Showing papers by "Missouri University of Science and Technology published in 1980"

Propagating Fronts for Competing Species Equations with Diffusion

Abstract: 1. The notion of a traveling wave front in the context of population dynamics is a natural one and has undoubtedly been in existence a long time. This concept, however, was apparently first modeled by a differential equation by FISHER in 1937 [1]. Fisher had in mind a community in which the processes of natural selection and random spatial migration were evident. The front then represented a wave of spatial advance of a favorable gene. In the final analysis, FISHER'S equation was simply the usual logistic growth equation, supplemented by an extra term uxx representing the effect of spatial diffusion:

Locally optimal block quantizer design

Abstract: Several properties are developed for a recently proposed algorithm for the design of block quantizers based either on a probabilistic source model or on a long training sequence of data. Conditions on the source and general distortion measures under which the algorithm is well defined and converges to a local minimum are provided. A variation of the ergodic theorem is used to show that if the source is block stationary and ergodic, then in the limit as n → ∝, the algorithm run on a sample distribution of a training sequence of length n will produce the same result as if the algorithm were run on the “true” underlying distribution.

Polymerization in water‐in‐oil microemulsion systems. I

Abstract: Phase diagrams for monomer (methyl acrylate containing microemulsions) are shown and described. Polymerizations of a series of microemulsified monomer reveals the expected linear dependence of 1/DS vs. [S]/[M] for pentanol acting as a chain transfer agent and giving a value of 5.1 × 10−4 for Cs. No break in molecular weight behavior was shown as a result of micellization at higher water contents. A comparison of molecular weights obtained by various classical methods (solution, emulsion, bulk) are also given.

Probability of correct selection of weibull versus gamma based on livelihood ratio

Abstract: This paper proposes the use of tne likelihood ratio statistic in choosing between a Neibull or gamma model, values of the probability of correct seeiection are obtained by Monte Carlo simulation. This method provides some basis for decision even when the sample size is small. The technique is applied to four sets of data from the literature.

Polymerization in water in oil microemulsion systems containing methyl methacrylate

Abstract: Phase diagrams developed for methyl methacrylate containing microemulsions show that the effect of 001 M persulfate on the size of the phase stability region is negligible At higher concentrations ( 01 M) the persulfate showed an influence to be expected from an electrolyte; reduced water solubilization at low surfactant/ alcohol ratios and increased solubilization at the highest ratios Molecular weight dependencies on initiator concentration for both water and organic soluble initiators are shown to follow solution behavior Added chain transfer agents follow the Mayo equation, however the chain transfer constant for n-C10 SH is about 10 times lower than expected, possibly due to incorporation of the thiol group within the micellar interior Solvent chain transfer alone, being 10 times lower for MMA than for MA, does not give sufficient lowering of molecular weight to give useful comparisons by GPC technique Comparisons of structure based kinetic differences between emulsions and microemulsi

The System MgO‐MgCl2‐H2O at 23°C

Abstract: Solubilities of MgO in aqueous HC1 solutions at 23°±3°C were measured and combined with analyses of neat magnesium oxychloride cements, cured in sealed containers, to construct an equilibrium phase diagram for the system MgO-MgCl2-H2O. Specific gravities and acidities of solutions saturated with MgO and relative humidities of vapor phases over sealed samples were measured and combined with XRD data to define the compositions in equilibrium with two crystalline phases. Studies of relative reaction rates indicated that the 5–1–8 phase crystallizes more rapidly than the 3·1·8 phase and that cements near the 3·1·8 composition react rapidly with atmospheric CO2 to form the chlorocarbonate phase.

Inferences concerning the Mean of the Gamma Distribution

Abstract: Approximate tests for the mean of a gamma distribution with both parameters unknown are derived. The power of these tests is close to the power of the corresponding uniformly most powerful tests for the mean when the shape parameter is assumed known. The tests are studied by Monte Carlo simulation, and limiting results are also provided as the shape parameter goes to zero or infinity, as well as for the large-sample case. A limited study indicating the nonrobustness of the standard t test for this case is also included.

Evaluation of zinc sulphate electrolytes containing certain impurities and additives by cyclic voltammetry

Abstract: The polarization characteristics of acid zinc sulphate electrolytes containing various amounts of germanium and cobalt were examined by cyclic voltammetry. The effects of zinc and acid concentration, temperature, and surface preparation were also investigated. Small concentrations of impurities are shown to cause measurable changes in polarization behaviour. Levels as low as 0.02 mgl−1 Ge and 0.1 mgl−1 Co can be detected using this technique. The actual mechanism of impurity behaviour is more clearly delineated using this technique and evaluation of the data from these tests indicate that germanium and cobalt form local galvanic cells. The results of these short-term tests are shown to correlate with classical long-term efficiency tests. The deposit morphologies obtained for short-time cathodic cycles were also studied using scanning electron microscopy.

Polymerization in lyotropic liquid crystals. I. Change of structure during polymerization

Abstract: Polymerization was made at 60°C in a lyotropic liquid crystal of sodium undecenoate and water. The liquid crystalline structure prior to polymerization was identified by optical microscopy and low-angle x-ray diffraction as an array of hexagonal closely packed cylinders with the hydrophobic part of the soap in the center of the cylinders. During polymerization the structure became isotropic at 60°C. Cooling to 20°C transformed the structure to a lamellar liquid crystal–a reversible transition. The structure of the lamellar phase was interpreted as a polyethylene backbone from which deformed decanoate chains reached toward the aqueous layer. Molecular models showed the model to accept head-tail, head-head, and tail-tail configurations in cis and trans conformations with the exception of the cis tail-tail configuration.

