Showing papers by "Technion – Israel Institute of Technology published in 1975"
TL;DR: In this paper, a set of constitutive equations has been formulated to represent elastic-viscoplastic strain hardening material behavior for large deformations and arbitrary loading histories, and the total deformation rate is considered to be separable into elastic and inelastic components which are functions of state variables at all stages of loading and unloading.
Abstract: : A set of constitutive equations has been formulated to represent elastic-viscoplastic strain hardening material behavior for large deformations and arbitrary loading histories. An essential feature of the formulation is that the total deformation rate is considered to be separable into elastic and inelastic components which are functions of state variables at all stages of loading and unloading. The theory, therefore, is independent of a yield criterion or loading and unloading conditions. The deformation rate components are determinable from the current state which permits an incremental formulation of problems. Strain hardening is considered in the equations by introducing plastic work as the representative state variable. The problem of uniaxial straining has been examined for a number of histories that included straining at various rates, rapid changes of strain rate, unloading and reloading, and stress relaxation. The calculations were based on material constants chosen to represent commercially pure titanium. The results are in good agreement with corresponding experiments on titanium specimens. (Author)
942 citations
TL;DR: The read would be well advised to have knowledge of primWe roots and residua classes modultb primes, as well as of finite Gcllois ficlde5, necessary to understand the problems of inequality in this paper.
507 citations
TL;DR: Contrary to the present view of fire as simply destructive, both fire and grazing have favored genetical as well as ecological diversity and should be studied as integral components of Mediterranean ecosystems and their evolution.
Abstract: Fire has played a decisive role in Post-Glacial biological and cultural evolution in the Mediterranean Region. Its evolutionary impact on plants has been manifested by feedback responses, in which the fire and its after-effects selected plants for physiological and other mechanisms that enable direct fire tolerance or permit avoidance followed by vegetative and reproductive regeneration.
470 citations
TL;DR: An improved technique for bounding the mean-square error of signal parameter estimates is presented and the resulting bounds are independent of the bias and stronger than previously known bounds.
Abstract: An improved technique for bounding the mean-square error of signal parameter estimates is presented. The resulting bounds are independent of the bias and stronger than previously known bounds.
213 citations
TL;DR: In this article, the drift velocities per unit current density ranged between 10-13 and 10-15 cm3 A-1 s-1 and the gold motion was always in the direction of electron flow.
162 citations
TL;DR: Computer controlled radiant heat stimulation for a combined psychophysical and electrophysiological research in pain was achieved by the use of an infrared Laser beam, suitable for recording of averaged evoked responses as well as for determination of pain and thermal thresholds.
Abstract: Controlled radiant heat stimulation for a combined psychophysical and electrophysiological research in pain was achieved by the use of an infrared Laser beam. The computer controlled stimuli, being of very brief duration (down to 5 msec) and sharply localized, are suitable for recording of averaged evoked responses as well as for determination of pain and thermal thresholds. These stimuli can be applied to any locus on the skin. The threshold energy delivered by this technique is similar to that obtained by the Hardy-Wolff-Goodell method. Special precautions were taken to avoid injury to the skin and the eyes.
160 citations
TL;DR: In this paper, it was shown that the electronic charge density of a ground-state atom decreases monotonically as a function of radial distance from the nucleus, contrary to the widespread belief that the shell structure is reflected by relative maxima in the density.
Abstract: It is shown that the electronic charge density of a ground-state atom decreases monotonically as a function of radial distance from the nucleus, contrary to the widespread belief that the shell structure is reflected by relative maxima in the density. Any proposed relationship between chemical bonding and the maxima in the radial density functions of atoms should therefore be regarded with caution. It is proven that the electrostatic potential of an atom must be monotonically decreasing. The changes in charge distribution upon molecule formation are also discussed.
152 citations
TL;DR: In this paper, experimental investigation of failure of balanced angle-ply laminates under symmetric uniaxial tension revealed three distinct failure modes for reinforcement angles smaller than ±45°.
