The state estimation strategy using the smooth variable structure filter （SVSF） is based on the variable structure and sliding mode concepts. As presented in its standard form with a fixed boundary layer limit, the ...The state estimation strategy using the smooth variable structure filter （SVSF） is based on the variable structure and sliding mode concepts. As presented in its standard form with a fixed boundary layer limit, the value of the boundary layer width is not precisely known at each step and may be selected based on a priori knowledge. The boundary layer width reflects the level of uncertainty in the model parameters and disturbance characteristics, where large values of the boundary layer width lead to robustness without optimality and small values of the boundary layer width provide optimality with poor robustness. As a solution and to overcome these limitations, an adaptive smoothing boundary layer is required to achieve greater robustness and suitable accuracy. This adapted value of the boundary layer width is obtained by minimizing the trace of the a posteriori covariance matrix. In this paper, the proposed new approach will be considered as another alternative to the extended Kalman filters （EKF）, nonlinear H∞ and standard SVSF-based data fusion techniques for the autonomous airborne navigation and self-localization problem. This alternative is based on strapdown inertial navigation system （SINS） and GPS data using the nonlinear SVSF with a covariance derivation and adaptive boundary layer width. Furthermore, the full mathematical model of the SINS/GPS navigation system considering the unmanned aerial vehicle （UAV） position, velocity and Euler angle as well as gyro and accelerometer biases will be used in this paper to estimate the airborne position and velocity with better accuracy.展开更多
Use of a flexible thermoelectric source is a feasible approach to realizing selfpowered wearable electronics and the Internet of Things.Inorganic thin films are promising candidates for fabricating flexible power supp...Use of a flexible thermoelectric source is a feasible approach to realizing selfpowered wearable electronics and the Internet of Things.Inorganic thin films are promising candidates for fabricating flexible power supply,but obtaining highthermoelectric‐performance thin films remains a big challenge.In the present work,a p‐type Bi_(x)Sb_(2−x)Te_(3) thin film is designed with a high figure of merit of 1.11 at 393 K and exceptional flexibility(less than 5%increase in resistance after 1000 cycles of bending at a radius of∼5 mm).The favorable comprehensive performance of the Bi_(x)Sb_(2−x)Te_(3) flexible thin film is due to its excellent crystallinity,optimized carrier concentration,and low elastic modulus,which have been verified by experiments and theoretical calculations.Further,a flexible device is fabricated using the prepared p‐type Bi_(x)Sb_(2−x)Te_(3) and n‐type Ag_(2)Se thin films.Consequently,an outstanding power density of∼1028μWcm^(−2)is achieved at a temperature difference of 25 K.This work extends a novel concept to the fabrication of highperformance flexible thin films and devices for wearable energy harvesting.展开更多
基金supported by the National Natural Science Foundation of China(No.61375082)
文摘The state estimation strategy using the smooth variable structure filter （SVSF） is based on the variable structure and sliding mode concepts. As presented in its standard form with a fixed boundary layer limit, the value of the boundary layer width is not precisely known at each step and may be selected based on a priori knowledge. The boundary layer width reflects the level of uncertainty in the model parameters and disturbance characteristics, where large values of the boundary layer width lead to robustness without optimality and small values of the boundary layer width provide optimality with poor robustness. As a solution and to overcome these limitations, an adaptive smoothing boundary layer is required to achieve greater robustness and suitable accuracy. This adapted value of the boundary layer width is obtained by minimizing the trace of the a posteriori covariance matrix. In this paper, the proposed new approach will be considered as another alternative to the extended Kalman filters （EKF）, nonlinear H∞ and standard SVSF-based data fusion techniques for the autonomous airborne navigation and self-localization problem. This alternative is based on strapdown inertial navigation system （SINS） and GPS data using the nonlinear SVSF with a covariance derivation and adaptive boundary layer width. Furthermore, the full mathematical model of the SINS/GPS navigation system considering the unmanned aerial vehicle （UAV） position, velocity and Euler angle as well as gyro and accelerometer biases will be used in this paper to estimate the airborne position and velocity with better accuracy.
基金National Natural Science Foundation of China,Grant/Award Number:62274112Guangdong Basic and Applied Basic Research Foundation,Grant/Award Number:2022A1515010929Science and Technology Plan project of Shenzhen,Grant/Award Numbers:JCYJ20220531103601003,20220810154601001。
文摘Use of a flexible thermoelectric source is a feasible approach to realizing selfpowered wearable electronics and the Internet of Things.Inorganic thin films are promising candidates for fabricating flexible power supply,but obtaining highthermoelectric‐performance thin films remains a big challenge.In the present work,a p‐type Bi_(x)Sb_(2−x)Te_(3) thin film is designed with a high figure of merit of 1.11 at 393 K and exceptional flexibility(less than 5%increase in resistance after 1000 cycles of bending at a radius of∼5 mm).The favorable comprehensive performance of the Bi_(x)Sb_(2−x)Te_(3) flexible thin film is due to its excellent crystallinity,optimized carrier concentration,and low elastic modulus,which have been verified by experiments and theoretical calculations.Further,a flexible device is fabricated using the prepared p‐type Bi_(x)Sb_(2−x)Te_(3) and n‐type Ag_(2)Se thin films.Consequently,an outstanding power density of∼1028μWcm^(−2)is achieved at a temperature difference of 25 K.This work extends a novel concept to the fabrication of highperformance flexible thin films and devices for wearable energy harvesting.
