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Hydrothermal liquefaction (HTL) of biomass used HTL reaction under high temperature and pressure to produce bio-oil. This technology is considered as one of the most promising converting technology of biomass to biofuels. This paper summarized current research developments of HTL for bio-oil and analyzed its reaction mechanism and influencing factors based on bibliometric analysis. The results showed that reaction conditions and catalyst have been still global researching focuses about HTL. Compared with homogeneous catalysts, the study of HTL by using heterogeneous catalyst developed more quickly. With promotion of resource recovering, food waste, sludge, and other organic waste can also be used as raw materials for HTL for bio-oil now. [ABSTRACT FROM AUTHOR]

The accuracy of channel state information (CSI) acquisition directly affects the performance of millimeter wave (mmWave) communications. In this article, we provide an overview on CSI acquisition, including beam training and channel estimation for mmWave massive multiple-input multiple-output systems. The beam training can avoid the estimation of a high-dimension channel matrix, while the channel estimation can flexibly exploit advanced signal processing techniques. In addition to introducing the traditional and machine learning-based approaches in this article, we also compare different approaches in terms of spectral efficiency, computational complexity, and overhead. [ABSTRACT FROM AUTHOR]

This work investigates the estimation of target scattering coefficients (TSC) in cognitive radar systems with temporally correlated targets. An estimation method based on Kalman filtering (KF) is proposed to exploit the temporal TSC correlation between the pulses in the frequency domain. To minimize the mean square error of the estimated TSC at each KF iteration, unlike existing indirect methods, in this paper the radar waveform is optimized directly under the constraints of transmitted power, peak-to-average power ratio (PAPR) and detection probability. Since the optimization problem regarding the waveform design is non-convex, a novel method is proposed to convert this problem into a convex one. Simulation results demonstrate that the performance of the TSC estimation for the temporally correlated target is significantly improved by radar waveform optimization. Meanwhile, no performance degradation is observed with the introduction of the additional PAPR constraints and the detection constraints for KF estimation with the optimized waveform. [ABSTRACT FROM AUTHOR]

H.264/AVC achieves higher compression efficiency than previous video coding standards. However, the process of selecting the optimal coding mode for each macroblock (MB) results in extremely high computation complexity, which make it difficult for practical use. In this paper, an efficient algorithm is proposed to reduce the complexity of MB mode selection. The proposed algorithm identified the interior region of the motion object by using the motion vectors information firstly. For the interior region surrounded by the identical motion vectors, we skip the mode selection of the MBs and then treat them with large block size modes directly. We also discuss the specific examples in this region. For the boundary region, we classify them into different types according to the coded mode information. After that we process the different regions with different mode set distinctly. Experimental results show that the proposed algorithm can save the encoding time up to 46% on average compared to the conventional method in the JVT JM8.6 reference encoder with only 0.12 dB performance degradation. [ABSTRACT FROM AUTHOR]

The paper presents a kind of transmission system which employs M-ary Position Phase Shift Keying (MPPSK) to send data and Phase Locked Loop (PLL) based techniques for data retrieve. With a single PLL, MPPSK demodulation is achieved, as well as carrier recovery and symbol synchronization. Firstly, MPPSK modulation method is briefly introduced. 2PPSK’s PSD expression is given with its optimization result. Orthogonal Phase Detector (PD) and static threshold are used for the purpose of wider phase range and simplicity in demodulation. The data rate is alterable, which is 4.65 kbps for 2PPSK and 9.3 kbps for 4PPSK in the paper. Then some indicative comparisons in Signal to Noise Ratio Symbol Error Rate (SNR-SER) are made among 2PPSK, 3PPSK and 4PPSK, of which 4PPSK has proved to be optimal in ten slots each symbol conditions. And finally, it is demonstrated by system simulations that lower than 10−4 Symbol Error Rate (SER) performance can be obtained at 13 dB symbol SNR. [ABSTRACT FROM AUTHOR]