共查询到20条相似文献,搜索用时 234 毫秒
1.
The scattering problem involving water waves by small undulation on the porous ocean-bed in a two-layer fluid,is investigated within the framework of the two-dimensional linear water wave theory where the upper layer is covered by a thin uniform sheet of ice modeled as a thin elastic plate.In such a two-layer fluid there exist waves with two different modes,one with a lower wave number propagate along the ice-cover whilst those with a higher wave number propagate along the interface.An incident wave of a particular wave number gets reflected and transmitted over the bottom undulation into waves of both modes.Perturbation analysis in conjunction with the Fourier transform technique is used to derive the first-order corrections of reflection and transmission coefficients for both the modes due to incident waves of two different modes.One special type of bottom topography is considered as an example to evaluate the related coefficients in detail.These coefficients are depicted in graphical forms to demonstrate the transformation of wave energy between the two modes and also to illustrate the effects of the ice sheet and the porosity of the undulating bed. 相似文献
2.
3.
美国、英国、埃塞俄比亚等多国科学家目前透露,位于非洲东北部与阿拉伯半岛之间的红海正在发生分裂,数百万年之后可能将产生一个新的海洋,而非洲大陆也将分成两部分.这个研究成果证实了目前普遍认同的大陆板块构造学说. 相似文献
4.
杨成才,从大学毕业分配至中波轮船股份公司,仅用短短7年时间就成长为中波公司最年轻的优秀轮机长。扎实深厚的理论功底,刻苦钻研的探索精神,踏实肯干的工作作风以及对远洋运输事业的热爱与执着,是他快速脱颖而出的源泉。他曾先后荣获全国交通系统青年岗位能手,中央企业知识型先进职工,第三届中远集团十大杰出青年等荣誉称号。 相似文献
5.
军工科技档案是武器装备研制单位在从事军工科技活动中形成的原始记录,是重要的国家和国防科技财富,是军队列装技术和国防储备技术的重要信息源.做好军工科技档案保密工作事关党和国家的根本利益,事关军队的安危,事关军工科技事业发展的全局,我们一定要从政治和战略的高度,充分认识此项工作的极端重要性. 相似文献
6.
学习贯彻十七大精神,对于动员拿党全国各族人民,存以胡锦涛同忠为总书记的党中央坚强领导下,高举中国特色社会主义伟大旗帜,奋力夺取全面建没小埭社会新胜利、圩创中国特色礼会主义事业新局而,具有重大现实意义和深远历史意义。长汀航道各级党组织要把组织学习和贯彻落实十七大精神作为当前和今后一个时期的首要政治任务,迅速把干部职工的思想和行动统一到全会精神上来, 相似文献
7.
0引言近年来全球集装箱运量的年增长率基本维持在10%以上,据初步统计2007年全球集装箱运量达1.3亿TEU,港口吞吐量达4.7亿TEU。随着集装箱制造、装卸工艺的改进,适箱货物的范围也在不断扩大。20世纪90年代,美国就开始采用集装箱运 相似文献
8.
<正>众所周知,三一重工股份有限公司是一家享有盛誉的上市公司,曾连续4年上榜中国最具价值品牌,是工程机械行业内的标志性企业之一。作为中国最具科研实力的工程机械制造商,三一重工拥有国家级技术中心、博士后工作站,并承接有国家863课题,取得专利400多项。三一重 相似文献
9.
10.
11.
12.
仿真在造船企业管子生产物流系统中的应用 总被引:2,自引:1,他引:2
以某造船企业管子分厂产能评估为应用背景,针对生产过程为多班制、多工艺、多工序、混合作业的复杂生产方式,将生产物流仿真系统分为输入层、仿真层、输出层三个层次,采用面向对象的仿真技术,把管子生产物流中的各种要素分为不同的类,构建了管子生产物流系统的仿真模型.并对管子分厂生产能力在不同工况条件下,在不同生产调度策略下分别进行了评估.通过仿真评估帮助决策者制定出最佳的决策,提高生产能力. 相似文献
13.
