Showing papers by "Missouri University of Science and Technology published in 1981"
342 citations
TL;DR: In this article, the authors demonstrate that the abnormally large hysteresis effect observed in advancing and receding contact angles of water on some polymer surfaces can be attributed to the reorientation of hydrophilic moieties of polymer molecules at the surface.
Abstract: The contact angle of a water droplet on the surface of a solid polymer or hydrogel (water-swollen three-dimensional network) depends on whether a hydrophilic moiety of the polymer molecule is oriented towards the air interface or towards the bulk of the solid, but not on the hydrophilicity of the molecule. Therefore, the short-range rotational mobility of a polymer molecule has a major influence on the apparent hydrophilicity of a polymer surface as measured by the contact angle of water. By the came principle, the abnormally large hysteresis effect observed in advancing and receding contact angles of water on some polymer surfaces can be attributed to the reorientation of hydrophilic moieties of polymer molecules at the surface. These factors are demonstrated by selected polymer surfaces with different degrees of mobility at the polymer-air interface.
312 citations
01 Jul 1981
TL;DR: Attention is given to the following topics: systems and signal analysis, random signal theory, information and channel capacity, baseband data transmission, analog signal transmission, noise in analog communication systems, digital carrier modulation schemes, error control coding, and the digital transmission of analog signals.
Abstract: Add this article to private library Remove from private library Submit corrections to this record View record in the new ADS The book presents an introductory treatment of digital and analog communication systems with emphasis on digital systems. Attention is given to the following topics: systems and signal analysis, random signal theory, information and channel capacity, baseband data transmission, analog signal transmission, noise in analog communication systems, digital carrier modulation schemes, error control coding, and the digital transmission of analog signals. Bibtex entry for this abstract Preferred format for this abstract
245 citations
TL;DR: In this article, the authors provide further evidence on the development and application of the iterative bidding technique used to assess environmental impacts, and examine theoretically and empirically the effect of the survey technique, the questionnaire information structure, and the bidding procedure starting point.
193 citations
TL;DR: In this article, the maximum normal-strain theory for fracture is modified as a new approach to the study of the angled crack problem, and the authors present predictions on the direction of initial crack extension and the fracture strength for plates containing a slit crack as well as those with an elliptic crack under uniform edge stresses.
167 citations
TL;DR: This paper presents a directed graph, G, which consists of a set of nodes, V which represent "blocks" of groups of code, and a set E, of edges which corresponds to the flow of control among the various nodes.
Abstract: For the past several years an accepted method of determining the complexity of computer programs has involved developing a direct graph, G=(V,E) which represents the flow of control of the program. The directed graph, G consists of a set of nodes, V which represent "blocks" of groups of code, and a set E, of edges which corresponds to the flow of control among the various nodes. The graph is usually restricted to having one initial node which is always executed first. In addition, each block has two properties:
148 citations
TL;DR: The ability of the more predictive stimulus, the tone, to overshadow the contextual cues was determined by the tone’s temporal contiguity with the footshock, which increased with increases in the trace duration.
Abstract: Rats were given tone-footshock pairings with a 0-, 10-, or 30-sec trace interval between tone offset and shock onset. Half the rats within each trace interval were tested for their conditioned fear of the tone through a lick suppression procedure; the remaining rats were evaluated for their fear of the background or contextual cues through their avoidance of the compartment in which conditioning had occurred. Less conditioning was observed to the tone with increasing trace intervals. However, conditioned fear of the context increased with increases in the trace duration. The ability of the more predictive stimulus, the tone, to overshadow the contextual cues was determined by the tone’s temporal contiguity with the footshock. The need to incorporate temporal parameters within current theories of conditioning is discussed.
107 citations
01 Jan 1981
94 citations
TL;DR: In this article, the crystallographic and the magnetic structures of Y(Mn1−xFex)12 intermetallic compounds were investigated and the solid solubility limit (x = 0.67) of Fe in YMn12.
Abstract: The crystallographic and the magnetic structures of Y(Mn1−xFex)12 intermetallic compounds were investigated. They crystallize in the ThMn12 structure type. The Y atoms occupy the 2(a) sites and the transition metals are distributed on 3 nonequivalent sites 8i, 8j, and 8f. We have determined the solid solubility limit (x = 0.67) of Fe in YMn12. Neutron diffraction spectra at different temperatures have been used to study the nuclear and magnetic structure of Y(Mn0.7Fe0.3)12 and Y(Mn0.4Fe0.6)12. The Mn and Fe atoms are found to exhibit strong site preference with the i site favoring Mn atoms and the f site Fe atoms. Accordingly the instability of the RFe12 phase can be explained on the basis of the preferential atomic ordering observed in the ternary compounds. Based on the results of magnetic structure refinements using the Rietveld profiling method, antiferromagnetic, noncollinear structures are proposed for these two compounds.
