There are many demands for the cooperative localization (CL) of multiple people, such as firefighter rescue. The classical foot-mounted inertial navigation based on zero velocity update (ZUPT) suffers from accumulating error due to the low-cost inertial sensor, and the pre-placed anchors in the ultra-wideband (UWB) system limit the application in an unknown environment. In this study, a group of sensors including the inertial measurement unit (IMU), magnetometer, barometer, and UWB sensor is used. Through the different characteristics of sensors and the position relationship between people, a cooperative localization system using an extended Kalman filter for three-dimensional firefighter tracking is proposed. Ranging information between firefighters from UWB is utilized, and couplings introduced by relative measurement are estimated. Two experiments are designed to verify the proposed algorithm in building and forest environments. Compared with the results of single-person inertial navigation, the average positioning precision of the algorithm in the building and forest is, respectively, improved by 38.93% and 79.01%. This approach successfully suppresses the divergence of positioning errors, and fixed UWB anchors are not needed.

With the complexity and diversification of rocket launch tasks, more stringent requirements are put forward for MEMS electronic equipment, which is closely related to the stability and security of rocket. The key components of the rocket-borne electronic system are composed of discrete components, integrated components and corresponding connected fixed components. The selection, welding and board level connection of each electronic element determine the reliability of the MEMS component. In this paper, the fault tree analysis method is applied to the reliability analysis of the rocket-borne recorder, and the dynamic fault tree analysis method is introduced to compensate the deficiency of the traditional static fault tree analysis method, finally the simulation comparison with Monte-Carlo analysis method is carried out to verify the effectiveness and feasibility of the proposed method. The work of this paper is of great significance for establishing the reliability theory of the system and mastering the experience of quick failure diagnosis.

Breeze energy is a widely distributed renewable energy source in the natural world, but its efficient exploitation is very difficult. The conventional harvester with fixed arm length (HFA) has a relatively high start-up wind speed owing to its high and constant rotational inertia. Therefore, this paper proposes a harvester with a helix s-type vertical axis (HSVA) for achieving random energy capture in the natural breeze environment. The HSVA is constructed with two semi-circular buckets driven by the difference of the drag exerted, and the wind energy is transferred into mechanical energy. Firstly, as the wind speed changes, the HSVA harvester can match the random breeze to obtain highly efficient power. Compared with the HFA harvester, the power coefficient is significantly improved from 0.15 to 0.2 without additional equipment. Furthermore, it has more time for energy attenuation as the wind speeds dropped from strong to moderate. Moreover, the starting torque is also better than that of HFA harvester. Experiments showed that the HSVA harvester can improve power performance on the grounds of the wind speed ranging in 0.8–10.1 m/s, and that the star-up wind speed is 0.8 m/s and output peak power can reach 17.1 mW. In comparison with the HFA harvester, the HSVA harvester can obtain higher efficient power, requires lower startup speed and keeps energy longer under the same time. Additionally, as a distributed energy source, the HSVA harvester can provide a self-generating power supply to electronic sensors for monitoring the surrounding environment.

The torsional characteristics and the suspension control of test sample in the electrostatic levitation field are investigated in this article. Firstly, the model of coulombic force generated by the high voltage electrode is established, and the electric image force in electrostatic levitation field is detailly established. Furthermore, the suspension characteristics of test sample in vertical and horizontal axes are studied, and torsional characteristics of test sample around horizontal axes are investigated. Moreover, the control model of test sample in the electrostatic levitation field is designed to control the torsional vibration. The numerical simulations about force characteristics of electrostatic levitation field are developed, and the voltage-force coefficient of coulombic force is obtained. Finally, the experiments are conducted to analyze the suspension and torsion characteristics of test sample with coulombic force and electric image force, and the suspension and torsional stability of test sample are affected by the control voltage and the displacement deflection, and the tunable coulombic force could push the test sample back to the equilibrium position.

With the development of switching power supply in the direction of high efficiency, high integration, miniaturization and intelligence, LLC resonant converter has been widely used for its advantages of low loss and high efficiency. As an indispensable part in the design, the circuit board is responsible for the dual connection of the electrical part and the mechanical part of the LLC resonant converter. With the increasing of integration and distribution density of components, the EMC problem becomes more and more serious. In this paper, LLC resonant converter PCB is taken as an example to guide the selection and layout of active components based on field-circuit combination method, and the signal integrity of the system is analyzed. Finally, an experimental platform is built to verify the feasibility and effectiveness of the proposed method.