矮塔斜拉桥地震损伤试验研究

为研究矮塔斜拉桥的纵桥向地震损伤发展过程,以一座典型的塔梁墩固结体系三塔矮塔斜拉桥为原型桥梁,设计、制作了缩尺比为1∶20的全桥振动台试验模型,并采用El Centro波和场地人工波作为地震动输入对试验模型进行纵桥向振动台试验,观测各试验工况下的试验模型地震损伤情况.结果表明,塔梁墩固结体系矮塔斜拉桥的地震损伤主要出现...     

Experimental studies of heating rheologically complex fluids with electromagnetic field

Heating of rheologically complex fluids in electromagnetic field in a coaxial system is studied. The experimental results show that the dynamics of changes in temperature of the fluid are affected by the electromagnetic field.     

Experimental and numerical studies on corrosion failure of a three-limb pipe in natural gas field

A bursting incident occurred in a three-limb pipe, having 16Mn steel for the main pipe and 316L + L416 composite metal for the branch pipe, in a natural gas field. The failure analysis was performed by means of inspection, experiments and computational fluid dynamics (CFD) simulation. The CFD results indicated the radical change in the flow characteristics inside the three-limb pipe due to its upright structure and the formation of a low vortex in the downstream near the junction, which indicated the condensation of water vapor containing high salinity. The condensed brine saturated with CO₂ adhered to the inner wall surface of the main pipe. In such a corrosive medium, 16Mn steel acts as an anode and is preferentially corroded due to galvanic corrosion. In addition, the downstream area, covered by low vortex, exhibited high shear stress and droplet impingement stress, resulting in an increase in flow erosion. Thus, the failure of the three-limb pipe can be attributed to the synergistic effect of galvanic corrosion and flow erosion.     

Drag on a sphere accelerating rectilinearly in an elastico-viscous fluid

The exact solution for the drag on a sphere moving in an arbitrary manner along a rectilinear path in an otherwise-still elastico-viscous fluid of infinite extent is presented. The Fourier transform technique is used to derive the solution. This technique is based on the fact that drag on an accelerating body can be obtained by integrating the drag on an oscillating body over all possible frequencies. The solution is also expressed in terms of infinite series which is suitable for numerical evaluation of the drag. The solution for the drag on a sphere suddenly brought to uniform motion is presented as an example of this study.     

Benchmarking of activation reaction distribution in an intermediate energy neutron field

Neutron-induced reaction rate depth profiles inside concrete shield irradiated by intermediate energy neutron were calculated using a Monte-Carlo code and compared with an experiment. An irradiation field of intermediate neutron produced in the forward direction from a thick (stopping length) target bombarded by 400 MeV nucleon(-1) carbon ions was arranged at the heavy ion medical accelerator in Chiba. Ordinary concrete shield of 90 cm thickness was installed 50 cm downstream the iron target. Activation detectors of aluminum, gold and gold covered with cadmium were inserted at various depths. Irradiated samples were extracted after exposure and gamma-ray spectrometry was performed for each sample. Comparison of experimental and calculated shows good agreement for both low- and high-energy neutron-induced reaction except for (27)Al(n,X)(24)Na reaction at the surface.     

Experimental studies on an optical multimode multichannel hybrid junction branch

Translated from Izmeritel'naya Tekhnika, No. 10, p. 31, October, 1991.     

Experimental realization of an imaging system with an extended depth of field

We describe the experimental realization of an all-optical imaging system with an extended depth of field (DOF). The core of the system is a phase mask consisting of 16 Fresnel lenses (FLs) that are spatially multiplexed and mutually exclusive. Because each FL, in tandem with the primary lens, is designed to produce a sharp image for a specific object plane location, jointly the FLs achieve a wide DOF. However, the resultant image exhibits reduced resolution. The acquired image, onto which we did not apply any postprocessing, clearly is sharper than that acquired with a clear-aperture imaging system with the same pupil size.     

Longitudinal chromatic aberration of an accelerating gap

An expression for the longitudinal chromatic aberration of an accelerating gap with an arbitrary distribution of the electrostatic field along the electron trajectory is presented, and a method is proposed for reducing it in time-transforming chronographs to values of order 10 fs. Pis’ma Zh. Tekh. Fiz. 25, 17–20 (April 26, 1999)     

Experimental investigation of the temperature distribution in thin films heated by an electron beam

The temperature distribution in thin carbon films irradiated in an electron microscope has been measured. The experimental curve is in good agreement with the result calculated by assuming that heat is removed from the object mainly by conduction.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol.21, No.6, pp. 1084–1090, December, 1971.     

