Моделирование динамики температурного поля в нестационарном приближении при выращивании монокристаллов методом Чохральского

This paper presents a comprehensive analysis of the identification and control of a reflow soldering oven, with the primary goal of developing a Proportional-Integral (PI) controller to ensure precise temperature regulation and high-quality solder joints in circuit board manufacturing. The study begins by examining the generic thermal profile of a reflow soldering oven, offering insights into its temperature dynamics and control requirements. A mathematical model of the oven is derived using a first-order transfer function with transport delay, based on system response analysis. This model serves as the basis for designing and tuning the PI controller. The design process involves a systematic approach, including model validation and performance analysis under various operating conditions. The optimization of temperature control focuses on minimizing overshoot, compensating for steady-state errors, and ensuring robust responses to disturbances. Comprehensive simulations are conducted to evaluate the system's performance and stability, taking into account potential disturbances, noise, and time delays. The effectiveness of the developed PI controller is validated through comparisons with a simple Proportional (P) controller, and its accuracy is verified using the pole placement method. The results demonstrate significant improvements in temperature control, highlighting the controller's ability to precisely maintain desired thermal profiles.

This paper proposes a temperature control of the dehumidifier by thermoelectric using the SPI controller. The dehumidifier using thermoelectric module cooled an air by the heat absorption of thermoelectric module, and then removed a water in air using this process. Therefore, the temperature control for the heat absorption side of the thermoelectric module is a very important factor in determining the performance of the dehumidifier. To improve performance of the conventional PI controller which widely used in industrial field, this paper proposes the series connected PI (SPI) controller which can be adjusted an input value of PI controller. The SPI controller proposed in this paper is consisted of the series connected PI controller. The first PI controller adjusted the input value of second PI controller using the teal temperature and the command temperature. The second PI controller controled the temperature using the adjusted input value. In this paper, We compareed the characteristics of temperature control by PI and SPI controllers, and proved the validity of the proposed method.

This research demonstrates the designing of Model Predictive Controllers (MPCs) to control the temperature for thermal model of house. It also introduces an identified transfer model with a best fit criterion around 97%. In addition, a comparison study between Proportional Integral Controller (PI), Proportional Integral Derivative Controller (PID) Fractional Order PI (FOPI), Fractional Order PID (FOPID) and Model predictive Control (MPC) has been discussed in this research. Moreover, all the parameters of the suggested strategies have been tuned by Cuckoo Search Algorithm (CSA). In fact, heating systems in house buildings aim to control the indoor temperature. To realize this purpose, it is necessary to have suitable control strategies that could implement a precise temperature control. As a result a Simulink model is used to simulate the operation of temperature control and the suggested control approach. The obtained results depict that the performance evaluation includes rise, settling times, system overshoots, and Integral Time Absolute Error (IT AE) are the best values under applying MPC over using others controllers (traditional, fractional order and thermostat) controllers. As a result it can be concluded that the MPCs have the main concern of utilizing it in the area of control the thermal house temperature. Additionally, the introduced results are promising in this problem.

In a process industry, the control of temperature is a significant requirement. The various conventional control schemes using PID controllers and soft computing-based controllers such as neural networks and fuzzy logic controllers have been implemented for the temperature control system in the industry. In this paper, the emotional behaviour-based controller called brain emotional learning-based intelligent controller (BELBIC) is implemented for continually stirred tank heater (CSTH) and its performance is compared with that of conventional proportional integral (PI) controller for various test conditions. The simulations are performed for: set point tracking, disturbance rejection and multi-set point tracking. It is observed that BELBIC gives better response as compared to PI controller in terms of performance parameters for different test conditions.

This article is concerned with the stability analysis of a 2 × 2 conservation law with PI and PDP boundary feedback control. In the PI controller case, the authors establish a sufficient and necessary stability condition for feedback parameters by Walton–Marshall criterion. Moreover, in PDP controller case, the characteristic equation is an exponential polynomial which includes two exponential arguments. Based on Ruan’s results on stability for quasi-polynomials and Schur–Cohn criterion on the roots inside the unit circle for a real coefficient polynomial, a complete characterization for system parameters and the feedback delay is presented. Also, the delay-independent and delay-dependent stability intervals are obtained in this article.

