scholarly journals Computer simulation of the mold heating and cooling control loop, using conventional control strategies

1978 ◽  
Author(s):  
R.H. Floersch
Keyword(s):  
Computer Simulation ◽  
Control Strategies ◽  
Control Loop ◽  
Heating And Cooling ◽  
Cooling Control

Heat Flux Distribution Over a Solar Central Receiver Using an Aiming Strategy Based on a Conventional Closed Control Loop

2017 ◽  
Author(s):  
Jesús García ◽  
Yen Chean Soo Too ◽  
Ricardo Vasquez Padilla ◽  
Rodrigo Barraza Vicencio ◽  
Andrew Beath ◽  
...  
Keyword(s):  
Heat Flux ◽  
Flux Distribution ◽  
Thermal Stresses ◽  
Control Strategies ◽  
Multiple Input Multiple Output ◽  
Control Loop ◽  
Heat Flux Distribution ◽  
Input Multiple Output ◽  
Solar Receiver ◽  
Solar Field

Solar thermal towers are a maturing technology that have the potential to supply a significant part of energy requirements of the future. One of the issues that needs careful attention is the heat flux distribution over the central receiver’s surface. It is imperative to maintain receiver’s thermal stresses below the material limits. Therefore, an adequate aiming strategy for each mirror is crucial. Due to the large number of mirrors present in a solar field, most aiming strategies work using a data base that establishes an aiming point for each mirror depending on the relative position of the sun and heat flux models. This paper proposes a multiple-input multiple-output (MIMO) closed control loop based on a methodology that allows using conventional control strategies such as those based on Proportional Integral Derivative (PID) controllers. Results indicate that even this basic control loop can successfully distribute heat flux on the solar receiver.

scholarly journals Proposed Strategies for Improving Poor Hygrothermal Conditions in Museum Exhibition Rooms and Their Impact on Energy Demand

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 620 ◽  
Author(s):  
Joanna Ferdyn-Grygierek ◽  
Krzysztof Grygierek
Keyword(s):  
Relative Humidity ◽  
Energy Demand ◽  
Air Conditioning ◽  
Control Strategies ◽  
Internal Heat ◽  
Current Method ◽  
Dramatic Improvement ◽  
Precise Control ◽  
Heating And Cooling ◽  
Microclimate Conditions

In museums, poor microclimate conditions, especially large changes in relative humidity and temperature, can lead to serious deterioration of the exhibits. Properly designed heating, ventilation, and air conditioning (HVAC) systems for precise control of the air parameters are required. However, due to the financial restrictions of museums, complex air-conditioning systems are often not feasible. In this study, we tested and propose novel methods to reduce the short- and long-term fluctuations in the relative humidity in exhibition rooms of a Polish museum. The methods only include indoor temperature and ventilation airflow control strategies, without the use of (de)humidification equipment. The analysis is based on simulations using EnergyPlus software. A multi-zone thermal model of the museum building was validated and calibrated with measured data. A full calendar year was simulated for five control cases (including the current method used) and two internal heat gain schedules. The energy demand for heating and cooling for each case was calculated. The combination of temperature control and adequate ventilation using ambient airflow allows for dramatic improvement in the microclimate conditions. The proportion of the year when the instantaneous indoor relative humidity is ±5% from set point decreased from 85% to 20%. A significant effect was obtained over the summer months.

Analysis of Hybrid Electric/Thermofluidic Control for Wet Shape Memory Alloy Actuators

2009 ◽  
Author(s):  
Leslie Flemming ◽  
Stephen Mascaro
Keyword(s):  
Control Strategies ◽  
Fluid Dynamic ◽  
Thermal Response ◽  
Electric Heating ◽  
Electrical Heating ◽  
Linear Contraction ◽  
Heating And Cooling ◽  
The Wire ◽  
Temperature Strain ◽  
Strain Model

