ANALYSIS OF CONCENTRATION FORCING IN HETEROGENEOUS CATALYSIS

An analysis of reaction rate enhancements by forced concentration oscillations of reactants for an adsorption/desorption type model with Eley-Rideal surface kinetics, is presented. Under cycling conditions in which the cycle time approaches zero, there is considerable rate enhancement relative to optimal steady state for nonlinear kinetics but no improvement for linear kinetics. The presence of inerts or products from irreversible reactions deteriorates the rate enhancement. For cycle times approaching infinity, there is no rate enhancement for either linear or nonlinear kinetics.     

TWO-STEP MECHANISM IN HETEROGENEOUS CATALYSIS AND DYNAMIC ANALYSIS

Recent development of the dynamic analysis technique has made it possible to measure separately kinetic parameters of a catalytic reaction as well as to study the effect of catalyst preparation parameters. But its application is still limned to first-order reaction. This work is aimed to demonstrate in some detail that,by comparison of the reaction rate expressions with the two-step mechanism used in catalytic kinetics and dynamic analysis, these methods can be extended to non-first-order reaction, and the kinetic parameters measured by dynamic techniques are interpreted for different reaction mechanisms.     

动态（脉冲）—原位测试技术的发展及其在多相催化研究中的应用

介绍一种动态－原位红外技术,采用这一技术可以获取在催化剂表面上生成的中间化合物的特征光谱信息。根据特征峰出现的先后,峰的大小和消长以及形成的时间,可以直接地、更有论据地推断反应机理,比目前采用“黑箱”的方法优越。通过标定特征峰与表面浓度的关系,可以研究表面中间化合物生成的复杂反应网络,求出相应的动力学参数和最慢的速控步骤。利用上述技术还可以发展一种“化学捕获”法,直接证明催化剂表面存在的中间化合物。     

广义线性模型与非线性模型参数的统计推断

概述了广义线性模型(含半参数广义线性模型)与非线性模型研究的新进展,着重讨论了它们参数估计的统计推断。近年来,广义线性模型与非线性模型的研究发展迅速,有着广泛的应用前景。     

富勒烯类炭材料作为新型载体在多相催化中的应用

评述了富勒烯类新型炭材料作为金属催化剂的载体在多相催化领域中的潜在应用途径。首先概要介绍这些炭材料在均相和多相催化中一些应用实例,然后分别详细分绍C60分子化合物、单壁纳米炭管和多壁纳米炭管等富勒烯类新型炭材料的催化性能及其应用。     

QUALITATIVE AND QUANTITATIVE IDENTIFIABILITY ANALYSIS OF NONLINEAR CHEMICAL KINETIC MODELS

Identiriability analysis deals with the problem of uniqueness of the parameters when fitting a model to a set of observations. If the model is not qualitatively identifiable, then several or infinitely many parameter sets generate identical predictions of the observed quantities. Three rigorous approaches are evaluated to study qualitative identiriability of nonlinear dynamic models, with emphasis on chemical kinetic modelling. Analysis of a large variety of systems of higher-order reactions shows that under reasonable experimental conditions such models are rarely unidentifiable in the qualitative sense, although there exist well-known examples of unidentifiable models for monomolecular reaction systems. Kinetic models are, however, frequently unidentifiable in a quantitative sense, when a particular sel of error-corrupted data does not allow for obtaining reliable estimates of the parameters. In such cases the goodness-of-fit depends only on some combinations of the parameters. Performing a logarithmic transformation, the well-known principal component analysis is shown to offer an efficient method for detecting and identifying nonlinear dependences among the parameters, thereby suggesting simpler models leading to meaningful estimates     

DATA AUGMENTATION AND DYNAMIC LINEAR MODELS

Abstract. We define a subclass of dynamic linear models with unknown hyperpara-meter called d -inverse-gamma models. We then approximate the marginal probability density functions of the hyperparameter and the state vector by the data augmentation algorithm of Tanner and Wong. We prove that the regularity conditions for convergence hold. For practical implementation a forward-filtering-backward-sampling algorithm is suggested, and the relation to Gibbs sampling is discussed in detail.     

