Constrained Drying of an Aqueous Yttria-Stabilized Zirconia Slurry on a Substrate II: Binary Particle Slurry

Binary-sized particle slurries (binary slurries) prepared by mixing micro-particles and electrostatically stabilized nano-particle slurries (nano-slurries) were cast onto metal substrates to form wet coatings and the drying process was studied. The highly charged nano-particles were found to deposit on the surface of the micro-particles, resulting in a decrease in the viscosity of the binary slurry. The drying kinetics were classified as an initial constant rate period (CRP), followed by a falling rate period. In the early stage of CRP, the movement of micro-particles induced coating shrinkage and tensile stresses developed due to the constraint of the substrate. Thereafter, the nano-slurry continued to dry and shrink around the static micro-particles without further coating shrinkage, but with an increase in the stress. The addition of micro-particles reduced the level of the maximum stress and prevented crack formation during drying. The microstructure of green coatings shows the presence of nano-particles between micro-particles that cement the micro-particles together.     

基于复杂网络的股票社团化分析

为了更清楚地了解股票间价格波动的相互影响,利用改进的Newman贪婪算法将沪市A股成功分为13个社团,并根据其紧密程度,得到内部股价波动影响关系比较敏感的社团.另外,根据股票间的吸引率对社团之间的影响程度进行了量化,找到联系最紧密的两个社团.从社团结构可以读出大量的市场信息,为投资决策以及评定行业前景提供可靠的依据,同时也体现出复杂网络的应用价值.     

二甲醚发动机低压共轨燃料喷射系统的设计及试验

针对二甲醚燃料低粘性、高蒸汽压以及容易与空气形成混合气的特性,设计了一种可控预混合燃烧的二甲醚发动机低压共轨电控燃油喷射系统.在此基础上,以柴油代替二甲醚进行试验,分析了在喷射持续期,共轨压力、针阀升程和转速对燃油喷射过程的影响,得出了低压共轨燃料系统的燃料喷射特性,对二甲醚低压共轨系统的实用化起到了促进作用.     

Particle inertial focusing and its mechanism in a serpentine microchannel

Particle inertial focusing in a curved channel promises a big potential for lab-on-a-chip applications. This focusing concept is usually based on the balance of inertial lift force and the drag of secondary flow. This paper proposes a new focusing concept independent of inertial lift force, relying solely on secondary flow drag and particle centrifugal force. Firstly, a focusing mechanism in a serpentine channel is introduced, and some design considerations are described in order to make the proposed focusing concept valid. Then, numerical modelling based on the proposed focusing mechanism is conducted, and the numerical results agree well with the experimental ones, which verify the rationality of proposed mechanism. Thirdly, the effects of flow condition and particle size on the focusing performance are studied. The effect of particle centrifugal force on particle focusing in a serpentine microchannel is carefully evaluated. Finally, the speed of focussed particles at the outlet is measured by a micro-PIV, which further certifies the focusing positions of particles within the cross section. Our study provides insights into the role of centrifugal force on inertial focusing. This paper demonstrates for the first time that a single focusing streak can be achieved in a symmetric serpentine channel. The simple serpentine microchannel can easily be implemented in a single-layer microfluidic device. No sheath flow or external force field is needed allowing a simple operation in a more complex lab-on-a-chip system.     

两种基于北斗BDM100模块的家庭监护终端设计

针对家庭监护中老人实时定位问题,结合北斗全球卫星定位系统和北斗模块BDM100,分别采用3G和2G模块设计了两种解决方案。3G方案中,采用AT91SAM9260芯片作为主控芯片,自定义通信协议,并封装了若干基于Linux操作系统的通信函数,具有良好的扩展性和稳定性。2G模块则采用LPC1766芯片,设计了具有良好健壮性的软件,成本低,对于单一需求的用户具有很好的适应性。     

Mechanical properties and microstructures of machinable silicon carbide

Mechanical properties and microstructures of machinable silicon carbide, fabricated by pressureless sintering of silicon carbide fine powder with the aid of polysilastyrene, have been examined. Drastic changes in microstrucyure and in mechanical properties between specimens sintered at below 1773 K and at above 1873 K were observed. By sintering at above 1883 K the macinable silicon carbide had a good strength of more than 200 Mpa with high reliability, which was maintained beyond 1773 K. Polysilastyrene was converted in -phase silicon carbide and ribbon carbon in the pores. The (001) plane of carbon is parallel to the (111) planes of -phase silicon carbide.     

Linux系统下DB2数据库的备份与恢复实例

通过具体的数据库故障实例,介绍了Linux系统下DB2数据库的备份与恢复方法,通过直观详细的操作命令,使读者掌握DB2数据库的备份与恢复技术.     

Boost型电路双闭环功率因数校正控制策略

以Boost拓扑电路为基础,对其进行深入分析,建立理想情况下的电压平衡方程式.提出一种给定占空比的电压和电流反馈的功率因数校正控制策略,利用MATLAB/Simu-link进行仿真.仿真结果表明,与平均电流法控制策略相比,在保证输出电压稳定控制精度的情况下,改善了系统的响应速度.在STM32F103X(ARM)为主控制器的实验平台上进行实验,结果表明系统输出电压稳定,纹波电压小,输入电流波形正弦度好,功率因数接近1.表明该策略具有良好的功率因数校正控制效果.     

A method for fuzzy group decision making based on induced aggregation operators and Euclidean distance

In this paper, we present the fuzzy‐induced Euclidean ordered weighted averaging distance (FIEOWAD) operator. It is an extension of the ordered weighted averaging (OWA) operator that uses the main characteristics of the induced OWA (IOWA), the Euclidean distance and uncertain information represented by fuzzy numbers. The main advantage of this operator is that it is able to consider complex attitudinal characters of the decision maker by using order‐inducing variables in the aggregation of the Euclidean distance. Moreover, it is able to deal with uncertain environments where the information is very imprecise and can be assessed with fuzzy numbers. We study some of its main properties and particular cases such as the fuzzy maximum distance, fuzzy minimum distance, fuzzy‐normalized Euclidean distance (FNED), fuzzy‐weighted Euclidean distance (FWED), and fuzzy Euclidean ordered weighted averaging distance (FEOWAD) operator. Finally, we present an application of the operator to a group decision‐making problem concerning the selection of strategies.     

求解网格奇点的曲率传输方法

为了降低网格在参数化过程中产生的扭曲,提出一种基于曲率传输求解网格奇点个数和位置的方法.首先,通过求解Yamabe方程获得网格顶点的共形缩放因子,利用共形缩放因子的持续性确定第1部分的奇点,并计算基于该奇点集合的参数化扭曲;然后,根据参数化扭曲确定第2部分的奇点,并优化奇点的位置;最后,顶点曲率集中到奇点上计算出最优传输代价,通过不断地更新奇点位置,使上述最优传输代价达到最小,得到最终奇点分布.经过计算大量的网格,实验结果表明,与其他曲率方法以及近几年的方法相比,利用该方法确定的奇点可以有效地降低网格参数化带来的扭曲.