Estimation of bitumen emulsion dispersion using a light scattering method

Petroleum bitumen in the emulsified state is widely used as a binder in road and civil construction. Along with traditional quality parameters of bitumen emulsions the particle size is considered to be very important characteristic. The particle size of the dispersed phase affects the setting rate and viscosity of bitumen emulsions. The complete data on the particles size distribution can be obtained using such technical methods as light scattering and microscopy. In the study bitumen emulsions with three types of surfactants (cationic, nonionic, zwitterionic) have been prepared and their viscosity and decay index have been determined. The emulsions also have been studied with a microscope, as well as by the method of dynamic light scattering. The dynamics of particle size changes of the bitumen emulsions has been compared with the dynamics of the change in the basic parameters of the emulsions, such as viscosity and decay index, and the correlation between them has been found. Thus, using a modern laser and optical equipment, it is possible to estimate the quality of emulsions and, if necessary, to correct their composition.     

CO2激光用于船体型线放样切割的研究及应用

用激光打标和激光切割方法,实现对船舶建造中船体型线样板箱制作材料的划线与下料的工艺步骤.介绍了由激光器、数控系统、机床构架和冷水机组、除尘与空气压缩机组等辅助设备组成的龙门式三维激光加工联合机床的设计配置与工作原理,并通过对机床的操作试验,选定对木制材料加工的主要工艺参数,并对影响加工质量的现象进行了分析.     

高精度光波导损耗测试系统的设计与实现

以波导耦合理论为依据,采用棱镜耦合法设计了集光电为一体的高精度波导损耗测量系统。测量以激光为光源,采用双光路法,消除了通用检测仪由于光源光强不稳定产生的误差,使得测量结果只与光强的相对变化量有关;光波出入波导均采用棱镜耦合,减少了普通测试方法因样品质量及面形误差和端面洁净情况不同或输出透镜不能很好汇聚光波而产生的误差;利用常规仪器设备实现了数字化检测显示,避免了人为主观读数产生的误差; 利用AD538实时模拟计算芯片,提高了计算精度和运算速度。     

Optical properties of CdSe quantum dots grown on ZnSe and ZnBeSe by molecular beam epitaxy

We report detailed studies of the optical properties of CdSe quantum dots (QDs) grown on ZnSe and ZnBeSe by molecular-beam epitaxy (MBE). We performed steady-state and time-resolved photoluminescence (PL) measurements and observe that nonradiative processes dominate at room temperature (RT) in the CdSe/ZnBeSe QDs structures, though these nonradiative processes do not dominate in the CdSe/ZnSe QDs structures up to RT. We performed secondary ion-mass spectrometry (SIMS) measurement and propose that the oxygen incorporation in the ZnBeSe layers (possibly caused by the reactivity of Be) may contribute to the dominant nonradiative processes at high temperatures in the QDs grown on ZnBeSe.     

Computational studies on the radiative and nonradiative processes of luminescent N-heteroleptic platinum(II) complexes

Three N-heteroleptic Pt(II) complexes, [Pt(C^C)(O^O)] [O^O = acetylacetonate, C^C = 1-phenyl-1,2,4-triazol-5-ylidene (1), C^C = 4-phenyl-1,2,4-triazol-5-ylidene (2), C^C = 2-phenylpyrazine (3)] have been investigated with density functional theory (DFT) and time-dependent density functional theory (TDDFT). The radiative decay rate constants of complexes 1–3 have been discussed with the oscillator strength (f_n), the strength of spin–orbit coupling (SOC) interaction between the lowest energy triplet excited state (T₁) and singlet excited states (S_n), and the energy gaps between E(T₁) and E(S_n). To illustrate the nonradiative decay processes, the transition states between triplet metal-centered (³MC) and T₁ states have been optimized and were verified with the calculations of vibrational frequencies and intrinsic reaction coordinate (IRC). In addition, the minimum energy crossing points (MECPs) between ³MC and ground states (S₀) were optimized. At last, the potential energy curves relevant to the nonradiative decay pathways are simulated. The results show that complex 3 has the biggest photoluminescence quantum yield because the complex 3 has the biggest radiative decay rate constant and the smallest nonradiative decay rate constant in complexes 1–3.     

基于特征波段-Fisher-K近邻的木器漆拉曼光谱的快速无损鉴别

为了实现木器漆的快速无损检测以及精确识别与分类,采集并获取了晨阳等3种品牌木器漆样本的拉曼光谱,并考察了基线校正、Savitzky-Golay九点平滑法、一阶导数和二阶导数等不同预处理方法的处理效果,建立了特征波段比值、Fisher判别、K近邻(KNN)模型。结果表明:特征波段比值法能以1358cm-1/1239cm-1表征3种木器漆的特征;基于Fisher判别的基线校正、平滑和二阶导数处理的拉曼光谱模型的分类准确率最高,能实现100%区分;在相同的预处理下,KNN判别模型的准确率仅为88.5%。基于二阶导数的拉曼光谱结合特征波段-FisherKNN法能为不同品牌木器漆的准确检测提供一种新的快速无损分析手段,具有普适性和一定的借鉴意义。     

大功率白光LED封装技术对器件寿命的影响

通过功率LED器件封装工艺技术的改进来降低芯片结温,从而减缓器件光衰速率,延长其预期的工作寿命时间。对用于封装的关键原材料的选取进行了对比实验,指出了采用纳米级材料改进导热可降低热阻,论述了正确选用混胶材料和工艺,可以减缓器件光衰速率,达到在较高的环境温度条件下,器件使用寿命大于50 000 h。论述了器件芯片的结温对光、电、色性能的影响和不同结温其预期工作寿命时间也不同的关联性。     

碲镉汞薄膜少子寿命测试研究

碲镉汞(HgCdTe)材料的少子寿命是影响碲镉汞红外探测器性能的重要参数.分别采用微波光电导衰减(Microwave Photoconductivity Decay,μ-PCD)法和微波探测光电导(Microwave Detected Photoconductivity,MDP)法对 HgCdTe 薄膜的少子寿命进行了...     

六种木材的微波处理实验研究*

微波处理可以破坏木材的微观结构,有效提高木材的流体渗透性。为探究微波处理木材流体渗透性改善机理,同时为人工林木材的功能化改性研究提供理论依据,文章对杉木、落叶松、樟子松、毛白杨、泡桐及尾巨桉六种木材进行微波处理实验。从扫描电镜图片中可以看出,微波处理后,微波处理材会产生射线薄壁细胞之间或与轴向组织的胞间层处产生破坏、闭塞纹孔的打开、纹孔膜破坏、细胞壁破坏及内含物重新分布等变化。微观结构的破坏导致处理材力学性能下降。其中,微波处理后樟子松、杉木、落叶松、尾巨桉、毛白杨及泡桐的抗弯弹性模量(MOE)较处理前分别下降了31.1%、35.4%、45.6%、5.5%、24.4%和23.2%;抗弯强度(MOR)分别下降了38.4%、29.4%、67.2%、9.1%、34.0%和29.1%。同时,不同树种木材中不同的微观结构破坏形式造成处理材不同的吸水性测试结果。而根据微波处理材的吸水性及力学性能测试结果,可以选择适合用于微波处理后进行功能化改性处理的树种。     

网格环境下信任机制的研究

本文介绍了网格环境下信任机制的重要性,给出了信任的定义、特性和分类,并重点描述了行为信任机制的研究方法。文章最后给出了行为信任机制在网格环境下的典型应用场景。