Interaction between high-intensity pulsed ion beam （HIPIB） and a double-layer target with titanium film on top of aluminum substrate was simulated. The two-dimensional nonlinear thermal conduction equations, with th...Interaction between high-intensity pulsed ion beam （HIPIB） and a double-layer target with titanium film on top of aluminum substrate was simulated. The two-dimensional nonlinear thermal conduction equations, with the deposited energy in the target taken as source term, were derived and solved by finite differential method. As a result, the two-dimensional spatial and temporal evolution profiles of temperature were obtained for a titanium/aluminum double-layer target irradiated by a pulse of HIPIB. The effects of ion beam current density on the phase state of the target materials near the film and substrate interface were analyzed. Both titanium and aluminum were melted near the interface after a shot when the ion beam current density fell in the range of 100 A/cm2 to 200 A/cm2.展开更多
The design and fabrication method of magnetic field coils with high uniformity is essential for atomic magnetometers.In this paper,a novel design strategy for cylindrical uniform coils is first proposed,which combines...The design and fabrication method of magnetic field coils with high uniformity is essential for atomic magnetometers.In this paper,a novel design strategy for cylindrical uniform coils is first proposed,which combines the target-field method(TFM)with an optimized slime mold algorithm(SMA)to determine optimal structure parameters.Then,the realization method for the designed cylindrical coil by using the flexible printed circuit(FPC)technology is presented.Compared with traditional fabrication methods,this method has advantages in excellent flexibility and bending property,making the coils easier to be arranged in limited space.Moreover,the manufacturing process of the FPC technology via a specific cylindrical uniform magnetic field coil is discussed in detail,and the successfully realized coil is well tested in a verification system.By comparing the uniformity performance of the experimental coil with the simulation one,the effectiveness of the FPC technology in producing cylindrical coils has been well validated.展开更多
针对复杂输电环境下机械臂多目标点路径规划效率低、路径代价高的问题,提出了基于改进的人工势场引导的知情快速扩展随机树算法(improved artificial potential field-informed rapidly-exploring random trees star,IAPF-IRRT^(*))来...针对复杂输电环境下机械臂多目标点路径规划效率低、路径代价高的问题,提出了基于改进的人工势场引导的知情快速扩展随机树算法(improved artificial potential field-informed rapidly-exploring random trees star,IAPF-IRRT^(*))来提升路径规划的性能。首先引入长方体斥力场模型改进传统人工势场中球形斥力场模型,建立输电环境下复杂障碍物的斥力场。然后采用位置均匀分布的椭球域改进IAPF-IRRT*算法中的椭圆域,避免复杂输电环境下采样点出现局部冗余,提高搜索效率。最后引入三角寻优法优化路径中的冗余节点并结合三次样条插曲线对路径平滑处理。在三维简单、三维复杂和复杂输电环境这三组不同复杂程度的障碍物地图上进行验证,其结果表明:IAPF-IRRT*算法与标准RRT、RRT*算法相比,时间效率分别提升了44.8%~83.8%、68.3%~95.2%、26.5%~71.8%;路径代价分别降低了15.5%~35.0%、14.1%~35.3%、31.5%~43.5%;路径中的节点数量分别减少了75.6%~78.8%、75.0%~78.0%、70.4%~72.0%。展开更多
针对传统人工势场法在多障碍物复杂环境的全局路径规划中出现的目标不可达、易陷入陷阱区域以及局部极小点问题,提出一种简化障碍物预测碰撞人工势场法(simplified obstacles and predict collision of artificial potential field meth...针对传统人工势场法在多障碍物复杂环境的全局路径规划中出现的目标不可达、易陷入陷阱区域以及局部极小点问题,提出一种简化障碍物预测碰撞人工势场法(simplified obstacles and predict collision of artificial potential field method,SOPC-APF),算法引入预测碰撞思想,在机器人未进入陷阱区域或者极小点问题前做出决策;对于多障碍物的斥力与目标点的引力产生的合力使机器人陷入震荡,提出简化障碍物,即简化为影响范围内目标点一侧的受限障碍物;针对目标不可达问题,在碰撞预测基础上,设定虚拟目标点,经改进的斥力函数引导机器人快速生成一条平滑、平稳、无碰撞的路径。通过与传统算法、改进APF算法以及改进蚁群算法的仿真对比实验表明,SOPC-APF有效解决了人工势场法不适用于多障碍物复杂环境的问题,以及传统算法容易陷入陷阱区域和局部极小点问题。展开更多
Significant high magnetic gradient field strength is essential to obtaining high-resolution images in a benchtop mag- netic resonance imaging （BT-MRI） system with permanent magnet. Extending minimum wire spacing and...Significant high magnetic gradient field strength is essential to obtaining high-resolution images in a benchtop mag- netic resonance imaging （BT-MRI） system with permanent magnet. Extending minimum wire spacing and maximum wire width of gradient coils is one of the key solutions to minimize the maximum current density so as to reduce the local heating and generate higher magnetic field gradient strength. However, maximum current density is hard to optimize together with field linearity, stored magnetic energy, and power dissipation by the traditional target field method. In this paper, a new multi-objective method is proposed to optimize the maximum current density, field linearity, stored magnetic energy, and power dissipation in MRI gradient coils. The simulation and experimental results show that the minimum wire spacings are improved by 159% and 62% for the transverse and longitudinal gradient coil respectively. The maximum wire width increases from 0.5 mm to 1.5 mm. Maximum gradient field strengths of 157 mT/m and 405 mT/m for transverse and lon- gitudinal coil are achieved, respectively. The experimental results in BT-MRI instrument demonstrate that the MRI images with in-plane resolution of 50 ~tm can be obtained by using the designed coils.展开更多
基金supported by National Natural Science Foundation of China (No.10975026)
文摘Interaction between high-intensity pulsed ion beam （HIPIB） and a double-layer target with titanium film on top of aluminum substrate was simulated. The two-dimensional nonlinear thermal conduction equations, with the deposited energy in the target taken as source term, were derived and solved by finite differential method. As a result, the two-dimensional spatial and temporal evolution profiles of temperature were obtained for a titanium/aluminum double-layer target irradiated by a pulse of HIPIB. The effects of ion beam current density on the phase state of the target materials near the film and substrate interface were analyzed. Both titanium and aluminum were melted near the interface after a shot when the ion beam current density fell in the range of 100 A/cm2 to 200 A/cm2.
