离轴反射系统设计的关键环节是确定适用初始结构并进行优化,一般从同轴结构或者专利库中寻找相似的结构开始优化,这往往需要耗费大量的时间。以Seidel像差理论为依据,研究了一种获取离轴四反系统初始结构的设计方法。在设计之初引入视...离轴反射系统设计的关键环节是确定适用初始结构并进行优化,一般从同轴结构或者专利库中寻找相似的结构开始优化,这往往需要耗费大量的时间。以Seidel像差理论为依据,研究了一种获取离轴四反系统初始结构的设计方法。在设计之初引入视场偏置,通过追迹近轴光线给出五种单色像差的初级Seidel像差表示。以Seidel像差绝对值最小化作为目标函数,同时加入对光学和系统结构上的限制条件构建含有约束条件的单目标非线性优化模型,并通过粒子群优化算法进行求解。在此基础上,通过MATLAB调用CODE V API接口,判断此视场偏置情况下是否满足无遮拦的条件,并从中挑选出满足条件的初始结构。设计了一款焦距为1200 mm,视场1.2°×20°,F数为6的离轴四反光学系统,系统结构布局紧凑,成像质量良好,各项指标均满足设计要求。展开更多
Silicon （Si） has the highest known theoretical specific capacity （3,590 mAh/g for Li1.5Si4, and 4,200 mAh/g for Li22Si4） as a lithium-ion battery anode, and has attracted extensive interest in the past few years. ...Silicon （Si） has the highest known theoretical specific capacity （3,590 mAh/g for Li1.5Si4, and 4,200 mAh/g for Li22Si4） as a lithium-ion battery anode, and has attracted extensive interest in the past few years. However, its application is limited by poor cyclability and early capacity fading due to significant volume changes during lithiation and delithiation processes. In this work, we report a coaxial silicon/anodic titanium oxide/silicon （Si-ATO--Si） nanotube array structure grown on a titanium substrate demonstrating excellent electrochemical cyclability. The ATO nanotube scaffold used for Si deposition has many desirable features, such as a rough surface for enhanced Si adhesion, and direct contact with the Ti substrate working as current collector. More importantly, our ATO scaffold provides a rather unique advantage in that Si can be loaded on both the inner and outer surfaces, and an inner pore can be retained to provide room for Si volume expansion. This coaxial structure shows a capacity above 1,500 mAh/g after 100 cycles, with less than 0.05% decay per cycle. Simulations show that this improved performance can be attributed to the lower stress induced on Si layers upon lithiation/delithiation compared with some other recently reported Si-based nanostructures.展开更多
文摘离轴反射系统设计的关键环节是确定适用初始结构并进行优化,一般从同轴结构或者专利库中寻找相似的结构开始优化,这往往需要耗费大量的时间。以Seidel像差理论为依据,研究了一种获取离轴四反系统初始结构的设计方法。在设计之初引入视场偏置,通过追迹近轴光线给出五种单色像差的初级Seidel像差表示。以Seidel像差绝对值最小化作为目标函数,同时加入对光学和系统结构上的限制条件构建含有约束条件的单目标非线性优化模型,并通过粒子群优化算法进行求解。在此基础上,通过MATLAB调用CODE V API接口,判断此视场偏置情况下是否满足无遮拦的条件,并从中挑选出满足条件的初始结构。设计了一款焦距为1200 mm,视场1.2°×20°,F数为6的离轴四反光学系统,系统结构布局紧凑,成像质量良好,各项指标均满足设计要求。
文摘Silicon （Si） has the highest known theoretical specific capacity （3,590 mAh/g for Li1.5Si4, and 4,200 mAh/g for Li22Si4） as a lithium-ion battery anode, and has attracted extensive interest in the past few years. However, its application is limited by poor cyclability and early capacity fading due to significant volume changes during lithiation and delithiation processes. In this work, we report a coaxial silicon/anodic titanium oxide/silicon （Si-ATO--Si） nanotube array structure grown on a titanium substrate demonstrating excellent electrochemical cyclability. The ATO nanotube scaffold used for Si deposition has many desirable features, such as a rough surface for enhanced Si adhesion, and direct contact with the Ti substrate working as current collector. More importantly, our ATO scaffold provides a rather unique advantage in that Si can be loaded on both the inner and outer surfaces, and an inner pore can be retained to provide room for Si volume expansion. This coaxial structure shows a capacity above 1,500 mAh/g after 100 cycles, with less than 0.05% decay per cycle. Simulations show that this improved performance can be attributed to the lower stress induced on Si layers upon lithiation/delithiation compared with some other recently reported Si-based nanostructures.
