Distributed Coordination of Heterogeneous Multi-agent Systems with Dynamic Quantization and L2-L∞ Control

Shixun Xiong,Qingxian Wu,Yu-Hui Wang 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.10

This paper studies the dynamic output feedback consensus control problem of linear heterogeneous multi-agent systems under the leader-follower formation with a dynamic quantizer. In the practical engineering, the status information of the unmanned aircraft vehicle (UAV) and the unmanned underground vehicle (UGV) is normally unmeasurable, which is difficult to design the state feedback controller for the UAV-UGV formation. Besides, in the communication topology of the leader-follower formation based on UAVs and UGVs, the signals should be quantized in each follower. However, the traditional static quantizer has a quantization error, which affects the formation stability. Therefore, the control objective is to guarantee the UAV-UGV formation tracking consensus while improving the precision of the quantization. First, the followers and leader systems are based on the discretetime model, and the output trajectory of the leader is time-varying. Then, a dynamic output feedback controller is provided with a dynamic quantizer to guarantee the tracking performance of the heterogeneous multi-agent systemswith a leader. The followers can asymptotically track the leader system with L2 − L∞ control gains by solving a set of linear matrix inequalities (LMIs). Finally, simulation results demonstrate the effectiveness of the designed control strategies.

Improved and Extended Range Scale Algorithm for Wireless Cellular Location

Shixun Wu,Jiping Li,Shouyin Liu,Jong-Wha Chong IEEE 2012 IEEE communications letters Vol.16 No.2

<P>The range scale algorithm (RSA) proposed in 2004 is a constrained optimization problem with only three base stations (BSs). In this letter, by introducing a new variable to replace the square term, the quadratic objective function of the constrained optimization problem in RSA is turned into a linear objective function. Then the computational complexity is reduced and the performance is improved. Moreover, when the number of BSs is larger than three, we construct a new objective function and give the corresponding constraints. So the RSA is extended for more BSs and the performance of positioning is improved significantly. Simulation results demonstrate that our proposed algorithms improve the location accuracy over traditional algorithms in different Non-line-of-sight (NLOS) environments.</P>

Optimization design of graphene with adjustable hydrophilic properties by finite elements analysis

Shixun Sun,Jiaming Song,Naiyu Cui,Xinyue Lu,Xuehan Li,Heng Zhang,Heng Bo Jiang 대한치과재료학회 2021 대한치과기재학회 학술대회 Vol.2021 No.4

Transmission Line Modeling and Algorithm Analysis Considering Parameter Asymmetry and Transient High-frequency Components

Mo Shixun,Lv Zhipeng,Han Kunlun,Yuan Rongji,Yang Hao,Jiang Kunping,Liang Zhenshen 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.2

When the power system is disturbed or the operation mode is changed, the electromagnetic transient process will occur, which will lead to the high frequency transient component and aff ect the protection and control of the power system. Therefore, attention should be paid to the analysis of high-frequency transient components when modeling and analyzing the system model. In view of the fact that the symmetrical-component theory is not suitable for asymmetric transmission lines and the phasor method is not suitable for transient analysis and calculation, this paper uses the phase coordinate approach and Laplace transform to derive the node voltage equation of three-phase π type transmission lines in frequency domain, which can be used to calculate the transient response of transmission lines caused by the change of operation mode or disturbance. And vectorized NILT is used to calculate the time domain solution, which greatly improves the calculation speed. The calculated results are basically consistent with those of ATP-EMTP, and can fully refl ect the transient characteristics. This method lays a foundation for analyzing the infl uence of high frequency transient components on power system and fault analysis considering transient process.

