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Effects of benthic hydraulics on sediment oxygen demand in a canyon-shaped deep drinking water reservoir:Experimental and modeling study

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Journal of Environmental Sciences 2021年第4期33卷 226-234页

作者： Nan Li Tinglin Huang Zhiying chang kai Li Key Laboratory of Northwest Water Resource Environment and EcologyMOEXi’an University of Architecture and TechnologyXi’an 710055China Shaanxi Key Laboratory of Environmental Engineering Xi’an University of Architecture and TechnologyXi’an 710055China

Sediment oxygen demand(SOD)is a major contributor to hypolimnetic oxygen depletion and the release of internal nutrient *** measuring the SOD in experimental chambers using in both dissolved oxygen(DO)depletion and diffusional oxygen transfer methods,a model of SOD for a sediment bed with water current-induced turbulence was *** experimental study was also performed using near-sediment vertical DO profiles and correlated hydraulic parameters stimulated using a computational fluid dynamics model to determine how turbulences and DO concentrations in the overlying water affects SOD and diffusive boundary layer *** dependence of the oxygen transfer coefficient and diffusive boundary layer on hydraulic parameters was quantified,and the SOD was expressed as a function of the shear velocity and the bulk DO *** predictions were validated using microelectrode measurements in a series of laboratory *** study found that flow over the sediment surface caused an increase in SOD,attributed to enhanced sediment oxygen uptake and reduced substances fluxes,i.e.,for a constant maximum biological oxygen consumption rate,an increased current over the sediment could increase the SOD by 4.5 times compared to stagnant *** results highlight the importance of considering current-induced SOD increases when designing and implementing aeration/artificial mixing strategies.

关键词： Sediment oxygen demand Sediment-water flux Diffusive boundary layer thickness Turbulence Biological oxygen consumption

Design of novel NiSiAlY alloys in marine salt-spray environment:PartⅠ.Al-Si-Y and Ni-Si-Y subsystems

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Journal of Materials Science & Technology 2021年第29期88卷 66-78页

作者： kai Xu Keke chang Yong Du Liping Wang Key Laboratory of Marine Materials and Related Technologies Zhejiang Key Laboratory of Marine Materials and Protective TechnologiesNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo315201China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing100049China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China

MCrAlY(M=Ni,Co,NiCo)alloys have been widely used as a bond layer for thermal barrier coatings(TBCs).However;oxides form discontinuously on MCrAlY surface in the marine environment since Cr_(2)O_(3)can react with NaCl and H_(2)O at temperatures above 500℃.Replacing Cr with other alloying elements(such as Si)might prevent severe salt-spray corrosion *** save time and efforts in materials design of the Ni-Si-Al-Y system;we obtained the thermodynamic descriptions of the ternary compounds by coupling the CALPHAD(CALculation of PHAse Diagrams)approach and first-principles *** and eighteen ternary compounds were evaluated and calculated in the Al-Si-Y and Ni-Si-Y systems;*** diagrams of the two systems were depicted after a series of experimental Al/Ni-Si-RE(RE denotes rare earth elements,including La,Ce,Pr,Nd,Sm,Gd,Dy,Ho,and Er)systems being *** is found that the RE elements with the same reference states tend to form ternary compounds with the same crystal *** model-based descriptions are the basis for the research and development of novel NiSiAlY alloys in resisting high-temperature corrosion.

关键词： Ternary compounds NiSiAlY CALPHAD Formation enthalpy Rare earth elements

Suppression of Cs FAD3 in a JA-dependent manner,but not through the SA pathway,impairs drought stress tolerance in tea

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Journal of Integrative Agriculture 2024年第11期23卷 3737-3750页

作者： Na chang Xiaotian pi Ziwen Zhou Yeyun Li Xianchen Zhang State Key Laboratory of Tea Plant Biology and Utilization Anhui Agricultural UniversityHefei 230036China

The growth and yield of tea plants are seriously limited by drought *** acid desaturases(FADs)contribute to the mediation of membrane fluidity in response to different stresses,although the role ofω-3 FAD(Omega-3fatty acid desaturase)-mediated damage induced by drought stress in tea plants is poorly *** this study,drought stress significantly promoted the synthesis of C18:3(linolenic acid)and the expression level of *** experiments further demonstrated that CsFAD3 can convert C18:2 to C18:3,and that the 35S:GFP-CsFAD3fusion protein was localized in the endoplasmic reticulum of Nicotiana benthamiana ***3-silenced tea leaves exhibited poor drought tolerance,with a lower F_(v)/F_(m)and a higher malondialdehyde(MDA)content than the control ***,transgenic 35S:CsFAD3 Arabidopsis plants showed the opposite *** addition,the jasmonic acid(JA)content and the expression levels of CsLOX2,CsLOX4,CsAOS,CsAOC3 and CsOPR2 were significantly reduced in CsFAD3-silenced leaves under drought ***,no substantial difference in the salicylic acid(SA)content was detected under normal or drought *** analysis of Atcoi1(JA receptor)or Atnpr1(SA receptor)mutant Arabidopsis plants in 35S:CsFAD3 backgrounds further revealed that knockout of Atcoi1impaired the drought-tolerant phenotypes of CsFAD3 overexpression ***,this study demonstrated that CsFAD3 plays a crucial role in drought tolerance by mediating JA pathways.

