红外热成像技术在高分子科学研究中的应用

红外热成像技术是一种非接触、非破坏性的测试材料表面温度的方法,具有既能生成优质图像,又能够精确测温的特点。该技术已被广泛用于全球工业行业的过程状态检测,如电力、建筑、医疗、军事等领域,但在高分子科学的研究领域应用还较少。本文介绍了红外热成像技术的基本原理,综述了红外热成像技术在高分子科学研究中的应用状况,包括研究材料在拉伸、冲击、疲劳过程的热效应特征,研究纤维成形过程的纺丝动力学及高分子聚合过程的反应动力学。     

使用多孔蜗舌的贯流风机

将贯流风机的蜗舌替代为多孔板与容腔组合的结构,定性地研究其控制气动噪声的可行性。通过对气动特性和辐射声信号的实验测量,结合内部流场的非稳态雷诺平均数值模拟,分析了这种蜗舌改造对贯流风机的整体特性和内部流动特征的影响,结果表明多孔蜗舌对贯流风机的压力-流量曲线作用并不明显,但对风机的噪声有着重要的影响,改变蜗舌迎风面的穿孔率可以有效地控制贯流风机的噪声。     

聚多联苯2,6-二甲酰对苯二胺的力学性能模拟

设计了一类线型聚多联苯2,6-二甲酰对苯二胺聚合物, 并对聚合物分子模型进行了计算机模拟, 通过分子力学和力学性质模块的计算得到了聚多联苯2,6-二甲酰对苯二胺的一些力学参数. 模拟结果表明, 聚多联苯2,6-二甲酰对苯二胺类型芳酰胺聚合物通过自组装可以呈现类倒插蜂窝结构排列, 除聚二联苯2,6-二甲酰对苯二胺和聚三联苯2,6-二甲酰对苯二胺以外, 该系列聚合物在xy平面内均具有负泊松比.     

272 W quasi-single-mode picosecond pulse laser of ytterbium-doped large-mode-area photonic crystal fiber

A large-mode-area(LMA) ytterbium-doped photonic crystal fiber(PCF) with core NA of 0.034 and core diameter of 50 μm was made by the stack-and-draw technique. The core is formed by Yb~(3+)/Al~(3+)/F-/P~(5+) co-doped silica glass containing 0.09 mol% Yb_2O_3 with an absorption coefficient at 976 nm up to 3.2 d B/m. The core glass with homogeneous distribution of Yb~(3+) ions and refractive index difference of 4 × 10~(-4) compared with pure silica was prepared by the sol-gel method and heat homogenization at 2000°C. Laser power amplification of this LMA PCF was studied using a seed source of 21 ps pulse duration and 48.7 MHz repetition rate at 1030 nm wavelength. With pump power of 520 W, a maximum 272 W(266 k W peak power) quasi-single-mode laser output with M~2 of 2.2 was achieved in a 4.7 m fiber length bent at a diameter of 47 cm with slope efficiency of 52%, and no obvious mode instability, stimulated Raman scattering, or thermal damage on the end facet of the fiber were observed.     

2-μm emission performance of Tm~(3+)-Ho~(3+) co-doped tellurite glasses

The emission properties of 2-μm region fluorescence of Tm~(3+)-Ho~(3+) co-doped tellurite glasses are investigated. Introducing F~- ions to the composition of tellurite glasses plays a positive effect on the 2-μm emission.A maximum intensity of 2-μm emission is achieved when 1.5-mol%Tm_2O_3 and l-mol% Ho_2_O3 concentration are doped in the glasses.The emission cross section and gain coefficient of the ~5I_8→~5I_7 transition of Ho~(3+) are calculated.The emission cross section has a maximum of 1.29×10~(-2...     

CaLa4Si3O13:Eu3+红色荧光粉制备条件优化及助熔剂作用研究

采用高温固相法制备了CaLa4Si3O13:Eu3+红色荧光粉,研究了助熔剂总量、Li和B物质的量之比、烧成温度对发光性能的影响。以Eu3+的5 D0-7 F2发射强度为指标得出的最佳制备条件为:硼锂双助熔剂B和Li物质的量之比为1:1,总量为0.4 mol.mol-1,950℃预烧150 min,1150℃,240 min烧成。硼组分进入晶格置换硅,使晶胞参数a,c和晶胞体积V均逐渐减小,提高电/磁偶极跃迁强度比和总发光强度。助熔剂总量达到0.24 mol.mol-1后,进入基质的硼趋于饱和。硼组分起到助熔剂和基质组分置换双重作用。     

Neural Wave Representation in Early Vision

The neural wave representation which describes spatiotemporal information in early vision is proposed in terms of extended Gabor functions in this paper. Its reasonability, completeness and uncertainty in spatiotemporal domains and their frequency domains were investigated. The ranges of these parameters in this representation were estimated on electrophysiological and psychophysical data. We derived the partial differential equations which the neural wave satisfied. The general significance of 3D neural wave representation has been explored.     

局域神经线路的联结系综模型

本文首次提出了局域神经线路的一种联结系综模型。本模型把神经元之间的相互作用分成两个层次,即神经元之间的突触联结和神经元集团之间的宏联结。宏联结的有效性是由各有关突触联结的有效性定量决定的,而且它具有渐近稳定性质。这个模型成功地描述了局域神经线路形态上的变异性和功能上的恒定性这一神经生物学中普遍存在的事实。联结系综概念的内涵看来是相当深刻的,它丰富了当前神经网络动力学研究的内容。     

Watt-level Yb-doped silica glass fiber laser with a core made by sol-gel method

A Yb-doped silica glass fiber laser with a core made by sol-gel method is reported. The maximum power of 1.14 W is obtained with a pump power of 5.46 W at a wavelength of 976 nm. The slope efficiency is 34%. The refractive index fluctuation across the core is below 5×10^-4 at a doping level of Yb 0.15 mol%, A203 4.0 mol%, and P2O5 2.0 mol%. High background attenuation of 6 dB/m at 1 053 nm limites the slope efficiency and maximum output power.     

高效率全国产化10kW光纤激光器

基于自主研发的大模场增益光纤和无源器件,采用双端抽运技术,搭建了一台全国产化10 kW光纤激光器,实现了非线性效应抑制。该激光器的功率放大器的输出功率达到10.14 kW,中心波长为1070.36 nm,3 dB光谱带宽为5.32 nm。其主放大级最大光-光转换效率为87.8%,斜率效率为89.2%,成为目前国内报道的效率最高的10 kW级光纤激光器。