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Arbitrary manipulations of focused higher-order Poincare beams by a Fresnel zone metasurface with alternate binary geometric and propagation phases

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Photonics Research 2022年第4期10卷 1117-1126页

作者： XIANGYU ZENG YUQIN zhanG MANNA GU zijun zhan RUIRUI zhanG YU zhanG RUI SUN CHANGWEI HE CHUNXIANG LIU CHUANFU CHENG School of Physics and Electronics Shandong Normal UniversityJinan 250014China School of Science Shandong Jianzhu UniversityJinan 250101China School of Computer Science and Technology Shandong University of Finance and EconomicsJinan 250014China

The manipulation of high-quality vector beams(VBs)with metasurfaces is an important topic and has potential for classical and quantum *** this paper,we propose a Fresnel zone(FZ)metasurface with metallic nanoslits arranged on FZs,which sets alternate binary geometric and propagation phases to cancel the incident spin component and focus the converted spin component(CSC).The rotation designs of nanoslits transform the incident polarization state on the conventional Poincare sphere to VBs on the higher-order Poincare(HOP)*** two orbital angular momentum states of the CSCs were manipulated,and the focused HOP beams were *** experimental results demonstrate the broadband generation of arbitrarily focused HOP beams of high quality under the illumination of the red(632.8 nm),green(532 nm),and blue(473 nm)*** work will be of significance for the applications of VBs in different areas,such as precision metrology,optical micromanipulation,and quantum information.

关键词： Poincare alternate Fresnel

Surface ligand modified cesium lead bromide/silica sphere composites for low-threshold upconversion lasing

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Photonics Research 2022年第3期10卷 628-636页

作者： Qian Xiong Sihao Huang zijun zhan Juan Du Xiaosheng Tang Zhiping Hu Zhengzheng Liu Zeyu zhang Weiwei Chen Yuxin Leng State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science Shanghai Institute of Optics and Fine Mechanics(SIOM)Chinese Academy of Sciences(CAS)Shanghai 201800China Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310024China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China School of Physics and Electronics Shandong Normal UniversityJinan 250014China College of Optoelectronic Engineering Chongqing University of Post and TelecommunicationsChongqing 400065China

In recent years,all-inorganic halide perovskite quantum dots(QDs)have drawn attention as promising candidates for photodetectors,light-emitting diodes,and lasing ***,the sensitivity and instability of perovskite to moisture and heat seriously restrict their practical application to optoelectronic ***,a facile ligand-engineering strategy to suppress aggregation by replacing traditional long ligands oleylamine(OAm)during the hot injection process has been ***,we further explore its thermal stability and the evolution of photoluminescence quantum yield(PLQY)under ambient *** modified CsPbBr_(3)QDs film can maintain 33%of initial PL intensity,but only 17%is retained in the case of unmodified QDs after 10 h continuous ***,the obtained QDs with higher initial PLQY(91.8%)can maintain PLQY to 39.9%after being continuously exposed in air for 100 days,while the PLQY of original QDs is reduced to 5.5%.Furthermore,after adhering CsPbBr3 QDs on the surface of a micro SiO_(2)sphere,we successfully achieve the highly-efficient upconversion random *** comparison with the unmodified CsPbBr_(3)QDs,the laser from the modified CsPbBr_(3)QDs presents a decreased threshold of 79.81μJ/cm^(2)and higher quality factor(Q)of *** work may not only provide a facile strategy to synthesize CsPbBr_(3) QDs with excellent photochemical properties but also a bright prospect for high-performance random lasers.

