三维三分量CSAMT法有限元正演模拟研究初探

首先从麦克斯韦方程出发,用伽里金方法推导了三维三分量CSAMT法的有限元方程.在研究过程中,认识到加入散度条件的必要性,在公式中强加了散度条件,提高了解的完备性.其次将成功应用于二维线源频率域电磁法有限元模拟中的两种技术推广到三维中,一是边界条件统一采用一阶吸收边界,使线源产生的电磁波在边界上按波的传播规律被吸收,以降低平面波假设造成的影响;二是总体系数矩阵的存储,用两个二维数组分别记录总体系数矩阵的非零元素及其在总体结点编号中所处的位置,使总体系数矩阵的存储量达到最小的同时,物理意义明确,迭代求解时迅速简便.最后用均匀半空间模型进行了验证.     

伪谱法弹性波场数值模拟中的边界条件

边界条件问题长期以来一直是困扰地震波数值模拟研究者的一个难题,许多人都提出了有效的方法,但是该问题仍然需要研究.本文针对伪谱法地震波场数值模拟的特殊要求,即所有网格点相互耦合,且傅立叶变换的周期性使得方程在网格边界上很难得到一个吸收的替代方程,研究衰减边界条件中衰减系数的变化对边界反射波衰减效果的影响.数值实验结果说明,随着衰减系数的增大,振幅衰减加快,用很少的过渡带网格就可以使边界上的反射波能量很小.但是如果衰减率过大,就会在传播区和过渡带产生干扰波场.因此,在衰减系数的选择上应采取折中办法,即在取某一较小的衰减系数的前提下,设置较少的过渡带网格数使边界的能量反射最少.     

A Sensitivity Study of Arctic Ice-Ocean Heat Exchange to the Three-Equation Boundary Condition Parametrization in CICE6

In this study, we perform a stand-alone sensitivity study using the Los Alamos Sea ice model version 6(CICE6) to investigate the model sensitivity to two Ice-Ocean(IO) boundary condition approaches. One is the two-equation approach that treats the freezing temperature as a function of the ocean mixed layer(ML) salinity, using two equations to parametrize the IO heat exchanges. Another approach uses the salinity of the IO interface to define the actual freezing temperature, so an equation describ...     

Latitudinal and local variations of the life history characteristics of the thalassinidean decapod, Upogebia yokoyai: A hypothesis based on trophic conditions

Mean total length of the eldest cohort (MTLe) of the thalassinidean decapod, Upogebia yokoyai sampled at 16 sites showed a latitudinal variation from south-west islands of the Ryukyu Archipelago (24° N) to the Seto-Inland Sea of Japan (34° N). Local variations were however also found from sites in the same latitudes. The level of the organic content in each habitat showed a positive correlation with MTLe. We hypothesized that MTLe is strongly affected by the trophic condition, resulting in the local variations. To test this hypothesis, two estuaries with different organic content were compared; Kodono River (Kochi Prefecture, 33° N) which was relatively oligotrophic and Sakata River (Hiroshima Prefecture, 34° N) which was highly eutrophicated. The Kodono River population showed slow growth after settlement, and growth stopped in May to June. This population survived for only one or two years, resulting in small MTLe. On the other hand, the Sakata River population showed fast growth from August to December. This population survived for three years, resulting in large MTLe. Maturation was estimated to occur two years after settlement in both populations. Low salinities may partially affect MTLe. Habitats in the Seto-Inland Sea (33.5–34.8° N) were eutrophicated, but many habitats in the subtropical islands (24–31° N) were relatively oligotrophic. Latitudinal variation of MTLe was reflected by the geographical difference in trophic condition. A negative relationship between population density and growth was found, which was explained in terms of reduced survival of recruits in the eutrophicated habitats.     

Scaling wave impact pressures on vertical walls

It is widely recognized that the use of Froude similarity for scaling up wave impact pressures recorded during physical model tests may lead to over-estimation of impact maxima. Based on reviewing historical work dating back to the 30s and further developments in the 60s and 80s, a general method is presented that is suitable for scaling up impact pressures and rise times measured during small scale physical model tests. The method accounts for the effect of air leakage and is applicable to most wave impact loads. The model is applied to scale wave impact pressures on vertical walls and similar structures, and consistent correction factors for the Froude scaling law are derived.     

钦州湾潮流深槽的成因与稳定性探讨

据钦州湾2007年1—2月的实测潮流,结合径流、潮汐等资料,经水动力和港湾地形综合分析揭示:钦州湾的潮流深槽是潮流作用于葫芦形复式港湾的必然产物,是在内湾纳潮蓄能、湾颈狭道强流、颈口岛礁分流喷射冲刷而成的。通过对潮流流路和强度的分析,对潮流深槽的稳定性进行了探讨;进而通过湾颈流速-内湾纳潮关系计算,给出了潮流深槽稳定的临界条件。     

桂林柑桔主要病虫害发生的气象条件分析

通过桂林地区柑桔主要病虫害发生发展的气象条件分析,找出了病虫害的发生发展与气象条件的关系很密切。     

使用MODIS陆地产品LST和NDVI监测中国中、西部干旱

利用中分辨率成像光谱仪AQUA-MODIS卫星资料反演的地表温度LST和归一化差值植被指数NDVI,在中国中、西部地区应用植被温度混合状态指数VTCI方法,遥感监测干旱的空间分布状况。同时结合该地区有代表性的气象站逐月降水资料与VTCI指数进行相关分析,来验证此方法的适用性。结果表明,VTCI指数不仅与当月的降水量,也与其前期2至6个月的累积降水量有较好的线性相关性,显示VTCI方法不仅是较为有效的近实时大范围干旱监测方法,对于干旱的缓慢发展过程也有一定指示作用。     

金银花尺蠖的发生与气象条件的关系

金银花尺蠖是近年发现的金银花产区的主要害虫,该虫在封丘县每年发生4代.通过对金银花尺蠖发生的气象因子分析,得出金银花尺蠖发生与气象条件的关系,并结合金银花尺蠖的生活特性提出了防治措施.     

新一轮基准地价更新应注意的几个问题

地价一直是土地市场上最活跃的因素,在土地储备和招标、拍卖、挂牌供地政策全面实施的情况下,如何运用价格机制调控土地市场,已成为新形势下的关键问题.城市社会经济的发展、基础设施建设的不断完善,城市地价的空间分布规律发生了变化,必须进行新一轮的基准地价更新.定期进行基准地价更新是城市社会经济发展的要求.运用数理分析和统计的方法,对新一轮基准地价更新应注意的几个问题进行了理论研究和实证研究.研究结论认为,基准地价内涵及基准条件的界定、样点地价数据的检验、基准地价结果分析是提高新一轮基准地价更新质量的重中之重.