Showing papers by "Technion – Israel Institute of Technology published in 1986"
TL;DR: In this paper, the authors study the effects of an imperfect production process on the optimal production cycle time and derive the optimal cycle time for the case where the defective rate is a function of the set-up cost.
Abstract: In this paper, we study the effects of an imperfect production process on the optimal production cycle time. The system is assumed to deteriorate during the production process and produce some proportion of defective items. The optimal production cycle is derived, and is shown to be shorter than that of the classical Economic Manufacturing Quantity model. The analysis is extended to the case where the defective rate is a function of the set-up cost, for which the set-up cost level and the production cycle time are jointly optimized. Finally, we also consider the case where the deterioration process is dynamic in its nature, i.e., the proportion of defective items is not constant. Both linear, exponential, and multi-state deteriorating processes are studied. Numerical examples are provided to illustrate the derivation of the optimal production cycle time in these situations.
1,021 citations
TL;DR: It is suggested that inexperienced physicians should first attempt central vein catheterizations in unconscious and mechanically ventilated patients, whereas in conscious patients these rates were 70.5% and 13.8%, respectively.
Abstract: • We prospectively studied the results of 714 attempts at central venous catheterization during an eight-month period in our intensive care department. We compared the rates of failure of catheterization and early complications among three percutaneous approaches: subclavian, anterior jugular, and posterior jugular veins. The procedures were performed by experienced staff or resident physicians and inexperienced interns and residents under teaching supervision. Overall rates of failure and complication were similar for each percutaneous approach within each group of physicians. Overall failure rate was 10.1% for the experienced group and 19.4% for the inexperienced. The complication was 5.4% for experienced and 11% for inexperienced. Among inexperienced physicians, the success rate was 86.7% and the complication rate 7.6% in unconscious patients, whereas in conscious patients these rates were 70.5% and 13.8%, respectively. The inexperienced physicians caused fewer complications in mechanically ventilated than in spontaneously breathing patients. We suggest that inexperienced physicians should first attempt central vein catheterizations in unconscious and mechanically ventilated patients. (Arch Intern Med1986;146:259-261)
621 citations
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TL;DR: In this article, an algorithm is presented that can be used to design new bus routes taking account of both passenger and operator interests; however, this algorithm focuses on only a single component of the overall bus operations planning process described in this paper.
Abstract: This paper describes the bus network design problem, summarizes the different approaches that have been proposed for its solution and proposes a new approach incorporating some of the positive aspects of prior work. The proposed approach is intended to be easier to implement and less demanding in terms of both data requirements and analytical sophistication than previous methods. An algorithm is presented that can be used to design new bus routes taking account of both passenger and operator interests; however, this algorithm focuses on only a single component of the overall bus operations planning process described in this paper.
553 citations
01 Jan 1986
TL;DR: Consideration is given to normative and descriptive approaches; subjective, performance, and arousal measures; performance operating characteristics; and psychophysiological measures of workload.
Abstract: The relations between task difficulty and workload and workload and performance are examined. The architecture and limitations of the central processor are discussed. Various procedures for measuring workload are described and evaluated. Consideration is given to normative and descriptive approaches; subjective, performance, and arousal measures; performance operating characteristics; and psychophysiological measures of workload.
538 citations
TL;DR: In this paper, a variant of the Byzantine Generals problem is considered, in which processes start with arbitrary real values rather than Boolean values or values from some bounded range, and in which approximate, rather than exact, agreement is the desired goal.
Abstract: This paper considers a variant of the Byzantine Generals problem, in which processes start with arbitrary real values rather than Boolean values or values from some bounded range, and in which approximate, rather than exact, agreement is the desired goal. Algorithms are presented to reach approximate agreement in asynchronous, as well as synchronous systems. The asynchronous agreement algorithm is an interesting contrast to a result of Fischer et al, who show that exact agreement with guaranteed termination is not attainable in an asynchronous system with as few as one faulty process. The algorithms work by successive approximation, with a provable convergence rate that depends on the ratio between the number of faulty processes and the total number of processes. Lower bounds on the convergence rate for algorithms of this form are proved, and the algorithms presented are shown to be optimal.
531 citations
TL;DR: In this article, the extinction rules for three of the five icosahedral Bravais quasilattices are compared, and some simple relationships with the six-dimensional cut and projection crystallography are derived.
