Magnetocontrollable Droplet and Bubble Manipulation on a Stable Amphibious Slippery Gel Surface

Smart manipulation of liquid/bubble transport has garnered widespread attention due to its potential applications in many fields. Designing a responsive surface has emerged as an effective strategy for achieving controllable transport of liquids/bubbles. However, it is still challenging to fabricate stable amphibious responsive surfaces that can be used for the smart manipulation of liquid in air and bubbles underwater. Here, amphibious slippery surfaces are fabricated using magnetically responsive soft poly(dimethylsiloxane) doped with iron powder and silicone oil. The slippery gel surface retains its magnetic responsiveness and demonstrates strong affinity for bubbles underwater but shows small and switching resistance forces with the water droplets in air and bubbles underwater, which is the key factor for achieving the controllable transport of liquids/bubbles. On the slippery gel surface, the sliding behaviors of water droplets and bubbles can be reversibly controlled by alternately applying/removing an external magnetic field. Notably, compared with slippery liquid‐infused porous surfaces, the slippery gel surface demonstrates outstanding stability, whether in air or underwater, even after 100 cycles of alternately applying/removing the magnetic field. This surface shows potential applications in gas/liquid microreactors, gas–liquid mixed fluid transportation, bubble/droplet manipulation, etc.     

基于FPGA实现塔康地面信标信号发生器设计

为满足某型飞机塔康设备检测仪器要求,对其提供稳定、可靠、多样的塔康地面信标信号.设计利用Ahera公司的EP4CE6E22C8为控制核心,以DAC813JP为DA转换器,运用DDS基本原理,通过QuartusⅡ软件编写塔康地面信标信号发生器的每个单元模块,最终完成整个设计方案.并进行了Matlab与QuartusⅡ相结合的仿真验证,同时设计连接了外部电路.相较于传统塔康地面信标信号发生器操作简单,便于升级,能够满足检测仪器的各项要求.     

La2O3的掺杂对氧化锌压敏陶瓷电性能的影响

采用传统固相法制备稀土氧化物La2O3掺杂的ZnO压敏陶瓷。采用X线衍射(XRD)、扫描电子显微镜(SEM)和压敏电阻直流参数仪对样品的物相、显微组织及电性能进行分析。结果表明,随着La2O3掺杂量的增加,ZnO压敏陶瓷电位梯度单调递增,非线性系数先增加后减小,而漏电流呈现先减小后增大的变化趋势。综合衡量ZnO压敏电阻的各项性能指标发现,在1 000 ℃烧结温度下,La2O3的质量分数为0.25%时,ZnO压敏电阻的综合性能最好,其电位梯度为532.2 V/mm,非线性系数为41.6,漏电流为3.3 μA。     

An Investigation of Diffusion Barrier Characteristics of an Electroless Co(W,P) Layer to Lead-Free SnBi Solder

Diffusion barrier characteristics for eutectic SnBi solder/electroless Co(W,P) couples were investigated via liquid-state aging at 250°C and solid-state aging at 120°C. At the couple interface, CoSn₃ intermetallic compound (IMC) spallation was observed for the SnBi/amorphous Co(W,P) couple subjected to liquid-state aging. In contrast, no spallation of IMCs was observed for the SnBi/amorphous Co(W,P) couples subjected to solid-state aging. For the SnBi/polycrystalline Co(W,P) couple, a thick IMC layer was observed adjacent to a tungsten-enriched amorphous interfacial layer regardless of aging conditions. IMC formation in all samples indicated that Co(W,P) is essentially a sacrificial barrier to SnBi solder. However, amorphous Co(W,P) might also exhibit stuffed-type barrier behavior due to its relatively high phosphorus (P) content. Analytical results indicated that the P content in Co(W,P) is a crucial factor affecting the structural evolution at the SnBi/electroless Co(W,P) interface.     

