多孔介质孔隙模型及其应用——毛细管束模型

在多孔介质中许多物理化学行为均与其自身的孔隙结构构型密切相关,建立一种切实可行的孔隙模型将会对研究材料和化工过程多孔介质提代很大的帮助。毛细管模型是一种较为简单的实用孔隙模型,它可以通过使用毛细管压对多孔介质的浸渗和排空情况进行计算,也可用于对多孔介质中的浸渗和排空过程进行定性的解释。针对在研项目,对毛细管束模型情况做一评述。     

多孔介质孔隙结构的网络模型应用

本研究分别用毛细管束模型和网络模型对多孔介质的孔构型进行描述。为了克服毛细管束模型在反映真实结构存在的局限性 ,有必要发展更为精确的方法。在诸多的多孔介质模型中 ,网络模型经过多年的研究、发展 ,已经可以较好地实现对过程机理进行定量预测。进一步通过引入非线形分形理论 ,对复杂孔隙结构可望得到更为真实可靠的构型模型     

多孔介质孔隙结构的网络模型应用

本研究分别用毛细管束模型和网络模型对多孔介质的孔构型进行描述。为了克服毛细管束模型在反映真实结构存在的局限性,有必要发展更为精确的方法,在诸多的多孔介质模型中,网络模型经过多年的研究、发展,已经可以较好地实现对过程机理进行定量预测,进一步通过引入非线形分形理论,对复杂孔隙结构可望得到更为真实可靠的构型模型。     

基于模拟退火算法的多孔介质三维重建

为了研究固相转换器内部流体的流动状态,将动态退火系数的模拟退火算法与基于改进的状态更新的随机重建方法相结合,提出一种对固相转换器这类多孔介质进行软件重建的三维随机重建策略.首先对显微CT采集得到的多孔介质图像进行处理,得到基于孔隙相与固体相的二值化图像,并将其作为参考模型;然后在保持多孔介质孔隙率不变的前提下对多孔介质进行重建,实现了对其采样、图像处理与重建的过程.实验结果表明,该策略可以提升重建速度与渗透率的精度,重建模型与参考模型的两点相关函数与孔隙分形维数有很好的一致性.     

多孔介质3维孔隙空间的隐式曲面造型方法

多孔介质中孔隙空间的结构描述和问题求解是许多复杂形态实体微观分析和科学计算的基础,而实际的多孔介质孔隙空间结构由于异常复杂,采用简单的造型方法往往不能满足绘制和进一步计算的要求。为此,针对自然岩石核磁共振的3维体数据,提出了一种适用于多孔介质孔隙空间的造型方法。该方法首先通过最大球方法识别体数据中的孔隙空间,然后根据孔隙的层次关系和连通关系,通过建立孔隙空间的孔洞-网络模型来描述孔隙空间的拓扑结构,并结合隐式曲面造型方法来构造多孔介质孔隙空间的模型。将该方法运用到自然岩石的3维图像分析中的实验结果表明,该方法不仅使得多孔介质孔隙空间的复杂拓扑结构得以保留,而且保证了重建曲面的光滑性。     

多点地质统计学在数字岩心重构中的算法研究

在一个多孔介质中流体物质的渗流依赖孔隙空间几何结构和拓扑结构特性。因此,描述介质特征及预测其流动特性最重要的第一步是对一个多孔介质的三维孔隙空间进行重构。有介于此,一种随机模拟技术被提了出来,应用二维切片训练图像重构一个三维的孔隙图像。这项技术基于从连续的二维多点统计模拟拟合多尺度二维调节数据提取的过程。单一标准方程模拟算法(SNESIM),最初作为一种模拟引擎,起到了对地质构造的曲线特征进行复制的作用。     

