摘要：对于三片式照相物镜的设计,首先,根据设计要求从已有专利、文献中选取一个与其相近的系统作为原始系统。其次,利用Zemax光学设计与仿真软件对初始结构进行整体缩放,直至符合设计要求值。最后,分别通过优化镜头诸面的面形参数及调制传递函数(MTF)曲线对像差进行优化与校正。得到一款焦距为30 mm,半视场角为25°,F数为4的三片式照相物镜。该镜头由1个弯月凸透镜、1个双凹透镜和1个双凸透镜组成。设计结果表明:整个光学系统为对称式结构,结构简单且紧凑,总轴长度为33.83 mm,光学系统的弥散斑较小,最大畸变小于0.017。

摘要：Tunneling heterostructures are emerging as a versatile architecture for photodetection due to their advanced optical sensitivity,tailorable detection band,and wellbalanced photoelectric ***,the existing tunneling heterostructures are mainly operated in the visible wavelengths and have been rarely investigated for the nearinfrared ***,we report the design and realization of a novel broken-gap tunneling heterostructure by combining WSe2 and Bi2Se3,which is able to realize the simultaneous visible and near-infrared detection because of the complementary bandgaps of WSe2 and Bi2Se3(1.46 and 0.3 e V respectively).Thanks to the realigned band structure,the heterostructure shows an ultralow dark current below picoampere and a high tunneling-dominated *** photodetector based on our tunneling heterostructure exhibits a superior specific detectivity of 7.9×1012Jones for a visible incident of 532 nm and 2.2×1010Jones for a 1456 nm nearinfrared *** study demonstrates a new band structure engineering avenue for the construction of van der Waals tunneling heterostructures for high-performance wide band photodetection.

摘要：针对脉冲推力航天器轨道追逃博弈问题,提出一种基于强化学习的决策方法,实现追踪星在指定时刻抵近至逃逸星的特定区域,其中两星都具备自主博弈能力.首先,充分考虑追踪星和逃逸星的燃料约束、推力约束、决策周期约束、运动范围约束等实际约束条件,建立锥形安全接近区及追逃博弈过程的数学模型;其次,为了提升航天器面对不确定博弈对抗场景的自主决策能力,以近端策略优化(Proximal policy optimization,PPO)算法框架为基础,采用左右互搏的方式同时训练追踪星和逃逸星,交替提升两星的决策能力;在此基础上,为了在指定时刻完成追逃任务,提出一种终端诱导的奖励函数设计方法,基于CW(Clohessy Wiltshire)方程预测两星在终端时刻的相对误差,并将该预测误差引入奖励函数中,有效引导追踪星在指定时刻进入逃逸星的安全接近区.与现有基于当前误差设计奖励函数的方法相比,所提方法能够有效提高追击成功率.最后,通过与其他学习方法仿真对比,验证提出的训练方法和奖励函数设计方法的有效性和优越性.

摘要：摄制于1992年的电影《阏里人家》延续了中国第四代导演吴贻弓一贯的表达方式,以普通家庭为切入口,以日常生活的横断面为表现形态,映射出国家与时代的变迁、民族历史与文化传统的厚度、道德与责任的冲突。影片的叙事策略与镜语体系也在传承中愈显圆熟,现实题材与诗意特征相得益彰,流畅的时空转换、造型性的镜头运用、精心处理的影片色调与细节共同营造了具有丰厚韵味的影像空间。

摘要：基于直线发电机的直驱式波浪发电系统可以直接将波浪能转化为电能,具有结构简单和效率高等优点。然而,由于波浪速度较低,造成直驱式波浪发电机体积庞大和功率密度较低,为解决这个问题,该文基于磁齿轮和磁场调制电机的增速效应,结合横向磁通电机的横向磁路,提出一种用于波浪发电的新型磁场调制横向磁通直线发电机结构。首先,介绍发电机的结构、工作原理和磁场调制机理,采用多目标优化法对发电机电磁结构进行优化设计;研究不同极槽配比和调制器倾斜角度对发电机电磁性能的影响;计算发电机对应不同电枢电流的损耗和效率,对比该结构、交叉绕组结构和现有文献中横向磁通直线电机的功率密度;最后,制造样机并搭建实验测试平台,测量发电机推力和反电势,证明所提出拓扑结构的合理性和有限元计算结果的准确性。

