Dynamic analysis of three-dimensional marine cables

Marine cables are widely used in a variety of offshore activities. In this paper, a numerical approach is presented which is capable of predicting the dynamic behaviour of three-dimensional marine cables. The solution of this problem is of practical importance in the estimation of dybamic loading and motion, and thus has direct application to the enhancement of safety and the effectiveness of the offshore activities. The approach is based upon the lump-mass-and-spring model and the finite difference method. Mathematical analysis is provided on the basic characteristics of the model and the numerical stability. A numerical example is given to demonstrate the validity of the approach.     

发展地理信息系统产业

“全国地理信息系统技术与应用工作会议”今天召开了。我代表国家科委向参加会议的同志们表示热烈的欢迎,预祝会议取得圆满的成功。并向为地理信息系统技术和应用的发展做出贡献的科技、经营管理及市场营销人员致以诚挚的问候和崇高的敬意! 这次会议将对发展我国地理信息系统产业的战略、政策等问题进行研讨,同时交流产品开发和推广应用等方面的经验。希望通过这次会议,达到统一认识、推动全社会各个方面为地理信息系统产业发展多做实事的目的,加速我国地理信息系统产业的发展。     

EFFECT OF NITRATE AND PHOSPHATE ON ACCUMULATION OF β-CAROTENE ISOMERS IN DUNALIELLA SALINA

DunaIiella salina, a halotolerent unicellular green alga, can accurmulate a Iarge amount of β-caroteneunder environmental conditions. The isorners of β-carotene extIacted from D. salina culturedin medium with different nitrate and phosphate concentrations were analysed by HPLC with Alox-Talumins column. At least six isomers were found in different proportions depending on the culture me-dia's nitrate and/or phosphate concentrations. Nitrate and/or phosphae defidency was conducive tothe accumulation of totaI cis isomers but not of al1 trans isomer. lt is sUggeSted that 1 mmol/L KNO_3and 0.1 mmol/L KH_2, PO_4 are favourable for accumulation of total cis β-carotene.     

STUDY ON BEIJING''''S EMERGING MOBILE COMMUNICATION INDUSTRIAL CLUSTER AND ITS POLICY IMPLICATIONS

1INTRODUCTIONClusters,definedasgeographicallyproximategroupsofinterconnectedcompaniesandassociatedinstitutionsinparticularfields,linkedbycommonalitiesandcomple-mentarities(PORTER,2000),havearousedanintenseinterestofurbanandregionalplanningresearchersandpolicymakersoverthepastdecades.Itiswidelyrecog-nizedthatclusterscanpromoteproductivityandinno-vation,developlocalcompetitiveadvantages.Popular-izedbyMichaelPORTERinhisbook“TheCompetitiveAdvantageofNationsin1990,theclusterisnotanewcon…     

欧盟RoHS指令与中国的对策

对欧盟RoHS指令的主要内容进行了简述,初步介绍了与RoHS指令相似或者相关的各国的环保指令,讨论了RoHS指令等对我国电子电气行业带来的巨大冲击。简要总结我国电子信息产业部、国家质量监督检验检疫总局、商务部等各管理及技术部门为了应对RoHS指令和提高我国电子电气行业竞争力而作出的相应对策。     

南海波高熵和风速熵

根据风速的统计分布，给出了有因次风速熵和无因次风速熵的定义及其计算方法，使用ＧＥＯＳＡＴ高度计１９８６年１１月－１９８９年２月的有效波高和风速的资料，计算，分析了南海海域上的波高熵，风速熵，给出它们的时间变化特征和空间变化特征，并对不同随机量的无因次熵，即随机度进行了比较。     

ELASTIC CLASSIFICATION OF MODIFIED WATER MASS IN SHALLOW SEA

In this paper, the principle and steps for differentiating water masses by fuzzy cluster method are introduced, and a scalar formula based on Euclidean distance and a method for determining objectively the number of water masses by F-test are proposed. Consequently, a method and specific steps for differentiating modified water masses in shallow sea according to fuzzy elastic classification are given. Computation of the membership degree in which each sample belongs to every water mass determines conveniently and quantitatively the cores, boundaries of water masses and mixed zones. An example for the Huanghai Sea and East China Sea is shown and compared with previous results.