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Single-row laser beam with energy strengthened ends for continuous scanning laser surface hardening of large metal components

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Science China(Physics,Mechanics & Astronomy) 2013年第6期56卷 1074-1078页

作者： LI ShaoXia YU Gang ZHANG JingChuan tan qiaofeng XU NingHan SUN PeiPei ZHENG CaiYun State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua University Key Laboratory of Mechanics in Advanced Manufacturing Institute of MechanicsChinese Academy of Sciences Beijing Institute of Spacecraft Environment Engineering

For laser surface hardening of metal components with large superficies,a binary grating is proposed to generate single-row laser beam with proportional-intensity diffractive *** obtain a uniform hardened band distribution and improve the wear resistance of the sample surface,the binary grating is designed to produce single-row laser beam with energy strengthened at the two *** profile of the laser beam spot was designed to be strip with high length-width ratio to improve the machining efficiency of the hardening of large surfaces.A new advantage is suggested to obtain proportional intensity spots with *** design results show that the diffractive efficiency of the binary grating is more than 70%,and the uniformity is less than 3%.The surface profile of the grating fabricated was measured,which shows that the fabrication error is less than 2%.The application of the binary grating in the laser surface hardening of metal components with large superficies is experimentally investigated,and the results show that the hardness distribution of the modified layer is more uniform than that hardened by Gaussian laser beam or array spots with equal intensity distribution.

关键词： binary grating beam shaping laser surface hardening diffraction

Helicity dependent directional surface plasmon polariton excitation using a metasurface with interfacial phase discontinuity

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Light(Science & Applications) 2013年第1期2卷 197-203页

作者： Lingling Huang Xianzhong Chen Benfeng Bai qiaofeng tan Guofan Jin Thomas Zentgraf Shuang Zhang School of Physics&Astronomy University of BirminghamBirmingham B152TTUK State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentsTsinghua UniversityBeijing 100084China Department of Physics University of PaderbornD-33098 PaderbornGermany

Surface plasmon polaritons(SPPs)have been widely exploited in various scientific communities,ranging from physics,chemistry to biology,due to the strong confinement of light to the metal *** many applications,it is important that the free space photon can be coupled to SPPs in a controllable *** this Letter,we apply the concept of interfacial phase discontinuity for circularly polarizations on a metasurface to the design of a novel type of polarization-dependent SPP unidirectional excitation at normal *** unidirectional excitation of SPPs along opposite directions is experimentally demonstrated at optical frequencies by simply switching the helicity of the incident *** approach,in conjunction with dynamic polarization modulation techniques,opens gateway towards integrated plasmonic circuits with electrically reconfigurable functionalities.

关键词： metamaterials metasurface surface plasmon

Miniaturized structured illumination microscopy with diffractive optics

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Photonics Research 2022年第5期10卷 1317-1324页

作者： GUOXUAN LIU NING XU HUAIDONG YANG qiaofeng tan GUOFAN JIN State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China

Structured illumination microscopy(SIM)is an advanced microscope system that provides superresolution capability with excellent imaging speed,which has become a practical tool for live-cell ***,the bulky size is blocking the application of SIM in wider study fields and ***,we developed a miniaturized SIM(Mini SIM)system that provided periodic illumination using a diffractive optical element(DOE)for the first *** optimized phase-only DOE generated the two-dimensional sinusoidal illumination by optical Fourier transform with an illuminating objective lens,which substantially simplified and miniaturized the illumination *** built up a Mini SIM prototype and demonstrated lateral superresolution imaging of fluorescence beads and A549 cell *** proposed Mini SIM greatly simplifies the experimental setup and may lead to important applications in bio-imaging.

关键词： illumination optics system

Active coherent control of nanoscale light confinement：Modulation of plasmonic modes and position of hotspots for surface-enhanced Raman scattering detection

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Nano Research 2017年第9期10卷 2934-2943页

作者： Zhendong Zhu Qixia Wang Fa Zeng Oubo You Sitian Gao Benfeng Bai qiaofeng tan Guofan Jin Qunqing Li Shoushan Fan Wei Li Yushu Shi Xueshen Wang Division ofNano Metrology and Materials Measurement National Institute ofMetrology Beijing 100028 China State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision Instrument Tsinghua University Beijing 100084 China Tsinghua-Foxconn Nanotechnology Research Center Tsinghua University Beijing 100084 China Laser Fusion Research Center China Academic of Engineering Physics Mianyang 621900 China