摘要：The low efficiency of photogenerated carrier separation,and the poor adsorption and activation ability of CO_(2)on the surface of photocatalyst were the key problems to limit the efficiency of photocatalytic CO_(2)***,maximally accelerating the immigration of photogenerated charges d increasing the number of active sites are critical points to boost the overall performance of photocatalytic CO_(2)***,it is still huge *** this work,the Ni-doped ultrathin Bi_(4)O_(5)Br_(2)nanosheets,which was successfully prepared by hydrothermal and ultrasonic chemical stripping methods,exhibited efficient photocatalytic conversion of CO_(2)to *** results of experiments and theoretical calculations indicated that the doped Ni^(2+)significantly increased the crystal dipole moment of Bi_(4)O_(5)Br_(2)in y direction(from 0 to 0.096 e?),which enhanced the polarized electric field strength inside Bi_(4)O_(5)Br_(2),and further promoted the immigration of photogenerated ***,the ultrathin structure and doped Ni^(2+)synergistically increased the number of active sites,thereby promoting the adsorption and activation of CO_(2)molecules,as evidenced by experimental and theoretical results *** result,The CO yield was as high as 26.57μmol g–1 h–1 for the prepared Ni-doped ultrathin Bi_(4)O_(5)Br_(2)nanosheets under full spectrum light irradiation,which was 9.48 times that of Bi_(4)O_(5)Br_(2).Therefore,it is of great scientific significance in this study to explore strategies to promote the separation of photogenerated carriers and enhance the adsorption and activation ability of CO_(2)on the surface.

摘要：Normal photocatalysts cannot effectively remove low-concentration NO because of the high recombination rate of the photogenerated *** overcome this problem,S-scheme composites have been developed to fabricate ***,a novel S-scheme Sb2WO6/g-C3N4 nanocomposite was fabricated by an ultrasound-assisted method,which exhibited excellent performance for photocatalytic ppb-level NO *** with the pure constituents of the nanocomposite,the as-prepared 15%-Sb2WO6/g-C3N4 photocatalyst could remove more than 68%continuous-flowing NO(initial concentration:400 ppb)under visible-light irradiation in 30 *** findings of the trapping experiments confirmed that•O2^–and h+were the important active species in the NO oxidation ***,the transient photocurrent response and PL spectroscopy analyses proved that the unique S-scheme structure of the samples could enhance the charge separation *** situ DRIFTS revealed that the photocatalytic reaction pathway of NO removal over the Sb2WO6/g-C3N4 nanocomposite occurred via an oxygen-induced *** present work proposes a new concept for fabricating efficient photocatalysts for photocatalytic ppb-level NO oxidation and provides deeper insights into the mechanism of photocatalytic NO oxidation.

摘要：从功能上看,传统仪式大致可分为“为解决人与人之关系而产生的仪式”和“为解决人与自然之关系而产生的仪式”两个大类。在许多人看来,传统仪式似乎包含一些“迷信”内容,但实际上,传统仪式在构建和谐社会、建设环境友好型社会和传承人类文明方面一直发挥着重要作用。要想保护好这类非物质文化遗产,一定要抓住重点,重点保护好那些与传统仪式类遗产息息相关的食品制作技术、仪式用装制作技术、仪式装饰装潢技术以及文学艺术,特别是其中富含的民族精神与传统美德。从田野实践看,当前对传统仪式类遗产的认识还存在许多误区,例如人们经常误将“仪式”当“迷信”,误将“信仰”当“非遗”,误将“配角”当“主角”以及误将“现产”当“遗产”等问题,这些问题不解决,传统仪式类遗产保护就很难进入通途。

摘要：本文研究了对非合作目标的自主绕飞控制问题,提出了基于混合状态机的自主绕飞多模态控制方法。首先,根据自主绕飞任务目标和轨道安全性分析,定义了远程接近、近程接近、相对位置保持、绕飞转移、碰撞规避、撤离等状态以及各个状态的控制目标。其次,为了实现航天器各个行为状态之间的协调转换与控制,建立混合状态机模型对各个状态进行自主管理和监控,设计了状态之间跳转的转换函数。然后,根据不同状态的控制目标,设计了多模态运动规划与控制策略,实现多模态自适应有限时间跟踪控制。最后,对本文所提出的自主绕飞控制方法进行了仿真验证,仿真结果说明了所提出的方法的有效性。

摘要：针对提高空间目标相对轨道确定精度的问题,研究了在主航天器轨道运动受限时,通过设计和优化辅航天器相对轨道要素的航天器编队优化方法。首先,介绍了基于扩展卡尔曼滤波的双视线测量相对轨道确定方法;之后,通过研究双视线测量下的空间目标定位误差变化规律,得到了减小定位误差的角度条件;然后,通过分析该角度条件和辅航天器相对轨道要素的关系,设计并采用遗传算法优化了辅航天器相对轨道;最后,数学仿真结果表明,设计的编队可保证目标相对位置估计误差收敛,优化后的编队可使目标相对位置估计误差减小至0.3 km且不超过1.2 km。