Purpose： In this paper, we combined the method of co-word analysis and alluvial diagram to detect hot topics and illustrate their dynamics. Design/methodology/approach： Articles in the field of scientometrics were c...Purpose： In this paper, we combined the method of co-word analysis and alluvial diagram to detect hot topics and illustrate their dynamics. Design/methodology/approach： Articles in the field of scientometrics were chosen as research cases in this study. A time-sliced co-word network was generated and then clustered. Afterwards, we generated an alluvial diagram to show dynamic changes of hot topics, including their merges and splits over time. Findings： After analyzing the dynamic changes in the field of scientometrics from 2011 to 2015, we found that two clusters being merged did not mean that the old topics had disappeared and a totally new one had emerged. The topics were possibly still active the following year, but the newer topics had drawn more attention. The changes of hot topics reflected the shift in researchers＇ interests. subdivided and re-merged. For example, several topics as research progressed. Research topics in scientometrics were constantly a cluster involving ＂industry＂ was divided into Research limitations： When examining longer time periods, we encounter the problem of dealing with bigger data sets. Analyzing data year by year would be tedious, but if we combine, e.g. two years into one time slice, important details would be missed. Practical implications： This method can be applied to any research field to illustrate the dynamics of hot topics. It can indicate the promising directions for researchers and provide guidance to decision makers. Originality/value： The use of alluvial diagrams is a distinctive and meaningful approach to detecting hot topics and especially to illustrating their dynamics.展开更多
In order to realize the explorer autonomy, the software architecture of autonomous mission management system (AMMS) is given for the deep space explorer, and the autonomous mission planning system, the kernel part of ...In order to realize the explorer autonomy, the software architecture of autonomous mission management system (AMMS) is given for the deep space explorer, and the autonomous mission planning system, the kernel part of this architecture, is designed in detail. In order to describe the parallel activity, the state timeline is introduced to build the formal model of the planning system and based on this model, the temporal constraint satisfaction planning algorithm is proposed to produce the explorer’s activity sequence. With some key subsystems of the deep space explorer as examples, the autonomous mission planning simulation system is designed. The results show that this system can calculate the executable activity sequence with the given mission goals and initial state of the explorer.展开更多
This biographical timeline complements the biography of Professor Karl Pister at the beginning of this special issue in providing the background information of some of Professor Karl Pister’s influential teachers,men...This biographical timeline complements the biography of Professor Karl Pister at the beginning of this special issue in providing the background information of some of Professor Karl Pister’s influential teachers,mentors,colleagues,research collaborators,and students.展开更多
在过去的30年中,Timeliner语言被成功应用在国际空间站和轨道快车的任务管理、核心操作与有效载荷操作、运载火箭提供自主发射控制系统等诸多方面。然而Timeliner的相关技术研究大多集中在欧美发达国家,因此开展和掌握Timeliner相关技...在过去的30年中,Timeliner语言被成功应用在国际空间站和轨道快车的任务管理、核心操作与有效载荷操作、运载火箭提供自主发射控制系统等诸多方面。然而Timeliner的相关技术研究大多集中在欧美发达国家,因此开展和掌握Timeliner相关技术对促进我国相关领域研究和应用水平的提高具有重要意义。本文基于对Timeliner语言的深入分析和将其在自主任务规划调度领域应用的成功经验,借鉴Timeliner思想设计了TSCL(Timeliner-based Spacecraft Control Language)脚本控制语言规范,实现了一个简单的编译执行环境原型,为今后的研究与应用打下良好的基础。展开更多
Human ancestors first set foot on the interior of the Qinghai-Tibetan Plateau around 30,000–40,000 years ago, according to new research by scientists from the Chinese Academy of Sciences(CAS). This new finding moves ...Human ancestors first set foot on the interior of the Qinghai-Tibetan Plateau around 30,000–40,000 years ago, according to new research by scientists from the Chinese Academy of Sciences(CAS). This new finding moves back the earliest data of habitation in the interior by 20,000 years or more.展开更多
250B.C.Ctesibius of Alexandriabuilds organs and water clockswith movable figures.1495The first humanoidrobot was designed to situp,wave its arms,and moveits head via a flexible neckwhile opening and closing itsjaw.
