Physical modelling of sand injectites

Sand injectites are structures that result from intrusion of fluidized sand into fractures. We have studied them in the Tampen Spur area of the North Sea, and have reproduced them experimentally, by driving compressed air through layers of sand, glass microspheres, and silica powder. The silica powder was cohesive and capable of hydraulic fracturing, whereas the sand and glass microspheres were almost non-cohesive and therefore able to fluidize. The models were dynamically similar to their natural counterparts, for as long as equilibrium was static. When the processes became dynamic, so that inertial forces were significant, the scaling was approximate and the corresponding Reynolds numbers differed. The experimental apparatus was a square box, 1 m × 1 m wide, resting on a grid of fluid diffusers. During the experiments, the fluid pressure increased, until it attained and surpassed the weight of overburden. Flat-lying hydraulic fractures, containing air, formed within cohesive and least permeable layers. Heterogeneities in material properties and layer thicknesses were responsible for localizing fracture networks. When any one network broke through to the surface, rapid flow of air through the fractures fluidized the underlying mobile materials and even depleted some of the layers. Some of the fluidized material extruded at the surface through vents, forming volcanoes and sheets. The remainder lodged at depth, forming sand injectites or laccoliths. Conical sand injectites formed preferentially, where layers had high resistance to bending. Laccoliths formed nearer the surface, where overlying layers had low resistance to bending. The experimental sand injectites were broadly similar to those in the Tampen Spur area of the North Sea, as well as other areas.     

基于FLUS-UGB的县域土地利用模拟及城镇开发边界划定研究

当前城镇开发边界的制定与已有基本农田和生态保护红线存在较大的龃龉,在新的国土空间规划体系下,需要科学划定县域合理的城镇开发边界以实现国土空间的可持续开发利用。对此,本文提出了基于三线协调和FLUS-UGB的城镇增长边界划定方法,以江苏省丰县为研究案例,在对其2011—2017年土地利用进行模拟和验证的基础上预测了至2035年的多情景土地利用变化,结合耕地保护与生态控制背景,最终确定城镇增长边界。结果表明：① 2017年丰县土地利用模拟的总体精度达到94.7%,Kappa系数为0.895,模拟精度较高。② 基准情景下,城镇用地呈现“摊大饼”的空间扩张趋势。在耕地保护与生态控制背景下,城镇呈“放射式”向外有序扩张。③ 预测2035年丰县城镇用地开发边界面积为80.29 km²,2017—2035年共17年增长幅度达到69.07%。明确划分城镇开发边界能够有效避免城镇用地对永久基本农田和重要生态用地的侵占,从而实现城镇扩张、永久基本农田和重要生态用地保护三者之间的良好空间协调。     

El Nino年和La Nina年的非线性临界层与副高的形成、维持和振荡

采用欧洲中心１９８２年１２月、１９８３年４月、１９８４年１０月和１９８５年４月的月平均纬向风场实际观测资料,作为非线性临界层模式的基本气流进行数值积分,得到：用１９８２年１２月和１９８３年４月的基流模拟出的副高强、范围大、数目少,维持２￣３个单体,且向西移,东西振荡周期１－２个月。用１９８４年１０月和１９８５年４月的基流模拟出的副高弱、范围小,成带状分布,数目多达４个单体,副高合并、分裂得较快,亦     

用VB语言实现地震动态演示

Ｖ Ｂ 编程语言提供了图形环境,能可视化的设计窗体和控件。本文介绍了应用该设计语言的特性如何实现地震资料的动态显示过程。     

基态位涡径向分布对浅水涡旋系统演变的影响分析Part Ⅱ:扰动发展和结构变化

本文在基态位涡（Potential Vorticity,PV）径向分布和基态涡旋强度对热带气旋（Tropical Cyclone,TC）类涡旋系统稳定性特征影响的研究基础上,结合理想试验和数值模拟诊断分析基态PV径向分布对扰动增长和系统结构变化的影响.基于线性正压浅水模型,设计三种典型基态PV中空结构下基态涡旋强度对系统稳定性影响的敏感性试验.结果表明：基态涡旋的强度主要影响稳定性的强弱,强度越强,不稳定增长率越大,而基态PV径向分布对系统最不稳定波动性质起着决定作用.分析不同波数下扰动的发展及不同波数间扰动的相互作用可知,对于宽且实的PV环,系统稳定性主要取决于低波数不稳定,且最不稳定波数扰动的发展具有明显的优势地位;对于窄且空的PV环,系统稳定性主要取决于高波数不稳定,且多个高波数下增长最快模态的不稳定增长率值十分接近.利用模态线性叠加法讨论扰动增长对系统结构变化的影响表明：最不稳定波数的扰动发展对系统结构变化有关键影响,而多个波数的扰动不稳定增长相当时,不同波数的扰动发生相互作用从而影响系统结构变化.最后,利用实际个例模拟资料分析基态PV径向分布及其变化对TC结构和强度的影响表明：TC内核区出现的多边形眼墙结构与当前时刻基态PV径向分布所决定的最不稳定波数有很好的对应关系,同时基态PV径向分布变化所反映出的系统动力稳定性强弱与TC强度发展阶段具有很好的相关性.     

