Photonic generation of arbitrary waveforms based on incoherent wavelength-to-time mapping

We demonstrate experimentally a radio frequency arbitrary waveform generator using the incoherent wavelengthto-time mapping technique.The system is implemented by amplitude modulation of a broadband optical resource whose spectrum is reshaped by a programmable optical pulse shaper and transmitted over a single mode fiber link.The shape of the generated waveform is controlled by the optical pulse shaper,and the fiber link introduces a certain group velocity delay to implement wavelength-to-time mapping.Assisted by the flexible optical pulse shaper,we obtain different shapes of optical waveforms,such as rectangle,triangle,and sawtooth waveforms.Furthermore,we also demonstrate ultra-wideband generation,such as Gaussian monocycle,doublet,and triplet waveforms,using the incoherent technique.     

Some remarks on the modulus of continuity of a conformal mapping of the disk onto a Jordan domain

Letd(;z, t) be the smallest diameter of the arcs of a Jordan curve with endsz andt. Consider the rapidity of decreasing ofd(;)=sup{d(;z, t):z, t , ¦z–t¦} (as 0,0) as a measure of nicety of . Letg(x) (x0) be a continuous and nondecreasing function such thatg(x)x,g(0)=0. Put¯g(x)=g(x)+x, h(x)=(¯g(x))². LetH(x) be an arbitrary primitive of 1/h ^–1(x). Note that the functionH ^–1 x is positive and increasing on (–, +),H ^–1 0 asx– andH ^–1+ asx +. The following statement is proved in the paper.Translated fromMatematicheskie Zametki, Vol. 60, No. 2, pp. 176–184, August, 1996.This research was supported by the Russian Foundation for Basic Research under grant No. 93-01-00236 and by the International Science Foundation under grant No. NCF000.     

（T＋λI）－1不一定是非扩张映射

设Ｔ是ｍ-增生算子，Ｉ是恒等映射．本文通过一个反例说明（Ｔ＋λＩ）^－1（λ＞０）不一定是非扩张映射．     

Crumpled laminations and manifolds of nonfinite type

Using a group-theoretic construction due to Bestvina and Brady, we build -manifolds which admit partitions into closed, connected -manifolds but which do not have finite homotopy type.

     

Solving two-Level variational inequality

An approach to solving a mathematical program with variational inequality or nonlinear complementarity constraints is presented. It consists in a variational re-formulation of the optimization criterion and looking for a solution of thus obtained variational inequality among the points satisfying the initial variational constraints.This research was supported by the Russian Fundamental Research Foundation, Grant No. 93-012-842     

导体栅的静电屏蔽作用

采用保角变换的方法 ,计算了导体栅作屏蔽罩时的场强分布 ,所得结果表明导体栅具有很好的静电屏蔽作用     

间隙线性反馈控制混沌

提出了两种控制混沌的线性间隙反馈方法.该方法由控制相和非控制相组成,通过选取合适的反馈系数和控制相时间,可以获得各种不同的所需稳定的周期轨道.分别对一维的声光双稳系统和二维的类Henon吸引子进行计算机模拟,表明该方法可以使既定的系统按照给定的周期轨道演化,并且是大范围可控的. 关键词： 间隙线性反馈 混沌 类Henon映射 Lyapunov指数     

主被动光学图像融合技术研究

本文应用扫描式激光成像雷达获取试验数据并实现对激光数据的三维成像处理,给出了基于目标特征的激光雷达图像与被动光学图像的数据融合方法,实现了激光图像和光学图像间的三维融合。试验结果表明,本文所提出的基于目标特征的两种不同质图像间的融合方法是可行的,融合后的图像具有丰富的光谱信息和三维立体信息。     

Chemical depth profiling and 3D reconstruction of III–V heterostructures selectively grown on non‐planar Si substrates by MOCVD

The chemical characterization of novel 3D architectures with nanometre‐scale dimensions is extremely challenging. The chemical composition of InGaAs/AlAs quantum wells selectively grown in SiO₂ trenches, 100–300 nm wide, is studied. Combining high lateral resolution 3D ToF‐SIMS analysis and Auger measurements, the chemical composition of individual trenches was obtained confirming the uniformity of these III–V heterostructures. These results correlate well with an average approach using SIMS depth profiling. The effects of ion beam orientation on the surface topography of confined structures were highlighted. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

空间遥感测绘光学系统研究综述

将遥感技术应用到测绘当中是现代地质测绘技术的发展趋势,随着光学载荷分辨率的不断提高,遥感测绘已经成为社会发展和国民经济发展的重要保障。光学载荷决定了测绘空间遥感器的分辨率、测绘精度、卫星平台体积与重量,是遥感器的核心部分。本文对高成像质量透射光学系统、同轴三反光学系统、离轴三反系统等常用的空间遥感测绘光学系统的结构形式和光学性能分别进行了介绍,并对处于研发阶段的新型空间反射光学系统的结构形式和光学性能进行了展望。分析认为,根据不同的应用环境和技术指标,合理选用不同种类的遥感测绘光学系统,可以最大程度利用平台资源,满足遥感测绘需求。