为了减少车辆自动驾驶行驶过程中由于故障导致的安全风险,基于故障树理论(FTA,Fault Tree Analysis)对自动驾驶车辆故障进行了定性分析。通过评估不同故障对自动驾驶车辆安全行驶影响的严重程度,结合最小风险策略,设计出了一套分类分阶...为了减少车辆自动驾驶行驶过程中由于故障导致的安全风险,基于故障树理论(FTA,Fault Tree Analysis)对自动驾驶车辆故障进行了定性分析。通过评估不同故障对自动驾驶车辆安全行驶影响的严重程度,结合最小风险策略,设计出了一套分类分阶段的自动驾驶故障处理方案,尽最大能力提升行车安全。展开更多
基于深度学习的目标检测方法在智能车载控制器应用时很难同时满足检测精度与速度的要求。因此,提出一种多级参数融合的驾驶场景目标检测方法,实现检测速度和精度的同步提升。首先,设计出一种多级分支结构用于构建模型,同时,为提高模型...基于深度学习的目标检测方法在智能车载控制器应用时很难同时满足检测精度与速度的要求。因此,提出一种多级参数融合的驾驶场景目标检测方法,实现检测速度和精度的同步提升。首先,设计出一种多级分支结构用于构建模型,同时,为提高模型的推理速度,引入一种多级参数融合的方法,即将多级结构层等效为单一的卷积-批标准化层,在保证模型泛化能力不变的条件下,大幅度减小模型的参数量。其次,为增加模型的检测精度,提出一种SSIoU(Soft scaledintersectionofunion)边界框损失计算方法以及一种联合半锚框的标签关联算法,提高模型对驾驶场景的适应能力。最后,开展基于DAIR-V2X-V数据集的试验验证,结果表明,所提出的多级参数融合模型,相比于目前先进的YOLO(You only look once)算法,检测精度(Mean average precision,mAP)提高了9.89%,推理速度(Frames per second,FPS)提高了51.89%。展开更多
This paper deals with the blowup estimates near the blowup time for the system of heat equations in a half space coupled through nonlinear boundary conditions. The upper and lower bounds of blowup rate are established...This paper deals with the blowup estimates near the blowup time for the system of heat equations in a half space coupled through nonlinear boundary conditions. The upper and lower bounds of blowup rate are established. The uniqueness and nonuniqueness results for the system with vanishing initial value are given.展开更多
In this paper,a reaction-diffusion system is proposed to investigate avian-human influenza.Two free boundaries are introduced to describe the spreading frontiers of the avian influenza.The basic reproduction numbers r...In this paper,a reaction-diffusion system is proposed to investigate avian-human influenza.Two free boundaries are introduced to describe the spreading frontiers of the avian influenza.The basic reproduction numbers rF0(t)and RF0(t)are defined for the bird with the avian influenza and for the human with the mutant avian influenza of the free boundary problem,respectively.Properties of these two time-dependent basic reproduction numbers are obtained.Sufficient conditions both for spreading and for vanishing of the avian influenza are given.It is shown that if rF0(0)<1 and the initial number of the infected birds is small,the avian influenza vanishes in the bird world.Furthermore,if rF0(0)<1 and RF0(0)<1,the avian influenza vanishes in the bird and human worlds.In the case that rF0(0)<1 and RF0(0)>1,spreading of the mutant avian influenza in the human world is possible.It is also shown that if rF0(t0)>1 for any t0>0,the avian influenza spreads in the bird world.展开更多
We study a simplified version of a West Nile virus （WNv） model discussed by Lewis et al. （2006）, which was considered as a first approximation for the spatial spread of WNv. The basic reproduction number R0 for th...We study a simplified version of a West Nile virus （WNv） model discussed by Lewis et al. （2006）, which was considered as a first approximation for the spatial spread of WNv. The basic reproduction number R0 for the non-spatial epidemic model is defined and a threshold parameter RD for the corresponding problem with null Dirichlet boundary condition is introduced. We consider a free boundary problem with a coupled system, which describes the diffusion of birds by a PDE and the movement of mosquitoes by an ODE. The risk index R0^F（t） associated with the disease in spatial setting is represented. Sufficient conditions for the WNv to eradicate or to spread are given. The asymptotic behavior of the solution to the system when the spreading occurs is considered. It is shown that the initial number of infected populations, the diffusion rate of birds and the length of initial habitat exhibit important impacts on the vanishing or spreading of the virus. Numerical simulations are presented to illustrate the analytical results.展开更多
In this paper,we consider a localized problem with free boundary for the heat equation in higher space dimensions and heterogeneous environment.For simplicity,we assume that the environment and solution are radially s...In this paper,we consider a localized problem with free boundary for the heat equation in higher space dimensions and heterogeneous environment.For simplicity,we assume that the environment and solution are radially symmetric.First,by using the contraction mapping theorem,we prove that the local solution exists and is unique.Then,some sufficient conditions are given under which the solution will blow up in finite time.Our results indicate that the blowup occurs if the initial data are sufficiently large.Finally,the long time behavior of the global solution is discussed.It is shown that the global fast solution does exist if the initial data are sufficiently small,while the global slow solution is possible if the initial data are suitably large.展开更多
