Knock prediction for dual fuel engines by using a simplified combustion model

INTRODUCTIONDuetodwindlingfueloilreservesandthedesireforreducedpollutantemissions,naturalgas,whichisdominantlycomposedofmethane,hasbeennowwidelyusedasanalternativefuelininternalcombustionengines .Aconventionaldieselenginecanbeconvertedwithoutexcessiveincr…     

承压含水层中反应性溶质运移实验与模拟研究——以苯胺和1,2-萘醌-4-磺酸钠为例

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.     

Optimization of succinic acid fermentation with Actinobacillus succinogenes by response surface methodology (RSM)

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.     

建立面向本科生的开放性化学实验室改革传统化学实验教学模式的探讨与实践

以建立面向本科生的开放性化学实验室为起点，通过改革传统的化学实验教学方法、实验内容、实验时间探索传统化学实验教学模式的改革，建立起以教师为主导，以学生为中心，实验内容具有探索性，学生对实验时间有主导性，实验教学能激发学生科研热情的新型教学和科研相结合的化学实验教学模式。     

Contributions of Learning Through Analogies to the Construction of Secondary Education Pupils’ Verbal Discourse about Chemical Change

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.     

Optimization of a Reduced Chemical Kinetic Model for HCCI Engine Simulations by Micro-Genetic Algorithm

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.     

氢氧化钠溶液吸收硫酰氟的传质反应动力学

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。     

四川盆地紫色土小流域土壤的可蚀性

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。     

应用量化参数研究CCK受体拮抗剂的结构与活性的相关性

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.     

Analysis of the values perceived by adolescents through television viewing. Values perceived by adolescents through TV viewing / Análisis de los valores percibidos por los adolescentes en el medio televisivo. Valores percibidos por adolescentes en la TV

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.     

联苯型大环化合物的~1HNMR谱研究

本文报道了联苯型[11]及[17]环系大环化合物1—3的合成，归属了化合物1～3的1HNMR谱图的质子化学位移值，由公式推导的化合物1～3的联苯中苯环质子的化学位移的计算值与其实测值基本一致，但环上亚甲基质子的化学位移值的计算值与实测值有一定的差值，表明大环上N原子所连取代基的吸电子效应强及小环的亚甲基质子的化学位移值大。     

On equitable cake-cutting, or: caring more about caring

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     

模糊数学在化合物分类判别中的应用

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％。     

The Transfer of Chemical Knowledge: The Case of Chemical Technology and its Textbooks

This paper is a study of textbooks in chemical technology in Sweden during the industrialisation in the 19th century. In this period, teaching in technological education in general became more and more founded on science. However, there existed very few textbooks in chemical technology, and it is argued that the reason was that the essentials of the knowledge used for developing chemical industry were of a tacit and local character. Such knowledge could only with difficulty be transferred through textbooks with scientific ambitions. Thus the textbooks written or translated by scientists were not as widely used as the ones written or translated by chemical engineers. The usefulness of the latter group can be explained by the fact that they had been adapted to local circumstances, and expressed generalisations, not as scientific laws, but as rules of thumb. Finally, a model for the diffusion of knowledge is suggested, by which the role of textbooks in chemical technology better can be understood.     

Logical positivism as a tool to analyse the problem of chemistry's lack of relevance in secondary school chemical education

Secondary school chemical education has a problem: namely, the seeming irrelevance to the pupils of chemistry. Chemical education prepares pupils for participation in society. Therefore, it must imply a model of society, of chemistry, and of the relation between them. In this article it is hypothesized that logical positivism currently offers this model. Logical positivism is a philosophy of science that creates a divide between science and society. It is therefore further hypothesized that the adoption of logical positivism causes chemistry's lack of relevance in chemical education. Both hypotheses could be confirmed by an analysis of a grade nine course.     

论德州市化工教育与化工企业的合作与发展

通过分析目前德州市化工企业从业人员的学历构成情况,结合德州学院化工技术人才的培养能力,拟定了加强校企合作促进德州市化工教育和化工企业共同发展的规划,提出了化工专业人才培养的目标、模式和途径.     

Values in Science: An Educational Perspective

Science is not value-free, nor does it provide the only model of objectivity. Epistemic values guide the pursuit and methods of science. Cultural values, however, inevitably enter through individual practitioners. Still, the social structure of science embodies a critical system of checks and balances, and it is strengthened by a diversity of values, not fewer. Science also exports values to the broader culture, both posing new values- questions based on new discoveries, and providing a misleading model for rational decision-making. Science teachers who understand the multi-faceted relationship between science and values can guide students more effectively in fully appreciating the nature of science through reflexive exercises and case studies.     

从新课程理念看化学微格教学中的“提问技能”

“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。     

Expectancy-value theory of achievement motivation: A developmental perspective

I consider Eccles et al.'s (1983) expectancy-value model of achievement performance and choice from a developmental perspective, by examining how recent research on the development of young children's competence beliefs, expectancies for success, subjective task values, and achievement goals can be incorporated into the model. The kinds of change in children's achievement beliefs considered include change in the factor structure of children's competence beliefs and values; change across age in the mean level of those constructs; and change in children's conceptions of ability beliefs and subjective values. I also discuss how achievement goals are conceptualized in this model, and how goals are conceived by other current motivation researchers. Changes in the nature of relations among competence beliefs, subjective task values, achievement goals, and achievement behaviors also are considered.     

Making sense of boiling points and melting points

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.