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排序方式: 共有1939条查询结果,搜索用时 31 毫秒
171.
The mechanical properties of carbon nanotubes (CNTs) reinforced composites would mainly depend on the pullout behavior of carbon nanotubes which are randomly distributed in matrix. In this paper, an analytical pullout model is developed for an inclined CNT embedded into matrix to study the mechanisms for improving mechanical properties of inclined CNTs reinforced composites. In this model, by employing the assumptions of constant compression stress as well as the punch strength of matrix and a perfect plastic matrix near exit point, the maximum pullout load can be predicted analytically and the entire pullout process can be characterized. Moreover, by extending the definition for inclination angle this model can be fit to more complicated loading situations. Due to all the derivations are based on assumption of continuum mechanics, this model can be used for various inclined fibers besides CNTs. 相似文献
172.
分析认为,中国现行的数字电视发展战略实质上是城市数字有线电视优先战略.尽管国家广电部门对发展农村数字电视作出了很大努力,但当前的实际情况不尽如人意.分析了农村数字电视发展缓慢的问题实质,提出一种创新的发展思路,即推动以地面数字电视为主体的有偿公益运营模式,以加速农村的数字电视发展. 相似文献
173.
《Carbon》2013
We demonstrate a method which directly grows large areas of graphene on carbon paper and glassy carbon (GC) substrates from graphite powder and anionic surfactant, sodium dodecyl sulfate, assisted electrochemical exfoliation. The electrochemically reduced graphene has been carefully characterized by scanning electron microscopy (SEM) and electrochemical techniques. Particularly, SEM images show enhanced growth of graphene structures formed of ‘urchin’ objects. The CV spectra illustrate that a variety of the oxygen-containing functional groups has been thoroughly removed from the graphite plane via electrochemical reduction. Potential peak (Ep) of graphene electrode in [Fe(CN)6]3−/4− solution is as small as 212 mV which is 168 mV smaller than that of graphite electrode. This could be attributed to the high quality graphene accelerating the electron transfer rate in [Fe(CN)6]3−/4− electrochemistry. Finally, platinum was electro reduced onto the GC and graphene modified GC based electrodes for use in methanol oxidation. The catalytic activities of graphene-supported Pt nanoparticles and Pt-GC electrocatalysts for methanol oxidation were 1900 and 915.5 A g−1 Pt, which can reveal the particular properties of the exfoliated graphene supports. 相似文献
174.
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176.
针对传统日志模板挖掘时需要日志聚类数目作为先验信息的问题,提出了一种基于归一化特征判别的日志模板挖掘算法.首先,对日志数据进行压缩,以提高后续处理效率;其次,进行日志聚类过程,使用归一化的日志统计特征判断聚类是否满足要求,若满足,则聚类成功;若不满足,则采用二分搜索的方式调整日志聚类的数目,重新进行聚类;最后,从聚类结果中提取日志模板,设计了一种衡量模板挖掘效果的评价指标.在真实数据集上的实验结果表明,算法的模板挖掘匹配度优于基准方法,并且具有良好的泛化性能. 相似文献
177.
为研究现浇混凝土填充外墙对剪力墙结构抗震性能的影响,完成了10个采用不同做法和不同形式填充墙的足尺墙体试件和2个无填充墙对比试件的拟静力试验。结果表明:填充墙与主体结构之间采用聚苯板条分隔做法和PVC板条分隔做法时,填充墙对主体结构的影响基本一致,均一定程度上改变了主体结构破坏过程及最终破坏形态,对于PVC板条分隔做法的试件,其破坏时的延性好于聚苯板条分隔做法的试件;填充墙增大了试件的承载能力,对于聚苯板条分隔做法的试件,其峰值荷载为无填充墙试件的1.37~3.31倍,两种做法填充墙试件的峰值荷载大小相当;填充墙减小了试件的变形能力,对于极限位移角,聚苯板条分隔做法的试件为无填充墙试件的20%~65%,PVC板条分隔做法的试件的变形能力明显大于聚苯板条分隔做法的试件;除聚苯板条分隔做法的结构洞墙试件外,其余试件的极限位移角均满足剪力墙结构抗震变形能力要求;填充墙显著增大了试件弹性及弹塑性阶段的刚度。基于试验结果,建议结构计算时合理考虑填充墙的不利影响,工程中尽量避免采用结构洞填充墙,对填充墙部位的结构构件及填充墙采取一定的加强措施。 相似文献
178.
从UPS工作原理入手,分析单相UPS和三相UPS“另起的系统”的接地问题,结论:UPS输出端的中性线做重复接地的规定有误。 相似文献
179.
Ning Han Fengyun Wang Zaixing Yang SenPo Yip Guofa Dong Hao Lin Ming Fang TakFu Hung Johnny C Ho 《Nanoscale research letters》2014,9(1):347
Growing Ga2O3 dielectric materials at a moderately low temperature is important for the further development of high-mobility III-V semiconductor-based nanoelectronics. Here, β-Ga2O3 nanowires are successfully synthesized at a relatively low temperature of 610°C by solid-source chemical vapor deposition employing GaAs powders as the source material, which is in a distinct contrast to the typical synthesis temperature of above 1,000°C as reported by other methods. In this work, the prepared β-Ga2O3 nanowires are mainly composed of Ga and O elements with an atomic ratio of approximately 2:3. Importantly, they are highly crystalline in the monoclinic structure with varied growth orientations in low-index planes. The bandgap of the β-Ga2O3 nanowires is determined to be 251 nm (approximately 4.94 eV), in good accordance with the literature. Also, electrical characterization reveals that the individual nanowire has a resistivity of up to 8.5 × 107 Ω cm, when fabricated in the configuration of parallel arrays, further indicating the promise of growing these highly insulating Ga2O3 materials in this III-V nanowire-compatible growth condition.
PACS
77.55.D; 61.46.Km; 78.40.Fy 相似文献180.
The microstructural evolution of high nitrogen austenitic stainless steel under various deformation conditions was characterized by isothermal compression test. Special attention was paid to the variation of microhardness and its relationship with grain size was also derived. Results indicated that two kinds of strengthening mechanism acted during the whole temperature range. When the temperature is between 950 °C and 1150 °C, grain refinement plays a dominant role. But at temperatures lower than 900 °C, no recrystallization occurs and substructure (dislocations and twins) contributes massively to the strength. Furthermore, it was found that the peak precipitation of grain boundary carbides which are seriously detrimental to toughness appeared at 850 °C. Therefore, an optimizing processing route could be recommended to achieve a good combination of high strength and good toughness. Firstly, the hot-rolling at 950–1100 °C should have large stain to gain refined grains, and accelerated cooling is applied from 950 to 750 °C in order to avoid carbide precipitation along grain boundary. Lastly, at temperatures lower than 750 °C warm-rolling with medium stain can get substructure strengthening effects. 相似文献