Showing papers by "Stevens Institute of Technology published in 1986"
TL;DR: In this article, the extent to which dispersed-phase viscosity influences equilibrium mean drop size and drop size distribution at constant interfacial tension is determined for dilute suspensions by dispersing silicone oils of various viscosities grades in water.
Abstract: The extent to which dispersed-phase viscosity influences equilibrium mean drop size and drop size distribution at constant interfacial tension is determined for dilute suspensions by dispersing silicone oils of various viscosity grades in water. A mechanistic model for mean drop size is developed which predicts the moderate-viscosity data and whose parameters correlate the high-viscosity results. Trends in the mean size data coincide with those for the drop size distribution, which broadens considerably as viscosity increases and suggests a dependency on breakage mechanism.
377 citations
TL;DR: In this article, three hypothesis-confirmation strategies were examined: evidence being sought to the extent that it is more likely under the hypothesis being tested than under the alternative, the tendency to ask questions that will have the effect of making the hypothesis under test appear to be true, and a diagnosing strategy under which people prefer evidence that is most differentially probable under both the hypothesis and the alternative.
309 citations
TL;DR: In contrast to the usual probabilistic model for network reliability, one can use a deterministic model which is called network vulnerability, and certain reliability synthesis problems can be converted to a vulnerability question.
Abstract: In contrast to the usual probabilistic model for network reliability, one can use a deterministic model which is called network vulnerability. Many different vulnerability criteria and the related synthesis results are reviewed. These synthesis problems are all graph external questions. Certain reliability synthesis problems can be converted to a vulnerability question. Several open problems and conjectures are presented.
177 citations
TL;DR: In this paper, a state transformation is employed to improve the upper bounds on the linear time-varying perturbation of an asymptotically stable linear time invariant system for robust stability.
Abstract: This note addresses the issue of "conservatism" in the time domain stability robustness bounds obtained by the Lyapunov approach. A state transformation is employed to improve the upper bounds on the linear time-varying perturbation of an asymptotically stable linear time-invariant system for robust stability. This improvement is due to the variance of the conservatism of the Lyapunov approach with respect to the basis of the vector space in which the Lyapunov function is constructed. Improved bounds are obtained, using a transformation, on elemental and vector norms of perturbations (i.e., structured perturbations) as well as on a matrix norm of perturbations (i.e., unstructured perturbations). For the case of a diagonal transformation, an algorithm is proposed to find the "optimal" transformation. Several examples are presented to illustrate the proposed analysis.
144 citations
TL;DR: It is shown how a number of unsolved graph extremal problems relate to the synthesis question, and a survey of the graph theoretic notions which are relevant to thehesis problem is given.
Abstract: The analysis and synthesis of reliable large-scale networks typically involve a graph theoretic model. We give a survey of the graph theoretic notions which are relevant to the synthesis problem. It is shown how a number of unsolved graph extremal problems relate to the synthesis question.
122 citations
TL;DR: This work shows that many of the formulas for determiningt(G), the number of spanning trees of any graphG, in terms of a determinant, can be simply derived from known properties of Chebyshev polynomials.
Abstract: The Kirchhoff Matrix Tree Theorem provides an efficient algorithm for determiningt(G), the number of spanning trees of any graphG, in terms of a determinant. However for many special classes of graphs, one can avoid the evaluation of a determinant, as there are simple, explicit formulas that give the value oft(G). In this work we show that many of these formulas can be simply derived from known properties of Chebyshev polynomials. This is demonstrated for wheels, fans, ladders, Moebius ladders, and squares of cycles. The method is then used to derive a new spanning tree formula for the complete prismR
n
(m) =K
m
×C
n
. It is shown that
$$2^{\left( {\begin{array}{*{20}c} n \\ 2 \\ \end{array} } \right)\left( {1 - \frac{1}{{r - 1}} + o\left( 1 \right)} \right)} $$
whereT
n
(x) is then
th order Chebyshev polynomial of the first kind.
