An application of least-squares inverse analysis in kinetic interpretations of hydrous pyrolysis experiments     

S?ren B. Nielsen  Tanja Barth 《Mathematical Geology》1991,23(4):565-582

A least-squares inverse method is applied to the estimation of optimum kinetic parameters with statistical error bounds from concentration data obtained in isothermal hydrous pyrolysis experiments. The inverse method requires the specification of a data-parameter relationship (e.g., classical kinetic theory), the prior covariance matrices of data and parameter errors, as well as the prior central estimates of data and parameters. The reaction scheme considered is the common case of kerogen breakdown by Gaussian-weighted independent parallel first-order reactions and bitumen cracking by a single first-order reaction. The nonlinearity of the problem is reduced by a logarithmic transformation, which suggests a parameterization in terms of logarithmic concentrations, activation energies, and logarithmic Arrhenius factors. The linearized variance analysis is valid for the case studied, and the posterior covariance matrix reveals which parameters are constrained by the data. We find that the statistical errors in the average activation energy and the associated Arrhenius factor are strongly correlated. Hence, the parameters which determine the temperature dependence of the reaction rate have not been resolved independently. Furthermore, the kinetic results are very sensitive to the presence of a distribution of activation energies in kerogen breakdown. This distribution is not constrained by the data. As a consequence, neglecting the consideration of distributions of activation energies results in activation parameter values which are much too low. This is the major reason for the commonly encountered discrepancy between kinetic parameter values obtained from hydrous pyrolysis and micropyrolysis experiments, respectively.  相似文献   

陕西丹凤秦岭群石榴子石变质结晶动力学研究     

王河锦 《矿物学报》1991,11(3):258-266

本文运用晶体大小分布理论对陕西丹凤秦岭群石榴子石进行了变质结晶动力学的研究,通过对石榴子石在岩石中出现的频率及其大小值的系统测定,有关变质结晶动力学的分析计算,最终得出了丹凤秦岭群石榴子石的变质结晶初始成核密度、成核速度、晶体生长速度、生长时间及冷却过程中体积转移量等诸动力学要素,并从晶体大小分布研究中获得了多期复杂变质这一与地质事实一致的重要地质信息。  相似文献   

New aspects on the chemistry of aluminum in soils   总被引：2，自引：0，他引：2  

Gerhard Furrer 《Aquatic Sciences - Research Across Boundaries》1993,55(4):281-290

Dissolution kinetics of minerals can be significantly inhibited by re-adsorbed aluminum. As a consequence of neutralization, polynuclear Al species may be formed in soil solutions. While re-acidification leads to decomposition of the polymers, further neutralization induces the formation of aggregates. The complexation of heavy metal ions with dissolved and aggregated Al polymers is illustrated as a potential factor influencing the chemical speciation of heavy metals in soils.  相似文献   

集安岩群石榴石成分特征及其动力学意义     

Hu Daqian  Xu Xuechun 《吉林大学学报(地球科学版)》1994,(4)

集安岩群石榴石以富铁为特征，均属铁铝榴石。形成于高角闪岩相的石榴石成分比较稳定，＜ＦｅＯ＞平均含量３２．２０％，ＭｇＯ５．１７％，Ｘ＿（Ｍｇ）平均值０．２３；结晶于低角闪岩相的石榴石（ＦｅＯ＋ＭｇＯ）含量３３．５０％，（ＭｎＯ＋ＣａＯ）６．９１％。石榴石微区成分不均匀，晶体内具有一些微区成分环带，这种环带不是各进变质作用阶段ｐ－Ｔ条件平衡或近平衡的产物。石榴石边缘存在着明显的扩散环带，表现为晶体边缘相对晶体核部，Ｃａ含量和＜ＦｃＯ＞含量增高，ＭｇＯ含量降低，Ｘ＿（Ｍｇ）值变小，反映本区变质峰期后经历的是一个近等压冷却的地质动力学过程。  相似文献   

生油岩热解生烃潜力及生烃动力学研究     

查明  赵永军  毛超林  周绍强 《地质论评》1994,40(7):63-69

利用岩石评价仪(R0cK EVAL I)对某凹陷30块生油岩进行了热解生烃和生烃动力学研究。在热解实验中，用类型指数、生烃潜量、最大热解峰温Tmax、等指标对上侏罗统3个层位的生油岩进行了母质类型、成熟度和生烃能力评价，结果表明，母质类型好、有机质丰富的未成熟生油岩的热解生烃量要比相同的已成熟生油岩高得多，说明选择未成熟生油岩热解对评价其生油能力的重要性。在对另2个未成熟生油岩的热解模拟实验中，得到了生烃率与温度之间的关系，并由此计算了生油岩的表观活化能、频率因子等动力学参数。  相似文献   

