Showing papers by "Technion – Israel Institute of Technology published in 1970"
TL;DR: Composite materials macroscopic thermoelastic properties relationships to constituents properties, discussing effective thermal expansion coefficients and specific heats are discussed in this paper, where the authors also discuss the effect of specific heats.
592 citations
TL;DR: The criterion for optimality is that the normalized average of the squared norm of the difference between the T - second undistorted source sample and the corresponding T -second sample delivered to the final destination be minimum.
Abstract: This paper is concerned with the transmission of information with a fidelity criterion where the source output may be distorted prior to encoding and, furthermore, where the output of the decoder may be distorted prior to its delivery to the final destination. The criterion for optimality is that the normalized average of the squared norm of the difference between the T - second undistorted source sample and the corresponding T -second sample delivered to the final destination be minimum. The optimal structure of the encoder and decoder is derived for any T .
235 citations
TL;DR: Using immunochemical techniques, evidence is obtained that older nematodes (Turbatrix aceti) contain two populations of enzyme molecules—one active and the other totally inactive.
Abstract: Using immunochemical techniques, evidence is obtained that older nematodes (Turbatrix aceti) contain two populations of enzyme molecules—one active and the other totally inactive.
200 citations
TL;DR: In this article, a rational performance equation incorporating the residence time, the number of flocculation compartments, the stirrer characteristics and the energy requirements, such that these function in an optimum manner in the treatment of a particular water was presented.
Abstract: Designers of flocculators are required to select the residence time, the number of flocculation compartments, the stirrer characteristics and the energy requirements, such that these function in an optimum manner in the treatment of a particular water. This paper presents a rational performance equation incorporating these parameters and demonstrates its validity with measurements employing a continuously operating model flocculation apparatus. Performance is shown to be determined by both the energy dissipation rate and the type of stirring equipment, but excessive energies result in floc breakup and reduced performance. At any particular performance a minimum residence time is shown to exist corresponding to an optimum energy dissipation. Anemometric measurements demonstrate a linear relationship between the mean square fluctuating velocity and the root mean velocity gradient computed from energy measurements. Whereas different stirrers have similar turbulence spectra, they display quite different performance coefficients.
157 citations
TL;DR: In this article, the breakdown of anodic films on Al and Ta, during their formation is always associated with crystallization, and various possible mechanisms for the electrolytic breakdown are discussed.
144 citations
TL;DR: In this paper, a solution for the flow fields interior and exterior to a single spherical droplet submerged in an unbounded fluid is presented for the general case when the unperturbed velocity is Stokesian but otherwise quite arbitrary.
Abstract: A solution is presented for the flow fields interior and exterior to a single spherical droplet submerged in an unbounded fluid, for the general case when the unperturbed velocity isStokesian but otherwise quite arbitrary.
119 citations
TL;DR: In this article, the authors derived the residence time distribution (RTD) functions for screw extruders, based on the "parallel plate" and curved channel flow models, and derived the average strain distribution in the fluid across the channel.
Abstract: The residence time distribution (RTD) functions were derived for screw extruders, based on the “parallel plate” and curved channel flow models. The results indicate a relatively narrow distribution, and they explain several characteristics of screw extruders. The strain distribution in the fluid across the channel was also derived. With the aid of these two functions an average strain of the fluid leaving the extruder was defined. The resulting weighted-average total strain (WATS) provides a quantitative criterion to the “goodness of mixing” in extruders.
119 citations
TL;DR: In this article, a theoretical and experimental treatment of the strength of unidirectional fiber-reinforced composite loaded in tension in the fiber direction is presented, where the fibers are treated as having variable strength which results in fiber fractures prior to composite failure.
103 citations
TL;DR: In this paper, a solution for the flow field in and around a single spherical droplet or bubble moving axially at an arbitrary radial location, within a long circular tube, is presented.
