Quadrature Oscillators with Grounded Capacitors and Resistors Using FDCCIIs

Two current‐mode and/or voltage‐mode quadrature oscillator circuits each using one fully‐differential second‐generation current conveyor (FDCCII), two grounded capacitors, and two (or three) grounded resistors are presented. In the proposed circuits, the current‐mode quadrature signals have the advantage of high‐output impedance. The oscillation conditions and oscillation frequencies are orthogonally (or independently) controllable. The current‐mode and voltage‐mode quadrature signals can be simultaneously obtained from the second proposed circuit. The use of only grounded capacitors and resistors makes the proposed circuits ideal for integrated circuit implementation. Simulation results are also included.     

On minimizing end-to-end delay with optimal traffic partitioning

Multipath transport provides higher usable bandwidth for a session. It has also been shown to provide load balancing and error resilience for end-to-end multimedia sessions. Two key issues in the use of multiple paths are 1) how to minimize the end-to-end delay, which now includes the delay along the paths and the resequencing delay at the receiver, and 2) how to select paths. This paper presents an analytical framework for the optimal partitioning of real-time multimedia traffic that minimizes the total end-to-end delay. Specifically, it formulates optimal traffic partitioning as a constrained optimization problem using deterministic network calculus and derives its closed-form solution. Compared with previous work, the proposed scheme is simpler to implement and enforce. This analysis also greatly simplifies the solution to the path selection problem as compared to previous efforts. Analytical results show that for a given flow and a set of paths, a minimal subset can be chosen to achieve the minimum end-to-end delay with O(N) time, where N is the number of available paths. The selected path set is optimal in the sense that adding any rejected path to the set will only increase the end-to-end delay.     

ZBO(ZnO∶B)靶材烧结机理与特征的研究

用常压烧结方法，在1200℃-1350℃烧结不同含B量的掺硼氧化锌（ZBO）靶材。研究了掺杂量、烧结温度对ZBO靶材微观结构的影响。实验表明，随着烧结温度的增加。ZBO陶瓷的晶粒大小和密度逐渐增大。指出了由于B2O3的挥发，造成ZBO靶材的剩余含B量与掺B量的不符，要获得含定量B的ZBO就必须掺入大约2倍所需量的B2O3。     

Si(111)7×7表面Gd@C82分子的STM研究

用超高真空扫描隧道显微镜(UHV-STM)研究了金属富勒烯分子Gd@C82在Si(111)7×7重构表面的吸附特性和电学特性.STM形貌像显示Gd@C82分子和Si基底之间相互作用较强,Gd@C82分子吸附在Si基底的三种特定的位置上,其中在Si(111)7×7单胞内三个顶戴原子间的吸附位最稳定.扫描隧道谱(STS)的测量显示Gd@C82分子呈现半导体特性.分子表面局域电子态密度(LDOS)在Gd附近受到Gd与碳笼间电子转移的影响,发生显著变化.     