99 citations
TL;DR: In this article, the intrinsic membrane transfer coefficients of the solute are adequately described by the simple model of unhindered diffusion in tortuous pores developed earlier, and applied pressure difference did not influence the overall solute transfer coefficient as long as it was not close to that required for the breakthrough of aqueous phase into organic phase.
95 citations
TL;DR: It is found that briefly flashed pictures of a face were detected more accurately than was a control pattern with a nose, a mouth, and a pair of eyes positioned arbitrarily so that they did not form a face.
Abstract: We found that briefly flashed pictures of a face were detected more accurately than was a control pattern with a nose, a mouth, and a pair of eyes positioned arbitrarily so that they did not form a face. It has been known for some time that a face, as an organized set of features, is remembered more easily than is any one of its isolated features. Our results show that the perceptual superiority of faces extends to detection tasks, in which there is no need to remember any aspect of the face.
66 citations
TL;DR: In this article, a Marker-and-Cell numerical simulation of the filling of a cavity utilizing the Marker andCell numerical technique in solving the transient problem involved is presented.
Abstract: This work deals with the simulation of the filling of a cavity utilizing the Marker-and-Cell numerical technique in solving the transient problem involved. The cavity is confined by two parallel plates, and is “end fed.” The flow was assumed isothermal and the fluid incompressible, obeying the power law model. Special attention was given to the flow region near the advancing melt front, in order to obtain a better insight of the “fountain effect,” during which the fluid flows from the center to the walls of the cavity. The results of the simulation of the front flow region are supported by and in qualitative agreement with experimental results involving “tracer resins” during cavity filling. Although the flows considered were slow and isothermal, this study has significant practical ramifications on industrial mold filling during injection molding.
62 citations
TL;DR: In this paper, career exploration and goal-setting among 257 managers in a large communications company were examined, and high work role salience and the perceived availability of mobility opportunities were associated with extensive participation in career exploration.
60 citations
TL;DR: In this article, an analytical investigation is carried out on the wave-induced motions on two closely spaced, hydrodynamically interacting slender bodies advancing in oblique waves, including the hydrodynamic interaction and an integral equation method.
Abstract: An analytical investigation is carried out on the wave-induced motions on two closely spaced, hydrodynamically interacting slender bodies advancing in oblique waves. The two-dimensional procedure, including the hydrodynamic interaction and an integral equation method, is utilized. Numerical results are presented for the coupled motions of two ships. Comparisons are made with the behavior of a monohull and the interaction effect is found to be very important. Different headings and speeds are investigated. It has been found that the rolling motion is reduced while the ships are advancing--a helpful circumstance for cargo transfer between two ships. This study shows that the strip method is a useful technique to predict the hydrodynamically coupled motions between two ships advancing in oblique seas.
TL;DR: In this paper, an experimental study of the preparation and gas permeation characterization of aqueous membranes immobilized across the whole thickness or in a thin section of microporous hydrophobic Celgard 2400 and 2500 polypropylene films is described.
TL;DR: In this paper, an anti-Markovnikov addition reaction was used to transform α-vinyl-β-lactams involving an anti Markov addition reaction to terminal aldehydes instead of the expected methyl ketones.
TL;DR: Some recent polynomial-time algorithms for the exact computation of network reliability are surveyed, which apply to several classes of planar networks, which include series-parallel, inner-cycle-free, inner the inner-four- cycle-free and planar cube-free.
Abstract: We survey some recent polynomial-time algorithms for the exact computation of network reliability. The algorithms apply to several classes of planar networks, which include series-parallel, inner-cycle-free, inner-four-cycle-free and planar cube-free. We describe these classes and discuss the related polynomial algorithms for computing their reliability.
TL;DR: In this paper, a cluster of 13 beryllium atoms has been studied in ab initio Hartree-Fock calculations, and the chosen geometric configuration has D3h symmetry and corresponds to a central Be with 12 atoms situated at the hexagonal close-packed, nearest-neighbor positions.
