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Experiments and Simulation of Thermal Behaviors of the Dual-drive Servo Feed System 被引量:6
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作者 YANG Jun MEI Xuesong +3 位作者 FENG Bin ZHAO Liang MA Chi SHI Hu 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第1期76-87,共12页
The machine tool equipped with the dual-drive servo feed system could realize high feed speed as well as sharp precision. Currently, there is no report about the thermal behaviors of the dual-drive machine, and the cu... The machine tool equipped with the dual-drive servo feed system could realize high feed speed as well as sharp precision. Currently, there is no report about the thermal behaviors of the dual-drive machine, and the current research of the thermal characteristics of machines mainly focuses on steady simulation. To explore the influence of thermal characterizations on the precision of a jib boring machine assembled dual-drive feed system, the thermal equilibrium tests and the research on thermal-mechanical transient behaviors are carried out. A laser interferometer, infrared thermography and a temperature-displacement acquisition system are applied to measure the temperature distribution and thermal deformation at different feed speeds. Subsequently, the finite element method (FEM) is used to analyze the transient thermal behaviors of the boring machine. The complex boundary conditions, such as heat sources and convective heat transfer coefficient, are calculated. Finally, transient variances in temperatures and deformations are compared with the measured values, and the errors between the measurement and the simulation of the temperature and the thermal error are 2 ~C and 2.5 pm, respectively. The researching results demonstrate that the FEM model can predict the thermal error and temperature distribution very well under specified operating condition. Moreover, the uneven temperature gradient is due to the asynchronous dual-drive structure that results in thermal deformation. Additionally, the positioning accuracy decreases as the measured point became further away from the motor, and the thermal error and equilibrium period both increase with feed speeds. The research proposes a systematical method to measure and simulate the boring machine transient thermal behaviors. 展开更多
关键词 dual-drive feed system thermal deformation temperature distribution thermal characteristics measurement FEM
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Quantitative analysis on influencing factors for interface propagation-based thermal conductivity measurement method during solid-liquid transition 被引量:1
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作者 ZHOU Tian MA Xiao-yi +1 位作者 LIU Xu LI Yuan 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第8期2041-2055,共15页
The recently proposed interface propagation-based method has shown its advantages in obtaining the thermal conductivity of phase change materials during solid-liquid transition over conventional techniques. However, i... The recently proposed interface propagation-based method has shown its advantages in obtaining the thermal conductivity of phase change materials during solid-liquid transition over conventional techniques. However, in previous investigation, the analysis on the measurement error was qualitative and only focused on the total effects on the measurement without decoupling the influencing factors. This paper discusses the effects of influencing factors on the measurement results for the interface propagation-based method. Numerical simulations were performed to explore the influencing factors, namely model simplification, subcooling and natural convection, along with their impact on the measurement process and corresponding measurement results. The numerical solutions were provided in terms of moving curves of the solid-liquid interface and the predicted values of thermal conductivity. Results indicated that the impact of simplified model was strongly dependent on Stefan number of the melting process. The degree of subcooling would lead to underestimated values for thermal conductivity prediction. The natural convection would intensify the heat transfer rate in the liquid region, thereby overestimating the obtained results of thermal conductivity. Correlations and experimental guidelines are provided. The relative errors are limited in ±1.5%,±3%and ±2% corresponding to the impact of simplified model, subcooling and natural convection, respectively. 展开更多
关键词 phase change material thermal conductivity measurement influencing factor interface propagation-based method numerical simulation
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The Approach of Compensation of Air Refractive Index in Thermal Expansion Coefficients Measurement Based on Laser Feedback Interferometry 被引量:2
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作者 郑发松 丁迎春 +2 位作者 谈宜东 林静 张书练 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第7期17-20,共4页
