Temperature Control Process Research Articles

A study of the influence of external factors on the temperature control process of a 3D printer head in FDM technology

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

Automatic control of air temperature in the greenhouse considering the weather forecast data

The paper concerns the problem of improving energy efficiency and the quality of air temperature automatic control in industrial greenhouses. The article proposes a method based on the principle of disturbance compensation using weather forecast data. The plant dynamic model structure is described by the linear 1st order aperiodic link with delay both for the control circuit and for the disturbance circuit. To solve the problem of time delays in the plant mathematical model it is suggested along with the use of outside temperature sensor signal to take into account the weather forecast data for the outdoor temperature changes over the specific forthcoming interval of time. It allows the controller to generate appropriate compensation control signal in advance. The block diagram of the automatic control system of the greenhouse temperature is given. Theoretical mathematical expressions for the regulation algorithm and analysis of regulation quality are obtained and the results of numerical modeling of the temperature control process are presented. The proposed automatic control method can be used to regulate the air temperature in buildings with high requirements for microclimate parameters.

Isotropy of mechanical properties and environmental stress crack sensitivity in injection‐ and injection‐compression molding of polystyrene with different mold temperature

AbstractIn addition to conventional injection‐compression molding and injection molding with dynamic process temperature control, a synergistic combination of both processes has recently been applied in dynamic temperature‐controlled injection‐compression molding. The two‐dimensional holding pressure effect in combination with the long maintenance of the flowability of the melt due to high mold temperature enables particularly large flow path to wall thickness ratios. In the most cases, only the optimized molding of microstructures and aspect ratios is considered without including the changed internal structure of such manufactured components. In the course of this investigation, the influence of different process strategies under variation of the mold temperature on production‐related anisotropies in the mechanical properties and stress crack sensitivity of thin‐walled polystyrene components was examined. The determined mechanical properties are significantly below the values given in the data sheet of the material in the adapted process variant of injection‐compression molding with high mold temperature. However, the results also show a clear homogenization of the direction‐ and flow path‐dependent mechanical properties. In contrast, components produced in this way tend to show increased environmental stress crack sensitivity. This could be attributed to significantly reduced orientations as a result of the favorably proceeding orientation relaxation.

Research on optimization of improved ant colony algorithm in the temperature control process of cold creep forming

In the process of cold creep forming, the temperature control has problems such as low accuracy and slow response speed. Moreover, the conventional PID temperature controller has poor anti-interference ability and low control accuracy.This paper designs a PID control strategy based on improved ant colony algorithm which is applied to the temperature control of cold creep forming. With the help of Matlab simulation software, a temperature controller simulation model is established, and certain improvements are made to the model on the basis of the traditional ant colony algorithm, applying to search for the optimal parameter combination in PID control. The simulation results show that the designed control strategy can find a better parameter combination than the PID control of the ant colony algorithm. Therefore, the application of this control method to the cold creep forming temperature control system can effectively improve the product quality and production efficiency of the cold creep forming process.

Gelatinization or Pasting? The Impact of Different Temperature Levels on the Saccharification Efficiency of Barley Malt Starch.

Efficient enzymatic hydrolysis of cereal starches requires a proper hydrothermal pre-treatment. For malted barley, however, the exact initial temperature is presently unknown. Therefore, samples were micro-mashed according to accurately determined gelatinization and pasting temperatures. The impact on starch morphology, mash viscometry and sugar yields was recorded in the presence and absence of an amylase inhibitor to differentiate between morphological and enzymatic effects. Mashing at gelatinization onset temperatures (54.5–57.1 °C) led to negligible morphological and viscometric changes, whereas mashing at pasting onset temperatures (57.5–59.8 °C) induced significant starch granule swelling and degradation resulting in increased sugar yields (61.7% of upper reference limit). Complete hydrolysis of A-type and partial hydrolysis of B-type granules was achieved within only 10 min of mashing at higher temperatures (61.4–64.5 °C), resulting in a sugar yield of 97.5% as compared to the reference laboratory method mashing procedure (65 °C for 60 min). The results indicate that the beginning of starch pasting was correctly identified and point out the potential of an adapted process temperature control.

