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Reliable intracavity reflection for self-injection locking lasers and microcomb generation

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Photonics Research 2024年第5期12卷 I0001-I0010页

作者： BITAO shen XUGUANG ZHANG YIMENG wang ZIHAN TAO HAOWEN SHU HUAJIN chang WENCAN LI YAN ZHOU Zhangfeng Ge RUIXUAN CHEN BOWEN BAI LIN chang XINGJUN wang State Key Laboratory of Advanced Optical Communications System and Networks School of ElectronicsPeking UniversityBeijing 100871China Peng Cheng Laboratory Shenzhen 518055China Peking University Yangtze Delta Institute of Optoelectronics Nantong 226010China Frontiers Science Center for Nano-optoelectronics Peking UniversityBeijing 100871China

Self-injection locking has emerged as a crucial technique for coherent optical sources,spanning from narrow linewidth lasers to the generation of localized *** technique involves key components,namely a laser diode and a high-quality cavity that induces narrow-band reflection back into the laser ***,in prior studies,the reflection mainly relied on the random intracavity Rayleigh backscattering,rendering it unpredictable and unsuitable for large-scale production and wide-band *** this work,we present a simple approach to achieve reliable intracavity reflection for self-injection locking to address this challenge by introducing a Sagnac loop into the *** method guarantees robust reflection for every resonance within a wide operational band without compromising the quality factor or adding complexity to the fabrication *** a proof of concept,we showcase the robust generation of narrow linewidth lasers and localized microcombs locked to different resonances within a normal-dispersion ***,the existence and generation of localized patterns in a normal-dispersion cavity with broadband forward–backward field coupling is first proved,as far as we know,both in simulation and in *** research offers a transformative approach to self-injection locking and holds great potential for large-scale production.

关键词： intracavity injection locking

Theoretical insights of the pharmaceutical compound fluoxetine in water:Role in direct photolysis and indirect photolysis by free radicals

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Journal of Environmental Sciences 2024年第8期142卷 269-278页

作者： Ying Lu Se wang Yifan shen School of Environmental Science and Engineering Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologyJiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution ControlNanjing University of Information Science and TechnologyNanjing 210044China

The frequent detection of pharmaceutical compounds in the environment has led to a growing awareness,which may pose a major threat to the aquatic *** this study,photodegradation(direct and indirect photolysis)of two different dissociation states of fluoxetine(FLU)was investigated in water,mainly including the determination of photolytic transition states and products,and the mechanisms of indirect photodegradation with·OH,CO_(3)^(*-)and NO_(3)^(*).The main direct photolysis pathways are defluorination and C–C bond *** addition,the indirect photodegradation of FLU in water is mainly through the reactions with·OH and NO_(3)^(*),and the photodegradation reaction with CO_(3)^(*-)is relatively difficult to occur in the water *** results provide a theoretical basis for understanding the phototransformation process of FLU in the water environment and assessing its potential risk.

关键词： Fluoxetine Photochemical mechanism Direct photolysis Free radical reaction DFT

Investigation of Ce/BEA as a passive NO_(x)adsorber:*** aging deactivation mechanism

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Journal of Rare Earths 2024年第8期42卷 1524-1530,I0004页

作者： Yiying Ding Minghui Yu Xiaojie Yu Meiqing shen Jianqiang wang Jun wang Gurong shen School of Chemical Engineering and Technology Tianjin UniversityTianjin300350China School of Materials Science and Engineering Tianjin UniversityTianjin300350China National Rare Earth Catalysis Research Institute Dongying257000China

Ce/BEA has the potential to be applied as a novel passive NO_(x)absorber(PNA)in the after-treatment of vehicles due to its considerable NO_(x)storage ***,as a vehicle exhaust after-treatment material,it must withstand the test of long-term hydrothermal *** work examined the deactivation mechanism of Ce/BEA during hydrothermal aging.3.0 wt%Ce/BEA was prepared using the ionexchange method,and then subjected to hydrothermal treatment at 650℃with 10%H_(2)O for 1-12 h to obtain samples with different aging *** comparison,the H-BEA support was aged under the same ***-Emmett-Teller(BET)method,X-ray diffraction(XRD),NH_(3)temperature programmed reduction(NH_(3)-TPD),^(27)Al MAS nuclear magnetic resonance(^(27)Al MAS NMR),H_(2)temperature programmed reduction(H_(2)-TPR),and high resolution-transmission electron microscopy(HR-TEM)were performed to characterize the changes in PNA performance,structure,Ce species,and *** HR-TEM and H_(2)-TPR results show that CeO_(x)particles appear after hydrothermal aging,which results from the detachment and aggregation of active Ce *** on the^(27)Al MAS NMR results,we conclude that BEA zeolite dealumination leads to the loss of acidic sites and the transformation of active Ce species on the acidic sites into the less active CeO_(x).This is the primary reason for the hydrothermal aging deactivation of Ce/BEA.

