高温高压下H2O-CH4体系PVTx性质的分子动力学模拟研究

Geological fluids are important components in the earth system. To study thephysical chemistry properties and the evolution of fluid system turns out to be one of the most challenging issues in geosciences. Besides the conventional experimental approaches and theoretical or semi-theoretical modeling, molecular level computer simulation(MLCS) emerges as an alternative tool to quantificationally study the physico-chemical properties of fluid under extreme conditions in order to find out the characteristics and interaction of geological fluids in and around earth. Based on our previous study of the intermolecular potential for pure H2O and thestrict evaluation of the competitive potential models for pure CH4 and the ab initio fitting potential surface across H2O-CH4 molecules in this study, we carried out more than two thousand molecular dynamics simulations for the PVTx properties of pure CH4 and the H2O-CH4 mixtures. Comparison of 1941 simulations with experimental PVT data for pure CH4 shows an average deviation of 0.96% and a maximum deviation of 2.82%. The comparison of the results of 519 simulations of the mixtures with the experimental measurements reveals that the PVTx properties of the H2O-CH4 mixtures generally agree with the extensive experimental data with an average deviation of 0.83% and 4% in maximum, which is equivalent to the experimental uncertainty. Moreover, the maximum deviation between the experimental data and the simulation results decreases to about 2% as temperature and pressure increase,indicating that the high accuracy of the simulation is well retained in the high temperature and pressure region. After the validation of the simulation method and the intermolecular potential models, we systematically simulated the PVTx properties of this binary system from 673 K and 0.05 GPa to 2573 K and 10 GPa. In order to integrate all the simulation results and the experimental data for the calculation of thermodynamic properties, an equation of state (EOS) is developed for the H2O-CH4 system covering 673 to 2573 K and 0.01 to 10 GPa. Isochores for compositions < 4 mol% CH4 up to 773 K and 600 MPa are also determined in this thesis.

南襄盆地泌阳凹陷断裂斜坡带构造特征与油气成藏

The faulted slope zone of Biyang depression, a multiple hydrocarbon accumulation zone lying in a rich oil depression of Nanxiang basin, is a structural-sedimentary compounded slope, which is developed in Yanshanian period and has an area of 500 km2. From the ‘bottom up’, the developed strata may be divided into Yuhuangding formation in Neogene, Dacang Fang, Hetao-yuan plus Liaozhuang formations and Fenghuangzheng plus Pingyuan formation in Neogene, while Hetao-yuan formation is the main hydrocarbon-bearing target. Because of transtensional stress fields formed by persistent action of large-scale faulting in the south of the depression, sedimentary differential compaction in different stages, and tectonic inversion in later developing stage of the depression, a series of nose structure zones cut by different strike faults are developed. Therefore, the reservoir migration and accumulation are controlled by the complex faulted-nose structural zone, reservoir types are dominated by faulted-noses, faulted-blocks and fault-lithology, while lithology and stratigraphic unconformable reservoirs are locally developed. In combination with demands of practical production, applying with a new research approach of systematology and a combination with dynamic and static modes, guided by modern petroleum geologic theory, and based on previous data and studies, new techniques, methods of geophysical exploration, various computer simulation and forecasting techniques are applied in the new research of this paper. Starting from the structural features and formation mechanism, the forming mechanism of faulted structure, conditions and controlling factors of hydrocarbon accumulation, as well as various space-time allocation relationships in the process of accumulation are analyzed in the research. Besides that, the hydrocarbon migration, accumulation mechanism and dynamic evolution process are also discussed in the paper. Through the research, the accumulation rule of the faulted slope zone in faulted lake basin, the distribution and enrichment regularity of different reservoir controlling factors are systematically summarized. The summarizations indicate that the faulted slope is a favorable orientational zone, hydrocarbon is accumulated in nose structures and enriched in the main body of nose structures, faulted transformation zone and the ascent direction of laddering faulted blocks, the faults are the controlling factors, hydrocarbon accumulation zones controlled by fault-lithology are distributed along the faulting direcion. In the end, hydrocarbon migration and accumulation models of complex faulted-nose blocks are established. 1) Down cut model—‘flank-sheet’: the hydrocarbon is migrated like ‘sheet’ along a series of faults with parallel distribution and accumulated in the flank of nose structures; 2）Cross cut --‘axis-string’ model: the hydrocarbon cutting across the faults is migrated like ‘string’ and accumulated in the axis of nose structures. In view of different distribution models, reservoir forming combination patterns are divided and hydrocarbon reservoir evaluation exploration is carried out, which achieves good results in application. Key words: faulted slope zone; migration and accumulation model; reservoir controlling mechanism; reservoir-forming combination

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.