关键词： composites modified perovskite

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基于通配符模式与随机游走的关键词提取方法

计算机工程 2020年第7期46卷 78-83页

作者：马慧芳李苗童海斌詹子俊西北师范大学计算机科学与工程学院兰州730070 桂林电子科技大学广西可信软件重点实验室广西桂林541004

结合通配符模式与引入先验信息的随机游走算法,提出一种改进的关键词提取方法。使用通配符约束捕获词语之间的语义关系,提取满足间隙约束和一次性条件的顺序模式以计算模式支持度,并在模式支持度大于等于最小支持度阈值时建立节点关联... 详细信息

结合通配符模式与引入先验信息的随机游走算法,提出一种改进的关键词提取方法。使用通配符约束捕获词语之间的语义关系,提取满足间隙约束和一次性条件的顺序模式以计算模式支持度,并在模式支持度大于等于最小支持度阈值时建立节点关联图。将维基百科知识库中词语间的相似度作为先验信息,利用基于先验信息的PageRank算法在关联图上进行随机游走直至其排名分数趋于稳定,选取排名前Top K个词语作为关键词。实验结果表明,与TextRank、GraphSum算法相比,该方法具有更高的提取准确率及稳定性。

关键词：关键词提取通配符模式随机游走间隙约束 PageRank算法

A-DDPG:多用户边缘计算系统的卸载研究

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计算机工程与应用 2023年第1期59卷 259-268页

作者：曹绍华姜佳佳陈舒詹子俊张卫山中国石油大学(华东)计算机科学与技术学院山东青岛266580

为了降低多边缘服务器多用户系统中用户的总成本,结合深度确定性策略梯度(deep deterministic policy gradient,DDPG)、长短期记忆网络(LSTM)和注意力机制,提出了一种基于DDPG的深度强化学习卸载算法(A-DDPG)。该算法采用二进制卸载策略... 详细信息

为了降低多边缘服务器多用户系统中用户的总成本,结合深度确定性策略梯度(deep deterministic policy gradient,DDPG)、长短期记忆网络(LSTM)和注意力机制,提出了一种基于DDPG的深度强化学习卸载算法(A-DDPG)。该算法采用二进制卸载策略,并且将任务的延迟敏感性和服务器负载的有限性以及任务迁移考虑在内,自适应地卸载任务,以最大限度减少由延迟敏感型任务超时造成的总损失。考虑时延和能耗两个指标并设定了不同的权重值,解决因用户类型不同带来的不公平问题,制定了任务卸载问题以最小化所有任务完成时延和能量消耗的总成本,以目标服务器的选择和数据卸载量为学习目标。实验结果表明,A-DDPG算法具有良好的稳定性和收敛性,与DDPG算法和双延迟深度确定性策略梯度(twin delayed deep deterministic policy gradient,TD3)算法相比,A-DDPG算法的用户总成本分别降低了27%和26.66%,平均达到最优任务失败率的时间分别提前了57.14%和40%,其在奖励、总成本和任务失败率方面取得了较好的效果。

关键词：移动边缘计算计算卸载深度确定性策略梯度(DDPG) 资源分配

Ruddlesden-Popper型准二维钙钛矿温度依赖发光光谱研究

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发光学报 2023年第4期44卷 569-578页

作者：杜子孝杜海南胡智萍罗家俊黄斯豪占子俊李骞刘征征杜鹃冷雨欣中国科学院上海光学精密机械研究所强场激光物理国家重点实验室上海201800 国科大杭州高等研究院物理与光电工程学院浙江杭州310024 中国科学院大学材料与光电研究中心北京100049 华中科技大学光学与电子信息学院湖北武汉430074

准二维Ruddlesden-Popper(R-P)卤化物钙钛矿具有优越的光电特性,在太阳能电池、发光二极管、激光器等光电器件中受到广泛关注,但严重影响载流子的弛豫和传输特性的激子-声子之间的相互作用还未得到充分揭示。与广泛研究的三维钙钛矿结... 详细信息

