基于变差函数全局纹理增强的结构相似度图像质量评价

为解决结构相似度算法的图像质量评价缺陷,提出了一种基于变差函数全局纹理增强的结构相似度图像质量评价。该方法首先利用改进的对数变差函数模型提取原图像和失真图像在水平0°、垂直90°和对角45°、135°四个方向的纹理信息特征,然后分别求出对应的纹理增强图像,最后改进SSIM中的结构信息来确定纹理区域的明显失真,计算得到整幅图像的VSSIM值。目前大多数的全参考评价方法不能对数据库中的所有失真类型进行评价,只能对某一类固定的失真类型来评价。本方法对LIVE数据库中的五种失真类型都适用,仿真实验表明,该算法对五种不同失真类型的评价结果具有一定的合理性,并且与主观评价数据库较为一致,其性能也优于其他质量评价模型。     

Gain‐scheduled filtering for linear parameter‐varying systems using inexact scheduling parameters with bounded variation rates

This paper is concerned with the problem of full‐order H₂ linear parameter‐varying filter design for continuous‐time systems with bounded rate of variations under the condition that the scheduling parameters do not exactly fit the real ones. The scheduling parameters and their derivatives are supposed to belong to polytopes with known vertices. The synthesis conditions are formulated in terms of parameter‐dependent bilinear matrix inequalities by means of parameter‐dependent Lyapunov function and introducing some extra variables for the filter design. An iterative procedure is presented to cast the bilinear matrix inequalities problem into a linear matrix inequality optimization problem. The design of robust filters for both time‐varying and time‐invariant systems can be viewed as particular cases of the proposed method. The merit of the method presented in this paper lies in two fields. The first pertains to dealing with the measurement uncertainty in a less conservative manner than available approaches in the gain‐scheduled filtering problem. The second is to provide more efficient methods than the existing ones in the literature for the robust filter design. Copyright © 2015 John Wiley & Sons, Ltd.     

消除halo效应和色彩失真的去雾算法

目的 雾天条件下采集的图像存在低对比度和低场景可见度的问题,传统的去雾算法易产生halo效应和色彩失真问题。为此,结合大气散射光特性提出一种基于相对总变差的图像复原方法。方法 首先从大气散射光与纹理信息无关的角度出发,利用相对总变差分离图像主结构和图像纹理信息准确估计大气耗散函数,通过引入一个自适应保护因子来避免复原图像的色彩失真问题,最后由大气散射模型计算复原图像并进行图像的亮度调整,得到一幅清晰无雾的图像。结果 通过与经典的去雾算法比较,表明该方法可以有效避免halo效应和天空颜色失真等不足,并且在图像的深度突变处也能得到很好的去雾效果。结论 实验表明该算法的场景适应能力较强,时间复杂度与图像的大小成线性关系,相比于前人的算法在计算速度上有一定的提高。     

山西省近50年风速变化及突变特征分析

利用线性拟合、M-K方法对山西省22个气象观测站1960—2010年的逐日风速资料进行了倾向、突变、逐年代变化等特征分析。研究表明,近50年来山西省平均风速存在明显的下降趋势,平均风速由20世纪60年代的2.16 m/s下降到21世纪初的1.86 m/s;不同时间段呈现不同的变化特征,1979—1989年风速出现显著下降,年均递减率达到0.046 m/s,变率远超出其他时段;对近50年山西省平均风速进行M-K检验后发现,在1982年出现明显的突变点。山西省四季平均风速均呈下降趋势,四季风速下降速率最快的为春季,冬季次之,夏季风速下降速率最慢。同样,四季风速均发生突变,突变时间点分布在1980—1985年间。除8月外,山西省各个月份风速也呈下降趋势,且均出现突变现象。     

Optimal Control of Switching Times in Switched Stochastic Systems

In this paper, we solve an optimal control problem for switched stochastic systems using calculus of variations, where the objective is to minimize a cost functional defined on the state and the switching times are the sole control variables. In particular, we focus on the problem in which a pre‐specified sequence of active subsystems is given. For one switching time case, the derivative of the cost functional with respect to the switching time is derived, which has an especially simple form and can be directly used in gradient descent algorithms to locate the optimal switching instant. Then, we propose an approach to deal with the problem with multi‐switching times case. Finally, two numerical examples are given, highlighting the viability and advantages of the proposed methodology.     

