Control Of Temperature Fields Research Articles

Temperature reconstruction in data centers using gappy pod combined with genetic algorithm and optimization of sensor layout

Temperature field data are essential for intelligent environmental control systems. However, acquiring comprehensive temperature distributions in data centers with numerous sensors is not only costly but can also disrupt other equipment layouts. Thus, the capability to rapidly reconstruct temperature fields using a minimal number of sensors is crucial for smart adjustments in these systems. This paper introduces a genetic algorithm (GA) to the gappy proper orthogonal decomposition (POD) method, proposing an objective function to optimize the placement and quantity of sensors. This benchmark for optimization is applied to a case study on environmental control within a data center, where the optimal sensor layouts and the corresponding mean absolute errors were determined for configurations using 5 to 15 sensors, all maintained within 1 °C. Notably, the lowest reconstruction errors of 0.03 °C and 0.05 °C were achieved with a 12-sensor setup. Six uniform sensor layouts acted as control groups. Results demonstrated that error improvements in the optimized layouts were 98.25 % superior to those in uniform layouts. Moreover, transient CFD simulations were conducted to experimentally control the gappy POD algorithm. These simulations confirmed the capability of this approach to compute optimal air supply parameters and maintain temperature control within standard limits, resulting in a 24 % airflow savings compared to fixed ventilation modes under identical conditions. Consequently, this study effectively achieves rapid reconstruction and environmental control of temperature fields in data centers, offering important theoretical and practical insights for real-world engineering applications.

PHYSICO-CHEMICAL CHARACTERISTICS OF MATERIALS BASED ON CERIUM AND CHROMIUM LANTHANOIDES

Some physical and chemical characteristics of hexa(thiocyanate-N)chromate complexes of cerium lanthanides with 3-pyridine-3-carboxylic acid are studied. It was shown by IR spectroscopy for displacement of the main absorption bands that the compounds are N-thiocyanate, the organic ligand is bidentate due to the proton transfer of the carboxyl group to atom nitrogen with the formation of a conjugate system: imino-amine tautomerism of organic ligand leads to the occurrence of pyridinium-3-carboxylic ion. It was established by X-ray diffraction analysis of monocrystals that substances have an isle structure, crystallize according the same structural type, and their crystallographic parameters change regularly in accordance with the change in the radii of Ln3+ ions. The obtained substances of the isle type are isostructural. Iintermolecular hydrogen bonds between crystallization water molecules and N–H groups of coordinated molecules of organic ligands are found. The compositions of the substances differ only in the content of crystallization water in the molecules. Studies of the magnetic properties of the samples were carried out taking into account their stability in the range of 80-360 K. The decomposition sequence is established and composition of thermolysis products. The experimental and calculated values effective magnetic moments is in agreement. Values effective magnetic moments characterize the antiferromagnetic nature of the interaction between paramagnetic centers. At temperatures below 100 K, discrepancies between the experimental and calculated values are observed, which may be due to the transition of compounds from the paramagnetic to antiferromagnetic state. The thermal behavior of substances in an inert atmosphere and oxidizing atmospheres to interval of tempetures 293-1273 K are presented. Compounds obtained determine the promising magnetic and thermal properties of substances as precursors for the low-temperature production of heterometallic oxide ceramic materials, as well as molecular magnets and thermoindicators for visual control of temperatures and temperature fields.

Soft Matter Sample Environments for Time-Resolved Small Angle Neutron Scattering Experiments: A Review

With the promise of new, more powerful neutron sources in the future, the possibilities for time-resolved neutron scattering experiments will improve and are bound to gain in interest. While there is already a large body of work on the accurate control of temperature, pressure, and magnetic fields for static experiments, this field is less well developed for time-resolved experiments on soft condensed matter and biomaterials. We present here an overview of different sample environments and technique combinations that have been developed so far and which might inspire further developments so that one can take full advantage of both the existing facilities as well as the possibilities that future high intensity neutron sources will offer.

Near-infrared measurement of water temperature near micro-magnetic particle layer in a fluidic channel under induction heating

This paper presents an experimental method for measuring the water temperature near micro-magnetic particle (MMP) layers in a fluidic channel under induction heating. This method is based on the temperature dependence of the spectrum of the ν1 + ν3 absorption band of water in the near-infrared (NIR) region. The absorbance images at the wavelength of 1412 nm, which is the most temperature-sensitive wavelength in the band, were obtained through a U-shaped channel with an optical path length of 1 mm using a narrow-bandpass filter and an NIR camera. An MMP layer was formed on the inner surface of the channel by an external strong permanent magnet and then heated inductively by applying a 760-kHz magnetic field. The temperature distribution of water was found to depend on the heating time, heating power level, and MMP layer thickness (0.5, 0.6, and 1.0 mm). The maximum increase in temperature near the MMP layer was approximately 5 °C, and the temperature resolution was 0.2 °C. A numerical simulation was used to verify the measured temperature profiles then apply the residual fitting method to determine the heat generation rates (HGRs) of the MMPs. The HGRs were independent of the heating time, and varied consistently with the heating power level. This method is useful for the quantitative understanding and control of temperature fields in applications that use MMPs for chemical reactions and cell/tissue therapy.

Modelling of heat transfer in composite bodies reinforced with tubes with incompressible liquid coolant moving in laminar regime

The equations were obtained for description of heat transfer in composite bodies with reinforcement with a set of smooth tubes with pumping of incompressible liquid coolant. The appropriate boundary-value problem of heat transfer was formulated with the following qualitative analysis. The steady temperature fields in cylindrical shells with spiral-shaped tube reinforcement (with liquid coolant flow) were simulated. The influence on the temperature fields from the side of reinforcement geometry parameters, flow direction and velocity, tubes cross sections was studied. It was found that these characteristics allow significant variation of temperature field in its gradients within the composite item: this open ways for effective control of temperature fields.