In mathematics, space encompasses various structured sets such as Euclidean, metric, or vector space. This article introduces temporal space—a novel concept independent of traditional spatial dimensions and frames of...In mathematics, space encompasses various structured sets such as Euclidean, metric, or vector space. This article introduces temporal space—a novel concept independent of traditional spatial dimensions and frames of reference, accommodating multiple object-oriented durations in a dynamical system. The novelty of building temporal space using finite geometry is rooted in recent advancements in the theory of relationalism which utilizes Euclidean geometry, set theory, dimensional analysis, and a causal signal system. Multiple independent and co-existing cyclic durations are measurable as a network of finite one-dimensional timelines. The work aligns with Leibniz’s comments on relational measures of duration with the addition of using discrete cyclic relational events that define these finite temporal spaces, applicable to quantum and classical physics. Ancient formulas have symmetry along with divisional and subdivisional orders of operations that create discrete and ordered temporal geometric elements. Elements have cyclically conserved symmetry but unique cyclic dimensional quantities applicable for anchoring temporal equivalence relations in linear time. We present both fixed equivalences and expanded periods of temporal space offering a non-Greek calendar methodology consistent with ancient global timekeeping descriptions. Novel applications of Euclid’s division algorithm and Cantor’s pairing function introduce a novel paired function equation. The mathematical description of finite temporal space within relationalism theory offers an alternative discrete geometric methodology for examining ancient timekeeping with new hypotheses for Egyptian calendars.展开更多
Timeline generation is an important research task which can help users to have a quick understanding of the overall evolution of one given topic. Previous methods simply split the time span into fixed, equal time inte...Timeline generation is an important research task which can help users to have a quick understanding of the overall evolution of one given topic. Previous methods simply split the time span into fixed, equal time intervals without studying the role of the evolutionary patterns of the underlying topic in timeline generation. In addition, few of these methods take users＇ collective interests into considerations to generate timelines. We consider utilizing social media attention to address these two problems due to the facts： 1） social media is an important pool of real users＇ collective interests; 2） the information cascades generated in it might be good indicators for boundaries of topic phases. Employing Twitter as a basis, we propose to incorporate topic phases and user＇s collective interests which are learnt from social media into a unified timeline generation algorithm. We construct both one informativeness-oriented and three interestingness-oriented evaluation sets over five topics. We demonstrate that it is very effective to generate both informative and interesting timelines. In addition, our idea naturally leads to a novel presen- tation of timelines, i.e., phase based timelines, which can potentially improve user experience.展开更多
With the increase of space debris,space debris removal has gradually become a major issue to address by worldwide space agencies.Multiple debris removal missions,in which multiple debris objects are removed in a singl...With the increase of space debris,space debris removal has gradually become a major issue to address by worldwide space agencies.Multiple debris removal missions,in which multiple debris objects are removed in a single mission,are an economical approach to purify the space environment.Such missions can be considered typical time-dependent traveling salesman problems(TDTSPs).In this study,an intelligent global optimization algorithm called Timeline Club Optimization(TCO)is proposed to solve multiple debris removal missions of the TDTSP model.TCO adopts the traditional ant colony optimization(ACO)framework and replaces the pheromone matrix of the ACO with a new structure called the Timeline Club.The Timeline Club records which debris object to be removed next at a certain moment from elitist solutions and decides the probability criterion to generate debris sequences in new solutions.Two hypothetical scenarios,the Iridium-33 mission and the GTOC9 mission,are considered in this study.Simulation results show that TCO offers better performance than those of beam search,ant colony optimization,and the genetic algorithm in multiple debris removal missions of the TDTSP model.展开更多
Google Location Timeline,once activated,allows to track devices and save their locations.This feature might be useful in the future as available data for evidence in investigations.For that,the court would be interest...Google Location Timeline,once activated,allows to track devices and save their locations.This feature might be useful in the future as available data for evidence in investigations.For that,the court would be interested in the reliability of these data.The position is presented in the form of a pair of coordinates and a radius,hence the estimated area for tracked device is enclosed by a circle.This research focuses on the assessment of the accuracy of the locations given by Google Location History Timeline,which variables affect this accuracy and the initial steps to develop a linear multivariate model that can potentially predict the actual error with respect to the true location considering environmental variables.The determination of the potential influential variables(configuration of mobile device connectivity,speed of movement and environment)was set through a series of experiments in which the true position of the device was recorded with a reference Global Positioning System(GPS)device with a superior order of accuracy.The accuracy was assessed measuring the distance between the Google provided position and the de facto one,later referred to as Google error.If this Google error distance is less than the radius provided,we define it as a hit.The configuration that has the largest hit rate is when the mobile device has GPS available,with a 52%success.Then the use of 3G and 2G connection go with 38%and 33%respectively.The Wi-Fi connection only has a hit rate of 7%.Regarding the means of transport,when the connection is 2G or 3G,the worst results are in Still with a hit rate of 9%and the best in Car with 57%.Regarding the prediction model,the distances and angles from the position of the device to the three nearest cell towers,and the categorical(nonnumerical)variables of Environment and means of transport were taking as input variables in this initial study.To evaluate the usability of a model,a Model hit is defined when the actual observation is within the 95%confidence interval provided by the model.Out of the models developed,the one that shows the best results was the one that predicted the accuracy when the used network is 2G,with 76%of Model hits.The second model with best performance had only a 23%success(with the mobile network set to 3G).展开更多
March 28 Underground water floods the pit of Wangjialing Coal Mine at approximately 1:40 p.m.,and 108 workers escape while 153 others remain trapped in the shaft.
