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New Cutting Force Modeling Approach for Flat End Mill

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Chinese Journal of Aeronautics 2007年第3期20卷 282-288页

作者： WAN Min ZHANG Wei-hong TAN Gang QIN Guo-hua sino-french laboratory of Concurrent Engineering The Key Laboratory of Contemporary Design ＆ Integrated Manufacturing Technology Northwestern Polytechnical University Xi＇an 710072 China

A new mechanistic cutting force model for flat end milling using the instantaneous cutting force coefficients is proposed. An in-depth analysis shows that the total cutting forces can be separated into two terms: a nominal component independent of the runout and a perturbation component induced by the runout. The instantaneous value of the nominal component is used to calibrate the cutting force coefficients. With the help of the perturbation component and the cutting force coefficients obtained above, the cutter runout is identified. Based on simulation and experimental results, the validity of the identification approach is demonstrated. The advantage of the proposed method lies in that the calibration performed with data of one cutting test under a specific regime can be applied for a great range of cutting conditions.

关键词： runout cutting force flat end mill calibration cutting force coefficient

Roll-pitch-yaw autopilot design for nonlinear time-varying missile using partial state observer based global fast terminal sliding mode control

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Chinese Journal of Aeronautics 2016年第5期29卷 1302-1312页

作者： Ahmed Awad Wang Haoping sino-french International Joint laboratory of Automatic Control and Signal Processing (LaFCAS) School of AutomationNanjing University of Science & Technology

The acceleration autopilot design for skid-to-turn （STT） missile faces a great challenge owing to coupling effect among planes, variation of missile velocity and its parameters, inexistence of a complete state vector, and nonlinear aerodynamics. Moreover, the autopilot should be designed for the entire flight envelope where fast variations exist. In this paper, a design of integrated roll-pitch-yaw autopilot based on global fast terminal sliding mode control （GFTSMC） with a partial state nonlinear observer （PSNLO） for STT nonlinear time-varying missile model, is employed to address these issues. GFTSMC with a novel sliding surface is proposed to nullify the integral error and the singularity problem without application of the sign function. The proposed autopilot consisting of two-loop structure, controls STT maneuver and stabilizes the rolling with a PSNLO in order to estimate the immeasurable states as an output while its inputs are missile measurable states and control signals. The missile model considers the velocity variation, gravity effect and parameters＇ variation. Furthermore, the environmental conditions＇ dynamics are mod- eled. PSNLO stability and the closed loop system stability are studied. Finally, numerical simulation is established to evaluate the proposed autopilot performance and to compare it with existing approaches in the literature.

关键词： Flight control system Global fast terminal slidingmode control Integrated autopilot Nonlinear state observer Skid-to-turn missile

Matching CCD images to a stellar catalog using locality-sensitive hashing

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Research in Astronomy and Astrophysics 2018年第2期18卷 105-114页

作者： Bo Liu Jia-Zong Yu Qing-Yu Peng College of Information Science and Technology Jinan University sino-french Joint laboratory for Astrometry Dynamics and Space Science Jinan University

The usage of a subset of observed stars in a CCD image to find their corresponding matched stars in a stellar catalog is an important issue in astronomical research. Subgraph isomorphic-based algorithms are the most widely used methods in star catalog matching. When more subgraph features are provided, the CCD images are recognized better. However, when the navigation feature database is large, the method requires more time to match the observing model. To solve this problem, this study investigates further and improves subgraph isomorphic matching algorithms. We present an algorithm based on a locality-sensitive hashing technique, which allocates quadrilateral models in the navigation feature database into different hash buckets and reduces the search range to the bucket in which the observed quadrilateral model is located. Experimental results indicate the effectivity of our method.

关键词： astronomical databases: miscellaneous -- methods: data analysis -- techniques: imageprocessing

Simple Reconstruction of Tree Branches from a Single Range Image

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Journal of Computer Science & Technology 2007年第6期22卷 846-858页

作者：程章林张晓鹏陈宝权 sino-french laboratory LIAMA Institute of AutomationChinese Academy of Sciences Digital Technology Center University of MinnesotaMinneapolisMN 55455U.S.A.

