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Article
Publication date: 4 March 2024

Yuxuan Wu, Wenyuan Xu, Tianlai Yu and Yifan Wang

Polyurethane concrete (PUC), as a new type of steel bridge deck paving material, the bond-slip pattern at the interface with the steel plate is not yet clear. In this study, the…

Abstract

Purpose

Polyurethane concrete (PUC), as a new type of steel bridge deck paving material, the bond-slip pattern at the interface with the steel plate is not yet clear. In this study, the mechanical properties of the PUC and steel plate interface under the coupled action of temperature, normal force and tangential force were explored through shear tests and numerical simulations. An analytical model for bond-slip at the PUC/steel plate interface and a predictive model for the shear strength of the PUC/steel plate interface were developed.

Design/methodology/approach

The new shear test device designed in this paper overcomes the defect that the traditional oblique shear test cannot test the interface shear performance under the condition of fixed normal force. The universal testing machine (UTM) test machine was used to adjust the test temperature conditions. Combined with the results of the bond-slip test, the finite element simulation of the interface is completed by using the COHENSIVE unit to analyze the local stress distribution characteristics of the interface. The use of variance-based uncertainty analysis guaranteed the validity of the simulation.

Findings

The shear strength (τf) at the PUC-plate interface was negatively correlated with temperature while it was positively correlated with normal stress. The effect of temperature on the shear properties was more significant than that of normal stress. The slip corresponding to the maximum shear (D1) positively correlates with both temperature and normal stress. The interfacial shear ductility improves with increasing temperature.

Originality/value

Based on the PUC bond-slip measured curves, the relationship between bond stress and slip at different stages was analyzed, and the bond-slip analytical model at different stages was established; the model was defined by key parameters such as elastic ultimate shear stress τ0, peak stress τf and interface fracture energy Gf.

Details

International Journal of Structural Integrity, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 18 March 2024

Min Zeng, Jianxing Xie, Zhitao Li, Qincheng Wei and Hui Yang

This study aims to introduce a novel technique for nonlinear sensor time constant estimation and sensor dynamic compensation in hot-bar soldering using an extended Kalman filter…

Abstract

Purpose

This study aims to introduce a novel technique for nonlinear sensor time constant estimation and sensor dynamic compensation in hot-bar soldering using an extended Kalman filter (EKF) to estimate the temperature of the thermocouple.

Design/methodology/approach

Temperature optimal control is combined with a closed-loop proportional integral differential (PID) control method based on an EKF. Different control methods for measuring the temperature of the thermode in terms of temperature control, error and antidisturbance are studied. A soldering process in a semi-industrial environment is performed. The proposed control method was applied to the soldering of flexible printed circuits and circuit boards. An infrared camera was used to measure the top-surface temperature.

Findings

The proposed method can not only estimate the soldering temperature but also eliminate the noise of the system. The performance of this methodology was exemplary, characterized by rapid convergence and negligible error margins. Compared with the conventional control, the temperature variability of the proposed control is significantly attenuated.

Originality/value

An EKF was designed to estimate the temperature of the thermocouple during hot-bar soldering. Using the EKF and PID controller, the nonlinear properties of the system could be effectively overcome and the effects of disturbances and system noise could be decreased. The proposed method significantly enhanced the temperature control performance of hot-bar soldering, effectively suppressing overshoot and shortening the adjustment time, thereby achieving precise temperature control of the controlled object.

Details

Soldering & Surface Mount Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 28 February 2024

Magdalena Saldana-Perez, Giovanni Guzmán, Carolina Palma-Preciado, Amadeo Argüelles-Cruz and Marco Moreno-Ibarra

Climate change is a problem that concerns all of us. Despite the information produced by organizations such as the Expert Team on Climate Change Detection and Indices and the…

Abstract

Purpose

Climate change is a problem that concerns all of us. Despite the information produced by organizations such as the Expert Team on Climate Change Detection and Indices and the United Nations, only a few cities have been planned taking into account the climate changes indices. This paper aims to study climatic variations, how climate conditions might change in the future and how these changes will affect the activities and living conditions in cities, specifically focusing on Mexico city.

Design/methodology/approach

In this approach, two distinct machine learning regression models, k-Nearest Neighbors and Support Vector Regression, were used to predict variations in climate change indices within select urban areas of Mexico city. The calculated indices are based on maximum, minimum and average temperature data collected from the National Water Commission in Mexico and the Scientific Research Center of Ensenada. The methodology involves pre-processing temperature data to create a training data set for regression algorithms. It then computes predictions for each temperature parameter and ultimately assesses the performance of these algorithms based on precision metrics scores.

