基于结构方程的城市低收入通勤者活动-出行行为模型

为了分析影响低收入通勤者活动-出行的因素,揭示活动与出行之间的互动机理,基于南京市居民一日出行调查数据,采用结构方程模型建立低收入通勤者活动-出行模型.统计数据表明,低收入通勤者较多进行生存型活动,较少参与维持型活动和休闲型活动,出行链以简单工作链为主,电动车是其主要出行方式.模型标定结果显示,个人及家庭社会经济属性、可达性对低收入通勤者的活动参与、出行生成和方式选择有显著影响,并且活动-出行模式变量间也存在较强的相互关系.社会经济属性、可达性主要通过活动参与间接影响出行生成,而方式选择主要受社会经济属性和出行生成的直接影响.     

南北方老年人出行链选择行为对比

为研究中国南北方老年人出行行为之间的差异,以老年人出行链为研究对象,将老年人出行链分为简单出行链和复杂出行链两种基本形式.基于北方城市东营市2011年的居民出行调查数据和南方城市恩平市2013年的居民出行调查数据,运用二项Logit模型对南北方老年人出行链选择行为进行建模分析,同时考虑个人属性、家庭属性以及出行链属性对老年人出行链选择的影响.模型分析结果表明,个人属性均对南北方老年人出行链选择影响不显著,出行链的出行时间对老年人选择简单出行链产生负影响,家庭月收入、家庭是否拥有小汽车对老年人复杂出行链选择产生负影响,家庭是否拥有自行车对北方老年人简单出行链选择产生正影响.     

基于结构方程模型的不同规模城市居民出行方式选择影响因素的关联性分析

针对目前城市居民出行方式选择的相关研究主要集中在个人属性对交通方式选择的影响方面,忽略了不同城市建成环境与出行方式的关联性分析问题。选取个人属性、交通供给属性和城市规模为外因变量,同时选取出行目的、出行时间、出行偏好、出行距离和出行方式选择为内因变量,采用结构方程模型(SEM)建立各影响因素与城市居民出行方式选择的关系结构;以3个不同规模的城市为研究对象,利用其居民出行调查数据对构建的SEM进行辨识与修正,采用卡方自由度比、适配度、调整适配度和均方残差4个指标对构建的SEM进行拟合优度检验,从而得到各因素对居民出行方式选择的正负影响及程度。结果表明:4个评价指标的结果均符合适配标准或临界值要求,表明构建的SEM较好;性别、职业和收入水平3个外因观察变量对"个人属性"具有显著的正影响;目的地是否有停车场对交通供给属性具有显著的正影响,目的地停车设施越完善、停车供给越充足,城市居民选择小汽车出行的比例越大;大城市和中等城市对城市规模有显著的正影响,大城市和中等城市的居民更偏爱公交车出行;个人属性、交通供给属性和城市规模3个外因潜在变量对出行方式有显著的正影响;出行偏好对出行方式有显著的正影响。研究结果对进一步优化居民出行方式结构、改善城市交通拥堵具有指导意义。     

城市居民出行碳排放研究进展

在应对全球气候变化和解决城市交通问题中,居民出行碳排放逐渐成为科学研究的重要课题.文章从居民出行碳排放的核算、影响因素和模拟三方面系统归纳了居民出行碳排放的研究内容及相关研究方法.可以认为:使用自下而上方法核算居民出行直接碳排放能明晰社区-家庭层级上居民出行碳排放的变化特征,由于数据获取困难,使用复杂方法核算居民出行间接碳排放的可操作性差;区域-城市环境特征和社区-家庭因素共同作用影响居民出行碳排放的变化,单方面分析居民出行碳排放的影响因素会出现研究结果的偏差,将二者结合使用复杂的数理统计方法量化各因子是揭示居民出行碳排放驱动机制的关键;基于时间地理学理论和GIS空间技术模拟居民出行时空轨迹可以较为直观地分析居民出行碳排放的时空特征,且为居民出行碳排放驱动机制分析提供支持.虽然考虑城市形态、土地利用、交通系统和居民个体行为的综合模型的时间和空间精度较低,却是未来模拟和调控居民出行碳排放的有效途径.     

