基于层流边界层理论的单组分液体蒸发速率的预测

对单组分液体蒸发模型的研究进展进行了总结。根据层流边界层理论和分子扩散理论,建立了层流环境下单组分液体蒸发的数学模型,并进行了风洞蒸发实验。将实验结果同新建模型的预测结果以及常用蒸发模型的预测结果进行了对比分析。结果表明,新建模型的预测结果与实验结果的偏差为33.5%,预测精度仅次于M ackay&M atsugu模型、NIOH-1模型和SUBTEC模型。在较低风速内,随着风速的增加,新建模型的预测精度逐渐增加;随着蒸发液体挥发性能的减弱,新建模型的预测精度增加。     

基于智能拟合法的气液相平衡预测

利用自行开发的智能拟合法对甲醇—水溶液气液相平衡数据进行拟合,得到该溶液气液相平衡的最佳预测式及其预测结果,并将预测结果与传统预测式的预测结果进行了对比。结果表明,智能拟合法可以自动搜索得到最佳拟合式,具有形式简单、预测精度高的优点。该方法不仅对甲醇—水溶液适用,而且对其它平衡曲线无下凹的中等非理想溶液的气液相平衡预测均适用,具有广阔的应用前景。     

基于LM算法的棒束通道内空泡份额预测模型研究

应用Anklam T M和Byong-Jo Y的实验数据成功构建了基于LM算法优化的人工神经网络(ANN),用训练成功的ANN对棒束通道内的空泡份额进行预测,并得出了新的空泡份额预测关系式,其预测的均方根误差为7.80%。将ANN的预测结果与Cunningham J P and Yeh H C模型、Kamei A模型、Paranjape S模型的预测结果进行对比,结果表明:ANN的预测结果优于Cunningham J P and Yeh H C模型、Paranjape S模型的预测结果,与Kamei A模型的预测结果相近。通过输入变量对输出变量影响的敏感性分析,发现测点轴向距离与当量直径之比Z/DH、质量流密度G、加热棒束的热流密度q对棒束内空泡份额有很大的影响。     

神经网络方法在储层孔隙度预测中的应用

储层参数预测对油田勘探具有重要意义。文章采用主成分变换优化法对海拉尔盆地某油田的11种地震属性进行标准化、主成分变换,计算结果说明,只需其中4种主成分用于储层预测。利用神经网络方法对储层孔隙度进行预测,预测结果与测井资料十分吻合,取得了较好的预测效果。     

粗糙集理论在薄膜蒸发器产量预测中的应用

应用粗糙集理论研究了薄膜蒸发器历史数据不确定影响下的产量预测问题。结合0.4 m2薄膜蒸发器试验数据,应用粗糙集理论,给出了从数据准备、数据挖掘、挖掘结果的解释与评估到最终产量预测结果的完整预测过程。结果表明:应用粗糙集理论得到的薄膜蒸发器产量预测结果与工程实践吻合较好。     

基于有限元法的压力容器爆破压力预测

针对带接管的圆柱形壳体这一压力容器的典型结构,采用有限元法对其进行爆破失效分析,预测爆破压力。将有限元法的计算结果与经验公式的计算结果进行了对比,结果显示有限元分析结果较经验公式的计算结果偏安全,是一种有效的压力容器爆破压力预测方法。采用的预测方法可为压力容器按照爆破失效准则进行设计和预测爆破压力提供参考。     

支持向量机在型坯挤出壁厚预测中的应用

将支持向量机应用于挤出吹塑过程的一段型坯壁厚分布的预测,并将预测结果与人工神经网络预测的结果进行比较,验证了支持向量机具有更强的泛化能力。     

油气田开发动态规律的分析方法研究与应用

基于油气田开发动态分析研究的调研,以梁家楼油田纯56断块为实例,通过编制的计算机软件进行了动态分析及开发效果的评价。结果表明：水驱曲线的预测结果误差较小,但不同的水驱曲线结果仍存在一定的误差,实例中丙型水驱曲线法预测误差最小;预测模型法预测结果误差较大,仅Logistic模型预测结果具有参考价值;经验公式法中陈元千公式法、美国GG经验公式和美国API公式预测结果误差较小。本文的研究思路和分析结果对油田高效开发与开采具有较重要的指导作用。     

