Research on multiple elimination methods in inverse data space based on randomized singular value decomposition

Based on surfaced-related multiple elimination( SRME),this research has derived the methods on multiples elimination in the inverse data space.Inverse data processing means moving seismic data from forward data space( FDS) to inverse data space( IDS).The surface-related multiples and primaries can then be separated in the IDS,since surface-related multiples will form a focus region in the IDS.Muting the multiples energy can achieve the purpose of multiples elimination and avoid the damage to primaries energy during the process of adaptive subtraction.Randomized singular value decomposition( RSVD) is used to enhance calculation speed and improve the accuracy in the conversion of FDS to IDS.The synthetic shot record of the salt dome model shows that the relationship between primaries and multiples is simple and clear,and RSVD can easily eliminate multiples and save primaries energy.Compared with conventional multiples elimination methods and ordinary methods of multiples elimination in the inverse data space,this technique has an advantage of high calculation speed and reliable outcomes.

数据空间建设的实践进展与运营模式分析——基于Data Spaces Radar的案例

数据空间建设为数据要素的价值实现提供了可资借鉴的实践经验,全面解析其实践进展与运营模式,有助于破解数据流通的现实堵点、拓展数据利用的发展思路。文章首先将结构主义分析方法中的案例研究法作为主要研究方法,综合运用文献调研、比较分析等方法,以Data Spaces Radar为案例来源,从实践进展、运营模式、核心要素等维度提炼数据空间建设特征。其次,在制度与技术的双轮驱动下,数据空间建设秉持制度规范统一性、技术设计整体性和治理模式协同性的架构原则,并按照产业思维、底线思维、信任思维、链式思维、集约思维的底层逻辑,形成较为完整的运营体系。未来应着力探索和解决数据空间视域下的数据资源价值化开发路径,针对数据流通堵点、利用痛点及信任难点问题,从体制机制、政策框架与技术应用等角度为推进我国的数据要素流通利用提供有益参考。

Research on key technologies of edge cache in virtual data space across WAN

The authors of this paper have previously proposed the global virtual data space system (GVDS) to aggregate the scattered and autonomous storage resources in China’s national supercomputer grid (National Supercomputing Center in Guangzhou, National Supercomputing Center in Jinan, National Supercomputing Center in Changsha, Shanghai Supercomputing Center, and Computer Network Information Center in Chinese Academy of Sciences) into a storage system that spans the wide area network (WAN), which realizes the unified management of global storage resources in China. At present, the GVDS has been successfully deployed in the China National Grid environment. However, when accessing and sharing remote data in the WAN, the GVDS will cause redundant transmission of data and waste a lot of network bandwidth resources. In this paper, we propose an edge cache system as a supplementary system of the GVDS to improve the performance of upper-level applications accessing and sharing remote data. Specifically, we first designs the architecture of the edge cache system, and then study the key technologies of this architecture: the edge cache index mechanism based on double-layer hashing, the edge cache replacement strategy based on the GDSF algorithm, the request routing based on consistent hashing method, and the cluster member maintenance method based on the SWIM protocol. The experimental results show that the edge cache system has successfully implemented the relevant operation functions (read, write, deletion, modification, etc.) and is compatible with the POSIX interface in terms of function. Further, it can greatly reduce the amount of data transmission and increase the data access bandwidth when the accessed file is located at the edge cache system in terms of performance, i.e., its performance is close to the performance of the network file system in the local area network (LAN).

Reliable transmission of consultative committee for space data systems file delivery protocol in deep space communication

In consultative committee for space data systems（CCSDS） file delivery protocol（CFDP） recommendation of reliable transmission,there are no detail transmission procedure and delay calculation of prompted negative acknowledge and asynchronous negative acknowledge models.CFDP is designed to provide data and storage management,story and forward,custody transfer and reliable end-to-end delivery over deep space characterized by huge latency,intermittent link,asymmetric bandwidth and big bit error rate（BER）.Four reliable transmission models are analyzed and an expected file-delivery time is calculated with different trans-mission rates,numbers and sizes of packet data units,BERs and frequencies of external events,etc.By comparison of four CFDP models,the requirement of BER for typical missions in deep space is obtained and rules of choosing CFDP models under different uplink state informations are given,which provides references for protocol models selection,utilization and modification.

