影响烷基芳烃黏度的内在结构因素探究

利用多种分子模拟方法对78种不同结构烷基芳烃分子分别计算了331种微观结构参数(包括前线轨道能量、电荷分布、表面积、偶极矩电子结构参数、几何结构参数和分子拓扑指数)。采用遗传算法(GFA)将这些微观结构参数与烷基芳烃的100℃黏度进行回归分析,构建烷基芳烃100℃黏度与其分子结构参数之间的定量关系方程。方程相关系数平方为0.935,交叉检验相关系数平方为0.921,具有较高的可靠性和预测能力。该方程揭示了烷基芳烃的前线轨道能量间隙、分子体积和可旋转化学键数量是影响其100℃黏度高低的主要结构因素。烷基芳烃前线轨道能量间隙越窄,黏度越高;分子尺寸越大,黏度越高;可旋转化学键越少,黏度越高。依据这三个结构参数,利用构建的定量关系方程,能够对烷基苯、烷基萘等芳烃的100℃黏度进行较为准确地预测,对于设计与优化具有理想黏度值的烷基芳烃基础油具有一定的指导意义和价值。     

含氮化合物碱性的QSAR研究

应用Materials Studio4.2计算38个含氮化合物的结构参数,对其碱性做QSAR研究.使用遗传函数算法(genetic function approximation,GFA),从前线分子轨道能量、偶极矩、部分电荷、分子表面积、分子体积等30个反映分子微观特征和溶剂化效应的结构参数中,筛选出主要的结构参数,建立出含氮化合物碱性-结构参数定量关系方程.所建方程的关联系数r2=0.951,交叉相关系数CV-r2=0.930,并且应用方程估算测试样本的碱性,其预测值与实验值基本一致,表明建立的QSAR方程具有较好的拟合度和较强的预测能力.分析QSAR方程各参数对含氮化合碱性影响表明,分子的最高占据轨道能量(HOMO)、偶极矩、氮原子上的电荷以及表示溶剂化效应的参数,是影响碱性的主要结构因素.HOMO能量反映分子供电子能力,能量越高,越易供给电子,碱性越强.分子偶极矩越大、氮原子上的负电荷越多,都使碱性增强.方程中引入电介质能量,说明溶剂化效应对含氮化合物碱性有一定的影响;电介质能量越大,溶质一溶剂的相互作用可能降低溶质分子的稳定性,使含氮化合物的碱性增强.     

乙二胺缩3,5-二氯水杨醛的合成、表征及量子化学计算

本文用乙二胺与水杨醛衍生物在非水相中合成了一种新的双希夫碱配体,并通过元素分析、核磁、质谱和红外等方法进行了表征。采用Gaussian 03在DFT/B3LYP水平下进行理论研究。计算出分子总能量TE、分子最高占据轨道能E_(HOMO)、分子最低空轨道能E_(LUMO)、标准焓H~θ、标准自由能G~θ、恒容热熔Cv~θ、标准熵S~θ、零点能E_0、分子偶极矩μ、前线轨道能量差△E等热力学参数。优化了几何构型模拟出分子的部分重要键长((?))、键角(°)、二面角(°)等结构参数。经过Mulliken布居分析得到了原子的净电荷分布。计算出原子轨道对前线分子轨道的贡献(%)。通过对热力学参数、结构参数、原子净电荷布局和原子轨道对前线分子轨道贡献的总体探讨,表明目标分子具有较好的空间结构和较强的配位能力,是一个良好的配体;并且,它的生物活性很强,可以进一步进行抑菌性能和抗氧化性能等研究并且应用到各个领域。     

氯酚类污染物的光催化降解活性与结构参数的关系研究

为进一步阐明光催化降解常数与氯酚类的分子结构关系,引入灰色关联分析方法,运用灰色关联理论,通过均值化处理使相关因子的实验数据无量纲化,计算出作为描述符的14种结构参数对于光催化降解常数影响程度的排序,并结合变量的物理意义作简要分析,结果表明,对光催化影响最大的参数是偶极距、(E_(lumo)-E_(homo))~2、E_(lumo)-E_(homo)、E_(homo)、E_(lumo) E_(homo)及碳原子的平均静电荷。     