Robust Control of Temperature Fields in Steel Casting Mould as Distributed Parameter Systems

In the paper, modelling and robust control of temperature fields of the casting mould in the benchmark casting plant is presented. Temperature fields are supposed as distributed parameter systems with dynamic described by partial differential equations. Based on finite element method modelling, models for control synthesis purpose in the form of lumped-input/distributed-output system are created. For this representation, uncertainty of the controlled system was considered and robust control synthesis with internal model control structure was designed. Robust control of the temperature fields in the casting mould was carried out using the Distributed Parameter Systems Blockset for MATLAB & Simulink.

Control of temperature fields of a strapdown inertial navigation system based on fiber optic gyroscopes

Theoretical and applied issues of creating a reversible control system of time-variant temperature fields of fiber optic gyroscopes and a strapdown inertial navigation system based on such gyroscopes are considered. Mathematical models of thermal processes in the fiber optic gyroscopes and a strapdown inertial navigation system with an active double-loop reversible temperature control system based on thermoelectric coolers are constructed. Software is developed, parameters of the temperature control system are selected, computational experiments are performed, and estimates of the operation of the corresponding dynamic systems under complex thermal conditions are obtained.

Rapid High-Precision Non-Linear Calibration for Temperature Sensors in Transient Aerodynamic Heating Simulation Systems

In order to accurately simulate the transient aerodynamic heating conditions experienced by aircraft when flying at high speeds, rapid and highly precise non-linear dynamic control of the heating process in aerodynamic simulation experiments must be conducted using a transient heat flux control system. This process involves carrying out ‘thermoelectric potential - temperature (E-T)’ conversion of sensors. Here a fast and high-precision ‘E-T’ sensor conversion method for the transient aerodynamic heating control systems of high-speed aircraft is proposed. The developed method has the advantages of easy calculation, rapid conversion speed and high calibration precision, and can thus be employed for fast non-linear dynamic control of rapidly-changing temperature fields in the aerodynamic heating process of high-speed aircraft.

Fast and High Precision Thermoelectric Potential – Temperature Conversion Method for Aerodynamic Heating Control Systems

A fast and high-precision ‘thermoelectric potential - temperature (E-T)’ sensor conversion method for the transient aerodynamic heating control systems of high-speed aircraft is proposed. The developed method has the advantages of easy calculation, rapid conversion speed and high calibration precision, and can thus be employed for fast non-linear dynamic control of rapidly-changing temperature fields in the aerodynamic heating process of high-speed aircraft.

Uncertainty analysis and robust control of temperature fields of casting mould as distributed parameter systems

In the paper, an uncertainty analysis and simulation of a robust control of temperature fields of the casting mould in the benchmark casting plant are presented. Temperature fields are supposed as distributed parameter systems with dynamic models in the form of lumped-input/distributed-output system. For this representation, uncertainty of the controlled system was considered and robust control synthesis with internal model control structure was designed. Simulation of the robust control of the temperature field in the casting mould was carried out using the Distributed Parameter Systems Blockset for MATLAB & Simulink – Third-party MathWorks product.

Control of buoyancy-induced temperature and flow fields with an embedded adiabatic thin plate in porous triangular cavities

Natural convection has been performed in an insulated horizontally thin plate embedded in a triangular enclosure filled with fluid saturated porous medium, numerically. Bottom and inclined wall of triangular enclosure are isothermally heated and cooled, respectively. Vertical wall of enclosure is adiabatic. Steady, two-dimensional, laminar governing equations, which are written with Darcy model, were solved with finite-difference method. Calculations are conducted for different lengths and locations of thin plate, different aspect ratios, and Darcy-modified Rayleigh number. Prandtl number was chosen as 0.71. It is observed that the change on plate location in vertical and horizontal axes makes small effect on heat transfer; however flow field and temperature distribution strongly affected from these parameters.

Proposal of New Electromechanical Poling Treatment for Barium Titanate Single Crystals

The phase transition behaviors of the [111] oriented barium titanate (BaTiO3) single crystals were investigated as functions of temperature, uniaxial stress and electric fields. For the phase transition by temperature, with decreasing temperature above Tc, the paraelectric phase changed to the intermediate phase with superparaelectric state, and finally change to the ferroelectric phase with randomly oriented spontaneous polarizations. Moreover, it was also found that the phase transition by uniaxial stress field above Tc was almost similar one by temperature. On the other hand, for the phase transition by electric field above Tc, with increasing electric field, the paraelectric phase changed to the intermediate phase, and finally changed to the ferroelectric phase with the oriented polar direction. These results suggested that above Tc, combination between uniaxial stress and electric fields might be effective for a poling treatment of BaTiO3 crystals. Thus, in this study, a new poling method for the BaTiO3 crystals was proposed using control of temperature, uniaxial stress and electric fields.

The control of gas temperature and velocity fields of a RF induction thermal plasma by injecting secondary gas

The present study describes the control characteristics of the gas temperature and velocity fields of a RF induction argon thermal plasma by injecting cold helium gas axially at atmospheric pressure. The flow and the gas temperature fields in the RF induction mixed gas plasma are obtained by solving the axisymmetric turbulent 2D MHD equations and the energy transport equation coupled with 2D Maxwell's equations. The mixing rate of a secondary injected gas is also calculated using the species conservation equation. It is examined how the thermofluid and diffusion characteristics of a RF induction plasma are influenced by the input power and the positions of injection of secondary gas and swirling. The calculated gas temperature shows good agreement with the previously obtained experimental data.