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Spacelike Framed Curves with Lightlike Components and Singularities of Their Evolutes and Focal Surfaces in Minkowski 3-space

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Acta Mathematica Sinica,English Series 2024年第6期40卷 1521-1532页

作者： peng Cheng LI Dong He PEI xin zhao School of Mathematics and Statistics Northeast Normal UniversityChangchun 130024P.R.China Department of Mathematics Harbin Institute of TechnologyWeihai 264209P.R.China School of Mathematics and Statistics Qingdao UniversityQingdao 266071P.R.China

In this paper,we define the evolute and focal surface of a spacelike framed curve with lightlike components in Minkowski *** is a generalization of the previous results of regular spacelike curves,since singularities are allowed in the original spacelike curves studied by spacelike framed curves with lightlike ***,we show a new geometric invariant to characterise singularities of the focal ***,the classification theorem and recognition theorem for the singularities of the focal surface in generic are also given.

关键词： Evolutes focal surfaces spacelike framed curves singularities

Fine-tuning the ductile-brittle transition temperature of Mg_2Si intermetallic compound via Al doping

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International Journal of Minerals,Metallurgy and Materials 2019年第4期26卷 507-515页

作者： Ao Li xin-peng zhao Hai-you Huang Yuan Ma Lei Gao Yan-jing Su Ping Qian Institute for Advanced Materials and Technology University of Science and Technology Beijing Corrosion and Protection Center Key Laboratory for Environmental Fracture of Ministry of EducationUniversity of Science and Technology Beijing Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology Beijing Department of Physics University of Science and Technology Beijing

Brittleness is a dominant issue that restricts potential applications of Mg_2Si intermetallic compounds(IMC). In this paper, guided by first-principles calculations, we found that Al doping will enhance the ductility of Mg_2Si. The underlying mechanism is that Al doping could reduce the electronic exchange effect between Mg and Si atoms, and increase the volume module/shear modulus ratio, both of which are beneficial to the deformation capability of Mg_2Si. Experimental investigations were then carried out to verify the calculation results with Al doping contents ranging from Al-free to 10 wt%. Results showed that the obtained ductile-brittle transition temperature of the Mg_2Si–Al alloy decreased and the corresponding ductility increased. Specifically, the ductile-brittle transition temperature could be reduced by about 100℃. When the content of Al reached 6 wt%, α-Al phase started to precipitate, and the ductile-brittle transition temperature of the alloy no longer decreased.

关键词： Mg alloy intermetallic compound first-principles calculations mechanical properties ductile-brittle transition temperature

Nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in aerospace community:a comparative analysis

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International Journal of Extreme Manufacturing 2024年第2期6卷 190-271页

作者： Guolong zhao Biao zhao Wenfeng Ding Lianjia xin Zhiwen Nian Jianhao peng Ning He Jiuhua Xu College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016People’s Republic of China

The aerospace community widely uses difficult-to-cut materials,such as titanium alloys,high-temperature alloys,metal/ceramic/polymer matrix composites,hard and brittle materials,and geometrically complex components,such as thin-walled structures,microchannels,and complex *** machining is the main material removal process for the vast majority of aerospace ***,many problems exist,including severe and rapid tool wear,low machining efficiency,and poor surface *** energy-assisted mechanical machining is a hybrid process that uses nontraditional energies(vibration,laser,electricity,etc)to improve the machinability of local materials and decrease the burden of mechanical *** provides a feasible and promising method to improve the material removal rate and surface quality,reduce process forces,and prolong tool ***,systematic reviews of this technology are lacking with respect to the current research status and development *** paper reviews the recent progress in the nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in the aerospace *** addition,this paper focuses on the processing principles,material responses under nontraditional energy,resultant forces and temperatures,material removal mechanisms,and applications of these processes,including vibration-,laser-,electric-,magnetic-,chemical-,advanced coolant-,and hybrid nontraditional energy-assisted mechanical ***,a comprehensive summary of the principles,advantages,and limitations of each hybrid process is provided,and future perspectives on forward design,device development,and sustainability of nontraditional energy-assisted mechanical machining processes are discussed.

