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Iterative Methods for Solving the Nonlinear Balance Equation with Optimal Truncation

Advances in Atmospheric Sciences 2021年第5期38卷 755-770页

作者： Qin XU Jie CAO NOAA/National Severe Storms Laboratory NormanOklahoma 73069USA Cooperative Institute for Mesoscale Meteorological Studies University of OklahomaNormanOklahoma 73072USA Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China

Two types of existing iterative methods for solving the nonlinear balance equation(NBE)are revisited.In the first type,the NBE is rearranged into a linearized equation for a presumably small correction to the initial guess or the subsequent updated solution.In the second type,the NBE is rearranged into a quadratic form of the absolute vorticity with the positive root of this quadratic form used in the form of a Poisson equation to solve NBE iteratively.The two methods are rederived by expanding the solution asymptotically upon a small Rossby number,and a criterion for optimally truncating the asymptotic expansion is proposed to obtain the super-asymptotic approximation of the solution.For each rederived method,two iterative procedures are designed using the integral-form Poisson solver versus the over-relaxation scheme to solve the boundary value problem in each iteration.Upon testing with analytically formulated wavering jet flows on the synoptic,sub-synoptic and meso-αscales,the iterative procedure designed for the first method with the Poisson solver,named M1a,is found to be the most accurate and efficient.For the synoptic wavering jet flow in which the NBE is entirely elliptic,M1a is extremely accurate.For the sub-synoptic wavering jet flow in which the NBE is mostly elliptic,M1a is sufficiently accurate.For the meso-αwavering jet flow in which the NBE is partially hyperbolic so its boundary value problem becomes seriously ill-posed,M1a can effectively reduce the solution error for the cyclonically curved part of the wavering jet flow,but not for the anti-cyclonically curved part.

关键词： nonlinear balance iterative method optimal truncation

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A New Diagnosis Method with Few-shot Learning Based on a Class-rebalance Strategy for Scarce Faults in Industrial Processes

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Machine Intelligence Research 2023年第4期20卷 583-594页

作者： Xinyao xu De xu Fangbo qin Research Center of Precision Sensing and Control Institute of AutomationChinese Academy of SciencesBeijing100190China School of Artificial Intelligence University of Chinese Academy of SciencesBeijing100049China

For industrial processes, new scarce faults are usually judged by experts. The lack of instances for these faults causes a severe data imbalance problem for a diagnosis model and leads to low performance. In this article, a new diagnosis method with few-shot learning based on a class-rebalance strategy is proposed to handle the problem. The proposed method is designed to transform instances of the different faults into a feature embedding space. In this way, the fault features can be transformed into separate feature clusters. The fault representations are calculated as the centers of feature clusters. The representations of new faults can also be effectively calculated with few support instances. Therefore, fault diagnosis can be achieved by estimating feature similarity between instances and faults. A cluster loss function is designed to enhance the feature clustering performance. Also, a class-rebalance strategy with data augmentation is designed to imitate potential faults with different reasons and degrees of severity to improve the model’s generalizability. It improves the diagnosis performance of the proposed method. Simulations of fault diagnosis with the proposed method were performed on the Tennessee-Eastman benchmark. The proposed method achieved average diagnosis accuracies ranging from 81.8% to 94.7% for the eight selected faults for the simulation settings of support instances ranging from 3 to 50. The simulation results verify the effectiveness of the proposed method.

关键词： Data augmentation feature clustering class-rebalance strategy few-shot learning fault diagnosis

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Hybrid Methods for Computing the Streamfunction and Velocity Potential for Complex Flow Fields over Mesoscale Domains

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Advances in Atmospheric Sciences 2022年第9期39卷 1417-1431页

作者： Jie CAO Qin XU Haishan CHEN Shuping MA Key Laboratory of Meteorological Disaster(KLME) Ministry of Education&Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science&TechnologyNanjing 210044China Cooperative Institute for Mesoscale Meteorological Studies(CIMMS) University of OklahomaNorman 73072OklahomaUSA NOAA/OAR/National Severe Storms Laboratory Norman 73069OklahomaUSA Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China

