中国海员教育的出路

根据BIMCIO/ISF公布的《2000年世界海员市场供需情况报告》,预测按目前世界各航线对船员需求的增长速度,到2010年,世界高级船员的短缺将达4.6万人。与此同时,目前国内内河持证     

基于模糊集合理论的船舶碰撞危险度模型

为了解决多船避碰决策过程中避让行动优先级问题,提出一种基于模糊集合理论的船舶碰撞危险度确定模型。选取最近会遇距离、最近会遇时间、船间距离、相对方位、船速比5个因素建立碰撞危险度影响因素集,并确定各因素评价集、评价指标以及各参数的隶属度函数,经模糊综合评价得到船舶碰撞危险度计算模型。设置两船交叉会遇以及多船交叉会遇2种会遇局面进行仿真实验,实验结果验证了该模型的有效性。     

A semi-fragile wavelet transform watermarking scheme for content authentication of images

A novel semi-fragile watermarking scheme for the content authentication of images using wavelet transform (WT) is presented in this paper. It is tolerant to the embedded wavelet image compression methods based on WT such as embedded zerotree wavelet (EZW), set partitioning in hierarchical trees (SPIHT) and embedded block coding with optimized truncation (EBCOT) in JPEG2000 to a pre-determined bit-plane, but is sensitive to all other malicious attacks. The image features are generated from the lowest-frequency (LF) subband of the original image as the embedded watermark. The watermark is embedded into the pre-determined bit-plane by adjusting the corresponding values in the given subband. In the process of watermarking authentication, we compare the image features generated from the LF subband of the received image with the embedded watermarking information (the image features of the original image) extracted from the pre-determined bit-plane in the given subband of the received image to decide whether the image is attacked maliciously or processed acceptably (the embedded wavelet compression). The most important advantage of our watermarking scheme is that the watermark information can be extracted from the watermarked image when detecting watermark, so the received image authentication needs no information about the original image or watermark. Experimental results prove the effectiveness of our proposed watermarking scheme.     

基于MATLAB7.0的船舶安全航宽计算

在我国经济高速发展的大前提下,航运业也有了快速的发展。随着港口和船舶的增加,现有的通航资源显得越来越珍贵。因此,在港口航道规划及海事主管机关的船舶安全监管中,都将船舶受自然条件影响产生的漂移量作为一个重要的参数进行考虑。但由于船舶漂移量计算参数较多,包括风、流及船型等多个要素,当需计算多船不同天气条件下的船舶漂移量并绘制曲线时,计算量相当大。而简单的手工计算和绘图显然不能很好的完成。本文介绍一种基于数值计算软件MATLAB7.0的船舶漂移量计算方法,并结合实例利用其进行船舶安全航宽的计算。     

沿河取排水工程通航安全影响研究

目前,制约长江黄金水道作用充分发挥的因素很多,在诸多因素中,复杂多变的水域通航环境是一个不可忽略的重要因素,其中在长江干流水域修建取水工程,必将对该水域的通航环境造成一定影响,为防止工程水域通航环境恶化,保障该水域船舶航行安全及工程自身安全,防止水域污染,本文提出了一套科学可行的研究方法,来评估论证取水工程的修建对所在航道船舶的安全航行及船舶通航环境的影响。对取水工程的选址、设计规模和设计方案是否合理可行,做出判断,并提出一些相应的解决方案或安全措施。