无线Ad hoc网络中基于节点停留概率的路径压缩

该文提出一种基于节点停留概率的路径压缩算法NSP-PCA。通过计算造成路径变化的节点相对于另一节点传输区域的停留概率,动态预测压缩路径的稳定性,并以此为依据决定压缩操作的优先级。仿真表明,NSP-PCA能有效控制短暂缩减和多次缩减等非正常压缩,在端到端时延,路由开销和包发送率方面均优于SHORT和PCA压缩算法。     

无障碍可调节腋支撑行走助力器的设计研究

针对老年人和下肢残疾者出行问题,设计了一种无障碍可调节腋支撑的行走助力器,该行走助力器不仅具有新型的腋支撑机构,而且在行走腿前部减少了阻挡构件,延长了使用者的步距,降低了使用者视觉上的障碍恐惧心理。     

无线城市：从热点服务到全面应用

目前大部分发达国家和地区均开展了无线城市的建设,但由于普遍缺乏较为成功的商业模式,业务应用较为单一,因此效果不够理想。我国无线城市的运营应基于全球无线城市的运营经验,必须把握几个关键点,即获取政府支持、创新商业模式、打造统一平台、丰富业务应用、强化网络支撑等。     

超大型网络圆锥曲线密码管理解决方案

二进制域上圆锥曲线密码是一种新型的公钥密码系统,在随机选取曲线参数,明文嵌入方面较椭圆曲线有优势.针对在超大型网络系统中,各种密码管理混乱、安全隐患严重的问题,利用圆锥曲线的优点,提出了一种安全的密码管理解决方案,该方案利用圆锥曲线/AES混合加密的方式保证密钥传输中的机密性、完整性、不可否认性.该方案对于强化超大型网络系统的运维管理有一定的实际意义.     

Unexpected Sole Enol‐Form Emission of 2‐(2′‐Hydroxyphenyl)oxazoles for Highly Efficient Deep‐Blue‐Emitting Organic Electroluminescent Devices

Considerable efforts have been devoted to the development of highly efficient blue light‐emitting materials. However, deep‐blue fluorescence materials that can satisfy the Commission Internationale de l'Eclairage (CIE) coordinates of (0.14, 0.08) of the National Television System Committee (NTSC) standard blue and, moreover, possess a high external quantum efficiency (EQE) over 5%, remain scarce. Here, the unusual luminescence properties of triphenylamine‐bearing 2‐(2′‐hydroxyphenyl)oxazoles ( 3a–3c ) and their applications in organic light‐emitting diodes (OLEDs) are reported as highly efficient deep‐blue emitters. The 3a ‐based device exhibits a high spectral stability and an excellent color purity with a narrow full‐width at half‐maximum of 53 nm and the CIE coordinates of (0.15, 0.08), which is very close to the NTSC standard blue. The exciton utilization of the device closes to 100%, exceeding the theoretical limit of 25% in conventional fluorescent OLEDs. Experimental data and theoretical calculations demonstrate that 3a possesses a highly hybridized local and charge‐transfer excited state character. In OLEDs, 3a exhibits a maximum luminance of 9054 cd m^?2 and an EQE up to 7.1%, which is the first example of highly efficient blue OLEDs based on the sole enol‐form emission of 2‐(2′‐hydroxyphenyl)azoles.     

Influence of Substrate Temperature on Structural Properties and Deposition Rate of AlN Thin Film Deposited by Reactive Magnetron Sputtering

Aluminum nitride (AlN) thin films with c-axis preferred orientation have been prepared by reactive direct-current (DC) magnetron sputtering. The degree of preferred crystal orientation, the cross-sectional structure, and the surface morphology of AlN thin films grown on Si (100) substrates at various substrate temperatures from 60°C to 520°C have been investigated by x-ray diffraction, scanning electron microscopy, and atomic force microscopy. Results show that the substrate temperature has a significant effect on the structural properties, such as the degree of c-axis preferred orientation, the full-width at half-maximum (FWHM) of the rocking curve, the surface morphology, and the cross-sectional structure as well as the deposition rate of the AlN thin films. The optimal substrate temperature is 430°C, with corresponding root-mean-square surface roughness (R _rms) of 1.97?nm, FWHM of AlN (002) diffraction of 2.259°, and deposition rate of 20.86?nm/min. The mechanisms behind these phenomena are discussed. Finally, film bulk acoustic resonators based on AlN films were fabricated; the corresponding typical electromechanical coupling coefficient (k _t ² ) is 5.1% with series and parallel frequencies of 2.37?GHz and 2.42?GHz, respectively.     

Cu5Zn8 Growth Reversion in Cu/Sn-8Zn-3Bi/Cu During Discontinuous Electromigration

A Cu/Sn-8Zn-3Bi/Cu structure was used to investigate the intermetallic compound (IMC) growth behavior during discontinuous electromigration under current density of 10⁴?A/cm² at 70°C. Cu₅Zn₈ IMC formed at both the anode and the cathode interfaces, and the thickness increased with the stressing time. With prolonging the current stressing time, a bulged Cu₅Zn₈ layer was squeezed out between the former Cu₅Zn₈ layer and Cu substrate in the samples to relax the excess compressive stress. Additionally, due to the back stress gradient built up by the Sn diffusion, the Zn atomic flux reacted with Cu to form Cu₅Zn₈ at the cathode side when the power was turned off. Finally, the total IMC thickness of the anode and the cathode under discontinuous current stressing showed a ??reversion?? in the 69?h and 310?h samples.     

基于STC12C2052的人民币识别控制系统的设计

设计研究人民币纸币识别控制系统中的主要模块,如图像采集、控制模块。在硬件部分,选用STC12C2052作为控制系统的芯片,选用MVC1000M作为图像的采集器件;在软件部分,在红外和紫外光源的作用下通过高清摄像头拾取图影信息,通过与数据库中的真版人民币特征的数据比对来判断真伪,选取预处理之后的纸币图像的尺寸特征用模糊逻辑推理方法识别图像的面值,提取矩作为特征。通过实验证明该控制系统的有效性和可行性。     

汽车自动巡航系统PID控制策略的研究

文章介绍汽车自动巡航控制系统的结构组成和工作原理,选择基于Atmega 8单片机的PID控制策略实现车辆的稳定行驶及加速、减速的控制过程.本系统能有效地减轻长途驾驶中驾驶员的工作强度,提高舒适性,并减少燃料消耗,利于环保.     

安全协议DoS攻击的形式化分析方法研究

针对形式化方法对安全协议DoS攻击分析的不足之处,提出了一种基于串空间模型的扩展形式化方法。利用扩展后的形式化方法,对IEEE802．11i四步握手协议进行了DoS攻击分析,发现其的确存在DoS攻击漏洞。通过分析,提出一种可以改善DoS攻击的方法,并通过了扩展形式化方法对于判断安全协议DoS攻击分析的测试规则。最后,根据扩展形式化方法对改进后的四步握手协议进行证明,得出改进后协议可以通过两类DoS测试规则运行至结束。