Multi-rate Dynamic Event-triggered H∞ Control for Linear Singularly Perturbed Systems

Shixian Luo,Zhan He,Xin Chen,Qinghua Zhong 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.11

This paper addresses the event-triggered multi-rate H∞ control problem for linear singularly perturbed systems. A two-time-scale dynamic event-triggering mechanism is proposed to generate sampling time sequences for slow and fast subsystems. The proposed dynamic event-triggering mechanism embeds with internal dynamic variables and dwell times, which can not only increase the inter-event times compared with its static counterparts but also avoid Zeno behavior naturally. The multi-rate sampled-data control law is designed by discretizing the continuous-time composite controller based on the reduced-order technique. By employing switched time-delay system approach combined with a novel switching time-dependent Lyapunov functional, sufficient conditions for stability and L2-gain properties of the closed-loop systems are established in terms of linear matrix inequalities. The effectiveness of the theoretical results is demonstrated by a vehicle active suspension system.

Manufacturing High Sensitive Strain Sensor of Polyurethane Nanofiber Mat/AgNWs by Simple Dip-dry Method

Lingling Liu,Shixian Chen,Anchang Xu,Guangming Cai 한국섬유공학회 2020 Fibers and polymers Vol.21 No.2

Adding nano silver wires (AgNWs) onto electrospun polyurethane (PU) nanofiber mat provide a new idea for developing wearable smart textiles. The excellent stretchability of PU and the excellent electrical conductivity of AgNWsenable wearable smart textiles to monitor human physiological data. In this study, PU nanofiber mat was prepared by electrospinning and subsequently was dip into AgNWs dispersion for conductivity. The PU nanofiber mats adsorbed with AgNWs were with both good stretching and electrical conductivity. The surface morphology and surface elements were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The mechanical properties and the variation of electrical conductivity under static and dynamic stretching cycles were studied. In addition, it is accurately monitoring variation in electrical conductivity during finger bending and wrist movement. The experimental results show that the PU mat treated by AgNWs has the potential to be used as a wearable strain sensor for real-time monitoring of human motion.

A Framework for Analyzing Anonymous Network Topology

Tianbo Lu,Shixian Du,Yang Li,Peiyuan Dong,Xiaoyan Zhang 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.4

Nowadays, Internet privacy becomes more and more important and sensitive, and has been one of the latest buzz words to hit the Internet world. In response to protect the privacy of Internet users, a variety of privacy enhancing technologies (PETs) have emerged. As one of privacy enhancing technologies, anonymous communication has been extensively studied from various aspects by researchers. Node churn is frequent in anonymous network, which make it difficult to maintain a stable network topology, therefore it is necessary to get more insight into the overall anonymous network topology. In this work, in order to better grasp the present situation of research, we investigate existing organizations and universities which study anonymous communication from the perspective of network topology, and related projects. Then we survey related papers to anonymous communication published in recent years, which focus on the analysis of node selection (especially in the Tor). In addition, we present a framework of anonymous communication network topology, and a visual illustration of this analysis that shows the progression of the research of network topology and node discovery in anonymous communication. Finally, some related problems and follow-up study are presented to be studied deeply in future.

Direct Determination of Interchain Transfer Constants for Radical Polymerization of Benzyl Acrylate by RAFT Polymerization and Polymer Chromatography

Yang Xue,Xiaohua Li,Shixian Zhang,Ruiwei Guo 한국고분자학회 2021 Macromolecular Research Vol.29 No.7

Chain transfer reactions are important side reactions in the radical polymerization of acrylates. Discrimination between interchain and intrachain transfer is still a challenge for the study of interchain transfer. A prepolymer, poly(benzyl acrylate) with hydroxy terminals (HO-PBzA), was designed and used in the reversible addition-fragmentation chain transfer (RAFT) polymerization of BzA to measure the interchain transfer degree, with benzyl N-carbazole dithiocarbamate (BCBD) as the RAFT agent. Liquid chromatography at critical conditions was used to separate and measure interchain transfer products and then BzA interchain transfer constants (Ctr) at different temperatures determined without other kinetic parameters. Experimental results showed that experimental parameters in RAFT polymerization, except the high dosage of BCBD, had no significant effects on the measured Ctr, which showed good repeatability. The Ctr of benzyl acrylate at 100-120 °C was in the order of 1-2×10-4 and the activation energy of Ctr was at 31.1 kJ∙mol-1.

