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纳米金属催化剂的制备方法包括化学法和物理法。化学法中主要有溶胶-凝胶法、沉淀法、溶剂热合成法、微乳法和水解法等;物理法主要有气相凝聚法、溅射法和机械研磨法等。其中化学法中的溶胶-凝胶法及沉淀法应用最广。对纳米金属催化剂的制备方法进行了比较,并简要论述了制备及应用过程中存在的主要问题。 相似文献
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Douglas D. Frey 《Chemical Engineering Communications》1986,47(4):273-293
Several methods are evaluated for predicting or correlating liquid-phase mass-transfer coefficients in multicomponent ion exchange. Comparisons are made of methods based on matrix generalizations of binary results, methods using the film-model relation between multicomponent fluxes and binary mass-transfer coefficients, and effective-diffusivity methods. It was determined that methods based on the film model give results in good agreement with matrix generalization methods and, where comparisons can be made, both of these methods give results in good agreement with exact calculations. Effective-diffusivity methods were found to be less reliable. The film-model methods developed in this study are analogous to methods commonly used in nonelectrolyte systems. 相似文献
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短链氯化石蜡(SCCPs)是2017年新定义的持久性有机污染物(POPs),能对人体健康及生态环境造成重大危害。现阶段国内外关于SCCPs的研究工作主要集中在环境中SCCPs的分析检测方法和浓度水平分布规律,对SCCPs的高效去除方法及去除机理的研究较少。本文主要综述了现阶段SCCPs的有效去除方法,包括物化法(一般物化法和高级氧化处理)和生物法(细菌降解和植物吸收法),对比分析了这些方法的优缺点,讨论了不同方法去除SCCPs的影响因素、可能降解机理及途径,并通过类比借鉴,提出了其他具有可行性的去除SCCPs的方法。总体而言,虽然物化法去除效率高,但是成本高且操作条件苛刻,微生物法因经济环保而具有更大的发展潜力,但若将微生物法与物化法联用,则有可能发展成为最佳去除工艺。最后展望了环境中SCCPs去除方法的研究重点。 相似文献
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作为传统线性系统辨识方法的一个有益补充,子空间模型辨识方法(SMI)近年来获得了广泛关注.这类方法综合了系统理论,线性代数和统计学三方面的思想,其特点是直接由输入输出数据辨识系统的状态空间模型,因而非常适合多变量系统辨识.首先介绍了SMI的基本思想, 然后分析了3种基本算法(N4SID、MOESP和CVA)的异同点、算法实现、统计特性和模型稳定性等方面.随后探讨了其他一些SMI算法,包括连续时间系统SMI算法、频域SMI算法、闭环SMI算法和非线性系统SMI算法.为说明SMI方法的特性,通过一个工厂实际例子研究对比了3种SMI基本算法和一种传统辨识算法——预测误差方法(PEM).最后阐述了理论方面有待进一步研究的主要问题. 相似文献
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注塑参数优化研究方法 总被引:9,自引:1,他引:9
对参数优化方法在注塑研究中的应用进行了综述,阐述了各方法的基本原理和主要特点,着重讨论了优化方法所适用的优化问题的类型和其对注塑翘曲、收缩、熔接缝及强度的预测能力以及模拟软件的应用,探讨了不同优化方法相结合对搜索效率和优化结果的影响。 相似文献
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就工业合成对甲苯磺酰基甲基异腈生产中成品及其中间体对甲苯亚磺酸钠、对甲苯磺酰基甲基甲酰胺分别拟定了定量分析方法。三者均采用化学法测定,准确方便。 相似文献
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This paper presents a comparison of twelve selected methods for the prediction of the compressibility factor of natural gases containing H2S and CO2. The methods are compared with experimental data from the published literature and with previously unpublished data made available by oil and gas companies operating in Alberta. The method of Robinson, Macrygeorgos and Govier, and the method of Robinson and Jacoby are found to be most accurate over the range tested here. A brief desription of the twelve methods considered is also presented. Three new methods are also proposed. Two of the proposed methods are modifications of the Pitzer method and the Redlich-Kwong equation of state. These methods are suitable for digital computer applications. The third method proposed here is developed for hand calculations. The new methods presented here are superior to the twelve methods tested in this study. 相似文献
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This paper reviews empirical Bayes methods for disease mapping. A distinction is made between spatial models (which take into account the geographical distribution of disease) and nonspatial models. Several estimators are presented, and methods of estimation are described. Empirical Bayes methods are compared with full Bayes methods, and we argue that both have their place. 相似文献
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蔗糖酯的合成与应用研究进展 总被引:2,自引:0,他引:2
蔗糖酯是一种性能优良的非离子表面活性剂,综述了蔗糖酯的合成方法,分别了溶剂法(包括二甲基甲酰胺法、丙二醇法、水溶剂法、甲醇法及相转移催化法)及非溶剂法(包括生物合成法)。对蔗糖酯的应用及市场情况作了较为详细的介绍。 相似文献
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In this paper, several competitive spatial discretization methods recently developed for the convection term are reviewed and analyzed in terms of accuracy, temporal performance, and stability. This analysis was performed using a prediction–correction DAE integrator within the framework of the MOL (Method Of Lines). The discretization methods are classified by Fixed Stencil (FS), Adaptive Stencil (AS) and Weighted Stencil (WS) approaches and their main characteristics are demonstrated via a number of bench marking tests. Of the 14 discretization methods tested, four have been shown to be the most reliable, when we consider the accuracy of the calculation and the computational time required. Application of commonly-used FS methods to convection-dominated problems containing a moving shock results in a relatively short calculation time. However, almost of the FS methods, except for the first-order upwind FS method, are unstable, providing spurious oscillatory profiles (termed the Gibbs phenomena) near the shock. Employing AS methods such as ENO (Essentially Non-Oscillatory) schemes, this Gibbs phenomena disappears. Therefore, AS methods enhance stability and accuracy but are somewhat prohibitive. WS methods (i.e. Weighted ENO schemes), which use a convex combination of candidate stencils weighted by the ENO idea, can reduce the calculation time, and are inheriting of the non-oscillation nature inherent in the AS methods. The ENO and WENO methods are efficient to track a shock and steep moving front and these methods are essential for numerical schemes which use relatively small number of mesh points. 相似文献
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根据被测对象、测量区间、试验条件不同,黏度测定方法也有区别.介绍了涂料黏度不同测定方法及各自的优劣势,并给出了不同黏度单位的标准及由不同测定方法所得黏度数据的换算方法. 相似文献
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反应器网络综合优化方法的研究进展 总被引:3,自引:0,他引:3
反应器网络综合优化方法在选择反应器类型和反应工艺条件时,比传统的方法表现出了很大的优势。综述了各类反应器网络综合优化方法的基本原理和研究进展,并分析了它们的优缺点。这些方法有基于过程特征的方法,包括可得区法和导数分析法;超结构优化法;目标类方法,包括目标法、构造目标法和构造MINLP法;以及经验推断法和分布参数法等。最后分析了这方面研究的发展趋势。 相似文献
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Fenton氧化技术与其他方法联用在废水处理方面的研究进展 总被引:1,自引:0,他引:1
综述了近些年Fenton氧化技术与其他方法联用在处理难降解有机废水方面的研究进展,探讨了吸附-Fenton氧化技术、混凝-Fenton氧化技术、微波-Fenton氧化技术、生物方法-Fenton氧化技术的特点及其应用研究现状,指出了这些联用技术可改进的地方。此外,展望了联用方法的发展趋势。 相似文献