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Learning Invariance Preserving Moment Closure Model for Boltzmann-BGK Equation

Communications in Mathematics and Statistics 2023年第1期11卷 59-101页

作者： zhengyi li Bin Dong Yanli Wang School of Mathematical Sciences Peking UniversityBeijingPeople’s Republic of China Beijing International Center for Mathematical Research&Center for Machine Learning Research Peking UniversityBeijingPeople’s Republic of China Beijing Computational Science Research Center BeijingPeople’s Republic of China

As one of the main governing equations in kinetic theory,the Boltzmann equation is widely utilized in aerospace,microscopic flow,*** high-resolution simulation is crucial in these related ***,due to the high dimensionality of the Boltzmann equation,high-resolution simulations are often difficult to achieve *** moment method which was first proposed in Grad(Commun Pure Appl Math 2(4):331-407,1949)is among the popular numerical methods to achieve efficient high-resolution *** can derive the governing equations in the moment method by taking moments on both sides of the Boltzmann equation,which effectively reduces the dimensionality of the ***,one of themain challenges is that it leads to an unclosed moment system,and closure is needed to obtain a closedmoment *** is truly an art in designing closures for moment systems and has been a significant research field in kinetic *** than the traditional human designs of closures,the machine learning-based approach has attracted much attention lately in Han et al.(Proc Natl Acad Sci USA 116(44):21983-21991,2019)and Huang et al.(J Non-Equilib Thermodyn 46(4):355-370,2021).In this work,we propose a machine learning-based method to derive a moment closure model for the Boltzmann-BGK *** particular,the closure relation is approximated by a carefully designed deep neural network that possesses desirable physical invariances,i.e.,the Galilean invariance,reflecting invariance,and scaling invariance,inherited from the original Boltzmann-BGK equation and playing an important role in the correct simulation of the Boltzmann *** simulations on the 1D-1D examples including the smooth and discontinuous initial condition problems,Sod shock tube problem,the shock structure problems,and the 1D-3D examples including the smooth and discontinuous problems demonstrate satisfactory numerical performances of the proposed invariance preserving neural closure method

关键词： Boltzmann equation Moment closure Machine learning Neural networks Invariance preserving

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Partial CRC-aided decoding of 5G-NR short codes using reliability information

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Science China(Information Sciences) 2019年第8期62卷 35-43页

作者： Ming JIANG zhengyi li Xiao YANG Chunming ZHAO National Mobile Communications Research Laboratory Southeast University

In this paper, we focus on how to further enhance the performance of the channel codes in order to meet the more stringent reliability requirements of future networks(5G and beyond). A general decoder with the aid of partial cyclic redundancy check(CRC) bits is proposed for the polar codes and short low-density parity-check(LDPC) codes in 5G systems. The decoder based on ordered statistic decoding(OSD) method can effectively improve the error-correction performance on the condition that extra CRC bits are used to assist in decoding. Meanwhile, the remaining part of CRC keeps its capability of errordetection to guarantee the undetected error rate low enough. This paper gives the detailed implementation schemes of the partial CRC-aided OSD process and its combination with the conventional decodings of the LDPC/polar codes in 5G systems. The simulation results show our proposed decoding scheme achieves a promising trade-off between the performance gain and the error-detection capabilities.

关键词： polar codes LDPC codes CRC codes successive cancellation list decoding ordered statistic decoding

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Catalytic cascade acetylation-alkylation of biofuran to C_(17)diesel precursor enabled by a budget acid-switchable catalyst

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Chinese Journal of Chemical Engineering 2021年第6期34卷 171-179页

