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181.
Equations are obtained for the motion of a water-soil mixture in the layer next to the base. The water-soil mixture is modeled by means of a viscous-friable medium, and the acceleration of the mixture is assumed to be small and is not taken into account. The validity of the equations is confirmed by the experimental data for the following characteristics of uniform motion of a flow: for the speed of the start of particles touching on an even bed and with allowance for inclines of a bed, and also for the flow rate of loads on an even bed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 182–185.The author is grateful to A. G. Kulikovskii, V. Ya. Shkadov, and M. É. Églit for discussing the results of the study.  相似文献   
182.
übersicht Mittels eines auf der Randintegralgleichungsmethode basierenden numerischen Berechnungsverfahrens werden zun?chst die Kerbfaktoren tordierter Wellen mit kreisf?rmig ausgerundeter Einzelkerbe bestimmt und mit bekannten Ergebnissen verglichen. Dabei wird eine von Neuber [1] angegebene Interpolations-formel gut best?tigt, die in Abh?ngigkeit von Kerbtiefe und Kerbsch?rfe eine bequeme Bestimmung der Kerbfaktoren erlaubt. Anschlie?end wird die gegenseitige Beeinflussung von zwei in beliebigem Abstand zueinander angeordneten kongruenten Kerben untersucht. Entsprechende Kerbfaktordiagramme werden angegeben und analytische Interpolationsformeln für die genauere Bestimmung von Zwischenwerten aufgestellt. Ein Vergleich mit den in der Literatur bekannten Ergebnissen von Mehrfachkerben wird vorgenommen.
Summary Stress concentration factors arising in the torsion of shafts with a circumferential notch are determined by means of a computer program, based on a boundary integral equation method, and are compared with known results. The results agree well with stress concentration factors obtained from a semiempirical interpolation formula of Neuber [1], which allows a comfortable determination of the concentration factors depending on the base radius and the depth of the grooves. In the second part the reciprocal influence of two congruent circumferential notches, located at an arbitrary distance from each other, is investigated. Corresponding stress concentration factor graphs are given and an analytical interpolation formula is drawn up. A comparison is undertaken with known results for shafts with an infinite system of small grooves.
  相似文献   
183.
Summary In many electro-chemical experiments it is desirable that one of the current-carrying electrodes of an electrolytic bath has a constant potential. This may be realized by manual control of the bath current. Owing to the sudden and unpredictable potential fluctuations of the electrode concerned, this is very difficult and even impossible in some special cases, e.g. when passivating an Fe-electrode in aqueous H2SO4. In addition there may be a considerable time-lag between the potential and the current fluctuations. The different types of potentiostats described so far seem to have too large a time-lag or/and too low a sensitivity for this purpose. The authors describe a potentiostat with proportional and integrating properties resulting in a stabilization of the potential within 1/2 mV in favourable sections of the potential current characteristic. Even with an electrode with a very steep potential current characteristic (e.g. the above mentioned Fe-electrode) the ripple never exceeds a few mV. The bath current, the maximum value of which is 30 mA, is the differential current of two electronic tubes. This type of circuit offers various advantages.  相似文献   
184.
Analysis methodology for 3C-PIV data of rotary wing vortices   总被引:1,自引:0,他引:1  
3C-PIV data from tip vortices of either fixed-wing or rotating wing experiments are challenging from an analysis point of view. Model motion, vortex wander, spurious vectors, periodic and aperiodic effects, turbulence, and other disturbing effects are all present in the data. In most cases the vortices are not measured perpendicular to their axis as well. Engineers need time-averaged properties from the vortex in the vortex axis system for a proper modelization within simulation codes. This article describes the methods needed to deal with all the mentioned problem areas, including the conditional averaging and rotation into the vortex axis system. The methods are validated by using numerically generated vortex vector fields, and finally applied to experimental data from a hover condition of a model rotor.  相似文献   
185.
