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21.
硬盘驱动器巨磁电阻(GMR)磁头:从微米到纳米   总被引:7,自引:0,他引:7  
蒋致诚 《物理》2004,33(7):529-533
近年来电脑硬盘存储密度的飞速增长(年增长100%)已超出摩尔定律的预言.这种惊人的高速增长中,最关键的因素是自旋阀纳米多层膜结构,即巨磁电阻(GMR)读传感器磁头的应用.事实上,巨磁电阻磁头读传感器(reader sensor)已经实现由微电子器件向纳米电子器件转化,并且形成大规模产业.这一过程包含了自旋电子学、材料科学、微电子工程学、化学、微机械力学和工程学等诸学科和相关微加工技术综合性挑战极限,进入纳米科技领域实质性进步.  相似文献   
22.
According to the concept of the recognized visual space of illumination (RVSI) the lightness of an object surface is perceived in relation to its conceptualized size. To prove this proposition the lightness of gray test patches was judged when they were located at various positions inside an illuminated space composed of two rooms in the depth direction from a subject. No retinal image arrangement was changed in the test patch and its immediate surroundings, but the front room had walls, floors and furniture lower in lightness by the amount of N1.5 than the back room to make the RVSI of the former smaller despite the illuminance in the entire space being the same. The results showed that the apparent lightness of the patches was perceived higher by amount of about 13 in L units for the N4 test patch and about 20 for N6 when the patches were located in the front room, in accordance with the prediction. It was stressed that the experiment of lightness judgment should be conducted in a three dimensional space rather than two dimensional plane as done by several investigators.  相似文献   
23.
The coupled model has been developed in this study for moisture transport and beat exchange in soil. The model is driven by atmospheric conditions measured in a field. The concept that soil has a surface resistance to evaporation is introduced in order to relate the evaporation from surface with the vapour flux in air. With the use of this concept, the simulation results agree quite well with the measured data.  相似文献   
24.
本文介绍一种电阻温度系数微机测定实验的系统。  相似文献   
25.
詹Wei民 《应用光学》1995,16(5):47-48
通过实验分析确立了把光纤电阻作为衡量气密性碳涂覆光纤通过2%应变筛选的过渡标准。要拉制2%应变筛选的碳涂覆光纤,其电阻值应小于30kΩ/cm。  相似文献   
26.
介绍铌材超导腔的研制进展,重点讨论了国产铌腔的材料改性,以及相应的超导腔性能的改进.叙述了1.5GHz铌腔的腔形设计,分析了铌材的射频性能和机械性能,制定了铌腔制作与后处理的特定工艺.最后给出了1.5GHz铌材超导腔的低温实验结果.  相似文献   
27.
An evolutionary method for optimization of plate buckling resistance   总被引:9,自引:0,他引:9  
Optimization of plate buckling resistance is very complicated, because the in-plane stress resultants in the prebuckled state of a plate are functions of thickness distribution. This paper discusses the problem of finding the optimum thickness distribution of isotropic plate structures, with a given volume and layout, that would maximise the buckling load. A simple numerical method using the finite-element analysis is presented to obtain the optimum thickness distribution. Optimum designs of compression-loaded rectangular plates with different boundary conditions and plate aspect ratios are obtained by using the proposed method. Optimum designs from earlier studies and the methods of buckling analysis used to attain these results are discussed and compared with the designs from the proposed method. This paper also examines the reliability of the optimality criterion generally used for plate buckling optimization, which is based on the uniform strain energy density.  相似文献   
28.
Development and application of high strength ternary boride base cermets   总被引:8,自引:0,他引:8  
Reaction boronizing sintering is a novel strategy to form a ternary boride coexisting with a metal matrix in a cermet during liquid phase sintering. This new sintering technique has successfully developed world first ternary boride base cermets with excellent mechanical properties such as Mo2FeB2, Mo2NiB2 and WCoB base ones.In these cermets Mo2FeB2 and Mo2NiB2 base ones consist of a tetragonal M3B2 (M: metal)-type complex boride as a hard phase and a transition metal base matrix. The cermets have already been applied to wear resistant applications such as injection molding machine parts, can making tools, and hot copper extruding dies, etc.This paper focuses on the characteristics, effects of the additional elements on the mechanical properties and structure, and practical applications of the ternary boride base cermets.  相似文献   
29.
Supported gold catalyst for eliminating hydrogen from CO2 feed gas in the production of urea is found to be superior to other industrial catalysts (e.g. Pt/Al2O3 and PdPt/Al2O3) in catalytic activity and resistance to sulfur poisoning.  相似文献   
30.
斑图是在空间或时间上具有某种规律性的非均匀宏观结构,普遍存在于自然界,事实上大多数电化学体系在适当参数范围内也可以形成各种电化学斑图。本文介绍了电化学斑图中空间耦合的三种方式,重点总结了在不同机理作用下可能出现的斑图种类,并简述了电化学斑图模拟方面的发展。  相似文献   
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