Abstract: A solution is presented for the flow field in and around a single spherical droplet or bubble moving axially at an arbitrary radial location, within a long circular tube. In the tube there is viscous fluid flowing with a constant Poiseuillian velocity distribution far from the droplet.The settling velocity of the droplet or bubble is
\begin{eqnarray*}
U = \frac{2(\rho_i-\rho_e)ga^2}{9\mu_e}\frac{1+\alpha}{\frac{2}{3}+\alpha}\left[1-\frac{2+3\alpha}{3(1+\alpha)}\left(\frac{a}{R_0}\right)f\left(\frac{b}{R_0}\right)\right]+U_0\left[1-\left(\frac{b}{R_0}\right)^2\right.\\
\left. - \frac{2\alpha}{2+3\alpha}\left(\frac{a}{R_0}\right)^2\right] + O\left(\frac{a}{R_0}\right)^3.
\end{eqnarray*}
This is a general equation and it contains as special cases the familiar solutions of Stokes, Hadamard-Rybczynski, Brenner & Happel, Greenstein & Happel and Haberman & Sayre.The function describing the deviation of the interface from sphericity is solved and an iterative procedure is suggested for obtaining higher order solutions.
92 citations
TL;DR: In this paper, a critical minimum size of window was assessed subjectively, and it was found that this critical minimum was governed more by the visual information provided by the view outside than by the amount of daylight or sunlight which penetrates the room, by the level of interior artificial lighting or by the viewing position in the room.
Abstract: When working light is provided by permanent supplementary artificial lighting, the function of the window is modified. The main visual functions then become (a) the provision of a view, and (b) the provision of some modelling light to enhance the appearance of solid objects. This study was concerned to establish whether a critical minimum size of window could be assessed subjectively. It was found that a criterion could be recognised, and that this critical minimum size was governed more by the visual information provided by the view outside than by the amount of daylight or sunlight which penetrates the room, by the level of interior artificial lighting or by the viewing position in the room.
92 citations
TL;DR: The nematode Turbatrix aceti in axenic cultures has been shown to be suitable for aging research for the following reasons: it is possible to obtain age-synchronized populations of T. aceti and establish survival curves with 50 per cent survival of about 25 days.
TL;DR: In this paper, a finite difference solution in the laminar flow field was achieved by modifying the potential flow field to yield convective terms equivalent to the LQE terms in the energy equation.
TL;DR: In this article, the stability of simply supported conical shells under axial compression was investigated for four different sets of in-plane boundary conditions with a linear Donnell type theory, and the first two stability equations are solved by the assumed displacement, while the third is solved by a Galerkin procedure.
Abstract: : The stability of simply supported conical shells under axial compression is investigated for 4 different sets of in-plane boundary conditions with a linear Donnell type theory. The first two stability equations are solved by the assumed displacement, while the third is solved by a Galerkin procedure. The boundary conditions are satisfied with 4 unknown coefficients in the expressions for u and v. Both circumferential and axial restraints are found to be of primary importance. Buckling loads about half the 'classical' ones are obtained for all but the stiffest simple supports SS4 (v = u = o). The low buckling loads for 'classical' simple supports SS3 are confirmed by two different methods of analysis, a closed form solution in Hankel functions and a finite difference solution. Except for short shells, the effects do not depend on the length of the shell. Buckling under combined axial compression and external or internal pressure is studied and interaction curves were calculated for the 4 sets of in-plane boundary conditions. (Author)
TL;DR: In this paper, it was shown that hydration rather than electrical charge is responsible for the stabilisation of the cloud, rather than acidity, which decreases with decreasing pH, and the adsorption of oil globules on the rag particles enhances their stability in suspension, by decreasing their density.
Abstract: Orange juice is a suspension of heterogeneous particles in a clear serum. The size of the particles varies between 0·05 μm and a few hundred μm. The particles with a size below 2 μm constitute the stable ‘cloud’. This fraction consists of needle-like crystals of hesperidin, chromoplastids, amorphous (rag) particles and oil globules attached to some of these particles. The adsorption of oil globules on the rag particles enhances their stability in suspension, by decreasing their density. The hesperidin crystals are formed partly by crystallisation immediately after juice extraction. All the cloud particles exhibit a negative charge, which decreases with decreasing pH. However, it seems that hydration rather than electrical charge is responsible for the stabilisation of the cloud. Heat treatment of the juice causes an increase in the number of fine particles at the expense of coarser ones. In this process some extraction of pectin into the serum also takes place but this has little significance on the cloudiness and cloud stability of the juice.