Investigation of fl ow regime in debris bed formation behavior with nonspherical particles

Songbai Cheng,Pengfeng Gong,Shixian Wang,Jinjiang Cui,Yujia Qian,Ting Zhang,Guangyu Jiang 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.1

It is important to clarify the characteristics of flow regimes underlying the debris bed formation behaviorthat might be encountered in core disruptive accidents of sodium-cooled fast reactors. Although in ourprevious publications, by applying dimensional analysis technique, an empirical model, with itsreasonability confirmed over a variety of parametric conditions, has been successfully developed topredict the regime transition and final bed geometry formed, so far this model is restricted to predictionsof debris mixtures composed of spherical particles. Focusing on this aspect, in this study a new series ofexperiments using nonspherical particles have been conducted. Based on the knowledge and data obtained,an extension scheme is suggested with the purpose of extending the base model to cover theparticle-shape influence. Through detailed analyses and given our current range of experimental conditions,it is found that, by coupling the base model with this scheme, respectable agreement betweenexperiments and model predictions for the regime transition can be achieved for both spherical andnonspherical particles. Knowledge and evidence from our work might be utilized for the futureimprovement of design of an in-vessel core catcher as well as the development and verification of sodium-cooled fast reactor severe accident analysis codes in China.

Green Tea Extract Thermogenesis-Induced Weight Loss by Epigallocatechin Gallate Inhibition of Catechol-O-Methyltransferase

J. Shi,Y. Kakuda,Y. Jiang,Q. Shixian,B. VanCrey 한국식품영양과학회 2006 Journal of medicinal food Vol.9 No.4

Epidemiological studies have shown that intake of tea catechins is associated with a lower risk of cardiovas-cular disease. The antioxidative activity of tea-derived catechins has been extensively studied. Reports have shown that greentea extract intake is associated with increased weight loss due to diet-induced thermogenesis, which is generally attributed tothe catechin epigallocatechin gallate. That catechin-polyphenols are known to be capable of inhibiting catechol-O-methyl-transferase (the enzyme that degrades norepinephrine) is a possible explanation for why the green tea extract is effective instimulating thermogenesis by epigallocatechin gallate to augment and prolong sympathetic stimulation of thermogenesis.Knowledge about thermogenesis-induced weight loss produced by green tea’s epigallocatechin gallate and its ability to in-hibit catechol-O-methyltransferase is important for health benefits and for prolonging the action of norepinephrine in the synap-tic cleft.

Re-entrant relaxor ferroelectricity of methylammonium lead iodide

Haiyan Guo,Peixue Liu,Shichao Zheng,Shixian Zeng,Na Liu,Seungbum Hong 한국물리학회 2016 Current Applied Physics Vol.16 No.12

We have performed a piezoresponse force microscopy (PFM) study on methylammonium lead iodide (MAPbI3) thin films in normal (non-resonance, non-band-excitation) contact mode. In contrast to the ferroelectric Pb0.76Ca0.24TiO3 (PCT) control sample, a typical ferroelectric response was not observed. However, a nonlinear electric field dependence of the local PFM amplitude was found in MAPbI3, similar to PCT. An analysis combining results on structure, dielectric dispersion, and weak ferroelectricity demonstrates that MAPbI3 is actually a re-entrant relaxor ferroelectric which, upon cooling, enters into a relaxor phase below its ferroelectric phase transition at ~327 K, due to the balance between the long range ferroelectric order and structural methylammonium group orientational disorder. The ferroelectricity at room temperature is compromised due to the re-entrant relaxor behavior, causing the poor polarization retention or weak ferroelectricity. Our findings essentially conciliate the conflicting experimental results on MAPbI3's ferroelectricity and are beneficial both for basic understanding as well as for device applications.

Study on Wear Prediction of Shield Disc Cutter in Hard Rock and Its Application

Zhenyong Wang,Chenglong Liu,Yusheng Jiang,Linwei Dong,Shixian Wang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.3

It is important to enable the prediction of disc cutter wear during shield tunnelling through hard rock because such wear is associated with project delays and increased costs. Based on a theoretical analysis of Archard’s wear mechanism and Euler’s rotation theorem, a displacement equation of rock-breaking point A on the disc cutter ring is studied, and then a new wear prediction model is established combined with the theoretical analysis of the disc cutter force and wear test. The cutter wear prediction model is verified by using the data of two cases, and the results reveal that the errors between measured and predicted values are less than 25%. The research results also show that abrasive wear is the main wear mechanism (approximately 88%). In addition, the influence of fatigue wear is very small, accounting for only approximately 2%, which can be ignored. Finally, the maximum tunneling distance of disc cutters under different installation radii and penetration is studied using the model, and the results can be used as references for optimizing shield tunneling parameters and predicting the disc cutter replacement time.