Abstract: Since the definition of quasiperiodicity is intimately connected to the indexing of a Fourier transform, for the case of an icosahedral solid, the step necessary to prove, using diffraction, that an object is quasiperiodic, is described. Various coordinate systems are discussed and reasons are given for choosing one aligned with a set of three orthogonal two-fold axes. Based on this coordinate system, the main crystallographic projections are presented and several analyzed single-crystal electron diffraction patterns are demonstrated. The extinction rules for three of the five icosahedral Bravais quasilattices are compared, and some simple relationships with the six-dimensional cut and projection crystallography are derived. This analysis leads to a simple application for indexing powder diffraction patterns.
432 citations
TL;DR: In this paper, the authors examine how incentives for two duopolists to honestly share information change depending upon the nature of competition (Cournot or Bertrand) and the information structure.
Abstract: We examine how incentives for two duopolists to honestly share information change depending upon the nature of competition (Cournot or Bertrand) and the nature of the information structure. While in earlier papers uncertainty is about an unknown common demand intercept, in the present paper uncertainty is about unknown private costs. The different information structure reverses the incentives to share information. While with unknown common demand sharing is a dominant strategy with Bertrand competition and concealing is a dominant strategy with Cournot competition, with unknown private costs sharing is a dominant strategy with Cournot competition and concealing is a dominant strategy with Bertrand competition.
432 citations
TL;DR: In this article, three experiments were conducted to investigate the 24-hour structure of sleepiness after 1 night of sleep deprivation under two experimental conditions: instructing subjects to attempt to fall asleep or instructing subject to resist sleep.
420 citations
TL;DR: It is suggested that inexperienced physicians should first attempt central vein catheterizations in unconscious and mechanically ventilated patients, whereas in conscious patients these rates were 70.5% and 13.8%, respectively.
Abstract: • We prospectively studied the results of 714 attempts at central venous catheterization during an eight-month period in our intensive care department. We compared the rates of failure of catheterization and early complications among three percutaneous approaches: subclavian, anterior jugular, and posterior jugular veins. The procedures were performed by experienced staff or resident physicians and inexperienced interns and residents under teaching supervision. Overall rates of failure and complication were similar for each percutaneous approach within each group of physicians. Overall failure rate was 10.1% for the experienced group and 19.4% for the inexperienced. The complication was 5.4% for experienced and 11% for inexperienced. Among inexperienced physicians, the success rate was 86.7% and the complication rate 7.6% in unconscious patients, whereas in conscious patients these rates were 70.5% and 13.8%, respectively. The inexperienced physicians caused fewer complications in mechanically ventilated than in spontaneously breathing patients. We suggest that inexperienced physicians should first attempt central vein catheterizations in unconscious and mechanically ventilated patients. (Arch Intern Med1986;146:259-261)
389 citations
TL;DR: Routine activities of early life history stages of fishes occur in an intermediate hydrodynamic environment, between a zone where drag is linearly dependent on velocity and resistive forces make large contributions to thrust, and a Zone where inertial forces dominate except in the boundary layer immediately adjacent to the body surface.
Abstract: Routine activities of early life history stages of fishes occur in an intermediate hydrodynamic environment (as identified by Reynolds numbers), between a zone where drag is linearly dependent on velocity and resistive forces make large contributions to thrust, and a zone where inertial forces dominate except in the boundary layer immediately adjacent to the body surface. Sprint performance carries larvae into this latter zone; thus, locomotor activities important for survival of both larvae and adults occur in the same hydrodynamic environment and similar selective pressures would be expected to influence locomotor morphology of larvae and adults. The simplest framework for evaluating and interpreting development of larvae recognizes the parental form as the developmental terminus and uses adult forms as references to identify similarities and discrepancies in larva structure. Three measures of locomotor structure are used to examine changes during development: (a) the ratio of caudal peduncle d...
320 citations
TL;DR: In this article, the invariance of a solution to a partial differential equation under a generalized group of transformations is defined as a special case of invariance under a set of transformations.
TL;DR: Results of simulations indicate that the variances of the estimates are of the same order of magnitude as the CRB for sufficiently large data sets, and illustrate the performance in enhancing noisy artificial periodic signals.