86 citations
01 Nov 1981
TL;DR: In this paper, the authors used low-angle X-ray scattering to determine the composition range of stability and geometrical dimensions of lecithin and alkanediols.
Abstract: Lamellar liquid crystals from lecithin and alkanediols were studied to determine the composition range of stability and geometrical dimensions using low-angle X-ray scattering. An estimation of the dislocation pattern was made from the optical pattern in polarized light. The ethylene glycol gave the widest range of stability for the lamellar structure, the range being reduced toward heptanediol, the longest member to give liquid crystals. The interlayer spacing was reduced with increasing chain length of the diol and the dislocation pattern remained identical.
84 citations
TL;DR: In this article, a finite element scheme based on both the Galerkin method and the residual least squares method with eight noded isoparametric elements is described for the solution of the problem of acoustic transmission through a non-uniform duct carrying a high speed subsonic compressible flow.
TL;DR: In this article, a glow discharge polymer was applied to polymers and metal surfaces to measure the adhesion of glow discharge polymers to metals and polymers in an adhesive joint, which was measured by lap-shear test and immersion in hot water for an extended time.
Abstract: Adhesion of glow discharge polymers to metals and polymers in an adhesive joint was measured by lap-shear test and immersion in hot water of 70°C °C for an extended time. A glow discharge polymer was deposited onto polymers [polyethylene and poly(tetrafluoroethylene)] and metals (aluminum and stainless steel) prior to when the polymer and metal were joined. It is found that the lap-shear strength is enhanced by coating the surfaces of these substrates with plasma film produced from methane, ethylene, and acetylene, and that deterioration of the adhesive bonding part, when immersed in hot water of 70°C, is strongly dependent on the gas used as well as operational conditions where a polymer film is formed. The adhesion of a polymer produced from methane on the polymer and metal is strong enough to apply for durable, adhesive joints.
TL;DR: In this article, chi-squared, Student's t and noncentral t approximations for certain functions of the maximum likelihood estimators of the parameters of the extreme value distribution were studied by comparing them to existing Monte Carlo simulation results.
Abstract: One form of the generalized gamma distribution brings out an association between the normal distribution and the extreme-value distribution. This relationship suggests chi-squared, Student's t and noncentral t approximations for certain functions of the maximum likelihood estimators of the parameters of the extreme-value distribution. The accuracy of these approximations is studied by comparing them to existing Monte Carlo simulation results. These approximations provide simple procedures for obtaining approximate confidence intervals for the parameters, tolerance limits, and confidence limits on reliability for the Weibull or extremevalue distribution.
TL;DR: This article covers the following topics: reaction types and their interaction with mixing; closure of the Reynolds equations for mixing and reactions; application to complex geometries; random coalescence-dispersion modelling; and selection of model complexity.
Abstract: Applications of the fundamentals of turbulent mixing become clear once those fundamentals are understood. The first article in this series presented those fundamentals, in order to show how to apply turbulent mixing fundamentals modelling and scaleup, this article covers the following topics: 1. reaction types and their interaction with mixing; 2. closure of the Reynolds equations for mixing and reactions; 3. application to complex geometries; 4. random coalescence-dispersion modelling; 5. application to complex chemistry. The most difficult problem in applying our knowledge of turbulence to mixer modelling and scaleup is the choice of model complexity. The levels of model complexity available and how to apply them to various problems are presented following the introduction.
TL;DR: The dimer model gave more accurate predictions, with a maximum deviation of 4.4% between observed and predicted solubilities in all systems studied, compared to the predictions of equations developed previously for solubility in systems of purely nonspecific interactions.
TL;DR: In this paper, the authors show how the normally generated third-harmonic voltage can be used to protect the lower ten to twenty percent of generator stator windings against ground faults, and a method of determining the applicability of the scheme to a given machine is described which takes into account the design of the generator and its externally connected apparatus.
Abstract: The paper shows how the normally generated third-harmonic voltage can be used to protect the lower ten to twenty percent of generator stator windings against ground faults. A method of determining the applicability of the scheme to a given machine is described which takes into account the design of the generator and its externally connected apparatus. The effects of finite resistence ground faults are also investigated and other advantages of the scheme, such as protection of the neutral, are also highlighted.
01 Jan 1981
TL;DR: The application of a thin coating of glow-discharge polymerized methane under a thicker Parylene-N coating improved the adhesion of the latter to the underlying substrate in isotonic sodium chloride solution and during accelerated testing conditions done by boiling.
TL;DR: In this article, exact integral equations are derived describing the source function and radiative flux in a two-dimensional, radially infinite cylindrical medium which scatters anisotropically.
