The accurate characterization of thermoelectric properties at low temperatures is crucial for the development of high-performance thermoelectric cooling devices. While measurement errors of thermoelectric properties a...The accurate characterization of thermoelectric properties at low temperatures is crucial for the development of high-performance thermoelectric cooling devices. While measurement errors of thermoelectric properties at temperatures above room temperature have been extensively discussed, there is a lack of standard measurement protocols and error analyses for low-temperature transport properties. In this study, we present a measurement system capable of characterizing all three key thermoelectric parameters, i.e., Seebeck coefficient, electrical conductivity, and thermal conductivity, for a single sample across a temperature range of 10 K to 300 K. We investigated six representative commercial Bi_(2)Te_(3)-based samples(three N-type and three P-type). Using an error propagation model, we systematically analyzed the measurement uncertainties of the three intrinsic parameters and the resulting thermoelectric figure of merit. Our findings reveal that measurement uncertainties for both N-type and P-type Bi_(2)Te_(3)-based materials can be effectively maintained below 5% in the temperature range of 40 K to 300 K. However, the uncertainties increase to over 10% at lower temperatures, primarily due to the relatively smaller values of electrical resistivity and Seebeck coefficients in this regime. This work establishes foundational data for Bi_(2)Te_(3)-based thermoelectric materials and provides a framework for broader investigations of advanced low-temperature thermoelectrics.展开更多
A Fourier analysis applied to the Mach-Zehnder interferometer （MZI） transmission spectrum for simultaneous refractive index （RI） and temperature measurements is proposed and experimentally demonstrated in this Let...A Fourier analysis applied to the Mach-Zehnder interferometer （MZI） transmission spectrum for simultaneous refractive index （RI） and temperature measurements is proposed and experimentally demonstrated in this Letter. In the fast Fourier transform （FFT） spectrum of the MZI transmission spectrum, several frequency components are generally observed, which means that the transmission spectrum of the MZI is formed by the superposition of some dual-mode interference （DMI） spectra, and each frequency component represents different core-cladding interferences. We can select some dominant frequency components in the FFT spectrum of the MZI transmission spectrum to take the inverse FFT （IFFT）. Then, the corresponding DMI patterns can be obtained. Due to the shift of the wavelength of these DMI spectra with changes in the environmental parameters, we can use the coefficient matrix of these DMI spectra for multi-parameter sensing. In this Letter, two DMI patterns are separated from the resultant transmission spectrum of the MZI. As the RI and temperature change, the shifts of the two DMI patterns with respect to the RI and temperature will be observed. The sensitivities of the RI and temperature are -137.1806 nm/RIU （RI unit） and 0.0860 nm/℃, and -22.9955 nm/RIU and 0.0610 nm/℃ for the two DMIs. Accordingly, it can be used to simultaneously measure RI and temperature changes. The approach can eliminate the influence of multiple interferences and improve the accuracy of the sensor.展开更多
Noninvasive technology for measuring instantaneously two-dimensional （2D） temperature distributions of flame using two-color planar laser induced fluorescence （PLIF） of OH is investigated. A calibration method is ...Noninvasive technology for measuring instantaneously two-dimensional （2D） temperature distributions of flame using two-color planar laser induced fluorescence （PLIF） of OH is investigated. A calibration method is researched and developed. This method is based on the calibration experiments with a laminar premixed flame and thermocouple, and avoids complex calculation and uncertainty of the spectrum parameters. Measurements for a flat burner at ambient temperature under atmospheric pressure are also presented; calibration results are used to diagnose a supersonic combustion in scramjet combustor. The conclusion indicates that this method is useful, and a better precision of calibration can be acquired by correcting the line shapes of the spectral lines and lasers.展开更多
The turbine blades operate under high temperature and high pressure conditions,and when using radiation thermometry,the influence of radiation from surrounding blades leads to measurement errors.To address this issue,...The turbine blades operate under high temperature and high pressure conditions,and when using radiation thermometry,the influence of radiation from surrounding blades leads to measurement errors.To address this issue,this paper develops a three-dimensional discretized dynamic radiation transfer model based on the blade shape of the turbine.The relationship between the radiation angle coefficient of the surrounding blades and the rotation angle of the blade under test is analyzed.The radiation angle coefficient is calculated using the triangular element method,and temperature inversion is performed based on the effective emissivity to compute the measurement error.The results show that under dynamic high temperature conditions,the temperature measurement error caused by reflection at the selected 60%leaf height point varies with the rotation angle,and the maximum reaches 25.58K.The angular coefficient exhibits periodic fluctuations with changes in rotation angle,and the maximum effective emissivity increases as the rotation angle increases.As the blade height increases,the impact of reflected radiation on radiometric temperature measurement errors shows a decreasing trend.This study provides a reference for radiation thermometry in dynamic high-temperature environments.展开更多
