Effect of flexibility of substructures upon thermal behaviour of spherical double layer space truss domes. Part II: Gradient & partial loading

This paper presents the second part of a study on the influence of the type and properties of support conditions on the thermal behaviour of spherical double layer space truss roofs. Whereas the first part focused on the consequences of uniform thermal loadings, this paper studies the effects of support flexibilities on the behaviour of such structures subjected to gradient and partial loadings. It is observed that the thermal forces are very high and depend on the magnitude of temperature and the dome size. It is also pointed that the important point in partial loading is the unsymmetrical deformation and behaviour of the dome, while in gradient loading it is the rotational deformations. Finally, it is concluded that the use of rigid supports should be carefully examined.     

一种Ka波段混合集成的单平衡混频器

本文介绍了一种由正交E面折叠魔T与鳍线混合集成的Ka波段单平衡混频器的研制概况,混频器使用国产W121封装的带状引线混频二极管。介质基片采用国产的仿RT-Duroid5880,经测试该混频器的最小单边带噪声为5.7dB(不包括前中噪声),射频与本振的隔离度均优于20dB,整体尺寸为32×19×14(mm)。     

Molecular beam epitaxial HgCdTe material characteristics and device performance: Reproducibility status

Extensive material, device, and focal plane array (FPA) reproducibility data are presented to demonstrate significant advances made in the molecular beam epitaxial (MBE) HgCdTe technology. Excellent control of the composition, growth rate, layer thickness, doping concentration, dislocation density, and transport characteristics has been demonstrated. A change in the bandgap is readily achieved by adjusting the beam fluxes, demonstrating the flexibility of MBE in responding to the needs of infrared detection applications in various spectral bands. High performance of photodiodes fabricated on MBE HgCdTe layers reflects on the overall quality of the grown material. The photodiodes were planar p-on-n junctions fabricated by As ion-implantation into indium doped, n-type, in situ grown double layer heterostructures. At 77K, diodes fabricated on MBE Hg_1−xCd_xTe with x ≈ 0.30 (λ_co ≈ 5.6 μm), x ≈ 0.26 (λ_co ≈ 7 μm), x ≈ 0.23 (λ_co ≈ 10 μm) show R₀A products in excess of 1 x 10⁶ ohm-cm², 7 x 10⁵ ohm-cm², and 3 x 10² ohm-cm², respectively. These devices also show high quantum efficiency. As a means to assess the uniformity of the MBE HgCdTe material, two-dimensional 64 x 64 and 128 x 128 mosaic detector arrays were hybridized to Si multiplexers. These focal plane arrays show an operability as high as 97% at 77K for the x ≈ 0.23 spectral band and 93% at 77K for the x ≈ 0.26 spectral band. The operability is limited partly by the density of void-type defects that are present in the MBE grown layers and are easily identified under an optical microscope.     

冷床上料系统双槽上卸钢装置的改造

济南钢铁总厂针对２５０ｍｍ半连轧机原冷床上料系统存在的问题进行了技术改造，将双槽推料改为单槽推料，并优化控制系统，简化设备结构，提高了工作效率，满足了半连轧机后面配６５ｍ超短冷床实现高速、无间隙轧制的生产要求。     

低本底测量用的6路~3He计数管电子学组合装置

本文介绍一个结构紧凑,对本底中子有良好屏蔽效果的多路中子探测装置。装置内有6路~3He计数管—前置放大器—主放大器—甄别器,一个求和电路和高压电源,每一路均有模拟信号和甄别信号输出。     

阴极射线管显示器不同屏显字符形状和颜色特征的识别工效的比较研究

本实验研究用数字、汉字、飞机图标和几何图形比较了颜色编码、形状编码及颜色和形状双重编码的检测工效。在阴极射线管（ＣＲＴ）显示器屏幕的９个固定位置（３×３矩阵）上同时显示同一形状不同颜色、同一颜色不同形状或颜色和形状都不相同的３、６或９个字符，让被试按颜色、形状或同时按颜色和形状找出一目标字符，并按压键标数字与所找字符显示位置号相同的键。每个字符在各个位置的显示概率是相等的，显示的先后次序是随机的。字符的显示、目标字符的检测时间和错误率由计算机系统程序控制，实时计算和打印记录。结果表明，就检测工效而言，颜色编码优于颜色和形状双重编码，后者又优于形状编码；目标字符的检测时间随同时显示字符的数量的增加而增长，并得到了从同时显示的３、６、９个字符中按不同特征检测目标字符的搜索一识别时间和包括按键操作在内的目标检测时间。     

An experimental study on the axial collapse characteristics of hat and double hat shaped section members at various velocities

In this study, the axial collapse tests were performed under either static (or quasi-static) or impact loads with several collapse velocities based on the expectation that para-closed sections of the front-end side members (spot welded hat and double hat shaped section members) would show quite different collapse characteristics from those for seamless section. The test results showed that both of the hat and double hat shaped section members failed in the stable sequential collapse mode in the static or quasi-static collapse tests, while the double hat shaped section members underwent the unstable collapse mode especially when the impact velocity is high. The mean collapse loads in the hat shaped section members increase with collapse velocity for all the cases of the static, quasi-static, and impact collapse tests. In the double hat shaped section members, however, the mean collapse loads decrease with increase in collapse velocity in the impact tests.     

Ni-based superalloy surface alloying by double-glow plasma surface alloying technique

The double-glow surface alloying technique, also called the Xu-Tec/Xu-Loy process, is a novel technique in the field of surface alloying. This technique allows alloy layers with unique physical, chemical and mechanical properties, such as nickel-based alloy layers, stainless-steel layers and age-hardened surface high-speed steel layers to be formed at the surface of treated metallic materials. In this paper, recent research of the application of the double-glow plasma surface alloying technique in the formation of corrosion resistance alloy layers is briefly reviewed. The results of a study of Ni-Cr-Mo-Nb and Ni-Cr-Mo-Cu corrosion-resistant alloying layers as well as composite alloying layers with an electric brush plating Ni interlayer are reported.     

Performance measures of an ant based decentralised routing scheme for circuit switching communication networks

 Swarm intelligence is a new challenging branch of artificial life which takes advantage of the collective behaviour of animals with limited intellectual faculties (insects, flocking birds, schools of fish) to solve algorithmically complex problems. Recently a new routing method based on the way that ants are communicating with each other has been applied to solve routing problems in telecommunication networks. This paper examines the behavior of an ant based decentralised router using an adequate set of commonly acceptable and some newly introduced metrics.     

使用在系统可编程模拟器件实现二阶控制系统

在系统可编程模拟技术ispPAC改变了传统的模拟电路的设计和实现方法。本文阐述了在系统可编程器件的结构特性以及工作原理,并提出了使用该器件实现二阶控制系统的方法。计算机仿真和实测结果表明用ispPAC10器件能够实现各种二阶控制器功能,并具有良好的电路重构、级联及可编程性能。