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Gas diffusion plays a key role in CO 2-enhanced recovery of coal bed methane (ECBM), where more than one types of gases coexist and multicomponent gas diffusion occurs. Such process is now usually described by non-coupled two-component gas diffusion equations which exclude the interactions between gases. Self-diffusion and mutual diffusion of CO 2-CH 4 mixture are investigated through molecular simulation for the first time. The self-diffusion coefficients of CO 2 and CH 4 decrease with gas concentration but increase with temperature. The mutual diffusion coefficients of binary gas mixture of CO 2-CH 4 in coal are computed through Maxwell-Stefan diffusion theory. A 2D diffusivity matrix |D| (with diagonal element D i and non-diagonal element D ij) is obtained to depict the mutual diffusion of the gas mixture. It is found that CO 2 (CH 4) diffusion is coupled with CH 4 (CO 2). The diffusion coupling strength of CO 2 and CH 4 decreases with increasing gas

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Abstract-Small talk is an important social lubricant that helps people, especially strangers, initiate conversations and make friends with each other in physical proximity. However, due to difficulties in quickly identifying significant topics of common interest, real-world small talk tends to be superficial. The mass popularity of mobile phones can help improve the effectiveness of small talk. In this paper, we present E-SmallTalker, a distributed mobile communications system that facilitates social networking in physical proximity. It automatically discovers and suggests topics such as common interests for more significant conversations. We build on Bluetooth Service Discovery Protocol (SDP) to exchange potential topics by customizing service attributes to publish nonservice-related information without establishing a connection. We propose a novel iterative Bloom filter (IBF) protocol that encodes topics to fit in SDP attributes and achieves a low false positive rate. We have implemented the system in Java ME for ease of deployment. Our experiments on real-world phones show that it is efficient enough at the system level to facilitate social interactions among strangers in physical proximity. To the best of our knowledge, E-SmallTalker is the first distributed mobile system to achieve the same purpose.

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