A Joint TDOA/FDOA Lo calization Algorithm Using Bi-iterative Method with Optimal Step Length

In order to improve the estimation accuracy of multi-station joint Time difference of arrive/ Frequency difference of arrive (TDOA/FDOA) location with Bi-Iterative method, a solution for the position of target with Gauss-Newton optimal step length is proposed in this paper. First, get the initial estimation of target based on Two-stage weighted least-squares (TSWLS) algorithm, and then alternately solve the position and velocity of the target with Bi-Iterative method. In this paper, Gauss-Newton method is applied to iteratively solve the target position, including the detailed equations of the descending direction and the optimal iterative step length in each iterative process. Simulations are carried out to examine the algorithm's performance by comparing it with TSWLS method and Gauss-Newton method regardless of the step length. The results show that when Gauss noise variance is small, the estimation accuracy is close to Cramer Rao lower bound (CRLB) and the proposed method performs better than the other two methods. In addition, because the model which includes the position and velocity of the observation station and the target is in line with the over-the-horizon reality scene in this paper, our research has certain practical value.     

An Information Quantity in Pure State Models

When we consider an error model in a quantum computing system, we assume a parametric model where a prepared qubit belongs. Keeping this in mind, we focus on the evaluation of the amount of information we obtain when we know the system belongs to the model within the parameter range. Excluding classical fluctuations, uncertainty still remains in the system. We propose an information quantity called purely quantum information to evaluate this and give it an operational meaning. For the qubit case, it is relevant to the facility location problem on the unit sphere, which is well known in operations research. For general cases, we extend this to the facility location problem in complex projective spaces. Purely quantum information reflects the uncertainty of a quantum system and is related to the minimum entropy rather than the von Neumann entropy.     

取代1-氯蒽醌中分子内卤键的电子密度拓扑分析

运用量子化学密度泛函B3LYP方法,在6-311＋＋G（d,p）基组水平上对邻位和间位取代1-氯葸醌的分子内卤键进行了研究．用电子定域函数和“分子中的原子,,理论对分子内卤键的性质进行了电子密度拓扑分析．通过对计算得到的密度矩阵进行σ-π兀分离,得到了π-键的键径和分子图,并讨论了。电荷密度和兀电荷密度对卤键的影响．结果表明,键鞍点和环鞍点处的电子密度拓扑性质均可作为衡量分子内卤键强度的量度．键鞍点和环鞍点处的电荷密度P越大,键鞍点与环鞍点的距离越大,卤键强度越大．除σ电荷密度外,π电荷密度对分子内卤键的性质也有明显影响．     

一种平面传声器阵列在声源定位中的研究

空域中声源定位主要利用传声器阵列到达时间差(TDOA)技术实现,为避免阵列自身精度对测量的影响和复杂的计算,提出一种便捷的平面十字形传声器阵列模型,分析声源定位TDOA技术和模型在三维空间中的应用,给出了定位算法和误差公式,论证了模型在构造、计算方面的优势。系统虽在精度等方面有待进一步提高,但对无源定位的方法和阵列构造有较强的实用价值,在各类阵列技术领域中有广泛的应用前景。     

区域分工水平评价的新方法——区位结构熵法

根据区域产业分工理论,运用区位商测定区域专业化程度.然后,基于复杂系统结构熵理论,从产业在区际和区内聚集分布信息出发,融合行业路径和地区路径分析法于一体,提出并证明了可以用区位结构熵全面衡量产业在空间上的分布状况.在此基础上,构建一维区域分工指数,综合测定区域分工水平.最后,以我国工业空间分布为例,例证了该方法是合理的、可行的,具有一定的推广和应用价值.     

Asymptotic results in robust quasi-bayesian estimation

Let Θ be a real random variable with a known (a priori) distribution. Let the observations given Θ be iid with a common distributionF₀(·)=F(·−0)F is known to belong to some family of distributions on the real line. We find estimators of Θ which are asymptotically minimax for two types of loss functions.     

基于曲线拟合的亚像素边缘定位方法的研究

图像的边缘定位是图像测量的关键之一,随着测量精度要求的提高,已由早期的像素级边缘定位发展到了现在的亚像素级边缘定位。根据地球在地球敏感器CCD阵面中的成像特性,提出了一种基于曲线拟合的亚像素边缘定位方法以获取地球“灼热圆盘”的边缘。该方法利用曲线拟合获得的拟合斜率以及灰度值来提取图像的边缘。仿真结果表明,采用曲线拟合亚像素边缘定位法可使图像的边缘定位精度达到百分之几个像素,具有较高的精度。     

小型无线场强探测传感器研究

近年来,微波加热因其高效性和清洁无污染等优点广泛应用于各个领域.然而,微波加热的不均匀性限制了微波作为高效加热能源的应用.通过测量和分析加热腔中的电场分布情况可以帮助设计人员改进微波加热腔体设计,提高微波加热的均匀性.现有的场强测量设备均为有线设备,应用场景极为有限.因此,本文提出了一种由探头、接收机和上位机三部分组成...     

A MAC protocol to support hybrid antennas in a wireless LAN

Hybrid Distributed Coordination Function （HDCF）, a modified medium access control protocol of IEEE 802.11 standard, is proposed in this paper to support both smart adaptive array antennas and normal omni-directional antennas simultaneously in one wireless LAN. Omni-directional antennas follow the standard Distributed Coordination Function （DCF） and smart antennas follow the Directional DCF （DDCF）. The proposed DDCF is based on Hybrid Virtual Carrier Sense （HVCS） mechanism, which includes Omni-directional Request-To-Send/Clear-To-Send （ORTS/OCTS） handshake mechanism and directional data transmission. HDCF is compatible with DCF. When a node transmits in a directional beam, the other nodes can multiplex the physical channel. Hence, HDCF supports Space Division Multiple Access （SDMA）. Simulation results show that HDCF can support hybrid antennas effectively and provide much higher network throughput and lower delay and jitter than DCF does.     

无线传感器网络多跳路由协议研究

目的：无线传感器网络发展迅速,但传感器的高能耗问题成为制约其发展的主要瓶颈,高效节能的路由协议设计成为研究热点。方法：针对目前无线传感器网络常用的LEACH路由协议存在的簇首能耗过分集中、簇首分布不均衡问题,提出了改进的路由协议EEACRA,在总结、分析LEACH路由协议现有问题的基础上,给出了EEACRA路由协议的簇首选取门限值、簇首位置调整算法和基于能量代价最小的簇间多跳路由算法的实现方法,同时给出了具体的实现EEACRA协议的工作流程和关键算法。在MATLAB环境下对LEACH路由协议和EEACRA路由协议进行了仿真,对比了不同能耗降低措施对网络能耗降低的贡献。结果：仿真结果表明EEACRA路由协议的网络稳定期较LEACH路由协议有较大的改善。结论：证明了改进的路由协议EEACRA可以有效地提高网络的稳定期。