基于Terzaghi假定的基坑抗隆起稳定性计算方法研究

本文根据Terzaghi地基承载力理论,针对基坑隆起破坏时土体向基坑一侧滑移失稳的实际情况和地下水渗流对基坑稳定性影响,对Terzaghi法确定基坑抗隆起安全系数做了相应的改进,推导出新的计算抗隆起稳定安全系数方法.对影响基坑抗隆起稳定问题的因素进行了参数分析,并通过工程实例计算分析,证明新的计算方法提高了基坑抗隆起稳定设计的可靠性.     

一种基于正则化方法的SAR图像边缘检测算法

提出了一种基于正则化方法的SAR图像边缘检测算法,并用MSTAR(moving and stationary target acquisitions and recognition)数据进行大量的仿真实验。实验表明,与经典的边缘检测方法相比,该方法能保持图像的细节特征,较好地解决了边缘断裂和抗噪问题,具有较好的边缘检测能力。     

膨胀系数可调的Balloon Snake方法在道路轮廓提取中的应用

以条带检测的结果初始化道路轮廓,利用balloon snake方法提取道路轮廓.在初始道路轮廓存在缺失的情况下,balloon snake的膨胀作用可以找回丢失的道路片段,提高道路提取的完整性.基于图像梯度和轮廓曲率调节膨胀系数,降低道路提取效果对膨胀系数的敏感,并加快道路轮廓的扩张,减少迭代次数.通过多幅道路图像的试...     

国外航海保障体系研究与启示

通过对以英国、美国和日本为代表的国外航海保障体系的研究,重点从组织结构与人员构成、技术支持与主要产品、质量管理与服务体系几方面分析了的国外航海保障体系的先进性,指出其对我国航海保障体系发展的启示之处,提出了我方的改进方向。     

基于复小波变换的SAR图像斑点滤波方法

斑点噪声的存在使得SAR图像的应用受到较大的限制.文中首先介绍了SAR图像斑点噪声模型以及几种常用的SAR斑点噪声抑制方法;然后对小波变换斑点噪声滤波方法进行分析,提出了基于二元树复小波变换的SAR图像滤波方法.实验比较表明,二元树复小波变换抑制SAR斑点噪声效果明显,较小波变换更具有优越性.     

大连港外海域船舶尾迹光学特征研究

通过大连港外海上实验测量船舶含气泡尾迹表观光学特征(如离水辐亮度、遥感反射率),分析了尾迹气泡对极度混浊的Ⅱ类水体海水表观光学特征的影响.实验结果证明:无论在可见光还是近红外波段,尾迹气泡都增强了海水表观光学量,如耘海船尾迹遥感反射率在可见光波段相对背景海水提高了50%,在近红外波段相对提高了159%.数据分析结果表明在此种水体中,气泡使得尾迹海水水色变黄,而不是在Ⅰ类水体中使水色变绿.随着观测点在尾迹中的位置靠近目标船,气泡数密度不断增加,遥感反射率也随之增强.     

天基海洋目标信息感知与融合技术研究

天基信息网络海洋目标监视既要建立完善的天基海洋目标监视系统,更要研究面向海洋目标监视的多源卫星观测信息融合技术,提升海洋目标监视的广域搜索、精细识别、持续监视和快速响应能力。分析了海洋目标信息感知与融合中的海洋环境和海洋目标特点,在总结分析天基海洋目标信息感知与融合的发展历程和数据特点的基础上,提出了天基海洋目标信息感知与融合在平台网络、时空融合和信息融合等方面的技术突破途径和未来发展方向。     

A mesoscale eddy detection method of specific intensity and scale from SSH image in the South China Sea and the Northwest Pacific

Mesoscale eddies exist almost everywhere in the ocean and play important roles in the ocean circulation of the world. These eddies may cause sound spread singular regions and bring great influences to the upwater ship and underwater aircraft. Due to the lack of hydrographic survey datasets, study of mesoscale eddies has been greatly restricted. Fortunately, satellite altimeter provided an effective way to study mesoscale eddies. An automatic detection algorithm is introduced to detect mesoscale eddies of specific intensity and spatial/temporal scale based on satellite sea surface height (SSH) data and the algorithm is applied in a strong eddy activity region: the South China Sea and the Northwest Pacific. The algorithm includes four steps. The first step is preprocessing of the SSH image, which includes elimination of error SSH data and interpolation. The second step is to detect suspected mesoscale eddies from preprocessed SSH images by dynamic threshold adjustment and morphological method, and the suspected mesoscale eddy detection includes two procedures: suspected mesoscale eddy core region detection and suspected mesoscale eddy brim extraction. The third step is to pick out mesoscale eddies satisfied with specified criteria from suspected mesoscale eddies. The criteria include three items, that is, intensity criterion, spatial scale, criterion and temporal scale criterion. The last step is algorithm performance analysis and verification. The algorithm has the capability of adaptive parameter adjustment, and can extract mesoscale eddies of interested intensity and spatial/temporal scale. The paper can provide a basis for analyzing space-time characteristics of mesoscale eddy in the South China Sea and the Northwest Pacific.     

Integrated Navigation System and Experiment of a Low-Cost and Low-Accuracy SINS/GPS

When SINS (strap-down inertial navigation system) is combined with GPS, the observability of the course angle is weak. Although the course angle error is improved to some extent through Kalman filtering, the course angle still assumes a divergent trend. This trend is aggravated further when using low-cost and low-accuracy SINS. In order to restrain this trend, a method that uses AHRS to substitute for SINS course angle information is put forward aimed at the hardware component characteristic of the low-cost and low-accuracy SINS including AHRS (attitude and heading reference system) and IMU (inertial measurement unit). Real static and dynamic experiments show that the method can restrain the divergent trend of the navigation system angle effectively, and the positioning accuracy is high.     

运用改进系统建模法对南海气象数据的建模研究

在系统建模理论的基础上,运用改进的动态数据建模方法,对南海气象数据中的温度进行建模并验证了模型的适用性.根据模型推导出格林函数、逆函数和自协方差函数等,并讨论了南海气象数据中温度模型的稳定性、可逆性和合理性.对系统的频率特性和谱函数进行分析讨论,并给出建模过程中的一些图像.根据模型的适用性检验发现,对所研究的气象数据而言,ARMA(4, 3)模型是最合适的,具有平稳可逆性.所有的建模和分析过程在MATLAB上实现.实验结果表明这种建模方案简便易行,能够快速准确地确定系统的合理模型.