A versatile signal flow graph realization of a general transfer function by using CDBA

A general synthesis procedure is given for a versatile signal flow graph realization of a general transfer function by using current differencing buffered amplifier (CDBA). The proposed configuration uses n+1 CDBAs, n capacitors and at most 2n+4 resistors. This number of resistors can be reduced to n+1 for special cases. The circuit is eligible to obtain a variety of transfer characteristics with the same common denominator polynomial, and it is easily converted to different modes of operations. It is straightforward to find the values of the passive elements from the coefficients of the transfer function to be realized. Simulations results are obtained by using commercially available active component AD844 and CMOS technology as well. All of these make the proposed circuit attractive.     

MC-CDMA系统中基于DFT的信道估计改进算法研究

LS信道估计算法运算量小,实现简单,但估计值对噪声影响敏感,算法精度低。为降低噪声对精度的影响,文章提出一种新的基于DFT的LS信道估计改进算法。该算法利用并行PN序列信号特性,通过时延点信息获取算法得到多径信道的时延点信息,并在改进的信道估计算法中利用此信息,最大程度地抑制噪声。仿真结果表明,与现有的基于DFT的LS改进算法相比,本算法可进一步提高估计精度,在低信噪比条件下性能更好。     

Coexisting with the dynamic PU,the effect of PU‐returns on a secondary network

Coexisting with a dynamic primary user network is a challenge in cognitive radio networks, since the rate at which primary user reoccupies the spectrum is high. Therefore, it is important to investigate deeply the effect of primary traffic dynamics on secondary network performance metrics. To do that, interference due to both sensing error and primary user re‐occupancy must be formulated and considered in throughput and collision probability. Besides them, secondary packet retransmissions due to such interference should be considered in metrics such as average energy consumption and average packet delay. In this study, we formulate the mentioned secondary network metrics regarding to such kinds of interference and secondary packet retransmission. Numerical results along with discussions are given to clarify derived expressions. Simulations are also performed to justify the theoretical results, and optimum operating point for secondary network settings is derived by genetic algorithm.     

The impact of synchronization on the performance of FDL buffers

Circumventing the speed bottleneck of electronic switching, novel switching approaches like optical burst switching (OBS) and optical packet switching (OPS) handle the switching of bursts (or packets) in backbone nodes optically, and include a set of fiber delay lines (FDLs) for optical buffering. While previous work acknowledges the performance difference between optical FDL buffers and electronic RAM buffers, the important role of synchronization herein has received little attention to date.     

电子束曝光UV3正性抗蚀剂的工艺研究

为了在体硅CMOSFinFET中用等离子体腐蚀精细凹槽图形，研究了将电子束直写曝光用于原为深紫外光学曝光的UV3正性抗蚀剂的工艺技术；详细分析了包括膜厚、曝光能量、曝光剂量、显影时间、设计尺寸和衬底材料等在内的各类工艺参数与实际曝光图形效果的关系；特别指出了曝光过程中特有的延迟效应及解决办法。采用最终的优化工艺条件，得到了合适的图形效果。     

0.18μm CMOS工艺条件下的信号完整性分析

通过模拟分析了0 18μmCMOS工艺条件下的信号完整性问题.在进行串扰延迟和噪声分析中发现了一些规律,这些规律对以后的设计有一定的指导意义.     

自适应奇异值分解瞬变信号检测研究

该文介绍了奇异值分解检测信号的原理,研究了井下电磁脉冲数据传输中接收到的瞬变信号和噪声的奇异值分布特性,提出了相邻奇异值增量的概念,并根据瞬变信号和噪声相邻奇异值增量的不同,区分信号与噪声。在此基础上,提出了自适应选择主奇异值个数的奇异值分解检测瞬变信号的方法,并给出该方法检测瞬变信号的具体流程。仿真结果表明,与传统奇异值分解相比,该方法检测微弱瞬变信号更准确。     

无线控制的负延时存储测试方法

针对在恶劣环境下冲击波场超压测试传统方法中布线难、干扰大、无法实时监测和及时获取数据等问题,提出了一种无线控制的负延时存储测试方法。存储测试装置由传感器、模拟适配调理电路、A/D变换器、存储器、控制电路、接口、电池组成,由单片机与CPLD共同控制两片NAND结构闪存实现高速完整存储。Zigbee无线传感器网络技术用于对整个测试系统的触发、采集和数据传输等操作的控制。实验表明:这种新型测试方法具有可无线遥控、微功耗、抗高冲击、抗干扰、工作稳定可靠等特点,适于恶劣环境下数据记录和传输。     

延时控制差异并联算法与自适应加权融合算法

为提高延时控制系统现有决策算法的精度,提出了基于遗传算法的差异并联决策算法,利用遗传算法对各个延时电路的决策增量进行优化求解;为改善系统决策算法的鲁棒性,提出一种自适应加权融合算法,在对实测数据进行分析的基础上确定合理的权值分配策略。利用数值算例对精度、可靠度、鲁棒性和实时性的对比表明:与原有算法相比,所提两种算法具有更优的综合性能,其中自适应加权融合算法性能较为均衡,而差异并联算法具有较强的抑制异常测量值能力,适用于对鲁棒性要求较高的场合。     

存在反馈延迟时V-BLAST系统的功率分配算法

针对信道反馈有延迟条件下的垂直贝尔实验室分层空时(Vertical Bell Laboratories Layered Space Time,V-BLAST)系统,提出基于最小均方误差检测(Minimize Mean Square Error,MMSE)的自适应功率分配算法.通过系统建模和性能分析,推导出系统瞬时信干噪比的条件概率密度函数,并得到V-BLAST系统的平均BER表达式.发 送端在总功率约束条件下,以瞬时BER为优化目标,利用拉格朗日极值法求解自适应功率分配矩阵.仿真结果表明,在信道反馈有延迟时,与等功率分配相比,采用所提算法可显著改善系统的BER性能.