The 1.55μm laser technology is widely applied in military,information communication,biomedicine and other fields.With the deepening development of these application areas,the demand for novel 1.55μm laser gain media...The 1.55μm laser technology is widely applied in military,information communication,biomedicine and other fields.With the deepening development of these application areas,the demand for novel 1.55μm laser gain media is becoming increasingly urgent.This study reports a novel Yb^(3+),Er^(3+)co-doped KBa_(0.94)Ca_(0.06)Y(MoO_(4))_(3) (KBCYM)crystal.In this crystal,Yb^(3+)serves as a sensitizer,significantly enhancing the emission intensity of Er^(3+)in both visible and near-infrared bands.Notably,when the concentration of Yb^(3+)reaches 6 mol%,the emission intensity peaks at 1.55μm.Optical cross-section calculations reveal that the crystal exhibits a low laser pumping threshold at this concentration,demonstrating its potential as a laser gain medium.However,the crystal inevitably generates thermal effects during operation,which may adversely affect its performance.Therefore,real-time monitoring of the operating temperature is crucial.The thermal stability of the crystal was evaluated by measuring the temperature dependence of its luminescence intensity in the near-infrared band.Remarkably,even when the temperature rises to 553 K,the emission intensity at 1.55μm only decreases by 10.9%.Additionally,the temperature sensing performance was evaluated using fluorescence intensity ratio techniques,yielding absolute and relative sensitivities of 0.00981 K^(-1)at 453 K and 1.32%/K at 303 K,respectively,highlighting its potential for optical temperature sensing.Finally,through leveraging the unique properties of Yb^(3+),Er^(3+):KBCYM crystals,we successfully developed 1.55μm luminescent optical devices with practical applications.These devices not only exhibit efficient luminescent performance,but also possess a self-temperature measu rement functio n,opening up new avenues for the further development of laser technology.展开更多
Arching and cracking of joints between slabs have become a problem in China Railway Track System(CRTS)II slab track.The slab track is susceptible to complex temperature variations as a longitudinal continuous structur...Arching and cracking of joints between slabs have become a problem in China Railway Track System(CRTS)II slab track.The slab track is susceptible to complex temperature variations as a longitudinal continuous structure.Based on measured data,a thermal-mechanical coupling model of the track was established.The deformation characteristics and interfacial damage behavior of joints under typical temperature fields were studied.The findings indicate that the annual extreme temperature range of the slab track,fluctuates from−1.4 to 49.8℃.The annual temperature gradient within the vertical depth range of 0 to 0.2 m of the track varies between−16.19℃/m and 30.15℃/m.The vertical deformation of joints is significantly influenced by high temperatures,with a maximum measured deformation of 0.828 mm.The joint seams are primarily affected by low temperatures,which lead to a separation of 0.9 to 1.0 mm.Conversely,interlayer damage of joints is predominantly influenced by elevated temperatures.In summer,the maximum ratio of interface damage area in the joint can reach up to 95%,with the maximum debonding area ratio can be as high as 84%.The research results can provide help for joint damage regularity and deformation control of CRTS II slab track.展开更多
With the widespread adoption of ultra-precision machining(UPM)in manufacturing,accurately monitoring the temperature within micro-scale cutting zones has become crucial for ensuring machining quality and tool longevit...With the widespread adoption of ultra-precision machining(UPM)in manufacturing,accurately monitoring the temperature within micro-scale cutting zones has become crucial for ensuring machining quality and tool longevity.This review comprehensively evaluates modern in-process cutting temperature measurement methods,comparing conventional approaches and emerging technologies.Thermal conduction-based and radiation-based measurement paradigms are analyzed in terms of their merits,limitations,and domain-specific applicability,particularly with regard to the unique challenges involving micro-scale cutting zones in UPM.Special emphasis is placed on micro-scale sensor-integrated tools and self-sensing tools that enable real-time thermal monitoring at cutting edges.Furthermore,we explore thermal monitoring and management techniques for atomic and close-to-atomic scale manufacturing(ACSM),as well as the transformative potential of emerging technologies like artificial intelligence(AI),internet of things(IoT),and data fusion for machining temperature measurement.This review may serve as a reference for UPM cutting temperature measurement research,helping foster the development of optimized process control technologies.展开更多
A high precision, high antijamming multipoint infrared telemetry system was developed to measure the piston temperature in internal combustion engine. The temperature at the measuring point is converted into correspon...A high precision, high antijamming multipoint infrared telemetry system was developed to measure the piston temperature in internal combustion engine. The temperature at the measuring point is converted into corresponding voltage signal by the thermo-couple first. Then after the V/F stage, the voltage signal is converted into the frequency signal to drive the infrared light-emitting diode to transmit infrared pulses. At the receiver end, a photosensitive audion receives the infrared pulses. After conversion, the voltage recorded by the receiver stands for the magnitude of temperature at the measuring point. Test results of the system indicate that the system is practical and the system can perform multipoint looping temperature measurements for the piston.展开更多
The plastic work-heat conversion coefficient is one key parameter for studying the work-heat conversion under dynamic deformation of materials. To explore this coefficient of 7075-T651 aluminum alloy under dynamic com...The plastic work-heat conversion coefficient is one key parameter for studying the work-heat conversion under dynamic deformation of materials. To explore this coefficient of 7075-T651 aluminum alloy under dynamic compression, dynamic compression experiments using the Hopkinson bar under four groups of strain rates were conducted, and the temperature signals were measured by constructing a transient infrared temperature measurement system. According to stress versus strain data as well as the corresponding temperature data obtained through the experiments, the influences of the strain and the strain rate on the coefficient of plastic work converted to heat were analyzed.The experimental results show that the coefficient of plastic work converted to heat of 7075-T651 aluminum alloy is not a constant at the range of 0.85–1 and is closely related to the strain and the strain rate. The change of internal structure of material under high strain rate reduces its energy storage capacity, and makes almost all plastic work convert into heat.展开更多
