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Acta Mathematicae Applicatae Sinica 2023年第2期39卷 337-353页

作者： Sheng Xiao Xiang-dong LIU Ying-qiu LI School of economics Jinan UniversityGuangzhou510632China School of Mathematics and Statistics Changsha University of Science and TechnologyChangsha 410004China Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering Changsha University of Science and TechnologyChangsha 410004China

Let(Z_(n))be a supercritical bisexual branching process in a random environmentξ.We study the almost sure(a.s.)convergence rate of the submartingale W_(n)=Z_(n)/In to its limit W,where(In)is an usually used norming sequence.We prove that under a moment condition of order p∈(1,2),W-W_(n)=o(e^(-na))a.***.for some a>0 that we find explicitly;assuming the logarithmic moment condition holds,we haveW-W_(n)=o(n^(-α))a.s..In order to obtain these results,we provide the L^(p)-convergence of(W_(n));similar conclusions hold for a bisexual branching process in a varying environment.

关键词： bisexual branching process convergence rate varying environment random environment

A bearing fault diagnosis method based on a convolutional spiking neural network with spa tial-tempor al fea ture-extr action capability

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Transportation Safety and Environment 2023年第2期5卷 59-70页

作者： Changfan Zhang Zunguang xiao Zhenwen sheng College of Railway Transportation Hunan University of TechnologyZhuzhou 412007HunanChina Shandong Xiehe University Jinan 250109ShandongChina

Convolutional neur al netw orks(CNNs)ar e widel y used in the field of fault diagnosis due to their strong feature-extraction capability.How ever,in eac h timeste p,CNNs onl y consider the curr ent input and ignor e any cyclicity in time,ther efor e pr oducing difficulties in mining temporal features from the data.In this w ork,the third-gener ation neur al netw ork-the spiking neur al netw ork(SNN)-is utilized in bearing fault diagnosis.SNNs incorpor ate tempor al concepts and utilize discrete spike sequences in communication,making them more biolo gically e xplanatory.Inspired by the classic CNN LeNet-5 fr amew ork,a bearing fault diagnosis method based on a convolutional SNN is proposed.In this method,the spiking convolutional network and the spiking classifier network are constructed by using the inte gr ate-and-fire(IF)and leaky-inte gr ate-and-fire(LIF)model,respectively,and end-to-end training is conducted on the overall model using a surrogate gradient method.The signals are adaptively encoded into spikes in the spiking neuron layer.In addition,the network utilizes max-pooling,which is consistent with the spatial-temporal characteristics of SNNs.Combined with the spiking con volutional la y ers,the netw ork fully extracts the spatial-temporal featur es fr om the bearing vibration signals.Experimental validations and comparisons are conducted on bearings.The results show that the proposed method achieves high accuracy and takes fewer time steps.

关键词： fault diagnosis spiking neural network(SNN) convolutional neural network(CNN) surrogate gradient method

Compiler IR-Based Program Encoding Method for Software Defect Prediction

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Computers, Materials & Continua 2022年第9期72卷 5251-5272页

作者： Yong Chen Chao Xu Jing Selena He Sheng Xiao Fanfan Shen School of Information Engineering Nanjing Audit UniversityNanjing211815China Department of Computer Science Kennesaw State UniversityKennesaw30144-5588USA Information Science and Engineering Department Hunan First Normal UniversityChangsha410205China

With the continuous expansion of software applications,people’s requirements for software quality are increasing.Software defect prediction is an important technology to improve software quality.It often encodes the software into several features and applies the machine learning method to build defect prediction classifiers,which can estimate the software areas is clean or buggy.However,the current encoding methods are mainly based on the traditional manual features or the AST of source code.Traditional manual features are difficult to reflect the deep semantics of programs,and there is a lot of noise information in AST,which affects the expression of semantic features.To overcome the above deficiencies,we combined with the Convolutional Neural Networks(CNN)and proposed a novel compiler Intermediate Representation(IR)based program encoding method for software defect prediction(CIR-CNN).Specifically,our program encoding method is based on the compiler IR,which can eliminate a large amount of noise information in the syntax structure of the source code and facilitate the acquisition of more accurate semantic information.Secondly,with the help of data flow analysis,a Data Dependency Graph(DDG)is constructed on the compiler IR,which helps to capture the deeper semantic information of the program.Finally,we use the widely used CNN model to build a software defect prediction model,which can increase the adaptive ability of the method.To evaluate the performance of the CIR-CNN,we use seven projects from PROMISE datasets to set up comparative experiments.The experiments results show that,in WPDP,with our CIR-CNN method,the prediction accuracy was improved by 12%for the AST-encoded CNN-based model and by 20.9%for the traditional features-based LR model,respectively.And in CPDP,the AST-encoded DBNbased model was improved by 9.1%and the traditional features-based TCA+model by 19.2%,respectively.