关键词： difficult-to-cut materials geometrically complex components nontraditional energy mechanical machining aerospace community

Computed tomography-based multi-organ radiomics nomogram model for predicting the risk of esophagogastric variceal bleeding in cirrhosis

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World Journal of Gastroenterology 2024年第36期30卷 4044-4056页

作者： Yu-Jie peng xin Liu Ying Liu Xue Tang Qi-peng zhao Yong Du Department of Radiology The Affiliated Hospital of North Sichuan Medical CollegeNanchong 637000Sichuan ProvinceChina Department of Radiology The People’s Hospital of Chongqing Liang Jiang New AreaChongqing 401121China

BACKGROUND Radiomics has been used in the diagnosis of cirrhosis and prediction of its associated ***,most current studies predict the risk of esophageal variceal bleeding(EVB)based on image features at a single level,which results in incomplete *** studies have explored the use of global multi-organ radiomics for non-invasive prediction of EVB secondary to *** To develop a model based on clinical and multi-organ radiomic features to predict the risk of first-instance secondary EVB in patients with *** In this study,208 patients with cirrhosis were retrospectively evaluated and randomly split into training(n=145)and validation(n=63)*** areas were chosen as regions of interest for extraction of multi-organ radiomic features:The whole liver,whole spleen,and lower esophagus–gastric fundus *** the training cohort,radiomic score(Rad-score)was created by screening radiomic features using the inter-observer and intra-observer correlation coefficients and the least absolute shrinkage and selection operator *** clinical risk factors were selected using multivariate logistic regression *** radiomic features and clinical risk variables were combined to create a new radiomics-clinical model(RC model).The established models were validated using the validation *** Radiomics has been used in the diagnosis of cirrhosis and prediction of its associated ***,most current studies predict the risk of esophageal variceal bleeding(EVB)based on image features at a single level,which results in incomplete *** studies have explored the use of global multi-organ radiomics for non-invasive prediction of EVB secondary to *** To develop a model based on clinical and multi-organ radiomic features to predict the risk of first-instance secondary EVB in patients with *** In this study,208 patients with cirrhosis were retrospectively evaluated and randoml

关键词： Artificial intelligence Cirrhosis Radiomics Esophagogastric variceal bleeding

A review on heat transfer in nanoporous silica aerogel insulation materials and its modeling

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Energy Storage and Saving 2022年第4期1卷 217-240页

作者： Chuan-Yong Zhu Hai-Bo Xu xin-peng zhao Liang Gong Zeng-Yao Li Key Laboratory of Thermo-Fluid and Science and Engineering Ministry of EducationSchool of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an710049China College of New Energy China University of Petroleum(East China)Qingdao266580China

Silica aerogels are widely used in many fields for thermal insulation,such as building insulation,electric power energy,energy storage systems,and high-temperature thermal protection due to their excellent insulation ***,the heat transfer in silica aerogels and its modeling in recent years have attracted much attention and many valuable achievements have been *** heat transfer in nano-porous silica aerogels and its modeling methods are reviewed in this *** review starts with a brief introduction of heat transfer characteristics in silica aerogels,including the multi-component and multi-mode coupling effect,size effect,and multiscale *** the heat transfer mechanism of each mode,including heat transfer via gas phase,solid phase,and thermal radiation,is reviewed,and the models for predicting the gaseous thermal conductivity in nanoscale pores,gas-contributed thermal conductivity,the apparent thermal conductivity of solid skeleton,and finally the effective thermal conductivity are collected and discussed in ***,modeling of transient heat transfer in silica aerogels is also briefly ***,the conclusions and some problems which need to be further investigated in the future are provided.

关键词： Nanoporous silica aerogels Heat transfer characteristics Thermal conductivity Thermal insulation Modeling

Evaluation of water management on arsenic methylation and volatilization in arsenic-contaminated soils strengthened by bioaugmentation and biostimulation

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Journal of Environmental Sciences 2024年第3期137卷 515-526页

作者： peng Chen Yi Liu Guo-xin Sun State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Key Laboratory of Aquatic Botany and Watershed Ecology Wuhan Botanical GardenChinese Academy of SciencesWuhan 430074China University of Chinese Academy of Sciences Beijing 100049China