Temperature control and low infrared emissivity double-shell phase change microcapsules and their application in infrared stealth fabric

With the rapid development of infrared detection technology, the development of infrared stealth products has become an urgent requirement. Infrared stealth effect is affected by both temperature and infrared emissivity, but most of the previous studies focus on a single factor, which limits the effectiveness of the products. Herein, we prepared double-shell microcapsules (DSMs) with both temperature control and low infrared emissivity. It firstly uses eicosane as the phase change material (PCM) and melamine, urea and formaldehyde (MUF) as the shell material to form microcapsules. Then, polyaniline (PANI) is deposited on the surface of these microcapsules to form DSMs. The DSMs were measured to have a particle size concentrated at 1.484 μm, a latent heat of 155.1 J/g, a core content of 63.25% and an infrared emissivity as low as 0.722. After coating the DSMs onto polyester fabrics, the infrared emissivity of the coating has a little increase to 0.794, but impressively, the as prepared fabric can be cooled down by a maximum of 11.2 °C compared to the untreated fabric, and the temperature control process can last for 27 min, which is superior to similar products. Featured with temperature control by PCM and low emissivity by PANI, the infrared camera image shows that the fabric has an obvious infrared stealth effect, proving it is a great potential candidate in infrared stealth materials.

A new method for hydraulic mass concrete temperature control: Design and experiment

In this paper, a new method for hydraulic mass concrete temperature control to reduce temperature stress is proposed. Based on dam temperature distribution characteristics, an external heating and cooling source is used to make the water circulate in the pre-embedded pipe net in the concrete surface layer to control the concrete temperature. The minimum adverse strain principle is used to design the key parameters of the control system, and the strain caused by temperature and moisture is considered because of the porousness of concrete. The feasibility of the new method is studied via a mass concrete (1 m × 1 m × 1 m) experiment with pre-embedded temperature and moisture sensors under cold environmental conditions. The temperature and moisture evolutions in the control process show that the concrete temperature can be effectively controlled by the new method, but temperature control also has a great effect on the moisture in the surface layer concrete. Considering that the decreasing moisture of surface layer concrete in the temperature control process can also lead to adverse strain, based on the coupled heat and moisture transfer theory, the key parameters of the control system in the experiment are studied and optimized via simulations to reduce adverse strain.

Parameter identification of fractional-order time delay system based on Legendre wavelet

This paper proposes a parameter identification method of fractional-order time delay system based on Legendre wavelet. An integration operational matrix and delay operational matrix of a Legendre wavelet are constructed. The process is derived to convert a fractional-order time delay system based on a Legendre wavelet operational matrix to algebraic equation. The least squares method is used to simultaneously estimate the order, model parameters and time delay coefficient of a system. In addition, wavelet decomposition and reconstruction algorithm are used to pre-process the output signal, which separate the noise from signal. The proposed method overcomes the initial-state dependence and randomness of the identification result in the algebraic solution of the traditional operational matrix, and reduces the effect of noise on the accuracy of parameter identification. It is especially suitable for engineering application. The effectiveness is verified by numerical simulation and a temperature process control system.

General type industrial temperature system control based on fuzzy fractional-order PID controller

A fuzzy fractional-order PID control algorithm for a general type industrial temperature control system is proposed in this paper. In order to improve the production quality and controlled model accuracy, a fractional-order elementary system is used to describe the temperature control process. The gain coefficients of the proposed fractional-order PID controller is updated online based on a set of fractional-order fuzzy rules which are defined by Mittag–Leffler functions and follow fat-tailed distributions. Therefore, the proposed controller parameters could be auto-tuned according to model uncertainties, noise disturbance, random delay, and etc. Examples of the studied temperature control systems are shown to verify the effectiveness of the proposed controller. The superiority of fractional calculus is fully explored in the presented control methodology. The controlled temperature profile with the proposed algorithm could realize more satisfactory dynamic performance, better robustness respect to environment changes caused by internal and external disturbance.

Simple model reduction technique for transfer function models

AbstractIn this work, a novel model reduction method is proposed for transfer function models. The method is based on equating the ratio of the coefficients of the ‘s’, powers of ‘s’ in the numerator to the corresponding coefficients of the s, powers of ‘s’ in the denominator of the closed‐loop transfer function of the higher order process to the closed‐loop transfer function of the reduced order model with PI controlling settings. Using this method, a stable higher order process is reduced to a first‐order plus time delay (FOPTD) model. The step response of the closed loop of the reduced order model is compared with the corresponding higher order process. The efficiency of the proposed method is shown for several examples and for the experimental temperature control process. By the proposed reduction method for higher order processes without zero, the reduced model time constant is simply written with the addition of the all time constants of the higher order process.

