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Gas film/regenerative composite cooling characteristics of the liquid oxygen/liquid methane (LOX/LCH4) rocket engine

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第8期25卷 631-649页

作者： Xinlin LIU jun SUN Zhuohang JIANG Qinglian LI peng CHENG Jie SONG Science and Technology on Scramjet Laboratory College of Aerospace Science and EngineeringNational University of Defense TechnologyChangsha 410073China

The thermal protection of rocket engines is a crucial aspect of rocket engine *** this paper,the gas film/regenerative composite cooling of the liquid oxygen/liquid methane(LOX/LCH4)rocket engine thrust chamber was investigated.A gas film/regenerative composite cooling model was developed based on the Grisson gas film cooling efficiency formula and the one-dimensional regenerative cooling *** accuracy of the model was validated through experiments conducted on a 6 kg/s level gas film/regenerative composite cooling thrust ***,key parameters related to heat transfer performance were *** results demonstrate that the model is sufficiently accurate to be used as a preliminary design *** temperature rise error of the coolant,when compared with the experimental results,was found to be less than 10%.Although the pressure drop error is relatively large,the calculated results still provide valuable guidance for heat transfer *** addition,the performance of composite cooling is observed to be superior to regenerative *** the gas film flow rate results in higher cooling efficiency and a lower gas-side wall ***,the position at which the gas film is introduced greatly impacts the cooling *** optimal introduction position for the gas film is determined when the film is introduced from a single row of *** optimal introduction position results in a more uniform wall temperature distribution and reduces the peak ***,it is observed that a double row of holes,when compared to a single row of holes,enhances the cooling effect in the superposition area of the gas film and further lowers the gas-side wall *** results provide a basis for the design of gas film/regenerative composite cooling systems.

关键词： Liquid oxygen/liquid methane(LOX/LCH4)rocket engine Gas film cooling Regenerative cooling Heat transfer characteristics

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A novel thermally-stable single-phase phosphor Ca_(2)InTaO_(6):Dy^(3+)for NUV-excited white LEDs

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Journal of Rare Earths 2024年第10期42卷 1855-1864页

作者： Jian Hu Ruirui Cui jun Zhang peng Linghu Youzhen Shi Xiang Guo Key Laboratory of Micro-Nano-Electronics and Software Technology of Guizhou Province College of Big Data and Information EngineeringGuizhou UniversityGuiyang550025China College of Computer and Information Engineering Guizhou University of CommerceGuiyang550014China

The work focuses on the utilization of the conventional solid-state sintering procedure to synthesize white phosphors Ca_(2)InTaO_(6):xDy^(3+)(0.02≤x≤0.12).Utilizing X-ray diffraction,the phase structure of samples was examined,and the crystal structure was refined using the Rietveld method.A scanning electron microscope was used to analyze the microstructure of ***-principles calculations confirm that the indirect bandgap of Ca_(2)InTaO_(6)is 3.786 eV,The luminous properties and energy transfer mechanism of Ca_(2)InTaO_(6):xDy^(3+)were studied using photoluminescence ***~4F_(9/2)→~6H_(13/2)transition of Dy^(3+)ions is responsible for the greatest emission peak,which was measured at 575 *** to research,the lifespan falls as the concentration of Dy^(3+)doping amount rises because of frequent interaction and ene rgy transfer between Dy^(3+)*** correlated color temperature of the WLEDs packaged with Ca_(2)InTaO_(6):0.08Dy^(3+)is 4677 K and CIE 1931 chromaticity coordinates are(0.3578,0.3831).Meantime,the phosphor also shows outstanding te mperature stability property,which maintains 83.8%of its initial emission intensity at 450 K(activation energy of 0.1467 eV).The W-LEDs retain their performance for 100 min when powered at 3.4 V voltage and 600 mA current,demonstrating the packed W-LEDs'sustaine d operation at high temperatures.