Anonymous authentication protocol based on elliptic curve Diffie–Hellman for wireless access networks

Anonymous channel tickets have been proposed as a way to provide user anonymity and to reduce the overhead of re‐authentication for authentication in wireless environments. Chen et al. proposed a secure and efficient protocol, based on a protocol proposed by Yang et al., which is resistant to guessing attacks on networks from which users’ secret keys are easy to obtain. However, their scheme is time‐consuming in the phases of ticket issuing and authentication. Furthermore, a malicious attacker can utilize the expired time, T_exp, to launch a denial of authentication (DoA) attack, which is a type of denial of service attack. Because T_exp is exposed to any user, it would be easy to launch a DoA attack that could make the scheme impractical. To resist against DoAs that the scheme of Chen et al. might suffer, we propose an improved scheme based on elliptic curve cryptography in this paper. Our scheme not only reduces time cost but also enhances security. The basis of the proposed scheme is the elliptic curve discrete logarithm problem. The operations of points of an elliptic curve are faster and use fewer bits to achieve the same level of security. Therefore, our scheme is more suitable for mobile devices, which have limited computing power and storage. Copyright © 2012 John Wiley & Sons, Ltd.     

Efficient Color-theory-based Dynamic Localization for Mobile Wireless Sensor Networks

Location information is critical to mobile wireless sensor networks (WSN) applications. With the help of location information, for example, routing can be performed more efficiently. In this paper, we propose a novel localization approach, Color-theory based Dynamic Localization (CDL), which is based on color theory to exploit localization in mobile WSNs. CDL makes use of the broadcast information, such as locations and RGB values, from all anchors (a small portion of nodes with GPS receivers attached), to help the server to create a location database and assist each sensor node to compute its RGB value. Then, the RGB values of all sensor nodes are sent to the server for localization of the sensor nodes. A unique feature of our color-theory based mechanism is that it can use one color to represent the distances of a sensor node to all anchors. Since CDL is easy to implement and is a centralized approach, it is very suitable for applications that need a centralized server to collect user (sensor) data and monitor user activities, such as community health-care systems and hospital monitoring systems. Evaluation results have shown that for mobile WSNs, the location accuracy of CDL (E-CDL, an enhanced version of CDL) is 40–50% (75–80%) better than that of MCL (Hu, L., & Evans, D. (2004). Localization for mobile sensor networks. In Proceedings of the 10th annual international conference on mobile computing and networking, pp. 45–57). In addition, we have implemented and validated our E-CDL algorithm on the MICAz Mote Developer’s Kit.     

Electrically tunable room-temperature 2/spl pi/ liquid crystal terahertz phase shifter

Tunable phase shift up to 360/spl deg/ at 1 THz is demonstrated using electrically controlled birefringence in a vertically aligned nematic liquid crystal (E7) cell, 1.83 mm in thickness. The driving voltage and corresponding field required for a phase shift of 360/spl deg/ at 1 THz are 100 V and 90.5 V/cm, respectively.     

Finding point correspondence using local similarity and global constraint under insignificant scaling and roll

Establishing point correspondences is an important research topic in computer vision. Proposed is an algorithm using local similarity and global constraint to obtain point correspondence. The point correspondences are obtained by comparing their associated colour codes, which are computed by image gradients, and using spatial relationships among neighbouring feature points. The approach assumes insignificant scaling and roll, and is suitable for real-time applications     

ARM9芯片EP9315驱动TFT-LCD的研究

介绍了EP9315的LCD控制器的数据和控制管脚,并给出了LCD的控制流程和EP9315 LCD控制器的设置规则。参照SHARP公司LQ080V3DG01 TFT LCD的逻辑要求和时序要求设计了驱动电路,设置了各主要LCD寄存器。开发了LQ080V3DG01在嵌入式LINUX下的显示驱动程序,并在LQ080V3DG01上显示了清晰稳定的画面。文中给出EP9315驱动TFT-LCD的一套较佳的解决方案。     

水雷武器安全保险系统可靠性评估探讨

可靠性是水雷武器完成预定作战任务的有力保障,尤其对于水雷武器安全保险系统这种结构、运行模式复杂的子系统,保证其达到可靠性指标尤为重要。评估可靠性的方法是可靠性研究的关键,尝试对其可靠性的评估方法进行了探讨,并结合某型水雷实例作出具体分析。