Co-design of Anti-windup Compensator and a Novel Saturation-based Dynamic Event-triggered Mechanism for Asymmetric Saturated System

Hongchao Li,Huimin Deng,Nan Zhang,Mengfan Li 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.2

This paper addresses the co-design of anti-windup compensator and a novel saturation-based dynamic event-triggered condition for asymmetric saturated system. Asymmetric saturation frequently appears in practical systems, which may seriously degrade the system performance. For the systems with undetectable state, dynamic output feedback controller is employed in this paper. A saturation-based dynamic event-triggered mechanism related to the upper and lower bounds of asymmetric saturation is proposed in this paper, which has better performance in reducing the event-triggered number than static event-triggered condition. In addition, the minimum triggering time interval is calculated to avoid Zeno behavior. An optimization problem is formulated to maximize estimated stable region for the closed-loop system. Finally, the proposed results are illustrated by a numerical example.

Cavitation cloud dynamic characteristics of dual-chamber self-excited oscillatory waterjet

Dezheng Li,Yong Kang,Hanqing Shi,Yi Hu,Qi Liu,Hongchao Li,Jincheng Hu,Jiamin Li 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12

Aiming to enhance self-excited oscillating cavitation jet performance, the effect of the dual-chamber nozzlestructure on the jet dynamical characteristics was designed and investigated. With high-speed camera technology,the cavitation phenomenon was investigated to analyze the area pattern and shedding period of the cavitation cloudunder different nozzle structures. The results showed that the dual-chamber nozzle significantly improved the jet cavitationstrength, and the cavitation cloud area increased by 76% and decreased the shedding period by 90% comparedwith the single-chamber nozzle. In the upstream chamber, the upper shrinkage ratio had a more drastic effect on thecavitation cloud area and shedding frequency than the lower shrinkage ratio with a more sensitive effect on the sheddingfrequency. In the downstream chamber, the outlet diameter ratio and chamber diameter were more sensitive tothe regulation of cavitation cloud shedding frequency and area, respectively, with the optimal regulation at the outletdiameter ratio of 1 and chamber length of 6 mm. The chamber diameter modulated the cavitation cloud most drasticallywith a comprehensive performance optimum at 12mm, which the area fluctuation reached 76.8%. The resultsprovide a basis for further research and application of dual-chamber nozzles.

Research on Temperature Points Selection of the Non-source Temperature Calibration Method Based on Pyrometer Transfer Function

Sun Kun,Wang Jing,Wang Hongchao,Yu Limei,Li Chenyang,Zhang Xiaowen 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.11

The non-source temperature calibration method of the multi-spectral pyrometer (MSP), put forward in the previous article, is the non-source calibration method based on the MSP transfer function (NCCTF). In this paper, the practicability of NCCTF is researched. The situations that maybe encountered of the temperature points in the actual calibration process are simulated. The impact of the intervals temperature points of different number and unequal intervals temperature points on the NCCTF accuracy are researched theoretically to determine the temperature points select method. Simulation experimental results show that the NCCTF can meet the actual calibration process with good usability.

Research on Synthesis and Rheological Properties of Silicone Oil-based Ferrofluid with Dual Surfactants

Hongchao Cui,Jiahao Xu,Jiajia Zhang,Jingjing Lu,Zhenkun li 한국자기학회 2023 Journal of Magnetics Vol.28 No.1

Ferrofluids as a new kind of nano-functional material, possessing both magnetism of solid material and fluidity of liquid material, thus, they have extensive scientific research and engineering application value. To avoid the defects of conventional non- or single silane coupling agent in silicone oil-based ferrofluid preparation, TEOS and KH-792 were introduced as surfactants to modify Fe3O4 magnetic nanoparticles (MNPs). Silicone oil modified by carboxylic acid was used as based liquid because of improved compatibility with surfactants. Silicone oil-based ferrofluid was prepared by high-energy ball milling method, and its rheological properties were studied. The saturated magnetization of the silicon oil based ferrofluid was 142.71 Gs. When external magnetic field was applied, the MNPs formed a chain structure in the microscope. The viscosity of ferrofluid increased with magnetic field and the shear stress rose with shear rate. The viscosity decreased steeply with increasing temperature and shear rate. The viscosity of silicone oil-based ferrofluid was 950 mPa·s at 25 °C and can vary from 2044 mPa·s at 5 °C to 465 mPa·s at 40 °C. The ferrofluid transformed from a Newtonian fluid at zero magnetic field to a shear-thinning pseudoplastic Bingham fluid when an external magnetic field was applied. The viscosity varied from 1.37 to 2.38 × 105 mPa·s at zero shear rate. While, when magnetic field varied from 0 kA/ rose to 160 kA/m, the viscosity increased obviously and this phenomenon became more pronounced as the shear rate decreased. When magnetic field intensity was higher than 64 kA/m, the viscosity increased slowly with increasing shear rates and viscosity curve was close to a straight line at 100 s-1. This study expands the idea of exploring the synthesis of ferrofluids with mixed surfactants. Silicone oil-based ferrofluid is expected to have unique application prospects in the aerospace field, especially in space damping, sealing and biomedicine.