A new method for reconstructing the geological history of hydrocarbon accumulation is developed, which are constrained by U-Pb isotope age and clumped isotope((35)47) temperature of host minerals of hydrocarbon-bearin...A new method for reconstructing the geological history of hydrocarbon accumulation is developed, which are constrained by U-Pb isotope age and clumped isotope((35)47) temperature of host minerals of hydrocarbon-bearing inclusions. For constraining the time and depth of hydrocarbon accumulation by the laser in-situ U-Pb isotope age and clumped isotope temperature, there are two key steps:(1) Investigating feature, abundance and distribution patterns of liquid and gaseous hydrocarbon inclusions with optical microscopes.(2) Dating laser in-situ U-Pb isotope age and measuring clumped isotope temperature of the host minerals of hydrocarbon inclusions. These technologies have been applied for studying the stages of hydrocarbon accumulation in the Sinian Dengying gas reservoir in the paleo-uplift of the central Sichuan Basin. By dating the U-Pb isotope age and measuring the temperature of clumped isotope((35)47) of the host minerals of hydrocarbon inclusions in dolomite, three stages of hydrocarbon accumulation were identified:(1) Late Silurian: the first stage of oil accumulation at(416±23) Ma.(2) Late Permian to Early Triassic: the second stage of oil accumulation between(248±27) Ma and(246.3±1.5) Ma.(3) Yanshan to Himalayan period: gas accumulation between(115±69) Ma and(41±10) Ma. The reconstructed hydrocarbon accumulation history of the Dengying gas reservoir in the paleo-uplift of the central Sichuan Basin is highly consistent with the tectonic-burial history, basin thermal history and hydrocarbon generation history, indicating that the new method is a reliable way for reconstructing the hydrocarbon accumulation history.展开更多
In order to study the evolution of the freezing fringe and final lenses of frost susceptible soils and advance the understanding of frost heave and mechanism of frost heave control, we used an open one-dimensional fro...In order to study the evolution of the freezing fringe and final lenses of frost susceptible soils and advance the understanding of frost heave and mechanism of frost heave control, we used an open one-dimensional frost heave test system of infrared radiation technology, instead of a traditional thermistor method. Temperatures of the freezing fringe and segregated ice were measured in a non-contact mode. The results show that accurate and precise temperatures of ice segregation can be obtained by infrared thermal imaging systems. A self-developed inversion program inverted the temperature field of frozen soils. Based on our analysis of temperature variation in segregated ice and our study of the relationship between temperature and rate of ice segregation in cooling and warming processes during intermittent freezing, the mechanism of decreasing frost heave of frozen soils by controlling the growth of final lenses with an intermittent freezing mode, can be explained properly.展开更多
In a context of cryosphere degradation caused by climate warming,rock temperature is one of the main driving factors of rockfalls that occur on high-elevation mountain slopes.In order to improve the knowledge of this ...In a context of cryosphere degradation caused by climate warming,rock temperature is one of the main driving factors of rockfalls that occur on high-elevation mountain slopes.In order to improve the knowledge of this critical relationship,it is necessary to increase measurement capability of rock temperature and its variability in different lithological and slope/aspect conditions,and also to increase local scale studies,increasing the quality and the comparability of the data.This paper shows an example of metrological characterization of sensors used for rock temperature measurement in mountain regions,by means of the measurement uncertainty.Under such approach,data and results from temperature measurements carried out in the Bessanese high-elevation experimental site(Western European Alps)are illustrated.The procedures for the calibration and field characterization of sensors allow to measure temperature in different locations,depths and lithotypes,within 0.10°C of overall uncertainty.This work has highlighted that metrological traceability is fundamental to asses data quality and establish comparability among different measurements;that there are strong differences between air temperature and near-surface rock temperature;and that there are significant differences of rock temperature acquired in different aspect conditions.Finally,solar radiation,slope/aspect conditions and lithotype,seem to be the main driving factors of rock temperature.展开更多
An infrared colorimetric radiation thermometrical system was established based on the theory of optical radiation. The dynamic temperature history of fuel air explosive (FAE) was measured to obtain the temperature res...An infrared colorimetric radiation thermometrical system was established based on the theory of optical radiation. The dynamic temperature history of fuel air explosive (FAE) was measured to obtain the temperature responses of primary initiation FAE and secondary initiation FAE in real time. And the characteristics of their temperature history curves were compared and analyzed. The results show that the primary initiation FAE has higher explosion temperature and longer duration compared to the secondary initiation FAE.展开更多
It is well known that optical tomography can accurately and quantitatively reconstruct the refractive index field of a transparent medium and display the three dimensional image of other physical quantities relevant t...It is well known that optical tomography can accurately and quantitatively reconstruct the refractive index field of a transparent medium and display the three dimensional image of other physical quantities relevant to temperature or density. In this paper, a new multidirectional holographic interferometric system is built, and two kinds of image reconstruction algorithms are introduced and an automatic image processing system of interferogram is designed. A three dimentsional asymmetric gas flow field above a combustor is expertmentally investigated with holographic interferometry. The reconstructed temperatures are similar to those measured with a thermocouple.展开更多