上海市集中测绘成果管理系统的建设与维护

本文在深入调研上海市集中测绘成果管理系统的基础上,通过对系统的建立与长期维护的总结,简要的介绍了系统实现的功能与系统架构,总结了系统建设过程中的思路与做法。着重阐述了系统在整合测绘处理与成果管理、保持基础数据的现势性方面所取得的成果,总结了系统在建设与使用过程中的优缺点,为其它地区建立或改造测绘成果系统提供借鉴。     

AutoCAD二次开发与横断面绘制

AutoCAD的二次开发技术是许多领域内专用软件的开发技术,它有利于该领域内绘图效率的提高。本程序是为通惠排干渠横断面测量开发的一个小程序,主要是针对横断面图绘制部分。程序中利用AutoCAD二次开发技术,采用Visual Basic 6.0,AutoCAD VBA为平台,通过AutoCAD ActiveX Automation接口将消息发送到Au-toCAD。AutoCAD VBA允许VBA环境与AutoCAD同时运行,并通过ActiveX Automation接口对AutoCAD进行编程控制,在Visual Basic 6.0中用代码进行参数化自动绘图。程序可以实现横断面图自动生成。为方便使用者操作,程序设计了与AutoCAD交互的界面,用户只需要在对话框中输入数据文件名,其余的绘图工作由程序自动完成。     

Highlights of Recent Scientific Earthquake Hazard Mitigation

Earthquakes are a serious natural disaster faced by countries all over the world. Research on earthquake hazard mitigation are important parts of earthquake science and is a feature of China''s development of earthquake science. In recent years, the Ministry of Science and Technology (MOST) of the People''s Republic of China, the National Natural Science Foundation of China (NSFC) and the China Earthquake Administration (CEA) have attached great importance to basic research on earthquake hazard mitigation, and new opportunities and challenges have emerged. This paper collects the applications and approvals of the National Key R&D Program and the NSFC projects undertaken by the research institutes of the CEA system in recent years. The CEA system has received funding in the 13th “Five-year Plan” for “Monitoring, Early Warning and Prevention of Major Natural Disaster”. The implementation of these projects is expected to provide support for the basic science and applied research of the CEA system. In the NSFC, the number of applications from the CEA system is relatively stable, and the funding rate is slightly higher than the average for the department of earth science. Although no detailed statistical analysis has been performed, the CEA system still has room for improvement in the application of talent and major programs. I hope that the brief review of new opportunities that have arose in recent years described in this article can provide some background and new thinking for future challenges.     

从二维地转风到三维涡旋运动

给出了大气三维涡旋运动基本态所满足的简洁的偏微分方程. 大气涡旋运动存在低压辐合上升和高压辐散下沉的基本状况，基本态的三维速度场可以用流函数和对流速度势分解，且具有螺旋结构. 当Reynolds数Re→∞时，涡旋运动就化为地转风，涡旋运动近似就化为地转风近似.     

Plume rise and spread in a linearly stratified environment

We present analyses of plume rise into a linearly stratified environment, either with or without a uniform horizontal flow. In the case of a still ambient, we collate results on plume spreading height and volume flux, enabling the speed of the spreading intrusion in the buoyancy-inertia regime to be expressed in terms of the fundamental parameters of plume buoyancy flux and ambient buoyancy frequency. A theoretical expression for the final volume flux emanating from the plume-rise region, in terms of maximum rise height, is also derived. Hence it is shown that the ratio of the intrusion radius to the maximum rise height is a simple function of ambient buoyancy frequency and time. In the case of a wind, we analyse the theoretical model for a rising plume to obtain predictions for the downwind volume flux, and subsequent lateral spread, in the limits of strong and weak wind. We identify a regime of very weak wind, which may be modelled as a passive advection of plume flow in the still case as a first approximation. Numerical solutions of a general model are presented which show that it predicts a peak in entrainment, and hence volume-flux growth, in the case of intermediate wind strength. We verify the crosswind model predictions of lateral spread, upwind penetration and entrainment by comparison with large-eddy simulations.