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Adaptive Sliding Mode Control Using Radial Basis Function Network for Container Cranes
Ngo Phong Nguyen,Quang Hieu Ngo,Chi Ngon Nguyen 제어로봇시스템학회 2017 제어로봇시스템학회 국제학술대회 논문집 Vol.2017 No.10
An adaptive sliding mode control scheme using radial basis function network (RBFN) for container cranes is investigated in this study. Here, a sliding surface is designed in such a way that sway motion of the payload is incorporated into the trolley dynamics. In addition, to relax the requirement of mathematical model in the design of a traditional sliding mode control (SMC) system, a neural network compensator, obtained by a radial basis function network and an adaption law, which approximates the nonlinear functions in the traditional SMC control law. This control scheme guarantees the asymptotic stability of the closed-loop system based on Lyapunov theory. To illustrate the efficiency of proposed control strategy, simulation results are provided.
Autonomous Offshore Container Crane System Using a Fuzzy-PD Logic Controller
Ngo Phong Nguyen,Trong Nghia Phan,Quang Hieu Ngo 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10
A Fuzzy-PD control strategy for an offshore container crane is investigated in this study. The offshore crane is used to handle containers between a mega container ship (called the “mother ship”) and a smaller ship (called the “mobile harbor”), which is equipped with container crane. The concept of the mobile harbor is a floating form that has the capability of transferring cargo to the local harbor from a large ship that is anchored in a nearby sea, thereby minimizing the port congestion and also eliminating the need of expanding outwards. The control objective during the loading and unloading process is to keep the payload in the desired region in the presence of ship motions. A new control strategy which is a combination of a Fuzzy controller, PD controller and compensation mechanism, is proposed as well. A Fuzzy controller plays a main role in creating the appropriate voltage, based on the dynamics and knowledge of an experienced designer, for guarantees not only prompt suppression of load swing but also accurate control of container crane position. In addition, a classical PD controller is used to tune the value of state variables into suitable range before becoming the inputs of the fuzzification process. This control scheme guarantees the stability of the closed-loop system. Simulation and experimental results are provided to verify the effectiveness of the proposed control system for offshore container cranes.
Active Control of an Offshore Container Crane
Ngo Phong Nguyen,Quang Hieu Ngo,Quang Phuc Ha 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10
Open sea loading/unloading cargos provides a potential solution to tack the problem related with port construction, expansion and congestion. This process involves a crane attached to a mobile harbor (MH) which can dynamically handle container from a large container anchored in deep water. The control objective during the operation is to maintain the payload in the desired position in the presence of ocean waves. This paper presents a robust control strategy for trajectory tracking and sway suppression of an offshore container crane. A fuzzy sliding mode control law is proposed for that. Experimental results are provided to indicate the efficiency of the proposed control strategy.
Phong Anh NGUYEN,Anh Hoang NGUYEN,Thanh Phu NGO,Phuong Vu NGUYEN 한국유통과학회 2019 The Journal of Asian Finance, Economics and Busine Vol.6 No.3
The study aims to examine the impact of productivity in addition to the policy of increasing the foreign investors’ ownership rate on the performance of businesses which were listed on Vietnam's stock exchange market from 2010 to 2017. With the database of 3.961 observations, the study employs a statistical method – multiple regression to estimate the relationship between labor productivity, foreign ownership as well as other firm-level characteristics and firm performance. Research findings show that increasing labor productivity and increasing foreign ownership rates help increase firm performance. In addition, except for financial leverage, variables such as liquidity and firm size have positive effects on firm performance measured by Tobin’s Q. These findings have theoretical contributions and practical implications for managers, investors and government in Vietnam. Managers should pay attention to improving labor productivity through employing incentive mechanisms, building a good working environment, investing in technology, etc. in order to enhance the firm performance. Investors could utilize the labor productivity and foreign ownership indicators to select stocks of good companies for investment. For Vietnamese government, relaxing the limit of foreign ownership and accelerating the divesting of State capital in Stateowned enterprises could help increase the investment scale of foreign investors and resulting in positive effects on the firm performance.