基于深度神经网络的交通出行方式选择模型

由于自身的局限性,传统的交通出行方式选择模型不能很好地发挥大数据的作用,而深度学习在大数据分析领域具有广阔的应用前景.建立基于深度神经网络的出行方式选择预测模型,运用随机梯度下降算法、丢弃法等解决层数加深后导致的过拟合问题;利用广州市居民出行调查数据对模型进行训练和测试.结果表明,该模型具有较高的测试精度和泛化能力.     

基于隐马尔可夫模型的公交乘客出行链识别方法

以公交IC卡数据为基础,结合公交站点周边土地类型及乘客时空转移序列构建隐马尔可夫模型对乘客的出行目的进行识别,继而实现完整乘客公交出行链的提取。采用石家庄某一工作日的公交IC卡数据来实现模型,并与同日期的公交乘客出行调查数据对比,结果表明模型与实际调查结果较为吻合,工作日公交乘客出行链以通勤类出行链为主,总占比达81.87%,通勤活动具有很强的时效性。本文模型为公交IC卡数据的深度研究提供了一定的基础。     

城市企事业人群出行链提取及出行特征分析

居民出行特征分析是研究交通需求和探寻交通拥堵症结的基础手段。为研究居民出行特征,本文基于企事业单位人群出行特征调研数据,改进经典DBSCAN聚类算法,识别出居民出行停留点,进而结合关联规则提取出居民出行轨迹数据；根据出行轨迹数据的时空特征,分别从时空角度和功能区划分角度,挖掘出企事业人群出行时空分布规律,以及不同功能区企事业人群的出行特征。最后,以北京市亦庄区为例进行分析,得到以下结果：居民出行群体以中低收入的中青年通勤族为主,出行潮汐现象明显,工作日居民出行起讫点分布有明显规律,而休息日居民出行时间灵活,出行起终点分布较分散；商务区、居住区内居民出行量较大,起终点时间分布主要集中在早晚高峰时期,而混合区居民出行起终点分布呈现双高峰规律,休闲区居民出行规律不显著。     

居民非工作活动和出行的结构方程建模

非工作出行在城市居民出行结构中所占比重呈现不断上升趋势.结合上海市居民出行调查数据,采用结构方程模型(SEM),对社区居民非工作活动和出行的作用机制进行建模分析.研究结果表明个人特征、家庭特征和社区特征都能对居民非工作活动和出行产生影响,但社区特征具有较强作用,而出行者个人属性和家庭属性的影响强度相对要小.个人特征中就业情况对居民非工作活动和出行影响显著,家庭特征中小汽车数量有较强的影响效应,社区特征中社区公共设施覆盖率影响最为显著.     

城市通勤出行链模式选择行为研究

通勤出行是城市居民最基本和最重要的出行,对其进行研究是进行交通规划、设计与管理的一项不可缺少的基础工作,因此本文开展了基于2008年东莞城市居民出行调查数据和多项Logistic模型建立居民通勤出行链模式选择模型的研究工作。本文中的通勤出行链模式选择模型将通勤出行链模式细分为五类（HWH、HWHWH、HWH＋、HWHWH＋、HW＋WH）,并考虑了出行方式对出行链模式的影响作用。通过对模型结果的分析,总结了通勤出行链模式的显著影响因素以及通勤出行链模式选择中的特征。研究内容对于建立基于活动的交通需求预测模型、制定交通管理政策具有重要借鉴作用。     

基于手机信令数据的居民出行调查扩样模型

系统分析了居民出行调查的误差成因,简要介绍了传统加权扩样模型并分析了其局限性,特别是对沉默出行需求揭示不足的缺点。结合手机信令数据用于出行行为研究的优势及特点,提出了利用手机信令数据进行居民出行调查扩样及对挖掘沉默出行需求的方法。设计了包含5个主要步骤的居民出行调查样本数据、交通运行监测数据和手机信令数据相结合的扩样模型结构。以驻点分类技术为基础,建立了基于手机信令数据的出行活动分布模型。在获取长周期手机信令数据推断人口职住分布的基础上,基于居民出行调查RP(revealed preference)数据对交通方式划分模型参数进行了标定。从出行目的组成、时间分布和出行距离分布3个方面,对比分析了调查样本、传统加权扩样模型和新模型的计算结果的差异,结果表明新模型在揭示因瞒报、漏报而产生的沉默出行需求方面作用显著。     