Findings

This paper combines a geospatial perspective with computational tools and machine learning algorithms. Among the two regression algorithms used, it was observed that k-Nearest Neighbors produced superior results, achieving an R2 score of 0.99, in contrast to Support Vector Regression, which yielded an R2 score of 0.74.

Originality/value

The full potential of machine learning algorithms has not been fully harnessed for predicting climate indices. This paper also identifies the strengths and weaknesses of each algorithm and how the generated estimations can then be considered in the decision-making process.

Details

Transforming Government: People, Process and Policy, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1750-6166

Keywords

Article
Publication date: 21 February 2024

Mohamed Bechir Ben Hamida

This study investigates the impact of three parameters such as: number of LED chips, pitch and LED power on the junction temperature of LEDs using a best heat sink configuration…

Abstract

Purpose

This study investigates the impact of three parameters such as: number of LED chips, pitch and LED power on the junction temperature of LEDs using a best heat sink configuration selected according to a lower temperature. This study provides valuable insights into how to design LED arrays with lower junction temperatures.

Design/methodology/approach

To determine the best configuration of a heat sink, a numerical study was conducted in Comsol Multiphysics on 10 different configurations. The configuration with the lowest junction temperature was selected for further analysis. The number of LED chips, pitch and LED power were then varied to determine the optimal configuration for this heat sink. A general equation for the average LED temperature as a function of these three factors was derived using Minitab software.

Findings

Among 10 configurations of the rectangular heat sink, we deduce that the best configuration corresponds to the first design having 1 mm of width, 0.5 mm of height and 45 mm of length. The average temperature for this design is 50.5 C. For the power of LED equal to 50 W–200 W, the average temperature of this LED drops when the number of LED chips reduces and the pitch size decreases. Indeed, the best array-LED corresponds to 64 LED chips and a pitch size of 0.5 mm. In addition, a generalization equation for average temperature is determined as a function of the number of LED chips, pitch and power of LED which are key factors for reducing the Junction temperature.

Originality/value

The study is original in its focus on three factors that have not been studied together in previous research. A numerical simulation method is used to investigate the impact of the three factors, which is more accurate and reliable than experimental methods. The study considers a wide range of values for the three factors, which allows for a more comprehensive understanding of their impact. It derives a general equation for the average temperature of the LED, which can be used to design LED arrays with desired junction temperatures.

Details

Multidiscipline Modeling in Materials and Structures, vol. 20 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 1 May 2003

Xing Yang Liu and Jiaren Jiang

The effect of humidity, temperature and temperature ramping rate on the dimensional changes of the photo‐cured stereolithography (SL) resin SL5195 was investigated. It was found…

Abstract

The effect of humidity, temperature and temperature ramping rate on the dimensional changes of the photo‐cured stereolithography (SL) resin SL5195 was investigated. It was found that moisture absorption by the SL resin is a very slow process at ambient temperatures. Varying relative humidity (RH) between 20 and 90 per cent in the environment only produced slight changes in the sample dimensions during the time period investigated. Increasing the environment temperature caused a significant increase in the sample dimensions through thermal expansion along with accelerated moisture absorption at 50 per cent or higher RH. Increasing the temperature ramping rate reduces the moisture absorption during the thermal cycles.

Details

Rapid Prototyping Journal, vol. 9 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 November 1961

W.G. Durbin

CONVENTIONAL aircraft thermometers are of the platinum‐resistance type, comprising one arm of a Wheatstone bridge network. The meter connected to the network is graduated on a…

Abstract

CONVENTIONAL aircraft thermometers are of the platinum‐resistance type, comprising one arm of a Wheatstone bridge network. The meter connected to the network is graduated on a temperature scale and different values are due to changes in the resistance of the platinum element. These arise from variations in the temperature of the air immediately in contact with the element or its protective casing. Any indicated temperature is a measure of the temperature of the air in contact with the thermometer. It is also the temperature of those parts of the aircraft over which the air is moving at the same speed as it is flowing past the thermometer. Since the air does not flow at the same speed over all parts of the aircraft it is clear that by mounting thermometers in different positions on an aircraft, different temperatures will be obtained. Due mainly to kinetic heating none of these will be the true temperature of the air in the free stream—i.e. away from the influence of the aircraft—and to obtain the free stream air temperature it is necessary to apply corrections. For many purposes, particularly meteorological research, it is important to be able to obtain true air temperatures from indicated air temperatures quickly and accurately and it is with this purpose in mind that the diagram to be described was devised and constructed.

Details

Aircraft Engineering and Aerospace Technology, vol. 33 no. 11
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 3 April 2019

Zhaoqiang Wang, Jun Cheng, Hong Ji, Shan Hu and Hao Chen

The purpose of this paper is to study the effects of single parameters for temperature characteristics of oil film in port plate pair and the relationship of calculated results…

Abstract

Purpose

The purpose of this paper is to study the effects of single parameters for temperature characteristics of oil film in port plate pair and the relationship of calculated results and experimental results under different viscosity.

