10 research outputs found
Location Fingerprint Extraction for Magnetic Field Magnitude Based Indoor Positioning
Smartphone based indoor positioning has greatly helped people in finding their positions in complex and unfamiliar buildings. One popular positioning method is by utilizing indoor magnetic field, because this feature is stable and infrastructure-free. In this method, the magnetometer embedded on the smartphone measures indoor magnetic field and queries its position. However, the environments of the magnetometer are rather harsh. This harshness mainly consists of coarse-grained hard/soft-iron calibrations and sensor electronic noise. The two kinds of interferences decrease the position distinguishability of the magnetic field. Therefore, it is important to extract location features from magnetic fields to reduce these interferences. This paper analyzes the main interference sources of the magnetometer embedded on the smartphone. In addition, we present a feature distinguishability measurement technique to evaluate the performance of different feature extraction methods. Experiments revealed that selected fingerprints will improve position distinguishability
Controlled Synthesis of Organic/Inorganic van der Waals Solid for Tunable Light-matter Interactions
Van der Waals (vdW) solids, as a new type of artificial materials that
consist of alternating layers bonded by weak interactions, have shed light on
fascinating optoelectronic device concepts. As a result, a large variety of vdW
devices have been engineered via layer-by-layer stacking of two-dimensional
materials, although shadowed by the difficulties of fabrication. Alternatively,
direct growth of vdW solids has proven as a scalable and swift way, highlighted
by the successful synthesis of graphene/h-BN and transition metal
dichalcogenides (TMDs) vertical heterostructures from controlled vapor
deposition. Here, we realize high-quality organic and inorganic vdW solids,
using methylammonium lead halide (CH3NH3PbI3) as the organic part (organic
perovskite) and 2D inorganic monolayers as counterparts. By stacking on various
2D monolayers, the vdW solids behave dramatically different in light emission.
Our studies demonstrate that h-BN monolayer is a great complement to organic
perovskite for preserving its original optical properties. As a result,
organic/h-BN vdW solid arrays are patterned for red light emitting. This work
paves the way for designing unprecedented vdW solids with great potential for a
wide spectrum of applications in optoelectronics