On the Possibility of using Vertical Receiving Arrays for Underwater Acoustic Communication on the Arctic Shelf

Acoustical Physics - Numerical simulation is applied to analyze the possibilities of using vertical receiving arrays covering the entire waveguide for underwater acoustic communication on the...     

Acoustic Communication Equipment for Monitoring the Operation of an Autonomous Hydroacoustic Bottom Station on the Shelf

Acoustical Physics - The paper presents the acoustic communication equipment with bottom stations of the Shelf-2014 hydroacoustic complex—built-in acoustic bottom station modems and a...     

水下光学监控系统照明方式的研究

提出了一种确定水下光学监控系统中照明光源方向角和安装位置的方法.利用光在水中的传输特性,分析了传输距离、体积散射函数、散射角和小体积元的影响,以及照明光源不同方向角产生的不同照明效果.据此提出了光源方向角的确定原则,即在满足监控区域要求的前提下,照明光源的方向角应该选取散射角最大的方向.在视场角为45°时,光源方向角应为67.5°.根据监控范围边界的要求以及光源方向角,确定光源安装位置.实际应用结果表明,此方法可以很好地满足水下光学监控系统的要求.     

水下光学监控系统照明方式的研究

提出了一种确定水下光学监控系统中照明光源方向角和安装位置的方法.利用光在水中的传输特性,分析了传输距离、体积散射函数、散射角和小体积元的影响,以及照明光源不同方向角产生的不同照明效果.据此提出了光源方向角的确定原则,即在满足监控区域要求的前提下,照明光源的方向角应该选取散射角最大的方向.在视场角为45°时,光源方向角应...     

3维VSP光纤检波器井下地震采集系统

介绍了一种用于石油勘探的井下3维VSP(Vertical Seismic Profile)采集系统设计方案,实验验证该系统达到了可测量动态范围80 dB(可测量最大值与最小之比),系统采集、处理和传输的总延时低于200 ms(2 kbit/s采样率)的指标,适用于井下VSP采集.系统采用六级光纤加速度传感器组成阵列,其中每级传感器由三个麦克尔逊干涉仪构成.使用高速DSP处理芯片实现相位产生载波(Phase Generated Carrier,PGC)解调等算法以获得地震波信号;同时应用多个ARM处理器设计光纤检波器阵列控制器以及阵列内部总线.     

A Review of the New European Technical Recommendations for Monitoring Individuals Occupationally Exposed to External Radiation

This paper reviews the revised Technical Recommendations for Monitoring Individuals Occupationally Exposed to External Radiation as issued by the European Commission as Radiation Protection 160. These recommendations are aimed at all stakeholders in radiation protection dosimetry with an emphasis in the responsible technical staff of approved dosimetry services. This paper briefly touches each Chapter and ends with a more in depth section on the uncertainty evaluation of dose measurements.     

On the Thomas Equation for the Ion-Exchange Operations

The Thomas equation is an interesting subject in physical sciences. In this paper, we analytically solve the Thomas equation. The transformation obtained hereby is more general than the Thomas-Rosales transformation.     

谈数控机床实习教学的几点体会

作为现代制造技术的数控机床加工，正越来越广泛地被应用到国民经济的各个方面。本文结合作者多年从事数控机床实践教学工作经验，介绍了在数控机床实习教学中的一些具体做法和体会。     

水下通信中的异常声压监控网络系统设计

传统水下通信声压异常监控网络存在无法自主完成节点的投放和回收,存储监控盲区并且无法进行动态组网,不能对异常声压进行准确的监控等较大的缺陷;为此,设计并实现了一种新的水下异常声压监控系统,系统中的通信协议基于节点间的深度信息完成数据的转发,给出了系统中监控器、CC2430 处理器、终端节点以及协调器节点的硬件设计原理并给出了系统采集数据的软件流程;系统中实现了对链路层的AODV 路由协议进行改进,增强系统对异常声压的监控性能;测试结果说明,该系统获取的声压监测星座图明显优于传统系统,在不同的干扰类型下,发射信号使用PSK调制,载波中心频率是10 kHz,采样率是50 kHz,码率是2 000 bit/s;实验结果表明:该种系统具有较低异常声压信号监控误差率,可对异常声压信道的传输特性进行较好的校正和补偿,具有较强稳定性。     

Assessing the Possibilities of Identifying Bowhead Whales on the Arctic Shelf

Acoustical Physics - Real recordings of bowhead whale signals and numerical simulation were used to investigate the propagation of such signals in an Arctic-type shallow-water waveguide. The...     

Laboratory Physical Simulation of Acoustic Wave Propagation on the Shelf

Acoustical Physics - In laboratory conditions, the vertical structure of short mode pulses was studied near the critical thicknesses of hydroacoustic waveguides of constant and variable depth with...     

Numerical Simulation of Hydro- and Seismoacoustic Waves on the Shelf

Acoustical Physics - A finite element method is used for three-dimensional numerical simulation of hydro- and seismoacoustic waves in shallow water, generated by harmonically oscillating sources....     

