纳米多层膜的电性能及表面形貌

用热蒸发沉积和自然氧化法制备纳米量级的Al／Al2O3及Cr／Cr2O3薄膜和多层膜．本文采用三点法测定了常温、低温下的U—I特性，发现常温、低温下纳米量级的Al／Al2O3及Cr／Cr2O3薄膜具有类似负阻的特性。SEM检测表明，薄膜表面均匀，薄膜的厚度和称重法所得的厚度基本相符．AFM和STM观察表明薄膜表面存在着岛状结构，表面粗糙度在纳米尺度范围内。     

不同底层(Ag, Ti, Cu, Pt)对[Fe/Pt]n多层膜磁性的影响

利用磁控溅射的方法, 在热玻璃基片上制备了[Fe/Pt]n多层膜, 经不同温度真空热处理后, 得到L10有序结构的FePt薄膜(L10-FePt).实验结果表明 [Fe/Pt]n多层膜结构可使FePt薄膜的有序化温度由500 ℃降到350 ℃, 350 ℃退火20 min后其平行膜面矫顽力可达到421.8 kA·m-1.同时以Ag, Ti, Cu和Pt做底层, 利用[Fe/Pt]n多层膜结构制备了FePt薄膜, 磁性和X射线衍射结果表明 与[Fe/Pt]n多层膜相比, 四种底层均没有进一步降低FePt薄膜的有序化温度, 其中Ag做底层对[Fe/Pt]n多层膜退火后的平行膜面矫顽力影响较小, 但能够提高其垂直磁各向异性;其他底层均会降低[Fe/Pt]n多层膜在高温退火时的平行膜面矫顽力, 且对其垂直磁各向异性无改善作用.     

Efficient and accurate multilayer solid‐shell element: non‐linear materials at finite strain

We present in this paper an efficient and accurate low‐order solid‐shell element formulation for analyses of large deformable multilayer shell structures with non‐linear materials. The element has only displacement degrees of freedom (dofs), and an optimal number of enhancing assumed strain (EAS) parameters to pass the patch tests (both membrane and out‐of‐plane bending) and to remedy volumetric locking. Based on the mixed Fraeijs de Veubeke‐Hu‐Washizu (FHW) variational principle, the in‐plane and out‐of‐plane bending behaviours are improved and the locking associated with (nearly) incompressible materials is avoided via a new efficient enhancement of strain tensor. Shear locking and curvature thickness locking are resolved effectively by using the assumed natural strain (ANS) method. Two non‐linear 3‐D constitutive models (Mooney–Rivlin material and hyperelastoplastic material at finite strain) are applied directly without requiring the enforcement of the plane‐stress assumption. In particular, we give a simple derivation for the hyperelastoplastic model using spectral representations. In addition, the present element has a well‐defined lumped mass matrix, and provides double‐side contact surfaces for shell contact problems. With the dynamics referred to a fixed inertial frame, the present element can be used to analyse multilayer shell structures undergoing large overall motion. Numerical examples involving static analyses and implicit/explicit dynamic analyses of multilayer shell structures with both material and geometric non‐linearities are presented, and compared with existing results obtained from other shell elements and from a meshless method. It is shown that elements that did not pass the out‐of‐plane bending patch test could not provide accurate results, as compared to the present element formulation, which passed the out‐of‐plane bending patch test. The present element proves to be versatile and efficient in the modelling and analyses of general non‐linear composite multilayer shell structures. Copyright © 2005 John Wiley & Sons, Ltd.     

Approximate Feedback Linearisation Using Multilayer Neural Networks

In this paper we introduce the approximate feedback linearisation using multilayer feedforward neural networks. We propose to approximate a basis of the one-dimensional codistribution of an affine nonlinear system with the derivative of a multilayer neural network [6] and form a change of coordinates with n multilayer neural networks [5]. In this paper we will prove that the transformation can define a local diffeomorphism, with which a local stabilising feedback law can be designed for a kind of non-linearisable nonlinear systems.     