Considered in Part I was the debonding instability of a three-layered composite system made of steel, adhesive and rubber which models the situation in a solid-fuel rocket motor. Under the condition of a uniform stress rate of 0.75 ksi/s applied to the longitudinal and transverse direction, severe inhomogeneity of the material response were found in regions next to the adhesive/rubber interface. This led to the prediction of a macrocrack about 5 × 10−3 in. after an elapsed time of one second and sudden fracture over a length of 1.88 in. at eight seconds after loading.This is Part II of the work that examines the influence of load transients on interface failure. As unequal stress rate state is assumed where loading in the transverse direction is removed causing a more severe disturbance in the longitudinal direction even though the same stress rate of 0.75 ksi/s is maintained. A slightly bent crack of the order of 10−3 in. is predicted to initiate near the adhesive/rubber interface; it led to the onset of fracture over a length of 1.60 in. at four seconds. Onset of instability is predicted to occur at a much earlier state.  相似文献   
186.
A method of deriving the equations that describe long nonlinear waves in channels of arbitrary cross section, taking the transverse acceleration of fluid particles into account (the Boussinesq approximation), is proposed. For channels of certain cross sections the equations are written in explicit form. In the case of narrow channels the Boussinesq equations and those of the next approximation are written in explicit form for arbitrary cross sections.  相似文献   
187.
We study the structure of the set of solutions (continuous and bounded for t R +) of one class of systems of nonlinear functional difference equations with a nonlinear deviation of the argument that depends on unknown functions.  相似文献   
188.
Lagrange's equations are used to examine the long-range interaction of bubbles. The Lagrange function equals the kinetic energy of an ideal liquid flowing around a bubble. The generalized external forces include the upthrust and the viscous resistance to flow around each buble. The azimuthal angle is increased by the long-range interaction. The locus for the relative motion is calculated for: 1) the case in ~hieh the relative speed is fairly high, which allows one to neglect the effects of viscosity on the collision time. 2) low relative speed, where the viscous forces determine the motion. Estimates are given for the differential effective cross-section for elastic scattering and the coalescence cross-section.We are indebted to V. G. LevichandV. V. Tolmachev for discussions.  相似文献   
189.
Summary This paper is devoted to a study of the flow of a second-order fluid (flowing with a small mass rate of symmetrical radial outflow m, taken negative for a net radial inflow) over a finite rotating disc enclosed within a coaxial cylinderical casing. The effects of the second-order terms are observed to depend upon two dimensionless parameters 1 and 2. Maximum values 1 and 2 of the dimensionless radial distances at which there is no recirculation, for the cases of net radial outflow (m>0) and net radial inflow (m<0) respectively, decrease with an increase in the second-order effects [represented by T(=1+2)]. The velocities at 1 and 2 as well as at some other fixed radii have been calculated for different T and the associated phenomena of no-recirculation/recirculation discussed. The change in flow phenomena due to a reversal of the direction of net radial flow has also been studied. The moment on the rotating disc increases with T.Nomenclature , , z coordinates in a cylindrical polar system - z 0 distance between rotor and stator (gap length) - =/z 0, dimensionless radial distance - =z/z 0, dimensionless axial distance - s = s/z0, dimensionless disc radius - V =(u, v, w), velocity vector - dimensionless velocity components - uniform angular velocity of the rotor - , p fluid density and pressure - P =p/(2 z 02 2 , dimensionless pressure - 1, 2, 3 kinematic coefficients of Newtonian viscosity, elastico-viscosity and cross-viscosity respectively - 1, 2 2/z 0 2 , resp. 3/z 0 2 , dimensionless parameters representing the ratio of second-order and inertial effects - m = , mass rate of symmetrical radial outflow - l a number associated with induced circulatory flow - Rm =m/(z 01), Reynolds number of radial outflow - R l =l/(z 01), Reynolds number of induced circulatory flow - Rz =z 0 2 /1, Reynolds number based on the gap - 1, 2 maximum radii at which there is no recirculation for the cases Rm>0 and Rm<0 respectively - 1(T), 2(T) 1 and 2 for different T - U 1(T) (+) = dimensionless radial velocity, Rm>0 - V 1(T) (+) = , dimensionless transverse velocity, Rm>0 - U 2(T) (–) = , dimensionless radial velocity, Rm=–Rn<0, m=–n - V 2(T) (–) = , dimensionless transverse velocity, Rm<0 - C m moment coefficient  相似文献   
190.
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