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401.
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Sea ice data has significant scientific value for climate, environmental impact and engineering studies leading to the construction of facilities in Arctic waters, as well as to support tourism and fishing planning. Large collections of such data are acquired, compiled, produced and maintained by national and international agencies such as the Canadian Ice Service (CIS). Some of these data collections have been made available online. However, current Internet‐based sea ice data dissemination practices do not foster easy access to and use of the data, especially given the amount of the archived sea ice data and the nature of their spatial changes and high temporal variations. This article reports a research effort in developing a web‐based geographical information system (GIS) that facilitates the access and use of the historical sea ice data. The system provides online access, exploration, visualization, and analysis of the archived data, mostly in the form of ice charts, within a web‐based GIS. The results from a prototype development indicate that web GIS, developed using Rich Internet Application (RIA) technologies, provides added values in serving sea ice data and suggests that such a system can better accommodate more advanced sea ice data access and analysis tools. 相似文献
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A novel type of angle steel buckling‐restrained brace (ABRB) has been developed for easier control on initial geometric imperfection in the core, more design flexibility in the buckling restraining mechanism and easier assembly work. The steel core is composed of four angle steels to form a non‐welded cruciform shape restrained by two external angle steels, which are welded longitudinally to form an external tube. Component test was conducted on seven ABRB specimens under uniaxial quasi‐static cyclic loading. The test results reveal that the consistency between the actual and design behavior of ABRB can be well achieved without the effect of weld in the core. The ABRBs with proper details exhibited stable cyclic behavior and satisfactory cumulative plastic ductility capacity, so that they can serve as effective hysteretic dampers. However, compression–flexure failure at the steel core projection was found to be the primary failure mode for the ABRBs with hinge connections even though the cross‐section of the core projection was reinforced two times that of the yielding segment. The failure mechanism is further discussed by investigating the Nu– Mu correlation curve. It is found that the bending moment response developed in the core projection induced by end rotation was the main cause for such a failure mode, and it is suggested that core projection should be kept within elastic stage under the possible maximum axial load and bending moment response. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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采用SPOT5和Quickbird遥感影像,结合地面调查,分析石棉县地质灾害类型、规模和分布.结果表明,石棉县地质灾害以中小型滑坡、崩塌和泥石流为主,其分布与降雨、海拔,岩性、断裂构造和地形密切相关. 相似文献
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In this paper the wave action balance equation in terms of frequency-direction spectrum is derived.A theoretical formulation is presented to generate an invariant frequency space to replace the varying wavenumber space through a Jacobian transformation in the wave action balance equation.The physical properties of the Jacobian incorporating the effects of water depths are discussed.The results provide a theoretical basis of wave action balance equations and ensure that the wave balance equations used in the SWAN or other numerical models are correct.It should be noted that the Jacobian is omitted in the wave action balance equations which are identical to a conventional action balance equation. 相似文献
408.
高层建筑结构的抗震可靠度分析与优化设计 总被引：12，自引：4，他引：12
本文根据我们在文献２中给出的等效随机地震静力作用模型，紧密结合规范和利用我们在文献６中提出的结构体系可靠度分析的最弱失效模式法，提出了结构构件和体系“小震不坏”和“大震不倒”及结构体系在设计基准期内的抗震可靠度分析方法；重新校准了结构构件的目标可靠度指标；综合考虑结构造价和损失期望，提出了结构体系抗震目标可靠度的优化决策方法；分别给出了满足构件抗震目标可靠指标与同时满足构件和体系抗震目标可靠指标的 相似文献
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根据天水农试站１９８３—１９９２年地下水位观测资料，分析得出了当地地下水位的变化规律和地下水对土壤水分变化的影响，并根据当地主要粮食作物的生长特点，对其需水与地下水位变化的关系进行了探讨。 相似文献