关键词： Passive NO_(x)adsorber Ce/BEA Hydrothermal aging CeO_(x) Dealumination Rare earths

Function-reversible facets enabling SrTiO_(3)nanocrystals for improved photocatalytic hydrogen evolution

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Frontiers in Energy 2024年第1期18卷 101-109页

作者： Bin wang Bei AN Xiaoqian LI Shaohua shen School of Physics Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter(Ministry of Education)Key Laboratory of Shaanxi for Advanced Materials and Mesoscopic PhysicsXi’an Jiaotong UniversityXi’an 710049China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China

It has been widely reported that,for faceted nanocrystals,the two adjacent facets with different band levels contribute to promoted charge separation,and provide active sites for photocatalytic reduction and oxidation reaction,*** such cases,only one family of facets can be used for photocatalytic hydrogen ***,by using SrTiO_(3)nanocrystals enclosed by{023}and{001}facets as a model photocatalyst,this paper proposed a strategy to achieve the full-facets-utilization of the nanocrystals for photocatalytic hydrogen via chemically depositing Pt nanoparticles on all *** photo-deposition experiment of CdS provided direct evidence to demonstrate that the{023}facets which were responsible for photooxidation reaction can be function-reversed for photocatalytic hydrogen evolution after depositing Pt nanoparticles,together with the{001}***,the full-facets-utilization led to a much-improved activity for photocatalytic hydrogen,in contrast to those SrTiO_(3)nanocrystals with only{001}facets deposited by Pt nanoparticles via a photo-deposition method.

关键词： SrTiO_(3)nanocrystals crystal facets photocatalysis hydrogen evolution

Spatiotemporal characteristics of seed rain and soil seed bank of artificial Caragana korshinskii Kom. forest in the Tengger Desert, China

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Journal of Arid Land 2024年第4期16卷 550-566页

作者： shen Jianxiang wang Xin wang Lei wang Jiahui QU Wenjie ZHANG Xue chang Xuanxuan YANG Xinguo CHEN Lin QIN Weichun ZHANG Bo NIU Jinshuai College of Ecological Environment Ningxia UniversityYinchuan 750021China Key Laboratory of Restoration and Reconstruction of Degraded Ecosystems in Northwest China Ministry of EducationNingxia UniversityYinchuan 750021China College of Agriculture Ningxia UniversityYinchuan 750021China

Vegetation restoration and reconstruction are effective approaches to desertification control and achieving social and economic sustainability in desert ***,the self-succession ability of native plants during the later periods of vegetation restoration remains ***,this study was conducted to bridge the knowledge gap by investigating the regeneration dynamics of artificial forest under natural *** information of seed rain and soil seed bank was collected and quantified from an artificial Caragana korshinskii *** in the Tengger Desert,*** germination tests were conducted in a laboratory *** analysis of species quantity and diversity in seed rain and soil seed bank was conducted to assess the impact of different durations of sand fixation(60,40,and 20 a)on the progress of vegetation restoration and ecological conditions in artificial *** *** results showed that the top three dominant plant species in seed rain were Echinops gmelinii Turcz.,Eragrostis minor Host.,and Agropyron mongolicum Keng.,and the top three dominant plant species in soil seed bank were ***,Chloris virgata Sw.,and *** restoration period increased,the density of seed rain and soil seed bank increased first and then *** for species richness,as restoration period increased,it gradually increased in seed rain but decreased in soil seed *** was a positive correlation between seed rain density and soil seed bank density among all the three restoration *** species similarity between seed rain or soil seed bank and aboveground vegetation decreased with the extension of restoration *** shape of the seeds,specifically those with external appendages such as spines and crown hair,clearly had an effect on their dispersal,then resulting in lower seed density in soil seed *** addition,precipitation was a crucial factor in promoting rapid germination,also resulting in lower seed density in soi

关键词： ecological restoration soil seed bank seed rain artificial forest vegetation desertification Caragana korshinskii Tengger Desert

Investigation of Ce/BEA as a passive NO_(x)adsorber:*** occurrences of cerium and adsorption behavior

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Journal of Rare Earths 2024年第7期42卷 1265-1271,I0003页

作者： Minghui Yu Yiying Ding Xiaojie Yu Siwei Yan Meiqing shen Jianqiang wang Jun wang Gurong shen School of Materials Science and Engineering Tianjin UniversityTianjin300350China School of Chemical Engineering and Technology Tianjin UniversityTianjin300350China National Rare Earth Catalysis Research Institute Dongying257000China

