PVC及PMMA在CO_2环境中玻璃化转变特性的研究

对聚合物在CO2环境中的玻璃化转变特性进行了研究。利用蠕变柔量法,在自建的实验装置上,对聚氯乙烯和聚甲基丙烯酸甲酯在CO2环境中不同压力下的玻璃化转变温度进行了测定,并利用间接法测定了对应状态下聚合物中CO2的质量分数。结果表明,在CO2环境中2种材料的玻璃化转变温度显著降低。利用基于经典热力学与统计热力学理论构建的模型,对聚合物中不同的CO2质量分数对应的玻璃化转变温度值进行了计算,得到的计算结果与实验结果较吻合。     

无载调压变压器高压绕组直流电阻不平衡故障分析

介绍变压器绕组直流电阻的测量、故障分析及处理。通过测量变压器绕组连同套管的直流电阻,检查绕组内部导线接头的焊接质量、引线与绕组接头的焊接质量、电压分接开关各个分接位置及引线与套管的接触是否良好、并联支路连接是否正确、变压器载流部分有无短路情况以及绕组有无短路现象,以保证变压器安全稳定运行。     

浅谈窃电、防治窃电措施和检查步骤

随着我国经济的快速发展,人们对电力资源的需求量越来越大。一些用户在利益的驱使下,为了减少电费开支,常采用一些不法手段窃电,这极大地降低了电力企业的经济效益,对电力企业的发展造成了很大的影响。通过分析常见的窃电手法,提出了一些防治窃电的措施。     

基于ZnO@rGO/PVDF柔性复合薄膜的压电纳米发电机

采用简单的一步水热法合成了自支撑的氧化锌纳米棒(ZnO NRs)@还原氧化石墨烯(rGO)复合材料,通过旋涂法制备ZnO@rGO/聚偏二氟乙烯(PVDF)柔性复合薄膜压电纳米发电机。研究结果表明,ZnO@rGO/PVDF柔性复合薄膜压电纳米发电机的输出性能随ZnO@rGO掺杂质量先增大后减小,当ZnO@rGO的质量分数为3.0%时,输出电压可达9.06 V,输出电流可达0.74μA,与仅掺杂3.0%ZnO NRs的ZnO/PVDF纳米发电机相比,其输出电压和电流分别提高了120%和124%。当负载电阻为10 MΩ时,ZnO@rGO/PVDF柔性复合薄膜压电纳米发电机输出功率最大为5.79μW。经过4 000次循环测试表明,该文所制备ZnO@rGO/PVDF柔性复合薄膜压电纳米发电机的输出性能稳定。该纳米发电机可以监测人体行走和跑步姿势,记录运动次数。有望作为自供电压力传感器件植入可穿戴电子设备中。     

基于Pro/E的结肠镜机器人的建模与仿真

连续型机器人是一种新型的仿生机器人。以所研制的结肠镜机器人样机为基础,基于Pro/E的运动仿真模块对结肠镜机器人单关节进行运动学分析,完成了万向环间的干涉检验,从而验证结肠镜机器人的结构设计可行。     

宁夏遥感影像旅游地图的编制

为更加充分地展示宁夏地貌、地形特点,选用平面制图软件CorelDRAW12,从宁夏遥感影像地图的整体设计、特色符号设计、绘制地图等方面制作宁夏遥感影像旅游地图,使其成为独具宁夏文化旅游特色的旅游地图,并把宁夏旅游信息传递给各地游客．     

Dynamic changes in wax and cutin compounds and the relationship with water loss in 'Red Fuji' and 'Golden Delicious' apples during shelf life

Knowledge of the dynamic composition changes of combined cuticular wax and cutin in apples during their shelf life is scarce. Therefore, this issue was addressed using GC-MS analyses of the respective epidermal components in 'Red Fuji' and 'Golden Delicious' apples at 5 days intervals during the shelf life of 25 days. Water loss from the apples was also assessed. The proportion of total n-alkanes decreased in cuticular wax, whereas total acids increased gradually, and cutin monomer content significantly changed during the first 5 days. The predominant wax compound, nonacosane (C₂₉), decreased by 40.13% and 26.22% in 'Red Fuji' and 'Golden Delicious' apples, respectively. The cutin monomers 10,16-dihydroxy hexadecanoic acid (10,16-diOH C_16:0) and 9,10,18-trihydroxyoctadecanoic acid (9,10,18-triOH C_18:0) were detected only at the beginning of shelf life in apples of both cultivars. Regression analysis indicated that the rate of water loss significantly correlated with eight components. Our results expand the understanding of the dynamics of both wax and cutin compounds in postharvest apples and help to target specific compounds to maintain the quality of apples throughout their shelf life.     

大庆油田加密井地面工程项目质量及进度管理与控制研究

油田地面工程建设在油田管理工作中占有重要地位。油田地面工程建设作为一项持续不间断的工作,投资大,投资周期长,并直接影响到油田企业的产能建设成效。因此施工管理具有极其重要意义。本文主要结合油田A区块加密井产能建设地面工程项目开展研究,对项目组织管理与控制、项目进度管理与控制、项目质量管理与控制等方面如何如何进行管理进行了论述,对提高油田地面工程的质量,确保工程的运行效果具有一定的现实意义。     

废弃纤维再生混凝土受压徐变及预测模型

为研究再生粗骨料替代率、废弃纤维体积掺入量对废弃纤维再生混凝土受压徐变破坏时间、徐变变形和徐变度的影响规律,对普通混凝土、再生混凝土和废弃纤维再生混凝土试件在实验室条件下进行了85%、90%和95%应力水平的徐变试验。试验结果表明：随着再生粗骨料替代率的增加,徐变破坏的时间缩短、徐变变形及徐变度增大;随着废弃纤维体积掺入量的增加,徐变变形及徐变度减小,徐变破坏时间增加。废弃纤维的加入能有效缓解再生混凝土受压徐变的破坏程度。在考虑再生粗骨料替代率及废弃纤维体积掺入量的基础上,对ACI209R徐变预测模型进行修正,模型预测结果与试验值吻合较好。     

Electrical performance and ferroelectric phase transition characteristic in different oriented 0.73PMN-0.27PT single crystals

The electrical and optical properties of (001)- and (110)-oriented 0.73 Pb(Mg_1/3Nb_2/3)O₃-0.27PbTiO₃ single crystals are systematically investigated at various temperatures, both of which present a series of ferroelectric phase transition processes. Dielectric performance measurements reveal that the ferroelectric phase transition occurs over a temperature range, rather than at one temperature point. By testing the ferroelectric hysteresis P–E curves as well as bipolar and unipolar electric field-induced strain S–E curves, the values of remnant polarization, coercive field, maximum strain, and converse piezoelectric constant d₃₃^* change considerably near the phase transition temperatures. Simultaneously, the 0.73PMN-0.27PT single crystals with (001)- and (110)-orientations under a low electric field show ultrahigh d₃₃^* values of 3540 and 2817 pm/V, respectively, which can be attributed to the electric field-induced monoclinic and orthorhombic phases, respectively. The series of ferroelectric phase transitions upon heating, that is, from rhombohedral ferroelectric to monoclinic/orthorhombic, followed by from monoclinic/orthorhombic to tetragonal, and finally from tetragonal to cubic paraelectric, are further investigated via polarized light microscopy and Raman spectroscopy.