IEEE 802.22.1信标网络应用研究

多个IEEE 802.22.1信标设备将自组织成信标网络。介绍了IEEE 802.22.1标准中定义的自组织方案;讨论了信标网络建立与维持过程中的判决策略;介绍了无线区域网络(WRAN)设备对IEEE 802.22.1信标网络的识别与信息获取机制;给出了确保实现对信标网络信息解析所需要安排的最大时延。     

区域重叠的无线传感器网络节点定位算法研究

传感器节点的自身定位是无线传感器网络应用的一个重要研究方向。为了确定节点的位置,需应用各种限制条件对其所在区域进行求解,找到解的交集,即找出符合各种条件的重叠区域。以区域的形状为线索,对基于区域重叠的无线传感器网络节点的定位算法进行了研究,分析了几种典型算法的原理与特点,对同一类算法优缺点进行了对比,对部分算法进行了仿真,得出了区域重叠算法的研究重点。最后对无线传感器网络定位的发展趋势进行了展望。     

基于BPSK调制方式的无线信标机的设计

针对黑匣子等弹载记录设备搜寻困难的问题,设计了一种基于BPSK(二进制相移键控)调制方式的无线信标机。选用U-BLOX公司的GPS(全球定位系统)模块NEO-5Q自我定位,使用DDS(直接数字频率合成器)芯片AD9910进行高频BPSK调制,再将信标数据帧通过射频电路板以一定频段发射。经实测,该设计可以得到输出功率达1.9mW、频段为400MHz以上的BPSK调制信号。该设计是借用软件无线电的思想,通过软件实现无线电台的各种功能,具有灵活性与开放性的特点。     

Single Beacon Cruise Positioning Algorithm in Wireless Sensor Networks

Node localization is important in WSNs （Wireless sensor networks） applications. We present a new cruise positioning algorithm, where a single beacon node cruises an entire network, broadcasting its position periodically with fixed signal strength. Meawhile, an unknown node obtains the location and the corresponding distance of the beacon node. Two possible position coordinate sets for the unknown node can then be calculated, and the coordinate mean of the point set with a small variance is an unbiased estimator of the unknown node＇s coordinate. The positioning algorithm＇s computation is simple, positioning accuracy is not limited by a physical distance measuring tool, and there are no restrictions on the path of motion, which makes it more realistic. An algorithm simulation is presented to compare the original and cruise location algorithm. Numerical results show that the cruise localization algorithm can achieve good positioning accuracy.     

自适应光学中扩展信标波前探测的研究与实验

讨论了一种基于Hartmann Shack (H S)传感器的扩展信标相关波前探测方法。通过在传统H S探测光路的物平面上加入视场光阑消除了子孔径像斑的重叠问题 ,并利用一种快速相关算法计算各像斑的相对位移 ,进而得到各子孔径波前的相对斜率。光学实验研究证实了该相关波前探测方法能够较精确地测算出波前像差 ,从而使目前使用最多的H S传感器具有扩展信标波前探测能力     

基于长脉冲光源的钠信标回光特性实验研究

采用与信标发射接收系统参数匹配的长脉冲光源,可在脉冲回光时间内产生较亮星等的钠信标,既有利于提高信标探测的信噪比,也有利于实现自适应光学系统的高频闭环校正.基于450 mm直径望远镜和大能量长脉冲光源,开展了钠信标探测实验,得到了长脉冲光源产生的钠信标回光特性.通过CCD和光电倍增管,采集得到了不同发射能量、出射偏振态下的回光强度,并获得了最大强度为15万光子/m2/pulse的回光,对应脉冲回光时间内约4.1等星的亮度.分析推算了实验条件下钠原子的柱密度.实验全过程未出现明显的饱和现象,验证了采用长脉冲钠信标光源避免饱和效应、得到高亮度钠信标的可行性.     

