Inertial navigation based on micro-electromechanical system (MEMS) inertial measurement units (IMUs) has attracted numerous researchers due to its high reliability and independence. The heading estimation, as one of the most important parts of inertial navigation, has been a research focus in this field. Heading estimation using magnetometers is perturbed by magnetic disturbances, such as indoor concrete structures and electronic equipment. The MEMS gyroscope is also used for heading estimation. However, the accuracy of gyroscope is unreliable with time. In this paper, a wearable multi-sensor system has been designed to obtain the high-accuracy indoor heading estimation, according to a quaternion-based unscented Kalman filter (UKF) algorithm. The proposed multi-sensor system including one three-axis accelerometer, three single-axis gyroscopes, one three-axis magnetometer and one microprocessor minimizes the size and cost. The wearable multi-sensor system was fixed on waist of pedestrian and the quadrotor unmanned aerial vehicle (UAV) for heading estimation experiments in our college building. The results show that the mean heading estimation errors are less 10° and 5° to multi-sensor system fixed on waist of pedestrian and the quadrotor UAV, respectively, compared to the reference path.

ZnO nanospikes, due to their novel properties, are promising components in a wide range of nanoscale devices for future applications. Herein, current research activities are focused on the synthesis, characterization and applications of ZnO nanostructures encapsulated by a hydrogen bonded liquid crystal matrix (HBLC e.g. azelaic acid and heptyloxy benzoic acid) in optical switching. We briefly describe the smartest applied methodologies for the synthesis of ZnO nanostructures and smooth dispersion within the liquid crystalline optical materials. In fact, HBLC doping was recently found to significantly influence the nucleation and growth of many functional nanocrystals (NCs), and provide a fundamental approach to modify the crystallographic phase, size, morphology, and electronic configuration of nanomaterials. All the homologues of the present series show rich mesomorphism, exhibiting orthogonal and tilted phases. A range of remarkable characteristics is then presented, organized into sections describing the optical, electrical and electro-optical phase transitions and DC bi-stable switching properties. The other display parameters such as spontaneous polarization, rotational viscosity, switching response, capacitance, dielectric permittivity, dielectric loss spectra and low frequency relaxation (Goldstone mode) are also investigated for these nanospike–HBLC composites, and support the observations described in this article. Moreover, polarizing optical microscopy reveals various phases with different textural appearances, which proves the influence of the nanomaterial. Most observed phenomena are discussed in terms of a new smectic ordering, named smectic X*, which is sandwiched between traditional nematic and convectional smectic C* phases. Dielectric relaxations in the smectic C* phases of pure and doped LCs have been analyzed. In this feature article, we provide an overview of the most recent progresses in HBLC (AC + 7BAO) doping-induced control of efficient switching, as well as the high performances of novel functional nanomaterials, for the first time. These investigations are developing versatile applications of opto-electronic and high resolution liquid crystal devices.

For nearly five years, the photoelectric conversion efficiency of the perovskite-based solar cells are extraordinarily developed at a high speed, showing a good application prospect. It is necessary to further optimize the devices and make them industrially feasible. The different temperature requirements of perovskite solar cells during the preparation process will result in undesirable thermal stresses. There have already existed a number of papers concerning methods to improve power conversion efficiency of perovskite-based solar cell. However, the thermal properties of laminated structure of solar cell, which significantly affect the long-time reliability of solar cell packaging, have rarely been discussed. Different temperature loads in preparation process are taken into account to obtain the resulting thermal stresses in this paper. The fabrication processing is reproduced in FEM simulations which are able to directly analyze the internal stresses within and between solar cell layers. The goal is to develop a systematic understanding of thermal behavior of perovskite solar cell during the fabrication process. The study figures out that the maximum Mises stresses are located in central area for the upper layers. But the maximum stress on the bottom layer occurs at the fringe of the etching groove. The large accumulated plastic strain at the center will cause a crack initiation at this location and then the crack may continue to grow to the etching groove or even cause delamination. Due to the mismatch of the coefficient of thermal expansion, warpage is evident for alumina film and molybdenum oxide film, which had a bad influence on the uniformity of the following encapsulation process. It is meaningful to provide a reference for the continuous improvement of efficiency. The encapsulation of perovskite-based solar cells also will be discussed to reduce the resulting internal loads to a minimum value.