A low-cost testbed of underwater mobile sensing network

Comprised by a swarm of acoustically linked and cooperative autonomous underwater vehicles (AUVs) with onboard sensors, an underwater mobile sensing network (UMSN) will be a complementary means to fixed observatory networks, e.g. seafloor observatory networks and moored buoy arrays. It has obvious advantages over a single large AUV in higher efficiency due to parallel observation, stronger robustness to vehicle failures and lower cost. Although an UMSN can be viewed as a counterpart of wireless mobile sensing networks for air and terrestrial applications, it is much more challenging due to poor performance of underwater acoustic communication, poor performance of underwater positioning and high degree of uncertainty in vehicle dynamics and underwater environment. In order to verify key technologies involved in an UMSN, e.g. cooperation of multi-AUVs based on acoustic communication, a low cost testbed has been developed for experimental study. The design of both hardware and software is introduced. Also the results of a functional test for verification of the effectiveness of the testbed are presented.     

Pressure-Based Approach to Estimating the Injection Start and End in Single and Split Common Rail Injection Processes

The deep understanding on sand and sand dunes scale can be useful to reveal the formation mechanism of the sandstorm for early sandstorm forecast. The current sandstorm observation methods are mainly based on conventional meteorological station and satellites remote sensing, which are difficult to acquire sand scale information. A wireless sensing network is implemented in the hinterland of desert, which includes ad hoc network, sensor, global positioning system (GPS) and system integration technology. The wireless network is a three-layer architecture and daisy chain topology network, which consists of control station, master robots and slave robots. Every three robots including one master robot and its two slave robots forms an ad hoc network. Master robots directly communicate with radio base station. Information will be sent to remote information center. Data sensing system including different kinds of sensors and desert robots is developed. A desert robot is designed and implemented as unmanned probing movable nodes and sensors’ carrier. A new optical fiber sensor is exploited to measure vibration of sand in particular. The whole system, which is delivered to the testing field in hinterland of desert (25 km far from base station), has been proved efficient for data acquisition.     

The Acquisition of Sand Vibration Information in Hinterland of Desert Based on Advanced Remote Sensing System and Network Technologies

The deep understanding on sand and sand dunes scale can be useful to reveal the formation mechanism of the sandstorm for early sandstorm forecast. The current sandstorm observation methods are mainly based on conventional meteorological station and satellites remote sensing, which are difficult to acquire sand scale information. A wireless sensing network is implemented in the hinterland of desert, which includes ad hoc network,sensor, global positioning system(GPS) and system integration technology. The wireless network is a three-layer architecture and daisy chain topology network, which consists of control station, master robots and slave robots.Every three robots including one master robot and its two slave robots forms an ad hoc network. Master robots directly communicate with radio base station. Information will be sent to remote information center. Data sensing system including different kinds of sensors and desert robots is developed. A desert robot is designed and implemented as unmanned probing movable nodes and sensors' carrier. A new optical fiber sensor is exploited to measure vibration of sand in particular. The whole system, which is delivered to the testing field in hinterland of desert(25 km far from base station), has been proved efficient for data acquisition.     

基于移动代理的分布式无线传感器网络管理

无线传感器网络正日益成为一种用于各类应用中的重要技术。无线传感器网络由成百上千个传感器结点构成,这些传感器结点具有传感、处理及无线通信的能力。但迄今为止,无线传感器网络及其应用在发展的同时,并未考虑对无线传感器网络管理的解决方案。作为一种动态拓扑的无线移动网络,相对于常规网络的管理而言,无线传感器网络的管理有它自身的特点和要求。本文首先分别介绍了无线传感器网络以及移动代理的基本概念和特点,分析研究了无线传感器网络管理的自身特点和需求。然后在此基础上,提出了一种基于移动代理的分布式无线传感器网络管理的体系结构,其中包括网络管理体系结构的工作原理,以及被管理的传感器结点的结构模型。最后讨论研究了在此网络管理体系结构中的传感器结点的分簇要求及特点。     

An range-free localization scheme for large scale underwater wireless sensor networks

