Strength of biodegradable polypropylene tapes filled with a modified starch

The possibility of creating composite materials with high deformation and strength characteristics based on polypropylene (PP) and a natural polysaccharide in the form of a modified starch (MS) has been studied. The modified starch is shown to interact chemically with functional groups of PP, thereby positively affecting the physicomechanical properties, structure, and water absorption properties of films and oriented flat fibers based on starch-filled PP. The strength characteristics of both oriented and unoriented composites are 1.5–2.0 times as high as those of the initial PP. The water absorption ability of the materials varies symbatically with content of MS, which points to the dominant contribution of interactions at the PP-MS interface. The introduction of MS into synthetic polymers offers a possibility of producing new ecologically safe materials with high strength characteristics. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 3, pp. 389–400, May–June, 2006.     

Data Sphering: Some Properties and Applications

Centring-then-sphering is a very important pretreatment in data analysis. The purpose of this paper is to study the asymptotic behavior of the sphering matrix based on the square root decomposition (SRD for short) and its applications. A sufficient condition is given under which SRD has nondegenerate asymptotic distribution. As examples, some commonly used and affine equivariant estimates of the dispersion matrix are shown to satisfy this condition. The case when the population dispersion matrix varies is also treated. Applications to projection pursuit (PP) are presented. It is shown that for elliptically symmetric distributions the PP index after centring-then-sphering is independent of the underlying population location and dispersion.     

基于投影偏度和投影峰度的投影寻踪自助法的正态性检验

本文研究了多元分布的正态性检验问题,用投影寻踪自助法,获得了投影偏度和投影峰度正态性检验统计量,证明了在零假设成立时,所提出的偏度和峰度检验统计量的极限分布为一高斯过程的上界.为计算机模拟计算提供了有力的手段和依据.     

两多维样本模型中位置参数相等性的M-检验

本文给出了基于投影寻踪方法检验两多维样本位置参数相等的M 统计量和t 统计量,分别用PP型自助M 统计量和PP型自助t 统计量给出了上述两统计量的近似分布, 并给出了检验的算法,进行一些模拟.     

寿命分布的PP图

本文介绍了三种寿命分布的PP图,并比较了PP图和QQ图,得出PP图是一种更加直观的、更具解释性的拟合优度检验图;     

PP 检验的渐近功效

投影寻踪(Projection Pursnit,简称 PP)是一种处理高维数据的统计方法,近年来借助于计算机的发展,它的理论得到了迅速的发展.假如(?)为一能反映统计性质的指标,对每个 p 维方向α,计算出(?)(α~(?)X_1,…,α~(?)X_(?)),从中找出使(?)(α~(?)?X_1,…,α~(?)X_(?))最大的方向α_0,通过研究数据α_0~(?)X_1,…,α_0~(?)X_(?) 的性质,来了解原数据 X_1,…,X_(?)的性质,这就是所谓数值 PP 的基本想法.如果用一维检验或估计统计量(?)作指标,则可得到多维检验或估计(?)(?)(α~(?)X_1,…,α~(?)X_(?)).见文献[2,3,5—7].在上述文章中这些检验和     

关于Baer PP和PS环的一些性质(英)

在此文中,我们对Strong-Armendariz环和Baer PP及PS环Ore-扩张R[x,x~(-1)；α]的一些性质进行了讨论研究,并得到了一些结果．主要证明了R是Baer(PP)环当且仅当R[[x]]是Baer(PP)环及R是α-rigid环时,R是Baer(PP,PS)环当且仅当R[[x]]是Baer(PP,PS)环．     

PP multivariate random weighting method

According to the Projection Pursuit (PP) method and the random weighting method, we propose a PP random weighting method, and set up the asymptotic distribution theory and strong limit theorem of PP random weighting empirical process. Applying this method, we obtain two kinds of goodness-of-fit test for a multivariate distribution function, i.e., we get the random weighting approximations of PP Kolmogorov Smirnov statistics (PPKS) and PP Smirnov Cramér Von Mises statistics (PPSC), we prove that the asymptotic distribution of PPKS and PPSC are the same as those of their respective random weighting approximations.Supported by the National Natural Science Foundation of China.     

形式三角矩阵的PP和半遗传环(英文)

In this paper the sufficient and necessary conditions are given for a formal triangular matrix ring to be right PP, generalized right PP, or semihereditary, respectively.     

Coordination of production and interstage batch delivery with outsourced distribution

In this paper, we consider coordinated production and interstage batch delivery scheduling problems, where a third-party logistics provider (3PP) delivers semi-finished products in batches from one production location to another production location belonging to the same manufacturer. A batch cannot be delivered until all jobs of the batch are completed at the upstream stage. The 3PP is required to deliver each product within a time T from its release at the upstream stage. We consider two transportation modes: regular transportation, for which delivery departure times are fixed at the beginning, and express transportation, for which delivery departure times are flexible. We analyze the problems faced by the 3PP when either the manufacturer dominates or the 3PP dominates. In this context, we investigate the complexity of several problems, providing polynomiality and NP-completeness results.     

