Commercial behavior in towns and cities is mainly divided into formal and informal behavior.Rapid urbanization has enabled formal commerce to develop more and more perfectly in towns,basically meeting the living needs...Commercial behavior in towns and cities is mainly divided into formal and informal behavior.Rapid urbanization has enabled formal commerce to develop more and more perfectly in towns,basically meeting the living needs of residents. However, because of problems such as urban history and management mechanism, informal commercial behavior formed by floating stallholders and other employed people is widespread in towns. Due to the characteristics of instability, flexibility and richness,informal commerce has gradually developed into an important business to attract residents and tourists. In this paper, the general characteristics of informal commercial behavior in towns, the characteristics of the urban public space bearing this kind of commerce, and residents' demand for informal commercial space were summarized, and then the optimization strategies of this kind of public space were put forward to help towns make full use of their scattered space, create diversified commercial places, and add vitality to urban space while providing residents and tourists with daily life needs and convenience.展开更多
1.Introduction In the past few decades,satellite technologies have advanced considerably,enabling seamless connectivity and wide coverage across the world.As a result,remote sensing now permits the collection of massi...1.Introduction In the past few decades,satellite technologies have advanced considerably,enabling seamless connectivity and wide coverage across the world.As a result,remote sensing now permits the collection of massive space information,which can be leveraged to support time-sensitive services and countermeasures to serious emergencies such as natural disasters[1,2].展开更多
A multi-path routing algorithm based on network coding is proposed for combating long propagation delay and high bit error rate of space information networks.On the basis of traditional multi-path routing,the algorith...A multi-path routing algorithm based on network coding is proposed for combating long propagation delay and high bit error rate of space information networks.On the basis of traditional multi-path routing,the algorithm uses a random linear network coding strategy to code data pack-ets.Code number is determined by the next hop link status and the number of current received packets sent by the upstream node together.The algorithm improves retransmission and cache mechanisms through using redundancy caused by network coding.Meanwhile,the algorithm also adopts the flow distribution strategy based on time delay to balance network load.Simulation results show that the proposed routing algorithm can effectively improve packet delivery rate,reduce packet delay,and enhance network performance.展开更多
It is a challenge to investigate the interrelationship between the geometric structure and performance of sensor networks due to the increasingly complex and diverse architecture of them.This paper presents two new fo...It is a challenge to investigate the interrelationship between the geometric structure and performance of sensor networks due to the increasingly complex and diverse architecture of them.This paper presents two new formulations for the information space of sensor networks,including Lagrangian and energy–momentum tensor,which are expected to integrate sensor networks target tracking and performance evaluation from a unified perspective.The proposed method presents two geometric objects to represent the dynamic state and manifold structure of the information space of sensor networks.Based on that,the authors conduct the property analysis and target tracking of sensor networks.To the best of our knowledge,it is the first time to investigate and analyze the information energy-momentum tensor of sensor networks and evaluate the performance of sensor networks in the context of target tracking.Simulations and examples confirm the competitive performance of the proposed method.展开更多
The features of information technology （IT） are discussed first. On this basis, the features of space information technology （SIT） are presented and SIT is elaborated in five categories. The popularization of SIT ...The features of information technology （IT） are discussed first. On this basis, the features of space information technology （SIT） are presented and SIT is elaborated in five categories. The popularization of SIT is an informatization process and will promote the industrialization of national economy and the modernization of industry such as agriculture. The necessity of the synthetical application of SIT is studied emphatically, and the development trend of SIT is discussed.展开更多
