Diagnostic testing of a 10-kbit bubble memory chip

A 10-kbit bubble memory chip has been designed and fabricated. Testing was accomplished using a new diagnostic test system, which can drive the bubble chip at two different speeds with bias fields switched synchronously with the bubble propagation. Bias margins of the fabricated chips were analyzed and it was confirmed that a sufficient bias-margin window could be assured in long-term operation.     

Theoretical analysis of longevity testing on bubble memory devices

Theoretical results of magnetic bubble device long-term reliability testing are reported. The bubble during propagation along Permalloy tracks is represented by a simple, one-dimensional stochastic model. An equation to describe fluctuation in cylindrical bubble radius is approximated in the Langevin type stochastic differential equation, in which a set of small effects, such as interaction among bubbles and crystal nonuniformity, are considered as a white noise forcing term. Estimating the average time to bubble annihilation or runout (bubble memory mean time to failure) is reduced to a level-crossing problem for a random process. Calculated bias field margin degradation shows a qualitative agreement with experimental results for an actual bubble device. Bubble material parameters for obtaining maximum operation time are suggested.     

空气净化器检测用的香烟烟雾发生器

香烟烟雾的发生采取正压式,并通过对进入发生器的气体压力和流量进行控制,使得香烟烟雾发生的速度和浓度均是可控的,可以应用于空气净化器洁净空气量(CADR)的检测。     

Digital generator for adjustment and testing of electrical prospecting equipment

The block diagram is described of a circuit that generates a digital signal representing a sum of exponents with initial values and attenuation constants against the background of sinusoidal noise of a given frequency and amplitude.Translated from Izmeritel'naya Tekhnika, No. 12, pp. 39–42, December, 1993.     

无蜗壳离心风机性能及测试方法的探讨

试验分析普通离心风机、无蜗壳离心风机和箱式无蜗壳离心风机的性能差异,总结不同测试方法对无蜗壳离心风机性能测试结果的影响。     

Hydrodynamics of a centrifugal sprayer

An asymptotic analysis is made of the flow of a film of an inviscid incompressible liquid in a centrifugal sprayer under high heads. The conditions under which the film turns through an angle along the surface of the sprayer are determined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 51, No. 1, pp. 68–75, July, 1986.     

Separation of a vapor bubble and calculation of the critical bubble radius

On the basis of the solution to the equation of motion of a variable mass, a formula is derived for analytically calculating the critical radius of a vapor bubble in a boiling liquid during free flow of the latter.Translated from Ihzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 5, pp. 831–835, May, 1973.     

A novel signal processing technique for eddy-current testing ofsteam generator tubes

In eddy-current testing of steam generator tubes of nuclear power plants, the signals of defects may be corrupted by noise and other nondefect signals arising from the probe lift-off and the structures attached to the tubes, resulting in unreliable detection and inaccurate characterization of defects. In this paper, a novel signal processing technique is presented to reduce the noise and nondefect signals by the use of a wavelet transform. The noise and nondefect signals are reduced by first decomposing testing signals into wavelet components and then modifying the wavelet coefficients. The defect signals embedded in noise and nondefect signals are reconstructed through the inverse wavelet transform of the modified wavelet coefficients. The results of processing the one-dimensional and two-dimensional signals from eddy-current testing of tube test pieces show that this signal processing technique is effective for extracting defect signals embedded in noise and nondefect signals     

Fatigue failure of a centrifugal compressor

A single stage centrifugal type compressor failed during operation and a blade detached. Failure analysis was carried out to delineate the cause of the failure.Investigation shows that multiple fatigue cracks were generated during service from forging defects in the root area of the blade. When they grew to a critical size under (high cycle fatigue) HCF, the blade detached from the root in an over load manner. At the high rpm of the engine, the detached blade collided with other rotating part of the engine and entangled between the compressor and multiplier assembly. This resulted in the subsequent damage in the engine.     

