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1. chinaXiv:202002.00021 [pdf]

关于新型冠状病毒感染人数的预测研究

吴宇宸
Subjects: Mathematics >> Mathematics (General)

2019年12月,新型冠状病毒肺炎(NCP,又称2019-nCoV)疫情从武汉开始爆发,几天内迅速传播到全国乃至海外,对我国的工农业生产和人民生活产生了重要影响。科学有效掌控疫情发展对疫情防控至关重要。本文基于中国卫健委及湖北省卫健委每日公布的累计确诊数,采用逻辑斯蒂模型对数据进行了拟合,以期给该疾病的防控治提供科学依据。通过公布的疫情数据,我们反演了模型的参数,进而有效地模拟了目前疫情的发展,并预测了疫情未来的趋势。我们预测,湖北省疫情还要持续至少2周,而在全国其他地区,疫情可望1周左右达到顶峰。

submitted time 2020-02-18 Hits758Downloads310 Comment 0

2. chinaXiv:202001.00045 [pdf]

Approximation-Degree-Based Interpolation: A New Interpolation Method

廉师友
Subjects: Mathematics >> Numerical Analysis

This paper introduces the measure of approximate-degree and the concept of approximate-degree function between numerical values, thus developing a new interpolation method —— approximation-degree-based interpolation, i.e., AD interpolation. One-dimensional AD interpolation is done directly by using correlative interpolation formulas; n(n>1)-dimensional AD interpolation is firstly separated into n parallel one-dimensional AD interpolation computations to do respectively, and then got results are synthesized by Sum-Times-Difference formula into a value as the result value of the n-dimensional interpolation. If the parallel processing is used, the efficiency of n-dimensional AD interpolation is almost the same as that of the one-dimensional AD interpolation. Thus it starts a feasible and convenient approach and provides an effective method for high-dimensional interpolations. Furthermore, if AD interpolation is introduced into machine learning, a new instance-based learning method is expected to be realized.

submitted time 2019-12-29 Hits82Downloads48 Comment 0

3. chinaXiv:201911.00099 [pdf]

滑动均值聚类

何沧平; 孟令霞
Subjects: Mathematics >> Computational Mathematics.

本文提出一个名为滑动均值的聚类算法,尝试替代常用的k均值算法。滑动均值能处理大量的样本,自行决定类别数量,用混洗样本来避免出现很差的中心点,能够中途裁减类别数量,聚类效果显著好于k均值。在鸢尾花数据和手写数字数据上,滑动均值的聚类效果比k均值分别高9.93%和5.17%。

submitted time 2019-11-26 Hits1661Downloads271 Comment 0

4. chinaXiv:201911.00094 [pdf]

Copositivity for 3rd order symmetric tensors and applications

刘佳蕊; 宋义生
Subjects: Mathematics >> Mathematical Physics

The strict opositivity of 4th order symmetric tensor may apply to detect vacuum stability of general scalar potential. For finding analytical expressions of (strict) opositivity of 4th order symmetric tensor, we may reduce its order to 3rd order to better deal with it. So, it is provided that several analytically sufficient conditions for the copositivity of 3th order 2 dimensional (3 dimensional) symmetric tensors. Subsequently, applying these conclusions to 4th order tensors, the analytically sufficient conditions of copositivity are proved for 4th order 2 dimensional and 3 dimensional symmetric tensors. Finally, we apply these results to present analytical vacuum stability conditions for vacuum stability for $\mathbb{Z}_3$ scalar dark matter.

submitted time 2019-11-23 Hits1425Downloads181 Comment 0

5. chinaXiv:201910.00071 [pdf]

Sparse Representation Based Efficient Radiation Symmetry Analysis Method for Cylindrical Model of Inertial Confinement Fusion

张雁峰
Subjects: Mathematics >> Modeling and Simulation

Radiation symmetry evaluation is critical to the laser driven Inertial Confinement Fusion (ICF), which is usually done by solving a view-factor equation model. The model is nonlinear, and the number of equations can be very large when the size of discrete mesh element is very small to achieve a prescribed accuracy, which may lead to an intensive equation solving process. In this paper, an efficient radiation symmetry analysis approach based on sparse representation is presented, in which, 1) the Spherical harmonics, annular Zernike polynomials and Legendre-Fourier polynomials are employed to sparsely represent the radiation flux on the capsule and cylindrical cavity, and the nonlinear energy equilibrium equations are transformed into the equations with sparse coefficients, which means there are many redundant equations, 2) only a few equations are selected to recover such sparse coefficients with Latin hypercube sampling, 3) a Conjugate Gradient Subspace Thresholding Pursuit (CGSTP) algorithm is then given to rapidly obtain such sparse coefficients equation with as few iterations as possible. Finally, the proposed method is validated with two experiment targets for Shenguang II and Shenguang III laser facility in China. The results show that only one tenth of computation time is required to solve one tenth of equations to achieve the radiation flux with comparable accuracy. Further more, the solution is much more efficient as the size of discrete mesh element decreases, in which, only 1.2% computation time is required to obtain the accurate result.

submitted time 2019-10-23 Hits1315Downloads105 Comment 0

6. chinaXiv:201910.00074 [pdf]

