基于主成分分析和优化聚类算法的行驶工况研究

针对模糊C均值聚类算法容易陷入局部最优以及传统的主成分分析法没有完全体现出用数量较少的综合指标来代替多个指标的问题,提出了一种改进的主成分分析和利用遗传模拟退火算法优化后的模糊C均值聚类算法相结合的聚类算法(GSA-FCM),从而构建汽车行驶工况图:首先,利用改进的主成分分析法对特征参数矩阵进行处理;然后,采用GSA-FCM聚类算法对运动学片段进行聚类;最后,选择合适的片段合成最终工况图. 并且,对GSA-FCM聚类、传统的K均值聚类的合成工况与实际工况中的特征参数进行有效性验证,与NEDC标准测试工况进行比对. 实验结果表明:GSA-FCM聚类合成工况与实际工况的特征参数的平均相对误差为6.46%,说明GSA-FCM聚类算法的聚类效果明显、误差小,所合成的行驶工况可以代表该城市的汽车行驶状况.     

组合优化聚类与马尔科夫链的城市环卫车辆行驶工况构建方法

为客观描述城市环卫车的实际行驶特征,基于3辆市政环卫车连续一周实际道路行驶数据,提出一种组合优化聚类与马尔科夫链的城市环卫车辆行驶工况构建方法. 首先对特征参数矩阵做均值化处理,增强参数降维后每一个主成分中所包含的特征参数信息;其次利用k均值聚类将不同运行特征的运动学片段划分到不同类的样本集内,以马尔科夫链法在每一类样本集中做状态预测,按时间比例合成代表工况. 最后,基于运动学参数对所构建的代表工况进行有效性检验. 结果表明,所构建的福州市环卫车辆行驶工况相较于C-WTVC国家标准工况,能更客观地反映福州市环卫车辆的实际运行情况.     

基于数据的K均值理论及其应用

首先使用主成分分析方法对车辆行驶工况的特征参数进行处理,然后利用K-均值聚类原理对所有具有代表性的运动学片段进行聚类分析,由此得出汽车行驶工况的数学原理.为汽车节能减排的发展和建立能够正确反映我国道路工况特征的行驶工况提供理论依据.     

基于主成分和聚类分析的汽车行驶工况构建

基于城市汽车实际道路行驶采集的数据,运用主成分和K-means聚类分析,对汽车行驶工况进行构建并分析误差.首先,对5种类型的原始数据,依次进行时间不连续数据、尖点数据、毛刺噪声数据以及怠速异常数据等预处理;其次基于预处理后的数据,对运动学片段进行划分,同时引入14个相关的运动特征指标,采用主成分分析进行降维处理并选取了具有代表性的5个主成分,基于K-means聚类分析算法将其运动学片段按照拥堵路况、一般拥堵路况和通畅路况分为3类,再根据聚类结果选取最优工况片段,从而得到最终的工况曲线.最后,对汽车行驶工况与所采集数据源的各运动特征值进行误差分析,验证了所构建的汽车行驶工况的合理性.     

基于GPRS的电动汽车道路行驶工况自学习

提出了一种基于GPRS的道路行驶工况数据的远程采集方法,并将其应用在电动汽车的实际运行中,获得电动汽车道路试验原始数据库.同时将自组织映射(SOM)神经网络引入到行驶工况的自学习中,通过SOM网络对原始数据进行运动学片段的聚类分析,构建出了电动汽车在实际运行中的3种典型工况,为电动汽车基于行驶工况的自适应优化控制策略提供了基础环节.所构建的行驶工况和其他行驶工况相比具有一般规律,表明应用SOM网络能够很好地实现道路行驶工况的自学习功能.     

