共查询到20条相似文献，搜索用时 57 毫秒
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探讨了windows编程环境下，编绘软件的网络实现方法。通过对WinSock编程方法的讨论，表明了编绘软件电子图板实现网络化编辑的可行性。 相似文献
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基于MapObjects组件的海岸带地理信息系统开发最佳技术 总被引：1，自引：0，他引：1
本文采用组件式 GIS软件 Map Objects2 .1和编程工具 Visual Basic6 .0对海岸带地理信息系统的开发思路、对象类型、系统结构和主要功能等做出讨论 ,并对海岸带地区的矢量与栅格数据在 Map Objects2 .1中的配准以及编程方法等进行分析。结果表明 ,Map Objects2 .1由于其灵活、高效、独立性强、兼容性强等特点可以有效管理海岸带数据 ,为海岸带管理提供有力的支撑 相似文献
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本文以海域管理信息系统的开发为例，研究探讨了VB结合MapObjects2．2进行GIS开发中长度量算功能的实现方案，详细介绍了长度量算的不同方式及具体编程实现方法。 相似文献
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The most common method of reducing roll motion of ship-shaped floating systems is the use of bilge keel which act as damping elements. The estimation of the damping introduced by bilge keel is still largely based on empirical methods. The present work adopts the CFD approach to the estimation of roll damping, both without and with bilge keel and validates the results with experiments conducted in a wave flume. Specifically, free oscillation tests are conducted at model scale to obtain roll damping, both by experiments and CFD simulation and reasonably good comparisons are obtained. The experiments also include PIV study of the flow field and attempt has been made to correlate the measured flow field with that obtained by CFD. The CFD methodology has the potential to determine rationally the size and orientation of bilge keels in design with reasonably accurate estimate of the additional roll damping that it provides to ship's roll motion. 相似文献
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In this study, we develop a numerical method for a 3D linear hydroelastic analysis of floating structures with liquid tanks subjected to surface regular water waves and compare the numerical results with experimental tests. Considering direct couplings among structural motion, sloshing, and water waves, a mathematical formulation and a numerical method extended from a recent work [1] are developed. The finite element method is employed for the floating structure and internal fluid in tanks, and the boundary element method is used for the external fluid. The resulting formulation completely incorporates all the interaction terms including hydrostatic stiffness and the irregular frequency effect is removed by introducing the extended boundary integral equations. Through various numerical tests, we verify the proposed numerical method. We also performed 3D hydroelastic experimental tests of a floating production unit (FPU) model in an ocean basin. The measured dynamic motions are compared with the numerical results obtained using the proposed method. 相似文献
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The present paper reports on a study of the interaction of a current-free monochromatic surface wave field with a wave-free uniform current field in a three-dimensional flow frame. The wave and the current fields are not necessarily collinear with each other. The formulation of the wave-current field is done under the assumption of irrotational and inviscid flow. We have developed the three dimensional expressions describing the characteristics of the combined flow in terms of mass, momentum and energy transport conservation. These equations are found efficient to describe the sought-for combined wave-current field. The parameters describing the wave-current field after the interaction are the surface disturbance amplitude and length, mean water depth, mean current-like parameter and direction of the combined flow, which would be calculated from a set of equations that satisfy conservation of mean mass, momentum and energy flux and a dispersion relation on the free surface before and after the interaction. The results are shown in terms of relative changes in wave heights and lengths, current-like parameters and final directions obtained for the combined wave-current field with respect to current-free wave and wave-free current pre-interaction parameters. 相似文献
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目的：研究气阴两虚Lewis肺癌荷瘤模型小鼠的行为学特征、饮水量、摄食量、体质量及肺复方对上述指标及脏器指数的影响。方法：取C57BL/6J小鼠40只,将其随机分为空白组8只、造模组32只。造模组灌服热性中药水煎液合并烟熏制备气阴两虚模型（造模第一阶段,共14 d）,于第15天移植Lewis肺癌细胞（造模第二阶段,共14 d）,按性别、体质量分层随机分为模型组、顺铂组、肺复方组及顺铂+肺复方组（联用组）,连续进行药物干预14 d。以造模每阶段及药物干预第1天的体质量、饮水量和摄食量分别作为基础体质量、基础饮水量和基础摄食量。并于固定时间,每2 d记录动物饮水量和摄食量,每3 d记录动物体质量,药物干预结束后处理动物,测量、计算其去瘤体质量和肝、脾及胸腺的脏器指数。结果：造模第一阶段小鼠饮水量和摄食量减少,造模第二阶段小鼠体质量增加,气阴两虚Lewis肺癌荷瘤模型小鼠脾脏和肝脏指数升高,胸腺指数降低（P<0.05或P<0.01）。药物干预后各组小鼠活动量增加,肺复方组饮水量、体质量增加,顺铂组小鼠摄食量、体质量减少,脾脏指数、去瘤体质量降低,联用组小鼠饮水量增加、摄食量减少,脾脏、胸腺指数升高（P<0.05或P<0.01）。结论：气阴两虚Lewis肺癌荷瘤模型小鼠的饮水量和摄食量减少,体质量增加;肺复方可缓解模型动物口干少饮、形体羸瘦等症状,改善顺铂引起的不良反应,增加模型小鼠脾脏和胸腺指数;肺复方干预肺癌的作用机制可能与其增强机体免疫功能有关。 相似文献