Frequent inter-satellite link(ISL)handovers will induce service interruption in large-scale space information networks,since traditional distributed/centralized routing strategy-based route convergence/update will con...Frequent inter-satellite link(ISL)handovers will induce service interruption in large-scale space information networks,since traditional distributed/centralized routing strategy-based route convergence/update will consume considerable time(compared with ground networks)derived from long ISL delay and flooding between hundreds or even thousands of satellites.During the network convergence/update stage,the lack of up-to-date forwarding information may cause severe packet loss.Considering the fact that ISL handovers for close-to-earth constellation are predictable and all the ISL handover information could be stored in each satellite during the network initialization,we propose a self-update routing scheme based on open shortest path first(OSPF-SUR)to address the slow route convergence problem caused by frequent ISL handovers.First,for predictable ISL handovers,forwarding tables are updated according to locally stored ISL handover information without link state advertisement(LSA)flooding.Second,for unexpected ISL failures,flooding could be triggered to complete route convergence.In this manner,network convergence time is radically descended by avoiding unnecessary LSA flooding for predictable ISL handovers.Simulation results show that the average packet loss rate caused by ISL handovers is reduced by 90.5%and 61.3%compared with standard OSPF(with three Hello packets confirmation)and OSPF based on interface state(without three Hello packets confirmation),respectively,during a period of topology handover.And the average endto-end delay is also decreased by 47.6%,9.6%,respectively.The packet loss rate of the proposed OSPF-SUR does not change along with the increase of the frequency of topology handovers.展开更多
Ongoing research is described that is focused upon modelling the space base information network and simulating its behaviours： simulation of spaced based communications and networking project. Its objective is to dem...Ongoing research is described that is focused upon modelling the space base information network and simulating its behaviours： simulation of spaced based communications and networking project. Its objective is to demonstrate the feasibility of producing a tool that can provide a performance evaluation of various eonstellation access techniques and routing policies. The architecture and design of the simulation system are explored. The algorithm of data routing and instrument scheduling in this project is described. Besides these, the key methodologies of simulating the inter-satellite link features in the data transmissions are also discussed. The performance of both instrument scheduling algorithm and routing schemes is evaluated and analyzed through extensive simulations under a typical scenario.展开更多
In this article,the phenomenon of“information space”and its methods of study,its types,elementary structure and qualitative characteristics are discussed,the author’s definition of the concept of“information”is g...In this article,the phenomenon of“information space”and its methods of study,its types,elementary structure and qualitative characteristics are discussed,the author’s definition of the concept of“information”is given,the structure of the information process,and the phases,which are the basis for the evolution of the information space and the universe of human activity,are considered.展开更多
A novel practical codebook-precoding multiple-input multiple-output（MIMO） system based on signal space diversity（SSD） with the minimum mean squared error（MMSE）receiver is proposed.This scheme utilizes rotation m...A novel practical codebook-precoding multiple-input multiple-output（MIMO） system based on signal space diversity（SSD） with the minimum mean squared error（MMSE）receiver is proposed.This scheme utilizes rotation modulation and space-time-frequency component interleaving.A novel precoding matrix selection criterion to maximize the average signal to interference plus noise ratio（SINR） is also put forward for the proposed scheme,which has a larger average mutual information（AMI）.Based on the AMI- maximization criterion,the optimal rotation angles for the proposed system are also investigated.The new scheme can make full use of space-time-frequency diversity and signal space diversity,and exhibit high spectral efficiency and high reliability in fading channels.Simulation results show that the proposed scheme greatly outperforms the conventional bit- interleaved coded modulation（BICM） MIMO-orthogonal frequency division multiplexing（OFDM） scheme without SSD,which is up to4.5 dB signal-to-noise ratio（SNR） gain.展开更多
(November 2009 Beijing, China) STUDY THE TECHNOLOGY OF SPACE INFORMATION EXPLORE THE FUTURE OF HUMAN KINDSponsored by China Academy of Space Technology (CAST) Co-sponsored by The Second Academy of China Aerospace Scie...(November 2009 Beijing, China) STUDY THE TECHNOLOGY OF SPACE INFORMATION EXPLORE THE FUTURE OF HUMAN KINDSponsored by China Academy of Space Technology (CAST) Co-sponsored by The Second Academy of China Aerospace Science and展开更多
Space information network is used for real time acquiring, transmitting and processing the space information on the space platform, which provides significant communication services for communication, navigation posit...Space information network is used for real time acquiring, transmitting and processing the space information on the space platform, which provides significant communication services for communication, navigation positioning and science exploration. In this paper, the architecture of Software Defined Space Optical Network (SDSON) based on cloud platform is designed by means of Software Defined Optical Network (SDON) and cloud services. The new architecture combining centralized and distributed management-control mechanism is a multi-layer and multi-domain architecture with powerful computing and storage ability. Moreover, reliable service and unreliable service communication models employed in the space information network are proposed considering the characteristic of Disruption/Delay Tolerant Network (DTN). Finally, the functional verification and demonstration are performed on our optical experimental network platform.展开更多
