Effect of slippage on the thermocapillary migration of a small droplet

We conduct a numerical investigation and analytical analysis of the effect of slippage on the thermocapillary migration of a small liquid droplet on a horizontal solid surface. The finite element method is employed to solve the Navier-Stokes equations coupled with the energy equation. The effect of the slip behavior on the droplet migration is determined by using the Navier slip condition at the solid-liquid boundary. The results indicate that the dynamic contact angles and the contact angle hysteresis of the droplet are strictly correlated to the slip coefficient. The enhancement of the slip length leads to an increase in the droplet migration velocity due to the enhancement of the net momentum of thermocapillary convection vortices inside the droplet. A larger contact angle leads to an increase in the migration velocity which in turn enlarges the rate of the droplet migration velocity to the slip length. There is good agreement between the analytical and the numerical results when the dynamic contact angle utilizes in the analytical approach obtained from the results of the numerical computation, and the static contact angle is smaller than 50°.     

System-level simulation of liquid filling in microfluidic chips

Liquid filling in microfluidic channels is a complex process that depends on a variety of geometric, operating, and material parameters such as microchannel geometry, flow velocity∕pressure, liquid surface tension, and contact angle of channel surface. Accurate analysis of the filling process can provide key insights into the filling time, air bubble trapping, and dead zone formation, and help evaluate trade-offs among the various design parameters and lead to optimal chip design. However, efficient modeling of liquid filling in complex microfluidic networks continues to be a significant challenge. High-fidelity computational methods, such as the volume of fluid method, are prohibitively expensive from a computational standpoint. Analytical models, on the other hand, are primarily applicable to idealized geometries and, hence, are unable to accurately capture chip level behavior of complex microfluidic systems. This paper presents a parametrized dynamic model for the system-level analysis of liquid filling in three-dimensional (3D) microfluidic networks. In our approach, a complex microfluidic network is deconstructed into a set of commonly used components, such as reservoirs, microchannels, and junctions. The components are then assembled according to their spatial layout and operating rationale to achieve a rapid system-level model. A dynamic model based on the transient momentum equation is developed to track the liquid front in the microchannels. The principle of mass conservation at the junction is used to link the fluidic parameters in the microchannels emanating from the junction. Assembly of these component models yields a set of differential and algebraic equations, which upon integration provides temporal information of the liquid filling process, particularly liquid front propagation (i.e., the arrival time). The models are used to simulate the transient liquid filling process in a variety of microfluidic constructs and in a multiplexer, representing a complex microfluidic network. The accuracy (relative error less than 7%) and orders-of-magnitude speedup (30 000X–4 000 000X) of our system-level models are verified by comparison against 3D high-fidelity numerical studies. Our findings clearly establish the utility of our models and simulation methodology for fast, reliable analysis of liquid filling to guide the design optimization of complex microfluidic networks.     

一种发动机液力悬置动特性研究

基于流体力学理论,研究发动机液力悬置惯性通道内阻尼力,建立一种液力悬置力学模型和数学模型,进行动特性仿真,从流体力学的角度分析了液力悬置的结构参数对其动态特性的影响。     

Electroosmotic flow in vapor deposited silicon dioxide and nitride microchannels

Electroosmotic flow was studied in thin film microchannels with silicon dioxide and silicon nitride sidewalls formed using plasma-enhanced chemical vapor deposition (PECVD). A sacrificial etching process was employed for channel fabrication allowing for cross-sections with heights of 3 μm, ranging from 2 μm to 50 μm in width. Flow rates were measured for single channels and multichannel electroosmotic pump structures for pH levels ranging from 2.6 to 8.3, and zeta potentials were calculated for both silicon dioxide and silicon nitride surfaces. Flow rates as high as 0.086 μL∕min were measured for nitride multichannel pumps at applied electric fields of 300 V∕mm. The surface characteristics of PECVD nitride were analyzed and compared to more well-known oxide surfaces to determine the density of amine sites compared to silanol sites.     

现代企业战略网络关系管理过程研究

组织间关系作为企业的关键资源,使得关系管理成为战略网络的主要管理模式.论述了关系管理在战略网络管理作用的基础上,结合组织冲突理论和联盟网络理论等,从过程论和组织间关系理论的视角,提出现代企业战略网络关系管理过程的动态模型,并对模型作进一步分析,为企业有效地实施战略网络关系管理提供理论指导.     

