近年来,美国家庭教育指导服务取得了社会认可并成为全球家庭教育指导工作的风向标,尤其是循证家庭教育指导服务成效显著。其中,“父母即教师”(Parent As Teachers,简称PAT)项目是美国循证家庭教育指导服务的杰出代表,其以改进家庭教育...近年来,美国家庭教育指导服务取得了社会认可并成为全球家庭教育指导工作的风向标,尤其是循证家庭教育指导服务成效显著。其中,“父母即教师”(Parent As Teachers,简称PAT)项目是美国循证家庭教育指导服务的杰出代表,其以改进家庭教育质量为主旨、以科学的循证模型为基础、收集丰富的实证数据来开展有针对性的家庭教育指导服务。展开更多
Free-space laser communication is characterized by high communication speed, strong anti-jamming ability, high confidentiality, and flexible configuration. In this paper, a pointing, acquisition, and tracking (PAT) sy...Free-space laser communication is characterized by high communication speed, strong anti-jamming ability, high confidentiality, and flexible configuration. In this paper, a pointing, acquisition, and tracking (PAT) system based on a two-stage (i.e., coarse and fine) composite tracking mechanism is proposed to solve the optical axis alignment problem, which is common in free-space laser communications. The acquisition probability of the PAT system is ensured by designing two tracking modules, a coarse tracking module which combines passive damping with active suppression and a fine tracking module based on an electromagnetic galvanometer. Both modules are combined by using a dynamic scanning mechanism based on the gyroscope signal. Finally, a free-space laser communication test with a long range and a high speed is conducted by two fixed-wing Y12 aircrafts equipped with the proposed PAT system. Experimental results show that the coarse tracking precision of the airborne PAT system is 10 μrad (1σ), and the fine tracking precision is 10μrad (1σ) during flights which are much improved as compared with the indoor tests. This indicates that the system can achieve a high precision for PAT during high-speed and long-range laser communications in the free-space. This also verifies the tracking capability and the environmental adaptability of the proposed laser communication PAT system.展开更多
枯草杆菌芽孢是极难被杀灭的细菌之一,为探究山梨酸钾与压力辅助热杀菌(pressure assisted thermal sterilization,PATS)对枯草杆菌芽孢的联合作用效果,该研究以OD600值(optical density at 600 nm)、OD_(260)值(optical density at 260...枯草杆菌芽孢是极难被杀灭的细菌之一,为探究山梨酸钾与压力辅助热杀菌(pressure assisted thermal sterilization,PATS)对枯草杆菌芽孢的联合作用效果,该研究以OD600值(optical density at 600 nm)、OD_(260)值(optical density at 260 nm)、OD_(280)值(optical density at 280 nm)、2,6-吡啶二羧酸释放率表征芽孢内容物的释放情况,扫描电镜、流式细胞术、傅里叶红外光谱仪、激光粒度仪检测芽孢结构变化情况。结果表明,山梨酸钾强化了PATS的杀菌效果,200 MPa-75℃处理杀灭了2.63 lg CFU/mL芽孢,添加2 g/L山梨酸钾后,杀灭了3.24 lg CFU/mL芽孢。较单独PATS处理,添加山梨酸钾后,促进了芽孢内容物的释放,内膜通透性增加,芽孢粒径显著减小,内膜、细胞壁等结构受损程度加剧。同时,Na^(+)/K^(+)-ATPase活力显著降低,膜电位平衡被破坏,基本生理代谢功能紊乱。总之,PATS结合山梨酸钾对枯草芽孢杆菌芽孢有协同杀菌作用,且随着山梨酸钾添加量或温度的升高而增强,有利于促进该技术在食品杀菌中的应用。展开更多
为了提高空间光通信PAT系统的扰动抑制能力,提出了一种基于扰动观测器的控制方法。该方法首先对PAT系统进行分析,得到简化的控制模型,然后利用扰动观测器从电机转动位置和光斑位置中观测出扰动,最后将扰动等效补偿量加入到电流环前的综...为了提高空间光通信PAT系统的扰动抑制能力,提出了一种基于扰动观测器的控制方法。该方法首先对PAT系统进行分析,得到简化的控制模型,然后利用扰动观测器从电机转动位置和光斑位置中观测出扰动,最后将扰动等效补偿量加入到电流环前的综合点。精跟踪系统的仿真实验结果表明:相比常规的PD控制器,加入扰动观测器使扰动隔离度在电机电流饱和前的几乎所有频率处都得到了提升,最优情况可达到28.2 d B;同时,该方法具有很强的鲁棒性,在系统物理参数变化15%时扰动隔离度依然比没有使用扰动观测器时提高了至少1倍。所述的控制方法显著提高了PAT系统的抗扰动性能,对大范围与高动态的精密光电跟踪系统有一定的参考价值。展开更多
文摘近年来,美国家庭教育指导服务取得了社会认可并成为全球家庭教育指导工作的风向标,尤其是循证家庭教育指导服务成效显著。其中,“父母即教师”(Parent As Teachers,简称PAT)项目是美国循证家庭教育指导服务的杰出代表,其以改进家庭教育质量为主旨、以科学的循证模型为基础、收集丰富的实证数据来开展有针对性的家庭教育指导服务。
基金the National Natural Science Foundation of China (Grant No. 51505087).
