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Ultralow-phase-noise and broadband frequency-hopping coupled optoelectronic oscillator under quiet point operation

Photonics Research 2024年第08期12卷 1785-1793页

作者： HUI LIU MINGYANG GUO TIAN ZHANG JIAN DAI KUN XU State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications School of Electronic Engineering Beijing University of Posts and Telecommunications

Advancements in microwave photonics have yielded novel approaches for generating high-purity microwave sources. Among these, optoelectronic oscillators（OEOs） and coupled optoelectronic oscillators（COEOs） have demonstrated the capability to generate frequency-independent microwaves with exceptionally low phase ***, the tunability of the oscillators is rather limited due to the necessity for narrowband electronic bandpass filters, presenting challenges in achieving both wide and rapid tuning capabilities. Here, we present a COEO featuring ultralow phase noise, flexible tuning capability, and high robustness. This is achieved through a quiet point（QP）-operated harmonic mode-locked fiber laser, which effectively mitigates optical amplifier noise and supermode competition, thus significantly diminishing the necessity for ultra-narrow electronic filters. Due to the liberated tuning ability, we present an oscillator that can be tuned from 2 GHz to 18 GHz, with phase noise as low as-140 d Bc/Hz at 10 k Hz under the QP operation. We then illustrate the practical application of the proposed oscillator in generating frequency-hopping signals with consistent spurious modes less than-85 d Bc,absolute phase noise below-135 d Bc/Hz at 10 k Hz, hopping resolution of 1.25 MHz, and fractional frequency stability below 6.1 × 10-12at 1 s averaging time when locked to a reference. The presented COEO structure emerges as a compelling solution for agile and low-noise microwave sources in advanced wireless communication and radar systems.

关键词： Bandpass filters Beam splitters Microwave photonics Mode-locked fiber lasers Optical amplifiers Phase noise

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Photothermal catalytic C-C coupling to ethylene from CO_(2) with high efficiency by synergistic cooperation of oxygen vacancy and half-metallic WTe_(2)

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Journal of Energy Chemistry 2024年第6期93卷 547-556,I0014页

作者： Xiaoyue Zhang Yong Yang Yingjie Hu Lijun Xiong Tianyu Wang Panjie Li Jinyou Shen Key Laboratory of Environmental Remediation and Ecological Health Ministry of Industry and Information TechnologySchool of Environmental and Biological EngineeringNanjing University of Science and TechnologyNanjing 210094JiangsuChina School of Chemistry and Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina Nanjing Key Laboratory of Advanced Functional Materials Nanjing Xiaozhuang UniversityNanjing 210094JiangsuChina Jiangsu Environmental Engineering Technology Co.Ltd Nanjing 210019JiangsuChina

Photothermal catalytic CO_(2) conversion provides an effective solution targeting carbon neutrality by synergistic utilization of photon and ***,the C-C coupling initiated by photothermal catalysis is still a big ***,a three-dimensional(3D)hierarchical W_(18)O_(49)/WTe_(2) hollow nanosphere is constructed through in-situ embodying of oxygen vacancy and tellurium on the scaffold of WO_(3).The light absorption towards near-infrared spectral region and CO_(2) adsorption are enhanced by the formation of half-metal WTe_(2) and the unique hierarchical hollow *** with the generation of oxygen vacancy with strengthened CO_(2) capture,the photothermal effect on the samples can be sufficiently exploited for activating the CO_(2) *** particular,the close contact between W_(18)O_(49)and WTe_(2) largely promotes the photoinduced charge separation and mass transfer,and thus the~*CHO intermediate formation and fixedness are *** a result,the C-C coupling can be evoked between tungsten and tellurium atoms on WTe_(2).The ethylene production by optimized W_(18)O_(49)/WTe_(2) reaches 147.6μmol g^(-1)with the selectivity of 80%.The in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and density functional theory(DFT)calculations are performed to unveil the presence and significance of aldehyde intermediate groups in C-C *** half-metallic WTe_(2) cocatalyst proposes a new approach for efficient CO_(2) conversion with solar energy,and may especially create a new platform for the generation of multi-carbon products.

