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Acta Metallurgica Sinica(English Letters) 2022年第6期35卷 985-995页

作者： Zijun Liao jiankai kang Qi Luo Caifeng Pan Jiangdong Chen Xiaolong Mo Hanbo Zou Wei Yang Shengzhou Chen School of Chemistry and Chemical Engineering Guangzhou UniversityGuangzhou 510006China Institute of Energy and Catalysis Guangzhou UniversityGuangzhou 510006China Key Laboratory of Fuel Cell Technology of Guangdong Province Guangzhou 510006China

Lithium-rich manganese-based oxides have the advantages of high discharge specific capacity, so they are potential candidates for advanced lithium battery cathode materials. However, they also have drawbacks to be solved such as serious irreversible loss of capacity and voltage decay in the cycling process. Surface coating method was used in this paper to modify the lithium-rich manganese-based oxide(LRMO,Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)) to improve its electrochemical properties. Zirconium-based compounds coated LRMO materials(ZBC@LRMO) were obtained via the reaction of lithium hydroxide with zirconium n-butanol and subsequent thermal treatment at different temperatures. The results of X-ray diffraction and transmission electron microscopy confirm that the crystal structure and composition of the ZBC coating layer vary with the calcination temperature. The coating layer obtained at 600 ℃ is composed of tetragonal ZrO_(2) and Li_(2)ZrO_(3). The ZBC@LRMO sample with tetragonal ZrO =2 and Li_(2)ZrO_(3) composite exhibits the best electrochemical performance: the discharge capacity of ZBC@LRMO can reach 296 mAh g^(-1) at 0.1 C and 120 mAh g^(-1) at high rate of 5 C.

关键词： Lithium-ion battery Cathode material Zirconium-based compounds coating Calcination temperature Electrochemical performance

Multifunctional dopamine-assisted preparation of efficient and stable perovskite solar cells

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Journal of Energy Chemistry 2021年第3期30卷 291-300页

作者： jiankai Zhang Huangzhong Yu School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640GuangdongChina The Key Laboratory of Functional Molecular Solids Ministry of EducationAnhui Normal UniversityWuhu 241000Anhui China Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development Guangzhou 510640GuangdongChina South China Institute of Collaborative Innovation Dongguan 523808GuangdongChina

Perovskite solar cells(PSCs)show great potential for next-generation photovoltaics,due to their excellent optical and electrical ***,defects existing inside the perovskite film impair both the performance and stability of the *** Pb^(2+),uncoordinated I^(-),and metallic Pb(Pb^(0))are the main defects occur during perovskite film preparation and device operation,due to the volatilization of organic cationic *** these defects is a desirable tas k,because they are non-radiative recombination centers that cause open-circuit voltage(VOC)loss and degradation of the perovskite ***,the multifunctional bioactive compound dopamine(DA)is introduced for the first time to control the perovskite film formation and passivate the uncoordinated Pb^(2+)defects via Lewis acid-base *** Pb^(0) and I^(-)defects are effectively suppressed by the DA *** the same time,the DA treatment results in a stronger crystal orientation along the(110)plane and upshifts the valence band of perovskite closer to the highest occupied molecular orbital(HOMO)of the hole transport layer(2,2’,7,7’-tetrakis(N,N’-di-pmethoxyphenylamine)-9,9’-spirobifluorene,spiro-OMeTAD),which is beneficial for charge separation and transport ***,the stability of MAPbI_(3)(MA=CH_(3)NH_(3))PSCs prepared with the DA additive(especially the thermal stability)is effectively improved due to the better crystallinity and lower number of defect trap states of the perovskite *** optimized MAPbI3 PSCs maintain approximately 90% of their original power conversion efficiency(PCE)upon annealing at 85℃ for 120 *** best performance triple-cation perovskite(Cs_(0.05)(FA_(0.83)MA_(0.17))_(0.95)Pb(I_(0.83)Br_(0.17))_(3))(FA=formamidinium)solar cell with ITO/SnO_(2)/Cs_(0.05)(FA_(0.83)MA_(0.17))_(0.95)Pb(I_(0.83)Br_(0.17))_(3):DA/spiro-OMeTAD/MoO_(3)/Ag(ITO=indium tin oxide)structure shows a PCE of 21.03% with negligible hysteresis,which is