作者： Chuanhui li Yuanzhong li Xiaoxiang Luo zhengyi li Heng Zhang Hu li Song Yang State Key Laboratory Breeding Base of Green Pesticide&Agricultural Bioengineering Key Laboratory of Green Pesticide&Agricultural BioengineeringMinistry of EducationState-Local Joint Laboratory for Comprehensive Utilization of BiomassCenter for R&D of Fine ChemicalsGuizhou UniversityGuiyang 550025China

lignocellulosic biomass is a promising feedstock for the synthesis of value-added chemicals and ***,one of the biggest challenges for producing high-quality diesel fuels is the lack of sufficient carbon-chain length in biomass *** this study,a C_(17)diesel precursor 1,1,1-tris(5-methyl-2-f uryl)ethane(TEMF)with a yield of ca.70%was synthesized from the cascade acetylation-hydroxyalkyla tion/alkylation of bio-based 2-methylfuran(MF)with acetic anhydride(AA)catalyzed by acid-treated montmorillonite with enhanced acidity and improved *** catalytic mechanism of the cascade reaction process was investigated over different types of acid species(Br?nsted acid and Lewis acid),and the influence of in situ formed acetic acid was also examined.A synergistic effect was observed to enable the synthesis of TEMF from the trimerization of MF with AA,in which Lewis acid and weak Br?nsted acid species mainly catalyze the acetylation and hydroxyalkylation processes,while the subsequent alkylation step is mainly catalyzed by strong Br?nsted acid.

关键词： Biomass Diesel Catalysis Biofuranic compound Acetylation-alkylation

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Bayesian estimator of human error probability based on human performance data

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Journal of Systems Engineering and Electronics 2013年第2期24卷 242-249页

作者： Zhiqiang Sun Erling Gong zhengyi li Yingjie Jiang Hongwei Xie College of Mechatronic Engineering and Automation National University of Defense Technology Department of Computer Changsha Social Work College

A Bayesian method for estimating human error probability（HEP） is *** main idea of the method is incorporating human performance data into the HEP estimation *** integrating human performance data and prior information about human performance together,a more accurate and specific HEP estimation can be *** the time-unrelated task without rigorous time restriction,the HEP estimated by the common-used human reliability analysis（HRA） methods or expert judgments is collected as the source of prior *** for the time-related task with rigorous time restriction,the human error is expressed as non-response ***,HEP is the time curve of non-response probability（NRP）.The prior information is collected from system safety and reliability specifications or by expert ***（joint） posterior distribution of HEP or NRP-related parameter（s） is constructed after prior information has been *** on the posterior distribution,the point or interval estimation of HEP/NRP is *** illustrative examples are introduced to demonstrate the practicality of the aforementioned approach.

关键词： human error probability(HEP) human performance data human reliability probabilistic safety assessment Bayesian approach

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MIDNet:Deblurring Network for Material Microstructure Images

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Computers, Materials & Continua 2024年第4期79卷 1187-1204页

作者： Jiaxiang Wang zhengyi li Peng Shi Hongying Yu Dongbai Sun National Center for Materials Service Safety University of Science and Technology BeijingBeijing100083China School of Materials Sun Yat-Sen UniversityShenzhen518107China School of Materials Science and Engineering Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Sun Yat-Sen UniversityGuangzhou510006China

Scanning electron microscopy(SEM)is a crucial tool in the field of materials science,providing valuable insightsinto the microstructural characteristics of ***,SEM images often suffer from blurrinesscaused by improper hardware calibration or imaging automation errors,which present challenges in analyzingand interpretingmaterial ***,rectifying the blurring of these images assumes paramountsignificance to enable subsequent *** address this issue,we introduce a Material Images DeblurringNetwork(MIDNet)built upon the foundation of the Nonlinear Activation Free Network(NAFNet).MIDNetis meticulously tailored to address the blurring in images capturing the microstructure of *** keycontributions include enhancing the NAFNet architecture for better feature extraction and representation,integratinga novel soft attention mechanism to uncover important correlations between encoder and decoder,andintroducing newmulti-loss functions to improve training effectiveness and overallmodel *** conducta comprehensive set of experiments utilizing the material blurry dataset and compare them to several state-of-theartdeblurring *** experimental results demonstrate the applicability and effectiveness of MIDNet in thedomain of deblurring material microstructure images,with a PSNR(Peak Signal-to-Noise Ratio)reaching 35.26 dBand an SSIM(Structural Similarity)of *** dataset is available at:https://***/woshigui/MIDNet.