Hybrid TOA/AOA Cooperative Mobile Localization in 4G Cellular Networks

Wu, Shixun,Wang, Shuliang,Xu, Kai,Wang, Honggang The Institute of Electronics and Information Engin 2013 IEIE Transactions on Smart Processing & Computing Vol.2 No.2

this study examined hybrid Time of Arrival/Angle of Arrival (TOA/AOA) localization technique in a cellular network. Based on the linearized equations from the TOA and AOA measurements, the weighted least square (WLS) method is proposed to obtain the location estimation of a mobile station (MS) by analyzing the statistical properties of the error vector in Line of Sight (LOS) and Non-line of Sight (NLOS) environments, respectively. Moreover, the precise expression of the Cramer-Rao lower bound (CRLB) for hybrid TOA/AOA measurements in different LOS/NLOS conditions was derived when the LOS error is a Gaussian variable and the NLOS error is an exponential variable. The idea of cooperative localization is proposed based on the additional information from short-range communication among the MSs in fourth generation (4G) cellular networks. Therefore, the proposed hybrid TOA/AOA WLS method can be improved further with the cooperative scheme. The simulation results show that the hybrid TOA/AOA method has better performance than the TOA only method, particularly when the AOA measurements are accurate. Moreover, the performance of the hybrid TOA/AOA method can be improved further by the cooperative scheme.

Effect of fabrication conditions on I-V properties for ZnO varistor with high concentration additives by sol-gel technique

Jincang Zhang,Shixun Cao,Ruiying Zhang,Liming Yu,Chao Jing 한국물리학회 2005 Current Applied Physics Vol.5 No.4

Polycrystalline nano-grain-boundary multi-doping ZnO-based nonlinear varistors with higher concentration additives have beenfabricated by solgel and standard solid-state reaction method, of which the best sample has a very high threshold voltage ofEb ¼ 3300 V/mm. The eect of sintering processes, sintering temperature and sintering time, and that of additive concentration ofBi2O3 on Eb of the samples are systematically investigated. The results show that the great merit of solgel method is its highthreshold voltage obtained by a lower sintering temperature than the solid-state reaction method. The present work also shows thatve phases including solid-state sintering, rich Bi liquid phase formation and ZnO as well as other additive dissolution, ZnO graingrowth, the secondary phase sucient formation and evolution have been experienced at dierent sintering temperatures. The holetype defect and nonhomogeneity of the microstructure will lead to the decrease of threshold voltage, i.e., the grain size and thehomogeneity of the material will be important factors and directly aect the characteristic of the varistor. The sintering charac-teristic and the inuence of Bi2O3 content on the threshold voltage are also discussed..

A Dynamical Hybrid CAC Scheme and Its Performance Analysis for Mobile Cellular Network with Multi-Service

( Jiping Li ),( Shixun Wu ),( Shouyin Liu ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.6

Call admission control (CAC) plays an important role in mobile cellular network to guarantee the quality of service (QoS). In this paper, a dynamic hybrid CAC scheme with integrated cutoff priority and handoff queue for mobile cellular network is proposed and some performance metrics are derived. The unique characteristic of the proposed CAC scheme is that it can support any number of service types and that the cutoff thresholds for handoff calls are dynamically adjusted according to the number of service types and service priority index. Moreover, timeouts of handoff calls in queues are also considered in our scheme. By modeling the proposed CAC scheme with a one-dimensional Markov chain (1DMC), some performance metrics are derived, which include new call blocking probability ( P_nb ) , forced termination probability (PF), average queue length, average waiting time in queue, offered traffic utilization, wireless channel utilization and system performance which is defined as the ratio of channel utilization to Grade of Service (GoS) cost function. In order to validate the correctness of the derived analytical performance metrics, simulation is performed. It is shown that simulation results match closely with the derived analytic results in terms of P_nb and PF. And then, to show the advantage of 1DMC modeling for the performance analysis of our proposed CAC scheme, the computing complexity of multi-dimensional Markov chain (MDMC) modeling in performance analysis is analyzed in detail. It is indicated that state-space cardinality, which reflects the computing complexity of MDMC, increases exponentially with the number of service types and total channels in a cell. However, the state-space cardinality of our 1DMC model for performance analysis is unrelated to the number of service types and is determined by total number of channels and queue capacity of the highest priority service in a cell. At last, the performance comparison between our CAC scheme and Mahmoud ASH`s scheme is carried out. The results show that our CAC scheme performs well to some extend.