煤种成浆性的人工神经网络预测模型研究

为更好地预测煤的成浆性,以大量煤种成浆浓度试验数据为基础,建立了3个输出因子的神经网络成浆浓度预测模型,模型采用L-M算法,对输入数据进行数据预处理,最后对比分析了神经网络预测模型与回归分析模型的预测结果。结果表明,以A_d、哈氏可磨性指数HGI和氧含量O为输入因子的模型预测结果平均绝对误差为0.63%,以M_(ad)、HGI和O为输入因子的模型预测结果平均绝对误差为0.60%,以M_(ad)、HGI和氧碳比O/C为输入因子的模型预测结果平均绝对误差为0.40%,3种组合的模型结果均小于回归分析模型的平均绝对误差1.15%。因此神经网络模型比回归分析模型有更好的预测能力,其中以M_(ad)、HGI和O/C为输入因子的神经网络模型预测结果最好。     

基于多元时序分析的水华预测及因素分析方法

在水华防治工作中,水华预测一直都是一个难点,为了解决由于水华生成过程中多种特征因素间的交互影响建模困难,现有的水华预测方法预测结果还不够准确,以及不同影响因素与水华发生的相关性程度的判定等问题,采用多元时间序列分析技术,研究多特征因素的水华预测及因素分析方法,通过对水华生成过程中的特征因素时序建模分析,提出多重潜周期多元自回归模型,给出了基于多元周期平稳时序分析的水华预测以及因素分析结果。采用本文方法及传统方法分别对江苏太湖水华特征因素监测数据进行建模预测,结果表明,基于本文方法的水华特征因素预测结果与实测结果更相符、预测平均误差绝对值更小。     

碳多孔体中碳化硅晶须原位生长条件的实验与模型研究

根据碳化硅晶须生长的特定驱动力要求，通过实验和建立气相传输模型研究了碳多孔体中碳化硅晶须原位生长的条件。模型和实验研究均表明：温度和多孔体表面气相组成对多孔体内的晶须原位生长起决定作用；体内附加反应可以改变晶须生长所要求的温度和表面气相条件。     

A diffusivity model for gas diffusion through fractal porous media

A fractal model for gas diffusivity in porous media is derived by using fractal theory and by considering rarefied gas effect in micro-/nano-channels/capillaries. The proposed gas diffusivity model is expressed as a function of micro-structural parameters (the fractal dimensions for pore area and for tortuosity of tortuous capillaries, porosity and pore sizes) of porous media. The effects of parameters such as porosity, microstructures of porous media and fractal dimensions on gas diffusivity are analyzed. The effective diffusivities predicted by the present fractal model are compared with the available experimental data, and a fair agreement between them is found when porosity is less than about 0.70.     

多孔介质内流体流动的格子Boltzmann模拟

采用格子Boltzmann方法模拟多孔介质内的流动过程,通过预测渗透率,比较了单松弛模型、多松弛模型和熵格子模型在多孔介质计算中的优劣,为研究多松弛模型中各自由参数的影响,选择了12种组合进行模拟,此外,还将大涡模拟与格子Boltzmann方法相结合模拟了多孔介质内高Reynolds数下的流动及流型的转变。结果表明：单松弛模型和熵格子模型预测的渗透率随黏度逐渐增大,而多松弛模型得到的结果随黏度变化很小,另外,多松弛模型中不同松弛参数的组合对结果有较大的影响,通过比较推荐了模拟多孔介质时的最佳组合,计算结果与经验公式吻合较好。大涡模拟与多松弛模型结合较好地预测了多孔介质内流型的转变,Reynolds数越大,多孔介质内的涡越多,并且变大。     

冷冻干燥法制备层状多孔羟基磷灰石支架过程中的溶剂升华行为

采用水基羟基磷灰石(hydroxyapatite,HA)浆料,经冷冻干燥和烧结工艺(1 250℃烧结3 h)制备了层状多孔HA支架.研究了冷冻温度、干燥压力和干燥温度对水基HA浆料中溶剂升华行为的影响.结果表明:随着冷冻温度的降低,多孔HA支架的层间距逐渐减小,支架的升华时间增加;由于样品的干燥过程同时受到传热和传质的...     

