Showing papers by "Michigan Technological University published in 1989"
TL;DR: In this paper, a gradient-dependent flow theory of plasticity for metals and granular soils is proposed and applied to the problems of shear banding and liquefaction.
Abstract: We propose a gradient-dependent flow theory of plasticity for metals and granular soils and apply it to the problems of shear banding and liquefaction. We incorporate higher order strain gradients either into the constitutive equation for the flow stress or into the dilantancy condition. We examine the effect of these gradients on the onset of instabilities in the form of shear banding in metals or shear banding and liquefaction in soils under both quasi-static and dynamic conditions. It is shown that the higher order gradients affect the critical conditions and allow for a wavelength selection analysis leading to estimates for the width or spacing of shear bands and liquefying strips. Finally, a nonlinear analysis is given for the evolution of shear bands in soils deformed in the post-localization regime.
128 citations
TL;DR: In this article, a mixed-integer programming (MILP) model is proposed to minimize the sum of train costs, car time costs, and classification yard costs, while not exceeding limits on train size and yard volumes.
Abstract: Railroad managers must determine (1) which pairs of terminals are to be provided with direct train connections, (2) the frequency of service, (3) how the individual cars are routed through the available configuration of trains and intermediate terminals, and (4) how cars are physically grouped or “blocked” within trains. The objective is to minimize the sum of train costs, car time costs, and classification yard costs, while not exceeding limits on train size and yard volumes. These decisions are modeled as a mixed-integer programming problem, where the decision to operate a given train connection corresponds to 0–1 variable. With no limits on train size, the model can be solved very efficiently using Lagrangian relaxation. If the solution contains some overloaded trains, which is likely, heuristic adjustments are necessary to obtain a feasible operating plan.
121 citations
15 May 1989
TL;DR: This paper examines the relationship between the data flow in a module and its level of cohesion using a processing element flow graph (PFG), and suggests that these slice profiles can be used to determine more easily the cohesiveness of a module.
Abstract: High module cohesion is often suggested as a desirable property of program modularity. The subjective nature of the definition of cohesion, however, can make it difficult to use in practice. In this paper, we examine the relationship between the data flow in a module and its level of cohesion using aprocessing element flow graph (PFG). Based on these PFG's, we regroup the original seven levels of cohesion into four classifications, Slice profiles are then defined by generating slices for all output variables of a module. A relationship is then shown between these slice profiles and the, PFG used to indicate levels of cohesion. It is suggested that these slice profiles can be used to determine more easily the cohesiveness of a module.
103 citations
01 Jan 1989-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the authors summarize the scope of operations for both cast-and powder-based processing and identify processing issues which cause matrix-reinforcement interface and property variability in discontinuous metal matrix composites.
Abstract: Metal matrix composite materials which utilize discontinuous-type reinforcement undergo unit operations associated with ingot, powder or cast metal manufacturing in addition to their own unique operations. An attempt is made to summarize the scope of operations for both cast- and powder-based processing and identify processing issues which cause matrix-reinforcement interface and property variability in discontinuous metal matrix composites.
94 citations
01 May 1989
TL;DR: In this article, a gradient dependent dilatancy condition is assumed in order to capture the heterogeneous character of deformation in granular soils and its implications in two interesting examples of patterning instability, that is shear banding and liquefaction, are examined.
Abstract: A gradient dependent dilatancy condition is assumed in order to capture the heterogeneous character of deformation in granular soils. This assumption is incorporated into the structure of classical deformation and flow theories of plasticity and its implications in two interesting examples of patterning instability, that is shear banding and liquefaction, are examined. Shear banding is considered within a modified gradient dependent deformation theory, while liquefaction is studied within a modified gradient dependent flow theory of plasticity. In both cases a deformation induced length scale is obtained near the instability, and this is identified with the thickness of the shear band or the spacing of the liquefying strips.
90 citations
TL;DR: In the dark, nitrate induced nitrate reductase expression in both etiolated and green leaves, indicating light and functional chloroplast were not required for enzyme expression.
