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Precise asymptotics on spectral statistics of random matrices
Junshan Xie 한국통계학회 2014 Journal of the Korean Statistical Society Vol.43 No.2
This paper focuses on the limiting properties of the spectral statistics of Wigner matricesand sample covariance matrices. Following the ideas of Gut and Spˇataru (2000a, b), Gutand Steinebach (2013) and Chow (1988) on precise asymptotics of i.i.d. random variablesin the context of complete convergence and moment convergence, we will establish thecorresponding results on the spectral statistics of random matrices.
Dehong Feng,Junshan He,Chenyu Zhang,Ling Wang,Xiaofeng Gu,Yu Guo 연세대학교의과대학 2019 Yonsei medical journal Vol.60 No.9
Ameloblastoma in the tibia is rare. Limb reconstruction after tumor resection is challenging in terms of selection of the operativemethod. Here, we report a case of radical resection of an ameloblastoma in the mid-distal tibia combined with limb salvage usinga three-dimensional (3D)-printed prosthesis replacement, with 1-year follow-up results. After receiving local institutional reviewboard approval, a titanium alloy prosthesis was designed using a computer and manufactured with 3D-printing technology. Duringthe operation, the stem of the prosthesis was inserted closely into the proximal tibial medullary cavity. Then, the metal anklemortise and the talus were compacted closely. Radiographic results at 1-year follow up showed that the prosthesis was wellplaced, and no loosening was observed. The Musculoskeletal Tumor Society (MSTS) 93 functional score was 26 points, and thefunctional recovery percentage was 86.7%. Computer-assisted 3D-printing technology allowed for more volume and structuralcompatibility of the prosthesis, thereby ensuring a smooth operation and initial prosthetic stabilization. During the follow up, thepresence of bone ingrowths on the porous surface of some segments of the prosthesis suggested good outcomes for long-term biologicalintegration between the prosthesis and host bone.
( Jingwen Liu ),( Junshan Tan ),( Jiaohua Qin ),( Xuyu Xiang ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.8
The traditional method of smoke image recognition has low accuracy. For this reason, we proposed an algorithm based on the good group of IMFOA which is GMFOA to optimize the parameters of SVM. Firstly, we divide the motion region by combining the three-frame difference algorithm and the ViBe algorithm. Then, we divide it into several parts and extract the histogram of oriented gradient and volume local binary patterns of each part. Finally, we use the GMFOA to optimize the parameters of SVM and multiple kernel learning algorithms to Classify smoke images. The experimental results show that the classification ability of our method is better than other methods, and it can better adapt to the complex environmental conditions.
Distributed CSMA Algorithms for Link Scheduling in Multihop MIMO Networks Under SINR Model
Dajun Qian,Dong Zheng,Junshan Zhang,Shroff, N. B.,Changhee Joo IEEE 2013 IEEE/ACM transactions on networking Vol.21 No.3
<P>In this paper, we study distributed scheduling in multihop multiple-input-multiple-output (MIMO) networks. We first develop a “MIMO-pipe” model that provides the upper layers a set of rates and signal-to-interference-plus-noise ratio (SINR) requirements that capture the rate-reliability tradeoff in MIMO communications. The main thrust of this paper is then dedicated to developing distributed carrier sense multiple access (CSMA) algorithms for MIMO-pipe scheduling under the SINR interference model. We choose the SINR model over the extensively studied protocol-based interference models because it more naturally captures the impact of interference in wireless networks. The coupling among the links caused by the interference under the SINR model makes the problem of devising distributed scheduling algorithms very challenging. To that end, we explore the CSMA algorithms for MIMO-pipe scheduling from two perspectives. We start with an idealized continuous-time CSMA network, where control messages can be exchanged in a collision-free manner, and devise a CSMA-based link scheduling algorithm that can achieve throughput optimality under the SINR model. Next, we consider a discrete-time CSMA network, where the message exchanges suffer from collisions. For this more challenging case, we develop a “conservative” scheduling algorithm by imposing a more stringent SINR constraint on the MIMO-pipe model. We show that the proposed conservative scheduling achieves an efficiency ratio bounded from below.</P>
