共查询到19条相似文献，搜索用时 127 毫秒
1.
提出了基于风险的海洋结构物无损检测功能分级方法，采用检测概率、错误识别概率和裂纹出现概率度量检测功能，并修正了错误识别概率的取值范围。根据风险值对无损检测功能进行了分级，研究了风险值随检测概率、错误识别概率和裂纹出现概率的变化规律，分析了风险值对检测费用、维修费用及失效费用的敏感性。在此基础上，将基于风险的海洋结构物无损检测功能分级方法应用于优化检测策略，用算例证明了文中所提方法的有效性。 相似文献
2.
为提高波能转换装置的生存能力,提出了一种新型的船体摆式波能转换装置:将所有活动部件封装在船体中,避免海水腐蚀;装置漂浮在海上,依靠船体与内部摆的相对转动转换能量,减少海工结构成本,便于拖曳回港口维修;采用液压PTO将机械能转换成电能输出。使用Fluent软件搭建数值波浪水槽,分析抛物线、双曲线、椭圆三种外形装置的水动力特性,并进行外形优化,结果表明:三种外形的船体摆式波能转换装置在波浪中均能够产生垂荡、纵荡、纵摇运动的动力,发电原理可行;船体采用不对称结构能够对波浪起到截止作用,减小能量向后辐射,光滑曲线外形可以减小旋涡造成的能量损失;椭圆形船体能够获得更大的纵摇水力矩,捕能效果更好。 相似文献
3.
缓波型立管由于设计参数较多且优化目标之间相互影响，设计结果具有很大的不确定性。随着代理模型和智能优化算法的发展，针对缓波型立管的优化可以提出更好的解决方案。以提高力学性能和经济效益为优化目标，采用基于Kriging插值模型和NSGA-II算法的多目标优化策略，对考虑顶部浮体影响的深水缓波型立管进行动力响应分析，并开展线型—截面双目标优化集成设计和线型—浮筒三目标优化集成设计。将处于不同几何尺度的设计变量进行集成，旨在各目标存在相互竞争的情况下，与截面、浮筒设计形成有效互动以提高线型设计的总体性能。结果表明，Pareto最优解集可提供多个选择方案，以满足工程实际需要。将所选最优方案与初始设计进行对比，并以疲劳性能和成本估算作为优化的校核指标，取得了理想的优化效果。 相似文献
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在解析YOLOv4算法基础上,针对应用YOLOv4算法检测遥感影像桥梁目标任务中出现的训练耗时严重及精度较低缺陷,从算法训练过程和结构模块两方面进行优化:使用多尺度训练以及fp_16训练策略降低算法训练成本,并引入SE模块和CBAM模块两种注意力机制提升算法检测精度。消融实验结果表明:优化训练策略能够有效降低算法训练成本,同时提高目标检测精度;相比较CBAM模块,SE模块对算法训练成本增加较小却能收获显著的检测精度提升,优化训练策略并嵌入SE模块的算法,使高分桥梁数据集和DOTA桥梁数据集的平均准确率分别提升1.4%和3%。该优化算法兼具效率和精度优势,为桥梁目标检测难题提供有效解决方法。 相似文献
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航路规划指在有障碍物的环境中,为无人平台规划出无碰撞的最优路径。以水下定位为任务的航路规划为水下无人平台规划出高定位精度指标的最优路径,对于提高水下无人平台的工作效率至关重要。 传统的水下无人平台航路规划主要基于人工势场法、蚁群法、遗传算法等,在这些算法中主要考虑的是避障问题,而没有充分考虑载荷任务,因此任务执行效率低。特别是对于水下定位任务,由于定位精度受到航路影响较大,因此需要对定位精度进行优化。针对这一问题,结合人工势场法与定位精度,提出了一种定位精度优化驱动的水下无人平台航路规划方法,实现了对避障能力与定位任务能力的兼顾,提高了基于水下无人平台的定位精度。 相似文献
6.
球柱组合壳是单壳体潜艇耐压船体结构的主要形式,其结构在极限载荷作用下的极限承载能力和变形是评估潜艇结构安全性的重要指标。 在试验模型基础上,根据三维实测初挠度数据建立含缺陷的球柱组合壳有限元模型,将极限强度计算结果与试验数据对比分析,结果表明:上述数值方法准确可靠,且缺陷的引入对于工程上潜艇结构的极限承载能力评估具有实际意义。 相似文献
7.