基金Project supported by the National Natural Science Foundation of China(Grant No.62101004)the Opening Research Fund of Anhui Engineering Research Center of Vehicle Display Integrated Systems(Grant No.VDIS2023C05)+1 种基金the Opening Project of Key Laboratory of Electric Drive and Control of Anhui Province,China(Grant No.DQKJ202309)the Excellent Scientific Research and Innovation Teams of Anhui Province,China(Grant No.2022AH010059)。
文摘The design and fabrication method of magnetic field coils with high uniformity is essential for atomic magnetometers.In this paper,a novel design strategy for cylindrical uniform coils is first proposed,which combines the target-field method(TFM)with an optimized slime mold algorithm(SMA)to determine optimal structure parameters.Then,the realization method for the designed cylindrical coil by using the flexible printed circuit(FPC)technology is presented.Compared with traditional fabrication methods,this method has advantages in excellent flexibility and bending property,making the coils easier to be arranged in limited space.Moreover,the manufacturing process of the FPC technology via a specific cylindrical uniform magnetic field coil is discussed in detail,and the successfully realized coil is well tested in a verification system.By comparing the uniformity performance of the experimental coil with the simulation one,the effectiveness of the FPC technology in producing cylindrical coils has been well validated.
文摘针对复杂输电环境下机械臂多目标点路径规划效率低、路径代价高的问题,提出了基于改进的人工势场引导的知情快速扩展随机树算法(improved artificial potential field-informed rapidly-exploring random trees star,IAPF-IRRT^(*))来提升路径规划的性能。首先引入长方体斥力场模型改进传统人工势场中球形斥力场模型,建立输电环境下复杂障碍物的斥力场。然后采用位置均匀分布的椭球域改进IAPF-IRRT*算法中的椭圆域,避免复杂输电环境下采样点出现局部冗余,提高搜索效率。最后引入三角寻优法优化路径中的冗余节点并结合三次样条插曲线对路径平滑处理。在三维简单、三维复杂和复杂输电环境这三组不同复杂程度的障碍物地图上进行验证,其结果表明:IAPF-IRRT*算法与标准RRT、RRT*算法相比,时间效率分别提升了44.8%~83.8%、68.3%~95.2%、26.5%~71.8%;路径代价分别降低了15.5%~35.0%、14.1%~35.3%、31.5%~43.5%;路径中的节点数量分别减少了75.6%~78.8%、75.0%~78.0%、70.4%~72.0%。
文摘针对传统人工势场法在多障碍物复杂环境的全局路径规划中出现的目标不可达、易陷入陷阱区域以及局部极小点问题,提出一种简化障碍物预测碰撞人工势场法(simplified obstacles and predict collision of artificial potential field method,SOPC-APF),算法引入预测碰撞思想,在机器人未进入陷阱区域或者极小点问题前做出决策;对于多障碍物的斥力与目标点的引力产生的合力使机器人陷入震荡,提出简化障碍物,即简化为影响范围内目标点一侧的受限障碍物;针对目标不可达问题,在碰撞预测基础上,设定虚拟目标点,经改进的斥力函数引导机器人快速生成一条平滑、平稳、无碰撞的路径。通过与传统算法、改进APF算法以及改进蚁群算法的仿真对比实验表明,SOPC-APF有效解决了人工势场法不适用于多障碍物复杂环境的问题,以及传统算法容易陷入陷阱区域和局部极小点问题。
基金Project supported by the Natural Science Foundation of the Ministry of Science and Technology of China (Grant No.2011ZX05008004)the Science Fund of the Committee of Science and Technology of Beijing,China
文摘Significant high magnetic gradient field strength is essential to obtaining high-resolution images in a benchtop mag- netic resonance imaging （BT-MRI） system with permanent magnet. Extending minimum wire spacing and maximum wire width of gradient coils is one of the key solutions to minimize the maximum current density so as to reduce the local heating and generate higher magnetic field gradient strength. However, maximum current density is hard to optimize together with field linearity, stored magnetic energy, and power dissipation by the traditional target field method. In this paper, a new multi-objective method is proposed to optimize the maximum current density, field linearity, stored magnetic energy, and power dissipation in MRI gradient coils. The simulation and experimental results show that the minimum wire spacings are improved by 159% and 62% for the transverse and longitudinal gradient coil respectively. The maximum wire width increases from 0.5 mm to 1.5 mm. Maximum gradient field strengths of 157 mT/m and 405 mT/m for transverse and lon- gitudinal coil are achieved, respectively. The experimental results in BT-MRI instrument demonstrate that the MRI images with in-plane resolution of 50 ~tm can be obtained by using the designed coils.
