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State-of-the-art progress in overall water splitting of carbon nitride based photocatalysts

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Frontiers in Energy 2021年第3期15卷 600-620页

作者： Bing LUO yuxin zhao Dengwei JING School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049China International Research Center for Renewable Energy and State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Converting solar energy into hydrogen(H_(2))by photocatalytic water splitting is a promising approach to simultaneously address the increasing energy demand and environmental *** decade has passed since the discovery of photo-induced water splitting phenomenon on TiO_(2)photoanode,while the solar to H_(2) efficiency is still around 1%,far below the least industrial ***,developing efficient photocatalyst with a high energy conversion efficiency is still one of the main tasks to be *** carbon nitride(g-C_(3)N_(4))is just such an emerging and potential ***,in this review,the state-of-the-art advances in g-C_(3)N_(4)based photocatalysts for overall water splitting were summarized in three sections according to the strategies used,and future challenges and new directions were discussed.

关键词： photocatalysis overall water splitting carbon nitride hydrogen

Imaging of the Space-time Structure of a Vortex Generator in Supersonic Flow

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Chinese Journal of Aeronautics 2012年第1期25卷 57-63页

作者： WANG Dengpan XIA Zhixun zhao yuxin WANG Bo zhao Yanhui Science and Technology on Scramjet Laboratory National University of Defense TechnologyChangsha 410073China

The fine space-time structure of a vortex generator （VG） in supersonic flow is studied with the nanoparticle-based planar laser scattering （NPLS） method in a quiet supersonic wind tunnel. The fine coherent structure at the symmetrical plane of the flow field around the VG is imaged with NPLS. The spatial structure and temporal evolution characteristics of the vortical structure are analyzed, which demonstrate periodic evolution and similar geometry, and the characteristics of rapid movement and slow change. Because the NPLS system yields the flow images at high temporal and spatial resolutions, from these images the position of a large scale structure can be extracted precisely. The position and velocity of the large scale structures can be evaluated with edge detection and correlation algorithms. The shocklet structures induced by vortices are imaged, from which the generation and development of shocklets are discussed in this paper.

关键词： vortex generator nanoparticle-based planar laser scattering vortical structure evolution characteristic shocklet

Experimental investigation on transverse jet penetration into a supersonic turbulent crossflow

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Science China(Technological Sciences) 2013年第8期56卷 1989-1998页

作者： SUN MingBo ZHANG ShunPing zhao YanHui zhao yuxin LIANG JianHan Science and Technology on Scramjet Laboratory National University of Defense Technology

The paper evaluates the evolvement of coherent structures and penetration height of gaseous transverse jet penetration into a supersonic turbulent *** high spatiotemporal resolution coherent structures of the jet plume are obtained by utilizing the nanoparticle-based planar laser scattering technique(NPLS).The evolving pattern of the coherent structures generated on the upwind surface of the transverse jet is analyzed based on the NPLS *** shedding eddies from the jet near-field have lower convection velocity along freestream direction,while vortex growth rate is apparently higher than the *** downstream,the large-scale eddies have less deformation and translate at velocities near the freestream *** the near-field determines the scale of eddies in the far-field and affects the whole mixing *** effect of injection stagnation pressure on the coherent structures is discussed and a modified penetration correlation is proposed based on an edge approximation definition and least square method with various injection pressures.

关键词： supersonic flow transverse jet penetration nanoparticle-based planar laser scattering(NPLS)

Multi-resolution Analysis of Density Fluctuation of Coherent Structures About Supersonic Flow over VG

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Chinese Journal of Aeronautics 2012年第2期25卷 173-181页

作者： WANG Dengpan zhao yuxin XIA Zhixun WANG Qinghua HUANG Xu Science and Technology on Scramjet Laboratory National University of Defense Technology Changsha 410073 China The ThirdInstitute the SecondArtillery Equipment Academy Beijing 100085 China

The density field around a vortex generator （VG） in supersonic flow is studied with a nanoparticle-based planar laser scattering （NPLS） method. Based on the calibration, i.e., the density distribution of the supersonic flow around a wedge, the density field of a supersonic VG is measured. According to movement characteristics of coherent structure in VG’s flow fields and the basic concepts of wavelet, the density fluctuating signals and multi-resolution characteristics of density field images are studied. The multi-resolution characteristics of density fluctuation can be analyzed with wavelet transformation of NPLS images. The wavelet approximate coefficients of density fluctuating signals exhibit their characteristics at different scales, and the corresponding detail coefficients show the difference of diverse layer smooth approximation in some way. Based on 2D wavelet decomposition and reconstruction of density field images, the approximate and detail signals at different scales are studied, and the coherent structures at different scales are extracted and analyzed.

关键词： vortex generator nanoparticle-based planar laser scattering coherent structure density fluctuation multi-resolution analysis

Multiobjective optimal dispatch of microgrid based on analytic hierarchy process and quantum particle swarm optimization

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Global Energy Interconnection 2020年第6期3卷 562-570页

作者： yuxin zhao Xiaotong Song Fei Wang Dawei Cui School of Electrical and Control Engineering North China University of TechnologyBeijing 100144P.R.China State Grid Shandong Electric Power Company Jinan 250001P.R.China State Grid Brazil Holding S.A. Rio de Janeiro20071-004RJBrasil

Owing to the rapid development of microgrids(MGs)and growing applications of renewable energy resources,multiobjective optimal dispatch of MGs need to be studied in *** this study,a multiobjective optimal dispatch model is developed for a standalone MG composed of wind turbines,photovoltaics,diesel engine unit,load,and battery energy storage *** economic cost,environmental concerns,and power supply consistency are expressed via subobjectives with varying ***,the analytic hierarchy process algorithm is employed to reasonably specify the weight coefficients of the *** quantum particle swarm optimization algorithm is thereafter employed as a solution to achieve optimal dispatch of the ***,the validity of the proposed model and solution methodology are con firmed by case *** study provides refere nee for mathematical model of multiojective optimizati on of MG and can be widely used in current research field.