关键词： tea plants CsFAD3 drought stress jasmonic acid

On the energy conversion in electrokinetic transports

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Applied Mathematics and Mechanics(English Edition) 2022年第2期43卷 263-274页

作者： Zhaodong DING Long chang kai TIAN Yongjun JIAN School of Mathematical Science Inner Mongolia UniversityHohhotInner Mongolia010021China School of Statistics and Mathematics Inner Mongolia University of Finance and EconomicsHohhotInner Mongolia010021China

Energy conversion in micro/nano-systems is a subject of current research,among which the electrokinetic energy conversion has attracted extensive ***,there exist two different definitions on the electrokinetic energy conversion efficiency in literature.A few researchers defined the efficiency using the pure pressure-driven flow rate,while other groups defined the efficiency based on the flow rate with the inclusion of the effect of the streaming potential *** this work,both definitions are investigated for different fluid types under the periodic electrokinetic flow *** Newtonian fluids,the two definitions give similar ***,for viscoelastic fluids,these two definitions lead to significant *** efficiency defined by the pure pressure-driven flow rate even exceeds 100%in a certain range of the *** result shows that in the case of viscoelastic flow,it is incorrect to define the energy conversion efficiency by pure pressure-driven flow *** the same time,the reason for this problem is clarified through comprehensive analysis.

关键词： electrokinetic transport energy conversion efficiency Newtonian fluid viscoelastic fluid streaming potential field

Integrating BDS and GPS for precise relative orbit determination of LEO formation flying

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Chinese Journal of Aeronautics 2018年第10期31卷 2013-2022页

作者： Bin YI Defeng GU Xiao chang kai SHAO College of Liberal Arts and Sciences National University of Defense Technology

Low-Earth-Orbit（LEO） formation-flying satellites have been widely applied in many kinds of space geodesy. Precise Relative Orbit Determination（PROD） is an essential prerequisite for the LEO formation-flying satellites to complete their mission in space. The contribution of the BeiDou Navigation Satellite System（BDS） to the accuracy and reliability of PROD of LEO formation-flying satellites based on a Global Positioning System（GPS） is studied using a simulation method. Firstly, when BDS is added to GPS, the mean number of visible satellites increases from9.71 to 21.58. Secondly, the results show that the 3-Dimensional（3 D） accuracy of PROD, based on BDS-only, GPS-only and BDS ＋ GPS, is 0.74 mm, 0.66 mm and 0.52 mm, respectively. When BDS co-works with GPS, the accuracy increases by 29.73%. Geostationary-Earth-Orbit（GEO） satellites and Inclined Geosynchronous-Orbit（IGSO） satellites are only distributed over the Asia-Pacific region; however, they could provide a global improvement to PROD. The difference in PROD results between the Asia-Pacific region and the non-Asia-Pacific region is not apparent. Furthermore, the value of the Ambiguity Dilution Of Precision（ADOP）, based on BDS ＋ GPS, decreases by 7.50% and 8.26%, respectively, compared with BDS-only and GPS-only. Finally, if the relative position between satellites is only a few kilometres, the effect of ephemeris errors on PROD could be ignored. However, for a several-hundred-kilometre separation of the LEO satellites, the SingleDifference（SD） ephemeris errors of GEO satellites would be on the order of centimetres. The experimental results show that when IGSO satellites and Medium-Earth-Orbit（MEO） satellites co-work with GEO satellites, the accuracy decreases by 17.02%.

关键词： Ambiguity Dilution Of Precision BeiDou Navigation Satellite System Geostationary-Earth-Orbit Global Positioning System LEO formation flying Precise Relative Orbit Determination

Real-time prediction of the peak suspended sediment concentration and sediment yield of the Lao-Nung River during storms

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International Journal of Sediment Research 2011年第2期26卷 163-180页

作者： pi-Chih HSU Ching-Nuo CHEN chang-Tai TASI Department of Constructing Engineering Nan Jeon Institute of Technologyand Ph.D.CandidateDepartment of Hydraulic and Ocean EngineeringNational Cheng-Kung University Department of Hydraulic and Ocean Engineering National Cheng-Kung University