THE STATE SPACE RECONSTRUCTION TECHNOLOGY OF DIFFERENT KINDS OF CHAOTIC DATA OBTAINED FROM DYNAMICAL SYSTEM

Certain deterministic nonlinear systems may show chaotic behavior. We consider the motion of qualitative information and the practicalities of extracting a part from chaotic experimental data. Our approach based on a theorem of Takens draws on the ideas from the generalized theory of information known as singular system analysis. We illustrate this technique by numerical data from the chaotic region of the chaotic experimental data. The method of the singular-value decomposition is used to calculate the eigenvalues of embedding space matrix. The corresponding concrete algorithm to calculate eigenvectors and to obtain the basis of embedding vector space is proposed in this paper. The projection on the orthogonal basis generated by eigenvectors of timeseries data and concrete paradigm are also provided here. Meanwhile the state space reconstruction technology of different kinds of chaotic data obtained from dynamical system has also been discussed in detail.

Constructing Three-Dimension Space Graph for Outlier Detection Algorithms in Data Mining

Outlier detection has very important applied value in data mining literature. Different outlier detection algorithms based on distinct theories have different definitions and mining processes. The three-dimensional space graph for constructing applied algorithms and an improved GridOf algorithm were proposed in terms of analyzing the existing outlier detection algorithms from criterion and theory. Key words outlier - detection - three-dimensional space graph - data mining CLC number TP 311. 13 - TP 391 Foundation item: Supported by the National Natural Science Foundation of China (70371015)Biography: ZHANG Jing (1975-), female, Ph. D, lecturer, research direction: data mining and knowledge discovery.

基于CiteSpace的用户画像知识图谱分析

为了明确用户画像研究热点和趋势,文章运用CiteSpace软件定量化分析知网1496篇用户画像文献。研究结果表明,国内对用户画像研究呈现增长态势,总体经历了研究萌芽、快速发展和质量提升三个阶段,虽然研究机构和作者群体稳定,但尚未形成核心作者群和跨专业领域的合作。研究趋势方面,大数据、数据挖掘、图书馆、机器学习、人工智能、精准营销、知识服务、协同过滤等是主要研究热点;前沿研究聚焦于信息服务、融媒体、数据采集、媒体融合和聚类。

Experiment on diffuse reflection laser ranging to space debris and data analysis

Space debris poses a serious threat to human space activities and needs to be measured and cataloged. As a new technology for space target surveillance, the measurement accuracy of diffuse reflection laser ranging （DRLR） is much higher than that of microwave radar and optoelectronic measurement. Based on the laser ranging data of space debris from the DRLR system at Shanghai Astronomical Observatory acquired in March-April, 2013, the characteristics and precision of the laser ranging data are analyzed and their applications in orbit determination of space debris are discussed, which is implemented for the first time in China. The experiment indicates that the precision of laser ranging data can reach 39 cm-228 cm. When the data are sufficient enough （four arcs measured over three days）, the orbital accuracy of space debris can be up to 50 m.

Modeling and Simulation Study of Space Data Link Protocol

This research paper describes the design and implementation of the Consultative Committee for Space Data Systems (CCSDS) standards REF _Ref401069962 \r \h \* MERGEFORMAT [1] for Space Data Link Layer Protocol (SDLP). The primer focus is the telecommand (TC) part of the standard. The implementation of the standard was in the form of DLL functions using C++ programming language. The second objective of this paper was to use the DLL functions with OMNeT++ simulating environment to create a simulator in order to analyze the mean end-to-end Packet Delay, maximum achievable application layer throughput for a given fixed link capacity and normalized protocol overhead, defined as the total number of bytes transmitted on the link in a given period of time (e.g. per second) divided by the number of bytes of application data received at the application layer model data sink. In addition, the DLL was also integrated with Ground Support Equipment Operating System (GSEOS), a software system for space instruments and small spacecrafts especially suited for low budget missions. The SDLP is designed for rapid test system design and high flexibility for changing telemetry and command requirements. GSEOS can be seamlessly moved from EM/FM development (bench testing) to flight operations. It features the Python programming language as a configuration/scripting tool and can easily be extended to accommodate custom hardware interfaces. This paper also shows the results of the simulations and its analysis.

Direct data domain approach to space-time adaptive processing

In non-homogeneous environment, traditional space-time adaptive processing doesn＇t effectively suppress interference and detect target, because the secondary data don＇ t exactly reflect the statistical characteristic of the range cell under test. A ravel methodology utilizing the direct data domain approach to space-time adaptive processing （ STAP ） in airbome radar non-homogeneous environments is presented. The deterministic least squares adaptive signal processing technique operates on a ＂snapshot-by-snapshot＂ basis to dethrone the adaptive adaptive weights for nulling interferences and estimating signal of interest （SOI）. Furthermore, this approach eliminates the requirement for estimating the covariance through the data of neighboring range cell, which eliminates calculating the inverse of covariance, and can be implemented to operate in real-time. Simulation results illustrate the efficiency of interference suppression in non-homogeneous environment.