A novel robust Virtual Reference Feedback Tuning approach for minimum and non-minimum phase systems

In real-world applications, it is often desired that the design of a closed-loop system must attain not only high performance but also robustness. This paper presents a novel robustness-based formulation for control for discrete time minimum and non-minimum phase systems using the Virtual Reference Feedback Tuning (VRFT) framework. The proposed idea is to design robust lower and higher order Proportional Integral and Derivative (PID) controller using Maximum Sensitivity (Ms) based closed-loop reference model by minimization of the VRFT objective function (JVR) The efficacy of the approach is verified on various systems in simulation and also demonstrated on the Temperature Control Process and Level Control Process experimental setups. The proposed VRFT approach provides improved performance and robustness for set point tracking and disturbance rejection. Also, the proposed approach ensures stability and specific robustness of the closed-loop system. Further, the fragility of the controller is investigated for perturbations in the controller parameters.

Double-loop control and intelligent parameter tuning for the temperature control system of a DBR semiconductor laser.

Aiming at lower startup power consumption, stronger thermal load adaptability, easier parameters adjustment, and higher parameter tuning efficiency for the temperature control system of a distributed Bragg reflector (DBR) semiconductor laser, this paper employs the double-loop control and intelligent parameter tuning methods. First, the thermal equivalent circuit model is established for the laser temperature control system, which has stronger thermal load adaptability than the traditional transfer function model. In order to improve the modeling speed and accuracy, a mean impact value (MIV) quantum particle swarm optimization (QPSO) intelligent algorithm is proposed to tune the model parameters. A double-loop temperature control system is set up on this basis. Then, the MIV-QPSO intelligent algorithm is used to tune the control parameters, which shortens the settling time, increases the tuning efficiency, and improves the temperature control effect. The feasibility and effectiveness of the proposed methods are verified through the MATLAB/Simulink simulation of the laser temperature control process.

РЕДУКЦИЯ МЕТОДА ПОИСКА ОПТИМАЛЬНЫХ НАСТРОЕК ПИД-РЕГУЛЯТОРА ДЛЯ ОПЕРАТИВНОГО УПРАВЛЕНИЯ ТЕХНИЧЕСКИМИ ОБЪЕКТАМИ

A mathematical method of reduction of optimization parameters is proposed to find the optimal settings of the PID controller. The proposed method is implemented in the Mathcad program, examples of its use for two technical objects are illustrated when a set of controller settings is found to achieve optimal quality of the control process. The first object is a computer model of the process of regulating the liquid level in the tank. The second is a computer model of the temperature control process in the tank using a PID controller. The proposed method and algorithm of the solution can be implemented using both licensed and free software

Paper] Stabilization Effect of Self-Assembly Dendrimer Doped Cholesteric Liquid Crystal on Helical Structure

In this paper, we report the resettable functionality of helix pitch length in the mixture composed of cholesteric liquid crystal and self-assembly dendrimer with lysine groups. Cholesteric-phase liquid crystal was obtained by doping a tiny amount of dendrimer less than 0.01 wt% concentration. The mixture showed not only thermal stability of helix pitch length but also resettability of that by temperature control process based on sol-gel transition characteristics in the dendrimer with lysine group. We discuss the temperature effect of the proposed cholesteric liquid crystal on such unique functionality.

The Structure and Magnetic Properties of Rapidly Quenched Fe72Ni8Nb4Si2B14 Alloy.

The complex structural and magnetic studies of the annealed rapidly quenched Cu-free Fe72Ni8Nb4Si2B14 alloy (metallic ribbons form) are reported here. Based on the calorimetric results, the conventional heat treatment process (with heating rate 10 °C/min and subsequent isothermal annealing for 20 min) for wound toroidal cores has been optimized to obtain the least lossy magnetic properties (for the minimum value of coercivity and magnetic core losses at 50 Hz). For optimal conditions, the complex permeability in the 104–108 Hz frequency range together with core power losses obtained from magnetic induction dependence up to the frequency of 400 kHz was successfully measured. The average and local crystal structure was investigated by the use of the X-ray diffraction method and the transmission electron microscopy observations and proved its fully glassy state. Additionally, for the three temperature values, i.e., 310, 340 and 370 °C, the glass relaxation process study in the function of annealing time was carried out to obtain a deeper insight into the soft magnetic properties: magnetic permeability and cut-off frequency. For this type of Cu-free soft magnetic materials, the control of glass relaxation process (time and temperature) is extremely important to obtain proper magnetic properties.