The identifiability of users as they interact in the digital world is fundamentally linked to privacy and security issues.Identifiability can be divided into two:subjective identifiability,which is based on psychologi...The identifiability of users as they interact in the digital world is fundamentally linked to privacy and security issues.Identifiability can be divided into two:subjective identifiability,which is based on psychological perceptions(i.e.,mental space),and objective identifiability,which is based on social media data(i.e.,information space).This study constructs a prediction model for social media data identifiability of users based on a supervised machine learning technique.The findings,based on data from Weibo,a Chinese social media platform,indicate that the top seven features and values for predicting social media identifiability include blog pictures(0.21),blog location(0.14),birthdate(0.12),location(0.10),blog interaction(0.10),school(0.08),and interests and hobbies(0.07).The relationship between machine-predicted and self-reported identifiability was tested using data from 91 participants.Based on the degree of deviation between the two,users can be divided into four categories—normal,conservative,active,and atypical—which reflect their sensitivity to privacy concerns and preferences regarding information disclosure.This study provides insights into the development of privacy protection strategies based on social media data classification.展开更多
With the rapid advancement of satellite communication technologies,space information networks(SINs)have become essential infrastructure for complex service delivery and cross-domain task coordination,facilitating the ...With the rapid advancement of satellite communication technologies,space information networks(SINs)have become essential infrastructure for complex service delivery and cross-domain task coordination,facilitating the transition toward an intent-driven task-oriented coordination paradigm across the space,ground,and user segments.This study presents a novel intent-driven task-oriented network(IDTN)framework to address task scheduling and resource allocation challenges in SINs.The scheduling problem is formulated as a three-sided matching game that incorporates the preference attributes of entities across all network segments.To manage the variability of random task arrivals and dynamic resources,a context-aware linear upper-confidence-bound online learning mechanism is integrated to reduce decision-making uncertainty.Simulation results demonstrate the effectiveness of the proposed IDTN framework.Compared with conventional baseline methods,the framework achieves significant performance improvements,including a 4.4%-28.9%increase in average system reward,a 6.2%-34.5%improvement in resource utilization,and a 5.6%-35.7%enhancement in user satisfaction.The proposed framework is expected to facilitate the integration and orchestration of space-based platforms.展开更多
A key objective of the Outline on the Development of Chinese Children(2021–2030)is to establish child-friendly cities and communities.Clarifying the characteristics of informal children's activity spaces and unde...A key objective of the Outline on the Development of Chinese Children(2021–2030)is to establish child-friendly cities and communities.Clarifying the characteristics of informal children's activity spaces and understanding their preferences can help stakeholders in promoting child-friendly community development.This study,based on a review of existing domestic and international literature as well as field research,employs quantitative indicators to refine the concept of informal children's activity spaces,ensuring its suitability for the Chinese context.These spaces are categorized into five types:street space,street-side open space,space near the residential complex entrance,pocket park,and square.Using questionnaire surveys and factor analysis,the study develops an evaluation system for assessing the child-friendliness of informal activity spaces across six dimensions:usability,interest,educational feature,natural design,safety,and environmental comfort.This system is then applied to the informal activity spaces in Chengdu.The findings reveal two key characteristics:(1)high accessibility and safety standards in existing designs and(2)a lack of play facilities for children and educational elements.Based on these results,the study proposes general strategies for the improvement of informal children's activity spaces in communities.Additionally,it identifies priority factors for different types of spaces,providing a scientific foundation for enhancing the quality of outdoor community environments and fostering children's the healthy development.展开更多
The paper is devoted to the problem of the development of information technologies in Sub-Saharan countries. The author comes to a conclusion that the up-to-date level of the development of information technologies in...The paper is devoted to the problem of the development of information technologies in Sub-Saharan countries. The author comes to a conclusion that the up-to-date level of the development of information technologies in Sub-Saharan countries doesn＇t give us an opportunity to estimate the close equal integration of the region into the global information and communication space. African countries don＇t have appropriate financial and technological resources which seem to be necessary when creating the well-developed information and telecommunication infrastructure on their territory. The author argues that in order to reach the level of the development of well-developed nations African states are forced to seek the aid of Western countries which use the technological and financial dependence of their African partners as the strong instrument of preservation of their influence in the region. In current circumstances it would be very difficult for Afxican countries to create a self-reliant information society and to preserve their cultural identity in the upcoming information age.展开更多
