Showing papers by "Technion – Israel Institute of Technology published in 1983"
TL;DR: A series of known and new protocols for connectivity test, shortest path, and path updating are described and validated and extended to networks with changing topology.
Abstract: A unified approach to the formal description and validation of several distributed protocols is presented. After introducing two basic protocols, a series of known and new protocols for connectivity test, shortest path, and path updating are described and validated. All protocols are extended to networks with changing topology.
471 citations
TL;DR: In this article, it was shown that squeeze film damping cutoff frequencies can be computed directly from the lowest eigenvalue of the Helmholtz equation, and a kinematic mode was proposed and analyzed for the computation of those frequencies.
Abstract: It is shown that squeeze film damping cutoff frequencies can be computed directly from the lowest eigenvalue of the Helmholtz equation. A kinematic mode is proposed and analyzed for the computation of those frequencies and it is demonstrated that Griffin’s calculations may underestimate considerably those frequencies. New results are given for the squeeze film behavior between rectangular plates, annuli which are not necessarily thin and plate sectors.
348 citations
TL;DR: A significant association was found between the complaint of excessive daytime sleepiness and the incidence of sleep apnea, and workers with more than 10 apneas per hour of sleep complained significantly more about loud snoring, hypermotility in sleep, and frequent headaches.
Abstract: Seventy-eight workers, drawn from a population of 1502 presumably healthy working men who were interviewed about sleep habits and sleep disorders, underwent polygraphic recordings for at least 1 night. A significant association was found between the complaint of excessive daytime sleepiness and the incidence of sleep apnea. Workers with more than 10 apneas per hour of sleep complained significantly more about loud snoring, hypermotility in sleep, and frequent headaches. They had significantly more ENT findings and hypertension.
300 citations
TL;DR: In this paper, the authors analyzed properties and characteristics of pedestrian flow on sidewalks and proposed level of service definitions based on these analyses, and suggestions for their use in planning and design of pedestrian walkways are made.
Abstract: This study analyzed properties and characteristics of pedestrian flow on sidewalks. Data were collected in the central business district of Haifa, Israel, with the aid of a videotape recorder and a digital clock. Walking speeds for men were found to be significantly greater than speeds for women; all speeds were found to be inversely related to densities. One‐ and three‐regime linear speed‐density regression models were calibrated and evaluated, and reasoning is given to support the adoption of the three regime model for speed predictions. Level of service definitions are proposed based on these analyses, and suggestions for their use in planning and design of pedestrian walkways are made.
298 citations
TL;DR: In this article, a complete system of relations is determined for these generators and the presentations of M n,0 and M n,1 obtained in this way are much simpler than the known presentations.
Abstract: LetF n.k be an orientable compact surface of genusn withk boundary components. For a suitable choice of 2n + 1 simple closed curves onF n,1 the corresponding Dehn twists generate bothM n,o andM n,1. A complete system of relations is determined for these generators and the presentations ofM n,0 andM n,1 obtained in this way are much simpler than the known presentations.
206 citations
TL;DR: In this article, the authors reviewed the thermodynamic status of contact angle equilibrium and dynamic spreading of liquids on solid surfaces, and discussed the qualitative and quantitative effects of the primary film.
193 citations
TL;DR: It is shown how workers' acceptance of goals can be influenced at various stages of the progression from goal setting to goal attainment.
Abstract: Goal setting has been widely used to enhance work motivation. This paper discusses the importance of goal acceptance in moderating goal setting effects and shows how workers' acceptance of goals can be influenced at various stages of the progression from goal setting to goal attainment. A heuristic organization of goal acceptance strategies is proposed as a basis for extending the theoretical framework underlying goal setting research.
157 citations
TL;DR: A new method for the construction of submodule specifications is described which defines the specification of the additional submodule in the general case where module specifications are given in terms of sets of possible execution sequences, and interaction occurs when several modules participate in the execution of an atomic interaction.
Abstract: The problem of elaborating the specification for the submodules of a system is considered. A new method for the construction of submodule specifications is described. If the system is to consist of n submodules and the system as well as (n 1) submodules are specified, then the method described determines the specification of the additional n t h submodule. A formula is given which defines the specification of the additional submodule in the general case where module specifications are given in terms of sets of possible execution sequences, and interaction occurs when several modules participate in the execution of an atomic interaction. For the restricted context of finite-state machines, a constructive algorithm for the evaluation of the formula is given. The use of this design method is demonstrated by examples, including a simple communication protocol involving error detection and retransmission. Possible applications in other areas, as well as remaining problems, are indicated.
