The meteorological measurement automatic temperature testing system has a defective image. To solve the problem such as noise and insufficient contrast, and put forward the research program for image pretreatment, the...The meteorological measurement automatic temperature testing system has a defective image. To solve the problem such as noise and insufficient contrast, and put forward the research program for image pretreatment, the median filter, histogram equalization and image binarization, methods were used to remove noise and enhance images. Results showed that feature points were clear and accurate after the experiment. This simulation experiment prepared for the follow-up subsequent recognition process.展开更多
A self-sensing test method for the temperature of piezoelectric stack,based on the high correlation between the static capacitance and the stack temperature,is proposed in order to construct a self-sufficient methodol...A self-sensing test method for the temperature of piezoelectric stack,based on the high correlation between the static capacitance and the stack temperature,is proposed in order to construct a self-sufficient methodology of temperature measurement. Firstly,a theoretical model of static capacitance of the piezoelectric stack under preload was set up,and the influence of preload on the static capacitance was analyzed. Secondly,the correctness of the model was verified by static capacitance test experiments under various preloading conditions. Finally, the temperature measurement experiments at low-temperature stage for two kinds of piezoelectric stacks,namely the lowtemperature-resistant piezoelectric stack and conventional piezoelectric stack, were conducted under various preloading conditions using a polynomial fitting method. The results,which validate the accuracy of the test method,show that the maximum temperature deviations of the two kinds of piezoelectric stack are 3.9 ℃ and 2.8 ℃,respectively,when the preload force is close to the specified value. The test method uses the piezoelectric stack itself as a temperature sensor,which does not require additional equipment for temperature sensing,so that the space and equipment cost could be economized. And the test for static capacitance is concise and convenient,which indicates that in the cooling process,a concise and efficient test of the temperature of the piezoelectric stack could be realized so as to grasp the current temperature change in time.展开更多
he thermal performance test of the horizontal coaxial double tube hot gas duct (HGD) with an internal thermal insulation for the 10MW High Temperature Reactor Test Module (HTR10) was conducted on a Helium Test Loop(HE...he thermal performance test of the horizontal coaxial double tube hot gas duct (HGD) with an internal thermal insulation for the 10MW High Temperature Reactor Test Module (HTR10) was conducted on a Helium Test Loop(HETL). The present paper deals with the technical feature of the HETL, the test section and the thermal performance test of the HGD. The HGD test section with a triple tube structure includes an inner heater, a HGD model and a coldhot gas mixer. A counterflow of cold and hot helium gas under the pressure of about 3.0 MPa and the minimum temperature of 100℃ in the annular passage and the maximum of 950℃ in the central tube of the HGD model was formed. The HGD model was undergone 20 times of pressure cycle test under the pressure ranging from 0.1 to 3.4 MPa, 18 times of the temperature cycle test under the temperature ranging from 100 to 950℃ and high temperature (700 to 950℃) helium flow test for a period of more than 350 hours. The effective thermal conductivity (λeff) of the internal insulation of the HGD was investigated experimentally. The relationship of the effective thermal conductivity with the average tmperature of the internal insulation layer is λeff(W/m/℃)=0.3512+0.0003T(℃). The test results indicate that the HGD model has good abilities to resist heat flux from the central tube to the annular passage, temperature variations, and pressure variations.展开更多
This study normalized the mixture's fatigue behavior at various temperatures,and the strength and fatigue tests of the mixture were conducted.The stress state of the asphalt mixture includes direct tensile,uniaxia...This study normalized the mixture's fatigue behavior at various temperatures,and the strength and fatigue tests of the mixture were conducted.The stress state of the asphalt mixture includes direct tensile,uniaxial compression,and indirect tensile.The Desai yield surface and fatigue path were proposed.And a normalized fatigue characteristics model of the mixture was established.The following conclusions were obtained.With the increases in the loading rate,the strength of the asphalt mixture increased.As the temperature increases,the strength of the mixture is reduced.At various temperatures and rates,the strength forms a closed curved surface.The Desai strength yield surface was established,which forms a closed curved surface.When the loading rate and temperature are below a certain critical line,the asphalt mixture will not undergo strength damage.At a fixed stress state,the fatigue damage path of the mixture was determined.The stress ratio was determined considering the influence of the loading rate.In this way,a normalized model can be described to express the asphalt mixture fatigue properties at various temperatures and stress levels.For the asphalt mixture in an indirect tensile state,the normalized fatigue equation parameter is 4.09.This model is more suitable for reflecting the viscous-elastic behavior of the mixtures than the fatigue equation determined by the notional stress ratio.展开更多
