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Multi-junction cascaded vertical-cavity surface-emitting laser with a high power conversion efficiency of 74%

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Light(Science & Applications) 2024年第3期13卷 555-565页

作者： yao Xiao jun Wang Heng Liu pei Miao Yudan Gou Zhicheng Zhang Guoliang Deng Shouhuan Zhou College of Electronics and Information Engineering Sichuan UniversityChengdu 610064China Suzhou Everbright Photonics Co. LtdSuzhou 215163China

High electro-optical conversion efficiency is one of the most distinctive features of semiconductor lasers as compared to other types of *** further increase remains a significant *** enhancing the efficiency of edgeemitting lasers(EEL),which represent the highest efficiency among semiconductor lasers at present,is *** efficiency of vertical cavity surface emitting lasers(VCSELs)has always been relatively low compared to *** paper,combining modeling with experiments,demonstrates the potential of multi-junction cascaded VCSELs to achieve high efficiency beyond that of EELs,our simulations show,that a 20-junction VCSEL can achieve an efficiency of more than 88%at room *** fabricated VCSEL devices with different numbers of junctions and compared their energy efficiency.15-junction VCSELs achieved a maximum efficiency of 74%at room temperature under nanosecond driving current,the corresponding differential quantum efficiency exceeds 1100%,being the largest electro-optical conversion efficiency and differential quantum efficiency reported until now for VCSELs.

关键词： cascaded power cavity

Numerical investigation of non-uniform temperature fields for proppant and fluid phases in supercritical CO_(2)fracturing

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Particuology 2024年第7期90卷 149-163页

作者： Boyu Liu jun yao Research Center of Multiphase Flow in Porous Media China University of Petroleum(East China)Qingdao 266000China

The non-uniform temperature distribution in supercritical CO_(2)(Sc-CO_(2))fracturing influences the density,viscosity,and volume expansion or shrinkage rate of Sc-CO_(2),impacting proppant *** study presents a coupled computational fluid dynamics-discrete element method and heat transfer model to examine the effects of proppant bed shape and the heat transfers of proppant-wall,proppant-fluid,and fluid-wall on the fluid and proppant temperature *** Sc-CO_(2)volume expansion is assessed under various temperature conditions by evaluating the volume-averaged Sc-CO_(2)*** factors,including proppant size,shape,thermal conductivity,concentration,temperature difference,and injection velocity,are carefully analyzed to elucidate their *** findings elucidate the existence of four distinct zones in the fluid temperature *** zone exhibits different magnitudes of temperature change under diverse conditions and undergoes dynamic transformations with the development of the proppant *** fluid-wall heat transfer and the fluid temperatures in Zones C and D are significantly subject to the fluid injection velocity(governing the heating duration),the temperature difference between fluid and formation(impacting the magnitude of heat flux),and the proppant bed shape(controlling the effective heating area).Additionally,the proppant-wall and proppant-fluid heat transfers determine the temperatures of both the proppant bed and the fluid within Zone B,showing a strong correlation with proppant thermal conductivity,proppant size,injection velocity,and temperature *** proposed coupled model provides valuable insights into the temperature distributions and flow behaviors of temperature-dependent fracturing fluids and proppants.

关键词： CFD-DEM Heat transfer Compressible fluid CO_(2)sequestration Proppant transport

Exponential Synchronization of Delayed Stochastic Complex Dynamical Networks via Hybrid Impulsive Control

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 785-787页

作者： yao Cui pei Cheng Xiaohua Ge the School of Mathematic Science Anhui UniversityHefei 230601China IEEE the School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyMelbourne VIC 3122Australia

Dear Editor,This letter addresses the synchronization problem of a class of delayed stochastic complex dynamical networks consisting of multiple drive and response *** aim is to achieve mean square exponential synchronization for the drive-response nodes despite the simultaneous presence of time delays and stochastic noises in node dynamics.