The riot in Xinjiang capital leaves horrible memories in the multiethnic city The evening of July 5 was like any other in People’s Square in downtown Urumqi, capital of northwest China’s Xinjiang Uygur Autonomous Re...The riot in Xinjiang capital leaves horrible memories in the multiethnic city The evening of July 5 was like any other in People’s Square in downtown Urumqi, capital of northwest China’s Xinjiang Uygur Autonomous Region. People were out enjoying the night air, walking, singing and dancing.展开更多
Standalone systems cannot handle the giant traffic loads generated by Twitter due to memory constraints.A parallel computational environment pro-vided by Apache Hadoop can distribute and process the data over differen...Standalone systems cannot handle the giant traffic loads generated by Twitter due to memory constraints.A parallel computational environment pro-vided by Apache Hadoop can distribute and process the data over different desti-nation systems.In this paper,the Hadoop cluster with four nodes integrated with RHadoop,Flume,and Hive is created to analyze the tweets gathered from the Twitter stream.Twitter stream data is collected relevant to an event/topic like IPL-2015,cricket,Royal Challengers Bangalore,Kohli,Modi,from May 24 to 30,2016 using Flume.Hive is used as a data warehouse to store the streamed tweets.Twitter analytics like maximum number of tweets by users,the average number of followers,and maximum number of friends are obtained using Hive.The network graph is constructed with the user’s unique screen name and men-tions using‘R’.A timeline graph of individual users is generated using‘R’.Also,the proposed solution analyses the emotions of cricket fans by classifying their Twitter messages into appropriate emotional categories using the optimized sup-port vector neural network(OSVNN)classification model.To attain better classi-fication accuracy,the performance of SVNN is enhanced using a chimp optimization algorithm(ChOA).Extracting the users’emotions toward an event is beneficial for prediction,but when coupled with visualizations,it becomes more powerful.Bar-chart and wordcloud are generated to visualize the emotional analysis results.展开更多
基金supported by the National Social Science Foundation of China (Grant No.: 14BTQ030)
文摘Purpose： In this paper, we combined the method of co-word analysis and alluvial diagram to detect hot topics and illustrate their dynamics. Design/methodology/approach： Articles in the field of scientometrics were chosen as research cases in this study. A time-sliced co-word network was generated and then clustered. Afterwards, we generated an alluvial diagram to show dynamic changes of hot topics, including their merges and splits over time. Findings： After analyzing the dynamic changes in the field of scientometrics from 2011 to 2015, we found that two clusters being merged did not mean that the old topics had disappeared and a totally new one had emerged. The topics were possibly still active the following year, but the newer topics had drawn more attention. The changes of hot topics reflected the shift in researchers＇ interests. subdivided and re-merged. For example, several topics as research progressed. Research topics in scientometrics were constantly a cluster involving ＂industry＂ was divided into Research limitations： When examining longer time periods, we encounter the problem of dealing with bigger data sets. Analyzing data year by year would be tedious, but if we combine, e.g. two years into one time slice, important details would be missed. Practical implications： This method can be applied to any research field to illustrate the dynamics of hot topics. It can indicate the promising directions for researchers and provide guidance to decision makers. Originality/value： The use of alluvial diagrams is a distinctive and meaningful approach to detecting hot topics and especially to illustrating their dynamics.