基于线性模型平均估计的置信区间

王苗苗
Subjects: Mathematics >> Statistics and Probability

已有的关于模型平均估计渐近分布理论的研究多是基于局部误设定的假设,[1] 是其中开创性的且最著名的文章之一. 虽然利用局部误设定的假设可以证明模型平均估计渐近分布理论, 但是 [2] 等对此假设提出了不合理性质疑和解释. 本文我们研究[1]中的置信区间估计方法. 证明了在一般参数设定下, 虽然 [1]中的渐近分布理论不一定成立, 但是关于不确定参数的线性函数的置信区间在正态分布误差、线性回归模 型下是有效的, 即置信区间的覆盖率趋于预设定的名义水平. 我们通过模拟研究进一步验证了理论结果.

submitted time 2019-10-14 Hits807Downloads125 Comment 0

7. chinaXiv:201909.00015 [pdf]

Analytical expressions of copositivity for 4th order symmetric tensors and applications

宋义生; 祁力群
Subjects: Mathematics >> Control and Optimization.

In particle physics, scalar potentials have to be bounded from below in order for the physics to make sense. The precise expressions of checking lower bound of scalar potentials are essential, which is an analytical expression of checking copositivity and positive definiteness of tensors given by such scalar potentials. Because the tensors given by general scalar potential are 4th order and symmetric, our work mainly focuses on finding precise expressions to test copositivity and positive definiteness of 4th order tensors in this paper. First of all, an analytically sufficient and necessary condition of positive definiteness is provided for 4th order 2 dimensional symmetric tensors. For 4th order 3 dimensional symmetric tensors, we give two analytically sufficient conditions of (strictly) cpositivity by using proof technique of reducing orders or dimensions of such a tensor. Furthermore, an analytically sufficient and necessary condition of copositivity is showed for 4th order 2 dimensional symmetric tensors. We also give several distinctly analytically sufficient conditions of (strict) copositivity for 4th order 2 dimensional symmetric tensors. Finally, we apply these results to check lower bound of scalar potentials, and to present analytical vacuum stability conditions for potentials of two real scalar fields and the Higgs boson.

submitted time 2019-08-30 Hits339Downloads176 Comment 0

8. chinaXiv:201908.00121 [pdf]

一中求解特征值问题的广义共轭梯度算法

谢和虎; 张宁; 李瑜; 徐然; 游春光
Subjects: Mathematics >> Computational Mathematics.

本文基于阻尼块反幂法与子空间投影算法设计了一种求解特征值问题的广义共轭梯度算法, 同时也实现了相应的计算软件包. 然后对算法和计算过程进行了一系列的优化来提高算法的稳定性、计算效率和并行可扩展性, 使得本文的算法适合在并行计算环境下求解大规模稀疏矩阵的特征值. 所形成的软件包是基于Matrix-Free和Vector-Free设计的, 可以应用于任意的矩阵向量结构. 针对几种典型矩阵的测试结果表明本文的算法和软件包不但具有良好的数值稳定性, 同时相比于SLEPc软件包中的LOBPCG以及Jacobi-Davidson解法器有2-6倍的效率提升. 软件包的网址: https://github.com/pase2017/GCGE-1.0.

submitted time 2019-08-27 Hits982Downloads237 Comment 0

9. chinaXiv:201705.00826 [pdf]

Relative Entropy Minimizing-Based Theory of Intelligent Systems

Xi, Guangcheng
Subjects: Mathematics >> Statistics and Probability

Based on the point of view of neuroethology and cognition-psychology, general frame of theory for intelligent systems is presented by means of principle of relative entropy minimizing in this paper. Cream of the general frame of theory is to present and to prove basic principle of intelligent systems: entropy increases or decreases together with intelligence in the intelligent systems. The basic principle is of momentous theoretical significance and practical significance .From the basic principle can not only derive two kind of learning algorithms (statistical simulating annealing algorithms and annealing algorithms of mean-field theory approximation) for training large kinds of stochastic neural networks,but also can thoroughly dispel misgivings created by second law of thermodynamics on 'peoplespsychology ,hence make one be fully confident of facing life.Because of Human society, natural world, and even universe all are intelligent systems.

submitted time 2019-07-21 Hits2517Downloads1077 Comment 0

10. chinaXiv:201907.00015 [pdf]

一道工序智能加工系统 RGV 调度模型

周伟刚; 冯倩倩
Subjects: Mathematics >> Applied Mathematics

研究了一道工序智能加工系统轨道式自动引导车(RGV)调度问题. 该问题为2018年全国大学生数学建模竞赛B题的一部分. 系统由一辆轨道式自动引导车和若干台计算机数控机床(CNC)等部件组成, RGV操控多台CNC完成多个物料加工, RGV调度方案决定了系统的效率. 以 RGV的移动路径为决策变量, 以RGV在CNC上的操作结束时刻为时间节点, 以物料加工剩余时间为状态变量, 给出了问题的数学模型, 但模型中的部分参数以决策变量为下标. 通过定义新的变量和约束, 将模型修改为不含变量下标和分段函数的非线性混合整数规划模型. 最后给出了算例, 说明了模型的正确性和可操作性.

submitted time 2019-07-16 Hits3501Downloads277 Comment 0

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