关键词： Image deblurring material microstructure attention mechanism deep learning

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Structure of the brachial plexus root and adjacent regions displayed by ultrasound imaging

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Neural Regeneration Research 2012年第26期7卷 2044-2050页

作者： zhengyi li Xun Xia Xiaoming Rong Yamei Tang Dachuan Xu Institute of Clinical Anatomy Southern Medical University Guangzhou 510515 Guangdong Province China Department of Ultrasound Shenzhen Second People's Hospital Shenzhen 518035 Guangdong Province China Department of Neurology Sun Yat-sen Memorial Hospital Sun Yat-sen University Guangzhou 510120 Guangdong Province China

Brachial plexuses of 110 healthy volunteers were examined using high resolution color Doppler ultrasound. Ultrasonic characteristics and anatomic variation in the intervertebral foramen, interscalene, supraclavicular and infraclavicular, as well as the axillary brachial plexus were investigated. Results confirmed that the normal brachial plexus on cross section exhibited round or elliptic hypoechoic texture. Longitudinal section imaging showed many parallel linear hypo-moderate echoes, with hypo-echo. The transverse processes of the seventh cervical vertebra, the scalene space, the subclavian artery and the deep cervical artery are important markers in an examination. The display rates for the interscalene, and supraclavicular and axillary brachial plexuses were 100% each, while that for the infraclavicular brachial plexus was 97%. The region where the normal brachial plexus root traversed the intervertebral foramen exhibited a regular hypo-echo. The display rate for the C5-7 nerve roots was 100%, while those for C8 and T1 were 83% and 68%, respectively. A total of 20 of the 110 subjects underwent cervical CT scan. High-frequency ultrasound can clearly display the outline of the transverse processes of the vertebrae, which were consistent with CT results. These results indicate that high-frequency ultrasound provides a new method for observing the morphology of the brachial plexus. The C~ vertebra is a marker for identifying the position of brachial plexus nerve roots.

关键词： brachial plexus ultrasound anatomical characteristics CT nerve root brachial plexus block neuralregeneration

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Acidic Magnetic Biocarbon-Enabled Upgrading of Biomass-Based Hexanedione into Pyrroles

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Journal of Renewable Materials 2023年第11期11卷 3847-3865页

作者： Zhimei li Kuan Tian Keping Wang zhengyi li Haoli Qin Hu li School of Chemistry and Materials Science Guizhou Normal UniversityGuiyang550001China National Key Laboratory of Green Pesticide Key Laboratory of Green Pesticide and Agricultural BioengineeringMinistry of EducationState-Local Joint Laboratory for Comprehensive Utilization of BiomassCenter for R&D of Fine Chemicals of Guizhou UniversityGuiyang550025China

Sustainable acquisition of bioactive compounds from biomass-based platform molecules is a green alternative for existing CO_(2)-emitting fossil-fuel ***,a core–shell magnetic biocarbon catalyst functionalized with sulfonic acid(Fe3O4@SiO_(2)@chitosan-SO_(3)H,MBC-SO_(3)H)was prepared to be efficient for the synthesis of various N-substituted pyrroles(up to 99% yield)from bio-based hexanedione and amines under mild *** abundance of Bronsted acid sites in the MBC-SO_(3)H ensured smooth condensation of 2,5-hexanedione with a variety of amines to produce N-substituted *** reaction was illustrated to follow the conventional Pall-Knorr coupling pathway,which includes three cascade reaction steps:amination,loop closure and *** prepared MBC-SO_(3)H catalyst could effectively activate 2,5-hexanedione,thus weakening the dependence of the overall conversion process on the amine *** influence of different factors(e.g.,reaction temperature,time,amount of catalyst,molar ratio of substrates,and solvent type)on the reaction activity and selectivity were investigated ***,the MBC-SO_(3)H possessed excellent thermochemical stability,reusability,and easy separation due to the presence of magnetic core-shell ***,there was no activity attenuation after 5 consecutive catalytic *** work demonstrates a wide range of potential applications of developing functionalized core-shell magnetic materials to construct bioactive backbones from biomass-based platform molecules.