This paper discusses the mathematical description of hybrid event systems, consisting of continuous, discrete, even logic-judgment and inference-decision event systems. The description takes events as its core, and in...This paper discusses the mathematical description of hybrid event systems, consisting of continuous, discrete, even logic-judgment and inference-decision event systems. The description takes events as its core, and information interconnection as its tie. In this paper, an event, instead of a process, is regarded as an analyzed element. The hybrid event systems are described in mathematical models with the following tools: chains of time, generalized space and interconnecting information.展开更多
To clarify the concept framework to assess web based information systems (WIS) evolution from an information perspective instead of the usual systems perspective, and to seek for in-depth understanding of maturing pat...To clarify the concept framework to assess web based information systems (WIS) evolution from an information perspective instead of the usual systems perspective, and to seek for in-depth understanding of maturing patterns of WISs based on the framework, several central concepts related to the information aspect of WIS are firstly discussed, then a growth model of local government websites based on a survey study is proposed.展开更多
Focusing on its main requirements and challenges and by analyzing the characteristics of different space platforms,an overall architecture for space information networks is proposed based on national strategic plannin...Focusing on its main requirements and challenges and by analyzing the characteristics of different space platforms,an overall architecture for space information networks is proposed based on national strategic planning and the present development status of associated technologies.Furthermore,the core scientific problems that need to be solved are expounded.In addition,the primary considerations and a preliminary integrated demonstration environment for verification of key technologies are presented.展开更多
The scale expansion of the space information networks(SINs)makes the demands for tacking,telemetry and command(TT&C)missions increase dramatically.An increasing number of missions and a sharp conflict of resources...The scale expansion of the space information networks(SINs)makes the demands for tacking,telemetry and command(TT&C)missions increase dramatically.An increasing number of missions and a sharp conflict of resources make it much more challenging to schedule missions reasonably.In order to ensure both the mission completion rate of the high concurrent emergency missions and the performance of regular missions,a conflict degree scheduling algorithm based on transfer strategy(CDSA-TS)is proposed concurrently reconfiguring multi-dimensional resources reasonably.Furthermore,we design an emergency mission planning algorithm based on simulated annealing algorithm(EMPA-SA)to increase the probability of jumping out of the trap through the iterative neighborhood searching strategy and destabilization.Finally,we design a simulation system to verify the network performance in terms of the integrated weights of completed missions and the time consumption of the proposed algorithms.We also investigate the impact of the scheduling strategy for emergency missions on regular missions to improve the overall network performance,which provides guidance for emergency mission planning in the future for the large scale constellation oriented SINs.展开更多
基金Supported by National Natural Science Foundation of China (51768026)Humanities and Social Sciences Project of Colleges and Universities in Jiangxi Province,China (YC2021-S225)。
文摘Commercial behavior in towns and cities is mainly divided into formal and informal behavior.Rapid urbanization has enabled formal commerce to develop more and more perfectly in towns,basically meeting the living needs of residents. However, because of problems such as urban history and management mechanism, informal commercial behavior formed by floating stallholders and other employed people is widespread in towns. Due to the characteristics of instability, flexibility and richness,informal commerce has gradually developed into an important business to attract residents and tourists. In this paper, the general characteristics of informal commercial behavior in towns, the characteristics of the urban public space bearing this kind of commerce, and residents' demand for informal commercial space were summarized, and then the optimization strategies of this kind of public space were put forward to help towns make full use of their scattered space, create diversified commercial places, and add vitality to urban space while providing residents and tourists with daily life needs and convenience.
文摘1.Introduction In the past few decades,satellite technologies have advanced considerably,enabling seamless connectivity and wide coverage across the world.As a result,remote sensing now permits the collection of massive space information,which can be leveraged to support time-sensitive services and countermeasures to serious emergencies such as natural disasters[1,2].
