Conventional Al-Si materials always have a coarse and discontinuous Si structure,which limits their application as thermal management materials.Fortunately,nature has evolved efficient strategies to form complex micro...Conventional Al-Si materials always have a coarse and discontinuous Si structure,which limits their application as thermal management materials.Fortunately,nature has evolved efficient strategies to form complex microstructures that exhibit excellent wear resistance and thermal properties;one such example is found in the red deer antler.Here,inspired by the antler structure,AleSi composites with a novel fenestrated network-particle structure(F-N)and with a common isolated island structure(I-I)are designed and prepared.Subsequently,the dynamic formation of F-N is tracked and studied using computational fluid dynamics(CFD)simulation.To investigate the reinforcement mechanisms of F-N,the wear resistances and thermal properties of F-N and I-I are compared and analyzed.Simulation and experimental results show that the reconstruction of a semi-continuous structure promotes the formation of a striated structure,whereas flowing Si particles provide some sites for the formation of the fenestrated structure.The dynamic formation of F-N is strongly influenced by the convectionediffusion process and the flow path.Moreover,this biomimetic F-N structure exhibits better wear resistance and thermal properties than I-I,owing to its strong structural support and high expansion resistance.This work is expected to provide new perspectives on the microstructural design of thermal management materials with good wear resistance.展开更多
基于可信计算技术的恶意代码防范机制可以弥补传统杀毒方式对未知恶意代码防范能力的不足,但是软件自动在线升级和补丁安装会生成和调用未知的动态代码,对这些动态代码的实时可信判定问题阻碍了可信计算技术的应用普及.动态代码实时可...基于可信计算技术的恶意代码防范机制可以弥补传统杀毒方式对未知恶意代码防范能力的不足,但是软件自动在线升级和补丁安装会生成和调用未知的动态代码,对这些动态代码的实时可信判定问题阻碍了可信计算技术的应用普及.动态代码实时可信判定和可信传递方法(Trust Determination and Transitivity Method of Dynamic codes,TDTMD)从代码的调用环境和调用方式出发,对动态代码的来源是否可信进行判定,进而对动态代码是否可信进行判断.TDTMD可以在保证应用软件和系统的运行连续性前提下,提供对各种已知或未知恶意代码攻击的有效防范能力.TDTMD的原型系统及其实验结果表明,它对系统的运行性能影响较小,并且安全有效.展开更多
人体运动过程中,肢体的运动是连续的,而对应的运动捕捉数据是离散的.为了更好地分析人体日常运动行为的连续性与周期性,本文提出了一种基于函数型数据分析(Functional data analysis,FDA)的人体动态行为识别方法.首先,利用函数型数据分...人体运动过程中,肢体的运动是连续的,而对应的运动捕捉数据是离散的.为了更好地分析人体日常运动行为的连续性与周期性,本文提出了一种基于函数型数据分析(Functional data analysis,FDA)的人体动态行为识别方法.首先,利用函数型数据分析方法,将可穿戴式运动捕捉系统采集的人体周期行为数据函数化,通过函数准确地定义数据的连续性与周期性;然后,根据导函数信息确定一个运动周期的起始点,并近似地提取出一个运动周期的数据序列;最后,根据不同行为一个周期内的曲线特征差异,利用支持向量机对动态行为进行分类识别.实验结果表明,本文的算法既能够较好地描述人体动态行为的连续性与周期性,又使得运动数据在标定的统一起始点处对齐,且在WARD数据集与自采集数据集上均取得了较好的识别率,分别达到97.5%与98.75%.展开更多
基金supported by the financial support of the National Science Foundation of China(No.51607132 and No.51906189)the National Science Foundation of Shaanxi(No:2019JQ-842).
文摘Conventional Al-Si materials always have a coarse and discontinuous Si structure,which limits their application as thermal management materials.Fortunately,nature has evolved efficient strategies to form complex microstructures that exhibit excellent wear resistance and thermal properties;one such example is found in the red deer antler.Here,inspired by the antler structure,AleSi composites with a novel fenestrated network-particle structure(F-N)and with a common isolated island structure(I-I)are designed and prepared.Subsequently,the dynamic formation of F-N is tracked and studied using computational fluid dynamics(CFD)simulation.To investigate the reinforcement mechanisms of F-N,the wear resistances and thermal properties of F-N and I-I are compared and analyzed.Simulation and experimental results show that the reconstruction of a semi-continuous structure promotes the formation of a striated structure,whereas flowing Si particles provide some sites for the formation of the fenestrated structure.The dynamic formation of F-N is strongly influenced by the convectionediffusion process and the flow path.Moreover,this biomimetic F-N structure exhibits better wear resistance and thermal properties than I-I,owing to its strong structural support and high expansion resistance.This work is expected to provide new perspectives on the microstructural design of thermal management materials with good wear resistance.
文摘基于可信计算技术的恶意代码防范机制可以弥补传统杀毒方式对未知恶意代码防范能力的不足,但是软件自动在线升级和补丁安装会生成和调用未知的动态代码,对这些动态代码的实时可信判定问题阻碍了可信计算技术的应用普及.动态代码实时可信判定和可信传递方法(Trust Determination and Transitivity Method of Dynamic codes,TDTMD)从代码的调用环境和调用方式出发,对动态代码的来源是否可信进行判定,进而对动态代码是否可信进行判断.TDTMD可以在保证应用软件和系统的运行连续性前提下,提供对各种已知或未知恶意代码攻击的有效防范能力.TDTMD的原型系统及其实验结果表明,它对系统的运行性能影响较小,并且安全有效.
文摘人体运动过程中,肢体的运动是连续的,而对应的运动捕捉数据是离散的.为了更好地分析人体日常运动行为的连续性与周期性,本文提出了一种基于函数型数据分析(Functional data analysis,FDA)的人体动态行为识别方法.首先,利用函数型数据分析方法,将可穿戴式运动捕捉系统采集的人体周期行为数据函数化,通过函数准确地定义数据的连续性与周期性;然后,根据导函数信息确定一个运动周期的起始点,并近似地提取出一个运动周期的数据序列;最后,根据不同行为一个周期内的曲线特征差异,利用支持向量机对动态行为进行分类识别.实验结果表明,本文的算法既能够较好地描述人体动态行为的连续性与周期性,又使得运动数据在标定的统一起始点处对齐,且在WARD数据集与自采集数据集上均取得了较好的识别率,分别达到97.5%与98.75%.