关键词： dynamics stochastic letter

Deciphering a Million-Plus RSA Integer with Ultralow Local Field Coefficient h and Coupling Coefficient J of the Ising Model by D-Wave 2000Q

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Tsinghua Science and Technology 2024年第3期29卷 874-882页

作者： Chao Wang Qiaoyun Hu Haonan yao Sumin Wang Zhi pei Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication Shanghai UniversityShanghai 200444China

This work is the first to determine that a real quantum computer(including generalized and specialized)can decipher million-scale RSA relying solely on quantum algorithms,showing the real attack potential of D-Wave *** influence of different column widths on RSA factorization results is studied on the basis of a multiplication table,and the optimal column method is determined by traversal *** traversal experiment of integer factorization within 10000 shows that the local field and coupling coefficients are 75%–93%lower than the research of Shanghai University in 2020 and more than 85%lower than that of Purdue University in *** low Ising model parameters are crucial to reducing the hardware requirements,prompting factoring 1245407 on the D-Wave 2000Q real machine.D-Wave advantage already has more than 5000 qubits and will be expanded to 7000 qubits during 2023–2024,with remarkable improvements in decoherence and *** machine is expected to promote the solution of large-scale combinatorial optimization *** of the contributions of this paper is the discussion of the long-term impact of D-Wave on the development of post-quantum cryptography standards.

关键词： quantum annealing RSA D-Wave 2000Q post-quantum cryptography

Topology modulation of tetraphenylethylene graphdiyne at a liquid-liquid interface

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Nano Research 2024年第6期17卷 4661-4667页

作者： Tingting Xu pei Wen Ng Shaofei Wu Danjun Fu Yunhan Ma yao Liu Lidao Li Xiaofei Zhang jun Zhu Department of Chemistry National University of SingaporeSingapore 117543Singapore Institute of Materials Research and Engineering(IMRE) Agency for ScienceTechnology and Research(A*STAR)Singapore 138634Singapore

Monomers with low symmetries can form different topological structures in the preparation of organic two-dimensional(2D)***,it remains challenging to modulate the topologies in practical *** theoretical insights into the formation energy of potential structural configurations,we report the topology modulation of a graphdiyne(GDY)derivative constructed from two-fold symmetric tetrakis(4-ethynylphenyl)ethene precursor by changing solvent combinations in a liquid-liquid interfacial *** aqueous-organic(water-dichloromethane)interface afforded GDY with a kagome topology while a rhombic topology was formed at an organic-organic(hexane-acetonitrile)interface.A comprehensive evaluation of their structures and optoelectronic properties was conducted through various characterization techniques and theoretical *** study provided new insights to modulate the topology of not only GDY but also other framework structures and obtain topologically pure materials in situations where different topologies are possible during practical synthesis.

关键词： graphdiyne derivative tetraphenylethylene topology modulation aggregation-induced emission(AIE)two-dimensional(2D)polymers interfacial synthesis

All-dielectric bowtie waveguide with deep subwavelength mode confinement

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Frontiers of physics 2018年第4期13卷 229-235页

作者： Wen-Cheng Yue pei-jun yao Li-Xin Xu Hai Ming Department of Optics and Optical Engineering University of Science and Technology of China Hefei 230026 China

Plasmonic waveguides and conventional dielectric waveguides have favorable characteristics in photonic integrated circuits. Typically, plasmonic waveguides can provide subwavelength mode confinement, as shown by their small mode area, whereas conventional dielectric waveguides guide light with low loss, as shown by their long propagation length. However, the simultaneous achievement of subwavelength mode confinement and low-loss propagation remains limited. In this paper, we propose a novel design of an all- dielectric bowtie waveguide, which simultaneously exhibits both subwavelength mode confinement and theoretically lossless propagation. Contrary to traditional dielectric waveguides, where the guidance of light is based on total internal reflection, the principle of the all-dielectric bowtie waveguide is based on the combined use of the conservation of the normal component of the electric displacement and the tangential component of the electric field, such that it can achieve a mode area comparable to its plasmonic counterparts. The mode distribution in the all-dielectric bowtie waveguide can be precisely controlled by manipulating the geometric design. Our work shows that it is possible to achieve extreme light confinement by using dielectric instead of lossy metals.

关键词： dielectric waveguide nanophotonics plasmonics photonic integrated circuits silicon

Permanent lining castable with low bulk density and thermal conductivity:bauxite castable for tundish obtained by adding pearlescent sand

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Journal of Iron and Steel Research(International) 2024年第3期31卷 634-646页

作者： Yi Wang Jian Yang Bao Wang Hai-jun Zhang Juan Han pei-yan pei Wen-long Lv Jian-an Zhou The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081HubeiChina Wuhan Research Institute of Metallurgical Construction MCCWuhan 430081HubeiChina