Abstract: A new algorithm is presented for adaptive comb filtering and parametric spectral estimation of harmonic signals with additive white noise. The algorithm is composed of two cascaded parts. The first estimates the fundamental frequency and enhances the harmonic component in the input, and the second estimates the harmonic amplitudes and phases. Performance analysis provides new results for the asymptotic Cramer-Rao bound (CRB) on the parameters of harmonic signals with additive white noise. Results of simulations indicate that the variances of the estimates are of the same order of magnitude as the CRB for sufficiently large data sets, and illustrate the performance in enhancing noisy artificial periodic signals.
TL;DR: In this article, the authors present a systematic development of a continuum model of a porous medium and of transport processes occurring in it, and the concept of a Representative Elementary Volume (REV) as opposed to any arbitrary volume of averaging quantities at the micro-scale, is quantified.
Abstract: This is the first of two papers presenting a systematic development of a continuum model of a porous medium and of transport processes occurring in it. The concept of a Representative Elementary Volume (REV) as opposed to any arbitrary volume of averaging quantities at the micro-scale, is quantified. A universal criterion for selecting the size of an REV as a function of measurable characteristics of a porous medium and selected tolerance levels of estimation errors, is developed. The rules of spatial averaging are extended by including the effects of both the configuration of the solid matrix and of interphase transfer phenomena within an REV.
TL;DR: The proposed picture compressibility is shown to possess the properties that one would expect and require of a suitably defined concept of two-dimensional entropy for arbitrary probabilistic ensembles of infinite pictures.
Abstract: Distortion-free compressibility of individual pictures, i.e., two-dimensional arrays of data, by finite-state encoders is investigated. For every individual infinite picture I , a quantity \rho(I) is defined, called the compressibility of I , which is shown to be the asymptotically attainable lower bound on the compression ratio that can be achieved for I by any finite-state information-lossless encoder. This is demonstrated by means of a constructive coding theorem and its converse that, apart from their asymptotic significance, might also provide useful criteria for finite and practical data-compression tasks. The proposed picture compressibility is also shown to possess the properties that one would expect and require of a suitably defined concept of two-dimensional entropy for arbitrary probabilistic ensembles of infinite pictures. While the definition of \rho(I) allows the use of different machines for different pictures, the constructive coding theorem leads to a universal compression scheme that is asymptotically optimal for every picture. The results are readily extendable to data arrays of any finite dimension.
TL;DR: In this paper, necessary and sufficient conditions are given for a control sequence belonging to a polyhedral constraint set, to stabilize the system under the condition that the state is restricted to the polyhedral state constraint set.
Abstract: For linear discrete-time dynamical systems, necessary and sufficient conditions are given for a control sequence belonging to a polyhedral constraint set, to stabilize the system under the condition that the state is restricted to a polyhedral state constraint set. A variable structure linear state feedback controller, given in terms of the controls at the vertices of the polyhedral state constraint set, is presented.
TL;DR: In this paper, the authors compared the therapeutic efficacy of three exercise therapy approaches: traditional exercises and functional activities, proprioceptive neuromuscular facilitation and Bobath approach, and found that no substantial advantage could be attributed to any one of the three approaches.
Abstract: The purpose of this study was to compare the therapeutic efficacy of three exercise therapy approaches. Three groups of adult stroke patients (N = 131) participated in the study. The first group received conventional treatment that consisted of traditional exercises and functional activities. The treatment of the second group was based on proprioceptive neuromuscular facilitation techniques. The third group was treated using the Bobath approach. The improvement of each patient was evaluated after six weeks of treatment in terms of functional gains in activities of daily living as measured using the Barthel index, changes in the muscle tone of the involved limbs as measured using a five-point ordinal scale, changes in the isolated motor control of the ankle and wrist as measured by tests of muscle strength and range of motion, and changes in the patients' ambulatory status as measured using a nominal scale of four categories. The therapeutic effects of exercise according to each of the three approaches were compared using descriptive and nonparametric statistical methods. No substantial advantage could be attributed to any one of the three therapeutic approaches.
TL;DR: It is demonstrated that the dominant photocarriers generated in polythiophene with excitation above the energy gap E sub g are charged bipolarons (spin zero) from photoinduced absorption and light induced electron spin resonance.