关键词： Photothermal catalysis Half-metal WTe_(2) C–C coupling Carbon neutrality

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Stochastic Economic Dispatch Based Optimal Market Clearing Strategy Considering Flexible Ramping Products Under Wind Power Uncertainties

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1525-1535页

作者： Haoyong Chen Jianping Huang Zhenjia Lin Fanqi Huang Mengshi Li School of Electric Power South China University of TechnologyGuangzhou510641China Department of Electrical Engineering The Hong Kong Polytechnic UniversityHong KongChina

High penetration level of renewable energy has brought great challenges to operation of power systems,and use of flexible resources(FRs)is becoming increasingly *** of power systems can be improved by changing generation arrangements,but the interests of some market participants may be harmed in the *** study proposes a stochastic economic dispatch model with trading of flexible ramping products(FRPs).To calculate changes in revenue and reasonably compensate units that provide FRs,multisegmented marginal bidding for energy is simulated by linearizing generation cost,and an optimal market clearing strategy for FRPs is developed according to changes in clearing energy and marginal clearing ***,the correlation between prediction errors of wind speeds among different wind farms is determined based on a joint distribution function modeled by the copula function,and quasi-Monte Carlo simulation(QMC)is used to generate wind power ***,numerical simulations of modified IEEE-30 and IEEE-118 bus systems is performed with minimum comprehensive cost as the objective *** verifies the proposed model could effectively deal with wind variability and uncertainty,stabilize the marginal clearing price of the electricity market,and ensure fairness in the market.

关键词： Flexible ramping product marginal clearing price risk cost stochastic economic dispatch wind power correlation

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Nanoconfinement-induced water molecules and hydrogen molecules transport behaviors in ball-in-ball structure photocatalysts to improve hydrogen evolution

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Nano Research 2024年第5期17卷 3752-3760页

作者： Ben Chong Baorong Xu He Li Honghui Ou Guidong Yang XJTU-Oxford Joint International Research Laboratory of Catalysis School of Chemical Engineering and TechnologyXi’an Jiaotong UniversityXi’an 710049China

The diffusion,adsorption/desorption behaviors of water molecules and hydrogen molecules are of great importance in heterogeneous photocatalytic hydrogen *** the study of structure-property-performance relationships,nanoconfined space provides an ideal platform to promote mass diffusion and transfer due to their extraordinary properties that are different from the bulk ***,we designed and prepared a nanoconfined CdS@SiO_(2)-NH_(2) nanoreactor,whose shell is composed of amino-functionalized silica nanochannels,and encapsulates spherical CdS as a photocatalyst *** and simulated results reveal that the amino-functionalized nanochannels promote water molecules’and hydrogen molecules’directional diffusion and *** molecules are enriched in the nanocavity between the core and the shell,and promote the interfacial photocatalytic *** a result,the maximized water enrichment and minimized hydrogen-occupied active sites enable photocatalyst with optimized mass transfer kinetics and localization electron distribution on the CdS surface,leading to superior hydrogen production performance with activity as high as 37.1 mmol·g^(-1)·h^(-1).

关键词： nanochannels photocatalytic hydrogen evolution mass transfer amino-functionalized CdS

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Screening COVID-19 from chest X-ray images by an optical diffractive neural network with the optimized F number

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Photonics Research 2024年第7期12卷 1410-1426页

作者： JIALONG WANG SHOUYU CHAI WENTING GU BOYI LI XUE JIANG YUNXIANG ZHANG HONGEN LIAO XIN LIU DEAN TA Academy for Engineering and Technology Fudan UniversityShanghai 200433China Center for Biomedical Engineering Fudan UniversityShanghai 200433China Department of Chemistry Fudan UniversityShanghai 200433China Department of Biomedical Engineering School of MedicineTsinghua UniversityBeijing 100084China

