省级广播电视安全播出调度指挥平台的设计与应用

为切实推进省级安全播出调度指挥工作的信息化、网络化建设,进一步提高调度指挥效能,按照上级总体部署,结合省级具体情况,设计并建成了省级广播电视安全播出调度指挥平台工程.该工程的设计秉承安全、稳定、实用、经济的原则,充分采用当今尖端的计算机编程技术,将公告发布、数据传输、预警信息发送及视音频通信功能融为一体,并利用先进的网络集成和数字通信手段,通过光纤和SDH环网等设施将网络延伸至省局属各有关单位值班机房,既实现了安全播出信息资源共享和调度指挥指令第一时间到达播出第一线,又为安全播出事件事故的应急处置工作提供了便捷高效的平台.     

Modeling of silicon oxynitride etch microtrenching using genetic algorithm and neural network

A prediction model of etch microtrenching was constructed by using a neural network. The etching of silicon oxynitride films was conducted in C₂F₆ inductively coupled plasma. The process parameters that were varied in a statistical experimental design include radio frequency source power, bias power, pressure, and C₂F₆ flow rate. The etch microtrenching was quantified from scanning electron microscope images. The prediction accuracy of optimized neural network model with genetic algorithm had a root mean-squared error of 0.03 nm/min. Compared to conventional model, this demonstrates an improvement of about 32%. The constructed model was used to infer etch mechanisms particularly as a function of pressure. Roles of profile sidewall variations were investigated by relating them to the microtrenchings. The pressure effect was conspicuous at lower source power, lower bias power, or higher C₂F₆ flow rate. Microtrenching variations could be reasonably explained by the expected ion reflection from the profile sidewall. The pressure effect seemed to be strongly affected by the relative dominance of fluorine-driven etching over polymer deposition initially maintained in the chamber.     

无源光网络的工程特点与实用设计:PON均值查图法

介绍了无源光网络的工程设计特点 ,分析了ITU TG 982推荐采用的高斯统计法的应用限制 ,并介绍了一种新的无源光网络设计预算的简便方法———PON均值查图法 ,该方法的特点和A、B图及查图使用方法。最后试用PON均值查图法 ,对一个包含有 1∶3非均匀分光器的 4级连 1/ 8无源分配网络进行了工程设计预算。     

Joint spectrum and power optimization in the design of the UMTS satellite component

The paper provides a power and spectrum joint analysis of the universal mobile telecommunications system (UMTS) satellite component, based on the wideband code division multiple access (W‐CDMA) air interface. In fact, power and spectral efficiency may become highly conflicting requirements in a satellite system and a trade‐off analysis is needed to drive a proper dimensioning of the satellite. The proposed approach allows a dimensioning of the satellite component either in terms of orbit and power budget or in terms of additional capacity for the terrestrial section, for specified orbit and power limitations. The impact of candidate frequency bands, orbit type and diversity on both spectral and power requirements of the satellite component is evaluated. For given traffic requirements, power‐vs‐spectrum trade‐off is proposed which ensures a proper resources utilization. The efficiency evaluation accounts for: beams overlapping, ortho gonality, voice activity factor, diversity and cross‐polarization frequency reuse. Perfect power control is assumed and the effect of the excess power required by the shadowed users is accounted for in the interference calculation. Furthermore, still in the frame of a proper resource exploitation, a possible optimization of capacity through the use of unpaired bands in the two link directions is analysed. Copyright © 2001 John Wiley & Sons, Ltd.     

AlGaN/GaN HFET的优化设计

从自洽求解薛定谔方程和泊松方程出发研究了不同掺杂方式下异质结能带和二维电子气的行为。发现掺杂能剪裁异质结能带的弯曲度、控制电子气的二维特性和浓度。在此基础上研究了不同掺杂方式的掺杂效率。通过掺杂和势垒结构的优化设计,得出了用δ掺杂加薄AlN隔离层的结构,既提高了电子气浓度,又保持电子气的强二维特性。从电子气浓度和栅对电子气的控制力度出发,提出了HFET势垒优化设计中的电子气浓度与势垒层厚度乘积规则。依据二维表面态理论,研究了表面态随帽层掺杂结构的变化。从前述乘积规则和表面态变化出发进行了内、外沟道异质结构的优化设计。优化结构既提高了电子气浓度和跨导,降低了欧姆接触电阻,又抑制了电流崩塌。     

一种易于制造的空间相机光学系统设计

空间技术的不断发展对空间相机光学系统的设计不断提出新的要求,为了提高相机系统的可靠性,对系统的面型加工精度有更高的要求。介绍了一种易于制造的空间相机光学系统,基于R-C系统,设计了含有三块球面校正镜组件的折反式光学系统。结果表明,该光学系统在空间频率50 lp/mm处,调制传递函数均大于0.4,主镜和次镜均为二次曲面,其余均为球面,具有易于制造装调等优点。     

Reproducing consistent wireless protocol performance across environments

Full scale experimentation with wireless networks in deployment environments is difficult. Therefore a common validation technique is to test a prototype network in a convenient environment prior to deployment. In this paper, we consider the problem of obtaining comparable protocol performance when the test and deployment environments differ in RF propagation environment and/or inter-node spacing. To achieve comparable protocol behavior in the two settings, we propose the concept of “link usage spectrum”. Based on the hypothesis that the link usage spectrum is a gross predictor for network performance, we show how to replicate in the test setting the link usage spectrum of the protocol that is expected in the deployment setting. We show our technique for achieving comparable protocol behavior via experiments and simulations in multiple indoor and outdoor propagation environments. The link usage spectrum is protocol specific; we illustrate for a family of protocols how the link usage spectrum is calculated analytically, from the protocol metric for choosing forwarding links in the network, and how power scaling can be used to match the link usage spectrum across networks.     

通用航电总线驱动软件设计与应用

针对现有航电仿真系统中总线驱动软件存在的功能单一、可扩展性差、重复开发严重等问题,结合航电仿真系统数据驱动特点,提出了一种扩展便捷、配置灵活、运行稳定的通用航空总线驱动仿真软件的设计与实现方案.该方案基于面向对象设计思想,采用分层式软件架构与模块化设计,利用可扩展标记语言(XML)格式的灵活配置特性和发布/订阅式数据分发网络的动态性及传输优势进行设计,保证了方案的通用性和灵活性,提高了软件的健壮性和可重用性.基于该方案设计的通用总线驱动软件可显著提高航电仿真场景中多总线数据分发的效率.     

高速深孔加工顶紧系统设计分析

在高速深孔加工中,其中影响加工可靠性的重要因素就是工件以及受油器,在不同的高速深孔加工过程中,对连接工件以及受油器的顶紧力的要求也是不一样的,对顶紧力的精度有着更高的要求.本文就高速深孔加工顶紧系统设计进行具体地分析,进而使该技术得到更好地应用.     

不同粘结体系对PBX炸药能量输出特性的影响

粘结剂作为PBX炸药中重要的添加剂,对炸药的力学性能、能量特性等都有很大的影响.为研究不同粘结体系对PBX炸药水下爆炸能量特性的影响,首先对不同粘结体系炸药配方进行优化设计,然后进行不同粘结体系PBX炸药的水下爆炸试验.试验结果表明:与HTPB惰性粘结体系炸药相比,含能粘结体系应用于PBX炸药后,比冲击波能提高了12%~23%;但是由于含能粘结体系力学和工艺性能的限制,使得炸药固含量降低,降低了炸药的气泡能.总的来看,TEGDN、GAP、HTPB粘结体系的PBX炸药总能量分别达到了2.01、1.99、2.15倍TNT当量.