Abstract: From photoinduced absorption and light-induced electron-spin resonance, we demonstrate that the dominant photocarriers generated in polythiophene with excitation above the energy gap (${E}_{g}$) are charged bipolarons (spin 0). The observation of bipolarons (${B}^{2\ifmmode\pm\else\textpm\fi{}}$) rather than polarons (${P}^{\ifmmode\pm\else\textpm\fi{}}$) as the dominant photoexciations demonstrates that the Coulomb contribution to the bipolaron energy (${U}_{B}$) is sufficiently small that ${P}^{\ifmmode\pm\else\textpm\fi{}}$+${P}^{\ifmmode\pm\else\textpm\fi{}}$\ensuremath{\rightarrow}${B}^{\ifmmode\pm\else\textpm\fi{}2}$. From the analysis of the spectra, we find ${U}_{B}$/${E}_{g}$\ensuremath{\simeq}0.12. .AE
TL;DR: It is found that both mechanical and osmotic compression produce the same lowering of sulphate uptake relative to uncompressed controls, and glycosaminoglycan synthesis returned to its control level when the conditions prevailing in the matrix, in the absence of pressure or added solute, were restored.
TL;DR: The main enzymatic steps in the formation of ubiquitin protein conjugates have been delineated and a broad outline of the major routes of the degradation of ubiqu itin-conjugated proteins has been described in the chapter.
Abstract: Publisher Summary This chapter discusses the mode of action and biological functions of the ubiquitin system. Ubiquitin is a small polypeptide present in apparently all eukaryotic cells. It was originally isolated in the characterization of polypeptide hormones of the calf thymus. The sequence of ubiquitin is identical in organisms as diverse as cattle, man, toad, and insects. The extraordinary conservation of ubiquitin in evolution indicates some important cellular functions. There are two processes in which ubiquitin is known to be involved—namely, histone modification and intracellular protein breakdown. In both cases, ubiquitin is linked to protein amino groups. Though the general structure of polyubiquitin genes has been conserved in evolution, there are species differences in the number of ubiquitin repeats, number of genomic loci, and nature of the aminoacid residue(s) following the carboxyl-terminus of the last ubiquitin repeat. For direct examination of the notion that ubiquitin-protein conjugates are intermediates in protein breakdown, it is necessary to demonstrate the existence of an enzyme system that preferentially degrades proteins conjugated to ubiquitin, but not unconjugated proteins. The main enzymatic steps in the formation of ubiquitin protein conjugates have been delineated and a broad outline of the major routes of the degradation of ubiquitin-conjugated proteins has been described in the chapter. Powerful tools are now available to study the biological functions of the ubiquitin system, including specific antibodies, a temperature-sensitive mutant, microinjection techniques, and cloned genes.
TL;DR: The construction of a new series of vectors which retain the pUC multiple cloning site (MCS) but in which copy number control has been recovered and the lac alpha/lac promoter expression region has been inserted into a HpaI cassette, allowing selection of recombinants by their Lac- phenotype on MacConkey agar.
TL;DR: In this article, the authors considered nonlinear programming problems with stochastic constraints and showed that the deterministic surrogate problem CE-P contains a penalty function which penalizes violation of the constraints in the mean.
Abstract: We consider nonlinear programming problem P with stochastic constraints. The Lagrangean corresponding to such problems has a stochastic part, which in this work is replaced by its certainty equivalent in the sense of expected utility theory. It is shown that the deterministic surrogate problem CE-P thus obtained, contains a penalty function which penalizes violation of the constraints in the mean. The approach is related to several known methods in stochastic programming such as: chance constraints, stochastic goal programming, reliability programming and mean-variance analysis. The dual problem of CE-P is studied for problems with stochastic righthand sides in the constraints and a comprehensive duality theory is developed by introducing a new certainty equivalent NCE concept. Motivation for the NCE and its potential role in Decision Theory are discussed, as well as mean-variance approximations.
TL;DR: This article examined three explanations of why participation in goal-setting may lead to increased performance: the social factor of group discussion, the motivational factor of involvement in goal setting, and the cognitive factor of information sharing.