关键词： Perovskite solar cell Dopamine Defect Passivation Performance

An Improved Power Flow Method to Cope with Non-smooth Constraints of Integrated Energy Systems

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CSEE Journal of Power and Energy Systems 2022年第6期8卷 1784-1793页

作者： Yuntao Ju jiankai Wang Zifeng Zhang College of Information and Electrical Engineering China Agricultural UniversityBeijing 100083China

Integrated energy system applications can significantly improve energy *** this paper,we establish an integrated energy system containing heat,electricity and *** existing power flow(PF)calculation method applied to integrated energy systems(IESs)does not consider non-smooth constraints,such as the piecewise pipeline friction coefficient and generator buses reactive power limits,*** integer nonlinear programming(MINLP)is conventionally used to deal with piecewise pipeline friction coefficients in gas network parts,but it is both complex and ***,we develop a piecewise linear function-based fitting method that can reduce the number of integer variables and enhanced the computational *** the electric network part,if the reactive power of the PV bus violates limits,it will be converted into a PQ bus,which is a non-differentiable and non-smooth *** complementarity problems are conventionally introduced to represent the PV-PQ buses type switching relationship and are addressed by the Newton-Raphson(NR)***,the above method is sensitive to the initial ***,we introduce a robust projected Levenberg-Marquardt(PLM)algorithm to cope with this *** demonstrate the advantages of our method and validate it both in a small-scale system and largescale network test cases.

关键词： Complementarity constraints integrated energy system non-smooth constraints piecewise linear function-based fitting method

Parallel-Dynamic Interpolation Algorithm of Sea Surface Height for Future 2D Altimetry Mapping of Sea Surface Height

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Journal of Ocean University of China 2021年第5期20卷 1121-1135页

作者： DI jiankai MA Chunyong CHEN Ge College of Information Science and Engineering Ocean University of ChinaQingdao 266100China Laboratory for Regional Oceanography and Numerical Modeling Laboratory for Ocean Dynamics and ClimateQingdao National Laboratory for Marine Science and TechnologyQingdao 266237China

The sea surface height data volume of the future wide-swath two-dimensional(2D)altimetric satellite is thousands of times greater than that of nadir altimetric *** time complexity of the 2D altimetry mapping reaches O(n^(3)).It is challenging to map the global grid products of future 2D altimetric *** this study,to improve the efficiency of global data mapping,a new algorithm called parallel-dynamic interpolation(PA-DI)was *** the use of 2D data segmentation and fine-grained data mosaic methods,the parallel along-track DI processes were accelerated,and a fast and efficient spatial-temporal high-resolution and low-error enhanced mapping method was *** determined from a comparison of the single-threaded DI with the PA-DI,the new algorithm optimized the time complexity from O(n^(3))to O(n^(3)/KL),which improved the mapping efficiency and achieved the expected *** to the test results of the observing system simulation experiments,the PA-DI algorithm may provide an efficient and reliable method for future wide-swath 2D altimetric satellite mapping.

关键词： parallel computation data segmentation data mosaic dynamic interpolation wide-swath 2D altimetric satellite

Analyzing electrostatic modulation of signal transduction efficiency in MoS2 nanoelectromechanical resonators with interferometric readout

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Science China(Information Sciences) 2022年第2期65卷 218-224页

作者： jiankai ZHU Pengcheng ZHANG Rui YANG Zenghui WANG Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China University of Michigan-Shanghai Jiao Tong University Joint Institute Shanghai Jiao Tong University

Optical interferometry is a highly sensitive method for detecting the miniscule resonant motion in two-dimensional(2D) nanoelectromechanical systems(NEMS). However, the technique to control the interferometry signal strength has not been fully understood. In this work, we present analytical modeling of an effective method for tuning motion-to-signal responsivity in interferometric detection of 2D molybdenum disulfide(MoS) NEMS resonators. We show that the responsivity can be tuned very efficiently, all the way from maximum to 0, by varying the vacuum gap underneath the 2D membrane electrostatically. We further show that the gate voltage corresponding to 0 responsivity, which means no motion signal can be detected,varies with the MoSthickness, diameter, pre-strain, and initial vacuum gap. Our findings provide an important guideline for optimizing measurement conditions when detecting motion in 2D NEMS structures using laser interferometry.

