Distributed Consensus for High-order Agent Dynamics with Communication Delay

Zhenhua Wang,Yanli Zhu,Xinmin Song,Huaxiang Zhang 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.8

In this paper, consensus problem for high-order multi-agent systems that are at most critically unstable is researched under directed graph. Under the assumption that the delay appears in the communication and being unknown, a distributed protocol with delayed relative state information is proposed to solve the problem, and the design of the constant control gain is not utilizing the precise information of delay. If the agent dynamics has nonzero poles on the imaginary axis, an allowable delay bound is provided to guarantee consensus by studying the joint effects of agent dynamics, network topology and communication delay; otherwise, consensus is tolerant for any large yet bounded communication delay. Especially, it is shown that the unknown delay in communication is allowed to be time-varying if the network topology is undirected, and in this case the delay bound can be enlarged by improving the synchronizability of the undirected graph. Finally, two numerical examples are presented to illustrate the effectiveness of the theoretical result.

Consensus Problems for Discrete-time Agents with Communication Delay

Zhenhua Wang,Huanshui Zhang,Xinmin Song,Huaxiang Zhang 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.4

In this paper, consensus problems for first-order multi-agent systems with unstable pole are investigatedover undirected network, where the network is affected by communication delay. By jointly utilizing both thedelayed distributed state information and agent’s own historical input information in the protocol, sufficient conditionrelated to agent dynamic, network topology and communication delay is obtained for consensus, which isalso proven to be necessary in case of one step delay. Furthermore, the consensus problem is studied on conditionthat the delay is time-varying. Finally, numerical simulations are provided to demonstrate the effectiveness of theproposed theoretical results.

Research on a New Hybrid Intelligent Fault Diagnosis Method and its Application

Zhenhua Wang,Zhentao Liu,Xueyan Lan,Jian Liu,Shaowei Wang,Yangming Wu,Yanbing Xue 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.7

In order to overcome the shortcomings of slow convergence speed and easy falling into the local minimum values of the BP neural network, an improved particle swarm optimization(PSO) algorithm is proposed to optimize the redial basic function (RBF) neural network, in order to propose a new hybrid intelligent fault diagnosis(IMPSO-RBFNN) method. In the IMPSO-RBFNN method, the adaptive dynamic adjusting strategy is used to control the inertia weight of the PSO algorithm in order to an improved particle swarm optimization(IMPSO) algorithm. Then the IMPSO algorithm is selected to optimize the parameters of RBF neural network by encoding the particle and continuous iteration of the IMPSO algorithm in order to obtain the optimal combination values of the parameters of RBF neural network. The optimal combination values are regarded as the values of these parameters of the RBFNN for constructing the final IMPSO-RBFNN method. In order to test the effectiveness of the proposed IMPSO-RBFNN method, the data from bearing data center of CWRU is selected in this paper. The experiment results show that the IMPSO algorithm can effectively optimize the weights of RBFNN, the IMPSO-RBFNN method can accurately realize high precision fault diagnosis of rolling bearing.

Influence of Water on the Methanation Performance of Mo-Based Sulfur-Resistant Catalysts with and without Cobalt Additive

Haiyang Wang,Can Lin,Zhenhua Li,Baowei Wang,Xinbin Ma 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.1

The activities of Mo-based and Co-containing Mo-based catalysts for sulfur-resistant methanation in the presence and the absence of water are compared. When water was added to the Mo-based catalyst, its methanation activity decreased and the activity could not be recovered even after the water was removed from the system. However, for the Co-containing Mo-based catalysts, the formation of Co9S8 improved not only the methanation activity of the catalyst as active sites but also the stability of the catalyst especially in water-containing hydrogenation. The deactivation of the Mo-based catalyst in the presence of water is mainly due to reduction of the external acid sites and fewer molybdenum sulfide (MoS2) stacks. The addition of Co protects the active MoS2 phase, thereby preventing the deactivation of the catalyst in the presence of water.

