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In this paper a double square loop switchable metamaterial absorber based on active frequency selective surface (AFSS) is introduced. The design of AFSS structure is comprised of periodically arranged square loops with PIN diodes. There are four states simulation results can be presented by controlling the bias voltage of the PIN diodes, and the method for the design of feeder circuits is probe-fed...
In this paper, we present a multifunctional active frequency selective surface (MAFSS), which consists of two metallic layers and a substrate layer. Three electromagnetic functions of switching, polarization selection and frequency tuning, are integrated into a single board. The bias networks are embedded in each layer and comprise the MAFSS elements themselves, which eliminates the need of extra...
In this paper, a Boost type control strategy is proposed to solve the problems of large power backflow and low conversion efficiency in dual active bridge bidirectional DC-DC converter which occur in the traditional phase-shifted control strategies. In the condition that the main topology circuit is not changed, the control strategy proposed in this paper can make the circuit work in Boost state every...
Three level neutral-point-clamped(NPC) single-phase cascaded inverter is used in advanced cophase traction power supply system. Because a lot of power modules and switches are used, reliability of this system could be decreased. To diagnose fault of cascaded inverter, different fault types of individual module are analyzed. A fault diagnostic method is proposed to diagnose open circuit fault of single-phase...
Aiming at solving the problem of low efficiency of energy transmission in bidirectional energy storage system under the condition of large voltage difference between DC bus and battery, a novel phase angle modulation control strategy based on dual active bridge DC-DC converter is proposed in this paper. Under the control strategy, the energy stored in the inductor reaches the maximum during each switching...
In this paper, we propose a multifunctional active frequency selective surface (MAFSS), which can be switched freely between the electromagnetic switching function and the polarization selection function. Thus, four different working states can be attained by controlling two external bias networks independently. Resonant structures take upon themselves the role of allowing DC currents to pass through...
A 2-bit active frequency selective surface (AFSS) is designed, fabricated and measured in this paper. This FSS structure loaded PIN diodes and biasing lines are designed carefully to realize four switchable states (2-bit): both TE polarization & TM polarization band-pass filter for code 00; TE band-pass filter or polarizer for code 01; TM band-pass filter or polarizer for code 10; both TE &...
On the background of an AC/DC hybrid microgrid on a small island, operation mode of the microgrid was divided into diesel generator power supply independently, inverter power supply independently and compositive power supply according to the cooperation of the diesel generator and the interface inverter. Switch control strategy of the microgrid operation mode was proposed in this paper based on hierarchical...
In order to reduce the impact of current and voltage effectively, when the dual-mode inverter grid-connected/off-grid mode transfer in the micro-grid system. There is a uncontrollable parameter perturbations influence in the transfer process of grid-connected/off-grid. This paper presents micro-grid dual-mode inverter which take H∞ robust controller in current inner loop, reducing external disturbances...
A power supply module using synchronous Buck circuit for ultrawide input-voltage range is proposed in this paper. In some renewable energy utilizations such as photovoltaic and geothermal power generation. The DC bus voltage of generator is substantial jump occasionally. A DC-DC power supply module which can work in the circumstance of ultra-wide input voltage range is developed, and output of module...
Cascaded H-bridge multilevel converter based active power filter can compensate high-order harmonics (17th–50th) in middle-high voltage system with relatively lower switching frequency, but at the same time, a special DC capacitor energy unbalance problem is caused. When the compensation current frequency is close to the witching frequency of the H-bridge cell, harmonic power coupling will lead to...
A reconfigurable electromagnetic shield by active frequency selective surface (AFSS) with switch function at LTE-D 4G mobile communication is proposed in this paper. Double coupled metallic meandered structures on one layer substrate loaded PIN diodes are designed carefully to realize the band-pass characteristic at 2.6GHz when PINs are OFF and the rejection characteristic when PINs are ON. The proposed...
The fast path, as the cache of exact-match rules in the slow path, is applied in software-based OpenFlow switches to improve the forwarding performance. A microflow in the fast path is the specification of its corresponding rules in the slow path, i.e., every field is explicit in a microflow. A rule can generate multiple microflows in the fast path, and a microflow can be generated from multiple rules...
CRM Boost PFC converter features zero-current turn-on for the switch and no reverse recovery in diode. However, its switching frequency varies over a wide range, which leads to the efficiency deterioration and the EMI filter design complexity. In this paper, a minimum switching frequency variation range control (MFVC) strategy is proposed by injecting the optimal 3rd harmonic into the input current...
Large-scale sensor-based Electrical Capacitance Tomography systems have a bright industrial application prospect. However, in terms of the hardware design of capacitance measuring circuits of the systems, a particular difficulty is to eliminate strong stray capacitance measuring interference produced by overlong single-shield coaxial cables and single analog switches. Therefore, in this paper different...
A new discrete switch-chaos system is proposed for generating chaotic PN sequences. Performance analysis with respect to Logistic map, Tent map and the new switch-chaos system are discussed, including the onto mapping range of the chaos system, the uniformity and pseudo-random of the sequences. An android SMS encryption system based on switch-chaos system is also designed. Experimental results show...
Several cases of unusual mal-operation of the current differential protection for transformer, generator and transmission line already in service, due to the adjacent transformer switching-on, have been reported. The complex inrush current, including the magnetizing inrush current and the sympathetic inrush current, is considered to be relevant with this sort of mal-operation. However, the detail...
Current-mode control is commonly used in buck converters. Many current-mode buck converters with variable-frequency controllers have been published for smaller inductance and maintaining efficiency via fast and slow frequency, respectively. However, bandwidth of the current-mode buck converter with fixed compensation coefficients is limited by the lowest switching frequency, thus decreases transient...
As the smartphone/cellphone market has exploded, the war on which smartphone platform will dominate has become fiercer than ever. In that vain, the goal of this paper is to answer two fundamental questions: What are the adoption trends for smartphones? And how can we estimate the demand for new smartphones? We answer these two questions by collecting a dataset of 3 million subscribers from a nationwide...
High speed routers in Internet are becoming increasingly more powerful, as well as more energy hungry. However, they always show power-inefficient property due to we unilaterally in pursuit of high speed before. In response to this problem, we present a power-efficient router architecture named GreenRouter in this paper. GreenRouter separates a line card into two parts physically: the network interface...
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