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Voice assistants such as Amazon Echo (Alexa) and Google Home use microphone arrays to estimate the angle of arrival (AoA) of the human voice. This paper focuses on adding user localization as a new capability to voice assistants. For any voice command, we desire Alexa to be able to localize the user inside the home. The core challenge is two-fold: (1) accurately estimating the AoAs of multipath echoes without the knowledge of the source signal, and (2) tracing back these AoAs to reverse triangulate the user's location.We develop VoLoc, a system that proposes an iterative align-and-cancel algorithm for improved multipath AoA estimation, followed by an error-minimization technique to estimate the geometry of a nearby wall reflection. The AoAs and geometric parameters of the nearby wall are then fused to reveal the user's location. Under modest assumptions, we report localization accuracy of 0.44 m across different rooms, clutter, and user/microphone locations. VoLoc runs in near real-time but needs to hear around 15 voice commands before becoming operational. 

The theoretical investigation of heat dissipation for polymer‐bonded explosives (PBXs) is in high demand in explosive design in terms of safety and realibility, particularly as lack of effective experimental measurements. Here, we investigate the fundamental understanding of thermal transport across the heterogeneous interface between HMX and PVDF, by using the diffuse mismatch model and anharmonic inelastic model. This work explores the interfacial thermal conductance viaab initiocalculation and derived phonon dispersions, phonon group velocities. For HMX‐PVDF interface, it is shown that low‐frequency phonon modes (especially lower than 10 THz) and two‐phonon elastic processes play dominant roles in the interface thermal transport. Furthermore, we present the calculated interfacial thermal conductance as a function of temperature. The thermal conductivity of mixture HMX‐PVDF system is analyzed with an effective medium approximation model. From these calculations, we give the thermal transport properties predictions of PBX for thermal conductivity enhancement and provides fundamental microscopic insights into phonon transport physics in PBX.