Abstract: Experimental investigation of failure of balanced angle-ply laminates under symmetric uniaxial tension revealed three distinct failure modes. The three different modes were observed for reinforcement angles smaller than ±45°, for the ±45° angle ply and for angles larger than ±45°. Comparison of experimental failure loads with theoretical failure loads based on first laminate failure criteria showed good agreement for certain ranges of reinforcement angle and disagreement for others.
119 citations
01 Jan 1975
TL;DR: In this paper, an inviscid flow model is employed to show that by proper positioning fish in a tightly packed school can utilize part of the energy shed by their neighbors. But this model is not suitable for the case of fish swimming close to each other in synchronization.
Abstract: Hydrodynamical interactions between fish swimming close to each other in synchronization at equal velocities are examined. An inviscid flow model is employed to show that by proper positioning fish in a tightly packed school can utilize part of the energy shed by their neighbors.
115 citations
TL;DR: In this article, the synthesis of α-alkyl mercaptohippuric acid (3a-d), N-benzyloxycarbonyl-α-methylthioglycine (3e) and their methyl esters (5a−d) was described.
114 citations
TL;DR: In this paper, a cutting plane algorithm for the solution of generalized geometric programs with bounded variables is described and illustrated by the detailed solution of a small numerical example, and convergence of this algorithm to a Kuhn-Tucker point of the program is assured if an initial feasible solution is available to initiate the algorithm.
Abstract: A cutting plane algorithm for the solution of generalized geometric programs with bounded variables is described and then illustrated by the detailed solution of a small numerical example. Convergence of this algorithm to a Kuhn-Tucker point of the program is assured if an initial feasible solution is available to initiate the algorithm. An algorithm for determining a feasible solution to a set of generalized posynomial inequalities which may be used to find a global minimum to the program as well as test for consistency of the constraint set, is also presented. Finally an application in optimal engineering design with seven variables and fourteen nonlinear inequality constraints is formulated and solved.
TL;DR: In this paper, a model sequencing algorithm for model-mix assembly lines is proposed, the objective function of which is to minimize the overall assembly line-length for no operator interference.
Abstract: SUMMARY This paper describes a model sequencing algorithm for model-mix assembly lines. A new formulation of the sequencing problem is proposed, the objective function of which is to minimize the overall assembly line-length for no operator interference. Lower bounds for the overall line-length are developed. Two types of work station interfaces are considered; ‘closed’, where boundaries cannot be violated, and ‘open’ where defined boundaries do not exist—adjacent operators being allowed to enter each others apparent work areas without causing any interference. A complete factorial experiment was made on five factors to determine their influence on the overall assembly line length. These are, the number of models, the model cycle time deviation, the production demand deviation for each model, the operator time deviation, and the number of stations in the assembly line. The main conclusions of this experiment are discussed and recommendations made for the selection of parameters used in the design of model...
TL;DR: In this article, the axisymmetric vibrations of radially polarized piezoelectric ceramic long tubes, whose cylindrical surfaces are electroded and subjected to an alternating voltage, were established for axisymetric vibrations.
TL;DR: In this paper, a new method is described for the evaluation of impact ionization coefficients, α, in insulators by the measurement of current transients which grow due to impact ionisation.
TL;DR: In this article, the authors developed and measured a concept of Work-Role Centrality, mainly from a cognitive perspective, and examined by means of questionnaire data its distribution in a representative sample of 778 males participating in the labor force in Israel.
Abstract: This study develops and measures a concept of Work-Role Centrality, mainly from a cognitive perspective, and examines by means of questionnaire data its distribution in a representative sample of 778 males participating in the labor force in Israel. It also investigates the relationship between specific job rewards and work-role centrality for the five major occupational categories in this sample. Its results show that work-role centrality is a fairly reliable and valid measure: groups of different ethnic origin, educational level, employment status, and occupation differ in their work centrality, in the directions hypothesized a priori. It also demonstrates that for each occupational category, work centrality is related to intrinsic, material, social, and hygienic rewards, regardless of the importance assigned to these rewards. For all groups the strongest relationship is with intrinsic rewards. The findings concerning the relationship with intrinsic rewards corroborate previous studies, while the other ...
