Innovative use of HfO_(2)-based high-dielectric-permittivity materials could enable their integration into few-nanometre-scale devices for storing substantial quantities of electrical charges,which have received wides...Innovative use of HfO_(2)-based high-dielectric-permittivity materials could enable their integration into few-nanometre-scale devices for storing substantial quantities of electrical charges,which have received widespread applications in high-storage-density dynamic random access memory and energy-efficient complementary metal-oxide-semiconductor devices.During bipolar high electric-field cycling in numbers close to dielectric breakdown,the dielectric permittivity suddenly increases by 30 times after oxygen-vacancy ordering and ferroelectric-to-nonferroelectric phase transition of near-edge plasma-treated Hf_(0.5)Zr_(0.5)O_(2) thin-film capacitors.Here we report a much higher dielectric permittivity of 1466 during downscaling of the capacitor into the diameter of 3.85μm when the ferroelectricity suddenly disappears without high-field cycling.The stored charge density is as high as 183μC cm^(−2) at an operating voltage/time of 1.2 V/50 ns at cycle numbers of more than 10^(12) without inducing dielectric breakdown.The study of synchrotron X-ray micro-diffraction patterns show missing of a mixed tetragonal phase.The image of electron energy loss spectroscopy shows the preferred oxygen-vacancy accumulation at the regions near top/bottom electrodes as well as grain boundaries.The ultrahigh dielectric-permittivity material enables high-density integration of extremely scaled logic and memory devices in the future.展开更多
针对实际档案库房操作空间的动态约束性,常见的运动规划算法难以满足快速在线规划的问题,分别从规划速度和动态空间在线规划两个方向进行研究.首先,提出一种新型快速搜索随机树法(rapidly-exploring random trees,RRT),基于剪枝和路径...针对实际档案库房操作空间的动态约束性,常见的运动规划算法难以满足快速在线规划的问题,分别从规划速度和动态空间在线规划两个方向进行研究.首先,提出一种新型快速搜索随机树法(rapidly-exploring random trees,RRT),基于剪枝和路径细化策略能够大幅减少无用节点计算和冗余路径运动.其次,将人工势场法与RRT算法相结合,新节点拓展时会受到期望为当前势场合力的高斯分布的影响,在满足对动态障碍物的在线运动规划的同时提高了算法的拓展能力.最后,通过仿真结果证明,新型RRT算法在拓展效率上的高效性和混合运动规划算法在动态规划和探索效率上的优越性.展开更多
时变干扰问题在风洞流场控制中较为常见,其中典型的例子是跨声速连续变迎角试验中迎角变化对马赫数控制造成的干扰。为提高存在时变干扰情况下的流场控制精度,本文创新性地提出一种新型的前馈+反馈复合控制方案。该方案中,前馈控制采用...时变干扰问题在风洞流场控制中较为常见,其中典型的例子是跨声速连续变迎角试验中迎角变化对马赫数控制造成的干扰。为提高存在时变干扰情况下的流场控制精度,本文创新性地提出一种新型的前馈+反馈复合控制方案。该方案中,前馈控制采用基于超前校正的增量式扩张状态观测器(Lead Correction based Incremental Extend State Observer,LIESO),反馈控制则采用增量式比例积分(Proportional–Integral,PI)控制。针对1.2 m跨超声速风洞连续变迎角试验,对该复合控制方法进行了试验验证。结果表明:LIESO+PI复合控制能够有效抑制时变干扰,鲁棒性良好,在不同模型堵塞度和试验马赫数下均表现出较好的适应性,具备较高的工程应用价值。展开更多
基金supported by the National Key Basic Research Program of China (2022YFA1402904)Basic Research Project of Shanghai Science and Technology Innovation Action (grant number 24CL2900900)the National Natural Science Foundation of China (grant number 61904034)
文摘Innovative use of HfO_(2)-based high-dielectric-permittivity materials could enable their integration into few-nanometre-scale devices for storing substantial quantities of electrical charges,which have received widespread applications in high-storage-density dynamic random access memory and energy-efficient complementary metal-oxide-semiconductor devices.During bipolar high electric-field cycling in numbers close to dielectric breakdown,the dielectric permittivity suddenly increases by 30 times after oxygen-vacancy ordering and ferroelectric-to-nonferroelectric phase transition of near-edge plasma-treated Hf_(0.5)Zr_(0.5)O_(2) thin-film capacitors.Here we report a much higher dielectric permittivity of 1466 during downscaling of the capacitor into the diameter of 3.85μm when the ferroelectricity suddenly disappears without high-field cycling.The stored charge density is as high as 183μC cm^(−2) at an operating voltage/time of 1.2 V/50 ns at cycle numbers of more than 10^(12) without inducing dielectric breakdown.The study of synchrotron X-ray micro-diffraction patterns show missing of a mixed tetragonal phase.The image of electron energy loss spectroscopy shows the preferred oxygen-vacancy accumulation at the regions near top/bottom electrodes as well as grain boundaries.The ultrahigh dielectric-permittivity material enables high-density integration of extremely scaled logic and memory devices in the future.
文摘针对实际档案库房操作空间的动态约束性,常见的运动规划算法难以满足快速在线规划的问题,分别从规划速度和动态空间在线规划两个方向进行研究.首先,提出一种新型快速搜索随机树法(rapidly-exploring random trees,RRT),基于剪枝和路径细化策略能够大幅减少无用节点计算和冗余路径运动.其次,将人工势场法与RRT算法相结合,新节点拓展时会受到期望为当前势场合力的高斯分布的影响,在满足对动态障碍物的在线运动规划的同时提高了算法的拓展能力.最后,通过仿真结果证明,新型RRT算法在拓展效率上的高效性和混合运动规划算法在动态规划和探索效率上的优越性.
文摘时变干扰问题在风洞流场控制中较为常见,其中典型的例子是跨声速连续变迎角试验中迎角变化对马赫数控制造成的干扰。为提高存在时变干扰情况下的流场控制精度,本文创新性地提出一种新型的前馈+反馈复合控制方案。该方案中,前馈控制采用基于超前校正的增量式扩张状态观测器(Lead Correction based Incremental Extend State Observer,LIESO),反馈控制则采用增量式比例积分(Proportional–Integral,PI)控制。针对1.2 m跨超声速风洞连续变迎角试验,对该复合控制方法进行了试验验证。结果表明:LIESO+PI复合控制能够有效抑制时变干扰,鲁棒性良好,在不同模型堵塞度和试验马赫数下均表现出较好的适应性,具备较高的工程应用价值。
