用超声脉冲反射谱评价圆管厚度的实验研究

垂直入射到固体圆管表面产生的反射超声脉冲波的频谱在圆管的厚度共振频率处产生谱陷，利用谱陷频率可以评价固体圆管的厚度。本文利用超声脉冲反射谱法在实验室内对不同形状的钢样品进行了厚度测量，测量得的厚度与样品的实际厚度的一致性很好。并且，超声波探头的频带越宽，则用此探头可以测量到的圆管的厚度范围越大。     

Measuring the diameter of cylindrical articles by the method of running a roller over their surfaces

Conclusions The tests of the model confirm the technical possibility of producing a transducer which combines the characteristic of a running roller and a feeler measuring instrument without any complications of the electronic part of the instrument.The above design is suitable for evaluating the extremal values of diameters of components when the component's cross section approaches an oval or elliptical shape.     

Study on small diameter drilling in GFRP

In small diameter drilling with the drilling machine, the drilled hole quality of the printed wiring board (PWB), made of GFRP, is evaluated by investigating the surface roughness and the internal damage to the hole. An investigation of the damage is conducted by changing the number of drilled holes. Additionally, in laser drilling using a CO₂ source and a YAG source, the laser drilling process is clarified by observing the damage to the hole, and moreover the relation between the drilling conditions and the damage of the hole is obtained. In conclusion, it is shown that, in the case of the present drilling machine, the anisotropy of the hole surface roughness is able to be developed by the tool tip profile, and as the new process is of no contact drilling, the application of a laser beam machine using a CO₂ laser source is effective in the smaller diameter drilling in PWB's.     

Measuring the diameter of a moving microwire conductor

Conclusions The dynamic properties of the automatic equipment model make it possible to measure the conductor diameters of the above microwires with an error of 0.5–0.7 for a wire propulsion speed of 2.5 mm/sec.Such systems are suitable for application in special measuring laboratories. If the measuring channels' operating speed of the polar-coordinate autocompensators is improved it will be possible to use them for manufacturing microwires with stable diameters.Translated from Izmeritel'naya Tekhnika, No. 11, pp. 39–41, November, 1974.     

Stressed state of cylindrical bodies with multilayer inhomogeneous coatings

We deduce engineering formulas for the evaluation of stresses in a cylinder with inhomogeneous multi-layer coatings by using the approach based on the application of generalized boundary conditions and the approach based on the reduction of the corresponding boundary-value problem of elasticity to the solution of integral equations. We also compare and analyze the ranges of applicability of each approach.     

Flow boiling in small diameter channels

Many studies have been carried out on two-phase flow heat transfer in channels with hydraulic diameter bigger than 6 mm, but relatively little work has been done for small diameter channels in the meso and compact range (diameter from 0.1 to 3 mm). The use of exchangers with small channels in refrigeration units, which are very numerous besides, could bring a significant reduction of the internal volume of the exchanger, and therefore diminish the refrigerant charge of the whole refrigerating system. One can imagine the interest to widen knowledge on the flow and the heat transfer in small-diameter tubes. This paper examine the thermal behavior of refrigerants boiling in small pipes. The correlations available for in-tube evaporation heat transfer coefficient are discussed and evaluated, when possible, and new research areas of relevance than can contribute to expand the use of small-diameter channels evaporators in refrigeration units are suggested.     

变厚度旋转圆柱壳的自由振动研究

为了提高旋转圆柱壳结构的使用性能和工作效率,减轻其质量已成为有效方式之一,针对这一需求,旋转圆柱壳结构有设计为厚度沿轴向变化即变厚度的趋势。基于此,利用Chebyshev-Ritz方法,对厚度沿轴向有3种线性变化形式的变厚度旋转圆柱壳的自由振动进行研究。考虑科氏力与离心力的影响,基于Sanders壳理论,将圆柱壳的位移场近似展开为Chebyshev多项式与边界函数乘积的形式,计算变厚度旋转圆柱壳的动能与势能,再根据Ritz方法获得变厚度旋转圆柱壳的频率方程。在此基础上,将所得结果与已有文献中的结果进行比较,验证了建模方法的准确性,并对计算结果进行了收敛性研究。最后比较了不同厚度变化形式下旋转圆柱壳的自由振动,并讨论了转速、厚度变化参数、圆柱壳长径比等参数对变厚度旋转圆柱壳自由振动的影响。     

Hyperthermia of cylindrical biotissue samples by microwave electromagnetic radiation

Consideration is given to the interaction of plane and cylindrical electromagnetic waves with layered cylindrical biotissue. Space distributions of the power density of heat loss are calculated and analyzed. The influence of biotissue inhomogeneities (arteries, veins) on electromagnetic heating is evaluated. The results reported can be used for hyperthermia of biological objects in oncology. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 2, pp. 268–272, March–April, 1998.