Main Features and Problems of Modern Evolution Process of Coastal Wetlands in North Jiangsu,China

Based on field monitoring and remote sensing extraction, this paper analyzed the landscape evolution, reclamation process and transformation characteristics in north Jiangsu coastal region since 1980 through landscape transfer analysis, landscape spatial conversion model, and landscape dynamicity model. Results indicated that natural wetland decreased while in contrast the artificial wetland increased. Natural wetland was mostly converted into mudflats, and large proportion of mudflats were subsequently exploited into aquaculture waters, and other man-made construction projects. Significant transformation ranking ahead were mudflat to aquaculture waters, Suaeda glauca to dry land, Suaeda glauca to aquaculture waters, Couch grass to aquaculture waters, respectively. The proportion of transformation caused by anthropogenic activities was up to 82%, much higher than natural succession. Coastal ecological systems were severely disturbed and destroyed largely due to wetland reclamation and resources exploitation. The results suggest that the impact of human activity on wetland ecology needs more attention.     

淮河管桥的安全性与剩余寿命评估方法研究

本文在文献［１］的基础上，进一步运用现代断裂力学和结构系统可靠性分析原理，导出了一种处理多种交变应力引起结构系统疲劳失效的计算方法，提出了一种考虑构件腐蚀、在交变应力及地震力作用下结构系统安全寿命的评估方法，并开发出相应的计算机软件，对淮河跨越管桥结构系统进行评估，验证了该方法的有效性和可靠性。     

绿洲夜间“冷岛效应”的模拟研究

本文利用一维地气耦合模式，并考虑大气长波辐射的影响，模拟HEIFE期间绿洲、戈壁和沙漠夜间大气边界层的演变，对夏季夜晚绿洲近地面气温低于沙漠的现象作出解释，并运用实际观测资料加以论证。在总结前人研究成果的基础上，利用数值试验，得出绿洲夜间“冷岛效应”形成的主要原因在于风速较小与夜间蒸发，从而排除了归因于绿洲、沙漠辐射方面的差异的可能性。     

Numerical studies on the failure process and associated microseismicity in rock under triaxial compression

In this paper, firstly the mesoscopic elemental mechanical model for elastic damage is developed and implemented into the rock and tool interaction code (R-T^2D). Then the failure processes of a heterogeneous rock specimen subjected to a wide variety of confining pressures (0–80 MPa) are numerically investigated using the R-T^2D code. According to the simulated results, on the one hand, the numerical simulation reproduced some of the well-known phenomena observed by previous researchers in triaxial tests. Under uniaxial compression, rock failure is caused by a combination of axial splitting and shearing. Dilatancy and a post-failure stage with a descending load bearing capacity are the prominent characteristics of the failure. As the confining pressure increases, the extension of the failed sites is suppressed, but the individual failure sites become dense and link with each other to form a shear fracture plane. Correspondingly, the peak strength, the residual strength and the shear fracture plane angle increase, but the brittleness decreases. When the confining pressure is high enough, the specimen behaves in a plastic manner and a narrow shear fracture plane leads to its failure. The prominent characteristics are volume condensation, ductile cataclastic failure, and a constant load bearing capacity with increasing strain. On the other hand, the numerical simulation revealed some new phenomena. The highest microseismicity events occur in the post-failure stage instead of the maximal stress, and most of the microseismicity energies are released in the failure localization process. As the confining pressure increases, the microseismicity events in the non-linear deformation stage increase dramatically and the ratio between the energies dissipated at the non-linear deformation stage and those dissipated in the whole loading process increases correspondingly. Therefore, it is concluded that the developed mesoscopic elemental mechanical model for elastic damage is able to reproduce accurately the failure characteristics in loading rock specimens under triaxial conditions, and the numerical modelling can furthermore obtain some new clarifications of the rock fracture process.     

In-situ Measurements of Cutter Forces on Boring Machine at Äspö Hard Rock Laboratory Part I. Laboratory Calibration and In-situ Measurements

