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Abstract: Cellulosic aerogels have attracted much attention because of their low density, high porosity and low thermal conductivity in many modified composite materials. Glycidyl methacrylate (GMA) is a new type of polymeric monomer with low cost, low toxicity, good biocompatibility, and easy chemical modification that has emerged in recent years, and it was widely used in the modification of rubber, fiber and other polymer materials. Cellulose composite aerogel, which is constructed by using GMA as a bridge to connect other materials, has rich functionality and shows great application potential in biomedicine, catalysis, adsorption and other fields. In this paper, the classification and properties of aerogels and cellulose are briefly described at first, then the synthesis methods of cellulose aerogels are introduced, and the applications of composite aerogels synthesized from cellulose modified by GMA in various fields in recent years are reviewed. This paper reviews the application of GMA-modified cellulose composite aerogels about the heavy metal and dye adsorption, biological tissues, wound dressings, drug carriers, biosensor and catalytic carriers. Finally, the future development prospect and current limitations of GMA modified cellulose aerogel are briefly introduced.Abstract: Cellulosic aerogels have attracted much attention because of their low density, high porosity and low thermal conductivity in many modified composite materials. Glycidyl methacrylate (GMA) is a new type of polymeric monomer with low cost, low toxicity, good biocompatibility, and easy chemical modification that has emerged in recent years, and it wa...Learn More
Abstract: This paper focuses on the design of l2 gain controller for discrete time switching systems with dwell time (DT) switching. So far, the quantitative relationship between l2 gain stability and dwell time is one of the unsolved problems in the field of switching systems. Different from previous studies, a novel dwell time dependent Lyapunov function (DTDLF) is proposed in this paper for the first time to obtain a less conservative stability criterion. The innovation of this Lyapunov function lies in that it is no longer built by the traditional two-step controller design method, but combines the two design tasks of controller and switching law into one framework, in which solving linear matrix inequalities (LMIs) involves only one step. Compared with the two-step design scheme, this method greatly simplifies the design process. Based on the resident time dependent Lyapunov function and the resident time switching strategy, a dwell time dependent (DTD) H∞ controller is designed such that the system is globally uniformly asymptotically stable (GUAS) and has a guaranteed H∞ performance index. Finally, a numerical example is given to verify the validity of the proposed design method. The simulation results show that the proposed design method can guarantee a shorter resident time limit and a smaller error result.Abstract: This paper focuses on the design of l2 gain controller for discrete time switching systems with dwell time (DT) switching. So far, the quantitative relationship between l2 gain stability and dwell time is one of the unsolved problems in the field of switching systems. Different from previous studies, a novel dwell time dependent Lyapunov function (...Learn More
Abstract: The underwater target detection based on the pulse signal has many applications in the field of marine engineering. Based on the simulation analysis of the traditional circular intersection positioning solution, this paper studies and designs a scheme for accurately calculating the target depth by estimating the time delay information of the three-pulse coded signal. The first pulse signal detects the target position and calculates the horizontal distance information. The time delay difference between the sounding pulse and the reference pulse and the first pulse corresponds to the pressure difference obtained by the high-precision sensor in the target, and the depth information of the target is obtained. However, the copy correlation technology is combined with the quadrature receiver algorithm theory to complete the amplitude detection and envelope estimation of sounding pulse and reference pulse. Through the verification of the field measurement data results, the underwater target resolution algorithm based on the pulse signal can achieve the indicators that the horizontal positioning error of the target is less than 5m and the depth positioning error is less than 2m in a specific scenario. This method can provide strong support for collaborative positioning of underwater targets and guarantee early warning maintenance.Abstract: The underwater target detection based on the pulse signal has many applications in the field of marine engineering. Based on the simulation analysis of the traditional circular intersection positioning solution, this paper studies and designs a scheme for accurately calculating the target depth by estimating the time delay information of the three-...Learn More
