Nodes and Field of Tourist Origins to Ancient Village——A Case Study of Huangcheng Village in Shanxi Province of China

Based on Hagget's theory of spatial structure,researches on the nodes and field of tourist origins to Huang-cheng Village in Shanxi Province of China have been explored.Nodal hierarchy structure of tourist origins is analyzed with cluster analysis and the gravity model.And field of tourist origins is analyzed with attraction radius index(R)and geography concentration index(G).In the field analysis,R and G of Huangcheng Village are compared with Xidi Village that is a world heritage located in Huangshan City of Anhui Province in China.According to comparison of loca-tions of two areas,influential factors for field area of Huangcheng Village are identified.It is concluded that:1)cluster analysis and gravity model can be complementary methods to each other for nodal hierarchy structure analysis of tour-ist origins;and 2)as far as location is concerned,the weak intensity effect of tourism resources in the tourist region is a major cause for explaining why tourist origins to Huangcheng Village are mainly its neighboring areas.Moreover,it is suggested that the regional effect of tourist resources should be regarded as a component of destination attractiveness when applying gravity model.     

论四川盆地丘陵区防护林体系的建设

四川盆地丘陵区,人多地少,资源贫乏,经济不发达,生态环境质量低劣,因而建设具有生态效益、经济效益和社会效益的防护林体系很有必要。建设本区防护林体系的原则应是:共生,布局与结构合理,土地资源充分利用和总体最优。经采取切实有效的措施后,最终建成一个良性农田生态防护林网络体系,以协调当地人口、资源、经济和环境之间的关系,并使其日臻完善。     

一致性哈希算法在数据库集群上的拓展应用

在数据库集群的研究中,可扩展性是一个重要的性能指标。为实现在数据高速增长或部分集群服务器故障情况下,数据依然能够快速、可靠、安全的分布到新的集群服务器节点上的目的,就必须合理设置数据划分的策略。将Key-Value存储技术中使用的一致性哈希算法思想借鉴运用到并行分析型数据库集群中,提出针对大规模结构化类特殊数据的一致性哈希划分方法,并在MapReduce框架下设计具体的数据划分方案。最后,以TPC-DS作为测试基准,与同类系统进行性能对比测试,实验结果表明方案不仅有良好的划分性能,且扩展性也较好。     

一致性哈希算法在数据库集群上的拓展应用

在数据库集群的研究中,可扩展性是一个重要的性能指标.为实现在数据高速增长或部分集群服务器故障情况下,数据依然能够快速、可靠、安全的分布到新的集群服务器节点上的目的,就必须合理设置数据划分的策略.将Key-Value存储技术中使用的一致性哈希算法思想借鉴运用到并行分析型数据库集群中,提出针对大规模结构化类特殊数据的一致性哈希划分方法,并在MapReduce框架下设计具体的数据划分方案.最后,以TPC-DS作为测试基准,与同类系统进行性能对比测试,实验结果表明方案不仅有良好的划分性能,且扩展性也较好.     

海温异常对东亚夏季风强度先兆信号的影响

利用ERA-Interim再分析资料、NOAA海温资料、CMAP格点降水资料和中国气象站降水资料,通过合成、相关和回归分析等方法研究了1979—2012年东亚夏季风强度与其先兆信号的关系,并分析了热带海温异常的可能影响。研究表明:东亚夏季风先兆指数反映了2月200 hPa纬向风距平的主要模态特征 (EOF1),前冬热带中东太平洋海温偏低 (高),2月亚洲地区西风急流位置偏北 (偏南),东亚夏季风先兆指数偏强 (弱)。前期热带海温异常对东亚夏季风强度有明显影响,前冬热带中东太平洋海温偏低 (高) 有利于东亚夏季风偏强 (弱)。2月亚洲中纬度地区纬向风异常特征在春季不能持续,先兆信号与东亚夏季风强度的联系主要源自热带海洋。     

