Lubricant‐Infused Anisotropic Porous Surface Design of Reduced Graphene Oxide Toward Electrically Driven Smart Control of Conductive Droplets' Motion

The study of Nepenthes pitcher plants‐bioinspired anisotropic slippery liquid‐infused porous surfaces (SLIPS) is currently in its infancy. The factors that influence their anisotropic self‐cleaning and electric response of a drop's motion and the mechanism have not been fully elucidated. In order to address these problems, two new types of anisotropic slippery surfaces have been designed by using directional, porous, conductive reduced graphene oxide (rGO) films, and different lubricating fluids (conductive and nonconductive), which are used to study the influencing factors and the mechanism of anisotropic self‐cleaning and electric‐responsive control of a drop's motion. The results demonstrate the anisotropic self‐cleaning property of these two types of SLIPS is closely related to the interaction between liquid drops, lubricating fluids and dirt, and the conductive lubricating fluids filling the rGO porous film can reduce the response voltage of the electrically driven reversible control of a drop's slide. The uniqueness of this research lies in the use of two different lubricating fluids and graphene materials to prepare anisotropic SLIPS, identify the key factors to achieve an electrically driven system. These studies are essential for advancing the application of electronically responsive SLIPS in the fields of liquid directional transportation, microfluidics, microchips, and other related research.     

适于视频应用的高数据传输率集成CMOS收发机

这篇文章给出了一个5GHz CMOS射频收发机的设计方案。此设计采用0.18微米射频CMOS加工工艺,集合了最新IEEE802.11n的特性例如多输入多输出技术的专利协议以及其他无线技术,可提供应用在家庭环境中的实时高清电视数据的无线高速传输。设计频率涵盖了从4.9GHz到5.9GHz的ISM频带,每个射频信道的频宽为20MHz。收发机采用了直接上变频发射器和低中频接收器的结构。在没有片上校准的情况下,设计采用双正交直接上变频混频器,得到了超过35dB的镜像抑制。测试结果得到6dB接收机噪声系数以及在-3dBm输出功率时得到发射机EVM结果优于33dB。     

天线隔离度的频率依赖特性

明确地指出了在计算2个不同频系统的天线隔离度时,天线的功率效率和方向图是随频率变化的,一些情况下是需要使用天线在失配区特性的;详细地阐述了一种估算单频段垂直极化偶极子阵列结构的基站天线方向图参数随频率变化的方法;通过计算电磁学仿真对该方法进行了验证;实际测量实验也表明隔离度和天线频率特性是密切相关的。     

InP基光电探测器材料的MOCVD锌扩散

锌(Zn)扩散是制作InP基光电探测器(PD)的重要工艺过程.分析了锌扩散的机制,利用金属有机化学气相沉积(MOCVD)设备对InP基PD及雪崩光电探测器(APD)材料进行了锌扩散,由于MOCVD设备具有精确的温度控制系统,所以该扩散工艺具有简单、均匀性好、重复性好的优点.对于扩散后的样品,采用电化学C-V方法和扫描电子显微镜(SEM)等测试分析手段,研究了退火、扩散温度、扩散源体积流量和反应室压力等主要工艺参数对InP材料扩散速率和载流子浓度的影响,并将该锌扩散工艺应用于InP基光电探测器和雪崩光电探测器的器件制作中,得到了优异的器件性能结果.     

雷达/红外复合导引头信息融合算法

毫米波雷达/ 红外成像复合制导已成为当前多模复合制导技术的研究热点。从毫米波雷达/ 红外成像复合导引头系统的特点及其工程应用出发,建立了一种基于联邦滤波(FF)的分布式雷达/ 红外复合导引头信息融合算法。首先,针对扩展卡尔曼滤波存在线性化误差以及雷达测量噪声非高斯的特点,采用粒子滤波算法(PF)设计雷达子滤波器;针对红外传感器不能测量目标距离的特点,采用伪线性卡尔曼滤波算法(PLKF)设计红外子滤波器。然后通过主滤波器进行信息融合,并对两个子滤波器进行信息分配和重置。仿真结果表明,该信息融合算法能够有效地提高雷达/红外复合导引头系统的目标跟踪精度及系统的稳定性。     