Exhaust gas temperature is an important factor in NOx, THC and PM emissions of engines. Especially 2D temperature and concentration distribution plays an important role for the engine efficiency. A thermocouple is int...Exhaust gas temperature is an important factor in NOx, THC and PM emissions of engines. Especially 2D temperature and concentration distribution plays an important role for the engine efficiency. A thermocouple is intrinsically a point temperature measurement method and noncontact 2D temperature distribution cannot be attained by thermocouples. Recently, as a measurement technique with high sensitivity and high response, laser diagnostics has been developed and applied to the actual engine combustions. With these engineering developments, transient phenomena such as start-ups and load changes in engines have been gradually elucidated in various conditions. In this study, the theoretical and experimental research has been conducted in order to develop the noncontact and fast response 2D temperature and concentration distribution measurement method. The method is based on a Computed Tomography （CT） method using absorption spectra of water vapor at 1388 nm. It has been demonstrated that the method has been successfully applied to engine exhausts to measure 2D temperature distributions.展开更多
The magnetic field is one of the most important parameters in solar physics,and a polarimeter is the key device to measure the solar magnetic field.Liquid crystals based Stokes polarimeter is a novel technology,and wi...The magnetic field is one of the most important parameters in solar physics,and a polarimeter is the key device to measure the solar magnetic field.Liquid crystals based Stokes polarimeter is a novel technology,and will be applied for magnetic field measurement in the first space-based solar observatory satellite developed by China,Advanced Space-based Solar Observatory.However,the liquid crystals based Stokes polarimeter in space is not a mature technology.Therefore,it is of great scientific significance to study the control method and characteristics of the device.The retardation produced by a liquid crystal variable retarder is sensitive to the temperature,and the retardation changes 0.09°per 0.10℃.The error in polarization measurement caused by this change is 0.016,which affects the accuracy of magnetic field measurement.In order to ensure the stability of its performance,this paper proposes a high-precision temperature control system for liquid crystals based Stokes polarimeter in space.In order to optimize the structure design and temperature control system,the temperature field of liquid crystals based Stokes polarimeter is analyzed by the finite element method,and the influence of light on the temperature field of the liquid crystal variable retarder is analyzed theoretically.By analyzing the principle of highprecision temperature measurement in space,a high-precision temperature measurement circuit based on integrated operational amplifier,programmable amplifier and 12 bit A/D is designed,and a high-precision space temperature control system is developed by applying the integral separation PI temperature control algorithm and PWM driving heating films.The experimental results show that the effect of temperature control is accurate and stable,whenever the liquid crystals based Stokes polarimeter is either in the air or vacuum.The temperature stability is within±0.0150℃,which demonstrates greatly improved stability for the liquid crystals based Stokes polarimeter.展开更多
A two-temperature(2 T)thermal non-equilibrium model is developed to address the thermal nonequilibrium phenomenon that inevitably exists in the reverse-polarity plasma torch(RPT)and applied to numerically investigate ...A two-temperature(2 T)thermal non-equilibrium model is developed to address the thermal nonequilibrium phenomenon that inevitably exists in the reverse-polarity plasma torch(RPT)and applied to numerically investigate the plasma flow characteristics inside and outside the RPT.Then,a detailed comparison of the results of the 2 T model with those of the local thermal equilibrium(LTE)model is presented.Furthermore,the temperature of the plasma jet generated by a RPT and the RPT’s voltage are experimentally measured to compare and validate the result obtained by different models.The differences of the measured excitation temperature and the arc voltage between the 2 T model and experimental measurement are less than 13%and 8%,respectively,in all operating cases,validating the effectiveness of the 2 T model.The LTE model overestimates the velocity and temperature distribution of the RPT and its plasma jet,showing that thermal non-equilibrium phenomena cannot be neglected in the numerical modelling of the RPT.Unlike other common hot cathode plasma torches,the thermal non-equilibrium phenomenon is found even in the arc core of the RPT,due to the strong cooling effect caused by the big gas flow rate.展开更多
A novel method based on wavelength-multiplexed line-of-sight absorption and profile fitting for nonuniform flow field measurement is reported. A wavelength scanning combing laser temperature and current modulation WMS...A novel method based on wavelength-multiplexed line-of-sight absorption and profile fitting for nonuniform flow field measurement is reported. A wavelength scanning combing laser temperature and current modulation WMS scheme is used to implement the wavelength-multi- plexed-profile fitting method. Second harmonic （2f） signal of eight H20 transitions features near 7,170 cm^-1 are measured in one period using a single tunable diode laser. Spatial resolved temperature distribution upon a CH4/air premixed flat flame burner is obtained. The result validates the feasibility of strategy for non-uniform flow field diagnostics by means of WMS-2f TDLAS.展开更多
