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排序方式: 共有10000条查询结果,搜索用时 62 毫秒
991.
基于local-area的Internet路由级拓扑抽象算法 总被引:1,自引:0,他引:1
通过分析Internet的本地聚集特性,给出了local-area和connect-area的定义,并基于此,为提高并行网络模拟性能,提出一种新型拓扑抽象算法——基于local -area的拓扑抽象(TABLA)算法.TABLA算法在给定的聚合粒度下,迭代搜索网络内的local-area,对拓扑进行抽象.模拟结果表明在... 相似文献
992.
993.
进行保边滤波需要已知反射倾角和边界信息,通常这些信息由全频率地震资料估算得到,但噪声的存在往往会降低估算的准确性.地震资料的各个频率成分具有不同的信噪比,Morlet小波具有良好的局部性能,所以用Morlet小波可以将地震数据按照倍频程分为几个分频体.对于信噪比不是太低(一般指大于2.5 )的地震资料,会有2-3个分频体具有较高的信噪比.扫描上述分频体,确定它们的倾角以及边界信息,然后利用倾角及边界信息对上述分频体以及与其频率接近的分频体进行平滑,并根据是否存在边界采取不同的滤波手段,保证滤波算法的稳定性,最后将平滑后的各频段地震记录合成,得到去噪后的地震记录.理论模型和实际资料处理表明,对于信噪比大于2.5的地震资料,该方法能有效去除噪声. 相似文献
994.
Chen Dapeng Zhu Gang Zhu Xingong Qiao Xueliang Chen Jianguo 《Journal of Materials Science: Materials in Electronics》2011,22(12):1788-1795
Silver nanostructures have been synthesized via a simple solvothermal method by adding sodium sulfide (Na2S) into the solution. The morphologies of products are controlled by the concentration of Ag2S formed in the initial stage. A low-concentration Ag2S (12.5 ~ 50 μM) acts as the catalysis, leading to the formation of silver nanocubes with controllable sizes. However, a high-concentration
Ag2S (100 μM) mainly acts as the controlling agent. It facilitates the synthesis of silver nanowires. Reaction conditions, the
reaction temperature and the molar ratio of the repeating unit of PVP to AgNO3 (R), have also been investigated. A possible mechanism is proposed to interpret the synthesis of silver nanocubes and nanowires.
Finally, our results indicate that this strategy provides a simple route to prepare silver nanocubes with adjustable sizes. 相似文献
995.
Dapeng Chen Xueliang Qiao Xiaolin Qiu Jianguo Chen Renzhi Jiang 《Journal of Materials Science: Materials in Electronics》2011,22(1):6-13
Silver nanostructures have been synthesized through a simple solvothermal method by reducing silver nitrate (AgNO3) with ethylene glycol (EG) and using poly(vinylpyrrolidone) (PVP) as an adsorption agent. Different concentrations of ferric
chloride (FeCl3) are added into the solution. It is found that AgCl colloids formed in the initial stage greatly influence the final morphologies
of the products. When a low-concentration FeCl3 solution is used, there is a mixture of silver nanoparticles and nanowires. However, when a high-concentration FeCl3 solution (100 μM) is used, large amounts of AgCl colloids appear, resulting in decreasing free Ag+ during initial formation of silver seeds and slowly releasing of Ag+ to the solution in the subsequent reaction. This leads to the formation of silver nanowires. Furthermore, an increase in
the concentration of FeCl3 from 100 to 300 μM results in the synthesis of silver nanowires with larger sizes. In addition, Fe(III) is reduced to Fe(II)
form which in turn reacts with and removes adsorbed atomic oxygen from the surface of silver seeds. In this case, uniform
silver nanowires can be obtained. 相似文献
996.
997.
Jinshuo Qiao Kening Sun Naiqing Zhang Bing Sun Jiangrong Kong Derui Zhou 《Journal of power sources》2007
In this paper, Ni/YSZ and Ni–CeO2/YSZ anodes for a solid oxide fuel cell (SOFC) were prepared by tape casting and vacuum impregnation. By this method, the Ni content in the anode could be reduced compared to the traditional tape casting method. It was found that adding CeO2 into the Ni/YSZ anode by a Ni(NO3)2 and Ce(NO3)3 mixed impregnation could further enhance cell performance. This was investigated in H2 at 1073 K. XRD patterns indicated that CeO2 and Ni were separate phases, and the CeO2 addition could enhance the Ni dispersion on the YSZ framework surface which was observed by SEM images. It was shown that adding CeO2 into the Ni anodes could decrease the cell polarization resistance. The maximum power density for cells with 25 wt.% Ni, 5 wt.% CeO2–25 wt.% Ni/YSZ, or 10 wt.% CeO2–25 wt.% Ni/YSZ anode was 230 mW cm−2, 420 mW cm−2 and 530 mW cm−2, respectively, in H2 at 1073 K. The OCV for these cells was 1.05–1.09 V, indicating that a dense electrolyte film was obtained by co-firing porous YSZ layer and dense YSZ layer. 相似文献
998.
Xiaolu Li Xinqi Qiao Liang Zhang Junhua Fang Zhen Huang Huimin Xia 《Renewable Energy》2005,30(13):2075-2084
Though, as a renewable energy resource, alcohol fuel has many advantages in China, it is difficult for diesel engines to operate on alcohol due to its low cetane number and high latent heat of vaporization. This paper proposes an approach to its ignition problem by combining internal exhaust gas recirculation (EGR) with injection of small diesel fuel. Based on this approach, a two-stroke single-cylinder diesel engine was developed. Preliminary studies demonstrated that the engine can run on alcohol with almost zero level of smoke and low exhaust gas temperature, and that the engine operating on alcohol has lower nitrogen oxide (NOx) emissions and 2–3% higher effective thermal efficiency than that operating on diesel fuel in moderate and high load zones. 相似文献
999.
生物质半焦气化的反应动力学 总被引:11,自引:0,他引:11
利用热重分析仪研究了CO2气氛下的生物质半焦的反应性。研究发现,所研究的4种生物质半焦都表现出了相同的反应性趋势。其反应性随着转化率的增加而增加。这可能是由于生物质焦样中的碱金属含量,尤其是钾的含量较高的原因。对比生物质气化反应动力学参数研究表明,4种焦样的气化行为可以用收缩核模型来描述,并求出了4种生物质焦样的反应动力学参数。在不同的CO2分压下进行了花生壳焦样的反应性实验研究,发现焦样的反应性正比于反应气体浓度,求出了花生壳焦样的反应动力学方程式。 相似文献
1000.