Nd:LMA自锁模飞秒激光器腔结构最佳化设计

Nd:LMA晶体相对低的非线性折射率n₂,使得针对Ti:Sapphire自锁模激光器设计的腔,对Nd:LMA介质而言并没有提供足够的自幅度调制(SAM).为了在Nd:LMA激光器上实现自锁模,在腔内引入一个具有大的非线性系数n₂、快的响应时间的SF57介质,这样就使得激光腔的结构比较特殊.在这篇文章里利用ABCD传输矩阵对该激光器的结构从理论上进行了分析和计算,使腔结构达到了最佳化设计.     

提高超声测距分辨力的分析与设计

本文分析了分辨力误差的定量关系，并以此为指导选择和设计超声发射，接收，测时等电路以及数字滤波方法，提亢超声测距的精度和分辩力。     

紫外光辐照清洗带膜MCP的工艺研究

介绍微通道板（MCP）防离子反馈膜在Ⅲ代微光像增强器中的作用，指出微通道板防离子反馈膜的制备工艺对微通道板电性能的影响，提出清洗带膜微通道板的工艺方案，测量清洗前后带膜微通板的电学特性。     

猛炸药RHT-901和钝感炸药IHE-2的爆轰波直角绕射

 采用高速转镜分幅相机和电探针技术研究了猛炸药RHT-901和钝感炸药IHE-2的爆轰波直角绕射图像和不同位置上的爆轰波传播时间。从研究得出，两种炸药都在拐角顶点附近绕射，爆轰波传播时间增长，爆速变小。但是两种炸药绕射爆轰波的状态不一样，钝感炸药IHE-2中爆轰波绕过直角时，在拐角顶点附近约10 mm范围内炸药未完全反应，猛炸药RHT-901中爆轰波绕过直角时未出现类似现象。两者相比，钝感炸药中绕射爆轰波速度变化大，波阵面曲率半径小，而猛炸药的绕射爆轰波速度变化小，波阵面曲率半径大。这说明炸药的爆轰波绕射与炸药的冲击感度、反应区宽度有关。     

Coherent resonant transport through a mesoscopic system with quantum ac microwave field

The time-dependent transport through an ultrasmall quantum dot coupling to two electron reservoirs is investigated. The quantum dot is perturbed by a quantum microwave field (QMF) through gate. The tunneling current formulae are obtained by taking expectation values over coherent state (CS), and SU(1,1) CS. We derive the transport formulae at low temperature by employing the nonequilibrium Green function technique. The currents exhibit coherent behaviors which are strongly associated with the applied QMF. The time-dependent currents appear compound effects of resonant tunneling and time-oscillating evolution. The time-averaged current and differential conductance are calculated, which manifest photon-assisted behaviors. Numerical calculations reveal the similar properties as those in classical microwave field (CMF) perturbed system for the situations concerning CS and squeezed vacuum SU(1,1) CS. But for other squeezed SU(1,1) CS, the tunneling behavior is quite different from the system perturbed by a single CMF through gate. Due to the quantum signal perturbation, the measurable quantities fluctuate fiercely. Received 28 May 1998     

非光滑叶片对叶栅流道内通道涡影响的实验研究

在低速平面叶栅风洞中对光滑叶片叶栅及三种非光滑叶片叶栅进行了实验研究,以研究 与光滑叶片相比,非光滑叶片对叶栅流道内通道涡发展变化的影响。实验结果表明,与光滑叶片相 比,非光滑叶片对叶栅流道内的通道涡有明显的影响,通道涡的位置沿节距方向移向流道中心处, 沿叶高方向不变,通道涡的强度有所减弱。分析了非光滑叶片的影响原因。     

New experimental evidence of the structural modification in single crystal Bi2Sr2CaCu2Oy by X-ray diffraction observation

The variations of the high angle 00 peak-shape by means of X-ray l scans of the 00l fundamental reflections were investigated in detail for a highly oriented Bi₂Sr₂CaCu₂O_y (Bi2212) crystal with sufficiently small intrinsic mosaicity and the same crystal annealed in air at 250, 300, 400, 600, and 750°C for 20 h in consequence. For the first time, we observed a new additional reflection almost overlapped original 00l fundamental reflection at annealing temperature below 400°C by X-ray diffraction measurement, which shows that there coexisted two sets of lattice periodicity in the c-direction of the annealed crystal. The new additional reflection appeared at 250°C and disappeared at 400°C. Its intensity was increased at 300°C. The measurements of the AC susceptibility, c-axis parameter and full width at half maximum (FWHM) of the 00 peaks showed that the new additional reflection was associated with the oxygen diffusion in CuO₂ planes and the changes of strain field. The results provide the new experimental evidence that the structural distortion is more sensitive to the oxygen diffusion in CuO₂ planes than to that in Bi–O layers.     

光谱,波谱法研究铜锌超氧歧化酶与氯化钴（Ⅱ）,组氨酸钴（？…

我们首次发现的铜锌超氧歧化酶（Ｃｕ２Ｚｎ２ＳＯＤ）与氨基酸等发生直接相互作用的现象,是一种前人未研究过的重要的生化新现象。在此新发现的基础上,本文用ＩＣＰ,ＶＩＳ,ＮＭＲ和酶活性测定方法,又从不同角度拓展研究了Ｃｕ２Ｚｎ２ＳＯＤ酶与两类不同化合物,     

HeICl络合物的振动预离解：含时黄金规则波包研究

用含时黄金规则波包法计算了ＨｅＩＣｌｖａｎ ｄｅｒ Ｗａａｌｓ络合物分子的振动了解寿命和离解碎片ＩＣｌ的终转动态分布。并与实验和其他理论计算帮了比较。波包计算所用的总传播时间实际上是解离碎片在振动退激发绝热势能面上的滞留时间。终态相互作用对终转动态分布起着决定性作用。并预言了ＨｅＩＣｌ终转动态分布对振动态的依赖。     

Hyperfine anomaly measurements in francium isotopes and the radial distribution of neutrons

We have performed precision measurements in a magneto-optical trap of the 7P_1/2 hyperfine structure of the isotopes ^209-210Fr. The ratio of these hyperfine constants to the previously measured 7S_1/2 ground state values reveals a significant hyperfine anomaly. This anomaly results from the different radial dependence of the electron density in the two atomic levels. The measurements are sensitive to changes in the radial distribution of the neutron magnetism. This revised version was published online in August 2006 with corrections to the Cover Date.