AN EVALUATION OF SAS/GRAPH SOFTWARE FOR COMPUTER CARTOGRAPHY1

The SAS® computer software system, widely used and respected for its capabilities in statistical analysis and data base management, now includes a new set of graphic and cartographic procedures called SAS GRAPH?. We have used these cartographic procedures in research on mapping ethno-cultural census data from metropolitan areas in Ontario and in undergraduate and graduate courses in computer cartography. On the basis of that experience, we describe and evaluate SAS/GRAPH'S cartographic capabilities and illustrate with maps drawn by various devices.     

台湾海峡西岸重力场变化梯度场图像分析

讨论了应用曲面拟合技术和利用离散的重力观测点的重力变化对特定研究区的重力场变化进行数值模拟以获取该区重力变化空间梯度场图像的具体方法;并应用该方法获得了2004年3月福建安溪3.6级地震前的重力变化空间梯度场图像,发现空间梯度场图像能清晰地反映出地震前重力场群体性变化的差异性;利用此方法对2005年6月~2006年3月间台湾海峡西岸重力场变化进行数值模拟,获得其空间梯度场图像。     

A qualitative and quantitative evaluation of experimental model catchment evolution

Due to the geological time scales required for observation of catchment evolution, surrogates or analogues of field data are necessary to understand long‐term processes. To investigate long‐term catchment behaviour, two experimental model catchments that developed without rigid boundaries under controlled conditions are examined and a qualitative and quantitative analysis of their evolution is presented. Qualitatively, the experimental catchments have the visual appearance of field scale data. Observation demonstrates that changes in catchment shape and network form are conservative. Quantitative analysis suggests that the catchments reach an equilibrium form while a reduction in the channel network occurs. While the catchments are laboratory scale models, the results provide insights into field scale behaviour. Copyright © 2003 John Wiley & Sons, Ltd.     

西洋东大港水道流速垂线分布研究

对辐射沙洲海域东大港4#站位连续2个潮周期的流速测量资料进行了分析、研究,拟合给出了流速垂线分布关系,并根据实际测量资料确定了该站位6个水层的浑水水流尾流函数项表达式。这些表达式表明浑水水流尾流函数是相对深度和摩阻速度的函数。探讨分析了尾流函数的空间分布和潮周期过程。非恒定流的水流尾流函数项的准确表达,对于揭示含沙水流流速结构及水、沙相影响作用规律将起到启发和推动作用。     

Effect of Berm Width and Elevation on Irregular Wave Run-Up

This paper discusses the effect of berm width and elevation of composite slope on irregular wave run-up. Based on the data obtained from model tests, the formula and distribution of irregular wave run-up on composite slope are derived. The changing of wind speed, width and elevation of the berm are considered comprehensively. The wave run-up with various exceedance probability can be es-timated utilizing the distribution curves of irregular wave run-up.     

南海輓近海平面变化与构造升降初步研究

揭示南海輓近海平面变动和古岸线诸多遗迹,探讨晚更新世以来海平面变化一般规律,初步分析南海周缘中全新世和现代地壳构造升降速率,得出本区海平面上升率适中参考值为0.10—2.0mm/a,初步估算未来50年内海平面变化趋势在1.26—4.0mm/a之间;而构造升降受块断差异运动控制,一般规律是南海北部沿岸自东向西递减,由福建南部1.15mm/a至海南岛南部0.54mm/a。近代地壳形变资料亦证实这种变化规律。     

Effect of free surface and strut on fins attached to a strut

An extensive experimental and computational investigation of the combined and separate effects of free surface and body on the lift characteristics of a pair of fins attached to a strut and fin alone is conducted. The results reveal that the free-surface effect becomes significant when the depth of submergence to chord ratio (H/c) is less than three. The effect of the strut is also realized for shallower depth of submergence of the fins through free-surface deformation leading to a significant change in the incidence angle of the flow to the fins. The numerical results based on the Higher Order Boundary Element Method with the linearized free-surface condition show good agreement with the experimental results for fin (foil) alone even at shallow submergence, but some discrepancies appear for the fin attached to the strut at higher speeds mostly due to the neglect of the nonlinear free-surface effect.     

晚中生代─新生代南海周缘地块运动与南海演化

报道了由华南几个盆地的古地磁数据综合而得的反映该区白垩纪以来古纬度变化曲线，结合Ｓｃｈｍｉｄｔｋｅ等（１９９０）发表的加里曼丹１５０Ｍａ以来的古地磁数据，表明华南与加里曼丹在４０Ｍａ前具有大致相同的古纬度变化史，差异仅出现在距今３０Ｍａ前后和１０Ｍａ以来。若此趋势可靠，则可作出下列推断：（１）南海的扩张只能发生在距今３０Ｍａ附近或１０Ｍａ以后华南与加里曼丹反向运动时期；距今３０Ｍａ的扩张已被广为接受；（２）华南与加里曼丹之向可能存在的古南海只能在９１Ｍａ之前存在；（３）南海演化可能存在两期扩张。南海的拟合可通过沿３５００ｍ等深线的先道时针旋转、后北向平移两个步骤完成。这与Ｈａｙａｓｈｉｄａ等（１９９１）提出的日本海张开与扩张模式很相似，提示东亚边缘海的形成和演化可能具有同样的机制。华南距今５０Ｍａ以来的古纬度变化与Ｔａｐｐｏｎｎｉｅｒ（１９８２）的传播挤出构造模式所预期的基本吻合，表明距今５０Ｍａ以来华南古纬度变化的运动学机制可用Ｔａｐｐｏｎｎｉｅｒ模式作解释。     

A Sensitivity Analysis of the Waterline Method of Constructing a Digital Elevation Model for Intertidal Areas in ERS SAR scene of Eastern England

A sensitivity analysis of the waterline method of constructing a Digital Elevation Model (DEM) of an intertidal zone using remote sensing and hydrodynamic modelling is described. Variation in vertical height accuracy as a function of beach slope is investigated using a set of nine ERS Synthetic Aperture Radar (SAR) images of the Humber/Wash area on the English east coast acquired between 1992 and 1994. Waterlines from these images are heighted using a hydrodynamic tide-surge model and interpolated using block kriging. On 1:500 slope beaches, an average block height estimation standard deviation of 18–22 cm is achieved. This rises to 27 cm on 1:100 slope beaches, and 32 cm on 1:30 slope beaches. The average heighting error at different slopes is decomposed into components due to waterline heighting error, inadequate sensor resolution and interpolation inaccuracy. It is shown that, at 1:500 slope, waterline heighting error and interpolation inaccuracy are the main error sources, whilst at 1:30 slope, errors due to inadequate sensor resolution become dominant. The ability of the technique to generate intertidal DEMs for almost the entire coastal zone in a complete ERS SAR scene covering 100×100 km is demonstrated.     

浅述多元数据处理的一种简化拟合形式及算法剖析

在实际工程试验与研究中 ,多元数据处理经常遇到 ,根据 Weierstrass定理 ,采用多项式拟合是一种常见的数据处理方法。对于多元多项式的系数求解问题 ,可以归结为超定方程组的求解问题。该文以超定方程组的 SVD求解算法为核心 ,阐述了在工程实际中关于多元数据处理的一种应用方法 ,并尝试给出多元多项式拟合的一种简化方法