Precise control of the number and position catalytic metal ions in heterogeneous catalysts remains a big challenge. Here we synthesized series two-dimensional (2D) covalent organic frameworks (COFs) containing two different types nitrogen ligands, namely imine bipyridine, with controllable contents. For first time, selective coordination ligands 2D COFs to complexes, chloro(1,5-cyclooctadiene)rhodium(I) (Rh(COD)Cl) palladium(II) acetate (Pd(OAc)2 ), has been realized using programmed...

This paper focuses on the vibration periodic property of Duffing oscillator with generalized initial conditions. Firstly, undamped case is solved by Ji-Huan He’s frequency formulation; Secondly, formulation extended to damped case. Numerical verification shows that mathematically simple and physically insightful practically applicable. paves a novel way for engineers use study nonlinear system ease reliability.

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This paper proposes a fixed-time prescribed performance control technique to address the challenge of precise trajectory tracking for unmanned surface vessels (USVs) in presence external time-varying disturbances and input saturation. To begin with, disturbance observer is created handle interference. The can accurately estimate compensate fixed time, which effectively improves robustness system. Furthermore, guarantee both transient steady-state response system, we employed specific...

This article proposes a prescribed-time trajectory tracking control algorithm for unmanned surface vessels with lumped disturbances, limited communication, and error constraints, utilizing an event-triggered mechanism. Firstly, we present disturbances observer to accurately estimate the including external ocean model uncertainties, unmodeled dynamics. Then, prescribed performance function is implemented achieve guaranteed steady-state within predefined time. In addition, strategy embedded...

The ship dynamic positioning system has long been a subject of great interest due to the intricate and unpredictable nature maritime environment, which affects its dependability timeliness. This study focuses on issue developing robust, efficient, adaptable fault-tolerant control for systems that experience thruster malfunctions. Firstly, we build motion model ship’s with three degrees freedom, as well faults in thruster. A second-order fast fixed-time nonsingular sliding mode surface is...

Epitaxial crystallization of poly(ε-caprolactone) (PCL) on reduced graphene oxide (RGO) was investigated by melt and solution crystallization. RGO (GO) provided an opportunity to investigate the influence surface functional groups epitaxial with lattice matching. After annealing treatment, PCL/RGO composites showed extra melting peak, which implied that PCL could form thicker lamellae. An analogous procedure used confirm epitaxy morphology orientation polymer chains. The results chains...

In the field of structural health monitoring (SHM), with mature development artificial intelligence, deep learning-based damage identification techniques have attracted wide attention. this paper, convolutional neural network (CNN) is used to extract feature simple supported steel beams. Firstly, transient dynamic analysis beam carried out by finite element software, and acceleration response signals under different scenarios are obtained. Then, signal decomposed wavelet packet decomposition...

Abstract This paper proposes a composite non-singular fast terminal sliding mode attitude control scheme based on reduced-order extended state observer for the stratospheric airship’s system affected by multiple disturbances. First, feedback linearisation method is applied to address nonlinearity of motion model and achieve decoupling in three channels. Second, overall disturbances, encompassing airship parameter perturbations external are treated as an aggregate. A designed each channel...

Formation obstacle avoidance is a critical aspect of cooperation among unmanned surface vehicles (USVs). In practical scenarios involving multiple USVs, managing during formation assembly and navigation essential to ensure the success cooperative tasks. This study devised obstacle-avoidance scheme utilizing dynamical systems (DS). The traditional interfered fluid system (IFDS) applied in two-dimensional planes was enhanced address local minima issues. Furthermore, robust virtual structure...

Defects in pile foundations, such as neck defects, bulge imperfections, weak concretes, cracks, and broken piles, can cause a decrease the bearing capacity structural stability of foundation. Identification type defect is vital formulating reasonable repair plan for In this study, authors proposed scheme to identify types defects concrete piles based on convolution neural network low-strain integrity test (LSPIT). A batch modeling method defective foundations using Python script was also...

This study proposes a fixed-time precision tracking control scheme for unmanned surface vessels with complex disturbances and unknown system dynamics. The is based on nonsingular fast terminal sliding mode includes an adaptive integral lumped disturbance observer to precisely observe compensate unknowns. To ensure performance under both transient steady-state conditions, prescribed function was utilized enable the trajectory error converge predetermined range. proposed scheme, called...

The alignment accuracy and stability of shipborne electro-optical system are affected by external attitude disturbance internal non-linear disturbance. Therefore, this study examined a new digital sliding mode control based on novel reaching law with an n-order compensator to solve problem. Specially, the proposed was chatter-free method, in which, as switching gain replaced adaptive function, chattering surface tended zero. For perturbed systems, controller able guarantee narrow...

This paper describes a novel approach based upon wavelet transforms for sensor validation. By the use of that well localise characterisation signal both in time and frequency domains, occurring instants abnormal status its output can be identified. Once these are detected, distributions energy, on all decomposed levels this before after instants, used to validate because there various energy distribution patterns different failures sensor. Both computer simulation experimental data from...

Fast steering mirrors (FSMs) have been used for decades to improve the performance of electro-optical imaging systems, such as airborne systems and space-based optical surveillance systems. With advantage increasing accuracy image motion compensation efficiency scanning imaging, backscanning step-and-stare has become main approach realizing wide-area According operating mode profile FSM in system, a combined optimized (COP) is designed avoid abrupt changes velocity acceleration FSM. The...

This paper investigates the challenging problem of fixed-time formation trajectory tracking control for multiple unmanned surface vessels (USVs) affected by uncertain model dynamics, time-varying external ocean disturbances, as well input saturation. Firstly, an adaptive super-twisting lumped disturbance observer (ASTLDO) is created integrating high-order sliding mode with technology, which can accurately observe and compensate complex system within a finite time. Secondly, following...

The control problem of avoidance-path-following is a critical consideration in the research unmanned surface vehicle (USV) navigation control, and it holds great significance for safety USVs. A guidance scheme based on finite-distance convergence proposed this paper. First, requirements USV to avoid obstacles from perspective path-following lateral error are analyzed. Then, new performance function with constrain error. Based this, heading law backstepping controller designed ensure that...

This article proposes a comprehensive approach to achieve high-precision modeling, high bandwidth, and robust control for the voice coil actuator fast steering mirror (VCA-FSM). includes Hankel matrix identification method, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$H_{\infty }$</tex-math></inline-formula> sensitivity control, disturbance observer (DOB), zero phase error tracking (ZPETC) algorithms....

In this study, a sliding mode control (SMC) algorithm was proposed based on novel reaching law to solve the nonlinear disturbance problem of ground-based laser communication turntable. This is chatter-free method, in which coefficient variable structure function designed as an adaptive function, so chattering approaches zero. For any perturbed system, can ensure finite time for system state reach surface from initial state. Additionally, will stabilize quasi-sliding domain (QSMD) with O(T3)...