Abstract: This study examined three explanations of why participation in goal setting may lead to increased performance—the social factor of group discussion, the motivational factor of involvement in goal setting, and the cognitive factor of information. A 2 X 2 X 2 experimental design (low and high levels of group discussion, involvement, and information) was used to study a sample of 96 white collar employees who worked on a personnel selection task. Results indicated that the social and motivational factors of participation increased performance quantity, incidental learning, goal acceptance, group commitment, and satisfaction. The motivational and cognitive factors significantly contributed to performance quality, but the cognitive factor did not significantly affect performance quantity and work attitudes. Extensive research on participation in goal setting and decision making (PDM) has revealed that numerous factors, both cognitive and motivational, are inherent in the process of participation but that different studies have emphasized different factors in this process. (Beehr & Love, 1983; Campbell & Gingrich, in press: Coch & French, 1948; Earley, 1985; Erez, Barley, & Hulin, 1985; Erez & Kanfer, 1983; Latham & Steele, 1983; Lewin, 1943, 1951; Locke & Schweiger, 1979). The present study distinguishes between three different factors evolving from the studies reviewed; a social factor of group discussion, leading to a decision, a motivational factor of involvement in goal setting, and a cognitive factor of information sharing.
TL;DR: The general implications of CP invariance on quark mass matrices within the standard SU(2) × U(1) gauge theory with an arbitrary number of fermion families were studied in this paper.
TL;DR: In this paper, the Skorohod generalized stochastic integral with respect to the Wiener process over some general parameter space T and it's relation to the Malliavin calculus as the adjoint of the malliavin derivative is discussed.
Abstract: The paper first reviews the Skorohod generalized stochastic integral with respect to the Wiener process over some general parameter space T and it's relation to the Malliavin calculus as the adjoint of the Malliavin derivative. Some new results are derived and it is shown that every sufficiently smooth process {ut, t∈T} can be decomposed into the sum of a Malliavin derivative of a Wiener functional, and a process whose generalized integral over T vanishes. Using the results on the generalized integral, the Bismut approach to the Malliavin calculus is generalized by allowing non adapted variations of the Wiener process yielding sufficient conditions for the existence of a density which is considerably weaker than the previously known conditions.
11 Aug 1986
TL;DR: In this article, it was shown that all languages in NP possess zero-knowledge proofs for CNF formulas without revealing any other property of the formula, without yielding neither a satisfying assignment nor weaker properties.
Abstract: Under the assumption that encryption functions exist, we show that all languages in NP possess zero-knowledge proofs. That is, it is possible to demonstrate that a CNF formula is satisfiable without revealing any other property of the formula. In particular, without yielding neither a satisfying assignment nor weaker properties such as whether there is a satisfying assignment in which x 1 = TRUE, or whether there is a satisfying assignment in which x 1 = x 3 etc.
TL;DR: The structure of minimal unsatisfiable CNF formulas in n variables containing precisely n + 1 clauses is characterised, and this characterization is given a geometric interpretation.
TL;DR: The results reveal an analogy with the tensile properties of cartilage and indicate that the collagen network is mainly responsible for controlling the "instantaneous" deformation, while the proteoglycans play an indirect role by modulating the stiffness of the collagennetwork through their osmotic pressure.
TL;DR: An algorithm for efficient recursive computation of the Fisher information matrix of Gaussian time series whose random components are stationary, and whose means and covariances are functions of a parameter vector is presented.
Abstract: The paper presents an algorithm for efficient recursive computation of the Fisher information matrix of Gaussian time series whose random components are stationary, and whose means and covariances are functions of a parameter vector. The algorithm is first developed in a general framework and then specialized to the case of autoregressive moving-average processes, with possible additive white noise. The asymptotic behavior of the algorithm is explored and a termination criterion is derived. Finally, the algorithm is used to demonstrate the behavior of the exact Cramer-Rao bound (for unbiased estimates) for some ARMA processes, as a function of the number of data points. It is shown that for processes with zeros near the unit circle and short data records, the exact Cramer-Rao bound differs dramatically from its common approximation based on asymptotic theory.
TL;DR: In this article, the effect of replacing 35 to 50 percent of cement by fly ash on workability, water requirement, bleeding, and setting time of lean concrete mixtures was investigated, using two ASTM Class F and two ASCM Class C fly ashes.