A Solenoid-Type Inductor Fabricated by MEMS Technique

A solenoid-type inductor for high frequency application is realized using a micro-electro-mechanical systems (MEMS) technique.In order to achieve a high inductance value and Q factor,UV-LIGA,dry etching technique,fine polishing and electroplating technique are adopted.The dimensions of the inductor are 1500μm×900μm×70μm,having 41 turns with a coil width of 20μm separated by 20μm spaces and a high aspect ratio of 3.5∶1.The maximum measured inductance of the inductor is 6.17nH with a Q factor of about 6.     

航空航天用新材料的开发现状与展望

尖端科学技术的发展促进了航空航天工业的发展,而航空航天工业的发展又加快了新材料产业的发展并对新材料的性能提出了更为苛刻的要求。航空航天工业的发展历史,在某种意义上讲,实际上就是材料的开发、性能的改善和用途的开拓的历史。从多年来航空工业常用的木材、铁、铜、铝、镁、不锈钢、合金钢.钛合金等材料到现今日益广泛采用的以复合材料为代表的高性能尖端材料来看,无一不是如此。就发展的趋     

加强高校师资队伍建设的思考与措施

师资队伍是高校最重要的资源。教师是高校的第一生产力，是决定大学教育和科研水平的关键因素。文章在分析当前高校师资队伍建设存在的主要问题的基础上，提出了以转变观念为先导，加大人才培养和引进的力度，积极创造人才成长的良好环境等措施，做好高校师资队伍的建设。     

GB／T19000—ISO 9000标准系列的宣贯及一些浅探（Ⅱ）

六、质量体系认证ISO 9000标准系列的发布既是众多经济发达国家质量管理实践经验的科学总结,又是生产力发展的必然产物并适应了国际贸易发展之需要.国内国际的实施采用都表明了它既提高了企业质量管理水平和企业产品在国内外的竞争能力,也有利于保护消费者的利益;对我国的质量管理与国际规范接轨更是意义重大     

苏联铁合金工业的发展现状与动向

苏联的铁合金工业创建于本世纪三十年代,并同其他黑色冶金业一样获得了长足的发展,特别是在七十年代由于钢铁业的飞速发展使铁合金工业的发展达到了高潮,1970～1985年期间新建和投产了30座单:炉容量33～75MV·A的大型铁合金电炉,使铁合金的生产能力翻     

Three-Dimensional Reconstruction of Welding Pool Surface by Binocular Vision

Current research of binocular vision systems mainly need to resolve the camera's intrinsic parameters before the reconstruction of three-dimensional(3D)objects.The classical Zhang'calibration is hardly to calculate all errors caused by perspective distortion and lens distortion.Also,the image-matching algorithm of the binocular vision system still needs to be improved to accelerate the reconstruction speed of welding pool surfaces.In this paper,a preset coordinate system was utilized for camera calibration instead of Zhang'calibration.The binocular vision system was modified to capture images of welding pool surfaces by suppressing the strong arc interference during gas metal arc welding.Combining and improving the algorithms of speeded up robust features,binary robust invariant scalable keypoints,and KAZE,the feature information of points(i.e.,RGB values,pixel coordinates)was extracted as the feature vector of the welding pool surface.Based on the characteristics of the welding images,a mismatch-elimination algorithm was developed to increase the accuracy of image-matching algorithms.The world coordinates of match-ing feature points were calculated to reconstruct the 3D shape of the welding pool surface.The effectiveness and accuracy of the reconstruction of welding pool surfaces were verified by experimental results.This research proposes the development of binocular vision algorithms that can reconstruct the surface of welding pools accurately to realize intelligent welding control systems in the future.     

Effects of Defocus Distance on Three-Beam Laser Internal Coaxial Wire Cladding

Three-beam laser internal coaxial wire feeding cladding is regarded as a promising additive manufacturing technique because it is highly efficient and controllable.In this study,the effects of the defocus distance on cladding using a three-beam laser with internal wire feeding are experimentally and numerically studied.A process map indicating the surface characteristics at different defocus distances with various parameter combinations was developed.The transmission characteristics including laser intensity,beam size,and laser spot distance of the three-beam laser at different defocus distances were analyzed using TracePro software.Based on the TracePro results as heat source,a three-dimensional transient finite element (FE) thermal model was formulated to predict the thermal field,tempera-ture history and molten pool shape at different defocus distances.A molten pool with a flat bottom and low melting depth is generated when the defocus distance is-2.5 mm,whereas when this distance is-1.5 mm,a pool with a valley-shaped bond and high melting depth is formed.The simulated results of the temperature cycle and clad geometry are both validated and found to well agree with experimental measurements.The influence of the defocus distance on the microstructure and microhardness are discussed based on the temperature history and cooling rate.With the increase in the absolute defocus distance,the height and dilution of the clad decreased,whereas the width increased.In addition,the effects of defocus distance with various parameter combinations on clad geometry were explored using the formulated FE model.     

A 7 T Pulsed Magnetic Field Generator for Magnetized Laser Plasma Experiments

A pulsed magnetic field generator was developed to study the effect of a magnetic field on the evolution of a laser-generated plasma.A 40 kV pulsed power system delivered a fast(~230 ns),55 kA current pulse into a single-turn coil surrounding the laser target,using a capacitor bank of 200 nF,a laser-triggered switch and a low-impedance strip transmission line.A one-dimensional uniform 7 T pulsed magnetic field was created using a Helmholtz coil pair with a 6 mm diameter.The pulsed magnetic field was controlled to take effect synchronously with a nanosecond heating laser beam,a femtosecond probing laser beam and an optical Intensified Charge Coupled Device(ICCD) detector.The preliminary experiments demonstrate bifurcation and focusing of plasma expansion in a transverse magnetic field.     

Experimental study on the characteristics of horizontal flame spread over XPS surface on plateau

A series of comparative laboratory-scale experiments were carried out in the Lhasa plateau and the Hefei plain respectively to investigate the characteristics of flame spread over the extruded polystyrene (XPS) foam, a typical thermal insulation material. Flame shape and the temperature profile in solid phase were monitored, and the effects of altitude on the heat transfer process were analyzed. The results show that the temperature rise with time undergoes three stages: the preheating stage, the melting stage and the pyrolysis stage. The durations of the melting and pyrolysis stages on plateau are longer than that in plain, which sequentially results in a lower flame spread rate on plateau. Comparing of the temperature change rate curve on plateau with that in plain, it is found that the peak characteristics of the curves in the pyrolysis stage changed from single peak to multi-peaks, which suggests that the altitude difference might change the pyrolysis mechanisms of XPS material. Moreover, the sample scale effects on flame spread are also explored. Two different regimes are found in flame spread behavior with sample scale at the both altitudes. The spread rate drops with sample scale in convection regime and rises in radiation regime.