Editorial for Special Issue on Underwater Wireless Optical Communication

正Underwater wireless optical communication(UWOC) has gained increasing research interest worldwide from both academic and industrial communities, because of its high bandwidth, compact antennas, low latency, cost-effectiveness, and     

Fundamentals of Passive Seismohydroacoustic Methods for Arctic Shelf Investigation

Acoustical Physics - A paper reviews existing and future seismohydroacoustic technologies, equipment, and novel scientific approaches to studying the Arctic Ocean. Particular attention is paid to...     

Operations support systems for managing fiber to the subscriber

Many considerations must be carefully thought through before introducing a new fiber loop distribution system that does not look or act like traditional copper pair cables. This paper describes an approach to managing such a fiber system, including ways in which that management can be integrated with existing telephone company operating support systems.     

Low-Frequency Hydroacoustic Experiments on the Shelf Using the Data of Geoacoustic Sediment Model

Acoustic and seismoacoustic methods have become the most perspective and intensely developed meth- ods in the research of dynamic processes and inho- mogeneities in shallow water. Seismoacoustic moni- toring allows one to draw conclusions about the pres- ence of different inhomogeneities in the water environ- ment and to identify various dynamic processes in the oceanic shelf zone. Studies of the propagation of hy- droacoustic signals of different frequencies and config- urations are widely discussed in scientific publications in Russia, China and the United States Solutions to inversion problems in acoustics, the con- struction of geoacoustic models and research of low- frequency acoustic signals with respect to the absorb- ing bottom are without any doubt at the forefront of underwater acoustics.     

基于逆模型的混合驱动水下滑翔机垂直面控制

混合驱动水下滑翔机（Hybrid-driven underwater gliders ,简称HDUGs)是集无人自治水下机器人（Automomous Underwater Vehicles ,简称 AUVs）和水下滑翔机（Autonomous Underwater Gliders,简称 AUGs）于一体的新型水下机器人。由于HDUGs是非线性、强耦合,且受到海流、结构不确定等因素的影响,为了克服这些问题,针对混合驱动水下机器人工作在混合模式下,对其垂直面提出了一种基于逆模型和滑模控制的非线性控制方法,该方法将原始系统解耦为两个单入单出的线性系统,仿真结果证明了该方法具有良好的控制性能,而且对外界扰动具有一定的鲁棒性。     

酥梨货架期的高光谱成像无损检测模型研究

水果新鲜度是反映水果是否新鲜、饱满的重要品质指标,为了探讨水果不同货架期的预测和判别方法,以酥梨为研究对象,利用高光谱成像技术,结合偏最小二乘判别法（PLS-DA）和偏最小二乘支持向量机（LS-SVM）算法对酥梨货架期进行判别。由光源、成像光谱仪、电控位移平台和计算机等构成的高光谱成像装置采集样品光谱,装置光源采用额定功率为200 W四个溴钨灯泡成梯形结构设计,光谱范围为1 000～2 500 nm,分别率为10 nm。选取优质酥梨30个,货架期设置为1, 5和10 d,对30个样品完成3次光谱图像的采集,并矫正原始图像。实验结果表明：基于图像的酥梨货架期定性分析时,对不同货架期样品的原始图像进行PCA压缩,得到三种不同货架期的权重系数数据,PC1图像提取特征波长点为1 280,1 390,1 800,1 880和2 300 nm,以特征图像的平均灰度值作为自变量且以货架期作为因变量建立定性判别模型,建模集68个,预测集22个。最小二乘支持向量机以RBF为核函数时,预测集中样品的误判个数为1,误判率为4.5%。而当采用lin核函数时,样品的误判个数为0,误判率为0。PLS-DA定性分析时RMSEC为1.24,R_c为0.93。RMSEP为1,R_p为0.96,预测集误判率为0。特征图像对酥梨货架期判别LS-SVM中的lin核函数所建立的模型结果较好,优于RBF核函数的建模效果,也优于PLS-DA判别模型。ENVI软件提取实验样品光谱后建立LS-SVM和PLS-DA判别模型,LS-SVM利用RBF和lin核函数误判率分别为4.5%和0。与RBF核函数相比,lin核函数所建立的模型预测酥梨货架期的效果更好。PLS-DA方法主成分因子数为12,RMSEC和RMSEP分别为0.48和0.78,R_c和R_p分别为0.99和0.97,建模集与预测集的误判率均为零。LS-SVM中的lin核函数所建立的模型结果较好,依然优于PLS所建立的检测模型。酥梨的光谱信息结合LS-SVM可以实现对酥梨货架期的检测和判别。基于图像建立酥梨的货架期预测模型与光谱相比,都实现了酥梨货架期的判别,而特征图像法,选择区域较少流失部分信息,计算量小,建模结果相对略差。酥梨货架期的高光谱成像检测模型研究为消费者正确评价水果新鲜度提供了理论指导, 也为后期果水果货架期检测仪器的开发提供了技术支持。     

Multisymplectic Geometry for the Seismic Wave Equation

The multisymplectic geometry for the seismic wave equation is presented in this paper. The local energy conservation law, the local momentum evolution equations, and the multisymplectic form are derived directly from the variational principle. Based on the covariant Legendre transform, the multisymplectic Hamiltonian formulation is developed. Multisymplectic discretization and numerical experiments are also explored.