准二维Ruddlesden-Popper(R-P)卤化物钙钛矿具有优越的光电特性,在太阳能电池、发光二极管、激光器等光电器件中受到广泛关注,但严重影响载流子的弛豫和传输特性的激子-声子之间的相互作用还未得到充分揭示。与广泛研究的三维钙钛矿结构相比,准二维钙钛矿存在天然形成的量子阱结构,具有更大的激子结合能,激子效应更加明显,但对其激子-声子相互作用的研究仍然较少。因此,我们通过溶液法制备了准二维R-P型钙钛矿(PEA)_(2)Cs_(n-1)Pb_(n)Br_(3n+1)薄膜,其增益系数高达~1090.62 cm^(-1),获得了低阈值(~12.48μJ/cm^(2))的放大自发辐射。基于此,我们通过变温荧光光谱(77~300 K)和瞬态吸收光谱技术研究了(PEA)_(2)Cs_(n-1)Pb_(n)Br_(3n+1)薄膜随温度变化的发光特性,以阐述其内部的激子-声子相互作用对其发光性能的影响。发现在低温域内(77~120 K),由激子-声子相互作用引起的带隙变化相对较弱,晶格热膨胀占主导地位;随着温度升高,激子-声子相互作用对带隙变化产生较大影响。另一方面,激子-声子相互作用会促使发光光谱线宽加宽,但我们在77~120 K的温度范围内观察到了反常线宽变窄现象,这归因于由局域化效应引起的多量子阱中的能量转移机制;直到120 K之后,激子-声子相互作用引起的谱线加宽才足以逆转这一趋势。本文对准二维钙钛矿的激子-声子相互作用的研究对于提高准二维钙钛矿光学性能及其发光应用具有指导价值。

关键词：激子-声子相互作用准二维钙钛矿光谱加宽局域化效应

Is there any amphidromic point of S_2 constituent around the Natuna Islands in the southern South China Sea?

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Chinese Science Bulletin 2006年第B12期51卷 26-30页

作者： MAO Qingwen QI Yiquan SHI Ping zhan Haigang GAN zijun LED South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China

The discrepancies that if there is any amphidromic point of S2 constituent and its location if there is around the Natuna Islands in the southern South China Sea have suspended for a long time, however, there is always no convincing research to settle them up to now. The TOPEX/Poseidon and Jason-1 altimeters have been providing a long-term sea surface height data, which can be used to calculate the constants of tidal constituents along the satellite footprint with the harmonic analysis method. Based on more than 12 years altimetry data from T/P and Jason-1, the character of phase lags from harmonic analysis is used to identify if there is a S2 am-phidromic point around the Natuna Islands. The result shows that there is no S2 amphidromic point instead of a nodal line of a standing wave, and the amplitude of S2 constituent is close to zero along the nodal line.

关键词：南海南部海域旋转潮波无潮点 S2分潮海面高度表资料纳土纳群岛

Comparison on Non-isothermal Oxidation between Spent Catalytic Cracking Catalysts and Coal

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China Petroleum Processing & Petrochemical Technology 2010年第2期12卷 33-40页

作者： Men Xiujie zhan Shuhong Li Yanjun Wang zijun Wang Xieqing (Research Institute of Petroleum Processing,SINOPEC,Beijing 100083) Research Institute of Petroleum Processing SINOPEC Beijing 100083 China

Oxidation of coke deposited on spent catalytic cracking catalysts was compared with that of coal and coal char via the non-isothermal oxidation means, i.e. the thermal-gravimetric analysis （TGA） and the differential thermal analysis （DTA）. Oxidation kinetic parameters were further investigated by model-fitting methods. The test results showed that the oxidation of spent catalysts was a quite mild process, while coal and coal char experienced sharp weight loss during oxidation. The temperature for commencement and termination of oxidation increased in the following order： coal〈coal char〈spent catalysts, and the oxidation of the three tested materials displayed a self-catalytic nature, with their largest oxidation rate appearing at a weight percent of 24.96%, 34.21% and 57.93%, respectively. The oxidation of spent catalysts obeyed a random nucleation model for the first-order reaction, with Ea=206.13 kJ/mol and lgA=10.10, and the oxidation of coal could be a diffusion-controlled reaction mechanism, with Ea=161.61 kJ/mol and lgA=7.74, while the oxidation of coal char also obeyed a random nucleation model for the first-order reaction, with Ea= 149.36 k J/mol and lgA=7.89.

