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Notes: We analyse the problem of radiation of seismic waves by a vibroseis source when the baseplate is subject to flexure. A theoretical model is proposed to account for baseplate flexure, generalizing the well-known model of the vibroseis source of Sallas and Weber, which was developed for a rigid plate. Using the model proposed, we analyse the effect of flexure on the properties of seismic waves. We show that the flexure does not contribute to the far-field and mainly affects the readings of the reference accelerometer that is used to measure the force applied to the ground; these readings generally become dependent on the location of the sensor on the plate. For muddy and sandy soils, the effect of flexure on baseplate-acceleration measurements is nonetheless pronounced at the high end of the vibroseis frequency band only (∼100 Hz), and is negligible at all frequencies for stiffer soils. The corresponding phase lags introduced by the flexural vibrations at high frequencies lead to errors in the traveltime measurements (through the cross-correlation function) of up to 0.6 ms for muddy soils and less for denser soils. We show the existence of an optimal position of the reference sensor on the baseplate and also propose a general method of eliminating the phase lag due to the baseplate flexure in acceleration measurements.

Notes: Abstract The paper presents the results on differential cross sections for elastic scattering of 7+-, K+-mesons and protons on protons in the 4-momentum transfer squared range 0·08 ≦¦t¦≦ ≦1·0 (GeV/c)2 and incident particle momentum of 29 and 43 GeV/c for pions and kaons and 29, 43, 50 and 65 GeV/c for protons. The measurements were taken with the spectrometer Sigma, installed in the positive beam of the IHEP accelerator.

Notes: Summary Electrophysiological micropuncture techniques were used to study the effect of certain diuretics on transtubular transport of electrolytes in the rat kidney. The mercurial diuretic novurite caused a reduction of active sodium transport in the proximal tubule, measured by short-circuit current and increased permeability of the tubular wall to ions which led to a considerable drop in transtubular potential and transepithelial resistance. Ethacrynic acid decreased the shortcircuit current in the proximal tubule, without changing the permeability characteristics of the nephron. Xanthine diuretic euphylline did not reduced the short-circuit current in the proximal segment of the nephron; however, it increased the transepithelial potential of the renal tubule. In the distal tubule, euphylline and ethacrynic acid increased the difference in transtubular potential, whereas novurite distal tubule as a result of euphylline and ethacrynic acid action may be responsible for increasing potassium excretion. A decrease of the transtubular potential in the distal tubule under the action of novurite may serve to explain a lack of significant potassium excretion under mercurial diuretic action. The reduction of tubular reabsorption as a result of diuretic action is due to drug effect on different levels of the transtubular-ion transport system.

Notes: Abstract The appearance of a pronounced velocity-field nonuniformity beyond the granular bed has been established experimentally for the case in which a stream compresses the bed. This effect is absent in the opposite case, when the bed is made friable by a stream.

Notes: Abstract An equation for concentration pulsations is derived, and an approximation is given for the unknown correlations in the equation. An approximation is proposed for the probability distribution of the passive-impurity concentration, taking account of intermittency and allowing the effect of pulsations on the jet-flow parameters to be taken into account. Using the semiempirical (e−ɛ) model of turbulence and equations for concentration pulsations in the boundary-layer approximation, the characteristics of isothermal submerged axisymmetric jets and of axisymmetric submerged diffusion flames of propane and hydrogen in air are calculated. It is established that with increase in Froude number the intensity of the concentration pulsations decreases both for isothermal jets and for diffusion flames. The concentration pulsations have a significant effect on the characteristics of the turbulent diffusion flame in its initial region. In the absence of buoyancy forces, concentration fluctuations have little effect on the characteristics in the main region of the flame. A burning jet has a longer range than a jet that is not burning. Combustion has little effect on the intensity of velocity and concentration pulsations. The approaches that are widely used at present for the theoretical investigation of the turbulent mixing of jet-type flows use, as closure relations, a two-parameter model of turbulence consisting of semiempirical differential equations [1, 2]. As a rule, one of the equations in the turbulence model is an equation for the turbulent energy, $$e \equiv {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}\left\langle {u_\alpha ^\prime u_\alpha ^\prime } \right\rangle $$ (u′α is the pulsational component of the velocity; α = 1, 2, 3; 〈 〉 are the averaging brackets), and the other is either an equation for the integral scale L of the turbulence [3], or an equation for different combinations of these parameters—the turbulent viscosity $$\varepsilon \sim \sqrt {eL} $$ [4], the the dissipation rate ɛ ∼ e2/ɛ [5], etc. The need to use such an approach is associated primarily with the possibility of calculating mean parameters and turbulence characteristics of complex non-self-similar flows depending on the previous development of the flow. In addition, by this means of closure it is possible, using a semiempirical equation for the concentration pulsations σ $$\sigma \equiv \sqrt {\left\langle {\left( {c - \left\langle c \right\rangle } \right)^2 } \right\rangle } $$ [6, 7] (c is the mass concentration) to calculate the meansquare value of the concentration pulsations and also to determine the intermittency coefficient γ and the distribution function of the probability density P(c). A knowledge of these values is particularly important in investigating turbulent mixing in the presence of diffusion combustion. It is known [8] that pulsations of the gasdynamic parameters must be taken into account in describing turbulent combustion, since the calculation of diffusion-combustion characteristics in the “quasilaminar” formulation does not allow a number of qualitative features of the process to be taken into account. Despite the many works on turbulent-flow calculations now available, there has been little investigation of a whole series of aspects of this type of flow. For example, there has not been sufficient study of the effect of the buoyancy forces arising because of the density difference between jets of different gases on the level of the concentration pulsations. Very little data is available on the effect of combustion on the turbulent flow characteristics. The present work takes up these questions. A semiempirical equation is proposed for the concentration pulsations. This equation, which is related to the (e−ɛ) model of turbulence developed in [4], is tested in calculations of isothermal jets and also diffusional combustion flames. Particular attention is paid to the behavior of the concentration pulsations.

Notes: Abstract An investigation of the flow at a rough surface, as well as in pipes and channels with rough walls, is one of the most important problems of applied hydrodynamics. Results of classical investigations, in which the most important flow properties near a rough surface are clarified, are generalized in [1–3]. These investigations are the basis for the construction of numerous semiempirical theories using the “mixing path∝ model of L. Prandtl (for instance, [4–6]). However, despite their simplicity these methods possess all the disadvantages inherent in the Prandtl theory: They are not universal, they describe the transition from the laminar to the turbulent mode poorly, and they are not applicable for the computation of complex non-self-similar flows. Meanwhile, an analysis of the experimental results obtained in [7], for example, indicates an extremely complex flow structure both in the neighborhood of the rough surface and far away from it. Models using the differential equation of the kinetic energy of turbulence have recently been developed to describe turbulent flow near a rough surface [8]. The possibilities of applying a model using the equation for turbulent viscosity to close the problem [9] are analyzed in this paper in an example of a steady turbulent incompressible fluid flow in a circular pipe with rough walls.