关键词： Ca_(2)InTaO_(6):Dy^(3+)phosphors Thermal stability Photoluminescence W-LEDs Thermal imaging Rare earths

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Low‑light enhancement method with dual branch feature fusion and learnable regularized attention

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Frontiers of Optoelectronics 2024年第3期17卷 93-111页

作者： Yixiang Sun Mengyao Ni Ming Zhao Zhenyu Yang Yuanlong peng Danhua cao School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China State Grid Information&Telecommunication Branch Beijing 100761China

Restricted by the lighting conditions,the images captured at night tend to sufer from color aberration,noise,and other unfavorable factors,making it difcult for subsequent vision-based *** solve this problem,we propose a two-stage size-controllable low-light enhancement method,named Dual Fusion Enhancement Net(DFEN).The whole algorithm is built on a double U-Net structure,implementing brightness adjustment and detail revision respectively.A dual branch feature fusion module is adopted to enhance its ability of feature extraction and *** also design a learnable regularized attention module to balance the enhancement efect on diferent ***,we introduce a cosine training strategy to smooth the transition of the training target from the brightness adjustment stage to the detail revision stage during the training *** proposed DFEN is tested on several low-light datasets,and the experimental results demonstrate that the algorithm achieves superior enhancement results with the similar *** is worth noting that the lightest DFEN model reaches 11 FPS for image size of 1224×10^(24)in an RTX 3090 GPU.

关键词： Power inspection Low-light enhancement Feature fusion Learnable regularized attention

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Eco-Friendly Encapsulation of Metal Clusters in Porous Organic Cages for Engineerable Microenvironment and Enhanced Catalysis

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CCS Chemistry 2024年第9期6卷 2186-2197页

作者： Siyu Ren Liangxiao Tan jun-Hao Zhou Jian Sun peng Zhang Xingzhong cao Yun-Hong Zhang Jian-Ke Sun MOE Key Laboratory of Cluster Science Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion MaterialsSchool of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 102488 Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049

Developing artificial catalysts that mimic the functionality of enzymes and adapt to the surrounding microenvironment to achieve specific activity and selectivity is a fascinating research area yet remains a great *** this work,we present a meticulously designed strategy for the successful encapsulation of ultrasmall metal clusters(MCs)within an amine-type porous organic cage(POC)through electrostatic complexation,phase transfer,and alcohol reduction *** amine cage showcases an intriguing and customizable feature that allows for the regulation of the surrounding microenvironment of the confined MCs through a feasible postmodifi-cation *** functionalization of cage skeleton further facilitates precise adjustment to the surface electronic state of Pd cluster,thereby influencing the adsorption behavior of ***,this controlled regulation leads to modified activity and chemoselectivity in the catalytic hydrogenation of halogenated ***,the investigation of the correlation between the surrounding microenvironment,substrate adsorption,and catalytic performance in the POC-immobilized MCs system has not been previously *** anticipate that our research will provide valuable insights in this field.

关键词： metal cluster porous organic cage encapsulation microenvironment catalysis

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Co-incorporating green manure and crop straw increases crop productivity and improves soil quality with low greenhouse-gas emissions in a crop rotation

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The Crop Journal 2024年第4期12卷 1233-1241页

作者： Na Zhao Xiquan Wang jun Ma Xiaohong Li Jufeng cao Jie Zhou Linmei Wu Peiyi Zhao Weidong cao Bayannur Academy of Agricultural and Animal Sciences Linhe 015400Inner MongoliaChina College of Agronomy Inner Mongolia Agricultural UniversityHohhot 010019Inner MongoliaChina College of Agriculture Nanjing Agricultural UniversityNanjing 210095JiangsuChina Inner Mongolia Academy of Agricultural&Animal Husbandry Sciences Hohhot 010031Inner MongoliaChina State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China/Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural SciencesBeijing 100081China

In a nine-year field experiment in a wheat-maize-sunflower cropping system in Hetao Irrigation Area,Inner Mongolia,China,organic amendments applied as straw,manure,green manure,and the combination of green manure and straw increased wheat and maize yield,soil aggregate stability,and soil microbial activity in comparison with chemical fertilizer,without changing greenhouse gas emission intensity.

关键词： Green manure Straw Manure Soil organic carbon Soil quality Crop production Diversified cropping

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Construct a 3D microsphere of HMX/B/Al/PTFE to obtain the high energy and combustion reactivity

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Defence Technology（防务技术） 2024年第2期32卷 45-54页

作者： Jian Wang Jie Chen Yaofeng Mao Yongjun Deng Wei cao Fude Nie jun Wang Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621999PR China Shock and Vibration of Engineering Materials and Structures Key Lab of Sichuan Province Mianyang 621010PR China

