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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.
近年来,受各种因素的影响,海峡东岸高雄港的国际集装箱中转港和世界大港地位受到挑战,尤其是来自西岸厦门港的威胁。本文从高雄和厦门两港的地理位置出发,对两港的港航条件、外部环境和吞吐量格局进行了比较分析。  相似文献   

3.
《机电设备》2007,24(4):I0010-I0011
海一鸥游艇有限公司是代理销售国外知名船艇并提供相关服务及设施的专营公司.海一鸥游艇有限公司注册于上海,分别在北京、大连、青岛、深圳设有分公司,在广州设有分销商.  相似文献   

4.
《机电设备》2007,24(8):I0005-I0005
由国家自然科学基金、王宽诚基金、美国电气电子工程师学会(IEEE)和日本香川大学等资助,哈尔滨工程大学承办的"2007IEEE机电一体化及自动化国际会议"8月6日在哈尔滨市香格里拉饭店开幕.来自中、美、日、韩、加等27个国家和地区的500余名代表出席会议,其中有近200名国外代表,国防科工委副主任金壮龙,黑龙江省委常委、省科技厅厅长孙尧出席大会并致辞.会议共收到来自33个国家和地区的投稿论文1861篇.经过国内外专家的严格审阅和定稿,最终录用701篇,采用率不到37%.  相似文献   

5.
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   

6.
张成  袁兵 《集装箱化》2008,19(2):24-27
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   

7.
<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   

8.
美国海岸警备队港口长官(COTP)或口岸当局(OCMI)对存在缺陷的船舶,根据缺陷的严重性,决定对这些船舶采取控制行动来保证船舶、港口和环境的安全,至于控制的程度、范围以及当局的执行力则和这些缺陷的本性一致.  相似文献   

9.
Global strength is a significant item for floatingproduction storage and offloading (FPSO) design, and steel weightplays an important role in the building costs of FPSO. It is the maintask to consider and combine these two aspects by optimizing hulldimensions. There are many optional methods for the globalstrength analysis. A common method is to use the ABS FPSOEagle software to analyze the global strength including the rulecheck and direct strength analysis. And the same method can beadopted for the FPSO hull optimization by changing the depth.After calculation and optimization, the results are compared andanalyzed. The results can be used as a reference for the futuredesign or quotation purpose.  相似文献   

10.
For a large floating vessel in waves,radiation damping is not an accurate prediction of the degree of roll unlike other degrees of freedom motion.Therefore,to get the knowledge of roll motion performance of deepwater pipelay crane vessels and to keep the vessel working safety,the paper presents the relationship between a series of dimensionless roll damping coefficients and the roll response amplitude operator(RAO).By using two kinds of empirical data,the roll damping is estimated in the calculation flow.After getting the roll damping coefficient from the model test,a prediction of roll motion in regular waves is evaluated.According to the wave condition in the working region,short term statistics of roll motion are presented under different wave parameters.Moreover,the relationship between the maximal roll response level to peak spectral wave period and the roll damping coefficient is investigated.Results may provide some reference to design and improve this kind of vessel.  相似文献   

11.
This primary objective of this paper is to examine the causes for the change in energy consumption in the transport sector in India. The pattern of energy consumption and their causes for change are benchmarked against select countries. A mathematical model that decomposes changes in energy consumption to various factors has been used. The changes in the energy consumption are attributed to growth in transport volume, structural change or modal shift, and energy intensity. The analysis is conducted for passenger and freight transport separately. Results indicate that the growth in transport volume has been the main cause for increase in energy consumption for both passenger and freight transport in India despite the decline in energy intensity of various transport modes. Though not surprising for a growing economy like India, this poses a challenge for the future. Currently, India is a low carbon economy.  相似文献   

12.

Transferring decision-making process from central to local government and enhancing the role of local communities in managing coastal zones is an increasing commitment by governments in Southeast Asia. This article analyzes decentralized coastal zone management in two neighboring countries, Malaysia and Indonesia. The Federal system in Malaysia is argued to be able to influence more decentralized coastal zone management and to promote community-based management approaches. Meanwhile, the large diversity of coastal resources and communities combined with a still as yet tested decentralization policy in Indonesia is argued to bring more challenges in implementing the decentralization and community-based approaches in coastal zones. The lessons learned in this study provide insight in how far decentralized coastal zone management has taken place in Malaysia and Indonesia. The significant differences in the pattern of coastal zone management in these two countries are discussed in detail. This study recognizes that co-management and community-based approaches can be appropriate in dealing with coastal zone management. This comparative perspective is important to the development of a bigger picture of sustainable coastal zone management processes and cross-regional knowledge-sharing in Southeast Asia.  相似文献   

13.
通过分析近年来土工合成材料在长江口深水航道、洋山港、太仓港、吕四港、宁波港、曹妃甸等具有代表性的堤坝工程中的应用情况,系统总结了土工合成材料在堤坝工程中的应用经验,可对同类工程有所借鉴.  相似文献   

14.
港口集装箱起重机钢丝绳使用情况调查与分析   总被引:3,自引:3,他引:0  
24个码头的 5 0 0多台集装箱起重机的钢丝绳使用情况表明 ,国内港口所用钢丝绳的品牌规格较多 ,其中日本产品和国内产品的市场占有率较高 ,国内产品的消耗量最大 ;进口产品的性能普遍较好 ,而国内产品则性能质量差异较大 ,除少数品牌外 ,使用寿命较短 ;各国内部品牌之间的价格接近 ,欧洲产品价格最高 ,国产品牌价格低廉  相似文献   