There currently does not exist in industry a reliable method for the detection of rail foot flaws.Like their head-based counterparts,foot flaws result in broken rail with potentially catastrophic consequences.A propos...There currently does not exist in industry a reliable method for the detection of rail foot flaws.Like their head-based counterparts,foot flaws result in broken rail with potentially catastrophic consequences.A proposed area of research for the detection of these flaws is thermography,a non-contact method of measuring and analysing infrared emissions from an object under test.In industry,active excitation thermography is the most common,requiring an excitation source.This paper will present a temperature measurement system and a method of transient temperature extraction from the running rails for the effects of a passing train to evaluate heat transfer in the practical rail environment.The outcomes of these results will provide future direction in the development of a rail heat transfer model and determine if train passage provides enough active excitation for a thermography-based detection technique.展开更多
This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put ...This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 52172259)the National Key Research and Development Program of China (Grant Nos. 2021YFA0718700 and 2022YFB3803900)the Fundamental Research Funds for the Inner Mongolia Normal University (Grant No. 2022JBTD008)。
文摘The accurate characterization of thermoelectric properties at low temperatures is crucial for the development of high-performance thermoelectric cooling devices. While measurement errors of thermoelectric properties at temperatures above room temperature have been extensively discussed, there is a lack of standard measurement protocols and error analyses for low-temperature transport properties. In this study, we present a measurement system capable of characterizing all three key thermoelectric parameters, i.e., Seebeck coefficient, electrical conductivity, and thermal conductivity, for a single sample across a temperature range of 10 K to 300 K. We investigated six representative commercial Bi_(2)Te_(3)-based samples(three N-type and three P-type). Using an error propagation model, we systematically analyzed the measurement uncertainties of the three intrinsic parameters and the resulting thermoelectric figure of merit. Our findings reveal that measurement uncertainties for both N-type and P-type Bi_(2)Te_(3)-based materials can be effectively maintained below 5% in the temperature range of 40 K to 300 K. However, the uncertainties increase to over 10% at lower temperatures, primarily due to the relatively smaller values of electrical resistivity and Seebeck coefficients in this regime. This work establishes foundational data for Bi_(2)Te_(3)-based thermoelectric materials and provides a framework for broader investigations of advanced low-temperature thermoelectrics.
基金supported by the National Natural Science Foundation of China(Nos.61327012 and 61275088)the Research Foundation of Education Bureau of Shaanxi Province,China(No.14JS073)+2 种基金the Youth Science and Technology Innovation Fund of Xi’an Shiyou University(No.2014QN005)the Excellent MA Theses Fund of Xi’an Shiyou University(No.2014yp130816)the Graduate Student Innovation Fund(No.2014cx130842)
文摘A Fourier analysis applied to the Mach-Zehnder interferometer （MZI） transmission spectrum for simultaneous refractive index （RI） and temperature measurements is proposed and experimentally demonstrated in this Letter. In the fast Fourier transform （FFT） spectrum of the MZI transmission spectrum, several frequency components are generally observed, which means that the transmission spectrum of the MZI is formed by the superposition of some dual-mode interference （DMI） spectra, and each frequency component represents different core-cladding interferences. We can select some dominant frequency components in the FFT spectrum of the MZI transmission spectrum to take the inverse FFT （IFFT）. Then, the corresponding DMI patterns can be obtained. Due to the shift of the wavelength of these DMI spectra with changes in the environmental parameters, we can use the coefficient matrix of these DMI spectra for multi-parameter sensing. In this Letter, two DMI patterns are separated from the resultant transmission spectrum of the MZI. As the RI and temperature change, the shifts of the two DMI patterns with respect to the RI and temperature will be observed. The sensitivities of the RI and temperature are -137.1806 nm/RIU （RI unit） and 0.0860 nm/℃, and -22.9955 nm/RIU and 0.0610 nm/℃ for the two DMIs. Accordingly, it can be used to simultaneously measure RI and temperature changes. The approach can eliminate the influence of multiple interferences and improve the accuracy of the sensor.
基金supported by the National Natural Science Foundation of China under Grant No.11272338
文摘Noninvasive technology for measuring instantaneously two-dimensional （2D） temperature distributions of flame using two-color planar laser induced fluorescence （PLIF） of OH is investigated. A calibration method is researched and developed. This method is based on the calibration experiments with a laminar premixed flame and thermocouple, and avoids complex calculation and uncertainty of the spectrum parameters. Measurements for a flat burner at ambient temperature under atmospheric pressure are also presented; calibration results are used to diagnose a supersonic combustion in scramjet combustor. The conclusion indicates that this method is useful, and a better precision of calibration can be acquired by correcting the line shapes of the spectral lines and lasers.
文摘The turbine blades operate under high temperature and high pressure conditions,and when using radiation thermometry,the influence of radiation from surrounding blades leads to measurement errors.To address this issue,this paper develops a three-dimensional discretized dynamic radiation transfer model based on the blade shape of the turbine.The relationship between the radiation angle coefficient of the surrounding blades and the rotation angle of the blade under test is analyzed.The radiation angle coefficient is calculated using the triangular element method,and temperature inversion is performed based on the effective emissivity to compute the measurement error.The results show that under dynamic high temperature conditions,the temperature measurement error caused by reflection at the selected 60%leaf height point varies with the rotation angle,and the maximum reaches 25.58K.The angular coefficient exhibits periodic fluctuations with changes in rotation angle,and the maximum effective emissivity increases as the rotation angle increases.As the blade height increases,the impact of reflected radiation on radiometric temperature measurement errors shows a decreasing trend.This study provides a reference for radiation thermometry in dynamic high-temperature environments.