基金supported by the National Natural Science Foundation of China(No.60929003)
文摘A multi-path routing algorithm based on network coding is proposed for combating long propagation delay and high bit error rate of space information networks.On the basis of traditional multi-path routing,the algorithm uses a random linear network coding strategy to code data pack-ets.Code number is determined by the next hop link status and the number of current received packets sent by the upstream node together.The algorithm improves retransmission and cache mechanisms through using redundancy caused by network coding.Meanwhile,the algorithm also adopts the flow distribution strategy based on time delay to balance network load.Simulation results show that the proposed routing algorithm can effectively improve packet delivery rate,reduce packet delay,and enhance network performance.
基金supported by the National Natural Science Foundation of China(No.51875014)。
文摘It is a challenge to investigate the interrelationship between the geometric structure and performance of sensor networks due to the increasingly complex and diverse architecture of them.This paper presents two new formulations for the information space of sensor networks,including Lagrangian and energy–momentum tensor,which are expected to integrate sensor networks target tracking and performance evaluation from a unified perspective.The proposed method presents two geometric objects to represent the dynamic state and manifold structure of the information space of sensor networks.Based on that,the authors conduct the property analysis and target tracking of sensor networks.To the best of our knowledge,it is the first time to investigate and analyze the information energy-momentum tensor of sensor networks and evaluate the performance of sensor networks in the context of target tracking.Simulations and examples confirm the competitive performance of the proposed method.
文摘The features of information technology （IT） are discussed first. On this basis, the features of space information technology （SIT） are presented and SIT is elaborated in five categories. The popularization of SIT is an informatization process and will promote the industrialization of national economy and the modernization of industry such as agriculture. The necessity of the synthetical application of SIT is studied emphatically, and the development trend of SIT is discussed.
基金the National Natural Science Foundations of China(Nos.61771074,62171059)。
文摘Frequent inter-satellite link(ISL)handovers will induce service interruption in large-scale space information networks,since traditional distributed/centralized routing strategy-based route convergence/update will consume considerable time(compared with ground networks)derived from long ISL delay and flooding between hundreds or even thousands of satellites.During the network convergence/update stage,the lack of up-to-date forwarding information may cause severe packet loss.Considering the fact that ISL handovers for close-to-earth constellation are predictable and all the ISL handover information could be stored in each satellite during the network initialization,we propose a self-update routing scheme based on open shortest path first(OSPF-SUR)to address the slow route convergence problem caused by frequent ISL handovers.First,for predictable ISL handovers,forwarding tables are updated according to locally stored ISL handover information without link state advertisement(LSA)flooding.Second,for unexpected ISL failures,flooding could be triggered to complete route convergence.In this manner,network convergence time is radically descended by avoiding unnecessary LSA flooding for predictable ISL handovers.Simulation results show that the average packet loss rate caused by ISL handovers is reduced by 90.5%and 61.3%compared with standard OSPF(with three Hello packets confirmation)and OSPF based on interface state(without three Hello packets confirmation),respectively,during a period of topology handover.And the average endto-end delay is also decreased by 47.6%,9.6%,respectively.The packet loss rate of the proposed OSPF-SUR does not change along with the increase of the frequency of topology handovers.
基金This project was supported by the National "863" High-Tech Research and Development Program of China(2002AA7170)
文摘Ongoing research is described that is focused upon modelling the space base information network and simulating its behaviours： simulation of spaced based communications and networking project. Its objective is to demonstrate the feasibility of producing a tool that can provide a performance evaluation of various eonstellation access techniques and routing policies. The architecture and design of the simulation system are explored. The algorithm of data routing and instrument scheduling in this project is described. Besides these, the key methodologies of simulating the inter-satellite link features in the data transmissions are also discussed. The performance of both instrument scheduling algorithm and routing schemes is evaluated and analyzed through extensive simulations under a typical scenario.
文摘In this article,the phenomenon of“information space”and its methods of study,its types,elementary structure and qualitative characteristics are discussed,the author’s definition of the concept of“information”is given,the structure of the information process,and the phases,which are the basis for the evolution of the information space and the universe of human activity,are considered.
