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A New Type of Fuzzy Membership Function Designed for Interval Type-2 Fuzzy Neural Network

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自动化学报 2017年第8期43卷 1425-1433页

作者： Jiajun Wang School of Automation Hangzhou Dianzi University Hangzhou 310018 China

A new type of fuzzy membership function (FMF) is proposed for interval type-2 fuzzy neural network (IT2FNN) in this paper. Three types of interval type-2 FMF (IT2FMF) can be derived from the proposed type of FMF. And each type of IT2FMF has different shape of footprint of uncertainty (FOU). The derived IT2FMFs are applied to a simplified T2FNN to identify two nonlinear systems. The identification performance of the derived IT2FMFs are compared with Gaussian and ellipsoidal type of IT2FMFs through simulation. Simulation results certify that the derived IT2FMFs can achieve better identification performance than Gaussian and ellipsoidal type of IT2FMFs with elaborately tuning of the parameters for the simplified IT2FNN.

关键词：模糊隶属函数模糊神经网络区间设计识别性能非线性系统不确定性调整参数

Parameter Optimization of Interval Type-2 Fuzzy Neural Networks Based on PSO and BBBC Methods

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IEEE/CAA Journal of Automatica Sinica 2019年第1期6卷 247-257页

作者： Jiajun Wang Tufan Kumbasar the School of Automation Hangzhou Dianzi University IEEE the Control and Automation Engineering Department Faculty of Electrical and Electronics EngineeringIstanbul Technical University

Interval type-2 fuzzy neural networks(IT2FNNs)can be seen as the hybridization of interval type-2 fuzzy systems(IT2FSs) and neural networks(NNs). Thus, they naturally inherit the merits of both IT2 FSs and NNs. Although IT2 FNNs have more advantages in processing uncertain, incomplete, or imprecise information compared to their type-1 counterparts, a large number of parameters need to be tuned in the IT2 FNNs,which increases the difficulties of their design. In this paper,big bang-big crunch(BBBC) optimization and particle swarm optimization(PSO) are applied in the parameter optimization for Takagi-Sugeno-Kang(TSK) type IT2 FNNs. The employment of the BBBC and PSO strategies can eliminate the need of backpropagation computation. The computing problem is converted to a simple feed-forward IT2 FNNs learning. The adoption of the BBBC or the PSO will not only simplify the design of the IT2 FNNs, but will also increase identification accuracy when compared with present methods. The proposed optimization based strategies are tested with three types of interval type-2 fuzzy membership functions(IT2FMFs) and deployed on three typical identification models. Simulation results certify the effectiveness of the proposed parameter optimization methods for the IT2 FNNs.

关键词： Big bang-big crunch (BBBC) interval type-2 fuzzy neural networks (IT2FNNs) parameter optimization particle swarm optimization (PSO)

Fundamentals,preparation,and mechanism understanding of Li/Na/Mg-Sn alloy anodes for liquid and solid-state lithium batteries and beyond

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Nano Research 2023年第6期16卷 8191-8218页

作者： Amardeep Amardeep Donald JFreschi Jiajun Wang Jian Liu School of Engineering Faculty of Applied Sciencethe University of British ColumbiaKelownaBC V1V 1V7Canada Fenix Advanced Materials Trail BCV1R 2T3Canada MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage School of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150001China

