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The present work used a methane-air mixture chemical kinetics scheme consisting of 119 elementary reaction steps and 41 chemical
species to develop a simplified combustion model for prediction of the knock in dual fuel engines. Calculated values by the
model for natural gas operation showed good agreement with corresponding experimental values over a broad range of operating
conditions.
Project (No. 50106014) supported by the National Natural Science Foundation of China 相似文献
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反应性溶质运移机理和模拟是地下水污染防治的前提和基础.为了考察化学反应和水流条件对溶质运移的影响,本文设计了承压含水层物理模型,以苯胺和1,2-萘醌-4-磺酸钠化学反应为例,开展了双分子化学反应条件下不同流速溶质运移实验和模拟研究,得到主要结论如下：（1）利用变系数二级反应率改进的ADRE模型能够较好地模拟在3种不同流速下双分子反应性溶质运移行为,峰值浓度相对误差分别为4.5％、5.0％及10.1％,模型可行,且模拟精度较高.（2）随着流速增大,模型参数m减小,而β0则增大.（3）模型对参数m值变化最敏感,其次是β0值,较不敏感的是弥散系数D.（4）随着流速增大,反应物和产物穿透曲线的不规则性加强,存在较明显的“拖尾”现象,今后需要进行机理方面的研究. 相似文献
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María del Mar Aragón Antonio Navarrete 《International Journal of Science Education》2013,35(12):1960-1984
This article analyzes the relationship between pupils’ level of understanding of the analogies proposed in class while working with a model of chemical change and their competence at constructing a coherent verbal discourse of that model in both its macroscopic and submicroscopic representations. The study participants were 35 pupils in their 3rd year of compulsory secondary education (14–15 years of age) who had been studying chemical change for several weeks in their subject of Physics and Chemistry. The results suggested that the pupils generally understood the proposed analogies quite well, and that a good proportion of them assimilated adequately the verbal discourse inherent in the proposed model of chemical change. There was also a statistically significant association between modeling and analogical thinking. In particular, the pupils with greater understanding of the analogies being considered were also those who tended to show a greater ability to verbalize the model of chemical change and reason with it when solving the tasks they had been set. These results concur with the literature by suggesting that a link exists between analogical thinking and modeling, and that learning with analogies has a positive influence on the construction of the chemical change model. 相似文献
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Yun-jian Zhang Qiang Li Yu-xiu Zhang Dan Wang Jian-min Xing 《Journal of Zhejiang University. Science. B》2012,13(2):103-110
Succinic acid is considered as an important platform chemical. Succinic acid fermentation with Actinobacillus succinogenes strain BE-1 was optimized by central composite design (CCD) using a response surface methodology (RSM). The optimized production
of succinic acid was predicted and the interactive effects between glucose, yeast extract, and magnesium carbonate were investigated.
As a result, a model for predicting the concentration of succinic acid production was developed. The accuracy of the model
was confirmed by the analysis of variance (ANOVA), and the validity was further proved by verification experiments showing
that percentage errors between actual and predicted values varied from 3.02% to 6.38%. In addition, it was observed that the
interactive effect between yeast extract and magnesium carbonate was statistically significant. In conclusion, RSM is an effective
and useful method for optimizing the medium components and investigating the interactive effects, and can provide valuable
information for succinic acid scale-up fermentation using A. succinogenes strain BE-1. 相似文献
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Yong NIE ;Xiao-jiang LIANG ;Mei-zhen LU ;Feng-wen YU ;Da-yong GU ;Min MIN ;Jian-bing JI 《浙江大学学报(A卷英文版)》2014,15(7):540-546
研究目的：研究方法：重要结论：确定氢氧化钠溶液化学吸收硫酰氟的传质反应动力学区域,建立增强因子模型。研究气液传质测定设备双搅拌釜中氢氧化钠溶液化学吸收硫酰氟的过程,并结合实验研究与理论分析建立了增强因子模型。基于氢氧化钠溶液化学吸收硫酰氟过程的实验研究,确定了氢氧化钠溶液化学吸收硫酰氟的传质反应动力学区域为快速拟一级反应。得到了298K下其二级反应速率常数为1．44m3／（mol·s）,并建立了增强因子模型E=68．08CBL1/2,为脱除熏蒸后残留硫酰氟的工业化应用提供了理论依据。 相似文献
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A reduced chemical kinetic model （44 species and 72 reactions） for the homogeneous charge compression ignition （HCCI） combustion of n-heptane was optimized to improve its autoignition predictions under different engine operating conditions. The seven kinetic parameters of the optimized model were determined by using the combination of a micro-genetic algorithm optimization methodology and the SENKIN program of CHEMKIN chemical kinetics software package. The optimization was performed within the range of equivalence ratios 0.2-1.2, initial temperature 310- 375 K and initial pressure 0, 1-0.3 MPa, The engine simulations show that the optimized model agrees better with the detailed chemical kinetic model （544 species and 2 446 reactions） than the original model does. 相似文献
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四川盆地紫色土小流域土壤的可蚀性 总被引：1，自引：0，他引：1
为揭示不同土地利用方式和植被类型对紫色土壤可蚀性的影响,调查和测试了紫色土丘陵区3个典型小流域内林地、园地和旱耕地的表层土壤（0-20 cm）的理化性质,并利用EPIC公式计算了土壤可蚀性K值,结果表明：样地表层土壤（0-20 cm）可蚀性K值大小顺序依次是：SP4〉SP7〉SP5〉SP2〉SP6〉SP3〉SP1;除全磷与K值相关性较小外,K值与其他影响因子达到了显著（极显著）相关;K值与各影响因子之间的相关程度：有机碳〉砂粒〉粉粒=黏粒〉全氮〉全磷。因此,提高有机碳含量,降低化肥的使用量,促进土壤团聚体形成,增加团聚度,是增加紫色土抗蚀性能的重要途径。 相似文献
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从新课程理念看化学微格教学中的“提问技能” 总被引：2，自引：0，他引：2
“提问技能”是微格教学的教学技能之一,大量的教学实践表明,加强化学微格教学中“提问技能”的教学和训练能有效解决师范生课堂教学中在处理教材、组织课堂教学、衔接各知识点或各知识块等方面的薄弱环节,使化学微格教学的训练更有针对性、更有效。尝试从新课程对未来教师教学专业素养的要求角度,审视化学微格教学中“提问技能”在培养师范生教学技能方面的教学价值和教学策略。 相似文献
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The boiling and melting points of a pure substance are characteristic physical constants of that substance in its pure state.
