Inverse Approach Using Bio-Inspired Algorithm Within Bayesian Framework for the Estimation of Heat Transfer Coefficients During Solidification of Casting

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
P. S. Vishweshwara ◽  
N. Gnanasekaran ◽  
M. Arun
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Initial Conditions ◽  
Bayesian Framework ◽  
Simultaneous Estimation ◽  
Unknown Parameters ◽  
Single Experiment ◽  
Inverse Approach ◽  
Solidification Problem ◽  
The Mathematical Model

Abstract In any parameter estimation problem, it is desirable to obtain more information in one single experiment. However, it is difficult to achieve multiple objectives in one single experiment. The work presented in this paper is the simultaneous estimation of heat transfer coefficient parameters, latent heat, and modeling error during the solidification of Al–4.5 wt %Cu alloy with the aid of Bayesian framework as an objective function that harmoniously matches the mathematical model and measurements. A 1D transient solidification problem is considered to be the mathematical model/forward model and numerically solved to obtain temperature distribution for the known boundary and initial conditions. Genetic algorithm (GA) and particle swarm optimization (PSO) are used as an inverse approach and the estimation of unknown parameters is accomplished for both pure and noisy temperature data. The use of Bayesian framework for the estimation of unknown parameters not only provides the information about the uncertainties associated with the estimates but also there is an inherent regularization term in which the inverse problem boils down to well-posed problem thereby plethora of information is extracted with less number of measurements. Finally, the results of this work open up new prospects for the solidification problem so as to obtain a feasible solution with the present approach.

Systems Actuated by Shape Memory Alloys: Identification and Modeling

2021 ◽  
Vol 1 (2) ◽  
pp. 12-20
Author(s):  
Najmeh Keshtkar ◽  
Johannes Mersch ◽  
Konrad Katzer ◽  
Felix Lohse ◽  
Lars Natkowski ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Numerical Simulations ◽  
Shape Memory ◽  
Transfer Equation ◽  
Mechanical Parameters ◽  
Heat Transfer Equation ◽  
The Mathematical Model

This paper presents the identification of thermal and mechanical parameters of shape memory alloys by using the heat transfer equation and a constitutive model. The identified parameters are then used to describe the mathematical model of a fiber-elastomer composite embedded with shape memory alloys. To verify the validity of the obtained equations, numerical simulations of the SMA temperature and composite bending are carried out and compared with the experimental results.

scholarly journals AGV Brake System Simulation

2019 ◽  
Vol 10 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Daniel Varecha ◽  
Robert Kohar ◽  
Frantisek Brumercik
Keyword(s):  
Mathematical Model ◽  
Input Data ◽  
Initial Conditions ◽  
Brake System ◽  
Disc Brake ◽  
Hydraulic Control ◽  
Stopping Distance ◽  
Braking Force ◽  
Braking Process ◽  
The Mathematical Model

Abstract The article is focused on braking simulation of automated guided vehicle (AGV). The brake system is used with a disc brake and with hydraulic control. In the first step, the formula necessary for braking force at the start of braking is derived. The stopping distance is 1.5 meters. Subsequently, a mathematical model of braking is created into which the formula of the necessary braking force is applied. The mathematical model represents a motion equation that is solved in the software Matlab by an approximation method. Next a simulation is created using Matlab software and the data of simulation are displayed in the graph. The transport speed of the vehicle is 1 〖m.s〗^(-1) and the weight of the vehicle is 6000 kg including load. The aim of this article is to determine the braking time of the device depending from the input data entered, which represent the initial conditions of the braking process.

scholarly journals Development of condenser mathematical model for research and development of ways to improve its efficiency

2020 ◽  
Vol 18 (4) ◽  
pp. 578-585
Author(s):  
Madina Shavdinova ◽  
Konstantin Aronson ◽  
Nina Borissova
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Water Temperature ◽  
Steam Turbine ◽  
Cooling Water ◽  
Laboratory Research ◽  
Thermal Engineering ◽  
Linear Regression Method ◽  
Cooling Water Temperature ◽  
The Mathematical Model