Lithium metal is one of the most promising anodes to develop high energy density and safe energy storage devices due to its highest theoretical capacity(3860 mAh·g^(−1))and lowest electrochemical potential,demonstrating great potential to fulfill unprecedented demand from electronic gadgets,electric vehicles,and grid storage.Despite these good merits,lithium metal suffers from low Coulombic efficiency and dendritic growth,leading to internal short-circuiting of the cell and raising safety concerns about employing lithium metal as an anode.Recently,lithium-tin(Li-Sn)alloys,among other lithium alloys,have emerged as a potential alternative to lithium metal to efficiently suppress the lithium dendrite formation and reduce interfacial resistance for safer and longer-lasting lithium batteries.Accordingly,this work first reviews the fundamentals of Li-Sn alloys,and critically analyzes the failure mechanisms of pristine Li-metal anode and how Li-Sn alloys could overcome those challenges.The subsequent section examines various strategies to synthesize Li-Sn bulk and protection film alloys,followed by an evaluation of symmetric cell performance.Furthermore,the comparative electrochemical performance of full cells against different cathodes and solid electrolytes provides an overview of the present research.Subsequently,advanced characterization techniques were discussed to visualize lithium dendrites directly and quantify the mechanical performance of Li-Sn alloys.Last but not the least,the state-of-the-art progress of applying M-Sn(M=Na and Mg)beyond lithium batteries was summarized.In closing,this work identifies the critical challenges and provides future perspectives on Li-Sn alloy for lithium batteries and beyond.

关键词： Li-Sn alloys fundamental studies dendrite-free anodes liquid/solid-state batteries Li-Sn alloys synthesis approachescum-electrochemical performance lithium batteries and beyond

A novel CRISPR/Cas9 system for efficiently generating Cas9- free multiplex mutants in Arabidopsis

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aBIOTECH 2020年第1期1卷 6-14页

作者： Jiajun Wang Haodong Chen State Key Laboratory of Protein and Plant Gene Research School of Advanced Agricultural Sciences and School of Life SciencesPeking-Tsinghua Center for Life SciencesPeking UniversityBeijing 100871China

The CRISPR/Cas9 genome-editing system has emerged as a popular powerful tool for biological research.However,the process of selecting efficiently edited Cas9-free plants is usually laborious and time consuming.Here,we demonstrated P2A to be the most efficient self-cleaving peptide for fusing Cas9 and GFP in Arabidopsis and then used Cas9-P2A-GFP to develop a novel CRISPR/Cas9 system.Additionally,a pair of isocaudomer restriction enzymes were selected to conveniently assemble multiple sgRNAs.In this system,the GFP fluorescence intensity in T1 transgenic plants indicates the expression level of the Cas9 protein,which correlates well with the editing efficiency.Furthermore,Cas9-free plants can be easily selected by examining GFP fluorescence in T2 transgenic plants.The efficient knockout of BRI1,BZR1 and BES1 demonstrated the robustness of our new system.Thus,we designed a novel CRISPR/Cas9 system that can generate Cas9-free multiplex mutants efficiently in Arabidopsis and possibly in other plant species.

关键词： CRISPR Cas9 Cas9-free P2A Multiplex mutant Arabidopsis

High-efficiency nonlocal reflection-type vortex beam generation based on bound states in the continuum

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National Science Review 2023年第5期10卷 201-207页

作者： Tongyu Li Jiajun Wang Wenjie Zhang Xinhao wang Wenzhe Liu Lei Shi Jian Zi State Key Laboratory of Surface Physics Key Laboratory of Micro-and Nano-Photonic Structures (Ministry of Education) and Department of PhysicsFudan University Department of Physics The Hong Kong University of Science and Technology

Momentum-space polarization vortices centered at symmetry-protected bound states in the continuum of a periodic structure,e.***.photonic crystal slab,provide a novel nonlocal approach to generate vortex beams.This approach enjoys a great convenience of no precise alignment requirements,although the generation efficiency of the nonlocal generators requires further optimization before the practical application.In this work,we propose a temporal-coupled-mode-theory-based guideline for high-efficiency nonlocal reflection-type vortex generator design.The conversion efficiency of the vortex beam is found to be limited by the ratio of the radiative loss to the intrinsic absorption in practical systems.To increase this ratio through mode selection and structure design,the photonic crystal slabs are theoretically designed and experimentally characterized,showing a maximum on-resonance conversion efficiency of up to 86%.Combining high efficiency with simple fabrication and no re quirement for precise alignment,reflection-type photonic crystal slabs could offer a new and competitive way to generate vortex beams flexibly.

