The most popular hardware used for parallel depth migration is the PC-Cluster but its application is limited due to large space occupation and high power consumption. In this paper, we introduce a new hardware archite...The most popular hardware used for parallel depth migration is the PC-Cluster but its application is limited due to large space occupation and high power consumption. In this paper, we introduce a new hardware architecture, based on which the finite difference （FD） wavefield-continuation depth migration can be conducted using the Graphics Processing Unit （GPU） as a CPU coprocessor. We demonstrate the program module and three key optimization steps for implementing FD depth migration： memory, thread structure, and instruction optimizations and consider evaluation methods for the amount of optimization. 2D and 3D models are used to test depth migration on the GPU. The tested results show that the depth migration computational efficiency greatly increased using the general-purpose GPU, increasing by at least 25 times compared to the AMD 2.5 GHz CPU.展开更多
Based on the physical meaning of sensitivity,a new finite element(FE) model updating method was proposed. In this method,a three-dimensional FE model of the Nanjing Yangtze River Bridge(NYRB) with ANSYS program was es...Based on the physical meaning of sensitivity,a new finite element(FE) model updating method was proposed. In this method,a three-dimensional FE model of the Nanjing Yangtze River Bridge(NYRB) with ANSYS program was established and updated by modifying some design parameters. To further validate the updated FE model,the analytical stress-time histories responses of main members induced by a moving train were compared with the measured ones. The results show that the relative error of maximum stress is 2.49% and the minimum relative coefficient of analytical stress-time histories responses is 0.793. The updated model has a good agreement between the calculated data and the tested data,and provides a current baseline FE model for long-term health monitoring and condition assessment of the NYRB. At the same time,the model is validated by stress-time histories responses to be feasible and practical for railway steel bridge model updating.展开更多
In this paper, we propose an optical burst network architecture supporting the ge- netic mesh topology. The intermediate node architecture of the mesh network can be the same with current wavelength switching Wave- le...In this paper, we propose an optical burst network architecture supporting the ge- netic mesh topology. The intermediate node architecture of the mesh network can be the same with current wavelength switching Wave- length Division Multiplexing （WDM） net- works, and thus can reuse existing deployed infrastructure. We employ a novel Optical Time Slot Interchange （OTSI） at the source nodes for the first time to mitigate the burst conten- tion and to increase the bandwidth utilization. Time- and wavelength-domain reuse in the OTSI significantly saves optical components and red- uces blocking probability.展开更多
Surface effects play an important role in the mechanical behavior of nanosized structural elements owing to the increased ratio of surface area to volume. The surface effects on the large deflection of nanowires were ...Surface effects play an important role in the mechanical behavior of nanosized structural elements owing to the increased ratio of surface area to volume. The surface effects on the large deflection of nanowires were considered. Both geometric nonlinearity in finite deformation and surface effects at nanoscale were taken into account to analyze the bending of nanowires subjected to a concentrated force. For simply supported beams and clamped-clamped beams, the influence of surface effects and geometric nonlinearity were discussed in detail. It is found that both surface effects and geometric nonlinearity tend to decrease the deflection of bending nanowires and thus increase the effective elastic modulus of nanowires. Surface effects yield the size dependent behavior of nanowires.展开更多
Behavior of structural elements under blast loading is different from that under usual loading conditions that are considered in conventional structural deigns. Cantilever slabs are more vulnerable than most other ele...Behavior of structural elements under blast loading is different from that under usual loading conditions that are considered in conventional structural deigns. Cantilever slabs are more vulnerable than most other elements under blast loads because of their shape. Understanding the blast behavior of cantilever slabs is useful in strengthening them against blast loads. In this paper, blast loading design envelopes for cantilever slabs are proposed using which, the blast behavior of conventional cantilever slabs can be identified. The paper describes the theories behind these envelopes and the way they can be applied to improve conventional designs. These envelopes have been prepared using numerical techniques. The theories used are accepted, verified and validated theories. The paper shows the possibility of converting a conventional cantilever slab design into impulsive regime design with minor adjustments to the structural design. It points out the importance of increasing slab thickness and controlling steel/concrete ratio for strengthening conventional cantilever slab designs and the requirement of reinforcement at top and bottom fibers.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 41104083 and 40804024) Fundamental Research Funds for the Central Universities (No, 2011YYL022)
文摘The most popular hardware used for parallel depth migration is the PC-Cluster but its application is limited due to large space occupation and high power consumption. In this paper, we introduce a new hardware architecture, based on which the finite difference （FD） wavefield-continuation depth migration can be conducted using the Graphics Processing Unit （GPU） as a CPU coprocessor. We demonstrate the program module and three key optimization steps for implementing FD depth migration： memory, thread structure, and instruction optimizations and consider evaluation methods for the amount of optimization. 2D and 3D models are used to test depth migration on the GPU. The tested results show that the depth migration computational efficiency greatly increased using the general-purpose GPU, increasing by at least 25 times compared to the AMD 2.5 GHz CPU.