In this paper, we study an area localization problem in large scale underwater wireless sensor networks (UWSNs). The limited bandwidth, the severely impaired channel and the cost of underwater equipment all make the underwater localization problem very challenging. Exact localization is very difficult for UWSNs in deep underwater environment. We propose a range free method based on mobile detachable elevator transceiver (DET) and 3D multi-power area localization scheme (3D-MALS) to address the challenging problem. In the proposed scheme, the ideas of 2D multi-power area localization scheme (2D-ALS) and utilizing DET are used to achieve the simplicity, location accuracy, scalability and low cost performances. The DET can rise and get down to broadcast its position. And it is assumed that all the underwater nodes underwater have pressure sensors and know their z coordinates. We evaluate the performances of 2D-ALS and our proposed 3D-MALS schemes under both ideal and non-ideal channel propagation conditions, in terms of localization error and localization ratio. The simulation results show that our proposed scheme is much more efficient than the 2D-ALS.     

一种分布式Ad hoc网络广播算法

在无线Ad hoc网络中,广播作为一种重要的通信方式被许多单播和多播协议用来完成其路由建立和维护工作.文中假设网络中所有的移动节点共享信道,并且节点不知道全局网络拓扑信息.因此网络中每个节点只能通过洪泛进行通信.但是采用洪泛方式广播,由于每个节点都要向其相邻节点转发报文,协议效率低、通信代价昂贵,而且还会带来广播风暴问题.为避免由于洪泛造成的广播风暴问题,文中提出一种分布式Ad hoc网络广播算法.该算法无需任何控制报文.算法简单易行,适合移动无线网络环境.仿真实验结果表明新的算法与现有算法相比更加有效和健壮.     

基于能量与功率控制的TopDisc拓扑算法研究

拓扑控制是无线传感器网络的一个重要研究方向,选择良好的拓扑控制机制,能够提高网络通信效率并延长网络的生命周期。在TopDisc算法的基础上,提出了一种基于能量与功率控制的拓扑控制算法,在能量的引导下,通过调整节点的发射功率,生成更适合的网络拓扑结构。仿真实验结果表明改进的算法形成的簇的交叠更少,网络的生存时间更长。     

大深度水下航行体引起的水底压力变化

水下航行体引起的水底压力变化是航行体的重要目标特性之一,可用于水下运动目标探测和水中兵器研制.基于船舶水动力学势流理论,建立了水下航行体水底压力计算模型.利用HessSmith方法,对大深度水下航行体的压力场分布进行了计算,分析了航行体水压场沿纵向和潜深的变化规律,计算结果和实验结果有较好的一致性.     

超空泡航行器舵效的水洞试验研究

为了获得超空泡航行器可控弹道与总体设计输入条件,对通气超空泡的生成和尾翼舵角的力学特性进行了缩比模型试验.通过改变通气量和尾翼舵角,对模型超空泡的形态和力学特性进行了深入分析,获得了尾翼舵角对升力的影响规律及尾翼舵效随攻角和通气量变化的规律,并探讨了由于空泡尾部重力效应引起的上漂现象的补偿方法.试验结果表明:在沾湿条件下,水下超空泡航行器尾翼舵面升力线斜率可取正值常数进行全域投影,这与同样条件下常规水下航行器相同;完成超空化后,当攻角为0.4°时,主体空泡耦合升力损失将导致舵效减小,且舵效对通气量的改变不敏感;当攻角大于1.2°后,舵效特性逐步恢复,此时主体空泡已经脱离翼面,舵面处于沾湿状态.     

基于多参数加权的IVC网络系统移动自适应分群算法研究

由于IVC车辆间通信系统中车辆的移动性,其无线通信网络的拓扑结构是动态变化的.若每个车辆节点各自维护网络路由信息会导致大量的控制信息而占用带宽资源,因此需要将IVC网络内的车辆节点进行分群处理.文中提出了一种针对IVC网络系统的基于多参数融合加权的改进移动分群算法,该算法将节点的位置及速度等运行状态信息作为决定分群的因素,并考虑了车辆节点的移动特性,因此保证了网络分群的稳定性和移动适应性.     

水下不分散混凝土柱受压性能试验研究

基于跨江、跨海、深水港工程的环境特点,工程中采用大量水下不分散混凝土材料,进行了水下不分散混凝土短柱的轴心和偏心受压实验,分析了水下不分散混凝土的破坏形态和承载能力.试验结果表明,水下不分散混凝土的抗压性能与普通钢筋混凝土的抗压性能具有相似的特征.     