156 citations
TL;DR: In this article, the same regression model is fitted to several subsamples and the question arises whether the effect of some of the explanatory variables, as expressed by the linear model, is the same for all subsamples.
Abstract: The comparison of regression coefficients across subsamples is relevant to many studies. Often, the same regression model is fitted to several subsamples and the question arises whether the effect of some of the explanatory variables, as expressed by the linear model, is the same for all subsamples. Because there are sometimes misunderstandings as to the statistical procedure which ought to be applied and consequently, wrong formulae are sometimes adopted by researchers. The purpose of this article is to describe in detail the relevant statistical procedures, together with the assumptions underlying the statistical tests. Some examples are quoted, in which wrong formulae were applied. It is demonstrated how the adoption of the wrong formulae might lead to mistaken conclusions.
154 citations
TL;DR: The authors showed that the photogeneration de porteurs de charges auto-localises is unique a l'isomere trans and en IR a 1370 and a 1260 cm −1.
Abstract: La photoexcitation du polyacetylene trans mais pas du cis a pour resultat l'apparition de modes locaux fortement actifs en IR a 1370 et a 1260 cm −1 . Cette observation demontre que la photogeneration de porteurs de charges auto-localises est unique a l'isomere trans
149 citations
TL;DR: Gel-filtered platelets (GFP) from normal human subjects bound both low density lipoproteins (LDL) and high density lipohexanedione-treated LDL (CHD-LDL), suggesting that arginine residues are necessary for LDL but not HDL binding.
TL;DR: In this paper, electron diffraction patterns showing orientation of the chitin and protein constituents of the insoluble organic matrix of mollusc shell nacreous layers have been obtained, using low dose conditions and samples cooled to −100°C.
TL;DR: In this article, a model for the dynamic perforation of viscoplastic plates by rigid projectiles is presented, which is considered to occur in five continuously coupled but distinct stages.
07 Nov 1983
TL;DR: It is shown that if p, the number of participants in the protocol, is part of the input then the security problem becomes NP-Hard and Relaxing the definition of a ping-pong protocol so that operators can operate on half words causes theSecurity problem to become undecidable.
Abstract: We define a p-party ping-pong protocol and its security problem, along the lines of Dolev and Yao's definition for twoparty ping-pong protocol. In the case of two parties, it was assumed, with no loss of generality, that there exists a single saboteur in the net and the protocol was defined to be secure iff it was secure against the active interventions of one saboteur. We show that for more than 2 parties this assumption can no longer be made and that for p parties 3(p-2) + 1 is a lower bound on the number of saboteurs which should be considered for the security problem. On the other hand we establish a 3(p-2) + 2 upper bound on the number of saboteurs which should be considered. We conclude that for a fixed p, p-party ping-pong protocols can be tested for security in 0(n3) time and 0(n2) space, when n is the length of the protocol. We show that if p, the number of participants in the protocol, is part of the input then the security problem becomes NP-Hard. Relaxing the definition of a ping-pong protocol so that operators can operate on half words (thus introducing commutativity of the operators) causes the security problem to become undecidable.
TL;DR: In this article, the behavior of a ferrite-elastomer composite is studied under the combined influence of changing elastic stresses and magnetic fields, and the results obtained are presented in a series of graphs.
TL;DR: Dialkyldimethylammonium hydroxide surfactants are highly soluble in water and form spontaneous stable vesicles, and appear to provide an ideal membrane mimetic system for the study of fusion and ion transport.
Abstract: Dialkyldimethylammonium hydroxide surfactants are highly soluble in water and form spontaneous stable vesicles. These vesicles can be grown to size with added acid, and appear to provide an ideal membrane mimetic system for the study of fusion and ion transport. These phenomena are a consequence of strong hydration forces that are not necessarily limited to the hydroxide ions. The forces can be used to design a variety of model systems whose behavior differs from that of systems in which double-chained surfactants form insoluble liquid crystalline phases in water and unstable vesicle suspensions on prolonged sonication.
TL;DR: In this article, the problem of linear system decoupling is examined based on recent results on linear feedback, through which resolution of the decoupliug problem is accomplished by calculations, performed directly on the given transfer matrix.
Abstract: The problem of linear system decoupling is examined based on recent results on linear feedback. New insight is obtained, through which resolution of the decoupliug problem is accomplished by calculations, performed directly on the given transfer matrix. Computation of the decoupling compensators follows by easy constructions. The problem of feedback block decoupling with internal stability, is also formulated and resolved.
TL;DR: It was concluded that the limiting factor for the growth of carp in properly processed commercial soybean meals was not the residual antitrypsin, but inadequate lysine.
