• International Journal of Control, Automation, and Systems
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• v.6 no.1
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• pp.15-23
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• 2008

This paper considers the problem of delay-dependent guaranteed cost controller design for uncertain neutral systems with distributed delays. The system under consideration is subject to norm-bounded time-varying parametric uncertainty appearing in all the matrices of the state-space model. By constructing appropriate Lyapunov functionals and using matrix inequality techniques, a state feedback controller is designed such that the resulting closed-loop system is not only robustly stable but also guarantees an adequate level of performance for all admissible uncertainties. Furthermore, a convex optimization problem is introduced to minimize a specified cost bound. By matrix transformation techniques, the corresponding optimal guaranteed controller can be obtained by solving a linear matrix inequality. Finally, a simulation example is presented to demonstrate the effectiveness of the proposed approach.

• Journal of Power System Engineering
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• v.17 no.5
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• pp.128-137
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• 2013

Modern transmission technologies such as automated manual transmission(AMT) and dual clutch transmission(DCT) are interested to all manufactures due to their fuel efficiency and driver's convenience, especially in a hybrid system. AMT has advantages in that they have a high efficiency of manual transmissions(MT) and offer operation convenience similar to automatic transmissions(AT), but it has some disadvantages in that they have torque gap during gear shift and shift time. To reduce disadvantages, it is necessary to evaluate errors and characteristics as a developing simulation model before experimental verification. The purpose of this study is to develop virtual components and simulate the transient response of AMT. A dynamic AMT model and a control logic for an integrated vehicle model have been developed using Matlab/Simulink as a simulation platform. In this paper, the clutch model to describe the stick-slip transition mode and the transmission model to describe the neutral gear shifting is introduced and compared with each other.

• Journal of Astronomy and Space Sciences
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• v.7 no.2
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• pp.113-123
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• 1990

Two dimensional electrostatic model was used to investigate the interactions between beam electron and neutral plasma. It was found that results heavily depend on the beam density. When the beam electron density is lower than the ambient plasma beam density, many beam electrons exhibit vortex structure through beam-plasma interactions and can propagate into the ambient plasma easily from the injection area. On the other hand, when the beam density larget than that of the neutral ambient plasma, it was found that most of the beam electrons constitute return current and ion with much larger mass than that of the electron can be accelerated according to the magnetic field strength. Furthermore, as external field strength varies, it was found that propagation and interaction of the beam can show large dependence on it.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.711-717
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• 2011

Two dimensional simulation results of a capacitively coupled oxygen plasma in a cylindrical reactor geometry are presented. Detailed electron impact reaction rates, which strongly depend on electron energy, are computed from collision cross sections of electrons with $O_2$ and O. Through the coupling of a three moment plasma model with a neutral chemistry/transport model are predicted spatiotemporal distributions of both charged species (electron, $O_2{^+}$, $O^+$, $O_2{^-}$, and $O^-$) and neutral species including ground states ($O_2$ and O) and metastables, known to play important roles in oxygen plasma, such as $O_2(a^1{\Delta}_g)$, $O_2(b^1{{\Sigma}_g}^+)$, $O(^1D)$, and $O(^1S)$. The simulation results clearly verify the existence of a double layer near sheath boundaries in the electronegative plasma.

• Asia pacific journal of information systems
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• v.12 no.2
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• pp.197-216
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• 2002

Cooperativeness within an organization can be conceptualized as the degree of members' willingness to work with others. The simulation study investigates the relationships of cooperativeness with team performance at different levels of information redundancy by using a multi-agents model called Team-Soar. The model consists of a group of four individual Al agents situated in a network, which models a naval command and control team consisting of four members. The study used a $9{\times}3$ design in which agent cooperativeness was manipulated at nine levels by gradually replacing selfish team members with increasing numbers of neutral and cooperative members, while information redundancy was controlled at three different levels(i.e., low, medium, and high). Results of the Team-Soar simulation show that cooperation has positive impacts on team performance. Further, the results reveal that the impact of agent cooperativeness on team performance depends on the amount of information needed to be processed during the decision making process.