Although it is not possible to predict these physical constants for a given substance, it is, however, possible to rationalize
these values on a relative basis for given substances, taking into account the type of chemical bonding, the intermolecular
forces and other factors.
S Prahlada Rao is an R & D consultant for chemical industries with teaching as a hobby.
Shravan Sunkada is a 5th year student at Indian Institute of Technology, Bombay, pursuing a dual degree programme in Material
Science and Metallurgical Engineering. 相似文献
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通常,教科书及各种化学手册中给出的离子标准生成焓都是相对于氢离子而言的,是相对值。本文将给出水溶液中离子的绝对标准生成焓。 相似文献
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明栋才 《四川师范学院学报》2008,(2):69-72
价值取向日益多元化的今天。对榜样教育提出了严峻的挑战。它要求对各种价值观念进行整合。实现主体价值、主导价值和主流价值的统一。另外,在具体措施上,榜样教育应该更加灵活多样。 相似文献
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应用MM+分子力学法对24个CCK受体拮抗剂类似物进行结构优化,然后应用量子化学AM1法计算了24个CCK受体拮抗剂类似物的部分量化参数,并通过逐步回归分析方法建立了量化指数与CCK受体拮抗剂活性之间的定量相关模型,取得了良好的结果,其模型相关系数为R=0.886;继以留一法(Leave-one-out,LOO)进行交互检验,复相关系数为R2cv=0.539,说明定量相关模型具有良好的稳定性和预测能力.发现CCK受体拮抗剂的活性部位主要在分子的A、B环及其支链C21和N20上. 相似文献
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The authors of the current chemistry curriculum—implemented in Grade 12 in France—provided a criterion of change allowing prediction of direction of chemical changes and pointed out the difference to be made between experimental facts and models. A study analysing part of the curriculum content and the effects of teaching this content on students’ reasoning was conducted. The content analysis presents the functioning of the thermodynamic model, which highlights the links to be made between the experimental situation and the model when predicting the direction of a chemical change. This functioning specifies the role of the chemical equation and that of the criterion of change (comparing the reaction quotient to the equilibrium constant) and stresses the crucial points that may lead to misunderstandings. Written tests were administered to students after teaching them to determine how they predicted the direction of a chemical change, and whether they made a relevant choice between using the chemical equation and using the criterion of change and a clear distinction between the experimental situation and the thermodynamic model. Few students had a good understanding of the respective roles of the criterion and the chemical equation. A majority used the criterion to predict the direction of chemical changes relevantly, but correct answers were not widespread. Two particular mistakes, the modification of the expression of the reaction quotient and the prediction of a change despite a missing reactant, revealed that students do not properly understand the difference and the relationship between the experimental situation and the thermodynamic model. 相似文献
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Using a sample of 464 adolescents from Vizcaya, Spain, the aim of this study is to identify and analyse the values they perceived from their favourite TV character. The data were collected in person by means of two instruments: the Val-TV 0.2 questionnaire, based on the Schwartz model, and a personal essay, out of which 50 were randomly selected, to identify values perceived through the analysis of the essays, based on the Hall-Tonna model. The quantitative results show that adolescents perceive values related to hedonism, benevolence and self-direction in their favourite TV character. These values could be associated with qualitative values related to fun, belonging and the search for one’s own autonomy. The values perceived to a lesser extent from both perspectives are related to security, conformity and tradition. The conclusions support the relevance of the Hall-Tonna model for improving the understanding of values perceived by adolescents through the medium of television. 相似文献
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Felicity Haynes 《Educational Philosophy and Theory》1989,21(2):12-22
It is obvious that the values of women differ very often from the values which have been made by the other sex. It is the masculine values that prevail.
Virginia Woolf
A Room of One's Own
Getting hold of the difficulty deep down is what is hard. Because if it is grasped near the surface, it simply remains the difficulty it was. It has to be pulled out by the roots, and that involves our having to think about these things in a new way. The change is as decisive as for example, that from the alchemical to the chemical ways of thinking. The new way of thinking is what is so hard to establish.
Wittgenstein
Culture and Values 相似文献
Virginia Woolf
A Room of One's Own
Getting hold of the difficulty deep down is what is hard. Because if it is grasped near the surface, it simply remains the difficulty it was. It has to be pulled out by the roots, and that involves our having to think about these things in a new way. The change is as decisive as for example, that from the alchemical to the chemical ways of thinking. The new way of thinking is what is so hard to establish.
Wittgenstein
Culture and Values 相似文献
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引进影响化合物化学键型的两个主要参数a与b．分别为电荷半径比之和(∑(Z／r))与电负性之差(△X1)，从而建立了化合物分类判别的模糊数学模型；该模型可以比较好地判别化合物的化学键型，分辨率达到了93％。 相似文献