A phosphorus‐containing phenolic derivative and its application in benzoxazine resins: Curing behavior,thermal, and flammability properties

In this work, flame‐retardant benzoxazine resins were prepared by copolymerization of bisphenol A based benzoxazine (BA‐a) and a phosphorous‐containing phenolic derivative (DOPO‐HPM). The curing behavior, thermal stability, and flame resistance of BA‐a/DOPO‐HPM composites were studied by differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), limited oxygen index (LOI) measurement, UL94 test, and cone calorimeter. The DSC results indicated that DOPO‐HPM catalyzed the curing reaction because of its acidity. The TGA results revealed that the BA‐a/DOPO‐HPM thermosets possessed higher decomposition temperatures (T_5%) and char yields than that of BA‐a. The combustion tests indicated that the flame retardant properties of BA‐a/DOPO‐HPM thermosets were enhanced. The BA‐a/DOPO‐HPM‐20 sample acquired the highest LOI value of 32.6% and UL94 V‐0 rating. Moreover, the average of heat release rate (av‐HRR), peak of heat release rate (pk‐HRR), average of effective heat of combustion (av‐EHC) and total heat release (THR) of BA‐a/DOPO‐HPM‐20 were decreased by 24.6%, 53.1%, 14.9%, and 22.1%, respectively, compared with BA‐a. The attractive performance of BA‐a/DOPO‐HPM blends was attributed to the molecular structure of DOPO‐HPM composed of DOPO group with excellent flame‐retardant effect and phenolic hydroxyl group with catalysis. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43403.     

基于Contourlet变换和多尺度Rentinex的水下图像增强算法

针对水下图像对比度低、边缘模糊、噪声大等特点,提出一种基于非下采样Contourlet变换和多尺度Retinex的水下图像增强算法。将水下图像进行多尺度多方向的非下采样Contourlet变换;利用多尺度Retinex算法调整低频系数,提高图像整体对比度;在各带通方向子带上估计噪声,抑制模值小于阈值的系数,改进神经网络中的Sigmoid函数用于调节模值大于阈值的系数;经非下采样Contourlet逆变换得到增强图像。与几种传统增强算法相比,本算法处理的图像达到了抑制噪声、改善图像对比度、突出目标轮廓的目的,具有较高的对比度评估值。     

大学物理仿真实验教学系统中霍尔效应虚拟实验课件的设计实现

霍尔效应虚拟实验课件采用面向对象技术实现实验场景及仪器的数值建模与图像建模,用逼真的三维图片和事件驱动方式实现场景和仪器的界面及操作仿真,实现了可设计性、操作的任意性和具有真实感的交互功能,使学生能像操作真实实验一样操作它,产生浓厚的兴趣,达到良好的教学效果。     

嗜热链球菌分批发酵工艺放大研究

近年来,随着国内消费者对酸奶制品需求量的激增,使得乳酸菌浓缩培养成为亟待解决的难题。针对这种情况,在确定嗜热链球菌适宜的碳、氮源分别为乳糖和蛋白胨、适宜的碳氮比例为2∶1的基础上,将嗜热链球菌从小试培养放大到10L发酵罐。试验结果初步证实,三颈瓶比三角瓶更适于将实验室成果向小规模工业发酵过渡,只要保证关键参数与发酵罐相同或接近,嗜热链球菌经三颈瓶培养6h的最大活细胞数可达到3.81×109cfu/mL,与10L发酵罐的3.78×109cfu/mL菌体产量相似。     

银铜复合带材生产工艺的研究

采用快冷雾化制粉技术和可控气氛复合技术生产高性能的银铜复合带材，可以连续大卷重进行生产，所生产的复合带材厚度比均匀，复合介面清洁、复合强度高，电性能良好，并可根据客户的要求生产不同厚度比和机械性能的带材。     

PDH准数字微波通信设备技术维护经验浅议（下）

在我省所用的PDH准数字微波通信设备运行维护的基础上，对经常发生的设备故障和由此而引起的电路阻断原因进行了分析和总结，汇集了多年来各站的故障判断及处理方法和维护经验。     

THE PRELIMINARY STUDY ABOUT THE COMPOSITION OF DAQING HEAVY FRACTION OIL

The family composition of Daqing heavy fraction oil and the latent content of lubricating oil by mass spectrography and slovent dewaxing methods were determined, and then compared with document data.The change of Daqing heavy distillate is discussed.The results show Daqing crude oil and its distillates have the trend to be heavier,but its heavy distillates are still suitable for catalytic stocks of heavy catalytic cracking and its residuum can be also used for the feed stocks and other wide uses. We hope the analysis results can provide scientific basis for refineries.     

一种光虚拟专用网管理实现方案

光虚拟专用网（OVPN）是自动交换光网络（ASON）的一种新兴的增值业务,ASON控制平面使得OVPN的实现更加灵活.文章对OVPN的管理方案进行分析,提出了一种基于WBEM（Web-based enterprise management）的管理体系结构,并对OVPN的通用信息模型（Common Information Model）进行了分析设计.     

Analysis and spectral characteristics of a spread-spectrumtechnique for conducted EMI suppression

Frequency modulation (FM) and random switching methods have been used for reducing conducted electromagnetic interference (EMI) in power converters. Limited theoretical studies and comparisons of these schemes, however, are available. In this paper, a detailed analysis and the spectral characteristics of a random carrier-frequency (RCF) technique for suppressing conducted EMI in an offline switched-mode power supply are presented. The analysis provides a theoretical platform for studying the characteristics of this random switching scheme. The level of randomness is defined for the RCF scheme and varied in the converter example so that the effects on the power spectra can be demonstrated. Theoretical predictions of the spectral characteristics of this scheme are confirmed with measurements. The RCF scheme has been compared with the standard constant-frequency pulsewidth modulation (PWM) scheme and the FM scheme. Comparisons of their spectral performance show that the RCF scheme has better conducted EMI suppression than the FM and standard PWM schemes