The condensing unit is one of the most important elements of the steam turbine of a combined heat and power plant. Defects in elements of the condensing unit lead to disturbances in the steam turbine operation, its failures and breakdowns, as well as efficiency losses of the plant. Therefore, the operating personnel need to know the cause of the malfunction and to correct it immediately. There are no diagnostic models of condensers in the Republic of Kazakhstan at the moment. In this regard, a mathematical model of a condenser based on the methodology of Kaluga Turbine Plant (KTP) has been developed. The mathematical model makes it possible to change the input parameters, plot dependency diagrams, and calculate the plant efficiency indicators. The mathematical model of the condenser can be used to research ways for the improvement of the condensing unit efficiency, for diagnostic purposes of the equipment condition, for the energy audit conduction of the plant, and in the training when performing virtual laboratory research. Using static data processing by linear regression method we obtain that the KTP methodology of condenser calculation is fair at cooling water temperature from 20 °C to 24 °C, but at cooling water temperature from 20 °C to 28 °C, the methodology of JSC "All-Russia Thermal Engineering Institute" (JSC "VTI") is used. One of the ways to increase the condenser efficiency has been proposed. It is the heat transfer augmentation with riffling annular grooves on tubes. This method increases the heat transfer coefficient by 2%, reduces the water subcooling of the heating steam by 0.9 °C, and decreases the cooling area by 2%.

Parametric Study of Temperature Field During the Cooling Stage for Extrusion Blow Molded Part

2005 ◽  
Author(s):  
Zhan-Song Yin ◽  
Hon-Xiong Huang
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Internal Heat ◽  
Mold Material ◽  
Orthogonal Experimental Design ◽  
Ann Model ◽  
Molded Part ◽  
Artificial Neural Network Ann ◽  
The Mathematical Model ◽  
Part Thickness

A mathematical model of the transient heat transfer during the cooling and solidification of extrusion blow molded part was developed. The temperature profiles were obtained by using finite element (FE) code POLYFLOW to solve the mathematical model. The influences of blow mold material, internal heat transfer coefficient, part thickness, and initial parison temperature on cooling were analyzed. An orthogonal experimental design was applied to determine the significance of four process parameters on the time for opening the mold. The calculated results were estimated by analysis of variance (ANVOA). An artificial neural network (ANN) model based on the numerical simulation data was developed to build for predicting the temperature distribution across thickness. The results showed that ANN approach was an effective method for analyzing the cooling of blow molded part.

Heat Convection from a Horizontal Cylinder Rotating in a Quiescent Fluid

1986 ◽  
Vol 10 (3) ◽  
pp. 141-152
Author(s):  
H.M. Badr ◽  
S.M. Ahmed
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Horizontal Cylinder ◽  
Heat Transfer Process ◽  
Two Dimensional ◽  
Two Dimensional Flow ◽  
Boussinesq Fluid ◽  
The Mathematical Model ◽  
Quiescent Fluid

The aim of this work is a theoretical investigation to the problem of heat transfer from an isothermal horizontal cylinder rotating in a quiescent fluid. The study is based on the solution of the conservation equations of mass, momentum and energy for two-dimensional flow of a Boussinesq fluid. The effects of the parameters which influence the heat transfer process namely the Reynolds number and Grashof number are considered while the Prandtl number is held constant. Streamline and isotherm patterns are obtained from the mathematical model and the results are compared with previous experimental data. A satisfactory agreement was found.

Experimental Research on Performance of Heat Transfer and Pressure Drop for Primary Surface Recuperator With Mini Channels

2011 ◽  
Author(s):  
Hugen Ma ◽  
Hui Gao ◽  
Wenjing Tu
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Pressure Drop ◽  
Experimental Research ◽  
Transfer Factor ◽  
Flow And Heat Transfer ◽  
Good Consistency ◽  
Mini Channels ◽  
Performance Of Heat Transfer ◽  
The Mathematical Model

Based on the single blow technique, experimental research was conducted for the performance of heat transfer and flow drop for six test cores with cross corrugated (CC) or corrugated undulated (CU) primary surfaces for different geometries. After the mathematical model was established for heat transfer under the condition of single blow, a matching numerical solution was obtained for different NTU. The correlations of hear transfer factor j and friction factor f were obtained for three types of cross corrugated primary surfaces (crossed angle 45∼75°) with a range of Re = 120∼800 and three types of corrugated undulated primary surfaces (crossed angle 52.5∼67.5°) with a range of Re = 200∼1200. Hydraulic diameters of all heat transfer surfaces are from 1.2∼1.48mm. Analysis on the flow and heat transfer for cross corrugated and corrugated undulated primary surfaces was made based on the comprehensive evaluating factor j/f. The experimental results were compared to references with good consistency. The regressive errors of correlations were less than 16%.