浮式生产储油船船体疲劳计算 总被引：2，自引：0，他引：2
船体结构的疲劳问题一直是船舶设计者十分关注的问题，特别是高强度钢在船体结构中的广泛使用，使船体结构的疲劳破坏问题更加突出。本文以一大型浮式生产储油船（Floating Production and Storage and Offilading)为例，系统地介绍了一种基于S－N曲线和Miner线性疲劳累积损伤原理，计算船体在局部结构应力热点处的疲劳寿命。该方法考察了船舶运营期内的实际工况和海况条件，船体局部应力热点的焊接情况，几何形状，受载形式以及尺寸效应等因素。计算中借助了DNV船级社的SESAM程序系统的部分模块。 相似文献
8.
基于过程系统综合的方法，对采用多级反渗透工艺的海水、苦咸水淡化系统的设计进行了研究。首先，建立1个包括所有可行设计方案的超结构模型，同时采用本文提出的膜组件模型来近似描述当中的反渗透单元的分离过程。该单元模型考虑了膜元件中的压降和浓差极化。然后给出了相关的经济模型，将投资费用、操作费用和设计变量相关联。以年费用最小为目标，将系统的设计问题表达为1个混合整数非线性规划（MINLP）。对此数学规划问题进行求解，可得到最优的反渗透结构，操作条件，以及每个压力容器中最恰当的膜元件数。对几个苦咸水淡化的实例进行设计，得到较高的产水率，吨水费用比没有进行结构优化的情况低10％-15％，表明这种方法是有效的。 相似文献
9.
近年来，拖网渔船捕捞成本不断上升，经济效益受到影响，捕捞成本和收益成为渔民最为关心的问题。文章依据2018年荣成、象山和北海的调研数据，对3个海区拖网渔船的成本收益进行分析。结果显示：在成本结构方面，油、冰、水支出占比最大，其次是雇工支出；在收益结构方面，捕捞生产收入占了绝大部分比重；在经济效益方面，利润由高到低依次为象山、荣成和北海，但总体来看利润都较低；在盈亏平衡和敏感性分析中，荣成拖网渔船捕捞风险最高，而北海拖网渔船更容易受到市场波动的影响，规避市场风险的能力最弱。基于此，拖网渔业渔船通过渔业合作社集中购买柴油的方式，以及使用现代捕捞设备等途径来降低成本，提高捕捞效益。渔业相关部门应完善相应的补贴政策，同时也要重视对渔民捕捞技术的培训，提高产品附加值以及加强对渔业资源养护与管理。 相似文献
10.
可靠性约束下的海底油气集输管网系统优化 总被引：1，自引：0，他引：1
在管网系统满足一定可靠度的基础上，以费用最小为优化目标，对系统进行了优化，求出了满足一定可靠度指标的费用最小的管网布置方案。对树状网络可靠性进行了评估，提出了一个0-l规划模型，并运用图论和网络理论将管网系统的优化问题转变为求可靠度至少为α的网络固的最小生成树问题。 相似文献
11.
Owing to high costs and unnecessary inspections necessitated by the traditional inspection planning for ship structures, the risk-based inspection and repair planning should be investigated for the most cost-effective inspection. This paper aims to propose a cost-benefit assessment model of risk-based inspection and repair planning for ship structures subjected to corrosion deterioration. Then, the benefit-cost ratio is taken to be an index for the selection of the optimal inspection and repair strategy. The planning problem is formulated as an optimization problem where the benefit-cost ratio for the expected lifetime is maximized with a constraint on the minimum acceptalbe reliability index. To account for the effect of corrosion model uncertainty on the cost-benefit assessment, two corrosion models, namgly, Paik＇ s model and Guedes Soares＇ model, are adopted for analysis. A numerical example is presented to illustrate the proposed method. Sensitivity studies are also providet. The results indicate that the proposed method of risk-based cost-benefit analysis can effectively integrate the economy with reliability of the inspection and repair planning. A balance can be achieved between the risk cost and total expected inspection and repair costs with the proposed method, which is very. effective in selecting the optimal inspection and repair strategy. It is pointed out that the corrosion model uncertainty and parametric uncertaintg have a significant impact on the cost-benefit assessment of inspection and repair planning. 相似文献
12.
Risk Based Optimal Inspection and Repair Planning for Ship Structures Subjected to Corrosion Deterioration 总被引：1，自引：1，他引：1
A framework of risk based inspection and repair planning was presented to optimize for the ship structures subjected to corrosion deterioration. The planning problem was formulated as an optimization problem where the expected lifetime costs were minimized with a eonstraint on the minimum aceeptable rehability index. The safety margins were established for the inspection events, the repair events and the failure events for ship struetures. Moreover, the formulae were derived to calculate failure probabihties and repair probabilities. Based on them, a component subjected to corrosion is investigated for illustration of the process of selecting the optimal inspection and repair strategy. Furthermore, some sensitivity studies were provided. The results show that the optimal inspection instants should take place before the reliability index reaches the minimum acceptable reliability index. The optimal target failure probability is 10^-3. In addition, a balance can be achieved between the risk cost and total expected inspection and repair costs by means of the risk-based optimal inspection and repair method, which is very effective in selecting the optimal inspection and repair strategy. 相似文献
13.