Abstract: Exact integral equations are derived describing the source function and radiative flux in a two-dimensional, radially infinite cylindrical medium which scatters anisotropically. The problem is two-dimensional and cylindrical because of axisymmetric loading. Radially varying collimated radiation is incident normal to the upper surface while the lower boundary has no radiation incident upon it. The scattering phase function is represented by a spike in the forward direction plus a series of Legendre polynomials. The two-dimensional integral equations are reduced to a one-dimensional form by separating variables for the case when the radial variation of the incident radiation is a Bessel function. The one-dimensional form consists of a system of linear, singular Fredholm integral equations of second kind. Other more complex boundary conditions are shown to be solvable by a superposition of this basic Bessel function case. Diffusely incident radiation is also considered.
TL;DR: In this article, a direct method of determining whether unknown parameters of a dynamical system can be determined uniquely from an input-output experiment is presented, relying on the fact that a completely controllable and completely observable system is parameter identifiable if and only if it is not algebraically equivalent to any other system.
Abstract: A direct method of deciding whether or not the unknown parameters of a dynamical system can be determined uniquely from an input-output experiment is presented. The method relies on the fact that a completely controllable and completely observable system is parameter identifiable if and only if it is not algebraically equivalent to any other system.
TL;DR: Experimentally and theoretically determined differential cross sections are reported for electron capture in collisions of protons with helium atoms for incident proton energies of 25, 30, 50, and 100 keV and for center-of-mass scattering angles of 00 to 20 mrad as mentioned in this paper.
Abstract: Experimentally and theoretically determined differential cross sections are reported for electron capture in collisions of protons with helium atoms for incident proton energies of 25, 30, 50, and 100 keV and for center-of-mass scattering angles of 00 to 20 mrad The magnitudes of the experimentally determined differential cross sections decrease from 10/sup -10/ to 10/sup -12/ cm/sup 2//sr within the 00--08-mrad range of the center-of-mass scattering angle At approximately 08 mrad a distinct change in the slope of the differential cross section is observed The experimental results which are for capture into all bound states of hydrogen are compared with the theoretical results of a calculation for capture into the ground state using the two-state two-center atomic expansion method in the eikonal approximation Good agreement between the theoretical and the experimental results is obtained with a static potential which accounts for screening of the helium nucleus by a single passive electron
TL;DR: Differential cross sections for electron capture in collisions between protons and hydrogen atoms have been experimentally determined for incident proton energies of 25, 60, and 125 keV in the center-of-mass scattering-angle range of 0 --3 mrad as mentioned in this paper.
Abstract: Differential cross sections for electron capture in collisions between protons and hydrogen atoms have been experimentally determined for incident proton energies of 25, 60, and 125 keV in the center-of-mass scattering-angle range of 0 --3 mrad. The experimental results compare more favorably with the results of both a multistate and a two-state calculation than with the results of a continuum distorted-wave-approximation calculation. There is no evidence of a Jackson-Schiff-type minimum.
TL;DR: In this article, the thermally stimulated polarization (TSPC) and depolarization (TSDC) current was used to investigate the sodium ion motion in three sodium silicate glasses and a sodium aluminosilicate glass, and two TSDC peaks were attributed to localized sodiumion movement around a nonbridging oxygen ion, a type of dipolar orientational polarization, and to a longer-range sodium motion leading to interfacial polarization at the immiscible phase boundaries.
Abstract: Sodium-ion motion in three sodium silicate glasses and a sodium aluminosilicate glass was investigated by the thermally stimulated polarization (TSPC) and depolarization (TSDC) current techniques. The two TSDC peaks found in the sodium silicate glasses were attributed to localized sodium-ion movement around a nonbridging oxygen ion, a type of dipolar orientational polarization, and to a longer-range sodium motion leading to interfacial polarization at the immiscible phase boundaries. The high-temperature background (HTB) current corresponded to the sodium motion for dc conductivity and diffusion. The commonly observed dc absorption current was found to be related to the two TSDC peaks.
TL;DR: The Earth's atmosphere was produced by exhaustive degassing of the upper mantle during the first 200My, but the lower mantle has retained an appreciable fraction of its initial inventory of primordial 3 He as discussed by the authors.
