高能X射线源焦斑尺寸的时间分辨诊断

将门控分幅相机与快闪烁晶体结合,构成时间分辨X射线诊断系统,对神龙一号直线感应加速器产生的高能脉冲X射线源焦斑进行了测量,在时间间隔为10 ns的情况下,获得了焦斑尺寸随时间的变化曲线。在此基础上,设计了单像素尺寸为0.78 mm×0.78 mm的LYSO闪烁晶体阵列,并进行了X射线照射晶体阵列发光的初步实验,结果表明该阵列可用于高能X射线源焦斑的时间分辨诊断,并能显著提高成像的空间分辨力。     

低温真空冷冻干燥室内温度特性的研究

真空冷冻干燥设备广泛应用于药品、食品等的干燥领域,该干燥方式能避免药品、微生物等产生变性或失去生物活力,但是能耗较大,且干燥室内的温度在真空条件下,比较难于控制。文中从三个方面对其温度特性进行了实验研究:真空度对温度特性的影响;板面温度对于冻干瓶内温度控制的影响;保护气对于冻干瓶内温度控制的影响。     

The laser-induced fluorescence spectrum of CoS between 15 200 and 19 000 cm-1

测量了在15200～19000 cm^-1的超声射流冷却的CoS自由基的激光诱导荧光激发谱. 观测到[15.58]⁴Δ_7/2～X⁴Δ_7/2, [16.02]⁴Δ_7/2～X⁴Δ_7/2, [16.50]⁴Δ_7/2～X⁴Δ_7/2, [17.80]⁴П_5/2～X⁴Δ_7/2和[18.00]⁴Δ_7/2～X⁴Δ_7/2五个电子跃迁序列. 此外,还测量到了大多数观察的振动带的寿命. 并讨论了这些新的电子态的电子构型.     

基于PCA的变压器故障红外监测应用研究

变压器作为电力系统中非常重要的输变电设备,其运行状况直接影响到整个系统运行的安全水平。根据红外光谱仪所测得信息,通过傅里叶变换可得到各故障特征气体红外吸收信息;依据Lambert-Beer定律并结合所测信息,采用主成分分析法就可以对各故障特征气体进行定性与定量分析,判别当前变压器的运行状况。对于故障运行的电力变压器,及时发现并解除存在的故障或故障隐患对整个系统的安全运行具有重要意义。     

Volume perception from motion

Volume perception, that is, perception of a partially enclosed space filled with a medium, can be assessed not only from binocular viewing but also from motion. We studied the volume perception of a cylindrical object in motion. The motion (rotation, translation, or rolling) of the cylindrical object was simulated with and without appearing and disappearing parts (ADPs). We found that volume perception could be assessed easily with ADPs but was difficult without ADPs. These experimental results indicate that ADPs are an essential factor for volume perception from motion, which is correspond to binocularly unpaired regions for volume perception in binocular viewing.     

Effects of annealing on luminescence efficiency of large-size YAG:Ce crystal grown by temperature gradient techniques

<正>YAG:Ce crystal with a diameter of 110 mm is successfully grown by the temperature gradient technique (TGT).The effects of annealing on the luminescence efficiency of YAG:Ce crystal are investigated,and the optimal annealing temperature and atmosphere are obtained.The mechanism of variation behavior of the luminescence efficiency of YAG:Ce under different annealing conditions is discussed and some details on the luminescence associated with color centers are analyzed.     

液滴冲击液膜过程实验研究

实验显示了液滴撞击物体表面液膜后产生水花、发生飞溅,特别是产生“钟形”水花等的流动现象.根据实验结果,探讨了液滴冲击速度、液体黏性、表面张力、液滴直径和液膜厚度等对液滴冲击后产生的流动现象,以及液膜形状演化的影响,分析了观测到的鲜有文献报道的液滴撞击液膜后产生“钟形”水花的现象.     

SrF2-CaF2混合物薄膜的物理及红外光学特性研究

采用热蒸发和电子束蒸发两种沉积方式分别沉积了相同厚度的SrF₂-CaF₂ (比例为1∶1) 的混合物薄膜,对其物理和光学特性进行了研究,并定量地给出了其在红外波段的光学常数,填补了这一数据的空白. 同时提供了一种获得不同低折射率薄膜的方法.文中还以该比例的混合物作为低折射率材料,研制出具有很好的光学性能的长波红外宽光谱增透膜.     

Surface dynamics studied by time-dependent tunneling current

Scanning tunneling microscopy (STM) is not only an excellent tool for the study of static geometric structures and electronic structures of surfaces due to its high spatial and energy resolution, but also a powerful tool for the study of surface dynamic behaviors, including surface diffusion, molecular rotation, and surface chemical reactions. Because of the limitation of the scanning speed, the video-STM technique cannot study the fast dynamic processes. Alternatively, a time-dependent tunneling current, I-t curve, method is employed in the research of fast dynamic processes. Usually, this method can detect about 1000 times faster dynamic processes than the traditional video-STM method. When placing the STM tip over a certain interesting position on the sample surface, the changing of tunneling current induced by the surface dynamic phenomena can be recorded as a function of time. In this article, we review the applications of the time-dependent tunneling current method to the studies of surface dynamic phenomena in recent years, especially on surface diffusion, molecular rotation, molecular switching, and chemical reaction.     

多量子位Heisenberg XX链中的杂质纠缠

通过分析系统的杂质位与其余部分间的纠缠N_1-A以及单个正常位与其余部分间的纠缠N_L-A研究了匀强磁场作用下含杂质Heisenberg XX链的纠缠特性.研究表明三量子位时纠缠存在的临界温度依赖于杂质参数J₁和匀强磁场B.研究发现,当量子位L为奇数时,纠缠N_1-A随量子位的增加而增大,而L为偶数时则相反,并且量子位L为偶数时的纠缠大于量子位L为奇数时的纠缠;对N_L-A, 量子位L为奇数时,纠缠随杂质参数J₁的变化与L=3类似,而L为偶数时纠缠随杂质参数|J₁|的增加而增加.