Experimental study of different modes of block sliding along interface. Part 1. Laboratory experiments

This paper is the first part of an experimental work on studying the formation of different deformation modes of rock discontinuities under laboratory and field conditions. The formation conditions of different sliding modes were studied under laboratory conditions for several types of discontinuities, such as rigid surface contact and cracks filled with quartz sand, talc, and clay. A wide range of shear deformation modes were experimentally reproduced—from dynamic slip with a maximum velocity of tens of mm/s to stable sliding with a velocity of 1 µm/s. The behavior of a crack with a clay-containing gouge drastically changes after its wetting. The larger is the content of clay, the longer is the slip duration. The motion of a block consists of a long phase (~100 s) in which displacement velocity smoothly increases, and a retardation phase of almost the same duration in which displacement velocity decreases down to a few tens of µm/s. The used sensors detected no acoustic emission prior to the beginning of block sliding as well as on all stages of block motion until its full stop. It is shown that slow slip events have all stages typical for stick-slip motion: acceleration, long sliding, retardation, arrest, and quiescence. The conducted laboratory experiments substantiate the earlier statement that all types of deformation processes in the Earth’s crust produce a common range of phenomena.     

Experimental study of different modes of block sliding along interface. Part 3. Numerical modeling

This paper completes a series of studies on the patterns of block sliding along interface. It has been shown that in order to model the whole range of crustal block movements, the empirical rate and state friction law must be supplemented with a term that accounts for the appearance of additional shear resistance associated with the dynamic viscosity of the contact between blocks. With this term, the experimentally observed slow slip events can be modeled with good accuracy. A generalization of results of the entire series of studies published in several issues of the journal suggests that both the dynamic and quasi-static modes of sliding along faults are components of a single deformation process. The parameter that governs the formation and evolution of a fault sliding mode is the ratio between the effective values of the fault zone stiffness and rock mass stiffness. Their variation determines the occurrence of a particular sliding mode.     

渗透现象实验设计与研究

设计了一套渗透现象的定量观测实验装置用于大学基础物理实验教学.通过实验得到了渗透流量和渗透膜两侧溶液浓度差的线性关系,验证了渗透流量经验公式.此外,从物理学宏观和微观的角度给出了渗透现象的定性解释,并从基本的动力学理论出发引入了范托夫定律的理论推导.     

Experimental study of electrical properties at the Nd-doped Si-SiO2 interface

This paper presents the results of an experimental study designed to explore the electrical properties at the Nd-doped Si-SiO₂ interface. The Nd-doped silicon wafers and control silicon wafers (undoped) were annealed under different conditions of temperature, time and atmosphere. The electrical properties were measured using MOS test structures. The Nd-doped silicon wafers were analysed by electron spectroscopy (AES and ESCA). These results were compared with the Pd-, Rh-, La- and Gd-doped interfaces and briefly discussed in terms of the relevant action mechanisms of the negative electric effects.     

Experimental observation of evanescent modes at the interface to slow-light photonic crystal waveguides

We experimentally study the fields close to an interface between two photonic crystal waveguides that have different dispersion properties. After the transition from a waveguide in which the group velocity of light is v(g) ~ c/10 to a waveguide in which it is v(g) ~ c/100, we observe a gradual increase in the field intensity and the lateral spreading of the mode. We attribute this evolution to the existence of a weakly evanescent mode that exponentially decays away from the interface. We compare this to the situation where the transition between the waveguides only leads to a minor change in group velocity and show that, in that case, the evolution is absent. Furthermore, we apply novel numerical mode extraction techniques to confirm experimental results.     