基金supported by the National Natural Science Foundation of China(61171101)the Fundamental Research Funds for the Central Universitiesthe 2014 Doctorial Innovation Fund of Beijing University of Posts and Telecommunications(CX201426)
文摘A novel practical codebook-precoding multiple-input multiple-output（MIMO） system based on signal space diversity（SSD） with the minimum mean squared error（MMSE）receiver is proposed.This scheme utilizes rotation modulation and space-time-frequency component interleaving.A novel precoding matrix selection criterion to maximize the average signal to interference plus noise ratio（SINR） is also put forward for the proposed scheme,which has a larger average mutual information（AMI）.Based on the AMI- maximization criterion,the optimal rotation angles for the proposed system are also investigated.The new scheme can make full use of space-time-frequency diversity and signal space diversity,and exhibit high spectral efficiency and high reliability in fading channels.Simulation results show that the proposed scheme greatly outperforms the conventional bit- interleaved coded modulation（BICM） MIMO-orthogonal frequency division multiplexing（OFDM） scheme without SSD,which is up to4.5 dB signal-to-noise ratio（SNR） gain.
文摘(November 2009 Beijing, China) STUDY THE TECHNOLOGY OF SPACE INFORMATION EXPLORE THE FUTURE OF HUMAN KINDSponsored by China Academy of Space Technology (CAST) Co-sponsored by The Second Academy of China Aerospace Science and
文摘Space information network is used for real time acquiring, transmitting and processing the space information on the space platform, which provides significant communication services for communication, navigation positioning and science exploration. In this paper, the architecture of Software Defined Space Optical Network (SDSON) based on cloud platform is designed by means of Software Defined Optical Network (SDON) and cloud services. The new architecture combining centralized and distributed management-control mechanism is a multi-layer and multi-domain architecture with powerful computing and storage ability. Moreover, reliable service and unreliable service communication models employed in the space information network are proposed considering the characteristic of Disruption/Delay Tolerant Network (DTN). Finally, the functional verification and demonstration are performed on our optical experimental network platform.
基金supported by the National Social Science Funds of China(Grant No.21BSH050)Major Project of National Social Science Funds of China(Grant No.20&ZD013).
文摘The identifiability of users as they interact in the digital world is fundamentally linked to privacy and security issues.Identifiability can be divided into two:subjective identifiability,which is based on psychological perceptions(i.e.,mental space),and objective identifiability,which is based on social media data(i.e.,information space).This study constructs a prediction model for social media data identifiability of users based on a supervised machine learning technique.The findings,based on data from Weibo,a Chinese social media platform,indicate that the top seven features and values for predicting social media identifiability include blog pictures(0.21),blog location(0.14),birthdate(0.12),location(0.10),blog interaction(0.10),school(0.08),and interests and hobbies(0.07).The relationship between machine-predicted and self-reported identifiability was tested using data from 91 participants.Based on the degree of deviation between the two,users can be divided into four categories—normal,conservative,active,and atypical—which reflect their sensitivity to privacy concerns and preferences regarding information disclosure.This study provides insights into the development of privacy protection strategies based on social media data classification.
基金supported by the National Key Research and Development Program of China(2020YFB1807700)Innovation Capability Support Program of Shaanxi(2024RS-CXTD-01).
文摘With the rapid advancement of satellite communication technologies,space information networks(SINs)have become essential infrastructure for complex service delivery and cross-domain task coordination,facilitating the transition toward an intent-driven task-oriented coordination paradigm across the space,ground,and user segments.This study presents a novel intent-driven task-oriented network(IDTN)framework to address task scheduling and resource allocation challenges in SINs.The scheduling problem is formulated as a three-sided matching game that incorporates the preference attributes of entities across all network segments.To manage the variability of random task arrivals and dynamic resources,a context-aware linear upper-confidence-bound online learning mechanism is integrated to reduce decision-making uncertainty.Simulation results demonstrate the effectiveness of the proposed IDTN framework.Compared with conventional baseline methods,the framework achieves significant performance improvements,including a 4.4%-28.9%increase in average system reward,a 6.2%-34.5%improvement in resource utilization,and a 5.6%-35.7%enhancement in user satisfaction.The proposed framework is expected to facilitate the integration and orchestration of space-based platforms.