3D modeling of trees in real environments is a challenge in computer graphics and computer vision, since the geometric shape and topological structure of trees are more complex than conventional artificial objects. In this paper, we present a multi-process approach that is mainly performed in 2D space to faithfully construct a 3D model of the trunk and main branches of a real tree from a single range image. The range image is first segmented into patches by jump edge detection based on depth discontinuity. Coarse skeleton points and initial radii are then computed from the contour of each patch. Axis directions are estimated using cylinder fitting in the neighborhood of each coarse skeleton point. With the help of axis directions, skeleton nodes and corresponding radii are computed. Finally, these skeleton nodes are hierarchically connected, and improper radii are modified based on plant knowledge. 3D models generated from single range images of real trees demonstrate the effectiveness of our method. The main contributions of this paper are simple reconstruction by virtue of image storage order of single scan and skeleton computation based on axis directions.

关键词： cylinder fitting generalized circular cylinder skeleton tree branch modeling

Reduced-order method for nuclear reactor primary circuit calculation

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Nuclear Science and Techniques 2024年第11期35卷 28-45页

作者： Ze-Long Zhao Ya-Hui Wang Zhe-Xian Liu Hong-Hang Chi Yu Ma sino‑french Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

Accurate real-time simulations of nuclear reactor circuit systems are particularly important for system safety analysis and *** effectively improve computational efficiency without reducing accuracy,this study establishes a thermal-hydraulics reduced-order model(ROM)for nuclear reactor circuit *** full-order circuit system calculation model is first established and verified and then used to calculate the thermal-hydraulic properties of the circuit system under different states as *** proper orthogonal decomposition method is used to extract the basis functions from snapshots,and the ROM is constructed using the least-squares method,effectively reducing the difficulty in constructing the ROM.A comparison between the full-order simulation and ROM prediction results of the AP1000 circuit system shows that the proposed ROM can improve computational efficiency by 1500 times while achieving a maximum relative error of 0.223%.This research develops a new direction and perspective for the digital twin modeling of nuclear reactor system circuits.

关键词： Reactor system model Primary circuit Reduced-order Proper orthogonal decomposition Least-squares method

Fast Construction of Plant Architectural Models Based on Substructure Decomposition

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Journal of Computer Science & Technology 2003年第6期18卷 780-787页

作者：严红平 Philippe de Reffye 潘春洪胡包钢 National laboratory of Pattern Recognition Institute of Automation The Chinese Academy of Sciences Beijing 100080 P.R. China Sino-French Laboratory of Information Mathematics and Automation Institute of Automation The Chinese Academy of SciencesBe CIRAD Montpellier FranceSino-French Laboratory of Information Mathematics and Automation Institute of Automation The Chinese Academy of Sciences Beijing 100080 P.R. China

Plant structure, representing the physical link among different organs, includes many similar substructures. In this paper, a new method is presented to construct plant architectural models of most plant species. The plant structure is decomposed into a stem, a set of lateral substructures and a terminal substructure, which is called substructure decomposition; then based on substructure decomposition, the plant structures are expressed in an iterative way; and further the derivative formula is employed to compute the number of organs in plant structures to get the geometrical sizes of 3D plant organs by borrowing Hydraulic Model. Using 3D organs, a substructure library is built. Based on the substructures stored in substructure library, one can construct 3D plant structure according to certain topological and geometrical rules. The experiments with different plant species are included in this paper to demonstrate the validity of the new method for constructing plant structures. The experimental results show that the approach follows botanical knowledge with high efficiency in constructing plant structures of most plant species. In addition,this method enables users to check the detail information of plant structure.

