Wave energy and clast transport in eastern Tasman Bay,New Zealand

Coarse‐gravel beaches are common features along the eastern margin of Tasman Bay, at the north end of South Island, New Zealand. Although these features have traditionally been interpreted as spits, contemporary incident wave energy appears too small to transport boulders and cobbles persistently along the beaches and platforms by longshore drift. An alternative explanation suggests that boulder beaches are essentially derived in situ from resistant bedrock, which lies seaward and was buried by gravel during the Holocene sea level rise. Wind, wave and clast size data from Cable Bay and the Nelson Boulder Bank were used to resolve this problem. Wave and wind data indicate that waves reaching these areas are derived locally in Tasman Bay, and are limited in size and energy. Hindcasting predicts a 4·7 m wave could propagate from Tasman Bay. However, during Cyclone Yalli, the most intense storm in nearly 40 years of wind records, the largest wave measured in the nearby area of Cable Bay was only 2·7 m high. Maximum orbital velocity on the seabed beneath a 4·7 m is calculated to be 2·9 m s^?1, which cannot initiate transport of clasts greater than 0·15 m in diameter. Clasts on the gravel platforms have average diameters greater than this, but some clasts may be as large as 1·0 m in diameter. By comparison, a swash run‐up method predicts that a wave 4·7 m high can transport clasts no larger than 0·3 m in diameter. These data and approximate calculations strongly suggest that the present wave environment in eastern Tasman Bay is not capable of consistently transporting clasts on the boulder platforms by longshore drift. Reduced sea levels in the pre‐Holocene period would further reduce wave energies available in Tasman Bay. Copyright © 2006 John Wiley & Sons, Ltd.     

超氯盐渍土的工程特性指标研究

以探讨超氯盐渍土的含盐量与工程特性指标间关系为目的 ,采用室内土工试验与数学分析相结合的方法 ,深入研究了含盐量对塑性指标、抗剪强度的影响以及盐渍土渗透系数与干重度、含水量之间的关系。研究发现 :超氯盐渍土洗盐前后可塑性变化幅度较大 ;抗剪强度随含盐量增加而增大 ;在干重度、含水量与渗透系数三者相互关系中存在界限含水量和界限干重度。所得结论对深入研究盐渍土的工程特性、指导盐田建设将有所裨益     

有限范围的重力层间改正算法

层间改正是重力归算的一项重要内容,传统的平面层层间改正、球面层层间改正与地形改正的范围不一致,因此均存在远区虚拟地形引入的近似误差,且计算点高度越高,此误差越大。本文提出使用有限范围的层间改正进行重力归算的方法,使其区域范围与地形改正的范围一致。然后给出了有限范围层间改正的简便计算方法,该算法与通过地形改正严密积分法演化来的算法具有较好的一致性。内插试验说明当计算点地形高于1000m时,内插应使用基于有限范围层间改正的重力归算方法。     

陕西中部地区粮食增产潜力及措施

农业是国民经济的基础,粮食是基础的基础。陕西中部地区素有“陕西粮仓”之称,探索其发展规律,分析其障碍因素,寻求其发展潜力,采取“一靠政策,二靠科技,三靠投入”的战略措施,对同类地区的粮食发展具有重要意义。     

利用有限区域模式对1979年1月东亚平均环流和寒潮过程的初步模拟试验

利用不同分辨率的有限区域数值模式, 由FGGE III b分析场提供模式的初始条件和随时间变化的侧边界条件,通过长时间连续积分对东亚地区5.625～63.75oN、61.375～138.75oE范围内,1979年1月的平均环流和寒潮过程进行了模拟和试验研究。文中首先考察了在研究时段内长时间积分后,模式的计算性能及其稳定性。结果表明,由于强加于模式的侧边界条件的作用,可以使得误差增长控制在一定范围之内。在此基础上进一步分析了误差的时空分布特征及其成因。通过对24小时变高、24小时变温负中心值和逐日温压场的分     

异养细菌在海洋生态系统中的作用

概述异养细菌的分布、生物学特点、对物质矿化分解的作用以及在海洋生态系统物质循环和能量流动中的作用 ;海洋细菌生物量和生产力的研究方法 ;异养细菌在铁限制大洋生态系中的作用 ;国内外对底栖异养细菌生态功能研究的现状 ;最后提出该领域今后应加强研究的内容     

A Discusion on Limited Load-Carrying Capacity of Rectangular Plates

The elastic-plastic method is often used in designing the inner flat bulkhead plates of submarines, and the upper structure of ships and drilling platforms. Such bulkhead plates can bear the load only once. For the improvement of the load-carrying capacity or the reduction of the weight of plates, the yield line analytical method is employed in this paper to design the bulkhead plate to improve economy and increase the effiective load. Besides, a further sutdy of this method has been made theoretically and experimentally, and the data of the limited load-carrying capacity of the plate have been obtained. Furthermore, the safety coefficients for such a method are presented, which can be used as reference for related departments and staffs.     

Similarities of Some Wind Input and Dissipation Source Terms

Wind input parameterizations proposed by Jeffreys, Sverdrup and Munk, and Plant are analyzed. It is round by analogy that the similarity of integrals of the three wind input parameterizations exists. Wave breaking dissipation parmneterizations proposed by Tsikunov, Hasselmann, and Phillips are also analyzed. Likewise it is found by analogy that the similarity of integrals of the three dissipation parameterizations exists. The similarities of wind input and dissipation are applied to the investigation of the fetch-limited growth of wind waves, together with the 3/2 power law presented by Toba. Some semi-empirical formulas concerning the growth of wave height and period with fetch are presented. The results from the formulas are in good agreement with previous field observations.     

Stage Predictions of Landslide and Subsidence from an Once-Through Cycle

In this paper both processes of landslide and subsidence are consid-ered to be limited systems.Each of these systems in nature might be re-garded as an organism.Generally their lifespan must develop with com-mon ecological characteristics,including several evolutional stages,such asinitiation,growth,maturation,decline and death.Among these stages,maturation is emphasized so as to find the occurring or thriving date ofboth systems.An once-through cycle of both landslide and subsidence isestablished and is accurately predicted by a developed,mathematic model of thePoisson cycle.The Weibull distribution is cited for a landslide example.Both fundamentals are discussed.Stage predictions of landslide and subsid-ence are performed for several examples.Back analysis of landslides thathave already happened are studied with the same model.And when com-pared with results from the biological mathematic model and with practicalresults,it is found that they correspond.Stage prediction of subsidences isalso researched     

辽宁省及邻近地区较大地震震级的测定方法

本文使用１９８６年至１９９１年期间沈阳遥测地震台网记录到的１４５３次地震的持续时间资料（２．０≤Ｍ＿Ｌ≤６．１级、５ｋｍ＜△＜１０００ｋｍ），求得了辽宁省及其邻近地区多台多幅度持时震级的经验公式，结果表明，这种震级误差小，应用范围为Ｍ＿Ｌ≤６．０级，解决了限幅地震无法计算震级的难题．