Summary This paper presents the testing methods used and the results obtained in an investigation of the cutter forces on a Boretec DS 1.6 boring machine during field boring in ?sp? Hard Rock Laboratory. Two button cutters, one front cutter and one gauge cutter, were used in the field measurements. A total of 6 strain gauges were bonded on the shaft of each cutter. And each group of two gauges was used to measure a one-orthogonal cutter force component, i.e. the normal force, tangential force, and side force, respectively. In order to measure the cutter forces successfully, a telemetry system composed of a transmitter and a receiver was employed to transfer the signals from the strain gauges to a computer.  A three-direction-loading system was employed in the laboratory calibration so as to solve the force-coupling problem appearing in the cutter force measurements. Correspondingly, a mathematical treatment of the force-coupling problem was performed. Then, by means of the established testing system, which was proved successful in the laboratory, the normal force, tangential force, and side force of the two button cutters on the boring machine were measured in the field. In addition, the penetration rate, thrust, and rotation speed of the boring machine were also recorded in the field. The results show the following. (1) A force-coupling phenomenon really exists and it should be considered. (2) All three directional force components always show quite a high peak value every few seconds. (3) The cutter forces of the front cutter are always much larger than the respective cutter forces of the gauge cutter. Moreover, as expected, the normal force of each cutter is much larger than the tangential force and side force of the cutter in question. Received October 5, 2001; accepted June 25, 2002; Published online November 19, 2002     

气旋生成机制的位涡反演诊断

本文采用位涡反演方法,对一次西太平洋地区爆发性气旋的生成机制进行了诊断分析。结果表明：高层位涡扰动（即高空槽脊系统）所诱生的低层扰动风场特征为一支位于高空槽前下方的偏南气流,这支偏南气流是促使低层锋区扰动发展的主要动力因子：而低层位涡扰动（即低层锋区扰动）所诱生的低层扰动位势场和扰动风场是低层降压和气旋性环流生成的主要原因。     

2002年6月20～24日梅雨锋中尺度对流系统发生发展分析

利用“973”中国暴雨试验获得的加密观测资料 ,首先对 2 0 0 2年 6月 2 0～ 2 4日发生在长江中下游地区的中尺度对流系统发生发展进行了分析 ,有 7个尺度较大的α中尺度对流系统在长江中下游地区发展 ,造成了大范围的强降雨。然后针对安徽南部发生的中尺度对流系统发生发展过程进行了详细分析 :MCS生成于切变线南侧的西南暖湿气流中 ,其源地是大别山区和大别山与九华山之间的长江河谷地带 ;低层西南风的水汽输送是安徽南部对流不稳定和对流有效位能积聚的主要原因 ;在降雨发生前整层可降水量有明显增加 ,开始降雨后则逐渐减小。雷达探测的回波显示α中尺度对流系统中有 β和γ中尺度系统的活动 ,β和γ中尺度系统与整个中尺度对流系统的移动方向不一致 ;中尺度对流系统中的带状回波有地面中尺度辐合线配合 ,对流带随地面的中尺度辐合线移动 ,对流带中的对流单体沿辐合带移动。     

一种改进的降水临近外推预报技术方法研究及效果检验

中尺度模式对于0～2h的预报存在起转问题,因此外推预报成为0～2h临近预报中不可或缺的技术方法。目前INCA(Integrated Nowcasting through Comprehensive Analysis System)降水外推预报中,外推矢量扰动由外推矢量随时间的变化确定,即相邻时次外推矢量差确定,本文统计2017年7月江淮地区(29°～35.5°N,114°～120°E)INCA系统相邻10min外推矢量偏差来代表外推矢量随时间变化。若降水向东北方向移动,则外推矢量方向规定为东北方向。统计结果表明:①对于江淮地区,外推矢量以东北方向和西南方向偏差为主,外推矢量越大,其偏差的大小越大;②从外推矢量方向看,东北方向外推矢量占绝大多数(73%),可能是因为绝大多数降水发生在槽前形势下,引导气流为西南风。基于外推矢量偏差统计样本,随机生成多个符合外推矢量偏差分布的外推矢量扰动,得到多个不确定的外推矢量,将INCA确定性外推预报变为0～2h降水外推集合预报,采用均方误差(MSE)、TS评分、BIAS评分和Brier技巧评分等方法,对集合预报结果检验表明:随着预报时效增加,集合预报比确定性预报的优势更明显。因此,考虑外推矢量的不确定性可以提高降水外推预报准确率。     

古城601井井身结构优化设计

古城地区实钻中存在表层窜冒、却尔却克组大段难钻“黑被子”地层、H2S、卡钻、井漏、溢流、井塌、地层压力温度高等技术难点，导致该区块钻井周期长、钻井成本高。针对古城地区地质特点，结合古城601井钻井目的及完井方式，综合考虑地层压力、必封点等井身结构设计关键点，在保障安全和质量的前提下，对古城601井进行了井身结构优化设计，并经实钻验证该设计思路合理，为古城地区井身结构设计提供了新思路。