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SiC JFET bi-directional switches (BDS) are widely used in construction of matrix converters, multi-level converters, solid state switches, etc. In this research work, the phenomenon of unwanted turn-on (UTO) of SiC JFET-based BDS and its related constant envelop oscillation is investigated. This phenomenon is critical to power conversion systems' stability and reliability. Firstly, the roots of UTO...
In order to make the ejector refrigeration system reach subzero refrigeration, the ejector structure is optimized in this paper. A two-stage ejector model in series with two ejectors is proposed. Comparing with traditional single ejector models, the two-stage ejector carries out a two boost of the secondary flow by connecting two ejectors in series. Using a water cooled condenser can also reduce the...
In order to improve the breaking capacity of contacts, it is very important to find a better contact material. In this paper, the triggering experiments of plate contact with different material are studied to investigate the characteristics of vacuum arc. The current range is from 1kA to 9kA (rms). The gap distance is 3mm and 5mm. The arc appearance and the behavior of cathode spots are captured by...
Internet connection is essential for daily life, however not all areas are covered by Internet access due to historical reasons. For example, with 3.7 million daily passengers, London underground system has no WiFi or cellular signal provided during travelling due to legacy reasons. Deploy new access infrastructure need to consider the integrating problem with the current environment, also bring a...
Using magnetic fields to control the vacuum arc is a major way to improve the breaking capacity of vacuum interrupters. Besides the single transverse magnetic field (TMF) and single axial magnetic field (AMF), new type of TMF-AMF contact structure has been put forward to control the vacuum arc in recent years. In this paper, two different structure contacts are used in experiments. The arc evolution...
In order to reduce imaging time of complex targets in a large scene, an efficient strip-mode microwave correlated imaging method with data fusion is proposed. Due to its rangegate feature, while random radiation radar array transmits narrow-pulse random signals synchronously, the whole imaging area can be divided into multiple imaging strips in the range direction. By analyzing the temporal-spatial...
A fast correlated imaging method based on strip division in large scenes is proposed. By transmitting narrow-pulse random signals synchronously from random radiation radar array, the whole imaging area is divided into multiple strips in range direction, then correlated imaging model in strip mode is established, which reduces the scale of its imaging matrix equation greatly; By multi-strip stitching,...
The industry's first 10nm low power high performance mobile SoC has been successfully ramped in production. Thanks to a thorough design-technology co-development, 10nm SoC is 16% faster, 37% smaller, and 30% lower power than its 14nm predecessor. The latest SoC features a gigabit class modem and is set to advance AR/VR, AJ, machine learning, and computing. 10nm FinFet technology scaling challenges...
As a distributed system, Hadoop heavily relies on the network to complete data processing jobs. While Hadoop traffic is perceived to be critical for job execution performance, the actual behaviour of Hadoop network traffic is still poorly understood. This lack of understanding greatly complicates research relying on Hadoop workloads. In this paper, we explore Hadoop traffic through experimentation...
This study presents electrical and optical performances of textured silicon solar cell improved by plasmonic-scattering and luminescent-down-shifting effects. The cell with the proposed effects demonstrated a 1.79 % absolute-gain in efficiency compared with a reference-cell.
This study reports photovoltaic performance of MOS-structure Si solar cells enhanced by the combination of antireflection, biasing, and plasmonic scattering effects. The absolute gain in efficiency by 4.66% was obtained, compared with the reference cells.
To reveal the detailed correlation between the controllability of structure parameters in fabrication process and the homogeneity of device performance of single photon avalanche diodes (SPADs), simulations on multi-parameter fluctuations are carried out. We find that, for typical InGaAsP/InP SPADs, significant fluctuation of structure parameters cause asymmetry distribution of the dark count rate...
In order to enhance the temporal-spatial stochastic characteristics of stochastic radiation fields, a new microwave staring correlated imaging method based on random linear frequency modulation with different rates is proposed, where microwave pulse signals emitted by different elements of stochastic radiation radar array have the same pulse periods and repetition frequencies, however, each pulse...
In this paper, a 3D model for vacuum arc controlled by transverse magnetic field (TMF) is built and simulation on its parameters is calculated. In the simulation, only the external TMF is taken into consideration and arc is assumed to contracts itself. Arc is not neutral so that ions and electrons are calculated respectively. According to the simulation results, both ions and electrons are deflected...
Vacuum arc consists of cathode spot and mixing zone, arc column and anode zone. The separate jets and the mixing zone should be considered in the model of vacuum arc, especially the diffuse arc. In this paper, mixing and interaction of multi-cathode spot vacuum arc jets were studied through simulation. To investigate the mixing and interaction of vacuum arc jets a steady 3D Magneto-Hydro-Dynamic (MHD)...
A series of triggering experiments were carried out to investigate into the characteristics of vacuum arc controlled by TMF-AMF contacts. During the whole experiments, current ranged from 5kA to 20kA (rms) and both arc appearance and the behavior of cathode spots were captured by high-speed camera with corresponding arc current and arc voltage. A 3D steady MHD model was built to simulate and analyze...
To better protect the security of the core site, such as precious material storage or the place to be visited by important figure, and to improve the efficiency of the security system of the core site, this paper proposes an identity authentication scheme based on fingerprint authentication and pulse. According to fingerprint and the dynamic password, and on the condition of the pulse for ensuring...
The aperture integral equation (AIE) and method of moment (MoM) technique is proposed for analyzing the electromagnetic scattering properties of a finite perfectly conducting cone loaded with a slot. The solution allows us to deal accurately with slots of any shape. Two kinds of slots representing for electrical large and electrical small structure respectively, are considered in this paper. Bi-static...
This paper reports a novel tunable photonic device. The device is based on dual coupled photonic crystal (PhC) nanobeam cavities. Different from other studies, where the cavities are mechanically tuned by varying the coupling gap, here the cavities are tuned by lateral shearing while maintaining a constant coupling gap. In experiments, both electrostatic force and optical gradient force are used to...
A series of triggering experiments were carried out to investigate into the characteristics of vacuum arc controlled by TMF-AMF contacts. During the whole experiments, current ranged from 5kA to 20kA (rms) and both arc appearance and the behavior of cathode spots were captured by high-speed camera with corresponding arc current and arc voltage. A 3D steady MHD model was built to simulate and analyze...
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