Extremely large-scale multiple-input multiple-output(XL-MIMO)and terahertz(THz)communications are pivotal candidate technologies for supporting the development of 6G mobile networks.However,these techniques invalidate...Extremely large-scale multiple-input multiple-output(XL-MIMO)and terahertz(THz)communications are pivotal candidate technologies for supporting the development of 6G mobile networks.However,these techniques invalidate the common assumptions of far-field plane waves and introduce many new properties.To accurately understand the performance of these new techniques,spherical wave modeling of near-field communications needs to be applied for future research.Hence,the investigation of near-field communication holds significant importance for the advancement of 6G,which brings many new and open research challenges in contrast to conventional far-field communication.In this paper,we first formulate a general model of the near-field channel and discuss the influence of spatial nonstationary properties on the near-field channel modeling.Subsequently,we discuss the challenges encountered in the near field in terms of beam training,localization,and transmission scheme design,respectively.Finally,we point out some promising research directions for near-field communications.展开更多
目的探索性构建一个科学的中医药国际标准实施效果评价指标体系以指导标准实施效果评价工作。方法通过文献分析、专家访谈等方法建立中医药国际标准实施效果评价指标框架,并开展2轮德尔菲问卷,收集专家对各指标的重要性评分及修改意见,...目的探索性构建一个科学的中医药国际标准实施效果评价指标体系以指导标准实施效果评价工作。方法通过文献分析、专家访谈等方法建立中医药国际标准实施效果评价指标框架,并开展2轮德尔菲问卷,收集专家对各指标的重要性评分及修改意见,统计分析专家的基本信息和问卷结果,包括专家积极系数、肯德尔和谐系数以及指标评分均数、满分比、变异系数等。结果专家的遴选体现了较高权威性,2轮德尔菲问卷回收率为76.47%和100%,专家权威系数均高于0.7,Kendall s W分别为0.271、0.308,专家意见总体协调性较好。“技术创新”指标均数<3.5且满分比7.69%予以删除;根据专家意见,增加“可操作性”“技术成熟度”三级指标,对“标准转化应用”“与相关政策规范协调”“提高效率”“能源消耗”“市场需求”等指标进行相应调整。结论初步构建了包含3个一级指标9个二级指标和27个三级指标的中医药国际标准实施效果评价指标体系,从标准技术水平、实施情况和实施效益3个维度体现了标准实施效果评价环节的全面性,为开展中医药国际标准实施效果评价研究提供了指导与参考。展开更多
基金supported in part by National Key Research and Develop⁃ment Young Scientist Project 2023YFB2905100the National Natural Sci⁃ence Foundation of China under Grant Nos.62201137 and 62331023+1 种基金the Fundamental Research Funds for the Central Universities under Grant No.2242022k60001the Research Fund of National Mobile Communications Research Laboratory,Southeast University,China under Grant No.2023A03.
文摘Extremely large-scale multiple-input multiple-output(XL-MIMO)and terahertz(THz)communications are pivotal candidate technologies for supporting the development of 6G mobile networks.However,these techniques invalidate the common assumptions of far-field plane waves and introduce many new properties.To accurately understand the performance of these new techniques,spherical wave modeling of near-field communications needs to be applied for future research.Hence,the investigation of near-field communication holds significant importance for the advancement of 6G,which brings many new and open research challenges in contrast to conventional far-field communication.In this paper,we first formulate a general model of the near-field channel and discuss the influence of spatial nonstationary properties on the near-field channel modeling.Subsequently,we discuss the challenges encountered in the near field in terms of beam training,localization,and transmission scheme design,respectively.Finally,we point out some promising research directions for near-field communications.
文摘目的探索性构建一个科学的中医药国际标准实施效果评价指标体系以指导标准实施效果评价工作。方法通过文献分析、专家访谈等方法建立中医药国际标准实施效果评价指标框架,并开展2轮德尔菲问卷,收集专家对各指标的重要性评分及修改意见,统计分析专家的基本信息和问卷结果,包括专家积极系数、肯德尔和谐系数以及指标评分均数、满分比、变异系数等。结果专家的遴选体现了较高权威性,2轮德尔菲问卷回收率为76.47%和100%,专家权威系数均高于0.7,Kendall s W分别为0.271、0.308,专家意见总体协调性较好。“技术创新”指标均数<3.5且满分比7.69%予以删除;根据专家意见,增加“可操作性”“技术成熟度”三级指标,对“标准转化应用”“与相关政策规范协调”“提高效率”“能源消耗”“市场需求”等指标进行相应调整。结论初步构建了包含3个一级指标9个二级指标和27个三级指标的中医药国际标准实施效果评价指标体系,从标准技术水平、实施情况和实施效益3个维度体现了标准实施效果评价环节的全面性,为开展中医药国际标准实施效果评价研究提供了指导与参考。