Multistep plasmonic nanostructures can induce the deep modulation of electromagnetic-field interactions on the nanoscale for positioning hotspots, and this generation of enhanced fields is important in many optical applications. In this article, a new strategy is proposed for fabricating a plasmonic doublestacked nanocone (DSC) nanostructure. In the DSC structure, a tunable plasmonic hybrid mode proceeds from the strong coupling of the plasmonic resonance of a fundamental cavity mode with a localized surface plasmon gap mode. In the nanostructure, the far-field response is deeply modulated and the hottest spots can be effectively positioned on the top surface of the DSC nanostructure. A controllable and cost-effective mask-reconfiguration technique for manufacturing the multiscale nanostructure is developed, which guarantees the generation of the introduced crucial stage on the DSC nanostructure. To evaluate the features of the plasmonic resonance, the DSC nanostructure is used as a surface-enhanced Raman scattering (SERS) substrate for detecting 4-mercaptopyridine molecules under specific excitation conditions. Its good performance, with an average measured SERS enhancement factor as high as 108, demonstrates its strong plasmonic-mode hybridization and extreme field enhancement.

关键词： surface plasmons mode hybridization positioning hotspot double-stacked nanocone (DSC) nanostructure surface-enhanced Raman scattering (SERS)

复杂水利-电力约束下梯级水电站短期多层级多目标优化调度研究

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水利学报 2023年第4期54卷 392-404页

作者：闻昕刘凡骞谭乔凤王浩河海大学水利水电学院江苏南京210098 河海大学水安全与水科学协同创新中心江苏南京210098 中国水利水电科学研究院北京100038

电网高强度的调峰调频任务和流域严格的水量调度要求,限制了梯级水电站调度运行的优化空间,造成水调电调协调困难、效益发挥不充分、机组长时间低效运行等问题。本文统筹考虑梯级水电站发电效益、调峰能力以及运行工况等目标,分别建立... 详细信息

电网高强度的调峰调频任务和流域严格的水量调度要求,限制了梯级水电站调度运行的优化空间,造成水调电调协调困难、效益发挥不充分、机组长时间低效运行等问题。本文统筹考虑梯级水电站发电效益、调峰能力以及运行工况等目标,分别建立电网、梯级、电站等不同层级的调度模型,研究多层级多目标协同优化机制,提出模型求解方法。通过不同层级之间相互嵌套,滚动向前,在复杂水利-电力约束条件下保证梯级电站的安全高效运行。以黄河上游水电基地为例,该方法可在保障黄河流域水量调度要求和西北地区高比例风光全额消纳前提下,将梯级水电站发电量提升2.75%,耗水率降低2.38%,机组低效运行时间降低50.64%,且有效提升水电调峰能力,平滑了火电出力过程,对于梯级水电科学调度和安全运行具有科学意义和实际价值。

关键词：短期调度多尺度嵌套经济运行负荷分配黄河上游水电基地

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考虑梯级水库库容补偿和设计洪水不确定性的汛限水位动态控制域研究

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工程科学与技术 2017年第1期49卷 60-69页

作者：谭乔凤雷晓辉王浩王旭四川大学水利水电学院四川成都610065 中国水利水电科学研究院北京100038

汛限水位动态控制本质上是风险调度的范畴,其最主要的风险源来自于入库洪水的不确定性。不仅包括由于预报误差带来的实时调度风险,还包括由于设计阶段对于设计洪水不确定性考虑不周而存在的潜在防洪风险。本文针对梯级水库,提出了一种... 详细信息

汛限水位动态控制本质上是风险调度的范畴,其最主要的风险源来自于入库洪水的不确定性。不仅包括由于预报误差带来的实时调度风险,还包括由于设计阶段对于设计洪水不确定性考虑不周而存在的潜在防洪风险。本文针对梯级水库,提出了一种考虑库容补偿和设计洪水不确性的汛限水位动态控制域求解新方法。通过分析梯级水库库容补偿调度原理,定义了水库极限汛限水位上限值,并给出了考虑设计洪水不确定性的防洪风险定量表达式。以Copula函数为工具建立上游和区间天然来水的联合概率密度函数,求出下游遭遇某一设计洪水时,上游可能出现的洪水范围,从而得到考虑梯级水库调蓄作用的不确定性设计洪水。通过反复迭代计算最终得到兼顾防洪风险与兴利效益的汛限水位动态控制域。将该方法运用在考虑潘口库容补偿作用的黄龙滩汛限水位动态控制域计算中,并与同频率法和典型年法比较,得到以下结论:1)所提方法能通过挖掘历史洪水信息,为模拟梯级水库设计洪水不确定性提供参考信息;2)相对于同频率法和典型年法,所提方法推求的汛限水位动态控制域更加的安全;3)黄龙滩水库汛期运行水位可以从[240,247]m变为[240,248.21]m。可使汛期来水较多的2000年和来水较少的1994年分别增加发电量0.13和0.11×108k W·h。所提方法能充分考虑梯级水库库容补偿和设计洪水的不确定性,能得到不增加防洪风险的水库汛限水位动态控制域。