Exact algorithms for the two-dimensional strip packing problem with and without rotations

We propose exact algorithms for the two-dimensional strip packing problem (2SP) with and without 90° rotations. We first focus on the perfect packing problem (PP), which is a special case of 2SP, wherein all given rectangles are required to be packed without wasted space, and design branch-and-bound algorithms introducing several branching rules and bounding operations. A combination of these rules yields an algorithm that is especially efficient for feasible instances of PP. We then propose several methods of applying the PP algorithms to 2SP. Our algorithms succeed in efficiently solving benchmark instances of PP with up to 500 rectangles and those of 2SP with up to 200 rectangles. They are often faster than existing exact algorithms specially tailored for problems without rotations.     

正规几乎PP环

首先探讨正规几乎PP环的内刻划及左右对称性；其次，研究正规几乎PP环与PP环的关系，最后证明多项式环R［X」是正规几乎PP环当且仅当R是正规几乎PP环．     

Gorenstein范畴上的一个问题

设■是阿贝尔范畴,■是■的子范畴.Sather-Wagstaff, Sharif和White引入了Gorenstein子范畴的概念,记为■.我们用■(相应地,■)代表纯投射R-模类(相应地,投射R-模类).本文给出了一类满足条件"■"的环,由此给出了当■是■的子范畴时,■是否包含在■中的一个否定回答.进一步,刻画了包含关系■和■何时成立.     

基于稳定分布的PARCH模型

本文首先介绍了稳定分布和基于正态分布、稳定分布的PARCH模型,并通过股票指数收益率的稳定化PP图和直方图发现其具有高峰厚尾特征.最后,通过上证指数的VaR计算,得到在金融风险度量中基于稳定分布的PARCH模型比基于正态分布的PARCH模型更加有效。     

协方差矩阵的齐性检验

基于ＰＰ技术、Ｂｏｏｔｓｔｒａｐ方法和数论方法,对于ｋ个总体协方差矩阵相等的检验,给出了ＰＰ型检验统计量,并讨论了它的渐近分布和Ｂｏｏｔｓｔｒａｐ逼近,最后给出了一些实际模拟结果。     

A result on large surfaces of prescribed mean curvature in a Riemannian manifold

Plateau's problem (PP) is studied for surfaces of prescribed mean curvature spanned by a given contour in a 3-d Riemannian manifold. We consider the local situation where a neighborhood of a given point on the manifold is described by a single normal chart. Under certain conditions on and the contour, existence of a small -surface to (PP) is guaranteed by [HK]. The purpose of this paper is the investigation of large -surfaces. Our result states: For sufficiently large (constant) mean curvature and a sufficiently small contour depending on the local geometry of the manifold, (PP) has at least two solutions, a small one and a large one. The proof is based on mountain pass arguments and uses – in contrast to results in the 3-d Euclidean space and in order to derive conformality directly – also a deformation constructed by variations of the independent variable. Received November 8, 1995 / Accepted April 29, 1996     

随机PP Kolmogorov多维拟合优度检验乃其Bootstrap逼近

本文提出了一种基于随机选择投影方向的PP型棉球等高分布族的拟合优度检验，其特点是计算上较通常的PP检验统计量简单．得到了其检验统计量在零假设下的极限分布，讨论了其Bootstrap逼近及逼近的相容性．     

投影寻踪方法与高光谱遥感图像数据特征提取的研究

高光谱技术的发展与应用对高维的高光谱遥感数据的处理方法提出了更高的要求，投影寻踪方法是一种处理高维数据的十分有效的降维方法。高光谱图像分析对投影寻踪方法仍是一个全新的领域。本文介绍了投影寻踪的一般概念。分析了基于信息散度指标投影的寻踪方法在高光谱图像处理中的应用，给出了它与主成份分析处理结果的对比。并提出PP与高光谱研究将来的发展方向。     

Analytic methods for obstruction to integrability in discrete dynamical systems

A unique analytic continuation result is proven for solutions of a relatively general class of difference equations by using techniques of generalized Borel summability. This continuation allows for Painlevé property methods to be extended to difference equations. It is shown that the Painlevé property (PP) induces, under relatively general assumptions, a dichotomy within first‐order difference equations: all equations with PP can be solved in closed form; on the contrary, absence of PP implies, under some further assumptions, that the local conserved quantities are strictly local in the sense that they develop singularity barriers on the boundary of some compact set. The technique produces analytic formulas to describe fractal sets originating in polynomial iterations. © 2004 Wiley Periodicals, Inc.     

Positivity-Preserving Local Discontinuous Galerkin Method for Pattern Formation Dynamical Model in Polymerizing Actin Flocks

In this paper, we apply local discontinuous Galerkin (LDG) methods for pattern formation dynamical model in polymerizing actin flocks. There are two main difficulties in designing effective numerical solvers. First of all, the density function is non-negative, and zero is an unstable equilibrium solution. Therefore, negative density values may yield blow-up solutions. To obtain positive numerical approximations, we apply the positivity-preserving (PP) techniques. Secondly, the model may contain stiff source. The most commonly used time integration for the PP technique is the strong-stability-preserving Runge-Kutta method. However, for problems with stiff source, such time discretizations may require strictly limited time step sizes, leading to large computational cost. Moreover, the stiff source any trigger spurious filament polarization, leading to wrong numerical approximations on coarse meshes. In this paper, we combine the PP LDG methods with the semi-implicit Runge-Kutta methods. Numerical experiments demonstrate that the proposed method can yield accurate numerical approximations with relatively large time steps.