乙烯-醋酸乙烯酯体系的汽液相平衡分子模拟

本文采用分子模拟手段对乙烯-醋酸乙烯酯体系的汽液相平衡性质进行了研究。首先,采用量化模拟方法分析了醋酸乙烯酯分子的电子特性,揭示其相互作用特点,并采用格点取样法模拟计算了醋酸乙烯酯分子对构型的分子间相互作用能,拟合了CHo=c(sp~2)原子基团的非键作用项参数;其次采用GEMC方法,在T=303.15 K,P=310 kPa、724 kPa、1138 kPa条件下对乙烯-醋酸乙烯酯二元混合物体系的汽液相平衡性质进行了模拟考察。模拟值与文献值相对偏差较小,说明采用修正后的力场可以较好地描述醋酸乙烯酯体系的汽液相平衡性质。     

乙烯在醋酸中溶解度的Gibbs系综蒙特卡罗模拟

使用Gibbs系综蒙特卡罗方法,采用TraPPE-UA力场对乙烯-醋酸体系的溶解度和液相密度进行了模拟计算。对303.15K时,45KPa、105KPa和185KPa三个压力点的模拟值与实验值进行了对比,确认了模拟方法对低于常压时的适用性。由于醋酸的缔合特性,为了修正常压及高于常压时的计算结果,使用Dmol3计算了8种醋酸二聚体的能量,并选择其中2种拟合出Lennard-Jones曲线和参数,以此为初值修正了力场参数,进行计算后与实验数据再次比较,偏差缩小至约15%~17%。使用修正后的力场,根据实际工况,对101KPa时温度从285K到395K的溶解度和密度进行了预测计算。计算结果为精馏的设计提供了参考。     

CO在碳酸二甲酯中溶解度的GEMC模拟

采用Gibbs系综蒙特卡罗模拟方法,将TraPPE联合原子力场中缺少的参数补齐。通过设置恰当的模拟参数,首先模拟计算了碳酸二甲酯纯物质的液相密度。结论表明,碳酸二甲酯纯组分的液相密度模拟值与文献数据随着温度的变化有着相同的变化趋势,相对偏差为0.10%~0.55%。在此基础之上,将TraPPE联合力场与DREIDING力场联合使用,进一步计算了CO在碳酸二甲酯中的溶解度,将模拟结果与文献数据进行了对比,相对偏差为3.20%~10.15%。模拟结论表明,改写的力场对CO在碳酸二甲酯中溶解度的模拟具有较高的模拟精确度,为采用分子模拟方法检验和预测CO和碳酸二甲酯二元体系的气液相平衡数据提供了一定的理论基础。     

二氧化碳-醋酸乙烯体系相平衡的GEMC模拟

采用吉布斯系综蒙特卡罗方法 (GEMC)来研究二氧化碳-醋酸乙烯二元组分的汽-液相平衡性质。以Tra PPE-UA力场为原始模型,采用量子化学方法构建出适用于醋酸乙烯分子的特定力场。选择适合与Tra PPE-UA力场结合使用的Tra PPE-EH力场建立二氧化碳模型,采用NPT-GEMC方法计算二氧化碳-醋酸乙烯二组分体系的汽-液相平衡性质,所得模拟结果与实验值吻合较好。在313.15 K时,二氧化碳在醋酸乙烯中摩尔分数的模拟值与实验值的相对误差范围是3.8%~7.6%;在333.15 K时,相对误差范围是3.7%~11.3%;随着压力增加误差逐渐增大,接近混合物临界区域时误差最大。模拟结果表明构建的醋酸乙烯力场具有较高的模拟精度,可用于预测醋酸乙烯体系的汽-液相平衡性质。     