TL;DR: In this paper, a controlled experiment was conducted to determine the relative importance of pedestrian, vehicle, and situational factors in influencing drivers to give way to crossing pedestrians in a crosswalk scenario.
Abstract: A controlled experiment was conducted to determine the relative importance of pedestrian, vehicle, and situational factors in influencing drivers to give way to crossing pedestrians. The following ...
01 May 1975
TL;DR: In this paper, a quadratic extended interior penalty function formulation especially well suited for second-order unconstrained optimization procedures is presented, where analytical derivatives of constraints and an approximate analysis technique are used.
Abstract: A quadratic extended interior penalty function formulation especially well suited for second-order unconstrained optimization procedures is presented. Analytical derivatives of constraints and an approximate analysis technique are used. Minimum-mass design results are presented which indicate that the combination of these procedures can help make mathematical programming a useful optimization tool for large-order structural design problems with a large number of design variables and multiple constraints. Examples include statically loaded high- and low-aspect-ratio wings simultaneously subjected to stress, displacement, minimum gage and, in some cases, maximum strain constraints.
TL;DR: In this paper, the authors studied the behavior of cottonseed oil which had been exposed to frying under controlled conditions in a system in which only the oil, water and/or the antioxidant BHT were present.
Abstract: The behaviour was studied in cottonseed oil which had been exposed to frying under controlled conditions in a system in which only the oil, water and/or the antioxidant BHT were present. In the oils, changes which had been caused by heating were evaluated through determination of acid, hydroxyl, TBA and iodine values, extinctions at 232 nm and 460 nm, fatty acid composition, viscosity, amounts of “polymers” and non-urea-adduct-forming fatty acid methyl esters. All the changes were less pronounced when the frying was carried out in presence of either nitrogen or water. The latter protected the oil only if it was present in amounts sufficient to generate such a volume of vapours which could effectively act as an inert gas-blanket. BHT had no delaying effect on the deterioration of the oil during frying. When the oil was heated in the presence of air, the antioxidant's destruction was lessened by the presence of water in the system, but a large portion of BHT was lost through steam distillation.
TL;DR: A lower bound on the minimal mean-square error in estimating nonlinear Markov processes is presented, based on the Van Trees' version of the Cramer-Rao inequality.
Abstract: A lower bound on the minimal mean-square error in estimating nonlinear Markov processes is presented. The bound holds for causal and uncausal filtering. The derivation is based on the Van Trees' version of the Cramer-Rao inequality.
TL;DR: Addition of dicyclohexylcarbodiimide reversed the light-induced pH changes to the normal proton uptake and increased the pH optimum of the Hill reaction.
Abstract: Chloroplasts were treated with 2 m sodium bromide. The resulting particles lost their ATPase activity and chloroplast coupling factor 1 subunits were detected in the supernatant by means of gel electrophoresis and specific antibodies. The chloroplast coupling factor 1 depleted particles show high rates of Hill reaction with pH optimum shifted toward lower pH. The sodium bromide treatment also abolished the light-induced proton uptake. In the presence of N-methylphenazonium methosulfate light-induced proton release, insensitive to uncouplers, was observed. Addition of dicyclohexylcarbodiimide reversed the light-induced pH changes to the normal proton uptake and increased the pH optimum of the Hill reaction.
TL;DR: In this paper, the degradation process is attributed to penetration of water into the matrix-fiber interfaces and is followed by an attack, at high temperatures, on the glass-fibers surface and coupling agent.
Abstract: Glass-fiber reinforced epoxy (GRP) and unfilled epoxy specimens were exposed to different environmental conditions consisting of hot- and cold-water absorption and subsequent drying. Effects of the environmental history on deformational and strength characteristics of the composite material were investigated.
GRP specimens exposed to hot water undergo pronounced degradation, which sets in shortly after exposure and is associated with a significant irrecoverable weight loss. Degraded specimens are characterized by higher void content and lower strength compared with their cold-water and reference counterparts. The degradation process is attributed to penetration of water into the matrix-fiber interfaces and is followed by an attack, at high temperatures, on the glass-fibers surface and coupling agent. As a result, glass constituents are leached out and then removed from the system by diffusion.
