Authenticity green coffee bean species and geographical origin using near-infrared spectroscopy combined with chemometrics

To prevent the adulteration of agricultural resources and provide a solution to enhance the green coffee bean supply chain, authentication using the near-infrared spectroscopy (NIRS) technique was investigated. Partial least square with discrimination analysis (PLS-DA) models combined with various preprocessing methods were built from NIR spectra of 153 Vietnamese green coffee samples. The model combined with the standard normal variate and the first order of derivative yielded excellent performance in predicting coffee species with the error cross-validation of 0.0261. PLS-DA model of mean centre and first-order derivative spectra also yielded good performance in verifying geographical indication of green coffee with the error of 0.0656. By contrast, the predicting abilities of post-harvest methods were poor. The overall results showed a high potential of the NIRS in online authentication practices.     

High-efficiency Silicon Solar Cells: A Review

Over the past few decades, crystalline silicon solar cells have been extensively studied due to their high efficiency, high reliability, and low cost. In addition, these types of cells lead the industry and account for more than half of the market. For the foreseeable future, Si will still be a critical material for photovoltaic devices in the solar cell industry. In this paper, we discuss key issues, cell concepts, and the status of recent high-efficiency crystalline silicon solar cells.     

金属/Al2O3基纳米复合材料研究最新进展

金属／Al2O3纳米复合材料在保持原有金属的功能特性时，还可以获得 很好的力学性能，是有良好发展前景的一种纳米复合材料。本文回顾了近年来金属／Al2O3基纳米复合材料在制备工艺，微观结构和力学性能，增韧强化机理方面的最新进展，并指出了今后的研究方向。     

A random switching method for HPWM full-bridge inverter

To overcome the problem of unequal switching loss in power switches, in conventional hybrid pulse width modulation (HPWM) full-bridge inverters, a random switching method for HPWM full-bridge inverters is proposed. The proposed method equalizes switching losses of the four switches, while also providing good output performance     

电脑提花圆机图案的设计与开发

应用当前景流行的图形设计软件Coredraw9.0和Photoshop5.0，设计针织面料T恤花型，进一步利用SCC4F-548型电脑提花圆机相配套的图形设计软件Aupaint处理，生成提花花型图案，为夏季T恤花型图案设计提供了一条简便快捷的设计方法和新的设计思路。     

捞油车自动排绳控制装置

针对部分油田采用捞油的采油方式，介绍的自动排绳装置，是双通道化例闭环控制系统，特点是按照输入的给定、误差信号方向、大小变化，输出信号的方向、大小随之变化，自动跟踪，自动补偿，输出速度连续无级变速，可以手动和自动工作。     

色用缓变光纤中交叉相位调制不稳定性分析

从非线性薛定谔方程出发得到了色散缓变光纤（DDF）中交叉相位调制（XPM）不稳定增益谱。研究了增益谱随入纤功率及光纤纵向色散参量的变化关系。结果表明：反常色散区的增益谱宽比正常色散区宽，且峰值增益高：DDF中XPM不稳定增益谱宽比常规光纤的宽，二者的比值随传输距离和光纤色散参量的乘积成指数增长；DDF的反常色散区是产生调制不稳定的较好的色散介质。     

Holographic polymer‐dispersed liquid crystal fabrication under electric field

The transmission mode of holographic polymer‐dispersed liquid crystals (HPDLCs) was developed an under electric field. It is reported that orientation of LC molecules under an electric field induces orientation of oligomer molecules giving rise to low off‐state diffraction and small grating shrinkage. Copyright © 2005 Society of Chemical Industry     

GM300电台的调试原理及方法

GM300电台是一种性能优良的电台，目前在我国的地震勘探领域广泛应用。与其它类型的电台相比，GM300电台的调试方法完全不同。掌握其调试原理及方法是对该类电台进行正确维护的基础。本文从分析GM300电台调试原理入手，总结了该电台的调试方法。     

冷成型模具低温锌系磷化

研制出适用于冷成型模具高硬度表面的低温锌系磷化工艺。其中磷化液含Zn(H2 PO4 ) 2 ·2H2 O 6 0g/L ,Zn(NO3) 2 ·6H2 O 90g/L ,NaNO2 1.5g/L ,稀土促进剂 0～ 1.0g/L ,游离酸度 4～ 6点 ,总酸度 70～ 75点。该磷化液在 4 0℃下 ,处理 30～ 4 0min后可获得厚约 10 μm的磷化膜。性能测试表明 ,其减摩、润滑性能良好 ,摩擦系数约降 0 .1,与未处理试样相比磨损量下降 96 % ,附着力 1级。