无旋性前进重力波传递在均匀流中的Lagrangen解析解与试验验证Ⅱ.试验验证

针对文献[1]中的无旋性自由表面周期性规则前进重力波传递在均匀流中,本文以与前进波波向同向与反向的均匀流两种特例情况,进行试验测量,所得的波形曲线、流速分布、流体质点的运动轨迹与运动周期及其质量传输速率与Lagrange平均高程等特性,均与文献[1]中全以Lagrange方式所得的三阶解结果符合得很好.这证实本研究取定的标注流体质点的参数,正好为其在原静止水中的位置坐标值.同时亦证实波流场中由流体质点所构成的波形曲线,其波长皆同于(纯)前进波,而其传播速度为(纯)前进波波速与均匀流流速之和是具Doppler效应的;而流体质点的运动周期与其运动周期平均高程、及其质量传输速率扣掉均匀流流速等,都与(纯)前进波的相符.另外,亦揭示出流体质点的运动轨迹,在前进波波向与均匀流同向中,当流体质点在波谷断面处时沿前进波波向的流速分量为反向、零与正向时,则其形状分别为朝波向前进的扁长辐状余摆线、在波谷断面处成尖点朝下的滚轮状线与短辐形余摆线;而在前进波波向与均匀流反向中,当流体质点的质量传输速率为沿前进波波向为正向与零时,则其形状分别为朝波向前进的缩短的扁长辐形余摆线与长轴在前进波波向上椭圆形封闭曲线;而当流体质点的质量传输速率为反前进波波向,但质点在波峰断面处时沿前进波波向的流速分量分别为正向、零与反向时,则其形状分别为反波向前进的倒扁长辐形余摆线、在波峰断面处成尖点朝上的倒滚轮状线与倒短辐形余摆线.     

A study of the metal-ionic conductor interface capacitances. I. Experimental method

In the study of interface capacitances of metal-ionic conductor contacts, difficulties are often encountered to make a reference electrode. The samples used in this work have two blocking electrodes and a third one, located in the bulk of the ionic material. This arrangement is elaborated by successive depositions of gold, lead fluoride, and gold thin films. Each interface capacitance can be obtained from a frequency analysis of the three-probe system. The results show that the structure is not symmetrical, because of differences in the roughness of the electrodes.     

A model equation for the study of plasmo-hydrodynamical modes

We study a one dimensional linearized Krook equation with a Vlassov term and we formulate a perturbative scheme for calculating the frequencies of the long wavelength modes.     

Experimental study of AO and T1 modes of the concert harp

String instruments are usually composed of a set of strings, a soundboard, and a soundbox with sound holes, which is generally designed to increase the sound level by using the acoustic resonances of the cavity. In the case of the harp, the soundbox and especially the sound holes are primarily designed to allow access to the strings for their mounting. An experimental modal analysis, associated to measurements of the acoustic velocity in the holes, shows the importance of two particular modes labeled A0 and T1 as it was done for the guitar and the violin. Their mode shapes involve coupled motions of the soundboard's bending and of the oscillations of the air pistons located in the sound holes. The A0 mode is found above the frequency of the lowest acoustically significant structural mode T1. Thus, the instrument does not really take advantage of the soundbox resonance to increase its radiated sound in low frequencies. However, contribution of mode A0 is clearly visible in the response of the instrument, confirming the importance of the coupling between the soundboard and the cavity.     

Contrast variation SANS experiments to the study of detergent-induced micellization of block copolymers

PEO—PPO—PEO triblock copolymer P85 [(EO)₂₆(PO)₃₉(EO)₂₆] dissolves as unimers and detergent sodium dodecyl sulfate (SDS) forms micelles in aqueous solution at 20°C. The mixing of detergent with triblock copolymer induces the micellization of triblock copolymers. Contrast variation small-angle neutron scattering measurements show that triblock copolymer forms mixed micelles with detergent and the mixing of two components in the mixed micelles is uniform.     

Numerical study of the single fibre push-out test: Part III. Singularity of interface stresses

The singular behaviour at the free edges of the fibre-matrix interface is analysed for the fibre push-out test geometry based on the boundary element method. The fibre push-out test has been extensively used to measure the fibre-matrix interfacial properties in polymer, ceramic and metal matrix composites. There are two free edges in the fibre push-out specimen: one is at the loaded fibre end and the other at the supported fibre end. The singular stresses can be expressed as a function of singular exponent and singular stress intensity. It is shown that the singular exponents obtained at both fibre ends are characteristic of composite constituent properties, such as Young's moduli of fibre and matrix, and does not vary with specimen dimensions. The singular exponents are real and identical for the shear and radial stress components at fibre ends where the wedge angles are the same. The singular stress intensities are also implicit in material properties, and vary with specimen dimensions, such as fibre to matrix radius ratio, fibre aspect ratio and support hole size. An interfacial failure criterion is proposed here based on the average stress concept to determine the critical singular stress intensities in mode I and mode II loads.     

Comparison of experiments and computations for cold gas spraying through a mask. Part 2

This paper presents experimental and simulation results of cold spray coating deposition using the mask placed above the plane substrate at different distances. Velocities of aluminum (mean size ~ 30 μm) and copper (mean size ~ 60 μm) particles in the vicinity of the mask are determined. It was found that particle velocities have angular distribution in flow with a representative standard deviation of 1.5–2 degrees. Modeling of coating formation behind the mask with account for this distribution was developed. The results of model agree with experimental data confirming the importance of particle angular distribution for coating deposition process in the masked area.     