几种新型双吡唑衍生物缓蚀性能的理论研究

通过量子化学计算中的密度泛函理论(DFT)/B3LYP方法在6-311+G(d,p)水平上对3种新型双毗唑衍生物5,5'-二甲基-4-乙酯基-1'氢-1,3'-二吡唑(Bipl)、1,1',5,5'一四甲基-1氢,1'氢-3,3'-二吡唑(Bip2)和3-(溴甲基)-5,5'-二甲基-1'氢-1,3'-二吡唑(Bip3)的缓释性能与结构关系进行了研究。用Fukui指数分析了分子中反应活性位点。结果表明全局活性参数最高占据轨道能量(E_(HOMO))、偶极矩(μ)、电负性(X)及电子转移数(△N)与缓释性能有良好的关系。缓蚀性能的理论评价结论与实验结果相吻合。     

方酸菁染料结构与电子性质的分子轨道法研究

采用改进的半经验分子轨道法(PPP—SCF—MO)计算了8种吲哚方酸菁染料分子的电子结构和电子光谱,计算得到的最大吸收峰波长与实验值较好的一致,计算得到的荧光跃迁能ΔE_(fl)与荧光峰波数υ_(fl)存在如下关系:υ_(fl)=10.664ΔE_(fl)-3.1299(k·cm~(-1)),r=0.9721。计算得到的前线轨道能量E_(HOMO)和电子跃迁能E_(abs)与氧化电位E_(1/2,OX)存在如下关系:E_(1/2,OX)=0.520(-E_(HOMO))+4.291E_(abs)-11.100,r=0.909。并讨论了电子结构与光谱性能的关系。     

取代酚类化合物LC_(50)的QSAR模型建立与分析

基于定量结构.活性(QSAR)研究取代酚类化合物的急毒性具有重要意义。采用DFT-B3LYP方法,在较高基组6-311G~(**)水平下,全优化计算21种取代酚。从中获得分子最高占用和最低空轨道能(E_(HOMO)和E_(LUMO))、分子次最高占用和次最低空轨道能(E_(NHOMO)和E_(NLUMO))、分子总能量(E_T)、氢原子所带的最高正电荷(q_H~+)、最负非氢原子的静电荷(q~-)、分子偶极矩(μ)和分子体积(V)等描述符。结合文献中标题化合物对梨形四膜虫的毒性值(-lg LC_(50))和疏水性系数(10g Kow),由多元线性回归方法建成QSAR模型,采用内外双重验证的办法,深入分析和检验模型的稳健性。最佳模型的复相关系数(R~2),去一法(LOO)交替检验复相关系数(R_(cv)~2),外部预测样本复相关系数(R_(ext)~2)分别为0.924,0.922和0.830,故所建QSAR模型的稳定性和预测能力良好。由此推断,标题物对梨形四膜虫的毒性作用分为两步,首先穿过细胞壁在细胞内富集,以log Kow描述;其次与亲核试剂发生亲电反应,以点E_(NLUMO)表示。     

分子动力学模拟聚赖氨酸在晶格界面上的吸附

分子模拟为从微观角度理解生物大分子提供了有利的工具。本文采用分子动力学方法研究在Pt(100)、Pt(110)及Pt (111)三种晶格界面上聚十赖氨酸分子的吸附,以从分子水平上研究蛋白质吸附的动态过程和机理。界面的作用使部分聚十赖氨酸分子出现了较明显的二面角变化,说明吸附过程中界面的特性对聚赖氨酸的分子结构有影响;在Pt(100)与Pt(111)界面上,聚十赖氨酸分子构象变化较大,Pt(110)变化较小。聚十赖氨酸分子在吸附中,能量变化与分子构象变化的结果一致,构象变化较大的Pt(100)和Pt(111)界面上聚十赖氨酸分子能量的平均值高于Pt(110)。聚十赖氨酸分子在Pt(100)与Pt(111)界面上先远离界面运动,然后在某位置稳定波动;在Pt(110)界面上先靠近界面运动一段时间后又远离界面。     