TL;DR: If Q is an inftmte field (e.g, the rauonal numbers or the complex numbers), then the equwalence problem for ~ is probabilistlcally decidable in polynomml time and the equivalence problem is NP-hard.
Abstract: Let Q be any algebraic structure and ~the set of all total programs over Q using the instruction set {z ,,-1, z , , x + y, z ,,-x y , z ~ x * y , z ~-x / y } . (A program is total if no division by zero occurs during any computation ) Let the equivalence problem for ~ be the problem of deciding for two given programs in ~whether or not they compute the same funcuon The following results are proved: (1) If Q is an inftmte field (e.g, the rauonal numbers or the complex numbers), then the equwalence problem for ~ is probabilistlcally decidable in polynomml time. The result also holds for programs with no dwlslon instructions and Q an infimte integral domain (e.g., the integers). (2) If Q is a finite field, or if Q is a fimte set of integers of cardmahty _>2, then the equivalence problem is NP-hard. The case when the field Q is finite but its cardinality is a funcuon of the size of the instance to the eqmvalence problem is also considered An example is shown for which a sharp boundary between the classes NP-hard and probabihsticaUy decidable exists (provided they are not identical classes).
TL;DR: This work considers several classes of interfering queues that appear in packet-radio networks and calculates the average packet waiting time and queue lengths, and develops a method to approximate these quantities.
Abstract: We consider several classes of interfering queues that appear in packet-radio networks. We analyze the class of systems where one of the queues is given full priority and obtain an expression for the joint probability distribution of the queue lengths. For ALOHA-type systems with two symmetric queues we calculate the average packet waiting time and queue lengths, and for symmetric systems with an arbitrary number of subscribers we develop a method to approximate these quantities. The approximation turns out to be close to the analysis and simulation results.
TL;DR: The gene for the P700 chlorophylla apoprotein has been physically mapped on the spinach plastid chromosome by hybrid selection mapping and DNA-programmed cell-free transcription-translation using cloned restriction fragments of plastids DNA.
Abstract: A photosystem I reaction center complex has been purified to homogeneity by a procedure involving partial solubilization of spinach thylakoid membranes, ion exchange chromatography and centrifugation in sucrose gradients. The complex contains 7 polypeptides: the P700 chlorophylla apoprotein with an apparent molecular weight of 67 kd, which at high resolution splits into two bands, and smaller polypeptides of 22 (subunit 2), 18.5, 18, 16, 12 and 10 kd. Stable transcripts for the P700 chlorophylla apojprotein and subunit 2 were found in plastid and cytosolic RNA, respectively. The apoprotein product obtained by translation in a mRNA-dependent cell-free rabbit reticulocyte lysate and also by DNA-programmed transcription-translation of cloned plastid DNA fragments inE. coli lysates was indistinguishable immunologically and electrophoretically from the authentic protein. However, the product immunologically related to subunit 2 was 4 kd larger than the mature compound indicating that this protein is encoded in the nucleus and synthesized as a precursor. The gene for the P700 chlorophylla apoprotein has been physically mapped on the spinach plastid chromosome by hybrid selection mapping and DNA-programmed cell-free transcription-translation using cloned restriction fragments of plastid DNA. There is one gene copy per chromosome and it is located centrally in the large single-copy region of the circular DNA molecule. This gene is uninterrupted and is transcribed in the same direction as that of the large subunit of ribulose bisphosphate carboxylase/oxygenase. Its transcript is approximately 4 kb longer than the 2 kbp structural gene.
TL;DR: The Rieske iron‐sulfur protein and the cytochrome f apoprotein appear to be made as precursors with excess sequences of 7 and 4 kd, respectively.
Abstract: Cytochrome b6/f complex was prepared from washed thylakoid membranes by a procedure involving detergent treatment and centrifugation in sucrose gradients The complex is composed of at least four polypeptide species, cytochrome f which occurs in two variant forms (mol wt 34/33 kd), cytochrome b6 (23 kd), the high-potential Rieske iron-sulfur protein (19 kd) and a fourth subunit (17 kd) of unknown function Transcripts for the cytochromes f, b6 and subunit 4 were found in plastid RNA, those for the Rieske iron-sulfur protein in cytosolic poly(A)+ RNA Transcripts for cytochrome b6 and subunit 4 are translated in rabbit reticulocyte lysates into products of correct length The Rieske iron-sulfur protein and the cytochrome f apoprotein appear to be made as precursors with excess sequences of 7 and 4 kd, respectively Cytochrome f, cytochrome b6 and subunit 4 are encoded by uninterrupted plastid genes that are located in the large single-copy region of the circular DNA molecule Each of these genes is present once per chromosome Their location and direction of transcription have been determined by hybrid-selection mapping and by cell-free transcription/translation of various recombinant DNAs The genes for cytochrome b6 and for subunit 4 lie near each other, but do not overlap They are transcribed into a single message The gene for cytochrome f maps 15 kbp away from this cluster, close to the 3' end of the gene for the large subunit of ribulosebisphosphate carboxylase/oxygenase, and is transcribed into a separate 4 kb long RNA All these genes have the same polarities with respect to each other
TL;DR: In this article, an overview of nonlinear elastic shell theory is provided, where the authors discuss definitions of a two-dimensional stress resultant, stress couple, displacement, spin (angular velocity), entropy resultant, temperature mean, temperature drop, and other fields.
