A Modified Polynomial Preserving Recovery and Its Applications to A Posteriori Error Estimates

<正>A modified polynomial preserving gradient recovery technique is proposed. Unlike the polynomial preserving gradient recovery technique,the gradient recovered with the modified polynomial preserving recovery(MPPR) is constructed element-wise, and it is discontinuous across the interior edges.One advantage of the MPPR technique is that the implementation is easier when adaptive meshes are involved.Superconvergence results of the gradient recovered with MPPR are proved for finite element methods for elliptic boundary problems and eigenvalue problems under adaptive meshes. The MPPR is applied to adaptive finite element methods to construct asymptotic exact a posteriori error estimates.Numerical tests are provided to examine the theoretical results and the effectiveness of the adaptive finite element algorithms.     

Pesticides in water and the performance of the liquid-phase microextraction based techniques. A review

The control of pesticides in surface, drinking and groundwater is nowadays a real necessity. In the European Community, their concentration must comply with the established parametric and environmental quality standards (EQSs). Regarding the new legislation, this article updates the information concerning the monitoring of pesticides and the technical specifications for their measurement in water samples where ultra-sensitive analytical methods are required. For some compounds, like pesticides, there is still a need to improve the performance of the existing methods. High sensitive techniques like gas chromatography tandem mass spectrometry (GC–MS/MS) and liquid chromatography coupled with mass spectrometry (LC–MS) have been developed. However, for most of the substances present at trace and ultra-trace levels the extraction and preconcentration steps are so far essential for their detection. Advances at a micro scale have been made and different types of microextractions are being developed. Liquid-phase microextraction (LPME) is an example. The study of this technique has increased in the last years and some innovations have been recently reported for pesticides water analysis. This article reviews the new developed LPME-based techniques and compares its performance with the analytical specifications established for pesticides water monitoring. The results show that LPME-based techniques can be a promising tool to improve the nowadays performance of methods used in pesticides water control.     

色谱技术在中药有效成分辨识中的应用进展

中药效应成分辨识是中药质量控制研究的关键,本文从化学特性、生物靶标和整体作用三个层面综述了2000年以来色谱技术在中药效应成分辨识研究中的应用进展,并提出未来发展方向.     

Potentiometric sensor using sub-micron Cu2O-doped RuO2 sensing electrode with improved antifouling resistance

A Cu₂O-doped RuO₂ sensing electrode (SE) for potentiometric detection of dissolved oxygen (DO) was prepared and its structure and electrochemical properties were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron microscopy (XPS) and energy-dispersive spectroscopy (EDS) techniques. Cu₂O-RuO₂-SE displayed a linear DO response from 0.5 to 8.0 ppm (log[O₂], −4.73 to −3.59) within a temperature range of 9-30 °C. The maximum sensitivity of −47.4 mV/decade at 7.27 pH was achieved at 10 mol% Cu₂O. Experimental evaluation of the Cu₂O-doped RuO₂-SE demonstrated that the doping of RuO₂ not only improves its structure but also enhances both sensor's selectivity and antifouling properties. Selectivity measurements revealed that 10 mol% Cu₂O-doped RuO₂-SE is insensitive to the presence of Na⁺, Mg²⁺, K⁺, Ca²⁺, NO₃⁻, PO₄²⁻ and SO₄²⁻ ions in the solution in the concentration range of 10⁻⁷-10⁻¹ mol/l.     

长沙市老龄人口生活质量分析

按照人口基本特征、物质生活水平、精神生活、健康状况、社会环境与家庭生活分析了长沙市老龄人口生活特征,并从中选取10个代表性指标,采用因子分析的方法分析了各个因子方差贡献率的大小,得到了影响长沙市老龄人口生活质量的主要指标为:精神生活、物质生活水平、健康状况、文化程度与家庭生活.     

质量保证策略下服务商的质量缺陷补偿决策分析

随着竞争的日趋激烈,越来越多的服务商采用质量保证策略作为竞争手段以吸引顾客,然而现有研究缺乏对该策略下的质量缺陷补偿问题的深入分析。鉴于此,本文系统地分析了质量保证策略下服务商的质量缺陷补偿问题:首先分析了当服务价格外生时,服务商的最优质量缺陷补偿决策;然后分别探讨在服务价格内生变化和服务供给变动的影响下,服务商的最优质量缺陷补偿;最后,通过数值分析,探寻在服务价格和服务供给的双重变动影响下,服务商的最优质量缺陷补偿。本文拓展了服务质量的研究,对于指导服务型企业如何制定质量缺陷补偿具有较强的实践启示意义。     

随机需求下物流服务供应链订购策略研究

针对由单个物流服务提供商和集成商组成的物流服务供应链,基于集中化模式、纳什博弈模式和Stackelberg博弈模式三种典型模式,考虑市场需求随机且受服务质量缺陷承诺水平的影响,探讨物流服务供应链的订购与质量缺陷承诺策略问题。通过分析发现:物流服务质量缺陷承诺水平随着市场需求弹性系数的增加而递减,但其受物流服务集成商观测水平的影响却因合作模式不同而变化不一致;集中化模式下的物流服务订购量随着物流服务集成商观测水平或市场需求弹性系数的增大而递减,但在其他两种合作模式下物流服务订购量随着物流服务集成商观测水平或市场需求弹性系数的增加而增加;在三种模式下,物流服务供应链的整体利润随着市场需求弹性系数的增加而递减,但其受物流服务集成商观测水平的影响却因合作模式不同而变化不一致。     

以质取胜——企业技术创新与经营绩效

本文选择创新型上市公司2006~2013年的数据为样本,实证检验专利产出对企业经营绩效的影响。结果发现,专利数量的剧增对企业经营绩效有显著的负向影响,专利质量才能促进企业经营绩效的改善。专利质量对高科技企业、国有企业和知识产权保护好地区的企业经营绩效具有显著的促进作用。进一步研究发现,专利质量通过影响企业在产品市场中的市场势力进而作用于经营绩效。最后,为提升企业的专利质量,本文从企业自身和政府部门两个角度提出对策建议。     

再使用产品的质量判断研究

再使用产品是回收产品再利用的第一优先级.给出了再使用产品的定义,并利用数据包络分析方法对其进行了质量判断.通过案例分析,说明该模型用于再使用产品质量判断是可行的和有效的.