Inkjet printing and nanoindentation of porous alumina multilayers

The objectives of this study were to analyse the effect of inkjet 3-D printing parameters, particularly the splat overlap distance, for the fabrication of defect-free porous Al₂O₃ ceramic multilayers, and to correlate the resulting porosities with the mechanical properties measured using nanoindentation. An aqua-based alumina ink was used in this study to fabricate the multilayers on dense alumina substrates by inkjet printing. The as-printed specimens were dried and sintered at 1200–1500 °C. The resulting microstructural features of each specimen and their corresponding porosities were studied using FIB-SEM. Elastic modulus and hardness were determined using the spherical nanoindentation technique. Results showed that defect-free porous alumina multilayers with excellent layer to layer and layer to substrate integrity were successfully fabricated. The porosity-dependence of the elastic modulus and hardness was shown to be consistent with values predicted using empirical expressions, despite the presence of abnormal grain growth at higher temperatures.     

Effect of Decomposition Kinetics and Failure Criteria on Binder-Removal Cycles From Three-Dimensional Porous Green Bodies

A previously developed algorithm can be used to predict the minimum time for the thermal removal of binder from porous green ceramic bodies. The algorithm combines a variational statement on internal pressure, which is generated by binder decomposition, with a transport model that treats the convective flow of binder decomposition products in a porous medium. The minimum time heating cycles depend on a number of coupled transport, kinetic, and dimensional parameters. The predicted minimum time heating cycles depend on the decomposition kinetics (activation energy, preexponential factor, and decomposition mechanism) and on the temperature and pressure at which failure occurs in the green body.     

Comparison of experimental and predicted breakthrough curves for adiabatic adsorption in fixed bed

Mass and heat transfer in adiabatic fixed bed adsorbers is described by a model which considers resistance to mass and heat transfer simultaneously within the porous adsorbent particles and in the fluid flowing past the pellets. The adsorption equlibrium is described by a temperature dependent Freundlich isotherm.The mathematical model which is given in dimensionless form is solved numerically for different values of the dimensionless parameters.An example of predicted concentration and temperature breakthrough curves for an adiabatic integral bed is given. This prediction is performed solely on the basis of data from an isothermal differential bed. The predicted breakthrough time is within 8% of the experimental value when the dimensionless parameters are assumed constant and within 2% when their concentration and temperature dependence is taken into account.     

Optimal parameters to produce high quality diamond films on 3D Porous Titanium substrates

Diamond films grown on three-dimensional (3D) porous titanium substrate were obtained by hot filament chemical vapor deposition (HFCVD) technique. The growth parameters strongly influenced the film properties during this complex film formation process. The pressure inside the reactor as well as the methane concentration showed their influence on the film morphology, quality, and growth rate. The substrates were totally covered by a diamond coating including deeper planes leading to a 3D porous diamond/Ti composite material formation. The sp²/sp³ ratio as “purity index” (PI) and the “growth tendency index” (GTI), evaluated from Raman and X-ray spectra respectively, were obtained for these composite materials as a function of their growth parameters.     

Modelling and simulation of self-ordering in anodic porous alumina

Real-time evolution of pre-textured anodic porous alumina growth during anodization is numerically simulated in two-dimensional cases based on a kinetic model involving the Laplacian electric field potential distribution and a continuity equation for current density within the oxide body. Ion current densities governed by the Cabrera–Mott equation in high electric field theory are formed by ion migration within the oxide as well as across the metal/oxide (m/o) and oxide/electrolyte (o/e) interfaces, and the movements of the m/o and o/e interfaces due to oxidation and electric field assisted oxide decomposition, respectively, are governed by Faraday's law. Typical experimental results, such as linear voltage dependence of the barrier layer thickness and pore diameter, time evolution of the current density, scalloped shape of the barrier layer, and the extreme difference in the reaction rates between pore bottoms and pore walls, are successfully predicted. Our simulations revealed the existence of a domain of model parameters within which pre-textured porous structures which do not satisfy self-ordering configurations are driven into self-ordering configurations through a self-adjustment process. Our experimental results also verify the existence of the self-adjustment process during anodization.     

扫描喷射电沉积制备多孔金属镍

采用扫描喷射电沉积制备具有一定厚度、孔隙率较高、组织较均匀的多孔金属镍;并研究了在不同扫描速率、喷嘴高度等实验条件下,多孔金属镍电沉积生长的行为特性;最后应用图形处理软件Image J对多孔金属镍的孔隙率和相对密度进行分析,得到了最佳实验参数.结果表明:采用扫描速率为4 mm/s时,孔隙结构相当完善;当喷嘴高度为6 mm时,孔隙率和相对密度比较适中.