基金Project supported by Jilin Provincial Department of Education(JJKH20230821KJ,JJKH20230822KJ,JJKH20230823KJ,JJKH20240930KJ,20240101107JC)。
文摘The 1.55μm laser technology is widely applied in military,information communication,biomedicine and other fields.With the deepening development of these application areas,the demand for novel 1.55μm laser gain media is becoming increasingly urgent.This study reports a novel Yb^(3+),Er^(3+)co-doped KBa_(0.94)Ca_(0.06)Y(MoO_(4))_(3) (KBCYM)crystal.In this crystal,Yb^(3+)serves as a sensitizer,significantly enhancing the emission intensity of Er^(3+)in both visible and near-infrared bands.Notably,when the concentration of Yb^(3+)reaches 6 mol%,the emission intensity peaks at 1.55μm.Optical cross-section calculations reveal that the crystal exhibits a low laser pumping threshold at this concentration,demonstrating its potential as a laser gain medium.However,the crystal inevitably generates thermal effects during operation,which may adversely affect its performance.Therefore,real-time monitoring of the operating temperature is crucial.The thermal stability of the crystal was evaluated by measuring the temperature dependence of its luminescence intensity in the near-infrared band.Remarkably,even when the temperature rises to 553 K,the emission intensity at 1.55μm only decreases by 10.9%.Additionally,the temperature sensing performance was evaluated using fluorescence intensity ratio techniques,yielding absolute and relative sensitivities of 0.00981 K^(-1)at 453 K and 1.32%/K at 303 K,respectively,highlighting its potential for optical temperature sensing.Finally,through leveraging the unique properties of Yb^(3+),Er^(3+):KBCYM crystals,we successfully developed 1.55μm luminescent optical devices with practical applications.These devices not only exhibit efficient luminescent performance,but also possess a self-temperature measu rement functio n,opening up new avenues for the further development of laser technology.
基金Projects(U23A20666,52178405)supported by the National Natural Science Foundation of ChinaProject(K2022G038)supported by the Science and Technology Research and Development Program of China State Railway Group Co.,Ltd.Project(2021B03)supported by the Science and Technology Plan of Shandong Provincial Department of Transportation,China。
文摘Arching and cracking of joints between slabs have become a problem in China Railway Track System(CRTS)II slab track.The slab track is susceptible to complex temperature variations as a longitudinal continuous structure.Based on measured data,a thermal-mechanical coupling model of the track was established.The deformation characteristics and interfacial damage behavior of joints under typical temperature fields were studied.The findings indicate that the annual extreme temperature range of the slab track,fluctuates from−1.4 to 49.8℃.The annual temperature gradient within the vertical depth range of 0 to 0.2 m of the track varies between−16.19℃/m and 30.15℃/m.The vertical deformation of joints is significantly influenced by high temperatures,with a maximum measured deformation of 0.828 mm.The joint seams are primarily affected by low temperatures,which lead to a separation of 0.9 to 1.0 mm.Conversely,interlayer damage of joints is predominantly influenced by elevated temperatures.In summer,the maximum ratio of interface damage area in the joint can reach up to 95%,with the maximum debonding area ratio can be as high as 84%.The research results can provide help for joint damage regularity and deformation control of CRTS II slab track.
基金supported by the National Natural Science Foundation of China(Nos.52425505 and U22A20207)the National Key R&D Program of China(No.2022YFB3403302)the Zhejiang Provincial Key R&D Program of China(No.2023C01056).
文摘With the widespread adoption of ultra-precision machining(UPM)in manufacturing,accurately monitoring the temperature within micro-scale cutting zones has become crucial for ensuring machining quality and tool longevity.This review comprehensively evaluates modern in-process cutting temperature measurement methods,comparing conventional approaches and emerging technologies.Thermal conduction-based and radiation-based measurement paradigms are analyzed in terms of their merits,limitations,and domain-specific applicability,particularly with regard to the unique challenges involving micro-scale cutting zones in UPM.Special emphasis is placed on micro-scale sensor-integrated tools and self-sensing tools that enable real-time thermal monitoring at cutting edges.Furthermore,we explore thermal monitoring and management techniques for atomic and close-to-atomic scale manufacturing(ACSM),as well as the transformative potential of emerging technologies like artificial intelligence(AI),internet of things(IoT),and data fusion for machining temperature measurement.This review may serve as a reference for UPM cutting temperature measurement research,helping foster the development of optimized process control technologies.
文摘A high precision, high antijamming multipoint infrared telemetry system was developed to measure the piston temperature in internal combustion engine. The temperature at the measuring point is converted into corresponding voltage signal by the thermo-couple first. Then after the V/F stage, the voltage signal is converted into the frequency signal to drive the infrared light-emitting diode to transmit infrared pulses. At the receiver end, a photosensitive audion receives the infrared pulses. After conversion, the voltage recorded by the receiver stands for the magnitude of temperature at the measuring point. Test results of the system indicate that the system is practical and the system can perform multipoint looping temperature measurements for the piston.
基金supported by the National Nature Science Foundation of China (Grants 11132011 and 11472288)
文摘The plastic work-heat conversion coefficient is one key parameter for studying the work-heat conversion under dynamic deformation of materials. To explore this coefficient of 7075-T651 aluminum alloy under dynamic compression, dynamic compression experiments using the Hopkinson bar under four groups of strain rates were conducted, and the temperature signals were measured by constructing a transient infrared temperature measurement system. According to stress versus strain data as well as the corresponding temperature data obtained through the experiments, the influences of the strain and the strain rate on the coefficient of plastic work converted to heat were analyzed.The experimental results show that the coefficient of plastic work converted to heat of 7075-T651 aluminum alloy is not a constant at the range of 0.85–1 and is closely related to the strain and the strain rate. The change of internal structure of material under high strain rate reduces its energy storage capacity, and makes almost all plastic work convert into heat.