Correspondence Analysis on a Space-Time Data Set for Multiple Environmental Variables

Applications of the multivariate technique called correspondence analysis for environmental studies are relatively new and are limited to spatial multivariate data set. In this paper, a procedure of applying correspondence analysis to a large space-time data set for multiple environmental variables is shown. In particular, nitrogen dioxide and carbon monoxide hourly concentrations measured during January 1999 at several monitored stations in a district of Northern Italy are analyzed. The procedure consists in transforming the continuous variables into categorical ones by the means of appropriate indicator variables, generating special contingency tables and applying correspondence analysis. The use of this classical multivariate technique allows the identification of important relationships among pollution levels and monitoring stations and/or relationships among pollution levels and observation times.

Evidences of the expanding Earth from space-geodetic data over solid land and sea level rise in recent two decades

According to the space-geodetic data recorded at globally distributed stations over solid land spanning a period of more than 20-years under the International Terrestrial Reference Frame 2008,our previous estimate of the average-weighted vertical variation of the Earth＇s solid surface suggests that the Earth＇s solid part is expanding at a rate of 0.24 ± 0.05 mm/a in recent two decades.In another aspect,the satellite altimetry observations spanning recent two decades demonstrate the sea level rise（SLR） rate 3.2 ± 0.4 mm/a,of which1.8 ± 0.5 mm/a is contributed by the ice melting over land.This study shows that the oceanic thermal expansion is 1.0 ± 0.1 mm/a due to the temperature increase in recent half century,which coincides with the estimate provided by previous authors.The SLR observation by altimetry is not balanced by the ice melting and thermal expansion,which is an open problem before this study.However,in this study we infer that the oceanic part of the Earth is expanding at a rate about 0.4 mm/a.Combining the expansion rates of land part and oceanic part,we conclude that the Earth is expanding at a rate of 0.35 ± 0.47 mm/a in recent two decades.If the Earth expands at this rate,then the altimetry-observed SLR can be well explained.

高新区转型下的国内创新城区研究进展与展望:基于CiteSpace文献计量软件

创新城区是未来城市创新化和综合化发展的重要空间形式,其因设施系统性、功能多样性和服务综合性而受到众多关注.高新区作为以高新技术产业开发为主要功能的区域,与综合性功能的创新城区还有很大差距,若将两者进行系统对比分析则有利于进一步了解国内创新城区发展基础并促进高新区向创新城区转型.本文以中国知网核心期刊作为文献来源,运用CiteSpace文献计量软件对国内2000—2021年高新区和创新城区领域文献的年份、作者、机构和关键词进行可视化分析和对比研究.结果显示,在发展演变、学界研究及研究热点上,高新区的研究较为系统丰富,创新城区的研究相对不足,且国内对二者的研究均存在一些不足.基于此,从研究脉络、研究方法、研究内容以及学科层面展开了评述,并从多尺度、分重点、全域性和多角度4个方面提出了对高新区转型和创新城区建设的研究展望.

我国警察心理健康研究的知识图谱——基于CiteSpace的可视化分析

以中国知网为检索源,共纳入790篇与警察心理健康相关的期刊论文作为文章的研究对象。借助CiteSpace软件对现有的警察心理健康研究进行演进历程、发文作者、研究机构、关键词共现、聚类与突现等可视化分析。结果发现,警察的心理健康状况与水平是研究的焦点,但尚未提出能有效预防、干预警察心理健康问题的举措。因此,在未来的实践和研究中应积极关注警察及警校生的日常生活和心理健康状况,为警察赋能,根据警察的职业特殊性建立适配警察的心理健康服务体系。

元宇宙视域下个人信息保护的困境及法规重塑

元宇宙是下一代互联网的数字技术媒介。在元宇宙的中心化治理、分布式治理的场景下,个人可以实现深度媒介化的虚拟数字化生存,也伴随着数据安全的挑战,面临着个人信息外延持续扩大、个人生物信息被收集、“知情-同意”原则被冲击、传统信息监管模式被打破等个人信息保护危机。加强对元宇宙的规则建构探索,对于个人数据安全乃至国家战略安全都具有重要意义。当前,需要通过构建技术促进规则、厘清个人生物信息法律定位、重构分层—动态同意原则、平衡平台与个人权利关系等有效措施,积极解决元宇宙数字媒介空间下的个人信息保护问题。

