排序方式: 共有37条查询结果,搜索用时 156 毫秒
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目前还没有一种被广泛承认的理论能够解释高压过冷池沸腾换热,其机理尚不明确。为了揭示高压池内过冷核沸腾的物理传热机理,并获得气泡脱离频率与活化穴半径的函数关系,根据池内过冷核沸腾加热表面活化穴的分布,在统计方法的基础上,提出了高压池内过冷核沸腾的一个数学模型。从该模型中发现,池内过冷核沸腾热流密度是壁面过热度、液体过冷度、活化穴尺寸、流体的接触角以及流体物理特性的函数。对不同的过冷度,将模型预测的结果与实验数据进行了比较,两者吻合得极好,从而证明了数学模型的可靠性。该解析模型更深刻地揭示了过冷池沸腾换热的物理机理,且没有增加新的经验常数。 相似文献
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Epidemic propagation on adaptive coevolutionary networks with preferential local-world reconnecting strategy 下载免费PDF全文
In the propagation of an epidemic in a population, individuals adaptively adjust their behavior to avoid the risk of an epidemic. Differently from existing studies where new links are established randomly, a local link is established preferentially in this paper. We propose a new preferentially reconnecting edge strategy depending on spatial distance (PR- SD). For the PR-SD strategy, the new link is established at random with probability p and in a shortest distance with the probability 1 p. We establish the epidemic model on an adaptive network using Cellular Automata, and demonstrate the effectiveness of the proposed model by numerical simulations. The results show that the smaller the value of parameter p, the more difficult the epidemic spread is. The PR-SD strategy breaks long-range links and establishes as many short-range links as possible, which causes the network efficiency to decrease quickly and the propagation of the epidemic is restrained effectively. 相似文献
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考虑在纳米流体中纳米颗粒做布朗运动引起的对流换热, 基于纳米颗粒在纳米流体中遵循分形分布, 本文得到纳米流体对流换热的机理模型. 本解析模型没有增加新的经验常数, 从该模型发现纳米流体池沸腾热流密度是温度、纳米颗粒的平均直径、 纳米颗粒的浓度、纳米颗粒的分形维数、沸腾表面活化穴的分形维数、基本液体的物理特性的函数. 对不同的纳米颗粒浓度和不同的纳米颗粒平均直径与不同的实验数据进行了比较, 模型预测的结果与实验结果相吻合. 所得的解析模型可以更深刻地揭示纳米流体对流换热的物理机理. 相似文献
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In this paper, we study the epidemic spreading in scale-free networks and propose a new susceptible-infected- recovered (SIR) model that includes the effect of individual vigilance. In our model, the effective spreading rate is dynamically adjusted with the time evolution at the vigilance period. Using the mean-field theory, an analytical result is derived. It shows that individual vigilance has no effect on the epidemic threshold. The numerical simulations agree well with the analytical result. Furthermore, we investigate the effect of individual vigilance on the epidemic spreading speed. It is shown that individual vigilance can slow the epidemic spreading speed effectively and delay the arrival of peak epidemic infection. 相似文献
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