基于肖特基势垒二极管的太赫兹固态倍频源和检测器研制

本文基于GaAs肖特基势垒二极管以及混合集成电路工艺,对太赫兹固态倍频和检测技术开展了研究.文章结合肖特基势垒二极管物理结构,采用电磁场仿真软件和电路仿真软件相结合的综合分析方法,对各模块电路进行优化设计,研制出了高倍频效率的倍频源和高灵敏度的检测器(检波器和谐波混频器).0.15THz检波器测得最高检波电压灵敏度1600mV/mW,在0.11~0.17THz灵敏度典型值为600mV/mW,切线灵敏度优于-29dBm.0.15THz二倍频器测得最高倍频效率7.5%,在0.1474~0.152THz效率典型值为6.0%.0.18THz二倍频器测得最高倍频效率14.8%,在0.15~0.2THz效率典型值为8.0%.0.15THz谐波混频器测得最低变频损耗10.7dB,在0.135~0.165THz变频损耗典型值为12.5dB.0.18THz谐波混频器测得最低变频损耗5.8dB,在0.165~0.2THz变频损耗典型值为13.5dB,在0.21~0.24THz变频损耗典型值为11.5dB.     

CMOS射频集成电路的现状与进展

随着低功耗、可移动个人无线通信的发展和CMOS工艺性能的提高,用CMOS工艺实现无线通信系统的射频前端不仅必要而且可能.本文讨论了用CMOS工艺实现射频集成电路的特殊问题.首先介绍各种收发器的体系结构,对它们的优缺点进行比较,指出在设计中要考虑的一些问题.其次讨论CMOS射频前端的重要功能单元,包括低噪声放大器、混频器、频率综合器和功率放大器.对各单元模块在设计中的技术指标,可能采用的电路结构以及应该注意的问题进行了讨论.此外,论文还讨论了射频频段电感、电容等无源器件集成的可能性以及方法.最后对CMOS射频集成电路的发展方向提出了一些看法.     

Manufacturing polymer/clay nanocomposites through elongational flow technique

A novel processing technique that employs continuous elongational flow to fabricate polymer/clay nanocomposites has been developed and evaluated in this work. A self-made vane mixer has been used to supply the continuous elongational flow, while high-density polyethylene (HDPE) and organic montmorillonite (O-MMT) were used as the polymer matrix and clay, respectively. The morphology of resultant nanocomposites has been carefully revealed and studied by examining wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). Intercalation effect and dispersion of O-MMT layers have been investigated by the morphology study. The results indicate that the elongational flow has a great potential in melt intercalation of O-MMT, and can lead to an orderly O-MMT layers’ distribution. Thermal properties of as-mixed nanocomposites that prepared under elongational flow have been determined by the differential scanning calorimetry (DSC), which demonstrates that the introduction of O-MMT nano-sheets is bad for the crystal of HDPE matrix. The universal tensile test shows how O-MMT layers affect the mechanical properties of nanocomposites, including the tensile strength and elongation at break. The strain–stress relationship reveals that with continually adding O-MMT layers, the tensile strength increases at first, and then decreases. While the elongation at break shows the same trend.     

Mixing and Simplex Search for Optimal Illumination in Machine Vision

Mixed-color illumination affects the quality of images in industrial vision system and it is important to optimize color and intensity for image acquisition. This study used simplex search to find the optimal illumination in a short amount of time. A typical color mixer synthesized various color of lights by changing the inputs of RGB power LEDs and passing the lights through an optical system. The image quality under mixed-color illumination was calculated according to the sharpness. For the purpose of optimal illumination using simplex search, a probe network was organized with N + 1probing points for N inputs. The shape of the probe network, simplex, was varied through procedures of extension, contraction, and shrinkage. The inputs of the color mixer were changed until the size of the simplex became smaller than a threshold. The simplex search was tested for commercial semiconductor patterns, and was useful for finding the optimal illumination.     

Combined static mixers for high viscous fluids mixing

A new static mixer Cross-over-Disc has been invented to strip off the boundary layer and to make strong radial mixing. The pressure drop of Cross-over-Disc is 12-26 times as large as that of empty pipe with equivalent diameter and length. The mixing performance of Cross-over-Disc with 14 elements has been investigated in the viscosity range of 190–250 Pa·s by decoloration method, and the gray analysis of images shows that mixing inhomogeneity is about 7.5% and 9.4% for the mixing ratio of 5:1 and 10:1, respectively. Furthermore, mixing inhomogeneity for a combination of static mixing elements (four from Cross-over-Disc and three pairs from Sulzer-type) can be decreased to 2.1%–3.1% within a reasonable range of pressure drop.     

260 t鱼雷形混铁车检修工艺研究

文章从260t鱼雷形混铁车的结构入手，研究了鱼雷形混铁车走行部检修工艺装备布置的合理性，科学安排车辆走行部检修工序，形成一套完整的检修工艺，解决了260t鱼雷形混铁车检修工艺的新课题。     

中浓纸浆悬浮液的流动特性与混合实验

论述了中浓度（MC）纸浆的流动特性，由于纤维网络的存在，中浓度纸浆的泵送和混合均不同于其它类似水流的液体，对于中浓度纸浆的流动特性来说，其中一个重要的概念就是“流体化”，中浓度纸浆的流体化是和纤维网络的强度相对应的。在中浓度纸浆漂白中，纸浆产生流体化是达到较好的漂白质量的一个必要条件。本研究通过一个简单的纸浆流体化实验，测量了纸浆产生流体化所需的临界剪切应力，接着计算出纸浆产生流体化时的单位体积能量耗散，以此作为中浓度纸浆混合器的设计依据。     

基于谐波插入的提高混频器线性度方法的研究

提出了将谐波插入用于提高混频器线性度的方法。该方法是将输出信号的二次谐波及二次互调产物反馈(插入)到输入端,通过非线性系统后产生的信号可抵消由原信号引入的交调产物,从而减少输出端交调失真的一种反馈技术。与前馈法相比,二次谐波插入法具有电路简单、性能稳定、成本低廉等优点,而且便于实现。谐波插入方法对中频三阶交调产物抑制作用明显。给出了该方法的理论分析并做了仿真实验。     

近几年济钢铁前系统技术进步

介绍了近几年济钢依靠科技进步,在铁前系统技术改造方面所做的主要工作及技术改造所取得的效果,阐述了今后８济钢铁前系统在技术进步方面努力的方向。     

视频会议系统中视频混合器的二次编码优化

介绍了视频会议系统中构造多路视频混合器的基本原理，提出了一种在视频会议系统中视频混合器对混合图像进行二次编码时重新利用原始码流信息的方法，减少了运算量，提高了编码效率。