CATV网渐进升级为全业务接入网的技术

本文就ＣＡＴＶ网向宽带全业务网升级的策略和技术进行了讨论。首称要将现有ＣＡＴＶ网改造为双向传输网。在此基础上,建成ＣＡＴＶ广播网和计算机网并行的网络。在计算机网中,应用Ｃａｂｌｅ ｍｏｄｅｍ实现数据双向传播,或在ＣＡＴＶ网中应用暂时富裕的光纤构成独立计算机网。     

一种混合型盲均衡算法

盲均衡器在通信系统中有着重要的作用，但一般的盲均衡器存在收敛速度慢的缺点，本文以广泛使用的CMA（ConstantModulusAlgorithm）为基础，提出一种混合型均衡算法，不仅提高了收敛速度，而且减小了收敛后的剩余干扰，使均衡器收敛后不必切换到普通均衡方式。     

火力发电厂球磨机应用磁性衬板的初探

通过介绍磁性衬板在矿山球磨机上应用的原理和实例,及比较矿山球磨机和火力发电机球磨机结构、运行方面的异同,总结和分析了在滦河发电厂６号炉球磨机上进行局部磁性衬板试验的情况,认为有必要进行应用磁性衬板的整体试运,方能定论。     

乘改革开放春风开拓燃机安装市场

以天然气或柴油为燃料的燃气－蒸汽联合循环发电技术具有热效率高,对环境污染小的突出优点,央国内外建设燃机电厂逐年呈上升之势。文章总结了武汉电力燃机安装有限公司秉发放的春风,开辟国内燃机安装市场的发展道路,为优质、高速地建设燃机电站,争取早日打入国际市场提供了富贵的经验。     

导弹箱式发射的仿真研究

建立了导弹箱式发射的数学模型，并对该数学模型进行计算机仿真．通过仿真。分析了导弹质量、质心、助推器推力、推力偏心、偏斜和适配器位置等因素对导弹发射安全性的影响．该数学模型具有一定的通用性，仿真结论具有工程应用价值．     

一种高压4H-SiC二极管改进场限环结终端结构

设计了一种用于3.3 kV4H-SiC肖特基二极管的场限环(FLR)结终端保护结构。该结终端保护结构是通过在高能离子注入形成二极管p+有源区的同时在结边缘形成多个不同间距的p+场限环来实现的,以避免多次离子注入。借助半导体数值仿真软件Silvaco,对制备二极管所用的4H-SiC材料外延层耐压特性进行了仿真验证;对场限环的环间距和场限环宽度进行了优化,形成由34个宽度5μm的场限环构成的场限环结终端结构。以此为基础,采用4英寸(1英寸=2.54 cm)n型4H-SiC外延片成功制备了3.3 kV4H-SiC二极管器件。简述了制备工艺流程,给出了部分关键工艺参数。对二极管芯片进行了在片测试和分析,反向漏电流密度1 mA/cm2时的击穿电压约为3.9 kV,且70%以上的二极管耐压可达到3.6 kV以上,验证了这一场限环结终端的可行性。     

面向需求面向服务(上)——深圳广播电影电视集团网络化建设实践

本文从深圳广播电影电视集团网络化建设实践出发,针对电视台全台网系统的建设、维护两大阶段的相关问题,提出了面向需求的网络系统架构模式和面向服务的网络系统运维管理模式,对广电媒体行业的网络系统架构和运维管理的模式和方法进行了初步的探讨.     

Improving Ideality of P-Type Organic Field-Effect Transistors via Preventing Undesired Minority Carrier Injection

Electron injection plays a crucial role in arousing the double-slope characteristics for p-type organic field-effect transistors (OFETs) with narrow-bandgap organic semiconductors (OSCs). This issue will not only result in the misrepresentation of OFET performance but also may cause device instability, hence impeding their further development in real-world applications. A facile and highly efficient approach is developed to circumvent this issue by implementing modification on the electrode/organic semiconductor interface. An ultrathin layer of wide-bandgap OSC with suitable energy levels is introduced to block the undesirable electron injection. By this means, typical double-slope behaviors and bias stress stability in the p-type OFETs can be significantly improved. Using 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene-based OFETs the double-slope behaviors of as-fabricated devices are effectively converted to near-ideal behaviors after modification, leading to a dramatic improvement of average reliability from 65.11% to 91.76%. Furthermore, the positive drift of transfer curves under prolonged bias stress is also successfully suppressed. This strategy demonstrates good universality and can provide a new guideline for the fabrication of OFETs with ideal behaviors.     

Effective image retrieval based on hidden concept discovery in image database.

This paper addresses content-based image retrieval in general, and in particular, focuses on developing a hidden semantic concept discovery methodology to address effective semantics-intensive image retrieval. In our approach, each image in the database is segmented into regions associated with homogenous color, texture, and shape features. By exploiting regional statistical information in each image and employing a vector quantization method, a uniform and sparse region-based representation is achieved. With this representation, a probabilistic model based on statistical-hidden-class assumptions of the image database is obtained, to which the expectation-maximization technique is applied to analyze semantic concepts hidden in the database. An elaborated retrieval algorithm is designed to support the probabilistic model. The semantic similarity is measured through integrating the posterior probabilities of the transformed query image, as well as a constructed negative example, to the discovered semantic concepts. The proposed approach has a solid statistical foundation; the experimental evaluations on a database of 10000 general-purposed images demonstrate its promise and effectiveness.