Studi Perpindahan Panas Material pada Sistem Koordinat Segitiga

2017 ◽  
Vol 1 ◽  
pp. 114
Author(s):  
Imam Basuki ◽  
C Cari ◽  
A Suparmi
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Heat Conduction ◽  
Partial Differential Equations ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Numerical Solution ◽  
Difference Method ◽  
The Finite Difference Method ◽  
The Mathematical Model

<p class="Normal1"><strong><em>Abstract: </em></strong><em>Partial Differential Equations (PDP) Laplace equation can be applied to the heat conduction. Heat conduction is a process that if two materials or two-part temperature material is contacted with another it will pass heat transfer. Conduction of heat in a triangle shaped object has a mathematical model in Cartesian coordinates. However, to facilitate the calculation, the mathematical model of heat conduction is transformed into the coordinates of the triangle. PDP numerical solution of Laplace solved using the finite difference method. Simulations performed on a triangle with some angle values α and β</em></p><p class="Normal1"><strong><em> </em></strong></p><p class="Normal1"><strong><em>Keywords:</em></strong><em>  heat transfer, triangle coordinates system.</em></p><p class="Normal1"><em> </em></p><p class="Normal1"><strong>Abstrak</strong> Persamaan Diferensial Parsial (PDP) Laplace  dapat diaplikasikan pada persamaan konduksi panas. Konduksi panas adalah suatu proses yang jika dua materi atau dua bagian materi temperaturnya disentuhkan dengan yang lainnya maka akan terjadilah perpindahan panas. Konduksi panas pada benda berbentuk segitiga mempunyai model matematika dalam koordinat cartesius. Namun untuk memudahkan perhitungan, model matematika konduksi panas tersebut ditransformasikan ke dalam koordinat segitiga. Penyelesaian numerik dari PDP Laplace diselesaikan menggunakan metode beda hingga. Simulasi dilakukan pada segitiga dengan beberapa nilai sudut  dan  </p><p class="Normal1"><strong> </strong></p><p class="Normal1"><strong>Kata kunci :</strong> perpindahan panas, sistem koordinat segitiga.</p>

scholarly journals Weak resonances of periodical nonlinear oscillations

2017 ◽  
Vol 58 ◽  
Author(s):  
Olga Lavcel-Budko ◽  
Aleksandras Krylovas
Keyword(s):  
Mathematical Model ◽  
Asymptotic Solution ◽  
Space Variable ◽  
Nonlinear Oscillations ◽  
Initial Conditions ◽  
Perturbation Technique ◽  
The Mathematical Model

The mathematical model of nonlinear oscillations of weightless string is analyzed. Coefficients of the mathematical model and initial conditions are periodical functions of the space variable. A multiscale perturbation technique and integrating along characteristics are used to construct asymptotic solution without secular members.

scholarly journals Modeling of additive height and numerical analysis of cooling parameters for aero blade remanufacturing

2021 ◽  
Vol 12 (2) ◽  
pp. 803-818
Author(s):  
Miao Gong ◽  
Shijie Dai ◽  
Tao Wang ◽  
Liwen Wang
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Numerical Analysis ◽  
Cooling Effect ◽  
Transfer Model ◽  
Factors Affecting ◽  
Coupled Heat Transfer ◽  
Blade Repair ◽  
Geometric Morphology ◽  
The Mathematical Model

Abstract. Additive remanufacturing height and matching cooling parameters are the key factors affecting blade repair quality. First, the mathematical model of the single additive remanufacturing repair height and wire-feeding speed was established, the solution method was proposed and the numerical solution was obtained, and the validity of the model was verified by experiments. Then, based on the calculation results of a single additive remanufacturing repair, the geometric morphology of the cross section under double additive remanufacturing repair was analyzed, and the mathematical model was established. Second, based on the optimal parameters obtained by numerical analysis and the mathematical model, the fluid structure coupling heat transfer model of “blade fixture” for base channel cooling was established. The cooling effect of the typical section under different initial temperatures and different flow rates was calculated, and the coupled heat transfer in the process of blade remanufacturing was explained by the mechanism. Third, through the comparative analysis of the cooling effect, optimal cooling parameters of double additive remanufacturing repair were obtained, and the model of coupled heat flow was verified by experiment. The results showed that the mathematical model of additive remanufacturing height is effective for studying the thermal cycle and cooling effect of welding, and the cooling parameters obtained by numerical analysis can effectively guarantee the quality of double additive remanufacturing of blade repair.

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