关键词： Magnetic materials biomass conversion heterogeneous catalysis sustainable chemistry

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Omics for deciphering oral microecology

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International Journal of Oral Science 2024年第2期16卷 197-207页

作者： Yongwang lin Xiaoyue liang zhengyi li Tao Gong Biao Ren Yuqing li Xian Peng State Key Laboratory of Oral Diseases&National Center for Stomatology&National Clinical Research Center for Oral Diseases West China Hospital of StomatologySichuan UniversityChengduChina

The human oral microbiome harbors one of the most diverse microbial communities in the human body,playing critical roles in oral and systemic *** technological innovations are propelling the characterization and manipulation of oral ***-throughput sequencing enables comprehensive taxonomic and functional profiling of oral *** long-read platforms improve genome assembly from complex ***-cell genomics provides insights into uncultured *** imaging modalities including fluorescence,mass spectrometry,and Raman spectroscopy have enabled the visualization of the spatial organization and interactions of oral microbes with increasing *** techniques link phylogenetic identity with *** spectrometry imaging reveals metabolic niches and activities while Raman spectroscopy generates rapid biomolecular fingerprints for *** facilitates the isolation and cultivation of novel fastidious oral taxa using high-throughput *** integration of these technologies holds the promise of transforming our understanding of oral microbiome assembly,gene expression,metabolites,microenvironments,virulence mechanisms,and microbe-host interfaces in the context of health and ***,significant knowledge gaps persist regarding community origins,developmental trajectories,homeostasis versus dysbiosis triggers,functional biomarkers,and strategies to deliberately reshape the oral microbiome for therapeutic *** convergence of sequencing,imaging,cultureomics,synthetic systems,and biomimetic models will provide unprecedented insights into the oral microbiome and offer opportunities to predict,prevent,diagnose,and treat associated oral diseases.

关键词： insight holds oral

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Novel supramolecular organocatalysts of hydroxyprolinamide based on calix[4]arene scaffold for the enantioselective Biginelli reaction

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Science China Chemistry 2011年第11期54卷 1726-1734页

作者： li zhengyi XING HuaiJie HUANG Guoli SUN XiaoQiang JIANG Juli WANG LeYong Key Laboratory of Fine Petrochemical Engineering School of Petrochemical Engineering Changzhou University Changzhou 213164 China Institute of Chemical Biology and Drug Innovation School of Chemistry and Chemical Engineering Nanjing University Nanjing 210093 China

A series of novel supramolecular organocatalysts of hydroxyprolinamide based on the upper rim of calix[4]arene scaffold have been developed to catalyze enantioselective multi-component Biginelli reaction. Under the optimal conditions, the reactions occurred with moderate-to-excellent enantioselectivities (up to 98% ee). A plausible transition state constructed by the supra- molecular interaction of hydrogen bond and cation-π between catalysts and substrates has been proposed.

关键词： supramolecular organocatalyst calixarene hydroxyprolinamide enantioselective Biginelli reaction

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Protective Graphite Coating for Two-Dimensional Carbon/Carbon Composites

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Fluid Dynamics & Materials Processing 2024年第1期20卷 97-108页

作者： Wei Shi zhengyi li Xiaobing Xu Yingshui Yu Xiaofei Ding Heng Ju School of Mechanical and Power Engineering Dalian Ocean UniversityDalian116023China School of Mechanical and Electrical Engineering Gongqing Institute of Science and TechnologyJiujiang332020China

Two-dimensional carbon/carbon(2D C/C)composites are a special class of carbon/carbon composites,generally obtained by combining resin-impregnated carbon fiber clothes,which are then cured and *** study deals with the preparation of a protective coating for these *** coating,based on graphite,was prepared by the slurry *** effect of graphite and phenolic resin powders with different weight ratios was *** results have shown that the coating slurry can fill the pores and cracks of the composite surface,thereby densifying the surface layer of the *** the increase of the graphite powder/phenolic resin weight ratio,the coating density is enhanced while the coating surface flatness decreases;moreover,the protective ability of coating against erosion first increases(from 1:3 to 2:2)and then decreases(from 2:2 to 3:1).When the weight ratio is about 1:1,the coating for 2D C/C composites exhibits the best erosion resistance,which greatly aids these materials during gas *** this case,the erosion rate is decreased by approximately 41.5%at the impact angle of 30°and 52.3%at normal impact,*** can be attributed to the ability of the coating slurry to infiltrate into the substrate,thereby bonding the fibers together and increasing the compactness of the 2D C/C composites.

关键词： Carbon/carbon composites graphite coating microstructure erosion resistance

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