基于LLEKM和马尔科夫链的城市轻型车行驶工况构建

为客观描述机动车在道路上的运行特征,针对传统城市道路标准行驶工况构建方法的弊端,提出一种基于局部线性嵌入与K均值聚类(LLEKM)和马尔科夫链的汽车工况构建方法,并对该方法的应用准确性进行研究。首先,结合道路交通条件对实测样本数据进行除噪平滑处理,根据运动学片段定义将其划分为1 754个运动学片段,并选取16个运动学参数构建特征参数矩阵。其次,利用局部线性嵌入算法降维约简特征参数矩阵,解决了由数据压缩重构导致的线性结构丢失的问题;通过K均值聚类分析,计算不同类型数据集中各行驶状态时间占比的差异性,得到相应类型下城市道路汽车的行驶特点。然后,以每类中各相邻行驶状态的统计量确定状态转移概率矩阵,采用马尔科夫链方法从每类中选取特征参数误差最小的运动学片段,按照时间比例合成代表工况。最后,以厦门市3个月内同一辆轻型汽车的行驶数据为例展开实证分析,验证所提方法的准确性。研究结果表明:与样本数据和传统方法构建的工况相比,所提方法构建的轻型车行驶工况主要特征参数与样本数据吻合度更好,平均相对误差从9.69%降低到4.47%;提出方法的速度-加速度联合概率分布误差明显降低,行驶工况构建精度得到了提高;对比分析现行方法构建的标准工况,该方法能更加真实地反映厦门市轻型车的实际运行状况。     

佛山市机动车交通特征研究

采用GPS车载测试系统和视频采集技术对佛山市城区和郊区的交通流量与行驶工况进行了测试.基于测试数据,对佛山市的交通特征、城区不同道路类型的机动车行驶特征进行了深入分析,采用特征参数法合成佛山市城区和郊区高速的行驶工况,并与欧洲标准工况进行了对比.结果表明:佛山市城区主干路、次干路和居民路平均每小时的车流量分别为3 667辆、2 418辆和822辆;郊区高速、国道和省道平均每小时的车流量分别为1 192辆3、024辆和1 583辆.城区机动车平均速度为20.54 km/h.佛山实际工况平均速度、加\减速度与NEDC相差17.26%~55.91%.     

基于主成分分析和两阶段聚类分析的汽车行驶工况评价模型

为了准确评价汽车行驶工况,促进汽车节能减排.本文在修正异常数据的基础上,提取了1743条运动学片段,并构建了一种包括平均速度、发动机转速比和扭矩百分比等18个特征参数的汽车运动特征评价体系.利用基于主成分分析和两阶段聚类分析的汽车行驶工况评价模型,将运动学片段的样本数据聚为低速工况、中速工况和高速工况3类.聚类结果的准...     

多源信息融合的插电式混合动力公交车行驶工况构建

为了反映插电式混合动力公交车(PHEB)在实际公交工况运行时的真实油耗,提出了一种基于实时交通信息的工况构建方法。首先,通过车载传感器获取实时交通信息,利用D-S证据理论对获取的多种传感器信息进行多源信息融合。其次,根据实车采集的原始行驶数据,对车速片段进行划分。利用马尔可夫转移矩阵,结合蒙特卡洛方法构建了全局行驶工况。通过实时更新的交通信息对构建的全局行驶工况进行实时更新,从而进一步反映实时的道路行驶路况。最后,通过与实际工况数据的比较,验证所提出方法的有效性。研究结果表明:基于实时交通信息构建的行驶工况与实际工况较为吻合,主要特征参数的相对误差均在5%以内,百公里油耗与实际工况的百公里油耗相对误差为1.8%。     

改进模糊C均值聚类法的车辆实际行驶工况构建

针对模糊C均值(FCM)聚类法的性能依赖于初始聚类中心、迭代容易陷入局部极值、不能确保FCM收敛于一个最优解的问题,利用多岛遗传算法(MIGA)与序列二次规划法(SQP)组合优化,对FCM聚类的初始聚类中心进行优化,从而使聚类结果更加接近最优聚类。采用主成分分析和改进的FCM聚类分析,将运动学片段的特征值进行降维和分类处理,构建出基于大样本、符合郑州市交通特征的行驶工况。与试验数据对比表明:所构建的乘用车行驶工况与试验数据特征参数平均相对误差仅为2.097%,速度-加速度联合分布差异(SAFD_(diff))仅为1.74%,行驶工况拟合精度较高,更能综合反映郑州市交通真实状况。     

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…     

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).     

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.     

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.