多段双折射光纤构成环镜滤波器的滤波特性

讨论了多段双折射光纤构成环镜滤波器的滤波特性。从理论上得到了N段双折射光纤构成环镜滤波器滤波特性的结果;具体给出了N为1、2和3时的具体表达式;分析了所构成的环镜滤波器的偏振无关特性;讨论了双折射光纤的长度、拍长、双折射光纤之间夹角等因素对滤波器滤波特性的影响;最后,做了相关的实验验证。所得到的实验结果和理论模拟结果非常吻合。证实了理论的正确性。基于多段双折射光纤构造的滤波器。稳定性优于一般的全光纤马赫—曾德尔干涉仪型滤波器。具有结构简单,灵活性强,偏振无关,插入损耗小和成本低等优点,在光纤传感解调,调谐光纤激光器和光纤通信滤波器等领域具有巨大的应用前景。     

Magnetointersubband Oscillations of the Two-Dimensional Electron Gas in AlxGa1-xN／GaN Heterostructures

Shubnikov-de Haas (SdH) measurements are performed over a temperature range of 1.5-20 K in Al0.22 Ga0.78N/GaN heterostructures with two subbands occupied. In addition to an intermodulation between two sets of SdH oscillations from the first and second subbands, a beating in oscillatory magnetoresistance at 12K is observed, due to the mixing of the first subband SdH oscillations and ‘magnetointersubband‘ (MIS) oscillations. A phase shift of π between the SdH and MIS oscillations is also clearly identified. Our experimental results, i.e. that the SdH oscillations dominate at low temperature and MIS oscillations dominate at high temperature, fully comply with the expected behaviour of MIS oscillations.     

全光纤瓦级纳秒脉冲掺Yb放大器

采用单模放大和包层抽运放大的级联方式,在主振荡功率放大系统中,将平均功率0.5 mW、脉宽20 ns以及重复频率为50 kHz的光脉冲安全放大到平均功率0.6 W、峰值功率600 W的脉冲输出.相应增益为30.8 dB.放大输出的脉冲信号信噪比为30 dB,脉冲形状基本没有发生畸变.在前置放大结构中抽运光通过级联熔融拉锥型波分复用器耦合,有效确保了抽运源(976 nm)的正常工作.     

二维氢原子的相对论修正

求解了二维氢原子的Ｄｉｒａｃ方程,得到了精确的相对论能级与波函数,并详细讨论了非相对论极限。     

一维波动方程反问题求解的正则化方法

讨论了一维波动方程u_{tt-∂x(μ(x)ux)=0在一般的初、边值条件和附加条件下系数μ(x)的求解方法.把反问题归结为一不适定的非线性积分方程组,利用正则化方法克服了反问题的不适定性.}     

Description of the Structural Properties of Low-Lying States in ^102Ru with IBM2

We describe the properties of low-lying states of ^102Ru within the framework of the proton-neutron interacting model IBM2. The theoretical predictions of the ground state, quasi-γ and quasi-β bands, and the ratios of the B（E2） transition strengths are reproduced very well. The structural properties of ^102Ru are identified in the parameters space of the interacting boson model （IBM2）. The characteristic feature of the energy spectrum structure exhibits that ^102Ru is very close to the critical point of Uπv（5）-Oπv（6） transition and towards Uπv（5） symmetry. The key sensitive quantities of the B（E2） branching ratio clearly indicate that ^102Ru is a primary Oπv（6） symmetry, while with a somewhat Uπv（5） symmetry. It is possible that the shape coexistence persists in ^102Ru, whereas the evident fingerprint of the shape coexistence has not been observed.     

主次双波长计算光度法测定铁的研究(Ⅰ)--phen-Fe(Ⅱ)显色体系测定水中铁

利用主次双波长光度法,通过Fe(Ⅱ)-phen显色体系,依据显色体系吸光度A与照射波长λ及物质浓度x间关系,提出了测定铁的主次波长新光度法,精密度提高,检出限降低.     

Dielectric and Pyroelectric Properties of （Pb0.50Sr0.50）TiO3 Ceramics

Lead strontium titanate （Pb0.50Sr0.50）TiO3 （PST） ceramics are prepared by the traditional ceramic processing. The dielectric constants and dielectric loss have been investigated in a temperature range from 25℃ to 300℃. The maximum dielectric constants for unpoled and poled samples are 9924 and 9683, respectively. The temperatures of phase transition for unpoled and poled samples are observed at 153℃ and 157℃, respectively. The phasetransition temperatures for unpoled and poled samples are not equal, which results from the polarization state of the domains. The remnant polarization and the coercive electric field are 18 uC/cm^2 and 6 kV/cm, respectively, from polarization-electric field （P - E） hysteresis loop. The temperature dependence of pyroelectric coefficients of the PST ceramics is measured by a dynamic technique. The dielectric constant and loss Lan δ of the poled PST ceramics are 813 and 0.010, respectively. The pyroelectric coefficients and figure of merit are 294 uC/cm^2 K and 13.6 × 10^-6 pa^-0.5, respectively, at room temperature 25℃and frequency lOOHz.     

课外练习

如图是3只3的正方形,求图中匕1 艺2十… 艺9的度数之和.2.分别以△ABC的三个 顶点A、B、C为圆心画 三个半径相等的圆(圆 的直径小于各边长), 三个圆与△ABC公 共部分的面积之和为 8二cmZ,求圆的半径之 长为多少?[自编」3.已知:。,b,。,d满足a b一c d,彭 澎一产 dZ,求证:aZoO4 bZoo4一eZood d2004.求一李一十下井~ … 2了1一卜1丫23了2 2了3100、/丽 99甲产饭万的值.2.已知正数二与y,且x y一6,试求 、于不万的最小值3.正数a,b,。,A 十亡一k_证明:、B、C满足a十八一0下月一‘aB bC十‘A<澎.已知二次函数y一a尹 bx十2004(a<。,b毛。…     

PMSM系统的参数稳定性分析和自适应控制

针对含未知参数的永磁同步电机(PMSM)系统,研究其参数稳定性和自适应控制问题.首先,分析了参数变化对PMSM系统平衡点的影响.然后,通过设计自适应控制器使得闭环系统具有耗散Hamiltonian结构,使闭环系统的能量分布随着未知参数的漂移而自动的改变,且能量函数总在未知参数对应的平衡点处取得极小值,从而实现自适应参数...