The COVID-19 pandemic continues to significantly impact people's lives worldwide, emphasizing the critical need for effective detection methods. Many existing deep learning-based approaches for COVID-19 detection offer high accuracy but demand substantial computing resources, time, and energy. In this study, we introduce an optical diffractive neural network(ODNN-COVID), which is characterized by low power consumption, efficient parallelization, and fast computing speed for COVID-19 detection. In addition, we explore how the physical parameters of ODNN-COVID affect its diagnostic performance. We identify the F number as a key parameter for evaluating the overall detection capabilities. Through an assessment of the connectivity of the diffractive network, we established an optimized range of F number, offering guidance for constructing optical diffractive neural networks. In the numerical simulations, a three-layer system achieves an impressive overall accuracy of 92.64% and 88.89% in binary-and threeclassification diagnostic tasks. For a single-layer system, the simulation accuracy of 84.17% and the experimental accuracy of 80.83% can be obtained with the same configuration for the binary-classification task, and the simulation accuracy is 80.19% and the experimental accuracy is 74.44% for the three-classification task. Both simulations and experiments validate that the proposed optical diffractive neural network serves as a passive optical processor for effective COVID-19 diagnosis, featuring low power consumption, high parallelization, and fast computing capabilities. Furthermore, ODNN-COVID exhibits versatility, making it adaptable to various image analysis and object classification tasks related to medical fields owing to its general architecture.

关键词： neural network offering

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Constructing high-toughness polyimide binder with robust polarity and ion-conductive mechanisms ensuring long-term operational stability of silicon-based anodes

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Journal of Energy Chemistry 2024年第6期93卷 580-591,I0014页

作者： Yongjun Kang Nanxi Dong Fangzhou Liu Daolei Lin Bingxue Liu Guofeng Tian Shengli Qi Dezhen Wu State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China ENFI R&D Institute China ENFI Engineering CorporationBeijing 100038China China Automotive Battery Research Institute Co. Ltd.Beijing 101407China Changzhou Institute of Advanced Materials Beijing University of Chemical TechnologyChangzhou 213164JiangsuChina

Silicon-based materials have demonstrated remarkable potential in high-energy-density batteries owing to their high theoretical ***,the significant volume expansion of silicon seriously hinders its utilization as a lithium-ion ***,a functionalized high-toughness polyimide(PDMI) is synthesized by copolymerizing the 4,4'-Oxydiphthalic anhydride(ODPA) with 4,4'-oxydianiline(ODA),2,3-diaminobenzoic acid(DABA),and 1,3-bis(3-aminopropyl)-tetramethyl disiloxane(DMS).The combination of rigid benzene rings and flexible oxygen groups(-O-) in the PDMI molecular chain via a rigidness/softness coupling mechanism contributes to high *** plentiful polar carboxyl(-COOH) groups establish robust bonding *** ionic transport is achieved by incorporating the flexible siloxane segment(Si-O-Si),which imparts high molecular chain motility and augments free volume holes to facilitate lithium-ion transport(9.8 × 10^(-10) cm^(2) s^(-1) vs.16 × 10^(-10) cm^(2) s~(-1)).As expected,the SiO_x@PDMI-1.5 electrode delivers brilliant long-term cycle performance with a remarkable capacity retention of 85% over 500 cycles at 1.3 A g^(-1).The well-designed functionalized polyimide also significantly enhances the electrochemical properties of Si nanoparticles ***,the assembled SiO_x@PDMI-1.5/NCM811 full cell delivers a high retention of 80% after 100 *** perspective of the binder design strategy based on polyimide modification delivers a novel path toward high-capacity electrodes for high-energy-density batteries.