NECESSARY AND SUFFICIENT CONDITIONS FOR CAUSALITY TESTING IN MULTIVARIATE ARMA MODELS

Abstract. The necessary and sufficient conditions for Granger causality are provided. The condition is that some linear combinations of certain elements of AR matrix and certain elements of MA matrix must vanish. It is less restrictive than the condition heretofore utilized in the literature which is only sufficient in which certain elements in AR matrix as well as certain elements in MA matrix themselves are zero. A proper parsimonious parametric test procedure is also established by using the necessary and sufficient condition.     

TESTING SEPARATE TIME SERIES MODELS

Abstract. We develop simple procedures for testing the adequacy of separate time series models. The test statistics may be calculated using auxiliary regressions that are very similar to those used for calculating Lagrange multiplier test statistics. While the separate tests are designed to yield high power against separate alternatives, they are also powerful as diagnostic checks against a range of inappropriate alternatives. The small-sample properties of the separate and Lagrange multiplier tests are compared on the basis of a Monte Carlo experiment. In these experiments it is found that the separate tests are frequently more powerful than the Lagrange multiplier tests, even for alternatives against which the latter are asymptotically optimal.     

离子液体在催化反应和萃取分离中的研究和应用进展

离子液体研究已从“绿色”化学化工快速扩展到功能材料、能源、资源环境以及生命科学等领域,典型地体现了科学技术发展中的多学科交叉与综合.本文就离子液体在催化反应和萃取分离中的研究进展进行初步的总结与评述,以期为以后的研究工作提供参考.     

A LINEAR CORRELATION FOR SOLID SOLUBILITIES IN SUPERCRITICAL GASES

A previously derived equation (Jonah, 1986) for solid solubilities in supercritical gases is tested in empirically abbreviated form against experimental data on six solutes in supercritical ethylene and carbon dioxide. The solids considered are benzoic acid, 2,3- and 2,6-dimethylnaphthalene, naphthalene, phenanthrene and anthracene.

Our equation correlates these solid solubilities linearly with certain functions of pure solvent thermodynamic properties, thereby making possible the interpolation and extrapolation of sparse experimental data.     

石灰石在煤气化过程中的催化和固硫作用

基于CaO在煤气化中的催化和固硫作用,以及石灰石加热分解的性质,石灰石有可能作为煤气化过程中的催化剂和固硫剂。本文根据国内外对石灰石在煤燃烧和煤气化中作用的研究,从石灰石结构、Ca/C,Ca/S,可能的反应机理等几个方面进行了介绍和分析,并指出需进一步研究的内容。     

YULE-WALKER TYPE DIFFERENCE EQUATIONS FOR HIGHER-ORDER MOMENTS AND CUMULANTS FOR BILINEAR TIME SERIES MODELS

Abstract. In this paper we obtain difference equations for the third- and fourth-order lagged moments and cumulants when the time series {X_t} satisfies a bilinear model and is stationary up to fourth order. These equations are similar to the well-known Yule-Walker equations which are available for linear time series models.     

ON THE UNBIASEDNESS PROPERTY OF AIC FOR EXACT OR APPROXIMATING LINEAR STOCHASTIC TIME SERIES MODELS

Abstract. A rigorous analysis is given of the asymptotic bias of the log maximum likelihood as an estimate of the expected log likelihood of the maximum likelihood model, when a linear model, such as an invertible, gaussian ARMA ( p, q ) model, with or without parameter constraints, is fit to stationary, possibly non-gaussian observations. It is assumed that these data arise from a model whose spectral density function either (i) coincides with that of a member of the class of models being fit, or, that failing, (ii) can be well-approximated by invertible ARMA ( p, q ) model spectral density functions in the class, whose ARMA coefficients are parameterized separately from the innovations variance. Our analysis shows that, for the purpose of comparing maximum likelihood models from different model classes, Akaike's AIC is asymptotically unbiased, in case (i), under gaussian or separate parametrization assumptions, but is not necessarily unbiased otherwise. In case (ii), its asymptotic bias is shown to be of the order of a number less than unity raised to the power max { p, q } and so is negligible if max { p, q } is not too small. These results extend and complete the somewhat heuristic analysis given by Ogata (1980) for exact or approximating autoregressive models.     

