Showing papers by "Technion – Israel Institute of Technology published in 1972"
TL;DR: Algorithms for finding a maximum size clique and a minimum coloration of transitive grapl are presented and are applicable in solving problems in memo] allocation and circuit layout.
Abstract: A graph G with vertex set N = {1, 2, .-. , n} is called a permutation graph there exists a permutation P on N such that for i , j E N, (i j)[P-'(i) P-'(j)] < 0 if ar only if i and j are joined by an edge in G. A structural relationship is established between permutation graphs and transitive graph An algorithm for determining whether a given graph is a permutation graph is given. Efficie, algorithms for finding a maximum size clique and a minimum coloration of transitive grapl are presented. These algorithms are then shown to be applicable in solving problems in memo] allocation and circuit layout.
186 citations
TL;DR: In this article, the authors examine conditions under which a function g(x,t,...,t ) provides, via composition, a 1 m mapping between Sobolev spaces, and examine conditions which ensure that for every system of functions u_,...,u e W _ (Q) 1 m 1, q (where W, q is the class of L functions with L summable i,q q q q strong first derivatives on the domain Q, c: R )S the composite function v given by v(x) = g (x,un(
Abstract: The present paper is concerned with the circumstances under which a function g(x,t ,...,t ) provides, via composition, a ^ 1 m mapping between Sobolev spaces. That is, we examine conditions which ensure that for every system of functions u_,...,u e W _ (Q) 1 m 1, q (where W, (Q) is the class of L functions with L summable i,q q q strong first derivatives on the domain Q, c: R )S the composite function v given by v(x) = g(x,un(x) , . . . ,u (x) ) belongs to Wn _(£})> with preassigned 1 R locally absolutely continuous and ueW (H) , JL _L -L} 1 "I r\r+ lOC one has v(x) = g(u(x)) eW, ,(fl) if and only if g' (u(x) ) Vu(x) eL. (0) ~ ~ 1,1 ~ ~ l
185 citations
TL;DR: In this article, a new technique has been developed for the investigation of double layers on solid electrodes enabling the direct measurement of ion adsorption and the detection of the electrocapillary maximum.
160 citations
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TL;DR: A family of real functions, called r-convex functions, which represents a generalization of the notion of convexity is introduced, and is included in the family of quasiconveX functions.
Abstract: A family of real functions, calledr-convex functions, which represents a generalization of the notion of convexity is introduced This family properly includes the family of convex functions and is included in the family of quasiconvex functions Some properties ofr-convex functions are derived and relations with other generalizations of convex functions are discussed
126 citations
TL;DR: In this article, the relationship between drop size and location in an agitated liquid-liquid system was investigated, with a new sampling method in which the dispersion was sampled in a specially designed trap and immediately encapsulated by a polymer film.
Abstract: The relationship between drop size and location in an agitated liquid-liquid system was investigated, with a new sampling method in which the dispersion was sampled in a specially designed trap and immediately encapsulated by a polymer film. The liquid-liquid system used was water and a mixture of isooctane and carbon tetrachloride with a density closed to that of the water. Dispersed phase holdup was varied from 0.025 to 0.34 volume fraction.
For this system, which has low mutual sulubility and high interfacial tension, there is almost no dependence of drop size on location for the mixing geometries studied. This was due to the fact that the coalescence rate is low compared to the circulation time. An increase in impeller speed and drop size decreased the coalescence rate while an increase in holdup increased it.
The mean drop diameter was related to the Weber number and holdup by an equation. By comparison of mean drop diameters obtained using different impellers, it was shown that the criterion of equal power per volume can be used for estimating drop size when going from one mixing geometry ot another, not too different, geometry at moderate impeller speeds.
126 citations
120 citations
115 citations
TL;DR: In this paper, a large deformation elastic-viscoplastic theory is formulated which considers both elastic and inelastic deformations to be present at all stages of loading and unloading, and does not require the assumption of a yield criterion or the prior determination of whether the material is loading or unloading.
Abstract: : A large deformation elastic-viscoplastic theory is formulated which considers both elastic and inelastic deformations to be present at all stages of loading and unloading The theory does not require the assumption of a yield criterion or the prior determination of whether the material is loading or unloading The theory is based on relating the essential parameters to state variables; the particular constitutive relations are motivated by the equations of dislocation dynamics A numerical scheme for calculating deformations is developed and applied to a thick walled spherical shell under internal pressure Various numerical examples are presented (Author)
111 citations
TL;DR: The possibility that Protein 1 comprises the active site for mRNA binding on the 30-S ribosome, or at least contributes to it, is discussed and Aurintricarboxylic acid, which inhibits binding of poly(U) to ribosomes, has the same effect on binding ofpoly( U) to the pure Protein 1 preparation at a similar concentration.
99 citations
TL;DR: In this article, an analysis of quenched reacting mixtures and kinetic model calculations indicated that the additive influence was chemical and not thermal, and an explanation was advanced for the thermal correlation and its breakdown.