MIMO Ad Hoc Networks: Medium Access Control, Saturation Throughput, and Optimal Hop Distance
Hu, Ming,Zhang, Junshan The Korea Institute of Information and Commucation 2004 Journal of communications and networks Vol.6 No.4
In this paper, we explore the utility of recently discovered multiple-antenna techniques (namely MIMO techniques) for medium access control (MAC) design and routing in mobile ad hoc networks. Specifically, we focus on ad hoc networks where the spatial diversity technique is used to combat fading and achieve robustness in the presence of user mobility. We first examine the impact of spatial diversity on the MAC design, and devise a MIMO MAC protocol accordingly. We then develop analytical methods to characterize the corresponding saturation throughput for MIMO multi-hop networks. Building on the throughout analysis, we study the impact of MIMO MAC on routing. We characterize the optimal hop distance that minimizes the end-to-end delay in a large network. For completeness, we also study MAC design using directional antennas for the case where the channel has a strong line of sight (LOS) component. Our results show that the spatial diversity technique and the directional antenna technique can enhance the performance of mobile ad hoc networks significantly.
Adaptive Fault-tolerant Control for Trajectory Tracking and Rectification of Directional Drilling
Chi Zhang,Wei Zou,Ningbo Cheng,Junshan Gao 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.1
Motivated by the increasing demands on complex borehole trajectories in oil and gas directional drilling, an adaptive fault-tolerant control (AFTC) method for drilling trajectory tracking and rectification of rotary steerable system (RSS) is proposed by adopting actor-critic reinforcement learning (RL) and integral sliding mode control (ISMC) in the presence of system uncertainties and fault signals. Considering a discrete delay differential equation (DDE) with distance delays, uncertainties and fault signals, first we design an online learning framework via actor-critic RL and radial basis function neural network (RBFNN) in order to make drill bit can track pre-designed trajectory accurately and smoothly. Then in order to handle the fault signals problem, we utilize ISMC to eliminate it as weak as possible and rectify drilling trajectory which may derivate original direction caused by it. The system stability and convergence have been analyzed to ensure uniformly ultimately boundedness of tracking errors and fault-tolerant control signals. The proposed method would have wide application potentials in realizing the trajectory tracking and rectification with automatic operations of directional drilling. The effectiveness and accuracy of it are validated by simulation results with ramp and sine input signals.
Shi Yihan,Zhang Ming,Zhao Junshan,Zhang Liu,Cui Xumei,Zhu Xinhua,Jin Dandan,Gong Jiali,Yang Dingyu,Li Jitao 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.5
This work used a simple electrochemical reduction method to secondary construct the reduced nickel base (rNi Base) on nickel foam with a nano-core structure. The secondarily constructed base has a large specific surface area, which can increase the mass utilization of the active material. The rNi Base was used as a base for the reduction of nickel on Na+, K+, and NH+4, respectively. MnO2 was electrodeposited under three different cation pre-intercalation treatments, and the mechanism of the effect of different monovalent cations to guide the growth of MnO2 materials was investigated. Finally, rNi/MnO2&Na+ electrode with a special nano cauliflower structure was obtained. The special nanostructure of the electrode enhances its electrochemical performance, possessing 598 F g− 1 ultra-high specific capacitance at a current density of 1 A g− 1 and a high specific capacitance of 307.5 F g− 1 at a high current density of 20 A g− 1, and high specific capacitance maintenance rate of 92.7% after 500 cycles of charging and discharging at a current density of 2 A g− 1. In addition, the symmetrical supercapacitor assembled with this electrode has a very high specific capacitance (401.1 F g− 1 at a current density of 1 A g− 1) and energy density (80.22Wh kg− 1 at a power density of 599.99 W kg− 1).