A one dimensional microscopical model for the study of the coherence in the stopping power problem. Part 2

A frictional quantum mechanical system consisting of a particle being scattered inelastically by a chain ofN infinitely heavy, equidistantly spaced two-level atoms is studied. In continuation of Part 1 of this work (G. Süßmann, P. Szilas, Z. Phys. B-Condensed Matter39, 125 (1980)) where the stationary problem has been considered the time dependent problem of a Gaussian wave packet impinging on the target atoms is treated. The reduced density matrix x| _R (t)|x of the particle is calculated. With this explicit expression the time derivative of the mean positiond<x>/dt is found in agreement with the stationary mean velocity of Part 1. As a measure of the incoherence of _R , i.e. the deviation of the state of the particle from a pure state, the quantityI:=1-Tr( _R ² ) is calculated for the quasi elastic case, and an estimate is given for the inelastic case.     

Unsteady three-dimensional model of electric arc. Part 2. Verification

Numerical computations of the electric arc in the external magnetic field have been done for testing the unsteady three-dimensional mathematical model. The arc of a conical and helical shape has been implemented numerically. A satisfactory agreement of the computational results with experimental data points overall to the correctness of the mathematical model and of the computational algorithm.     

Experimental and theoretical study of harmonic generation at contacting interface

The second harmonic generation behavior of a contacting interface has been evaluated experimentally and discussed theoretically in the light of a nonlinear interface model. Two aluminum blocks were mated together to constitute a contact interface and subjected to normal compressive loading. A 5 MHz longitudinal toneburst wave was sent to the interface in the normal direction and the transmitted wave was recorded, from which the fundamental and the second harmonic components were extracted. A nonlinearity parameter was obtained as the ratio of the second harmonic amplitude to the squared fundamental amplitude. From the measured contact pressure dependence of the transmitted fundamental amplitude, the linear and the second-order interfacial stiffness parameters were identified, which enabled the evaluation of the nonlinearity parameter based on the theoretical model. The theoretical contact pressure dependence of the nonlinearity parameter was found to be in good qualitative agreement with the experimental results.     

Study of the oxygen electrode reaction using mixed conducting oxide surface layers. Part I: Experimental methods and current-overvoltage experiments

The oxygen gas electrode has been studied for a number of mixed conducting oxide surface layers on top of Gd₂Zr₂O₇ (TGZO) solid electrolytes. In part II of this paper we present the results of frequency dispersion measurements for the electrode reaction, supplying additional information to the results of current-overvoltage experiments presented in part I. For both kinds of experiments the same trends were observed for the electrode polarization. Best results are obtained for a surface layer of TGZO, while p-type mixed conducting oxides give less decreased values of the electrode polarization. High electrode capacitances were found in the case of mixed conducting surface layers (about 700 F/m²). The electrode reactions follow a Butler-Volmer type of equation. Most probably a diffusion process is rate controlling the overall charge transfer process.     

Experimental and numerical study of a vibro-impact phenomenon in a gearshift cable

This paper presents a study of the nonlinear dynamic behavior of a gearshift cable and more specifically of the associated tizzing phenomenon. A gearshift cable is composed of an inner wire that can slide freely in an outer composite housing. When undergoing harmonic excitation, the inner wire interacts with the housing. Hammer and swept sine shaker tests are first used to estimate the characteristics of the two main components. It is shown that the behavior of the outer housing is nonlinear and depends on the amplitude of the excitation. The assembled gearshift cable is then set up on the shaker and the nonlinear vibro-impacting phenomenon is studied. Finally a finite element model, based on the Euler-Bernoulli beams and the Rayleigh damping coefficients, proves to offer good correlation with the measured data for different excitation frequencies. A period doubling bifurcation is observed both experimentally and numerically.     

地铁车辆司机室内藏门漏声特性试验研究

为了进一步提高内藏门的密封性能,该文试验研究了地铁司机室内藏门密封性对司机室内噪声的影响。试验研究结果表明:在隧道直线段运行条件下,司机座椅声压级满足标准要求,在曲线段因啸叫声而超出标准限值;内藏门漏声主要来源于轮轨噪声;对司机室内藏门门框增加密封结构,可使隧道直线段在运行工况下司机座椅处噪声降低0.9 dB。最后,针对司机室内藏门门页后挡上门角漏声特征,提出了进一步的降噪措施。