低温流动改进剂在柴油蜡晶形成阶段的晶形控制作用

采用实验和分子动力学模拟结合的方法,考察了多种乙烯-醋酸乙烯酯(EVA)和聚甲基丙烯酸参酯(PMA)类低温流动改进剂(CFI),在蜡晶形成阶段,对蜡晶晶形的影响。结果表明,在蜡晶形成阶段,CFI通过改变柴油烃分子的排列方式和相互作用能,控制蜡晶形态,避免粒径较大且容易聚集的片状蜡晶生成。CFI分子保持伸展的构象,并对烃分子有较强的吸附能力,更利于其控制晶形作用的实现。CFI分子中的极性基团和非极性短支链可起到分散烃和分子保持聚合物分子的伸展构象的作用。CFI聚合物分子中含有较多连续的亚甲基结构有利于增强其吸附烃分子的能力。     

硝酸正丙酯和硝酸异丙酯的密度泛函理论研究

用密度泛函理论(DFT)中的B3LYP、B3PW91、B3P86方法研究硝酸正丙酯(n-propyl nitrate,NPN)和硝酸异丙醣(isopro- pyl nitrate,IPN)的平衡分子构型、前线轨道能(E_(HOMO)、E_(LUMO))、能差(△E=E_(LUMO)-E_(HOMO))和O-NO_2键的裂解能(BDE)。分析了两种硝酸酯分子和对应自由基的热稳定性。NPN和IPN中的O-NO_2键的裂解能用B3P86方法计算出最接近实验值。由O- NO_2键的裂解能符合文献中对应物质的表观活化能,推知两种物质的热分解反应只是单分子O-NO_2键的均裂反应。     

基于PCA与支持向量回归的储层渗透率预测

在测井技术与储层基本特征研究的基础上,对与渗透率相关的测井参数和岩心参数进行了分析,根据传统的储层渗透率预测方法,提出了一种基于主成分分析与支持向量回归的储层渗透率预测方法。应用主成分分析对测井参数和岩心参数进行数据降维,优选出与渗透率最相关的参数,将优选出的测井参数和岩心参数作为支持向量回归模型的输入参数进行渗透率预测。实验结果表明,利用主成分分析算法提取的特征参数与渗透率有较好的相关性,且支持向量回归具有较高的预测精度,显示出主成分分析和支持向量回归在储层渗透率预测中的优势与实际应用价值。     

蚁群算法中求解参数最优选择分析*

通过理论分析和一系列的对比模拟实验研究,来探讨蚁群算法中参数的最佳设定原则,以利于蚁群算法在实际中的应用和推广.     

Biotechnical measurement and software system controlled features for determining the level of psycho-emotional tension on man-machine systems by fuzzy measures

A new software technique for determining emotional tension on humans is developed by means of psychological tests connected with the psycho-emotional sphere and on indicators characterizing the state of a subject’s visual attention. Each of these two areas determines several factors for psycho-emotional tension. The level of tension is determined as an aggregate of these two components with the rules of fuzzy logic. The membership functions and solving rules for the psychological tests, and for the state of visual attention, are constructed using fuzzy logic theory. It is shown that the resulting method can be used as an informative feature for prediction of many properties, such as the situational awareness (training and experience) of an operator and the operator’s individual capacity to function (mental-physiological limits). The second group of indicators characterize properties such as switchable attention (the ability to switch attention) (SWA), concentration (ability to concentrate) (CNA), stability of visual attention (STA) and parameters determining the state of memory. One of the most important issues for man-machine systems is to evaluate the performance of operators under abnormal conditions such as stress or tension.     

一个MPEG—4兼容的人脸动画系统

MPEG－4是一个基于对象的多媒体压缩标准,允许将中的间频视频对象（自然的或合成的）独立编码,它能够净人脸动画和多媒体通信集成在一起并且可以在低带宽的网络上控制虚拟人脸,首先介绍MPEG－4中关于人脸动画的基本概念,然后提出一个MPEG－4兼容的有脸动画系统。     

Notes on the implementation of the IREQ model for the assessment of extreme cold environments

This paper has been devoted to the difficulties that practitioners, skilled ergonomists or occupational health experts could find in the assessment of cold environments by means of (insulation required) IREQ model at the base of the (International Standardization Organization) ISO 11079 Standard. The in-depth analysis discussed here has underlined several difficulties about: (a) the graphical calculation of the predicted limit exposures; (b) some differences in both IREQ and (duration limit exposure) DLE values reported in ISO 11079; and (c) some errors and incongruities in the program available online for the assessment of DLEs. These occurrences lead to the systematic overestimation of the DLE that exceed up to 4 h, those obtained by means of the figures reported in the Standard with the consequent unreliable assessment. Such matters justify the need to promote, in the whole scientific community involved in the ergonomics of the thermal environment, an in-depth discussion on the best practice to be followed for the assessment of extreme cold environments by means of IREQ model.