基金Supported by the China National Science and Technology Major Project(2016ZX05004-002)Basic Research and Strategic Reserve Technology Research Fund of Institutes Directly Under CNPC(2018D-5008-03)PetroChina Science and Technology Project(2019D-5009-16)。
文摘A new method for reconstructing the geological history of hydrocarbon accumulation is developed, which are constrained by U-Pb isotope age and clumped isotope((35)47) temperature of host minerals of hydrocarbon-bearing inclusions. For constraining the time and depth of hydrocarbon accumulation by the laser in-situ U-Pb isotope age and clumped isotope temperature, there are two key steps:(1) Investigating feature, abundance and distribution patterns of liquid and gaseous hydrocarbon inclusions with optical microscopes.(2) Dating laser in-situ U-Pb isotope age and measuring clumped isotope temperature of the host minerals of hydrocarbon inclusions. These technologies have been applied for studying the stages of hydrocarbon accumulation in the Sinian Dengying gas reservoir in the paleo-uplift of the central Sichuan Basin. By dating the U-Pb isotope age and measuring the temperature of clumped isotope((35)47) of the host minerals of hydrocarbon inclusions in dolomite, three stages of hydrocarbon accumulation were identified:(1) Late Silurian: the first stage of oil accumulation at(416±23) Ma.(2) Late Permian to Early Triassic: the second stage of oil accumulation between(248±27) Ma and(246.3±1.5) Ma.(3) Yanshan to Himalayan period: gas accumulation between(115±69) Ma and(41±10) Ma. The reconstructed hydrocarbon accumulation history of the Dengying gas reservoir in the paleo-uplift of the central Sichuan Basin is highly consistent with the tectonic-burial history, basin thermal history and hydrocarbon generation history, indicating that the new method is a reliable way for reconstructing the hydrocarbon accumulation history.
基金supported by the Key Project of the National Natural Science Foundation of China (No. 50534040)the Project of the National Natural Science Foundation of China (No. 40471021)
文摘In order to study the evolution of the freezing fringe and final lenses of frost susceptible soils and advance the understanding of frost heave and mechanism of frost heave control, we used an open one-dimensional frost heave test system of infrared radiation technology, instead of a traditional thermistor method. Temperatures of the freezing fringe and segregated ice were measured in a non-contact mode. The results show that accurate and precise temperatures of ice segregation can be obtained by infrared thermal imaging systems. A self-developed inversion program inverted the temperature field of frozen soils. Based on our analysis of temperature variation in segregated ice and our study of the relationship between temperature and rate of ice segregation in cooling and warming processes during intermittent freezing, the mechanism of decreasing frost heave of frozen soils by controlling the growth of final lenses with an intermittent freezing mode, can be explained properly.
基金carried out in the framework of the Ri ST2 Project,cofinanced by Fondazione Cassa di Risparmio di Torino。
文摘In a context of cryosphere degradation caused by climate warming,rock temperature is one of the main driving factors of rockfalls that occur on high-elevation mountain slopes.In order to improve the knowledge of this critical relationship,it is necessary to increase measurement capability of rock temperature and its variability in different lithological and slope/aspect conditions,and also to increase local scale studies,increasing the quality and the comparability of the data.This paper shows an example of metrological characterization of sensors used for rock temperature measurement in mountain regions,by means of the measurement uncertainty.Under such approach,data and results from temperature measurements carried out in the Bessanese high-elevation experimental site(Western European Alps)are illustrated.The procedures for the calibration and field characterization of sensors allow to measure temperature in different locations,depths and lithotypes,within 0.10°C of overall uncertainty.This work has highlighted that metrological traceability is fundamental to asses data quality and establish comparability among different measurements;that there are strong differences between air temperature and near-surface rock temperature;and that there are significant differences of rock temperature acquired in different aspect conditions.Finally,solar radiation,slope/aspect conditions and lithotype,seem to be the main driving factors of rock temperature.
基金Sponsored by the National Natural Science Foundation of China (10772032)
文摘An infrared colorimetric radiation thermometrical system was established based on the theory of optical radiation. The dynamic temperature history of fuel air explosive (FAE) was measured to obtain the temperature responses of primary initiation FAE and secondary initiation FAE in real time. And the characteristics of their temperature history curves were compared and analyzed. The results show that the primary initiation FAE has higher explosion temperature and longer duration compared to the secondary initiation FAE.
文摘It is well known that optical tomography can accurately and quantitatively reconstruct the refractive index field of a transparent medium and display the three dimensional image of other physical quantities relevant to temperature or density. In this paper, a new multidirectional holographic interferometric system is built, and two kinds of image reconstruction algorithms are introduced and an automatic image processing system of interferogram is designed. A three dimentsional asymmetric gas flow field above a combustor is expertmentally investigated with holographic interferometry. The reconstructed temperatures are similar to those measured with a thermocouple.