Purpose: To assess whether tailoring the Kp and Ki values of a proportional-integral (PI) controller during radiofrequency (RF) cardiac ablation could be advantageous from the point of view of the dynamic behaviour of the controller, in particular, whether control action could be speeded up and larger lesions obtained.Methods: Theoretical models were built and solved by the finite element method. RF cardiac ablations were simulated with temperature controlled at 55°C. Specific PI controllers were implemented with Kp and Ki parameters adapted to cases with different tissue values (specific heat, thermal conductivity and electrical conductivity) electrode–tissue contact characteristics (insertion depth, cooling effect of circulating blood) and electrode characteristics (size, location and arrangement of the temperature sensor in the electrode).Results: The lesion dimensions and Tmax remained almost unchanged when the specific PI controller was used instead of one tuned for the standard case: Tmax varied less than 1.9°C, lesion width less than 0.2 mm, and lesion depth less than 0.3 mm. As expected, we did observe a direct logical relationship between the response time of each controller and the transient value of electrode temperature.Conclusion: The results suggest that a PI controller designed for a standard case (such as that described in this study), could offer benefits under different tissue conditions, electrode–tissue contact, and electrode characteristics.

PEMFC involves a multi-physics coupling process which leads to some challenging difficulties for control strategy design and implementation. Among those, temperature regulation of PEMFC stack is essential to ensure the high operation efficiency, avoid thermal fatigue and prolong the stack lifespan [1, 2]. Several control strategies regarding to the temperature regulation have been carried out in recent years [3]. In [4], an extremum seeking control with a proportional-integral (PI) controller was proposed in order to achieve the optimal temperature regulation. In [5], the temperature control strategy was proposed for a PEMFC system with a water cooling system, where the voltage of a water circulation pump was manipulated through a PI controller and a water cooling fan was under the on/off modes. In [6], a more advanced fuzzy logic controller was applied to regulate the speed of the cooling fan and increase the convection ratio between PEMFC and atmosphere. However, the proposed control strategy is validated for a low-power PEMFC. Thus, the limitation of cooling capacity is not considered in those aforementioned control strategies [4,5,6]. When the generated heat from PEMFC is higher than the dissipated heat from the cooling system, the temperature of PEMFC will keep increasing. Recently, Chen et al. [7] considered the limited capacity of a water cooling system and current constraint in the PEMFC system and proposed three temperature control strategies, which developed a constrained model predictive control (MPC) strategy, and designed duty ratio split controller and current governor both based on the proportional-integral-derivative (PID) control in order to implement the trade-off between cooling capacity and power demand.

The superheater in the thermal power plant makes the wet steam into the dry steam with high temperature and high pressure by using the boiler heat. The dry steam pressure rotates the turbine-generator system. The efficiency and life time of the boiler heavily depends on the steam temperature regulation. The steam temperature can be deviated from the reference by the MW demand of the power plant. It is therefore required that the PI(proportional-integral) controller should be robust against the disturbance such as the MW demand. In this paper, the PI controller with the integral state predictor is proposed and applied to regulate the steam temperature of the superheater, and it is compared with the conventional PI controller operated in the thermal power plant in view of control performance.