基于GIS的广西电网流域面雨量计算方法与监测预警

以广西电网直调水电厂所处的西江流域为研究对象,基于GIS技术,在对西江流域面雨量监测区域基础信息处理基础上,采用比较分析方法,开展分流域面雨量计算方法研究,结果表明:(1)以1:5万数字高程模型为数据基础,针对西江流域河网、自动气象站、水电站等分布特点,结合水系、等高线特征,沿水系分水岭对西江流域干流进行精细化分区,为分流域面雨量计算提供基础参数;(2)对分流域面雨量采用算术平均法与泰森多边形法计算,结果为两种方法计算结果偏差较小,取算术平均法为流域分区面雨量计算方法;(3)逐小时处理、计算面雨量实时数据,实现西江流域面雨量的实时监测与预警服务。     

Symplectic adaptive algorithm for solving nonlinear two-point boundary value problems in Astrodynamics

In this paper, from a Hamiltonian point of view, the nonlinear optimal control problems are transformed into nonlinear two-point boundary value problems, and a symplectic adaptive algorithm based on the dual variational principle is proposed for solving the nonlinear two-point boundary value problem. The state and the costate variables within a time interval are approximated by using the Lagrange polynomial and the costate variables at two ends of the time interval are taken as independent variables. Then, based on the dual variational principle, the nonlinear two-point boundary value problems are replaced by a system of nonlinear equations which can preserve the symplectic structure of the nonlinear optimal control problem. Furthermore, the computational efficiency of the proposed symplectic algorithm is improved by using the adaptive multi-level iteration idea. The performance of the proposed algorithm is tested by the problems of Astrodynamics, such as the optimal orbital rendezvous problem and the optimal orbit transfer between halo orbits.     

AMR Simulations of Magnetohydrodynamic Problems by the CESE Method in Curvilinear Coordinates

The objective of this paper is to present new extensions of the space – time conservation element and solution element (CESE) method for simulations of magnetohydrodynamic (MHD) problems in general curvilinear coordinates by using an adaptive mesh refinement (AMR) grid system. By transforming the governing MHD equations from the physical space (x,y,z) to the computational space (ξ,η,ζ) while retaining the form of conservation, the CESE method is established for MHD in the curvilinear coordinates. Utilizing the parallel AMR package PARAMESH, we present the first implementation of applying the AMR CESE method for MHD (AMR-CESE-MHD) in both Cartesian and curvilinear coordinates. To show the validity and capabilities of the AMR-CESE-MHD code, a suite of numerical tests in two and three dimensions including ideal MHD and resistive MHD are carried out, with two of them in both Cartesian and curvilinear coordinates. Numerical tests show that our results are highly consistent with those obtained previously by other authors, and the results under both coordinate systems confirm each other very well.     

Modeling Research of the 27-day Forecast of 10.7 cm Solar Radio Flux (I)

Adopting the autoregressive method for time-series modeling, we have made a study on the medium-term forecast of solar 10.7 cm radio flux (F10.7). The result of forecast experiments and the error analysis indicate that when the solar activity is at a rather low level and the 27-day periodicity of F10.7 is apparent, the autoregressive forecast method has a high accuracy and relatively ideal effectiveness, but when a large active region appears or disappears on the solar dusk, the forecast effectiveness is not ideal. This means that the autoregressive method for the time-series modeling can reflect well the 27-day periodicity of F10.7, and that it has certain applicability for building a mediumterm forecast model of F10.7. By comparing the forecast results in the period from 21th September 2005 to 7th June 2007, it is demonstrated that the accuracy of the autoregressive forecast method is equivalent to that of the forecast made by the American Air Force.     

湘赣边界鹿井铀矿床流体包裹体及成矿机制

位于南岭成矿带南西部的鹿井矿床是华南热液型铀矿的典型代表.为查明其成矿流体来源、性质与演化以及成矿机制,开展了不同成矿阶段石英、萤石及方解石中流体包裹体的显微测温和不同阶段石英的氢?氧同位素分析.矿床地质特征表明成矿过程可划分为(I)粗晶石英+黄铁矿±绿泥石±绢云母、(II)沥青铀矿+硫化物+绿泥石+绢云母+暗灰色微晶...