一种集中式水下无线传感器网跨层调度协议

分析了水下无线传感器网络（WSNs）中单链路发射功率和距离与频率的关系,提出一种跨层的集中式调度方法,AP（access point）在网络中通过广播信标的形式收集估计各节点的时延和距离信息,在MAC层考虑水下链路延迟特点,对各链路进行调度减少冲突;节点在物理层通过自适应地改变节点发射功率和发射频率,减少能耗.仿真结果表明：所提方案在节省系统能量消耗的同时,能够减少碰撞,提高系统吞吐量.     

三级生物接触氧化在高层建筑污水处理改造工程中的应用

某高层建筑已完成污水处理装置土建部分的施工,为达标排放,提出改造方案。经方案比较,将原单级接触氧化法改为三级接触氧化法,将原鼓风曝气改为潜水曝气,增加污泥外循环回流及清水池和排水泵,以强化系统脱氮效果,保证出水顺利排放。同时,介绍了各处理单元的设计参数,分析了运行费用和投资,以供同类工程参考。     

挡水结构水下爆炸作用的离心模型试验

水下爆炸包括冲击波和气泡脉动,两者能量相当,均会对结构产生毁伤作用。水下爆炸载荷试验唯有在离心机内才满足相似关系,设计试验时宜在离心机负载范围内尽可能增加模型尺寸以减小边界效应。针对挡水结构,在离心机内布置压力传感器、高速摄像机、加速度计及应变片测试了冲击波、气泡脉动载荷及结构产生的动力响应。通过试验对比了水下爆炸和空爆产生的载荷,分析其引起结构动力响应的差异。对于水下爆炸,重力加速度的增加引起气泡脉动冲量的减小,而气泡脉动产生的峰值应变基本与气泡冲量呈线性关系,因而模拟气泡脉动对结构作用时应考虑重力效应。     

Adaptive tracking control of an autonomous underwater vehicle

This paper presents the trajectory tracking control of an autonomous underwater vehicle(AUV). To cope with parametric uncertainties owing to the hydrodynamic effect, an adaptive control law is developed for the AUV to track the desired trajectory. This desired state-dependent regressor matrix-based controller provides consistent results under hydrodynamic parametric uncertainties.Stability of the developed controller is verified using the Lyapunov s direct method. Numerical simulations are carried out to study the efficacy of the proposed adaptive controller.     

UWSNs中基于AUV移动的覆盖盲区修复算法

提出了一种水下无线传感器网络(UWSNs)中基于自主水下航行器(AUV)移动的覆盖算法。首先将要覆盖的区域网格化,然后以适当的策略遍历各个小格,从而实现盲区的覆盖修复。该算法克服了水下环境复杂未知、覆盖场景多样化而难以可靠覆盖的问题,同时使得AUV路径移动消耗最小化。文中还对3D场景和多AUVs协同等情况进行了分析和探讨。仿真实验表明,该算法在覆盖盲区规则、不规则或不连续等场景下均有较好的表现。     

基于变维卡尔曼滤波的UUV目标运动优化估计方法

为实现无人水下航行器精准、安全的跟踪目标从而高效地实现目标的信息采集,提出了一种针对该个体的目标运动优化估计方法。此方法通过建立目标运动模型,基于卡尔曼滤波基本原理,利用变维卡尔曼滤波的方法,达到UUV个体对目标运动状态准确估计的预期效果。为提高该方法的可行性,在利用最小化目标位置估计协方差矩阵完成目标运动轨迹估计及优化的过程中,考虑实际UUV机动时的最大速度限制、与目标最小距离的限制。文章详细阐述该方法的实现和步骤,并通过仿真实验验证了该优化算法的有效性。     

Evaluation on steel bar corrosion embedded in antiwashout underwater concrete containing mineral admixtures

This study aims the evaluation of the corrosion of steel bar embedded in antiwashout underwater concrete, which has rather been neglected to date. To that goal, accelerated steel bar corrosion tests have been performed for three series of steel bar-reinforced antiwashout underwater concrete specimens manufactured with different admixtures and under different environments. The three series of antiwashout underwater concrete were: concrete constituted exclusively by ordinary portland cement (OPC), concrete composed by ordinary portland cement mixed with fly-ash in 20% ratio (FA20) and concrete with ground granulated blast furnace slag is mixed in 50% ratio (BFS50). And, the three different environments were: manufacture in the air, in tap water, and in artificial seawater.Measurement results using half-cell potential surveyor showed that, among all the specimens, steel bar in OPC manufactured in artificial seawater was the first one that exceeded the threshold value proposed by ASTM C 876 with a potential value below − 350 mV after 14 cycles. And, the corresponding corrosion current density and concentration of water soluble chloride were measured as 0.3 μA/cm² and 0.258%. On the other hand, for the other specimens that are FA20 and BFS50, potential values below − 350 mV were observed later at 18 and 20 cycles, respectively.Results confirmed the expectation that mineral admixtures may be more effective in delaying the development of steel bar corrosion in antiwashout underwater concrete.     

基于正交小波变换的变步长盲均衡算法

提出了一种基于正交小波变换的变步长盲均衡算法。该算法将正交小波变换理论引入到常数模盲均衡算法中,充分利用小波变换对信号的去相关性及指数型变步长控制迭代过程的特性来加快收敛速度。与常数模算法及基于正交小波变换的盲均衡算法相比,该算法收敛速度快、稳态误差小、均衡效果好。水声信道盲均衡的仿真结果,验证了其的性能。     

深圳市抛石填海区物探方法研究

在深圳某抛石填海区,由于存在较厚的淤泥层,而且在淤泥层中大量的分布着大小不均的石块,在物探作业的时候,往往难以探测到淤泥下面的基岩面,本文基于以上情况,通过对几种常规的物探方法的对比,从理论到实践,从中找到了最优的勘探方法,为以后从事此类工程的物探工作者提供一些借鉴。     

基于平移不变小波变换的多普勒速度声纳输出信号处理

针对水下航行器组合导航系统所使用的多普勒速度声纳输出信号的特点,采用了平移不变小波变换的多分辨率分析的方法,利用Daubechies小波函数,采用了半软阈值去噪的方法,能够在低信噪比的情况下准确地估计多普勒声纳的频移,从含有噪声的多普勒输出信号中提取出原始信号.通过仿真实验表明:采用4层小波分解,算法计算量减小,有效地...