文摘In order to realize the explorer autonomy, the software architecture of autonomous mission management system (AMMS) is given for the deep space explorer, and the autonomous mission planning system, the kernel part of this architecture, is designed in detail. In order to describe the parallel activity, the state timeline is introduced to build the formal model of the planning system and based on this model, the temporal constraint satisfaction planning algorithm is proposed to produce the explorer’s activity sequence. With some key subsystems of the deep space explorer as examples, the autonomous mission planning simulation system is designed. The results show that this system can calculate the executable activity sequence with the given mission goals and initial state of the explorer.
文摘This biographical timeline complements the biography of Professor Karl Pister at the beginning of this special issue in providing the background information of some of Professor Karl Pister’s influential teachers,mentors,colleagues,research collaborators,and students.
文摘在过去的30年中,Timeliner语言被成功应用在国际空间站和轨道快车的任务管理、核心操作与有效载荷操作、运载火箭提供自主发射控制系统等诸多方面。然而Timeliner的相关技术研究大多集中在欧美发达国家,因此开展和掌握Timeliner相关技术对促进我国相关领域研究和应用水平的提高具有重要意义。本文基于对Timeliner语言的深入分析和将其在自主任务规划调度领域应用的成功经验,借鉴Timeliner思想设计了TSCL(Timeliner-based Spacecraft Control Language)脚本控制语言规范,实现了一个简单的编译执行环境原型,为今后的研究与应用打下良好的基础。
文摘Human ancestors first set foot on the interior of the Qinghai-Tibetan Plateau around 30,000–40,000 years ago, according to new research by scientists from the Chinese Academy of Sciences(CAS). This new finding moves back the earliest data of habitation in the interior by 20,000 years or more.
文摘250B.C.Ctesibius of Alexandriabuilds organs and water clockswith movable figures.1495The first humanoidrobot was designed to situp,wave its arms,and moveits head via a flexible neckwhile opening and closing itsjaw.
文摘In mathematics, space encompasses various structured sets such as Euclidean, metric, or vector space. This article introduces temporal space—a novel concept independent of traditional spatial dimensions and frames of reference, accommodating multiple object-oriented durations in a dynamical system. The novelty of building temporal space using finite geometry is rooted in recent advancements in the theory of relationalism which utilizes Euclidean geometry, set theory, dimensional analysis, and a causal signal system. Multiple independent and co-existing cyclic durations are measurable as a network of finite one-dimensional timelines. The work aligns with Leibniz’s comments on relational measures of duration with the addition of using discrete cyclic relational events that define these finite temporal spaces, applicable to quantum and classical physics. Ancient formulas have symmetry along with divisional and subdivisional orders of operations that create discrete and ordered temporal geometric elements. Elements have cyclically conserved symmetry but unique cyclic dimensional quantities applicable for anchoring temporal equivalence relations in linear time. We present both fixed equivalences and expanded periods of temporal space offering a non-Greek calendar methodology consistent with ancient global timekeeping descriptions. Novel applications of Euclid’s division algorithm and Cantor’s pairing function introduce a novel paired function equation. The mathematical description of finite temporal space within relationalism theory offers an alternative discrete geometric methodology for examining ancient timekeeping with new hypotheses for Egyptian calendars.
文摘Timeline generation is an important research task which can help users to have a quick understanding of the overall evolution of one given topic. Previous methods simply split the time span into fixed, equal time intervals without studying the role of the evolutionary patterns of the underlying topic in timeline generation. In addition, few of these methods take users＇ collective interests into considerations to generate timelines. We consider utilizing social media attention to address these two problems due to the facts： 1） social media is an important pool of real users＇ collective interests; 2） the information cascades generated in it might be good indicators for boundaries of topic phases. Employing Twitter as a basis, we propose to incorporate topic phases and user＇s collective interests which are learnt from social media into a unified timeline generation algorithm. We construct both one informativeness-oriented and three interestingness-oriented evaluation sets over five topics. We demonstrate that it is very effective to generate both informative and interesting timelines. In addition, our idea naturally leads to a novel presen- tation of timelines, i.e., phase based timelines, which can potentially improve user experience.
基金This research was supported by the National Key R&D Program of China(No.2019YFA0706500).
