The threshold dynamics method developed by Merriman, Bence and Osher (MBO) is an efficient method for simulating the motion by mean curvature flow when the interface is away from the solid boundary. Direct generalization of MBO-type methods to the wetting problem with interfaces intersecting the solid boundary is not easy because solving the heat equation in a general domain with a wetting boundary condition is not as efficient as it is with the original MBO method. The dynamics of the contact point also follows a different law compared with the dynamics of the interface away from the boundary. In this paper, we develop an efficient volume preserving threshold dynamics method for simulating wetting on rough surfaces. This method is based on minimization of the weighted surface area functional over an extended domain that includes the solid phase. The method is simple, stable with O(N log N ) complexity per time step and is not sensitive to the inhomogeneity or roughness of the solid boundary.

Objective: To prevent and control public health emergencies, we set up a prescreening and triage workflow and analyzed the effects on coronavirus disease 2019 .

Machine to machine (M2M) communications, also called machine-type communications (MTC), has widely been utilized in applications such as telemetry, industrial, automation, and SCADA systems. The group-based MTC, especially when MTC devices belong to non-3GPP network, will face new challenge of access authentication. In this paper, we propose a group authentication and key agreement protocol, called EG-AKA, for machine-type communications combining elliptic curve Diffie-Hellman (ECDH) based on EAP framework. Compared with conventional EAP-AKA, our protocol guarantees stronger security and provides better performance. Detailed security analysis has shown that the proposed EG-AKA protocol is secure in terms of user and group identity protection and resistance to several attacks. Furthermore, formal verification implemented in AVISPA proves that the proposed protocol is secure against various malicious attacks. Moreover, performance evaluation demonstrates its efficiency in terms of the signaling overhead, the bandwidth consumption, and the transmission cost.

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A dynamic wetting problem is studied for a moving thin fiber inserted in fluid and with a chemically inhomogeneous surface. A reduced model is derived for contact angle hysteresis by using the Onsager principle as an approximation tool. The model is simple and captures the essential dynamics of the contact angle. From this model, we derive an upper bound of the advancing contact angle and a lower bound of the receding angle, which are verified by numerical simulations. The results are consistent with the quasi-static results. The model can also be used to understand the asymmetric dependence of the advancing and receding contact angles on the fiber velocity, which was observed recently in the physical experiments reported in the work of Guan et al. [“Asymmetric and speed-dependent capillary force hysteresis and relaxation of a suddenly stopped moving contact line,” Phys. Rev. Lett. 116, 066102 (2016)].