基于同态球的多孔材料三维模型快速重构方法

研究多孔材料的三维模型重构问题,提高重构效率。多孔材料真实孔隙空间的结构异常复杂,孔隙空间的构成面较大,需要计算的孔隙像素量繁多,传统的基于二元表示法的重构方法,将孔隙空间逐一映射成像素点实现几何形态描述无法有效处理大量的孔隙像素量,巨大的计算量造成重构效率不高的问题。为此,提出了一种基于同态球的多孔材料三维模型重构方法。通过确定孔隙空间的"同态球"并据此定义孔隙体,将多孔材料的孔隙空间几何形态用孔隙体和吼道来表示,利用孔隙体和吼道之间的联系重构三维模型,避免了对孔隙空间逐一分析而造成的重构效率不高的问题。仿真实验表明,这种方法形象描述几何形态,有效减少了重构计算量,能够快速完成多孔材料三维模型的重构。     

基于MPS和多重模板的多孔介质重构方法

在油汽探测的研究中,提高探测的准确性,结多孔介质三维重构在油气探测有着重要意义,用规方法对多孔介质中长的孔隙通道和复杂的孔隙空间形状重构效果较差.为了提高探测精度,提出一种基于多点地质统计(MPS)和多重模板的多孔介质三维重构方法.将微米精度的多孔介质体数据作为训练图像,把逐渐密集化的网格作为多重数据模板提取其空间结构...     

一种基于物理模型的布料湿润效果真实感模拟方法

通过分析布料和流体之间的相互作用与关系,本文提出了一种新的基于多孔粒子模型的布料湿润效果真实感模拟方法。该模型可以看作是一种改进的弹簧质点模型,借鉴粒子模型的一些基本概念,模型中采用了多孔粒子这一结构。该结构中的孔隙可以作为流体在布料中的存储空间,由于相邻多孔粒子中流体存储量不同,形成的毛细压强差推动流体在所有粒子中流动。同时,该模型按照达西渗流原理控制整个流体湿润布料的过程,并且根据相关粒子饱和度的不同选择不同的纹理,用映射不同纹理的方式表现湿润过程中布料材质的改变。该模型计算效率高,且具有很强的可扩展性。     

基于TDMA算法的污染扩散方程无量纲化方法研究

为了实现对污染扩散的量化分析和评估,提出一种基于TDMA算法的污染扩散方程无量纲化分析方法。采用双曲函数建立污染扩散方程,构建污染扩散的动力学模型,采用湍流度的动力学修正方法进行污染扩散的流场分析,构建污染扩散的多相非饱和多重孔隙分布模型,结合TDMA算法进行污染扩散的多孔介质中两相界面湍流场分析,分析污染源的基质孔隙和裂隙的流体压力,结合孔隙介质的弹性柔度张量评估方法,实现污染扩散方程无量纲化分析和定量评估。仿真结果表明,采用该方法进行污染扩散的量化评估的准确性较高,对污染扩散的动态拟合性能较强,提高了污染扩散的准确分析和预测能力。     

High-aspect-ratio microstructure filling by centrifugal force field modeling

This paper addresses the influence of centrifugal force and surface tension on the fluid filling processes in high-aspect-ratio microstructures. The microstructure was treated as a porous media. Numerical solutions are obtained for different parameters that governing the fluid filling flow phenomena. It was found that at certain high rotation speed of the filling system, efficient filling can be attained regardless surface is hydrophobic or hydrophilic. The pressure distribution during the filling process is also addressed. It is found that pressure variations along the filling length were almost in linear fashion from inlet pressure to the capillary pressure for both complete and incomplete filling.This work was supported by the National Science Council (series no. NSC91-2218-E-005-001) of Taiwan. The National Synchrotron Radiation Research Center (NSRRC) provided synchrotron radiation for fabricating high-aspect-ratio PMMA molds is acknowledged.     

