A New Result on the Stability and Convergence of Self-tuning Adaptive Control

Weicun Zhang,Yuejin Song,Jiwei Liu 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

Among various types of self-tuning control schemes, only one-step-ahead self-tuning control of deterministic plant and minimum variance self-tuning control of stochastic plant can guarantee the stability and convergence of closed-loop system without requiring the convergence of parameter estimation. This paper presents a new result that the convergence of parameter estimates is not necessary for the stability and convergence of a general self-tuning control system comprising of any admissible control strategy and any admissible parameter estimation algorithm. This breakthrough result is owing to the adoption of a new type of virtual equivalent system: slow switching control system, whose stability and tracking performance are guaranteed under mild conditions.

Positive solutions for a three-point fractional boundary value problems for p-Laplacian with a parameter

Yitao Yang,Yuejin Zhang 한국전산응용수학회 2016 Journal of applied mathematics & informatics Vol.34 No.3

In this paper, we firstly use Krasnosel'skii fixed point theorem to investigate positive solutions for the following three-point boundary value problems for $p$-Laplacian with a parameter $$(\phi_{p}(D_{0^{+}}^{\alpha}u(t)))'+\lambda f(t,u(t))=0,\ \ \ 0<t<1,$$ $$D_{0^{+}}^{\alpha}u(0)=u(0)=u''(0)=0,\ \ \ u'(1)=\gamma u'(\eta),$$ where $\phi_{p}(s)=|s|^{p-2}s,\ p>1,\ D_{0^{+}}^{\alpha}$ is the Caputo's derivative, $\alpha\in (2,3],\ \eta,\gamma\in (0,1), \lambda>0$ is a parameter. Then we use Leggett-Williams fixed point theorem to study the existence of three positive solutions for the fractional boundary value problem$$(\phi_{p}(D_{0^{+}}^{\alpha}u(t)))'+f(t,u(t))=0,\ \ \ 0<t<1,$$ $$D_{0^{+}}^{\alpha}u(0)=u(0)=u''(0)=0,\ \ \ u'(1)=\gamma u'(\eta),$$ where $\phi_{p}(s)=|s|^{p-2}s,\ p>1,\ D_{0^{+}}^{\alpha}$ is the Caputo's derivative, $\alpha\in (2,3],\ \eta,\gamma\in (0,1).$

Numerical simulation on flow field of motor annular water jacket and its cooling performance optimization

Libin Tan,Yuejin Yuan 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8

Aiming at improving the cooling of motor annular water jacket, the effects of different water jacket designs and pump rotation speed and epoxy resin filling on the flow field characteristics and motor temperature distribution were studied. Results show that uneven flow distribution leads to high temperature of motor coil and large temperature gradient. The optimized water jacket has better flow, uniform flow distribution of long and short paths, higher utilization rate of coolant, and the coil temperature is 2 °C lower than that of original model. On the basis of optimized water jacket, when epoxy resin filling methodology and pump rotation speed increased to 5000 r/min are applied, the coil temperature can be reduced by 16 °C compared with the original model. From the cooling performance optimization results in current case, the improvement order from the smallest to the biggest is the optimization of motor water jacket flow field, optimization of motor water jacket system flow rate, and the epoxy resin filling. To meet the cooling demands of motor, the comprehensive effects from the aspects of reducing coolant system resistance, increasing pump speed, epoxy resin filling and other effective technologies are ought to be considered for all case studies.

DELAY-DEPENDENT GLOBAL ASYMPTOTIC STABILITY ANALYSIS OF DELAYED CELLULAR NEURAL NETWORKS

Yitao Yang,Yuejin Zhang 한국전산응용수학회 2010 Journal of applied mathematics & informatics Vol.28 No.3

In this paper, the problem of delay-dependent stability analysis for cellular neural networks systems with time-varying delays was considered. By using a new Lyapunov-Krasovskii function,delay-dependant stability conditions of the delayed cellular neural networks systems are proposed in terms of linear matrix inequalities (LMIs). Examples are provided to demonstrate the reduced conservatism of the proposed stability results.

Numerical simulation on flow field characteristics of the four cylinder engine cooling system and its performance improvement

Libin Tan,Yuejin Yuan 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1

The comprehensive performance evaluation procedure and overall performance evaluation indices for the four cylinder engine cooling systems are proposed in this work and the four cylinder engine cooling system with two different flow patterns are investigated. Coolant velocity distributions of nose bridge area sections of cylinder head water jacket and plane section of cylinder block water jacket in series flow pattern cooling system meet the coolant flow velocity requirements of 1.5 m/s in high-temperature area. Coolant velocity distributions of water jacket in parallel flow pattern cooling system is relatively lower and not meet the velocity requirements of 1.5 m/s. Through the improvement of pump performance, the system coolant flowrate in parallel flow pattern cooling system can be increased to 90 L/min. After velocity uniformity improvement of water jacket, the coolant velocity distributions in parallel flow cooling system become more uniform. Coolant velocity and heat transfer coefficient of high temperature area both meet the design requirements of coolant velocity 1.5 m/s and heat transfer coefficients of 5000 W/(m 2 ·K). The cooling performance for the engine with parallel flow pattern cooling system is significantly improved and meets the cooling design requirements.

