Aortic valve calcification disease (CAVD) is the most prevalent degenerative valve disease in humans, leading to significant morbidity and mortality. Despite its common occurrence, our understanding of the underlying ...Aortic valve calcification disease (CAVD) is the most prevalent degenerative valve disease in humans, leading to significant morbidity and mortality. Despite its common occurrence, our understanding of the underlying mechanisms remains incomplete, and available treatment options are limited and risky. A more comprehensive understanding of the biology of CAVD is essential to identify new therapeutic strategies. Animal models have played a crucial role in advancing our knowledge of CAVD and exploring potential treatments. However, these models have inherent limitations as they cannot fully replicate the complex physiological mechanisms of human CAVD. In this review, we examine various CAVD models ranging from pigs to mice, highlighting the unique characteristics of each model to enhance our understanding of CAVD. While these models offer valuable insights, they also have limitations and shortcomings. We propose that the guide wire model shows promise for future CAVD research, and streamlining the methodology could enhance our understanding and expand the research scope in this field.展开更多
In this paper,the covert age of information(CAoI),which characterizes the timeliness and covertness performance of communication,is first investigated in the short-packet covert communication with time modulated retro...In this paper,the covert age of information(CAoI),which characterizes the timeliness and covertness performance of communication,is first investigated in the short-packet covert communication with time modulated retrodirective array(TMRDA).Specifically,the TMRDA is designed to maximize the antenna gain in the target direction while the side lobe is sufficiently suppressed.On this basis,the covertness constraint and CAoI are derived in closed form.To facilitate the covert transmission design,the transmit power and block-length are jointly optimized to minimize the CAoI,which demonstrates the trade-off between covertness and timelessness.Our results illustrate that there exists an optimal block-length that yields the minimum CAoI,and the presented optimization results can achieve enhanced performance compared with the fixed block-length case.Additionally,we observe that smaller beam pointing error at Bob leads to improvements in CAoI.展开更多
针对地球观测领域规模最大的政府间国际组织“地球观测组织(Group on Earth Observations)”提出的“全球综合地球观测系统”这一概念,梳理了其实现和建设的现状,分析了其具有供给导向、元数据质量不高、无法直接支撑决策和行动等局限...针对地球观测领域规模最大的政府间国际组织“地球观测组织(Group on Earth Observations)”提出的“全球综合地球观测系统”这一概念,梳理了其实现和建设的现状,分析了其具有供给导向、元数据质量不高、无法直接支撑决策和行动等局限性。结合我国参加地球观测组织的计划和成果,详细阐述了面向全球服务的中国综合地球观测系统的内涵,并基于全球综合地球观测系统的优势与不足,提出了中国综合地球观测系统平台的系统架构,另外就优质数据集研制、信息专题服务以及数据应急响应3个案例阐述了中国综合地球观测系统平台的实践及成效。展开更多
针对当前无人机目标探测存在的发射功率大、积累时间长等问题,本文提出了一种新体制无人机探测系统,实现二维方向探测。首先,给出了该系统的整体架构,对探测过程进行建模,并推导出相关公式。系统通过两个垂直放置的时间调制阵列形成L型...针对当前无人机目标探测存在的发射功率大、积累时间长等问题,本文提出了一种新体制无人机探测系统,实现二维方向探测。首先,给出了该系统的整体架构,对探测过程进行建模,并推导出相关公式。系统通过两个垂直放置的时间调制阵列形成L型阵,从谐波域中获取目标的俯仰角和方位角信息。系统基于1bit开关,提高了接收信号的谐波分量功率,实现了无人机目标的二维波达方向(Direction Of Arrival,DOA)角估计。仿真实验验证了所提方法的有效性,并对比了不同开关占空比下的测角性能。展开更多
文摘Aortic valve calcification disease (CAVD) is the most prevalent degenerative valve disease in humans, leading to significant morbidity and mortality. Despite its common occurrence, our understanding of the underlying mechanisms remains incomplete, and available treatment options are limited and risky. A more comprehensive understanding of the biology of CAVD is essential to identify new therapeutic strategies. Animal models have played a crucial role in advancing our knowledge of CAVD and exploring potential treatments. However, these models have inherent limitations as they cannot fully replicate the complex physiological mechanisms of human CAVD. In this review, we examine various CAVD models ranging from pigs to mice, highlighting the unique characteristics of each model to enhance our understanding of CAVD. While these models offer valuable insights, they also have limitations and shortcomings. We propose that the guide wire model shows promise for future CAVD research, and streamlining the methodology could enhance our understanding and expand the research scope in this field.
文摘In this paper,the covert age of information(CAoI),which characterizes the timeliness and covertness performance of communication,is first investigated in the short-packet covert communication with time modulated retrodirective array(TMRDA).Specifically,the TMRDA is designed to maximize the antenna gain in the target direction while the side lobe is sufficiently suppressed.On this basis,the covertness constraint and CAoI are derived in closed form.To facilitate the covert transmission design,the transmit power and block-length are jointly optimized to minimize the CAoI,which demonstrates the trade-off between covertness and timelessness.Our results illustrate that there exists an optimal block-length that yields the minimum CAoI,and the presented optimization results can achieve enhanced performance compared with the fixed block-length case.Additionally,we observe that smaller beam pointing error at Bob leads to improvements in CAoI.
文摘针对地球观测领域规模最大的政府间国际组织“地球观测组织(Group on Earth Observations)”提出的“全球综合地球观测系统”这一概念,梳理了其实现和建设的现状,分析了其具有供给导向、元数据质量不高、无法直接支撑决策和行动等局限性。结合我国参加地球观测组织的计划和成果,详细阐述了面向全球服务的中国综合地球观测系统的内涵,并基于全球综合地球观测系统的优势与不足,提出了中国综合地球观测系统平台的系统架构,另外就优质数据集研制、信息专题服务以及数据应急响应3个案例阐述了中国综合地球观测系统平台的实践及成效。
文摘针对当前无人机目标探测存在的发射功率大、积累时间长等问题,本文提出了一种新体制无人机探测系统,实现二维方向探测。首先,给出了该系统的整体架构,对探测过程进行建模,并推导出相关公式。系统通过两个垂直放置的时间调制阵列形成L型阵,从谐波域中获取目标的俯仰角和方位角信息。系统基于1bit开关,提高了接收信号的谐波分量功率,实现了无人机目标的二维波达方向(Direction Of Arrival,DOA)角估计。仿真实验验证了所提方法的有效性,并对比了不同开关占空比下的测角性能。