关键词： photonic crystal slab vortex beam bound states in the continuum

Experimental investigation on degradation mechanism of membrane electrode assembly at different humidity under automotive protocol

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Chinese Journal of Chemical Engineering 2023年第4期56卷 70-79页

作者： Jiajun Wang Wenbin Yang Jiangtao Geng Zhigang Shao Wei Song Fuel Cell System and Engineering Laboratory Key Laboratory of Fuel Cells and Hybrid Power SourcesDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100039China

Humidity can affect the attenuation of MEA(membrane electrode assembly), however, the relationship between humidity and MEA decays is complex and ambiguous in realistic application. Herein, we design a simulating automotive protocol, performed on five single fuel cells under RH(relative humidity) 100%,RH 80%, RH 64%, and RH 40%, RH 10%, respectively, to study the relationship of MEA decays and humidity and suggest optimized humidity range to extend the durability. With the electrochemical impedance spectroscopy, cyclic voltammetry, X-ray fluorescence, X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, the four degradation mechanisms about catalyst layer, including Pt dissolution, Pt coarsening, carbon corrosion and ionomer degradation, are observed. Pt coarsening and carbon corrosion are accelerated by higher water content at high humidity. Ionomer degradation and Pt dissolution are enhanced in low humidity. With the linear sweep voltammetry, ion chromatography,nuclear magnetic resonance, tensile test and scan electron microscope, chemical and mechanical degradation in proton exchange membrane are all observed in these five fuels. Chemical degradation, characterized by membrane thinning and more fluoride loss, occurred markedly in RH 10%. Mechanical degradation, characterized by the non-uniformity thickness and bad mechanical properties, is more pronounced in RH 100%, RH 80%, RH 64%. These two degradations are in a moderate level in RH 40%. The research suggests that the RH range from 64% to 40% is conductive to mitigate the degradation of MEAs operated in automotive applications.

关键词： Fuel cell Simulating automotive protocol Relative humidity Degradation Membrane

Visible light-driven oxidant-free dehydrogenation of alcohols in water using porous ultrathin g-C_(3)N_(4)nanosheets

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Green Energy & Environment 2022年第4期7卷 712-722页

作者： Wei Zhang Jiajun Wang Zewei Liu Yibing Pi Rong Tan National&Local Joint Engineering Laboratory for New Petro-chemical Materials and Fine Utilization of Resources Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research(Ministry of Education)College of Chemistry and Chemical EngineeringHunan Normal UniversityChangsha410081China

Graphitic carbon nitride(g-C_(3)N_(4)) is a fascinating photocatalyst for solar energy utilization in photo-catalysis.Nevertheless,it often suffers from moderate photo-catalytic activity due to its low specific surface area and fast recombination rate of photogenerated electrons upon photo-excitation.Herein,we overcome the bottlenecks by constructing a porous g-C_(3)N_(4) nanosheet(PCNS)through a simple thermal oxidation etching method.Benefited from its porous layer structure,the obtained PCNS exhibits large specific surface area,efficient separation of photogenerated charge carriers,as well as high exposure of active sites.As a result,it is robust and universal in visible light-driven dehydrogenation of alcohols in water under oxidant-free condition.Almost quantitative yields(>99%)of various valuable carbonyl compounds were obtained over PCNS,while bulk g-C_(3)N_(4) was far less efficient.Moreover,the photo-catalyst was highly stable and could be facilely recovered from the aqueous system for efficient reuse.The easy preparation and excellent performance made PCNS a promising and competitive photocatalyst for the solar applications.

