Aiming to analyze the damage mechanism of UTAO from the perspective of meso-mechanical mechanism using discrete element method(DEM),we conducted study of diseases problems of UTAO in several provinces in China,and fou...Aiming to analyze the damage mechanism of UTAO from the perspective of meso-mechanical mechanism using discrete element method(DEM),we conducted study of diseases problems of UTAO in several provinces in China,and found that aggregate spalling was one of the main disease types of UTAO.A discrete element model of UTAO pavement structure was constructed to explore the meso-mechanical mechanism of UTAO damage under the influence of layer thickness,gradation,and bonding modulus.The experimental results show that,as the thickness of UTAO decreasing,the maximum value and the mean value of the contact force between all aggregate particles gradually increase,which leads to aggregates more prone to spalling.Compared with OGFC-5 UTAO,AC-5 UTAO presents smaller maximum and average values of all contact forces,and the loading pressure in AC-5 UTAO is fully diffused in the lateral direction.In addition,the increment of pavement modulus strengthens the overall force of aggregate particles inside UTAO,resulting in aggregate particles peeling off more easily.The increase of bonding modulus changes the position where the maximum value of the tangential force appears,whereas has no effect on the normal force.展开更多
目前出现的大规模(large-scale)的多媒体应用对 Internet 提出了新的挑战。传统的 IP 组播(IP multicast,IPM)由于实现技术的复杂性,很难在 Internet 上推广。相反,基于叠加网络(overlay network,ON)的解决方案则受到各方面的关注。本...目前出现的大规模(large-scale)的多媒体应用对 Internet 提出了新的挑战。传统的 IP 组播(IP multicast,IPM)由于实现技术的复杂性,很难在 Internet 上推广。相反,基于叠加网络(overlay network,ON)的解决方案则受到各方面的关注。本文针对大规模实时多媒体应用需求,通过建立评价参数模型对 ON 协议进行研究。尤其对 overlay组播(overiay multicast,OM)的 QoS 控制、可靠性以及可伸缩性机制进行了分析。与 IPM 相比,OM 虽然有性能代价(performance penalty)问题,但是 OM 能方便、灵活地利用多种高层的功能实现,基于 hop-by-hop 方式有效地提供E2E(end-to-end)的可靠性和 Qos 保障,并且较好地支持 TCP-friendliness,具有良好的可伸缩性。此外,OM 的基础网络(infrastructure/underlay network)无关性,也使其容易在 Internet 中进行配置。以上特性使得 OM 成为支持 Inter-net 上大规模实时多媒体应用的最具前景的技术。展开更多
文摘Aiming to analyze the damage mechanism of UTAO from the perspective of meso-mechanical mechanism using discrete element method(DEM),we conducted study of diseases problems of UTAO in several provinces in China,and found that aggregate spalling was one of the main disease types of UTAO.A discrete element model of UTAO pavement structure was constructed to explore the meso-mechanical mechanism of UTAO damage under the influence of layer thickness,gradation,and bonding modulus.The experimental results show that,as the thickness of UTAO decreasing,the maximum value and the mean value of the contact force between all aggregate particles gradually increase,which leads to aggregates more prone to spalling.Compared with OGFC-5 UTAO,AC-5 UTAO presents smaller maximum and average values of all contact forces,and the loading pressure in AC-5 UTAO is fully diffused in the lateral direction.In addition,the increment of pavement modulus strengthens the overall force of aggregate particles inside UTAO,resulting in aggregate particles peeling off more easily.The increase of bonding modulus changes the position where the maximum value of the tangential force appears,whereas has no effect on the normal force.
文摘目前出现的大规模(large-scale)的多媒体应用对 Internet 提出了新的挑战。传统的 IP 组播(IP multicast,IPM)由于实现技术的复杂性,很难在 Internet 上推广。相反,基于叠加网络(overlay network,ON)的解决方案则受到各方面的关注。本文针对大规模实时多媒体应用需求,通过建立评价参数模型对 ON 协议进行研究。尤其对 overlay组播(overiay multicast,OM)的 QoS 控制、可靠性以及可伸缩性机制进行了分析。与 IPM 相比,OM 虽然有性能代价(performance penalty)问题,但是 OM 能方便、灵活地利用多种高层的功能实现,基于 hop-by-hop 方式有效地提供E2E(end-to-end)的可靠性和 Qos 保障,并且较好地支持 TCP-friendliness,具有良好的可伸缩性。此外,OM 的基础网络(infrastructure/underlay network)无关性,也使其容易在 Internet 中进行配置。以上特性使得 OM 成为支持 Inter-net 上大规模实时多媒体应用的最具前景的技术。
