退火温度对铜纳米颗粒复合材料的三阶非线性光学性质的影响

采用离子注入法制备铜纳米颗粒复合材料,在波长为790 nm的入射激光作用下,运用Z-扫描技术测量了铜纳米颗粒复合材料的非线性光学折射率和非线性光学吸收系数,分析了退火温度对铜纳米颗粒复合材料光学性质的影响。结果表明,随着退火温度的升高,铜纳米颗粒复合材料的颗粒尺寸明显增大,且光学非线性折射率上升。通过改变非晶二氧化硅中铜纳米颗粒复合材料的形状,得到不同的三阶非线性光学系数的特定值。     

PEGDA/NIPAM共聚物水凝胶的溶胀性能及体积相变研究

以IRGACURE2959为光引发剂,聚乙二醇双丙烯酸酯(PEGAD)和N-异丙基丙烯酰胺(NIPAM)为单体,通过紫外光引发光聚合合成了PEGDA/NIPAM共聚物水凝胶.研究了不同单体质量比凝胶材料在不同温度和pH值下的溶胀性能,测试凝胶在不同温度水中的体积相变.研究结果表明,水凝胶的平衡溶胀率随着NIPAM质量浓度增大而增大,随着环境温度的升高而减小,随着环境pH的增大而增大;NIPAM引入后,随着温度升高达到凝胶低临界溶解温度(LCST)时,凝胶平衡溶胀率及溶胀比减小明显加快,发生体积相变;随着NIPAM质量浓度的增大,凝胶溶胀饱和率减小,凝胶具备良好的延缓溶胀性能.     

改进复杂网络模型的形状特征提取

目的 传统的基于欧氏距离的复杂网络表示方法容易受形状的非刚性变形影响。鉴于此,提出一种基于复杂网络模型与相对一致性距离相结合的形状特征提取方法。方法 首先,提取形状的边界轮廓点作为网络的节点,利用节点间的相对一致性距离作为边的权值构建初始的复杂网络模型;然后,利用阈值演化方法对初始网络模型进行动态演化,得到一系列子网络;最后,提取不同演化阶段下子网络的拓扑特征,实现对形状特征的提取。结果 分类和检索实验结果表明,相比于传统的复杂网络描述方法,本文方法对形状图像具有更强的描述和识别能力。结论 相比于传统的距离度量,相对一致性距离对形状的非刚性变形具有更强的稳定性。     

A Spatial Cognitive Model that Integrates the Effects of Endogenous and Exogenous Information on the Hippocampus and Striatum

Machine Intelligence Research - Reproducing the spatial cognition of animals using computational models that make agents navigate autonomously has attracted much attention. Many biologically...     

Growth and characterization of indium doped zinc oxide films sputtered from powder targets

Indium doped Zn O films were grown on quartz glass substrates by radio frequency magnetron sputtering from powder targets. Indium content in the targets varied from 1at% to 9at%. In doping on the structure, optical and electrical properties of Zn O thin films were studied. X-ray diffraction shows that all the films are hexagonal wurtzite with c-axis perpendicular to the substrates. There is a positive strain in the films and it increases with indium content. All the films show a high transmittance of 86% in the visible light region. Undoped Zn O thin film exhibits a high transmittance in the near infrared region. The transmittance of indium doped Zn O thin films decreases sharply in the near infrared region, and a cut-off wavelength can be found. The lowest resistivity of 4.3×10~(-4) Ω·cm and the highest carrier concentration of 1.86×10~(21) cm~(-3) can be obtained from Zn O thin films with an indium content of 5at% in the target.     

基于Backstepping的欠驱动船舶神经滑模航迹控制

在外界干扰和参数不确定的情况下,设计一种基于Backstepping的自适应神经滑模控制器对欠驱动船舶神经滑模航迹进行控制。采用趋近律的滑模控制,抑制常规滑模的固定切换增益系数带来的抖振现象;利用神经网络辨识对象,减少趋近律滑模控制对对象模型参数的依赖。以某实习船为例进行仿真,结果表明:在标称参数下,所设计的控制器能够有效跟踪设定的航迹并抑制常规滑模控制器的抖振现象;在外部环境扰动以及参数摄动的情况下,仍然能够实现较好的控制,表现出强鲁棒性。     

基于CS5463的双流制机车电度表设计

设计一种基于CS5463的双流制机车电度表。介绍了双流制电度表的技术性能、总体结构以及程序设计方法,通过对电能计量模块、中央处理模块、双路供电设备以及GPRS与RS485通信模块进行设计,实现机车交流与直流的显示、与TAX2机车监控装置通信以及远程无线抄表功能。采用型式试验、例行试验对新研制的双流制机车电度表进行测试,试验结果表明,该电度表具有制造成本低、数据处理能力强、安全保障度高、测量精度高、抗干扰能力强等优点。     

Mechanism for clogging of microchannels by small particles with liquid cohesion

We numerically investigate the effect of liquid cohesion on the clogging of microchannels induced by small wet particles. The computer simulation is performed by the discrete element method (DEM) with cohesive contact models in presence of pendular liquid bridges, which is embedded into the computational fluid dynamics (CFD). We find that liquid cohesion significantly promotes particle deposition and agglomerate growth. A clogging phase diagram, in the form of Weber number and Stokes number, is constructed to quantify the clogging-nonclogging transition. The competition between particle–particle and particle–fluid interactions is quantitatively discussed in terms of particle velocity and slip velocity. Strong cohesion can address a greater slip velocity or drag between particles and fluid, which depresses the resuspension of deposited particles and results in clogging. Finally, we compare our results with clogging induced by van der Waals adhesion of small dry particles and find that the competence of liquid cohesion is more prominent.     

Prestructured MXene fillers with uniform channels to enhance CO2 selective permeation in mixed matrix membranes

The packing pattern of two-dimensional (2D) sheet-like fillers in membranes is relatively random, leading to the unfavorable permeability from tortuous diffusion pathway. A new strategy that using prestructured materials with uniform channels as fillers was proposed. In this work, Ti₃AlC₂ is etched to prepare multilayered MXene (m-MXene), the channels aggregate as a whole unit, ensure the impossibility of ineffective packing compared with traditional individual sheets, largely facilitating the selective permeation. Then, the m-MXene/Poly (amide-6-b-ethylene oxide) (Pebax) MMMs are synthesized. SEM images demonstrate the accordion shaped structure of filler, which is the multi-channels laminates. Furthermore, the results of gas permeation test exhibit enhanced performance of m-MXene/Pebax MMMs. MMM with 0.5 wt.% m-MXene behaved best, CO₂ permeability of 86.22 Barrer as well as CO₂/N₂ selectivity of 104.85, transcending the Robeson upper bound (2008). Having distinct enhancement for CO₂ separation, the m-MXene/Pebax MMMs in this work offer prospective practical applications.