文摘With the increase of space debris,space debris removal has gradually become a major issue to address by worldwide space agencies.Multiple debris removal missions,in which multiple debris objects are removed in a single mission,are an economical approach to purify the space environment.Such missions can be considered typical time-dependent traveling salesman problems(TDTSPs).In this study,an intelligent global optimization algorithm called Timeline Club Optimization(TCO)is proposed to solve multiple debris removal missions of the TDTSP model.TCO adopts the traditional ant colony optimization(ACO)framework and replaces the pheromone matrix of the ACO with a new structure called the Timeline Club.The Timeline Club records which debris object to be removed next at a certain moment from elitist solutions and decides the probability criterion to generate debris sequences in new solutions.Two hypothetical scenarios,the Iridium-33 mission and the GTOC9 mission,are considered in this study.Simulation results show that TCO offers better performance than those of beam search,ant colony optimization,and the genetic algorithm in multiple debris removal missions of the TDTSP model.
基金supported by the Nederlands Forensisch Instituut.
文摘Google Location Timeline,once activated,allows to track devices and save their locations.This feature might be useful in the future as available data for evidence in investigations.For that,the court would be interested in the reliability of these data.The position is presented in the form of a pair of coordinates and a radius,hence the estimated area for tracked device is enclosed by a circle.This research focuses on the assessment of the accuracy of the locations given by Google Location History Timeline,which variables affect this accuracy and the initial steps to develop a linear multivariate model that can potentially predict the actual error with respect to the true location considering environmental variables.The determination of the potential influential variables(configuration of mobile device connectivity,speed of movement and environment)was set through a series of experiments in which the true position of the device was recorded with a reference Global Positioning System(GPS)device with a superior order of accuracy.The accuracy was assessed measuring the distance between the Google provided position and the de facto one,later referred to as Google error.If this Google error distance is less than the radius provided,we define it as a hit.The configuration that has the largest hit rate is when the mobile device has GPS available,with a 52%success.Then the use of 3G and 2G connection go with 38%and 33%respectively.The Wi-Fi connection only has a hit rate of 7%.Regarding the means of transport,when the connection is 2G or 3G,the worst results are in Still with a hit rate of 9%and the best in Car with 57%.Regarding the prediction model,the distances and angles from the position of the device to the three nearest cell towers,and the categorical(nonnumerical)variables of Environment and means of transport were taking as input variables in this initial study.To evaluate the usability of a model,a Model hit is defined when the actual observation is within the 95%confidence interval provided by the model.Out of the models developed,the one that shows the best results was the one that predicted the accuracy when the used network is 2G,with 76%of Model hits.The second model with best performance had only a 23%success(with the mobile network set to 3G).
文摘March 28 Underground water floods the pit of Wangjialing Coal Mine at approximately 1:40 p.m.,and 108 workers escape while 153 others remain trapped in the shaft.
文摘The riot in Xinjiang capital leaves horrible memories in the multiethnic city The evening of July 5 was like any other in People’s Square in downtown Urumqi, capital of northwest China’s Xinjiang Uygur Autonomous Region. People were out enjoying the night air, walking, singing and dancing.
文摘Standalone systems cannot handle the giant traffic loads generated by Twitter due to memory constraints.A parallel computational environment pro-vided by Apache Hadoop can distribute and process the data over different desti-nation systems.In this paper,the Hadoop cluster with four nodes integrated with RHadoop,Flume,and Hive is created to analyze the tweets gathered from the Twitter stream.Twitter stream data is collected relevant to an event/topic like IPL-2015,cricket,Royal Challengers Bangalore,Kohli,Modi,from May 24 to 30,2016 using Flume.Hive is used as a data warehouse to store the streamed tweets.Twitter analytics like maximum number of tweets by users,the average number of followers,and maximum number of friends are obtained using Hive.The network graph is constructed with the user’s unique screen name and men-tions using‘R’.A timeline graph of individual users is generated using‘R’.Also,the proposed solution analyses the emotions of cricket fans by classifying their Twitter messages into appropriate emotional categories using the optimized sup-port vector neural network(OSVNN)classification model.To attain better classi-fication accuracy,the performance of SVNN is enhanced using a chimp optimization algorithm(ChOA).Extracting the users’emotions toward an event is beneficial for prediction,but when coupled with visualizations,it becomes more powerful.Bar-chart and wordcloud are generated to visualize the emotional analysis results.