长青沙大桥深水基础钢套箱-沉井施工技术

长青沙大桥跨越长江北汊,其水文、地质条件极其复杂,深水基础是全桥的施工难点,对钢套箱—沉井综合施工法在深水基础施工中的应用进行探讨,介绍了主要施工过程和注意事项。     

基于BTT控制的UUV H∞鲁棒自动驾驶仪设计

针对基于倾斜转弯控制技术的无从水下航行器自动驾驶仪三通道之间耦合的问题,提出了应用H∞反馈控制理论对其设计的方法。根据基于过载误差描述的系统状态方程,将控制通道间的耦合因素看作有界干扰,从而对滚动、俯仰和偏航三个通道独立进行设计,并给出了该方法的具体步骤。仿真结果表明,该方法可以很好地抑制耦合干扰,满足设计指标。     

桥梁围堰封底缺陷处理技术探讨

本文结合扬州市333省道新民滩特大桥的工程实例,对水下不分散混凝土与深水注浆技术在桥梁围堰封底缺陷处理中的综合应用进行了介绍,以期为同类桥梁深水基础施工出现的缺陷处理提供借鉴。     

桥梁水下承台施工技术

水中主墩是桥梁工程施工的关键,也是某桥梁主桥段的控制性工程.主墩下部结构施工方案的拟定直接影响到该桥的节点进度,对按期完成施工任务,早日实现全线贯通具有重要意义.鉴于此,在分析该工程施工难点的基础上,详细探讨其水下承台施工技术,以期为同行提供参考借鉴.     

基于碰撞危险度模型的AUV三维避障研究

自治式水下机器人(AUV)在复杂海洋环境航行时要求能够及时躲避障碍物.文中建立了基于前视声呐的环境模型,将未知障碍物信息转化到环境中,并对未知障碍物进行属性判断.将水面船舶的碰撞危险度概念应用到AUV的水下环境避障中,建立新的水下三维碰撞危险度模型,仿真实验证明此方法可以使AUV 在多水下运动障碍物的不确定环境中得到较好的局部避碰效果.     

水下隧道贯彻国防要求研究初探

介绍了国内已建、在建和拟建的重要水下隧道,总结了利用水下隧道进行军事运输的优缺点,初步探讨了水下隧道在建造阶段、日常管理和应急处置时,如何贯彻国防要求的问题和隧道发生事故时利用沉管法和悬浮法进行隧道抢修抢建的设想。最后,指出水下隧道工程在贯彻国防要求工作中的难点。     

信息融合技术在水下组合导航系统中的应用

要实现水下精确导航,采用单一导航方法,其精度、可靠性无法满足需要．将多种导航技术适当融合,可以取长补短提高导航精度．以捷联惯性导航系统作为组合导航系统的主导航设备,GPS导航、多普勒导航等为辅助导航设备,利用联邦Kalman滤波技术对水下组合导航系统进行信息融合,充分融合多导航传感器信息,提高远程自主水下航行器的导航精度．     

基于交叉口重要度深度搜索的区域信号协调控制方法

城市路网规模的不断扩大,给城市交通控制系统带来严峻的挑战.本文对交叉口之间的交通关联关系及表征交叉口关联性的交通流参数进行了分析,从而明确路网的拓扑结构,建立了以路网拓扑结构为基础的交叉口重要度估计模型,并根据有向深度搜索算法设计了区域信号协调优化方法.该方法从全局的角度建立了一种均衡疏导路网交通流的信号协调控制方法.最后将本文提出的方法与Synchro7优化出的控制方案对比,利用微观仿真软件SUMO进行控制效益评价,仿真结果表明,本文的方法可以有效提高信号控制效益.     

桥梁钻孔灌注桩基础施工技术

结合某桥梁工程实例,系统地介绍了该桥梁钻孔灌注桩的施工环节,包括施工准备、钻孔施工、钢筋笼埋设、水下混凝土灌注等,总结出各个施工环节的技术要点,指出施工中应注意的问题及对策,可为同类工程提供参考。