EIGENVALUE SPECTRA AND MODAL CONTRIBUTIONS FOR COUNTERFLOW REACTOR MODELS

Counterflow reactor models fall into three classes of partial differential equations: hyperbolic, parabolic, and mixed hyperbolic-parabolic. These have been analyzed to determine the behavior of their eigenvalues and their modal contributions. Using an asymptotic analytical technique (WKB theory), hyperbolic p.d.e. systems and mixed p.d.e. systems with characteristics similar to hyperbolic systems were found to have a “defective” internal structure, making them generally undesirable for modeling or control applications requiring low-order models. Parabolic systems, or mixed systems with characteristics similar to parabolic systems, were found to be “well-behaved”. Hence, where it is possible to choose the type of model to apply to a specific reactor, the choice of the parabolic form is strongly suggested to mitigate potential structural problems.     

A TEST FOR CONDITIONAL HETEROSKEDASTICITY IN TIME SERIES MODELS

Abstract. When testing for conditional heteroskedasticity and nonlinearity, the power of the test in general depends on the functional forms of conditional heteroskedasticity and nonlinearity that are allowed under the alternative hypothesis. We suggest a test for conditional heteroskedasticity and nonlinearity with the nonlinear autoregressive conditional heteroskedasticity model of Higgins and Bera as the alternative. Standard testing procedures are not applicable since our nonlinear autoregressive conditional heteroskedasticity (ARCH) parameter is not identified under the null hypothesis. To resolve this problem, we apply the procedure recently proposed by Davies. Power and size of the suggested test are investigated through simulation, and an empirical application of testing for ARCH in exchange rates is also discussed.     

非恒温非绝热固定床反应器非均相模型及其求解

非恒温非绝热固定床反应器广泛应用于强放热的反应体系,由于传热、传质阻力的存在,使得流体中的温度、浓度和催化剂表面处不同,按拟均相二维模型求得的结果和实际情况存在较大的偏差。为此利用分层次的反应器建模思想,建立了非恒温非绝热固定床反应器的非均相二维模型,并用正交配置法对该模型进行了求解,示例给出了萘氧化成邻苯二甲酸酐的模拟结果。     

分子筛催化在工业中的新应用

分子筛择形催化能够提高生产效率并且简化工艺流程,用低成本原料生产高价值的化工产品。综述了９０年代以来分子筛择形催化剂在利用炼厂气合成乙苯、异丙苯和甲胺等工工业生产方面的最新应用。     

SPECTRAL ESTIMATION AND DECONVOLUTION FOR A LINEAR TIME SERIES MODEL

Abstract. A vector linear time series model is observed as the sum of a convolution of an unknown signal and an additive noise process. The main objective is the estimation or deconvolution of the signal when the spectra of the signal and noise processes are unknown. We prove the strong consistency of a class of nonparametric spectral estimators derived by maximizing a particular Gaussian likelihood function. We also study the mean square convergence of the finite-sample deconvolution estimators as a function of the sample length T , the filter length M and the spectral bandwidth B_T = L_T/T .     

非均相硝化反应器的最佳中试容积

在5个几何相似的具有双排蛇管的模拟硝化反应器中,测定了不同工况下液液湍流搅拌分散系统的Sauter直径和固液混合系统相两相的停留时间分布（RTD）。关联出了Sauter直径与相比、转速、搅拌浆叶直径之间的关系式,得到了固液系统流体流动模型的模型参数。由各参数随硝化反应器容积的变化规律,确定了硝化反应器的最佳中试容积。