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《Information processing & management》2020,57(5):102219
GPS-enabled devices and social media popularity have created an unprecedented opportunity for researchers to collect, explore, and analyze text data with fine-grained spatial and temporal metadata. In this sense, text, time and space are different domains with their own representation scales and methods. This poses a challenge on how to detect relevant patterns that may only arise from the combination of text with spatio-temporal elements. In particular, spatio-temporal textual data representation has relied on feature embedding techniques. This can limit a model’s expressiveness for representing certain patterns extracted from the sequence structure of textual data. To deal with the aforementioned problems, we propose an Acceptor recurrent neural network model that jointly models spatio-temporal textual data. Our goal is to focus on representing the mutual influence and relationships that can exist between written language and the time-and-place where it was produced. We represent space, time, and text as tuples, and use pairs of elements to predict a third one. This results in three predictive tasks that are trained simultaneously. We conduct experiments on two social media datasets and on a crime dataset; we use Mean Reciprocal Rank as evaluation metric. Our experiments show that our model outperforms state-of-the-art methods ranging from a 5.5% to a 24.7% improvement for location and time prediction. 相似文献
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This paper is concerned with the problem of global finite-time stabilization via output feedback for a class of switched stochastic nonlinear systems whose powers are dependent of the switching signal. The drift and diffusion terms satisfy the lower-triangular homogeneous growth condition. Based on adding a power integrator technique and the homogeneous domination idea, output-feedback controllers of all subsystems are constructed to achieve finite-time stability in probability of the closed-loop system. Distinct from the existing results on switched stochastic nonlinear systems, the delicate change of coordinates are introduced for dominating nonlinearities. Moreover, by incorporating a multiplicative design parameter into the coordinate transformations, the obtained control method can be extended to switched stochastic nonlinear systems with nonlinearities satisfying the upper-triangular homogeneous growth condition. The validity of the proposed control methods is demonstrated through two examples. 相似文献
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能源-经济-环境系统可持续发展协调状态的测度与评价 总被引：16，自引：0，他引：16
系统可持续发展的目标之一就是在各个子系统之间建立一种稳定的协调发展状态。本文分析能源-经济-环境系统间的关系，设计系统发展水平指标体系，对系统间发展的协调状态进行测度与评价。 相似文献
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《Information processing & management》2023,60(1):103109
With an increase in the number of data instances, data processing operations (e.g. clustering) requires an increasing amount of computational resources, and it is often the case that for considerably large datasets such operations cannot be executed on a single workstation. This requires the use of a server computer for carrying out the operations. However, to ensure privacy of the shared data, a privacy preserving data processing workflow involves applying an encoding transformation on the set of data points prior to applying the computation. This encoding should ideally cater to two objectives—first, it should be difficult to reconstruct the data, second, the results of the operation executed on the encoded space should be as close as possible to the results of the same operation executed on the original data. While standard encoding mechanisms, such as locality sensitive hashing, caters to the first objective, the second objective may not always be adequately satisfied.In this paper, we specifically focus on ‘clustering’ as the data processing operation. We apply a deep metric learning approach to learn a parameterized encoding transformation function with an objective to maximize the alignment of the clusters in the encoded space to those in the original data. We conduct experimentation on four standard benchmark datasets, particularly MNIST, Fashion-MNIST (each dataset contains 70K grayscale images), CIFAR-10 consisting of 60K color images and 20-Newsgroups containing 18K news articles. Our experiments demonstrate that the proposed method yields better clusters in comparison to approaches where the encoding process is agnostic of the clustering objective. 相似文献