基金Project(2001G025) supported by the Foundation of the Science and Technology Section of Ministry of Railway of ChinaProject(2006FJ4233) supported by Hunan Postdoctoral Scientific Program of ChinaProject(2006) supported by the Postdoctoral Foundation of Central South University,China
文摘Based on the physical meaning of sensitivity,a new finite element(FE) model updating method was proposed. In this method,a three-dimensional FE model of the Nanjing Yangtze River Bridge(NYRB) with ANSYS program was established and updated by modifying some design parameters. To further validate the updated FE model,the analytical stress-time histories responses of main members induced by a moving train were compared with the measured ones. The results show that the relative error of maximum stress is 2.49% and the minimum relative coefficient of analytical stress-time histories responses is 0.793. The updated model has a good agreement between the calculated data and the tested data,and provides a current baseline FE model for long-term health monitoring and condition assessment of the NYRB. At the same time,the model is validated by stress-time histories responses to be feasible and practical for railway steel bridge model updating.
文摘In this paper, we propose an optical burst network architecture supporting the ge- netic mesh topology. The intermediate node architecture of the mesh network can be the same with current wavelength switching Wave- length Division Multiplexing （WDM） net- works, and thus can reuse existing deployed infrastructure. We employ a novel Optical Time Slot Interchange （OTSI） at the source nodes for the first time to mitigate the burst conten- tion and to increase the bandwidth utilization. Time- and wavelength-domain reuse in the OTSI significantly saves optical components and red- uces blocking probability.
基金Project(11072186)supported by the National Natural Science Foundation of China
文摘Surface effects play an important role in the mechanical behavior of nanosized structural elements owing to the increased ratio of surface area to volume. The surface effects on the large deflection of nanowires were considered. Both geometric nonlinearity in finite deformation and surface effects at nanoscale were taken into account to analyze the bending of nanowires subjected to a concentrated force. For simply supported beams and clamped-clamped beams, the influence of surface effects and geometric nonlinearity were discussed in detail. It is found that both surface effects and geometric nonlinearity tend to decrease the deflection of bending nanowires and thus increase the effective elastic modulus of nanowires. Surface effects yield the size dependent behavior of nanowires.
文摘Behavior of structural elements under blast loading is different from that under usual loading conditions that are considered in conventional structural deigns. Cantilever slabs are more vulnerable than most other elements under blast loads because of their shape. Understanding the blast behavior of cantilever slabs is useful in strengthening them against blast loads. In this paper, blast loading design envelopes for cantilever slabs are proposed using which, the blast behavior of conventional cantilever slabs can be identified. The paper describes the theories behind these envelopes and the way they can be applied to improve conventional designs. These envelopes have been prepared using numerical techniques. The theories used are accepted, verified and validated theories. The paper shows the possibility of converting a conventional cantilever slab design into impulsive regime design with minor adjustments to the structural design. It points out the importance of increasing slab thickness and controlling steel/concrete ratio for strengthening conventional cantilever slab designs and the requirement of reinforcement at top and bottom fibers.
