分子水平上研究地质流体的物理化学性质

Geological fluids exist in every geosphere of the Earth and play important roles in many processes of material transformations, energetic interchanges and geochemical interactions. To study the physicochemical properties and geochemical behaviors of geological fluids turn Girt to be one of the challenging issues in geosciences. Compared with conventional approaches of experiments and semi-theoretical modeling, computer simulation on molecular level shows its advantages on quantitative predictions of the physicochemical properties of geological fluids under extreme conditions and emerges as a promising approach to find the characteristics of geological fluids and their interactions in different geospheres of the Earth interior.This dissertation systematically discusses the physicochemical properties of typical geological fluids with state-of-the-art computer simulation techniques. The main results can be summarized as follows: (1) The experimental phase behaviors of the systems CH4-C2H6 and. CO2 have been successfully reproduced with Monte Carlo simulations. (2) Through comprehensive isothermal-isobaric molecular dynamics simulations, the PVT data of water hia^e been extended beyond experimental range to about 2000 K and 20 GPa and an improved equation of state for water has been established. (3) Based on extensive computer simulations, am optimized molecular potential for carbon dioxide have been proposed, this model is expected to predict different properties of carbon dioxide (volumetric properties, phase equilibria, heat of vaporization, structural and dynamical properties) with improved accuracies. (4) On the basis of the above researches of the end-members, a set of parameters for unlike interactions has been proposed by non-linear fitting to the ab initio potential surface of CO2-H2O and is superior to the common used mixing rule and the results of prior workers vs/Ith remarkable accuracies, then a number of simulations of the mixture have been carried out to generate data under high temperatures and pressures as an important complement to the limited experiments. (5) With molecular dynamics simulations, various structural, dynamical and thermodynamical properties of ionic solvations and associations have been oomprehensively analyzed, these results not only agree well with experimental data and first principle calculation results, but also reveal some new insights into the microscopic ionic solvation and association processes.

Total analytical method for Radix astragali extract using two-binary multi-segment gradient elution liquid chromatography

There is an urgent need for thorough analysis of Radix astragali, a widely used Chinese herb, for quality control purposes. This paper describes the development of a total analytical method for Radix astragali extract, a multi-component complex mixture. Twenty-four components were separated step by step from the extract using a series of isocratic isopropanol-methanol elutions, and then 42 components were separated similarly using methanol-water elutions. Based on the log k(w) and -S of the 66 components obtained from the above procedure and the optimization software developed in our laboratory, an optimum elution program consisting of seven methanol-water segments and four isopropanol-methanol segments was developed to finish the task of analyzing the total components in a single run. Under optimized gradient conditions, the sample of Radix astragali extract was analyzed. As expected, most of the components were well separated and the experimental chromatogram was in a good agreement with the predicted one.

Resolution deterioration in emission electron microscopy due to object roughness

In the present paper a general analytic expression has been obtained and confirmed by a computer simulation which links the surface roughness of an object under study in an emission electron microscope and it's resolution. A quantitative derivation was made for the model case when there is a step on the object surface. It was shown that the resolution is deteriorated asymmetrically relative to the step. The effect sets a practical limit to the ultimate lateral resolution obtainable in an emission electron microscope.

弈棋问题解决启发式的元策略模型

Problem solving is one of the basic processes of human cognition and heuristic strategy is the key to human problem solving, hence, the studies on heuristic strategy is of great importance in cognitive psychology. Current studies on heuristics in problem solving may be summarized as follows: nature and structure of heuristics, problem structure and representation, expert knowledge and expert intuition, nature and role of image, social cognition and social learning. The present study deals with the nature and structure of heuristics. The Solitaire problem was used in our the experiments. Both traditional experimental method and computer simulation were used to study the nature and structure of heuristics. Through a series of experiments, the knowledge of Solitaire problem solving was summed up, its metastrategy is worked out, and then the the metastrategy by computer simulation and experimental verification are tested.

风险认知的心理学研究

This research uses a multitask, multimodel approach to probe teh problem of risk perception. It consists of three parts. First, the research of risk perception in general social circumstances, the aim is to collect information about the risk perceived by popular; Secondly, the research of risk perception under working circumstances, in the form of questionaire on enterprises; Thirdly, an experimental test of risk cognitive strategies by computer simulation, that is 2x2x3 design of laboratory research based on questionaire.