Showing papers by "Missouri University of Science and Technology published in 1974"

A Heuristic Algorithm for the Vehicle-Dispatch Problem

Abstract: This paper introduces and illustrates an efficient algorithm, called the sweep algorithm, for solving medium-as well as large-scale vehicle-dispatch problems with load and distance constraints for each vehicle. The locations that are used to make up each route are determined according to the polar-coordinate angle for each location. An iterative procedure is then used to improve the total distance traveled over all routes. The algorithm has the feature that the amount of computation required increases linearly with the number of locations if the average number of locations for each route remains relatively constant. For example, if the average number of locations per route is 7.5, the algorithm takes approximately 75 seconds to solve a 75-location problem on an IBM 360/67 and approximately 115 seconds to solve a 100-location problem. In contrast, the time to solve a problem with a fixed number of locations increases quadratically with the average number of locations per route. The sweep algorithm generally produces results that are significantly better than those produced by Gaskell's savings approach and are generally slightly better than Christofides and Eilon's results; however, the sweep algorithm is not as computationally efficient as Gaskell's and is slightly less so than Christofides and Eilon's.

Effect of Dissolved Water on the Internal Friction of Glass

Abstract: The two internal friction peaks in (1−X) Na2P2O6· X Al2O3 glasses showed a pronounced dependence on the water content. With increasing water content, the alkali peak became 10–20% smaller and a slight increase in the activation energy was indicated. Similarly, the second peak became 2–4 times larger and shifted to lower temperatures. From the close correlation between the magnitude of the second peak and the water content, the mechanism for this peak was concluded to consist of the cooperative movement of a sodium ion and a neighboring proton. Comparison of aluminophosphate and alkali silicate glasses showed that the internal friction peaks have a similar dependence upon the water content in both types of glasses. It is concluded that the water content of a glass should be closely controlled when the effect of other compositional changes on the internal friction is being studied.

Influence of Oxygen Activity on the Sintering of MgCr2O4

Abstract: The sintering behavior of MgCr2O4 powder compacts was investigated as a function of temperature, time, and oxygen activity. The results show that MgCr2O4 cannot be densified to >70% of theoretical density at temperatures up to 1700°C if the oxygen activity exceeds 10−6 atm. The oxygen activity must be decreased to <10−10 atm before densities exceeding 90% of theoretical can be achieved. Weight loss and X-ray data indicated that maximum density occurred at an oxygen activity just above that where MgCr2O4 becomes unstable.

Thermochemical investigations of nearly ideal binary solvents. I. Standard heats and volume changes of solution in methanol-isopropanol mixtures at 25°C

Abstract: Standard heats and volume changes of solution of acetone,n-butanol, chloroform, and water in methanol, isopropanol, and mixtures of the two are reported. In every case, the value of a measured property in a mixture is more negative than the mole-fraction average of the values measured in the pure solvents. Equations relating the heat of solution in a binary mixture to the heats of solution in the pure solvents and the excess enthalpy of the binary mixture are developed from equations for the excess enthalpy of simple ternary systems. Heats of solution ofn-butanol agree fairly well with predicted values. Combination of standard heats of solution with standard volume changes of solution allow estimation of standard energy changes of solution at constant volume.

Surface electromagnetic waves on metals and polar insulators: some comments.

Abstract: The important parameters governing the propagation of surface electromagnetic waves (SEW) on metals or polar insulators have been theoretically investigated. General approximations for the propagation distance, decay distance, and penetration depth are presented in summary tables. It is found that the propagation distance of SEW can be used to study overlayer materials on metals, that the penetration depth of SEW fields into a metal is governed by the classical skin depth at low frequencies and by the plasma frequency in the visible wavelength region, that surface phonons can propagate over a centimeter on PbS, PbTe, and ferroelectrics, and that the propagation distances of SEW increase with decreasing temperature.

Some Results on Point Estimation for the Two-Parameter Weibull or Extreme-Value Distribution

Abstract: A simple unbiased estimator is proposed for the location parameter of the extreme-value distribution. This estimator is shown to have high eficiency, especially when heavy censoring is used. A simple estimator of reliability, when failure times follow the Weibull distribution, is also obtained, and it is shown to have high asymptotic efficiency when heavy censoring is employed.

Transient Thermal Stresses in a Sphere by Local Heating

Abstract: The problem of transient thermal stresses in a solid, elastic, homogeneous, and isotropic sphere is solved for uniform and nonuniform, local surface heating. The temperature solutions are obained by using separation of variables and integral transformation. The corresponding thermal stresses are derived by superposing a particular displacement potential function on Boussinesq solutions. Numerical solutions for 2 particular cases of localized heating of a typical brittle spherical solid have been obtained and presented. The results indicate a tensile stress concentration in the interior of the solid below the heated zone.

Evaluating the membrane fecal coliform test by using Escherichia coli as the indicator organism.