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介绍了基于FPGA和计算机视频混合的雷达雷终端显示设计。FPGA接收雷达回波信号,并将其由极坐标系转换为直角坐标系,同时,FPGA接收计算机显卡输出的DVI信号,并在行场同步信号的控制下,实现雷达回波和显卡输出数据的混合叠加,叠加后的数据经过DVI接口芯片转后,再次形成DVI标准数据,送光栅显示器显示。该设计实现雷达的回波和人机界面的同步混合显示,满足雷达系统的显示要求。工程上也验证了该设计的有效性。 相似文献
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The consensus problem for networks of multiple agents consists in reaching an agreement between certain coordinates of interest using a distributed controller. It may be desirable that all the agents find a consensus at a given desired leader coordinate (Leader Follower Consensus Problem LFCP), or it may be only necessary that they agree at a certain coordinates value (Leaderless Consensus Problem LCP). Consensus has many practical applications in robot networks systems, where the interconnection of the agents may present variable time delays, hence rendering the stability analysis and control design more complex. Another problem that may arise is the possible lack of velocity measurements. In this work, a Proportional plus damping injection (P + d) controller together with a linear velocity observer is introduced. Our approach is able to solve both the LFCP and the LCP in networks of robots modeled as undirected weighted graphs with unknown asymmetric (bounded) variable time delays. Local (semi global) asymptotic stability is proven and simulation results are provided to test the performance of the proposed scheme. 相似文献
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以南康市龙华乡集贸商住小区修建性详细规划项目为例,研究一种控制点重新定位的方法。实验以精度较高的参照点为依据,将假定坐标系交会出的参照点转换到原坐标系,从而实现了控制点的重新定位。同时,主要通过该项目的实际情况,结合测角前方交会观测的角度,然后由新的控制点坐标计算出的参照点坐标与原始参照点坐标进行比较、分析,证明了该方法是切实可行的。 相似文献
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《Information processing & management》2002,38(1):111-140
This research is a part of ongoing study to better understand citation analysis on the Web. It builds on Kleinberg's research (J. Kleinberg, R. Kumar, P. Raghavan, P. Rajagopalan, A. Tomkins, Invited survey at the International Conference on Combinatorics and Computing, 1999) that hyperlinks between web pages constitute a web graph structure and tries to classify different web graphs in the new coordinate space: out-degree, in-degree. The out-degree coordinate is defined as the number of outgoing web pages from a given web page. The in-degree coordinate is the number of web pages that point to a given web page. In this new coordinate space a metric is built to classify how close or far are different web graphs. Kleinberg's web algorithm (J. Kleinberg, Proceedings of the ACM-SIAM Symposium on Discrete Algorithms, 1998, pp. 668–677) on discovering “hub web pages” and “authorities web pages” is applied in this new coordinate space. Some very uncommon phenomenon has been discovered and new interesting results interpreted. This study does not look at enhancing web retrieval by adding context information. It only considers web hyperlinks as a source to analyze citations on the web. The author believes that understanding the underlying web page as a graph will help design better web algorithms, enhance retrieval and web performance, and recommends using graphs as a part of visual aid for search engine designers. 相似文献
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信息化标准是解决系统集成、数据共享的基本途径。本文以煤炭企业为切入点探讨信息化标准的有效性。基于煤企在引入一系列信息系统后产生的对信息化标准的客观需求,本文将信息化标准看作一个系统,从煤企信息系统建设的5个阶段以及信息化标准系统3个阶段出发,分析了有效的煤企信息化标准应该同时具有适应性A（adaptability）、实用性F（functionality）、可实现性R（realizability）、参与性J（joint）、科学性S（scientificity）、前瞻性P（prospective）等特性,在此基础上提出了煤企信息化标准系统有效性的影响因素并给出了因素关系图和关系链图。最后,构建了标准有效性的计算公式。 相似文献
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We present a term weighting approach for improving web page classification, based on the assumption that the images of a web page are those elements which mainly attract the attention of the user. This assumption implies that the text contained in the visual block in which an image is located, called image-block, should contain significant information about the page contents. In this paper we propose a new metric, called the Inverse Term Importance Metric, aimed at assigning higher weights to important terms contained into important image-blocks identified by performing a visual layout analysis. We propose different methods to estimate the visual image-blocks importance, to smooth the term weight according to the importance of the blocks in which the term is located. The traditional TFxIDF model is modified accordingly and used in the classification task. The effectiveness of this new metric and the proposed block evaluation methods have been validated using different classification algorithms. 相似文献