关键词： Polyimide binder High toughness Robust ionic transport Silicon-based anodes Lithium-ion batteries

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natural vibration and critical velocity of translating Timoshenko beam with non-homogeneous boundaries

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Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1523-1538页

作者： Yanan LI Jieyu DING Hu DING Liqun CHEN Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai Frontier Science Center of MechanoinformaticsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China School of Mathematics and Statistics Qingdao UniversityQingdao 266071Shandong ProvinceChina

In most practical engineering applications,the translating belt wraps around two fixed *** boundary conditions of the dynamic model are typically specified as simply supported or fixed *** this paper,non-homogeneous boundaries are introduced by the support *** the translating belt as the mechanical prototype,the vibration characteristics of translating Timoshenko beam models with nonhomogeneous boundaries are investigated for the first *** governing equations of Timoshenko beam are deduced by employing the generalized Hamilton's *** effects of parameters such as the radius of wheel and the length of belt on vibration characteristics including the equilibrium deformations,critical velocities,natural frequencies,and modes,are numerically calculated and *** numerical results indicate that the beam experiences deformation characterized by varying curvatures near the *** radii of the wheels play a pivotal role in determining the change in trend of the relative difference between two beam *** the results unearths that the relative difference in equilibrium deformations between the two beam models is more pronounced with smaller-sized *** the two wheels are of equal size,the critical velocities of both beam models reach their respective *** addition,the relative difference in natural frequencies between the two beam models exhibits nonlinear variation and can easily exceed 50%.Furthermore,as the axial velocities increase,the impact of non-homogeneous boundaries on modal shape of translating beam becomes more *** dealing with non-homogeneous boundaries is challenging,beam models with non-homogeneous boundaries are more sensitive to parameters,and the differences between the two types of beams undergo some interesting variations under the influence of non-homogeneous boundaries.

关键词： translating beam Timoshenko beam non-homogeneous boundary natural frequency critical velocity

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Forming process chain for manufacturing complex conical-section profiled rings:On a co-design method

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Chinese Journal of Aeronautics 2024年第6期37卷 485-503页

作者： Lei LIANG Chaojiang ZOU Lianggang GUO State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Guizhou Aviation Technology Development Co.Ltd Guiyang 550081China

The final quality of complex conical-section rings depends on co-design of multiple processes in forming process *** this study,for a complex aeroengine casing ring with a large slope and a flange on its end,a co-design method of the forming process chain is put forward towards the objective of precision forming,which not only proposes a standard process route composed of multiple processes of upsetting,punching,rectangular ring rolling,loose tooling forging and profiled ring rolling,but also presents co-design methods of dies and blanks for all the *** profiled ring rolling,a design method of preformed blank that makes the blank and the target conical-section ring have the same axial volume distribution is *** the method,the axial metal redistribution during the process can be alleviated greatly thus improving the forming stability and precision of the *** on the geometric features of designed preformed blank,design methods of blanks and dies for loose tolling forging,rectangular ring rolling,punching and upsetting are proposed *** view of the key roles of loose tooling forging(manufacturing the preformed blank)and profiled ring rolling on the final quality of the conical ring parts,inherited FE simulations for these two processes are performed to verify the proposed design methods and determine appropriate design *** is demonstrated that the proposed design method has significant advantages in improving forming ***,a suggestive value 1.5 of the rolling ratio for profiled ring rolling(a key design parameter)is given based on comprehensive consideration of multiple indicators such as ring roundness,deformation uniformity and forming *** corresponding industrial experiments performed illustrate that a high forming precision of the conical-section aeroengine casing ring is achieved.