Abstract: Publisher Summary This chapter provides an overview of nonlinear elastic shell theory The chapter starts with the integral equations of motion and thermodynamics of a three-dimensional body taken over its reference shape Specializing to shell-like bodies, chapter discusses definitions of a two-dimensional stress resultant, stress couple, displacement, spin (angular velocity), entropy resultant, temperature mean, temperature drop, and other fields These definitions provide a concrete, unambiguous tie between two- and three-dimensional continuum mechanics The two-dimensional integral equations, for sufficiently smooth fields, imply differential equations Those of conservation of linear and rotational momentum yield in a natural way a mechanical work identity that provides, automatically, two-dimensional strains conjugate to the stress resultants and couples This leads to a mechanical theory of shells in which a strain energy density, depending on these strains only, is assumed to exist In the chapter, a thermodynamic theory is formulated from a postulated first law in which the internal energy is a function of the aforementioned two-dimensional strains, plus an entropy resultant and couple Invariance requirements and dimensional analysis are used to simplify the form of the strain energy density (or the free-energy density in the thermodynamic theory)
TL;DR: In this paper, the motion of the wave front is characterized in terms of α, β and γ, and the effect of fast absorption (b 0, 0 < γ < 1) that causes extinction within a finite time, may break the evolving pulse into several sub-pulses and causes the expanding front to reverse its direction.
TL;DR: In this paper, the results obtained from electron microscopy of air-dried and frozen hydrated specimens of stained dispersions of liquid crystals and vesicles of synthetic and natural amphiphiles indicate that rearrangement upon drying causes gross changes in the original microstructure of the examined systems.
TL;DR: It is shown that the dispersion of parameters in the multi-efferent channels converging on a common tendon provides a spatial filtration generating a smoother muscle force in addition to extending the linear dynamic range compared to a similar system having identical motor units.
Abstract: The effects of parameter dispersion among motor units on the neuromuscular system performance as well as interaction between muscle segments and spinal cord mechanisms are investigated. Elementary components of the system are modeled to simulate with simple models their input-output characteristics. A leaky SS-IPFM encoder with a time-dependent threshold simulates the motor-neuron encoding characteristics. An amplitude and time dependent non-linear model represent the motor unit mechanical output to neuronal input relationship. The dispersion of parameters in the components of the whole muscle control model is investigated in the open loop mode. It is shown that the dispersion of parameters in the multi-efferent channels converging on a common tendon provides a spatial filtration generating a smoother muscle force in addition to extending the linear dynamic range compared to a similar system having identical motor units. Muscle segmental interaction is investigated in this distributed model by closing the loop through a coupling matrix, representing afferent-motorneuron interaction on the spinal cord level. A diagonal matrix represents no segmental interaction and a uniform matrix represents a uniform interaction between segments through the muscle spindles and Golgi tendon feedback elements. The close loop simulation studied shows that (a). The type of segmental interaction has little effect on the overall system performance, i.e., range of linerity and stability, which is the result of having a muscle system with a large number of motor units. (b) There are only minor differences in results between the uniform and normal parameter distributions tested. (c) A loop gain of 4÷8 in the distributed model can provide linearity through the full physiological force range. (d) Type of segmental interaction has significant effects on the individual segment. A uniform matrix provides a more stable segment due to the spatial filtration resulting from the segmental interaction, while the diagonal noninteracting matrix shows instabilities on the local segmental level despite global stability. The more realistic exponentially decaying spatial interaction matrix yields both global neuromuscular and local segmental stability with the same linear dynamic range generated with the uniform or diagonal matrices.
TL;DR: In this paper, the adiabatic shear bands formed by 7.62 mm armour-piercing bullets were examined using optical and transmission electron microscopy, and the rapid cooling of highly deformed shear band was of the order of 10 7 °C s −1.