关键词： Analytic hierarchy process(AHP) Quantum particle swarm optimization(QPSO) Multiobjective optimal dispatch Microgrid.

A flow control study of a supersonic mixing layer via NPLS

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Science China(Physics,Mechanics & Astronomy) 2009年第12期52卷 2001-2006页

作者： YI ShiHe HE Lin zhao yuxin TIAN LiFeng CHENG ZhongYu College of Aerospace and Material Engineering National University of Defense TechnologyChangsha 410073China

The flow control of a supersonic mixing layer was studied in a supersonic mixing layer wind tunnel with convective Mach number (Mc) at 0.5. The passive control of the mixing layer was achieved by perturbation tapes on the trailing edge of the splitter plate. The control effects of 2D and 3D perturbation tapes with different sizes were compared. The mixing layer was visualized via NPLS,and the transient fine structures were identifiable in NPLS images,which were used to analyze the effects of flow control. The results show that the 2D tapes can enhance the 2D characteristic of the mixing layer,delaying mixing layer transition; and the 3D tapes can enhance the 3D characteristic of the mixing layer,advancing mixing layer transition. 3D structures of the mixing layer were visualized,and the H-type Λ vortexes were found with 3D tapes control.

关键词： supersonic mixing layer NPLS flow control

Study of density field measurement based on NPLS technique in supersonic flow

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Science China(Physics,Mechanics & Astronomy) 2009年第9期52卷 1357-1363页

作者： TIAN LiFeng YI ShiHe zhao yuxin HE Lin CHENG ZhongYu College of Aerospace and Material Engineering National University of Defense TechnologyChangsha 410073China

Due to the influence of shock wave and turbulence, supersonic density field exhibits strongly inhomogeneous and unsteady characteristics. Applying traditional density field measurement techniques to supersonic flows yields three problems: low spatiotemporal resolution, limitation of measuring 3D density field, and low signal to noise ratio (SNR). A new method based on Nano-based Planar Laser Scattering (NPLS) technique is proposed in this paper to measure supersonic density field. This method measures planar transient density field in 3D supersonic flow by calibrating the relationship between density and concentration of tracer particles, which would display the density fluctuation due to the influence of shock waves and vortexes. The application of this new method to density field measurement of supersonic optical bow cap is introduced in this paper, and the results reveal shock wave, turbulent boundary layer in the flow with the spatial resolution of 93.2 μm/pixel. By analyzing the results at interval of 5 μs, temporal evolution of density field can be observed.

关键词： NPLS supersonic density field high spatiotemporal resolution

The fractal measurement of experimental images of supersonic turbulent mixing layer

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Science China(Physics,Mechanics & Astronomy) 2008年第8期51卷 1134-1143页

作者： zhao yuxin YI ShiHe TIAN LiFeng HE Lin CHENG ZhongYu College of Aerospace and Material Engineering National University of Defense TechnologyChangsha 410073China

Flow visualization of supersonic mixing layer has been studied based on the high spatiotemporal resolution Nano-based Planar Laser Scattering(NPLS) method in SML-1 wind tunnel. The corresponding images distinctly reproduced the flow structure of laminar,transitional and turbulent region,with which the fractal measurement can be implemented. Two methods of measuring fractal dimension were introduced and compared. The fractal dimension of the transitional region and the fully developing turbulence region of supersonic mixing layer were measured based on the box-counting method. In the transitional region,the fractal dimension will increase with turbulent intensity. In the fully developing turbulent region,the fractal dimension will not vary apparently for different flow structures,which em-bodies the self-similarity of supersonic turbulence.

关键词： NPLS turbulence mixing layer fractal dimension

Suppression of weeds and weed seeds in the soil by stubbles and no-tillage in an arid maize-winter wheat-common vetch rotation on the Loess Plateau of China

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Journal of Arid Land 2018年第5期10卷 809-820页

作者： YANG Mei zhao yuxin YANG Huimin SHEN Yuying ZHANG Xiaoyan State Key Laboratory of Grassland Agro-ecosystems College of Pastoral Agriculture Science and Technology Lanzhou University

Reduced tillage provides ecological and economic benefits to arable land on the Loess Plateau of China, where soil erosion has long been a serious problem and soil water availability is largely restricted. However, high abundances of weeds in reduced tillage systems cause significant yield losses. In this study, we explored the effects of no-tillage and stubble retention on the number and density of weeds and weed seeds in a 12-year maize-winter wheat-common vetch rotation on the Loess Plateau. Four treatments including conventional tillage, no-tillage, conventional tillage＋stubble retention and no-tillage＋stubble retention were designed and applied. We found that no-tillage increased the number of weed species and weed density in most of the crops, while stubble retention decreased weed density in maize and tended to suppress weeds in both no-tillage treatments（no-tillage and no-tillage＋stubble retention）. No-tillage led to an increase in the number of weed species in the weed seedbank and tended to increase seed density during the spring growth of winter wheat, but it decreased seed density during post-vetch fallow. Stubble retention tended to reduce seed density during the spring growth of winter wheat and post-vetch fallow. We concluded that no-tillage can promote weeds in the experimental crop rotation, while stubble retention suppresses weeds in untilled fields. The combined effects of stubble retention and no-tillage on weed suppression varied among the three crops. Based on these results, we recommend stubble retention in untilled legume-crop rotations on the Loess Plateau to improve the control of weeds.

关键词： agricultural conservation practice crop rotation no-tillage rainfed soil soil seedbank stubble retention weed control