共查询到20条相似文献,搜索用时 80 毫秒
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对将用于同步辐射EXAFS 实验站双晶单色器的晶体进行了双晶衍射失谐抑制高次谐波的实验.结果表明,对Si(111)晶体,当双晶衍射失谐到基波强度只有原来的一半时,高次谐波均消失.本文讨论了Si(222)衍射不完全消光的原因.对Si(220)晶体衍射的情况也进行了简要的讨论. 相似文献
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综合介绍了高分辨X射线双晶衍射技术、三轴晶衍射技术及掠入射衍射和全反射技术.着重介绍了这些技术应用于低维材料微结构探测所取得的新进展. 相似文献
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采用MOCVD技术在Al2O3(0001)衬底上生长了GaN薄膜,使用透射光谱、光致发光光谱和X射线双晶衍射三种技术测试了五类GaN薄膜样品,实验结果表明:GaN薄膜透射谱反映出的GaN质量与X射线双晶衍射测量的结果一致,即透射率越大,半高宽越小,结晶质量越好;而X射线双晶衍射峰半高宽最小的样品,其PL谱的带边峰却很弱,这说明PL谱反映样品的光学性能与X射线双晶衍射获得的结晶质量不存在简单的对应关系,同时还报导了一种特殊工艺生长的高阻GaN样品的RBS/沟道结果。 相似文献
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研究了具有45°内反射镜的0 98μm辐射波长的应变InGaAs/AlGaAs/GaAs单量子阱面发射半导体激光器结构,并采用MBE方法进行了材料制备。同时利用X射线双晶衍射,低温(10K)光致发光(PL)和电化学C V方法检测和分析了外延薄膜的光电和结构特性。在光致发光谱线中我们得到了发射波长0 919μm的谱峰,谱峰范围跨跃0 911~0 932μm,双晶回摆曲线、电化学C V分布曲线显示所设计的结构基本得到实现。 相似文献
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用电化学方法制备了不发光多孔硅和发光多孔硅,用X射线双晶衍射对两类多孔硅表面进行了微结构分析和晶体质量表征,实验表明两类多孔硅的微结构间存在着很大差别。不发光多孔硅表面对X射线的双晶衍射摇摆曲线可解叠成两个峰,它们分别来自样品多孔层和单晶硅衬底,而发光多孔硅对X射线的双晶衍射摇摆曲线呈高斯对称分布,不可解叠。发光多孔硅比不发光多孔硅表面晶体质量差,且电化学腐蚀越严重,表面晶体质量下降也越严重。 相似文献
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We consider slant normal magnetic curves in (2n + 1)-dimensional S-manifolds. We prove that γ is a slant normal magnetic curve in an S-manifold (M2m+s, φ, ξα, ηα, g) if and only if it belongs to a list of slant φ-curves satisfying some special curvature equations. This list consists of some specific geodesics, slant circles, Legendre and slant helices of order 3. We construct slant normal magnetic curves in ?2n+s(–3s) and give the parametric equations of these curves. 相似文献
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运用Landau-Lifshitz方程,边界处动态磁化强度由有效偶极边界条件约束,研究了无限长金属磁条中自旋波传播的特征,得到了该体系抽运微波磁场的阈值曲线以及色散曲线的解析式,揭示出自旋波激发谱与磁条宽度的具体关系.结果表明,平面约束下磁条的阈值曲线中出现了明显的扭结现象.并且随着磁条宽度的增加,其扭结数近似地呈指数形式增加,而最低扭结处两阈值的跳跃差值几乎呈反比形式变化.
关键词:
Landau-Lifshitz方程
有效偶极边界条件
阈值曲线
色散曲线 相似文献
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ZFA等角距曲线的优化设计 总被引:1,自引:0,他引:1
变焦距系统镜组的轴向位移与倍率关系通常不是线性的,示值间距标记也是非均匀的。在光学检测和计量仪器的应用中,操作者很难准确地选择刻度标志之外的焦距值,尤其是在高倍段刻度密集的和非线性显著的地方更是如此。在有电机驱动的系统中,电机匀速转动带来的是倍率的非线性变化,很难在短时间内稳定到预定倍率的目标值。对含有像差因子的变焦函数进行变换后所编制的计算程序可以十分快捷地得到预定的设计结果。一个实际的光学系统往往偏离理想情况,为了达到最佳结果,可把像差因子补充到变焦距函数中,可借助变焦函数方程进行等角距变倍曲线的研究和设计,研究成果已应用到了产品的设计中,并取得了很好的效果。 相似文献
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使用矩形截面磁芯研制了一台磁开关作为脉冲驱动源的主开关,并利用电容器放电法对磁芯不同位置处的磁滞回线进行了测量。结果表明,短边和长边测量得到的磁滞回线均能够适应磁开关需求,不同的励磁位置对磁滞回线形状的影响有限。设计了基于该磁芯的磁开关,使用PSpice软件进行了数值模拟,结果与理论分析相一致。结合卷绕型带状脉冲形成线,对磁开关作为脉冲驱动源主开关进行了实验研究。结果表明研制的磁开关实现了主开关功能,在1.1 的低阻抗负载上获得了峰值电压9 V、上升沿80 ns、脉冲半高宽230 ns的准方波脉冲输出。 相似文献
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The receiver operating characteristic (ROC) curve has been widely used as an evaluation criterion to measure the accuracy of biometrics system. Unfortunately, such an ROC curve provides no indication of the optimum threshold and cost function. In this paper, two kinds of 3D combinational curves are proposed: the 3D combinational accuracy curve and the 3D combinational performance curve. The 3D combinational accuracy curve gives a balanced view of the relationships among FAR (false alarm rate), FRR (false rejection rate), threshold t, and Cost. Six 2D curves can be derived from the 3D combinational accuracy curve: the conventional 2D ROC curve, 2D curve of (FRR, t), 2D curve of (FAR, t), 2D curve of (FRR, Cost), 2D curve of (FAR, Cost), and 2D curve of (t, Cost). The 3D combinational performance curve can be derived from the 3D combinational accuracy curve which can give a balanced view among Security, Convenience, threshold t, and Cost. The advantages of using the proposed 3D combinational curves are demonstrated by iris recognition systems where the experimental results show that the proposed 3D combinational curves can provide more comprehensive information of the system accuracy and performance. 相似文献
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In this paper, we present a real-time measurement and adjustment method, based on scanning imaging, for optical transmitter which emits 90° × 2° linear laser beam. This novel optical arrangement consists of an area array CCD and two linear array CCDs. According to the relationship between the positions, angles of transmitter optical components and the beam parameters of emergent laser, the system can help us to decide the real-time adjustment of optical transmitter by measuring the related beam parameters. In order to improve the measurement speed, avoid occlusion and ensure simultaneous measurement, the two linear array CCDs are placed at near field, far field and separated by a definite angle to acquire the beam intensity distribution through suitable nonlinear correction during the process of scanning. After a complete scanning, the beam parameters and the spot image are acquired by continuous measurement. The proof-of-principle experiments showed that the measurement results were in agreement with the analysis. The presented method was applied to direct fast adjustment for higher quality on the assembly of the optical transmitter. The presented procedure is highly advantageous for diverse laser beam emitted from the optical transmitter, such as elliptic, linear and so on. 相似文献
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This Letter considers the curvature conditions of AW(k)-type (k=1,2,3) null Cartan curves, and investigates null Cartan Bertrand curves. We show that null Cartan Bertrand curves are AW(k)-type (k=1,2,3) curves in Minkowski 4-space. 相似文献