Metal(aluminum and boron)based energetic materials have been wildly applied in various fields including aerospace,explosives and micro-devices due to their high energy ***,the low combustion efficiency and reactivity of metal fuels,especially boron(B),severely limit their practical ***,multi-component 3D microspheres of HMX/B/Al/PTFE(HBA)have been designed and successfully prepared by emulsion and solvent evaporation method to achieve superior energy and combustion *** reactivity and energy output of HBA are systematically measured by ignitionburning test,constant-volume explosion vessel system and bomb *** to the increased interfacial contact and reaction area,HBA shows higher flame propagation rate,faster pressurization rate and larger combustion heat of 29.95 cm/s,1077 kPa/s,and 6164.43 J/g,which is 1.5 times,3.5 times,and 1.03 times of the physical mixed counterpart(HBA-P).Meanwhile,HBA also shows enhanced energy output and reactivity than 3D microspheres of HMX/B/PTFE(HB)resulting from the high reactivity of *** reaction mechanism of 3D microspheres is comprehensively investigated through combustion emission spectral and thermal analysis(TG-DSC-MS).The superior reactivity and energy of HBA originate from the surface etching of fluorine to the inert shell(Al_(2)O_(3) and B_(2)O_(3))and the initiation effect of Al to *** work offers a promising approach to design and prepare high-performance energetic materials for the practical applications.

关键词： HMX/B/Al/PTFE 3D microspheres Surface etching Reaction mechanism

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The anisotropy of suprathermal electrons in the Martian ionosphere

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Earth and Planetary Physics 2024年第3期8卷 459-471页

作者： YuTian cao jun Cui XiaoShu Wu Wenjun Liang RuiQi Fu HaoYu Lu Planetary Environmental and Astrobiological Research Laboratory(PEARL) School of Atmospheric SciencesSun Yat-sen UniversityZhuhai 519082China Key Laboratory of Geospace Environment University of Science&Technology of ChinaChinese Academy of SciencesHefei 230026China Center for Excellence in Comparative Planetology Chinese Academy of SciencesHefei 230026China School of Space and Environment Beihang UniversityBeijing 102206China

Suprathermal electrons are an important population of the Martian ionosphere, either produced by photoionization of atmospheric neutrals or supplied from the Solar Wind (SW). This study is dedicated to an in-depth investigation of the pitch angle distribution of suprathermal electrons at two representative energies, 19−55 eV and 124−356 eV, using the extensive measurements made by the Solar Wind Electron Analyzer on board the Mars Atmosphere and Volatile Evolution. Throughout the study, we focus on the overall degree of anisotropy, defined as the standard deviation of suprathermal electron intensity among different directions which is normalized by the mean omni-directional intensity. The available data reveal the following characteristics: (1) In general, low energy electrons are more isotropic than high energy electrons, and dayside electrons are more isotropic than nightside electrons;(2) On the dayside, the anisotropy increases with increasing altitude at low energies but remains roughly constant at high energies, whereas on the nightside, the anisotropy decreases with increasing altitude at all energies;(3) Electrons tend to be more isotropic in strongly magnetized regions than in weakly magnetized regions, especially on the nightside. These observations indicate that the anisotropy is a useful diagnostic of suprathermal electron transport, for which the conversion between the parallel and perpendicular momenta as required by the conservation of the first adiabatic invariant, along with the atmospheric absorption at low altitudes, are two crucial factors modulating the observed variation of the anisotropy. Our analysis also highlights the different roles on the observed anisotropy exerted by suprathermal electrons of different origins.

关键词： Mars ionosphere suprathermal electron pitch angle distribution

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Large Eddy Simulation of Vertical Structure and Size Density of Deep Layer Clouds

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Advances in Atmospheric Sciences 2024年第8期41卷 1629-1642,1668-1670页

作者： Bangjun cao Xianyu YANG jun WEN Qin HU Ziyuan ZHU School of Atmospheric Sciences Chengdu University of Information TechnologyChengdu 610225China Institute for Geophysics and Meteorology University of CologneCologne 50923Germany

In a convective scheme featuring a discretized cloud size density, the assumed lateral mixing rate is inversely proportional to the exponential coefficient of plume size. This follows a typical assumption of-1, but it has unveiled inherent uncertainties, especially for deep layer clouds. Addressing this knowledge gap, we conducted comprehensive large eddy simulations and comparative analyses focused on terrestrial regions. Our investigation revealed that cloud formation adheres to the tenets of Bernoulli trials, illustrating power-law scaling that remains consistent regardless of the inherent deep layer cloud attributes existing between cloud size and the number of clouds. This scaling paradigm encompasses liquid, ice, and mixed phases in deep layer clouds. The exponent characterizing the interplay between cloud scale and number in the deep layer cloud, specifically for liquid, ice, or mixed-phase clouds, resembles that of shallow convection,but converges closely to zero. This convergence signifies a propensity for diminished cloud numbers and sizes within deep layer clouds. Notably, the infusion of abundant moisture and the release of latent heat by condensation within the lower atmospheric strata make substantial contributions. However, this role in ice phase formation is limited. The emergence of liquid and ice phases in deep layer clouds is facilitated by the latent heat and influenced by the wind shear inherent in the middle levels. These interrelationships hold potential applications in formulating parameterizations and post-processing model outcomes.