TL;DR: Lower bounds on the average distortion produced by noise for a class of distortion functions are derived and relate the "smoothness" of modulation techniques to the minimum error that can be achieved with them.
Abstract: We consider the problem of transmission of analog data over a noisy channel. It is assumed that the channel input is of the form \surd S f(t, X) , where X is an n -dimensional source vector, and S is the allowable transmitted power. The performance of any given modulation scheme f(t, \cdot ) as a function of the transmitted power S is studied. Lower bounds on the average distortion produced by noise for a class of distortion functions are derived. These bounds relate the "smoothness" of modulation techniques to the minimum error that can be achieved with them. It is shown that when the analog source emits a sequence of mutually independent real random variables at a rate of R per second, the mean-square error that is associated with any practical modulation scheme f(t, \cdot) decays no faster than S^{-2} as the signal power S \rightarrow \infty . It follows that in the case of a band-limited additive white Gaussian channel no single modulation scheme f(t, \cdot ) can achieve the ideal rate-distortion bound on the mean-square error for all values of S , if the channel bandwidth is larger than the source rate R .
TL;DR: In this article, the authors made a study of the flow mechanisms of two immiscible liquids with a small density difference introduced at a horizontal-pipe inlet in initial concentric flow.
Abstract: A study was made of the flow mechanisms of two immiscible liquids with a small density difference introduced at a horizontal-pipe inlet in initial concentric flow. Extent of the annular flow, its break-up mechanisms and the subsequent flow patterns encountered were investigated with the aid of high-speed photography.
Annular-flow break-up was found to occur by one of two mechanisms: collapse of the core-liquid by varicose Rayleigh-type waves or rupture of the top-wall liquid-film, attenuated by the ascent of the lighter core-liquid. Flow patterns observed after break-up involve fine dispersions, slugs or stratified layers. Charts mapping flow-pattern zones show conditions under which annular-flow holds over a considerable extent.
TL;DR: Results indicate that both the secondary structure of poly U and the chemical nature of the nitrocellulose filter influence the interaction of the polymer and the membrane.
TL;DR: In this paper, the authors present a reasonably comprehensive account of the relations governing the response of soils to applied forces, including effective stress, deformation, and the influence of the strain rate on strength.
TL;DR: In this paper, the authors show that there is a good correlation between contact length and the thermal conductivity of the tool material and conclude that contact length is predominantly governed by the variation of the temperature field in the tool-chip contact zone.
TL;DR: Numerically the problem of finding the potential and electric field around a negatively charged metallic contact on the surface of an n-type semiconductor is solved and it is shown that the numerical solution agrees well with the exact analytical solution of a linearized version of the problem.
Abstract: We solve numerically the problem of finding the potential and electric field around a negatively charged metallic contact on the surface of an n-type semiconductor. The semiconductor, which has permittivity ∊ 1 , fills the half-space y 0 is vacuum with permittivity ∊ 0 . In suitable dimensionless coordinates the potential ϕ satisfies Laplace's equation in y > 0 and the equation ▽2ϕ = eϕ − 1 in y 0 0 | » 1 and η = ∊ 0 /∊ 1 > « 1. We examine in considerable detail the limiting case η = 0, first for the less practical situation where |ϕ 0 | « 1 and then for |ϕ 0 | » 1. In case the |ϕ 0 | « 1 we show that our numerical solution agrees well with the exact analytical solution of a linearized version of the problem. For |ϕ 0 | » 1, we give plots of the equipotential curves, curves of equal charge density, and curves of constant electric field amplitude. These results also yield expressions for the capacitance of both a strip and a circular electrode. The modifications of these results when η > 0 are also given in some detail. Finally, we discuss the numerical calculations at some length.
