基于“流空间”视角的铁路客运空间组织分析——以长三角城市群为例     

陈维肖  刘玮辰  段学军 《地理研究》2020,39(10):2330-2344

当前,以“流空间”视角阐释现代交通运输方式在实现区域一体化中发挥的作用,通过关联性描述其网络空间组织过程,能为交通与城市体系互动发展提供科学支撑。基于此,以2000年以来铁路客运班次数据为依托,应用社区发现算法分析长三角城市群铁路客运网络及空间变化特征,结论如下：① 城市群发育出京沪社区、浙江社区、皖江社区和苏中北社区等子群,各社区内部为铁路客运联系的主要范围和方向,且表现出差异性空间联系格局变化;② 高内部联系社区具有较高外部社区间联系强度,枢纽城市间多发生跨社区高联系,形成不依赖于铁路可达性的“核心-边缘”式结构;③ 按空间特征将各社区分为单核心社区、双核心社区、多核心社区和无核心社区,从社区内联系模式看,核心城市数量不断减少、较高联系通道不断发育,但两者间存在不匹配;④ 从社区间联系模式看,高速铁路在增强跨社区交流过程中扮演重要角色,核心城市间联系增强,客运网络由通道指向转变为枢纽指向。  相似文献   

Early Cretaceous precious fossil-bearing beds in Weijialing—Yaolugou of Jianchang Basin,western Liaoning     

DUAN Ye  ZHANG Lijun Institute of Palaeontology  Shenyang Normal University  Shenyang  China 《东北亚地学研究》2009,12(2):87-93

The Jianchang Basin is one of the main localities of the precious fossils of Jehol Biota in western Liaoning. The fossil-bearing horizons are mainly in the Yixian- and Jiufotang formations. In the Weijialing- Yaolugou of southwest Jianchang Basin, many precious fossils have been found at Luojiagou Bed of the 2nd Member of the Yixian Formation and at Xidian Bed of the 1 st member of the Jiufotang Formation. The geologic setting, sedimentary environment and paleogeography of the precious fossil-bearing beds were also studied.  相似文献   

Estimation of Tsunami Run-up Height by Three Artificial Neural Network Methods     

Nuray GEDIK  Emel IRTEM  H.Kerem CIGIZOGLU  M.Sedat KABDASLI 《中国海洋工程》2009,23(1)

Tsunami run-up height is a significant parameter for dimemsions of coastal structures.In the present study,tsunami run-up heights are estimated by three different Artificial Neural Network (ANN) models,i.e.Feed Forward Back Propagation (FFBP),Radial Basis Functions (RBF) and Generalized Regression Neural Network (GRNN).As the input for the ANN configuration,the wave height (H) values are employed.It is shown that the tsunami run-up height values are closely approximated with all of the applied ANN methods.The ANN estimations are slightly superior to those of the empirical equation.It can he seen that the ANN applications are especially significant in the absence of adequate number of laboratory experiments.The restdts also prove that the available experiment data set can he extended with ANN simulations.This may be helpful to decrease the burden of the experimental studies and to supply results for comparisons.  相似文献   

Coupling Effect of Riser on Integrated FPS in Deepwater Area     

韩志强  Bernt J.Leira  李飒 《中国海洋工程》2009,23(4):613-622

The main challenge in predicting global responses of floating vessels in deepwater and ultra-deepwater areas comes from the system's coupled effect.In this paper,the coupled approach is used to analyze effects of riser on floating system in deepwater.The analysis results show that the coupling effects of risers will mainly affect the low frequency (LF) motions of the system.That is because risers will provide the system with a significant low frequency (LF) damping which will vary with the sea states.Under ...  相似文献   

Stability Analysis on Speed Control System of Autonomous Underwater Vehicle   总被引：1，自引：1，他引：0  

李晔  庞永杰  万磊  王芳  廖煜雷 《中国海洋工程》2009,23(2):345-354

The stability of the motion control system is one of the decisive factors of the control quality for Autonomous Underwater Vehicle (AUV).The divergence of control,which the unstable system may be brought about,is fatal to the operation of AUV.The stability analysis of the PD and S-surface speed controllers based on the Lyapunov' s direct method is proposed in this paper.After decoupling the six degree-of-freedom (DOF) motions of the AUV,the axial dynamic behavior is discussed and the condition is deduced,in which the parameters selection within stability domain can guarantee the system asymptotically stable.The experimental results in a tank and on the sea have successfully verified the algorithm reliability,which can be served as a good reference for analyzing other AUV nonlinear control systems.  相似文献   

An Efficient Model for Transient Surface Waves in Both Finite and Infinite Water Depths     

宁德志  滕斌  臧军  柳淑学 《中国海洋工程》2009,23(3):459-472

A numerical model is developed to simulate fully nonlinear extreme waves in finite and infinite water-depth wave tanks. A semi-mixed Eulerian-Lagrangian formulation is adopted and a higher-order boundary element method in conjunction with an image Green function is used for the fluid domain. The boundary values on the free surface are updated at each time step by a fourth-order Runga-Kutta time-marching scheme at each time step. Input wave characteristics are specified at the upstream boundary by an appropr...  相似文献   

小像幅航空影像纠正技术研究     

左志权  曹辉  段延松 《测绘通报》2009,(3)

以纠正为主题,通过大量试验数据及适当的理论推导,说明光学畸变羞纠正及系统误差补偿在小像幅数码影像处理中的必要性及重要性.从试验结果看,本义所提出的观点是正确的.  相似文献   

地理信息公共服务的若干思考   总被引：4，自引：2，他引：2  

徐敬仙  段志强 《地理空间信息》2009,7(5):65-68

在总结几位专家观点的基础上,结合作者的工作体会,对地理信息公共服务的本质、现有基础、总体架构、应用模式、平台解决方案等多个方面进行了探讨,并提出了地理信息公共服务需要信息化测绘、指引地理信息产业化的观点。  相似文献   

我国海岸工程技术展望   总被引：1，自引：0，他引：1  

左其华  窦希萍  段子冰 《海洋工程》2015,33(1):1-13

从海岸动力监测体系、河口海岸侵蚀及防护、海岸工程深水和离岸趋势、极端条件下海岸工程结构安全、岛礁工程开发技术、海岸管理与数字海岸、亲水工程、海洋能技术利用开发和海岸工程研究等九个方面对我国海岸工程中面临的问题,以及国外相关工程技术进展情况进行了分析,并指出我国未来海岸工程领域需要加以关注的重点问题和发展趋势。  相似文献   

苏北朱家墩气田成藏特征对南黄海南部盆地勘探的意义     

赵永强  段铁军  袁东风  刘运黎  罗锋 《海洋地质与第四纪地质》2007,27(4):91-96

南黄海南部盆地是下扬子地台沿北东方向向海域的自然延伸,盆地的区域构造及油气地质特征与陆上苏北盆地相似。苏北盆地朱家墩气田的成功开发为南黄海南部盆地的勘探提供了借鉴,在分析朱家墩气田成藏特征的基础上,将南黄海南部盆地的成藏条件与朱家墩气田成藏条件进行对比,发现两者具有很强的可比性,得出南黄海南部盆地具有良好的勘探前景,其勘探方向为寻找"古生新储"的气藏,其发育部位为邻近大断裂一侧的深凹带。  相似文献