Experimental Study on Mechanical Properties of Q690 High Strength Steel in Marine Corrosive Environment

Hongchao Guo,Tianqi Lei,Jinguang Yu,Defa Wang,Xiaolei Li 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.2

In order to study the mechanical property degradation rule of Q690 high-strength steel in the ocean wave splash area, the rusted specimen is obtained by indoor damp heat surrounding soaking environment corrosion test. The scanning electron microscopy, uniaxial tensile and cyclic loading tests of corroded steel are performed. This paper analyzes the steel from elastic modulus, yield strength, ductility and law of hysteresis degradation under diff erent corrosion cycles and establishes the constitutive model of HSS. The results show that the appearance of HSS is obviously aff ected by the corrosion cycle. With the increase of the corrosion cycle, reddish-brown fl aky corrosion products are formed on the surface of the steel and there are obvious corrosion pits. After 100 days of corrosion, the corrosion rate of steel reached 7.21%; the elastic modulus and yield strength under uniaxial tension load decreased by 10.2% and 4.9%. Under the eff ect of cyclic reciprocating load, the hysteretic energy is reduced by 15.3%; at the same time, the test curve is fi tted by the secondary plastic fl ow model and the Ramberg–Osgood model and it is found that the shape parameter S 1 and the cyclic strengthening coeffi cient K’ are reduced by 20.1% and 10.2%, While the shape parameter S 2 and the cycle strengthening index n’ have no obvious changes.

Research on the rheological properties of a silicone oil-based ferrofluid

Zhang Jiajia,Cui Hongchao,Han Shida,Li Zhenkun,Lu Jingjing 한국유변학회 2023 Korea-Australia rheology journal Vol.35 No.3

To study the overall rheological characteristics of the silicone oil-based ferrofluid, a chemical co-precipitation method was adopted for preparation, and transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) were used for characterization. The average size of Fe3O4 magnetic particles was 10.4 nm and the saturation magnetization of the ferrofluid was 5.98 emu/g. Then, the fluidity, magnetoviscous effect and viscoelasticity of the ferrofluid were studied using a rotational rheometer. The results showed obvious shear thinning of the silicone oil-based ferrofluid under an external magnetic field, and the yield stress of the ferrofluid could not be accurately obtained by fitting the flow curve with an H–B model at a continuous shear rate. A strong magnetoviscous effect could be observed at different shear rates and temperatures. The magnetoviscous parameter R increased with the increase of temperature and its variation decreased with the increase of shear rate. Moreover, based on the magnetic particle chain model and the viscosity–temperature characteristics of the base carrier liquid, different mechanisms of temperature influence on the magnetoviscous effect were analyzed. Finally, a discussion of the microstructure evolution mechanism of the ferrofluid in the modulus changing with frequency was presented through the viscoelastic analysis of the silicone oil-based ferrofluid.

Event-triggered Output-feedback Control for Networked Switched Positive Systems with Asynchronous Switching

Jiao Liu,Yake Yang,Hongchao Li,Yanli Geng 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.9

The issue of asynchronously output-feedback control for a class of discrete-time networked switched positive systems in the presence of network-induced time delays is discussed in this paper. Due to the limited communication energy or network bandwidth, an event-triggered control strategy capable of achieving the goal of reducing the resources and the communication load is adopted. Different from the existing results, by taking full advantage of positive property of output, a mode-dependent linear weighting triggering condition is given in the paper, which can deal with the positive stabilization problem efficiently. Furthermore, an asynchronously event-triggered output-feedback controller is designed to ensure the closed loop system remain positive and exponentially stable by virtue of multiple copositive type Lyapunov-Krasovskii functional incorporated with linear programming method. Finally, a numerical example is provided to verify the results obtained.

Fully Recrystallized Al0.5CoCrFeNi High-Entropy Alloy Strengthened by Nanoscale Precipitates

Haoxue Yang,Jinshan Li,Tong Guo,William Yi Wang,Hongchao Kou,Jun Wang 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.5

The correlation among the strength, ductility and precipitates in a dual-phase Al0.5CoCrFeNihigh-entropy alloy has beeninvestigated. The property of plastic was improved in the recrystallized Al0.5CoCrFeNiHEA prepared as the master alloy. Formation of the stable nanosized L12phases after aging at 650 °C was revealed, along with the lath-like BCC phasesprecipitated in the grain, as the primary contribution of the strength enhancement. Excellent balanced tensile properties atroom temperature were achieved through aging treatment, as the yield strength and ultimate tensile strength show 2.68, 1.63times higher in 650 °C/140 h aged condition than that in initial states, respectively, superior to many high-entropy alloysand conventional alloys.

Asynchronous Control for Positive Markov Jump Systems

Kai Yin,Dedong Yang,Jiao Liu,Hongchao Li 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.2

A new result is provided for the asynchronous control analysis of positive Markov jump systems (PMJSs) in this paper. Firstly, a hidden Markov model is described to express the asynchronous circumstances that appear between the system modes and controller modes. Secondly, by utilizing a copositive stochastic Lyapunov function, a sufficient and necessary condition is given to guarantee the mean stability of PMJSs. Thirdly, we obtain another equivalent condition and design the corresponding asynchronous controller. Finally, the correctness of these results is verified by two numerical examples.