Practitioner summary: Incongruities in IREQ model and errors in the code suggested by ISO 11079 Standard prevent a reliable assessment of cold environments with DLE systematically overestimated. Therefore IREQ model has been theoretically investigated trying to help both neophytes and skilled ergonomists on the best practice to be followed.     

A study of exposure to cold in cold stores

Effects of exposure to cold on skin-temperature and thermal sensations of eight experienced men wearing protective clothing, who were working normally in a cold store at sub-zero temperatures of about -27 degrees C, were studied to assess the feasibility of deriving work recovery routines from experiments conducted in the actual working environment. Although the variations in the responses to cold were such that insistence on a rigid pattern of working and recovery times would be unwise, results indicated that exposures of about 40% of the total time available would not make the risk of discomfort unacceptable, under the usual working conditions provided clothing rated at 5 to 6 togs was worn. Whilst individual reactions are important and there was, for example, an inverse relation between the age of the operative and the time spent in the cold, the results showed that the reactions of the working group are equally important. It was evident that the operatives worked together as a group which appeared to arrange the work loads to suit individual members of the group. The dry-bulb temperature of the air was an adequate index of the thermal environment, which was relatively constant so that the stress upon the operatives was assessed by time spent in the cold. Considerable individual variations in response to cold were evident; the hands and feet were found to be particularly vulnerable areas, and in general a significant fall in skin-temperature occurred whilst the operatives worked inside the store. At some time during the study, all operatives experienced discomfort from cold and there appeared to be a definite association between percentage incidence of discomfort and the time spent in the store. The current practice for the setting of work/recovery routines was questioned and suggestions were made following the results of the investigation.     

一种网格资源调度中QoS的最大化匹配算法

针对网格资源选择中复杂的QoS参数处理和精确匹配导致的资源调度率低下问题,将QoS参数按性质分类,定义了QoS参数距离,实现QoS参数相似性判断,由此提出了一种软化的参数处理模型,给出了一种最大化匹配调度算法。实验表明,该算法提高了系统吞吐量、任务满足率、资源调度率和整个系统资源利用率。     

Internet实时业务性能的测量与评估

提出了影响服务质量的几种关键网络性能参数的测量与计算方法，建立了MOS值与网络传输时延以及等效报文丢失率的函数关系，并利用该函数关系计算出满足一定服务质量时网络性能参数可能存在的边界值，为评估网络支持实时业务能力提供了参考。     

USTCFACE:一个基于Mpeg-4标准的语音动画系统

USTCFACE是一个与Mpeg-4标准兼容的人脸语音动画系统。本文介绍了构建这个系统的基本原理和关键技术。这个系统能够在低带宽的网络上完成高品质的人脸动画传输任务，可以用于改善人机界面或构造虚拟社区。     

Evaluation of methods for estimating aquifer hydraulic parameters

An accurate estimation of aquifer hydraulic parameters is required for groundwater modeling and proper management of vital groundwater resources. In situ measurements of aquifer hydraulic parameters are expensive and difficult. Traditionally, these parameters have been estimated by graphical methods that are approximate and time-consuming. As a result, nonlinear programming (NLP) techniques have been used extensively to estimate them. Despite the outperformance of NLP approaches over graphical methods, they tend to converge to local minima and typically suffer from a convergence problem. In this study, Genetic Algorithm (GA) and Ant Colony Optimization (ACO) methods are used to identify hydraulic parameters (i.e., storage coefficient, hydraulic conductivity, transmissivity, specific yield, and leakage factor) of three types of aquifers namely, confined, unconfined, and leaky from real time–drawdown pumping test data. The performance of GA and ACO is also compared with that of graphical and NLP techniques. The results show that both GA and ACO are efficient, robust, and reliable for estimating various aquifer hydraulic parameters from the time–drawdown data and perform better than the graphical and NLP techniques. The outcomes also indicate that the accuracy of GA and ACO is comparable. Comparing the running time of various utilized methods illustrates that ACO converges to the optimal solution faster than other techniques, while the graphical method has the highest running time.