EFFECTS OF PHOTOPERIOD AND SALINITY ON GROWTH AND UPTAKE OF 60Co AND 137Cs FOR CHLORELLA SP.

The effects of three photoperiods (24 hr illumination, 12 hr illumination + 12 hr darkness and 24 hr darkness) and three salinities (20‰, 30‰ and 35‰) on the uptake of 60Co and 137Cs for Chlorella sp. and on the growth of its algae are studied. The uptake of 60Co for the algae is two orders of magnitude higher than that of 137Cs. Of factorial effects, the effect of photoperiod is most significant either on the uptake of the radionuclides or on the growth of the algae; the effect of salinity comes next in order and that of their interaction remains with the last. The uptake of the two radionuclides increases with extended photoperiod while the uptake of 137Cs declines with increasing of salinity. The growth of the algae appears to be the best under the conditions of 24 hr illumination and 30‰ salinity.     

Experimental and Theoretical Investigation of Wave Forces on A Partially-Perforated Caisson Breakwater with A Rock-Filled Core

1.IntroductionVertical breakwaters are widely used for harbor and coastline protection in coastal engineering.Recently,perforated breakwaters have been often used in practice as they can effectively reduce thewaveforces actingon,the wave reflectionfromand…     

A Finite Element Solution of Wave Forces on Submerged Horizontal Circular Cylinders

In this paper, a numerical model is established for estimating the wave forces on a submerged horizontal circular cylinder. For predicting the wave motion, a set of two-dimensional Navier-Stokes equations is solved numerically with a finite element method. In order to track the moving non-linear wave surface boundary, the Navier-Stokes equations are discretized in a moving mesh system. After each computational time step, the mesh is modified according to the changed wave surface boundary. In order to stabilize the numerical procedure, a three-step finite element method is applied in the time integration. The water sloshing in a tank and wave propagation over a submerged bar are simulated for the first time to validate the present model. The computational results agree well with the analytical solution and the experimental data.Finally, the model is applied to the simulation of interaction between waves and a submerged horizontal circular cylinder.The effects of the KC number and the cylinder depth on the wave forces are studied.     

Wave Action on Structures of Combined Cylinders

1.Introduction Owingtoitssignificanteffectofreductionofwaveloadsandwaverun up,theperforatedwallon anarrayofcylindricalstructureshasreceivedconsiderableattentioninrecentyears.Manyresearches havebeencarriedoutinthisfield.Anexactsolutionforthediffractionoflinearwaterwaveswithan arrayofimpermeablecylinderswasfirstgivenbySpringandMonkmeyer(1974)usinganeigenfunction expansionapproach.Subsequently,LintonandEvans(1990)madeamajorsimplificationtothetheo ry,whichallowedthenear fieldquantitiessuchasload…     

A Model of Wave Spectrum in Shallow Water

By using the shallow water wave data continuously recorded in the Bohai Sea, Huanghai Sea, East China sea and South China Sea. a model of wave spectrum in shallow water is developed with three parameters—average wave height, average period and relative depth—on the basis of the principle of the spectrum pattern simularity and the method of parameterization. The magnitude of frequency index in the high frequency     

菲律宾海的气候特征

本文根据1950～1995年共46年西北太平洋船舶资料,以5°×5°网格为统计单元,绘制的累年各月风、温度、气旋、降水、能见度、雷暴、雾等气象要素图,并结合国内外其它资料对菲律宾海进行了较为详细的分析研究,阐明了该海区的气候特点及其变化规律.     

方解石和钾长石在模拟蚯蚓肠液中的初始溶解动力学机理及意义

蚯蚓肠道内小分子有机酸与摄入的土壤矿物相互作用,加速矿物溶解。摄入的土壤在蚯蚓肠道内平均停留时间约为12 h,不足以使土壤矿物产生显著的溶解特征,因此这一过程难以在蚯蚓体内进行评估。本研究通过体外实验控制pH值和有机酸浓度,模拟蚯蚓肠道中有机酸对土壤中常见矿物的溶解反应,探讨了方解石和钾长石在蚯蚓肠道环境中的初始溶解动力学。研究发现,矿物在混合有机酸中的溶解速率比在纯水中高一个数量级,说明有机配体和质子促进了矿物溶解。溶解速率及粒度分析表明,方解石(CaCO₃)溶解速率不受溶解过程中粒度变化的影响,而钾长石(KAlSi₃O₈)粒度在溶解期间未出现显著变化。在此基础上,采用初始速率法模拟了钾长石的初始溶解动力学,计算得出的溶解速率表明钾长石在溶解初期主要为表面K~+的释放。使用缩核模型(shrink core model)和Hixson-Crowell模型对方解石溶解过程进行动力学解析,发现方解石的溶解主要受溶液中反应物内扩散的速率影响。这定量描述了两种矿物在有机酸溶液和纯水中的溶解差异。现有研究表明,有机配体和质子协同促...     

基于单片机的智能轮椅控制系统设计

为提高轮椅使用者的生活自理能力,本文提出一种智能轮椅控制系统.该系统由STM32单片机进行控制,采用模块化、系统化设计,电源模块、摇杆模块、避障模块、驱动模块构成有机整体,各个模块共同作用、相互协调,共同构成了一个安全可靠的轮椅控制系统.通过通信设计可实现模块间数据的发送与接收.该轮椅设置手动控制和自动控制两种方式,可实现轮椅使用者独立生活和近距离出行,运行安全可靠.     

江陵凹陷古新世地下卤水型硼矿成因研究

中国探明硼资源主要分布于东北和青藏等地区,矿床品位低,共伴生矿物多,开发成本高,开发利用程度低,难以满足产业发展需求。目前,在江汉盆地江陵凹陷勘探中发现卤水中B2O3浓度达3 g/L,Li、K、Br、I、Rb、Cs含量超过工业品位,综合利用价值高。本文在前人研究的基础上,对江陵凹陷新生代卤水型硼矿开展水化学、同位素地球化学及实验地球化学分析,重点研究了古气候、构造和玄武岩等对卤水成矿的影响,探究其成因机制。研究初步认为,不同的储卤层岩性具有不同的地球化学和同位素特征,玄武岩有强烈的蚀变,说明地下流体对火成岩发生了交代作用,玄武岩的水-岩反应是富硼卤水矿的重要物质来源;一定盐度的流体有利于硼离子的活化,高盐度流体是硼成矿元素主要的迁移载体,表生环境下干热的古气候使含矿水体蒸发浓缩是富硼卤水富集成矿的重要形成机制。     

适用于曲边界的浅水非线性波浪数值模型

实际工程中存在大量的曲边界,因此在曲边界上的计算准确性可以考察出一个数值模型的实用价值。利用Beji的改进型Boussinesq方程建立了一个有限元方法的数值波浪模型。造波方面采用Fenton提出的非线性规则波浪解;在墙边界处,以求解法线方向和切线方向的速度和导数代替求解x、y方向的速度和导数,从而使边界条件直接适用、严格满足,保证了对曲边界计算的准确性。"重开始广义极小残量法"的使用保证了求解方程组的效率和精度,使造波和边界处理方法的有效性和准确性得到了合理地诠释。通过与试验数据、他人数值结果、解析解的比对,显示出该模型计算稳定、结果准确,真正体现出了有限元方法对曲边界适用的优势。