Combining molecular dynamics and lattice Boltzmann simulations: a hierarchical computational protocol for microfluidics

A hierarchical computational protocol is introduced to investigate the role of interfacial and wetting properties to the fluid displacement in hydrophilic pore network models (PNMs). Based on the combination of molecular dynamics (MD) and lattice Boltzmann method (LBM) simulations at both nano- and microscales, we study the role of dispersed functionalized \(\hbox {SiO}_{2}\) nanoparticles (NP) in brine to the oil displacement process in a clay (montmorillonite—MMT) pore structure. Our MD calculations indicate that dispersion of NP, with different hydrophilic properties, in brine solution reduces the interfacial tension between oil and brine, followed by an increase in the contact angle. The lowest interfacial tension and highest contact angle are for the hydrophilic NP functionalized with polyethylene glycol groups. By mapping the properties obtained from MD into LBM simulation parameters, we explore the oil displacement process in hydrophilic PNMs at the microscale. For all systems, the Young–Laplace filling rules are obeyed and, due to the finger formation, the displacement efficiency decreases as the capillary number increases. It was observed that, with the inclusion of NP, a reduction in interfacial tension associated with an increase in the contact angle may enhance the oil displacement process in hydrophilic pore systems at the microscale. The proposed computational protocol can be a versatile tool to explore the potentialities of chemical additives, such as NP, for the oil recovery process and investigate the effects of interfacial tension and wetting properties on the fluid behavior at both nano- and microscales.     

结合ISO 9000品质管理系统与PZB缺口模式以达成顾客满意目标之整合方法

The aim of this study is to combine the designed structure of ISO 9001:2000 QMS and the analysis flow of PZB Gap Model. Related requirements of ISO 9001:2000 QMS were "build-in" into the five gaps of the PZB Gap Model, during 3 phases, for the achievement of service quality. In phase 1, to identify Gaps by using PZB Gap Model as an analysis tool; In phase 2, we fill Gaps by applying ISO 9001:2000 clauses requirements; In phase 3, action are taken to close or narrow Gaps by developing SOP which can be followed by employees in accordance with ISO requirements suggested in phase 2. The integrated model and 3-phase transformation could be utilized as an effective and efficient tool to achieve customer satisfaction objective. It can not only to help both the manufacturing and service industries to satisfy or exceed the ultimate customer needs, but also to improve the processes among enterprises' whole quality management system. To verify our suggested model, we helped a university's Extension Education Training Center in Taiwan to establish its ISO quality management system. A Quality Manual and some ISO procedures were assigned to improve related "Gap" which designed in accordance with our integrated model. From the help of such an ISO and PZB combined philosophy, not only its efficiency improved, the higher trainee satisfaction was also reached.     

Settle3D—A numerical generator for artificial porous media

Reservoir rocks, regardless of what kind (oil-, gas- or water-bearing), are classified by their specific properties. Most rock properties, such as storage, permeability, electric conductivity, heat capacity and so on are determined by laboratory experiments and field tests under different external conditions. Besides temperature, pressure and chemical reactions, also the geometry of the pore space as well as porosity control the specific behaviour of a rock. In most experiments, heterogeneous deformation of the pore space, changes in porosity and inner surface or closing of micro-cracks or pore-throats, cannot be observed directly. To study the dynamic processes behind these changes, we developed the sedimentary tool “Settle3D”. With this software it is possible to generate different clastic rocks in a discrete way, which means that each grain inside this rock can be handled separately. The resulting porous medium can be directly used as import structure for different mechanical, hydraulic and thermal simulations. So the structural information of rocks can be linked to the petrophysical behaviour of porous media. To address these questions, we will present the development as well as the possibilities of “Settle3D”. These include the generation of various 3D grainpacks, handling of input parameters (such as grain size distribution of different materials), sedimentary processes via direct collision procedures and an analysis of the final pore space geometry.     

