An improved decoding algorithm based on joint bitplane decoding for distributed video coding is proposed. The new algorithm uses the decoded bitplane results of quantization coefficients as prior knowledge, and decodes the other bit-planes to avoid correlation weakening between sources when decoding bit-planes independently. It makes full use of correlation between Wyner-Ziv frames and key frames; therefore the rate-distortion performance of distributed video coding can be enhanced without increasing decoding complexity. Simulations indicate that, compared with the independent bit-planes decoding system, the proposed algorithm can achieve 13% to 16% bit-rate saving under the same condition, and performance improves more apparently with the increase of quantization levels.
β-Gallium oxide (β-Ga2O3) has been studied extensively in the past decades due to its excellent ability in fabricating variety of devices, such as solar-blind photodetectors and power devices. However, as an important part in device, the related investigation of β-Ga2O3-metal contact, especially for Schottky contact, are rare. In this review, we summarized the recent research progresses on β-Ga2O3-metal contact, including related theories, measurements, fabrication processes, controlment methods, etc. This review will provide insights for both theoretical understanding of the metal/semiconductor interface, and the fabrication process in engineering applications of Ga2O3 based devices.
Gallium oxide (Ga2O3) is a representative of ultra-wide bandgap semiconductor, with a bandgap of about 4.9 eV. In addition to a large dielectric constant, excellent physical and chemical stability, Ga2O3 has a breakdown electric field strength of more than 8 MV/cm, which is 27 times than that of Si and about twice larger than that of SiC and GaN. It is guaranteed that Ga2O3 has irreplaceable applications in ultra-high power (1-10 kW) electronic devices. Unfortunately, due to the difficulty of p-type doping of Ga2O3, only unipolar Ga2O3power Schottky diodes are feasible, but substantial progress has been made in recent years. In this article, we review the advanced progresses and important achievements of the state-of-the-arts Ga2O3 based power SBDs, and provide staged guidance for the further development of Ga2O3 power devices. The multiple type of device architectures, including basic structure, edge terminal processing, field plated, trench and heterojunction p-n structure, will be
This paper investigates a quantitative ground risk assessment method for future urban air mobility, which can be divided into three main processes: risk modelling, risk assessment and mitigation recommendation for flight planning and management. First, the aircraft kinetic models for both fixed-wing aircraft and rotorcraft are investigated, along with the corresponding ballistic and glide descent mode and the associated wind influence. The probabilistic impact to road traffic and pedestrians on the ground as a result of potential crash are then derived. With an assumed crash probability of the aircraft, the initial risk value and distribution are computed, which are used to produce a risk cost map across the mission area. Next, the flight request is processed based on such risk map using a common path planning algorithm, minimizing the overall risk for the flight plan to be generated. Finally, a preliminary case study involving a rotorcraft conducting urban cargo transportation service is performed to evaluate the proposed risk assessment method in a real-world urban environment.
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