共查询到20条相似文献,搜索用时 78 毫秒
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结合枢纽整体水工物理模型试验、船模试验结果,针对"曲进直出"和"直进曲出"两种方案,从口门区通航条件、船舶过闸效率、枢纽湘江大桥的跨径布置、预留二线船闸的施工影响和对枢纽泄流能力的影响等方面对土谷塘航电枢纽工程船舶进出闸方式进行了对比分析,为最终确定船舶进出闸方式提供了依据。 相似文献
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目前对现有水利工程进行维护与加固改造逐渐成为水利建设管理中的一项重要任务,张公龙水电站原溢流坝泄流能力不足,运行中曾出现水流漫坝下泄的险情,需在原溢流坝左侧增设溢流闸孔,而原有的三孔闸进行加固处理,此为广东省内首次将粘钢植筋法用于弧门支座的加固,该工程于2012年11月加固后下闸蓄水,至今运行良好。 相似文献
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白杨河水库溢洪道模型试验,结果表明原设计方案溢流堰泄流能力不满足设计要求,在急流收缩段形成了严重的冲击波,水流折冲形成水翅超出边墙,收缩段边墙高度不满足安全泄流要求。通过系列试验对设计方案进行修改优化,提出了增加WES堰泄流净宽度和收缩段长度,同时在收缩段设置一小于溢洪道底板坡度的正坡对称多边形孔板消除急流收缩段冲击波的优化方案。优化方案的试验结果表明,溢洪道泄流能力满足泄流要求,急流收缩段内泄洪流态明显改善,折冲水流产生的水翅消除,收缩段水深低于各段泄槽边墙高度,满足安全泄流要求。 相似文献
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内河航运枢纽厂坝间上游导墙布置参数与电站运行及枢纽泄洪密切相关。针对汉江雅口航运枢纽,采用物理模型试验研究了厂坝间导墙长度以及墙身开孔对电站进流和枢纽泄流能力的影响。结果表明,在设计拟定的三种导墙布置长度下,导墙长度越短对枢纽泄流能力及电站进流条件影响越小,同时导墙开孔可进一步提高泄流能力和改善电站引流条件。 相似文献
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The key features of the western Galician shelf hydrography and dynamics are analyzed on a solid statistical and experimental basis. The results allowed us to gather together information dispersed in previous oceanographic works of the region. Empirical orthogonal functions analysis and a canonical correlation analysis were applied to a high-resolution dataset collected from 47 surveys done on a weekly frequency from May 2001 to May 2002. The main results of these analyses are summarized bellow. Salinity, temperature and the meridional component of the residual current are correlated with the relevant local forcings (the meridional coastal wind component and the continental run-off) and with a remote forcing (the meridional temperature gradient at latitude 37°N). About 80% of the salinity and temperature total variability over the shelf, and 37% of the residual meridional current total variability are explained by two EOFs for each variable. Up to 22% of the temperature total variability and 14% of the residual meridional current total variability is devoted to the set up of cross-shore gradients of the thermohaline properties caused by the wind-induced Ekman transport. Up to 11% and 10%, respectively, is related to the variability of the meridional temperature gradient at the Western Iberian Winter Front. About 30% of the temperature total variability can be explained by the development and erosion of the seasonal thermocline and by the seasonal variability of the thermohaline properties of the central waters. This thermocline presented unexpected low salinity values due to the trapping during spring and summer of the high continental inputs from the River Miño recorded in 2001. The low salinity plumes can be traced on the Galician shelf during almost all the annual cycle; they tend to be extended throughout the entire water column under downwelling conditions and concentrate in the surface layer when upwelling favourable winds blow. Our evidences point to the meridional temperature gradient acting as an important controlling factor of the central waters thermohaline properties and in the development and decay of the Iberian Poleward Current. 相似文献
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介绍了网络基础建设和应用VPN技术实现企业网络互联的方案,重点介绍了系统的核心技术Microsoft SharePointTMTeamServices(STS)的特点和应用,随后介绍了本企业开发和引进的软件系统的应用和企业综合信息系统的集成。通过STS的成功应用可以看出,应用STS软件系统,即可轻松快速地架构起一个高效、强大的企业内部沟通协同的信息平台。 相似文献
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伶仃洋滩槽演变及其发展趋势 总被引:2,自引:0,他引:2
伶汀洋水面开阔 ,岛屿众多 ;径流来水来沙量大 ,入汇口门多而分布不均匀 ;潮汐弱 ,潮流强弱平面分布不均匀 ,因而造就了当今的三滩两槽的淤积形态。两槽的形成与中滩的发育演变相辅相成 ,随着东、西滩淤积抬高和中滩淤积南移 ,必将导致东槽南段的西南汊进、排水能力不断减小 ;与此同时西槽北端因西滩的挤逼和推移质淤积也将日益萎缩 ,中滩北段漫流日益增强 ,必将导致切滩夺主 ,在伶仃浅滩与拦江沙之间将重新冲开通道。顺应滩槽演变趋势 ,因势利导 ,挖通拦江沙与伶仃浅滩间的沙梗 ,不仅可使伶仃洋航道收“一劳永逸”和事半功倍之效 ,而且还可提高排沙能力 ,使伶仃洋延年益寿 相似文献
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This paper presents a simplified method for the reliability- and the integrity-based optimal design of engineering systems and its application to offshore mooring systems. The design of structural systems is transitioning from the conventional methods, which are based on factors of safety, to more advanced methods, which require calculation of the failure probability of the designed system for each project. Using factors of safety to account for the uncertainties in the capacity (strength) or demands can lead to systems with different reliabilities. This is because the number and arrangement of components in each system and the correlation of their responses could be different, which could affect the system reliability. The generic factors of safety that are specified at the component level do not account for such differences. Still, using factors of safety, as a measure of system safety, is preferred by many engineers because of the simplicity in