基金funded by the Youth Science Fund of the National Natural Science Foundation of China(Project No.51708370)。
文摘A key objective of the Outline on the Development of Chinese Children(2021–2030)is to establish child-friendly cities and communities.Clarifying the characteristics of informal children's activity spaces and understanding their preferences can help stakeholders in promoting child-friendly community development.This study,based on a review of existing domestic and international literature as well as field research,employs quantitative indicators to refine the concept of informal children's activity spaces,ensuring its suitability for the Chinese context.These spaces are categorized into five types:street space,street-side open space,space near the residential complex entrance,pocket park,and square.Using questionnaire surveys and factor analysis,the study develops an evaluation system for assessing the child-friendliness of informal activity spaces across six dimensions:usability,interest,educational feature,natural design,safety,and environmental comfort.This system is then applied to the informal activity spaces in Chengdu.The findings reveal two key characteristics:(1)high accessibility and safety standards in existing designs and(2)a lack of play facilities for children and educational elements.Based on these results,the study proposes general strategies for the improvement of informal children's activity spaces in communities.Additionally,it identifies priority factors for different types of spaces,providing a scientific foundation for enhancing the quality of outdoor community environments and fostering children's the healthy development.
文摘The paper is devoted to the problem of the development of information technologies in Sub-Saharan countries. The author comes to a conclusion that the up-to-date level of the development of information technologies in Sub-Saharan countries doesn＇t give us an opportunity to estimate the close equal integration of the region into the global information and communication space. African countries don＇t have appropriate financial and technological resources which seem to be necessary when creating the well-developed information and telecommunication infrastructure on their territory. The author argues that in order to reach the level of the development of well-developed nations African states are forced to seek the aid of Western countries which use the technological and financial dependence of their African partners as the strong instrument of preservation of their influence in the region. In current circumstances it would be very difficult for Afxican countries to create a self-reliant information society and to preserve their cultural identity in the upcoming information age.
文摘This paper discusses the mathematical description of hybrid event systems, consisting of continuous, discrete, even logic-judgment and inference-decision event systems. The description takes events as its core, and information interconnection as its tie. In this paper, an event, instead of a process, is regarded as an analyzed element. The hybrid event systems are described in mathematical models with the following tools: chains of time, generalized space and interconnecting information.
文摘To clarify the concept framework to assess web based information systems (WIS) evolution from an information perspective instead of the usual systems perspective, and to seek for in-depth understanding of maturing patterns of WISs based on the framework, several central concepts related to the information aspect of WIS are firstly discussed, then a growth model of local government websites based on a survey study is proposed.
基金supported by the National Natural Science Foundation of China(Nos.61231011,61671478)。
文摘Focusing on its main requirements and challenges and by analyzing the characteristics of different space platforms,an overall architecture for space information networks is proposed based on national strategic planning and the present development status of associated technologies.Furthermore,the core scientific problems that need to be solved are expounded.In addition,the primary considerations and a preliminary integrated demonstration environment for verification of key technologies are presented.
基金the Natural Science Foundation of China under Grant U19B2025 and Grant 62001347China Postdoctoral Science Foundation under Grant 2019TQ0241 and Grant 2020M673344the Fundamental Research Funds for the Central Universities under Grant XJS200117。
文摘The scale expansion of the space information networks(SINs)makes the demands for tacking,telemetry and command(TT&C)missions increase dramatically.An increasing number of missions and a sharp conflict of resources make it much more challenging to schedule missions reasonably.In order to ensure both the mission completion rate of the high concurrent emergency missions and the performance of regular missions,a conflict degree scheduling algorithm based on transfer strategy(CDSA-TS)is proposed concurrently reconfiguring multi-dimensional resources reasonably.Furthermore,we design an emergency mission planning algorithm based on simulated annealing algorithm(EMPA-SA)to increase the probability of jumping out of the trap through the iterative neighborhood searching strategy and destabilization.Finally,we design a simulation system to verify the network performance in terms of the integrated weights of completed missions and the time consumption of the proposed algorithms.We also investigate the impact of the scheduling strategy for emergency missions on regular missions to improve the overall network performance,which provides guidance for emergency mission planning in the future for the large scale constellation oriented SINs.
