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Frequency splitting, a phenomenon causing transfer efficiency decreasing in wireless power transfer (WPT) systems when the coupling strength is too strong, can be suppressed by combining the magnetic and the electric couplings with out-of-phase polarities to constitute a hybrid WPT (HWPT) structure. In this article, the exact critical coupling coefficient of the HWPT structure is obtained from the ridge equation of the analytical efficiency expression. It is found to approximate 1/ $Q$ ( $Q$ is the loaded quality factor of the resonators), which shows a similar property with the conventional inductively coupled WPT (IPT) system. In order to improve the efficiency after the critical coupling distance, the magnetic coupling only or the in-phase structures are proposed and realized by rotating the transmitter and adjusting the values of the electric coupling. In addition, for the applications requiring high efficiency over a long transfer distance, a design procedure of the resonator is given with the help of the analytical relationships between the electric parameters and geometrical parameters of the coupling structures. The electromagnetic simulations (ANSYS HFSS) and experiments show good agreement with the theory. The efficiency can hold above 70% within 40–260-mm transfer distance. Compared with the existing HWPT system, the operating distance range is extended from 130 to 220 mm, featuring an $\sim $ 69% improvement.

Nonferromagnetic metal materials are widely used in industry. Defects generated during manufacture and use may lead to serious accidents. The defect reconstruction is important for nondestructive evaluation. Eddy current pulsed thermography (ECPT) is a well-known nondestructive testing and evaluation method, but hardly reconstruct fully defect profile. Electrical impedance tomography (EIT) shows promising potential in defect profile reconstruction, but suffers from electrode number limitation. In this article, EIT is introduced to ECPT image sequences processing, and a new method, induced current thermo-electrical impedance tomography, is developed. The proposed method takes each infrared camera pixel as a virtual electrode, captures the electric current distribution with spatial resolution as high as camera, and reconstructs conductivity distribution at pixel level from which the defect profile can be identified. Experiments with different defects are carried out to verify the performance of the proposed method.

A new distributed filtering problem is fully studied in this article for time-varying systems over sensor networks under measurement errors and measurement censoring, where the measurement error is modeled as stochastic sensor bias driven by a dynamical equation and the measurement censoring is described by the Tobit measurement model. To reduce data congestion and transmission burden, a weighted try-once-discard protocol (WTODP) is applied to transmission channels to efficiently orchestrate data communication. The transmission priority is determined in a dynamical way depending on the importance of missions. The aim of this article is to construct an optimal distributed Tobit Kalman filter (TKF) such that filter parameters are rigorously determined in the minimum mean squared error sense under the consideration of the bias, censoring and WTODP effects. Specifically, sparsity of the network topology is comprehensively considered by using the novel matrix simplification technique. Furthermore, the resultant filtering error is ensured to be exponentially bounded in the mean squared sense. Finally, an illustrative example is used to show the applicability of the proposed filter.

Signed networks are widely applied to describe cooperative and competitive interaction relationships arising from various social, biological, and physical systems. In this article, a cooperation–competition evolutionary dynamic model is offered to explain the gradual evolution of the interaction relationship between neighboring nodes in signed networks. The core feature of our model is to portray the interaction relationship between neighboring nodes as a nonlinear function of the state difference, i.e., neighboring nodes cooperate with each other only if their state difference is within a limited range (called cooperation range); otherwise, they antagonize with each other. We investigate the leader–follower dynamics, and present the lower bound of the convergence rate by using the infinity norm of products of substochastic matrices. For the leaderless dynamics, we establish algebraic conditions with respect to the state differences and the cooperation range for realizing consensus and polarization behaviors. Finally, numerical examples are provided to illustrate the evolution dynamics.

In social networks with mixed trust and distrust relationships, polarization is a common class of opinion evolutionary phenomena. Existing studies have generally believed that structural balance on networks is a crucial condition for the emergence of opinion polarization under DeGroot-style interactions. Unlike existing studies, this article aims to establish a new updating model based on DeGroot-style interactions, thereby relaxing the network structure requirement of achieving opinion polarization to quasi-structural balance, which is a more general concept and can include structural balance as a special case. With the assistance of the method of products convergence of infinite super-stochastic matrices, a comprehensive analysis of the model is carried out, and algebraic conditions on the degrees of trust and distrust among agents are established, so as to ensure the realization of opinion polarization on quasi-structurally balanced networks. At last, numerical simulations are provided to verify the theoretical results.

The silicon carbide (SiC) power module is one of the most popular semiconductor devices in industrial applications with the enhanced current rating. In this paper, a 1200-V/200-A SiC three-level (3L) module with neutral point clamped (NPC) topology is designed and validated. Compared with other existing works, the drain current of the designed module is accurately measured by a custom-made current transformer (CT) combined with a commercially off-the-shelf current probe (CP), which is critical for power loss evaluation. Based on the simulation and experiment results, it can be found that the maximum internal commutation loop stray inductance is no more than 40 nH, and the total switching loss can be reduced more than 30${\%}$ compared with the hybrid 3L NPC module (Si IGBTs+SiC SBDs). Meanwhile, the power loss evaluation demonstrates that the designed 3L NPC module with all-SiC device is more suitable for high-voltage and high-frequency applications compared with its 2L counterpart, and the thermal simulation shows that the maximum junction temperature is less than 120 $^{\circ }$C when the module operates as a buck converter with $V_{DC}$ = 600 V, $I_{o}$ = 150 A, and $f_{s}$ = 100 kHz. In addition, compared with the 2L module, the 3L one presents enhanced spectrum amplitude in the high frequency (HF) range ($\ge$ 10 MHz) for the high-voltage applications, which indicates higher electromagnetic interference (EMI) noise. Then, two types of snubber circuits are used to suppress the HF oscillation of the SiC 3L NPC module and alleviate the EMI noise as well according to the experiment results.