their application. The aim of this paper is to provide a simplified method for design of engineering systems that directly involves the system annual failure probability as a measure of system safety, concerning system strength limit state. In this method, using results of conventional deterministic analysis, the optimality factors for an integrity-based optimal design are used instead of generic safety factors to assure the system safety. The optimality factors, which estimate the necessary change in average component capacities, are computed especially for each component and a target system annual probability of system failure using regression models that estimate the effect of short and long term extreme events on structural response. Because in practice, it is convenient to use the return period as a measure to quantify the likelihood of extreme events, the regression model in this paper is a relationship between the component demands and the annual probability density function corresponding to every return period. This method accounts for the uncertainties in the environmental loads and structural capacities, and identifies the target mean capacity of each component for maximizing its integrity and meeting the reliability requirement. In addition, because various failure modes in a structural system can lead to different consequences (including damage costs), a method is introduced to compute optimality factors for designated failure modes. By calculating the probability of system failure, this method can be used for risk-based decision-making that considers the failure costs and consequences. The proposed method can also be used on existing structures to identify the riskiest components as part of inspection and improvement planning. The proposed method is discussed and illustrated considering offshore mooring systems. However, the method is general and applicable also to other engineering systems. In the case study of this paper, the method is first used to quantify the reliability of a mooring system, then this design is revised to meet the DNV recommended annual probability of failure and for maximizing system integrity as well as for a designated failure mode in which the anchor chains are the first components to fail in the system. 相似文献
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Nonlinear behavior of jacket platforms is important in both design and rehabilitation issues that depends on the bracing arrangement. Both ductility and strength of the structures derived from pushover analysis are highly related to configuration of the braces. Considering a suitable criterion such as constant weight or constant stiffness and period of the structure in all arrangement cases, one can compare the capacity curves and find the best configuration. In this paper a simple logical method for investigating the strength and ductility of the jacket structure is presented, it is shown that global geometry and configuration of the braces are very important and effective in both strength and ductility parameters. Three parameters, normalized strength, normalized ductility and a combination of these two parameters are defined in order to have an engineering and practical index for comparing the results. At the end of the numerical discussion, the optimum configuration can be found. Such an investigation is very important in the initial design stage. Also, in assessment of existing platforms, it is very important to find the reliable strength and ductility of the structure. Such a study gives a deep view of this issue as well. 相似文献
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The evolution of maritime logistics as an emerging discipline has resulted, to a large extent, from the increasing and varied demands of shippers and customers and the rapidly changing role of ports in the context of supply and logistics chains. Scholars are becoming increasingly aware of the need to integrate logistics and supply chain management concepts in the maritime transportation chain and operations. This article aims to provide a review and foundation for understanding the domain of maritime logistics and to assess its potential as an emerging discipline. To do so, a framework for understanding the various aspects of maritime logistics strategy and implementation is developed. A synthesis of the existing knowledge on maritime logistics is done by integrating diverse explorations forming the basis of this framework. We draw upon the literature on maritime transport and ports and primarily theliterature that analyses concepts by adopting an economic or management perspective. 相似文献
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从回顾民船和军船的发展简史开始,介绍民船入级的意义,传统的军船设计内部标准,现今国际社会军船入级的现状;通过分析军船入级的意义,军船入级过程中须要解决的几个关键问题,提出了我国军船入级的展望及建议。 相似文献