关键词： spent catalysts coal coal char non-isothermal oxidation TGA oxidation kinetics and mechanism

Characterization of Catalytic Cracking Catalysts Regenerated by Gasifying Deposited Coke

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China Petroleum Processing & Petrochemical Technology 2010年第1期12卷 5-12页

作者： Men Xiujie zhan Shuhong Li Yanjun Wu Zhiguo Wang zijun Wang Xieqing (Research Institute of Petroleum Processing,SINOPEC,Beijing 100083) Research Institute of Petroleum Processing SINOPEC Beijing 100083 China

Partially or fully regenerated catalytic cracking catalysts were prepared by gasifying the coke deposited on coked catalysts with a gaseous mixture of oxygen and steam in a fixed fluidized bed （FFB）. The resultant samples were characterized by different methods such as the nitrogen adsorption-desorption analysis, the X-ray diffractometry, the infrared spectroscopy, the ammonia temperature-programmed desorption （NH3-TPD） method, the X-ray fluorescence （XRF） analysis, the transmission electron microscopy and energy dispersive X-ray spectroscopy （TEM-EDX）, the thermal-gravimetric analysis （TGA） and the differential thermal analysis （DTA）. The results showed that exposure of catalyst to steam for about 10 minutes at temperature ≥ 800 ℃ could not cause too much destruction of the catalysts, and an amount of coke equating to about 0.27 m% was enough to block approximately all acid sites in micro-pores of the zeolite catalyst. Coke didn＇t show equal reactivity during coke burning-off that could be accelerated by the catalytic action of nearby metal atoms. However, when the carbon content on the catalyst reached about 2.44 m%, the catalytic action of metals on the catalyst was not evident. The severe thermal and hydrothermal environment during exposure of the catalyst to steam at a temperature in the range of about 860--880 ℃ for 30 minutes could lead to collapse of pore structure and transformation of crystal phase and consequently decrease of the surface area and acid amount on the catalyst.

关键词： coked catalysts gasification hydrothermal destruction characterization

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粤港澳大湾区技术转移的空间关联与内生动力

地理学报 2024年第6期79卷 1503-1520页

作者：戴靓丁子军马海涛曹湛王瑞霖南京财经大学公共管理学院南京210023 中国科学院地理科学与资源研究所、中国科学院区域可持续发展分析与模拟重点实验室北京100101 同济大学建筑与城市规划学院上海200092 自然资源部国土空间智能规划技术重点实验室上海200092

技术转移是缩小区域差距、优化资源配置、实现协同创新的重要途径。既有文献多从技术势差、技术需求、技术吸收、邻近性等理论探究技术转移的影响因素,本文从网络共生演化视角,提出来自内生结构和微观机制的新发现。基于国家知识产权局... 详细信息

技术转移是缩小区域差距、优化资源配置、实现协同创新的重要途径。既有文献多从技术势差、技术需求、技术吸收、邻近性等理论探究技术转移的影响因素,本文从网络共生演化视角,提出来自内生结构和微观机制的新发现。基于国家知识产权局发明专利的转让数据,构建2007—2018年6个时间节点的粤港澳大湾区技术转移空间关联网络,分析其空间格局与网络结构的演化特征,并建立动态指数随机图模型,探讨网络演化的动力机制。结果表明:①大湾区技术转移网络由松散均质向双核驱动再向多中心发展。深圳、广州是区域的技术交易中心,与第二梯队的东莞、佛山、中山、惠州,形成了多维邻近的“深惠莞广佛中”组团。在大湾区城市群尺度下,受制度差异和地域分工影响,香港地区、澳门地区在区域多为单向技术输出且较为边缘化。②大湾区技术转移网络规模和结构有显著提升,技术转移路径稳中有变,不断优化。网络关系的互惠性提升明显,等级结构趋向收敛,网络传输性与凝聚力增强,朝多核联动的均衡化和社群化发展。③大湾区技术转移网络演化受内外生动力共同驱动,内生因素可降低对外生因素的依赖。城市经济发展水平、研发投入和科研成果转化能力可促进技术转移,存在发送者效应和接收者效应。制度邻近对技术转移的促进效果显著,其次是空间邻接和技术邻近。结构依赖和时间依赖是大湾区技术转移网络演化的重要内生动力,主要表现为延迟互惠性、传递闭合性、稳定性和创新性。

关键词：城市网络技术转移结构依赖动态指数随机图模型粤港澳大湾区