Arsenic(As) fate in paddy fields has been one of the most significant current issues due to the strong As accumulation potential of rice plants under fooded conditions. However,no attempt was done to explore As methylation and volatilization under non-fooded conditions. Herein, we investigated the effects of water management on As methylation and volatilization in three arsenic-contaminated soils enhanced by biostimulation with strawderived organic matter and bioaugmentation with genetic engineered Pseudomonas putida KT2440(GE P. putida). Under fooded conditions, the application of biochar(BC), rice straw(RS)and their combination(BC+RS) increased total As in porewater. However, these effects were greatly attenuated under non-fooded conditions. Compared with RS amendment alone, the combination of GE P. putida and RS further promoted the As methylation and volatilization,and the promotion percentage under non-fooded conditions were significantly higher than that under fooded conditions. The combined GE P. putida and RS showed the highest efficiency in As methylation(88 μg/L) and volatilization(415.4 μg/(kg·year)) in the non-fooded soil with moderate As contamination. Finally, stepwise multiple linear regression analysis presented that methylated As, DOC and p H in porewater were the most important factors contributing to As volatilization. Overall, our findings suggest that combination of bioaugmentation with GE P. putida and biostimulation with RS/BC+RS is a potential strategy for bioremediation of arsenic-contaminated soils by enhancing As methylation and volatilization under non-fooded conditions.

关键词： Arsenic methylation Arsenic volatilization Water management Straw incorporation Bioaugmentation

Principal components of nuclear mass models

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 65-71页

作者： xin-Hui Wu pengwei zhao Department of Physics Fuzhou UniversityFuzhou 350108China State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China

Principal component analysis(PCA)is employed to extract the principal components(PCs)present in nuclear mass models for the first *** effects from different nuclear mass models are reintegrated and reorganized in the extracted *** PCs are recombined to build new mass models,which achieve better accuracy than the original theoretical mass *** comparison indicates that using the PCA approach,the effects contained in different mass models can be collaborated to improve nuclear mass predictions.

关键词： nuclear mass principal component analysis nuclear models statistical methods

A sub-grid scale model for Burgers turbulence based on the artificial neural network method

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Theoretical & Applied Mechanics Letters 2024年第3期14卷 162-165页

作者： xin zhao Kaiyi Yin Department of Mechanics Beijing Institute of TechnologyBeijing 100081China

The present study proposes a sub-grid scale model for the one-dimensional Burgers turbulence based on the neuralnetwork and deep learning *** filtered data of the direct numerical simulation is used to establish thetraining data set,the validation data set,and the test data *** artificial neural network(ANN)methodand Back Propagation method are employed to train parameters in the *** developed ANN is applied toconstruct the sub-grid scale model for the large eddy simulation of the Burgers turbulence in the *** proposed model well predicts the time correlation and the space correlation of the Burgers turbulence.

关键词： Artificial neural network Back propagation method Burgers turbulence Large eddy simulation Sub-grid scale model

Nonlinear metamaterial enabled aeroelastic vibration reduction of a supersonic cantilever wing plate

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Applied Mathematics and Mechanics(English Edition) 2024年第10期45卷 1749-1772页

作者： peng SHENG xin FANG Dianlong YU Jihong WEN Laboratory of Science and Technology on Integrated Logistics Support College of Intelligence Science and TechnologyNational University of Defense TechnologyChangsha 410073China

The violent vibration of supersonic wings threatens aircraft *** paper proposes the strongly nonlinear acoustic metamaterial(NAM)method to mitigate aeroelastic vibration in supersonic wing *** employ the cantilever plate to simulate the practical behavior of a *** aeroelastic vibration model of the NAM cantilever plate is established based on the mode superposition method and a modified third-order piston *** aerodynamic properties are systematically studied using both the timedomain integration and frequency-domain harmonic balance *** presenting the flutter and post-flutter behaviors of the NAM wing,we emphasize more on the preflutter broadband vibration that is prevalent in *** results show that the NAM method can reduce the low-frequency and broadband pre-flutter steady vibration by 50%-90%,while the post-flutter vibration is reduced by over 95%,and the critical flutter velocity is also slightly *** clarified,the significant reduction arises from the bandgap,chaotic band,and nonlinear resonances of the NAM *** reduction effect is robust across a broad range of parameters,with optimal performance achieved with only 10%attached *** work offers a novel approach for reducing aeroelastic vibration in aircraft,and it expands the study of nonlinear acoustic/elastic metamaterials.

关键词： nonlinear acoustic metamaterial(NAM) hypersonic aeroelastic vibration vibration reduction fluid-structure interaction