Modelling and Control of Processes by Computer

1970 ◽  
Vol 3 (9) ◽  
pp. T148-T154
Author(s):  
T. Robbins ◽  
N. W. Francis
Keyword(s):  
Steady State ◽  
Crude Oil ◽  
Normal Operator ◽  
State Control ◽  
Crude Oil Distillation ◽  
Operator Control ◽  
Steady State Control ◽  
And Control ◽  
Digital Computers

Two applications of digital computers to control of crude oil distillation units are outlined. Results from both applications are quoted and comparisons made with normal operator control of the units. Difficulties encountered with the applications are mentioned and comments are made on steady-state control. The purpose of this paper is to describe two aspects of the application of digital computers to the control of crude oil distillation units.

Operation and Control of a Supercritical CO2 Compressor

2021 ◽  
Author(s):  
Joshua D. Neveu ◽  
Stefan D. Cich ◽  
J. Jeffrey Moore ◽  
Jason Mortzheim
Keyword(s):  
Steady State ◽  
Critical Point ◽  
Operating Conditions ◽  
State Control ◽  
Power Cycle ◽  
Low Head ◽  
And Performance ◽  
Steady State Control ◽  
And Control ◽  
Thermal Sources

Abstract Among the list of advanced technologies required to support the energy industry’s novel Supercritical Carbon Dioxide (sCO2) power cycle is the need for a robust and responsive control system. Recent testing has been performed on a 2.5 MWe sCO2 compressor operating near the critical temperature (31C) and critical pressure (73.8 bar), developed with funding from the US DOE Apollo program and industry partners. While sCO2 compression has been performed before, operating near the critical point has many key benefits for power generation with its low head requirements and smaller physical footprint. However, with these benefits come unique challenges, namely controlling this system to steady-state operating conditions. Operating just above the critical point (35°C [95°F] and 8.5 MPa [1,233 psi]) there can be large and rapid swings in density produced by subtle changes in temperature, leading to increased difficulty in maintaining adequate control of the compressor system. This means that proper functionality of the entire compressor system, and its usefulness to a closed loop recompression Brayton power cycle, is largely dependent on variables such as thermal sources, precision and response time of the instrumentation, proper heat soaking, and strategic filling and venting sequences. While other papers have discussed the science behind and performance of sCO2 compressors, this paper will discuss the challenges associated with steady-state control of the compressor at or near operating conditions, how the fill process was executed for optimal startup, and changes that occurred while idling during trip events.

scholarly journals On Linear Coding Schemes for Stabilizing LTI Control with Multiple Sensors

2010 ◽  
Vol 6 (1) ◽  
pp. 514521
Author(s):  
Anna N. Kim
Keyword(s):  
Steady State ◽  
Time Instant ◽  
Wireless Channel ◽  
State Control ◽  
Control Cost ◽  
Transmit Power ◽  
Multiple Sensors ◽  
Coding Schemes ◽  
Steady State Control ◽  
And Control

We examine the problem of designing the encoding and control policies of a linear stochastic control system, where the communication channel between the plant state observer (sensor) and the controller is a lossy wireless channel that is constrained in terms of transmit power and bandwidth. For a first-order ARMA modeled plant with Gaussian statistics, when there are two sensors observing the plant, nonlinear encoding is shown to result in smaller cost at time instant [Formula: see text] compared to the linear schemes, if transmissions are carried out over parallel Gaussian independent channels. In this paper, optimal linear coding schemes for the case of multiple sensors are examined. They are shown to minimize the control cost at the infinite time horizon, when the wireless channel is accessed using time division multiplexing. Our analysis is carried out for when separation between the state estimation and control is possible, and the optimal steady state control law is certainty equivalent. The distortion lower bound for estimating the plant state is derived, along with the necessary conditions on the transmit power that minimize the steady state control cost. We also propose a linear scheme that reaches the distortion bound asymptotically under relaxed conditions.

Steady-State Control of Hybrid Foil-Magnetic Bearings

2012 ◽  
Author(s):  
Ye Tian ◽  
Yanhua Sun ◽  
Lie Yu
Keyword(s):  
Steady State ◽  
Load Capacity ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
State Control ◽  
Foil Bearings ◽  
Foil Bearing ◽  
State Controller ◽  
Steady State Control ◽  
And Control

A hybrid foil-magnetic bearing is combination of a foil bearing and a magnetic bearing, which takes advantages of both bearings while compensating each other the weaknesses. It is a solution of friction and wear of foil bearings at low speeds and limited load capacity of magnetic bearings. Furthermore, load sharing and control of dynamics can be achieved in a hybrid foil-magnetic bearing. However, in the hybrid foil-magnetic bearing, the journal should run at certain eccentricity and attitude angle in order to take part of the loads, but the magnetic bearing would attempt to force the journal to the reference position at all times while using a conventional PID controller. Therefore, it is necessary to design a new control algorithm to overcome the contradictions. In this paper, the steady-state characteristics of a hybrid foil-magnetic bearing were analyzed. Then a searching algorithm was presented and a steady-state controller was designed to determine the steady-state working position of the hybrid foil-magnetic bearings. Finally, simulations were done to verify performances of the searching algorithm and designed steady-state controller, and the results show its validity.

