六态矢量Potts模型的相结构和相变性质

本文用变分累积展开（ＶＣＥ）方法对六态矢量Ｐｏｔｔｓ模型的相结构和相变性质进行了研究。在引进单变分参数情况下，系统的自由能，内能，比热和自发磁化强度被计算到四阶近似；在双变分参数情况下，上述物理量被计算到二阶近似。结果表明，系统存在三相结构，在较低温度下发生的是连续相变，而在较高温度下发生的是一级相变。得出的相变位置和用蒙特卡罗（ＭＣ）数值模拟方法给出的结果相一致，体现了用ＶＣＥ方法处理Ｐｏｔｔｓ模型的有效性。比用ＭＣ方法的优越性在于，用ＶＣＥ方法能体现出序参量和内能在一级相变时发生突变的情况。     

A relation between edit distance for ordered trees and edit distance for Euler strings

We consider a relationship between the unit cost edit distance for two rooted ordered trees and the unit cost edit distance for the corresponding Euler strings. We show that the edit distance between trees is at least half of the edit distance between the Euler strings and is at most 2h+1 times the edit distance between the Euler strings, where h is the minimum height of two trees. The result can be extended for more general cost functions.     

Confined‐error‐diffusion algorithm for flat‐panel display

Abstract— The reduction of a structural pattern at specific gray levels caused by digital halftone methods is the subject of this paper. This problem is more severe in some flat‐panel displays because their black levels typically are brighter than other display blocks. A patented halftone algorithm, confined error diffusion (CED), that confines the error‐carry within the dither mask is described and extended. First, the CED algorithm that dynamically applies random error diffusion or the ordered‐dither method, depending upon image content, is described in detail. Finally, we propose an advanced CED algorithm for improving the gradation characteristics of the CED algorithm. The performance of the proposed algorithms is compared to the experimental results for natural test images. In order to verify the halftone quality, a structural similarity measure for color images by taking into account the interrelation between color channels is proposed, and the results based on the proposed method, the color similarity measure method, is given.     

Minimizing ordered weighted averaging of rational functions with applications to continuous location

This paper considers the problem of minimizing the ordered weighted average (or ordered median) function of finitely many rational functions over compact semi-algebraic sets. Ordered weighted averages of rational functions are, in general, neither rational functions nor the supremum of rational functions so current results available for the minimization of rational functions cannot be applied to handle these problems. We prove that the problem can be transformed into a new problem embedded in a higher dimensional space where it admits a convenient polynomial optimization representation. This reformulation allows a hierarchy of SDP relaxations that approximates, up to any degree of accuracy, the optimal value of those problems. We apply this general framework to a broad family of continuous location problems showing that some difficult problems (convex and non-convex) that up to date could only be solved on the plane and with Euclidean distance can be reasonably solved with different _?p-norms${?}_p\mathrm{-}\mathrm{norms}$ in finite dimensional spaces. We illustrate this methodology with some extensive computational results on constrained and unconstrained location problems.     

Hydrogen oxidation on ordered intermetallic electrodes covered with CO

This describes an experimental evaluation of the electrocatalytic activity of the hydrogen oxidation reaction on electrodes of platinum and the ordered intermetallic phases PtSb and PtSn, on which CO has previously been deposited. The experiments were carried out in perchloric acid solution and the analysis based on steady-state polarization curves and Tafel plots derived from chronoamperometric data. Both intermetallics, PtSb and PtSn, performed better than Pt towards the HOR, when their surface was deliberately covered with CO. It is suggested that the intermetallic surfaces have a lower affinity for CO molecules, causing a lower CO coverage on these surfaces, and/or a weaker surface–CO interaction, compared to Pt under the same conditions.     

