SL(n+1,R)/S(GL(1,R)×GL(n,R))上线丛的一个超几何方程

本文研究了伪黎曼对称空间SL（n+1,R）/S（GL（1,R）×GL（n,R））线丛上的微分方程.利用李代数方法,即Casimir算子得到这个微分算子.这个微分算子是一个超几何方程,这个结论推广了文献[1,3,5]中的微分方程.     

非线性双曲型时滞偏微分方程解的振动性质

In this paper, oscillatory properties of solutions of certain hyperbolic partial differential equations with multi-delays are investigated and a series of sufficient conditions for oscillations of the equations are established. The results fully indicate that the oscillations are caused by delays.     

Light-controlled pulsed x-ray tube with photocathode

Unstable mechanical structure, low energy efficiency, and cooling requirements limit the application of conventional x-ray tubes based on filament as cathode in several academic areas. In this paper, we demonstrate a light-controlled pulsed x-ray tube using multialkali cathode as electron generator. The photocathode active area of the light controlled x-ray tube is 13.2 cm² (41 mm in diameter), which provides high photoelectron-emitting efficiency up to 0.288 mA/lm in 460-nm LED and 2.37-mA maximum tube current. Furthermore, the modulation ability from 1 kHz to 100 kHz of the x-ray tube is tested. The results suggest that the light-controlled pulsed x-ray tube has easy modulation and short x-ray pulse properties and is promising to be the next generation x-ray tube with wide applications in medical radiation therapy as well as the calibration for detectors and scintillators.     

基于超快激光调制的纳秒脉冲X射线发射源

面向基础科学与空间应用研究领域对小型化超快脉冲X射线发射源的需求,设计并研制了基于激光调制光源与光电阴极X射线管的超快脉冲X射线发生器,解决了传统X射线调制发射装置重复频率低、时间稳定性差、脉冲特性差等应用难题.本文主要开展了脉冲X射线发生器的超快调制控制模块研究,并利用基于预调制的激光控制光源实现了高时间精度、高时间稳定度的超快时变光子信号以及纳秒脉冲X射线产生.理论方面,建立了脉冲X射线发生器时间响应模型,分析了出射脉冲X射线的时域时间特性.实验方面,搭建了基于超快闪烁体探测器的脉冲X射线时间特性实验测试系统,测试了激光控制光源及脉冲X射线发射源的时间特性参数.实验结果表明脉冲X射线发生器可同时实现高重频(12.5 MHz)、超快脉冲(4 ns)、高时间稳定度(400 ps)特性,且与所建立的理论模型高度符合.相比于传统X射线调制方案,脉冲时间参数指标得到了大幅提升、应用场景获得了极大拓展,本项研究有望为实现超高时间稳定性、超快脉冲X射线发射源提供新思路.     

问题驱动教学法的研究与实践

Abs从教育的功能人手,通过对创新能力的分析,得出结论“一切思维和能力的培养皆依赖于问题的发现、分析与解决”,由此提出“问题驱动教学法”,同时给出该教学法的流程模式,并以“概率论与数理统计”课程的教学为例对该教学法进行具体说明.trcat