Mbius-invariant curve and surface energies and their applications

Curvature-based surface energies are frequently used in mathematics, physics, thin plate and shell engineering, and membrane chemistry and biology studies. Invariance under rotations and shifts makes curvature-based energies very attractive for modeling various phenomena. In computer-aided geometric design, the Willmore surfaces and the so-called minimum variation surfaces （MVS） are widely used for shape modeling purposes. The Willmore surfaces are invariant w.r.t conformal transformations （Mbius or conformal invariance）, and studied thoroughly in differential geometry and related disciplines. In contrast, the minimum variation surfaces are not conformal invariant. In this paper, we suggest a simple modification of the minimum variation energy and demonstrate that the resulting modified MVS enjoy Mbius invariance （so we call them conformal-invariant MVS or, shortly, CI-MVS）. We also study connections of CI-MVS with the cyclides of Dupin. In addition, we consider several other conformal-invariant curve and surface energies involving curvatures and curvature derivatives. In particular, we show how filtering with a conformal-invariant curve energy can be used for detecting salient subsets of the principal curvature extremum curves used by Hosaka and co-workers for shape quality inspection purposes.     

Almost strictly total positivity of NUAT B-spline basis

Total positivity of spline basis has been well known in the theory of computer aided geometry design, which is highly related with good shape preserving property. Almost strictly total positivity is stronger, which could determine the positive minors while the other is zero. In this paper, a geometrical approach is proposed to prove the collection matrices of NUAT B-spline basis are almost strictly totally positive. In this paper, knot insertion algorithm combined with coefficient variation of NUAT B-spline function, we put forward an intuitive and geometrical method.     

Molecular interaction networks in the analyses of sequence variation and proteomics data

Protein–protein interaction networks are typically generated in standard cell lines or model organisms as it is prohibitively difficult to record large interaction datasets from specific tissues or disease models at a reasonable pace. Although the interaction data are of high confidence, they thus do not reflect in vivo relationships as such. A wealth of physiologically relevant protein information, obtained under different conditions and from different systems, is available including information on genetic variation, protein levels, and PTMs. However, these data are difficult to assess comprehensively because the relationships between the entities remain elusive from the measurements. Here, we exemplarily highlight recent studies that gained deeper insight from genetic variation, protein, and PTM measurements using interaction information pointing toward the importance and potential of interaction networks for the interpretation of sequencing and proteomics data.     

基于离散粒子群算法全局QoS最优的Web服务选择

Web服务选择是Web服务组合中重要问题,也是一个NP难问题,使用离散粒子群算法对该问题进行建模求解并针对粒子群算法后期容易陷入局部最优进行改进,借鉴遗传算法中杂交变异的思想对算法迭代后期的一部分粒子进行杂交变异,实验仿真证明,由于杂交变异的引入,能够求得Web服务组合全局QoS更优的解。     

黄河下游2010年汛前调水调沙河势监测分析

利用环境减实卫星遥感监测影像,分析了2010年黄河调水调沙下游河势现状,并通过对比近几年河势变化情况,分析了调水调沙对河势的影响。结果表明:①经过多年调水调沙,黄河下游河道主槽刷深,过流能力大大增强,河势也相对稳定;②一些原来靠溜较好的工程,如驾部、南裹头、马庄、马渡险工等,有脱河脱溜的趋势,建议对这些河段加强河势变化监测;③在多年调水调沙作用下,毛庵—三官庙、黑岗口—东坝头河段工程靠溜状况趋好,河势逐步向有利方向发展,尤其是柳园口—欧坦工程河段,大部分原来不靠河的工程开始逐步靠溜,当前河势较为顺畅。