Finite plane strain deformations of rubberlike materials

Abstract: A finite element program capable of analysing finite plane strain deformations of incompressible rubberlike (Mooney–Rivlin) materials has been developed. Two problems, namely a long wall loaded uniformly in two directions and a thick-wall cylindrical pressure vessel loaded internally, have been solved. The computed values of displacements, strains, stresses and hydrostatic pressure agree very closely with their values obtained analytically.

Nucleate Boiling Performance of Refrigerants and Refrigerant-Oil Mixtures

Abstract: Current and previous studies by the authors and others have shown that the carry-over on oil in refrigeration systems can have a significant influence of the boiling performance in the evaporator of refrigeration systems. This investigation was conducted primarily to develop a general correlation equation for predicting the heat transfer coefficient for refrigerants and refrigerant-oil mixtures under pool boiling conditions. Experimental results were obtained to establish the validity of the correlation equation.

Noble gas anomalies and synthesis of the chemical elements

Abstract: There are two types of planetary noble gases: One, containing isotopically “anomalous” argon, krypton and xenon but isotopically “normal” helium and neon, was derived from outer stellar regions. The other, consisting almost entirely of isotopically “normal” argon, krypton and xenon, with little or no helium or neon, was derived from inner stellar regions. Mixing of nucleosynthesis products from different regions of a supernova is responsible for the observed correlations between elemental and isotopic ratios of planetary noble gases in different classes of meteorites. The solar system condensed directly from the chemically and isotopically heterogeneous debris of a single supernova. There is no convincing evidence, however, of separate nucleogenetic components in neon. Fractionation and spallation can account for all previously identified components of trapped meteoritic neon, Ne-A, Ne-B, Ne-C, Ne-D, Ne-E, Ne-Al, Ne-A2, Ne-E(L), Ne-E(H) and Ne-O, and this same mechanism also explains differences between the isotopic compositions of meteoritic, atmospheric, and solar wind neon. Variations in the abundance pattern of planetary noble gases are primarily the result of stellar fusion reactions and physical adsorption, rather than gas solubility.

Mutual information rate, distortion, and quantization in metric spaces

Abstract: Several new properties as well as simplified proofs of known properties are developed for the mutual information rate between discrete-time random processes whose alphabets are Borel subsets of complete separable metric spaces. In particular, the asymptotic properties of quantizers for such spaces provide a fink with finite-alphabet processes and yield the ergodic decomposition of mutual information rate. This result is used to prove the equality of stationary and ergodic process distortion-rate functions with the usual distortion-rate function. An unusual definition of mutual information rate for continuous-alphabet processes is used, but it is shown to be operationally appropriate and more useful mathematically; it provides an intuitive link between continuous-alphabet and finite-alphabet processes, and it allows generalizations of some fundamental results of ergodic theory that are useful for information theory.

Some complete and censored sampling results for the three-parameter weibull distribution

Abstract: Some simple point estimators are proposed for the three-parameter Weibull distribution. Both complete and type II censored sampling are considered. The biases and variances of these estimators are studied by Monte Carlo simulation. Percentage points for the estimator of the shape parameter are also obtained by Monte Carlo simulation, which enables interval estimation and tests of hypotheses to be carried out for the shape parameter.

Parametric Integer Programming Analysis: A Contraction Approach

Abstract: An algorithm is presented for solving families of integer linear programming problems in which the problems are "related" by having identical objective coefficients and constraint matrix coefficients. The righthand-side constants have the form b + θd where b and d are conformable vectors and θ varies from zero to one.

Evolution of perthite composition and microstructure during progressive metamorphism of hypersolvus granite, Rhode Island, USA

Abstract: The Scituate Granite in central Rhode Island, USA contains very coarse alkali feldspar mesoperthite and has been subjected to prograde metamorphism subsequent to original igneous cooling. The modal abundance and grain size of relics of alkali feldspar mesoperthite decrease systematically as metamorphic grade increases. The composition and microstructures of coexisting phases in the relict perthite grains also vary systematically with increasing metamorphic grade. Microstructures coarsen and become more complex, and compositions record increasing metamorphic temperatures.

Chlorpropamide inhibition of excision repair and postreplication repair of ultraviolet damage in Chinese hamster ovary cells.

Abstract: Chlorpropamide, an oral hypoglycemic agent, was tested for effects on excision repair and postreplication repair of ultraviolet (UV) damage of DNA in CHO-K1 cells. The technique used to measure excision repair involved isopycnic centrifugation of density- and isotopically-labeled DNA. Alkaline sucrose gradient sedimentation was used to monitor postreplication repair. Administration of chlorpropamide at 250 and 1000 μg/ml after exposure of cultures to 254nm UV reduced excision repair to 79 and 67%, resp., of control. Post-irradiation treatment with the drug at 1000 μg/ml inhibited the postreplication gap-filling mechanism almost as effectively as did 2 mM caffeine. The hypoglycemic agent was also found to reduce UV cell survival but did not appear to alter the rate of semiconservative replication. These results suggest that chlorpropamide inhibition of repair processes may potentiate the effects of known mutagenic hazards and may also be responsible for the increased incidence of chromosome aberrations in patients treated with the drug.

Some universal noiseless multiterminal source coding theorems

Abstract: Fixed and variable-rate block and sliding-block weighted universal noiseless coding theorems are obtained which extend the Slepian-Wolf theorem for a single multiterminal source to a family of finite-alphabet, stationary, ergodic multiterminal sources.