基于CNN和RNN的自由文本击键模式持续身份认证

个人击键节奏模式具有很难被模仿的特点并可以用于身份认证。根据个人自由文本输入时的击键数据可以学习到个人独有的击键模式。基于对用户自由文本击键输入的检测,能够在不影响用户输入的情况下完成对用户身份的持续认证。该文提出将整体击键数据划分成固定长度的击键序列,并且根据击键的时间特征将击键序列中的击键时间数据转化成击键向量。使用卷积神经网络(convolutional neural networks,CNN)加循环神经网络(recurrent neural networks,RNN)的模型进行个人击键向量序列进行学习,用于身份认证。结果表明:模型使用公开数据集进行实验获得最优拒真率(false rejection rate,FRR)为1.95%,容假率(false acceptance rate,FAR)为4.12%,相等错误率(equal error rate,EER)为3.04%。     

基于Levenberg-Marquardt算法的用户鉴别

为了维护计算机系统的安全,一般通过设置用户口令以便进行身份鉴别,防止他人冒名顶替.口令鉴别的主要弱点在于,一旦被窃,冒名顶替者就可以轻而易举地进入用户的私人账户进行非法活动.击键动力学的研究是给口令加上一个简便而有效的保护措施.击键动力学方法通过获取并分析用户敲击键盘的特征数据,自动地识别出用户的真实身份.这一辅助身份鉴别的关键问题主要是寻找准确率高、执行速度快的识别算法.本论文采用Levenberg-Marquardt(LM)算法对上述存在的问题进行了研究.     

基于语义行为和社交关联的好友推荐模型

现今社交媒体是建立社交联系的重要媒介,好友推荐对于扩展人们的关系网络起到至关重要的作用,准确的用户特征提取和分析是社交网络中好友推荐的关键.传统的好友推荐方法一般都是根据部分用户属性信息或行为信息进行推荐,所以对用户特征的描述不完整,推荐的效率和准确率远非预期.提出基于用户语义行为和社交关联的推荐模型应用于社交媒体平台上的好友推荐.为了获得准确的预测,使用LDA(Latent Dirichlet Allocation)对语义信息进行主题建模,得到基于主题的用户语义行为特征表达;使用DeepWalk算法对用户社交关联网络图进行特征提取,得到准确的社交关联特征表达;使用反向传播神经网络来预测用户潜在的社交关联,为用户精准推荐好友.该模型实现了利用用户语义行为和社交关联预测用户潜在的社交关联,可以根据潜在社交关联进行精准的好友推荐.     

基于用户行为影响的微博突发话题检测方法

考虑到微博数据存在时序性特征以及包含用户的社交网络行为特征,提出一种动量信号增强模型算法来有效地检测微博突发话题.由于传统模型未考虑微博数据变化以及用户社交行为的影响,为此首次提出影响力因子以及热度因子,用以修正动量模型.为获取影响力因子,将计算出当前时点前给定周期内的数据对当前数据的变化差值的指数累计影响作为影响力的衡量标准,以体现词频在该区间段的重要性.影响力因子将用于修正词频序列,以获取MACD值指标.由于用户的社交行为对话题产生影响巨大,进而提出热度因子用以修正MACD值指标.当模型满足指标阈值时,特征词则列为突发特征词.最后,通过K-means聚类算法将特征词进行归类合并,以获取突发话题.实验结果表明,模型精度能达到81.82%,表现良好.     

社交网络中水军用户团队不当行为准确识别技术

传统方法通过提取用户的静态行为特征,利用监督学习模型完成识别,在社交网络规模大的状态下,水军用户团队不当行为特征和正常用户越来越相似,无法准确识别社交网络中水军用户团队的不当行为。为了解决该问题,依据用户动态行为特征研究社交网络中水军用户团队不当行为准确识别技术。对社交网络进行描述,在此基础上,提取用户行为动态特征。把社交网络中水军用户团队不当行为识别问题看作二分类问题,将提取动态特征相应的样本作为输入,构建决策树,通过决策树对新的社交网络数据集进行水军用户团队不当行为识别。结果发现：采用的动态特征可有效反映水军团队不当用户行为特征;所提技术对水军用户团队不当行为的识别结果和人工标识结果基本一致;所提技术在三个数据集上的调和平均值和平衡准确度较其它技术高。可见所提技术识别准确性高。     

基于深度学习建模多行为动态演化的转化率预估

针对基于用户行为特征的转化率预估在计算广告领域的应用中尚未充分提取和利用用户多种行为模式的动态演化特性等问题,考虑用户兴趣模型和行为模型的动态演化性,提出一种融合注意力机制的深度学习策略,获取用户行为动态演化特征,进而构建基于用户行为特征的转化率预估模型.首先,构建基于门控循环单元(gated recurrent unit, GRU)和注意力机制的用户单个行为序列模型,将提取出的用户行为嵌入表示作为用户行为的动态变化特征;然后,利用自注意力对用户的多行为动态演化进行建模;最后,融合所提取的用户多行为序列向量作为用户的行为特征,构建移动APP广告转化率预估模型.实验结果表明所提取的用户行为序列特征可有效改善转化率预估效果.     

基于BP神经网络的信誉欺骗检测模型

在分析信誉系统评价的目标系统的行为特征的基础上,提出了一种集成的BP神经网络模型.该模型使用训练集对构造好的BP神经网络进行训练,将测试集输入到训练好的BP神经网络中,进行欺骗检测,并在行为维度上进行欺骗检测效果验证.实验结果验证了基于BP神经网络的信誉欺骗检测模型的可行性.基于BP神经网络的欺骗检测模型能够快速、准确地实现欺骗行为的检测.     

社交网络用户隐私量化建模与实证

在线社交网络的飞速发展对社交网络用户的隐私保护提出了新的挑战.通过使用社会网络分析、决策分析理论和实证研究的方法,建立了一种用户隐私向量模型,从而实现对社交网络中用户隐私保护状况的量化分析.并在此基础上以新浪微博为研究对象,通过微博用户的真实数据进行实证分析.研究结果表明:用户隐私量值对用户的行为有重要影响,真实社交网络中大部分用户的隐私关注程度较低,高隐私关注群体和低隐私关注群体的比例较小,用户的私信和地理位置信息的分享行为受用户的隐私关注情况影响大.研究结果对社交网络用户的隐私保护、社交网络中用户行为规律的研究具有参考意义.     

LTE网络用户行为分析系统的设计与实现

针对传统信令监测系统数据业务识别度低、统计能力不强等问题,在传统的监测系统基础上,提出了一种采用网络爬虫(web crawler)技术和深度包检测(deep packet inspection,DPI)技术的LTE网络用户行为分析系统.该系统对应用层业务内容进行精细化识别,进一步分析了移动互联网的用户行为特征.经现网测试验证,设计的用户行为分析系统达到了预期的效果,对移动互联网用户行为分析、精准化营销领域具有推广意义.     

在线社交网络用户分析研究综述

在对国内外在线社交网络用户分析相关研究归纳总结的基础上,综述了在线社交网络用户分析的最新进展,主要包括通过用户影响力和用户偏好进行用户行为分析、采用隐式和显式的分类方法对用户属性预测算法进行综述,简述了基于用户属性特征或(和)用户关系拓扑结构的用户分类研究进展,并分析了动态社交网络、并行算法及社交用户语义信息给在线社交网络用户分析所带来的机遇和挑战,对该研究方向上的发展趋势进行了展望.     

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.