Abstract: A cluster of 13 beryllium atoms has been studied in ab initio Hartree–Fock calculations. The chosen geometric configuration has D3h symmetry and corresponds to a central Be with 12 atoms situated at the hexagonal close‐packed, nearest‐neighbor positions. The lowest energy electronic state among those investigated is 5A‘1 and the first excited state is 5E‘ lying at 1.12 eV. A total of 14 states were identified below 2.0 eV. The 5A’’1 Hartree–Fock ground state has a binding energy of 12.0 kcal/mol relative to the separated atoms and an ionization potential of 0.54 eV. Total valence energies, orbital energies, binding energies, electric field gradients, diamagnetic shielding constants, nuclear–electron potentials, second moments, and Mulliken populations are reported. In addition, the cluster calculations give a reasonable estimate for the Sternheimer correction to the electric field gradient of the bulk metal.
TL;DR: In this paper, an experimental study was carried out to study and characterize the capillary extrudate swell and parison swell behavior in extrusion blow molding of two commercial high density polyethylene resins.
Abstract: An experimental study was carried out to study and characterize the capillary extrudate swell and parison swell behavior in extrusion blow molding of two commercial blow molding grade high density polyethylene resins. The capillary extrudate swell behavior of these resins were determined employing a capillary rheometer and a special thermostatting chamber. Parison swell behavior was determined using an Impco A13-R12 reciprocating screw blow molding machine in conjunction with cinematography and pinch-off. The experimental conditions under which capillary extrudate and parison swell data can be related are elucidated. Excellent agreement is found between the area swell values determined on the basis of capillary and parison swell experiments.
TL;DR: It appears that there are no appreciable differences in the physico-chemical properties, including conformation, among the heparins in H2O at 25 degrees C.
TL;DR: In this article, a series solution technique is developed to express each product composition and the pressure ratio as a power series in terms of a dimensionless membrane area for shell side constant-pressure feed flow.
Abstract: The problems in the numerical solution of boundary value problems encountered in hollow fiber binary gas permeatbrs having cocurrent or countercurrent permeate flow with axial pressure drop inside the fiber bore are discussed. A series solution technique is developed to express each product composition and the pressure ratio as a power series in terms of a dimensionless membrane area for shell side constant-pressure feed flow. Cocurrent or countercurrent rating or design problems require the solution of elther one algebraic equation, two coupled algebraic equations, or three coupled algebraic equations to determine the unknown quantities of interest. Calculated product and reject compositions, stage cuts, and closed-end pressure ratios compare quite well with those from numerical solutions for practically useful low to moderate cuts over a wide range of parameters. Cocurrent rating calculations requiring solution of only one algebraic equation are recommended for shortcut procedures since flow pattern effects are significant but not large.
TL;DR: In this paper, a systematic, experimental study was conducted on the elementary process of devolatilization and various parameters affecting it, using a specially designed apparatus, which is devoid of the flow complexities present in industrial equipment and which permits independent control of all pertinent parameters.
Abstract: A systematic, experimental study was conducted on the elementary process of devolatilization (DV) and the various parameters affecting it, using a specially designed apparatus, which is devoid of the flow complexities present in industrial equipment and which permits independent control of all pertinent parameters. The device simulates a flow configuration present in all rotating machinery used in DV, viz. the rotating melt pool. Parameters studied include exposure time, agitation rate, surface-to-volume ratio, melt viscosity, vapor pressure of volatile contaminant, applied vacuum level, concentration level of contaminant, and addition of inert substances for DV enhancement. The results of most parametric studies are presented here, but some will be published in a subsequent paper. All feed and product contaminant levels were analyzed using gas chromatography.
TL;DR: In this article, the spin-orbit splitting energies for the lowest doublet states of the atoms in Groups 13 and 17 of the Periodic Table were computed in procedures involving the use of spinorbit operators derived from relativistic effective core potentials (REP) and from separate calculations of the individual states in j-j coupling using REP's.
