激光诱导击穿光谱法定量分析水泥中的铜元素

为定量分析水泥中的铜(Cu)元素,根据激光诱导击穿光谱分析方法(Ll BS)的特点,建立了激光诱导击穿光谱分析系统。采用标准加入法为定标方法,制备了5个不同含铜量的水泥样品。根据LIBS谱图,以213.598 nm和219.958 nm作为分析线。应用Savitzky-Golary卷积平滑方法对光谱数据进行了预处理,比较了Guass、Lorentz和Voigt拟合方法对光谱曲线的拟合效果。对测量结果采用一元线性拟合建立了相应的定标曲线,213.598 nm和219.958 nm定标曲线的校正决定系数分别为0.994 8和0.986 4,平均相对误差分别为3.20%和5.78%。实验结果表明:213.598 nm作为分析线的准确度优于219.958 nm分析线,该方法能够满足水泥中Cu元素定量分析的要求。     

指向学生辩证思维能力培养的课堂教学——以“探究燃烧与灭火”为例

以培养学生辩证思维能力为理念,围绕“谈谈你所了解的燃烧与灭火”“对探究可燃物燃烧条件实验装置的反思”“对燃烧条件及现象的反思”等问题,设计并成功实施与此相关的系列实验,在纠正学生既有认知偏差的同时,发展学生的辩证思维能力。     

Quantum Fluids of Self-Assembled Chains of Polar Molecules at Finite Temperature

The finite temperature properties of self-assembled dipole chains of polar molecules in strongly confined pancake traps are investigated. The single-chain vibrations at finite temperature, which become important for long chains in a strongly interacting regime, are found to lower the transition temperature and to shift the chain distribution by less than 10%. We also propose experimental parameters to observe such quantum phase transition.     

Study of a millimeter-wave squint indirect holographic algorithm suitable for imaging with large field-of-view

In this paper a millimeter-wave （MMW） squint indirect holographic method is presented, which is suitable for imaging with a large field-of-view. The proposed system employs the squint operation mode to remove the background and twin- image interferences, which achieves a similar effect to off-axis holography but leaves out the large-aperture quasi-optical component. The translational scanning manner enables a large field of view and ensures the image uniformity, which is difficult to realize in off-axis holography. In addition, a corresponding imaging algorithm for the presented scheme is developed to reconstruct the image from the recorded hologram. Some imaging results on typical objects, obtained with electromagnetic simulation, demonstrate good performance of the imaging scheme and validate the effectiveness of the image reconstruction algorithm.     

Tomographic analysis of the central magnetohydrodynamic oscillations on the HT-7 tokamak

Multi-channel soft x-ray (SX) detectors are applied to generate images of magnetohydrodynamic (MHD) oscillation on the HT-7 tokamak, and the data from SX cameras are analysed by using the Fourier--Bessel harmonic reconstruction method and the singular value decomposition. The image reconstruction of SX emissivity is obtained on the assumption of plasma rigid rotation. One of the important phenomena in the HT-7 discharge is the transition from the sawtooth oscillations to the MHD oscillations when the plasma density grows higher. The MHD structure observed in the SX tomography is featured as follows: the magnetic surface of MHD structure is made up of the crescent-shaped ``hot core' and the circular ``cold bubble'. The structure of the magnetic surface is relatively stable. It rotates in the direction of the electron diamagnetic drift at a frequency being the oscillation frequency of the MHD oscillations.     

水-表面活性剂比对微乳液法制备磁性Ni-Fe复合纳米微粒的影响

Ni-Fe复合物纳米粒;磁学参数;水-表面活性剂比对微乳液法制备磁性Ni-Fe复合纳米微粒的影响     

用偶幂级数处理Abel变换问题

本文提出了用偶幂级数代替对称分布函数,使其线积分成为递推可积,从而简化了Abel逆变换。引进权函数使本方法简单地过渡到非对称问题。对一组假想相移信号进行变换,获得了可靠的密度分布结果,并对影响变换精度的各种因素作了讨论。     

一类函数的分部积分规律(一)

对于正整数指数幂与指数函数、正弦、余弦、双曲正弦、双曲余弦的乘积的不定积分,运用分部积分法,进行讨论,根据它们的运算特征找出规律,得出可以直接求得结论的普遍公式.     

新型铬锰复合氧化物低温选择性催化氨还原NOx

采用柠檬酸法合成了一系列铬锰复合氧化物催化剂,利用X射线衍射及X射线光电子能谱研究了催化剂活性相态,并考察了铬锰摩尔比对反应活性的影响. 结果表明,该体系在有氧条件下氨低温选择性催化还原氮氧化物反应中显示出优异的活性,其中Cr(0.4)-MnOx催化剂具有最佳低温催化活性,在空速 30 000 h-1和120 ℃条件下, NOx转化率达98.5%, N2选择性达100%. 在MnOx中添加Cr后形成了CrMn1.5O4晶相, 该相态在低温选择性催化还原NOx过程中起重要作用.     

KOH活化对焦炭孔隙结构以及导电特性影响

以木质素为原料,采用化学活化法(KOH活化剂)进行活化处理,分别探讨了不同活化温度、活化时间、KOH/木质素质量比R值对焦炭孔隙结构以及导电特性的影响规律。通过氮吸附(BET)、扫描电镜(SEM)和电阻率测定仪对焦炭性能进行表征。结果表明,KOH活化有效改善了焦炭的孔隙结构,通过增加焦炭微孔量提高了焦炭比表面积。实验得出的最优活化工况为:活化温度800℃,活化时间1 h,质量比R=3,此时焦炭达到最大比表面积。KOH活化后,焦炭电阻率最低可降至0.226Ω·cm。