The Jing-well point temperatures test method is a method to diagnose and guide the treatment of diseases by measuring the subjects' symmetrical well point temperature. it is improved from the method of knowing hea...The Jing-well point temperatures test method is a method to diagnose and guide the treatment of diseases by measuring the subjects' symmetrical well point temperature. it is improved from the method of knowing heat sensitivity. The application of Jing-well point temperatures test method is wide, and it can be used in internal and external gynecology and pediatrics and facial features department. at the same time, it has the advantage of objective and accurate diagnosis. The old law has some shortcomings, such as poor intuition, unavoidable omission of information, incomplete interpretation of information and so on. In this paper, Excel software is used to transform the data into line chart form, which improves the intuition and comprehensiveness of this method, so that the data can be better interpreted and used. It is newly proposed in this article that in addition to observing the longitudinal di fference of well point temperature, more attention should be paid to the horizontal contrast difference of well point temperature in different meridians. The article also summarizes a number of treatment methods, including acupuncture, moxa moxibustion, cupping and scraping, and the selection of acupoints, including mother acupoints, tenderness points and heat-sensitive moxibustion, so that doctors can combine traditional Chinese medicine professional knowledge in clinic.展开更多
Temperature control curve is the key to achieving temperature control and crack prevention of high concrete dam during construction,and its rationality depends on the accurate measurement of temperature stress.With th...Temperature control curve is the key to achieving temperature control and crack prevention of high concrete dam during construction,and its rationality depends on the accurate measurement of temperature stress.With the simulation testing machine for the temperature stress,in the present study,we carried out the deformation process tests of concrete under three temperature curves:convex,straight and concave.Besides,we not only measured the early-age elastic modulus,creep parameters and stress process,but also proposed the preferred type.The results show that at early age,higher temperature always leads to greater elastic modulus and smaller creep.However,the traditional indoor experiments have underestimated the elastic modulus and creep development at early age,which makes the calculated value of temperature stress too small,thus increasing the cracking risk.In this study,the stress values of the three curves calculated based on the strain and early-age parameters are in good agreement with the temperature stress measured by the temperature stress testing machine,which verifies the method accuracy.When the temperature changes along the concave curve,the law of stress development is in consistent with that of strength.Under this condition,the stress fluctuation is small and the crack prevention safety of the concave type is higher,so the concave type is better.The test results provide a reliable basis and support for temperature control curve design and optimization of concrete dams.展开更多
The purpose of this paper is to estimate the fatigue crack growth threshold of a high-Nb TiAl alloy at the different temperatures based on scanning electron microscopy (SEM) in-situ observation. The results indicate...The purpose of this paper is to estimate the fatigue crack growth threshold of a high-Nb TiAl alloy at the different temperatures based on scanning electron microscopy (SEM) in-situ observation. The results indicated that the fatigue crack growth threshold △Kth of a nearly lamellar high-Nb TiAl alloy with 8% Nb content at room temperature and 750℃ was determined as 12.89 MPa.m^1/2 and 8.69 MPa.m^1/2, respectively. The effect of the elevated temperature on the fatigue crack growth threshold cannot be ignored. At the same time, the early stage of fatigue crack propagation exhibited multicrack initiation and bridge-link behavior.展开更多
Variable temperature and pressure adsorption tests were conducted on four coal samples with different coal ranks, under simulated temperatures and pressures corresponding to coal reservoirs at different depths. The re...Variable temperature and pressure adsorption tests were conducted on four coal samples with different coal ranks, under simulated temperatures and pressures corresponding to coal reservoirs at different depths. The regularity of the variation in the amounts of adsorption by coals under variable temperature and pressure and 30 ℃ isothermal conditions are compared and the adsorption characteristics of coal under the composite effect of temperature and pressure were obtained. The adsorption test and data processing method of coal under variable temperature and pressure are presented and the effect of the mechanism of temperature and pressure on the adsorption capacity of coal has been studied. The research results are of significant importance in the investigation of coalbed methane storage mechanism and for the prediction of the amounts of coalbed methane at various depths.展开更多
The influence of processing variables on the mechanical properties of a nanostructured Al-10 wt.%Cu alloy was investigated.Stress-strain microprobe®system(SSM)and its automated ball indentation®(ABI®)te...The influence of processing variables on the mechanical properties of a nanostructured Al-10 wt.%Cu alloy was investigated.Stress-strain microprobe®system(SSM)and its automated ball indentation®(ABI®)test were used for evaluating the mechanical properties of this alloy.The tests were conducted at 21℃ on the bulk samples that were mechanically alloyed for 6 h at two ball-to-powder mass ratios(BPR)of 30:1 and 90:1.Furthermore,the tests were conducted at 200 and 400℃ on the samples that were processed at BPR of 90:1.Increasing BPR resulted in raising the final indentation load from(316±26)to(631±9)N and reducing the final indentation depth from 111 to 103μm.Regarding the samples that were processed at BPR of 90:1,increasing the test temperature from 21 to 400℃ resulted in decreasing the final load from(631±9)to(125±1)N and increasing the final depth from 103 to(116±1)μm.The sample processed at BPR of 90:1 and tested at 21℃ revealed the highest strength and the least deformability while the sample processed at BPR of 90:1 and tested at 400℃ exhibited the lowest strength and the greatest deformability,as compared to all samples under study.展开更多
