⋅A p-adaptive discontinuous Galerkin time-domain method is developed to obtain high-order solutions to electromagnetic scattering problems. A novel feature of the proposed method is the use of divergence error to drive the p-adaptive method. The nature of divergence error is explored, and that it is a direct consequence of the act of discretization is established. Its relation with relative truncation error is formed which enables the use of divergence error as an inexpensive proxy to truncation error. Divergence error is used as an indicator to dynamically identify and assign spatial operators of varying accuracy to substantial regions in the computational domain. This results in a reduced computational cost compared to a comparable discontinuous Galerkin time-domain solution using uniform degree piecewise polynomial bases throughout. Numerical results are presented to show performance of the proposed divergence error based p-adaptive solutions. It is shown that an accuracy similar to that of uniformly higher order solutions is obtained in terms of the scattering width, using fewer degrees of freedom. ....

In order to solve the problems of high THD (total harmonic distortion) of air-gap magnetic density, large cogging torque and low power density of permanent magnet (PM) hub motor, a built-in tangential and radial PM combined-pole hub motor is proposed in this paper. The magnetic field provided by tangential PM is the main magnetic field, and the magnetic field provided by radial PM plays an auxiliary role in regulation, which can effectively improve the air-gap magnetic density of the motor, reduce the THD of back electromotive force (EMF), and weaken the peak value of cogging torque. Based on the equivalent magnetic circuit method, this paper analyzes the magnetic circuit of the motor, deduces the leakage magnetic flux coefficient, and reduces the leakage magnetic flux by optimizing the structure of the motor. Finally, the prototype is manufactured and tested to verify the effectiveness of finite element analysis. The results show that the designed PM hub drive motor has low THD of back EMF and good sinusoidality of waveform under no-load condition, and good output performance.....

Benefit from the high resolution, penetrating and all weather advantages of millimeter-wave (MMW) imaging, MMW imaging plays an important role in remote sensing, security inspection, navigation, etc. Among the MMW imaging systems, synthetic aperture imaging radiometer (SAIR) utilizes aperture synthetic technology to achieve higher imaging resolution, but the perception information is insufficient, resulting in poor image quality. In order to improve the image quality of passive SAIR MMW image effectively, we propose a novel multichannel depth convolutional neural network (MDCNN) in this paper. Aiming at the characteristics of original MMW images with more noise in low-frequency information and less features in high-frequency information, wavelet transform is incorporated into the MDCNN to obtain the high and low frequency components firstly. Then, dense residual block and skip connection technology are adopted to denoise and enhance target information in the four independent channels respectively. Finally, high quality MMW images are synthesized by inverse wavelet transform. The simulation results show that the reconstructed images of MDCNN have better image quality (such as image contour and texture details) than other deep learning-based methods.....

In this paper, a novel flexible antenna for the new ISM band is proposed. A multi-objective optimization based on DDEA-SE is performed to optimize the antenna bandwidth and gain. The proposed optimized antenna has a 4 dB maximum realized gain and 50% maximum radiation efficiency on the ISM band. A fractal structure is used in this design to achieve a multi-band antenna. The bandwidth of this antenna covers several 5G bands. This multi-band antenna is fabricated on a cotton substrate. This antenna has a small dimension which makes it suitable for 5G applications. The bending tests are performed, and both simulation and measurement results show the good performance of the proposed antenna.....