A study on the field distribution of thin-film heads

The field distribution of a thin-film inductive head and its relationship to pole configurations are examined. Three components of the field distribution at high frequencies are measured using a newly developed electron beam tomography method. Focused ion beam etching is used for the processing of the pole configuration. A comparison between the measured field distribution and the results of three-dimensional computer simulation shows that a sharp field distribution suitable for high-density recording is produced to promote magnetization at the tip region. Furthermore, the optimum design of the pole configuration clarifies the feasibility of 1-μm track recording     

Specifics of the microwave-breakdown mode in an accelerating structure with parallel coupling

The results of examination of the microwave-breakdown mode in an accelerating structure with parallel coupling are reported. It is demonstrated that breakdown normally occurs in a single cavity of the structure, while other cavities and the structure in general remain unaffected. This is attributed to the fact that neighboring accelerating cavities are almost independent of each other. This feature makes the structure more resistant to breakdown failure and may be used to increase the amplitude of the accelerating field in accelerators with a large number of accelerating structures.     

Hydrodynamic pressure on an accelerating dam and criteria for cavitation

Summary The effect of finite reservoir on the hydrodynamic pressure due to horizontal as well as vertical ground excitations has been studied. It is found that for horizontal accelerations the hydrodynamic pressure force decreases as the size of the reservoir decreases. The effect of vertical acceleration on the pressure force on a dam is simply to adjust the hydrostatic pressure by replacing the gravitational constant by an effective gravitational acceleration and this is true for any arbitrary shapes of the reservoir. A simple criterion has been presented in this paper which would enable dam engineers to determine whether a given earthquake could cause cavitation at the dam-water interface or not.     

Qualitative motion of a liquid in an accelerating gas stream

Experimental data are examined on the interaction of liquid drops with the gas stream in a Venturi scrubber, the most promising available equipment.     

胶囊机器人在黏液中旋进运动的研究

研究表面螺旋胶囊机器人在外部旋转磁场作用下在黏液中的运动特性。首先介绍外磁推进的胶囊机器人的系统构成,给出表面螺旋胶囊在黏液中旋进的磁主动矩的表达式,然后制作了镶有条形强磁片的胶囊机器人样品,搭建了旋转磁场试验台,配置了不同动力黏度的二甲基硅油以模拟人体体液。试验模拟旋转磁场对胶囊机器人在不同黏性液体中的旋转,证明了设计的合理性和可行性。当外部磁场强度在6.281 A/m左右时,胶囊机器人受到的驱动力矩为1.0 mN·m左右。在胶囊机器人的设计中,决定需要的外部磁场强度以及所受到的阻力矩大小的因素依次为胶囊直径、设计的工作转速和黏液的黏度。     

Experimental study of the pressure field of an electric explosion of plane ring foil

Results of an experimental study of the pressure field of a shock acoustic wave in a closed chamber with condensed matter are presented; this wave results from the electric explosion of a plane ring foil, on which discharge current passes in the radial direction. The presence of a pronounced pressure maximum with regard to the electrode-system axis can be interpreted as the effect of nonlinear interaction of elements of the shock acoustic waves excited on diametrically opposite sides of the exploding ring foil.     

Experimental studies on ice shells in Asahikawa

An ice shell is thin, and its structural material is snow-ice. It may be an efficient form of instant shelter for snowy and cold regions. This paper describes two field studies on ice domes carried out in Asahikawa. The first one is an investigation on the creep collapse of a 5-m span model under a concentrated load acting on a circular area at the apex. Normal displacements and temperatures were measured up to the collapse. Experimental collapse time was examined, introducing the classical creep buckling value of a completely spherical shell under uniform external pressure. The second study deals with both the construction technique and the creep test of a 10-m span model. The construction technique consists of: (1) inflating a membrane bag covered with rope, (2) spraying it with snow and water, (3) solidifying the snow-ice sherbet on it, and (4) removing the bag and rope for reuse. Subsequently, a creep test was carried out under snow load, and its structural behaviour up to the collapse was examined. Based on the results of these studies, the production of 20–30-m span ice shells may be practicable.     

Experimental study concerning the thermal conductivity of saturated materials in an acoustic field of variable intensity

Results are shown of experimental estimates concerned with the effective thermal conductivity of capillary-porous and colloidal materials in an acoustic field of up to 2400 W/m² intensity. It is shown that the thermal conductivity of these materials becomes here accordingly 3.0–5.5 times higher.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 4, pp. 639–642, April, 1973.