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Computational 4D imaging of light-in-flight with relativistic effects

Photonics Research 2020年第7期8卷 1072-1078页

作者： Yue Zheng ming-jie sun Zhi-Guang Wang Daniele Faccio School of Instrumentation Science and Opto-electronic Engineering Beihang UniversityBeijing 100191China School of Physics Beihang UniversityBeijing 100191China School of Physics and Astronomy University of GlasgowGlasgow G128QQUK

Light-in-flight imaging enables the visualization and characterization of light propagation,which provides essential information for the study of the fundamental phenomena of light.A camera images an object by sensing the light emitted or reflected from it,and interestingly,when a light pulse itself is to be imaged,the relativistic effects,caused by the fact that the distance a pulse travels between consecutive frames is of the same scale as the distance that scattered photons travel from the pulse to the camera,must be accounted for to acquire accurate space–time information of the light ***,we propose a computational light-in-flight imaging scheme that records the projection of light-in-flight on a transverse x-y plane using a single-photon avalanche diode camera,calculates z and t information of light-in-flight via an optical model,and therefore reconstructs its accurate(x,y,z,t)four-dimensional *** proposed scheme compensates the temporal distortion in the recorded arrival time to retrieve the accurate time of a light pulse,with respect to its corresponding spatial location,without performing any extra *** light-in-flight imaging in a threedimensional space of 375 mm×75 mm×50 mm is performed,showing that the position error is 1.75 mm,and the time error is 3.84 ps despite the fact that the camera time resolution is 55 ps,demonstrating the feasibility of the proposed *** work provides a method to expand the recording and measuring of repeatable transient events with extremely weak scattering to four dimensions and can be applied to the observation of optical phenomena with ps temporal resolution.

关键词： relativistic dimensions scattered

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First-photon imaging via a hybrid penalty

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Photonics Research 2020年第3期8卷 325-330页

作者： XIAO PENG XIN-YU ZHAO LI-JING LI ming-jie sun School of Instrumentation and Optoelectronic Engineering Beihang UniversityBeijing 100191China

First-photon imaging is a photon-efficient,computational imaging technique that reconstructs an image by recording only the first-photon arrival event at each spatial location and then optimizing the recorded photon *** optimization algorithm plays a vital role in image formation.A natural scene containing spatial correlation can be reconstructed by maximum likelihood of all spatial locations constrained with a sparsity regularization penalty,and different penalties lead to different *** l1-norm penalty of wavelet transform reconstructs major features but blurs edges and high-frequency details of the *** total variational penalty preserves edges better;however,it induces a"staircase effect,"which degrades image *** this work,we proposed a hybrid penalty to reconstruct better edge features while suppressing the staircase effect by combining wavelet l1-norm and total variation into one penalty *** of numerical simulations indicate that the proposed hybrid penalty reconstructed better images,which have an averaged root mean square error of 12.83%,5.68%,and 10.56%smaller than those of the images reconstructed by using only wavelet l1-norm penalty,total variation penalty,or recursive dyadic partitions method,*** results are in good agreement with the numerical ones,demonstrating the feasibility of the proposed hybrid *** been verified in a first-photon imaging system,the proposed hybrid penalty can be applied to other noise-removal optimization problems.

关键词： function. penalty photon

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A Quasi-Linear Relationship between Planetary Outgoing Longwave Radiation and Surface Temperature in a Radiative-Convective-Transportive Climate Model of a Gray Atmosphere

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Advances in Atmospheric Sciences 2024年第1期41卷 8-18页

作者： jie sun Michael SECOR ming CAI Xiaoming HU Department of Earth Oceanand Atmospheric ScienceFlorida State UniversityTallahasseeFlorida 32304USA School of Atmospheric Sciences Sun Yat-sen University and Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Zhuhai 519082China