We present the thermal expansion coefficient (TEC) measurement technology of compensating for the effect of variations in the refractive index based on a Nd: YA G laser feedback system, the beam frequency is shifte... We present the thermal expansion coefficient (TEC) measurement technology of compensating for the effect of variations in the refractive index based on a Nd: YA G laser feedback system, the beam frequency is shifted by a pair of aeousto-optic modulators and then the heterodyne phase measurement technique is used. The sample measured is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams hit perpendicularly and coaxially on each surface of the sample. The reference beams hit on the reference mirror and the high-refiectivity mirror, respectively. By the heterodyne configuration and computing, the influences of the vibration, distortion of the sample supporter and the effect of variations in the refractive index are measured and largely minimized. For validation, the TECs of aluminum samples are determined in the temperature range of 29-748K, confirming not only the precision within 5 × 10-7 K-1 and the accuracy within 0.4% from 298K to 448K but also the high sensitivity non-contact measurement of the lower reflectivity surface induced by the sample oxidization from 448 K to 748 K. 展开更多
关键词 In TEC The Approach of Compensation of Air Refractive Index in thermal Expansion Coefficients Measurement Based on Laser Feedback Interferometry
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Out of Plane Thermal Conductivity of Carbon Fiber Reinforced Composite Filled with Diamond Powder 被引量:1
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作者 M. Srinivasan P. Maettig +4 位作者 K. W. Glitza B. Sanny A. Schumacher M. Duhovic J. Schuster 《Open Journal of Composite Materials》 2016年第2期41-57,共17页
Highly conductive fillers have a strong influence on improving the poor out of plane thermal conductivity of carbon fiber reinforced composites. The objective of this study has been to investigate the role of the diam... Highly conductive fillers have a strong influence on improving the poor out of plane thermal conductivity of carbon fiber reinforced composites. The objective of this study has been to investigate the role of the diamond powder (DP) in enhancing the out-of-plane thermal conductivity of the woven composites. Samples of the standard modulus T300 carbon fiber composite with 44% and 55% fiber volume fraction and the high modulus YS90A carbon fiber composite with 50% volume fraction were fabricated with their matrices comprising of neat epoxy and different loading of diamond powder within epoxy resin. Steady state thermal conductivity measurements were carried out and it was found from the measurements that the out of plane thermal conductivity of the standard modulus composite increased by a factor of 2.3 with 14% volume fraction of diamond powder in the composite while the out of plane thermal conductivity of the high modulus composite increased by a factor of 2.8 with 12% volume fraction of diamond powder in the composite. Finite Element Modeling (FEM) with the incorporation of microstructural characteristics is presented and good consistency between the measurements and FEM results were observed. 展开更多
关键词 Carbon Fibers thermal Conductivity Finite Element Analysis (FEA) MICRO-MECHANICS thermal Measurements
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Heat transfer enhancement in MOSFET mounted on different FR4 substrates by thermal transient measurement
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作者 Norazlina M S Dheepan Chakravarthii M K +2 位作者 Shanmugan S Mutharasu D Shahrom Mahmud 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第9期549-556,共8页
Miniaturization of electronic package leads to high heat density and heat accumulation in electronics device, resulting in short life time and premature failure of the device. Junction temperature and thermal resistan... Miniaturization of electronic package leads to high heat density and heat accumulation in electronics device, resulting in short life time and premature failure of the device. Junction temperature and thermal resistance are the critical parameters that determine the thermal management and reliability in electronics cooling. Metal oxide field effect transistor(MOSFET)is an important semiconductor device for light emitting diode-integrated circuit(LED IC) driver application, and thermal management in MOSFET is a major challenge. In this study, investigations on thermal performance of MOSFET are performed for evaluating the junction temperature and thermal resistance. Suitable modifications in FR4 substrates are proposed by introducing thermal vias and copper layer coating to improve the thermal performance of MOSFET. Experiments are conducted using thermal transient tester(T3ster) at 2.0 A input current and ambient temperature varying from25℃ to 75℃. The thermal parameters are measured for three proposed designs: FR4 with circular thermal vias, FR4 with single strip of copper layer and embedded vias, and FR4 with I-shaped copper layer, and compared with that of plain FR4 substrate. From the experimental results, FR4I-shaped shows promising results by 33.71% reduction in junction temperature and 54.19% reduction in thermal resistance. For elevated temperature, the relative increases in junction temperature and thermal resistance are lower for FR4I-shaped than those for other substrates considered. The introduction of thermal vias and copper layer plays a significant role in thermal performance. 展开更多
