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The problem of the near-earth asteroids encountering the earth

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Science China Mathematics 2000年第10期43卷 1114-1120页

作者：季江徽刘林 Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China Department of Astronomy Nanjing University Nanjing 210093 China

The asteroids are the most important small bodies in the solar system, while the movement of the near-earth-asteroids (NEAs) is specially concerned by the world. The focus on these asteroids is that they encounter the earth. The orbital evolution of this kind of asteroid is studied by analyzing and comparing them; reasonable dynamical models and corresponding algorithm are given, and the formal numbered NEAs are calculated. The results of the minimal distance.and the very closeapproach time with the earth agree well with those announced by the Minor Planet Center (MPC).

关键词： near-earth asteroids (NEAs) orbital evolution encounter minimal distance.

Approximation Algorithms for Solving Packing Problems of Convex Polygons in Plane

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Science China Mathematics 1993年第1期36卷 100-108页

作者：李庆华鄢勇刘健 Department of Computer Science & Engineering Huazhong University of Science & Technology

The problem of initial collision between convex polygons is studied in detail, and a fast algorithm for finding the embedded depth is obtained, by which the fast approximate algorithm for solving packing problems of c... 详细信息

关键词： convex polygon embedded depth squeezing elastic potential initial collision minimum collision distance.

PERTURBATION FOR ELLIPTIC VARIATIONAL INEQUALITIES

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Science China Mathematics 1991年第6期34卷 650-659页

作者：周叔子 Institute of Applied Mathematics Hunan University Changsha 410082 PRC

In this paper we consider the perturbation problems for linear elliptic variational in equa-lities in Hilbert spaces. A more general sufficient condition for the convergence of perturbedsolution to the original solution is derived and applied to deal with the boundary value pertur-bation problem and two practical variational inequalities.

关键词： variational inequality perturbation Hausdorff distance.

An Interval-valued Fuzzy Competitive Neural Network

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Journal of Donghua University(English Edition) 2006年第6期23卷 137-140页

作者：邓冠男邹开其 College of Information Engineering Dalian University

Because interval value is quite natural in clustering, an interval-valued fuzzy competitive neural network is proposed. Firstly, this paper proposes several definitions of distance.relating to interval number. And then, it indicates the method of preprocessing input data, the structure of the network and the learning algorithm of the interval-valued fuzzy competitive neural network. This paper also analyses the principle of the learning algorithm. At last, an experiment is used to test the validity of the network.

关键词： fuzzy competitive neural network interval value distance.

Nonlinear effects of the finite amplitude ultrasound wave in biological tissues

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Chinese Science Bulletin 2000年第6期45卷 508-512页

作者： Xiaozhou Liu Xiufen Gong Shigong Ye Weiya Zhang Nanjing Univ Inst Acoust State Key Lab Modern Acoust Nanjing 210093 Peoples R China

Nonlinear effects will occur during the transmission of the finite amplitude wave in biological tissues. The theoretical prediction and experimental demonstration of the nonlinear effects on the propagation of the finite amplitude wave at the range of biomedical ultrasound frequency and intensity are studied. Results show that the efficiency factor and effective propagation distance.will decrease while the attenuation coefficient increases due to the existence of nonlinear effects. The experimental results coincided quite well with the theory. This shows that the effective propagation distance.and efficiency factor can be used to describe quantitatively the influence of nonlinear effects on the propagation of the finite amplitude sound wave in biological tissues.

关键词： nonlinear effects efficiency factor effective attenuation coefficient effective propagation distance.

Reliability and Validity of the New Shooting Accuracy Measurement （SAM） System Software

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Journal of Sports Science 2017年第3期5卷 172-177页

The aim of this study was to investigate the reliability and validity of the New Shooting Accuracy Measurement Software （SAMS）. Thirty two male collegian soccer players performed three inner side kicking to the transparent goal construction. A High speed camera was placed at the back of the construction to determine where the ball contacted. Recorded video results were assessed with the SAMS and Kinovea software. To investigate test-retest reliability, three kicking results were examined twice by SAMS. Moreover kicking accuracy results obtained with SAMS were compared with results provided by Kinovea in order to investigate validity. Test-retest reproducibility of the new software was excellent, with Concordance Correlation Coefficient for distance.to target （0.99, 0.99 and 0.99 respectively） and for angular degree of the ball （0.97, 0.99 and 0.99 respectively）, low Coefficients of Variation （between 2.10 to 6.33 for distance.to target and 2.40 to 2.69 for angular degree） and random error （between _.＋ 0.55 to __＋ 3.44 for distance.to target and ___ 0.63 to ___ 2.75 for angular degree）. Constant error （between 0.44 to 1.28 for distance.to target and -1.16 to __. -2.51 for angular degree） and proportional error （between 0.97 to 0.98 for distance.to target and 1.00 to 1.01 for angular degree） were very low for validity. In conclusion, the SAMS represents a valid and reliable instrument to measure accuracy of shooting to target.

关键词： Shooting kicking accuracy measurement distance.

LIFE BLOOMS IN GALAI VILLAGE

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China's Tibet 2022年第4期33卷 4-9页

作者： Li Peng Huang Wenjuan 不详

It was just another April day,and everything living on the snow-covered plateau was beginning to come back to life as it became *** the banks of the Nyangchu River,parallel to the highway known as G318,the peach bloss... 详细信息

关键词：桃花村 distance. mountains

La coopération innovante et pragmatique renforce la relation sino-suisse

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今日中国（法文版） 2022年第8期60卷 46-48页

作者： WANG SHIHTING 不详

《Une connaissance mutuelle permet d'être voisins malgré la distance.》La Chine et la Suisse ont établi des relations diplomatiques le 14 septembre 1950 et la Suisse a été l’un des premiers pays occidentaux à... 详细信息

关键词： des distance. relation

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英语动名词和现在分词辨析

西北民族大学学报（哲学社会科学版） 1995年第1期 104-106页

作者：吴琛

英语动名词和现在分词辨析吴琛英语动名词和现在分词形式上一样，它们都能在一个句子中作定词、作表语，都能构成复合结构，这样，出现在一个句子中的ｖ－ｉｎｇ形式，是动名词还是现在分词？它承担句子中的什么成分？有时，很难辨认，... 详细信息

英语动名词和现在分词辨析吴琛英语动名词和现在分词形式上一样，它们都能在一个句子中作定词、作表语，都能构成复合结构，这样，出现在一个句子中的ｖ－ｉｎｇ形式，是动名词还是现在分词？它承担句子中的什么成分？有时，很难辨认，这是英语学习的难点之一，为便于准确...

关键词： Non-Euclidean cirde and distance.

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