焊缝超声相控阵检测数据深度学习降噪方法

超声相控阵检测技术在焊缝检测中具有广泛的应用.超声相控阵检测技术检测信号中常混入噪声导致检测成像时难以分辨真实的缺陷特征.这些噪声主要为无关的反射信号和局部相关的结构噪声,传统的超声图像降噪方法难以有效滤除这些噪声,且存在计算效率低、参数优化复杂等问题.该文提出了一种基于深度学习的焊缝超声相控阵检测技术检测S扫图像的降...     

泡沫铜基底原位生长的铜基导电金属有机框架作为双功能电催化剂

以泡沫铜为基底生长氢氧化铜纳米线,通过原位转化合成二维导电金属有机框架(MOF)材料Cu_3HITP_2(HITP=2,3,6,7,10,11-六氨基三亚苯)作为双功能催化剂,可直接用作析氧及氧还原反应的工作电极,而无需使用额外的基底或粘合剂,且无需后续热处理。研究发现以氢氧化铜纳米线为模板的Cu_3HITP_2表现出了更大的电化学比表面积,这种新型的电极可在碱性溶液(0.1和1.0 mol·L~(-1) KOH)中可以稳定运行,析氧反应中在电流密度达到10 mA·cm~(-2)时的过电位仅为1.53 V,超越了商业二氧化钌的催化性能。此外,该催化剂在氧还原反应中的半波电位达到0.75 V,优于大多数MOF材料。     

Ni-Cu双金属催化剂上乙醇水蒸气重整制氢研究—制备方法对催化性能的影响

我们采用分步浸渍法和共浸渍法制备了一系列的Ni-Cu/mSiO₂催化剂.运用XRD、N₂吸附-脱附、H₂-TPR、SEM、TG-DTG等表征手段对催化剂反应前后的物理化学性质进行分析,催化剂对乙醇水蒸气重整（ESR）反应的催化性能通过常压固定床反应器进行评价.结果表明：催化剂的催化性能与载体上的活性组分分散有关,而活性金属的分散性与制备方法有关.共浸渍法制备的催化剂Ni₁₄-Cu/mSiO₂活性组分分散度较高,抗积碳能力与稳定性更好.在质量空速为2.7 h^-1,水醇摩尔比为9,反应温度为550℃的条件下进行稳定性测试,催化剂Ni₁₄-Cu/mSiO₂测试25 h没有出现失活现象,乙醇转化率保持在100%,H₂的选择性保持在70%以上,反应后的积碳含量仅为5.52%.     

Electronic Curves Crossing in Methyl Iodide by Spin--Orbit Ab Initio Calculation

An ab initio investigation of electronic curve crossing in a methyl iodide molecule is carried out using spin-orbit multiconfigurational quasidegenerate perturbation theory. The one-dimensional rigid potential curves and optimized effective curves of low-lying states, including spin-orbit coupling and relativistic effects, are calculated. The spin-orbit electronic curve crossing between ^3Qo＋ and ^1Q1, and the shadow minimum in potential energy curve of ^3Qo＋ at large internuclear distance are found in both sets of the curves according to the present calcu- lations. The crossing position is in the range of Re-1 = 0.2370 3：0.0001 nm. Comparisons with other reports are presented.     

Cs^＋-K^＋ Exchange in Z-Cut KTiOPO4 Crystal Covered with Chromium Masking Layer

Cs^＋-K^＋ ion exchanges are performed on z-cut KTiOPO4 crystals with chromium coating covered. The temperature of ion exchange is 430℃, and the time range from 15min to 30min. The dark mode spectra of the samples are measured by the prism coupling method. The channel structures on the samples are observed by a microscope and the near field pattern of the channel waveguides are measured by the end-fire coupling method. The refractive index of the samples increases and the increments at surface are modulated due to the existence of Cr film. In the region covered by Cr film, the refractive index of the samples at the surface increases dramatically in a shallow layer. The results of energy dispersive x-ray spectra indicate that in the region covered with Cr film, Cr ions participate in the ion exchange process, and enhance the refractive index. The results may provide a possibility that achieves index enhancement and Cr doping synchronically.     