98 citations
TL;DR: Based on a model of a suspension of interacting particles in a pseudoplastic solvent, a rheological equation was developed which could describe the flow properties of concentrated orange juice in this paper.
Abstract: Based on a model of a suspension of interacting particles in a pseudoplastic solvent, a rheological equation was developed which could describe the flow properties of concentrated orange juice. The function was obtained by modifying Casson’s equation and has the following form:
The magnitude of the parameter ko is affected by the concentration of the suspended particles, the concentration of soluble pectin and by conditions favorable for pectin gel formation. The other two parameters, k and m, are determined mainly by the solvent properties. The mechanism responsible for the flow behaviour of the concentrated orange juice under various conditions could be predicted and explained by the properties of the components in the system.
TL;DR: In this paper, it was shown that k does not carry complete quantum-mechanical information about the motion of an electron in a periodic structure, and that k is not a suitable coordinate in describing the motion in the Bloch theory of conduction electrons.
Abstract: Publisher Summary In the Bloch theory of conduction electrons in solids, the concept of quasimomentum k is of great importance, because it is a conserved quantity and, in addition, it carries the significant information about the momentum of the electron. One should expect k to be a suitable coordinate in describing the motion of an electron in a periodic structure. It can, however, be seen that k does not carry complete quantum-mechanical information about the motion. From the point of view of elementary quantum mechanics, it is possible along with k to specify also to some extent the coordinate of the electron. This is so because k carries only partial information about the linear momentum p of the electron and when k is given, p is defined only up to an additive constant, 2πħ/a, where a is the lattice constant. It can easily be seen in this chapter that along with k quantum mechanics allows also to specify the quasicoordinate q of the electron that gives the position x up to the additive constant a. The coordinate q carries the most relevant information about the location of the electron in a periodic structure. The periodic potential of a crystal varies only inside a unit cell and is therefore a function of the quasicoordinate q only. From the point of view of the periodic structure it is completely irrelevant in which of the unit cells the electron is located. This chapter demonstrates the usefulness of the coordinates k and q in the following examples: The impurity problem in semiconductors, the dynamics in a constant electric field, and the effective Hamiltonian for a Bloch electron in a magnetic field.
TL;DR: Progressive age-dependent accumulation of pigment granules containing acid phosphatase activity was demonstrated in the intestinal epithelium of ageing animals, and it is suggested that these granules are age-pigment which is the product of peroxidation of cellular constituents.
TL;DR: A positive correlation between the delay in age-pigment accumulation and the prolongation of life span was shown and the significance of the effect of antioxidant on the life span and cell damage, and the possible role of peroxidation reactions in senescence, are discussed.
TL;DR: In this article, the authors used the Landau-Devonshire theory of perovskite ferroelectrics to explain the morphotropic phase transition in the ceramic solid solutions Pb(Zr, Ti) O3.
TL;DR: In this paper, the authors extended the analysis of viscous flow in concentrated solid suspensions to include concentrated emulsions of slightly deformable fluid particles in the presence or absence of surfactant impurities.
Abstract: Previous analysis byHappel (3) of viscous flow in concentrated solid suspensions has been extended to include concentrated emulsions of slightly deformable fluid particles in the presence or absence of surfactant impurities General expressions were obtained for viscous flow in multi-particle systems when arbitrary shear fields are imposed Specific relations were then derived for uniform,Couette and hyperbolic fields The behavior is found to be strongly dependent upon particle concentration and surfactant concentration The theoretical expressions obtained for effective viscosity of emulsions compare favorably with experimental data ofNeogy andGhosh (18),Sibree (15),Sherman (17), andBroughton andWindebank (16) These results support other studies on ensemble velocities [(10), (12), and in particular (22)], which strongly indicate the practical value and factual reliability of cell models in predicting the behavior of suspensions and emulsions
TL;DR: New techniques are presented for generating fault-detection experiments for combinational logic networks and provide minimal experiments for detecting multiple faults in two-level networks and nearly minimal experiments in most other networks.
Abstract: New techniques are presented for generating fault-detection experiments for combinational logic networks. Only single-output functions are considered. Test-covering and test-equivalence relations between networks are defined and these relations are shown to be Instrumental in generating the experiments. The techniques presented provide minimal experiments for detecting multiple faults In two-level networks and provide nearly minimal experiments for most other networks.
TL;DR: In this paper, an improved theoretical model was derived for the solids conveying zone of a plasticating extruder, making possible calculations in variable channel depth section, and an expression for maximum flow rate was also derived.
Abstract: An improved theoretical model was derived for the solids conveying zone of a plasticating extruder. The model makes possible calculations in variable channel depth section. It also allows for a bulk density which is a function of pressure and for the non-isotropic pressure distribution in the solid plug. An expression for maximum flow rate was also derived. Results simulated by the model on a computer indicate the effect of variables on extruder performance. The power consumption terms in the solids conveying zone of a plasticating extruder were also derived. Total power consumption is the sum of power consumptions on the barrel surface, screw surfaces and those due to pressure rise. Their relative importance was analyzed by computations. The effect of operating conditions and coefficients of friction on the various power terms was also analyzed.
