基于GA-SVR的渗透系数参数反演方法

渗透系数参数反演的本质是优化问题求解,遗传算法是一种基于自然选择和群体遗传机理的新的全局优化求解方法,可以较好地用于求解诸如渗透系数参数反演等复杂非线性组合优化问题。基于结构风险最小化原理的支持向量机具有逼近复杂非线性系统、较强的学习泛化能力,可以用来计算渗透系数参数反演过程中的测点水头值。实验表明,基于遗传算法-支持向量回归机的地下水渗透系统参数反演拟合效果良好,能大大提升区间搜索效率,避免出现局部最优解,其参数识别精度符合实际应用要求。     

Impact of Urbanization and Industrialization upon Surface Water Quality:A Pilot Study of Panzhihua Mining Town

In order to investigate the impact of urbanization and industrialization on surface water quality,a pilot study of Panzhihua mining town was carried out.The urbanization of Panzhihua region was dominated by industry development and population growth.The level of urbanization showed that it was 18.44% in 1965,and reached 45.99% in 1983.Then,it reached 53.71% in 2005,so the urbanization process was very rapid in Panzhihua region.In the process of industrialization,the level of industrialization was fluctuated...     

Comparisons of internal solitary wave and surface wave actions on marine structures and their responses

In this paper, a time-domain numerical model is established for computing the action of internal solitary wave on marine structures and structure motion responses. For a cylindrical structure, its side and bottom are discretized by pole and surface elements, respectively. The drag and inertial forces in the perpendicular direction of the structure are computed by the Morison equation from the pole elements, and the Froude–Krylov force in the axial direction of the structure due to internal wave motion is computed by integration of the dynamic pressure over the surface elements. The catenary theory is used to analyze the reaction force due to mooring lines, and the motion equation of the marine structure is solved by the fourth-order Runge–Kutta method in the time domain. The model is used to calculate the interaction of the internal solitary wave with a Spar platform with mooring system, and the surface wave action with the platform has also been computed by a frequency-domain boundary element method for comparison. Through the comparison based on a practical internal wave and surface wave states, it can be concluded that the internal wave force on the structure is only 9% of the one due to surface waves. However, the motion response due to the internal wave is much greater than the one due to the surface waves. It shows that the low-frequency effect of internal solitary waves is a great threat to the safety of marine structures.     

基于土地利用变化的生态系统服务价值核算——以江苏盐城滨海湿地为例

长三角一体化与江苏沿海开发上升为国家战略,使盐城滨海湿地面临空前的发展压力,如何正确认识滩涂的价值并加以合理利用是制定各项方针政策的前提.运用1987、1992、1997、2002、2007年共5个时相相Landsat数据来获得土地利用和景观的时空变化信息,综合运用直接市场价值法、间接市场价值法、替代成本法、Costa...     

基于半分析模型的高光谱遥感水深探测方法

海岸带浅水和底质的成分复杂且分布不均,使遥感水深探测面临很大挑战.尝试通过利用Hydrolight 仿真建立的遥感反射率半分析模型来解决这个问题.采用英属维尔京群岛彼得岛的高光谱影像,应用非线性优化的方法提取了水下地形.从反演水深和海图标注水深拟合的趋势线斜率为0.939 2,决定系数为0.825 8.试验结果证明,使...     

大长细比柔性杆件涡激振动实验

涡激振动(vortex-induced vibration,VIV)是导致深海细长柔性立管发生疲劳破坏的重要因素。采用实验观测手段研究了长细比为1 750的柔性立管多模态涡激振动特性。实验中,通过采用拖车拖拉立管模型在水池中匀速行进来模拟均匀流作用下的涡激振动响应。利用光纤光栅传感器测量立管模型在横流向(cross-flow,CF)和顺流向(in-line,IL)的应变,进而通过模态分解的方法,获得立管模型涡激振动的位移。在此基础上,研究了CF以及IL方向的响应频率、位移标准差的平均值和最大值等随流速的变化规律,并分析了立管模型上测点的运动轨迹及其影响因素。     

Some tests and improvements to the VFISV: Very Fast Inversion of the Stokes Vector for the Helioseismic and Magnetic Imager

Some experimental tests and improvements to the Very Fast Inversion of the Stokes Vector program, which is designed for the inversion calculation used by the Helioseismic and Magnetic Imager instrument on the Solar Dynamics Observatory,are given. On one hand, the interpolation for calculating the Voigt function is not smooth, which may occasionally cause the iteration process to converge to different minima although they are very close to initial values. This problem can be solved by a smoother interpolation. On the other hand, in order to improve the performance of this program, we have tried to abandon the randomly-jump-out strategy and set the initial value properly to avoid non-global minima. The resulting method costs only1/4 of the computational time, and will be very competitive when the users are only interested in the vectorial magnetic fields and the velocities along the line of sight.     

Distribution characteristics,exploration and development,geological theories research progress and exploration directions of shale gas in China

The shale gas resources in China have great potential and the geological resources of shale gas is over 100×10¹²m³,which includes about 20×10¹²m³ of recoverable resources.Organic-rich shales can be divided into three types according to their sedimentary environments,namely marine,marine-continental transitional,and continental shales,which are distributed in 13 stratigraphic systems from the Mesoproterozoic to the Cenozoic.The Sichuan Basin and its surrounding areas have the highest geological resources of shale gas,and the commercial development of shale gas has been achieved in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in these areas,with a shale gas production of up to 20×10⁹m³ in 2020.China has seen rapid shale gas exploration and development over the last five years,successively achieving breakthroughs and important findings in many areas and strata.The details are as follows.(1)Large-scale development of middle-shallow shale gas(burial depth:less than 3500 m)has been realized,with the productivity having rapidly increased;(2)breakthroughs have been constantly made in the development of deep shale gas(burial depth:3500-4500 m),and the ultradeep shale gas(burial depth:greater than 4500 m)is under testing;(3)breakthroughs have been made in the development of normal-pressure shale gas,and the assessment of the shale gas in complex tectonic areas is being accelerated;(4)shale gas has been frequently discovered in new areas and new strata,exhibiting a great prospect.Based on the exploration and development practice,three aspects of consensus have been gradually reached on the research progress in the geological theories of shale gas achieved in China.(1)in terms of deep-water fine-grained sediments,organic-rich shales are the base for the formation of shale gas;(2)in terms of high-quality reservoirs,the development of micro-nano organic matter-hosted pores serves as the core of shale gas accumulation;(3)in terms of preservation conditions,weak structural transformation,a moderate degree of thermal evolution,and a high pressure coefficient are the key to shale gas enrichment.As a type of important low-carbon fossil energy,shale gas will play an increasingly important role in achieving the strategic goals of peak carbon dioxide emissions and carbon neutrality.Based on the in-depth study of shale gas geological conditions and current exploration progress,three important directions for shale gas exploration in China in the next five years are put forward.     

许昌市地质环境恶化问题及防治对策

本文利用近期地质环境监测资料，对许昌市地质环境恶化问题作了简述，并提出了防治措施。