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深度确定性策略梯度下运动目标识别及无人机跟随
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作者 刘欣 张倩飞 +1 位作者 刘成宇 高涵 《西安工程大学学报》 CAS 2024年第4期9-17,共9页
针对无人机(unmanned aerial vehicle,UAV)平台采集运动目标图像信息过程中因UAV自身的飞行状态、环境的干扰、目标的随机性等原因易产生运动目标丢失等问题,提出了一种基于运动目标识别的深度确定性策略梯度(deep deterministic policy... 针对无人机(unmanned aerial vehicle,UAV)平台采集运动目标图像信息过程中因UAV自身的飞行状态、环境的干扰、目标的随机性等原因易产生运动目标丢失等问题,提出了一种基于运动目标识别的深度确定性策略梯度(deep deterministic policy gradient,DDPG)算法UAV跟随方法。面向高速公路的车辆目标,分析了UAV高度、位姿与高速车辆运动之间的关系,建立了移动平台目标检测帧率的速度自适应模型,根据目标的运动状态计算能够相匹配UAV的飞行状态,实时修正飞行姿态与速度,使UAV能够保持与目标的相对位置和角度。继而基于DDPG算法价值网络估计UAV在不同状态下采取特定动作的价值,策略网络生成UAV在给定状态下采取动作的策略,给予UAV飞行高度、速度控制参数用于目标跟踪,使UAV能够根据目标的运动变化自动调节飞行状态,实现运动目标的自适应跟随。仿真实验表明:DDPG算法能够提供稳定的飞行姿态数据,为UAV的跟随任务提供了可靠的控制基础;通过在真实场景下实验验证,UAV能够实时跟踪速度范围0~33 m/s、半径为120 m的圆形面积内的地面运动目标,且在续航范围内能够实现持续稳定跟随。 展开更多
关键词 四轴飞行器 高速公路 动态规划 深度确定性策略梯度 目标跟踪
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Role of Liver Progenitor Cell in Liver Regeneration Cellular Cross-Talks and Signals
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作者 陈黎黎 张倩飞 孔晓妮 《Journal of Shanghai Jiaotong university(Science)》 EI 2015年第2期251-256,共6页
The liver is well known for its ability to regenerate in response to injury. After partial hepatectomy and some chemicals induced acute liver injury, existing hepatocytes can expand to repair the liver function. While... The liver is well known for its ability to regenerate in response to injury. After partial hepatectomy and some chemicals induced acute liver injury, existing hepatocytes can expand to repair the liver function. While adult liver stem/progenitor cells(LPCs) are evoked and differentiate into functional hepatocytes and cholangiocytes to compensate the damaged liver once hepatocyte proliferation is severely impaired. A number of evidences suggest that adjacent hepatic stellate cells(HSCs) or invading leukocytes may be involved in LPCs directed regeneration through governning two major events including fibrogenic and inflammatory responses respectively or simultaneously. As such, a microenvironment(or "niche") composed of different cell sources or factors presents diversity, which eventually mediates LPCs response to biliary or hepatocellular regeneration. This mini review aims at summarizing the latest development on the roles of HSCs, macrophages and lymphocytes as well as corresponding signaling pathways in liver progenitor cells mediated biliary and hepatocellular regeneration, and discussing therapeutic potential of liver progenitor cells in hepatic diseases. 展开更多
关键词 liver stem/progenitor cell(LPCs) liver regeneration hepatic stellate cells(HSCs) MACROPHAGES LYMPHOCYTES cellular cross talks li
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