图书馆个性化服务绩效评价初探

本文将动态模糊的理念融入到图书馆个性化服务评价中,论证了动态模糊理论引入的必要性及可行性,并从动态模糊理论的视角出发建立了个性化服务评价标准,确定了权重系数论域及评语等级论域,以期对相关领域的理论及实证研究有所贡献。     

Repulsion-based model for contact angle saturation in electrowetting

We introduce a new model for contact angle saturation phenomenon in electrowetting on dielectric systems. This new model attributes contact angle saturation to repulsion between trapped charges on the cap and base surfaces of the droplet in the vicinity of the three-phase contact line, which prevents these surfaces from converging during contact angle reduction. This repulsion-based saturation is similar to repulsion between charges accumulated on the surfaces of conducting droplets which causes the well known Coulombic fission and Taylor cone formation phenomena. In our model, both the droplet and dielectric coating were treated as lossy dielectric media (i.e., having finite electrical conductivities and permittivities) contrary to the more common assumption of a perfectly conducting droplet and perfectly insulating dielectric. We used theoretical analysis and numerical simulations to find actual charge distribution on droplet surface, calculate repulsion energy, and minimize energy of the total system as a function of droplet contact angle. Resulting saturation curves were in good agreement with previously reported experimental results. We used this proposed model to predict effect of changing liquid properties, such as electrical conductivity, and system parameters, such as thickness of the dielectric layer, on the saturation angle, which also matched experimental results.     

基于成熟度视角的工业互联网平台评价研究

建设和推广工业互联网平台是工业互联网创新发展的关键，是构筑现代工业体系，加快制造强国和网络强国建设的重要抓手，也是全球新一轮产业竞争的制高点。当前，我国工业互联网平台总体处于起步探索阶段，其建设与发展是一个动态优化、持续演进的过程，亟需建立一套评估引导体系，促进工业联网平台发展从探索走向成熟。本文借鉴能力成熟度模型理论，提出了工业互联网平台建设能力成熟度等级划分，给出平台成熟度评估的基本框架，以及评估实施的方法和流程，有助于企业及政府等主体通过评估精准定位平台建设的薄弱环节，并建立针对性的改进方案，加快平台的建设和发展。     

反Opal及二维非线性光子晶体的研究（英文）

通过向SiO2 Opal模板中填充钛酸乙酯制备TiO2光子晶体，观测到光子晶体带隙位置的移动达62 nm，并发现光子晶体的有序度随填充率的升高而下降。向聚苯乙烯Opal模板中填充钛酸乙酯，制备成当时填充率最高、带隙最短的紫外波段TiO2反Opal光子晶体 (中心波长~380 nm)，并根据测量的其透射谱估算出其填充率约为12%，即Opal模板孔隙的50%被填充。本文还对二维 PPLN光子晶体进行了研究。建立了一套高压极化装置和电压数据采集装置，通过外加电场极化法成功制备出了具有正方形和矩形两种晶格形状二维 PPLN光子晶体。利用二维PPLN的二阶准相位匹配，测量了其对1.064 mm激光的二次谐波转换效率，并研究了晶体的温度、激光的入射角度及占空比对二次谐波转换效率的影响。利用矩形晶格实现了多方向、多波长倍频高效输出。     

构建测量组织战略绩效的指标体系方法研究

摘要：组织战略管理绩效服务于组织战略目标,是对组织战略行为和结果的考察与评价。组织战略管理的绩效决定了组织的绩效。由于组织战略的长期性、动态不确定性和复杂性,组织战略管理的绩效评估愈发复杂。本文提出了以简化SSM系统分析和3E理论为基础,从组织的愿景和战略出发,在“目标-过程-结果”系统地逻辑分析和理性思考基础上,基于组织功能模块和管理流程,构建具有逻辑关联性的测量组织战略绩效的指标体系。并以高校科研评价指标体系的构建为例,将高校发展战略分解运用到科研评价和管理的整个实施过程。此方法不但可以测量组织战略管理的绩效,还可用以重新设计、调整现有组织结构进而提高组织绩效。     

AMC视角下多市场接触对企业研发强度的影响--基于全球医药行业的实证研究

以往对多市场接触的研究大多集中于考察多市场接触对下游产品市场竞争强度的影响，本文将研究的注意力转向上游要素市场。基于多市场接触理论和动态竞争的意识—动机—能力 (awareness-motivation-capability, AMC) 框架，探讨了多市场接触对企业研发强度的影响。对全球最大的38家制药企业2007—2016年期间的面板数据分析表明，把企业间竞争的范围延伸到上游研发市场时，多市场接触会表现出显著的竞争效应，即多市场接触会正向影响企业的研发强度，从而说明经典的相互克制效应并不适用于要素市场。此外，本文检验了多市场接触和研发强度关系的边界条件，焦点企业专利存量和现金持有比会削弱多市场接触和研发强度之间的正向关系，而销量下降产品比例会强化二者之间关系。     

等离子体处理对聚四氟乙烯微孔薄膜界面粘结性能的影响

以XPS、动态接触角分析仪和扫描电镜等为手段,研究了不同条件下低温等离子体对聚四氟乙烯微孔薄膜界面粘结性能的影响。结果表明：等离子体处理功率对薄膜界面粘结性能的影响．因等离子体种类的不同而有明显的差别。等离子体处理时间对薄膜界面粘结性能的影响,因等离子体种类和处理功率的不同而有一定的差别。不同的等离子体,对薄膜界面粘结性能的改善效果,因等离子体处理功率的不同而有较明显的不同。     

基于三垂面上形核的润湿角

对三垂面基体上非自发形核进行了研究. 根据非自发形核的条件,对临界形核半径和临界形核功进行了推导,得到了临界形核功与润湿角的数学表达式.结果表明,临界形核功仅与润湿角有关,说明润湿角在非自发形核中起非常重要的作用.对形核润湿角进行的讨论表明了,与自发形核相比,非自发形核具有更小的临界形核功.     