关键词： deep layer cloud cloud spatial structure cloud size density large eddy simulation

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B-COPNA resin formation from ethylene tar light fractions:Process development and mechanical exploration by molecular simulation

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Chinese Journal of Chemical Engineering 2024年第6期70卷 118-129页

作者： Hongyan Shen Lingrui Cui Xingguo Wei Yuanqin Zhang Lian Cen jun Xu Fahai cao Engineering Research Center of Large Scale Reactor East China University of Science and TechnologyShanghai 200237China

An efficient utilization strategy of ethylene tar(ET),the main by-product of the ethylene cracking unit,is urgently required to meet demands for modern petrochemical *** the other hand,condensed polynuclear aromatic resin of moderate condensation degree(B-COPNA)is a widely used carbon material due to its superb processability,the production of which is,however,seriously limited by the high cost of raw *** such context,an interesting strategy was proposed in this study for producing B-COPNA resin using crosslinked light fractions of ethylene tar(ETLF,boiling point<260℃)facilitated by molecular simulation.1,4-Benzenedimethanol(PXG)was first selected as the crosslinking agent according to the findings of molecular *** effects of operating conditions,including reactions temperature,crosslinking agent,and catalyst content on the softening point and yield of B-COPNA resin products were then investigated to optimize the *** reaction mechanism of resin production was studied by analyzing the molecular structure and transition state of ETLF and crosslinking *** was shown that PXG exhibited a superior capacity of withdrawing electrons and a higher electrophilic reactivity than other crosslinking *** addition to the highest yield and greatest heat properties,PXG-prepared resin contained the most condensed *** corresponding optimized conditions of resin preparation were 180℃,1:1.9(PXG:ETLF),and 3%(mass)of catalyst content with a resin yield of 78.57%.It was the electrophilic substitution reaction that occurred between the ETLF and crosslinking agent molecules that were responsible for the resin formation,according to the experimental characterization and molecular ***,it was confirmed that the proposed strategy and demonstrated process can achieve a clean and high value-added utilization of ETLF via B-COPNA resin preparation,bringing huge economic value to the current petrochemical industry.

关键词： Ethylene tar Crosslinking COPNA resin Molecular simulation Transient state

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Structural engineering of BaWO_(4)/CsPbX_(3)/CsPb_(2)X_(5)(X=Cl,Br,I)heterostructures towards ultrastable and tunable photoluminescence

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Nano Research 2024年第3期17卷 1636-1645页

作者： peng Liu Yan Xu Bohan Li Yuchi Zhang Hongzhou Lian jun Lin Department of Chemistry College of SciencesNortheastern UniversityShenyang 110819China State Key Laboratory of Rare Earth Resource Utilization Chang Chun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

Construction of lead halide perovskite nanocrystals(LHP NCs)heterostructures is essential to obtain highly stable photoluminescence and expand their ***,a novel self-assembly strategy combining with a solvent-free thermal-assisted synthesis and a water-triggered reaction is developed to subsequently grow BaWO_(4)/CsPbX_(3)/CsPb_(2)X_(5)(X=Cl,Br,I)heterostructures at low nucleation temperature with high *** as-obtained ternary BaWO_(4)/CsPbX_(3)/CsPb_(2)X_(5)(X=Cl,Br,I)heterostructures exhibit remarkably enhanced panchromatic emission and ultrastable luminescence ascribing to the low-defect growth based on lattice *** white light-emitting diodes(WLEDs)have been constructed with a high correlated color temperature(CCT)of 7225 K and luminous efficiency of 74.4 lm·***^(3+)-doped BaWO_(4)/CsPbX_(3)/CsPb_(2)X_(5)(Ln^(3+)=Eu^(3+),Tb^(3+),Dy^(3+),Sm^(3+),Yb^(3+)/Er^(3+))nanocomposites are further designed with excitation-dependent photoluminescence and thermochromic properties,making them excellent candidates for high-level anti-counterfeiting and *** work offers a green and universal approach in assembling CsPbX_(3)(X=Cl,Br,I)on lattice-matched tungstate with adjustable panchromatic emission for versatile optical applications.

关键词： inorganic lead halide perovskites solvent-free synthesis panchromatic emission anti-counterfeiting and encryption application

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