In this study,we put forward a radiative-convective-transportive energy balance model of a gray atmosphere to examine individual roles of the greenhouse effect of water vapor,vertical convection,and atmospheric poleward energy transport as well as their combined effects for a quasi-linear relationship between the outgoing longwave radiation(OLR)and surface temperature(T_(S)).The greenhouse effect of water vapor enhances the meridional gradient of surface temperature,thereby directly contributing to a quasi-linear OLR-T_(S) *** atmospheric poleward energy transport decreases the meridional gradient of surface *** a result of the poleward energy transport,tropical(high-latitude)atmosphere-surface columns emit less(more)OLR than the solar energy input at their respective locations,causing a substantial reduction of the meridional gradient of the *** combined effect of reducing the meridional gradients of both OLR and surface temperature by the poleward energy transport also contributes to the quasi-linear OLR-T_(S) *** convective energy transport reduces the meridional gradient of surface temperature without affecting the meridional gradient of OLR,thereby suppressing part of the reduction to the increasing rate of OLR with surface temperature by the greenhouse effect of water vapor and poleward energy *** of the nature of the energy balance in the climate system,such a quasi-linear relationship is also a good approximation for the relationship between the annual-mean net downward solar energy flux at the top of the atmosphere and surface temperature.

关键词： outgoing longwave radiation greenhouse effect poleward energy transport

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Fluorescent carbon dots synthesized in solid phase and air for application in LEDs

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Nano Research 2024年第9期17卷 8495-8503页

作者： Wei-jie Zheng Zhao-Nan sun Yi-ming Wang Huan-ming Xiong Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan UniversityShanghai 200438China

Carbon dots(CDs)have been widely adopted as optical materials because of their excellent luminescent ***,most of the reported synthetic methods are conducted in solvents,especially hydrothermal/solvothermal reactions,leading to intractable problems such as toxic and flammable solvents,complex and inseparable by-products,and dangerously high pressures and ***-phase synthesis of CDs in air is an effective solution to overcome the above issues,but solid reactions always result in uncontrolled growth and agglomeration of *** this study,some inorganic salts are selected as catalysts for synthesizing CDs in solid states and air,which also play as dispersants to hinder CDs *** the meantime,some aromatic derivatives containing hydroxyl and amino groups are chosen as carbon sources,ground with the optimized catalyst,and then heated together in *** production yields are affected by the reaction time and reactant ratio,while the graphitization degrees of the CDs are determined by the reaction *** IG/ID value of their Raman spectra increases from 0.59 to 0.85,and the particle size decreases from 2.5 to 1.4 nm when the synthesis temperature is increased from 200 to 280℃.The as-prepared CDs show emission peaks ranging from 366 to 606 nm,with the photoluminescence(PL)quantum yield up to 53%.Their emission color variation mainly results from different carbon sources,which can be ascribed to the differences in the element composition,functional groups,and graphitic nitrogen content of these *** dispersing CDs of different concentrations into polyvinyl alcohol(PVA)and combining them with blue LEDs,cold,standard,and warm white light emitting devices(WLEDs)are prepared,with a color rendering index(CRI)up to *** the as-prepared CDs have antioxidant ability at high temperature,the as-prepared WLEDs have long lifespans,remaining the effective white luminescence after 72 h continuous work.

关键词： carbon dot solid-phase synthesis white LED photoluminescence inorganic salt catalysis

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Effect of Mg and Fe Doping on Optical Absorption of LiNbO3 Crystal through First Principles Calculations

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Chinese Physics Letters 2014年第3期31卷 125-128页

作者： HUANG Duo-Hui YANG Jun-Sheng CAO Qi-Long WAN ming-jie LI Qiang sun Liang WANd Fan- Hou Computational Physics Key Laboratory of Sichuan Province Yibin University Yibin 644007

Using first principles calculations, we investigate the structural, optical, and electronic properties of LiNbO3 （LN） and M doped LN （M=Mg, Fe）. The density of states are calculated to analyze the effect of doping Mg and Fe ions on the absorption spectra and electronic properties of LN. The results show an ultraviolet shift in the optical absorption edge of Mg-doped LN compared with that of intrinsic LN. On the contrary, the absorption edge of Fe-doped LN crystal reveals a red shift. The optical absorption spectra show an improved optical response in the visible range for Mg-doped LN, which significantly differs from that obtained for Fe-doped LN. The electronic excitations from the valence band to the conduction band of LN leads to an improved optical absorption response in the visible region as observed experimentally. The obvious changes of the doped LN crystal are found in some cases, which provide a helpful guide for preparing doped LN crystal.

