Among the plethora of IoT(Internet of Things)applications,the smart home is one of the fastest-growing.However,the rapid development of the smart home has also made smart home systems a target for attackers.Recently,r...Among the plethora of IoT(Internet of Things)applications,the smart home is one of the fastest-growing.However,the rapid development of the smart home has also made smart home systems a target for attackers.Recently,researchers have made many efforts to investigate and enhance the security of smart home systems.Toward a more secure smart home ecosystem,we present a detailed literature review on the security of smart home systems.Specifically,we categorize smart home systems’security issues into the platform,device,and communication issues.After exploring the research and specific issues in each of these security areas,we summarize the root causes of the security flaws in today's smart home systems,which include the heterogeneity of internal components of the systems,vendors'customization,the lack of clear responsibility boundaries and the absence of standard security standards.Finally,to better understand the security of smart home systems and potentially provide better protection for smart home systems,we propose research directions,including automated vulnerability mining,vigorous security checking,and data-driven security analysis.展开更多
The cavitation dynamics and mechanical stress in viscoelastic tissues, as the primary mechanisms of some ultrasound therapies, are extremely complex due to the interactions of cavitation bubble with adjacent bubbles a...The cavitation dynamics and mechanical stress in viscoelastic tissues, as the primary mechanisms of some ultrasound therapies, are extremely complex due to the interactions of cavitation bubble with adjacent bubbles and surrounding tissues.Therefore, the cavitation dynamics and resultant mechanical stress of two-interacting bubbles in the viscoelastic tissues are numerically investigated, especially focusing on the effects of the adjacent bubble. The results demonstrate that the mechanical stress is highly dependent on the bubble dynamics. The compressive stress and tensile stress are generated at the stage of bubble expansion and collapse stage, respectively. Furthermore, within the initial parameters examined in this paper, the effects of the adjacent bubble will distinctly suppress the radial expansion of the small bubble and consequently lead its associated stresses to decrease. Owing to the superimposition of two stress fields, the mechanical stresses surrounding the small bubble in the direction of the neighboring bubble are smaller than those in other directions. For two interacting cavitation bubbles, the suppression effects of the nearby bubble on both the cavitation dynamics and the stresses surrounding the small bubble increase as the ultrasound amplitude and the initial radius of the large bubble increase, whereas they decrease with the inter-bubble distance increasing. Moreover, increasing the tissue viscoelasticity will reduce the suppression effects of the nearby bubble, except in instances where the compressive stress and tensile stress first increase and then decrease with the tissue elasticity and viscosity increasing respectively. This study can provide a further understanding of the mechanisms of cavitation-associated mechanical damage to the adjacent tissues or cells.展开更多
Separation of primary Si phase and removal of boron in the primary Si phase during the solidification process of the Al-30%Si-10%Sn melt under a traveling magnetic field(TMF) were investigated. The results showed that...Separation of primary Si phase and removal of boron in the primary Si phase during the solidification process of the Al-30%Si-10%Sn melt under a traveling magnetic field(TMF) were investigated. The results showed that the agglomeration layer of the primary Si can be formed in the periphery of the ingot while the inner microstructures mainly consist of the eutectic α-Al+Si and β-Sn phases. The intense melt flow carries the bulk liquid with higher Si content to promote the growth of the primary Si phase which is first precipitated close to the inner wall of crucible with a relatively lower temperature, resulting in the remarkable segregation of the primary Si phase. The content of impurity B in the primary Si phase can be removed effectively with an increase in magnetic flux intensity. The results of electron probe microanalysis(EPMA) clearly indicated that the average intensity of the B Ka line in the α-Al phase region of Al-Si-Sn alloy is higher in the case of solidification under TMF than that of normal solidification condition, suggesting that the electromagnetic stirring can promote the B removal from the primary Si phase.展开更多
基金supported by the Hubei Provincial Key Research and Development Technology Special Innovation Project under Grant No.2021BAA032the Wuhan Applied Foundational Frontier Project under Grant No.2020010601012188the Guangdong Provincial Key Research and Development Plan Project of China under Grant No.2019B010139001.