关键词： MoS2 2D NEMS resonators laser interferometry responsivity

Zoning strategy of zonal modeling for thermally stratified large spaces

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Building Simulation 2021年第5期14卷 1395-1406页

作者： Yanyu Lu Zhaojun Wang Jing Liu jiankai Dong School of Architecture Harbin Institute of TechnologyHarbinHeilongjiang ProvinceChina Key Laboratory of Cold Region Urban and Rural Human Settlement Environment Science and Technology Ministry of Industry and Information TechnologyHarbinHeilongjiang ProvinceChina

Large space buildings play a significant role in modern society because of their environmental advantages and market *** the zonal model is promising for the efficient and rapid evaluation of the stratified thermal environment,there is a lack of a reasonable and convenient zoning strategy with the advent of modern *** paper presents a universal and practical zonal model,in which a simplified momentum equation is applied to consider air momentum preservation,transformation,and ***,the zoning structure is generalized and ***,limiting the dimensionless temperature constraint between adjacent zones establishes the connection between thermal nonuniformity and zoning results ***,the dimension and number of zones should be restricted within reasonable ranges to satisfy the characteristics of zonal simulation and reach the criteria of *** further explore and validate the zonal model,a reduced-scale experimental model was constructed to replicate the thermal stratification in a mechanically ventilated large space by considering many crucial realistic factors.A particle image velocimetry(PIV)measurement was then conducted to visualize the airflow pattern and support the partition of *** results showed that the zonal simulation with adaptive zoning method can realize a similar accuracy with fewer zones and exhibit a better tolerance for zoning results compared to the conventional empirical zoning ***,a case study of an atrium was performed to demonstrate the practicality and efficiency of the method for long-term dynamic simulations of complex thermal environments and building energy use.

关键词： zoning method zonal simulation temperature gradient large space PIV

Attribution of Biases of Interhemispheric Temperature Contrast in CMIP6 Models

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Advances in Atmospheric Sciences 2024年第2期41卷 325-340页

作者： Shiyan ZHANG Yongyun HU jiankai ZHANG Yan XIA Laboratory for Climate and Ocean-Atmosphere Studies Department of Atmospheric and Oceanic SciencesSchool of PhysicsPeking UniversityBeijing 100871China College of Atmospheric Sciences Lanzhou UniversityLanzhou 730000China School of Systems Science Beijing Normal UniversityBeijing 100875China

One of the basic characteristics of Earth's modern climate is that the Northern Hemisphere(NH) is climatologically warmer than the Southern Hemisphere(SH). Here, model performances of this basic state are examined using simulation results from 26 CMIP6 models. Results show that the CMIP6 models underestimate the contrast in interhemispheric surface temperatures on average(0.8 K for CMIP6 mean versus 1.4 K for reanalysis data mean), and that there is a large intermodel spread, ranging from -0.7 K to 2.3 K. A box model energy budget analysis shows that the contrast in interhemispheric shortwave absorption at the top of the atmosphere, the contrast in interhemispheric greenhouse trapping, and the crossequatorial northward ocean heat transport, are all underestimated in the multimodel mean. By examining the intermodel spread, we find intermodel biases can be tracked back to biases in midlatitude shortwave cloud forcing in AGCMs. Models with a weaker interhemispheric temperature contrast underestimate the shortwave cloud reflection in the SH but overestimate the shortwave cloud reflection in the NH, which are respectively due to underestimation of the cloud fraction over the SH extratropical ocean and overestimation of the cloud liquid water content over the NH extratropical *** that underestimate the interhemispheric temperature contrast exhibit larger double ITCZ biases, characterized by excessive precipitation in the SH tropics. Although this intermodel spread does not account for the multimodel ensemble mean biases, it highlights that improving cloud simulation in AGCMs is essential for simulating the climate realistically in coupled models.

