DEA models for ratio data: Convexity consideration

Data envelopment analysis (DEA) is defined based on observed units and by finding the distance of each unit to the border of estimated production possibility set (PPS). The convexity is one of the underlying assumptions of the PPS. This paper shows some difficulties of using standard DEA models in the presence of input-ratios and/or output-ratios. The paper defines a new convexity assumption when data includes a ratio variable. Then it proposes a series of modified DEA models which are capable to rectify this problem.     

A two-tail version of the PPS distribution with application to current account balance data

The double Pareto-positive stable (dPPS) distribution is introduced as a new model for describing countries’ global current account balance data. The dPPS distribution provides a flexible model for fitting the entire range of a set of current account data (both surplus and deficit), where zero and unimodality are possible, and the double-sided Pareto distribution is included as a particular case. Expressions for the cumulative distribution, probability density and quantile functions are given. An estimation method is discussed and a simple graphical method for studying the adequacy of the data to model is given. Finally, we consider the fit of countries’ global current account balance data for several years. The new distribution is compared with four classical models: Normal, Skew Normal, Asymmetric Laplace and Hyperbolic distributions. In all the data sets considered, the dPPS distribution outperforms the fits of these four distributions.     

PPS抽样──一种有效的水路运输量抽样方法

本文针对水运运输特点，通过对实际资料的分析和计算，对水运运输量的抽样方法作分析比较，提出利用ＰＰＳ抽样进行我国水路运输量的抽样抽查。     

Evaluation of long chain branching of polyphenylene sulfide using gel permeation chromatography with triple detection

The increasing polyphenylene sulfide (PPS) world demand due to its unique mechanical and chemical properties has augmented the pressure on development of analytical methods to evaluate its molecular weight distribution and structure. This article presents gel permeation chromatography with triple detection (GPC3D) performed in chloronaphthalene at 210°C on a commercially available instrument as a possible method to elucidate the structure properties of linear and branched PPS. The procedure allows measurement in a single run of the true molecular weight distributions and intrinsic viscosities, the Mark-Houwink parameters, and the number of long chain branches.     

Mechanical degradation of filter polymer materials: Polyphenylene sulfide

Polyphenylene sulfide (PPS) is known as a material resistant to high temperature and chemicals; however, there are arguments on the durability of PPS non-woven fabrics to chemicals, such as nitric acid (HNO₃), sulfuric acid (H₂SO₄), and hydrochloric acid (HCl). Therefore, this work aims at investigating the degradation of PPS non-woven fabrics in HNO₃, H₂SO₄ and HCl, and at confirming acid durability of PPS non-woven fabrics. In addition, this paper also studies the interaction among these three acids by measuring the retention of strength in binary or tertiary mixtures of these three acids. A discussion has been made on the acceleration/retardation of PPS degradation by the interactive effects, and also on the chemistry related to the degradation by these acids. Furthermore, there is a linear relationship between the nitric acid concentration and the proportion of carbon in the remaining PPS structures after 100 h of acid exposure. Also, this proportion of carbon is a good indicator of the retained strength in PPS fabrics.     

Analysis on interfacial stress in impact of polyphenylene sulfide/CaCO3 composites

The interfacial stress and its distribution during impact of inorganic particulate‐filled polymer composites were analyzed in the present paper by means of a three‐dimensional (3D) finite element method, and the software used was the ANSYS/LS‐DYNA (ANSYS Inc., Canonsburg, PA, USA). The simulation results showed that the normal stress, the shear stress, and the equivalent stress reached the maximum at the particle equator, and then they reduced quickly toward the direction of the particle pole along the interface between the particle and the matrix and achieved the minimum from about 0.5 to 2.0 µm from the equator. Finally, they tended to gently or somewhat increase. Furthermore, the ways and mechanisms of the major fail or fracture of the polyphenylene sulfide (PPS)/calcium carbonate (CaCO₃) composites under impact load were discussed. The mechanism of impact fracture or failure of inorganic particle‐filled PPS composites might be that the matrix around the neighboring inclusions will first yield owing to the stress concentration in the interface between the inclusion and the matrix to induce crazes and extend quickly. Copyright © 2011 John Wiley & Sons, Ltd.     

基于二相抽样的PPS二阶抽样

研究初级单元大小未知时基于二相抽样的PPS二阶抽样，给出总体总值的估计量，估计量的方差及方差的估计量。     

Comparative study of sub-micrometer polymeric structures: Dot-arrays, linear and crossed gratings generated by UV laser based two-beam interference, as surfaces for SPR and AFM based bio-sensing

Two-dimensional gratings are generated on poly-carbonate films spin-coated onto thin gold-silver bimetallic layers by two-beam interference method. Sub-micrometer periodic polymer dots and stripes are produced illuminating the poly-carbonate surface by p- and s-polarized beams of a frequency quadrupled Nd:YAG laser, and crossed gratings are generated by rotating the substrates between two sequential treatments. It is shown by pulsed force mode atomic force microscopy that the mean value of the adhesion is enhanced on the dot-arrays and on the crossed gratings. The grating-coupling on the two-dimensional structures results in double peaks on the angle dependent resonance curves of the surface plasmons excited by frequency doubled Nd:YAG laser. The comparison of the resonance curves proves that a surface profile ensuring minimal undirected scattering is required to optimize the grating-coupling, in addition to the minimal modulation amplitude, and to the optimal azimuthal orientation. The secondary minima are the narrowest in presence of linear gratings on multi-layers having optimized composition, and on crossed structures consisting of appropriately oriented polymer stripes. The large coupling efficiency and adhesion result in high detection sensitivity on the crossed gratings. Bio-sensing is realized by monitoring the rotated-crossed grating-coupled surface plasmon resonance curves, and detecting the chemical heterogeneity by tapping-mode atomic force microscopy. The interaction of Amyloid-β peptide, a pathogenetic factor in Alzheimer disease, with therapeutical molecules is demonstrated.