CHF+O2反应的理论研究

为了弄清CHF与O2反应在单重态势能面(PES)上的机理,我们在B3LYP/6-311++G(d,p)水平上对该反应作了详细的理论研究。优化了反应势能面上的反应物、中间体、过渡态和产物的几何构型,并在相同水平上用内禀反应坐标法确认了中间体和过渡态之间的相关性。为了获得准确的能量,我们将B3LYP/6-311++G(d,p)方法优化得的各驻点几何构型用QCISD/6-311++G(d,p)作了单点能计算。研究发现CHF+O2反应,第一步经无势垒络合生成HFCOO,然后经过一系列的异构化和断键过程,生成P1(HCO+FO)、P2(HF+CO2)和P3(CO+HOF)。其中P1(HCO+FO)通道最缺乏竞争力,而P2(HF+CO2)通道最有优势。在产物P2和P3的生成路径中,所有的过渡态能量都低于反应物,因而该反应在低温中起着重要作用。     

苯甲基阴离子复合物结构与性质的理论研究

用G98程序在B3LYP和MP2方法上和理论上计算苯…甲基阴离子复合物以预测其构型,得4种.在考虑基组重叠误差校正基础上,得结合能,并用自然键轨道分析法讨论其相互作用.结果表明,甲基阴离子中C13与苯中的一个C原子直接相连的构型比较稳定,其结合能为-108.45 kJ/mol(B3LYP/6-31+G*)、-154.1 kJ/mol(MP2(FC)/6-311++G**).其余的构型靠碳的孤对电子与C-Hσ反键轨道作用而形成,且稳定性较差.     

噻吩与过氧化氢气相反应机理的理论研究

采用密度泛函理论的B3LYP方法,在6-311+G（d,p）基组水平上研究了C₄H₄S与H₂O₂的微观反应机理,全参数优化了反应势能面上各驻点的几何构型,振动分析和内禀反应坐标（IRC）分析结果证实了中间体和过渡态的真实性,计算所得的键鞍点电荷密度的变化情况也确认了反应过程。结果表明,反应分2步进行,主要经历了O对S的进攻、H转移以及O-O键断裂的历程,决速步骤的活化能为157.3 kJ/mol,能垒高于甲硫醇、甲硫醚和过氧化氢反应的类似步骤。     

甲硫醇、二甲硫醚、噻吩与过氧乙酸气相反应机理的理论研究

采用密度泛函理论的B3LYP方法,在6-311+G(d,p)基组水平上研究了CH_3SH、CH_3SCH_3、C_4H_4S与CH_3CO_3H的微观反应机理,全参数优化了反应势能面上各驻点的几何构型,振动分析和内禀反应坐标(IRC)分析结果证实了中间体和过渡态的真实性。结果表明,三个反应主要经历了O对S的进攻、H转移以及O-O键断裂的历程。其中噻吩反应的活化能最高,为87.9 kJ/mol,说明噻吩的氧化脱硫最困难。对于甲硫醇、二甲基硫醚、噻吩与过氧化氢反应来说,当加入乙酸做催化剂后,第一步反应的活化能皆得到大幅度的降低。     

HSS和OH反应机理的理论研究

应用量子化学计算方法研究HSS和OH的反应机理。在B3LYP/6-311+G(2df,p)水平上对HSS和OH反应过程中所有物种进行了构型优化和频率计算。采用QCISD(T)/6-311+G(3df,2p)方法的能量数据,构建了标题反应的势能剖面。结果表明,HSS和OH反应体系中存在4条通道,主通道为OH中O原子夺取HSS中H原子形成产物P1(H_2O+S_2),该通道包含3条路径其表观活化能分别为-72.15,-33.07和-31.41 kJ·mol~(-1),优势路径经过环状过渡态TS1。基于统计热力学原理,预测了稳定物种的热力学性质。     