关键词： Complex conical-section ring Co-design of forming process chain Profiled ringrolling Preformed blank Loose tooling forging

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Simultaneous integration of Fe clusters and NiFe dual single atoms in nitrogen-doped carbon for oxygen reduction reaction

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Nano Research 2024年第4期17卷 2291-2297页

作者： Jirong Bai Yuebin Lian Yaoyao Deng Mei Xiang Peng Xu Quanfa Zhou Yawen Tang Yaqiong Su Research Center of Secondary Resources and Environment School of Chemical Engineering and MaterialsChangzhou Institute of TechnologyChangzhou 213022China Jiangsu Key Laboratory of New Power Batteries School of Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China School of Chemistry Engineering Research Center of Energy Storage Materials and Devices of Ministry of EducationNational Innovation Platform(Center)for Industry-Education Integration of Energy Storage TechnologyXi’an Jiaotong UniversityXi’an 710049China

Atomically-dispersed iron-based electrocatalysts are promising substitutes for noble metal electrocatalysts because of excellent performance in oxygen reduction reaction(ORR).Rationally modulating the local coordination environment of the Fe site and optimizing the binding energy of oxygen reduction intermediates are effective strategies to optimize ORR ***,we report a new method in which Ni is introduced to construct NiFe dual single atoms and iron nanoclusters loaded on the nitrogen-doped carbon with a highly porous *** design plays a synergistic role of dual single atoms and clusters,optimizes the 3d orbital and Fermi level of Fe,breaks the symmetrical structure of Fe-N_(4),and effectively improves the adsorption/desorption behavior of the oxygen-containing *** tests show FeNCs/NiFeSAs-NC has an excellent intrinsic *** calculations show the oxygen-containing species on the Ni active site will move to the middle of NiFe(bridge site connection)after optimization and that the key step is OH desorption,with a reaction energy of 0.27 *** electron exchange between NiFe-N6 and Fe-cluster is very strong,further indicating the introduction of Ni species and Fe clusters has a regulatory effect on the electronic structure of Fe-N_(4).

关键词： NiFe dual single atoms Fe clusters OH*adsorption energy oxygen reduction reaction

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Controllable shaping of high-index dielectric nanoparticles by exploiting the giant optical force of femtosecond laser pulses

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Photonics Research 2024年第2期12卷 282-291页

作者： YUHENG MAO SHUWEN BAI MINGCHENG PANMAI LIDAN ZHOU SHIMEI LIU SHULEI LI HAIYING LIU HAIHUA FAN JUN DAI SHENG LAN Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices School of Information and Optoelectronic Science and EngineeringSouth China Normal UniversityGuangzhou 510006China Shenzhen Institute of Terahertz Technology and Innovation Shenzhen 518102China State Key Laboratory of Optoelectronic Materials and Technologies School of Electronics and Information TechnologySun Yat-sen UniversityGuangzhou 510006China School of Optoelectronic Engineering Guangdong Polytechnic Normal UniversityGuangzhou 510665China

Nanoparticles made of different materials usually support optical resonances in the visible to near infrared spectral range,such as the localized surface plasmons observed in metallic nanoparticles and the Mie resonances observed in dielectric *** optical resonances,which are important for practical applications,depend strongly on the morphologies of *** irradiation is a simple but effective way to modify such optical resonances through the change in the morphology of a *** laser-induced shaping of metallic nanoparticles has been successfully demonstrated,it remains a big challenge for dielectric nanoparticles due to their larger Young’s modulus and smaller thermal ***,we proposed and demonstrated a strategy for realizing controllable shaping of high-index dielectric nanoparticles by exploiting the giant optical force induced by femtosecond laser *** was found that both Si and Ge nanoparticles can be lit up by resonantly exciting the optical resonances with femtosecond laser pulses,leading to the luminescence burst when the laser power exceeds a *** addition,the morphologies of Si and Ge nanoparticles can be modified by utilizing the giant absorption force exerted on them and the reduced Young’s modulus at high *** shape transformation from sphere to ellipsoid can be realized by laser irradiation,leading to the blueshifts of the optical *** was found that Si and Ge nanoparticles were generally elongated along the direction parallel to the polarization of the laser *** shaping of Si and Ge can be achieved by deliberately adjusting the excitation wavelength and the laser *** findings are helpful for understanding the giant absorption force of femtosecond laser light and are useful for designing nanoscale photonic devices based on shaped highindex nanoparticles.

关键词： optical polarization dielectric

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