低热通量下碳纤维/环氧树脂层合板的燃烧特性

使用锥形量热仪研究了35 kW/m²热通量下碳纤维/环氧树脂层合板的点燃时间、质量损失速率、热释放速率等燃烧特性参数与其厚度的关系,建立了热穿透深度的数学模型以得到不同厚度层合板的热穿透深度、判别层合板的热厚热薄特性并分析燃烧过程。结果表明：在低热通量下,随着碳纤维/环氧树脂层合板厚度的增加其点燃时间延长、平均质量损失速率和质量损失速率峰值下降、总释放热量增大、热释放速率峰值先增大后减小;碳纤维/环氧树脂层合板在点燃时表现为热薄型或是热厚型,与其物理厚度有直接关系。热厚型材料有一个由热厚型向热薄型转变的热响应过程。     

基于太阳能供热的石墨烯/石蜡复合相变材料蓄放热特性实验研究

由于太阳能间歇性和不稳定性的缺点,给其在供热方面的应用带来了局限,采用相变储能法可改善太阳能供热应用的缺点。对此以石蜡为基液,向其中添加石墨烯通过"两步法"制备出石墨烯质量分数分别为0.1%、0.3%和0.5%的复合相变材料,搭建复合相变材料蓄放热实验台并记录数据。结果表明:在相同的实验条件下,石墨烯/石蜡复合相变材料随着石墨烯质量分数的增加,熔化速率也随之增加,在添加量为0.5%时增加了14.15%;凝固速率也随石墨烯质量分数的增加而增加,但效果不如熔化速率明显;复合相变材料在圆管外的蓄放热过程中,位于圆管底部的材料熔化与凝固效果均不理想。     

Interference-aware node access scheme in UAV-aided VANET

In vehicular Ad Hoc network (VANET),frequent link handovers and channel interference can lead to increased transmission delay and decreased network throughput.To address the issues,unmanned aerial vehicle (UAV) were introduced to cooperate with vehicles and construct UAV-assisted air-ground integrated VANET.An interference-aware node access scheme was proposed.The node access problem was formulated as a multi-objective optimization problem considering link transmission rate,link handovers and transmit power.Then the optimization problem was decomposed into two convex optimization sub-problems by dual decomposition method,the sub-problem jointly optimizes handovers and link transmission rate while the sub-problem optimizes the transmit power based on link reliability.Finally,simulation results show that the proposed mechanism can effectively improve data delivery ratio,average end-to-end delay and network throughput.     

Systematic Analysis of Geometric Performance of Fengyun-3C MERSI Satellite Data Using Image Chip Matching Method

Geometrically corrected satellite image with the high accuracy is the key in support of the satellite data applications.However,the geometric errors of the data from the MEdium Resolution Spectrum Imager onboard the second generation of polar orbiting Chinese Meteorological satellite after the systematically geometric correction is still high.This paper came up with an approach to quantify the geometric errors and made the further analysis of these errors,aiming at the next step for the further geometric correction.The approach takes 4 indices to quantify the geometric errors:CE90 indicates the radius of the circle errors for the 90% control points;RMSEH indicates the horizontal errors on the image;RMSEX and RMSEY indicate the longitude and latitude errors,respectively.The image chip matching technology is applied to identify the control points on the image.The errors for the single image and time series of images were further calculated using abovementioned 4 indices.The case study in North China Plain shows that the geometric errors for various images are uneven and no uniform systematical geometric error found.Sometimes the geometric error may be small as CE90 1.41 pixels,RMSE H 0.97 pixels,RMSEX 0.74 pixels and RMSEY 0.64 pixels but for example April 29,2014,the geometric may be large as CE 90 14.87 pixels,RMSEH 13.0 pixels,RMSEX 9.45 pixels,RMSEY 8.93 pixels.The averaged geometric errors for the period of October 5,2013 to May 30,2015 were as CE90 5.97 pixels,RMSEH 4.94 pixels,RMSEX 3.29 pixels and RMSEY 3.28 pixels.A dramatic decrease of the geometric errors was observed since the beginning of the year 2015 due to the update of the systematical preprocessing of the satellite data at the end of 2014.This update improved the geometric errors with the decrease from approximate 15 pixels to below 8 pixels.This proposed approach has obvious advantages in terms of efficiency in comparison with manually identifying control points since it adopts image chip matching technology.     