关键词： LITHIUM niobate -- Optical properties RESEARCH SEMICONDUCTOR doping LIGHT absorption MAGNESIUM PHYSICS research

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Critical approaches in the catalytic transformation of sugar isomerization and epimerization after Fischer-History,challenges,and prospects

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Green Energy & Environment 2024年第3期9卷 435-453页

作者： Da-ming Gao Xun Zhang Haichao Liu Hidemi Fujino Tingzhou Lei Fuan sun jie Zhu Taoli Huhe National-local Joint Engineering Research Center of Biomass Refine and High-Quality Utilization Changzhou UniversityChangzhou213164China Institute of Urban and Rural Mining Research Changzhou UniversityChangzhou213164China Changzhou Key Laboratory of Biomass Green Safe&High Value UtilizationChangzhou UniversityChangzhou213164China Beijing National Laboratory for Molecular Science College of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China Department of Rehabilitation Science Kobe University Graduate School of Health SciencesKobe654-0142Japan

The transformation of aldose to ketose or common sugars into rare saccharides,including rare ketoses and aldoses,is of great value and interest to the food industry and for saccharidic biomass utilization,medicine,and the synthesis of ***,high-fructose corn syrup(HFCS)is industrially produced in more than 10 million tons annually using immobilized glucose *** low-calorie saccharides such as tagatose and psicose,which are becoming popular sweeteners,have also been produced on a pilot scale in order to replace sucrose and ***,current catalysts and catalytic processes are still difficult to utilize in biomass conversion and also have strong substrate dependence in producing high-value,rare *** the specific reaction properties of saccharides and catalysts,since the pioneering discovery by Fischer,various catalysts and catalytic systems have been discovered or developed in attempts to extend the reaction pathways,improve the reaction efficiency,and to potentially produce commercial *** this review,we trace the history of sugar isomerization/epimerization reactions and summarize the important breakthroughs for each reaction as well as the difficulties that remain unresolved to date.

关键词： Rare sugars Isomerization Ketonization Epimerization Catalytic transformation

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Atomistic study on the microscopic mechanism of grain boundary embrittlement induced by small dense helium bubbles in iron

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Nuclear Science and Techniques 2024年第3期35卷 84-95页

作者： Lei Peng Yong-jie sun Jing-Yi Shi Yi-Fei Liu Shang-ming Chen Liu-Liu Li State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230027China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610213China

The helium bubbles induced by 14 MeV neutron irradiation can cause intergranular fractures in reduced activation ferritic martensitic steel,which is a candidate structural material for fusion *** order to elucidate the susceptibility of different grain boundaries(GBs)to helium-induced embrittlement,the tensile fracture processes of 10 types of GBs with and without helium bubbles in body-centered cubic(bcc)iron at the relevant service temperature of 600 K were investigated via molecular dynamics *** results indicate that in the absence of helium bubbles,the GBs studied here can be classified into two distinct categories:brittle GBs and ductile *** atomic scale analysis shows that the plastic deformation of ductile GB at high temperatures originates from complex plastic deformation mechanisms,including the Bain/Burgers path phase transition and deformation twinning,in which the Bain path phase transition is the most dominant plastic deformation ***,the presence of helium bubbles severely inhibits the plastic deformation channels of the GBs,resulting in a significant decrease in elongation at *** bubble-decorated GBs,the ultimate tensile strength increases with the increase in the misorientation ***,the coherent twin boundary∑3{112}was found to maintain relatively high fracture strength and maximum failure strain under the influence of helium bubbles.

关键词： Helium bubble Grain boundary Embrittlement Reduced activation ferritic martensitic steel Molecular dynamics Bain path

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Subsurface multi-physical characterization of mountain excavation and city construction in loess plateau with a fiber-optic sensing system

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 2935-2946页

作者： jie Liu Bin Shi Kai Gu Meng-Ya sun Jun-Cheng Yao He-ming Han School of Earth Sciences and Engineering Nanjing UniversityNanjingJiangsu210023China Frontiers Science Center for Critical Earth Material Cycling Nanjing UniversityNanjing210023China School of Earth Sciences and Engineering Hohai UniversityNanjing210098China

Mountain excavation and city construction(MECC)projects being launched in the Loess Plateau in China involve the creation of large-scale artificial *** the subsurface evolution characteristics of the artificial land is essential,yet ***,we use an improved fiber-optic monitoring system for its subsurface multi-physical *** system enables us to gather spatiotemporal distribution of various parameters,including strata deformation,temperature,and ***’an New District was selected as a case study to conduct refined in-situ monitoring through a 77 m-deep borehole and a 30 m-long *** reveal that the ground settlement involves both the deformation of the filling loess and the underlying intact ***,the filling loess exhibits a stronger creep capability compared to underlying intact *** deformation along the profile is unevenly distributed,with a positive correlation with soil *** accumulation has been observed at the interface between the filling loess and the underlying intact loess,leading to a significant ***,the temperature and moisture in the filling loess have reached a new equilibrium state,with their depths influenced by atmospheric conditions measuring at 31 m and 26 m,*** refined investigation allows us to identify critical layers that matter the sustainable development of newly created urban areas,and provide improved insights into the evolution mechanisms of land creation.