采用级联原子滤光器的新型卫星激光链路系统研究

提出级联佛克脱型原子滤光器(Linked VADOF)的新构想。从理论上分析并计算了级联佛克脱型原子滤光器的透射谱。结果表明，级联佛克脱型原子滤光器将佛克脱型原子滤光器的多峰改造为单峰结构，具有比佛克脱型原子滤光器更窄的线宽和更高的噪声抑制比。将这种新型结构应用于激光信标锁频。该锁频方案提高了信标光频率的稳定性。在此基础上，给出了发射端采用级联佛克脱型原子滤光器锁频，接收端采用法拉第型原子滤光器(FADOF)滤光的新型卫星激光链路系统。外场初步联调实验表明了该系统的可行性。     

采用原子滤光器的新型激光信标方案研究

提出了采用法拉第反常色散滤光器（ＦＡＤＯＦ）的光电双反馈激光信标新方案。该方案通过数字控制系统和光反馈系统的共同作用，使激光信标系统的稳定性、抗干扰性和可靠性大大提高，并实现了上电自动工作。这种新型激光信标的频率稳定度优于５×１０－９，在３０ｍｓ内可将半导体激光频率稳定在法拉第反常色散滤光器任一透射峰上。该方案可与采用法拉第反常色散滤光器的新型跟瞄系统匹配使用，对建立卫星激光通信链路有重要意义。     

Several concerns about the primer design in the universal molecular beacon real-time PCR assay and its application in HBV DNA detection

A universal hepatitis B virus (HBV) DNA detection kit is appealing for the worldwide diagnosis and monitoring of the treatment of different mutant types of hepatitis B virus. A sensitive and reproducible real-time PCR assay based on the universal molecular beacon (U-MB) technique was developed for the detection of HBV DNA in serum. The U-MB probe used in the assay has no interaction with the HBV DNA sequence. The U-MB technique not only reduced the cost of HBV detection but also had the potential for the development of a universal detection kit for different mutant HBV types and other DNA systems. To demonstrate its clinical utility, 90 serum samples were analyzed using the U-MB real-time PCR method. In the experiments we found that several crucial factors needed to be considered in the primer design, such as the avoidance of formation of severe primer–dimer and primer self-hairpin structure. With the optimized primer sets, satisfactory results were obtained for all the tested samples. We concluded that this assay would be an excellent candidate for a universal HBV DNA detection method. Principle of the U-MB real-time PCR method for HBV DNAdetection     

Fast and sensitive DNA analysis using changes in the FRET signals of molecular beacons in a PDMS microfluidic channel

A new DNA hybridization analytical method using a microfluidic channel and a molecular beacon-based probe (MB-probe) is described. A stem-loop DNA oligonucleotide labeled with two fluorophores at the 5′ and 3′ termini (a donor dye, TET, and an acceptor dye, TAMRA, respectively) was used to carry out a fast and sensitive DNA analysis. The MB-probe utilized the specificity and selectivity of the DNA hairpin-type probe DNA to detect a specific target DNA of interest. The quenching of the fluorescence resonance energy transfer (FRET) signal between the two fluorophores, caused by the sequence-specific hybridization of the MB-probe and the target DNA, was used to detect a DNA hybridization reaction in a poly(dimethylsiloxane) (PDMS) microfluidic channel. The azoospermia gene, DYS 209, was used as the target DNA to demonstrate the applicability of the method. A simple syringe pumping system was used for quick and accurate analysis. The laminar flow along the channel could be easily controlled by the 3-D channel structure and flow speed. By injecting the MB-probe and target DNA solutions into a zigzag-shaped PDMS microfluidic channel, it was possible to detect their sequence-specific hybridization. Surface-enhanced Raman spectroscopy (SERS) was also used to provide complementary evidence of the DNA hybridization. Our data show that this technique is a promising real-time detection method for label-free DNA targets in the solution phase. Figure FRET-based DNA hybridization detection using a molecular beacon in a zigzag-shaped PDMS microfluidic channel