Sorbitol,triethanolamine,sodium benzoate,boric acid,and sodium carbonate were mixed to prepare a waterborne rust inhibitor.A temperature and humidity accelerated corrosion test was applied to investigate the corrosion...Sorbitol,triethanolamine,sodium benzoate,boric acid,and sodium carbonate were mixed to prepare a waterborne rust inhibitor.A temperature and humidity accelerated corrosion test was applied to investigate the corrosion behaviour of waterborne rust inhibitor coated Q235 steel and original Q235 steel,which was carried out in a temperature and humidity test chamber(WSHW-1000)at a temperature of 80℃and humidity of 95%.Compared with the original Q235,waterborne rust inhibitor coated Q235 has better resistance to corrosion in hot and humid ambient conditions.Electrochemical impedance spectroscopy and potentiodynamic polarization were measured with a three-electrode cell in 3.5%NaCl aqueous solution on a CHI760E potentiostat/galvanostat.Molecular dynamics was simulated to verify the synergistic corrosion inhibitory mechanism of sodium carbonate and triethanolamine.The test shows that the prepared waterborne rust inhibitor can reduce the tendency of Q235 to corrosion and can also effectively reduce the corrosion rate.展开更多
Based on LabVlEW platform, a distributed dynamic storage testing system is designed for measuring transient high temperature signals of explosion field. Using a highpower semiconductor laser as heat source, a traceabl...Based on LabVlEW platform, a distributed dynamic storage testing system is designed for measuring transient high temperature signals of explosion field. Using a highpower semiconductor laser as heat source, a traceable dynamic calibration system is established to perform dynamic calibration of thermocouples. With quantumbehaved particle swam optimization (QP-SO) algorithm on MATLAB platform, a model of dynamic compensation filter is established. It is used by LabVIEW that calls MATLAB Script nodes or COM components to accomplish the mixed programming of LabVIEW and MATLAB, further to compensate the temperature values of the thermocouples dynamically. The experimental results show that the technique that combines temperature measurement system with LabVIEW platform is applied well in testing the explosion temperature of ther mobaric weaponry and makes the compensation values closer to the actual signals.展开更多
To discuss the pavement performance of basalt fiber-modified asphalt mixtures,the optimum dosages of asphalt and fibers are studied by the Marshall test and the rutting test.The results demonstrate that the optimum do...To discuss the pavement performance of basalt fiber-modified asphalt mixtures,the optimum dosages of asphalt and fibers are studied by the Marshall test and the rutting test.The results demonstrate that the optimum dosages of asphalt and fibers are 4.63% and 0.3%,respectively.Then the pavement performances of basalt(polyester,xylogen)fiber-modified asphalt mixtures are investigated through high temperature stability tests,water stability tests and low temperature crack resistance tests.It indicates that the pavement performances of the fiber-modified asphalt mixtures such as rutting dynamic stability,freezing splitting tensile strength,low temperature crack resistance and so on are improved compared with control asphalt mixture.The results show that the pavement performances of asphalt mixtures can be improved by fiber-modifiers.Besides,the improvement effects of basalt fiber are superior to polyester fiber and xylogen fiber.展开更多
To obtain a quantitative understanding of the influence of temperature on the performance of multi-gap resistive plate chambers (MRPCs), we have tested the performance of a 10-gap, 12-pad, 2×2×12 cm2 activ...To obtain a quantitative understanding of the influence of temperature on the performance of multi-gap resistive plate chambers (MRPCs), we have tested the performance of a 10-gap, 12-pad, 2×2×12 cm2 active area MRPC at different temperatures with cosmic rays. Presented are results from measurements of high-voltage scans, noise rate, dark current, streamer, time resolution, count rate, charge spectrum, and detection efficiency. The test results show that the MRPC performance is significantly affected by temperature arising from the temperature- dependence of the glass resistivity.展开更多
In order to determine the environmental effects on the luminescence properties of a phosphor layer for high-power light emitting diodes, a high humidity and temperature test (85℃/85%RH) and a thermal aging test (8...In order to determine the environmental effects on the luminescence properties of a phosphor layer for high-power light emitting diodes, a high humidity and temperature test (85℃/85%RH) and a thermal aging test (85℃) were performed on silicone/YAG phosphor composites. The luminescence properties of silicone/phosphor composites are monitored by a fluorescence spectrometer. The results show that high temperature could result in an increase in conversion efficiency of composites during the early aging stage and red shift of YAG phosphor; and high humidity could result in a significant decrease in conversion efficiency of composites while having a small influence upon the optimal excitation wavelength of the YAG phosphor.展开更多