The low thermal conductivity and light mass of castables for tundish permanent linings are crucial for minimizing the heat loss of molten *** consideration of the low bulk density and thermal conductivity of pearlescent sand,the thermal insulation performance of castables was attempted to be improved by adding pearlescent *** sand was modified to prevent the strength of its porous structure from *** modification mechanism of pearlescent sand and the effect of pearlescent sand on the performance of bauxite castables were *** results suggested that the addition of the modified pearlescent sand significantly raised the apparent porosity and decreased the bulk density of bauxite *** 1000℃,the bulk density of more than 60%of the modified pearlescent sand-bauxite castable was only 2.03 g/cm^(3).The mechanical properties and thermal shock resistance of the modified pearlescent sand-bauxite castable were inferior to those of conventional bauxite castable but were adequate to meet the use conditions of casta-bles for tundish permanent *** high temperatures of 200-800℃,the thermal conductivity of more than 60%of the modified pearlescent sand-bauxite castable was smaller than that of conventional bauxite *** addition of the modified pearlescent sand can greatly reduce the thermal conductivity and bulk density of bauxite castable.

关键词： Pearlescent sand-Hydrophobic modification Bauxite castable Thermal insulation performance Mechanical property

Dynamic Couplingand Cooperative Control for Multi-paralleled Doubly Fed Induction Generator Wind Farms during Symmetrical Low Voltage Ride-through in a Weak Grid

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Protection and Control of Modern Power Systems 2024年第3期9卷 112-125页

作者： Lei Guan jun yao the College of Electrical Engineering at Chongqing University ChongqingChina the State Key Laboratory of Power Transmission Equipment Technology School of Electrical EngineeringChongqing UniversityChongqing 400044China

In multi-fed grid-connected systems,there are complex dynamic interactions between different pieces of *** in situations of weak-grid faults,the dynamic coupling between equipment becomes more *** may cause the system to experience small-signal instability during the fault *** this paper,multi-paralleled doubly fed induction generator(DFIG)-based wind farms(WFs)are taken as an example to study the dynamic coupling within a multi-fed system during fault steady-state of symmetrical low voltage ride-through(LVRT)in a weak *** analysis reveals that the dynamic coupling between WFs will introduce a damping shift to each *** inevitably affects the system’s dynamic stability and brings the risk of small-signal instability during fault steady-state in LVRT *** the distance to fault location and fault severity will exacerbate the dynamic coupling between *** of the dynamic coupling,adjusting the control state of one WF will affect the stability of the remaining WFs in the ***,a cooperative control strategy for multi-paralleled DFIG WFs is proposed to improve dynamic stability during *** analysis and the effectiveness of the proposed control strategy are verified by modal analysis and simu-lation.

关键词： Doubly fed induction generator(DFIG) wind farms(WFs) dynamic stability low voltage ride through(LVRT) weak grid dynamic coupling

Unraveling the mechanism of potassium metal capacitor for highly efficient charge storage

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Science China Chemistry 2024年第5期67卷 1578-1588页

作者： Qianqian yao pei Tang Kunyao Peng Zhenyuan Miao Yuecong Chen Qingyun Dou Xingbin Yan Department of Materials Science and Engineering Sun Yat-sen UniversityGuangzhou 510275China South China Academy of Advanced Optoelectronics South China Normal UniversityGuangzhou 510006China

Although hybrid metal ion capacitors(MICs) are highly desired to achieve both high power density of supercapacitors and high energy density of rechargeable batteries, the mismatch problem of electrochemical kinetics of negative and positive electrodes in MICs hampers the realization of this goal. Here, a new hybrid capacitor concept-potassium metal capacitor(PMC) is proposed for the first time, where potassium metal and commercial activated carbon(AC) without any modification are applied as negative and positive electrodes, respectively, and the electrolyte is the same as that of non-aqueous potassium ion batteries. The simplest PMC prototype exhibits a good combination of high energy density(184.9 Wh kg^(-1)) and power density(12.4 kW kg^(-1)), which benefits from the synergistic effect of potassium metal and AC electrode. The former experiences fast potassium plating/striping during charging and discharging, and the later possesses complex multiple charge behaviors driven by low potential of potassium metal. Specifically, below open-circuit voltage, transportation of solvated cations in AC pores plays an important role;beyond this voltage, synergy actions of cations and anions, including adsorption/desorption of solvated cations and anions, and ions exchange between them, dominate the capacitance contribution. This work enriches the types of MICs, and deepens the understanding of the energy storage mechanism of non-aqueous hybrid metal capacitors.

关键词： hybrid capacitor potassium metal activated carbon charge storage mechanism