Precursor effect on catalytic properties of Mo-based catalyst for sulfur-resistant methanation

Haiyang Wang,Xinbin Ma,Zhenhua Li,Baowei Wang,Shaodong Qin,Shouli Sun,Qi Sun 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.12

The catalytic activity of Mo-based catalysts prepared from (NH4)6Mo7O24 and (NH4)2MoS4 was com-pared in the sulfur resistant methanation process. The catalyst using oxide precursor had relatively higher activity thanthe catalyst using sulfide precursor, and the presulfidation procedure almost had no effect on the catalytic performanceof the catalyst using oxide precursor. In view of the characterization results, it could be supposed that the amorphousMoS2 was more active for sulfur-resistant methanation than the crystalline MoS2. The molybdenum sulfides and oxideswith lower valence states (Mo4+, Mo5+) could be responsible for the catalytic activity and make a possible contributionto the carbon monoxide methanation in the reaction condition.

Acute and repeated dose 26-week oral toxicity study of 20(S)-ginsenoside Rg3 in Kunming mice and Sprague-Dawley rats

Li, Chunmei,Wang, Zhezhe,Li, Guisheng,Wang, Zhenhua,Yang, Jianrong,Li, Yanshen,Wang, Hongtao,Jin, Haizhu,Qiao, Junhua,Wang, Hongbo,Tian, Jingwei,Lee, Albert W.,Gao, Yonglin The Korean Society of Ginseng 2020 Journal of Ginseng Research Vol.44 No.2

Background: 20(S)-ginsenoside-Rg3 (C₄₂H₇₂O₁₃), a natural triterpenoid saponin, is extracted from red ginseng. The increasing use of 20(S)-ginsenoside Rg3 has raised product safety concerns. Methods: In acute toxicity, 20(S)-ginsenoside Rg3 was singly and orally administrated to Kunming mice and Sprague-Dawley (SD) rats at the maximum doses of 1600 mg/kg and 800 mg/kg, respectively. In the 26-week toxicity study, we used repeated oral administration of 20(S)-ginsenoside Rg3 in SD rats over 26 weeks at doses of 0, 20, 60, or 180 mg/kg. Moreover, a 4-week recovery period was scheduled to observe the persistence, delayed occurrence, and reversibility of toxic effects. Results: The result of acute toxicity shows that oral administration of 20(S)-ginsenoside Rg3 to mice and rats did not induce mortality or toxicity up to 1600 and 800 mg/kg, respectively. During a 26-week administration period and a 4-week withdrawal period (recovery period), there were no significant differences in clinical signs, body weight, food consumption, urinalysis parameters, biochemical and hematological values, or histopathological findings. Conclusion: The mean oral lethal dose (LD₅₀) of 20(S)-ginsenoside Rg3, in acute toxicity, is above 1600 mg/kg and 800 mg/kg in mice and rats, respectively. In a repeated-dose 26-week oral toxicity study, the no-observed-adverse-effect level for female and male SD rats was 180 mg/kg.

Fracture Properties of Wide-Notch Concrete Beams strengthened with Near-Surface Mounted CFRP Rebar

Zhenhua Ren,Xiantao Zeng,Junbo Sun,Jun Wang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.11

Carbon fiber reinforced polymer (CFRP) is a promising engineering material nowadays. This study carried out four-point-bending fracture experiment on wide-notch-concrete beams reinforced with near-surface mounted (NSM) CFRP rebar, aiming at exploring the effect of CFRP rebar on beam fracture characteristics. The test comprised four groups concrete beam specimens (three for each) with varying reinforcing methodologies. The first group specimens were common concrete beams strengthened by one near-surface mounted CFRP bar, while the second group consisted of common concrete beams strengthened by two near-surface mounted CFRP bars. On the issue of the third group, there were three wide-notch concrete beams strengthened with one near-surface mounted CFRP bar. Lastly, three wide-notch concrete beams strengthened with two near-surface mounted CFRP bars form the group four. The study proposed various equations about the rectangular concrete beams strengthened with near-surface mounted CFRP rebar under tension-shearing condition. For both open cracks and closed cracks, the equations concluded stress intensity factor as well as extending angle in mode I and II crack types. Four-point-bending fracture experiments for wide-notch-concrete beams and numerical simulation experiments were included in this research. This research exhibited expanding direction of wing type crack under effective shearing stress by the superposition model of crack tip stress intensity factor and stress intensity factor. Four-point-bending fracture tests for wide-notch-concrete beams and numerical simulation tests are finished in this research. The tests demonstrate characteristics of crack expanding direction, extending angle, vertical displacement, maximum normal stress, shear strain rate, distribution of plastic zones. Combining the theory and reality, the experimental results were in close agreement with the numerical research.