Wire+arc additive manufacturing(WAAM)is considered an innovative technology that can change the manufacturing landscape in the near future.WAAM offers the benefits of inexpensive initial system setup and a high deposi...Wire+arc additive manufacturing(WAAM)is considered an innovative technology that can change the manufacturing landscape in the near future.WAAM offers the benefits of inexpensive initial system setup and a high deposition rate for fabricating medium-and large-sized parts such as die-casting tools.In this study,AISI H13 tool steel,a popular die-casting tool metal,is manufactured by cold metal transfer(CMT)-based WAAM and is then comprehensively analyzed for its microstructural and mechanical properties.Location-dependent phase combinations are observed,which could be explained by nonequilibrium thermal cycles that resulted from the layer-by-layer stacking mechanism used in WAAM.In addition,remelting and reheating of the layers reduces welding anomalies(e.g.,pores and voids).The metallurgical characteristics of the H13 strongly correlate with the mechanical properties.The combinations of phases at different locations of the additively manufactured part exhibit a periodic microhardness profile.Martensite,Retained Austenite,Ferrite,and Carbide phases are found in combination at different locations of the part based on the part’s temperature distribution during additive deposition.Moreover,the tensile properties at elevated temperatures(23℃,300℃,and 600℃)are comparable to those from other WAAM and additive manufacturing(AM)processes.The X-ray diffraction results verify that the microstructural stability of the fabricated parts at high temperatures would allow them to be used in high temperatures.展开更多
The overheating problems of terminal connectors severely threaten the operation of ultra-high voltage projects and cause enormous losses of economy,so a higher currentcarrying reliability of the connectors has an impo...The overheating problems of terminal connectors severely threaten the operation of ultra-high voltage projects and cause enormous losses of economy,so a higher currentcarrying reliability of the connectors has an important engineering significance with the development of transmission capacity.In this paper,a bivariate mathematical model of contact resistance as functions of temperature and tightening torque was deduced based on the large current temperature rise tests.To perform such analysis,four typical terminal connectors,namely:overlapping terminal of aluminum plates,overlapping terminal of copper plates,overlapping terminal of plates with clad layer and overlapping terminal of copper rod with aluminum clamp,were chosen for the experiments.The changing rules of DC resistance with different tightening torques and different currents were studied.Then the empirical formula of contact resistance was deduced.Finally,temperature calculations of different terminal connectors were realized to verify the effectiveness of the bivariate mathematical model.展开更多
In order to improve the overall performance of high temperature superconducting (HTS) motor, a radial connection torque tube with high strength and low thermal leakage has been designed. Firstly, fiberglass epoxy co...In order to improve the overall performance of high temperature superconducting (HTS) motor, a radial connection torque tube with high strength and low thermal leakage has been designed. Firstly, fiberglass epoxy composite is chosen as con- struction material. The structural size of the torque tube is obtained by means of load analysis and theoretical calculation. Secondly, thermal leakage of the torque tube is calculated with both theo- retical method and 3D finite-element analysis (FEA). According to the result of the thermal analysis and mechanical loads, the struc- tural stresses of the torque tube are also obtained by FEA method. Lastly, a low temperature test platform is developed to verify the strength and the thermal leakage of the torque tube. The results show that the maximal shear stress of the torque tube is 24.3 MPa and thermal leakage of torque tube is 10.5 W, which satisfy the design requirements of the HTS motor. The torque tube also works in good condition at full-power and full-torque testing of the motor. The design method is also applicable for other similar design of torque tube in other applications.展开更多
A simplified mathematical model was created for measurement of thermal expansion coefficients of thinsheet materials with holographic technique. Experimental set-ups corresponding to the mathematicalmodel were designe...A simplified mathematical model was created for measurement of thermal expansion coefficients of thinsheet materials with holographic technique. Experimental set-ups corresponding to the mathematicalmodel were designed and built for both tests above room temperature and at low temperatures. Afringe control technique was introduced for low temperature measurements to compensate rigid bodymovement. Thin sheet specimens of silicon and aluminum alloy (7075) were tested with the developedtechnique. The tested results are in good agreement with reported data and thus verify the validityof the developed technique. The thermal expansion coefficients of the tested materials ranged from2.5×10-6C-1 to 23.6×0-60C-1.展开更多
An attempt is made to investigate the ability of the revised K FIX code to the solution to natural convection. The new experimental data of the benchmark problem of the IAEA coordinated research program (CRP 3) on hea...An attempt is made to investigate the ability of the revised K FIX code to the solution to natural convection. The new experimental data of the benchmark problem of the IAEA coordinated research program (CRP 3) on heat transport and afterheat removal for GCRs under accident conditions provided by JAERI are used to calculate nitrogen natural convection in the pressurized vessel and air natural convection in the reactor cavity by using this revised code. Based on analysis, a refined mesh is used to solve the differential equations so as to get more detailed and more accurate result. The obtained velocity profiles are consistent with the result of TRIO EF code and the result of Bechtel laboratory. It can be drawn that the revised K FIX code can be used to solve this kind of problems.展开更多
文摘The meteorological measurement automatic temperature testing system has a defective image. To solve the problem such as noise and insufficient contrast, and put forward the research program for image pretreatment, the median filter, histogram equalization and image binarization, methods were used to remove noise and enhance images. Results showed that feature points were clear and accurate after the experiment. This simulation experiment prepared for the follow-up subsequent recognition process.