Based on rainfall erosion of soil and suspended sediment transport in storm events,a method is proposed to predict peak suspended sediment concentration and suspended sediment yield in watersheds based on rainfall characteristics prior to peak rainfall *** rainfall characteristics factors that dominate peak suspended sediment concentration Cpare rainfall erosion factor Ref, first peak rainfall intensity of area-average rainfall ip1and antecedent precipitation index Iap;the rainfall characteristics factors that dominate suspended sediment yield Yssin storm events are total rainfall P,suspended sediment yield factor Rsfand antecedent precipitation index *** research focuses on watersheds in Liau-Kwei observation station along Lao-Nung River in southern Taiwan as the research object,and adopts the PSED-model to simulate the discharge hydrograph, suspended sediment concentration hydrograph and suspended sediment yield in 11 storm events for *** analytical results show that there is a good correlation between the above-mentioned rainfall characteristics factors and CPas well as Yss,thus enabling Cpand Yssto be predicted by using Expressions(13) and(14).These two expressions are utilized to predict CPand Yssof Typhoon Morakot in 2009,and the results are compared with those from simulation by using the *** result of comparison shows there is a good capability in *** the watersheds where it is necessary to predict CPand Yssof a storm event for the benefit of effective operation of water resource facilities,the aforesaid rainfall characteristics factors can be utilized to establish applicable models for prediction.

关键词： Lao-Nung River Sediment Peak suspended sediment concentration PSED Morakot

Effect of Electric Field on the Electron-Surface Optical Phonon Scattering Rates in Quantum Wires

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Chinese Physics Letters 1996年第4期13卷 297-300页

作者： chang kai WANG Ruo-zhen MA Ben-kun Department of Physics Beijing Normal UniversityBeijing 100875

By using the variational method and the dielectric continuum model,we investigate the effect of electric Held on the intrasubband scattering rates of electron-surface optical *** results show that the scattering rates tend to increase with the electric field *** scattering rates become significant for wide quantum well wire and sufficiently high fields.

关键词： strength. Electron variational

Exciton Vortices in Two-Dimensional Hybrid Perovskite Monolayers

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Chinese Physics Letters 2020年第11期37卷 65-69页

作者： Yingda Chen Dong Zhang kai chang State Key Laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China Beijing Academy of Quantum Information Sciences Beijing 100193China

We study theoretically the exciton Bose–Einstein condensation and exciton vortices in a two-dimensional(2 D)perovskite(PEA)2 Pb I4 *** the first-principles calculations and the Keldysh model,the exciton binding energy of in a(PEA)2 Pb I4 monolayer can approach hundreds of me V,which make it possible to observe the excitonic effect at room *** to the large exciton binding energy,and hence the high density of excitons,we find that the critical temperature of the exciton condensation could approach the liquid nitrogen *** the presence of perpendicular electric fields,the dipole-dipole interaction between excitons is found to drive the condensed excitons confined in(PEA)2 Pb I4 monolayer flakes into patterned vortices,as the evolution time of vortex patterns is comparable to the exciton lifetime.

关键词： temperature. monolayer dipole

Even-odd-dependent optical transitions of zigzag monolayer black phosphorus nanoribbons

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Science China(Physics,Mechanics & Astronomy) 2021年第1期64卷 91-101页

作者： Pu Liu XianZhe Zhu XiaoYing Zhou GuangHui Zhou kai chang Department of Physics Key Laboratory for Low-Dimensional Structures and Quantum Manipulation(Ministry of Education)Synergetic Innovation Center for Quantum Effects and Applications of HunanHunan Normal UniversityChangsha410081China SKLSM Institute of SemiconductorsChinese Academy of SciencesBeijing100083China

We analytically study the electronic structure and optical properties of zigzag-edged phosphorene nanoribbons(ZPNRs) using the tight-binding Hamiltonian and Kubo formula. By directly solving the discrete Schrodinger equation, we obtain the energy spectra and wavefunctions for N-ZPNR(where N is the number of transverse zigzag atomic chains) and classify the eigenstates according to the lattice symmetry. Then, we obtain the optical transition selection rule of ZPNRs on the basis of symmetry analysis and analytical expressions of optical transition matrix elements. Under incident light that is linearly polarized along the ribbon, we determine that the optical transition selection rule for N-ZPNR with even-or odd-N is qualitatively different. Specifically, for even-N ZPNRs, the inter-(intra-) band selection rule is ?n =odd(even) because the parity of the wavefunction corresponding to the n-th subband in the conduction(valence) band is(-1)~n[(-1)~((n+1))] owing to the presence of C(2x) symmetry. However, the optical transitions between any subbands are possible owing to the absence of C(2x) symmetry. Our results provide a further understanding on the electronic states and optical properties of ZPNRs, which are useful for explaining the optical experiment data on ZPNR samples.

关键词： zigzag-edged phosphorene nanoribbons band structure light absorption selection rules