Papers by Keyword: Temperature

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Authors: B.J.M. Leite Ferreira, M.C.F. Magalhães, Rui N. Correia
Abstract: We investigated the in vitro formation of apatites and other biologically relevant calcium phosphates, in particular the influence of temperature and pH in the nature of the mineral phases. With this purpose several calcium phosphates were synthesized under controlled conditions, in presence of atmospheric CO2. The results obtained suggest that both factors under study, temperature and pH, have major influence in the nature of the mineral phases obtained.
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Authors: Ting Xu
Abstract: A two-dimensional depth-average temperature transport model was used to simulate the temperature diffusion and dissipation. It is done to analyze the temperature distribution under different cases. The results indicated that the general temperature rise (refer to present, the same as following) of the intakes is below 0.3°C in Case 2\3\4\5, and the max is 0.78°C in Case 1. According to the survey temperature at the project intake at present, it is 29.7°C, then the total temperature after the project is below 30.5°C. So the project is feasible for the water temperature.
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Authors: Guo Ming Zhu, Yong Lin Kang, Wei Chen, Guang Ting Ma
Abstract: In the H-beam rolling process, the deformations and temperature field of workpiece significantly influence the mechanical properties due to the change of product microstructure. Prediction of them is important for the groove design and passes sequences. To get the deformation behavior and the temperature field of workpiece, commercial FEM program LS-DYNA has been used to analyze the whole process of H-beam rolling. The approach is based on 3D thermal mechanical coupled finite element method. The rolling process is divided into several units for calculation. The mesh of workpiece is rebuilt in the simulation for reducing the influence of element distortion. The result shows that, the temperature at the wed to flange position maintains the highest during the whole rolling process, while area of the web the lowest. After the rolling, temperature difference is above 150K between the web’s surface and flange’s inside surface, approximate 130K on the flange’s outside surface and 200K in the cross section. The simulation results show good agreement with the measured temperature data.
532
Authors: Jie Zhang, Abel Cherouat, Houman Borouchaki
Abstract: As a material removal process, metal milling process involves large geometry deformation, material thermo-visco-plastic flow coupled with damage and complex contact-friction problems. During simulation of metal milling, the finite elements distort severely at the local regions with high gradient of physical field such as stress, strain and temperature due to these problems. This paper presents numerical adaptive remeshing procedure dedicated to metal milling process. The procedure integrates Explicit solver of ABAQUS, OPTIFORM mesher and python script program transfer to execute step by step the incremental milling process. At each step, the meshes are refined and coarsened automatically based on geometrical and physical error estimations; the physical fields are transferred (point to point) from old to the new one using advanced algorithm. Johnson-cook material model is used to simulate the material plastic flow with ductile damage. Some numerical results are given to demonstrate the efficiency of the proposed procedure.
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Authors: Jiang Long, Xu Dong Wang, Yu Song
Abstract: Thermoelectric Cooler (TEC), with typical advantages such as low acoustic noise, small volume, lightness, high performance and high reliability, is a compact device widely used in fields like military applications and cooling or heating small spaces. Circuit design of a real-time controlled, LED displayed and monitored cooling and heating system is presented in this paper. The system is consisted of STC89C52RC MCU, TEC1-12706, temperature monitoring chip DS18B20, LED temperature display unit etc. Five kinds of functions like heating or cooling automatically adjustable, temperature controlling, temperature real-time displaying and monitoring and limitation value settings are achieved. A high cooling/heating efficiency has been obtained. The test result shows that the temperature rise/decrease can be 6,83°C/2.18°C per minute in the early 5 operation process of this system.
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Authors: Grandprix T.M. Kadja, Rino R. Mukti, I. Nyoman Marsih, Ismunandar
Abstract: Zeolites are among the main catalysts in the petroleoum and fine-chemical industry. The well-defined channel framework with the acid sites have empowered this kind of material to catalyze many chemical reactions, such as alkylation, isomerization, and hydrocarbon cracking. Controlling the energy consumption towards efficient process in the synthesis of zeolite has been a great interest. In this light, we succesfully show that synthesis of MFI zeolite can be tailored by using high or low temperature heating. Synthesis via high-temperature heating (HTH) at 150 °C, resulted in conventional coffin-type morphology whereas low-temperature heating (LTH) at 90 °C, resulted in a spherical-type morphology. This phenomenon indicates that energy consumption for synthesizing MFI zeolite can be decreased. Moreover, the tetrapropylammonion ion (TPA+) amount as structure-directing agents (SDA) can be lowered, hence reducing the synthesis cost. The obtained samples were charaterized by advanced techniques to compare interesting properties between samples synthesized by HTH and LTH. This concerns on the resulting morphology, textural properties, and Si/Al framework ratio.