A wet SMA actuator is characterized by an SMA wire embedded within a compliant fluid-filled tube. Heating and cooling of the SMA wire produce a linear contraction and extension of the wire. Thermal energy can be transferred to and from the wire using combinations of resistive heating and free/forced convection using hot and cold fluid. The goal of this paper is to analyze the speed and efficiency of wet SMA actuators using a variety of control strategies involving different combinations of electrical and thermofluidic inputs. A computational fluid dynamic model is used in conjunction with a temperature-strain model to simulate the thermal response of the wire and compute strains, contraction/extension times and efficiency. The simulations produce cycling rates of up to 5 Hz for electrical heating and fluidic cooling, and up to 2 Hz for fluidic heating and cooling. The results demonstrate efficiencies up to 0.5% for electric heating and up to 0.2% for fluidic heating.

Experiments in Balance With a 2D One-Legged Hopping Machine

1984 ◽  
Vol 106 (1) ◽  
pp. 75-81 ◽  
Author(s):  
M. H. Raibert ◽  
H. B. Brown
Keyword(s):  
Computer Simulation ◽  
Attitude Control ◽  
Control Strategies ◽  
Legged Locomotion ◽  
Horizontal Velocity ◽  
Height Control ◽  
Control Scheme ◽  
Vertical Height ◽  
Control Part

The ability to balance is important to the mobility obtained by legged creatures found in nature, and may someday lead to versatile legged vehicles. In order to study the role of balance in legged locomotion and to develop appropriate control strategies, a 2D hopping machine was constructed for experimentation. The machine has one leg on which it hops and runs, making balance a prime consideration. Control of the machine’s locomotion was decomposed into three separate parts: a vertical height control part, a horizontal velocity part, and an angular attitude control part. Experiments showed that the three part control scheme, while very simple to implement, was powerful enough to permit the machine to hop in place, to run at a desired rate, to translate from place to place, and to leap over obstacles. Results from modeling and computer simulation of a similar one-legged device are described by Raibert [10].

scholarly journals An Advanced Guidance and Control System for an Unmanned Vessel with Azimuthal Thrusters

2018 ◽  
Author(s):  
M Bibuli ◽  
Ga Bruzzone ◽  
Gi Bruzzone ◽  
M Caccia ◽  
G Camporeale ◽  
...  
Keyword(s):  
Autonomous Navigation ◽  
Control Strategies ◽  
Vertical Axis ◽  
Control Loop ◽  
Guidance And Control ◽  
Marine Vehicles ◽  
Regulation Scheme ◽  
Control Scheme ◽  
Constrained Environments ◽  
And Control

The proposed paper presents the design and development of the combined guidance and control strategies for the autonomous navigation of an unmanned vessel characterized by azimuth-based thrust architecture. Autonomous Marine Vehicles (AMVs) are consolidates technological tools commonly employed for different tasks such as exploration, sampling and intervention. With the final aim of autonomous shipping, the capabilities of AMVs have to be migrated and adapted towards the reliable and safe control of commercial-like unmanned vessel, that are taking place thanks to a number of technological research projects. The employment of new concept hulls and thrust configurations, as for instance Small Waterplane Area Twin Hull (SWATH) combined with Azimuthal propulsion (common propeller-based thruster with the capability of 360◦ rotation around the vertical axis), requires robust guidance techniques to provide precise and reliable motion control during navigation. The paper proposes a dual-loop guidance and control scheme able to provide advanced navigation capabilities. In particular, the inner control loop, devoted to the actuation of the azimuthal thrusters, allows the tracking of reference course angle (namely the autopilot). Such a control loop is characterized by a modified PID regulation scheme, where a novel adaptive derivative component is inserted in order to improve the convergence curve towards the required course reference. The outer guidance loop, based on Lyapunov/virtual-target approach, allows the vessel to track generic desired paths, thus enhancing the autonomous navigation capabilities also in constrained environments. The paper will provide a deep design and analysis approach for the developed techniques, as well as simulation results of the combined guidance and control scheme, proving the reliability of the proposed approach in different operative conditions. Experimental results will be provided, depending on the availability of the actual autonomous vessel (currently under final development/test phases and related to the specific project activities). 

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