喷流噪声半经验预测模型程序设计

基于喷流混合噪声半经验预测方法 TA理论模型,设计了喷流混合噪声半经验预测模型程序。其中流场计算通过商用软件ANSYS,如ICEM和FLUENT实现,声场计算通过Fortran90代码编译完成,仿真计算得到的喷流噪声远场声压级与Tam等人的实验数据吻合较好。同时提出了一种简化计算方法,在保证计算结果准确性的前提下,明显提高了计算速度。     

甲叉膦酸型化合物阻垢机理的量子化学研究

运用密度泛函（DFT）理论，在B3LYP／6-31G水平下，系统研究了ATMP，EDTMP，HDTMP，GDMP，MADMP这5种甲叉膦酸类阻垢缓蚀剂分子结构与阻垢性能之间的构效关系。结果表明，5种膦酸分子中的氮原子及膦羧基团中的氧原子上负电荷密度较大，这使得氮原子及膦羧基易与垢晶体中的钙离子发生静电相互作用，如果氮原子与氧原子间距与方解石晶体生长面上的钙离子对间距匹配，将显著增强了阻垢剂分子与特定晶面的Coulomb吸附行为，诱导垢晶体发生畸变，有效地阻止其生长。本文还利用半经验（PM3）方法对分子势能面进行扫描，得出分子能量随二面角改变的变化率，初步探讨了分子柔性、刚性对其阻垢性能的影响。     

基于半经验公式的风力机尾流模型研究

以瑞典航空研究院(FFA)、东京大学及荷兰能源研究中心(ECN)的风洞实验为参照,以探究半经验公式类型的风力机尾流模型为目的,验证了Jensen模型和改进Jens-en模型。采用上述两个半经验模型,编写计算程序,然后按照上述每个风洞实验的参数,设定计算条件,计算风力机下游的无量纲风速,再分别与相应的实验值进行比较。结果表明,在各自的适用条件下,上述两个模型都能比较精确地模拟风力机尾流特性。这证明上述两模型可以用于进一步研究风力机尾流效应,以进行风电场微观选址与布局优化。     

添加纳米颗粒对溴化锂溶液表面张力的影响及其机理分析

纳米颗粒可以改变溴化锂溶液的表面张力,从而促进其传热传质效果。利用Wilhelmy平板法研究了温度、溶液浓度、分散剂和纳米颗粒添加量等因素对溴化锂溶液表面张力的影响。结果表明,溴化锂溶液表面张力随溶液浓度和纳米颗粒添加量的增加而增大,随温度和分散剂添加量的增加而减小。分散剂的添加量存在最佳值,此时溶液表面张力趋于稳定,且稳定纳米溴化锂溶液的表面张力是分散剂和纳米颗粒耦合作用的结果。并拟合出溶液温度25~60℃、溶液浓度50%~59%、分散剂质量分数0~5%、纳米颗粒质量分数0~0.2%时,稳定纳米溴化锂溶液的表面张力半经验模型。     

特快速暂态过电压和雷电冲击下SF6长间隙伏秒特性

为研究特高压气体绝缘开关设备(GIS)在特快速暂态过电压(VFTO)和雷电冲击(LI)下的SF6长间隙伏-秒(U-t)特性,设计了VFTO模拟产生装置。通过改变实验间隙距离、气压和电压种类,研究了不同气压下SF6棒-板和球-板长间隙在负极性VFTO和LI下的U-t特性。实验结果表明:球-板稍不均匀电场间隙在VFTO下的最小击穿电压高于LI下的,而VFTO下的U-t曲线较LI下的曲线平坦,导致2种电压下U-t曲线相交。对于高气压(0.5MPa)下棒-板间隙,VFTO下的U-t曲线位于LI的之下。基于对实验结果和U-t特性曲线物理意义的分析,得到了用于预测给定SF6长间隙U-t曲线的半经验公式,该公式为带有3个参数的幂指数函数,其中的待定参数可由气压、间隙距离和电场不均匀系数共同决定。校验结果表明:采用半经验公式预测的U-t曲线能准确反映SF6间隙击穿特性,从而为GIS绝缘设计提供参考。     

苏氨酸水溶液在298.15K到328.15K区间液相扩散系数的测定和关联

The diffusion coefficients of aqueous L-threonine solutions were determined from 298.15K to 328.15K by the metallic diaphragm cell method with accuracy, promptness and convenience. Meanwhile, the densities and viscosities of the solutions were also determined and correlated. Based on a seml-empirical model for correlating the diffusion coefficients of some amino acids in their aqueous solutions, a new semi-empirical model for correlating the diffusion coefficients involving temperature was provided, which is more comprehensive and less experiment dependent compared to the previous model. The fitting results are satisfactory. Compared to a former model for correlating the diffusion coefficients of solid organic salts in their aqueous solutions, this model provides significant improvement in correlation of diffusion coefficients with different temperatures avoiding arduous work.     