• Journal of Power Electronics
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• v.19 no.4
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• pp.989-999
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• 2019

This paper proposes a fault-tolerant control strategy with finite control set model predictive control (FCS-MPC) based on hierarchical optimization for five-level H-bridge neutral-point-clamped (5L-HNPC) inverter-fed induction motor drives. Fault-tolerant operation is analyzed, and the fault-tolerant control algorithm is improved. Adopting FCS-MPC based on hierarchical optimization, where the voltage is used as the controlled objective, called model predictive voltage control (MPVC), the postfault controller is simplified as a two layer control. The first layer is the voltage jump limit, and the second layer is the voltage following control, which adopts the optimal control strategy to ensure the current following performance and uniqueness of the optimal solution. Finally, simulation and experimental results verify that 5L-HNPC inverter-fed induction motor drives have strong fault tolerant capability and that the FCS-MPVC based on hierarchical optimization is feasible.

• Journal of the Semiconductor & Display Technology
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• v.2 no.4
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• pp.9-12
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• 2003

This paper describes a newly developed simulation environment for analysis and design of a plasma processing chamber based on first principles including complicated physical and chemical interactions of plasma, fluid dynamics of neutrals, and transport phenomena of particles. Capabilities of our simulator, named VIP-SEPCAD (Virtual Integrated Prototyping Simulation Environment for Plasma Chamber Analysis and Design), are demonstrated through a two dimensional simulation of an oxygen plasma chamber. VIP-SEPCAD can provide plasma properties such as spatiotemporal profiles of plasma density and potential, electron temperature, ion flux and energy, etc. By coupling neutral and particle transport models with a three moment plasma model, VIP-SEPCAD can also predict spatiotemporal profiles of chemically reactive species and particles exist in plasma.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1448-1457
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• 2018

Many researchers devote themselves to develop model-predictive direct power control (MPDPC) so as to accelerate the response speed of the grid-connected systems, but they are troubled its large computing amount. On the basis of MPDPC, dual MPDPC (DMPDPC) is presented in this paper. The proposed algorithm divides the conventional MPDPC into two steps. In the first step, the optimal sector is obtained, which contains the optimal switching state in three-level converters. In the second step, the optimal switching state in the selected sector is searched to trace reference active and reactive power and balance neutral point voltage. Simulation and experiment results show that the proposed algorithm not only decreases the computational amount remarkably but also improves the steady-state performance. The dynamic response of the DMPDPC is as fast as that of the MPDPC.

• Smart Structures and Systems
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• v.19 no.2
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• pp.115-126
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• 2017

In this paper, size dependent bending and free flexural vibration behaviors of functionally graded (FG) nanobeams are investigated using a nonlocal quasi-3D theory in which both shear deformation and thickness stretching effects are introduced. The nonlocal elastic behavior is described by the differential constitutive model of Eringen, which enables the present model to become effective in the analysis and design of nanostructures. The present theory incorporates the length scale parameter (nonlocal parameter) which can capture the small scale effect, and furthermore accounts for both shear deformation and thickness stretching effects by virtue of a hyperbolic variation of all displacements through the thickness without using shear correction factor. The material properties of FG nanobeams are assumed to vary through the thickness according to a power law. The neutral surface position for such FG nanobeams is determined and the present theory based on exact neutral surface position is employed here. The governing equations are derived using the principal of minimum total potential energy. The effects of nonlocal parameter, aspect ratio and various material compositions on the static and dynamic responses of the FG nanobeam are discussed in detail. A detailed numerical study is carried out to examine the effect of material gradient index, the nonlocal parameter, the beam aspect ratio on the global response of the FG nanobeam. These findings are important in mechanical design considerations of devices that use carbon nanotubes.

• Nuclear Engineering and Technology
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• v.21 no.1
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• pp.40-47
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• 1989

For the effective design of a beam forming structure of the negative-ion-based neutral beam injector, a computer program based on a particle simulation model is developed for the calculation of charged particle motions in the electrostatic fields. The motions of negative ions inside the acceleration tube of a multiple-aperture triode are computed at finite time steps. The electrostatic potentials are obtained from the Poisson's equation by the finite difference method. The successive overrelaxation method is used to solve the matrix equation. The particle and force weighting methods are used on a cloud-in-cell model. The optimum design of the beam forming structure has been studied by using this computer code for the various conditions of elctrodes. The effects of the acceleration-deceleration gap distance, the thickness of the deceleration electrode and the shape of the acceleration electrode on beam trajectories are exmined to find the minimum beam divergence. Some numerical illustrations are presented for the particle movements at finite time steps in the beam forming tubes. It is found in this particle simulation modelling that the shape of the acceleration electrode is the most significant factor of beam divergence.