关键词： Compiler IR CNN data dependency graph defect prediction

Note on Integer 4-flows in Graphs

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Acta Mathematica Sinica,English Series 2022年第9期38卷 1653-1664页

作者： xiao WANG You LU sheng Gui ZHANG School of Mathematics and Statistics Northwestern Polytechnical UniversityXi'an 710072P.R.China College of Mathematics and Computer Application Shangluo UniversityShangluo 726000P.R.China

Let G be a bridgeless graph and C be a circuit in G.To find a shorter circuit cover of G,Fan proposed a conjecture that if G/C admits a nowhere-zero 4-flow,then G admits a 4-flow(D,f)such that E(G)E(C)?supp(f)and|supp(f)∩E(C)|>3/4|E(C)|,and showed that the conjecture holds if|E(C)|≤19[Combinatorica,37,1097–1112(2017)].In this paper,we prove that the conjecture holds if|E(C)|≤27.

关键词： Integer 4-flow modulo 4-flow circuit

Production of high-energy neutron beam from deuteron breakup

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Nuclear Science and Techniques 2022年第7期33卷 125-132页

作者： Ren-sheng Wang Li Ou Zhi-Gang xiao School of Radiation Medicine and Protection Medical College of Soochow UniversitySuzhou215123China Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions Suzhou215123China College of Physics and Technology Guangxi Key Laboratory of Nuclear Physics and TechnologyGuangxi Normal UniversityGuilin541004China Department of Physics Tsinghua UniversityBeijing100084China

The deuteron breakup on heavy targets has been investigated in the framework of an improved quantum molecular dynamics model,focusing on the production of neutrons near zero degrees.The experimental differential cross sections of neutron production in the 102 MeV d+C reactions were reproduced by simulations.Based on the consistency between the model prediction and experiment,the feasibility of producing a neutron beam through the breakup of deuteron on a carbon target was demonstrated.Because of the nucleon Fermi motion inside the deuteron,the energy spectrum of the inclusive neutron near 0°in the laboratory exhibits considerable energy broadening in the main peak,whereas the long tail on the low-energy side is suppressed.By coincidentally measuring the accompanying deuteron breakup proton,the energy of the neutron can be tagged with an intrinsic uncertainty of approximately 5%(1σ).The tagging efficiency of the accompanying proton on the forward-emitted neutron can reach 90%,which ensures that the differential cross section in the(d,np)channel remains two orders higher than that in(p,n)after considering the measurement of accompanying protons.This enables the application of a well-defined energy neutron beam in an event-by-event scheme.

关键词： Deuteron breakup Monochromatic neutron High energy Quantum molecular dynamics

Kinematics Analysis and Singularity Avoidance of a Parallel Mechanism with Kinematic Redundancy

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Chinese Journal of Mechanical Engineering 2022年第5期35卷 244-261页

作者： Chaoyu Shen Haibo Qu sheng Guo xiao Li Robotics Research Center School of MechanicalElectronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China China Waterborne Transport Research Institute Beijing 100088China Key Laboratory of Vehicle Advanced Manufacturing Measuring and Control TechnologyMinistry of EducationBeijing Jiaotong UniversityBeijing 100044China

The kinematic redundancy is considered as a way to improve the performance of the parallel mechanism.In this paper,the kinematics performance of a three degree-of-freedom parallel mechanism with kinematic redundancy(3-DOF PM-KR)and the influence of redundant parts on the PM-KR are analyzed.Firstly,the kinematics model of the PM-KR is established.The inverse solutions,the Jacobian matrix,and the workspace of the PM-KR are solved.Secondly,the influence of redundancy on the PM-KR is analyzed.Since there exists kinematic redundancy,the PM-KR possesses fault-tolerant performance.By locking one actuating joint or two actuating joints simultaneously,the fault-tolerant workspace is obtained.When the position of the redundant part is changed,the workspace and singularity will be changed.The results show that kinematic redundancy can be used to avoid singularity.Finally,the simulations are performed to prove the theoretical analysis.

关键词： Parallel mechanism Kinematic redundancy Singularity Simulation analysis

Scattering center modeling for low-detectable targets

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Journal of Systems Engineering and Electronics 2022年第3期33卷 511-521页

作者： CHEN Yanxi GUO Kunyi xiao Guangliang sheng Xinqing Institute of Radio Frequency Technology and Software School of Integrated Circuits and ElectronicsBeijing Institute of TechnologyBeijing 100081China

The scattering centers(SCs)of low-detectable targets(LDTs)have a low scattering intensity.It is difficult to build the SC model of an LDT using the existing methods because these methods mainly concern dominant SCs with strong scattering contributions.This paper presents an SC modeling approach to acquire the weak SCs of LDTs.We employ the induced currents at the LDT to search SCs,and the joint time-frequency transform together with the Hough transform to separate the scattering contributions of different SCs.Particle swarm optimization(PSO)is applied to improve the estimation results of SCs.The accuracy of the SC model built by this approach is verified by a full-wave numerical method.The validation results show that the SC model of the LDT can precisely simulate the signatures of high-resolution images,such as high-resolution range profile and inverse synthetic aperture radar(ISAR)images.

