1ybdenum in alkaline so1utions, pH 9.5 -
TL;DR: In this article, a microinterferometric method was used to determine the concentration profiles in the infinite field unsteady state diffusion of D-Glucose in aqueous polymer solutions.
Abstract: A microinterferometric method was used to determine the concentration profiles in the infinite field unsteady state diffusion of D-Glucose in aqueous polymer solutions. Pseudo binary diffusion coefficients were determined as a function of reduced concentration both with and without the effect of liquid volume change during diffusion being considered. The systems studied were D-Glucose in aqueous Carboxymethylcellulose and D-Glucose in aqueous Carboxypolymethylene solutions. Solute concentration ranged from nearly zero to about 9% by weight D-Glucose in the aqueous polymer solutions.
01 Jan 1969
TL;DR: The results of an experimental investigation to determine the effect of relatively high amplitude and low frequency harmonic oscillations of a sphere on nucleate pool boiling of liquid nitrogen at atmospheric pressure are presented in this paper.
Abstract: The results of an experimental Investigation to determine the effect of relatively high amplitude and low frequency harmonic oscillations of a sphere on nucleate pool boiling of liquid nitrogen at atmospheric pressure are presented in this paper. As far as is known, there are no other steady-state nucleate boiling data for a spherical geometry available at this time. Previous oscillatory investigations have been conducted using wires and relatively small diameter tubes at high frequency and low amplitudes.