Distributed key management scheme for peer‐to‐peer live streaming services

Live media streaming over peer‐to‐peer (P2P) network structures is commonplace nowadays. However, with the large number of users in a typical P2P system, it is impractical to use the central server to process the key information update requests of all the users Accordingly, the present study proposes a distributed key management scheme in which the server is only required to transmit the key update information to a limited number of users. To further reduce the load on the server, the update information is distributed using a hop‐by‐hop approach. An effective method is proposed for protecting the key update information as it is propagated through the network. In addition, a technique is presented for ensuring the security of the certificates used in the system It is shown that the distributed key management scheme and authentication procedure ensure an efficient and secure P2P live streaming performance even in the event of high churn rates. Copyright © 2012 John Wiley & Sons, Ltd.     

Ultrabroadband Optical Superchirality in a 3D Stacked‐Patch Plasmonic Metamaterial Designed by Two‐Step Glancing Angle Deposition

Low‐cost and large‐scale fabrication of 3D chiral metamaterials is highly desired for potential applications such as nanophotonics devices and chiral biosensors. One of the promising fabrication methods is to use glancing angle deposition (GLAD) of metal on self‐assembled dielectric microsphere array. However, structural handedness varies locally due to long‐range disorder of the array and therefore large‐scale realization of the same handedness is impossible. Here, using symmetry considerations a two‐step GLAD process is proposed to eliminate this longstanding problem. In the proposed scheme, the unavoidable long‐range disorder gives rise to microscale domains of the same handedness but of slightly different structural geometries and ultimately contributes to a broad‐band response. Experimentally, a record‐breaking superchiral response of circular dichroism signal of ≈11° is demonstrated and an average polarization rotation angle of 27° in the visible region on ≈1 cm² sample is observed. Computer‐aided geometric reconstruction with experimental parameters unambiguously reveal the presence of strong structural anisotropy and chirality in the prepared stacked‐patch plasmonic chiral metamaterial; microscopic spectral analyses combined with full‐wave electromagnetic simulations coherently provide deeper insights into the measured circular dichroism and optical activity. The observed chiroptical response can also be flexibly controlled by adjusting the deposition parameters for various potential applications.     

MIMO satellite communication with accelerated dual paths asynchronous design

This paper presents a novel asynchronous design approach for multiple input multiple output (MIMO) satellite communication (SatCom) systems. One of the main challenges for MIMO SatCom systems is that these are prone to transient faults that typically are attributable to radiation hazards. Hence, instead of using conventional synchronous circuits, we conceive our design using asynchronous circuits since it inherently has a high tolerance to transient fault. Additionally, we adopt accelerated dual paths (ADP) design into our system. By carefully arranging the data flow between the two paths, the ADP design approach can help to further accelerate the asynchronous system and increase the reliability of the system by circumventing transient faults induced delay, as well as tolerating latch-ups and other permanent faults. The numerical results show that this design approach provides promising results. For example, the proposed design can decrease the delay overhead of the entire system from 43.5 to 19.8 % at the fault rate of 400/clock cycle.     

A Triode Device with a Gate Controllable Schottky Barrier: Germanium Nanowire Transistors and Their Applications

Electrical contacts often dominate charge transport properties at the nanoscale because of considerable differences in nanoelectronic device interfaces arising from unique geometric and electrostatic features. Transistors with a tunable Schottky barrier between the metal and semiconductor interface might simplify circuit design. Here, germanium nanowire (Ge NW) transistors with Cu₃Ge as source/drain contacts formed by both buffered oxide etching treatments and rapid thermal annealing are reported. The transistors based on this Cu₃Ge/Ge/Cu₃Ge heterostructure show ambipolar transistor behavior with a large on/off current ratio of more than 10⁵ and 10³ for the hole and electron regimes at room temperature, respectively. Investigations of temperature‐dependent transport properties and low‐frequency current fluctuations reveal that the tunable effective Schottky barriers of the Ge NW transistors accounted for the ambipolar behaviors. It is further shown that this ambipolarity can be used to realize binary‐signal and data‐storage functions, which greatly simplify circuit design compared with conventional technologies.