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551.
552.
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
553.
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
554.
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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556.
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
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558.
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
559.
本文根据中国西南部四个强震带残余应力场水平和铅直分布的测量和实验研究结果,讨论了古构造残余应力场对震源的作用:降低震源岩体强度,增大震源岩体形变,与现今应力场迭加在一起促成地震,随岩体破裂释放残余弹性能加到震源释放的现今弹性能中去提高震级和地震活动水平。 相似文献
560.
1987年8月2日,江西省寻邬发生MS5.5地震。本文研究了这次地震和震前的各种异常现象,研究发现,震前该区地壳形变和震活动出现了中、长期同步变化,短临阶段,出现了异常地震活动和宏观现象。根据岩石破裂实验结果和地震前兆理论,对这次地震的孕育过程作了阶段性的划分。 相似文献