共查询到19条相似文献，搜索用时 171 毫秒
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发生海上事故后，为对周边海域船只和人员进行疏散及为应急处置提供科学依据，并实现对不同检测位置检测浓度的校正，需要对事故有毒有害气体的扩散进行计算。本文先通过经验公式计算，模拟事故船舶自然燃烧，而后采用高斯烟羽模型，通过结合事故现场的风浪等水文气象参数，构建海上事故有毒有害气体扩散模型。该模型在改进的高斯烟羽模型的基础上，通过与 ArcGIS 结合，实现事故海域区域范围内有害气体扩散定量可视化，实验结果表明，“桑吉”轮撞事故中，有害气体沿向下风向西北处扩散，以事故点为起点向西北方向划线为轴线，宽幅选取 4 km 范围，最高浓度区域是以事故点下风向 3 km处为圆心，500 m 为半径的圆形区域，浓度可以达到 4* 10-5 mg/m3，边缘处气体浓度已低至 0.5 * 10-5 mg/m3。其模型简单且可以直观体现有毒有害气体扩散范围。 相似文献
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无动力或破损的船舶在海上自由漂移对海上的各项生产活动是一个巨大的危险。通过对海上漂浮的船舶进行受力分析,考虑船舶的外形特征及漂浮状态,建立了海上船舶漂移轨迹模型,对船舶海面以上与以下侧向投影面积之比(面积比)、风拖曳系数、流拖曳系数等参数均进行了敏感性分析,并针对2018年1月6日爆燃的"桑吉"油轮漂移轨迹开展了模拟应用。结果表明该模型针对不同类型海上船舶的漂移轨迹有一定合理的模拟能力,船舶面积比是准确模拟漂移轨迹的一个重要参数,同时,该模型对风拖曳系数、流拖曳系数较为敏感。针对"桑吉"油轮的模拟,科氏力的作用不可忽视,考虑科氏力作用后漂移轨迹的模拟效果得到了很好的改善。 相似文献
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利用MIKE21水动力模型对徐圩港区附近海域进行潮流数值模拟,并利用实测资料对模型计算的潮位、流速及流向进行验证。验证结果显示:数模结果与实测值吻合较好。该潮流数学模型可以反映研究海域水动力特性,并作为溢油模块的水动力基础数据。基于欧拉-拉格朗日"油粒子"理论考虑油膜运动过程中扩散、蒸发、乳化等过程,建立了徐圩港区邻近海域二维溢油扩散模型,模拟不同潮时情况下发生溢油,考虑不同风况(夏季常风向、冬季常风向和最不利风向),分析不同情况下的溢油油膜漂移路径、漂移路程及扫海面积。结果表明:72 h内油膜最大扫海面积及漂移路程均出现在落潮期最不利风时溢油,分别为28.2 km2和25.8 km。在夏季常风和最不利风的落潮期发生溢油,油膜会经过口门飘向西北侧海域,对该区域生态环境会造成一定影响。 相似文献
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目标触底过程中通常会产生强烈的瞬态地震波信号,通过对此类地震波信号的监测、处理和分析,能够帮助判断该信号的产生是否是由异常活动产生的,并且能够根据信号分析相关信息,实现早期预警, 从而做出快速响应。 由于双谱检测具有很好的抗高斯干扰能力,对高斯平稳随机过程和试验模拟目标触底瞬态地震波信号的双谱特性进行了分析,并在高斯背景中对试验采集的瞬态信号进行了检测仿真,仿真试验结果表明:在高斯背景的干扰下,双谱检测能够有效实现对瞬态信号的检测[1] 。 相似文献
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基于广义接触模型的离散元方法及其对船体冰载荷的分析 总被引：1，自引：1，他引：0
冰载荷是影响船舶结构安全的主要环境载荷,因而确定破冰船的冰载荷特征可用于船体结构设计及船舶安全预警分析。海冰作为典型的脆性材料,可采用单元间具有黏结失效效应的离散元方法模拟其破碎行为。为有效地模拟海冰破碎的渐进过程,采用由局部黏结点组成黏结单元的广义接触模型。为分析该模型中直接决定黏结单元失效的强度参数的影响,采用海冰单轴压缩和三点弯曲试验数值模拟进行分析。通过模型试验确定了失效模型中法向黏结强度、切向黏结强度和Mohr-Coulomb准则中的接触摩擦系数的影响。将该数值模型应用于极地科学考察船"雪龙号"的平整冰区冰载荷分析中,并与船舶整体冰阻力经验公式进行了对比验证。 相似文献
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完善污染物扩散基本方程。结合多组分扩散理论针对湿度变化对气体污染物扩散的影响进行研究，通过对气体污染物迁移、转化的基本方程进行修正，得到在无边界大气条件下1个稳定污染点源连续排放的扩散模型，并对方程进行了简化和求解；通过变湿度气态物扩散特性试验装置，对不同湿度条件下气体扩散性质进行了试验确定。得到了湿度变化条件下气体污染物扩散的一般规律。 相似文献
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基于高斯模式的大气污染模型的应用 总被引：1，自引：0，他引：1
通过运用MapInfo公司的MapX组件,基于高斯扩散模式建立1个大气污染模型,对发生意外事故导致的大气污染进行模拟和预测,模拟或预测结果通过等值线或专题图等形式进行表现,从而为发生环境污染事故后相关部门采取的紧急疏散等应急措施提供有价值的参考依据.文中重点介绍如何建立大气污染模型以及应用在环保应急系统中的方法和实际效果. 相似文献
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在Fudide-Krylov假设条件下,依据船舶分离建模理论在固定和运动坐标系中计算海面船只六自由度运动数学模型。主要包括:对风、浪、流的单独建模并进行矢量叠加,并在风浪流联合作用下对船舶六自由度运动构建简化的数学建模,完成实时仿真。基于Simulink和V-Realm Builder虚拟现实技术创建船舶运动模型、海洋表面环境及船只的几何模型,对船舶六自由度运动进行视景仿真,给出了有风无浪、有浪无风和风浪兼有三种情况下船只旋回路径和船舶运动轨迹。在VR视景浏览器中创建动态海面上船舶六自由度运动模型,不仅易于实现且结果逼真。得到的结果为进一步研究动态船只目标声散射特性的精确预报提供基础。 相似文献
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Ship-generated waves can contribute to the fatigue of offshore structures. This paper presents a numerical model for evaluating the forces exerted on a nearby fixed structure by ship-generated waves. The ship waves were modeled using Michell's thin-ship theory (Wigley waves), and the forces were computed using a boundary element method in the time domain. The simulation was validated by comparing its results with those of frequency-domain methods reported in the literature. It was then applied to calculate the forces exerted on a hemisphere by ship waves varying with the ship's speed, dimensions and distance from the hemisphere to the ship's path. Our results indicate that the ship waves have enormous effects on offshore structures and are not neglectable. 相似文献
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基于AIS的船舶会遇局面紧迫度量化分析 总被引：1，自引：0，他引：1