Design/methodology/approach

The paper established the mathematical model of oil film of port plate pair, calculated the energy equation of port plate pair, simulated for the oil film and temperature distribution and selected different kinds of lubricants to analyze the calculated value and the experimental value.

Findings

The results show: temperature rise of port plate pair is reduced with the increase of oil viscosity; temperature rise of port plate pair is decreased with rise of initial oil film thickness; temperature rise of port plate pair is increased with the rise of cylinder body speed, inclination angle and sealing belt width; and through the comparison of calculated value and experimental value, under the same viscosity and cylinder speed, experimental results are bigger.

Originality/value

This paper used the methods that the temperature of port plate pair was calculated numerically, and the results were consistent with experimental results, so it can get high precision.

Details

Industrial Lubrication and Tribology, vol. 71 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 2 September 2014

Qingrui Meng

The aim of this work is to reveal the temperature rise characteristics of the new designed disc during a braking process. In underground coal mines, the highest temperature of the…

Abstract

Purpose

The aim of this work is to reveal the temperature rise characteristics of the new designed disc during a braking process. In underground coal mines, the highest temperature of the disc brake used for inclined downward belt conveyors should be < 150 to prevent gas explosion during a braking process. To meet the requirements, a new type of disc was designed.

Design/methodology/approach

By using ANSYS software, the disc surface and interior temperature rise variations, effect of braking time and running speed on temperature rise are analyzed numerically.

Findings

The results show that the new designed disc can meet the coal mines’ requirements well, during the braking process the disc surface temperature increases at first and then decreases, there is an obvious temperature gradient in the axial direction; when running speed increases to two times of the rated one, the highest temperature nearly reaches 150; and a prolonged braking time can decrease the highest temperature effectively.

Research limitations/implications

It indicates that the disc brake should act as earlier as possible to slow down the belt conveyor when overspeed occurs; and when the running speed increases to two times of the rated one, the braking time must be prolonged to prevent gas explosion.

Originality/value

Research findings of this paper provides theoretical basis for the practical applications of the disc brake used for inclined downward belt conveyor.

Details

Industrial Lubrication and Tribology, vol. 66 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 1 August 1995

M.P. Miles, L. Fourment and J.L. Chenot

A finite‐element model for calculating the die temperatureprofile for a hot‐forging operation is presented. The workpieceis modelled as a thermo‐viscoplastic material, while the…

Abstract

A finite‐element model for calculating the die temperature profile for a hot‐forging operation is presented. The workpiece is modelled as a thermo‐viscoplastic material, while the dies are considered undeformable. Heat transfer between the dies and the workpiece is modelled using an iteratively coupled, fixed‐point calculation of the temperature in each domain. Transfer of temperature boundary conditions across contact interfaces is performed for non‐coincident meshes, using a boundary integration point contact analysis. Two industrial‐type examples are presented. In the first example, the effectiveness of the transfer of the temperature boundary conditions for a non steady‐state forging process is evaluated and determined to be satisfactory. Then weakly‐ and strongly‐coupled temperature resolutions are compared. It was found that the strongly‐coupled resolution may be necessary in order to obtain reasonably accurate results. In the second example, the weakly‐coupled resolution is compared to a constant‐temperature die approach for a relatively slow forging process, which shows the influence of the die temperature on the flow of the material.

Details

Engineering Computations, vol. 12 no. 8
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 5 January 2015

Wang Qing-Cheng, Wu Zhao-Chun and Zhu Xiang-Ping

The purpose of this paper is to reveal the characteristics of the temperature field under different types of heat sources, which are significant to the temperature control…

Abstract

Purpose

The purpose of this paper is to reveal the characteristics of the temperature field under different types of heat sources, which are significant to the temperature control encountered in practical manufacturing processes.

Design/methodology/approach

The temperature fields in an infinite slab under line or plane heat source are calculated numerically by control volume approach and ADI scheme, and the numerical results of the temperature rise have been compared among the different types of the heat sources.

Findings

The numerical results show the different changing patterns of temperature fields under line and plane heat source, respectively, and demonstrate that the magnitude of temperature rise depends strongly on the type of the heat sources. The order of temperature rise from high to low is point, line and plane heat source base on the same input heat.

Originality/value

The study is original and findings are new, which demonstrate the different changing patterns of temperature fields and the magnitude of temperature rise under line and plane heat source. The numerical solution is significant for the temperature control in practical manufacturing processes.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 25 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

1 – 10 of over 47000