Differential Expression Profiles of Alternaria alternate Genes in Response to Carbonyl Sulfide Fumigation

Tao Liu,Li Li,Yuejin Wang,Guoping Zhan,Bo Liu 한국미생물학회 2010 The journal of microbiology Vol.48 No.4

Carbonyl sulfide (COS) is a new fumigant used in phytosanitary treatments. It was developed as a potential alternative to methyl bromide, which is being phased out because of its ozone-depletion properties. To understand the molecular and cellular mechanisms occurring in fungal pathogens in response to COS fumigation, we cloned 510 cDNA fragments of Alternaria alternata (Fr.) Keissler genes that are differentially expressed; these genes were cloned using suppression subtractive hybridization. Changes in the levels of transcripts of 79 fragments were confirmed by microarray analysis and qRT-PCR. Further homology search revealed that they are highly homologous to 41 genes of other fungi, which were related to general metabolism, growth and division, defense, cellular transport, and signal transduction. These results provide an overview of differential expression profiles of A. alternata genes following COS treatment and some new clues about the mechanism of COS fungitoxicity.

POSITIVE SOLUTIONS FOR A THREE-POINT FRACTIONAL BOUNDARY VALUE PROBLEMS FOR P-LAPLACIAN WITH A PARAMETER

YANG, YITAO,ZHANG, YUEJIN The Korean Society for Computational and Applied M 2016 Journal of applied mathematics & informatics Vol.34 No.3

In this paper, we firstly use Krasnosel'skii fixed point theorem to investigate positive solutions for the following three-point boundary value problems for p-Laplacian with a parameter $({\phi}_P(D^{\alpha}_{0}+u(t)))^{\prime}+{\lambda}f(t, u(t))=0$, 0<t<1, $D^{\alpha}_{0}+u(0)=u(0)=u{\prime}{\prime}(0)=0$, $u^{\prime}(1)={\gamma}u^{\prime}(\eta)$ where ϕ_p(s) = |s|^p⁻²s, p > 1, $D^{\alpha}_{0^+}$ is the Caputo's derivative, α ∈ (2, 3], η, γ ∈ (0, 1), λ > 0 is a parameter. Then we use Leggett-Williams fixed point theorem to study the existence of three positive solutions for the fractional boundary value problem $({\phi}_P(D^{\alpha}_{0}+u(t)))^{\prime}+f(t, u(t))=0$, 0<t<1, $D^{\alpha}_{0}+u(0)=u(0)=u{\prime}{\prime}(0)=0$, $u^{\prime}(1)={\gamma}u^{\prime}(\eta)$ where ϕ_p(s) = |s|^p⁻²s, p > 1, $D^{\alpha}_{0^+}$ is the Caputo's derivative, α ∈ (2, 3], η, γ ∈ (0, 1).

A Stability Criterion for Weighting Multiple Model Adaptive Control

Weicun Zhang,Xiaobo Wang,Yuejin Song 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

Based on virtual equivalent system concept and methodology, a criterion on the stability of weighting multiple model adaptive control (MMAC) of linear time-invariant discrete plant is presented. The obtained result indicates that the stability of weighting MMAC depends mainly on the convergence of posterior probability evaluator which represents an identification subsystem in a weighting multiple model adaptive control system. For that a general weighting MMAC with arbitrary controller design strategy and arbitrary algorithm of posterior probability evaluation is considered, we believe that virtual equivalent system concept and methodology could be a potential approach towards a general theory of weighting multiple model adaptive control.

CFD simulation and optimization on airflow uniformity of material drying room used in steam blanching and hot-air vacuum drying equipment

Dong Wang,Libin Tan,Yuejin Yuan,Yuming Lu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10

Airflow velocity uniformity in material drying room used in steam blanching and hot-air vacuum drying equipment is crucial for obtaining a good drying quality of fruits and vegetables. To analyze the airflow velocity uniformity and give the optimization design for improving the airflow uniformity, CFD method is used for the flow field analysis of material drying room and the velocity non-uniformity coefficient is used as the evaluation indicator for the velocity uniformity. Results show that the airflow velocity distribution in the material drying room at the original inlet airflow distribution chamber is relatively uneven and the airflow velocity nonuniformity coefficient in drying area is 34 %. For reducing the airflow velocity non-uniformity, the airflow velocity distribution of three structural modification directions with 12 designs in total are analyzed and compared. The minimum airflow velocity non-uniformity coefficient for adding a spoiler model, reducing the closed end width and adding nozzle baffles are 17.1 %, 30.2 %, 10.4 %, respectively. Through comparison, adding the nozzle baffle with a width of 11 mm at the rear end of each nozzle outlet is considered as the optimal designs to conduct the experimental validation. Experimental validation results shows the the relative error between the simulated value and the measured value is within 10 %, proving that the CFD prediction results is reliable and the research results can give a theoretical reference for the designers to evaluate and optimize the structure of inlet airflow distribution chamber for improving the airflow uniformity in drying area.

DELAY-DEPENDENT GLOBAL ASYMPTOTIC STABILITY ANALYSIS OF DELAYED CELLULAR NEURAL NETWORKS

Yang, Yitao,Zhang, Yuejin The Korean Society for Computational and Applied M 2010 Journal of applied mathematics & informatics Vol.28 No.3

In this paper, the problem of delay-dependent stability analysis for cellular neural networks systems with time-varying delays was considered. By using a new Lyapunov-Krasovskii function, delay-dependant stability conditions of the delayed cellular neural networks systems are proposed in terms of linear matrix inequalities (LMIs). Examples are provided to demonstrate the reduced conservatism of the proposed stability results.