Abstract: The fecal coliform membrane filter method (MFC) currently used in water pollution analysis was evaluated by using two strains of Escherichia coli, a known fecal coliform, as the indicator organism. A large relative error in the results obtained with this method was found to be dependent upon the brand of membrane filter employed, the medium, and the temperature of incubation. MFC densities varied between 10 and 60% of the densities determined by means of total bacteria counts and total coliform counts performed at 35 C. Due to the large relative error encountered, the MFC method cannot be recommended as an analytical tool for the laboratory enumeration of E. coli. The results do show that the MFC method can be used at 35 C for enumeration of E. coli and for differential counts of E. coli and Enterobacter aerogenes.

Thermal stresses and movements in bridges

Abstract: A state-of-the-art review regarding the thermal behavior of bridges and considerations to be given to the resultant thermal effects is presented. The results of studies related to the thermal effects on bridges are reviewed. Studies attempting to relate environmental factors to bridge temperatures, and subsequently to bridge movements and stresses, indicate that the task is extremely complex. Some correlation has been made between equations predicting bridge temperatures and movements based on weather bureau records. However, further research is needed to evaluate the effects of factors other than temperature, such as creep, shrinkage, and humidity, on bridge movements and stresses.

A General Formula for the Capacity of Stationary Nonanticipatory Channels

Abstract: A general formula for the capacity of stationary nonantic~patory channels is known. However, it is difficult to use this formula to calculate the capacities of the particular channels that have been considered in the literature. In this paper we derive a different formula for the capacity of stationary nonantieipatory channels. We then use this formula to calculate the capacities of several channels. In this way we obtain a unified approach to the calculation of the capacity. This approach avoids having to prove a coding theorem and a weak converse for each special type of channel.

Internal Friction of Glasses with Low Water Contents

Abstract: Internal friction was measured for NaPO3 glasses containing from 0.0004 to 0.146 wt% H2O. In glasses containing ≤ 0.001 wt% H2O, the only internal friction peak observed was that resulting from the Na+ ions, i.e. the alkali peak; it was ∼ 30% larger than in as-melted glasses. The second peak normally observed in as-melted NaPO3 glass was completely absent when the water content was < 0.001 wt%, consistent with the interpretation that it is caused by a reorientation of proton-Na+ elastic dipoles. The concept that the second peak in as-melted alkali phosphate and silicate glasses results from nonbridging oxygen ions is not substantiated by these studies of NaPO3 glasses, which contain a high percentage of these ions but do not exhibit this peak when the proton concentration is sufficiently low.

Trapped xenon in meteorites

Abstract: Xenon in meteorites can be resolved into a mixture of component X and trapped xenon with the following composition, Xe-124 : Xe-126 : Xe-128 : Xe-130 : Xe-131 : Xe-132 : Xe-134 : Xe-136 = 0.0276 : 0.0248 : 0.501 : 1.00 : 5.04 : 6.19 : 2.31 : 1.90. This trapped meteoritic xenon is distinct from xenon trapped in the average carbonaceous chondrite which is shown to represent the average composition of the total xenon in meteorites containing various mixtures of component X and trapped meteoritic xenon.

Stability of developing pipe flow subjected to non-axisymmetric disturbances

Abstract: The linear stability of the developing flow of an incompressible fluid in the entrance region of a circular tube is investigated. The case of non-axisymmetric small disturbances is considered in the analysis. The main-flow velocity distribution used in the stability calculations is that from the solution of the linearized momentum equation. The eigenvalue problem consisting of the disturbance equations and the boundary conditions is solved by a direct numerical integration scheme along with an iteration procedure. The flow is found to be unstable to nonaxisymmetric disturbances with an azimuthal wavenumber of one. Neutral-stability curves and critical Reynolds numbers at various axial locations are presented.

Kinetics and economics of anaerobic digestion of animal waste

Abstract: Disposal of animal waste represents a severe environmental problem, particularly in areas such as cattle feedlots where livestock are concentrated. Animal waste can be converted to CO2 and CH4 by the autocatalytic process of anaerobic fermentation. A scheme, based upon this process, for the disposal of the waste from a large feedlot is presented. The design of this process is based on kinetic data from the literature which are fitted to a kinetic model including diffusional resistances. Sale of the CH4 provides an economic incentive for this process and a return on investment of 23 % yr−1 appears possible for a large feedlot.

Anionic polymerization of a series of five-membered cyclocarbosiloxanes

Abstract: A study was conducted of the anionic polymerization of a series of methyl- and/or phenyl-substituted five-membered cyclocarbosiloxanes. The polymerization was initiated by lithium n-butyldiphenylsilanolate in the presence of tetrahydrofuran. The rate of conversion of monomer to polymer was measured in an NMR spectrometer. The rate of polymerization was largely dependent upon the structure of the growing chain ends. The apparent activation energies were in the range 10–14 kcal/mole for the series.

