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Acta Mechanica Solida Sinica 2023年第5期36卷 672-684页

作者： di chen Jun-Jiang Xiong School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China School of Transportation Science and Engineering Beihang UniversityBeijing 102206China

This paper seeks to investigate nonlinear out-of-plane mechanical behaviours of woven composite flexible skin(WCFS)through experimental and theoretical ***,quasi-static experiments are carried out on rectangular WCFSs with different aspect ratios under uniform normal pressure to measure out-of-plane deformation and failure ***,a new three-parameter geometric model is presented to describe 3D geometry of pressurized WCFS,and thus,a nonlinear mechanical model is deduced for depicting the relationship between pressure and out-of-plane *** application of the aforementioned models for experimental results shows that the new models have adequately and logically depicted deformation geometry and nonlinear mechanical characteristics.

关键词： Woven compositeﬂexible skin Nonlinear performance Uniform normal pressure Geometric model Mechanical model Aspect ratio

Observation of topological charge transformations in acoustic vortex using passive periodic systems

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 140-147页

作者： di-Chao chen Xie Liu Changqing Xu Da-Jian Wu Ying cheng Xiao-Jun Liu School of Physics and Technology Nanjing Normal University Key Laboratory of Modern Acoustics School of Physics Nanjing University

Vortex transmutation utilizes a periodic system, which not only enables the alteration of the topological charge(TC) of unstable input vortices but also facilitates their transformation into stable structures. This approach is crucial for investigating the characteristics of vortices in various wave systems. Here, we achieve acoustic vortex TC transmutation by employing a welldesigned dual-structured plate external system(DPES). The interactions between the acoustic vortex and the finite-order discrete rotational symmetry lead to the transformation of its topological charge when complete rotational symmetry is broken to Nthorder discrete symmetry. Our results experimentally demonstrate the acoustic vortex TC transmutation based on passive artificial structures, enabling numerous applications in particle manipulation and information multiplexing as well as advancing our understanding and control over free-space acoustic vortices.

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Characteristics of extratropical cyclone variability in the Northern Hemisphere and their response to rapid changes in Arctic sea ice

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Acta Oceanologica Sinica 2023年第10期42卷 10-22页

作者： di chen Qizhen Sun Ocean University of China Qingdao 266100China National Marine Environmental Forecasting Center Beijing 100081China

Extratropical cyclones are critical weather systems that affect large-scale weather and climate changes at mid-high ***,prior research shows that there are still great difficulties in predicting extratropical cyclones for occurrence,frequency,and *** this study,mean sea level pressure(MSLP)data from the European Centre for Medium-Range Weather Forecasts(ECMWF)reanalysis(ERA5)are used to calculate the variance statistics of the MSLP to reveal extratropical cyclone activity(ECA).Based on the analysis of the change characteristics of ECA in the Northern Hemisphere,the intrinsic link between ECA in the Northern Hemisphere and Arctic sea ice is *** results show that the maximum ECA mainly occurs in winter over the mid-high latitudes in the Northern *** maximum ECA changes in the North Pacific and the North Atlantic,which are the largest variations in the Northern Hemisphere,are independent of each other,and their mechanisms may be ***,MSLP is a significant physical variable that affects *** North Atlantic Oscillation(NAO)and North Pacific Index(NPI)are significant indices that impact ECA in the North Atlantic and North Pacific,*** innovation of this paper is to explore the relationship between the activity of extratropical cyclones in the Northern Hemisphere and the abnormal changes in Arctic sea ice for the first *** mechanism is that the abnormal changes in summer-autumn and winter Arctic sea ice lead to the phase transition of the NPI and NAO,respectively,and then cause the occurrence of ECA in the North Pacific and North Atlantic,*** sea ice plays a crucial role in the ECA in the Northern Hemisphere by influencing the polar vortex and westerly *** is the first exploration of ECAs in the Northern Hemisphere using Arctic sea ice,which can provide some references for the in-depth study and prediction of ECAs in the Northern Hemisphere.

关键词： extratropical cyclones mean sea level pressure North Atlantic Oscillation(NAO) North Pacific Index(NPI) Arctic sea ice

Restoration of Ultimate Strength of Dented Hemispheres Under External Hydrostatic Pressure

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China Ocean Engineering 2022年第3期36卷 500-507页

作者： HUANG chen ZHANG Jian WANG Fang di chen-yang School of Mechanical Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China Shanghai Engineering Research Center of Hadal Science and Technology Shanghai Ocean UniversityShanghai 201306China

This study aimed to restore the ultimate strength of dented stainless-steel hemispheres with a radius of 90 mm and a thickness of 0.86 *** of the hemispheres were subjected to external hydrostatic *** stainless-steel stiffened caps were used to eliminate the effect of indention on the ultimate *** caps had a radius of 36 mm,a thickness of 0.76 mm,and a height of 10.44 *** hemispherical samples,including two intact hemispheres,two dented hemispheres without stiffening,and two dented hemispheres with stiffening,were *** hemi-sphere was geometrically measured for shape and thickness,hydrostatically tested for destruction,and numerically evaluated for *** experimental and numerical data agreed well with each *** a result,a spherical cap can effectively restore the ultimate strength of dented hemispheres under external hydrostatic *** proposed restoration approach can be used to strengthen underwater pressure hulls with large local geometric imperfections.