Application of KNN and Semi-Empirical Models for Prediction of Polycyclic Aromatic Hydrocarbons Solubility in Supercritical Carbon Dioxide

The solubility of polycyclic aromatic hydrocarbons in supercritical carbon dioxide is of great importance in a wide range of applications such as extraction from polluted soils and catalytic hydrogenation. In this study, for the first time a K-nearest neighbor (KNN) as a nonparametric and easy learning model was proposed to predict the solubility of 11 polycyclic aromatic hydrocarbons in supercritical carbon dioxide. The KNN model was constructed with optimum values of K for different compounds. To have a better understanding of the KNN model capability, predictions were compared with the outputs of several well-known semi-empirical models (Chrastil, Adachi and Lu, Li, Garlapati and Madras, Sparks and Bian). Results showed that the KNN model has an average absolute relative deviation (AARD) of about 12.47% for 11 polycyclic aromatic hydrocarbons modified density based correlations (Sparks and Bian) while the best semi-empirical equation (Sparks) result an AARD of about and 11.50%.     

Measurement and correlation of solid drugs solubility in supercritical systems

A dynamic experimental set-up was utilized to measure ibuprofen solubility in supercritical CO2 at the pressure range of 8-13 MPa and the temperatures of 308, 313 and 318 K. Mole fraction values varied from 0.015＆#215;10^-3 to 3.261＆#215;10^-3 and correlated by using seven different semi empirical equations of state （Bartle, Modi-fied Bartle, Mendez-Teja, Modified Mendez-Teja, Kumar-Johnson, Sung-shim and Gordillo） as well as seven cubic equations of state （van der Waals, Redlich-Kwong, Soave-Redlich-Kwong, Peng-Robinson, Stryjek-Vera, Patel-Teja-Valderana and Pazuki）. Single and twin-parametric van der Walls mixing rules （vdW1, vdW2） were ap-plied in order to estimate the supercritical solution properties. The physicochemical properties were also obtained using Joback, Lydersen and Ambrose methods. Absolute average relatives deviation （AARD） were calculated and compared for all the correlating systems. Results showed that among the cubic equations of state （EOSs） the Pazuki equation （AARD=19.85% using vdW1 and AARD=8.79% using vdW2） and SRK equation （AARD=19.20%using vdW1 and AARD=10.03%using vdW2） predicted the ibuprofen solubility in supercritical CO2 with the least error in comparison to the others. Among the semi-empirical EOSs the most desirable deviation （AARD〈10%） was obtained by using Modified Bartle and Modified Mendez-Teja equations in all the studied temperatures.     

Kinetics of simultaneous leaching of Ag and Pb from hydrometallurgical zinc residues by chloride

The leaching kinetics of silver and lead simultaneously from zinc residue by chloride was investigated.The effects of stirring speed,temperature,sodium chloride concentration,particle size and liquid/solid ratio on Ag and Pb dissolution in sodium chloride were studied.It was determined that the dissolution rates increased with increasing sodium chloride concentration,temperature and decreasing particle size.The dissolution kinetics followed a shrinking core model,with inter-diffusion through gangue layer as the rate determining step.This finding is in accordance with the apparent activation energy(Ea)of 26.8 kJ.mol-1(Ag)and 26.5 kJ.mo1-1(Pb),and a linear relationship between the rate constant and the reciprocal of squared particle size.The orders of reaction with respect to sodium chloride concentration,temperature and particle size were also achieved.The rate of reaction based on diffusion-controlled process can be expressed by semi-empirical equations.     

随机地震荷载下黏性土残余应变的半经验计算公式

提出一个新的简化半经验计算公式，用于随机地震荷载作用下黏性土残余应变的计算。新公式放弃了目前将不规则地震荷载转换成一定次数等幅正弦波的方式，而采用直接对不规则动应力波进行逐波累计的计算方法，这样可以得到任意随机地震荷载作用下土残余应变的实际发展过程。新公式首先略去地震波频率特性的影响，将一随机地震应力时程保留其有效幅值，筛选成一系列不同幅值的往返荷载；然后，以增量方法逐波累计计算残余应变。对每一动应力循环，以已有等幅荷载经验计算公式对循环次数的偏导构造残余应变的增量模型，并考虑了动压应力对残余应变增长的控制作用。经计算，对于等幅动荷载作用，新公式与现有公式之间误差很小。对于地震荷载输入，采用动三轴试验与新公式进行对比。对比结果表明，提出的公式可以有效地描述不规则地震荷载下黏性土残余变形的增长过程和最终结果，可反映不同类型地震波作用下、CM和EM试验下以及不同波序下土残余变形的发展和差异。