关键词： Mountain excavation and city construction Fiber-optic monitoring Multi-physical characterization Compacted loess

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Grain boundary engineering for enhancing intergranular damage resistance of ferritic/martensitic steel P92

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Nuclear Science and Techniques 2024年第5期35卷 186-199页

作者： Lei Peng Shang-ming Chen Jing-Yi Shi Yong-jie sun Yi-Fei Liu Yin-Zhong Shen Hong-Ya He Hui-Juan Wang jie Tian State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230027China School of Materials Engineering Shanghai University of Engineering Science333 Long Teng RoadShanghai 201620China Experimental Center of Engineering and Material Science University of Science and Technology of ChinaHefei 230026China

Ferritic/martensitic(F/M)steel is widely used as a structural material in thermal and nuclear power ***,it is susceptible to intergranular damage,which is a critical issue,under service *** this study,to improve the resistance to intergranular damage of F/M steel,a thermomechanical process(TMP)was employed to achieve a grain boundary engineering(GBE)microstructure in F/M steel *** TMP,including cold-rolling thickness reduction of 6%,9%,and 12%,followed by austenitization at 1323 K for 40 min and tempering at 1053 K for 45 min,was applied to the as-received(AR)P92 *** prior austenite grain(PAG)size,prior austenite grain boundary character distribution(GBCD),and connectivity of prior austenite grain boundaries(PAGBs)were *** to the AR specimen,the PAG size did not change *** fraction of coincident site lattice boundaries(CSLBs,3≤Σ≤29)and Σ3^(n) boundaries along PAGBs decreased with increasing reduction ratio because the recrystallization fraction increased with increasing reduction *** PAGB connectivity of the 6%deformed specimen slightly deteriorated compared with that of the AR ***,potentiodynamic polarization studies revealed that the intergranular damage resistance of the studied steel could be improved by increasing the fraction of CSLBs along the PAGBs,indicating that the TMP,which involves low deformation,could enhance the intergranular damage resistance.

关键词： Grain boundary engineering Ferritic/martensitic steel Prior austenite grain boundary character distribution Grain boundary connectivity Intergranular damage resistance

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NiO-Doped Fe_(2)O_(3)/MgO Properties for the Chemical Looping Oxidative Dehydrogenation of Ethane

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China Petroleum Processing & Petrochemical Technology 2024年第1期26卷 27-33页

作者： Liang Hao Chen Junjie sun jie sun Hui Shenyang Ligong University Shenyang 110159China Fushun Ecology Environment Bureau Qingyuan County Branch Fushun 113399China

Ethane chemical looping oxidative dehydrogenation(CL-ODH)to ethylene is a new technology for ethylene ***_(2)O_(3)/MgO oxygen carrier was prepared using the co-precipitation *** influence of added NiO and its different loadings on Fe_(2)O_(3)/MgO were ***,a series of oxygen carriers were applied in the CL-ODH of the ethane cycle ***-Emmett-Teller(BET),X-ray diffractometry(XRD),X-ray photoelection spectroscopy(XPS),and H2-temperature programmed reduction(TPR)were used to characterize the physicochemical properties of these oxygen *** was confirmed that an interaction between NiO and Fe_(2)O_(3) occurred based on the XPS and H2-TPR *** on the CL-ODH activity performance tests conducted in a fixed-bed reactor,it was revealed that ethylene selectivity was significantly improved after NiO ***_(2)O_(3)-10%NiO/MgO showed the best activity performance with 93%ethane conversion and 50%ethylene selectivity at a reaction temperature of 650℃,atmospheric pressure,and space velocity of 7500 mL/(g·h).

关键词： chemical looping oxidative dehydrogenation oxygen carrier Fe_(2)O_(3)/MgO NiO

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