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The three-dimensional scattering of cnoidal waves by cylinder arrays are studied numerically by using the generalized Boussinesq equations. The boundary-fitted coordinate transformation and a dual-grid technique are used to simplify the finite-difference computation. Also, a set of open boundary conditions and an incident cnoidal wave are incorporated for time-domain simulation. The free-surface elevation and hydrodynamic forces on each cylinder are calculated to illustrate the evolution of nonlinear waves and their interactions with large cylinder arrays. Comparisons are made between the present nonlinear wave loads and those obtained from linear diffraction theory. The sheltering role played by the neighboring cylinders and the feature of wave interference are discussed. 相似文献
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The characteristics of the fish faunas in nearshore, shallow (<1.2 m) waters of the basins of estuaries along the same coastline, but which were open to the ocean for varying periods, have been determined and compared. The fish faunas of the permanently-open Oyster Harbour, the seasonally-open Broke, Irwin and Wilson inlets and the normally-closed Wellstead Estuary on the south coast of Western Australia were sampled by seine net seasonally for 2 years. Irrespective of the frequency and duration that the estuary mouth was open, the ichthyofauna of each estuary was numerically dominated by three atherinid species and three gobiid species (92.9–99.7%), each of which completes its life cycle within these estuaries. The ichthyofaunal compositions of each estuary differed significantly, however, from that of each other estuary. These differences were largely attributable to the relative abundances of the above six species varying between estuaries, which, in turn, reflected differences in such factors as estuary mouth status, macrophyte cover and salinity. For example, Favonigobius lateralis and Leptatherina presbyteroides, which are also represented by marine populations, were most abundant in the permanently-open estuary (Oyster Harbour), which, in terms of substrate and salinity, most closely resembled the nearshore marine environment. In contrast, Leptatherina wallacei made its greatest contribution in the only estuary to exhibit a protracted period of greatly reduced salinities, which is consistent with its distribution in permanently-open estuaries on the lower west coast of Australia, while Atherinosoma elongata and Pseudogobius olorum were particularly numerous in estuaries containing dense stands of the seagrass Ruppia megacarpa. Marine species made the greatest contribution to species richness in the permanently-open estuary and least in the normally-closed estuary. Species richness was greatest in summer and least in winter in each estuary, but differed markedly between years only in Wilson Inlet. Density of fishes was greatest in the most eutrophic estuary (Wellstead Estuary) and least in the most oligotrophic estuary (Broke Inlet) and only underwent marked seasonal variations in Wilson Inlet and Wellstead Estuary, in which densities fell to their minima in winter. Ichthyofaunal composition varied between years in the Broke and Wilson inlets and Wellstead Estuary, in which there was little or no connection with the ocean in one of those years. Species composition underwent progressive seasonal changes throughout the year in Wellstead Estuary, due to the abundance of certain species peaking at different times of the year. 相似文献
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This work presents a canonical study on a wedge entering water near a single piece of ice using computational-fluid-dynamics (CFD) and a Wagner-type theoretical model with corrections for non-linear effects. Calculations for a series of conditions with ice of different sizes and locations relative to the wedge are conducted. The hydrodynamic force due to impact, the pressure distribution on the wedge surface, and the pile-up phenomenon are examined to study the role of ice in the impact process. The theoretical model is shown to be accurate and can serve as a useful method to assess slamming loads under the influence of ice. It is shown that even for the case of a small piece of ice, the slamming force on the wedge can increase by 30%. 相似文献
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The height of a wave at the time of its breaking, as well as the depth of water in which it breaks, are the two basic parameters that are required as input in design exercises involving wave breaking. Currently the designers obtain these values with the help of graphical procedures and empirical equations. An alternative to this in the form of a neural network is presented in this paper. The networks were trained by combining the existing deterministic relations with a random component. The trained network was validated with the help of fresh laboratory observations. The validation results confirmed usefulness of the neural network approach for this application. The predicted breaking height and water depth were more accurate than those obtained traditionally through empirical schemes. Introduction of a random component in network training was found to yield better forecasts in some validation cases. 相似文献