Probabilistic modeling of aerated lagoons: A comparison of methodologies     

R. Leduc  S. Ouldali 《Stochastic Environmental Research and Risk Assessment (SERRA)》1990,4(1):65-81

Two stochastic models are developed to describe the BOD output (i.e. effluent) variation of facultative aerated lagoons in series. One of the models uses the uncertainty analysis (UA) technique and the other is based on the moment equation solution methodology of stochastic differential equations (SDE's). The former considers a second-order approximation of the expectation (SOAE) and a first-order approximation of the variance (FOAV). The SDE model considers that output variability is accounted for by random variations in the rate coefficient. Comparisons are provided. Calibration and verification of the two models are aciieved by using field observations from two different lagoon systems in series. The predictive performances of the two models are compared with each other and with another SDE model, presented in a previous paper, that considers input randomness. The three methods show similar predictive performances and provide good predictions of the mean and standard deviation of the lagoon effluent BOD concentrations and thus are considered as appropriate methodologies.  相似文献   

Autogenic and allogenic denudation in carbonate karst by the multiple basin method: An example from Svartisen,North Norway     

Stein-Erik Lauritzen 《地球表面变化过程与地形》1990,15(2):157-167

In carbonate karst basins, adequate denudation rates are difficult to estimate when there are allogenic inputs. It is shown that the common practice of correcting for allogenic input by Corbel's modified formula leads to erroneous results unless the karst ratio is very high. When choosing small basins that are subsets of each other, assumptions of hydrologic and lithologic uniformity may be satisfied. Then the autogenic and allogenic components of the denudation may be calculated by a linear model of uniform mixing. The model was tested in a subarctic stripe karst in North Norway, yielding an autogenic denudation rate of 32.5 ± 10.2 mm ka^?1. The mean annual runoff is 2600 mm. The result is supported by independent denudation rates from comparable areas, micro-erosion meter data as well as the total post-glacial corrosion deduced from pedestal and vein heights.  相似文献   

Kinetic Parameters of Methane Generated from Source Rocks in the Kuqa Depression of Tarim Basin and Their Application   总被引：2，自引：0，他引：2  

LI Xianqing  XIAO Xianming  MI Jingkui  TANG Yongchun  XIAO Zhongyao  LIU Dehan  SHEN Jiagui  YANG Yunfeng  WANG Yan  DONG Peng 《《地质学报》英文版》2008,82(1):154-163

In a thermal simulation experiment of gold tubes of closed-system, calculating with the KINETICS and GOR-ISOTOPE KINETICS software, kinetic parameters of gas generation and methane carbon isotopic fractionation from Triassic-Jurassic hydrocarbon source rocks in the Kuqa depression of Tarim Basin are obtained. The activation energies of methane generated from Jurassic coal, Jurassic mudstone and Triassic mudstone in the Kuqa Depression are 197-268 kJ/mol, 180-260 kJ/mol and 214-289 kJ/mol, respectively, and their frequency factors are 5.265×10^13 s^-1, 9.761×10^11 s^-1 and 2.270×10^14 s^-1. This reflects their differences of hydrocarbon generation behaviors. The kinetic parameters of methane carbon isotopic fractionation are also different in Jurassic coal, Jurassic mudstone and Triassic mudstone, whose average activation energies are 228 kJ/mol, 205 kJ/mol and 231 kJ/mol, respectively. Combined with the geological background, the origin of natural gas in the Yinan-2 gas pool is discussed, and an accumulation model of natural gas is thus established. The Yinan- 2 gas is primarily derived from Jurassic coal-bearing source rocks in the Yangxia Sag. Main gas accumulation time is 5-0 Ma and the corresponding Ro is in the range from 1.25 %-1.95 %. The loss rate of natural gas is 25 %-30 %.  相似文献   

Comparative studies on phosphorus uptake and growth kinetics of the microalga Tetraselmis subcordiformis and the macroalga Ulva pertusa     

Nan Chunrong  Dong Shuanglin 《中国海洋大学学报(英文版)》2004,3(1):56-59

Short-term uptake experiments and long-term semicontinuous culture experiments were performed under the condition of phosphorus (P) limitation to estimate and compare the P uptake and growth kinetics of the microalga Tetraselmis subcordiformis and the macroalga Ulva pertusa. Two new parameters, the maximum specific uptake rate (V _m ^sp ) and the maximal growth efficiency (β), are introduced to achieve uniformity for the comparison of nutrient uptake and growth efficiency between microalgae and macroalgae. T. subcordiformis possesses 3 times lower half saturation uptake constant, 4 times higher maximal growth rate and 20 times higher maximum specific uptake rate than U. pertusa, while U. pertusa possesses 4 times higher maximal growth efficiency than T. subcordiformis.  相似文献   

Third Integral and the Dynamics of the Galaxy in the Neighborhood of the Sun     

A. M. Boichenko 《Astrophysics》2004,47(1):134-142

Observational data on the dynamics of stars in the neighborhood of the sun indicate the existence of a third integral besides the integrals of the angular momentum and energy. The Poincaré integral is proposed as a third integral. The consequences of this assumption are derived and compared with available astrophysical data.  相似文献