Kazuhiro Aoyama Toshiharu Nomoto W Kentaro 《Journal of Marine Science and Technology》1999,4(1):35-43
There are many restrictions on production in the factory. The most efficient production schedule should be planned taking
these restrictions into account. Professional skill is necessary to plan the best schedule. A schedule planner has to deal
with so much information during production planning that it is difficult to plan the best production schedule with a consideration
of so many restrictions. In this study we introduced the use of Petri nets to support such production planning with a computer.
Petri nets have been widely used to simulate production because of their capability of modeling concurrency, synchronization,
and sequencing in discrete-event systems. This paper reports on implementing a simulation system for the shipyard. We had
already implemented a production planning support system for a shipyard that is a part of the computer integrated manufacturing
(CIM) system in shipbuilding. Based on this system, we implemented a shipyard simulator that can simulate the production activity
in the shipyard. We therefore have defined a shipyard model. The production conditions can be changed, and the efficiency
of a schedule can be evaluated. This paper discusses the effectiveness of using a factory simulator.
Received for publication on Oct. 5, 1998; accepted on May 12, 1999 相似文献
14.
论现代造船体制的特征和实践 总被引:5,自引:1,他引:4
中国一流船厂的造船综合生产效率仅为国际水平的十几分之一。症结在于尚未建立起符合成组技术原理的现代造体制,笔者认为,混合工种的生产组织,流通量控制的生产管理,分道布置的生产流程和壳舾涂一体化的作业方法是现代造船体制之基本特征,其实质是柔性化的流水生产,笔者提出了以理论研究为牵引,造船之首道工序为起点,从改革最基层的生产组织,建立“微型工厂”做起的实施思路,同时,论述了结合江南造船厂新建管子车间,广州 相似文献
15.
16.
在船舶管路系统设计中,弯管数量占管子总数的一半以上,管系的设计和加工直接影响到造船的进度和产量。采用矢量代数理论建立了完整的管子设计模型和计算公式,并就轮机专业工程师在TRIBON系统中进行管路放样给出了一种简易的三角函数方法和计算机电子表格程序。 相似文献
17.
针对造船生产的特点,提出利用EXTEND仿真软件及其遗传算法模块对车间作业调度问题进行优化和仿真的方法,为解决这类生产计划与调度问题提供新的方法和途径。 相似文献
18.
To implement efficient production control, this paper provides a timed colored Petri net (timed CPN) approach to performance modeling, real-timed dispatching and simulation of Panel hull block assembly system (PHBAS). The definition of Petri net is extended to accord with the real-world PHBAS’s organization, and the modeling method for hull flow production is provided in order to simplify modeling program. Using modeling and analyzing method, the dynamic characteristics of the system can be emulated and quantitatively calculated and work control tactics can be optimized. For the double bottom hull block shipbuilding system in a recently built shipyard in China, the simulation model with timed CPN was described and the system parameters and optimal task sequence which has the minimum operation time were obtained for a scheduling case. 相似文献
19.
20.
为了提高船舶中小组立等中间产品建造作业调度能力,提升船舶建造效率,提出面向多约束的船舶组立建造作业调度方法。首先,分析船舶组立建造的工艺流程和作业调度方法,综合考虑机器小组、工艺和交货期等多种约束条件,以建造周期最短为调度目标,建立船舶组立建造作业调度数学模型;其次,综合运用算法分解策略及调度规则,设计改进的最短作业优先调度算法实现模型求解;最后,以某船厂建造车间一定生产周期(17天)的中小组立先行中日程计划为对象,验证该方法的有效性和实用性。研究结果表明,所提出的面向多约束的船舶组立建造作业调度方法相较于当前的调度方法,排产周期压缩22小时,即缩短了原有周期的16.18%,有效提高了生产计划排产和作业调度效率。 相似文献