Miscibility, free volume behavior and properties of blends from cellulose acetate and castor oil-based polyurethane

A series of blend films from cellulose acetate (CA) and castor oil-based polyurethane (PU) were prepared. Morphology, miscibility, free volume behavior and properties of such blend films were investigated by wide-angle X-ray diffraction (WXRD), infrared, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), positron annihilation lifetime spectroscopy (PALS), thermogravimetric analysis and tensile test. The results indicated that lager free volume cavities did not form at the interface of two polymers although a certain degree of phase separation was found by the studies of SEM and DSC. Strong intermolecular hydrogen bonding interactions at the interface, which was proved by Fourier transform infrared spectroscopy, favors even better molecular packing, that is, PU dispersed in CA continuous phase to form fine microphase separation domain in the CA-rich blends. Due to such special interactions in the fine microphase separation domain structure, optimized properties of tensile strength, breaking elongation and cold-resistivity were obtained in the blend film with 75 wt% CA. The toughness of all the blend films was significantly higher than that of the film CA, owing to the plasticizing of PU elastomer in the blends.     

密封消解法测定CODMn

目的探索采用密封消解测定高锰酸盐指数的新方法,为监测和防治提供及时、可靠的数据.方法该法以《水和废水监测分析方法》中的标准法为基础,用密封消解法代替水浴加热,消解后仍然用滴定法测定,同时为了消除KMnO4自身分解对测定结果的影响,研究采用分光光度法建立吸光度和KMnO4浓度曲线测定自分解消耗量,并从滴定测定结果中扣除,保证了结果的准确性.结果标准曲线的相关系数r=0.999 8,消解时间15 min、温度150℃,测定结果的相对标准偏差小于2%,相对误差在5%~6%之间,精密度与准确度均能满足要求.结论在95%的置信度下,与标准法进行t值检验（t〈2.23）,说明两种方法不存在显著性差异.研究表明高锰酸盐指数测定的密封消解法具有省时节能、试剂用量少、操作简便、可批量处理等优点.     

基于大数据的继电保护智能运行管控体系探索

为推进继电保护运维专业管控体系化和全过程各个关键环节管控智能化,探索构建了基于大数据的智能运行管控体系。以继电保护数据中心为基础,构建了现场运维全过程关键环节的四大场景应用,包括现场可视化运维与防误预警、远程运维、工厂化检修、移动电子化作业。实现了继电保护运维专业技术管控的六大高级应用,包括工况评估及趋势预测、电网故障辨识、动作行为智能诊断、准实时在线监视、SCD智能管控和整定计算。该体系有助于解决变电站运行、维护、检修各个关键环节和继电保护专业技术管理存在的系列问题,提高了继电保护设备安全运行管控水平。     

含多个能源站的区域综合能源系统建模及协同优化运行策略

区域综合能源系统通过统一调度不同能源设备,协调优化电、气、冷、热多种能源系统来提高区域供能的经济性和环保性。但是多种能源的耦合提高了系统运行的复杂性,因此需要有效的优化方法来保证其运行经济性。通过分析多能源站区域综合能源系统结构,构建了区域综合能源系统模型。在此基础上,提出了一种以系统运行经济性为目标、包含多个能源站的区域综合能源系统协同优化调度方法。案例仿真结果显示,多能源站协同优化运行可以大幅提高区域综合能源系统运行的经济性。     

谐振式硅微结构压力传感器非线性振动特性研究

本文研究了谐振式硅微结构压力传感器在单频激励和双频激励情况下的非线性振动特性。利用多尺度法研究运动方程中三次非线性项对传感器频率特性的影响规律，提出了改善谐振式硅微结构传感器特性的方法以及在实现闭环自激系统时应采取的措施。