基于GPS数据的交通出行模式及转换点识别算法

GPS产生的大量数据携带了许多潜在信息。针对一段连续的GPS轨迹数据进行研究,识别GPS轨迹中的出行模式转换点;以出行模式转换点为分割点,将连续的GPS轨迹分割成多个GPS轨迹段;利用训练好的随机森林模型识别出不同GPS轨迹段的出行模式(包括步行、骑行、公交、地铁、汽车等类型),从而得到一段GPS轨迹的完整的出行模式描述。相比以前的研究,区别在于:提出一种基于低速度移动研判的出行模式转换点识别方法;新增加了"稳定速度"和"平均停留间隔"两种区别性特征,对已有基于随机森林的出行模式判定算法进行了改进。实验结果表明:改进之后的出行模式判定算法平均准确率提高了1.3%;同时,出行模式转换点识别方法大幅降低了算法的时间复杂度,使得GPS轨迹数据出行模式研判算法的F-score值提高了4%左右。     

基于信令数据的中等城市绿色出行政策建议

该文提出了一种基于信令数据识别交通方式并制定出行政策的方法，旨在促进中等城市的绿色、可持续发展。首先，针对中等城市信令数据的特点，结合基站定位原则和信息报送机制等因素，确定出行速度区间；然后，使用地图API(application programming interface)获取交通方式的速度，并通过调整速度区间和基于出行时间可靠度感知的Logit模型，完成交通方式的识别；最后，选取荆州市中心城区作为研究实例，对空气污染物排放量等数据进行验证。综合考虑扩展时空信息、路网交通状态和出行策略等方面，该文提出的方法能够有效地完成交通方式识别。此外，根据污染物排放可视化和居民出行情况，讨论了出行政策。研究结果表明：需加强学区和医院区的交通组织管理，以减少机动车在低速行驶阶段的污染物排放；在高峰时段，传统公交吸引力不足，应开设需求响应式公交；另外，可采用硬件与管理相结合的方式，鼓励特定人群使用非机动车。     

基于智慧出行用户画像的出行期望预留时长分析

可靠的交通出行信息服务是优质出行体验的基本保障,为了探究不同属性出行者、不同出行活动需求条件下的合理预留时长,通过SP调查实验获取出行者在各类典型出行活动场景下的期望预留时长,采用卡方检验与非参数秩和检验验证出行者的个人属性与出行活动类型对期望预留时长的差异性影响。研究发现：(1)受出行活动的价值或惩罚影响,不同类型出行活动的提前到达需求程度以及与之对应的期望预留时长存在显著差异,出行活动价值或惩罚越高,出行者期望预留时长越长;(2)相同类型出行活动需求下,出行者的个人属性亦会显著影响期望预留时长,不同类型出行活动需求下,影响出行者期望预留时长需求的属性类别存在差异,同一类型出行活动需求下,出行者属性的不同分类水平影响出行者期望预留时长需求,其差异程度可高达32分钟(103%)。研究结论对于开展精准出行用户的信息服务具有重要意义。     

基于自动检票系统数据挖掘的地铁刚性出行起讫点识别方法

刚性用户是地铁用户群的主要构成部分。对刚性出行起讫点的识别有助于深入了解该类型用户的出行特点,为地铁精细化管理和运营提供数据基础。针对现有起讫点挖掘方法指标较笼统、无法针对个体用户出行特征等问题,提出基于自动检票系统(automatic fare collection,AFC)数据挖掘的地铁刚性出行起讫点识别方法。首先,在分析AFC数据特点的基础上,以用户站点序列为媒介,通过用户出行的时空规律识别地铁刚性用户;其次结合刚性用户出行特点,提取刚性出行起讫点属性;最后以北京地铁为例,验证该算法的准确性,探讨北京地铁刚性需求分布。研究结果表明:该算法识别率可达到93. 5%,满足地铁运营和规划的数据要求;北京地铁刚性出行起讫点分布与现状用地属性及客流集散情况相吻合,间接证明了该算法的可靠性。     

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.     

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.     

A computer generator for randomly layered structures

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

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。     

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     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.