Abstract: cDNA clones were selected from a corn (Zea mays L.) leaf lambda gt11 expression library using polyclonal antibodies for corn leaf NADH:nitrate reductase. One clone, Zmnrl, had a 2.1 kilobase insert, which hybridized to a 3.2 kilobase mRNA. The deduced amino acid sequence of Zmnrl was nearly identical to peptide sequences of corn leaf NADH:nitrate reductase. Another clone, Zm6, had an insert of 1.4 kilobase, which hybridized to a 1.4 kilobase mRNA, and its sequence coded for chloroplastic NAD(P)+:glyceraldehyde-3-phosphate dehydrogenase based on comparisons to sequences of this enzyme from tobacco and corn. When nitrate was supplied to N-starved, etiolated corn plants, nitrate reductase, and glyceraldehyde-3-phosphate dehydrogenase mRNA levels in leaves increased in parallel. When green leaves were treated with nitrate, only nitrate reductase mRNA levels were increased. Nitrate is a specific inducer of nitrate reductase in green leaves, but appears to have a more general effect in etiolated leaves. In the dark, nitrate induced nitrate reductase expression in both etiolated and green leaves, indicating light and functional chloroplast were not required for enzyme expression.
87 citations
Patent•
22 Dec 1989TL;DR: In this article, a mixture of water and organic polyisocyanate is used to accelerate the reaction between wood flakes or particle board panels, and the resulting furnish is compression shaped under pressure and at a temperature less than 250° F. for a time period sufficient to form a composite article of the desired shape and/or dimensions.
Abstract: Flakeboard or particle board panels and other composite articles made from wood flakes or other particulate lignocellulosic materials having a relatively high internal bond and improved resistance to moisture are made from flakes or particles which have a moisture content of at least 15%. A catalyst capable of accelerating the reaction between the flakes or particles, the binder and water is applied to the flakes or particles prior to the addition of a moisture-tolerant particle board binder, such as an organic polyisocyanate. A mat of the resulting furnish is compression shaped under pressure and at a temperature less than 250° F. for a time period sufficient to form a composite article of the desired shape and/or dimensions.
85 citations
TL;DR: In this article, a physically-based theory of damage for ductile metals is outlined, which rests upon a direct extension of the authors recently proposed viscoplastic model for finite deformations to include the effects of dislocation, void interactions as they manifest themselves in void nucleation, growth and coalescence.
80 citations
TL;DR: In this article, a sample of olivine tholeiite lavas from the Portage Lake Volcanics (PLV) in northern Michigan have initial Nd and Sr isotopic compositions which cluster near Bulk Earth values.
78 citations
TL;DR: The observed structure/activity relationships suggest that these analogues, and the phytoalexins, function primarily as uncouplers of oxidative phosphorylation, which appears to be the main factors affecting the antifungal activity of flavonoids.
72 citations
TL;DR: In this paper, a theoretical model for predicting the mean loads in the plastic postbuckling range is developed on the basis of an inextensional folding mechanism and the notion of stationary and travelling plastic hinges.
Journal Article•
TL;DR: Preparation dalliages a base de Al-2014 and Al-7475, contenant chacun 15% de particules de SiC, en forme de toles a grains fins as mentioned in this paper.
TL;DR: An electronically driven lattice deformation which explains qualitatively the supermodulus effect in metallic superlattices is derived and predicts the absence of an effect when the bulk Fermi energies of the constituent metals are equal.
Abstract: An electronically driven lattice deformation which explains qualitatively the supermodulus effect in metallic superlattices is derived. It is shown in the Thomas-Fermi approximation that the total energy of a metallic superlattice is lowered by uniform deformations of the constituent materials. The theory gives the correct order of magnitude for changes in lattice constants, explains why the supermodulus effect is not observed in systems in which at least one constituent is nonmetallic, and predicts the absence of an effect when the bulk Fermi energies of the constituent metals are equal.
TL;DR: Nitrogen fixation rates, as estimated by the acetylene reduction technique, were determined in conifer wood litter being decayed by brown- and white-rot fungi, and greater nitrogen additions from nitrogen-fixing bacteria may be a factor in the more rapid white- rot decay of hardwood litter, as compared to the slower brown-rot decay of conifer Wood.
