可吸入颗粒物在驻波声场中运动的可视化研究

采用可视化实验的方法,拍摄可吸入颗粒在驻波声场中的运动轨迹.根据拍摄结果,分别采用标尺测量、颗粒重力沉降特性和声波夹带特性计算颗粒粒径.实验表明,可吸入颗粒在声团聚室中受到声波夹带、重力作用和粘性力的影响.计算结果说明,利用声波夹带特性可以准确计算颗粒粒径,颗粒的漂移现象是由漂移力引起.     

氢化物原子荧光光谱法测定土壤中砷的不确定度评定

本文介绍了氢化物原子荧光光谱法测定土壤中砷的不确定度评定方法,分析和识别测定过程中不确定度的来源,归纳提出了影响土壤中砷含量测定不确定度的主要因素.通过不确定度评定证明不确定度分量的主要来源为样品制备过程所带来的不确定度,其中,消解样品所引入的不确定度贡献最大;根据最小二乘法拟合校准曲线计算的标准不确定度次之,而标准储备液校准稀释以及重复性实验所带来的不确定度相对于前两者小很多.     

基于视差自相关特征水深反演

提出了一种基于视差自相关特征模拟水深的新方法。这种方法利用不同摄站获取的同一物体的两幅图像,在水的折射影响下,造成的视觉上的偏差计算水深,可以得到相关区域三维显示中各点的水深数值。以数码相机所拍摄两张照片为例,实现相关区域水深三维显示。结果表明此算法具有一定的可行性,可以进行更深层次的研究,并应用于浅海、河流等地的资源探测开发。     

A Bidirectional, Diode-Pumped, Passively Mode-Locked Nd：YVO4 Ring Laser with a Low-Temperature-Grown Semiconductor Saturable Absorber Mirror

We report the operation of a bidirectional picosecond pulsed ring Nd：YVO4 laser based on a low-temperaturegrown semiconductor saturable absorber mirror. Except for the laser crystal, the six-mirror ring laser cavity has no intra-cavity elements such as focusing lens or mirror. The bidirectional mode locked pluses are obtained at the repetition rate of 117.5 MHz, pulse duration of 81 ps, power of 2 × 200 mW.     

Formation of Pd-Ni Based Bulk Metallic Glasses

Bulk metallic glasses are prepared in Pd4o.sNi4o.sSixP19-x （x = 0-14 at.%） alloys by a combination of flux treatment and water quenching technique. It is found that the thermal stability of the Pd4o.sNi4o.sSixP19=x glassy alloys depends on the addition of Si content. Among the Pd4o.sNi4o.sSixP19=x glassy alloys studied, the Pd4o.sNi4o.sSisPls bulk metallic glass exhibits the largest supercooled liquid region （△T = 119 K） and the highest activation energy of crystallization （283.3k J/tool）, showing enhanced glass formation ability and extraordinary glassy thermal stability.     

An All-Solid-State Tunable Dual-Wavelength Ti：Sapphire Laser with Quasi-Continuous-Wave Outputs

A high power dual-wavelength Ti：sapphire laser system with wide turning range and high efficiency is described, which consists of two prism-dispersed resonators pumped by an a11-solid-state frequency-doubled Nd：YAG laser. Tunable dual-wavelength outputs, with one wavelength range from 750nm to 795nm and the other from 80Ohm to 850nm, have been demonstrated. With a pump power of 23 W at 532nm, a repetition rate of 6.5kHz and a pulse width of 67.6ns, the maximum dual-wavelength output power of 5.6 W at 785.3nm and 812.1 run, with a pulse width of 17.2ns and a line width of 2nm, has been achieved, leading to an optical-to-optical conversion efficiency of 24.4%.     

A 2.048μm Tm,Ho:GdVO4 Laser Pumped Doubly Resonant Optical Parametric Oscillator Based on Periodically Poled Lithium LiNbO3

A multi-grating periodically poled LiNb03 （PPLN） doubly resonant optical parametric oscillator （DROPO） pumped by a 2-ttm laser is demonstrated experimentally. Employing acousto-optically Q-switched Tm,Ho：GdV04 laser with pump pulse of 25ns and repetition rate of lOkHz as pump sources firstly, the noncritically quasi- phase-matched （QPM） tunable mid-IR output in 3.87-4.43 μm is produced. Wavelength tuning is achieved with crystal temperature tuning from 50-180^o C. When the incident average pump power is 3 W at 2.048μm, the total OPO output power of 195mW at wavelength 3.88μm is obtained, corresponding to optical-to-optical conversion efficiency up to 6.5%.     

格林公式的教学探究

首先通过一个热点问题和两个计算题引出学习格林公式的目的和必要性,迅速抓住学生的兴趣点,从第二型曲线积分入手,通过逐步分析操作给出前提条件,并最终得到公式,打破了书上的传统推导模式.     

次近邻电子跳跃对孤子的电子束缚态和孤子附近局域模的影响

从SSH模型出发,考虑电子次近邻跳跃的影响,研究了聚乙炔中孤子的电子束缚态和孤子附近的局域振动模。结果发现:1.电子能谱中的电子-空穴对称性消失;2.孤子的电子束缚态的数目和位置发生了变化,且与孤子的类型有关;3.孤子附近出现了一个新的局域振动模G₆;4.次近邻电子跳跃改变了局域模的频率,增强了局域模的局域性。 关键词：     

Pb(Zr,Sn,Ti)O3反铁电陶瓷的低温相变扩散与极化弛豫

用弱场介电温谱、热释电流谱、强场电滞回线和变温X射线衍射谱研究了微量La掺杂Pb(Zr ,Sn ,Ti)O3(PZST)反铁电 (AFEt)陶瓷在 - 10 0— 180℃温区内的结构与电学特性 .弱场介电温谱显示 ,AFEt陶瓷在低温段(- 10 0— 5 0℃ )呈现介电频率弥散 (0 1— 10 0kHz)和扩散型相变的特征 ,而变温X射线衍射谱却表明材料在这一温区内保持四方相结构 ;低温下经强场作用后 ,AFEt被诱导为亚稳三方铁电态 ,介电频率弥散消失 .基于多元复杂化合物的组分起伏理论 ,讨论了PZSTAFEt陶瓷的相变扩散与极化弛豫新现象 .