基金This work is supported by the NationalNatural Science Foundation of China (No. 11872207);the Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYCX18_0266)the Fundamental Research Funds for the Central Universities(No.kfjj20180105)
文摘A self-sensing test method for the temperature of piezoelectric stack,based on the high correlation between the static capacitance and the stack temperature,is proposed in order to construct a self-sufficient methodology of temperature measurement. Firstly,a theoretical model of static capacitance of the piezoelectric stack under preload was set up,and the influence of preload on the static capacitance was analyzed. Secondly,the correctness of the model was verified by static capacitance test experiments under various preloading conditions. Finally, the temperature measurement experiments at low-temperature stage for two kinds of piezoelectric stacks,namely the lowtemperature-resistant piezoelectric stack and conventional piezoelectric stack, were conducted under various preloading conditions using a polynomial fitting method. The results,which validate the accuracy of the test method,show that the maximum temperature deviations of the two kinds of piezoelectric stack are 3.9 ℃ and 2.8 ℃,respectively,when the preload force is close to the specified value. The test method uses the piezoelectric stack itself as a temperature sensor,which does not require additional equipment for temperature sensing,so that the space and equipment cost could be economized. And the test for static capacitance is concise and convenient,which indicates that in the cooling process,a concise and efficient test of the temperature of the piezoelectric stack could be realized so as to grasp the current temperature change in time.
文摘he thermal performance test of the horizontal coaxial double tube hot gas duct (HGD) with an internal thermal insulation for the 10MW High Temperature Reactor Test Module (HTR10) was conducted on a Helium Test Loop(HETL). The present paper deals with the technical feature of the HETL, the test section and the thermal performance test of the HGD. The HGD test section with a triple tube structure includes an inner heater, a HGD model and a coldhot gas mixer. A counterflow of cold and hot helium gas under the pressure of about 3.0 MPa and the minimum temperature of 100℃ in the annular passage and the maximum of 950℃ in the central tube of the HGD model was formed. The HGD model was undergone 20 times of pressure cycle test under the pressure ranging from 0.1 to 3.4 MPa, 18 times of the temperature cycle test under the temperature ranging from 100 to 950℃ and high temperature (700 to 950℃) helium flow test for a period of more than 350 hours. The effective thermal conductivity (λeff) of the internal insulation of the HGD was investigated experimentally. The relationship of the effective thermal conductivity with the average tmperature of the internal insulation layer is λeff(W/m/℃)=0.3512+0.0003T(℃). The test results indicate that the HGD model has good abilities to resist heat flux from the central tube to the annular passage, temperature variations, and pressure variations.
基金This manuscript is supported by the National Natural Science Foundation of China(Grant numbers:52108398,52225806,52078063)the Open Fund of Key Laboratory of Special Environment Road Engineering of Hunan Province(kfj210502).
文摘This study normalized the mixture's fatigue behavior at various temperatures,and the strength and fatigue tests of the mixture were conducted.The stress state of the asphalt mixture includes direct tensile,uniaxial compression,and indirect tensile.The Desai yield surface and fatigue path were proposed.And a normalized fatigue characteristics model of the mixture was established.The following conclusions were obtained.With the increases in the loading rate,the strength of the asphalt mixture increased.As the temperature increases,the strength of the mixture is reduced.At various temperatures and rates,the strength forms a closed curved surface.The Desai strength yield surface was established,which forms a closed curved surface.When the loading rate and temperature are below a certain critical line,the asphalt mixture will not undergo strength damage.At a fixed stress state,the fatigue damage path of the mixture was determined.The stress ratio was determined considering the influence of the loading rate.In this way,a normalized model can be described to express the asphalt mixture fatigue properties at various temperatures and stress levels.For the asphalt mixture in an indirect tensile state,the normalized fatigue equation parameter is 4.09.This model is more suitable for reflecting the viscous-elastic behavior of the mixtures than the fatigue equation determined by the notional stress ratio.