近年来船舶大型化、高速化的发展以及数量的不断递增,导致船舶碰撞概率大大增加。为更好地保障船舶航行安全,提出船舶会遇局面紧迫度这一概念。该概念表征船舶在当前航行状态下由于一定范围内所有其他船舶的存在而处于的会遇局面的紧迫程度,其旨在帮助船舶驾驶员实时感知并掌握船舶在海上航行时所处会遇局面的状况,从而据此加以判断并及时采取措施规避碰撞风险。建立了船舶会遇局面紧迫度的计算模型,该模型以考虑到本船速度的动态圆形领域为空间约束条件,综合考虑其他船舶相对于本船的方位分布和距离这两个指标的影响,基于信息量量化紧迫度。利用2016年1月1日天津港AIS数据进行紧迫度的计算与分析,计算结果与实际相符,该计算模型能够准确反映船舶在航行过程中所处会遇局面的紧迫程度。利用双线性内插法建立天津港区域紧迫度二维彩色平面分布图,其表达效果优于传统热度图。 相似文献
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基于二元LSTM神经网络的船舶运动预测算法研究 总被引：1，自引：1，他引：0
在海况环境下,进行船舶运动预测时。由于惯性传感器采集系统本身的电学特性,会产生误差偏移,影响预测的准确性。针对这一问题,在常规长短期记忆网络（LSTM）的基础上,设计改良了一种二元的LSTM网络架构。在船舶运动仿真平台上进行模拟船舶升沉运动实验,并通过惯性传感系统测量仿真平台实时积分位移进行计算验证。验证统计该网络预测结果峰差值均方差0.64%,均值均方差0.42%,峰值均方差0.57%,证实该网络较常规LSTM在船舶运动预测领域具有更好的针对性和适应性,更准确的对船舶运动进行预测。 相似文献
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Maneuverability is an important aspect of marine vehicle design. The performance of a rudder, as the most important means of maneuvering, has significant impacts on ship controllability characteristics. This study investigated the effect of five rudder profiles (NACA 0012, NACA0025, IFS, Fish tail, HSVA) on the turning characteristics of KCS containership model. This investigation was performed by direct simulation of the ship turning circle maneuver in computational fluid dynamic environment based on the ITTC verification procedure. All rudders were defined with the same lateral area. Simulations were conducted with the commercial software STAR-CCM+. The rudder turning and the ship's dynamic motion were modeled by the use of an overset technique and six-DOF dynamic solver, respectively. Roll, pitch and heave motions and forward speed reduction during the turning maneuver with different rudders were computed and compared. Results show that the rudder profiles designed specifically for marine applications (Fishtail, IFS and HSVA) perform better than the traditional NACA series. 相似文献
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A study is conducted to estimate the accurate attitude of a ship's motion and the estimation is used to arrive at the corrections required for a farfield pattern of a coaxial circular array. The relevant analytical expression is developed for the computation of moving average filter weights to estimate the ship's attitude for beamsteerings at different sea conditions. Farfield patterns are presented for different steered directions for the coaxial circular array of the additive type, and the multiplicative array technique is also used for beamsteering for higher steering angles to observe its control on the sidelobes as well as for the main beamwidths. In order to introduce an adaptive filter to estimate the accurate attitude for stable sonar platform, an adaptive parameter is examined for bathymetric applications where nonstationary ship movement prevails. 相似文献
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The PDFs (probability density functions) and probability of a ship rolling under the random parametric and forced excitations were studied by a semi-analytical method. The rolling motion equation of the ship in random oblique waves was established. The righting arm obtained by the numerical simulation was approximately fitted by an analytical function. The irregular waves were decomposed into two Gauss stationary random processes, and the CARMA (2, 1) model was used to fit the spectral density function of parametric and forced excitations. The stochastic energy envelope averaging method was used to solve the PDFs and the probability. The validity of the semi-analytical method was verified by the Monte Carlo method. The C11 ship was taken as an example, and the influences of the system parameters on the PDFs and probability were analyzed. The results show that the probability of ship rolling is affected by the characteristic wave height, wave length, and the heading angle. In order to provide proper advice for the ship''s manoeuvring, the parametric excitations should be considered appropriately when the ship navigates in the oblique seas. 相似文献