TL;DR: A review of measured breakdown properties in insulating films and of electronic theories of breakdown shows both theoretical and experimental inconsistencies as discussed by the authors, and a theory is proposed in which electronic breakdown is caused by local chance events such as a succession of avalanches at one spot.
Abstract: A review of measured breakdown properties in insulating films and of electronic theories of breakdown shows both theoretical and experimental inconsistencies. A theory is proposed in which electronic breakdown is caused by local chance events, such as a succession of avalanches at one spot. Successive avalanches sustain the growth of space charges, the local cathode field, and the avalanche rate. When the cathode field becomes large enough to make continuation of avalanching a certainty, instability with current runaway arises, causing breakdown. According to theory, breakdowns occur over a range of fields, their chance increasing very strongly with field; the breakdowns occur randomly in space and in time; the time to instability on a breakdown event decreases as some exponential function of increasing field; the breakdown field can both increase and decrease with temperature; it may be electrode dependent, and it decreases first rapidly and then more slowly with increasing film thickness. Obser...
TL;DR: In this article, a mathematical model has been developed to calculate the temperature profile in the solid plug together with the strongly interacting pressure profile, which indicates that high pressure in the solids conveying zone can practically be obtained only by very efficient cooling of the barrel in this zone.
Abstract: Isothermal solids conveying theories have been developed in the past. However, due to friction, the surface temperature of the solid plug does increase. This change in temperature will strongly affect the temperature sensitive coefficients of friction and consequently also the pressure that develops. The surface temperature of the solid plug is also an important variable on its own because, when it reaches the melting point, the solids conveying zone is terminated. A mathematical model has been developed to calculate the temperature profile in the solid plug together with the strongly interacting pressure profile. Calculations indicate that high pressure in the solids conveying zone can practically be obtained only by very efficient cooling of the barrel in this zone.
TL;DR: In this article, a theoretical study of the phenomenon for the two-dimensional steady flow past a blunt body of semi-infinite length is presented, where the exact equations of free-surface gravity flow are solved approximately by two perturbation expansions.
Abstract: Most of the wave resistance of blunt bow displacement ships is caused by the bow-breaking wave. A theoretical study of the phenomenon for the two-dimensional steady flow past a blunt body of semi-infinite length is presented. The exact equations of free-surface gravity flow are solved approximately by two perturbation expansions. The small Froude number solution, representing the flow beneath an unbroken free surface before the body, is carried out to second order. The breaking of the free surface is assumed to be related to a local Taylor instability, and the application of the stability criterion determines the value of the critical Froude number which characterizes breaking. The high Froude number solution is based on the model of a jet detaching from the bow and not returning to the flow field. The outer expansion of the equations yields the linearized gravity flow equations, which are solved by the Wiener-Hopf technique. The inner expansion gives a nonlinear gravity-free flow in the vicinity of the bow a t zero order. The matching of the inner and outer expansions provides the jet thickness as well as the associated drag.
01 Jan 1972
TL;DR: In this article, it was shown that there exists an ann×n matrix all of whose eigenvalues and off-diagonal elements are prescribed, and the number of such matrices is finite.
Abstract: It is shown that there exists ann×n matrix all of whose eigenvalues and off-diagonal elements are prescribed. The number of such matrices is finite.
TL;DR: In this paper, the oxide formed after first oxidation was found to be SiO2 only, substantiated by several types of measurements, and higher order oxidations included an increasing amount of Ge.
TL;DR: In this article, the existence of disjoint sets has been studied in the context of set-theoretic axioms and existence theorems, and the authors solve some problems arising from a work by Hechler.
Abstract: We solve here some problems arising from a work by Hechler [3]. We eliminate extra set-theoretic axioms (MA, in fact) from existence theorems and deal with the existence of disjoint sets.
TL;DR: In this paper, the conductivity and the Hall effect of pure CoO and of CoO doped with titanium or chromium have been measured over a wide range of oxygen pressures and the range of temperatures was 988-1280°C.
TL;DR: In this article, a theoretical model was developed for the newly defined delay zone of the plasticating screw extruder, and the results indicated that the film thickness at the end of the delay zone is several times the flight clearance.
Abstract: A theoretical model was developed for the newly-defined delay zone of the plasticating screw extruder. The delay zone starts at the end of the solids conveying zone, i.e. at the point where the solid plug surface contacting the barrel melts and forms a film of melt up to where the steady state melting mechanism starts to operate. The model permits the film thickness and pressure profiles in this zone to be calculated. Published results were used to support the validity of the model. The results indicate that the film thickness at the end of the delay zone is several times the flight clearance. Finally, a criteria, based on the final value of the film thickness, is suggested to calculate the length of the delay zone.
TL;DR: It is proved that for balanced incomplete block designs with blocks having five elements each the known necessary existence condition is also sufficient, with the exception of the non-existing design λ = 2, v = 15.