苯-噻吩-NMP三元体系汽液平衡的GEMC模拟

本研究采用了吉布斯系综蒙特卡洛方法(GEMC)对苯-噻吩-NMP三元体系在101.33 k Pa、4个温度点下的汽液平衡性质进行模拟计算。采用Tra PPE-EH力场模拟苯分子和噻吩分子,用OPLS-AA力场模拟NMP分子。得到的模拟结果与实验值吻合良好,证明了Tra PPE-EH力场以及OPLS-AA力场可以共同用于三元体系汽液平衡的预测,具有兼容性。对平衡液相的径向分布函数(RDF)的分析表明,由于NMP的加入,苯和噻吩的相互作用减弱,同时平衡液相中NMP与噻吩的相互作用强于NMP与苯的相互作用,整体表现为苯和噻吩的相对挥发度的增大。模拟结果也证明了几何平均以及算数平均混合规则在预测性质相近的原子的相互作用时精度接近,可以混用。     

甘油-水二元低温保护液玻璃化转变温度的理论预测

玻璃化是牛物器官低温保存的最有效方式,玻璃化转变温度(Tg)是表征和研究低温保护液玻璃化过程的重要参数.目前,测定玻璃化转变温度最常用方法是差示扫描量热法(DSC)和动态热机械分析法(DMA).本文初次尝试利用等温等压下的分子动力学模拟预测甘油水溶液(60%,wt/%)的玻璃化转变温度.在90 K～273 K范围内,逐个温度点模拟计算体系的恒压热容(Cp)、密度(P)、无定形晶胞体积(Vcell)、特征原子的径向分布函数和氧键的形成几率等状态参数.通过这些参数随温度的变化规律和拐点,确定甘油水溶液的Tg值.分子模拟计算结果表明:模拟计算的Tg值(160.06 K～167.51 K)与DSC实验测定结果(163.60 K～167.10 K)几乎一样.可见,分子动力学模拟(MD)可以预测甘油-水二元低温保护液的玻璃化转变温度,这种方法也可推广到其他的多元低温保护液.     

水的汽液相平衡及径向分布的分子模拟研究

采用J．R．Errington等提出的固定点电荷水分子新模型,分别以Buckingham Exp-5势能结合哥伦布势能模型计算分子间的短程作用及Ewald Summation方法计算电荷间的长程作用,采用恒NVT吉布斯系综Monte Carlo模拟方法模拟了水在300K～600K下的汽液相平衡,并采用经典的恒NVT系综Monte Carlo模拟方法模拟了水在温度T=300K,ρ=1．0g／cm^3下的原子对径向分布函数。模拟结果与文献中的实验值吻合良好。本文工作为推广至更复杂水溶液体系的模拟打下了良好的基础。     

二甲醚-甲醇二元体系汽液平衡的测定与计算

在0～1.45MPa压力范围内,测定了293．15K、323．15K、353．15K、373．15K温度下二甲醚-甲醇二元体系的汽液相平衡数据。利用气相色谱检测汽液相组成,对测定数据进行了热力学计算,采用PR方程计算气相各组分的逸度系数,利用NRTL和UNIFAC法计算液相活度系数。两种不同模型计算值与实验值符合良好,汽液相平衡数据经Herington面积法校验满足热力学一致性检验。     

甲醇-环己酮二元体系汽液平衡的测定与关联

用改进的Ellis汽液平衡釜测定甲醇-环己酮二元体系常压汽液平衡数据,并校验实验数据的Herington热力学一致性,结果表明实验数据满足热力学一致性要求.以汽相组成的误差平方和作为目标函数,分别用Willson和NRTL方程关联实验数据,得两热力学方程的模型参数.汽相组成的模型计算值与实验值的平均相对偏差分别为0.56%和1.10%.     

烯烃类分子的分子力学力场及热力学性质预测

高质量的分子力学力场是准确预测分子各种性质的前提。本文借助第一性原理计算开发了新的适用于烯烃类分子的全原子力场,将所得力场计算和预测不同的热力学性质、传递性质以及气液相平衡性质。该力场不但可以准确预测分子的气相性质,且可得到和实验值吻合较好的液相热力学性质。与已有力场相比,在应用范围和精度都有明显的改进。借助分子动力学和蒙特卡洛模拟,计算密度和实验值偏差±0.01g/ml左右,蒸发焓为±0.3 kcal/mol左右,热容为±1.0 cal/mo1·K左右,热胀系数为±10~(-4)K~(-1)左右,以及粘度为±0.02 centipoise左右。     

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     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

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。