Preparation of Cerium (III) 12-tungstophosphoric acid/ordered mesoporous carbon composite modified electrode and its electrocatalytic properties

In this work, a novel structured Cerium (III) 12-tungstophosphoric acid (CePW)/ordered mesoporous carbon (OMC) composite is synthesized. The characterization of the material by the Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical characterization shows that the novel CePW/OMC composite has improved properties based on the combination of CePW and OMC properties. CePW/OMC can be used to modify the glassy carbon (GC) electrode and the CePW/OMC/GC modified electrode shows an enhanced electrocatalytic activity. This property can be applied in the determination of some biomolecules. Especially, the detection and determination of the guanine (G) in the presence of adenine (A) is achieved. The catalytic current of G versus its concentration shows a good linearity with two good linear ranges from 4.0 × 10⁻⁶ to 8.0 × 10⁻⁵ M and from 8.0 × 10⁻⁵ to 1.9 × 10⁻³ M (correlation coefficient = 0.999 and 0.996) with a detection limit of 5.7 × 10⁻⁹ M (S/N = 3). The linear range for adenine is 4.0 × 10⁻⁶-7.0 × 10⁻⁴ M with a detection limit of 7.45 × 10⁻⁸ M. With good stability and reproducibility, the present CePW/OMC/GC modified electrode should be a good model for constructing a novel and promising electrochemical sensing platform for further electrochemical detection of other biomolecules.     

Ethylene glycol, 2-propanol electrooxidation in alkaline medium on the ordered intermetallic PtPb surface

The ethylene glycol and 2-propanol electrooxidation reaction was studied on carbon dispersed ordered intermetallic PtPb nanocatalysts in KOH solution. X-ray diffraction and X-ray photoelectron spectroscopy were used to characterize ordered intermetallic PtPb/C catalysts. The electrochemical behaviors for the ethylene glycol and 2-propanol electrooxidation reaction were measured in a thin film electrode by cyclic voltammetry, Tafel curves and electrochemical impedance spectroscopy. The results showed that in contrast with PtRu/C and Pt/C catalyst, ordered intermetallic PtPb/C had better electroactivity, and kinetic mechanism of PtPb/C is complex. Although the activity of electrocatalysts depends on many factors, such as modification of geometric and electronic structure by Pt-Pb interaction, crystalline size and so on. But the key factor for each electrooxidation reaction was different. For ethylene glycol electrooxidation, the effect of formation and desorption of poisonous species on activity of catalyst was very significant. For 2-propanol electrooxidation, the modification of geometric and electronic structures may be play a decisive role in the enhance activity of electrocatalyst.     

基于用户利益与出行意愿的电动汽车充放电调度策略

如今,随着越来越多智能充电桩的建立,人们对电动汽车的需求量日益加大,电动汽车不仅可以提高能源利用率、减少污染,而且还可以反向对电网进行供电,达到削峰填谷的目的。但是随着越来越多的电动汽车接入到电网,越来越多的用户参与到电动汽车调度中,电动汽车的充放电调度也变得越为复杂,在以往的一些调控中总是优先考虑电网的峰值负荷如何降低,却很少考虑用户的需求与利益。事实上,在保证电网负荷曲线的同时更应该考虑到用户的利益与需求,因为用户的利益与需求才是保证调度计划顺利实施的基础。文中基于用户的利益与出行意愿,利用粒子群算法对电动汽车的充放电进行调度,保证了用户的利益与满意度,同时有效削减了电网峰值时刻的负荷。     

Study of polymer electrolytes with grafted Au–γ-Fe2O3 nanoparticles

The work is aimed at enhancing the Li⁺ ion-conduction properties of polymer electrolytes (PE) for thin-film solid-state batteries. The research exploits novel ideas of structuring ionically conducting polymers or molecular polyether building blocks with grafted magnetic nanoparticles with the use of magnetic field, in order to enhance ionic conductivity along oriented helical PE chains. The experimental route being tested is based on the chemisorption of thiolated PEO on core–shell gold-coated maghemite. It was found that casting, under a gradient magnetic field (GMF), of concentrated PEs containing very small concentration – 0.5%(w/w) dithiol-connected Fe₂O₃/Fe₃O₄–Au nanoparticles results in enhancement of the total ionic conductivity by more than an order of magnitude.