Sharing and Privacy in PHRs: Efficient Policy Hiding and Update Attribute-based Encryption

( Zhenhua Liu ),( Jiaqi Ji ),( Fangfang Yin ),( Baocang Wang ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.1

Personal health records (PHRs) is an electronic medical system that enables patients to acquire, manage and share their health data. Nevertheless, data confidentiality and user privacy in PHRs have not been handled completely. As a fine-grained access control over health data, ciphertext-policy attribute-based encryption (CP-ABE) has an ability to guarantee data confidentiality. However, existing CP-ABE solutions for PHRs are facing some new challenges in access control, such as policy privacy disclosure and dynamic policy update. In terms of addressing these problems, we propose a privacy protection and dynamic share system (PPADS) based on CP-ABE for PHRs, which supports full policy hiding and flexible access control. In the system, attribute information of access policy is fully hidden by attribute bloom filter. Moreover, data user produces a transforming key for the PHRs Cloud to change access policy dynamically. Furthermore, relied on security analysis, PPADS is selectively secure under standard model. Finally, the performance comparisons and simulation results demonstrate that PPADS is suitable for PHRs.

A Virtual Spring Method for the Multi-robot Path Planning and Formation Control

Zhenhua Pan,Di Wang,Hongbin Deng,Kewei Li 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.5

Path planning is a challenging and critical issue in robotics, which involves computing a collision-freepath between initial and target. The formation control ensures the robots’ collaborative working. To address thesetwo problems, an efficient virtual spring method for multi-robot path planning and formation control is proposed,and the interaction dynamic model is established to describe both logical and physical topology of the network. Based on the network model, the virtual spring method control law is designed, and aiming at the non-reachableand local minima problems, the virtual target search method is proposed. The robots can calculate an optimal pathto the target in the predefined formation based on the control law and the virtual target search method. Finally, aseries of simulation results confirm that the approaches proposed in this paper are feasible and efficient in the pathplanning and formation control for the multi-robot systems.

Wake effects of an upstream bridge on aerodynamic characteristics of a downstream bridge

Zhenhua Chen,Zhenyun Lin,Haojun Tang,Yongle Li,Bin Wang 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.6

To study the wake influence of an upstream bridge on the wind-resistance performance of a downstream bridge, two adjacent long-span cable-stayed bridges are taken as examples. Based on wind tunnel tests, the static aerodynamic coefficients and the dynamic response of the downstream bridge are measured in the wake of the upstream one. Considering different horizontal and vertical distances, the flutter derivatives of the downstream bridge at different angles of attack are extracted by Computational Fluid Dynamics (CFD) simulations and discussed, and the change in critical flutter state is further studied. The results show that a train passing through the downstream bridge could significantly increase the lift coefficient of the bridge which has the same direction with the gravity of the train, leading to possible vertical deformation and vibration. In the wake of the upstream bridge, the change in lift coefficient of the downstream bridge is reduced, but the dynamic response seems to be strong. The effect of aerodynamic interference on flutter stability is related to the horizontal and vertical distances between the two adjacent bridges as well as the attack angle of incoming flow. At large angles of attack, the aerodynamic condition around the downstream girder which may drive the bridge to torsional flutter instability is weakened by the wake of the upstream bridge, and the critical flutter wind speed increases at this situation.