A scalable, power-efficient broadcast algorithm for wireless networks

Scalability and power-efficiency are two of the most important design challenges in wireless ad hoc networks. In this paper, we present a scalable, power-efficient broadcast algorithm for wireless ad hoc networks. We first investigate the trade-off between (i) reaching more nodes in a single hop using higher transmission power and (ii) reaching fewer nodes using lower transmission power and relaying messages through multiple hops. Our analysis indicates that multi-hop broadcast is more power-efficient if α ≥ 2.2, where α is the path loss exponent in the power consumption model P(r,α) = c₀⋅ r^α+c₁. Based on the analysis, we then propose Broadcast over Local Spanning Subgraph (BLSS). In BLSS, an underlying topology is first constructed by a localized topology control algorithm, Fault-Tolerant Local Spanning Subgraph (FLSS). FLSS can preserve k-connectivity of the network, where the value of k determines the degree of fault tolerance. Broadcast messages are then simply relayed through the derived topology in a constrained flooding fashion. BLSS is fully localized, scalable, power-efficient, and fault-tolerant. Simulation results show that the performance of BLSS is comparable to that of centralized algorithms. Ning Li received the B.E. and M.E. degrees from Department of Automation, Tsinghua University, Beijing, PR China, in 1998 and 1999, respectively, and the M.S. degree in Computer Engineering from The Ohio State University, Columbus, OH, in 2001 and the Ph.D. degree in Computer Science from University of Illinois at Urbana-Champaign, Urbana, IL. His research interests include design and analysis of wireless mobile ad hoc networks and sensor networks, large-scale network simulation and emulation, and distributed and mobile computing. Jennifer C. Hou received her Ph.D. from The University of Michigan, Ann Arbor, MI in 1993. She is currently a professor in the Department of Computer Science at University of Illinois at Urbana-Champaign, Urbana, IL. Dr. Hou has been supervising several federally and industry funded projects in the areas of network modeling and simualtion, network measurement and diagnostics, enabling communication software for assisted living, and both the theoretical and protocol design aspects of wireless sensor networks. She has published (with her former advisor, students, and colleagues) over 125 papers and book chapters in archived journals and peer-reviewed conferences, and released a truly extensible, reusable, component-based, compositional network simulation and emulation package, J-Sim. She has also served on the TPC of several major networking, real-time, and distributed systems conferences/symposiums, such as IEEE INFOCOM, IEEE ICNP, IEEE ICDCS, IEEE RTSS, IEEE ICC, IEEE Globecome, ACM Mobicom, and ACM Sigmetrics. She is the Technical Program Co-chair of 27th IEEE INFOCOM 2008, First International Wireless Internet Conference 2005, ACM 3rd Information Processing in Sensor Networks (IPSN 2004) and IEEE Real-time Technology and Application Symposium (RTAS 2000). She is severing on the editorial board of IEEE Trans. on Wireless Communications, IEEE Trans. on Parallel and Distributed Systems, IEEE Wireless Communication Magazine, ACM/Kluwer Wireless Networks, Kluwer Computer Networks, and ACM Trans. on Sensor Networks. Dr. Hou was a recipient of an ACM Recognition of Service Award in 2004, a Lumley Research Award from The Ohio State University in 2001, a NSF CAREER award in 1996–2000 and a Women in Science Intiative Award from The University of Wisconsin—Madison in 1993–1995.     

校园CPU卡密钥管理系统的设计与实现

文章研究了密钥管理系统在校园一卡通系统中的应用模式。首先以CPU卡技术和密码算法技术为基础,提出了一卡通系统的密钥管理系统的解决方案;然后针对系统的实现,描述了密钥分散的设计和实现过程;最后对系统中使用的算法进行了描述。密钥管理系统保证了高强度的校园一卡通系统的安全性。     

Application of Stereology on Neodymium-Doped Yttrium Aluminum Garnet (Nd∶YAG) Transparent Ceramics

Neodymium-doped yttriumaluminumgarnet (Nd∶YAG) transparent polycrystalline ceramics have theadvantages of good chemical stability ,high doped-ionconcentration ,excellent optical performance ,and hightemperature stability[1 ,2].Toi mprove the transmittanceof Nd∶YAGceramics ,most of the researches focus onthe precursor powders synthesis and on ceramic sinter-ing. However , quantification of ceramic microstruc-ture can aid in developing useful correlation betweenprocessing conditions andthe …     

Automated passive filter synthesis using a novel tree representation and genetic programming

This paper proposes a novel tree representation which is suitable for the analysis of RLC (i.e., resistor, inductor, and capacitor) circuits. Genetic programming (GP) based on the tree representation is applied to passive filter synthesis problems. The GP is optimized and then incorporated into an algorithm which can automatically find parsimonious solutions without predetermining the number of the required circuit components. The experimental results show the proposed method is efficient in three aspects. First, the GP-evolved circuits are more parsimonious than those resulting from traditional design methods in many cases. Second, the proposed method is faster than previous work and can effectively generate parsimonious filters of very high order where conventional methods fail. Third, when the component values are restricted to a set of preferred values, the GP method can generate compliant solutions by means of novel circuit topology.     

渐近波形估计技术结合矩量法分析圆形振子天线阵列阻抗

应用渐近波估计（AWE）技术结合矩量法（MOM）分析了八元圆形振子天线阵列的阻抗特性。采用矩量法求解天线阵列的电场积分方程，得到某一频率的电流分布和导纳，通过Pade逼近获得任意频率的导纳，从而得到天线阵列的频带特性。计算结果表明AWE能逼近MOM计算结果，同时可大大加快计算速度。     

基于小波分析的透平机械振动故障特征定量识别研究

通过对透平机械振动信号的连续小波变换，利用小波滤波器良好的时频特性,研究了振动故障信号的统计特征．在信号的特征提取中引入“灰度矩”，并把一阶矩作为定量指标．对8种典型振动故障信号的初步研究表明，这种方法能够简单有效地提取信号的特征，区分振动故障．