文摘基于深度学习的目标检测方法在智能车载控制器应用时很难同时满足检测精度与速度的要求。因此,提出一种多级参数融合的驾驶场景目标检测方法,实现检测速度和精度的同步提升。首先,设计出一种多级分支结构用于构建模型,同时,为提高模型的推理速度,引入一种多级参数融合的方法,即将多级结构层等效为单一的卷积-批标准化层,在保证模型泛化能力不变的条件下,大幅度减小模型的参数量。其次,为增加模型的检测精度,提出一种SSIoU(Soft scaledintersectionofunion)边界框损失计算方法以及一种联合半锚框的标签关联算法,提高模型对驾驶场景的适应能力。最后,开展基于DAIR-V2X-V数据集的试验验证,结果表明,所提出的多级参数融合模型,相比于目前先进的YOLO(You only look once)算法,检测精度(Mean average precision,mAP)提高了9.89%,推理速度(Frames per second,FPS)提高了51.89%。
基金This work was supported by the National Natural Science Foundation of China(Grant No.10171088)and also by SRF for ROCS,SEM.
文摘This paper deals with the blowup estimates near the blowup time for the system of heat equations in a half space coupled through nonlinear boundary conditions. The upper and lower bounds of blowup rate are established. The uniqueness and nonuniqueness results for the system with vanishing initial value are given.
基金supported by National Natural Science Foundation of China(Grant No.11071209)Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education,Science and Technology(Grant No.2010-0025700)Natural Science Foundation of the Higher Education Institutions of Jiangsu Province(Grant No.12KJD110008)
文摘In this paper,a reaction-diffusion system is proposed to investigate avian-human influenza.Two free boundaries are introduced to describe the spreading frontiers of the avian influenza.The basic reproduction numbers rF0(t)and RF0(t)are defined for the bird with the avian influenza and for the human with the mutant avian influenza of the free boundary problem,respectively.Properties of these two time-dependent basic reproduction numbers are obtained.Sufficient conditions both for spreading and for vanishing of the avian influenza are given.It is shown that if rF0(0)<1 and the initial number of the infected birds is small,the avian influenza vanishes in the bird world.Furthermore,if rF0(0)<1 and RF0(0)<1,the avian influenza vanishes in the bird and human worlds.In the case that rF0(0)<1 and RF0(0)>1,spreading of the mutant avian influenza in the human world is possible.It is also shown that if rF0(t0)>1 for any t0>0,the avian influenza spreads in the bird world.
基金supported by National Natural Science Foundation of China(Grant No.11371311)Top-Notch Academic Programs Project of Jiangsu Higher Education Institutions(Grant No.PPZY2015B109)
文摘We study a simplified version of a West Nile virus （WNv） model discussed by Lewis et al. （2006）, which was considered as a first approximation for the spatial spread of WNv. The basic reproduction number R0 for the non-spatial epidemic model is defined and a threshold parameter RD for the corresponding problem with null Dirichlet boundary condition is introduced. We consider a free boundary problem with a coupled system, which describes the diffusion of birds by a PDE and the movement of mosquitoes by an ODE. The risk index R0^F（t） associated with the disease in spatial setting is represented. Sufficient conditions for the WNv to eradicate or to spread are given. The asymptotic behavior of the solution to the system when the spreading occurs is considered. It is shown that the initial number of infected populations, the diffusion rate of birds and the length of initial habitat exhibit important impacts on the vanishing or spreading of the virus. Numerical simulations are presented to illustrate the analytical results.
基金supported by National Natural Science Foundation of China (Grant Nos.11071209 and 10801115)the PhD Programs Foundation of Ministry of Education of China (Grant No.20113250110005)
文摘In this paper,we consider a localized problem with free boundary for the heat equation in higher space dimensions and heterogeneous environment.For simplicity,we assume that the environment and solution are radially symmetric.First,by using the contraction mapping theorem,we prove that the local solution exists and is unique.Then,some sufficient conditions are given under which the solution will blow up in finite time.Our results indicate that the blowup occurs if the initial data are sufficiently large.Finally,the long time behavior of the global solution is discussed.It is shown that the global fast solution does exist if the initial data are sufficiently small,while the global slow solution is possible if the initial data are suitably large.
