孔径法测量铜带残余应力的试验研究

介绍了用于薄板残余应力测量的新方法——孔径法,该方法是通过测量冲孔直径的变化来间接求出各方向的残余应力;文中详细阐述了残余应力的标定方法;由于可针对不同材料建立了被测材料的平均应力(σ_l)与被测板材宽度(B)、厚度(H)以及冲孔后直径变化率(△D_i/D)之间的数学模型,因而使薄板残余应力测量变得简便而经济;此外还对该方法的分辨率与测量精度进行了实验、计算与分析。     

Microstructures of high-J c melt-textured YBa2Cu3O7−x /Ag superconductors

Silver has been previously added to the melt-textured YBa₂Cu₃O_7?x in order to increase the critical current density (J _c ) of these materials. However, the effect of this addition on theJ _c is presently unclear. The purpose of this study is to investigate the effect of silver on both critical current density and the microstructure of the melt-textured YBa₂Cu₃O_7?x superconductors by means of X-ray diffraction, optical polarized microscopy, and transmission electron microscopy (TEM). TheJ _c of the MTG YBCO/Ag samples is more than 10⁴A/cm² under the 5 kOe magnetic field. It has been shown that as the concentration of silver increases, the fraction of the 211 phase dispersed within the 123 matrix decreases. Therefore, theJ _c slightly decreases. These results, together with the effect of the 211 phase, dislocations, and other structure defects on flux pinning, are described in this paper.     

Probabilistic linear models for multiresolution estimation in gray-level images

A multiresolution analysis of digital gray-level images is presented. A gray-level multi-scale framework is determined from two main assumptions: the gray scale is binary at the finest spatial resolution, and the gray levels of composed regions are obtained additively. In order to interrelate the gray-level histograms of the same image at different resolutions, probabilistic linear models are developed, which are then applied for estimation. Linear-optimization theory is used as a way of constructing such models. A general procedure for image processing is sketched, based on gray-level estimation. A versatile algorithm for nonlinear filtering is derived. Some examples of prospective applications are given.This work was partially supported by grant TIC91-646 from the DGYCIT of the Spanish Government.     

Effect of ion energy on hydrogen diffusion in n- and p-GaAs

The ion energy during electron cyclotron resonance (ECR) plasma hydrogenation is found to have a strong effect on both the effective diffusivity and solubility of hydrogen in n⁺ and p⁺ GaAs. For fixed plasma exposure conditions (30 min, 250°C) the diffusion depths for -150 V acceleration voltage are ~50 and ~100% larger, respectively, in p⁺- and n⁺-GaAs compared to 0 V acceleration voltage. The smaller incorporation depths at lower ion energy coincide with much larger peak hydrogen concentrations and higher apparent thermal stability of passivated dopants     

关于生物系统超微弱发光的实验研究

生物系统存在超微弱光子辐射现象。通过一系列实验研究,我们认为,这种光子辐射既有低水平化学发光的性质,又有受激辐射的性质,是受激的低水平化学发光。     

Rapid isothermal processing for fabrication of GaAs-basedelectronic devices [HBTs]

The use of rapid isothermal processing (RIP) is detailed for each of the three annealing steps in the fabrication of heterostructure-based devices such as heterojunction bipolar transistors (HBTs). RIP can be used for the alloying of ohmic metal contacts, annealing of ion-bombarded regions for device isolation or parasitic capacitance reduction, and for conventional implant activation annealing. High-speed (f_T=65 GHz) HBTs were achieved using RIP for all of the required heating steps. The authors compare the use of several types of silicon carbide-coated graphite susceptors for eliminating slip formation on 2- and 3-in-diameter GaAs wafers during high-temperature implant activation annealing     

Nucleation and growth of nickel by electrodeposition under galvanostatic conditions

The first stages of nickel electrodeposition on amorphous carbon and polycrystalline silver substrates have been studied under galvanostatic conditions. An island growth mode is observed on the two types of substrate. For equivalent conditions the cluster density is higher on silver substrates than on carbon substrates. Dissolution of some nickel clusters is observed a short time after the onset of electrolysis on carbon substrates. This is confirmed by the evolution of the current efficiency and the evolution of the metal surface cluster density as a function of the quantity of electricity.