利用PCB设计工具进行集成电路版图设计

如果EDA系统配置不全面,如何充分利用现有条件更好更快地完成集成电路的设计工作?本文介绍了我们利用PCB(印刷电路板)设计工具设计集成电路版图的方法,并以一个600门的数字电路为例加以说明。PCB设计与版图设计本是两种类型的工作,但在某些条件下,将它们结合在一起可以充分利用计算机资源高效率地完成设计工作。希望本文在集成电路设计方法及充分利用计算机资源方面起到抛砖引玉的作用。     

直视芯式单模光纤熔接机微动机构

本文介绍了直视芯式单模光纤熔接机采用柔性铰链式微动机构的原理及构成,其调整精度可达到±0.1μm,使单模光纤熔接机的连接损耗大大降低。另外,还对其性能及指标与日本产品进行了比较。     

小尺度封闭空间可听化技术研究

综述了小尺度封闭空间可听化技术的最新进展,对该技术中的关键问题－－低频声传递函数的求解方法作了分析和比较。     

光纤工业控制网的研究

本文介绍了电路交换和分组交换相结合的新型光纤工业控制环网的设计与研究,着重考虑了环网的拓扑结构、体系结构、ＭＡＣ协议、帧结构和混合环路控制。     

大功率半导体激光束变发散角整形系统设计方法

在研究了大功率半导体激光器(HPLD)光束特性的基础上,提出了实现大功率半导体激光束变发散角的设计方法。针对线源像散激光光源设计了由两个垂直放置的平凸柱透镜组成的可变激光束发散角的整形系统。在满足光束发散角要求的前提下,通过离焦使其出射光束的发散角在一定范围内连续改变。建立了两个柱透镜移动量与光束发散角关系的数学模型。利用商用光学软件对整形系统进行了模拟,结果表明,光束发散角被压缩在一定范围内连续改变,从而可实现对不同范围物体照明。     

Hydrogen Selective NH2‐MIL‐53(Al) MOF Membranes with High Permeability

Hydrogen‐based energy is a promising renewable and clean resource. Thus, hydrogen selective microporous membranes with high performance and high stability are demanded. Novel NH₂‐MIL‐53(Al) membranes are evaluated for hydrogen separation for this goal. Continuous NH₂‐MIL‐53(Al) membranes have been prepared successfully on macroporous glass frit discs assisted with colloidal seeds. The gas sorption ability of NH₂‐MIL‐53(Al) materials is studied by gas adsorption measurement. The isosteric heats of adsorption in a sequence of CO₂ > N₂ > CH₄ ≈ H₂ indicates different interactions between NH₂‐MIL‐53(Al) framework and these gases. As‐prepared membranes are measured by single and binary gas permeation at different temperatures. The results of singe gas permeation show a decreasing permeance in an order of H₂ > CH₄ > N₂ > CO₂, suggesting that the diffusion and adsorption properties make significant contributions in the gas permeation through the membrane. In binary gas permeation, the NH₂‐MIL‐53(Al) membrane shows high selectivity for H₂ with separation factors of 20.7, 23.9 and 30.9 at room temperature (288 K) for H₂ over CH₄, N₂ and CO₂, respectively. In comparison to single gas permeation, a slightly higher separation factor is obtained due to the competitive adsorption effect between the gases in the porous MOF membrane. Additionally, the NH₂‐MIL‐53(Al) membrane exhibits very high permeance for H₂ in the mixtures separation (above 1.5 × 10^?6 mol m^?2 s^?1 Pa^?1) due to its large cavity, resulting in a very high separation power. The details of the temperature effect on the permeances of H₂ over other gases are investigated from 288 to 353 K. The supported NH₂‐MIL‐53(Al) membranes with high hydrogen separation power possess high stability, resistance to cracking, temperature cycling and show high reproducibility, necessary for the potential application to hydrogen recycling.     

Optimal provisioning for virtual network request in cloud-based data centers

Today applications and services are migrating to a cloud-computing-based paradigm in which the users access the applications and services hosted in data centers, by using thin-clients on the user terminal device. These applications/services are typically hosted and run on virtual machines in interconnected data centers. Different applications from the same user may need to access and change shared data or information. Thus, we may abstract the applications from same user as a virtual network (VN). For better performance and efficiency, it is critical that the VN request be accommodated with optimal provisioning under the current resource state of data centers. In this paper, for addressing the issue of how to design an optimal provisioning scheme for the VN request such that the total revenue of is maximized, we first develop a framework for the optimal provisioning of VN request by using mixed integer programming. Since the optimal provisioning problem is NP-hard, we also propose a genetic algorithm?Cbased heuristic algorithm for addressing the problem of optimal provisioning for VN with unsplittable flow and optimal provisioning for VN with splittable flow problems. We demonstrate the effectiveness of our approach in improving the total revenue by conducting extensive simulations on different networks.     

基于云计算的视频监控和资源整合优化系统

视频监控系统在日常生活中担当着越来越重要的作用,将云计算技术应用于视频监控系统中,以此构建了基于云计算的视频监控和资源整合优化系统;然后,改进了视频监控中的一个重要的算法—动态目标检测算法,以提高视频监控的准确性;最后,研究了如何对于云计算平台中的服务器资源进行整合优化,并对所实现的系统进行了测试,结果表明,该系统可以提高视频监控的准确性和服务器的响应时间.     

熔石英玻璃激光损伤的三维应力场研究

为了研究CO₂激光损伤后熔石英玻璃内部的三维应力场分布,采用脉冲CO₂激光与熔石英玻璃相互作用的有限元数值模型,计算了脉冲激光停止时熔石英玻璃内部的温度分布,并研究了材料冷却后的内部三维应力分布和表面初始损伤形貌,计算结果与实验结果吻合。以该模型为基础,详细分析了径向和环向应力的三维分布,结果表明,在损伤凹坑附近,径向应力表现为压应力,且在凹坑底部附近取得最大值后,径向应力沿深度方向逐渐转化为拉应力;损伤凹坑附近的环向应力与径向应力相似,均表现为压应力,但压应力沿径向逐渐转化为拉应力,不同深度处的环向应力沿轴向增至最大后逐渐减小。另外,脉冲激光能量的增大导致径向应力与环向应力及其影响范围均有明显增加。研究结果有助于分析激光损伤熔石英玻璃内部的三维应力场,为CO₂激光修复工艺的改进提供了理论依据。     

Asymmetric Tunable Photonic Bandgaps in Self‐Organized 3D Nanostructure of Polymer‐Stabilized Blue Phase I Modulated by Voltage Polarity

Electrically responsive photonic crystals represent one of the most promising intelligent materials for technological applications in optoelectronics. In this research, a polymer‐stabilized blue phase (PSBP) I film with the self‐organized 3D nanostructure is fabricated, and an electrically tunable photonic bandgap (PBG) is achieved. Interestingly, the large‐scale shift of the PBG covering the entire visible spectrum is found to be asymmetric and can be modulated by the polarity and magnitude of bias voltage. Moreover, to demonstrate the usability in optical devices, blue phase lasers are developed by doping the PSBP material with fluorescent dyes. And mirrorless lasing emission with electrically tunable wavelength is observed. This self‐assembled soft material is prospective to produce large‐scale electrically responsive photonic crystals in facile fabrication process and has enormous potential applications in intelligent optoelectronic devices, such as 3D tunable lasers, reflective full‐color displays, or photonic integrated circuits.