CN<em>x/TiN多层复合涂层抗水蚀性能的研究

采用多弧-磁控溅射镀膜机在不锈钢2Cr13衬底上沉积CN_<em>x/TiN多层复合涂层。利用光电子能谱仪(XPS)和透射电子衍射(TED)对涂层的组成和结构进行分析。利用自行研制的高压水蚀试验装置对不锈钢、高铬铸铁、司太立合金以及CN_<em>x/TiN多层复合涂层的抗水蚀性能进行对比试验,最后对涂层的水蚀失效机理进行了探讨。试验结果表明:CN_<em>x/TiN多层复合涂层具有较高的硬度、附着力、抗热冲击性能以及优异的抗水蚀性能,是一种优良的汽轮机末级叶片抗水蚀用涂层。     

纳米金刚石计算机磁头抛光液的研制及应用

用聚氧乙烯型非离子表面活性剂可有效分散纳米金刚石于油介质中,由此制得了纳米金刚石抛光液,探讨了纳米金刚石的分散机理,认为庞大的亲水性基团聚氧乙烯基象一巨大的屏障膜,使纳米金刚石颗粒在油中相互弹开,削弱颗粒间的相互作用能,阻止了纳米颗粒的重新团聚,从而实现了纳米金刚石在油中的稳定分散.本文研制的纳米金刚石抛光液应用于计算机磁头的精抛光,能降低计算机磁头表面粗糙度50%以上,解决了计算机磁头行业的技术难题.实验结果表明,纳米金刚石是一种理想的计算机磁头抛光材料.     

Development of a system for measurement of permeability of aroma compounds through multilayer polymer films by coupling dynamic vapour sorption with purge‐and‐trap/fast gas chromatography

A system for measurement of permeability of aroma compounds through laminated polymer films was constructed by combining dynamic vapour sorption (DVS) with purge‐and‐trap/fast gas chromatography (P&T–fGC). Data validation was achieved by measuring the permeability of limonene across an HDPE film (film C) and comparing the permeation data with the literature values. The general applicability of this system, as well as its potential for simultaneous measurement of permeability of multiple aroma compounds, was demonstrated by measuring the permeability of limonene and ethyl butyrate as single permeants or as co‐permeants under different environmental conditions (at 25°C, 30°C or 35°C and 0% or 75% RH) through three different multilayer polymer films (film A, HDPE/EVOH/HDPE/HDPE; film B, HDPE/nylon/HDPE/HDPE; film C, HDPE/HDPE). The results showed that the aroma barrier performance of plastic films was determined by the polymer composition and was affected by various factors, such as temperature and the presence of other co‐permeants. Simplicity, speed and accuracy were some of the attractive features of this system, which indicates its potential as a useful tool that could be applied in the food industry for screening or selection of appropriate packaging materials for specific applications. Copyright © 2004 John Wiley & Sons, Ltd.     

网络控制论的多层多重视点模型体系研究

建模分析是网络控制论中重要的分析方法,传统的模型不能全面地描述并分析网络控制论系统中的复杂问题。首先提出了多层多重视点模型体系;然后从网络控制论系统模型的分类、多层多重视点模型体系和建模的一般步骤3个方面,详细阐述了网络控制论的多层多重视点模型体系;通过实例表明:多层多重视点模型体系具有全局性、清晰性和主动性的特点,是分析网络控制论系统的一种有效方法。     

腊样芽孢杆菌DM423分批培养过程中生物量的人工神经网络软测量

利用静态多层前馈神经网络模型对腊样芽孢杆菌(Baeillus cereus DM423)(简称DM423)分批培养过程的生物量进行软测量.构建了以培养时间、温度、pH、溶氧和葡萄糖浓度作为网络的输入变量,生物量浓度为输出变量的5-5-1型的3层前馈网络,网络对DM423的生物量浓度估算精确度较好.分别对葡萄糖浓度、pH和溶氧的实际测量值施加干扰,对网络的鲁棒性进行检测,结果表明,所建立的神经网络具有一定的抗干扰能力.     

X射线超反射镜设计

阐述了一种新的X射线超反射镜的设计方法,它是基于经验理论公式的解析设计方法和基于计算机的数值优化设计方法相结合的产物。利用前者提供比较好的初始膜系,再利用后者对该初始膜系进行优化处理,从而获得比较好的设计结果,并大大减少了计算时间。讨论了实际制作出的多层膜存在的表面粗糙度及膜层材料间的相互扩散对多层膜反射性能的影响,并给出了模拟计算的结果。依据上述方法,在比较大的掠入射角情况下,设计出了具有较宽反射带宽的W/CX射线超反射镜。