基于激光雷达与遥感数据的地理空间要素识别方法

通过地理空间要素识别实现地理测绘和环境有效监测,提出基于激光雷达与遥感数据的地理空间要素识别方法。采用激光雷达的遥感监测方法实现对地理空间特征的对象集变化检测,根据地理空间测绘对象的纹理、形状、空间关系,采用遥感数据融合和空间信息表达方法实现对地理空间要素特征的专家知识融合,构建地理空间要素识别的遥感专家数据库。仿真结果表明,采用该方法进行地理空间要素识别的决策融合性较好。该方法也实现了对土地利用自然特征变化的检测,使得识别准确率的最大值可达到0.925,且识别耗时始终处于2.5 s以下。

城市轨道交通系统的层次化功能结构解析——以上海为例

解析城市轨道交通系统的功能结构对于建立以轨道交通为骨架的城市空间结构至关重要,其有助于优化城市空间布局,促进交通与土地利用融合,进而推动城市可持续发展。本文利用交通刷卡大数据,基于轨道交通站域的功能相似性和邻接关系提出了功能站组的概念,并形成了一套“站域功能分类—站组范围划定—站群结构识别”的方法体系。以上海市轨道交通系统为例,针对单个站域,构建表征站域土地利用功能的连续客流时间序列,并依据时间序列特征分类得到站域功能类型;将多个具有相似的出行模式和土地利用功能的相邻站域划定为功能站组;以功能站组为基本单元,采用社区发现算法,对功能站组间的客流交互网络进行分析以识别站群。研究结果表明,城市轨道交通系统的“站域—站组—站群”层次化功能结构解析方法综合了场所空间和流空间视角,有助于认识特大城市轨道交通系统的功能结构特征,并为轨道交通系统的发展提供多层次的空间优化建议。

基于多源数据的重庆中心城区绿地生态系统文化服务供需关系研究

快速城市化及城市扩张过程中,城市绿地生态系统文化服务(CES)供给与公众需求空间失衡问题日益凸显。如何有效识别城市绿地文化服务供需空间匹配特征是优化绿地空间布局、提升绿地服务效率的关键所在。本研究以重庆市中心城区为研究范围,基于地理空间数据等多源数据,运用GIS分析技术、空间相关性分析等方法,构建了城市绿地文化服务供需评价指标体系和分析框架,识别了山地城市绿地文化服务供给与居民需求的空间匹配类型。研究发现CES供给具明显的空间聚集性,全局莫兰指数为0.720,呈现为“大核—次核—小核”的分布形态,CES需求全局莫兰指数为0.834,呈现中心高外围低、西高东低的空间格局,双变量自相关分析显示供给与需求之间存在空间结构相似性,CES供需关系整体上较好,但一些关键区域匹配失衡压力较大。根据供需平衡关系特征,将研究区识别为六类空间类型,并对每种类型提出了CES优化提升路径。研究结果可为山地城市绿地生态系统文化服务优化路径提供理论支撑与实践借鉴。

城市中心区轨道交通站点步行接驳路径特征及优化

轨道交通站点步行接驳路径特征研究,对提升轨道交通承担率具有重要意义。基于百度时空大数据API,运用空间分析法、情景模拟法、视觉语义分割法,以天津市营口道站点为例,构建城市中心区轨道交通站点步行接驳路径特征分析方法,挖掘步行接驳路径特征并揭示成因,提出针对性的优化对策。研究表明,目标站点步行接驳效率南部高于北部,具体表现在路段重复率分布均匀度南部大于北部,差异路径分布数量北部多于南部,超过3/4路径的非直线系数偏高;除站点周边区域外,接驳路径品质西北部优于东南部,具体表现在西北部视觉出行环境建设最优,区域整体设施服务水平良好。根据步行接驳路径特征,提出路网结构调整、道路断面优化、出入口调整、绿化品质提升的优化对策。

基于游记大数据的环巢湖地区乡村旅游客源市场时空结构分析

以环巢湖地区作为研究对象,基于2016—2021年旅游网站的乡村旅游游记数据,结合统计分析以及ArcGIS空间分析法研究环巢湖地区乡村旅游客源市场的结构特征以及影响因素。结果表明:乡村旅游客源市场季节性明显,节假日及周末效应突出,其中4至10月为旅游旺季,11至3月为旅游淡季;乡村旅游客源市场的地理集中指数总体较高,客源呈集中分布特征,合肥市为主要客源地,客源吸引半径均值为219.59 km,属于近程客源市场,空间使用曲线是基本型曲线、“U”型曲线和Maxwell-Boltzman曲线3种曲线的复合,客源核心逐渐从长三角地区、京津冀地区向内陆地区、珠三角地区扩散。乡村旅游客源市场的时空结构是多种因素相互作用的结果,主要是由乡村旅游目的地的特殊性决定的,同时闲暇时间、气候舒适度、交通、客源地经济发展水平等也是重要影响因素。