文摘The Jing-well point temperatures test method is a method to diagnose and guide the treatment of diseases by measuring the subjects' symmetrical well point temperature. it is improved from the method of knowing heat sensitivity. The application of Jing-well point temperatures test method is wide, and it can be used in internal and external gynecology and pediatrics and facial features department. at the same time, it has the advantage of objective and accurate diagnosis. The old law has some shortcomings, such as poor intuition, unavoidable omission of information, incomplete interpretation of information and so on. In this paper, Excel software is used to transform the data into line chart form, which improves the intuition and comprehensiveness of this method, so that the data can be better interpreted and used. It is newly proposed in this article that in addition to observing the longitudinal di fference of well point temperature, more attention should be paid to the horizontal contrast difference of well point temperature in different meridians. The article also summarizes a number of treatment methods, including acupuncture, moxa moxibustion, cupping and scraping, and the selection of acupoints, including mother acupoints, tenderness points and heat-sensitive moxibustion, so that doctors can combine traditional Chinese medicine professional knowledge in clinic.
基金National Key R&D Plan Project(No.2021YFC3090102)。
文摘Temperature control curve is the key to achieving temperature control and crack prevention of high concrete dam during construction,and its rationality depends on the accurate measurement of temperature stress.With the simulation testing machine for the temperature stress,in the present study,we carried out the deformation process tests of concrete under three temperature curves:convex,straight and concave.Besides,we not only measured the early-age elastic modulus,creep parameters and stress process,but also proposed the preferred type.The results show that at early age,higher temperature always leads to greater elastic modulus and smaller creep.However,the traditional indoor experiments have underestimated the elastic modulus and creep development at early age,which makes the calculated value of temperature stress too small,thus increasing the cracking risk.In this study,the stress values of the three curves calculated based on the strain and early-age parameters are in good agreement with the temperature stress measured by the temperature stress testing machine,which verifies the method accuracy.When the temperature changes along the concave curve,the law of stress development is in consistent with that of strength.Under this condition,the stress fluctuation is small and the crack prevention safety of the concave type is higher,so the concave type is better.The test results provide a reliable basis and support for temperature control curve design and optimization of concrete dams.
基金financially supported by the National Basic Research Program of China (No.2011CB605506)
文摘The purpose of this paper is to estimate the fatigue crack growth threshold of a high-Nb TiAl alloy at the different temperatures based on scanning electron microscopy (SEM) in-situ observation. The results indicated that the fatigue crack growth threshold △Kth of a nearly lamellar high-Nb TiAl alloy with 8% Nb content at room temperature and 750℃ was determined as 12.89 MPa.m^1/2 and 8.69 MPa.m^1/2, respectively. The effect of the elevated temperature on the fatigue crack growth threshold cannot be ignored. At the same time, the early stage of fatigue crack propagation exhibited multicrack initiation and bridge-link behavior.
基金Project 2002CB211703 supported by the National Basic Research Program of China
文摘Variable temperature and pressure adsorption tests were conducted on four coal samples with different coal ranks, under simulated temperatures and pressures corresponding to coal reservoirs at different depths. The regularity of the variation in the amounts of adsorption by coals under variable temperature and pressure and 30 ℃ isothermal conditions are compared and the adsorption characteristics of coal under the composite effect of temperature and pressure were obtained. The adsorption test and data processing method of coal under variable temperature and pressure are presented and the effect of the mechanism of temperature and pressure on the adsorption capacity of coal has been studied. The research results are of significant importance in the investigation of coalbed methane storage mechanism and for the prediction of the amounts of coalbed methane at various depths.
文摘The influence of processing variables on the mechanical properties of a nanostructured Al-10 wt.%Cu alloy was investigated.Stress-strain microprobe®system(SSM)and its automated ball indentation®(ABI®)test were used for evaluating the mechanical properties of this alloy.The tests were conducted at 21℃ on the bulk samples that were mechanically alloyed for 6 h at two ball-to-powder mass ratios(BPR)of 30:1 and 90:1.Furthermore,the tests were conducted at 200 and 400℃ on the samples that were processed at BPR of 90:1.Increasing BPR resulted in raising the final indentation load from(316±26)to(631±9)N and reducing the final indentation depth from 111 to 103μm.Regarding the samples that were processed at BPR of 90:1,increasing the test temperature from 21 to 400℃ resulted in decreasing the final load from(631±9)to(125±1)N and increasing the final depth from 103 to(116±1)μm.The sample processed at BPR of 90:1 and tested at 21℃ revealed the highest strength and the least deformability while the sample processed at BPR of 90:1 and tested at 400℃ exhibited the lowest strength and the greatest deformability,as compared to all samples under study.