CH3S与CH2SH自由基反应的密度泛函理论研究

用量子化学从头算和密度泛函理论(DFT)对CH3S与CH2SH自由基反应进行了研究。在B3LYP/6-311+G(d,p)水平上优化了反应通道各驻点物种(反应物、中间体、过渡态和产物)的几何构型,用内禀反应坐标(IRC)计算和频率分析的方法对过渡态结构及连接性进行了验证。在QCISD(T)/6-311++G(d,p)水平上计算了各物种的单点能,并对总能量进行了零点能校正。研究结果表明,CH3S与CH2SH反应为多通道反应,有3条可能的反应通道。反应物首先通过C-S键相互作用形成链状碳-硫偶合中间体IM1,再经过裂解和脱氢气机理生成主要产物P1(CH3SH+CH2S)和次要产物P2和P3。根据势能面分析,所有反应均为吸热反应。相对于CH3S与CH2SH,各产物能量分别为(-175.2,335.5和331.5)kJ.mol-1。     

二甲基硫醚与过氧化氢反应机理的研究及溶剂效应

采用密度泛函理论的B3LYP方法,在6-311+G(d,p)基组水平上研究了CH3SCH3与H2O2的微观反应机理,全参数优化了反应势能面上各驻点的几何构型,振动分析和内禀反应坐标(IRC)分析结果证实了中间体和过渡态的真实性,计算所得的键鞍点电荷密度的变化情况也确认了反应过程.结果表明,反应共分2步进行,主要经历了O对S的进攻、H转移以及O-O键断裂的历程.并分别考察了其在水中和甲苯的溶剂效应.结果表明,溶剂效应降低了反应的活化能,并使过渡态红外光谱蓝移.     

取代乙酸脱羧反应机理的DFT研究

运用密度泛函理论(DFT)的B3LYP方法,在6-311~(++)G(d,p)基组水平上,采用CPCM模型对水溶剂条件下4种卤代羧酸和4种羰基(氰基)羧酸在无催化剂及水催化条件下的脱羧反应机理进行了研究。结果表明,在卤代羧酸的脱羧反应中,水催化时反应比无催化剂参与时容易,其中CCl_3COOH(A)和CF_3COOH(C)脱羧(H_2O催化)所需克服的能垒分别为192.60、210.33 kJ/mol,与Belsky等的实验结果基本一致。而对于4种羰基(氰基)羧酸,无水参与时脱羧主要经六元环过渡态进行,反应的活化能分别为300.01(CH_3COCOOH)、160.02(CNCH_2COOH)、94.01(CHOCH_2COOH)、105.26(NH_2COCH_2COOH)kJ/mol,比H_2O催化时反应的活化能低。     

C6H6和SO3相互作用的理论研究（英文）

采用B3LYP和MP2方法在6-31G*、6-31+G*和6-311+G**基组下对C6H6…SO3复合物体系的4种可能结构进行自由优化,得3种。在考虑基组重叠误差校正基础上,得结合能,并用自然键轨道分析方法讨论其相互作用。结果表明,用B3LYP/6-31G*计算3种复合物的结合能分别为-17.75, -18.33, -18.80 kJ/mol,且C6H6和SO3结合时电子从苯环向SO3转移,形成电荷转移复合物,它们之间的作用包含π-p作用方式。     

气相和水相中氯代酚与单线态氧反应机理的研究

用密度泛函理论分别研究气相和水相中的6种氯代酚(2-CP,3-CP,4-CP,2,4-DCP,2,4,6-TCP和PCP)与单线态氧的反应机理。在B3LYP/6-31+G(d,p)水平上,将可能路径上的反应复合物、过渡态和产物分别全优化几何结构和计算频率,通过内禀反应坐标(IRC)的方法验证反应路径,并在B3LYP/6-311+(2df,p)水平上计算单点能。采用极化统一模型(PCM)法探索溶剂效应。结果,不论气相还是水相,1,3加成生成1个烯丙基氢过氧化物和1,4加成生成1个酮类氢过氧化物,在热力学上均是可行的,但是在动力学上前者的能垒比后者更低,是优先路径。热力学更支持在水相中反应,而动力学则相反。能垒随氯代数量的增多而升高。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.