Rapid and timely testing is essential to minimize the COVID-19 spread. Decision makers and policy planners need to determine the equal distribution and accessibility of testing sites. This study mainly examines the sp...Rapid and timely testing is essential to minimize the COVID-19 spread. Decision makers and policy planners need to determine the equal distribution and accessibility of testing sites. This study mainly examines the spatial equality of COVID-19 testing sites that maintain a zero COVID policy in Guangzhou City. The study has identified the spatial disparities of COVID testing sites, characteristics of testing locations, and accessibility. The study has obtained information on COVID testing sites in Guangzhou City and population data. Point pattern analyses, Euclidian distance and allocation, and network analyses are the main methods used to achieve the research objectives, and 1183 total COVID testing sites can be recognized in Guangzhou City. Results revealed that spatial disparities could be noticed over the study area. Testing locations of Guangzhou City are highly clustered. The most significant testing sites are located in Haizhu District, which has the third largest population. The highest population density can be identified in Yuexiu District. However, only 94 testing sites are located there. According to all the results, higher disparities can be identified, and a lack of testing sites is located in the north part of the study area. Some people in the northern part have to travel more than 10 km to reach a testing site. Finally, this paper suggests increasing the number of testing sites in the north and south parts of the study area and keeping the same distribution, considering the area, total population, and population density. This kind of research will be helpful to decision-makers in making proper decisions to maintain a zero COVID policy.展开更多
In recent times, there has been growing interests in integration of voice, data and video traffic in wireless communication networks. With these growing interests, WCDMA has immerged as an attractive access technique....In recent times, there has been growing interests in integration of voice, data and video traffic in wireless communication networks. With these growing interests, WCDMA has immerged as an attractive access technique. The performance of WCDMA system is deteriorated in presence of multipath fading environment. The paper presents space-time coded minimum mean square error (MMSE) Decision Feedback Equalizer (DFE) for wideband code division multiple access (WCDMA) in a frequency selective channel. The filter coefficients in MMSE DFE are optimized to suppress noise, intersymbol interference (ISI), and multiple access interference (MAI) with reasonable system complexity. For the above structure, we have presented the estimation of BER for a MMSE DFE using computer simulation experiments. The simulation includes the effects of additive white Gaussian noise, multipath fading and multiple access interference (MAI). Furthermore, the performance is compared with standard linear equalizer (LE) and RAKE receiver. Numerical and simulation results show that the MMSE DFE exhibits significant performance improvement over the standard linear equalizer (LE) and RAKE receiver.展开更多
Direct-sequence code-division multiple access (CDMA) is considered for multiuser communication network in underwater acoustic channel, where extended multipath and rapid time-variability are encountered. To track and ...Direct-sequence code-division multiple access (CDMA) is considered for multiuser communication network in underwater acoustic channel, where extended multipath and rapid time-variability are encountered. To track and compensate the channel distortion, a decentralized hypothesis-feedback equalization (HFE) algorithm based on chip-rate update has been used[1]. But due to multiple access interference (MAI), its performance suffers degradation. For this reason, successive interference cancellation hypothesis-feedback equalization (SIC-HFE) algorithm is proposed, which combines the capabilities of HFE to track the time-varying channel and SIC implemented by cross-over feedback filters to cancel out the MAI effects between users. Simulation and experiment results show that the proposed algorithm can significantly improve the performance of asynchronous multiuser CDMA underwater communication system.展开更多