Influence of the camber trailing-edge wings on the motion performance of underwater gliders

Liu Yuhong,Xu Shixun,Tian Shan,Lan Shiquan,Deng Shihan,Liu Shuhe,Feng Dengxue 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1

Wings are the main source of lift for Underwater Gliders (UGs) and play a decisive role in their motion performance. The wings of UGs are generally rectangular and symmetrical airfoils. In this study, a mini- UG with flexible camber trailing-edge wings was proposed and developed to investigate the influence of the trailing edge of the wings on the motion performance of UGs. Flexible deformation of the trailing edge was realized using a steer-by-wire actuator. The test results showed that the trailing edge of the wing could realize maximum upward/downward sloping angles of þ16/16. By combining computational fluid dynamics simulations and tank experiments, this study obtained the glide efficiency (in liftdrag ratio) and stable margins of a mini-UG with variable camber trailing-edge wings. The results showed that the angles of attack corresponding to the minimum lift-to-drag ratio were all negative in cases of downward sloping and positive in cases of upward sloping. Moreover, the suitable camber of the trailing edge, that is, downward-sloping trailing edge on descending glides and upward-sloping trailing edge on ascending glides, can not only greatly improve glide efficiency but also benefit flight stability. Tank experiments showed that the lift-to-drag ratio of the mini-UG with appropriate variable camber trailing-edge wings can be increased by at least 25% compared to those with a symmetrical airfoil.

NMR Study of Magnetic Properties of Eu1−xSrxMnO3 (0 ≤ x ≤ 0.5)

Kenji Shimizu,Masanori Yamaguchi,Shujuan Yuan,Shixun Cao 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3

The perovskite manganite EuMnO3 is known to be a compound with a narrow eg-band width due to small ionic radius of Eu3+ compared to La3+. The Eu1−xSrxMnO3 compounds show complex magnetic properties, depending on the Sr concentration x. We have carried out 55Mn spin-echo nuclear magnetic resonance (NMR) measurements on polycrystalline Eu1−xSrxMnO3 (0 ≤ x≤ 0.5) compounds at 4.2 or 1.4 K in order to clarify the microscopic local magnetic state of the Mn ions. NMR spectra have been observed in the frequency range from 250 MHz to 400 MHz. For the A-type antiferromagnetic EuMnO3, the resonance frequency is about 260 MHz, which is much lower than that observed for Mn3+ in La1−xSrxMnO3. For 0.1 ≤ x ≤ 0.4, the resonance lines corresponding to Mn4+ and Mn3+ have been observed at about 315 MHz and 390 MHz, respectively. Furthermore, the spectra originating from Mn2+ have been observed around 590 MHz for 0.1 ≤ x ≤ 0.4. For Eu0.5Sr0.5MnO3, the NMR spectrum spreads widely with several distinct peaks in the frequency range from 250 MHz to 410 MHz, which shows that the compound is in an inhomogeneous state due to competition between the antiferromagnetic and the ferromagnetic states.

Magnetic alignment of MnBi crystals and magnetic properties of MnBi-Bi composites

Yongsheng Liu,Jincang Zhang,Zhongming Ren,Shixun Cao,Xiaoyong Zhang,Guangqiang Jia,Kang Deng,Xi Li,Junxi Zhang 한국물리학회 2007 Current Applied Physics Vol.7 No.5

Below Curie temperatureTC, MnBi crystals are aligned alongc-axis in a Bi matrix under a fabrication eldHfof 0.5 T. AboveTC,this alignment is also accomplished by quenching under a highHfof 10 T. Such a method has a prominent feature that MnBi crystalsgrow preferentially and congregate along theHfdirection. Magnetic testing shows a pronounced anisotropy in magnetization in direc-tions normal and parallel toHf, resulting from the alignment. In the case of the alignment belowTC,Hfincreases the transition temper-ature of spin-reorientation and the change in magnetization.