A model is given for the planning of the inspection and maintenance operations of a system: an application to an offshore structure is described. The objectiveis to minimize the total cost of inspections and consequences of failures, subject to an upper boundon the total failure probability of the system. An incremental algorithm is defined for the approximate solution of the problem, and a method is described for the evaluation of the quality of any feasible solution in terms of bounds of the optimal objective value. The incremental algorithm solves the problem parametrically for certain values of the system reliability. The model has been applied to obtain an optimal inspection plan against the consequences of gross errors, accidental events, fatigue and corrosion in terms of input describing element importance values, element reliability values, error detection probabilities, error detection costs and error repair costs for parametrical variations of the structural reliability. 相似文献
14.
多障碍环境中基于增强式学习的势场优化和机器人路径规划 总被引：3，自引：0，他引：3
该文把增强式学习方法应用于多障碍环境中机器人路径规划 ,并将增强式学习和路径规划相结合 ,通过工作空间势场的自适应优化学习 ,实现机器人的全局路径规划 ,即得到从任何初始位置开始的最优路径。与传统的人工势场方法相比 ,该方法避免了势场中局部极小点所引起的陷阱区域 ,并且所得到的路径具有最优特性。计算机仿真实验结果表明 ,这种学习方法能有效的解决多障碍环境中的机器人路径规划问题 相似文献
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16.
Time-Variant Reliability Analysis of FPSO Hull Girder Considering Corrosion Based on Statistics 总被引：1，自引：0，他引：1
FPSO is a kind of important exploitation platform used in ocean oil and gas industry, which has the unique character of mooring at outsea for a long time. Since it can not be inspected and maintained thoroughly at dock like other kinds of ships, the reliability of FPSO hull girder during the whole service should be focused. Based on latest corrosion database and rational corrosion model, the ultimate strength of one FPSO is calculated under the conditions of slight, moderate and severe corrosion. The results not only provide the reliability under different corrosion conditions, but also do well for further inspection and maintenance research. The results provide necessary foundation for deciding inspection intervals and maintenance measures, which has practical sense to improve the general safety level of ocean engineering. 相似文献
17.
In this paper, a hierarchical control framework with relevant algorithms is proposed to achieve autonomous navigation for an underactuated unmanned surface vehicle (USV) swarm. In order to implement automatic target tracking, obstacle avoidance and avoid collisions between group members, the control framework is divided into three layers based on task assignments: flocking strategy design, motion planning and control input design. The flocking strategy design transmits some basic orders to swarm members. Motion planning applies the potential function method and then improves it; thus, the issue of autonomous control is transformed into one of designing the velocity vector. In the last layer, the control inputs (surge force and yaw moment) are designed using the sliding mode method, and the problem of underactuation is handled synchronously. The proposed closed-loop controller is shown to be semi-asymptotically stable by applying Lyapunov stability theory, and the effectiveness of the proposed methodology is demonstrated via numeric simulations of a homogeneous USV swarm. 相似文献
18.
Considering the dynamic changes of unmanned surface vehicle (USV) in berthing tasks, the planning and control modes are divided into two phases: the remote phase and the terminal phase. According to the main influencing factors of the two phases, an improved artificial potential field method is proposed to complete autonomous berthing trajectory planning based on the analysis of environment constraint, berth point constraint and USV’s dynamics constraint. Combining with the dynamic characteristics and control objectives at different phases of berthing and analyzing the fuzzy rule regulation strategy of USV’s heading and speed control, an improved adaptive fuzzy PID control method is proposed to solve the control problem of USV, which is influenced by weak maneuver, large disturbance, limited water area and strong shore effect. Finally, the comparative test of berthing simulation verifies the superiority of the proposed control method. The autonomous berthing field experiment is completed based on the "Dolphin-I" small USV. It verifies the validity and feasibility of the proposed autonomous berthing method. 相似文献
19.
远洋运输系统人因可靠性定量分析 总被引：2，自引：0，他引：2
远洋运输中可能发生的灾害性事故,如船舶碰撞、搁浅、腐蚀疲劳破坏、火灾、爆炸等,大多与人为失误和组织失误（HOE）有关.因此,进行远洋运输系统人因可靠性定量分析,对于运输系统的安全非常重要.针对此问题,文章结合操作风险管理（ORM）技术,对远洋运输系统进行人因可靠性定量分析.为远洋船舶提供了一套预测人为误操作的分析方法,可以降低HOE风险的发生概率,以减小事故的发生. 相似文献