A new method of characterization for stratified thermal energy stores

A new method for characterization of stratified thermal energy stores (TES) that integrates both the first law and the second law concerns is presented here. The first law concern is incorporated into a quantity called energy response factor and the second law concern into an entropy generation ratio. A product of these two quantities is at the heart of the TES efficiency definitions. This approach removes the overemphasis of the existing methods either on the first or the second law of thermodynamics which often biases the characterization results. The information about the evolution of the temperature field of the system in time is the prerequisite of the new method. It may be obtained from experiments or from suitable numerical simulations. The current method can be easily integrated into computational fluid dynamic (CFD) simulations and thus facilitate CFD-based design analysis. As an example of such CFD-integrated analysis, a large-scale hot water seasonal heat store is numerically studied to identify the effects of aspect ratio, containment shape, internal structures, and containment size on their efficiency. The results suggest the effectiveness of the new method in deriving useful design insights.     

氮化镓低维纳米结构的制备与表征

主要是以氧化镓为原料,通过气相沉积法,制备出GaN纳米线和纳米带.通过X-射线衍射（XRD）,扫面电镜（SEM）和高分辨透射电镜（HRTEM）等测试手段对其形貌进行了表征和分析.研究了实验过程中工艺条件的改变对所制备GaN纳米结构形貌特征的影响.对两种GaN纳米材料的拉曼散射光谱进行了分析.     

CVD金刚石工具膜生长特征SEM观察

本文用不热形变栅状直丝化学气相沉积（ＣＶＤ）法生长金刚石膜，在Ｓｉ及ＷＣ－Ｃｏ硬质合金衬底上金刚石膜晶面显露规律随衬底温度和甲烷浓度而异，经适当表面处理及选择合适的工艺条件，当生长初期衬底上就呈现出良好晶形的沉积膜，衬底与膜之间的粘结力能得到提高。Ｒａｍａｎ谱分析表明此膜仅具有特征金刚石１３３２ｃｍ￣（－１）峰，通过ＳＥＭ观察揭示出盒刚石膜可在表面、侧面及棱上生长，并与衬底有良好的联结。     

A new surface characterization technique: RIMAPS (Rotated Image with Maximum Average Power Spectrum)

This work introduces a new imaging technique, Rotated Image with Maximum Average Power Spectrum (RIMAPS), for use in determining orientation and characteristics of surface topography. It consists of computing the maximum value of the averaged power spectrum, given by one step of the two‐dimensional Fourier transform, for each angle of rotation of a digitized image. The basic measurement science of this technique is described and different cases are studied. The characterization of simple geometrical figures explains the meaning of peaks and their angular positions given by RIMAPS analysis. A known surface pattern made on a sample of pure copper, mechanically ground, is used to study reproducibility, dependence on image quality and topography scale relative to pixel size and magnification. Samples of pure zinc, mechanically ground and chemically etched, were used to show the main features of RIMAPS analysis when characterizing a more complicated pattern on a real surface. All the studies performed under different conditions for observation and acquisition of images give strong evidence of the stability and robustness of RIMAPS as a technique for the characterization of topography.     

Screening of supports for the immobilization of pectinmethylesterase from acerola (Malpighia glabra L)

A partially purified extract of pectinmethylesterase (PME) from acerola fruit was immobilized on various supports: glass, celite, chrysotile, agarose, concanavalin A Sepharose 4B, egg shell, polyacrylamide and gelatin. In addition, reticulation with glutaraldehyde was assessed, as well as the use of gelatin in the presence of celite, glass and silica. The highest immobilization yields were obtained when the pectinmethylesterase was immobilized in concanavalin A Sepharose 4B (81.7%) and in gelatin‐water (78.0%). Copyright © 2004 Society of Chemical Industry     

超声珩磨在发动机缸套光整加工中的应用研究

本文介绍了发动机缸套的新型加工工艺-功率超声珩磨的原理。特点，装置组成。关键技术，工艺效果以及其应用前景。     

Low Temperature Elastic Constants of Polycrystalline MgB2

We have used a resonant ultrasound spectroscopy technique to measure the bulk and shear modulus of fully dense, polycrystalline MgB₂ between 4 and 300 K. Both moduli show good agreement with published first principle calculations. The internal friction shows a broad maximum around 40 K.     

用超声处理在石墨表面形成梯度孔洞

研究了超声处理对石墨表面状况的影响。超声处理初期，增加超声处理时间使石墨显气孔率增加，表面孔洞数量增多，尺寸变大；超声处理5min后，超声处理时间增加，显气孔率和孔洞状态基本不变。用超声处理能在石墨表面内层附近形成比较理想的梯度分布孔洞。     

纳米镓/聚甲基丙烯酸甲酯复合材料的原位超声合成与表征

超声作用于低熔点金属镓,使其超细化为纳米级的镓粒子,并采用无引发剂的乳液聚合方法制备出GA/聚甲基丙烯酸甲酯(PMMA)纳米复合粒子,并分析了其微观结构。结果表明纳米镓的形态和结构因有无表面改性剂而不同;乳液聚合得到的纳米镓复合粒子是核壳结构型,粒子大小为50~80 NM,内核金属镓粒径为30~50 NM,与聚合物存在一定的化学作用。     

半导体元件清洗技术浅谈

随着社会的进步和科学技术的迅猛发展,对洗净技术的要求也越来越高。清洗方式多种多样,但最主要的是突出在喷射清洗和超声波清洗两大方面,应用于全国各行各业,并且也得到了明显进步。