通过对中波频段的特性分析,提出一种创新的中波应急广播覆盖网构建方案。基于信号传播理论和通信工程原理,结合地理信息系统(Geographic Information System,GIS)技术,优化中波发射台布局,提高应急广播信号的覆盖范围和稳定性。采用先...通过对中波频段的特性分析,提出一种创新的中波应急广播覆盖网构建方案。基于信号传播理论和通信工程原理,结合地理信息系统(Geographic Information System,GIS)技术,优化中波发射台布局,提高应急广播信号的覆盖范围和稳定性。采用先进的调制解调技术和功率控制策略,有效克服信道传播中的多径效应和信号衰减,提升应急广播系统的抗干扰性。通过在不同地理环境下的仿真实验,验证所提出构建方案的可行性和效果,为中波应急广播系统的建设提供有力的技术支持,为应对突发事件提供可靠的通信保障。展开更多
Cadastral Information System (CIS) is designed for the office automation of cadastral management. With the development of the market economics in China, cadastral management is facing many new problems. The most cruci...Cadastral Information System (CIS) is designed for the office automation of cadastral management. With the development of the market economics in China, cadastral management is facing many new problems. The most crucial one is the temporal problem in cadastral management. That is, CIS must consider both spatial data and temporal data. This paper reviews the situation of the current CIS and provides a method to manage the spatiotemporal data of CIS, and takes the CIS for Guangdong Province as an example to explain how to realize it in practice.展开更多
Purpose： This article reports on an experiment that tested community members＇ collaborative information seeking （CIS） behavior, with an emphasis on how community type and task difficulty can affect user behavior a...Purpose： This article reports on an experiment that tested community members＇ collaborative information seeking （CIS） behavior, with an emphasis on how community type and task difficulty can affect user behavior and user awareness in collaboration.Design/methodology/approach： We carried out a laboratory study with 18 participants in 9 pairs using an experimental CIS system. Data were collected from questionnaires, Web logs and semi-structured interviews. Descriptive statistics and two-way analysis of variance （ANOVA） were used for data analysis. Findings： Compared with non-community members, community participants had a better understanding of search tasks and were aware of the ways of completing tasks successfully. They did not depend on the information retrieval system when constructing search queries and would adopt diversified cooperation strategies. They were more likely to recommend information to their partners. However, no significant difference was found between subject- based community and interest-based community in CIS practices and user awareness in collaboration. In addition, task difficulty only influenced user preference of issuing queries and confidence of completing search tasks. Research limitations： Our work was limited by the community type we chose and the small group size, which could affect the generalizability of our findings and should be addressed in future studies. Practical implications： The study results will help inform information system designers as they design collaborative systems to facilitate social communication in the information seeking process. Originality/value： Few studies have investigated community participants＇ information seeking practices. This study provides insights into community-based CIS behavior. The findings will help us understand social interactions among community members during their information seeking process.展开更多
以计算机联锁系统(Computer Based Interlocking,CI)为研究对象,分析了CI系统的通信板、控显及维护机存在的信息安全问题。研究结果表明CI系统存在漏洞被利用的风险,也为基于通信的列车控制系统(Communications Based Train Control,CB...以计算机联锁系统(Computer Based Interlocking,CI)为研究对象,分析了CI系统的通信板、控显及维护机存在的信息安全问题。研究结果表明CI系统存在漏洞被利用的风险,也为基于通信的列车控制系统(Communications Based Train Control,CBTC)信号系统信息安全防护提供了思路。展开更多
文摘通过对中波频段的特性分析,提出一种创新的中波应急广播覆盖网构建方案。基于信号传播理论和通信工程原理,结合地理信息系统(Geographic Information System,GIS)技术,优化中波发射台布局,提高应急广播信号的覆盖范围和稳定性。采用先进的调制解调技术和功率控制策略,有效克服信道传播中的多径效应和信号衰减,提升应急广播系统的抗干扰性。通过在不同地理环境下的仿真实验,验证所提出构建方案的可行性和效果,为中波应急广播系统的建设提供有力的技术支持,为应对突发事件提供可靠的通信保障。
文摘Cadastral Information System (CIS) is designed for the office automation of cadastral management. With the development of the market economics in China, cadastral management is facing many new problems. The most crucial one is the temporal problem in cadastral management. That is, CIS must consider both spatial data and temporal data. This paper reviews the situation of the current CIS and provides a method to manage the spatiotemporal data of CIS, and takes the CIS for Guangdong Province as an example to explain how to realize it in practice.
基金supported by the National Program for Support of Top-notch Young Professionals
文摘Purpose： This article reports on an experiment that tested community members＇ collaborative information seeking （CIS） behavior, with an emphasis on how community type and task difficulty can affect user behavior and user awareness in collaboration.Design/methodology/approach： We carried out a laboratory study with 18 participants in 9 pairs using an experimental CIS system. Data were collected from questionnaires, Web logs and semi-structured interviews. Descriptive statistics and two-way analysis of variance （ANOVA） were used for data analysis. Findings： Compared with non-community members, community participants had a better understanding of search tasks and were aware of the ways of completing tasks successfully. They did not depend on the information retrieval system when constructing search queries and would adopt diversified cooperation strategies. They were more likely to recommend information to their partners. However, no significant difference was found between subject- based community and interest-based community in CIS practices and user awareness in collaboration. In addition, task difficulty only influenced user preference of issuing queries and confidence of completing search tasks. Research limitations： Our work was limited by the community type we chose and the small group size, which could affect the generalizability of our findings and should be addressed in future studies. Practical implications： The study results will help inform information system designers as they design collaborative systems to facilitate social communication in the information seeking process. Originality/value： Few studies have investigated community participants＇ information seeking practices. This study provides insights into community-based CIS behavior. The findings will help us understand social interactions among community members during their information seeking process.
文摘以计算机联锁系统(Computer Based Interlocking,CI)为研究对象,分析了CI系统的通信板、控显及维护机存在的信息安全问题。研究结果表明CI系统存在漏洞被利用的风险,也为基于通信的列车控制系统(Communications Based Train Control,CBTC)信号系统信息安全防护提供了思路。
