【摘 要】
：
It is well known that cats have fascinating eyes with various colors,such as green,blue,and brown.In addition,they possess strong night vision ability,which can distinguish things clearly even in a poor light environment.These drive us to reveal the secre
【机 构】
：
Institute of Electromagnetics and Acoustics and Department of Physics,Xiamen University,Xiamen 36100
论文部分内容阅读
It is well known that cats have fascinating eyes with various colors,such as green,blue,and brown.In addition,they possess strong night vision ability,which can distinguish things clearly even in a poor light environment.These drive us to reveal the secrets behind them.In fact,cats\' eyes can be considered as special lenses[which we would like to mimic by using a Luneburg lens].We make an analysis of the role of photonic crystals behind the lens and demonstrate that the integration of photonic crystals into Luneburg lens can be regarded as a retroreflector and greatly improve the light focusing intensity of the lens in a broad band of frequencies.This wonderful bioinspired phenomenon is expected to design more interesting and serviceable devices by combining photonic crystals with transformation optics.
其他文献
氧枪作为转炉炼钢的重要设备,氧枪使用寿命低,转炉因氧枪黏钢频繁更换,严重影响生产的稳定顺行.对重钢210 t顶底复吹转炉氧枪黏钢原因进行分析,从装入量控制、加料方式、喷溅控制、枪位控制、炉型控制等方面查找原因.遵循前期早化渣、中期渣化透、后期渣作黏的原则,优化氧枪参数、优化冶炼工艺、稳定转炉炉型、控制液面标高,使氧枪黏钢得到有效控制,氧枪使用寿命得到很大提升,确保生产的稳定顺行.
We proposed an aperiodic laser beam distribution,in which the laser beams are placed along a Fermat spiral,to suppress the sidelobe power in the coherent beam combining.Owing to the changed distances between two consecutive beams,the conditions of the sid
We report the observation of second order Bragg resonance[2nd-OBG]produced by tilted fiber gratings[TFGs]fabricated using phase mask UV inscription.The theoretical analysis has revealed that the generation of high order Bragg resonance of gratings is indu
Recent advances in the research of vortex beams,structured beams carrying orbital angular momentum[OAM],have revo-lutionized the applications of light beams,such as advanced optical manipulations,high-capacity optical communications,and super-resolution i
The chloroplast NADH dehydrogenase-like(NDH)complex,homologous to respiratory complex I,participates in photosystem I cyclic electron flow(PSI-CEF)and chlororespiration in photosynthesis.Phylogenetic analyses indicated that Zostera marina,a widely distrib
以2008-2019年长三角、珠三角、京津冀城市群为研究对象,运用投入产出关系构建产业集群网络,在测度受2008年金融危机冲击后的城市经济韧性的基础上,实证检验了集群网络结构特征对城市经济韧性的直接影响与创新水平的中介机制.研究发现:产业集群网络密度与关联度因加剧风险传导等原因对城市经济韧性产生负向影响;产业集群网络特征对经济韧性的影响均能通过刺激城市创新,进而推动产业转型升级,提升城市经济韧性;集群企业间的网络特征主要通过促进低技术、高实用的创新进而提升城市经济韧性.
将休闲生活满意度分为休闲活动满意度和休闲环境满意度两部分,选择南京、苏州、杭州、宁波、合肥五座城市为案例地,基于2020年五座城市居民休闲满意度问卷调查数据,运用探索性因子分析、优序图法和地理探测器等方法,对居民休闲生活满意度特征及影响机理进行实证分析,探究五座城市居民休闲制约因素的维度构成,以及个人休闲活动满意度和城市休闲环境满意度特征排序,分析休闲制约因素和个人属性因素对休闲生活满意度的影响效应.重点阐释了居民休闲活动体验和城市休闲环境认知的因素差异及机理,可为长三角地区城市休闲生活高质量发展及区域一
Multi-band signal propagation and processing play an important role in quantum communications and quantum computing.In recent years,optical nonreciprocal devices such as an optical isolator and circulator are proposed via various configurations of atoms,m
We demonstrate an all-fiber-based photonic microwave generation with 10-15 frequency instability.The system consists of an ultra-stable laser by optical fiber delay line,an all-fiber-based “figure-of-nine” optical frequency comb,a high signal-to-noise rat
将人口普查和抽样调查数据匹配到城市层面,从高、低技能互补角度对异质性劳动力集聚的影响效果进行实证研究,为推进“人才新政”及加快产业结构升级提供经验证据.研究表明,高技能劳动力集聚能有效促进产业结构升级,集聚效应因城市发展水平而呈现明显区域差异,三线及以上城市或高竞争力城市高技能劳动力集聚对产业结构升级的影响系数比其他城市低.高—低技能劳动力共同集聚亦有显著正向作用,若忽视该影响,将高估高技能劳动力集聚的边际贡献.最后,通过市场规模甄别的实证策略发现,东部城市协调高—低技能劳动力共同集聚、中西部城市加快吸引