基于EMD方法的混沌信号中周期分量的提取

提出一种从Duffing振子产生的混沌信号中提取谐波分量的方法．依据任何信号由不同的固有简单振动模态组成的概念,利用经验模式分解（EMD）方法,将混沌信号分离为不同的内在模态函数(IMF),并在特定参数下从中分解出单一频率成分的谐波信号,从而成功地将混沌信号和谐波分量分离．仿真实验都表明该方法非常有效．     

基于EMD及非平稳性度量的趋势噪声分解方法

该文结合非平稳性度量,研究利用经验模态分解算法进行趋势噪声分解,提出基于非平稳性度量的准则来判定舍弃的本性模态函数的数目.通过数值模拟证明了该准则克服了连续均方误差准则的缺陷,在不同噪声强度和复杂趋势下,都能够达到很好的去噪效果.     

西部省区经济差距的发展动态与波动机制——基于EMD方法的多尺度分析

本文采用经验模态分解(EMD)方法,对西部12省区1952-2009年经济差距的发展动态进行多尺度分析,并从三次产业发展的角度剖析经济差距波动的生成机制。研究结果表明,西部省区经济差距发展的阶段性特征十分显著:在整个样本研究期间呈现出明显的N;;型曲线特征,而上世纪70年代以来则表现为U型曲线;区域经济差距的波动分别以准周期约为60年的长期趋势、准周期约为25年的中期尺度分量和9.5年的短期尺度分量为主,近期区域经济差距呈扩大趋势。三次产业的地区不平衡发展是导致经济差距波动的重要动因。据此文章从产业驱动、区域协作和宏观调控等方面提出了促进区域经济协调发展的政策建议。     

基于遗传算法和模拟退火的插值马氏模型用于真核生物启动子识别

启动子识别是生物信息学领域极具挑战的问题.本文在IMC(Interpolated Markov Chin)的框架下考虑碱基的插入与缺失,采用SA(Simulated Annealing)训练转移概率,以增加模型的鲁棒性,利用GA(Genetic Algorithm)优化IMC插值系数,以克服梯度算法易于陷入局部极值点的缺陷,最后将该模型用于启动子识别,识别率在测试集达到86%.     

基于L-M算法的电压互感器状态监测

电力系统发展中,互感器的运行管理相对注重长周期的检测,缺乏完整的安全监测与运行状态评估体系,从而导致因互感器异常而出现偏差的结果.因此,从数据的角度对互感器的测量数据进行挖掘与探索,将已经得到的测量数据通过潮流计算方程,利用L-M算法计算出对应的状态评估数据;而后利用一段时期的历史状态评估数据以及测量数据之间的误差关系,做出误差分析与判断,得到目标互感器的系统误差与随机误差,实现互感器监测与评估的整个过程.     

基于EMD-GA-BP与EMD-PSO-LSSVM的中国碳市场价格预测

由于碳交易市场价格的波动性大及相互影响关系的复杂性,本文试图构建碳价格长期和短期的最优预测模型。考虑到碳交易价格波动的趋势性和周期性特点,基于经验模态分解算法(EMD)、遗传算法(GA)—神经网络(BP)模型、粒子群算法(PSO)—最小二乘支持向量机(LSSVM)模型及由它们构建的组合预测模型,对中国碳市场交易价格进行短期预测和长期预测。实证分析中将影响碳交易价格的不同宏观经济因素和碳价格时间序列因素做为输入变量,分别代入组合模型进行预测。研究结果表明,在短期预测中,EMD-GA-BP模型预测效果优于GA-BP模型和PSO-LSSVM模型;而在长期预测中,组合模型EMD-PSO-LSSVM模型预测效果优于只考虑碳价格波动趋势性或周期性预测效果。     

Constant Sign and Sign Changing Solutions for Systems of Quasilinear Elliptic Equations

We establish the existence of two opposite constant sign solutions for a general noncoercive quasilinear elliptic system with homogeneous Dirichlet boundary conditions. In the case where the system has a variational structure, by strengthening the hypotheses, we obtain a third nontrivial solution which is sign changing in the sense that one cannot have both components of the new solution of the same constant sign. Our approach relies on a suitable method of sub-supersolutions combined with truncation and variational arguments that does not require a subcritical growth condition.     

Sign patterns for eigenmatrices of nonnegative matrices

For a square (0,?1,??1) sign pattern matrix S, denote the qualitative class of S by Q(S). In this article, we investigate the relationship between sign patterns and matrices that diagonalize an irreducible nonnegative matrix. We explicitly describe the sign patterns S such that every matrix in Q(S) diagonalizes some irreducible nonnegative matrix. Further, we characterize the sign patterns S such that some member of Q(S) diagonalizes an irreducible nonnegative matrix. Finally, we provide necessary and sufficient conditions for a multiset of real numbers to be realized as the spectrum of an irreducible nonnegative matrix M that is diagonalized by a matrix in the qualitative class of some S ² NS sign pattern.     

Sign Regularity Conditions for Discontinuous Boundary-Value Problems

For a multipoint discontinuous boundary-value problem with nonoscillating differential operator, we present an analog of the Kalafati conditions that ensure the sign regularity property, i.e., the property that the number of sign changes of the solution does not exceed the number of sign changes of the function on the right-hand side. The sign regularity property allows one to verify whether the spectrum of the corresponding spectral problem exhibits the Sturm properties (i.e., the reality, positiveness, and simplicity of eigenvalues, the alternation of zeros of eigenfunctions, etc.).     

Sign solvable graphs

A class of signed digraphs which arises naturally, in the theory of sign solvable linear systems is introduced. Several results are obtained concerning the structure of such graphs. Also an application is made revealing much of the structure of matrices of sign-solvable systems.     

Optimal Potentials for Problems with Changing Sign Data

The main purpose of this paper is to study the duality and penalty method for a constrained nonconvex vector optimization problem. Following along with the image space analysis, a Lagrange-type duality for a constrained nonconvex vector optimization problem is proposed by virtue of the class of vector-valued regular weak separation functions in the image space. Simultaneously, some equivalent characterizations to the zero duality gap property are established including the Lagrange multiplier, the Lagrange saddle point and the regular separation. Moreover, an exact penalization is also obtained by means of a local image regularity condition and a class of particular regular weak separation functions in the image space.     

Sign (di)lemma for dimension shifting

There is a surprising occurrence of some minus signs in the isomorphisms produced in the well-known technique of dimension shifting in calculating derived functors in homological algebra. We explicitly determine these signs. Getting these signs right is important in order to avoid basic contradictions. We illustrate the result − which we call as the sign lemma for dimension shifting − by some de Rham cohomology and Chern class considerations for compact Riemann surfaces.     

Sign balance for finite groups of Lie type

A product formula for the parity generating function of the number of 1’s in invertible matrices over is given. The computation is based on algebraic tools such as the Bruhat decomposition. It is somewhat surprising that the number of such matrices with odd number of 1’s is greater than the number of those with even number of 1’s. The same technique can be used to obtain a parity generating function also for symplectic matrices over . We present also a generating function for the sum of entries of matrices over an arbitrary finite field calculated in . The Mahonian distribution appears in these formulas.     

Computing stable loads for pallets

This paper describes an Integer Programming model for generating stable loading patterns for the Pallet Loading Problem under several stability criteria. The results obtained during evaluation show great improvement in the number of stable patterns in comparison with results reported earlier. Moreover, most of the solved cases also ensure optimality in terms of utilization of a pallet.