基金Funded by Key Scientific Research Projects Plan of Henan Higher Education Institutions(No.19A460025)National Natural Science Foundation of China(No.51809127)。
文摘Sorbitol,triethanolamine,sodium benzoate,boric acid,and sodium carbonate were mixed to prepare a waterborne rust inhibitor.A temperature and humidity accelerated corrosion test was applied to investigate the corrosion behaviour of waterborne rust inhibitor coated Q235 steel and original Q235 steel,which was carried out in a temperature and humidity test chamber(WSHW-1000)at a temperature of 80℃and humidity of 95%.Compared with the original Q235,waterborne rust inhibitor coated Q235 has better resistance to corrosion in hot and humid ambient conditions.Electrochemical impedance spectroscopy and potentiodynamic polarization were measured with a three-electrode cell in 3.5%NaCl aqueous solution on a CHI760E potentiostat/galvanostat.Molecular dynamics was simulated to verify the synergistic corrosion inhibitory mechanism of sodium carbonate and triethanolamine.The test shows that the prepared waterborne rust inhibitor can reduce the tendency of Q235 to corrosion and can also effectively reduce the corrosion rate.
基金The 11th Postgraduate Technology Innovation Project of North University of China(No.20141147)
文摘Based on LabVlEW platform, a distributed dynamic storage testing system is designed for measuring transient high temperature signals of explosion field. Using a highpower semiconductor laser as heat source, a traceable dynamic calibration system is established to perform dynamic calibration of thermocouples. With quantumbehaved particle swam optimization (QP-SO) algorithm on MATLAB platform, a model of dynamic compensation filter is established. It is used by LabVIEW that calls MATLAB Script nodes or COM components to accomplish the mixed programming of LabVIEW and MATLAB, further to compensate the temperature values of the thermocouples dynamically. The experimental results show that the technique that combines temperature measurement system with LabVIEW platform is applied well in testing the explosion temperature of ther mobaric weaponry and makes the compensation values closer to the actual signals.
文摘To discuss the pavement performance of basalt fiber-modified asphalt mixtures,the optimum dosages of asphalt and fibers are studied by the Marshall test and the rutting test.The results demonstrate that the optimum dosages of asphalt and fibers are 4.63% and 0.3%,respectively.Then the pavement performances of basalt(polyester,xylogen)fiber-modified asphalt mixtures are investigated through high temperature stability tests,water stability tests and low temperature crack resistance tests.It indicates that the pavement performances of the fiber-modified asphalt mixtures such as rutting dynamic stability,freezing splitting tensile strength,low temperature crack resistance and so on are improved compared with control asphalt mixture.The results show that the pavement performances of asphalt mixtures can be improved by fiber-modifiers.Besides,the improvement effects of basalt fiber are superior to polyester fiber and xylogen fiber.
基金Supported by National Natural Science Foundation of China(41204133)Young Backbone of Scientific Research Plan of CDUT and Projects of International Cooperation and Exchanges NSFC(11020101059)
文摘To obtain a quantitative understanding of the influence of temperature on the performance of multi-gap resistive plate chambers (MRPCs), we have tested the performance of a 10-gap, 12-pad, 2×2×12 cm2 active area MRPC at different temperatures with cosmic rays. Presented are results from measurements of high-voltage scans, noise rate, dark current, streamer, time resolution, count rate, charge spectrum, and detection efficiency. The test results show that the MRPC performance is significantly affected by temperature arising from the temperature- dependence of the glass resistivity.
基金Project supported by the Key Project of the National Natural Science Foundation of China(No.50835005)the National High Technology Research and Development Program of China(No.2009AA03A1A3)
文摘In order to determine the environmental effects on the luminescence properties of a phosphor layer for high-power light emitting diodes, a high humidity and temperature test (85℃/85%RH) and a thermal aging test (85℃) were performed on silicone/YAG phosphor composites. The luminescence properties of silicone/phosphor composites are monitored by a fluorescence spectrometer. The results show that high temperature could result in an increase in conversion efficiency of composites during the early aging stage and red shift of YAG phosphor; and high humidity could result in a significant decrease in conversion efficiency of composites while having a small influence upon the optimal excitation wavelength of the YAG phosphor.
