scholarly journals Physics-based control of neoclassical tearing modes on TCV

Author(s):  
Mengdi Kong ◽  
Federico Felici ◽  
Olivier Sauter ◽  
Cristian Galperti ◽  
Trang Vu ◽  
...  

Abstract This paper presents recent progress on the studies of neoclassical tearing modes (NTMs) on TCV, concerning the new physics learned and how this physics contributes to a better real-time (RT) control of NTMs. A simple technique that adds a small (sinusoidal) sweeping to the target electron cyclotron (EC) beam deposition location has proven effective both for the stabilization and prevention of 2⁄1 NTMs. This relaxes the strict requirement on beam-mode alignment for NTM control, which is difficult to ensure in RT. In terms of the EC power for NTM stabilization, a control scheme making use of RT island width measurements has been tested on TCV. NTM seeding through sawtooth (ST) crashes or unstable current density profiles (triggerless NTMs) has been studied in detail. A new NTM prevention strategy utilizing only transient EC beams near the relevant rational surface has been developed and proven effective for preventing ST-seeded NTMs. With a comprehensive modified Rutherford equation (co-MRE) that considers the classical stability both at zero and finite island width, the prevention of triggerless NTMs with EC beams has been simulated for the first time. The prevention effects are found to result from the local effects of the EC beams (as opposed to global current profile changes), as observed in a group of TCV experiments scanning the deposition location of the preemptive EC beam. The co-MRE has also proven able to reproduce well the island width evolution in distinct plasma scenarios on TCV, ASDEX Upgrade and MAST, with very similar constant coefficients. The co-MRE has the potential of being applied in RT to provide valuable information such as the EC power required for NTM control with RT-adapted coefficients, contributing to both NTM control and integrated control with a limited set of actuators.

2020 ◽  
pp. 107754632097290
Author(s):  
You-cheng Zeng ◽  
Hu Ding ◽  
Rong-Hua Du ◽  
Li-Qun Chen

In this article, a novel vibration control scheme of suspension systems is proposed. It combines the advantages of quasi-zero stiffness isolator, nonlinear energy sink absorber, and inerter. This proposed scheme can achieve low transmissibility, low amplitude, and low additional weight and resolve the conflict between riding comfort and handling stability. Strong nonlinear vibration equations of a quarter-vehicle suspension system are established. It also presents the detailed process of high-order harmonic approximation to obtain steady-state responses. Moreover, approximate solutions are validated by a numerical method. Furthermore, based on riding comfort and handling stability, the following four suspension systems are evaluated and compared, namely, 2-degree-of-freedom quarter-vehicle model, 2-degree-of-freedom quarter-vehicle with quasi-zero stiffness isolator, 2-degree-of-freedom quarter-vehicle with inerter-nonlinear energy sink absorber, and 2-degree-of-freedom quarter-vehicle integrated control scheme with quasi-zero stiffness and inerter-nonlinear energy sink. It is found that the integrated control scheme with quasi-zero stiffness and inerter-nonlinear energy sink can significantly improve the riding comfort and handling stability at the same time. In addition, the effects of system parameters are studied carefully. The results show that based on the reasonable design of the control system parameters, better riding comfort and handling stability can be obtained. In short, this article provides a theoretical basis for integrating quasi-zero stiffness isolators and inerter-nonlinear energy sink absorbers to improve the riding comfort and handling stability.


2020 ◽  
Vol 86 (5) ◽  
Author(s):  
R. Sweeney ◽  
A. J. Creely ◽  
J. Doody ◽  
T. Fülöp ◽  
D. T. Garnier ◽  
...  

SPARC is being designed to operate with a normalized beta of $\beta _N=1.0$ , a normalized density of $n_G=0.37$ and a safety factor of $q_{95}\approx 3.4$ , providing a comfortable margin to their respective disruption limits. Further, a low beta poloidal $\beta _p=0.19$ at the safety factor $q=2$ surface reduces the drive for neoclassical tearing modes, which together with a frozen-in classically stable current profile might allow access to a robustly tearing-free operating space. Although the inherent stability is expected to reduce the frequency of disruptions, the disruption loading is comparable to and in some cases higher than that of ITER. The machine is being designed to withstand the predicted unmitigated axisymmetric halo current forces up to 50 MN and similarly large loads from eddy currents forced to flow poloidally in the vacuum vessel. Runaway electron (RE) simulations using GO+CODE show high flattop-to-RE current conversions in the absence of seed losses, although NIMROD modelling predicts losses of ${\sim }80$  %; self-consistent modelling is ongoing. A passive RE mitigation coil designed to drive stochastic RE losses is being considered and COMSOL modelling predicts peak normalized fields at the plasma of order $10^{-2}$ that rises linearly with a change in the plasma current. Massive material injection is planned to reduce the disruption loading. A data-driven approach to predict an oncoming disruption and trigger mitigation is discussed.