Acute endurance exercise induces changes in vasorelaxation responses that are vessel-specific

2013 ◽  
Vol 304 (7) ◽  
pp. R574-R580 ◽  
Author(s):  
Juan M. Murias ◽  
Kenneth N. Grise ◽  
Mao Jiang ◽  
Hana Kowalchuk ◽  
C. W. James Melling ◽  
...  
Keyword(s):  
Steady State ◽  
Endurance Exercise ◽  
State Control ◽  
Average Response ◽  
Dynamic Adjustment ◽  
Acute Bout ◽  
Vascular Responsiveness ◽  
Femoral Vessels ◽  
Steady State Control ◽  
And Control

The dynamic adjustment and amplitude of the endothelium-dependent vasorelaxation of the carotid, aorta, iliac, and femoral vessels were measured in response to acute low- (LI) or high-intensity (HI) endurance exercise. Vasorelaxation to 10−4 M ACh was evaluated in 10 control, 10 LI, and 10 HI rats. Two-millimeter sections of carotid, aorta, iliac, and femoral arteries were mounted onto a myography system. Vasorelaxation responses were modeled as a monoexponential function. The overall τ (control, 10.5 ± 6.0 s; LI, 10.4 ± 5.7 s; HI, 11.0 ± 6.9 s) and time-to-steady-state (control, 47.6 ± 24.0 s; LI, 46.2 ± 22.8 s; HI, 49.1 ± 28.3 s) was similar in LI, HI, and control ( P > 0.05). The overall (average of four vessel-type) % vasorelaxation was larger in LI (73 ± 16%) and HI (73 ± 16%) than in control (66 ± 19%) ( P < 0.05). The overall rate of vasorelaxation was greater in LI (1.9 ± 0.9%·s−1) and HI (1.9 ± 1.1%·s−1) compared with control (1.6 ± 0.7%·s−1) ( P < 0.05). The vessel-specific responses (average response for the three conditions) showed that carotid displayed a slower adjustment (τ, 18.9 ± 4.4 s; time-to-steady-state, 80.4 ± 18.4 s) compared with the aorta (τ, 10.3 ± 3.8 s; time-to-steady-state, 46.3 ± 15.2 s), the iliac (τ, 6.3 ± 2.1 s; time-to-steady-state, 30.3 ± 9.0 s), and the femoral (τ, 6.0 ± 1.9 s; time-to-steady-state, 29.3 ± 8.4 s). The % vasorelaxation was larger in the carotid (82 ± 14%) than in the aorta (67 ± 16%), iliac (61 ± 13%), and femoral (71 ± 19%) ( P > 0.05). The rate of vasorelaxation was carotid (1.1 ± 0.2%·s−1), aorta (1.5 ± 0.4%·s−1), iliac (2.2 ± 0.8%·s−1), and femoral (2.6 ± 1.0%·s−1). In conclusion, an acute bout of endurance exercise increased vascular responsiveness. The dynamic and percent adjustments were vessel-specific with vessel function likely determining the response.

Steady-state control of plate pasteurisers

Food Control ◽  
2005 ◽  
Vol 16 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Ken R. Morison
Keyword(s):  
Steady State ◽  
State Control ◽  
Steady State Control

scholarly journals Research on Anti-saturation Feedback Control Method for UAV Avionics System

2018 ◽  
Vol 232 ◽  
pp. 04008
Author(s):  
Xiao-Jun Zhang
Keyword(s):  
Steady State ◽  
Control Method ◽  
Control Process ◽  
System Control ◽  
State Control ◽  
Saturation Control ◽  
Disturbance Rejection Control ◽  
Feedback Control Method ◽  
Equivalent Control ◽  
Steady State Control

UAV avionics system is prone to saturation distortion under unsteady conditions, so anti-saturation control is needed. A control method of UAV avionics system based on anti-saturation feedback compensation is proposed. The anti-saturation control process of UAV avionics system is a multi-objective optimization process with multi-variables. The constrained parameter model of UAV avionics system control is constructed. Electromagnetic loss, torque, output power and other parameters are taken as constraint indexes, the original control information of UAV avionics system is treated with self-stabilization, the equivalent control circuit is designed, and the magnetic resonance transmission mode of avionics system is analyzed. An anti-saturation feedback tracking control method is used for steady-state control of the output voltage of the avionics system. The error compensation function is constructed to adjust the output adaptive parameters of the avionics system and the static anti-saturation compensator is constructed to compensate the power gain. The yaw error and the output steady-state error of the avionics system are reduced. The simulation results show that the proposed method has better output stability, lower output error, better real-time performance and better linear auto-disturbance rejection control performance.

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