Analytical model of a bubble switch

A model is presented for a bubble switch based on the Y-bar propagation element. Good correlation of the predictions of the model with experimental results is found for 8 μ bubbles. The heuristically derived scaling law, which predicts that the switching current must remain constant as the bubble diameter decreases, is confirmed by direct calculation with the model. The model shows that it will be increasingly difficult to design switches as the bubble diameter is reduced below 1 μ.     

Optical operation of a magnetic bubble

A magnetic bubble domain is generated on liquid-phase epitaxial (LPE) garnet film by focusing laser light. It is possible to write with only a few milliwatts light power on a thin film with a low anisotropy field. Because the Bi-containing LPE films used have a high Faraday rotation angle, a written bit or bubble can be read out with a high contrast ratio. Because of its low coercivity, the bubble moves along the temperature gradient to the region heated by the light beam and is then stabilized at a corner of a square formed on the film by etching or ion-implantation. Erasure is possible selectively or all together by increasing the bias field. These optical operations of a magnetic bubble are discussed in connection with the material parameters.     

Breakaway of a bubble from a heating surface

In this paper we solve the problem of determining the breakaway, diameter of the vapor bubble in the case of a large number of active vapor-forming centers. The motion of the liquid is discussed. The dynamic pressure of the liquid surrounding the vapor bubble and the radius of the bubble on breakaway from the heating surface are determined.     

离心压缩机的操作维护

本文通过自身的实践 ,强调对离心压缩机专业理论知识的学习 ,提高操作技能 ,了解机组的内部构造 ,掌握离心压缩机的宏观运行规律的必要性。叙述了利用传统的检测方法、结合先进的检测仪器、科学的逻辑思维方法来全面分析离心压缩机出现的各种故障的心得体会。     

High friction on a bubble mattress

Reducing the friction of liquid flows on solid surfaces has become an important issue with the development of microfluidics systems, and more generally for the manipulation of fluids at small scales. To achieve high slippage of liquids at walls, the use of gas as a lubricant--such as microbubbles trapped in superhydrophobic surfaces--has been suggested. The effect of microbubbles on the effective boundary condition has been investigated in a number of theoretical studies, which basically show that on flat composite interfaces the magnitude of the slippage is proportional to the periodicity of the gaseous patterns. Recent experiments aiming to probe the effective boundary condition on superhydrophobic surfaces with trapped bubbles have indeed shown high slippage in agreement with these theoretical predictions. Here, we report nanorheology measurements of the boundary flow on a surface with calibrated microbubbles. We show that gas trapped at a solid surface can also act as an anti-lubricant and promote high friction. The liquid-gas menisci have a dramatic influence on the boundary condition, and can turn it from slippery to sticky. It is therefore essential to integrate the control of menisci in fluidic microsystems designed to reduce wall friction.     

Steady motion of a gas bubble in a liquid

A method is proposed for calculating the velocity of a gas bubble during a steady lift in a liquid, on the assumption that the bubble transmits to the medium an array of weak waves.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 25, No. 4, pp. 656–662, October, 1973.     

Slow motion of a bubble in a viscoelastic fluid

Summary The motion of a deformed spherical body in a fluid medium is significantly different from the motion of an undeformed spherical body in the same medium. It is shown in this work that a bubble moving in a viscoelastic fluid takes the shaper=a+U ₀₀/a( ₁– ₂)(180R ³+240R ²+816R+672)P ₂(cos)/960(1+R)³ and so one must expect the dynamics of a bubble moving in a non-Newtonian fluid to be significantly different from that of a bubble moving in a purely viscous fluid.     

Experimental investigation of a molecular generator

Conclusions Tests have shown that above molecular generator has a highly stable frequency and good operational properties. For any given absolute frequency the resonator should be tuned with respect to variations in the ammonia gas pressure. The accuracy of the absolute frequency of a molecular generator obtained by this means and the effect of various factors on it will be further investigated.A. I. Samoilovich participated in designing our molecular generator model, he also suggested the technique and carried out the construction of the grid with long channels. M.I. Klyus took part in the construction of the generator and E. Z. Orlov in the tests described above.