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Authors: Qing Wei Jiang, Lin Xiao, Xiao Wu Li
Abstract: The temperature-dependent deformation and damage behaviors of ultrafine-grained (UFG) Cu and Ti produced by equal channel angular pressing (ECAP) were investigated and compared. It was found that ECAPed materials with different crystalline structures, e.g. the present fcc Cu and hcp Ti, exhibited significantly distinctive high-temperature deformation and damage characteristics. As the testing temperature is below recrystallization, small- and large-scale cracks or voids formed along the shear bands (SBs) on the surface of UFG Cu, whereas only a few fine shear lines and some non-propagation voids appeared on the surface of UFG Ti. As the temperature is above recrystallization, some small cracks (or voids) formed along grain boundaries and slip deformation took place in many coarsened grains, while only extrusions and intrusions instead of obvious cracks or voids are observable for UFG Ti. The corresponding microstructual changes after compressive deformation, e.g. grain coarsening, were also examined and confirmed by TEM observations.
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Authors: Ya Ge Zhan, Jun Luo, Hua Wu
Abstract: A composite structure multi-parameter sensor based on an embedded polarization maintaining fiber grating (PMFG) has been studied theoretically and experimentally. A fiber Bragg grating (FBG, for comparison with the PMFG) and a PMFG are embedded in glass fiber reinforced polymer (GFRP) laminates in the experiment. The temperature and stress response characteristics of the fiber gratings embedded in corresponding GFRP are studied. The temperature sensitivity of the FBG improves from 10.64pm/°C to 21.66pm/°C. The temperature sensitivity of the PMFG improves from 10.22m/°C to15.7pm/°C (x-axis) and from 9.56 pm/°C to15.1 pm/°C (y-axis). The peak wavelengths in the reflection spectra of the two gratings all shift linearly with the temperature and/or the stress of GFRP. The two temperature-wavelength sensitivities and the two stress-wavelength sensitivities of the PMFG are all different with each other. The temperature and the stress of the GFRP can be calculated according to the two peak wavelength (in x-axis and in y-axis) shifts of a PMFG. Therefore, one PMFG is component for monitoring the temperature and the stress of a composite structure simultaneously according to the experimental results.
159
Authors: Xiang Tian Xu, Cai Xia Fan, Tian Yu Zhang
Abstract: To model the stress-strain relation of frozen soil under different temperatures, an elasto-plastic constitutive model coupling with temperature variable was proposed. Under axisymmetric condition, elastic strain was calculated by the K-G model coupling with temperature. The plastic strain was calculated by using the DP yield criterion, associated flow rule and isotropic hardening law. All of the elastic and plastic parameters are related to the temperature variable. The simulated results show that the proposed model can predict the deformation behavior of frozen soil under different temperatures.
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Authors: Xiao Peng Xie, Dong Hui Wang, Guo Jian Huang, Xin Hua Wang
Abstract: The arrangement positions and the quantities are different for different types of cranes. In order to make suitable decision, much investigate and survey was done at preliminary stage, and we know that the flange connected gate legs and turntables, the connections between load-bearing beam and rotary column under the engine room and the connections between jib and turntable are easy to lose efficient, and their mainly failure modes are cracks. By the method of finite element, 32 sensors (including 21 welding strain FBG sensors and 11 temperature FBG sensors) were used after doing much investigate and survey and finite element modeling analysis, which are arranged in different places of a gantry crane of MQ2533, for real-time structure health monitoring. This method makes the sensor data obtained more realistically reflects the crane structural condition, which provides reliable data support for crane safety monitoring and safety evaluation. Then a software platform is developed to monitor the real-time stress. If the real-time stress exceeds the allowable stress, it issues an alarm signal to the operator.
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