历史城区居民出行活动模式选择影响因素分析

探讨了历史城区内居民出行活动模式选择的影响因素,依据扬州市历史城区居民调查数据,将居民出行活动划分为家-工作/学习(内)-家、家-工作/学习(内)-其他-家、家-工作/学习(外)-家、家-工作/学习(外)-其他-家和家-其他-家5种典型模式.采用多项Logit模型分析了5种活动模式的选择与居民个体及家庭属性之间的关系,并探索了不同活动模式下的出行方式选择情况.结果表明,个体出行者的性别、年龄、职业、有无小汽车和家庭电动自行车数量显著影响着出行活动模式的选择,而家庭人口数、有无学龄前儿童、家庭自行车数、有无摩托车及家庭收入对于历史城区居民出行活动模式选择的影响并不显著.     

通勤出行时间与方式选择

针对不同方式通勤出行者在出行时间上的差异性,从通勤出行方式对通勤出行时间的影响出发,将通勤出行方式选择和出行时间选择纳入同一模型系统,建立由离散选择模型和线性回归模型组成的离散 连续模型,对通勤出行方式和出行时间选择及其相互影响模式进行了深入分析.研究表明,通勤出行方式对出行时间选择有显著影响,通勤者年龄、性别及其家庭成员结构、工作活动属性及通勤途中的非工作活动安排等都是出行方式和出行时间选择的重要影响因素.本研究对准确预测通勤出行选择行为及其对交通管理工作的影响有重要意义.     

历史城区典型通勤者活动与出行的结构方程建模

以历史城区为研究对象,结合扬州市通勤者出行调查数据,采用结构方程模型(SEM),对通勤者活动和出行相关特征进行建模分析。按照居住地和工作地所处区域的差异,将通勤者分为3类,以通勤者的个体特征和家庭特征作为外生变量,以活动强度和出行特征作为内生变量,分别对3类通勤者的结构方程模型进行了参数估计,并对估计结果进行了灵敏度分析。研究结果表明:通勤者职住分布特征的差异导致了活动特征的差异,进一步造成出行特征的差异;居住地和工作地所在区位的差异,对通勤者活动特征和出行特征具有较强的影响作用,而出行者个体和家庭属性的影响相对要小很多;历史城区由于功能的混合性和公共服务相对完善,其活动特征和出行特征相对其他区域复杂和多样,对区外居住者也有较大的吸引力。研究对完善历史城区交通政策制定具有很好的指导意义。     

考虑居民出行OD或居住地的出行方式选择巢式Logit模型

为定量化分析居民出行OD或居住地引入轨道交通后对出行方式选择的影响,在综合考虑出行者家庭特征、个人属性和出行特性的基础上,结合南京市居民出行调查数据,分别建立了考虑居民出行OD、考虑居住地、既不考虑出行OD也不考虑居住地的3个出行方式选择巢式Logit模型,并对比了模型的拟合度.结果表明:考虑居民出行OD的巢式Logit模型具有最高的拟合度;相比于出行OD小区或居住地远离轨道交通站点的出行者,出行OD小区或居住地接近轨道交通站点的居民更倾向使用慢行交通和/或公共交通出行方式.得到的分析结果为城市规划者认识轨道交通在吸引居民出行由小汽车向公共交通转移中的作用提供了理论支持和决策依据.     

南京城市内部迁居特征及未来住宅区开发的方向

随着城市规模的扩大,工作地与居住地在空间上逐步分离,居民的生活方式日趋多样化和个性化,居住选择的自由度增大,移动性和出行需求不断提高,个人偏好和主观能动性在居民活动行为中的作用不断加强.因此,解释城市活动空间的视角有必要拓展到经济、社会及文化这一更广的层面上来.本文以南京城市居民问卷调查为基础,通过对居民个人情况、家庭属性特征、迁居时空过程和迁居原因的分析,评价南京城市住宅区开发现状,提出未来开发方向,以供相关部门在进行城市居住空间决策时参考.     

节假日停车选择行为分析

根据居民的社会经济属性和出行特征,研究节假日停车选择的影响因素.以2013年清明节期间香山地区的居民出行调查和停车调查为基础,利用节假日交通特征,挖掘峰值出行需求条件下居民的活动特征和出行规律,并对居民出行和停车选择进行数据分析,建立节假日停车选择结构方程模型,探究节假日停车问题的诱因.研究表明,到达时间和逗留时间是影响停车选择的主要因素.同时,出行者对道路环境越熟悉,对停车情况越了解,出行方式越复杂,停车选择行为越多样.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

<正>~~     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to