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The application of microcomputers in support of national information systems is rapidly spreading in most of the Less Developed Countries (LDCs). The advantages and limitations of the technology in these countries are discussed. Hardware and software compatibility are not as important a requirement in this context as the availability of an adapted reference format, which the present standard formats do not properly meet. The application should take into account the specific constraints of national information systems in LDCs, including the need to minimize the repetitive recording of the same data elements and to secure full compatibility with international information systems. BABINAT has been designed toward this end by a consortium of French organizations which currently support the development of information systems in the LDCs. Its rationale, characteristic features and development are presented. 相似文献
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GPS手持机在土地利用更新调查中的应用 总被引：2，自引：0，他引：2
全国土地第二次调查是目前国土部门的一项重大任务。在对手持GPS机性能和定位精度研究的基础上,总结了一些实际工作中数据采集的方法,详细说明了GPS手持机中地方坐标系和国家坐标系的转换问题,并对其定位误差的处理措施和提高定位精度的方法做了说明。 相似文献
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In collaborative filtering recommender systems recommendations can be made to groups of users. There are four basic stages in the collaborative filtering algorithms where the group’s users’ data can be aggregated to the data of the group of users: similarity metric, establishing the neighborhood, prediction phase, determination of recommended items. In this paper we perform aggregation experiments in each of the four stages and two fundamental conclusions are reached: (1) the system accuracy does not vary significantly according to the stage where the aggregation is performed, (2) the system performance improves notably when the aggregation is performed in an earlier stage of the collaborative filtering process. This paper provides a group recommendation similarity metric and demonstrates the convenience of tackling the aggregation of the group’s users in the actual similarity metric of the collaborative filtering process. 相似文献
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基于CIM的电力信息管理系统,可以解决电力系统中数据一致性问题:使电力企业各部门、各业务使用的数据保持统一性、完整性、可靠性。电力系统信息管理涉及到不同的软件平台、不同的应用软件、不同的应用模式以及不同的数据类型和格式。不仅仅是将多个应用系统连接起来,而且可以将应用软件的数据交换标准化,以及根据业务处理需求协调不同的应用。 相似文献
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AVHRR全球时间序列研究进展：PAL-GIMMS-LTDR 总被引：5，自引：1，他引：4
AVHRR是1981年～2000年间主要的全球对地观测数据集,也是正在开发的跨传感器（AVHRR-MODIS-VIIRS）长期数据集的重要组成部分。由于AVHRR数据来自多个NOAA卫星,最初是为气象预报设计的,因此在利用AVHRR进行陆地生态系统研究时,虽然取得了最初设计AVHRR时所没有预料到的成绩,但是也不断遇到一些问题。对这些问题的不同处理,就形成了很多AVHRR数据集。本文从数据完整性、时空分辨率、地图投影、文件格式、传感器标定、卫星漂移校正、云检测、大气校正、数据构成与质量标记等方面,比较了3个主要的AVHRR数据集（PAL,GIMMS,LTDR）的特征。这些特征对重新评估基于各种AVHRR数据集研究报告的可靠性,合理使用不同AVHRR数据进行陆地生态系统长期变化研究,具有一定的参考意义。 相似文献
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尽管国内外学者对国家创新系统、区域创新系统、产业创新系统进行了大量系统的研究,但是缺乏对各创新系统之间关系的研究。如果不理清各创新系统之间关系,就难以深刻、完整地把握创新系统的状态和运行,也难以科学地指导创新政策的制定。回顾了创新系统研究演进,尤其是国家创新系统、区域创新系统和产业创新系统,并探讨了国家创新系统与区域创新系统、产业创新系统之间的关系。创新系统的研究可能沿着两个方向发展:一是构建多层次框架,统领从微观企业到中观产业和区域,再到宏观层面的国家,乃至全球创新要素之间的关系;二是研究某一地理尺度(如国家、区域)上产业创新要素之间的互动关系。 相似文献
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The use of metric tensors as inputs to computer programs designed to formulate engineering and scientific problems is considered as an alternative to the use of coordinate transformation equations. 相似文献
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宇宙各种大尺度物质运动交叉协调,在地球表面构成了完整的适宜人类生存的生态环境。人类必须遵循大心度交叉协调规律,全方位地同完整的世界协调,才能健康生存与可持续发展。各行业各地区各国都应该研究同全球大协调的发展策略,自觉顺应大转折的要求,共同走向大协调文明。 相似文献
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近10多年来,全球变化已经成为了地理科学、生态学和环境科学等学科最主要的研究方向之一,而全球变化影响下的资源利用问题对于资源科技工作者而言既是挑战也是机遇。本文阐明了全球变化的多元性和复杂性特征,提出：① 全球变化不仅仅指气候变化,而且涵盖了由自然和人文因素所引起的全球尺度地球系统功能变化,存在极其复杂的经济、社会、资源、环境、技术等多重因素相互作用过程;② 全球尺度上的变化过程已由过去的单一经济格局变动演变成经济、社会、政治、人口、资源、环境、科技等多要素之间耦合或胁迫的复杂过程;③ 全球资源利用面临着七大共同挑战,新的全球资源格局逐渐形成;④ 进入新时代的中国应对全球变化下资源利用挑战,应采取内外并举的双向战略,即对外大力推动“一带一路”倡议在国际上取得重大突破,力图构建新的全球资源治理体系,保障国际资源供给安全;对内积极实施“十三五”创新驱动战略,挖掘资源利用科技创新的新动能,保障国家资源需求安全。 相似文献