15.
风浪中螺旋桨水动力变化规律是研究舰船在风浪中速航性能的重要方面。本文参照有关文献,提出了一种计算风浪中螺旋桨推力、转矩损失的实用定量计算方法,既可用于较精确地估算舰船在风浪中的增阻和失速,还可供提高舰船在风浪中速航性的研究和螺旋桨设计参考。  相似文献   

16.
This paper provides an up-to-date review of the previous literature concerning the impact of passenger rail franchising on productivity and costs in Britain, and also presents important new evidence. In particular, the extension in time of previously-used datasets offers the first opportunity to study the impacts of re-franchising. The previous literature emphasised the failure of franchising to produce sustained productivity gains, with a sharp deterioration in productivity after 2000. The new evidence presented offers a somewhat more positive view of the British experience. It suggests that part of what was previously considered to be falling productivity may in fact be due to exogenous changes in diesel prices. Further, new data suggests that the recent increases in costs have resulted in higher quality of service. Finally, competitive re-franchising, and the associated unwinding of short-term management and re-negotiated contracts, seems to have led to improvements in productivity between 2006 and 2008. Nevertheless, it remains the case that passenger rail franchising in Britain has failed to reduce costs in the way experienced in many other industries and in rail in other European countries. The evidence is that somewhat larger franchises, avoiding overlapping and optimising train density and length, should reduce costs. We also speculate that the major increase in wages and conditions of staff might be moderated by longer franchises, although that remains to be proved. This re-appraisal of the British case is important in the context of the wider international interest in the use of franchising in passenger rail, and its relevance to the current review of ways of introducing competition into the domestic rail passenger market in Europe.  相似文献   

17.
航道护岸工程中基槽边坡稳定研究   总被引:1,自引:1,他引:0  
航道护岸工程中经常发生基槽边坡滑坡失稳事故,从而造成经济和安全问题。因此,就滑坡发生机理进行研究对保障航道护岸工程顺利建设有重大意义。从极限平衡原理出发,分别运用Fellenius法和Bishop法验算了苏北某航道护岸工程开挖边坡的设计稳定性,并分析比较两种方法的差异,得出了在多层土的计算中有时会出现Fellenius法比Bishop法的安全系数略大的结论。结合工程实际中可能出现的渗流和超载等因素,计算得到边坡安全系数的变化规律和极限平衡状态时的临界负荷,从而提出了相应的预防渗流、控制超载等措施,可以为航道护岸建设提供参考。  相似文献   

18.
Vertical bending moment (VBM) is of crucial importance in ensuring the survival of vessels in rough seas. With regard to conventional vessels, wave-induced maximum VBM is normally considered to be experienced in head seas. It is conservative to determine the extreme VBM based on either numerical simulations or model tests in long-crested head seas. Extensive model tests have been conducted in head seas with focus on the nonlinear vertical responses in severe seas, and the measured results were compared with numerical calculations for validation. Unexpected phenomena, however, were observed during the model tests of an ultra-large containership. The maximum sagging and hogging VBMs were encountered in oblique seas. Furthermore, the significant wave height used in oblique seas was even smaller than that used in head seas. The nonlinear vertical load effects in oblique seas require further investigations for this particular vessel. Limited experimental results in oblique seas have been reported, in which the lateral responses were always more concerned than the vertical responses. Up to now, rare systematic comparisons of the nonlinear vertical responses between head and oblique seas have been published, especially when the hydroelastic effects are also accounted for. A 13000-TEU ultra-large containership model, which was designed by Hyundai Heavy Industries (HHI), has been tested in the towing tank and the ocean basin at the Marintek center in Trondheim. The experimental results in regular waves are first compared between head and oblique seas. The statistical characteristics of the VBM amidships under nineteen irregular wave conditions are then investigated. Next, the extreme hogging and sagging VBMs are compared under different wave conditions with focus on the extreme hogging VBMs. At the end of the paper, the uncertainties in the experiments are discussed.  相似文献   

19.
This paper explores the relationships between the spatial patterns of the distribution of the young hakes of the year (YOY) and the oceanographical features in two areas of the Central Mediterranean (the Ligurian Sea and the Strait of Sicily), characterised by the occurrence of straits and channels. Comparative and correlative approaches were used to investigate coupling between biological and physical patterns. Density indices of the YOY were derived from annual trawl surveys from 1994 to 2004 in spring and autumn. Mean patterns of the YOY distributions were compared with the mesoscale oceanographical features reported in literature. No evident trends in recruitment strength were found in either areas. Inter-annual variability in YOY abundance in the Ligurian Sea was higher than in the Strait of Sicily. The location of nursery grounds in the study areas coincides with zones of relatively higher production, where upwelling and other enrichment processes regularly occur. The presence of predictable eddies and the frontal systems play a major role in the localization of nursery areas in the Strait of Sicily, maintaining their stable position throughout the years. The strongest transport of southern waters from the Tyrrhenian to the Ligurian Sea, due to the East Corsica Current, which is negatively correlated to winter North Atlantic Oscillation, is associated with the highest abundance of hake recruits in the nurseries of the Northern Ligurian Sea.  相似文献   

20.
位于长江口北支的崇启大桥处于盐淡水交替区,其混凝土桥墩易受海水腐蚀。为给桥墩抗腐试验提供必要的潮位变动区范围和盐度试验参数,建立了基于无结构网格的长江口盐水数值模型,计算分析了在不同径流量和外海潮汐边界条件下,崇启大桥断面潮位变幅及盐度变动过程。研究表明崇启大桥处潮位变幅大,潮汐是控制崇启大桥处水位变动范围的关键因素;桥墩处盐度整体取决于入海径流量,流量增加促使盐度降低,反之亦然;潮汐作用促使桥墩处呈现短周期性振荡盐度,盐度范围为10‰~26‰,其中枯季盐度平稳,洪季变幅大。  相似文献   

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