Internal Friction of Sodium Phosphate Glasses

Abstract: The internal friction of X Na 2 O·(1 − X )P 2 O 5 glasses, X varied from 0.29 to 0.59, has been measured from −100 to +300°C at ∼ Hz and from 25 to 300°C at ∼ 2000 Hz. Two internal friction peaks were observed. Based on the compositional dependence of the low temperature peak and the agreement between the activation energy of this peak with that calculated from dielectric loss measurements, this peak was assigned to the stress induced movement of the sodium ions. The magnitude of the second peak occurring at higher temperature, in addition to varying with the sodium content, was also very sensitive to the water content; its magnitude increasing with increasing water content. This peak was concluded to be a type of ‘mixed alkali’ peak involving the cooperative movement of sodium ions and protons. Due to the shift of the background damping to lower temperatures with decreasing sodium content, neither peak could be observed for X

Mechanical damping of silver-containing SiAsChalcogenide glasses

Abstract: Mechanical damping measurements were used to study the structural conditions responsible for the increase in thermal stability that has been observed when Ag and Se are substituted simultaneously in Si 35 As 25− x Ag x Te 40− y Se y glasses. Glasses containing Ag exhibited a mechanical damping peak whose magnitude was approximately proportional to the Ag content and which was absent in the more completely cross-linked Si 35 As 25 Te 40 base glass. This peak shifted to lower temperatures and split into two overlapping peaks with increasing Se content. The splitting of the peak has been tentatively attributed to phase separation which has been postulated to occur at higher Se contents.

Anodic Dissolution of Metals—Anomalous Valence

Abstract: When metals are dissolved anodically in aqueous and nonaqueous media, the weight of metal dissolved is sometimes greater than that calculated from Faraday’s law assuming normal oxidation states. Among several metals of industrial importance, Al, Be, Cd, Fe, Pb, Mg, Ti, and Zn exhibit this phenomenon. The usual implication is that these metals dissolve as ions with an ionic valence or oxidation number less than normal, e.g., Mg+, Be+, etc.

A Beam Condenser for Use with a High Pressure Diamond Anvil Cell

Abstract: Several recent papers and reviews have amply demonstrated the importance of high pressure studies on the electronic absorption bands in various coordination compounds. While studying the ligand field spectra of several pressure-sensitive transition metal complexes, we found that, although it was possible to obtain visible absorption spectra (in the range 650 to 300 nm), it was impossible to obtain usable spectra in the near infrared region (2000 to 650 nm). The difficulty arises because of the large size of the spectrophotometer sample beam and the small cross-sectional area (0.2 to 1.0 mm2) of the diamonds in the high pressure cell. Several attempts were made to overcome the small size of the diamond windows by masking the slit image in the reference beam of the spectrophotometer. However, these attempts were all unsuccessful because the masking necessitated operating the instrument at very high gain to prevent the slits from opening completely. The resulting spectra were extremely noisy and useless. We have now successfully overcome this problem by using a specially designed beam condenser.

Two-dimensional radiative equilibrium: A semi-infinite medium subjected to a finite strip of radiation

Abstract: Exact numerical results are presented for the emissive power and radiative flux at the boundary of a two-dimensional, absorbing-emitting, semi-infinite medium bounded by (1) a strip of collimated radiation and (2) a constant temperature black strip. The method of super-position is used to obtain the finite strip solutions in terms of cosine varying solutions. The infinite integrals arising in the solutions are converted to an alternating series of finite integrals. The Euler transformation is then applied to speed up convergence. Error bounds are determined whereby the two-dimensional finite strip analysis can be approximated by the simpler one-dimensional solution.

On the Analysis of the Condensational Growth of a Stationary Cloud Droplet in the Vicinity of Activation

Abstract: The theory of the growth (or evaporation) of a stationary drop has been cast into a form which reveals explicitly the role of both condensation and thermal accommodation coefficients. The equations for growth are integrated under constant ambient conditions. An application to cloud physics is discussed.

Two-dimensional radiative equilibrium: Boundary emissive powers for a finite medium subjected to cosine varying radiation

Abstract: Exact expressions are presented for the emissive power at the boundaries of a two- dimensional, finite, planar, absorbing-emitting, gray medium exposed on one side to cosine varying radiation and on the other side to no radiation. The emissive powers at the boundaries of a medium illuminated by cosine varying collimated radiation are the generalized X- and Y-functions which are analogous to Chandrasekhar's X- and Y-functions. Integro-differential equations for the generalized X- and Y-functions are formulated and reduced to a system of ordinary differential equations and are solved numerically. The emissive powers at the boundaries for cosine varying diffuse radiation are moments of the generalized X- and Y-functions.

A review of directed graphs as applied to computors

Abstract: The complexity of digital computers and their large scale use have led some researchers to investigate tools not commonly used. In recent years, applications of graph theory to computers as well as other fields of study have given fruitful results and have attracted more and more scientists. The attempt here will be to review previous accomplishments on a fundamental level and to stimulate the reader to investigate an area where valuable work is being performed.