基于要素选择的高考志愿填报“四步”法

如何填报高考志愿是许多考生和家长面临的一个难题．本文根据因素理论,从影响高考志愿填报的成绩、区域、学校、专业四个重要因素着手,设计基于要素选择的高考志愿填报“四步”法,对指导考生填报高考志愿有着重要意义。     

西方智力研究的发展与整合

西方传统智力理论旨在鉴别个体的学业差异,侧重于对智力结构、成分的描述和分析。受信息加工论、认知神经科学等新科学发展的影响,现代西方智力研究领域涌现出一批新的研究视角和智力理论,主要代表有加德纳的多元智力理论、斯腾伯格的三元智力和成功智力、戴斯等人的PASS模型、塞西的生物——生态学智力模型和珀金斯的真智力理论等。在此过程中,智力研究逐渐从智力因素论转变为智力过程论,智力发展过程的动态性受到空前的重视。同时,现代智力研究越来越注重智力研究的实践性和创造性,其理论取向也逐渐回归,在未来的研究中将呈现出一种＂聚拢——发散——再聚拢＂的融合发展态势。     

企业动态能力及组织能力演化:一个理论框架

动态能力理论是20世纪90年代在资源学派的基础上衍生出来的一个新的理论流派,在战略管理中处于前沿地位。探讨动态能力概念的演化,尝试构建企业动态能力理论的分析框架,并揭示动态能力理论对战略管理理论的新发展,指出该理论的不足及未来研究的方向。     

基于开放式创新的知识产权管理理论研究

本文论述了开放式创新理论发展及其成因,从四个方面分析了在基于开放式创新模式下的知识产权管理理论问题。提出了:从基于技术创新的角度、从技术-经济-法律一体化的角度、从商业化的角度、从利益机制的角度研究基于开放式创新的知识产权管理理论问题。     

动态能力对生物质能源企业创新绩效的影响研究

基于生物质能源企业视角,将我国生物质能源产业发展阶段特点与动态能力、创新绩效理论相结合,构建包含动态能力、创新模式和创新绩效在内的研究框架。从18个地区35家企业获取一手数据,结合现有文献进行分析,构建结构方程模型,取得相关研究结论。研究表明,学习能力对两种创新模式影响显著,且对渐进式创新影响更强;整合能力对激进式创新具有显著正向影响;两种创新模式对企业创新绩效均具有显著的正向影响,且生物质能源企业采用渐进式创新模式对创新绩效的影响作用更大。最后根据研究得出结论并提出建议。     

Cyclic olefin copolymer based microfluidic devices for biochip applications: Ultraviolet surface grafting using 2-methacryloyloxyethyl phosphorylcholine

This report studies the surface modification of cyclic olefin copolymer (COC) by 2-methacryloyloxyethyl phosphorylcholine (MPC) monomer using photografting technique for the purpose of biointerface applications, which demonstrate resistance to both protein adsorption and cell adhesion in COC-based microfluidic devices. This is essential because the hydrophobic nature of COC can lead to adsorption of specific compounds from biological fluids in the microchannel, which can affect the results during fluidic analysis and cause clogging inside the microchannel. A correlation was found between the irradiation time and hydrophobicity of the modified substrate. Static water contact angle results show that the hydrophilicity property of the MPC-grafted substrate improves with increasing irradiation time. The contact angle of the modified surface decreased to 20 ± 5° from 88 ± 3° for the untreated substrate. The surface characterization of the modified surface was evaluated using x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR spectroscopy). Attenuated total reflection-FTIR and XPS results show the presence of the phosphate group (P-O) on modified COC substrates, indicating that the hydrophilic MPC monomer has successfully grafted on COC. Finally, it was demonstrated that cell adhesion and protein adsorption on the MPC modified COC specimen has reduced significantly.     

轮轨垂向接触刚度分析

目前在机车／线路耦合动力学研究中,常采用赫兹非线性理论计算轮轨接触刚度,由于赫兹理论存在局限性,本文采用有限元计算方法,建立了三维轮轨接触模型,考虑了钢轨弯曲对接触区的影响,计算出合理的轮轨接触状态,考虑枕木周期变化对轮轨接触刚度的影响,考虑了道床对轮轨接触刚度的影响,计算得到轮轨接触刚度并与基于赫兹非线性理论的轮轨接触刚度进行比较。