Difference of Oxide Hetero-structure Junctions with Semiconductor Electronic Devices

Charge carrier injection is performed in Pr0.7Ca0.3MnO3 （PCMO） hetero-structure junctions, exhibiting the stability without electric fields and dramatic changes in both resistance and interface barriers, which are entirely different from behaviour of semiconductor devices. The disappearance and reversion of interface barriers suggest that the adjustable resistance switching of such hetero-strueture oxide devices should associate with motion of charge carriers across interfaces. The results suggest that injected carriers should be still staying in devices and result in changes of properties, which lead to a carrier self-trapping and releasing picture in a strongly correlated electronic framework. Observations in PCMO and oxygen deficient CeO2-δ devices show that oxides as functional materials could be used in mieroeleetronics with some novel properties, in which the interface is very important.     

Relationship of Polaron Exchange with Ferromagnetic and Insulator--Metal Transitions in Doped Manganites

We report the experiment results and data analyses based on a polaron exchange model for La0.7Ca0.3MnO3 and Pr0.7（Sr1-xCax）0.3MnO3 epitaxial thin films. In the polaron exchange model with an energy balance condition, critical temperature of Tc for stable ferromagnetic （FM） ordering should depend on △E as kBTc = E0 exp（-△E/kBTc）, where A E denotes the potential barrier for the exchange polarons to overcome. Using the small polaron hopping model, the resistivity peak temperature Tp is a function of the hopping energy Ehop. The dependence of Tp on Ehop is similar to the dependence of Tc on AE, which reveals that the polaron exchange relates to FM and insulator-metal transitions. The result indicates that the polaron exchange model is a simple way for describing the FM ordering, and is very helpful for understanding of complex doped manganites.     

薄膜生长速率对有机光伏器件性能的影响

采用真空热蒸发镀膜的方法制备了酞菁铜(CuPc)和富勒烯(C60)构成的平面异质结结构光伏器件,并初步研究了CuPc薄膜生长速率对器件光伏性能的影响,我们发现以较大薄膜生长速率制备的器件表现出较大的短路电流和能量转换效率。X射线衍射和原子力显微镜观察的结果表明生长速率较大的CuPc薄膜结晶相含量较少,薄膜结构较均匀、致密、平整,这可能使得CuPc薄膜激子扩散和载流子迁移特性得到提高,也可能改善其与C60受主薄膜和ITO阳极的接触,并有利于载流子的分离和收集,从而表现出较好的光伏特性。     

气溶胶前向散射大气能见度测量系统传递系数的标定及校准方法

分析了气溶胶的前向角散射特性,利用标准的大气透射仪标定前向散射大气能见度测量系统的传递系数。当系统结构发生变化时,传递系数也随之改变,为保证系统测量的准确性和简化系统传递系数的标定过程,提出了一种利用标准漫透射板校准系统传递系数的方法。该方法使用了两块具有相同透射系数的漫透射板,使气溶胶粒子团在前向半球上产生漫散射,此时探测器的测量值即为包含了仪器常数的定值。当系统结构改变时,这个测量值相对于原测量值的变化率作为比例系数代入系统传递系数的计算,实现校准。     

二次生长法NaA沸石分子筛膜的合成与表征——推荐一个研究型综合实验

介绍一个研究型综合实验——二次生长法NaA沸石分子筛膜的合成与表征。实验预先利用热浸渍法在α-Al_2O_3多孔载体管外表面引入NaA沸石分子筛晶种,再通过二次生长法合成NaA沸石分子筛膜。用扫描电子显微镜和X射线衍射仪表征载体管和NaA沸石分子筛及膜的形貌和结构,并利用渗透蒸发乙醇脱水膜分离装置测试膜的分离性能。通过本实验使学生了解膜分离技术这一科学前沿领域,激发学生对科学研究的兴趣,培养学生的科研探究能力。本实验涵盖合成、表征及性能测试,知识要点多、学科覆盖面广,有利于提升学生的实践操作能力、创新意识和综合运用知识的能力。