Tribological behaviors of DLC films in sulfuric acid and sodium hydroxide solutions

Tribological behaviors of three typical kinds of diamond-like carbon (DLC) films (a-C, a-C:Cr, and a-C:H) in sulfuric acid and sodium hydroxide solutions were investigated. The a-C film showed the lowest stable coefficients of friction (COF) in both sulfuric acid and sodium hydroxide solutions but the worst wear resistance in sulfuric acid solution. The a-C:H film showed the highest COF in sulfuric acid solution and the best wear resistance in both sulfuric acid and sodium hydroxide solutions. The a-C:Cr film exhibited superior comprehensive tribological performance in sulfuric acid solution, while in sodium hydroxide solution, high COF and very poor wear resistance was observed. What is more, friction and wear mechanism was revealed by investigating the friction-induced material evolutions on the sliding surface.     

Adsorptive Voltammetric Behaviors of Resveratrol at Graphite Electrode and its Determination in Tablet Dosage Form

The adsorptive voltammetric behavior of resveratrol was studied at a graphite electrode in B‐R buffer (pH = 6.0) solution using adsorptive cyclic voltammetric technique. The oxidation of resveratrol is an irreversible adsorption controlled process. The oxidation mechanism was proposed and discussed in this work. The dependence of the current on pH and the concentration and nature of buffer were investigated to optimize the experimental conditions for the determination of resveratrol. It was found that in the range of 8.0 × 10^?9 ～ 2.0 × 10^?6 mol/L, the currents measured by differential pulse voltammetries presented a good linear property as a function of the concentrations of resveratrol. In addition, validation parameters, such as reproducibility, sensitivity and recovery were evaluated as well. The proposed method was also successfully applied for the determination of resveratrol in Chinese patent medicine with good results.     

一类推广的非线性S-G型抛物方程解的渐近性与爆破

讨论了一类推广的非线性Sobolev-Galpern抛物方程的初边值问题,利用改进的积分估计法和特征函数法,深入探讨了相应问题解的渐近性和爆破现象,得到了许多新结果.     

基于动态切换的城市轨道交通车站应急疏散模型

基于应急条件下乘客可能采取的最近疏散行为、退避疏散行为、从众疏散行为、回返疏散行为、均衡疏散行为等5种主要疏散行为对乘客吸引力的动态变化,构建了基于应急信息刺激的乘客疏散行为动态切换的3层模型体系.对不同微观行人仿真模型的优缺点进行分析,构建了融合应急行为决策模型、A*算法、社会力模型的应急疏散联合仿真体系.最后,利用实际城市轨道交通车站的应急疏散调查数据,对模型参数进行了标定,并对仿真效果进行了验证.     

Influences of Bis-(2,6-Diisopropylphenyl) Carbodiimide on the Thermal Stability and Crystallization of Poly(P-Dioxanone)

The influences on the thermal degradation and crystallization behaviors of poly(p-dioxanone) (PPDO) were initially investigated by adding bis-(2,6-diisopropylphenyl) carbodiimide (labeled as St). It was found that the addition of St could significantly enhance the thermal stability and crystallizability of PPDO. The thermal decomposition temperature of PPDO increased with the increase of the amount of St added. The thermal decomposition activation energies of PPDO increased from 94.2 to 130.8 kJ mol^?1 in the case of 5 wt% St. The addition of St did not change the crystal structure of PPDO, while it increased the number of nucleation sites and improved the crystallizability of PPDO. The crystallization activation energies, calculated by the Kissinger method, for PPDO and PPDO/5 wt% St were ?111.4 and ?141.5 kJ mol^?1, respectively, confirming the crystallizability of PPDO was enhanced after the addition of St.     

碳纤维增强摩阻材料的摩擦磨损特性研究

利用Ｄ－ＭＳ摩擦磨损试验机研究了自制的碳纤维增强摩阻材料的碳纤维含量、表面状态、强度及长度对其摩擦磨损性能的影响．结果表明：碳纤维含量对摩阻材料的摩擦磨损性能有显著影响,低含量时主要起减摩作用,高含量时主要起抗犁削作用;经过表面改性的碳纤维与粘结剂结合强度较高,能改善摩阻材料的摩擦磨损性能,高强度碳纤维增强摩阻材料具有较好的摩擦磨损性能;碳纤维长度对摩阻材料的摩擦磨损性能和加工性能具有一定的影响．     

Near‐infrared spectroscopic studies on the cure behaviors of the CAE/DGEBA blend system initiated by a thermal latent catalyst

The latent properties and cure behaviors of an epoxy blend system based on cycloaliphatic epoxy (CAE) and diglycidyl ether of bisphenol A (DGEBA) epoxy containing N‐benzylpyrazinium hexafluoroantimonate (BPH) as a thermal latent initiator were investigated with near‐infrared (N‐IR) spectroscopy. The assignments of the latent properties and cure kinetics were performed by the measurements of the N‐IR reflectance for epoxide and hydroxyl functional groups at different temperatures and compositions. As a result, this system showed more than one type of reaction, and BPH was an excellent thermal latent catalyst without any coinitiator. The cure behaviors were identified by the changes in the absorption intensity of the hydroxyl groups at 7100 cm⁻¹ with different composition ratios. Moreover, characteristic N‐IR band assignments were used to evaluate the reactive kinetics and were shown to be an appropriate method for studying the cure behaviors of the CAE/DGEBA blend system containing a thermal latent catalyst. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 326–331, 2001     

基于小波技术的GPS相位观测值周跳探测

该文根据小波变换对信号奇异性检测的原理对GPS相位观测值进行周跳的探测,将GPS相位观测值发生周跳处视作信号的奇异点,其小波变换后的系数具有模量极大值,通过对模量极大值点的检测确定周跳的位置,实验数据证明基于小波变换的周跳探测自动化程度较高,定位准确,由于形成双差过程中消除了一些相关误差的影响,其双差观测值的探测比单差观测值效果明显,而且周跳越大效果越好。