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451.
452.
东方对虾的生产过程与气象关系及其应用 总被引:4,自引:0,他引:4
利用观测和调资料对东方对虾生产过程中的入室,越冬,育苗,放苗,养成,收获等主要生产环节与气象关系进行了计算分析,得出了各生育阶段适宜生长和生产的气象指标及其应用方法。 相似文献
453.
454.
The estimation of cyclic deformation demand resulting from earthquake loads is crucial to the core objective of performance‐based design if the damage and residual capacity of the system following a seismic event needs to be evaluated. A simplified procedure to develop the cyclic demand spectrum for use in preliminary seismic evaluation and design is proposed in this paper. The methodology is based on estimating the number of equivalent cycles at a specified ductility. The cyclic demand spectrum is then determined using well‐established relationships between seismic input energy and dissipated hysteretic energy. An interesting feature of the proposed procedure is the incorporation of a design spectrum into the proposed procedure. It is demonstrated that the force–deformation characteristics of the system, the ductility‐based force‐reduction factor Rμ, and the ground motion characteristics play a significant role in the cyclic demand imposed on a structure during severe earthquakes. Current design philosophy which is primarily based on peak response amplitude considers cyclic degradation only in an implicit manner through detailing requirements based on observed experimental testing. Findings from this study indicate that cumulative effects are important for certain structures, classified in this study by the initial fundamental period, and should be incorporated into the design process. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
455.
This paper attempts to assess the use of Global Navigation Satellite System (GNSS) as an accurate, reliable, and easy tool for sea level measurement. The GNSS technique was incorporated into a float based tide gauge system. A prototype of such an instrument was developed based on principles of conventional tide gauges, where high frequency noise is reduced mechanically. The ability of the GNSS based tide gauge (GTG) to monitor sea levels was tested in several experiments. The performance of the GTG was compared to that of a traditional tide gauge. The method of data analysis and data comparison between the GPS measurements and the tide gauge data is presented. The results show that the GTG is equal in performance to the traditional float operated tide gauge. It seems that the GTG is capable of delivering the same level of accuracy (1 cm), and its results are as reliable as its competitor, the traditional float tide gauge. The suggested instrument can be easily integrated into the array of permanent GNSS stations and assist in absolute measurements of sea level changes, caused by global warming and the greenhouse effect, for example. 相似文献
456.
Cu^2+,Zn^2+对罗非鱼鳃盖运动的影响 总被引:4,自引:1,他引:4
本文研究结果表明:(1)水体中含Cu2+和Zn2+的浓度越高,鱼中毒越深,鳃盖运动振幅的增大和频率的减小就越显著。(2)Cu2+/Zn2+混合液对鳃盖运动的影响具明显的协同作用,它的致毒效应分别为单一因子的3~5倍。(3)毒性次序:5×10-6Cu2+/50×10-6Zn2+>2.5×10-6Cu2+/25×10-6Zn2+>5×10-6Cu2+>50×10-6Zn2+(V/V)。(4)频繁的咳嗽反应是Zn2+中毒的主要症状,驱逐反射是Cu2+中毒的主要症状,两者均可作为单一和混合重金属离子污染的敏感生物学监测指标。 相似文献
457.
This paper presents the collecting methods of the deep-sea cosmic spherules and three major results analysed with various instruments, and especially indicates that iron spherule with golden Ni-Fe core and silicate spherule with golden Ni-Fe-S inclusion in deep-sea sediments are of significance for further understanding of the origin of the deep-sea spherules. 相似文献
458.
本文研究了1990年11月到199年8月间,该水域内叶绿素-a含量的时间空分布和初级生产力的分布与变化。叶绿素-a含量的分布同温和营养盐含量密切相关。 相似文献
459.
Mao Zhixiang Yan Peilan Huang Jianwei Dai Xiankai Han Naibing Chai Zhifang Qian Qinfang Ma Shulan Ma Jianguo Engineer Nanjing Hydraulic Research Institute Nanjing
Senior Engineer Nanjing Hydraulic Research Institute Nanjing
Associate Researcher 《中国海洋工程》1991,(3)
A new method of Neutron Activation Analysis (NAA) for sediment movement study is presented in this paper. Through analyzing the natural sediment, the information about natural tracing agents has been obtained, which can show the direction of sediment movement and relative discharge of sediment transportation. Test results in some areas, such as Shantou Harbour and Hangzhou Bay, are in good agreement with those from normal hydrologic measurements and some results are not obtainable with the latter. The NAA is economical, practical and reliable, and should be widely used in engineering practice. 相似文献
460.