一种基于遗传算法的自适应参数型多径时延估计

基于四阶累积量的自适应参数型多径时延估计（FOC—APMTDE）算法只能直接估计整数倍采样间隔的时延,为了克服此缺点,引入遗传算法进行时延估计的寻优,保留了FOC—APMTDE算法良好的抑制相关或非相关高斯噪声的性能,在低信噪比的情况下可以准确地直接估计非整数倍采样间隔的时延。计算机仿真试验验证了新方法的有效性。     

PCB插件孔散热焊盘设计对上锡影响

0引言 插件孔:即PCB通孔直插式元件与电路板连接的金属化孔(PTH),常规插件孔孔径公差要求为±0.075 mm,此类插件孔的孔需要焊接.也有一些要求为压接器件的插件孔,此类插件孔对孔径精度要求高,作用是直接将原件的引脚插进去,通过引脚与孔壁的接触导通电流,此类孔不需要焊接,常规压接插件孔孔径公差要求为±0.05 m...     

分子组装偶氮苯衍生物Langmuir-Blodgett膜热释电性能的研究

利用Langmuir-Blodgett方法对偶氮苯衍生物进行了极性分子组装.测得了静态和动态热释电活性和频率响应.30个单分子层LB膜的热释电系数在室温下达到7μCm~(-2)K~(-1).利用FTIR线性二向色性光谱研究了分子轴和几个主要的极性极团的跃迁矩方向和分子在LB膜中的结构.讨论了这种极化取向对热释电活性的影响.     

基于G.723算法的数字式录音机的研究

介绍了一款数字式录音机,其硬件系统的核心是数字信号处理器（ＤＳＰ）ＡＤＳＰ－２１８６和闪烁存储器ＦＬＡＳＨ ＭＥＭＯ ２８Ｆ３２０Ｊ５,使用的编码算法为国际电信联盟（ＩＴＵ）的Ｇ．７２３算法。     

激光喷丸强化ZK60变形镁合金的疲劳性能研究

为研究激光喷丸对高强度变形镁合金ZK60疲劳性能的影响机理,使之适应交变应力结构件的工作需要,进行了激光喷丸强化表面改性和拉伸疲劳性能实验。实验结果表明,在激光喷丸强化区域获得有益的残余压应力,产生硬化效应,表面塑性变形的微小区域,变形轮廓曲线波动范围较基体小,增加喷丸次数可增强激光喷丸的强化效应。经3次激光喷丸后,中心孔疲劳试样的平均疲劳寿命由未喷丸试样的78023次提高到125641次,寿命增益达61%。从断口来看,激光喷丸强化主要是改变了裂纹源萌生位置,延缓了裂纹扩展速率,对瞬断区无明显影响。激光喷丸强化为镁合金的抗疲劳制造提供了新的途径。     

等规模虚拟网络映射问题的反向和双向灌水方法

Previous Virtual Network (VN) embedding researches mostly focus on developing heuristic algo-rithms to enhance the efficiency of a physical re-source. However, in the equal-scale condition, where the scale of a VN is similar to that of a substrate net-work, the number of successfully mapped VNs de-creases sharply since bottlenecks form easily in the substrate network and disturb the embedding process. In this paper, reversed and bidirectional irrigation methods are proposed for the equal-scale and all-scale conditions. The two proposed methods can be com-bined with most of the existing heuristic algorithms and map a relatively large number of VNs by reducing the potential substrate bottlenecks. The simulation re-sults show that the reversed irrigation method almost doubles the successfully mapped Revenue than the traditional one in the equal-scale condition. Mean-while, the bidirectional irrigation method achieves the synthetically best performance in almost all scale con-ditions.     

A Facile Microwave Avenue to Electrochemiluminescent Two‐Color Graphene Quantum Dots

With the assistance of microwave irradiation, greenish‐yellow luminescent graphene quantum dots (gGQDs) with a quantum yield (QY) up to 11.7% are successfully prepared via cleaving graphene oxide (GO) under acid conditions. The cleaving and reduction processes are accomplished simultaneously using microwave treatment without additional reducing agent. When the gGQDs are further reduced with NaBH₄, bright blue luminescent graphene quantum dots (bGQDs) are obtained with a QY as high as 22.9%. Both GQDs show well‐known excitation‐dependent PL behavior, which could be ascribed to the transition from the lowest unoccupied molecular orbital (LUMO) to the highest occupied molecular orbital (HOMO) with a carbene‐like triplet ground state. Electrochemiluminescence (ECL) is observed from the graphene quantum dots for the first time, suggesting promising applications in ECL biosensing and imaging. The ECL mechanism is investigated in detail. Furthermore, a novel sensor for Cd²⁺ is proposed based on Cd²⁺ induced ECL quenching with cysteine (Cys) as the masking agent.     

Power‐efficient resource allocation with QoS guarantees for TDMA fading channels

This paper proposes two power‐efficient resource allocation policies with statistical delay Quality of Service (QoS) guarantees for uplink time‐division multiple access (TDMA) communication links. Specifically, the first policy aims at maximizing the system throughput while fulfilling the delay QoS and average power constraints, and the second policy is devised as an effort to minimize the total average power subject to individual delay QoS constraints. Convex optimization problems associated with the resource allocation policies are formulated based on a cross‐layer framework, where the queue at the data link layer is served by the resource allocation policy. By employing the Lagrangian duality theory and the dual decomposition theory, two subgradient iteration algorithms are developed to obtain the globally optimal solutions. The aforementioned resource allocation policies have been shown to be deterministic functions of delay QoS requirements and channel fading states. Moreover, numerical results are provided to demonstrate the performance of the proposed resource allocation policies. Copyright © 2010 John Wiley & Sons, Ltd.     

BIM技术在旧厂房空间改造中的应用

本文主要对旧厂房改造的意义、BIM技术的背景以及当前旧厂房改造过程中的问题和BIM在旧厂房空间改造过程中的实际应用进行阐述,旨在提高BIM在改造过程中的应用效果.     

基于空时融合隐马尔科夫模型的舰艇编队目标识别方法

基于末制导雷达搜索舰艇编队目标时获得的目标大角域高分辨距离像(HRRP)信息,该文建立了描述单个HRRP样本内向量之间统计关系的各态历经空间隐马尔可夫模型(SHMM)和描述HRRP样本之间统计关系的从左到右时间隐马尔可夫模型(THMM)。与对一类目标全方位角训练数据只建立一个THMM模型的方法相比,该方法充分利用目标的大角域HRRP信息,提高了识别性能。通过对5类舰船目标的仿真和3类民用船只的外场实测数据分析表明该方法的有效性。