Hermite matrix in Lagrange basis for scaling static output feedback polynomial matrix inequalities

Using Hermite's formulation of polynomial stability conditions, static output feedback (SOF) controller design can be formulated as a polynomial matrix inequality (PMI), a (generally nonconvex) nonlinear semidefinite programming problem that can be solved (locally) with PENNON, an implementation of a penalty and augmented Lagrangian method. Typically, Hermite SOF PMI problems are badly scaled and experiments reveal that this has a negative impact on the overall performance of the solver. In this note we recall the algebraic interpretation of Hermite's quadratic form as a particular Bézoutian and we use results on polynomial interpolation to express the Hermite PMI in a Lagrange polynomial basis, as an alternative to the conventional power basis. Numerical experiments on benchmark problem instances show the improvement brought by the approach, in terms of problem scaling, number of iterations and convergence behaviour of PENNON.     

多工器的综合与设计

介绍了一种通过特征多项式综合多工器耦合系数的方法。该方法在低通原型频域中运用迭代算法计算优化多工器整体及各支路滤波器的特征多项式,综合得出的各支路耦合系数考虑进了多工器其余支路的影响,大幅缩短滤波器优化时间,且各支路滤波器的传输零点位置可根据需要指定。该方法也适用于双工器及三工器的推导。最终利用软件Ansoft Designer,综合设计并检验一个四工器,利用该方法得出的曲线与预期吻合。     

The Gernsheim Collection

This article focuses on the photographs of public sculptures used on belle époque picture postcards of Brussels. The subject is approached from two perspectives. Firstly, we analyse the conventions of in situ photography of public sculpture in light of the genre’s reliance on painterly and photographic traditions, as well as its adoption of visual strategies derived from amateur and snapshot photography. Secondly, we explore the role of the photographic mise-en-scène of picture postcards in constructing an ideological as well as visual perspective on public monuments and the cityscape. The in situ photography of urban statues for picture postcards can be regarded as a photographic genre at the intersection of documentary art reproduction practices and amateur photography of the city. Moreover, the picture postcards discussed in this essay confirm and propagate dominant discourses on the monument and the cityscape, even if at the same time such visions were challenged. In the case of Brussels, the postcards demonstrate a preference for a monumental, impressive cityscape, worthy of representing the Belgian nation and capable of legitimising it through views of sculpture as a grand art, serving the worship of grands hommes.     

Colour and tolerance of preferred skin colours on digital photographic images

Skin‐tone has been an active research subject in photographic colour reproduction. There is a consistent conclusion that preferred skin colours are different from actual skin colours. However, preferred skin colours found from different studies are somewhat different. To have a solid understanding of skin colour preference of digital photographic images, psychophysical experiments were conducted to determine a preferred skin colour region and to study inter‐observer variation and tolerance of preferred skin colours. In the first experiment, a preferred skin colour region is searched on the entire skin colour region. A set of nine predetermined colour centers uniformly sampled within the skin colour ellipse in CIELAB a*b* diagram is used to morph skin colours of test images. Preferred skin colour centers are found through the experiment. In a second experiment, a twice denser sampling of nine skin colour centers around the preferred skin colour center determined in the first experiment are generated to repeat the experiment using a different set of test images and judged by a different panel of observers. The results from both experiments are compared and final preferred skin colour centers are obtained. Variations and hue and chroma tolerances of the observer skin colour preference are also analysed. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2013     

改进的数字版权保护模型

为有效解决目前数字版权保护模型中存在的对称性和不具备可撤销性等问题,提出了一种改进的基于叛逆者追踪方案的数字版权保护模型。该改进模型应用了不经意多项式估值(OPE)协议的特点,用户在注册阶段,商家和用户同时执行OPE协议,真正实现了两者之间的非对称性。针对买家付款后却可能收不到产品的问题,新模型还引进了既可以保护商家利益又可以保护用户利益的可信中心(TC),使其更具有实用性。改进模型还增加了软件服务撤销功能,该算法进一步完善了版权保护。通过具体实例表明了该模型的可行性和有效性。     

Multilevel preconditioning of graph-Laplacians: Polynomial approximation of the pivot blocks inverses

We consider the discrete system resulting from mixed finite element approximation of a second-order elliptic boundary value problem with Crouzeix–Raviart non-conforming elements for the vector valued unknown function and piece-wise constants for the scalar valued unknown function. Since the mass matrix corresponding to the vector valued variables is diagonal, these unknowns can be eliminated exactly. Thus, the problem of designing an efficient algorithm for the solution of the resulting algebraic system is reduced to one of constructing an efficient algorithm for a system whose matrix is a graph-Laplacian (or weighted graph-Laplacian).     

无锡房地产市场走势分析

基于无锡目前的发展模式和房市发展状态,对2011年~2013年无锡房产市场受宏观政策调控的影响进行了分析,综合分析影响价格的因素后,分别采用线性回归拟合、对数回归拟合、多项式回归拟合,比较R的大小,选用多项式回归拟合,对2014年无锡房地产市场房产价格进行了预测估计,结果表明:2014年无锡房地产市场价格总体保持平稳,但是略有上涨,涨幅在3%~5%之间。     

用DTM拟合GPS水准似大地水准面及其效果分析

介绍了使用CASS软件创建高程异常的地面数字模型并绘制等值线图拟合GPS水准的似大地水准面的方法,通过与多种曲面拟合方法比较验证了DTM法具有良好的拟合效果,非常便于工程实际使用。     

彩色柔性版印刷色彩阶调再现性

为提高彩色柔性版印刷的色彩阶调再现性,研究了柔性版印刷网点扩大特性、阶调再现特性和色彩再现特性,并对网纹辊线数与印版网点线数的关系进行了研究.在相同的印刷条件下,通过柔性版印刷机进行印刷实验,建立了柔性版印刷profile文件,从而得到柔性版印刷网点扩大曲线、阶调再现曲线和色彩再现特性.同时,采用不同线数的网纹辊对不同网点线数的印版进行印刷,测量了印刷品的阶调再现曲线和网点扩大曲线.实验结果表明:柔性版印刷网点扩大较大,且在亮调到中间调范围(网点百分比为30%～40%)处的网点扩大最严重,从而使得柔性版印刷的阶调再现范围较窄.网纹辊线数与印版网点线数的比值越大,所得到的印刷品阶调再现性越好,其比值应大于3～4.柔性版印刷的色域在红绿色范围内较胶印小,而在蓝色范围内较胶印大.为提高彩色柔性版印刷的质量,应利用profile文件对图象进行分色制版.     

低矮房屋风致结构响应极值不确定性分析

风致结构响应极值估算在结构抗风的可靠度设计中十分重要。在整个极值估算过程中,由于许多不定或随机的因素存在(如：极值自身、估算方法、样本采集、极值概率模型等),得到的极值通常存在不确定性。在各种影响因素中,该文将考虑结构响应极值变量本身的随机特性,对任意分位点处响应极值的不确定性进行分析。首先,利用有限元软件对低矮房屋模型进行框架结构设计并优化,加载风压荷载得到结构响应时程数据。然后,基于Hermite多项式模型(HPM)转换过程方法,估算得到响应的极值Ⅰ型分布(Gumbel);基于该极值估算方法,提出时程样本偏度、峰度、零超越次数与Gumbel分布两个参数之间的经验公式。接着,考虑前四阶矩的不确定性,利用经验公式以及多步概率分析,对任意分位点处响应极值的不确定性进行估计。最后,给出相关结论。