文摘Exhaust gas temperature is an important factor in NOx, THC and PM emissions of engines. Especially 2D temperature and concentration distribution plays an important role for the engine efficiency. A thermocouple is intrinsically a point temperature measurement method and noncontact 2D temperature distribution cannot be attained by thermocouples. Recently, as a measurement technique with high sensitivity and high response, laser diagnostics has been developed and applied to the actual engine combustions. With these engineering developments, transient phenomena such as start-ups and load changes in engines have been gradually elucidated in various conditions. In this study, the theoretical and experimental research has been conducted in order to develop the noncontact and fast response 2D temperature and concentration distribution measurement method. The method is based on a Computed Tomography （CT） method using absorption spectra of water vapor at 1388 nm. It has been demonstrated that the method has been successfully applied to engine exhausts to measure 2D temperature distributions.
基金the National Natural Science Foundation of China(Grant Nos.11427803,11427901 and 11773040)the Strategic Pioneer Program on Space Science,Chinese Academy of Sciences(CAS)(XDA04061002 and XDA15010800)the Public Technology Service Center,National Astronomical Observatories of CAS(829011V01)。
文摘The magnetic field is one of the most important parameters in solar physics,and a polarimeter is the key device to measure the solar magnetic field.Liquid crystals based Stokes polarimeter is a novel technology,and will be applied for magnetic field measurement in the first space-based solar observatory satellite developed by China,Advanced Space-based Solar Observatory.However,the liquid crystals based Stokes polarimeter in space is not a mature technology.Therefore,it is of great scientific significance to study the control method and characteristics of the device.The retardation produced by a liquid crystal variable retarder is sensitive to the temperature,and the retardation changes 0.09°per 0.10℃.The error in polarization measurement caused by this change is 0.016,which affects the accuracy of magnetic field measurement.In order to ensure the stability of its performance,this paper proposes a high-precision temperature control system for liquid crystals based Stokes polarimeter in space.In order to optimize the structure design and temperature control system,the temperature field of liquid crystals based Stokes polarimeter is analyzed by the finite element method,and the influence of light on the temperature field of the liquid crystal variable retarder is analyzed theoretically.By analyzing the principle of highprecision temperature measurement in space,a high-precision temperature measurement circuit based on integrated operational amplifier,programmable amplifier and 12 bit A/D is designed,and a high-precision space temperature control system is developed by applying the integral separation PI temperature control algorithm and PWM driving heating films.The experimental results show that the effect of temperature control is accurate and stable,whenever the liquid crystals based Stokes polarimeter is either in the air or vacuum.The temperature stability is within±0.0150℃,which demonstrates greatly improved stability for the liquid crystals based Stokes polarimeter.
基金support from National Natural Science Foundation of China(No.51875372)the Key R&D Program of Advanced Technology of Sichuan Science and Technology Department(No.2020YFG0111)。
文摘A two-temperature(2 T)thermal non-equilibrium model is developed to address the thermal nonequilibrium phenomenon that inevitably exists in the reverse-polarity plasma torch(RPT)and applied to numerically investigate the plasma flow characteristics inside and outside the RPT.Then,a detailed comparison of the results of the 2 T model with those of the local thermal equilibrium(LTE)model is presented.Furthermore,the temperature of the plasma jet generated by a RPT and the RPT’s voltage are experimentally measured to compare and validate the result obtained by different models.The differences of the measured excitation temperature and the arc voltage between the 2 T model and experimental measurement are less than 13%and 8%,respectively,in all operating cases,validating the effectiveness of the 2 T model.The LTE model overestimates the velocity and temperature distribution of the RPT and its plasma jet,showing that thermal non-equilibrium phenomena cannot be neglected in the numerical modelling of the RPT.Unlike other common hot cathode plasma torches,the thermal non-equilibrium phenomenon is found even in the arc core of the RPT,due to the strong cooling effect caused by the big gas flow rate.
基金supported by the National Natural Science Foundation of China(10772188)
文摘A novel method based on wavelength-multiplexed line-of-sight absorption and profile fitting for nonuniform flow field measurement is reported. A wavelength scanning combing laser temperature and current modulation WMS scheme is used to implement the wavelength-multi- plexed-profile fitting method. Second harmonic （2f） signal of eight H20 transitions features near 7,170 cm^-1 are measured in one period using a single tunable diode laser. Spatial resolved temperature distribution upon a CH4/air premixed flat flame burner is obtained. The result validates the feasibility of strategy for non-uniform flow field diagnostics by means of WMS-2f TDLAS.
基金The work was supported by the Australasian Centre for Rail Innovation under its HH01B—Evaluating infrared imaging and laser ultrasonics as detectors of rail foot flaws project.
文摘There currently does not exist in industry a reliable method for the detection of rail foot flaws.Like their head-based counterparts,foot flaws result in broken rail with potentially catastrophic consequences.A proposed area of research for the detection of these flaws is thermography,a non-contact method of measuring and analysing infrared emissions from an object under test.In industry,active excitation thermography is the most common,requiring an excitation source.This paper will present a temperature measurement system and a method of transient temperature extraction from the running rails for the effects of a passing train to evaluate heat transfer in the practical rail environment.The outcomes of these results will provide future direction in the development of a rail heat transfer model and determine if train passage provides enough active excitation for a thermography-based detection technique.
文摘This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.