Abstract: Spin‐orbit splitting energies are presented for the lowest doublet states of the atoms in Groups 13 and 17 of the Periodic Table. The splittings are computed in procedures involving the use of spin‐orbit operators derived from relativistic effective core potentials (REP) and from separate calculations of the individual states in j–j coupling using REP’s. Comparison with experiment and with results due to all electron numerical Dirac–Fock calculations show that using the spin‐orbit operator as a first‐order perturbation to calculations carried out in LS coupling leads to an error of up to 7% in comparison to Dirac–Fock results. The indirect effect on the results due to orbital relaxation in the presence of the spin‐orbit operator recovers about one‐half of this error. The REP‐based spin‐orbit operator is shown to be quite accurate both for light and for heavy atoms. This is contrasted to the use of the spin‐orbit operator comprised of one‐ and two‐electron terms due to the Breit–Pauli approximation and Hartree–Fock wave functions, where the results degrade severely as the atomic mass increases. The nature of the spin‐orbit interaction in fluorine is discussed.
TL;DR: In this paper, the rate of CO/sub 2/S absorption in aqueous amine solution was investigated in view of the hindrance effect and compared with the linear amines.
TL;DR: In this article, a numerical simulation of propagating stall in a linear cascade of airfoils at high Reynolds numbers is conducted using a vortex method which was first developed by Spalart [7] for this problem.
Abstract: A numerical simulation of propagating stall in a linear cascade of airfoils at high Reynolds numbers is conducted using a vortex method which was first developed by Spalart [7] for this problem. In this approach, the vorticity is discretized into a large collection of vortex blobs whose motion is tracked in time by the use of a well-known vortex tracing algorithm based on the Euler equation. The near-wall effects of viscosity are accounted for by the creation of discrete vortex sheets at the boundaries of the airfoils consistent with the no-slip condition. These boundary vortices are then released into the flow field downstream of the separation points which are obtained from a boundary-layer routine. Calculations are presented for a variety of flow geometries. It is demonstrated that (for a given cascade of airfoils, disturbance wavelength, and stagger angle) several different flow regimes are obtained: Attached flow at lower angles of attack and a chaotic deep stall configuration at larger angles of attack with a narrow intermediate range of such angles where propagating stall occurs. The physical characteristics of this propagating stall are parameterized and a quantitative study of the effects of camber and imposed wavelength is conducted. Comparisons are made with previous theoretical and experimental studies.
TL;DR: The retarded nonrelativistic Schr\"odinger Green's function for an electron in crossed electric and magnetic fields is derived here in closed form.
Abstract: The retarded nonrelativistic Schr\"odinger Green's function for an electron in crossed electric and magnetic fields is derived here in closed form. The electric and magnetic fields are taken to be spatially uniform but the electric field may have arbitrary time dependence and arbitrary orientation with respect to the constant magnetic field.
TL;DR: A non-Boltzmann balance-equation approach to linear and nonlinear dc steadystate electronic transport in a type-I superlattice (which is composed of infinitely many periodically arranged finite-width quantum wells) is developed in this article.
Abstract: A non-Boltzmann balance-equation approach to linear and nonlinear dc steady-state electronic transport in a type-I superlattice (which is composed of infinitely many periodically arranged finite-width quantum wells) is developed in the presence of an electric field parallel to the superlattice planes. The method is based on a separation of the parallel motion of the center of mass from the relative motion of the electron system. The Coulomb interactions between intralayer and interlayer carriers are naturally built in via the electron density-density correlation function of the superlattice system. The force and energy balance equations obtained are applied to the calculation of the Ohmic mobilities limited by remote and background impurity scatterings and by acoustic and polar optical-phonon scatterings in GaAs-${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As superlattices. The nonlinear mobility and electron temperature are numerically calculated as functions of drift velocity, including all the above-mentioned scattering mechanisms and the full effect of carrier-carrier Coulomb interaction within the framework of the random-phase approximation. The dependence of transport on the geometrical parameters of the superlattice is discussed.
TL;DR: The inverse bifurcation sequence in one-dimensional maps is modified in two-dimensional ones in a universal way to lead to universal behavior including universal strange attractors.
