Dip coating with colloids and evaporation

We investigate the coating of a glass plate with silica colloids by a dip coating method in presence of evaporation. We show experimentally that the deposed quantity plotted versus plate velocity V exhibits a minimum, in agreement with a simple argument developed by us in a previous, theoretical paper. This minimum corresponds to a crossover between the well-known Landau–Levich regime observed at higher plate velocity and a less well-known regime at lower plate velocity where the deposit is formed directly at the contact line. This very general result is consistent with experiments and calculations made by other teams with different compounds or under different drying geometries. Modifying our initial argument by taking into account the particle density gradient, we show that a simple modeling of each regime in terms of scaling laws is possible, the deposed mean thickness scaling respectively as V⁻¹ and V^2/3 in the lower and higher velocity limits.     

Finite element-based multi-phase modelling of shape memory polymer stents

In the western hemisphere almost the half of all events of death are caused by cardiovascular diseases, e.g. strokes and heart attacks. The latter are consequences of arteriosclerosis leading to abnormal deposits (plaque) in blood vessels. In order to avoid the serious symptoms discussed in the above or to hold affected blood vessels open, tubular structures made of metallic or polymeric materials (stents) are implanted.In the paper we discuss the modelling of a new kind of stents, so-called shape memory polymer (SMP) stents. The first part of the paper is devoted to the thermo-mechanical modelling of these materials. Aspects as the transition from entropy to energy elasticity are included. The constitutive equations are derived in the framework of large strains. We follow both, a purely macroscopic as well as a micromechanically motivated approach. In the second part of the work representative examples based on realistic stent structures are used to validate the model.     

Young’s modulus of ceramic particle reinforced aluminium: Measurement by the Impulse Excitation Technique and confrontation with analytical models

Young’s modulus of particulate metal matrix composites with volume fractions of reinforcement ranging from 40% to 60% is measured with the Impulse Excitation Technique. Results are compared with predictions of four common micromechanical mean-field models. Good agreement is obtained with the Torquato identical hard spheres (TIHS) and the generalized self-consistent (GSC) model.     

大跨度千吨桁架液压整体提升工法

新技术大跨度钢结构地面整体组装和应用集群液压千斤顶施工具有减少高处作业量，无需大型机械设备等特点，适用于高层建筑物在任意高度上的桥式连廊钢结构的整体安装。由于大部分工作在地面上进行。施工难度降低，保证了质量，提高了效率，增加了效益。     

谈建筑施工企业投标管理

对建筑施工企业在投标工作中出现的编制投标(报价)文件时间紧迫、工作量大、竞争激烈而难以保证投标文件质量的问题进行了讨论,同时也提出了自己的一些看法和解决思路,从而使投标管理工作更加规范。     

世界各国关于往复式发动机固定电站的排放法规

针对全球应用往复发动机的固定电站的市场份额急剧增长并由此带来的排放问题,介绍了一些世界主要国家和地区对往复式发动机固定电站所制定的排放法规,因我国在该领域的相应法规还不甚完善,希望能有所借鉴。     

大型煤化工过程污染物产生与防治概述

随着大型煤化工产业的不断发展,污染问题也越来越严重,造成了严重的环境污染。介绍了大型煤化工过程主要污染物,包括废水,废气,粉尘,废渣的产生、排放特征及相关治理措施。提出了防治煤化工行业污染的几点建议,要从工艺选择,工程设计和生产运行各个环节着手控制和防治污染物。     

A mechanistic model for transverse damage initiation,evolution, and stiffness reduction in laminated composites

A constitutive model to predict stiffness reduction due to transverse matrix cracking is derived for laminae with arbitrary orientation, subject to in-plane stress, embedded in laminates with symmetric but otherwise arbitrary laminate stacking sequence. The moduli of the damaged laminate are a function of the crack densities in the damaging laminae, which are analyzed one by one. The evolution of crack density in each lamina is derived in terms of the calculated strain energy release rate and predicted as function of the applied load using a fracture mechanics approach. Unlike plasticity-inspired formulations, the proposed model does not postulate damage evolution functions and thus there is no need for additional experimental data to adjust material parameters. All that it is needed are the elastic moduli and critical energy release rates for the laminae. The reduction of lamina stiffness is an integral part of the model, allowing for stress redistribution among laminae. Comparisons with experimental data and some results from the literature are presented.     

运载火箭一级发动机自动归零技术研究

基于现役某型号运载火箭一级伺服回路的控制方案和原理,提出一种在发射场一级发动机挂齿后进行自动归零的方法.经发射场试验实际验证:一级发动机喷管在实施自动归零措施后可快速回零且不发生偏离,自动归零方案可行有效.     

关于大角度范围内四元数与欧拉角转换的思考

在存在大角度姿态机动的场景中,航天飞行器通常采用基于姿态四元数的姿态运动模型,同时又多以欧拉角形式给定其期望姿态,因此研究四元数到欧拉角的转换关系十分必要.但是,姿态四元数与欧拉角之间并不存在一一对应的关系.以飞行器姿态为纽带,依据姿态四元数和欧拉角与飞行器姿态之间的内在关系,对各种可能出现的情形进行分析,在控制所对应的期望姿态的牵引下,确定出符合姿态控制利益的姿态四元数到欧拉角的转换关系.鉴于姿态四元数到欧拉角转换关系的复杂性,在飞行器进行大角度姿态机动控制时,建议采用基于四元数的姿态运动模型.