共查询到19条相似文献,搜索用时 187 毫秒
1.
2.
金枪鱼围网渔船技术经济分析 总被引:2,自引:0,他引:2
对金枪鱼围网渔船作了技术经济分析,指出金价与资源情况对金枪鱼围网渔船的净现值(NPV)有着较大的影响,燃油价与渔港至渔场的距离对NPV只有中等程度的影响,停港天数及造价系数对NPV的影响不大;同时围网渔船相对于每种鱼价,每种资源情况及每种渔港至渔场的距离都有一最佳船型区。 相似文献
3.
渔船船型技术经济论证目的,在于根据作业渔场的实际情况,在总结现有船舶使用经验的基础上,考虑到未来的发展趋势,结合新设计船的建造目的,通过对多船型方案的技术经济指标的比较分析,提出在技术上先进而又可行的,营运上经济合理的船型方案。 相似文献
4.
5.
本文指出在制定渔船技术设计任务书时,应把渔船、渔场、渔港与渔业市场视为一系统,进行经济性分析,并考察鱼价、油价,资源情况,渔港至渔场距离与停港天数等不确定性因素对渔船经济性的影响。还提出了应用分层序列搜索法以准确迅速地得到全域最优解。文中给出了一远洋拖网渔船技术设计任务书制定的示例。 相似文献
6.
7.
在分析拖虾船型线特征的基础上,利用母船改造法设计4种横剖面面积曲线,插值产生新船船体型线,采用FLUENT软件对4种船型进行三维船体数值模拟,得到相应速度下的阻力值,对比确定优化船型.以实际运营的36.80 m拖虾船为例,说明本文的方法在减轻设计人员工作强度、提高设计效率和设计质量方面可以起到积极的作用,加快拖虾渔船节能船型开发及标准化建设步伐. 相似文献
8.
本文介绍了用模矢法,单纯形以及Powell方法,根据渔场资源,鱼价,燃油价等因素寻求最佳拖网渔船船型的方法。对于赴多渔场捕捞的最佳拖网船船型而言,首先用直接搜索法加上Expand法找出相应于各个渔场的最佳船型,在这些船型中的最大主机功率与最小主机功率范围内,以MonteCorlo模拟法随机计算各该主机功率的船型通过多渔场作业后的经济效益,从而确定出最佳船型。 相似文献
9.
10.
11.
12.
A new index, namely the overall motion induced interruptions (OMII), is proposed as a seakeeping criterion for fishing vessels, to compare ships having different hull forms and dimensions by means of an only parameter, in a human centred approach, mainly related to the onboard risk level. Therefore, the first aim of the paper is to investigate the factors affecting fishing vessels’ seakeeping performances to improve them to reduce the high number of injuries occurring during fishing operations, mainly related to both risk perception and harsh weather conditions. Despite the classical approach, where motion induced interruption is determined for a certain sea state with regard to several location points, the new index accounts for all crew members’ positions on the working deck, all heading angles the vessel may experience during fishing operations, based on relevant operating scenario, and all sea states the ship may encounter in the fishing area. The influence of position, heading angles and sea states on the attained risk level is fully investigated, analysing seakeeping performances of four fishing vessels with different hull forms and dimensions. Finally, a new operability criterion is proposed, based on OMII, to investigate the influence of ship size and operating scenario on the risk of injuries during fishing operations. Main factors affecting fishing vessels’ seakeeping performances are fully discussed, paying attention to relevant correlation with ship roll natural period. 相似文献
13.
14.
A hypothesis of the minimum energy of secondary flow, suggested by Bessho, is introduced here. According to this hypothesis, it can be expected that hull forms having frame lines with a minimum energy of secondary flow show less form drag. In the first part of this article, secondary flow energy is evaluated for the cases with and without a free-surface effect, and Bessho’s hypothesis is confirmed for practical hull forms. Then optimization methods for the stern hull form are suggested, in which a nonlinear optimization technique is introduced. Numerical examples are given for a practical tanker hull form and a practical container hull form. From these studies, the suggested optimization method can be confirmed as a simplified and practical design method to the select frame lines of stern hull forms. 相似文献
15.
基于潜艇模型尾流湍流强度和耗散率的CFD模拟 总被引:1,自引:0,他引:1
优良的隐身性能使得潜艇具有强大的突防能力,因此,控制潜艇尾流信号特征对于提高潜艇隐身性能意义重大,这些信号特征主要包括尾部湍流强度、湍动能、湍流耗散率等。同时,优良的艇型对于抑制尾流信号特征、提高潜艇快速性和隐身性也具有重要意义。基于此,采用RANS方法计算SUBOFF潜艇主艇体艇型及6种改良艇型的艇体粘性绕流,将CFD方法用于分析艇体半径、艇艏长度、艇艉长度等参数对潜艇尾流信号特征的影响。计算结果显示:在SUBOFF潜艇主艇体艇型及其6种改良艇型的尾流场中,增加艇体半径有利于抑制远尾流场湍流信号特征,在近场则不利;增加艇艏长度能降低近尾流场湍流信号特征,在远场影响较小;增加艇艉长度在近、远尾流场均有利于降低其信号特征。 相似文献
16.
基于主要尺度要素的船型变换 总被引:1,自引:0,他引:1
针对船舶设计优化过程中性能计算提出一种船型变换方法,以7个主要尺度要素为变量改变船型,由母型船快速派生出系列船型,并以某三体船主体为示例,阐述船型变换的基本原理. 相似文献
17.
The prediction of a ship's resistance especially the viscous wave-making resistance is an important issue in CFD applications. In this paper, the resistances of six ships from hull 1 to hull 6 with different hull forms advancing in still water are numerically studied using the solver naoe-FOAM-SJTU, which was developed based on the open source code package OpenFOAM. Different components of the resistances are computed and compared while considering two speed conditions(12 kn and 16 kn). The resistance of hull 3 is the smallest while that of hull 5 is the largest at the same speed. The results show hull 3 is a good reference for the design of similar ships, which can provide some valuable guidelines for hull form optimization. 相似文献
18.
Hussein M. Alidina 《Coastal management》2013,41(4):459-470
The current regime of fisheries management and the prospects for attaining a more locally oriented, collaborative system of fisheries management in Diani-Chale, Kenya are examined. At present fisheries management in Diani-Chale is characterized by diminished government capacity for regulation, weakened local institutions, and little ability to exert control over the use of fisheries. Local level management requires the development and use of local institutions that can govern the use of fishery resources. The fish landing sites used by fishers and their associated fishing grounds were identified to be at the appropriate level for resolving fishery management issues. A more formal role for these entities, the clarification of fishing ground tenure and access rights, and support for the development and enforcement of local fishing rules can further local management. The socioeconomic condition of fishers, their fear of losing landing sites, and the continued perception of the imposition of a marine reserve pose barriers to initiatives seeking to further local level management. 相似文献
19.
The prediction of a ship's resistance especially the viscous wave-making resistance is an important issue in CFD applications. In this paper, the resistances of six ships from hull 1 to hull 6 with different hull forms advancing in still water are numerically studied using the solver naoe-FOAM-SJTU, which was developed based on the open source code package OpenFOAM. Different components of the resistances are computed and compared while considering two speed conditions (12 kn and 16 kn). The resistance of hull 3 is the smallest while that of hull 5 is the largest at the same speed. The results show hull 3 is a good reference for the design of similar ships, which can provide some valuable guidelines for hull form optimization. 相似文献