Abstract: The inverse bifurcation sequence in one-dimensional maps is modified in two-dimensional ones in a universal way. Two-piece, four-piece, etc., strange attractors are eliminated one by one as the Jacobian approaches one. Renormalization theory around the Hamiltonian ${T}^{\mathrm{*}}$ leads to universal behavior including universal strange attractors.
TL;DR: In this paper, a set of procedures employing melt viscoelasticity functions for selecting components and composition of the binary polyblends and estimating minor phase domain size is introduced and illustrated with examples.
Abstract: Set of procedures employing melt viscoelasticity functions for selecting components and composition of the binary polyblends and estimating minor phase domain size is introduced and illustrated with examples. The procedures intended for Computer Aided Manufacture of the polyblends (CAMOBLE) are based on shear stress dependent viscoelasticity ratios, and the selection of the composition exploits stress dependent synergism of the viscoelasticity functions. Also used is auxilary procedure for composition selection is based on verified blending laws accounting for interaction and shear effects. Evaluation of the performance characteristics (“mechanical properties”) is illustrated with a modified Kerner model.
Posted Content•
TL;DR: Information Systems Working Papers Series is a series of papers by scientists and engineers looking at ways to improve the quality of research and development in the information systems industry.
Abstract: Information Systems Working Papers Series
TL;DR: It is shown that an IFCF-graph can be reduced to an edge by a recursive application of series, parallel and Δ-Y replacements, and this property forms the basis of an O|V|2 algorithm to compute the probability that a probabilistic IFCf-graph is connected.
Abstract: A planar graph G = V, E is an Inner-Four-Cycle-Free graph IFCF-graph if, after all series and parallel replacements, it has a planar embedding G' with a face f such that every cycle of G' having four or more edges contains a vertex of f It is shown that an IFCF-graph can be reduced to an edge by a recursive application of series, parallel and Δ-Y replacements This property forms the basis of an O|V|2 algorithm to compute the probability that a probabilistic IFCF-graph is connected This result is extended to graphs whose triconnected components are IFCF such graphs are not necessarily IFCF The class of IFCF-graphs includes the series-parallel graphs, wheel-graphs, ladder networks and graphs in normal form, for which polynomial network reliability algorithms are already known
04 Sep 1986
TL;DR: In this article, the authors analyse des permeateurs a membranes asymetriques: vitesses de transfert du gaz and separation a travers les membranes; compositions and configurations des membranes; analyse d'un permeateur pour la separation d'une binaire; schemas de separation for separation of binaires; separation of a melange complexe de gaz; methode de conception; procedes de separation des gaz par membrane.
Abstract: Revue des travaux actuels, en particulier, analyse des permeateurs a membranes asymetriques: vitesses de transfert du gaz et separation a travers les membranes; compositions et configurations des membranes; analyse d'un permeateur pour la separation d'un binaire; schemas de separation pour la separation d'un binaire; separation d'un melange complexe de gaz; methode de conception; procedes de separation des gaz par membrane
TL;DR: In this paper, the authors describe the applications of the Boundary Element Method (BEM) for studies on acoustical field of various vibrating structures, such as a circular piston in an infinite, rigid baffle and cantilever-type beams.
Abstract: This paper describes the applications of the Boundary-Element Method (BEM) for studies on acoustical field of various vibrating structures. The studies emphasize the numerical aspects of the BEM. Both acoustical near and far fields of the vibrating structures are investigated in this work. The vibrating structures considered in this application studies are a circular piston in an infinite, rigid baffle and cantilever-type beams. In the case of piston in an infinite baffle, instead of using the method of images, the free-space Green’s function is used to evaluate boundary integral equation by including both piston and baffle surfaces. The influence of the stationary baffle in the case of piston is further investigated. The beams considered are of both rectangular and circular cross sections. The results obtained by BEM have compared well with the available results from classical methods. The studies indicate that in the application of BEM in such problems both the element size and the number of elements including stationary surface have significant effect on the results obtained. The studies have yielded that very good results are obtained when the largest dimension of an element is equal to 0.2 times the acoustic wavelength (in air) of the frequency of acoustic radiation.