Estimation of viscosity of ternary-metallic melts

A new model, based on Seetharaman’s viscosity model and Chou’s geometric-thermodynamic model, to predict the viscosity of ternary-metallic melts has been established. The viscosities of Ag-Au-Cu and Ag-Sn-Cu systems have been calculated with the present model, and the results are consistent with the experimental data. The viscosities of Au-Ni-Cu, Fe-Ni-Cu, Al-Sn-Cu, and In-Sn-Bi systems have also been predicted by the present model.     

化学镀镍合金在电子工业中的应用

对化学镀镍合金铁工艺和性能特性及其在电子工业中的应有委展现状作了评述。化学镀镍合金具有镀层均匀，适用基材广，结合力高，硬度高，优良的耐磨、耐蚀性，可焊性好和特殊的电磁性能等特性，在电子工业中获得了广泛的应用。文中着重介绍了化学镀镍合金在磁盘、电磁屏蔽、微电路、半导体、连接器及薄膜电阻上的应用情况。这些案例说明，合理应用化学镀镍合金技术，有利于提高电子元器件的质量，降低成本，促进技术进步。     

北京谱仪端盖簇射计数器工作气体的研究

为使北京谱仪端盖族射计数器更好地工作在自猝灭流光ＳＱＳ模式下，提高其能量分辨以及线性等指标，用Ａｒ，ＣＯ２，Ｌｓｏｂｕｔａｎｅ三元工作气体对探测器的工作性能进行了仔细研究，找出了一适合于主雇地数器的工作气体，此外，还研究了异丁的纯度对探测器性能的影响。     

Nonepitaxial Orientation in Sol–Gel Bismuth Titanate Films

Control over crystallographic orientation in ceramic thin films is important for highly anisotropic structures. Layered perovskites, like Bi₄Ti₃O₁₂, have interesting properties associated with their ferroelectric nature, which may be fully exploited only when films are highly textured. Textured films of this titanate were fabricated via a sol–gel technique without using epitaxial growth. Orientation in the film is confirmed by XRD and SEM, and supported by refractive index and dielectric measurements. In an attempt to explain the orienting effect, light scattering experiments were conducted to yield information about the molecular size, shape, and conformation of macromolecules as the sol–gel solution ages and condensation reactions proceed. These experiments clearly show an increase in the size of molecular clusters with time. We believe that it is the organization of these large clusters during spin coating, and the relationship of the backbone chemistry to the crystal structure of Bi₄Ti₃O₁₂, that are responsible for the observed orientation.     

通信用VRLA蓄电池可靠性指标及计算探讨

在说明通信局（站）电源系统对VRLA蓄电池组可靠性要求的基础上，阐述了为了达到电信设备的电压、电流需求，通过串联或串并联构成电池组的单体VRLA蓄电池应达到的可靠性指标。在确定单体VRLA蓄电池应达到的可靠性指标。在确定单体VRLA蓄电池可靠性参数时，可通过现场使用调查或加速寿命试验的办法来求得。在单体VRLA蓄电池可靠性指标过低的情况下，可通过多种冗余连接方式来提高电池组的可靠性。     

CT引导下经皮穿刺骨骼活检时穿刺针的选择与应用

在行骨骼活检时，穿刺针的选择非常重要，甚至直接影响着活检的成功与否。笔者根据多次实践，应用环锯和Ackerman钻取外替代传统的活检方法取得了较好的效果。     

长脉冲激光沉积原位生成YBaCuO超导膜

用长脉冲激光(脉冲宽度150μs,波长1.06μm)辐照高温烧结的YBa_2Cu_3O_(7-x)靶,在6Pa的氧气压强下,巳在(100)YSZ单晶衬底上原位生成YBa_2Cu_(?)O_(7-x)超导膜。衬底置于750℃的加热器上,衬底与靶之间的距离5cm,用该法制得的薄膜光亮坚实,正常态呈金属性,零电阻温度为84.7K。用XRD和SEM对薄膜进行了分析研究。     

CO_2激光对兔脑组织血脑屏障的影响

同等功率和照射时间条件下,在14只家兔大脑皮质运用伊文思蓝染料和超微结构观察方法进行血脑屏障改变的研究。结果表明:CO_2激光作用十分表浅,且激光作用后的水肿层血脑屏障改变是可逆的。     

Magnetic field effects on g-jitter induced flow and solute transport

Numerical modeling and analyses are presented of magnetic damping of g-jitter driven fluid flow and its effect on the solutal striation in a simplified Bridgman-Stockbarger crystal growth system under microgravity. The model development is based on the finite element solution of the momentum, energy and solute transport equations under g-jitter conditions in the presence of an external magnetic field. The numerical model is verified by comparison with analytical solutions obtained for a simple parallel plate channel flow driven by g-jitter in a transverse magnetic field. Simulations are carried out to study the behavior of convective flow and solutal transport induced by the combined g-jitter and magnetohydrodynamic forces. Both the idealized single frequency g-jitter force and the real g-jitter perturbation taken during space flight are considered. Results indicate that an applied magnetic field can effectively damp the velocity caused by g-jitter and help to reduce the time variation of solute redistribution. A stronger applied field is more effective in suppressing the convective flows and hence reducing concentration variation. It is found that g-jitter driven flows have the same oscillation period as the driving force with or without the applied field. However, an applied magnetic field shortens the transient period over which the flow field evolves into a quasi-steady state time harmonic oscillation after g-jitter sets in. The flow intensity increases with an increase in g-jitter magnitude but decreases with an increase in the applied field strength. The reduced convection in the liquid pool by the applied magnetic field results in a reduction of the concentration oscillation. The magnetic field is very useful in suppressing the spiking velocities that are induced by the spikes in the real g-jitter data. The damping effect is more pronounced if the magnetic field is switched on before the onset of g-jitter disturbances.     

Turbo Pascal在网络数据库图形处理中的应用

本文介绍用Turbo Pascal 5.0在3~+网上运行的DBASEⅢplus网络数据库中进行图形处理的技术.