文摘Free-space laser communication is characterized by high communication speed, strong anti-jamming ability, high confidentiality, and flexible configuration. In this paper, a pointing, acquisition, and tracking (PAT) system based on a two-stage (i.e., coarse and fine) composite tracking mechanism is proposed to solve the optical axis alignment problem, which is common in free-space laser communications. The acquisition probability of the PAT system is ensured by designing two tracking modules, a coarse tracking module which combines passive damping with active suppression and a fine tracking module based on an electromagnetic galvanometer. Both modules are combined by using a dynamic scanning mechanism based on the gyroscope signal. Finally, a free-space laser communication test with a long range and a high speed is conducted by two fixed-wing Y12 aircrafts equipped with the proposed PAT system. Experimental results show that the coarse tracking precision of the airborne PAT system is 10 μrad (1σ), and the fine tracking precision is 10μrad (1σ) during flights which are much improved as compared with the indoor tests. This indicates that the system can achieve a high precision for PAT during high-speed and long-range laser communications in the free-space. This also verifies the tracking capability and the environmental adaptability of the proposed laser communication PAT system.
文摘枯草杆菌芽孢是极难被杀灭的细菌之一,为探究山梨酸钾与压力辅助热杀菌(pressure assisted thermal sterilization,PATS)对枯草杆菌芽孢的联合作用效果,该研究以OD600值(optical density at 600 nm)、OD_(260)值(optical density at 260 nm)、OD_(280)值(optical density at 280 nm)、2,6-吡啶二羧酸释放率表征芽孢内容物的释放情况,扫描电镜、流式细胞术、傅里叶红外光谱仪、激光粒度仪检测芽孢结构变化情况。结果表明,山梨酸钾强化了PATS的杀菌效果,200 MPa-75℃处理杀灭了2.63 lg CFU/mL芽孢,添加2 g/L山梨酸钾后,杀灭了3.24 lg CFU/mL芽孢。较单独PATS处理,添加山梨酸钾后,促进了芽孢内容物的释放,内膜通透性增加,芽孢粒径显著减小,内膜、细胞壁等结构受损程度加剧。同时,Na^(+)/K^(+)-ATPase活力显著降低,膜电位平衡被破坏,基本生理代谢功能紊乱。总之,PATS结合山梨酸钾对枯草芽孢杆菌芽孢有协同杀菌作用,且随着山梨酸钾添加量或温度的升高而增强,有利于促进该技术在食品杀菌中的应用。
文摘为了提高空间光通信PAT系统的扰动抑制能力,提出了一种基于扰动观测器的控制方法。该方法首先对PAT系统进行分析,得到简化的控制模型,然后利用扰动观测器从电机转动位置和光斑位置中观测出扰动,最后将扰动等效补偿量加入到电流环前的综合点。精跟踪系统的仿真实验结果表明:相比常规的PD控制器,加入扰动观测器使扰动隔离度在电机电流饱和前的几乎所有频率处都得到了提升,最优情况可达到28.2 d B;同时,该方法具有很强的鲁棒性,在系统物理参数变化15%时扰动隔离度依然比没有使用扰动观测器时提高了至少1倍。所述的控制方法显著提高了PAT系统的抗扰动性能,对大范围与高动态的精密光电跟踪系统有一定的参考价值。