Abstract: Nitrogen fixation rates, as estimated by the acetylene reduction technique, were determined in conifer wood litter being decayed by brown- and white-rot fungi. Average ethylene production rates were significantly higher in white-rotted wood (15.1 nmol g−1 day−1) than in brown-rotted wood (2.3 nmol g−1 day−1). This difference may be related to a higher soluble sugar content in white-versus brown-rotted wood. The nitrogen-fixing bacteriumAzospirillum was not detected in any of the decaying wood samples examined. Greater nitrogen additions from nitrogen-fixing bacteria may be a factor in the more rapid white-rot decay of hardwood litter, as compared to the slower brown-rot decay of conifer wood.
TL;DR: In this paper, small amounts of endogenic siderite and traces of pyrite (FeS2) were found in a 1 m-long sediment core from Lake Nyos.
TL;DR: In this article, Attitudes toward imitation: Classical culture and the modern temper are discussed. But they focus on imitation in the context of imitation-theoretic languages. And they do not consider imitation in Rhetoric.
Abstract: (1989). Attitudes toward imitation: Classical culture and the modern temper. Rhetoric Review: Vol. 8, No. 1, pp. 5-21.
01 Nov 1989
TL;DR: In this paper, the collapse behaviour and crashworthy characteristics of cantilever circular tubes subjected to bending were studied both theoretically and experimentally, and three different fixture devices were used.
Abstract: The collapse behaviour and crashworthy characteristics of cantilever circular tubes subjected to bending are studied both theoretically and experimentally. Three different fixture devices were used...
TL;DR: Immunoaffinity-purified corn and squash NR were shown to have an interchain disulfide bond as well as a reactive thiol group and suggestions made for site-directed mutagenesis experiments to aid in identifying the cysteine residues of NR associated with these features of the enzyme.
Abstract: NADH: nitrate reductase (EC 1661) (NR) is present in small amounts in plant tissues and its polypeptide in inherently labile Consequently, NR is difficult to purify We have generated 20 monoclonal antibodies (McAb) for corn and squash NR and selected two for use in immunoaffinity chromatography Squash McAb CM 15(11) and corn McAb ZM 2(69)9, which both bind corn and squash NR, were covalently coupled to Sepharose and used for purification of NR with elution of the purified enzyme by a pH 11 buffer Although this procedure yielded highly purified NR, its activity was diminished by the pH 11 treatment When corn leaf crude extract was applied to McAb CM 15(11)-Sepharose, NR bound and could be eluted in homogeneous form by its substrate, NADH Corn leaf NR prepared by substrate elution retained a high level of NADH: NR activity Immunoaffinity-purified corn and squash NR were shown to have an interchain disulfide bond as well as a reactive thiol group These results are discussed in relation to the recently obtained sequences of NR clones and suggestions made for site-directed mutagenesis experiments to aid in identifying the cysteine residues of NR associated with these features of the enzyme
TL;DR: Stimulation of phosphatidylinositol labeling observed in these studies is the earliest response of aleurone cells to gibberellic acid reported.
Abstract: Phospholipids of barley (Hordeum vulgare L. cv Himalaya) aleurone layers were labeled with myo-[2-3H]inositol or [32Pi], extracted, and analyzed by physical (chromatography) and chemical (deacylation) techniques. Three phospholipids were found to incorporate both myo-[2-3H]inositol and [32Pi]—phosphatidylinositol, phosphatidylinositol-monophosphate, and phosphatidylinositol-bisphosphate. Stimulation of [3H]inositol prelabeled aleurone layers with GA3 showed enhanced incorporation of label into phosphatidylinositol within 30 seconds and subsequent rapid breakdown. Stimulation of phosphatidylinositol labeling observed in these studies is the earliest response of aleurone cells to gibberellic acid reported.
TL;DR: An SO2 flux of 1170±400 (1σ) tonnes per day was measured with a correlation spectrometer (COSPEC) in October and November 1986 from the continuous, non-fountaining, basaltic East Rift Zone eruption (episode 48A) of Kilauea volcano as mentioned in this paper.
