SVPWM Overmodulation Region II Control Method Based on the Chaos Ant Colony Algorithm

Zhang Siyan,Wang Xudong,Gao Junshan,Wu Xiaogang,Liu Jinfeng 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.4

The control method of space vector pulse width modulation (SVPWM) overmodulation region II has the disadvantages of a complicated process and large harmonic content. To solve these problems, this paper proposes an SVPWM overmodulation region II control method based on the chaos ant colony algorithm. Since the multiple control of the rotation angle ( θ ) in the SVPWM algorithm will bring about diff erent implementation eff ects, this paper uses the chaotic ant colony algorithm to optimize the control process of θ in overmodulation region II and summarizes the θ equations in each sector to achieve the goal of suppressing the total harmonic distortion ( THD ) in the output voltage vector. Simulation and experimental results demonstrate that this method makes the amplitude of the output voltage vector relatively continuous, thereby avoiding the harmonic content caused by the voltage jump of the traditional algorithm in overmodulation region II.

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.

MIMO Ad Hoc Networks: Medium Access Control, Saturation Throughput, and Optimal Hop Distance

Ming Hu,Junshan Zhang 한국통신학회 2004 Journal of communications and networks Vol.6 No.4

3D-Printed Prosthesis Replacement for Limb Salvage after Radical Resection of an Ameloblastoma in the Tibia with 1 Year of Follow Up: A Case Report

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.

Preparation of Manganese Dioxide Supercapacitors by Secondary Construction of Three-Dimensional Substrates and Ion Embedding

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).

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.

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>

Distributed Link Scheduling Under SINR Model in Multihop Wireless Networks

Jin-Ghoo Choi,Changhee Joo,Junshan Zhang,Shroff, Ness B. IEEE 2014 IEEE/ACM transactions on networking Vol.22 No.4

<P>Link adaptation technologies, such as Adaptive Modulation and Coding (AMC) and Multiple-Input-Multiple-Output (MIMO), are used in advanced wireless communication systems to achieve high spectrum efficiency. Communication performance can be improved significantly by adaptive transmissions based on the quality of received signals, i.e., the signal-to-interference-plus-noise ratio (SINR). However, for multihop wireless communications, most link scheduling schemes have been developed under simplified interference models that do not account for accumulative interference and cannot fully exploit the recent advances in PHY-layer communication theory. This paper focuses on developing link scheduling schemes that can achieve optimal performance under the SINR model. One key idea is to treat an adaptive wireless link as multiple parallel virtual links with different signal quality, building on which we develop throughput-optimal scheduling schemes using a two-stage queueing structure in conjunction with recently developed carrier-sensing techniques. Furthermore, we introduce a novel three-way handshake to ensure, in a distributed manner, that all transmitting links satisfy their SINR requirements. We evaluate the proposed schemes through rigorous analysis and simulations.</P>