Real Time Control For Time Delay System

Uniqueness of solutions and conservation laws for the quasigeostrophic model

This work demonstrates a handheld, micro-heater integrated metal oxide (MOX) based gas sensor interface system that includes digital set point, a precise closed loop temperature control and a wide range resistance readout circuit. The implementation of proposed system, constitutes two circuits. First, the temperature control loop circuit, able to set the platinum micro heater temperature over a range from ambient temperature to 300 °C, with a maximum peak to peak deviation less than 2.0 °C. An ON---OFF control technique is used to control the temperature of microheater since the heat transfer characteristics of micro heater are difficult to model. Second, a resistance to time conversion based resistance readout circuit is designed that measures the resistance over a range of 1 K? to 100 M?. The overall system is flexible and can be interfaced with integrated sensors having different power requirements and fabrication parameters. Gas sensing film used for gas detection is made of Tin oxide (SnO2). Since, the metal oxide sensor works at elevated temperatures, it can detect different gases like, ammonia (NH3) at 230 °C, nitrogen dioxide (NO2) at 80 °C and carbon mono-oxide (CO) at 270 °C. Various experiments were conducted to test the above mentioned circuit by first connecting discrete known resistive components and also, its response with NH3 is recorded with various concentrations. The resistance readout circuit output has an excellent accuracy with an error of less than 2 % in sensor resistance measurement and hence in measurement of gas concentration.

Embedded systems are expected to work without human intervention based on some environment conditions and take required action based on these sensed condition in real-time. The software in an embedded system contains the control logic which decides what action is to be taken based on the sensed parameter. In this paper we try to bring out most important and widely used types of control logic that can be implemented, its pros and cons with the example of an engine coolant fan control based on coolant temperature. Engine coolants are used to absorb the excess heat of the engine, which causes the coolant to get heated. A coolant fan is used to take away the excess heat based on the coolant temperature. The control logic software is used to vary the duty-cycle of the fan appropriately to maintain the engine coolant temperature within certain range. This paper describes in detail two control algorithms - Hysteresis and PI Control logic for this purpose. It is shown that Hysteresis is most suitable when the FAN has only a few well defined set-point duty-cycles, strict memory requirements. PI Control is ideal when precise temperature control is required. In cases where very precise control of at the set-point is not needed, the PI Control exhibits a cycling effect near the set-point. A combination of control logic is proposed to overcome this drawback. Also, the major factors which influence the selection of the control logic are described in detail.

In this paper, a method for obtaining conservation laws of dynamic systems with variable mass is developed. It is based on Noether’s theorem to the existence of conservation laws and D’Alembert’s variational principle. In the general case, a dynamic system with variable mass is purely nonconservative. Noether’s identity for such a case is expanded by the terms that describe the mass variation. If Noether’s identity if satisfied, a conservation law exists. Two groups of systems with variable mass are considered: a nonlinear vibrating machine and a rotor with variable mass. For these systems, conservation laws are obtained using the procedure developed in this paper.

We have shown in an earlier work that, assuming a particular class of equations of state, the Euler equations of one-dimensional gas flow are invariant under an SU(3) group of transformations, and in fact admit of a Lie group of symmetry of infinite order; they, therefore, possess an infinite number of conservation laws. We show in the present work that the SU(3) symmetrical formalism still brings about tremendous simplification and analytical order in the most general case where the equation of state is arbitrary. The six characteristic equations assume a vector form and relate two conjugate, three-dimensional vectors U and X. The SU(3) symmetry is only broken to a minor extent through the occurrence of a multiplicative factor Γ in the equations. The conservation laws take the form of the Cauchy integrability condition for the elements of a traceless second rank tensor εij and, taken all together, form an SU(3) octet; in the most general case, however, there exist four conservation laws only (five if the gas is monatomic) as a result of the breaking of symmetry. Application of these results to the theory of self-similar flow is also discussed. Finally, we show the invariance of the equations of monatomic gas flow under Lorentz transformations in a three-dimensional Minkowski space; that raises the question of whether a geometrical relation may exist between the Minkowski light cones and characteristics.

A simple method to monitor the temperature in a high pressure apparatus has been developed. In this, a small amount of NaCl placed in the graphite heater of a pressurized furnace assembly melted when the heater temperature was increased and this caused an abrupt change in the heater resistance. This effect could be used to measure the sample temperature in a high-pressure experiment and to calibrate the temperature as a function of electric power. The method was used successfully to attain a better control of temperature in growing crystals of cubic boron nitride under high-pressure high-temperature conditions.