H2O based different nanofluids with unsteady condition and an external magnetic field on permeable channel heat transfer

This paper investigates numerically the problem of unsteady magnetohydrodynamic nanofluid flow and heat transfer between parallel plates due to the normal motion of the porous upper plate. The governing equations are solved via the fourth-order Runge-Kutta method. Different kind of nanoparticles is examined. The effects of kind of nanoparticle, nanofluid volume fraction, expansion ratio, Hartmann number, Reynolds number on velocity and temperature profiles are considered. Also effect of different types of nanoparticles is examined. Results indicate that velocity decreases with increase of Hartmann number due to effect of Lorentz forces. Rate of heat transfer increase with increase of nanofluid volume fraction, Hartmann number and Reynolds number but it decreases with increase of expansion ratio. Also it can be found that choosing copper as a nanoparticle leads to highest enhancement.     

高压辊磨机制备高活性氢氧化铝晶种

结合高压辊磨机在冶金球团行业的应用经验,对高压辊磨机制备高活性氢氧化铝晶种工艺进行了探讨。经过高压辊磨机处理后的氢氧化铝晶种产生大量断裂面,比表面积、微观缺陷和活性点数量增加,晶种与铝酸钠溶液间的固液界面扩大,饱和铝酸钠溶液的分解率显著提高,对现场工艺和指标改善具有借鉴意义。     

拉挤型玻璃纤维管受压屈曲分析

基于二维Hashin准则,应用有限元软件ABAQUS对各种常见边界条件下拉挤型GFRP管的受压进行了屈曲分析,探究拉挤型GFRP管在各种简单边界条件下的破坏模式及破坏临界长细比,对于工程实际中拉挤型GFRP压管的应用提供参考。     

Modeling and analysis of an over-constrained flexure-based compliant mechanism

Bridge-type micro-displacement amplifier with flexure hinges is a classic displacement amplification mechanism. Existing theoretic models cannot predict its amplification ratio and input stiffness accurately and make it very difficult to confirm the amplifier’s performance and error compensation by means of these models, which is very significant in ultra-precision positioning. This paper focuses on the development of design equations that can accurately calculate the ideal displacement amplification ratio and input stiffness of the amplifier based on the thought of statically indeterminate structure. Force Method, Maxwell–Mohr Method, principle of superposition and deformation compatibility are used together to establish uncanonical linear homogeneous equations. The analytical results are verified by FEA simulations. The influence of the geometric parameters on the amplifier performance is investigated. It is noted that amplifier performance is more sensitive to the longitudinal distance of flexure hinges. Besides, two same-sized amplifiers with the opposite output directions can be clearly differentiated by these equations.     

射线检测中偏心透照方法探讨

在射线内透偏心法透照中,采用一次贴片,多次曝光,分次取片的检测方法效率高,但是检测人员容易忽视透照厚度比K值的变化,使得K值不符合标准要求。本文通过计算与分析,提出在内透偏心法透照中应首先确定一次最大偏心距离Smax,再通过和实际偏心距离对比,确定曝光方式,并提出在偏心透照方法中为保证底片的黑度和灵敏度应注意的一些问题。     

Estimation of Binding Constants of Cd(II), Ni(II) and Zn(II) with Polyethyleneimine (PEI) by Polymer Enhanced Ultrafiltration (PEUF) Technique

Abstract

Continuous and batch processes of polymer enhanced ultrafiltration for the estimation of binding constants of divalent cadmium, nickel, and zinc ions have been elaborated. Polyethyleneimine was used as a complexation agent. Effect of pH and ionic strength on the binding ability of target metal ions to polyethyleneimine were estimated by continuous mode PEUF system. A mathematical model was developed to estimate apparent complexation constants of metal ions with PEI. The development of this model, which is in good agreement with experimental data, enables to compare the data obtained in both continuous and batch system and correlate the effect of pH and ionic strength with apparent binding constants.     

桥式起重机轮跨比研究

介绍了桥式起重机轮跨比与桥架的自锁有密切关系的理论基础,详述了国内外相关技术资料关于轮跨比的推荐值,对国内外同类产品的轮跨比进行了详细的统计分析,并阐述了轮跨比与啃轨之间的关系,说明如果轮跨比取值较小时,务必保证产品的制造、安装工艺,严格满足各项要求.