The degradation effect was also confirmed by micro-observation of the fractured surfaces and by infra-red spectroscopy. A simple and effective testing method is recommended, permitting detection of degradation onset and its progress by simultaneous measurement of weight and dimensional changes with time.
TL;DR: In this paper, three ion exchange processes are characterized by a sharp moving boundary between the reacted shell and the shrinking unreacted core within each ion-exchanger bead, which is controlled by the rate of diffusion of the ions penetrating the reacted layer.
TL;DR: In this article, the authors determined the coexistence region near the morphotropic phase change of the PZT, where the tetragonal and the rhombohedral phases coexist.
Abstract: By means of X-ray diffraction, the authors have determined directly the coexistence region near the morphotropic phase change of the PZT, where the tetragonal and the rhombohedral phases coexist. In this region the lattice parameters of each phase do not change, and the relative amounts obey the leverage rule. The authors show that the morphotropic phase change may be considered as a first-order transition as a function of the temperature and the chemical potential (and not the concentration, as often supposed).
TL;DR: A comparative study is made between three methods for balancing single-model assembly lines, 10-SP, which selects the best of ten single-pass solutions; ARCUS—a random multi-pass method, and MALB, an iterative backtracking method.
Abstract: A comparative study is made between three methods for balancing single-model assembly lines. These include: 10-SP, which selects the best of ten single-pass solutions; ARCUS—a random multi-pass method, and MALB, an iterative backtracking method. The assembly tasks contain up to 140 work elements with widely differing precedence structures. Measurements of the Balance Delay are used for comparing the solution efficiencies and computation times are also compared. The experiments show significant differences between the three line balancing methods and that these differences are accentuated for certain conditions of task size, precedence structure and the imposed balancing requirements. It is shown that 10-SP is yet another simple but effective technique for balancing single-model assembly lines.
TL;DR: In this article, it was shown that the dual space of a compact linear operator from E to F is either reflexive or nonconjugate, and applications of these results are also given.
Abstract: LetE andF be reflexive Banach spaces andC the space of all compact linear operators fromE toF. A representation of the dual space ofC is given and it is proved thatC is either reflexive or nonconjugate. Applications of these results are also given.
TL;DR: Statistical analysis has shown that the experimental accumulative curves can be best described by a single parameter exponential equation Y = 1 − e−λα where Y is the accumulative fraction of fibers, α is the orientation angle and λ is a single empirical parameter.
Abstract: Oriented short fiberglass mats were prepared by a converging flow technique of fiber/glycerine dispersions. The fiberglass contained 3 percent of identical colored fibers which were counted from enlarged photographs in regard to their deviation from the alignment axis. Representative accumulative data of fiber alignment are shown for optimal and inadequate preparation conditions. In successful experiments over 90 percent of the fibers were found in the angular range of ±15 deg and 57 percent within the range of ±5 deg. Statistical analysis has shown that the experimental accumulative curves can be best described by a single parameter exponential equation Y = 1 − e−λα where Y is the accumulative fraction of fibers, α is the orientation angle and λ is a single empirical parameter.
01 Feb 1975
TL;DR: The probability distribution of the optimum of an integer linear program is discussed in which the elements of the right-hand-side (RHS) are distributed independently and the assumptions of the asymptotic algorithm of Gomory are supposed to hold for each realization of the RHS.
Abstract: The probability distribution of the optimum (Z) of an integer linear program is discussed in which the elements of the right-hand-side (RHS) are distributed independently. The assumptions of the asymptotic algorithm ofGomory are supposed to hold for each realization of the RHS. This algorithm serves also as the theoretic framework of the present communication. Bounds and approximations for the probability function of Z are derived demanding different levels of numerical efforts. The normal distribution is a satisfactory approximation which is asymptotically correct if the elements of the RHS are uniformly distributed within bounds satisfying some requirements and the number of inequalities approaches infinity.