Three types of previously used numerical methods are revisited for computing the streamfunctionψand velocity potentialχfrom the horizontal velocity v in limited domains.The first type,called the SOR-based method,uses a classical successive over-relaxation(SOR)scheme to computeψ(orχ)first with an arbitrary boundary condition(BC)and thenχ(orψ)with the BC derived from v.The second type,called the spectral method,uses spectral formulations to construct the inner part of(ψ,χ)-the inversion of(vorticity,divergence)with a homogeneous BC,and then the remaining harmonic part of(ψ,χ)with BCs from v.The third type,called the integral method,uses integral formulas to compute the internally induced(ψ,χ)-the inversion of domain-internal(vorticity,divergence)using the free-space Greenꞌs function without BCs and then the remaining harmonicψ(orχ)with BCs from v minus the internally-induced part.Although these methods have previously been successfully applied to flows in large-scale and synoptic-scale domains,their accuracy is compromised when applied to complex flows over mesoscale domains,as shown in this paper.To resolve this problem,two hybrid approaches,the integral-SOR method and the integral-spectral method,are developed by combining the first step of the integral method with the second step adopted from the SOR-based and spectral methods,respectively.Upon testing these methods on real-case complex flows,the integral-SOR method is significantly more accurate than the integral-spectral method,noting that the latter is still generally more accurate than the three previously-used methods.The integral-SOR method is recommended for future applications and diagnostic studies of complex flows.

关键词： streamfunction and velocity potential complex flow fields successive over-relaxation method mesoscale study

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GUIDE FOR AUTHORS

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Earthquake Research Advances 2023年第3期3卷 86-92页

作者： Qin XU Ningning Zheng 不详

INTRODUCTION Types of paper Contributions falling into the following categories will be considered for publication:Original research papers,reviews and short communications.Please ensure that you select the appropriate article type from the list of options when making your submission.Authors contributing to special issues should ensure that they select the special issue article type from this list.BEFORE YOU BEGIN Ethics in publishing For information on Ethics in Publishing and Ethical guidelines for journal publication see http://***/publishingethics and http://***/ethicalguidelines.

关键词： journal publishing http

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GUIDE FOR AUTHORS

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Earthquake Research Advances 2021年第2期1卷 60-66页

作者： Qin XU

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Partial Topology Identification of Stochastic Multi-Weighted Complex Networks Based on Graph-Theoretic Method and Adaptive Synchronization

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Advances in Applied Mathematics and Mechanics 2023年第6期15卷 1428-1455页

作者： Huiling Chen Chunmei Zhang Yuli Feng Qin XU School of Mathematics Southwest Jiaotong UniversityChengduSichuan 610031China

This article aims to identify the partial topological structures of delayed complex network.Based on the drive-response concept,a more universal model,which includes nonlinear couplings,stochastic perturbations and multi-weights,is considered into drive-response networks.Different from previous methods,we obtain identification criteria by combining graph-theoretic method and adaptive synchronization.After that,the partial topological structures of stochastic multi-weighted complex networks with or without time delays can be identified successfully.Moreover,response network can reach synchronization with drive network.Ultimately,the effectiveness of the proposed theoretical results is validated through numerical simulations.

关键词： Partial topology identification graph-theoretic method multi-weighted complex networks adaptive pinning control nonlinear coupling

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Harmonic Amplification Analysis of Cable Lines with Distributed Parameters Based on Kalman Filter and Convolution Inversion

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Journal of Modern Power Systems and Clean Energy 2023年第6期11卷 1804-1813页

作者： Yang Pu qin Shu Fangwei xu College of Electrical Engineering Sichuan UniversityChengdu 610065China IEEE

Harmonic amplification phenomena could appear at the point of common connection(PCC) of the cable line terminal. However, the distributed parameter model of the cable line contains hyperbolic functions with plural variables, which makes it challenging to obtain the harmonic amplification factor(HAF). Hence, a time-domain method combining the Kalman filter and convolution inversion(KFCI) methods is proposed to address this problem. First, the Kalman filter method optimizes the square wave pulse response(SWPR) with measurement error. Then, the optimized SWPR data are used to get the HAF by the convolution inversion method. Next, the harmonic amplification characteristics of cable lines are explored. Finally, an experimental simulation model is built on the PSCAD software, verifying the optimization effectiveness of Kalman filter for the SWPR with error and the accuracy of the HAF calculated by the proposed method. The analysis rationality of harmonic amplification properties is also demonstrated.