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Compliance with international emission regulations: Reducing the air pollution from merchant vessels
In September 1997, the International Maritime Organization (IMO) adopted an international convention protocol to reduce air pollution from ships, in order to achieve sustainable maritime development. This protocol has been approved by 15 member countries and will be enforced in May 2005. Pollutants emitted from ships, such as nitrogen oxides, volatile organic compounds, sulfur oxides, etc. will be regulated by this convention through ship inspections and issuance of certificates. Ships belonging to maritime countries such as Taiwan, which sail around the world and berth in commercial ports, must obey this convention. This study has investigated possible strategies, which may be adopted by maritime countries to conform to this IMO convention in order to reduce the air pollution from ships. A sea-going ship must prepare EIAPP and IAPP certificates for inspection by port-state-control officials, when the ship is anchored at a maritime port. These port-state-control officials may also require the continuous detection and sampling of a ship's emissions, while it is berthed at the port. Legislative support is necessary for successful implementation of these safeguards. It is suggested, therefore, that the administration of both navigational and environmental protection, in maritime countries, cooperate in the revision of relevant federal laws, to implement the provisions of the MARPOL 73/78/97 convention; in this way, the air pollution from ships can be effectively controlled. Installation of advanced detection equipment can effectively detect any ships’ violations of air pollution regulations. The Harbor Affairs’ Bureau should also establish a database of air pollution inspections for ships berthed within their harbor, requiring that ships’ equipment comply with the requirements of the MARPOL convention, for the reduction of air pollution. 相似文献
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The energy efficiency of ocean-going vessels can be increased through various operational considerations, such as improved cargo arrangements and weather routing. The first step toward the goal of maximizing the energy efficiency is to analyze how the ship's powering performance changes under different operational settings and weather conditions. However, existing analytical models and empirical methods have limitations in reliably estimating the powering performance of full-scale ships in real operating conditions. In this study, machine learning techniques are employed to estimate the powering performance of a full-scale ship by constructing regression models using the ship's operational data. In order to minimize the risk of overfitting in the regression process, domain knowledge based on physical principles is combined into the regression models. Also, the uncertainty of the estimated performance is evaluated with consideration of the environmental uncertainties. The obtained regression models can be used to predict the ship speed and engine power under different operational settings and weather conditions. 相似文献