Abstract: An SO2 flux of 1170±400 (1σ) tonnes per day was measured with a correlation spectrometer (COSPEC) in October and November 1986 from the continuous, nonfountaining, basaltic East Rift Zone eruption (episode 48A) of Kilauea volcano. This flux is 5–27 times less than those of highfountaining episodes, 3–5 times greater than those of contemporaneous summit emissions or interphase Pu'u O'o emissions, and 1.3–2 times the emissions from Pu'u O'o alone during 48A. Calculations based on the SO2 emission rate resulted in a magma supply rate of 0.44 million m3 per day and a 0.042 wt% sulfur loss from the magma upon eruption. Both of these calculated parameters agree with determinations made previously by other methods.
TL;DR: In this article, the authors analyze the startup problem for the Giesekus model, both asymptotically and numerically, and compare the results to those obtained for other models.
Abstract: The spurt phenomenon is a flow instability which occurs in pressure-driven parallel shear flows of viscoelastic liquids. This phenomenon is characterized by an abrupt increase in the volumetric throughput at a critical value of the driving pressure gradient. Recently, non-monotone (steady shear response) constitutive equations have been proposed to model this phenomenon. We analyze the startup problem for the Giesekus model, both asymptotically and numerically, and compare the results to those obtained for other models.
TL;DR: The possibility of using remote sensing to monitor potentially dangerous volcanoes is discussed in this article, where thermal studies of active volcanoes are considered along with using weather satellites to track eruption plumes and radar measurements to study lava flow morphology and topography.
Abstract: The possibility of using remote sensing to monitor potentially dangerous volcanoes is discussed. Thermal studies of active volcanoes are considered along with using weather satellites to track eruption plumes and radar measurements to study lava flow morphology and topography. The planned use of orbiting platforms to study emissions from volcanoes and the rate of change of volcanic landforms is considered.
TL;DR: In this article, a finite difference analysis is applied to surface diffusion-controlled instabilities of plates, and the results of this finite difference calculation are in reasonable accord with the CMK results, as far as predicting instability times are concerned.
Abstract: A two-dimensional finite difference analysis is applied to surface diffusion-controlled instabilities of plates. Plates can evolve into “cylinders,” or if the plates have longitudinal internal boundaries, they may split into two segments. The evolution process of plates containing internal boundaries into equilibrium shapes depends on both the initial plate aspect ratio (plate width to thickness) and the ratio of the internal boundary energy to the plate-matrix interface energy. When the internal boundary energy is relatively low or the initial plate aspect ratio is relatively small, the transverse equilibrium cross-sectional area shape is composed of two circular segments, with an appropriate dihedral angle dictated by the ratio of the interface energy terms. As either the internal boundary energy or the initial aspect ratio increases, plate splitting, rather than cylinderization, becomes the dominant instability mode. The results of this work are compared to a recent theory of Courtney and Malzahn Kampe (CMK) on shape instability diagrams.[1] The complicated interactive effects between cylinderization and boundary splitting were not considered in the analytical CMK approach; thus, when they are minimal, the results of this finite difference calculation are in reasonable accord with the CMK results, as far as predicting instability times are concerned. However, when the interaction is significant, cylinderization and/or splitting times are markedly changed. The present accurate calculations allow refinement of the CMK plate instability diagrams.
TL;DR: An experimental study to determine the flow characteristics of an incompressible fluid in turbulent, radially outward flow between two coaxial, stationary disks was conducted employing a split film anemometer probe as mentioned in this paper.
Abstract: An experimental study to determine the flow characteristics of an incompressible fluid in turbulent, radially outward flow between two coaxial, stationary disks was conducted employing a split film anemometer probe. Instantaneous velocity components in the radial and axial directions were measured; from these measurements, average velocity profiles, turbulence intensities, Reynolds stresses, energy spectra and probability density functions for the fluctuating components were computed. It is observed that the law of the wall may not be applicable everywhere. A criterion established earlier for reverse transition to laminar flow may be valid with a value of the constant smaller than suggested. A few other aspects of the flow are also discussed.