2013 ◽  
Vol 397-400 ◽  
pp. 1214-1219
Author(s):  
Xia Bai ◽  
Da Lu Guan ◽  
Chen Rui

This paper combines hardware reliability and software mobility with modern intelligent control through the analysis of the control object using intelligent decoupling control scheme to control the pressure control system of the large gas collector in coke oven. By using expert control strategies based on the DCS, the paper develops the system design which is versatile and effective.


Author(s):  
Daekyun Kim ◽  
Huei Peng ◽  
Shushan Bai ◽  
Joel M. Maguire

A process to design the control algorithm for an integrated powertrain system is proposed in this paper. The driver accelerator pedal position is first measured and interpreted as a power request. This power request is then satisfied by coordinating the transmission gear shift and the throttle position. The Dynamic Programming (DP) technique is used to obtain the optimal gear shift and throttle position for each predetermined constant power demands over a time horizon. The optimal results at different power levels are then combined to form a gear map and a throttle map. Flexible control architecture is presented where the relationship between the accelerator pedal rotation angle and the throttle opening angle can be adjusted according to the preference of the targeting customer group. Simulation and dyno test results show that the proposed integrated control scheme provides smooth constant power and improves fuel efficiency compared with the conventional transmission control scheme.


Robotica ◽  
2005 ◽  
Vol 23 (6) ◽  
pp. 799-803 ◽  
Author(s):  
Branko Karan

The paper presents a control scheme for simultaneous control of position and force of robot manipulator in contact with an elastodynamic environment. The control makes the assumption that interaction force between the robot and environment is adequately modeled by a second-order linear model with constant coefficients, and its implementation requires the knowledge of only boundary values of the environment parameters. It is shown that, provided that robot dynamics is exactly modeled, the scheme ensures asymptotic convergence of errors along nominal trajectories characterized by constant prescribed interaction forces and constant prescribed velocities along the contact surface.


The dynamic development of the construction industry in Russia is accompanied by an increase in the complexity of ongoing projects and, as a result, an increase in the flow of information processed. It is necessary to manage a large number of different in intensity, direction, volume, flow patterns of informational, material and technical flows, as well as the flow of regulatory influences. In this regard, it is advisable to use a multi-level approach to planning the implementation of investment and construction projects in order to increase the efficiency and intensification of the construction industry. The article deals with the problem of regulation of phenomena and processes occurring in the space of investment and construction activities, by economic methods towards the realization of sustainable development goals. Options for the implementation of integrated control based on the investment program engineering control scheme are proposed, a flowchart of the algorithm for linking and implementing strategic controlling and operational management procedures within the framework of the integral control of construction projects of technically complex and unique objects is formed.


2021 ◽  
Vol 28 (9) ◽  
pp. 092502
Author(s):  
Yuhang Luo ◽  
Zhe Gao

Author(s):  
R A Perez

The development of an integrated control scheme to enhance the performance of a generic interconnected multi-variable dynamical system, consisting of a turbofan engine and an airframe, in the presence of predominantly destructive dynamical interactions over the flight envelope is considered in this paper. The control scheme consists of two components: a simple static forward loop or feedback loop precompensator to improve the interactions followed by a forward or feedback loop controller to improve the performance. The system must be tolerant to soft and hard output sensor failures by means of analytic redundancy only. A control methodology to satisfy the above specifications is presented here. Necessary and sufficient conditions are presented in order to achieve a stable closed-loop performance of the overall system by tuning every loop separately, that is decentralized stability.


2007 ◽  
Vol 04 (01) ◽  
pp. 49-96 ◽  
Author(s):  
MIOMIR K. VUKOBRATOVIĆ ◽  
ALEKSANDAR D. RODIĆ

This work is concerned with the integrated dynamic control of humanoid locomotion mechanisms based on the spatial dynamic model of the humanoid mechanism, a servo system model, and an environment model. The control scheme was synthesized using the centralized model of the system and the hierarchical principle, with tactical and executive control levels. The proposed structure of the dynamic controller involves four feedback loops: position-velocity feedback at the robotic mechanism joints, dynamic reaction feedback at Zero-Moment Point, impact force feedback at the instant when the foot strikes the ground, and the load feedback of the mechanism joints. Simulation experiments are carried out for a number of characteristic examples. The numerical results obtained, along with theoretical study, serve as the basis for a critical evaluation of the performance of the devised controller.


2014 ◽  
Vol 945-949 ◽  
pp. 1539-1542
Author(s):  
Chao Yi Wei ◽  
Zhi Yu Long ◽  
Lei Xie ◽  
Min Yan Xie

A nonlinear tractor-semitrailer simulation model is established based on TruckSim. The control system which is designed in Matlab-Simulink contains roll, yaw folding and ABS integrated control strategy. A TruckSim-Simulink co-simulation model is constructed, and is based on which, tractor-semitrailer stability integrated control is simulation tested by a fishhook condition. The results reveal that the control system is effective. The proposed control scheme can significantly reduce the accidents of roll, jackknifing and yaw loss of control of a tractor semi-trailer, improving the vehicle driving stability.


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