[目的/意义]信息无障碍旨在让任何人都能平等、方便、安全地获取、交互、使用信息,实现信息无障碍对公共文化服务均等化的推进具有重要意义。本文的目的是揭示该领域的研究进展和发展方向。[研究设计/方法]结合马斯洛需求层次理论,从生...[目的/意义]信息无障碍旨在让任何人都能平等、方便、安全地获取、交互、使用信息,实现信息无障碍对公共文化服务均等化的推进具有重要意义。本文的目的是揭示该领域的研究进展和发展方向。[研究设计/方法]结合马斯洛需求层次理论,从生理和安全需求、归属与爱的需求以及尊重与自我实现的需求方面探讨信息无障碍的演化历程,检索了2012年12月31日-2022年12月31日期间CNKI数据库和Web of Science数据库中的相关文献,应用可视化工具进行关键词共现分析,从社会发展视角、城市建设视角、技术标准视角以及应用场景视角讨论信息无障碍领域的研究热点,探索其未来发展方向。[结论/发现]目前信息无障碍的研究体系已初步构建,相关研究也趋于多元化。虽然现有研究仍存在一些暂未关注的问题,但以人工智能、产品供给、虚拟形态为驱动,以人文精神为纽带来推动公共文化服务均等化,可以加快理想化的信息无障碍目标的实现。[创新/价值]结合马斯洛需求层次理论梳理了信息无障碍研究的演进历程,总结归纳出近十年的研究热点,并对信息无障碍的发展进行展望。展开更多
文摘Rapid and timely testing is essential to minimize the COVID-19 spread. Decision makers and policy planners need to determine the equal distribution and accessibility of testing sites. This study mainly examines the spatial equality of COVID-19 testing sites that maintain a zero COVID policy in Guangzhou City. The study has identified the spatial disparities of COVID testing sites, characteristics of testing locations, and accessibility. The study has obtained information on COVID testing sites in Guangzhou City and population data. Point pattern analyses, Euclidian distance and allocation, and network analyses are the main methods used to achieve the research objectives, and 1183 total COVID testing sites can be recognized in Guangzhou City. Results revealed that spatial disparities could be noticed over the study area. Testing locations of Guangzhou City are highly clustered. The most significant testing sites are located in Haizhu District, which has the third largest population. The highest population density can be identified in Yuexiu District. However, only 94 testing sites are located there. According to all the results, higher disparities can be identified, and a lack of testing sites is located in the north part of the study area. Some people in the northern part have to travel more than 10 km to reach a testing site. Finally, this paper suggests increasing the number of testing sites in the north and south parts of the study area and keeping the same distribution, considering the area, total population, and population density. This kind of research will be helpful to decision-makers in making proper decisions to maintain a zero COVID policy.
文摘In recent times, there has been growing interests in integration of voice, data and video traffic in wireless communication networks. With these growing interests, WCDMA has immerged as an attractive access technique. The performance of WCDMA system is deteriorated in presence of multipath fading environment. The paper presents space-time coded minimum mean square error (MMSE) Decision Feedback Equalizer (DFE) for wideband code division multiple access (WCDMA) in a frequency selective channel. The filter coefficients in MMSE DFE are optimized to suppress noise, intersymbol interference (ISI), and multiple access interference (MAI) with reasonable system complexity. For the above structure, we have presented the estimation of BER for a MMSE DFE using computer simulation experiments. The simulation includes the effects of additive white Gaussian noise, multipath fading and multiple access interference (MAI). Furthermore, the performance is compared with standard linear equalizer (LE) and RAKE receiver. Numerical and simulation results show that the MMSE DFE exhibits significant performance improvement over the standard linear equalizer (LE) and RAKE receiver.
基金National Natural Science Foundation of China (60572098)
文摘Direct-sequence code-division multiple access (CDMA) is considered for multiuser communication network in underwater acoustic channel, where extended multipath and rapid time-variability are encountered. To track and compensate the channel distortion, a decentralized hypothesis-feedback equalization (HFE) algorithm based on chip-rate update has been used[1]. But due to multiple access interference (MAI), its performance suffers degradation. For this reason, successive interference cancellation hypothesis-feedback equalization (SIC-HFE) algorithm is proposed, which combines the capabilities of HFE to track the time-varying channel and SIC implemented by cross-over feedback filters to cancel out the MAI effects between users. Simulation and experiment results show that the proposed algorithm can significantly improve the performance of asynchronous multiuser CDMA underwater communication system.
文摘[目的/意义]信息无障碍旨在让任何人都能平等、方便、安全地获取、交互、使用信息,实现信息无障碍对公共文化服务均等化的推进具有重要意义。本文的目的是揭示该领域的研究进展和发展方向。[研究设计/方法]结合马斯洛需求层次理论,从生理和安全需求、归属与爱的需求以及尊重与自我实现的需求方面探讨信息无障碍的演化历程,检索了2012年12月31日-2022年12月31日期间CNKI数据库和Web of Science数据库中的相关文献,应用可视化工具进行关键词共现分析,从社会发展视角、城市建设视角、技术标准视角以及应用场景视角讨论信息无障碍领域的研究热点,探索其未来发展方向。[结论/发现]目前信息无障碍的研究体系已初步构建,相关研究也趋于多元化。虽然现有研究仍存在一些暂未关注的问题,但以人工智能、产品供给、虚拟形态为驱动,以人文精神为纽带来推动公共文化服务均等化,可以加快理想化的信息无障碍目标的实现。[创新/价值]结合马斯洛需求层次理论梳理了信息无障碍研究的演进历程,总结归纳出近十年的研究热点,并对信息无障碍的发展进行展望。