An application of the Delta Model and BPR in transforming electronic business – the case of a food ingredients company in UK

Abstract. Companies are leveraging existing resources and the internet to come up with new or modified business models to respond to the demands of e‐business. Companies in the food processing industry are also waking to the reality that e‐business technology can make a big difference to the bottom line. This paper presents the result of an action research project which applied a new approach labelled as the Delta Model developed by Hax and Wilde (2001) of Sloan School of Management to strategy development for brick‐n‐mortar companies launching e‐business initiatives. The case company is called Whetstone Food Ingredients (WFI), located in UK. The company is firmly embedded in the agri‐product industry and operates in the ‘egg by‐product’ subsector. This paper is based upon action research supplemented by a programme of in‐depth interviews with managers at WFI for various aspects of their supply chain and e‐business initiatives. On the basis of these interviews and the companies also made a range of documents available throughout. These included internal memos, strategy plans, operational control documents and minutes of meetings. The Delta Model and Davenport's methodology of business process reengineering were adopted to structure this analysis. Used in conjunction, they helped to develop a vision, analyse the business processes, identify critical business processes, benchmark the critical processes, and then develop the information technology infrastructure. The infrastructure thus supported the critical business processes and leveraged the e‐business supply chain to enable the company to gain competitive edge.     

纳米催化以及反应蒙特卡罗分子模拟研究进展

应用蒙特卡罗分子模拟方法来模拟化学反应(尤其是孔内的化学反应)是分子模拟领域里一个比较前沿、新兴的研究方向。该方法能够从分子的微观层次上来观察催化材料的：孔径大小、形状、表面非均匀性等性质以及温度、压力等变量对化学反应平衡和反应动力学的影响，从而能更好地把握化学反应的本质特征。本文首先介绍了研究和应用领域里所被关注的催化介孔材料以及表征这些材料的物理模型；随后，综述了采用蒙特卡罗分子模拟方法来模拟化学反应的一些算法和应用；最后，指出了反应分子模拟领域所面临的难点以及挑战。     

Experimental and numerical investigation of capillary flow in SU8 and PDMS microchannels with integrated pillars

Microfluidic channels with integrated pillars are fabricated on SU8 and PDMS substrates to understand the capillary flow. Microscope in conjunction with high-speed camera is used to capture the meniscus front movement through these channels for ethanol and isopropyl alcohol, respectively. In parallel, numerical simulations are conducted, using volume of fluid method, to predict the capillary flow through the microchannels with different pillar diameter to height ratio, ranging from 2.19 to 8.75 and pillar diameter to pitch ratio, ranging from 1.44 to 2.6. The pillar size (diameter, pitch and height) and the physical properties of the fluid (surface tension and viscosity) are found to have significant influence on the capillary phenomena in the microchannel. The meniscus displacement is non-uniform due to the presence of pillars and the non-uniformity in meniscus displacement is observed to increase with decrease in pitch to diameter ratio. The surface area to volume ratio is observed to play major roles in the velocity of the capillary meniscus of the devices. The filling speed is observed to change more dramatically under different pillar heights upto 120 μm and the change is slow with further increase in the pillar height. The details pertaining to the fluid distribution (meniscus front shapes) are obtained from the numerical results as well as from experiments. Numerical predictions for meniscus front shapes agree well with the experimental observations for both SU8 and PDMS microchannels. It is observed that the filling time obtained experimentally matches very well with the simulated filling time. The presence of pillars creates uniform meniscus front in the microchannel for both ethanol and isopropyl alcohol. Generalized plots in terms of dimensionless variables are also presented to predict the performance parameters for the design of these microfluidic devices. The flow is observed to have a very low Capillary number, which signifies the relative importance of surface tension to viscous effects in the present study.     

TCP视频传输质量监控模型的研究

目前的网络视频传输质量监控模型大多是针对UDP的,而TCP视频传输质量监控模型的建立仍是一个待解决的问题。在基于MDI算法的UDP视频传输质量监控模型基础上,提出了能有效实时反应TCP视频传输质量的八个评估指标,并创建对应的监控模型进行文时指标计算。实验结果证明了该模型的可靠性和实用性。