Fabrication and amplification of Rhodamine B‐doped step‐index polymer optical fiber

A step‐index polymer optical fiber (SI POF) containing Rhodamine B in poly(methyl methacrylate) (PMMA) has been fabricated by a preform technique. Fluorescence of different fiber lengths were observed and discussed. A high gain (23 dB) for a SI POF with 60‐cm length, 400‐μm diameter was obtained. The Rhodamine B content of the doped SI POF is 5 ppm‐wt. The signal wavelength providing the highest gain for a 60 cm SI POF is around 630 nm, and the optimum fiber length is about 60 cm at 10 kW launched pump power. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 681–685, 2004     

Adsorptive voltammetry of Hg(II) ions at a glassy carbon electrode coated with electropolymerized methyl-red film

The glassy carbon electrode coated with electropolymerized methyl-red film, 1.2 × 10⁻⁶ m in thickness, (PMRE) showed high sensitivity towards Hg(II) ions. PMREs were adopted to accumulate and detect Hg(II) ions in a pH 2.56 Britton–Robinson buffer solution. Cyclic voltammogram of the accumulated Hg species on PMREs exhibited an anodic wave at 0.64 V and a cathodic wave at 0.13 V, due to the oxidation of accumulated Hg species on PMREs and the reduction of Hg(II) ions in the solution, respectively. For this heterogeneous adsorption of Hg(II) ions onto PMREs, the maximum surface concentration, adsorption equilibrium, and Gibbs energy change were evaluated to be 5.12 × 10⁻⁶ mol m⁻², 3.7 × 10⁵ l mol⁻¹, and −30.1 kJ mol⁻¹, respectively. The anodic peak current at 0.64 V was linear with the concentration of Hg(II) ions in the range of 1.1 × 10⁻¹⁰ to 1.1 × 10⁻⁷ M with a detection limit of 4.4 × 10⁻¹¹ M. The proposed method was utilized successfully for the detection of Hg(II) ions in the lake water.     

CIM环境下CAPP的研究与实践

通过对我国ＣＩＭＳＭＲ中的两个集成化ＣＡＰＰ系统──ＮＰＵＲＣＡＰ和ＦＡ－ＣＡＰＰ进行对比，对基于特征的零件模型、ＣＡＤ／ＣＡＰＰ／ＣＡＭ集成、ＣＡＰＰ同其它ＣＩＭ子系统的集成、工艺决策专家系统、工艺决策方法、工艺知识表示、工艺知识库技术等问题进行了研究，同时，提出了加工元（ＭＥ）概念，并把该概念用于零件的工艺性分析，以实现面向制造的设计（ＤＦＭ）和工艺决策的模型化、算法化．此外，也对工艺过程的动态优化问题进行了初步研究，为并行工程（ＣＥ）下的ＣＡＰＰ集成化研究提供基础．     

Synthesis of Polycaprolactone with Two Carboxyl End Groups

At 225℃. caprolactone has been polymerized in the presence of succinic acid under dry nitrogen atmosphere. Characterizations of the polymer through IR and molecular weight measurements by 1H-NMR and end group titration have shown that the polycaprolactone obtained is of two carboxyl end groups. The molecular weight of it increases with decreasing of the acid content in the reaction mixture under the same polymerization conditions. With a certain ratio of acid to caprolactone. the maximum of molecular weight of the polymer will be reached at the reaction time of 3h.     

IPTV业务保障及其关键技术研究

IPTV是当前最热门技术领域之一,主要的电信服务提供商都在努力推出自己的IPTV业务。研究了IPTV业务保障问题及其重要意义,提出了从承载网络、内容传送及业务体验三个方面实现IPTV业务保障并分析了其中的关键技术。     

Effect of silver nanoparticles on photo-induced reorientation of azo groups in polymer films

A series of polymer films containing azo groups and silver nanoparticles were prepared. Photo-induced reorientation of the film was conducted under irradiation of polarized light with wavelength at 365 nm, 442 nm and 532 nm, respectively. The influence of the concentration of dopant silver on the reorientation of the azo groups was studied. An enhancement of about 50% for the reorientation rate and about 70% for the reorientation amplitude was achieved. From a comparison of the enhancement obtained by irradiating with three different light sources, it was realized that the mechanism for enhancement of reorientation of azo groups is due to plasmon resonance of silver nanoparticles doped in the polymer films.     

