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By use of X-ray diffractometry and scanning electron microscope(SEM),the friction and wear results obtained from MM-1000 dynamometer tests of CVI pitch/resin C/C composites were analyzed.By investigating the factors that affected the friction and wear properties,such as matrix carbon,applcation environment,graphitization degree and brake pressure,etc,friction and wear mechanism of carbon materials were probed.The results indicate that pitch densified CVI initially treated composite is more graphitizable with its graphitization degree up 59 62%,and which results in uniform small debris easier to generate,more smooth friction curves with the coefficient of 0.3-0.4 and relatively higher wear and mass loss,compared with CVI/resin C/C composites.It was further proved by SEM observation that tribological behavior of C/C composite was system dependent.Factors determining the friction and wear properties such as the size of debris and its influence on friction and wear,brake pressure,graphization degree and debris bilm formation interacted and affected each other.The friction and wear mechanism of C/C composites under different high temperature treatments needs further research. 相似文献
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分析改质沥青生产中常见的过油不畅、中间槽液下泵损坏、改质釜搅拌器及电机损坏原因 ,提出改进措施 ,取得了良好的效果 相似文献
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In aluminium plants, the anode baking process is associated with an important release of volatile combustible matter. It is the purpose of this study to investigate the kinetics of the evolution of these volatiles. A large thermogravimetry set-up has been designed in such a way that it could simulate real plant conditions. Samples of two distinct masses have been subjected to pyrolysis at different heating regimes. The loss of weight together with the concentrations of the released gases were recorded on a continuous basis during the temperature rise. Kinetic results were found for methane, hydrogen and tar. No variation of the order of reaction with the heating rate was observed, whereas the activation energy and the pre-exponential factor increased. Furthermore, for the range of sample dimensions studied, it was found that the mass of the solid had no significant influence on the kinetic parameters. 相似文献
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变桨控制技术是风力发电机组的核心技术之一,开展对风力发电机组变桨控制方面的研究具有重要的理论和应用价值。根据风力发电机组在额定风速以上如何保持输出功率稳定和降低风轮转速波动的控制技术进行研究,在传统的变桨距控制策略基础上,提出了基于BP神经网络(Neural Network,NN)整定PID的控制策略,并在Matlab/simulink环境下对PID控制和BP神经网络控制相结合的复合控制系统进行建模与分析。对1.5MW风电机组的仿真验证了BPNN-PID算法的有效性,提出算法不仅能够解决传统PID控制器参数整定困难的问题,而且优化效率更高,可以得到优良的控制性能。 相似文献
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热溶过滤法脱除煤焦油沥青中喹啉不溶物的研究 总被引:3,自引:1,他引:3
以5种煤焦油沥青为原料,喹啉为溶剂,研究了热溶过滤法脱除喹啉不溶物(QI)等杂质的效应,目的是制备QI含量较低的净化沥青。结果表明:热溶过滤法可以有效地脱除喹啉不溶物,QI脱除率随滤网网目增加而提高,但阻力增加,脱除时间变长。综合考虑脱除率和实际可操作性,采用1000目的滤布,QI含量可以降到0.3%以下,基本能达到要求。采用凝胶色谱对QI脱除后沥青的组成和分子量分布的研究表明,热溶过滤脱除了沥青中的大分子组分,分子量减小,分子量分布变窄。 相似文献
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The thermal properties of amorphous gelatin films and gelatin films with renatured structural order were measured by using conventional and temperature modulated differential scanning calorimetry (DSC). Different amounts of gelatin structural order associated with a melting enthalpic change in the DSC measurement were prepared based on different gelatin drying conditions. Two consecutive heating and cooling DSC measurements on the gelatin films showed that there was no change in the glass‐transition temperature (Tg) for the amorphous gelatin but there was a decrease in the Tg for the structural gelatin on the second DSC scan. This decrease was attributed to the plasticizing effect from the release of originally hydrogen‐bonded water associated with the structural gelatin. In addition, a reversing endotherm observed upon melting of the structural gelatin during a temperature modulated DSC measurement indicated that the transition of bound water to free water occurred as the partial triple‐helix gelatin melted. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1795–1801, 2006 相似文献