Abstract: There is not a 1:1 correspondence of the pages here with those in the published paper " Geochemical Journal 2 The noble gas record of the terrestrial planets The Earth's atmosphere was produced by exhaustive degassing of the upper mantle during the first 200My, but the lower mantle has retained an appreciable fraction of its initial inventory of primordial 3 He. The lower mantle has retained most of its initial inventory of the heavy noble gases, and it is presently accumulating radiogenic 4 He and 40 Ar. Most of the radiogenic 40 Ar in air was produced in the crust during the first 2.5Gy. Extinct radionuclides have augmented the atmospheric inventory of 136 Xe by less than 1% and that of 129 Xe by about 5%. Terrestrial Ar, Kr, and Xe are type-Y, but the He and Ne are of solar wind origin. Terrestrial Xe may not be isotopically unique in the solar system; its composition can be related to that in meteorites by consideration of nucleogenetic heterogeneities and mass dependent fractionation. The atmospheres of the terrestrial planets were produced by exhaustive degassing of specific regions. Observed similarities in the abundance patterns of noble gases in meteorites and in the terrestrial planets rule out elemental fractionation in the evolution of their atmospheres. The degassed portions of Mars, Earth, and Venus are estimated to be 1-2%, 17% and 100%, respectively. The iron cores of these bodies were produced by heterogeneous accretion. INTRODUCTION Investigations of noble gases in meteoritic and lunar samples have played a key role in our understanding of the formation and early history of these extraterrestrial bodies Recently it has been realized that differences in the elemental and isotopic compositions of the noble gases in these objects may also contain important information on the synthesis of the chemical elements and the birth of the solar system (SABU and MANUEL, 1980a). Studies of terrestrial noble gases resulted in several important findings, but no comprehensive understanding of these discoveries has emerged. In this report we review the available data and suggest an outline of the basic features that seem to be emerging for the noble gas record of the terrestrial planets. Early attempts to decipher the Earth's noble gas record were hampered by the following set of widely-accepted assumptions about the distribution of the chemical elements and their isotopes in the primitive nebula: (i) the solar system condensed under conditions …
TL;DR: In this article, the authors used tetramethyltin as a starting compound for the film-forming experiments and showed that the resulting films contain carbon, tin and hydrogen with a carbon-to-tin atomic ratio of 2.5 or less.
TL;DR: In this paper, the problem of transmission of sound through non-uniform ducts carrying a high speed subsonic compressible flow is approached using the method of weighted residuals (MWR) in the form of a modified Galerkin method and the finite element method (FEM).
TL;DR: In this article, the maximum stress criterion for brittle fracture is examined and modified so that it may be applied to both the slit model and the elliptic model for a crack, and then applied this criterion to a study of the angled crack problem for plates with a slit crack as well as those with an elliptic crack.
TL;DR: In this paper, the chemistry and vegetation of wet areas below the Elvins tailings pile in the Old Lead Belt of Missouri were studied, and an apparent diel cycle in aqueous zinc at some sites is of particular interest, as it was not matched by changes in Ca or Cd.
Abstract: An account is given of the chemistry and vegetation of wet areas below the Elvins tailings pile in the Old Lead Belt of Missouri. Zinc in particular is present at highly elevated levels in the water (5.9–21.0 mg l−1) and most sediments. The two most widespread plants are a blue-green alga,Plectonema gracillimum, and a moss,Dicranella sp. In wetter areas the latter exists predominantly as protonema.Plectonema and the protonema typically grow in very close association, although situations do occur where only one or the other is present. For instance, algal flocs in two permanent ponds consisted largely ofPlectonema and unicellular blue-green algae, with a few eukaryotic algae, but no protonema. Other dominants in the area areEleocharis sp.,Scirpus americanus andTypha latifolia. One seepage was studied in more detail; it showed marked changes in both chemistry and vegetation on passing from source to a site 15 m downstream. Aqueous Zn dropped from 21 to 8 mg l−1. ThePlectonema-Dicranella protonema community predominated in the upper part, developing a laminated structure up to 3 cm thick (justifying recognition as a stromatolite). Further downstream a white crust including much hydrozincite and with a very high overall zinc content (c. 370 mg g−1 Zn) was deposited over the green layer, making it endolithic in position, though probably not in origin. Still further downstream the green layer disappeared, leaving only a hard white crust. A discussion is included of the extent to which observed variations in the zinc content of water and sediments below the tailings pile are influenced by living and dead plants. An apparent diel cycle in aqueous zinc at some sites is of particular interest, as it was not matched by changes in Ca or Cd.
TL;DR: In this article, the vortex instability of laminar, mixed-convection flow over an isothermal, horizontal flat plate is investigated analytically by the linear stability theory.
Abstract: The vortex instability of laminar, mixed-convection flow over an isothermal, horizontal flat plate is investigated analytically by the linear stability theory. In the analysis, the main flow and thermal fields are treated as non-parallel and the disturbances are assumed to have the form of a stationary longitudinal vortex roll that is periodic in the spanwise direction. Numerical results for the critical Grashof and Reynolds numbers that predict the first occurrence of the vortex rolls are obtained for fluids with Prandtl numbers of 0.7 and 7. It is found that the flow becomes more susceptible to vortex mode of instability as the buoyancy force increases. The present results are compared with available experimental data and also with analytical results from the wave mode of instability.