Satellite-based time series calibration of GF-1 WFV sensors for large view zenith angle observations

ABSTRACT

A novel satellite cross-calibration method is proposed using image pairs with large view zenith angle observations. Previous studies on cross calibration have focused primarily on image pairs with nadir or small view zenith angles, while this study introduces a technique for large view zenith angle observations using bidirectional reflectance distribution function (BRDF) correction. This technique was applied to images from the wide field of view (WFV) onboard the GAO FEN-1 (GF-1) satellite and Terra Moderate Resolution Imaging Spectroradiometer (MODIS) sensors as it transited over the Dunhuang site in China. A total of 62 image pairs, collected from 2013 to 2016, were used in the cross-calibration process. However, only 12 of 62 image pairs included a small view zenith angle difference (less than 10°), while the other image pairs featured a large view zenith angle difference. An experimental time series calibration was conducted using the proposed technique as well as conventional cross-calibration methods for comparison purposes. Time series calibration results also showed an attenuation trend for GF-1 WFV sensor and produced a calibration equation for day since launch (DSL). Then, the calibration equation by DSL was compared with four vicarious calibration results carried out over the Dunhuang test site from 2013 to 2016 to demonstrate its consistency. The calibration coefficients using the proposed method were also compared with the coefficients from other cross-calibration methods, taking the vicarious calibration coefficient as the reference. The comparison results showed that the calibration coefficients using the proposed method were with higher calibration accuracy and higher calibration frequency than other cross-calibration methods. The cross-calibration uncertainties caused by difference influence factors were analysed quantitatively. The results showed that the calibration uncertainties were decreased from 35.03–44.60% to 5.95–8.26% after BRDF correction, which demonstrated the proposed method to be superior for processing large view zenith angle images. These results suggest the proposed technique could be an effective new tool for future time series satellite calibration.     

无桥DBPFC变换器的虚拟超局部优化控制策略

针对传统平均电流控制的无桥Dual-Boost功率因数校正(DBPFC)变换器存在功率因数低、总谐波失真大、动态响应速度慢以及输出电压纹波较高等不足,文章提出一种虚拟超局部优化控制策略。通过坐标变换的方法建立了变换器在虚拟dq模式下的工作模型,实现对电流的无静差跟踪,并在此基础上设计了一种超局部优化控制策略,改善了基于数学模型设计的电流控制器对参数变化及内、外部扰动敏感的缺陷,克服控制器对参数的依赖。仿真和实验结果表明,文章所提虚拟超局部优化控制的无桥DBPFC变换器的功率因数可达0.996,总谐波失真为4.93%,且具有良好的动态响应能力和较高的电能质量水平。     

适用于污染河水修复的可渗透反应墙材料筛选

通过中试规模的模拟试验,进行了适用于污染河水修复的可渗透反应墙(PRB)反应材料筛选研究.结果表 明,以铁屑、焦炭、沸石和石灰石为反应材料的不同配比的6个反应器(A～F)对COD、TN及TP均有一定得去除效果,其中,反应器E对COD、TN及TP的平均去除率分别是61.0%、85.8%和82.O%,显著高于其它材料配比的反应器;各反应器出水铁离子含量均高于进水,但远远低于抑制微生物降解作用的最高容许含量.综合各项指标,反应器E和F反应材料铁屑,焦炭、沸石的体积比较佳,分别为1:2:1和1:1:2,适于典型地表污水.污染河水的修复,其中又以反应器E的反应材料配比更优.