基于FPGA的锯齿波调频梳状信号发生器的设计与实现

随着通信技术的发展,跳频信号在通信系统中有着越来越广泛的应用。梳状谱信号对跳频通信系统的影响十分显著,本文根据梳状谱信号产生机理,在理论分析与Matlab仿真基础上,基于FPGA平台设计与实现了锯齿波调频梳状谱信号发生器。     

Study of depolymerization of cotton cellulose by Pb/PbO2 anode electrochemical catalysis in sulfuric acid solution

A novel method of cotton cellulose depolymerization is investigated in this paper. In this work, a three-electrode system, which contains a Pb/PbO₂ anode, two copper cathodes and a reference saturated calomel electrode (SCE), is applied to electrocatalytic depolymerization of cotton cellulose. After electrocatalytic depolymerization of cotton cellulose in 0.5M sulfuric acid solution using Pb/PbO₂ anode at room temperature (25 °C), the average degree of polymerization (DP) can be reduced to the minimum 367 from 1100. The effects of operating parameters, such as supporting electrolyte, current density and reaction time are investigated as well. The composition of the products in filtrate is characterized by phenol-sulfuric acid method, extraction, NMR, GC-MS and High Performance Liquid Chromatography (HPLC). In addition, the solid sample is analyzed via SEM images, XRD diffractogram, Ubbelohde capillary viscometer and FT-IR spectra. The results suggest that it is effective to convert cotton cellulose to soluble sugar, 5-hydroxymethylfurfural (5-HMF) and other products by electrocatalytic methods. However, the yield of products is low and needs further study. A novel method to significantly convert cotton cellulose to biofuels and biomaterials can be hopefully developed if the selectivity of cotton cellulose electrocatalytic depolymerization is improved in the future.