TL;DR: In this paper, the effect of three distinctly different carbon precursor powders on the final titanium carbide morphology has been examined, and the effects of particle size and microstructure on the quality of the resulting product are also noted.
Abstract: Titanium carbide may be readily produced in high purity via direct reaction between the solid phases of titanium and carbon in the process of combustion synthesis, also known as self-propagating high-temperature synthesis (SHS). The high temperatures generated by this exothermic reaction (<3000 °C) melt the titanium phase which subsequently flows to and reacts with the solid carbon. As a result, with lightly or uncompressed green bodies a product is obtained which retains most of the carbon precursor powder morphology down to the μm scale. The effect of three distinctly different carbon precursor powders on the final titanium carbide morphology has been examined. Subsequent effects of particle size and microstructure on the quality of the titanium carbide product are also noted.
TL;DR: On presente aussi la cinetique de reaction metastable complete, ainsi que the dependance du champ electrique vis-a-vis du rapport d'emission de chaque configuration.
Abstract: Two metastable defect configurations, here designated M3 and M4, are observed in n-type GaAs grown by metal organic chemical-vapor deposition. The configurations are comprehensively characterized by deep-level transient spectroscopy and have enthalpies for thermal emission of electrons of 0.6 and 0.3 eV, respectively. The metastable transformation between these two centers is found to be temperature induced and bias controlled. The capture cross sections for both defect configurations are found to be temperature independent with values of 5.1\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}18}$ and 1.8\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}18}$ ${\mathrm{cm}}^{2}$ for the M3 and M4 configurations, respectively. Defect depth profiling shows defect densities that decrease monotonically from approximately 1\ifmmode\times\else\texttimes\fi{}${10}^{13}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ at 0.2 \ensuremath{\mu}m below the surface to approximately 1\ifmmode\times\else\texttimes\fi{}${10}^{11}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ at 0.6 \ensuremath{\mu}m below the surface for both defect configurations. Photocapacitance measurements give photoionization threshold energies consistent with the electrical measurements and photoionization cross sections of about 2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}19}$ ${\mathrm{cm}}^{2}$ at a photon energy of 0.75 eV. The complete metastable reaction kinetics are also reported, as well as the electric field dependence of the emission rate for each configuration.
TL;DR: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis with immunoblotting indicated that both TSST-1 and the TSST variant had a molecular size of 24 kilodaltons.
Abstract: A toxic shock syndrome toxin (TSST) variant with an isoelectric point (pI) of 8.6 produced by an ovine-associated Staphylococcus aureus strain was described previously. Analysis of additional strains associated with sheep, goats, cows, and humans by isoelectric focusing with immunoblotting using monoclonal antibodies revealed that all 18 strains associated with sheep and all 12 strains associated with goats produced the TSST variant. Only 1 of 10 bovine-associated strains and no human-associated strains produced the variant, whereas the others produced TSST-1 (pI between 7.0 and 7.2). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis with immunoblotting indicated that both TSST-1 and the TSST variant had a molecular size of 24 kilodaltons.
TL;DR: This work has found an unusually rapid light-induced release of nitrate reductase mRNA in the form of a sharp pulse at the mRNA, proteins, and activity levels.
Abstract: We have investigated the effect of light on nitrate reductase at the mRNA, proteins, and activity levels and found an unusually rapid light-induced release of nitrate reductase mRNA in the form of a sharp pulse
Patent•
17 Aug 1989TL;DR: Complexes of sulfited tannin extract and a copper(II) ion can be used to protect wood against fungal attack as discussed by the authors, and the complex can be impregnated into wood in a single step treatment using a water/organic solvent system.
Abstract: Complexes of sulfited tannin extract and a copper(II) ion effectively protect wood against fungal attack. The complex can be impregnated into wood in a single step treatment using a water/organic solvent system, or formed in situ by treating the wood with an aqueous solution containing the extract and subsequently treating the wood with an aqueous solution containing a copper (II) salt.