关键词： interhemispheric temperature contrast energy balance shortwave cloud forcing ITCZ CMIP6 AGCM

Record Arctic Ozone Loss in Spring 2020 is Likely Caused by North Pacific Warm Sea Surface Temperature Anomalies

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Advances in Atmospheric Sciences 2021年第10期38卷 1723-1736页

作者： Yan XIA Yongyun HU jiankai ZHANG Fei XIE Wenshou TIAN College of Global Change and Earth System Science Beijing Normal UniversityBeijing 100875China Key Laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Laboratory for Climate and Ocean-Atmosphere Studies Department of Atmospheric and Oceanic SciencesSchool of PhysicsPeking UniversityBeijing 100871China College of Atmospheric Sciences Lanzhou UniversityLanzhou 730000China

Record ozone loss was observed in the Arctic stratosphere in spring *** study aims to determine what caused the extreme Arctic ozone *** and simulation results are examined in order to show that the extreme Arctic ozone loss was likely caused by record-high sea surface temperatures(SSTs)in the North *** is found that the record Arctic ozone loss was associated with the extremely cold and persistent stratospheric polar vortex over February-April,and the extremely cold vortex was a result of anomalously weak planetary wave *** analysis reveals that the weak wave activity can be traced to anomalously warm SSTs in the North *** observations and simulations show that warm SST anomalies in the North Pacific could have caused the weakening of wavenumber-1 wave activity,colder Arctic vortex,and lower Arctic *** results suggest that for the present-day level of ozone-depleting substances,severe Arctic ozone loss could form again,as long as certain dynamic conditions are satisfied.

关键词： Arctic ozone loss stratospheric polar vortex sea surface temperature planetary-scale wave climate change

A Bi-population Cooperative Optimization Algorithm Assisted by an Autoencoder for Medium-scale Expensive Problems

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IEEE/CAA Journal of Automatica Sinica 2022年第11期9卷 1952-1966页

作者： Meiji Cui Li Li MengChu Zhou jiankai Li Abdullah Abusorrah Khaled Sedraoui IEEE the School of Intelligent Manufacturing Nanjing University of Science and TechnologyNanjing 210094China the Department of Electronics and Information Engineering Tongji UniversityShanghai 201804China the Helen and John C.Hartmann Department of Electrical and Computer Engineering New Jersey Institute of TechnologyNewarkNJ 07102 USA Center of Research Excellence in Renewable Energy and Power Systems Department of Electrical and Computer EngineeringFaculty of Engineeringand K.A.CARE Energy Research and Innovation CenterKing Abdulaziz UniversityJeddah 21589Saudi Arabia

This study presents an autoencoder-embedded optimization(AEO)algorithm which involves a bi-population cooperative strategy for medium-scale expensive problems(MEPs).A huge search space can be compressed to an informative lowdimensional space by using an autoencoder as a dimension reduction *** search operation conducted in this low space facilitates the population with fast convergence towards the *** strike the balance between exploration and exploitation during optimization,two phases of a tailored teaching-learning-based optimization(TTLBO)are adopted to coevolve solutions in a distributed fashion,wherein one is assisted by an autoencoder and the other undergoes a regular evolutionary ***,a dynamic size adjustment scheme according to problem dimension and evolutionary progress is proposed to promote information exchange between these two phases and accelerate evolutionary convergence *** proposed algorithm is validated by testing benchmark functions with dimensions varying from 50 to *** indicated in our experiments,TTLBO is suitable for dealing with medium-scale problems and thus incorporated into the AEO framework as a base *** with the state-of-the-art algorithms for MEPs,AEO shows extraordinarily high efficiency for these challenging problems,t hus opening new directions for various evolutionary algorithms under AEO to tackle MEPs and greatly advancing the field of medium-scale computationally expensive optimization.

关键词： Autoencoder dimension reduction evolutionary algorithm medium-scale expensive problems teaching-learning-based optimization

ON THE HEAT FLOW OF EQUATION OF H-SURFACE

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Acta Mathematica Scientia 2019年第5期39卷 1397-1405页

作者： Guochun WU Zhong TAN jiankai XU Fujian Province University Key Laboratory of Computational Science School of Mathematical Sciences Huaqiao University Quanzhou 362021 China School of Mathematical Sciences and Fujian Provincial Key Laboratory on Mathematical Modeling and Scientific Computing Xiamen University Xiamen 361005 China College of Information Science and Technology Hunan Agriculture University Changsha 410128 China

We study the heat flow of equation of H-surface with non-zero Dirichlet boundary in the present article. Introducing the "stable set" M2 and "unstable set" M1, we show that there exists a unique global solution provided the initial data belong to M2 and the global solution converges to zero in H^1 exponentially as time goes to infinity. Moreover, we also prove that the local regular solution must blow up at finite time provided the initial data belong to M1.

关键词： H-surface non-zero Dirichlet boundary singularity global solutions