新型小周期wiggler的研制

本文提出一种新型小周期wiggler结构,它是由带铁芯的双绕螺旋片组成,产生圆极化磁场,对周期为10mm,长100mm的wiggler原型的磁场进行测量,横向磁场可达1KG,根据现有的加速器,加速电压为400—500keV,提出了输出频率为190GHz的小周期wiggler自由电子激光放大器设计。 关键词：     

Total Dose Radiation Tolerance of Phase Change Memory Cell with GeSbTe Alloy

Phase change memory （PCM） cell array is fabricated by a standard complementary metal-oxide-semiconductor process and the subsequent special fabrication technique. A chalcogenide Ge2Sb2Te5 film in thickness 50hm deposited by rf magnetron sputtering is used as storage medium for the PCM cell. Large snap-back effect is observed in current-voltage characteristics, indicating the phase transition from an amorphous state （higher resistance state） to the crystalline state （lower resistance state）. The resistance of amorphous state is two orders of magnitude larger than that of the crystalline state from the resistance measurement, and the threshold current needed for phase transition of our fabricated PCM cell array is very low （only several μA）. An x-ray total dose radiation test is carried out on the PCM cell array and the results show that this kind of PCM cell has excellent total dose radiation tolerance with total dose up to 2 ×10^6 rad（Si）, which makes it attractive for space-based applications.     

Quantum—Confined Stark Effect of Vertically Stacked Self—Assembled Quantum Discs

We study the electronic energy levels and probability distribution of vertically stacked self-assembled InAs quantum discs system in the presence of a vertically applied electric field. This field is found to increase the splitting between the symmetric and antisymmetric levels for the same angular momentum. The field along the direction from one disc to another affects the electronic energy levels similarly as that in the opposite direction because the two discs are identical. It is obvious from our calculation that the probability of finding an electron in one disc becomes larger when the field points from this disc to the other one.     

Optical spectra and Exciton State in Vertically Stacked Self—Assembled Quantum Discs

We study the oscillator strengths of the optical transitions of the vertically stacked self-assembled InAs quantum discs.The oscillator strengths change evidently when the two quantum discs are far apart from each other.A vertically applied electric field affects the oscillator strengths severely.while the oscillator strengths change slowly as the radius of one disc increases.We also studied the excitonic energy of the system.including the Coulomb interaction.The excitonic energy increases with the increasing radius of one disc.but decreases as a vertically applied electric field increases.     

DMC航空影像的融合技术探讨与实践

本文从数字图像的色彩处理和波段融合的角度出发，阐述了DMC航空影像的融合技术要点，分析了融合过程中产生的问题以及需要解决的技术难点，为提高影像融合的效果打下了基础，并且通过实际的项目应用，验证了本方法的可行性。     

中学生学习《动量和动量守恒》一章的心理分析

文章从学生学习物理的心理特点和思维规律对《动量和动量守恒》一章教材进行了分析。首先分析了教材的特点,接着认真分析了学生学习这章可能产生的思维障碍,然后结合多年教学实践中不断积累的心理分析素材,归纳出克服思维障碍的途径和方法。     

用TREF方法分离聚烯烃共混物

用ＴＲＥＦ方法分离聚烯烃共混物徐君庭，封麟先，杨士林（浙江大学高分子科学与工程学系，杭州，３１００２７）关键词升温淋洗分级，聚烯烃，共混物升温淋洗分级（ＴＲＥＦ）方法是８０年代发展起来的，它按结晶度将聚合物分级［１］，目前主要用于聚烯烃的分级［２，３...     

利用大分子单体技术合成接枝共聚物

大分子单体和小分子共单体共聚是合成接枝共聚物的重要途径之一。本文综述了大分子单体通过各种聚合方式(自由基共聚、离子型共聚、配位共聚、基团转移共聚和逐步共聚)和普通小分子单体的共聚反应,详细讨论了大分子单体和小分子单体的自由基共聚反应动力学,并简要介绍了接枝共聚物的应用背景。     

竖向荷载作用下悬索桥纵向变位特征与机理

为揭示竖向荷载作用下悬索桥纵向变位特征与机理,以主缆变形理论为基础研究了其竖向荷载下的变位特征,并得出了其竖向及纵向位移解析解;在此基础上,分析了竖向荷载作用下传统悬索桥和设有中央扣悬索桥的纵向变位特征及加劲梁纵向位移,揭示了中央扣纵向约束机制,并分别推导了加劲梁在竖向荷载下的纵向位移计算公式;最后,通过算例分析验证所提位移计算公式计算精度. 结果表明：由于主缆的几何非线性特征,竖向位移与纵向位移相互耦合,在非对称竖向荷载作用下,主缆发生非同步纵向位移,而加劲梁主要以类似“摆锤体”发生刚体的纵向位移;跨中处主缆、加劲梁及中央扣因中央扣的存在形成一个“刚域”区,从而导致加劲梁纵向位移减小;所提计算方法与有限元数值解法在不同竖向荷载工况下吻合良好.     

自升式海洋石油平台液压机构动力学分析

通过对石油平台支撑结构的动力分析,找出了导致支撑液压缸发生永久型塑性形变的原因,提出改造后控制策略应注意的技术问题,可以供液压工程师参考使用。