关键词：汛限水位动态控制域库容补偿不确定性风险

光谱色散匀滑技术与衍射光学器件联用性能的空间频谱分析

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光子学报 2006年第9期35卷 1384-1387页

作者：谭峭峰严瑛白金国藩清华大学精密仪器系精密测试技术与仪器国家重点实验室北京100084

基于空间频谱分析方法,建立了光谱色散匀滑技术(SSD:SmoothingbySpectralDispersion)与衍射光学器件(DOE:DiffractiveOpticalElement)联用性能的简化分析模型,为SSD与DOE联用时,SSD参量的优化提供了理论依据.数值模拟了SSD各参量,包括... 详细信息

基于空间频谱分析方法,建立了光谱色散匀滑技术(SSD:SmoothingbySpectralDispersion)与衍射光学器件(DOE:DiffractiveOpticalElement)联用性能的简化分析模型,为SSD与DOE联用时,SSD参量的优化提供了理论依据.数值模拟了SSD各参量,包括脉冲时间、调制频率、位相调制系数、光栅线色散系数等对束匀滑性能的影响.模拟结果表明,SSD参量经过优化选取,且波前畸变随时间快速变化时,能获得良好的束匀滑性能.

关键词：衍射光学器件束匀滑光谱色散平滑空间频谱

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基于环形光束整形的衍射光学元件的精确设计

光学学报 2019年第3期39卷 84-89页

作者：杨美霞孔哲谭峭峰任钢薛亮平西南技术物理研究所四川成都610041 清华大学精密仪器系北京100084

提出一种改进的Gerchberg-Saxton(G-S)算法,实现了基于环形光束的衍射光学元件的精确设计。所提算法可以确保输出平面上有小的采样间隔,起到了抑制散斑的作用;与未采用散斑抑制的常规的改进G-S算法相比,所提算法得到了更高性能的均匀光... 详细信息

提出一种改进的Gerchberg-Saxton(G-S)算法,实现了基于环形光束的衍射光学元件的精确设计。所提算法可以确保输出平面上有小的采样间隔,起到了抑制散斑的作用;与未采用散斑抑制的常规的改进G-S算法相比,所提算法得到了更高性能的均匀光斑;仿真结果和实验结果一致。

关键词：衍射二元光学 Gerchberg-Saxton算法消除散斑光束整形衍射光学元件

1961—2015年淮河流域气象干旱发展过程和演变特征研究

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水利学报 2019年第5期50卷 598-611页

作者：方国华涂玉虹闻昕颜敏谭乔凤河海大学水利水电学院江苏南京210098 中国水利水电科学研究院流域水循环模拟与调控国家重点实验室北京100038

为刻画连续性干旱事件的时空动态演变过程,本文在时空维度下构建干旱事件发展时空特征变量并进行特征分析,对干旱发展过程和演变特征开展研究。首先确定干旱指标和阈值,然后判别干旱事件的时空连续性,进而建立涵盖干旱逐月集中点、干旱... 详细信息

为刻画连续性干旱事件的时空动态演变过程,本文在时空维度下构建干旱事件发展时空特征变量并进行特征分析,对干旱发展过程和演变特征开展研究。首先确定干旱指标和阈值,然后判别干旱事件的时空连续性,进而建立涵盖干旱逐月集中点、干旱时空集中点、干旱时空迁移速率等12项干旱事件发展时空特征变量,使干旱事件发展时空特征可视化,最后对1961—2015年淮河流域气象干旱事件开展实例研究。结果表明:淮河流域夏旱和春旱发生频率较高,夏秋冬三季连旱年发展过程呈现出起源于沂沭泗河流域,再转向淮河中游,并逐渐向淮河上游迁移的规律,并存在秋旱较为严重的特点;干旱迁移方向对干旱逐月强度大小有一定的影响;受干旱影响最严重的地区主要分布在流域北部;过去干旱强度呈增大趋势,干旱面积呈下降趋势,整体向西北方向迁移,预计未来将向流域东北方向迁移。该研究为全面、精细解析干旱发展过程和时空演变特征提供了新的方法和技术。

关键词：连续性干旱时空特征干旱指标发展过程动态演变