关键词 metal oxide field effect transistor(MOSFET) thermal transient measurement heat transfer path FR4
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Precipitation and stability of reversed austenite in 9Ni steel 被引量:14
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作者 Yue-hui Yang Qing-wu Cai Di Tang Hui-bin Wu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2010年第5期587-595,共9页
A new method was used to analyze the factors affecting the precipitation of reversed austenite during tempering. The samples were kept at various tempering temperatures for 10 min and their length changes were recorde... A new method was used to analyze the factors affecting the precipitation of reversed austenite during tempering. The samples were kept at various tempering temperatures for 10 min and their length changes were recorded. Then, the precipitation of reversed austenite which led to the length reduction was shown by thermal expansion curves. The results show that the effects of process parameters on the precipitation of reversed austenite can be determined more accurately by this method than by X-ray diffraction. When the quenching and tempering process is adopted, both the lower quenching temperature and higher tempering temperature can promote the precipitation of reversed austenite during tempering; and when the quenching, lamellarizing, and tempering process is used, intercritical quenching is considered beneficial to the precipitation of reversed austenite in the subsequent tempering because of Ni segregation during holding at the intercritical temperature. 展开更多
关键词 cryogenic equipment low carbon steel reversed austenite PRECIPITATION STABILITY thermal expansion measurement
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Nodeless superconductivity in a quasi-two-dimensional superconductor AuTe2Se(4/3)
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作者 Xiao-Yu Jia Yun-Jie Yu +5 位作者 Xu Chen Jian-Gang Guo Tian-Ping Ying Lan-Po He Xiao-Long Chen Shi-Yan Li 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第6期87-91,共5页
We performed ultra-low temperature thermal conductivity measurements on the single crystal of a new gold-based quasi-two-dimensional superconductor Au Te2Se(4/3), which has a superconducting transition temperature T... We performed ultra-low temperature thermal conductivity measurements on the single crystal of a new gold-based quasi-two-dimensional superconductor Au Te2Se(4/3), which has a superconducting transition temperature Tc = 2.70 K. A negligible residual linear term κ0/T in zero magnetic field is observed, which suggests fully gapped superconducting state.Furthermore, the field dependence of κ0/T is similar to that of the multi-band s-wave superconductor Ba Fe1.9 Ni0.1 As2 at low field. These results reveal multiple nodeless superconducting gaps in this interesting quasi-two-dimensional superconductor with Berezinsky–Kosterlitz–Thouless topological transition. 展开更多
关键词 SUPERCONDUCTIVITY thermal transport measurement gap structure two-dimensional material
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Field Performance Analysis of Shoes Used in the Takraw Games in Malaysia
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作者 Nor Mariah Adam Qi Jie Kwong Ezrin Husin 《Journal of Physical Science and Application》 2013年第5期316-327,共12页
Using proper footwear is crucial to avoid pain, deformations and injuries on foot. For athletes, a pair of good shoes is vital for comfort and may add to performance improvement. The main objective of this study is to... Using proper footwear is crucial to avoid pain, deformations and injuries on foot. For athletes, a pair of good shoes is vital for comfort and may add to performance improvement. The main objective of this study is to study the performance of some commonly used shoes in the takraw games by using experimental tests and thermal measurements. The momentum and kinetic energies that were generated by the takraw shoes were also measured. The methods used in this study included free fall test, impact force analysis and surface thermal assessment. From the outcomes of the experiments, it was found that the prototype FA shoe was better in absorption of momentum and impact force than the other shoes and also with lower surface temperature after the trial game. These outcomes suggested that it was more suitable to be worn by the takraw players for better performance. All the information obtained from this study are particularly useful for improvement on the current design oftakraw shoe. 展开更多
关键词 SHOE takraw games impact force MOMENTUM thermal measurements.