关键词： hemisphere restoration ultimate strength hydrostatic pressure buckling

Memetic algorithm for multi-mode resource-constrained project scheduling problems

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Journal of Systems Engineering and Electronics 2014年第4期25卷 609-617页

作者： Shixin Liu di chen Yifan Wang College of Information Science and Engineering Northeastern University

A memetic algorithm （MA） for a multi-mode resourceconstrained project scheduling problem （MRCPSP） is proposed. We use a new fitness function and two very effective local search procedures in the proposed MA. The fitness function makes use of a mechanism called ＂strategic oscillation＂ to make the search process have a higher probability to visit solutions around a ＂feasible boundary＂. One of the local search procedures aims at improving the lower bound of project makespan to be less than a known upper bound, and another aims at improving a solution of an MRCPSP instance accepting infeasible solutions based on the new fitness function in the search process. A detailed computational experiment is set up using instances from the problem instance library PSPLIB. Computational results show that the proposed MA is very competitive with the state-of-the-art algorithms. The MA obtains improved solutions for one instance of set J30.

关键词： project scheduling resource-constrained multi-mode,memetic algorithm (MA) local search procedure.

Minimax Optimal Rates of Convergence for Multicategory Classifications

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Acta Mathematica Sinica,English Series 2007年第8期23卷 1419-1426页

作者： di Rong chen Xu YOU Department of Mathematics and LMIB Beijing University of Aeronautics and Astronautics Beijing 100083 P. R. China

In the problem of classification （or pattern recognition）, given a set of n samples, we attempt to construct a classifier gn with a small misclassification error. It is important to study the convergence rates of the misclassification error as n tends to infinity. It is known that such a rate can＇t exist for the set of all distributions. In this paper we obtain the optimal convergence rates for a class of distributions L^（λ,ω） in multicategory classification and nonstandard binary classification.

关键词： rate of convergence error probability modulus of continuity multicategory classification

Construction of Authentication Codes with Double Arbiters over Symplectic Geometry

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Acta Mathematicae Applicatae Sinica 2015年第4期31卷 1141-1152页

作者： Shang-di chen Hao MA College of Science Civil Aviation University of China

In a common authentication code with arbitration, the dishonest arbiter may make a threat to the security of authentication system. In this paper, an authentication code with double arbiters over symplectic geometry is constructed, and the relevant parameters and the probabilities of successful attacks are calculated. The model not only prevents deception from the opponent and members of the system, but also effectively limits the attacks of single arbiter. Moreover, the collusion attacks from arbiters and participators are difficult to succeed.

关键词： authentication code double arbiters symplectic geometry

New Constructions of Orbit Codes Based on the Operations of Orbit Codes

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Acta Mathematicae Applicatae Sinica 2020年第4期36卷 803-815页

作者： Shang-di chen Jun-ying LIANG College of Science Civil Aviation University of ChinaTianjin 300300China Information Security Center State Key Laboratory of Net working and Switching TechnologyBeijing University of Posts and TelecommunicationsBeijing100876China

An orbit code is a special constant dimension subspace code,which is an orbit of a subgroup of a general linear group acting on the set of all subspaces in the given ambient *** paper presents some methods of constructing new orbit codes from known orbit ***,we introduce the sum operation,intersection operation and union operation of subspace codes,and then we give some methods to obtain new orbit codes from known orbit codes by fully applying the sub-orbits of permutation groups and the direct product operation of the ***,as a special application,partial spread codes are researched and a condition of orbit codes with constant distance is given.

关键词： network coding orbit code group action operation spread

Two Constructions of Optimal Cartesian Authentication Codes from Unitary Geometry over Finite Fields

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Acta Mathematicae Applicatae Sinica 2013年第4期29卷 829-836页

作者： Shang-di chen Da-wei ZHAO College of Science Civil Aviation University of China Information Security Center Beijing University of Posts and Telecommunications

Two constructions of cartesian authentication codes from unitary geometry are given in this paper. Their size parameters and their probabilities of successful impersonation attack and successful substitution attack ar... 详细信息

关键词： unitary geometry optimal authentication code finite field

Molecular mechanisms of dietary restriction in aging—insights from Caenorhabditis elegans research

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Science China(Life Sciences) 2015年第4期58卷 352-358页

作者： LAN JianFeng ZHANG Xuan chen di MOE Key Laboratory of Model Animal for disease Study Model Animal Research Center Nanjing Biomedical Research Institute Nanjing University

dietary restriction(DR) is one of the most robust environmental manipulations that not only extend life span but also delay the onset of age-related diseases in almost every species examined. Caenorhabditis elegans plays an important role in aging studies due to its simple life cycle, easy genetic manipulations and highly conserved genome. Recent studies have demonstrated that the beneficial effects of DR are mediated by the highly conserved transcription factors and signaling pathways in C. elegans. Here we review recent progress in the methodology and molecular mechanisms of DR using C. elegans as a model, as well as prospects for future research.

关键词： C. elegans dietary restriction aging TOR pathway insulin/IGF-1 signaling