X射线相位衬度CT

X射线相位衬度CT指的是在通过X射线光源来对物体进行成像过程中使用图像的位相衬度来反映物体的密度或者厚度分布,适用于弱吸收物体,还可以减少吸收剂量,放宽成像条件中光源强度的限制和减少对样品(尤其是生物样品)的损伤.介绍了目前用于X射线相位衬度CT的三种方法,实验及图像重建的过程,并分析了各自的优缺点.     

电动汽车充电桩检定过程中的几点经验

本文针对开展充电桩检定工作中所遇到的问题,结合检定规程,对实施充电桩检定时的一些注意事项进行了分析和归纳,并对常见不合格项目进行了阐述。     

硫系玻璃微纳光器件研究进展

微纳光器件是指尺寸在微纳米量级的光学器件,具有体积小、可靠性高、耦合效率高、重量轻、设计灵活、易于集成等优点。硫系玻璃作为一种新型的微纳光器件基质材料,具有优良的红外透过性能、极高的非线性系数、较小的双光子吸收系数、超短的非线性响应时间以及组分可调等优势。近年来硫系微纳光器件研究备受关注。回顾了硫系玻璃微纳光器件的研究历程,综述了硫系微纳光纤、微球、光子晶体、微环等几种微纳光器件的研究和发展状况,并对其发展前景进行了展望。     

超精密平面磨削0.01μm微量进给装置的实验研究

微量进给可满足可延性磨削的要求,微量进给装置采用压电陶瓷作为控制元件,通过调节空气轴承供气压力,实现超精密平面磨削０．０１μｍ的微进给量,实验表明该装置可用于磨床导轨误差的缓进给补偿控制中。     

DICOM格式CT图像的数据库存储技术

图像归档与传输系统(PACS)因其重要性倍受医学界与计算机界的关注。但是，目前实际应用的PACS都是基于文件系统的，即DICOM图像以文件的形式存储。这样的PACS系统有许多缺点，例如，查询某幅指定DICOM图像的信息比较困难；文件与相关数据库记录的一致性很难维护；网络传输效率低等。文中提出了一种存储技术，以解决传统PACS的上述问题。     

Mapping the chemistry of resinite,funginite and associated vitrinite in coal with micro‐FTIR

Micro‐FTIR mapping is a powerful tool for nondestructive, in situ chemical characterization of coal macerals at high resolution. In this study, the chemistry of resinite, funginite and associated vitrinite is characterized via reflectance micro‐FTIR for Cenozoic high volatile C bituminous coals from Colombia. In comparison with the micro‐FTIR spectra of vitrinite and inertinite, the corresponding spectra of liptinite macerals in the same coals are characterized by stronger aliphatic CH_x absorbance at 3000–2800 and 1460–1450 cm^?1, but less intense aromatic C=C ring stretching vibration and aromatic CH_x out‐of‐plane deformation at 700–900 cm^?1. The aliphatic components in resinite have the longest carbon chains and are least branched, bestowing the highest hydrocarbon generation potential on resinite among the three macerals studied. In contrast, funginite exhibits the strongest aromatic character, the highest aromaticity, the lowest ‘A’ factor values and the lowest C=O/C=C ratios among the three maceral groups. Vitrinite generally displays intermediate chemical characteristics. Reflectance micro‐FTIR mapping of coal samples further confirms the aliphatic character of resinite and the aromatic nature of funginite. In addition, chemical mapping of resinite and adjacent vitrinite shows that vitrinite immediately adjacent to resinite displays higher aliphatic CH_x stretching intensity than more distant vitrinite, suggesting that chemical components from resinite can diffuse over short distances into adjacent vitrinite, specifically causing hydrogen enrichment. It needs to be pointed out, however, that the region of influence is localized and limited to a narrow zone, whose extent likely depends on resinite's properties, such as its size and aliphatic material content. This way, the chemical map of resinite and associated vitrinite provides direct evidence of the intermaceral effects occurring during the peat forming stage or during later coalification. No influence of funginite (primarily fungal spores and sclerotia) on the chemistry of adjacent vitrinite has been demonstrated, which is likely due to the highly aromatic structure of this type of funginite.     

微型机械制冷机的污染失效及其考核方法

阐述了污染失效是影响微型机械制冷机可靠性的一个关键因素，在分析污染气体的来源及其对制冷机回热器的影响等污染失效机理的基础上制订了考核方案。设计了微型高压阀，向机械制冷机工作腔内在线、连续添加污染杂质进行污染加速试验，从而解决了污染失效考核的关键问题。通过一台机械制冷机的污染加速试验对其污染失效进行了量化考核，结果表明，水蒸气、酒精、丙酮3种主要污染气体分别为74mg、31mg、114mg时使制冷性能下降约40％。污染失效的考核为机械制冷机寿命预测与污染控制提供了依据。     

窄角锥束CT的改进扫描方式

基于圆形扫描轨道的FDK算法因其机械实现简单、算法效率高，已成为目前主要使用的三维锥束CT重建算法。但在工业CT（ICT）中，当探测器面阵的尺寸较小、射线束的水平张角较小，而待检测的工件较大时，单圆扫描的FDK重建算法受到限制。为解决小尺寸探测器检测大尺寸工件问题，本文研究了一种大步距平移加小分度旋转的扫描方式。与Ⅱ代锥束CT比，这种改进的扫描方式既可以节省扫描时间，数据的冗余量也比较少。仿真实验结果表明，这种改进的扫描方式具有良好的空间分辨率和密度分辨率。     

Design and implementation of a high‐efficiency bidirectional DC‐DC Converter for DC micro‐grid system applications

This paper studies the design and implementation of a non‐isolated dual‐half‐bridge bidirectional DC‐DC converter for DC micro‐grid system applications. High efficiency can be achieved under wide‐range load variations by the zero‐voltage‐switching features and an adaptive phase‐shift control method. A three‐stage charging scheme is designed to meet the fast‐charging demand and prolong the lifetime of LiFePO₄ batteries. A digital‐signal‐processing control IC is used to realize the power flow control, DC‐bus voltage regulation, and battery charging/ discharging of the studied bidirectional DC‐DC converter. Finally, a 10 kW prototype converter with Enhanced Controller Area Network communication function is built and tested for micro‐grid system applications. A light‐load efficiency over 96% and a rated‐load efficiency over 98% can be achieved. Copyright © 2013 John Wiley & Sons, Ltd.