文摘Among the plethora of IoT(Internet of Things)applications,the smart home is one of the fastest-growing.However,the rapid development of the smart home has also made smart home systems a target for attackers.Recently,researchers have made many efforts to investigate and enhance the security of smart home systems.Toward a more secure smart home ecosystem,we present a detailed literature review on the security of smart home systems.Specifically,we categorize smart home systems’security issues into the platform,device,and communication issues.After exploring the research and specific issues in each of these security areas,we summarize the root causes of the security flaws in today's smart home systems,which include the heterogeneity of internal components of the systems,vendors'customization,the lack of clear responsibility boundaries and the absence of standard security standards.Finally,to better understand the security of smart home systems and potentially provide better protection for smart home systems,we propose research directions,including automated vulnerability mining,vigorous security checking,and data-driven security analysis.
基金National Natural Science Foundation of China(51505079)Heilongjiang Education Department special Project in Fundamental Business(135309486)Qiqihar Science and Technology Project(GYGG-201719)~~
基金Project supported by the National Natural Science Foundation of China (Grant No.11904042)the Natural Science Foundation of Chongqing,China (Grant No.cstc2019jcyj-msxmX0534)the Science and Technology Research Program of Chongqing Municipal Education Commission,China (Grant No.KJQN202000617)。
文摘The cavitation dynamics and mechanical stress in viscoelastic tissues, as the primary mechanisms of some ultrasound therapies, are extremely complex due to the interactions of cavitation bubble with adjacent bubbles and surrounding tissues.Therefore, the cavitation dynamics and resultant mechanical stress of two-interacting bubbles in the viscoelastic tissues are numerically investigated, especially focusing on the effects of the adjacent bubble. The results demonstrate that the mechanical stress is highly dependent on the bubble dynamics. The compressive stress and tensile stress are generated at the stage of bubble expansion and collapse stage, respectively. Furthermore, within the initial parameters examined in this paper, the effects of the adjacent bubble will distinctly suppress the radial expansion of the small bubble and consequently lead its associated stresses to decrease. Owing to the superimposition of two stress fields, the mechanical stresses surrounding the small bubble in the direction of the neighboring bubble are smaller than those in other directions. For two interacting cavitation bubbles, the suppression effects of the nearby bubble on both the cavitation dynamics and the stresses surrounding the small bubble increase as the ultrasound amplitude and the initial radius of the large bubble increase, whereas they decrease with the inter-bubble distance increasing. Moreover, increasing the tissue viscoelasticity will reduce the suppression effects of the nearby bubble, except in instances where the compressive stress and tensile stress first increase and then decrease with the tissue elasticity and viscosity increasing respectively. This study can provide a further understanding of the mechanisms of cavitation-associated mechanical damage to the adjacent tissues or cells.
基金supported by the National Natural Science Foundation of China(Nos.51471042,51501028,and 51271042)
文摘Separation of primary Si phase and removal of boron in the primary Si phase during the solidification process of the Al-30%Si-10%Sn melt under a traveling magnetic field(TMF) were investigated. The results showed that the agglomeration layer of the primary Si can be formed in the periphery of the ingot while the inner microstructures mainly consist of the eutectic α-Al+Si and β-Sn phases. The intense melt flow carries the bulk liquid with higher Si content to promote the growth of the primary Si phase which is first precipitated close to the inner wall of crucible with a relatively lower temperature, resulting in the remarkable segregation of the primary Si phase. The content of impurity B in the primary Si phase can be removed effectively with an increase in magnetic flux intensity. The results of electron probe microanalysis(EPMA) clearly indicated that the average intensity of the B Ka line in the α-Al phase region of Al-Si-Sn alloy is higher in the case of solidification under TMF than that of normal solidification condition, suggesting that the electromagnetic stirring can promote the B removal from the primary Si phase.
