速度拖引干扰和杂波背景下脉冲多普勒雷达目标跟踪算法

针对在速度拖引干扰和杂波背景下脉冲多普勒(PD)雷达无法精确跟踪目标的问题,该文提出基于双模型(DM)和幅度信息(AI)的目标跟踪算法。分别建立基于位置、幅度量测的跟踪模型和基于位置、速度、幅度量测的跟踪模型。两个模型均使用基于幅度信息的概率数据互联(AI-PDA)尽可能地降低杂波的影响,然后使用常规方法进行滤波估计。若没有速度拖引干扰,则两个模型估计具有位置和速度上的相关性;若存在干扰,由于速度量测是虚假的,则两个模型估计不具有相关性。据此,进行卡方检验(chi-square test),分析影响检验结果的因素,进而确定最终的估计结果。仿真验证了该算法的有效性。     

�Ե�ǰ�Ĵ���Ȼ���۸�ĸ�����

为筹集天然气工业发展急需的资金,本文提出在天然气价格未全面调整前,对超包干天然气实行议价,随行就市,直接受市场调节。本文对这一办法进行了可行性分析,并列出超产气议价的幅度的计算方法,供决策参考。     

Collective Organization Behaviors of Multi-Cell Systems Induced by Engineered ECM-Cell Mechanical Coupling

Cells in vivo are surrounded by fibrous extracellular matrix (ECM), which can mediate the propagation of active cellular forces through stressed fiber bundles and regulate various biological processes. However, the mechanisms for multi-cellular organization and collective dynamics induced by cell-ECM mechanical couplings, which are crucial for the development of novel ECM-based biomaterial for cell manipulation and biomechanical applications, remain poorly understood. Herein, the authors design an in vitro quasi-3D experimental system and demonstrate a transition between spreading and aggregating in collective organizational behaviors of discrete multi-cellular systems, induced by engineered ECM-cell mechanical coupling, with the observed phenomena and underlying mechanisms differing fundamentally from those of cell monolayers. During the process of collective cell organization, the collagen substrate undergoes reconstruction into a dense fiber network structure, which is correlated with local cellular density and consistent with observed enhanced cells' motility; and the weakening of fiber bundle formation within the hydrogel reduces cells’ movement. Moreover, cells can respond to the curvature and shape of the original cell population and form different aggregation patterns. These results elucidate important physical factors involved in collective cell organization and provide important references for potential applications of biomaterials in new therapies and tissue engineering.     

烟蚜与烟蚜茧峰相互关系研究

研究结果表明，烟蚜茧蜂对烟蚜呈典型的Holling－Ⅱ型功能反应，参数a＝3．698／罩·天．Th＝0．0174天；该蜂对烟蚜生长发育和繁殖的影响因被寄生时蚜虫龄期不同而异，而蜂幼虫的发育不受寄生时蚜虫龄期的影响。当1～2龄蚜虫被寄生时，一般不能发育到成蚜期产蚜：从2龄中期起，蚜虫的生殖力和种群内禀增长率rm随着被寄生蚜虫龄期的增大而上升。由此可见，被寄生时蚜虫虫龄大小对蚜茧蜂寄生效果起着决定性的作用，寄生时蚜虫龄期越大，寄生作用越不明显。     

A novel contention solution strategy based on priority for optical burst switching networks

A fundamental issue in optical burst switching (OBS) networks is to solve the burst contention for the core node. In this paper, a novel priority-based contention solution strategy for OBS networks is proposed. When the contention occurs, the burst priority is considered firstly, and then the burst segmentation method is used for the low priority bursts in this strategy. Ensuring the integrity of high priority bursts, part of the segmented bursts can be transmitted to the destination node via combining wavelength conversion and optical buffer method. Simulation results show that the proposed scheme not only ensures the integrity of high priority bursts, but also reduces the packet loss rate of the low priority bursts maximally, so that it can support good quality of service (QoS) for the network.     

Highly stable fiber Bragg gratings written in hydrogen-loaded fiber

We demonstrated that the thermal stability of fiber Bragg gratings written in hydrogen-loaded standard fibers can be significantly enhanced by preirradiating the fiber with UV beam before writing gratings. Our experimental result shows that these gratings maintained more than 60% of their initial index modulation after 10 hours at 605/spl deg/C.     

产品开发过程标准化对产品开发质量的影响

本文从产品开发的标准化的一些内容来探讨企业产品开发过程标准化对产品开发质量的影响.     

Compound frequency selective surface with quasi-elliptic bandpass response

A compound frequency selective surface (FSS) with quasi-elliptic bandpass response is presented. The new FSS element comprises unit cells of two kinds of FSSs with one transmission zero. The FSS formed by this new element integrates the two transmission zeros of the original FSSs in one bandpass response curve and realises the quasi-elliptic filter response. Both theoretical and experimental investigations are carried out. Excellent agreement between simulation and measured results shows the validity of the theoretical analysis.     

基于小波的信号去噪分析

由实际应用可得,作为一种新的多辨认分析方法的小波变换,由于具有多分辨特征和时频局部性,可同时进行频域和时域分析,所以特别适用于进行非平稳信号的处理。首先介绍了小波分析的信号去噪原理,其次接着阐述了4种去噪算法：小波分解与重构去噪方法、模极大值检测法、阈值法及平移不变量小波去噪法。对于叠加了高斯白噪声的仿真信号,分别将上述的4种方法用于去噪处理,并通过仿真过程不同及图形差异对几种方法进行比较。