企业网络交换机配置文件的批量备份

交换机配置文件的备份是网络维护工作的一项重要内容,大型企业网中一般有不同规格型号的交换设备数百台,使得手动备份的工作相当繁琐。为解决交换设备配置文件批量和自动备份问题,使用Visual Basic.开发的一个运行在WIN DO WS环境下的软件,利用交换机备份数据表、Win Sock控件和Do Event函数等,有效地进行批量工作,并得到了较好的应用效果。     

程控多路宽电压通道切换电路设计

为克服传统校验方法的不足,简化自动化测试设备的面板设计和校验过程,基于单片机技术和RS-422通信接口,设计了一种程控多路宽电压通道切换电路。介绍了电路工作原理、元器件选择、软硬件设计过程。该电路已经在多台测试设备的校验环节得到应用,工作性能稳定。     

水中溶解性有机物分子量分布测定方法评价

文章介绍了两种测定水中有机物分子量分布的方法 :滤膜过滤法及凝胶液相色谱法 ,并列出了一些研究者用两种方法测定水源水的结果 ,根据两种方法的测定原理、测定步骤及对数据的分析 ,作者认为滤膜法应视作为一种粗略的方法 ,有条件时应尽量采用凝胶色谱法     

乙酸乙酯与乙酸正丙酯的切换式连续生产

作者在对乙酸乙酯、乙酸异丙酯、乙酸正丙酯和乙酸丁酯的现有生产工艺进行分析后,以乙酸乙酯和乙酸正丙酯为研究对象,在以往对两者研究的基础上,提出了乙酸乙酯与乙酸正丙酯切换式连续生产的工艺流程,并且通过模拟计算和小试验证证明,在同样的生产装置上,可以分别连续生产乙酸乙酯和乙酸正丙酯,采用该工艺生产乙酸乙酯能耗低于传统工艺12%,生产乙酸正丙酯比原有工艺可以提高收率2%。     

沿海电厂露天布置循环水泵出口液控蝶阀的可靠性优化

循环水泵出口液控蝶阀关系到循环水泵自身乃至整台机组的安全运行。但露天布置的液控蝶阀跟传统室内布置的液控蝶阀比,其运行环境比较恶劣,对系统的安全投运带来许多隐患。针对浙江大唐乌沙山发电厂出现的问题,本文从热控角度提出选型、安装、维护等方面的几点建议。     

基于S120变频器的转炉倾动主从控制设计及应用

随着SINAMICS S120在工控领域的应用,越来越多的成功应用案例随之产生,主从控制方案就是一个典型的案例,在许多工业领域得到了应用.本文主要介绍了转炉倾动控制系统的主从控制方案设计,实现变频器主从自动切换的调试过程及注意事项.     

开关电源新技术的应用研究

以功率MOSFET和IGBT为代表的、集高频、高压和大电流于一身的功率半导体复合器件,表明传统电力电子技术已经进入现代电力电子时代,开关电源的工作频率得以大大提高,一些新技术的应用更是进一步提升了开关电源的性能。开关电源拥有更广阔的发展空间和应用前景。     

可编程控制器和变频器在倒棱机中的应用

介绍可编程控制器、直流调速系统、变频器、电子凸轮开关在倒棱机中的应用。为使设备运行最佳化，对可编程控制器的程序、辊道的变频调速等进行技术改造，使设备性能大为改善，系统的稳定性显著提高。     

Adhesion-Delamination Mechanics of a Prestressed Circular Film Adhered onto a Rigid Substrate

A thin circular film clamped at the periphery is adhered to the planar surface of a rigid cylindrical punch. An external tensile load is applied to the punch, causing the film to delaminate from the substrate and the circular contact edge to contract. The film spontaneously separates from the punch, or pulls off, when the contact radius reduces to a range between 0.1758 and 0.3651 of the film radius, depending on the magnitude of the residual membrane stress. The mechanical delamination process is derived by a thermodynamic energy balance based on a coupled interfacial adhesion and residual membrane stress. The theoretical model has significant implications in nanoforce measurement, microelectromechanical systems (MEMS) comprising active moveable films, and biological cell adhesion.     

Accurate determination of hexanal in beef bouillons by headspace solid‐phase microextraction gas‐chromatography mass‐spectrometry

Lipid oxidation has great impact on the quality of food products through flavor and taste deterioration, reduction in nutritive value, and potential toxicity of the oxidized food components. Flavor and taste deterioration can be easily perceived and it represents one of the major causes of consumer complaints in the food industry. The deterioration of sensory properties is due to the decomposition products of hydroperoxides that easily isomerize and degrade into volatile compounds. Volatile products are responsible for flavor and taste deterioration. In this study, we present the development of the solid‐phase microextraction gas chromatography‐mass spectrometry (SPME‐GC‐MS) technique to quantify low amounts (μg/g range) of secondary oxidation products, i.e. hexanal. The optimization of SPME parameters is a difficult task because of the possibility of further formation of volatile products during analysis. Different parameters such as type of fiber, exposure time of the fiber to the sample headspace and the optimal temperature of absorption have also been investigated. The complete validation of the method was achieved by the determination of linearity, limits of detection and quantification and repeatability. We demonstrated that the SPME method is a valuable tool for the quantification of low amounts of secondary oxidation products such as hexanal. Therefore, this technique can be used to detect early formation of volatiles.