基金support of the Korea Institute of Industrial Technology as a project on the development of metal 3D printing materials and process optimization technology for medium-and large-sized transportation part mold manufacturing(KITECH JE200008)。
文摘Wire+arc additive manufacturing(WAAM)is considered an innovative technology that can change the manufacturing landscape in the near future.WAAM offers the benefits of inexpensive initial system setup and a high deposition rate for fabricating medium-and large-sized parts such as die-casting tools.In this study,AISI H13 tool steel,a popular die-casting tool metal,is manufactured by cold metal transfer(CMT)-based WAAM and is then comprehensively analyzed for its microstructural and mechanical properties.Location-dependent phase combinations are observed,which could be explained by nonequilibrium thermal cycles that resulted from the layer-by-layer stacking mechanism used in WAAM.In addition,remelting and reheating of the layers reduces welding anomalies(e.g.,pores and voids).The metallurgical characteristics of the H13 strongly correlate with the mechanical properties.The combinations of phases at different locations of the additively manufactured part exhibit a periodic microhardness profile.Martensite,Retained Austenite,Ferrite,and Carbide phases are found in combination at different locations of the part based on the part’s temperature distribution during additive deposition.Moreover,the tensile properties at elevated temperatures(23℃,300℃,and 600℃)are comparable to those from other WAAM and additive manufacturing(AM)processes.The X-ray diffraction results verify that the microstructural stability of the fabricated parts at high temperatures would allow them to be used in high temperatures.
基金This work was supported by the National Natural Science Foundation of China(51678548)the Science and Technology Project of the State Grid Corporation of China(GC71-16-003).
文摘The overheating problems of terminal connectors severely threaten the operation of ultra-high voltage projects and cause enormous losses of economy,so a higher currentcarrying reliability of the connectors has an important engineering significance with the development of transmission capacity.In this paper,a bivariate mathematical model of contact resistance as functions of temperature and tightening torque was deduced based on the large current temperature rise tests.To perform such analysis,four typical terminal connectors,namely:overlapping terminal of aluminum plates,overlapping terminal of copper plates,overlapping terminal of plates with clad layer and overlapping terminal of copper rod with aluminum clamp,were chosen for the experiments.The changing rules of DC resistance with different tightening torques and different currents were studied.Then the empirical formula of contact resistance was deduced.Finally,temperature calculations of different terminal connectors were realized to verify the effectiveness of the bivariate mathematical model.
基金Supported by the High Technology Research and Development Program of China(863 Program)(2008AA030601)
文摘In order to improve the overall performance of high temperature superconducting (HTS) motor, a radial connection torque tube with high strength and low thermal leakage has been designed. Firstly, fiberglass epoxy composite is chosen as con- struction material. The structural size of the torque tube is obtained by means of load analysis and theoretical calculation. Secondly, thermal leakage of the torque tube is calculated with both theo- retical method and 3D finite-element analysis (FEA). According to the result of the thermal analysis and mechanical loads, the struc- tural stresses of the torque tube are also obtained by FEA method. Lastly, a low temperature test platform is developed to verify the strength and the thermal leakage of the torque tube. The results show that the maximal shear stress of the torque tube is 24.3 MPa and thermal leakage of torque tube is 10.5 W, which satisfy the design requirements of the HTS motor. The torque tube also works in good condition at full-power and full-torque testing of the motor. The design method is also applicable for other similar design of torque tube in other applications.
文摘A simplified mathematical model was created for measurement of thermal expansion coefficients of thinsheet materials with holographic technique. Experimental set-ups corresponding to the mathematicalmodel were designed and built for both tests above room temperature and at low temperatures. Afringe control technique was introduced for low temperature measurements to compensate rigid bodymovement. Thin sheet specimens of silicon and aluminum alloy (7075) were tested with the developedtechnique. The tested results are in good agreement with reported data and thus verify the validityof the developed technique. The thermal expansion coefficients of the tested materials ranged from2.5×10-6C-1 to 23.6×0-60C-1.
文摘An attempt is made to investigate the ability of the revised K FIX code to the solution to natural convection. The new experimental data of the benchmark problem of the IAEA coordinated research program (CRP 3) on heat transport and afterheat removal for GCRs under accident conditions provided by JAERI are used to calculate nitrogen natural convection in the pressurized vessel and air natural convection in the reactor cavity by using this revised code. Based on analysis, a refined mesh is used to solve the differential equations so as to get more detailed and more accurate result. The obtained velocity profiles are consistent with the result of TRIO EF code and the result of Bechtel laboratory. It can be drawn that the revised K FIX code can be used to solve this kind of problems.