Sichuan Provincial Department of Education

LiDAR is an active optical sensing technology that measures target information by emitting laser pulses and analyzing the reflected echo signals. Among various LiDAR modalities, Inverse Synthetic Aperture LiDAR (ISAL) achieves super-diffraction imaging by synthesizing a large effective aperture through target motion and coherent accumulation. Linear Frequency Modulated Continuous Wave (LFMCW) coherent detection, as the core technology of ISAL systems, possesses Doppler sensitivity and serves as a key approach to surpass classical diffraction limits. However, in practical applications, LFMCW coherent detection systems often encounter severe clutter and noise interference, which significantly degrade the effective extraction and analysis of beat frequency signals, thus reducing the reliability of experimental outcomes. To address these challenges, this work introduces the Adaptive Variational Mode Decomposition (AVMD) with correlation-based mode selection algorithm to achieve effective separation and feature extraction of echo signals, and designs a receiver architecture based on an AVMD–Fast Fourier Transform (AVMD-FFT) framework to implement coherent detection functionality. The receiver system employs a field-programmable gate array (FPGA) control board and analog-to-digital conversion chips for real-time acquisition, storage, and transmission of echo signals. Subsequently, the acquired data are parsed by a backend control program and processed with the VMD-FFT algorithm for frequency discrimination and ranging. Experimental results demonstrate that the proposed system stably extracts meaningful target information even under harsh conditions with signal-to-noise ratios below 3dB. Furthermore, this innovative signal processing methodology can be extended to other optoelectronic detection systems, offering broad application prospects in autonomous driving perception, industrial high-precision measurement, aerospace target identification, and related fields.

Magnetic Fe and N-doped biochar (FeN-BC) was synthesized from waste bamboo through microwave pyrolysis and used as a catalyst for the degradation of tetracycline hydrochloride (TC) with peroxymonosulfate (PMS). The results showed that doping with Fe improved the recovery performance of biochar and the N-doping enhanced the activity of PMS. Simultaneously, it achieved a high degradation efficiency for TC (93%) under optimized conditions within 30 min. Electron paramagnetic resonance (EPR) and quenching experiments indicated that the main active radicals present in the experiment were SO4•- and •OH. Additionally, FeN-BC demonstrated good catalytic performance in the TC degradation process in a real water environment after five cycles. This work presents a practical strategy for preparing magnetic biochar to degrade organic pollutants from wastewater.

Almond shell-modifiedurea–formaldehyde resins (AUF) wereprepared in this study. The optimal addition amount of almond shellswas selected by formaldehyde emission and wet shear strength. Theactivation energy (Ea) values at differentconversion rates and the reaction kinetics were estimated based onthe Flynn–Wall–Ozawa method. The results indicated thatalmond shells can significantly reduce the formaldehyde emission andincrease wet shear strength and thermal stability of the urea–formaldehyderesin adhesive. The optimal addition of almond shells is 3 wt %.

In recent years, soy protein adhesive, as an environmentally friendly bio-based adhesive, has attracted extensive attention. In this study, in order to ameliorate the bonding quality of soy protein isolate (SPI) adhesive, the melamine–urea–formaldehyde prepolymer (MUFP) was synthesized, and different amounts of it were introduced into the SPI adhesive as a cross-linking agent. Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC), thermogravimetric analyze (TGA), and scanning electron microscopy (SEM) were used to analysis the mechanism of modification. The results of plywood test indicated that the wet bonding strength of the adhesives was first increased and then decreased with an increase in the amount of MUFP additive. FT-IR, TGA, and SEM tests suggested that the introduction of MUFP could promote the establishment of a cross-linking structure in the cured adhesive layer to improve the bonding quality of adhesives, but presence of excessive MUFP could introduce hydrophilic groups and adversely affect water resistance.