Stability and stabilization of impulsive switched system with inappropriate impulsive switching signals under asynchronous switching

The main objective of this paper is to study the stability and stabilization problems for a class of impulsive switched systems with inappropriate impulsive switching signals under asynchronous switching. Here, “inappropriate” means that the impulse jump moment may be inconsistent with the asynchronous switching moment or the system switching moment. And “asynchronous” implies that the switching of controller modes lags behind that of system modes. The hybrid case of stable or unstable subsystems combining with stable and unstable impulses is explored. A novel Lyapunov-like function is constructed, which is discontinuous at some special instants, including the switching instants, the instants when the system modes and filter modes are matched, and the impulse jump instants. Based on the novel multiple Lyapunov-like function, the sufficient conditions for the closed loop system to be globally uniformly exponentially stable (GUES) are obtained with admissible edge-dependent switching signals. Furthermore, by excogitating the state-feedback switching controller, the gain matrix of the controller can be obtained by solving the linear matrix inequalities. Finally, two numerical examples and simulation results are given to prove the effectiveness of our main results.     

Gas Chromatographic Analysis in the Synthesis of Poly (Ethylene Oxide) Dimethyl Ethers

ABSTRACT

Gas chromatography (GC) was used in the analysis of the synthesized oligomeric mixtures, involving poly(ethylene glycol)s, poly(ethylene oxide) monomethyl ethers, poly(ethylene oxide) dimethyl ethers and crown ethers. It was demonstrated that the samples could be successfully analyzed on the wide bore capillary column with cross-linked polar stationary phase (FFAP) without derivatization. An on-column injection technique is used to avoid possible sample distortion. Identification and quantitative analysis were achieved taking advantage of the GC homologues retention rule and the FID effective carbon number response rule, thus the limitations of some standard availability and purity problems were avoided. Much useful information such as average molecular weight, polydisperse distribution and so on were obtained by the established method, which is very important in the process monitoring and product quality control.     

Convergence and error estimation in free energy calculations using the weighted histogram analysis method

The weighted histogram analysis method (WHAM) has become the standard technique for the analysis of umbrella sampling simulations. In this article, we address the challenges (1) of obtaining fast and accurate solutions of the coupled nonlinear WHAM equations, (2) of quantifying the statistical errors of the resulting free energies, (3) of diagnosing possible systematic errors, and (4) of optimally allocating of the computational resources. Traditionally, the WHAM equations are solved by a fixed-point direct iteration method, despite poor convergence and possible numerical inaccuracies in the solutions. Here, we instead solve the mathematically equivalent problem of maximizing a target likelihood function, by using superlinear numerical optimization algorithms with a significantly faster convergence rate. To estimate the statistical errors in one-dimensional free energy profiles obtained from WHAM, we note that for densely spaced umbrella windows with harmonic biasing potentials, the WHAM free energy profile can be approximated by a coarse-grained free energy obtained by integrating the mean restraining forces. The statistical errors of the coarse-grained free energies can be estimated straightforwardly and then used for the WHAM results. A generalization to multidimensional WHAM is described. We also propose two simple statistical criteria to test the consistency between the histograms of adjacent umbrella windows, which help identify inadequate sampling and hysteresis in the degrees of freedom orthogonal to the reaction coordinate. Together, the estimates of the statistical errors and the diagnostics of inconsistencies in the potentials of mean force provide a basis for the efficient allocation of computational resources in free energy simulations.     

一种改进的随机Hough变换检测圆的方法

针对随机Hough变换检测圆准确率低的问题,提出了一种改进的随机Hough变换算法.算法利用原标准随机Hough变换的检测结果,确定出合适的阈值,将检测结果中平均误差超过此阈值的圆视为错检圆,并将这些圆上的点取出,重新进行随机Hough变换,直到正确检测出所有圆.模拟数据和真实图像的数值实验都表明改进算法的检测准确率明显提高.     

带导数的求积公式在一重积分Wiener空间下的平均误差

讨论了利用积分中值定理当积分区间趋于零时中间点的渐进位置作为相应的节点构造的带有导数的求积公式,在一重积分Wiener测度空间的平均逼近误差.     

相依随机序列加权和滑动平均的若干小偏差定理

引入随机序列滑动似然比作为任意二值随机序列相对于Bernoulli分布的独立随机变量序列偏差的一种随机性度量,通过滑动相对熵给出了样本空间的一个子集.在此子集上得到了一类关于随机序列滑动平均的用不等式表示的强极限定理,即小偏差定理,推广了文献[5],[6]等关于随机序列算术平均的结果,这些结果蕴含近期诸多文献的主要结果.     

三角模糊数直觉模糊PA算子及其应用

针对决策信息为三角模糊数直觉模糊数（TFNIFN）且属性间存在相互关联的多属性群决策（MAGDM）问题,提出了一种基于三角模糊数直觉模糊PA （TFNIFPA）算子的决策方法.首先,基于TFNIFN的运算法则和PA （Power Average）算子,定义了TFNIFPA算子.然后,研究了该算子的一些性质,建立基于TFNIFPA算子的MAGDM模型,结合排序方法进行决策.最后通过MAGDM算例验证了该算子的有效性与可行性.     

Multi-mode resource availability cost problem with recruitment and release dates for resources

This paper investigates the multi-mode resource availability cost problem with recruitment and release dates for resources. This problem is a more realistic model and extended case of the resource availability cost problem. The project contains activities interrelated by finish–start precedence relations with zero time lags, which require a set of renewable resources. First, a mixed integer programming formulation is proposed for the problem. Then, simulated annealing (SA) algorithm is proposed to obtain a satisfying solution for this NP-hard problem. The effectiveness of the proposed algorithm is demonstrated through comprehensive experimentation based on 300 test problems. The results are analyzed and discussed.     

2‐Distance Coloring of Sparse Graphs

For graphs of bounded maximum average degree, we consider the problem of 2‐distance coloring, that is, the problem of coloring the vertices while ensuring that two vertices that are adjacent or have a common neighbor receive different colors. We prove that graphs with maximum average degree less than and maximum degree Δ at least 4 are 2‐distance ‐colorable, which is optimal and improves previous results from Dolama and Sopena, and from Borodin et al. We also prove that graphs with maximum average degree less than (resp. , ) and maximum degree Δ at least 5 (resp. 6, 8) are list 2‐distance ‐colorable, which improves previous results from Borodin et al., and from Ivanova. We prove that any graph with maximum average degree m less than and with large enough maximum degree Δ (depending only on m) can be list 2‐distance ‐colored. There exist graphs with arbitrarily large maximum degree and maximum average degree less than 3 that cannot be 2‐distance ‐colored: the question of what happens between and 3 remains open. We prove also that any graph with maximum average degree can be list 2‐distance ‐colored (C depending only on m). It is optimal as there exist graphs with arbitrarily large maximum degree and maximum average degree less than 4 that cannot be 2‐distance colored with less than colors. Most of the above results can be transposed to injective list coloring with one color less.