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Multiband nodeless superconductivity near the charge-density-wave quantum critical point in ZrTe(3-x)Sex
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作者 崔珊 何兰坡 +3 位作者 洪晓晨 朱相德 Cedomir Petrovic 李世燕 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第7期89-92,共4页
It was found that selenium doping can suppress the charge-density-wave(CDW) order and induce bulk superconductivity in ZrTe3. The observed superconducting dome suggests the existence of a CDW quantum critical point... It was found that selenium doping can suppress the charge-density-wave(CDW) order and induce bulk superconductivity in ZrTe3. The observed superconducting dome suggests the existence of a CDW quantum critical point(QCP) in ZrTe3-xSex near x ≈ 0.04. To elucidate the superconducting state near the CDW QCP, we measure the thermal conductivity of two ZrTe(3-x)Sex single crystals(x = 0.044 and 0.051) down to 80 m K. For both samples, the residual linear term κ0/T at zero field is negligible, which is a clear evidence for nodeless superconducting gap. Furthermore, the field dependence of κ0/T manifests a multigap behavior. These results demonstrate multiple nodeless superconducting gaps in ZrTe(3-x)Sex,which indicates conventional superconductivity despite of the existence of a CDW QCP. 展开更多
关键词 superconductivity charge-density-wave order thermal transport measurement gap structure
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Molten Steel Breakout Prediction Based on Thermal Friction Measurement 被引量:8
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作者 QIN Xu ZHU Chao-fu +1 位作者 ZHENG Li-wen YIN Yan-rong 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2011年第4期24-29,35,共7页
By measuring the pressure and piston stroke of hydraulic servo cylinders in the oscillation system of a caster mould,friction between mould and shell can be determined.The condition of solidified shell can be monitore... By measuring the pressure and piston stroke of hydraulic servo cylinders in the oscillation system of a caster mould,friction between mould and shell can be determined.The condition of solidified shell can be monitored by thermocouples fixed to the mould.Breakouts,whether caused by shell cracking,shell sticking or entrained impurities,can therefore be predicted and effectively avoided through monitoring the change characteristics of friction and thermocouples temperature during the process. 展开更多
关键词 thermal friction measurement molten steel breakout prediction TECHNOLOGY
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Thermal analysis in high power GaAs-based laser diodes 被引量:3
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作者 龚雪芹 冯士维 +2 位作者 岳元 杨军伟 李经纬 《Journal of Semiconductors》 EI CAS CSCD 2016年第4期88-92,共5页
The thermal characteristics of 808 nm Al Ga As/Ga As laser diodes(LDs) are analyzed via electrical transient measurements and infrared thermography. The temperature rise and thermal resistance are measured at variou... The thermal characteristics of 808 nm Al Ga As/Ga As laser diodes(LDs) are analyzed via electrical transient measurements and infrared thermography. The temperature rise and thermal resistance are measured at various input currents and powers. From the electrical transient measurements, it is found that there is a significant reduction in thermal resistance with increasing power because of the device power conversion efficiency. The component thermal resistance that was obtained from the structure function showed that the total thermal resistance is mainly composed of the thermal resistance of the sub-mount rather than that of the LD chip, and the thermal resistance of the sub-mount decreases with increasing current. The temperature rise values are also measured by infrared thermography and are calibrated based on a reference image, with results that are lower than those determined by electrical transient measurements. The difference in the results is caused by the limited spatial resolution of the measurements and by the signal being captured from the facet rather than from the junction of the laser diode. 展开更多
关键词 laser diodes temperature rise thermal resistance electrical transient measurement infrared thermography
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Photoacoustic measurement of the thermal property of condensed matter using a strong light-absorbing surface layer
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作者 SHEN Jun, SUN Hongwei, HUANG Mengcai and CHEN Liangbing(Suzhou University, Suzhou 215006) 《Chinese Journal of Acoustics》 1991年第3期219-227,共9页
By using a strong light-absorbing surface layer and front-surface illumination with a low power He-Ne laser ( 6mW), photoacoustic measurements of the thermal effusivities of materials have been made, based on the phot... By using a strong light-absorbing surface layer and front-surface illumination with a low power He-Ne laser ( 6mW), photoacoustic measurements of the thermal effusivities of materials have been made, based on the photoacoustic theory, derived in this paper, of condensed matter with a strong light- absorbing surface layer. This method can eliminate the stray light, give full play to the power of the light irradiation, and improve the signal to noise ratio. The experiment results are in good agreement with the theoretical values. 展开更多
关键词 Photoacoustic measurement of the thermal property of condensed matter using a strong light-absorbing surface layer
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