关键词： Cable line distributed parameter Kalman filter convolution inversion harmonic amplification

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Lighting up rotaxanes with AIEgens

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Chinese Chemical Letters 2023年第3期34卷 122-133页

作者： Xiao-Qin XU xu-qing Wang Wei Wang School of Chemistry and Molecular Engineering East China Normal UniversityShanghai 200062China Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices South China University of TechnologyGuangzhou 510640China

Aiming at the construction of novel rotaxanes with desired luminescent properties for practical applications, recently the rapid development of rotaxanes decorated with aggregation-induced emission(AIE) luminogens(i.e., AIEgens) has been witnessed. The combination of AIEgens and rotaxanes leads to the successful construction of a novel type of luminescent rotaxanes with many attractive features. In particular, the unique controllable dynamic feature of rotaxanes endows the resultant AIEgen-based rotaxanes precisely tunable emissions under external stimuli, leading to the construction of a novel type of smart luminescent materials. In this minireview, the recent progress of AIEgen-based rotaxanes has been summarized, with an emphasis on the design strategy and potential applications.

关键词： Mechanically interlocked molecules Aggregation-induced emission Molecular shuttles F?rster resonance energy transfer Light harvesting Aggregate

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Enhanced thermal conductivity and microwave dielectric properties by mesostructural design of multiphase nanocomposite

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Nano Materials Science 2022年第2期4卷 133-138页

作者： Liping Zhou Peng xu Faxiang qin Institute for Composites Science Innovation(InCSI) School of Materials Science and EngineeringZhejiang University38 Zheda RoadHangzhou310027PR China

Next-generation packaging materials are expected to have higher thermal conductivity,because the heat accumulated in high-performance electronic equipment should be removed to increase the service life of the equipment.At the same time,the dielectric loss of the material needs to be reduced to lessen signal delay and attenuation,especially for the applications under high frequency.In this work,we introduce nano-silicon carbide(SiC)and carbon nanotubes(CNTs)into the polystyrene(PS)and poly(methyl methacrylate)(PMMA)blends system.The design of two-way migration at the interface of CNTs and SiC nanoparticles is realized through the masterbatch method and processing technology control.As a result,the thermal conductivity is successfully increased up to 75%.Meanwhile,compared to the CNTs single-phase migration system,it effectively reduces the dielectric loss of the nanocomposite and optimizes the electrical insulation.This work has significant practical application value in the design of electronic device substrates and packaging materials,and provides an innovative methodology for the mesostructure design of multiphase nanocomposites.

关键词： Immiscible blends Nanocomposite Microwave dielectric properties Thermal conductivity

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Covalent organic frameworks functionalized carbon fiber paper for the capture and detection of hydroxyl radical in the atmosphere

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中国化学快报：英文版 2020年第9期31卷 2495-2498页

作者： Zhiling Huang Qin XU Xiaoya Hu School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China Guangling College Yangzhou UniversityYangzhou 225002China

Developing a fast,sensitive and convenient method for the detection of hydroxyl radicals(·OH) in the atmosphere could help us know the precursor levels of atmospheric species and control air pollution.In this work,the carbon fiber paper(CFP) functionalizing with a kind of covalent organic frameworks(COFs),formed from 1,3,5-triformylphloroglucinol(Tp) and benzidine(BD)(COF(TpBD)),was firstly used a new platform for ·OH trapping and detection.The COF(TpBD) modified CFP was acted as a filter to impregnate salicylic acid(SA) and a detector to detect 2,5-dihydroxybenzoic acid(2,5-DHBA) which was produced from the reaction between the impregnated SA and ’OH in the atmosphere.This method provided a linearity for 2,5-DHBA from 5.0×10^-14 mol/L 1.0×10^-9 mol/L with a detection limit of 6.9×10^-15 mol/L,which is corresponding to the amount of ·OH from 3.0×10^7 to 6.0×10^11 molecules/cm3 with the detection limit of 4.1×10^6 molecules/cm3.This COF(TpBD)-CFP platform has been successfully applied for the detection of ·OH concentration under different conditions of Yangzhou when the sampling time was shortened to 30 min.This work has provided a new method for atmospheric·OH detection with excellent sensitivity,simplicity,and high speed.

关键词： Covalent organic frameworks Hydroxyl radical Electrochemical Detection

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