Received signal strength based positioning for multiple nodes in wireless sensor networks

We address the problem of locating multiple nodes in a wireless sensor network with the use of received signal strength (RSS) measurements. In RSS based positioning, transmit power and path-loss factor are two environment dependent parameters which may be uncertain or unknown. For unknown transmit powers, we devise two-step weighted least squares (WLS) and maximum likelihood (ML) algorithms for node localization. The mean square error of the former is analyzed in the presence of zero-mean white Gaussian disturbances. When both transmit powers and path-loss factors are unavailable, two nonlinear least squares estimators, namely, the direct ML approach and combination of linear least squares and ML algorithm, are developed. Numerical examples are also included to evaluate the localization accuracy of the proposed estimators by comparing with two existing node positioning methods and the Cramér–Rao lower bound.     

Overshoot‐free nonholonomic source seeking in 3‐D

This paper studies the problem of steering a nonholonomic vehicle with a constant forward velocity to localize a source in 3‐D. Of two existing 3‐D source‐seeking strategies, one causes overshoots of the vehicle around the source while the other shows slow convergence rate in approaching the source. We propose a composite of these 2 control strategies to achieve a balanced performance by taking advantage of both strategies. Moreover, we prove local exponential stability for a static spherical signal map using averaging and describe the influence of the parameters using root locus method. Simulation results further validate the effectiveness and advantages of the combined strategy.     

海外工程项目人力资源属地化研究——以中交四航局肯尼亚蒙内铁路项目为例

探讨海外工程项目人力资源属地化的必然性,分析其存在的问题。结合海外项目实际,提出制定人力资源属地化实施方案、建立规范的人力资源属地化管理制度、加强跨文化管理、加强外籍雇员培训、重视对海外项目部中方人员的"赋能"及建立完善的考核激励机制等人力资源属地化提升措施。     

Three-dimensional atom localization in a five-level M-type atomic system

By using three mutually perpendicular standing-wave fields, we propose a scheme for three-dimensional (3D) subwavelength atom localization in a five-level M-type atomic system. Based on the electromagnetically induced transparency, position probability distribution of the atom in 3D space could be determined via measuring the probe absorption which is proportional to the filter function. It is shown that patterns of 3D atom localization depends sensitively on the coupling schemes of the standing-wave fields. When the standing-wave fields couple three different transitions, the same atom localization patterns are formed in the eight subspaces of the 3D space. While all the standing-wave fields are applied on one transition, we can realize different atom localization patterns in the eight subspaces. From the view of the xy plane, various symmetric or asymmetric atom localization patterns could be formed at different z positions by adjusting the parameters of the laser fields.     

昆山思常路茶室

昆山市思常路茶室的设计探讨了在现代中国城市中如何让居民重新接触自然。同时,它还在建筑实体上用低技术、低成本的手段实验了平缓曲线的形式语言。此设计也可以看做海外建筑设计在中国产生的另类影响。     

基于蜂窝网络拓扑的无线传感网定位算法

针对无线传感网中DV-Hop定位算法过于依赖信标节点数量以及定位精度低的问题,提出基于蜂窝网络拓扑的定位算法(LABCNT)。通过对网络中节点的有向筛选,选取满足特定条件的节点,构造一个蜂窝的网络拓扑结构,得到网络上节点的相对位置;根据拓扑结构中的第二个信标节点确定网络上节点的绝对位置;将已定位的节点升级为协作节点,采用最小二乘算法对域内其它未知节点进行定位。仿真结果表明,与DH-RLS、IDVH-LA、IDVH-HCHEC算法相比,LABCNT算法的定位精度较高,所需信标节点数量最少。     

Distributed algorithm for target localization in wireless sensor networks using RSS and AoA measurements

This paper addresses target localization problem in a cooperative 3-D wireless sensor network (WSN). We employ a hybrid system that fuses distance and angle measurements, extracted from the received signal strength (RSS) and angle-of-arrival (AoA) information, respectively. Based on range measurement model and simple geometry, we derive a novel non-convex estimator based on the least squares (LS) criterion. The derived non-convex estimator tightly approximates the maximum likelihood (ML) one for small noise levels. We show that the developed non-convex estimator is suitable for distributed implementation, and that it can be transformed into a convex one by applying a second-order cone programming (SOCP) relaxation technique. We also show that the developed non-convex estimator can be transformed into a generalized trust region sub-problem (GTRS) framework, by following the squared range (SR) approach. The proposed SOCP algorithm for known transmit powers is then generalized to the case where the transmit powers are different and not known. Furthermore, we provide a detailed analysis of the computational complexity of the proposed algorithms. Our simulation results show that the new estimators have excellent performance in terms of the estimation accuracy and convergence, and they confirm the effectiveness of combining two radio measurements.     

异型混凝土结构的施工测量放样

随着国民经济不断提高以及建筑业的迅猛发展,建筑工程设计逐渐多样化、艺术化,施工定位测量技术的要求也越来越高,测量数据计算越来越复杂。在异型混凝土结构施工中,要确保建筑的整体质量和外观效果达到设计要求,异型构件的空间位置定位、平整度及观感质量尤为重要。     

我国核电循环泵齿轮箱的发展概况

简要概述了国内外核能发电业的发展状况,及核电循环泵齿轮箱的国产化应用情况,指出了目前制约我国核电齿轮箱国产化的主要问题,展望了核电齿轮箱国产化的发展前景。     

基于ABS模块升级的制动液加注机国产化改造

系统阐述了ABS制动液加注机国产化改造的方案和步骤,采用外置的国产解码器独立与汽车上的ABS模块通讯,与原有设备只进行一些简单的通讯,对原有设备只进行了一些外围的PLC程序和电路改造。