渤海海面太阳辐照强度的观测分析与计算方法研究

对渤海海面(1998-09-24～10-07和1999-04-28～05-11)实测太阳辐射日总量同云量的关系和春、秋季的对比关系及其与插值计算出的晴日太阳辐射日总量的关系进行了分析,并同烟台(福山)测站的结果进行了对比分析.通过分析发现,渤海海面太阳辐射日总量春季远大于秋季,其无云条件下的太阳辐射日总量与插值计算出的晴日太阳辐射日总量的差异秋季大于春季.分析表明,海陆温差引起的海面大气垂直输送与水汽物的产生是造成这种差异的主要原因.采用经验公式对渤海海面太阳辐射日总量进行计算,计算结果与实测结果具有较好的一致性.结果表明所用经验公式及推算出的参数适合于春、秋季渤海海面太阳辐照度的计算.     

一次热带气旋环流暴雨与前期一般性降水环境场的对比分析

登陆的台风环流暴雨是沿海地区重要的暴雨类型之一，降雨量大，范围广，危害大。本文应用诊断分析的方法，以1999年8月11日发生在山东半岛中东部大范围暴雨过程为实例，就暴雨发生前一般性降水时的环境场与暴雨发生时的环境场做了对比分析。结果表明，暴雨发生时均比暴雨发生前一般性降水时：低空辐合和高空辐散增强，低层水汽能量辐合及对流不稳定性增大，低空垂直环流发展。以上因子导致积云对流的发展。在弱垂直切变环境下，通过第二类条件不稳定(CISK)机制，使热带风暴减弱成的低气压环流维持，并促使中低压发生变化，使暴雨云团西行增强，暴雨增幅。     

On the interaction of a solitary wave and a submerged dike

The unsteady, two-dimensional Navier–Stokes equations and the exact free surface boundary conditions were solved to study the interaction of a solitary wave and a submerged dike. A piston-type wavemaker was set up in the computational domain to produce the incident solitary waves. The incident wave and the associated boundary layer flow in a wave tank with a flat bed were compared with the analytical solutions to verify the accuracy of this numerical scheme. Effects of the incident wave height and the size of the dike on the wave transformation, the flow fields, and the drag forces on the dike were discussed. Our numerical results showed that even though the induced local shear stress on the top surface of the dike is large at some particular locations, the resultant pressure drag is much larger than the friction drag. The primary vortex generated at the lee side of the dike and the secondary vortex at the right toe of the dike may scour the bottom and cause a severe problem for the dike.     

Predictions of the hydrodynamic performance of the wave rotor wave energy device

This paper provides a linear solution for the Wave Rotor, a wave energy device that comprises two parallel counter rotating cylinders in orbital motion. Theoretical results are obtained for the radiated waves generated by the device, and for its efficiency. Comparisons with earlier measurements of radiated waves show very promising agreement.     

Coastline configuration disrupts the effects of large-scale climatic forcing, leading to divergent temporal trends in wave exposure

Both climate change and the North Atlantic Oscillation (NAO) may influence coastal systems by altering wave exposure. The effects of such climatic forcing are often coherent over relatively large geographic areas. Temporal trends in wave exposure at any particular shore are, however, the result of an interaction between site-specific fetch characteristics and changes in wind climate. This leads to contrasting trends in wave exposure at locations separated by no more than a few kilometres. Wave exposures were estimated at locations around a sea lough over 32 years to characterise these scales of variability. Locations separated by approximately 5 km had independent dynamics with respect to the temporal trend (correlation range −0.35 to 0.44) and to associations with the NAO (correlation range −0.18 to 0.40). Wave exposure can therefore be increasing for a section of shore while nearby areas have the opposite trend. Mean exposure at a location was not a good predictor of the temporal trend. More exposed sites were, however, sensitive to variations in the strength of the NAO. The reduction of large scale forcing to small-scale variability has implications for the detection and mitigation of potential climate change impacts.     

Second-order wavemaker theory for multidirectional waves

The present paper develops the complete second-order wavemaker theory for the generation of multidirectional waves in a semi-infinite basin. The theory includes superharmonics and subharmonics and is valid for a rotational as well as a translatory serpent-type wave-board motion. The primary goal is to obtain the second-order motion of the wave paddles required to get a prescribed multidirectional irregular wave field correct to second order, i.e. to suppress spurious free-wave generation. The wavemaker theory is a 3D extension of the full second-order wavemaker theory for wave flumes by Schäffer (1996).     

改进波浪发电浮标性能的试验研究

为了改进波浪发电浮标为性能，以及推广使用，使之能适用于波浪周期短波高小的海区，对上海航标厂的波浪发电浮标为浮体进行了试验研究。试验测量了气室压力、内波高、浮体升沉等物理量。通过输出功率的比较，提出了浮体设计方案的建议。     

Deterministic combination of numerical and physical coastal wave models

A deterministic combination of numerical and physical models for coastal waves is developed. In the combined model, a Boussinesq model MIKE 21 BW is applied for the numerical wave computations. A piston-type 2D or 3D wavemaker and the associated control system with active wave absorption provides the interface between the numerical and physical models. The link between numerical and physical models is given by an ad hoc unified wave generation theory which is devised in the study. This wave generation theory accounts for linear dispersion and shallow water non-linearity. Local wave phenomena (evanescent modes) near the wavemaker are taken into account. With this approach, the data transfer between the two models is thus on a deterministic level with detailed wave information transmitted along the wavemaker.     

BinSq: visualizing geographic dot density patterns with gridded maps

ABSTRACT

Dot maps have become a popular way to visualize discrete geographic data. Yet, beyond showing how the data are spatially distributed, dot maps are often visually cluttered in terms of consistency, overlap, and representativeness. Existing clutter reduction techniques like jittering, refinement, distortion, and aggregation also address this issue, but do so by arbitrarily displacing dots from their exact location, removing dots from the map, changing the spatial reference of the map, or reducing its level of detail, respectively. We present BinSq, a novel visualization technique to compare variations in dot density patterns without visual clutter. Based on a careful synthesis of existing clutter reduction techniques, BinSq reduces the wide variety of dot density variations on the map to a representative subset of density intervals that are more distinguishable. The subset is derived from a nested binning operation that introduces order and regularity to the map. Thereafter, a dot prioritization operation improves the representativeness of the map by equalizing visible data values to correspond with the actual data. In this paper, we describe the algorithmic implementation of BinSq, explore its parametric design space, and discuss its capabilities in comparison to six existing clutter reduction techniques for dot maps.     

基于测量笔的模具刻线测量

针对模具工业对于模具刻线检测的迫切需求,首次将测量笔式单相机位姿测量系统引入模具刻线测量。基于单片空间后方交会原理建立测量笔坐标系与世界坐标系的关系,通过公共点转换求解刻线上测量点的三维坐标;再将所有测量点与CAD模型进行比对,得到刻线精度(均方根值)。实际工程应用表明该系统摄站灵活方便,测量精度高,在3 m范围内测得刻线精度优于0.5 mm,完全可以满足大尺寸测量中的刻线检测精度要求。