Ce/BEA has great potential as a passive NO_(x)absorber(PNA)to reduce the NO_(x)emissions during the cold start phase especially in diesel engine for its high resistance to CO and suitable NO_(x)desorption temperature ***,as a novel material,its physical and chemical properties still remain *** this work,Ce/BEA was synthesized by ion-exchange method to identify the active species in NO_(x)adsorption,compared with aggregated Ce species in Ce/SiAlO_(x) prepared by impregnation method.X-ray diffraction(XRD),high resolution-transmission electron microscopy(HR-TEM)and aberration-corrected-scanning transmission electron microscopy(AC-STEM)were performed to confirm the isolated single atom formation of Ce species in Ce/***-vis diffraction reflection spectra(DRS)and X-ray photoelectron spectroscopy(XPS)were conducted to find the difference of chemical environment between the isolated Ce species and aggregated *** performance evaluation and temperature programmed reduction of hydrogen(H_(2)-TPR)results show the high NO_(x)storage capacity and active oxygen species quantity in Ce/*** is also found that the main NO_(x)adsorption species are Ce^(4+)-O^(∗)rather than Ce^(3+).NO_(x)-diffuse reflectance infrared Fourier transform spectroscopy(NO_(x)-DRIFTS)confirms that the bidentate nitrite species are the critical NO_(x)adsorption intermediates and the conception of NO_(x)adsorption and desorption processes is proposed.

关键词： Passive NO_(x)absorber Ce/BEA Isolated Ce species Rare earths

Absolute pose estimation of UAV based on large-scale satellite image

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Chinese Journal of Aeronautics 2024年第6期37卷 219-231页

作者： Hanyu wang Qiang shen Zilong DENG Xinyi CAO Xiaokang wang School of Mechatronical Engineering Beijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

Obtaining absolute pose based on pre-loaded satellite images is one of the important means of autonomous navigation for small Unmanned Aerial Vehicles(UAVs)in Global Navigation Satellite System(GNSS)denied *** of the previous works have tended to build Convolutional Neural Networks(CNNs)to extract features and then directly regress the pose,which will fail when solving the challenges caused by the huge viewpoint and size differences between“UAV-satellite”image pairs in real-world ***,this paper proposes a probability distribution/regression integrated deep model with the attention-guided triple fusion mechanism,which estimates discrete distributions in pose space and three-dimensional vectors in translation *** order to overcome the shortage of the relevant dataset,this paper simulates image datasets captured by UAVs with forward-facing cameras during target searching and autonomous *** effectiveness,superiority,and robustness of the proposed method are verified by simulated datasets and flight tests.

关键词： Satellite imagery Unmanned Aerial Vehicle(UAV) Deep neural networks Vision navigation von Mises-Fisher distribution

Parallel Light Fields: A Perspective and A Framework

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 542-544页

作者： Fei-Yue wang Yu shen IEEE State Key Laboratory for Management and Control of Complex Systems Institute of AutomationChinese Academy of SciencesBeijing 100190China School of Artificial Intelligence University of Chinese Academy of ScienceBeijing 100049

Dear Editor,Light fields give relatively complete description of scenes from perspective of angles and positions of rays. At present time, most of the computer vision algorithms take 2D images as input which are simplified expression of light fields with depth information discarded. In theory, computer vision tasks may achieve better performance as long as complete light fields are acquired.

关键词： computer Framework simplified

Identifying the enhancement mechanism of Al/MoO_(3) reactive multilayered films on the ignition ability of semiconductor bridge using a one-dimensional gas-solid two-phase flow model

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Defence Technology（防务技术） 2024年第3期33卷 168-179页

作者： Jianbing Xu Yuxuan Zhou Yun shen Yueting wang Yinghua Ye Ruiqi shen School of Chemistry and Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094China Micro-Nano Energetic Devices Key Laboratory of MIIT Nanjing 210094China Institute of Space Propulsion Nanjing University of Science and TechnologyNanjing 210094China

Energetic Semiconductor bridge(ESCB)based on reactive multilayered films(RMFs)has a promising application in the miniature and intelligence of initiator and pyrotechnics *** the ignition enhancement mechanism of RMFs on semiconductor bridge(SCB)during the ignition process is crucial for the engineering and practical application of advanced initiator and pyrotechnics *** this study,a one-dimensional(1D)gas-solid two-phase flow ignition model was established to study the ignition process of ESCB to charge particles based on the reactivity of Al/MoO_(3) *** order to fully consider the coupled exothermic between the RMFs and the SCB plasma during the ignition process,the heat release of chemical reaction in RMFs was used as an internal heat source in this *** is found that the exothermal reaction in RMFs improved the ignition performance of *** the process of plasma rapid condensation with heat release,the product of RMFs enhanced the heat transfer process between the gas phase and the solid charge particle,which accelerated the expansion of hot plasma,and heated the solid charge particle as well as gas phase region with low *** addition,it made up for pressure loss in the gas *** the plasma dissipation process,the exothermal chemical reaction in RMFs acted as the main heating source to heat the charge particle,making the surface temperature of the charge particle,gas pressure,and gas temperature rise *** result may yield significant advantages in providing a universal ignition model for miniaturized ignition devices.

关键词： Ignition enhancement mechanism 1D gas-solid two-phase flow Al/MoO_(3)reactive multilayered films Semiconductor bridge Miniaturized ignition device