Quantitative risk assessment of listeriosis associated with fermented sausage and dry-cured pork shoulder consumption in Argentina

The risk of acquiring listeriosis from consuming fermented sausages and dry-cured pork shoulder (capicola/bondiola) in Argentina was estimated using quantitative microbiological risk assessment. The model included data about initial prevalence and contamination level of Listeria monocytogenes, product formulation with or without a starter culture (lactic acid bacteria [LAB]), time and temperature during distribution and storage prior to consumption, and consumption patterns. The probability of listeriosis from fermented sausage consumption in at-risk populations was estimated with average values of <10−11 per portion consumed. The main factor associated with such probability was the use of LAB in fermented sausage production, which reduced the risk by at least three orders of magnitude. Meat mass pH during fermentation and water activity (aw) at the end of ripening were the factors having the greatest impact on the probability of listeriosis. Thus, LAB added during production, pH values < 5.1 at the end of fermentation and aw <0.93 during ripening indicated that the environment was not appropriate for L. monocytogenes development, suggesting that fermented sausages had an adequate safety level. On the other hand, the risk of listeriosis from dry-cured pork shoulder consumption was negligible, even in the most susceptible populations. Both aw level and the strict control of process temperature were the main risk factors for acquiring listeriosis. The level of protection given by the current Argentine microbiological criterion for fermented sausages and dry-cured pork shoulder (absence of L. monocytogenes in 25 g of product) would guarantee the safety of these products similarly to the <100 cfu/g cut used in other countries.

Smart Box Development for Food Storage with PCI-Based Temperature PID Control

Temperature measurement with a control system aims to improve the quality of automation processes in the field of instrumentation, automatic systems and especially food production. The primary function of the control system is to maintain predetermined or changeable variables under specified conditions. The control system is determined by three factors, namely, process variables, controller variables and manipulated variables. In this study, the temperature response was measured in an acrylic box with a size of 30×30×20 cm3 using a PT100 sensor. The temperature response was verified with a PID control system integrated with LabVIEW software and acquired by a PCI 6221 card. The PT100 sensor calibration with the Voltcraft digital temperature shown a linear relationship. The results of the temperature response test with the PI system produced P and I parameters of 9.03 and 2.7 min, respectively, while in the PID system the P, I and D parameters were 13.2, 6.2 min and 0.2 min, respectively. The response of the control system with the PI type is more stable and consistent than the PID type. Based on the results obtained, the temperature control process using a PI or PID control system with a TD value of 0 is more recommended.

Stepped generalized predictive control of test tank temperature based on backpropagation neural network

It is significant to ensure the temperature stability of the test tank, which has a direct impact on reducing production energy consumption, improving tank quality and ensuring experimental results. However, the high nonlinearity and long delay of the temperature control process in the test tank make it difficult to satisfactorily control the temperature by traditional control methods. To solve the problem, this paper designs a temperature prediction model for the test tank based on backpropagation neural network (BPNN), which has a good fitting ability for nonlinear systems. The proposed model was coupled with improved generalized predictive control (GPC) into a new test tank temperature control method, namely, BPNN-based stepped GPC. Simulation results show that the new control method could reduce the prediction error of the BPNN and effectively control the temperature of the test tank.

Numerical Simulation of the Flow and Heat Transfer in an Electric Steel Tempering Furnace

Heat treatments, such as steel tempering, are temperature-controlled processes. It allows ferrous steel to stabilize its structure after the heat treatment and quenching stages. The tempering temperature also determines the hardness of the steel, preferably to its optimum working strength. In a tempering furnace, a heat-resistant fan is commonly employed to generate moderate gas circulation to obtain adequate temperature homogeneity and heat transfer. Nevertheless, there is a tradeoff because the overall thermal efficiency is expected to reduce because of the high rotating speed of the fan. Therefore, this study numerically investigates the thermal efficiency changes of an electric tempering furnace due to changes in the rotating speed of the fan and the effects on temperature homogeneity and the heat transfer rate to the load. Heat losses through the walls were calculated from the external temperature measurement of the furnace. Four different speeds were simulated: 720, 990, 1350, and 1800 rpm. Thermal homogeneity was improved at higher rotating speeds; this is because the recirculation zone caused by the fan improved the flow mixing and the heat transfer. However, it was found that the thermal efficiency of the tempering furnace decreased as the rotating speed values increased. Therefore, these characteristics should be modulated to obtain a profit when controlling the rotating speed. For example, although thermal efficiency decreases by 20% when the rotating speed is doubled, the heat transfer rate to load is increased by up to 50%, which can be beneficial in decreasing the process of tempering times.

Combined system development of heat ventilation air condition temperature control by fuzzy logic controller

This paper presents the development of combined model, which describes the temperature control process of an automated heat ventilation air condition system based on fuzzy logic algorithms and methods. This model solves the problem of hydraulic systems excessive inertia, what directly affects the quality of regulation. The operation principle of the system and its advantages, which consist in obtaining high-quality transients for the parameters of static error and transient process time, are presented. Proposed control principle allows to increase the system performance improving the quality of temperature parameters regulation. Model was developed in Matlab Simulink using FuzzyLogicToolbox.