关键词： plant structure substructure decomposition fast construction architectural model

Drag reduction of wall bounded incompressible turbulent flow based on active dimples/pimples

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Journal of Hydrodynamics 2017年第2期29卷 261-271页

作者：葛铭纬方乐刘永前 State Key laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University sino-french Engineering School Beihang University

The control of turbulence by dimples/pimples has drawn more and more attention. The objective of this paper is to investigate the effectiveness of the active dimples/pimples for the drag reduction in the incompressible turbulent flow. Firstly, the drag reduction by the opposition control based on active dimples/pimples at the lower wall is studied via the direct numerical simulation of the turbulent channel flow. It is found that large active dimples/pimples can not suppress the streamwise vortices significantly and thus almost no drag reduction is achieved. Small active dimples and pimples with the diameter of one fourth of the streak width can both reduce the friction drag, but pimples will induce a larger pressure drag than dimples. Then the suboptimal control scheme is examined based on small active dimples using the spanwise wall shear information only, It is shown that the friction drag decreases by about 4.5% but the total drag is only reduced by about 2.7% abated by the pressure drag. Compared with the actuation of the all-point blowing/suction or the all-point wall movement, the effectiveness of the turbulent drag reduction based on active shallow dimples is much smaller.

关键词： Turbulent drag reduction active dimple opposition control suboptimal control

Uncertainties of critical temperatures based on higher-order fluctuations of the largest fragment charge

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Chinese Physics C 2024年第1期48卷 110-124页

作者：肖尔熙雷昕黄英格冯玉洁祝龙苏军 sino-french Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

The new signature of liquid-gas phase transition has been well indicated by the higher-order fluctuations of the largest fragment charge,but the uncertainties of critical temperatures based on this signature have not been *** study extracts the critical temperatures of liquid-gas phase transition in nuclear reactions and investigates their *** the isospin-dependent quantum molecular dynamics model in conjunction with the statistical model GEMINI enables us to describe the dynamical path from the initial to the final *** isotope thermometer and a quantum fluctuation thermometer are employed to extract the nuclear *** higher-order fluctuations of the largest fragment charge and critical temperatures are studied in^(124)Sn+^(120)Sn collisions ranging from 400 to 1000 MeV/nucleon and^(124)Sn+AZ collisions at 600 MeV/*** revealed that the pseudo-critical point is robustly indicated by the higher-order fluctuations of the largest fragment *** critical temperatures extracted by the isotope thermometer are relatively consistent,with an uncertainty of 15%,while those obtained by the quantum fluctuation thermometer are heavily influenced by the incident energy and mass number of target *** excitation energy E∗and bound charge Zbound are used for *** two ensembles represent the statistical properties of the initial and final states of the system,*** initial-final correlations of statistical properties might lead to two ***,the size distribution of the largest fragment at the pseudo-critical point based on the Zbound ensemble is wide,while that based on E∗ensemble exhibits bimodality,which is a typical characteristic in the liquid-gas coexistence of a finite ***,the temperature at the pseudo-critical point based on the Zbound ensemble is higher than that based on the E∗***,the projectile-like system exhibits a significant dynamical ef

关键词： liquid-gas phase transition higher-order fluctuations of the largest fragment charge critical temperature initial-final correlations of the statistical properties dynamical path isospin-dependent quantum molecular dynamics

A literature survey on smart cities

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Science China(Information Sciences) 2015年第10期58卷 6-23页

作者： YIN ChuanTao XIONG Zhang CHEN Hui WANG JingYuan COOPER Daven DAVID Bertrand sino-french Engineer School Beihang University Research Institute of Beihang University in Shenzhen School of Computer Science and Engineering Beihang University LIRIS laboratory Ecole Centrale de Lyon

Rapid urbanization creates new challenges and issues, and the smart city concept offers opportunities to rise to these challenges, solve urban problems and provide citizens with a better living environment. This paper presents an exhaustive literature survey of smart cities. First, it introduces the origin and main issues facing the smart city concept, and then presents the fundamentals of a smart city by analyzing its definition and application domains. Second, a data-centric view of smart city architectures and key enabling technologies is provided. Finally, a survey of recent smart city research is presented. This paper provides a reference to researchers who intend to contribute to smart city research and implementation.

关键词： smart city architecture data-centric data vitalization urban data