关键词： low-detectable target(LDT) stealth target scattering center(SC)model time-frequency representation full-wave method

Pseudo-dynamic analysis of a 3D tunnel face in inclined weak strata

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Underground Space 2023年第5期12卷 156-166页

作者： sheng Xu Jing Liu xiao-Li Yang School of Civil Engineering Central South UniversityHunan 410075China

A new discretization technique is proposed for a three-dimensional(3D)tunnel face in weak strata with a random position in space.This method limits the angle,height,and thickness of the strata on the tunnel face.The original whole piece of soil is separated by a series of parallel planes,and two parallel planes are used as a stratum.Each radial discrete plane is separated when it passes through the strata,and the change in the soil properties of discrete points on the truncated plane is considered separately inside the strata.Considering the spatial and temporal characteristics of seismic waves,a pseudo-dynamic analysis of the tunnel face is carried out.The tunnel face active damage types under earthquake conditions are quantitatively analyzed,and the corresponding support pressure design diagrams are given for the case without weak strata.For the case containing weak strata,the presence of weak strata can have adverse effects on the face.The failure mechanism of the weak strata is given by the discretization method.For different friction angles,the presence of the weak strata changes the friction angles of the soils.For the thickness,location and angle of the weak strata,the variation in the support pressure is given in this paper.To more intuitively depict the change in the failure mechanism in the presence of weak strata,the change in the failure mechanism under different thicknesses and weaknesses of weak strata is plotted.

关键词： Tunnel face 3D discretization technique Weak strata Pseudo-dynamic

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气田水对甲烷氢同位素分馏作用

天然气地球科学 2018年第3期29卷 311-316页

作者：秦胜飞周国晓中国石油勘探开发研究院北京100083

水对甲烷碳同位素有明显的分馏作用,但对甲烷氢同位素是否也有分馏作用目前还未见报道。采用自然脱气和真空水浴加热脱气的方法对四川盆地安岳大气田龙王庙组气藏中的气田水进行分步脱气,开展水溶气与游离气中甲烷氢同位素对比研究。发... 详细信息

水对甲烷碳同位素有明显的分馏作用,但对甲烷氢同位素是否也有分馏作用目前还未见报道。采用自然脱气和真空水浴加热脱气的方法对四川盆地安岳大气田龙王庙组气藏中的气田水进行分步脱气,开展水溶气与游离气中甲烷氢同位素对比研究。发现气田水中脱出的甲烷氢同位素值比游离气的明显偏高。分步脱气研究表明,先后脱出的甲烷氢同位素有依次增高的趋势,说明气田水对甲烷氢同位素组成有明显的分馏作用。由此推断,在气藏形成过程中如果经历了大幅度的构造抬升,就会有较多的天然气从水中释放出来混入到游离气中,会使气藏中的甲烷氢同位素值增高。

关键词：气田水水溶气甲烷氢同位素分馏

Precipitation Microphysical Characteristics of Typhoon Ewiniar(2018) before and after Its Final Landfall over Southern China

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Advances in Atmospheric Sciences 2023年第6期40卷 1005-1020页

作者： Lu FENG Hui xiao Xiantong LIU sheng HU Huiqi LI Liusi xiao xiao HAO Guangzhou Institute of Tropical and Marine Meteorology China Meteorological AdministrationGuangzhou 510641China Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction China Meteorological AdministrationGuangzhou 510641China Guangzhou Meteorological Observatory China Meteorological AdministrationGuangzhou 511430China

In this paper, the evolution of the microphysical characteristics in different regions(eyewall, inner core, and outer rainbands) and different quadrants [downshear left(DL), downshear right(DR), upshear left(UL), and upshear right(UR)]during the final landfall of Typhoon Ewiniar(2018) is analyzed using two-dimensional video disdrometer and S-band polarimetric radar data collected in Guangdong, China. Due to the different types of underlying surfaces, the periods before landfall(mainly dominated by underlying sea surface) and after landfall(mainly dominated by underlying land surface) are also analyzed. Both before landfall and after landfall, the downshear quadrants had the dominate typhoon precipitation. The outer rainbands had more graupel than the inner core, resulting in a larger radar reflectivity, differential reflectivity, specific differential phase shift, and mass-weighted mean diameter below the melting layer. Compared with other regions, the eyewall region had the smallest mean logarithmic normalized intercept parameter before landfall and the smallest mean mass-weighted mean diameter and the largest mean logarithmic normalized intercept parameter after landfall. The hydrometeor size sorting was obvious in the eyewall and inner core(especially in the eyewall) after landfall. A high concentration of large raindrops fell in the DL quadrant, and more small raindrops fell in the UR quadrant. Although the icephase process and warm rain process were both important in the formation of tropical cyclone precipitation, the warm rain process(ice-phase process) contributed more liquid water before landfall(after landfall). This investigation provides a reference for improving the microphysical parameterization scheme in numerical models.

关键词： tropical cyclone precipitation microphysics raindrop size distribution southern China