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      • KCI등재

        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.

      • SCISCIESCOPUS

        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>

      • KCI등재

        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.

      • KCI등재

        Equilibrium, kinetics and thermodynamics study on biosorption of Cr(VI) by fresh biomass of Saccharomyces cerevisiae

        YunHai Wu,XianMiao,Li Jiang,Bin Li,ShiXun Feng 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.3

        The low cost fresh biomass of Saccharomyces cerevisiae (S. cerevisiae) was utilized for removal of Chromium ion from aqueous solution. The maximum biosorption was found to occur at pH 1.0. The biosorption capacity of S. cerevisiae was found to be 3.89 mg/g for a solution with initial Cr(VI) concentration of 50 mg/L at 35℃. Several biosorption isotherms were used to fit the equilibrium data, indicating biosorption relied mainly on physical adsorption onto heterogeneous surface. Kinetic models were evaluated and we found that pseudo-second-order rate kinetic model showed better correlation, and the biosorption of Cr(VI) was governed by film diffusion as well as intraparticle diffusion. Thermodynamic constants indicated that the biosorption was spontaneous and endothermic. Fourier transform infra-red (FTIR) spectroscopy was used to reveal the main function groups of biosorption, which were hydroxyl, amine groups, C-H of the alkanes, C=O and S=O.

      • KCI등재후보

        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<sub>nb</sub> ) , 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<sub>nb</sub> 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.

      • SCIESCOPUSKCI등재

        Production of Transgenic Chimeric Chickens Using Blastodermal Cells

        Yan, Haifeng,Lee, Chaeyoung,Xiao, Bingnan,Trefil, Pavel,Liu, Shixun,Kim, Younyoung,Wu, Xiaolin Asian Australasian Association of Animal Productio 2005 Animal Bioscience Vol.18 No.2

        A practical approach was proposed to produce transgenic chimeric chickens using blastodermal cells (BCs). The chicken BCs were mechanically dissociated and transferred into the recipient eggs that had been exposed to 500 rads irradiation of$^{60}Co$ and windowed on the equatorial plane. Chimeric chickens were generated using two models: the crosses (MXL) from Black Minors (ii,EE,b/b) ♂${\times}$Barred Leghorns (ii,ee,B/-) ♀ as donors and White Leghorns (WL, II) as acceptors (Model 1), or the Black Heifengs (BH, ii,EE,bb) as donors and Hua-xing white (HW, II) as recipients (Model 2). The treated eggs were incubated in their original shells in normal conditions until hatching. Green fluorescent protein (GFP) gene was transferred into the BCs derived from MXL and BH via lipofectamine and the pEGFP-C1, and transfection efficiency into the BCs was examined under a fluorescent microscope. Potential transgenic chimeras were selected based on the proposed methods in this study. Using the fresh BCs, the best rate of phenotypic chimeras was 6.7% and 26.0% in model-1 groups, and model-2 groups, respectively. We also described the optimized conditions for transfection. Although 30% of the BCs transfected in vitro emitted green light under an inverted fluorescent microscope, no embryos injected with the transfected BCs expressed foreign GFP gene at 3-4 days.

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