TL;DR: In this article, anodic oxide films were prepared from pure aluminium, titanium, niobium, tantatlum and tungsten, and examined by direct transmission electron microscopy.
TL;DR: In this article, it was shown that a necessary condition for causality violation is that the infinite-frequency limit of the phase velocity shall exceed the speed of light, which is the condition for all Lorentz-invariant wave equations.
Abstract: The classical analysis of Brillouin and Sommerfeld has shown that the appearance, in some frequency range, of group velocities in excess of the speed of light does not imply causality violation. The group velocity is not always identical with the velocity of signal propagation. We show that a necessary condition for causality violation is that the infinite- frequency limit of the phase velocity shall exceed the speed of light. Application of the theorem leads to the conclusions ( a ) that all Lorentz-invariant wave equations (and in particular the Feinberg ‘tachyon’) are causal, and ( b ) that the quasi-acoustic branch of the Bludman-Ruderman model is causal.
TL;DR: In this article, an experimental study of the piling-up phenomenon behind low and submerged breakwaters is presented, where the authors found that the relative height of piling up is a function of the relative depth of submergence, or of the depth of protrusion of the breakwaters.
Abstract: An experimental study of the phenomenon of piling-up behind low and submerged breakwater is presented. Piling-up occurs in completely enclosed areas or behind two-dimensional breakwaters as a result of overtopping of the breakwater. The water that spills into the protected area is accumulated there until the mean water level inside the protected area is higher than the man sea level outside. This difference in elevation, or height of piling-up, reaches eventually a value sufficient to cause a mean outflow of water through and above the breakwater equal to the mean inflow by water overtopping the structure and spilling into protected area. For a given breakwater and mean sea level, the height of piling-up was found to be an increasing function of the height of the waves in the deep sea. Expressing values relative to this wave height, the relative height of piling-up was found to be a function of the relative depth of submergence, or of the relative height of protrusion of the breakwaters. The maximum value of piling-up for the structures tested was found to be of the order of 60% of the wave height. Values of this magnitude were found for low breakwaters with crest elevations above mean sea level of between 50% and 90% of the wave height.
TL;DR: In this article, the convex polytope of all stochastic and symmetric matrices is considered and its extreme points are determined, and a method is given for counting these extreme points.
TL;DR: The effect of temperature on flow properties of all three types of material was studied in this article, where the authors found that, at the 60-65° Brix concentration level, Orange concentrate is a non-Newtonian fluid with yield stress and time dependent behaviour.
Abstract: Orange concentrate, at the 60-65° Brix concentration level, is a non-Newtonian fluid with yield stress and time dependent behaviour While recovery from low-rate shear is reversible, shear at high rate causes irreversible destruction of the viscous structure Part of this effect is due to disintegration of pulp particles Pulpless concentrate (serum) is also non-Newtonian, but yield stress and time dependent behaviour are present only when pectin concentration is high Depectinized serum is Newtonian The effect of temperature on flow properties of all three types of material was studied
TL;DR: In this paper, the minimum force required for degradation of polyisobutylene solutions to its final state is calculated in laminar flow through capillaries using a special apparatus with a view to a controlled shear history.
Abstract: Shear degradation of polyisobutylene solutions was studied in laminar flow through capillaries. A special apparatus was designed with a view to a controlled shear history. The various effects of initial molecular weight, concentration, temperature, and shear stress at the wall on the final degradation product are combined in a single parameter representing the minimum force required for degrading a polymer sample to its final state.
This work is based on the M.Sc. Thesis of A. Kadim, submitted at the Department of Chemical Engineering, Technion—Israel Institute of Technolog, Haifa, Israel.
TL;DR: The activity of the enzymes acetylcholine esterase, α-amylase, malic dehydrogenase, acid phosphatase and acid ribonuclease in cell homogenates of T. aceti were studied as a function of age to find changes in the pattern of activity.