关键词： Photo-catalysis Porous g-C_(3)N_(4)nanosheets Visible light irradiation Oxidant-free dehydrogenation Alcohols

Selective electrocatalytic reduction of CO_(2) to formate via carbon-shell-encapsulated In_(2)O_(3) nanoparticles/graphene nanohybrids

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Journal of Materials Science & Technology 2022年第26期121卷 220-226页

作者： Yidu wang Jingnan Ding Jun Zhao Jiajun Wang Xiaopeng Han Yida Deng Wenbin Hu Key Laboratory of Advanced Ceramics and Machining Technology(Ministry of Education) Tianjin Key Laboratory of Composite and Functional MaterialsSchool of Materials Science and EngineeringTianjin UniversityTianjin 300072China State Key Laboratory of Marine Resource Utilization in South China Sea School of Materials Science and EngineeringHainan UniversityHaikou 570228China Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityFuzhouBinhai New City 350207China

Constructing nanohybrids with a synergistic effect using multi-components and specific micro/nanostructures can significantly enhance their electrocatalytic activity.In this work,we fabricated an In_(2)O_(3)■NC@GO nanohybrid,in which In_(2)O_(3)nanoparticles(NPs)were encapsulated by an N-doped carbon(NC)shell and supported on graphene.The multi-components in In_(2)O_(3)■NC@GO synergistically optimize the structural and electronic properties of the material.The particle size and dispersion of In_(2)O_(3)NPs were optimized owing to the separation effect of the amorphous NC shell and graphene support.This separation effect exposes more number of active sites for the electrochemical reaction.Abundant oxygen vacancies exist in In_(2)O_(3),leading to a stronger ability for the adsorption and activation of CO.The NC shell inhibits the direct contact between the electrolyte and In_(2)O_(3),which significantly suppresses competitive Hevolution.The charge transfer during the electrocatalysis process is also effectively enhanced due to the carbon components.The synergistic effect of multi-components in the In_(2)O_(3)■NC@GO sample results in a significantly improved COreduction reaction performance with a high HCOOFaradic efficiency(FE)of 91.2%and a current density of 40.38 m A cmat–0.8 V obtained using a flow cell.The present work demonstrates that rationally designing nanohybrids with multifunctional components is an effective strategy for optimizing the structural and electrocatalytic properties of materials for energy conversion.

关键词： In_(2)O_(3) CO_(2)reduction electrocatalyst Oxygen vacancies N-doped carbon Nanohybrids

Perception Enhanced Deep Deterministic Policy Gradient for Autonomous Driving in Complex Scenarios

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 557-576页

作者： Lyuchao Liao Hankun Xiao Pengqi Xing Zhenhua Gan Youpeng He Jiajun Wang Fujian Provincial Key Laboratory of Automotive Electronics and Electric Drive Fujian University of TechnologyFuzhou350118China Fujian Provincial Universities Engineering Research Center for Intelligent Driving Technology Fuzhou350118China

Autonomous driving has witnessed rapid advancement;however,ensuring safe and efficient driving in intricate scenarios remains a critical challenge.In particular,traffic roundabouts bring a set of challenges to autonomous driving due to the unpredictable entry and exit of vehicles,susceptibility to traffic flow bottlenecks,and imperfect data in perceiving environmental information,rendering them a vital issue in the practical application of autonomous driving.To address the traffic challenges,this work focused on complex roundabouts with multi-lane and proposed a Perception EnhancedDeepDeterministic Policy Gradient(PE-DDPG)for AutonomousDriving in the Roundabouts.Specifically,themodel incorporates an enhanced variational autoencoder featuring an integrated spatial attention mechanism alongside the Deep Deterministic Policy Gradient framework,enhancing the vehicle’s capability to comprehend complex roundabout environments and make decisions.Furthermore,the PE-DDPG model combines a dynamic path optimization strategy for roundabout scenarios,effectively mitigating traffic bottlenecks and augmenting throughput efficiency.Extensive experiments were conducted with the collaborative simulation platform of CARLA and SUMO,and the experimental results show that the proposed PE-DDPG outperforms the baseline methods in terms of the convergence capacity of the training process,the smoothness of driving and the traffic efficiency with diverse traffic flow patterns and penetration rates of autonomous vehicles(AVs).Generally,the proposed PE-DDPGmodel could be employed for autonomous driving in complex scenarios with imperfect data.

关键词： Autonomous driving traffic roundabouts deep deterministic policy gradient spatial attention mechanisms