Numerical study was performed to evaluate the characteristics of combined heat transfer of radiation, conduction and convection in indirect near infrared ray （N/R） heating chamber. The effects of important design pa...Numerical study was performed to evaluate the characteristics of combined heat transfer of radiation, conduction and convection in indirect near infrared ray （N/R） heating chamber. The effects of important design parameters such as the shape of heat absorbing cylinder and heat releasing fin on the pressure drop and heat transfer coefficient were analyzed with different Reynolds numbers. The Reynolds numbers were varied from 103 to 3x106, which was defined based on the hydraulic diameter of the heat absorbing cylinder. Analyses were performed to obtain the inner and outer flow and the temperature distributions in the heat absorbing cylinder and the rates of radiation heat transfer and convection heat transfer. As the Reynolds number increases, the convection heat transfer rate is increased while the radiation heat transfer rate is decreased. The average convection heat transfer rate follows a power rule of the Reynolds number. Addition of three-dimensional heat releasing fin to the outside of the heat absorbing cylinder enhances the convection heat transfer.展开更多
The infrared radiation temperature(IRT)variation concerning stress and crack evolution of rocks is a critical focus in rock mechanics domain and engineering disaster warning.In this paper,a methodology to extract the ...The infrared radiation temperature(IRT)variation concerning stress and crack evolution of rocks is a critical focus in rock mechanics domain and engineering disaster warning.In this paper,a methodology to extract the key IRT features related to stress and crack evolution of loaded rocks is proposed.Specifically,the wavelet denoising and reconstruction in thermal image sequence(WDRTIS)method is employed to eliminate temporal noise in thermal image sequences.Subsequently,the adaptive partition temperature drift correction(APTDC)method is introduced to alleviate temperature drift.On this basis,the spatial noise correction method based on threshold segmentation and adaptive median filtering(OTSU-AMF)is proposed to extract the key IRT features associated with microcracks of loaded rocks.Following temperature drift correction,IRT provides an estimation of the thermoelastic factor in rocks,typically around 5.29×10^(-5) MPa^(-1) for sandstones.Results reveal that the high-temperature concentrated region in cumulative thermal images of crack evolution(TICE)can elucidate the spatiotemporal evolution of localized damage.Additionally,heat dissipation of crack evolution(HDCE)acquired from TICE quantifies the progressive failure process of rocks.The proposed methodology enhances the reliability of IRT monitoring results and provides an innovative approach for conducting research in rock mechanics and monitoring engineering disasters.展开更多
Far infrared(FIR)radiation(3-100µm)is an electromagnetic spectrum commonly studied for biological effects.This article aims to discuss using Far infrared radiation with sub-division(4-24µm)of this waveband t...Far infrared(FIR)radiation(3-100µm)is an electromagnetic spectrum commonly studied for biological effects.This article aims to discuss using Far infrared radiation with sub-division(4-24µm)of this waveband to stimulate tissues and cells and is considered an effective therapeutic modality for specific medical disorders.The IR application as a medical therapy has advanced rapidly in recent years.For example,IR therapy like IR-emitting apparel and materials that can be run solely by body heat(does not need an external power supply)have been developed.New methods for providing FIR radiation to the human body have emerged due to technological advancements.Specialty saunas and lamps that emit pure FIR radiation have become effective,safe,and widely used therapeutic sources.Fibers infused with thermide,FIR emitting ceramic nanomaterials and knitted into fabrics are used as clothes and apparel to produce FIR radiation and benefit from its effects.A deeper understanding of FIR's significant innovations and biological implications could aid in improving therapeutic efficacy or developing new methods that use FIR wavelengths.展开更多
Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical co...Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical conductivity,high solar absorptivity,and low infrared emissivity at the same time are rare in na-ture,which are highly anticipated and of great significance for highly efficient electric/solar heating.In this work,we demonstrate that Ti_(3)C_(2)T_(x) MXene with low IR emissivity(14.5%)fills the gap in the absence of the above materials,exhibiting a remarkable electric/solar heating performance.The saturated heating temperature of Ti_(3)C_(2)T_(x) film reaches a record-high value of 201°C at a low driving voltage of 1.5 V,and reaches 84.3°C under practical solar irradiation(750 W/m^(2))with a high solar to the thermal conversion efficiency of 75.3%,which is far superior to other reported materials.Meanwhile,the low IR emissivity endows Ti_(3)C_(2)T_(x) with a remarkable passive radiative heating capability of 7.0°C,ensuring zero-energy heating without electric/solar energy supply.The intrinsic characteristic of high electrical conductivity,high solar absorptivity,and low IR emissivity makes Ti_(3)C_(2)T_(x) unique existence in nature,which is highly promising for all-day and all-weather energy-saving heating.展开更多
随着大面阵、长线列、双/多色、数字化红外探测器技术的不断发展,杜瓦的尺寸和结构复杂程度逐步增加。计算辐射漏热时,传统的方法一般将杜瓦简化为同轴圆筒模型,导致计算误差较大。为提高杜瓦辐射漏热的计算精度,对主要的角系数计算方...随着大面阵、长线列、双/多色、数字化红外探测器技术的不断发展,杜瓦的尺寸和结构复杂程度逐步增加。计算辐射漏热时,传统的方法一般将杜瓦简化为同轴圆筒模型,导致计算误差较大。为提高杜瓦辐射漏热的计算精度,对主要的角系数计算方法进行分析,基于蒙特卡洛原理,采用3D Studio Max(3ds Max)建模,提取模型信息编写程序,得到了一种适用性较强的杜瓦结构通用角系数计算程序。为了检验计算程序的正确性,计算了三种典型模型的角系数和相对误差,计算结果表明随着能束数量的增加,相对误差可控制在1%~-1%之间。最后,计算了某型杜瓦的角系数并给出了其中的12个,对于紧凑结构的杜瓦,蒙特卡洛法是一种高效的计算方法,当能束数量达到万条的量级就可以得到有统计意义的结果。展开更多
The temperature distributions on the helicopter airframe and in the exhaust plume are affected seriously by the engine exhaust system, rotor downwash and solar irradiance. To precisely simulate temperature distributio...The temperature distributions on the helicopter airframe and in the exhaust plume are affected seriously by the engine exhaust system, rotor downwash and solar irradiance. To precisely simulate temperature distribution on the helicopter airframe and in the exhaust plume, the effects of rotor downwash and solar irradiance are considered in three-dimensional flow and heat transfer calculation under helicopter hovering. Based on the temperature distribution, a forward-backward ray tracing method is used to calculate the helicopter infrared （IR） radiation intensity. A numerical study is conducted on a fictitious helicopter model with an integrated exhaust system-tail airframe configuration, and the thermal and infrared radiation characteristics are analyzed.展开更多
A parameterized radiation and cloud model developed at the University of Utah,U.S.A.has been used to compute the atmospheric radiative properties in Zhangye area during the pilot experiment of HEIFE in September of 19...A parameterized radiation and cloud model developed at the University of Utah,U.S.A.has been used to compute the atmospheric radiative properties in Zhangye area during the pilot experiment of HEIFE in September of 1988.Some characteristics of atmospheric radiative heating fields during the autumn in Zhangye area have been analysed,and some questions that merit attention in the future observation are also discussed in this paper.展开更多
基金supported by the Second Stage of Brain Korea 21 Projects
文摘Numerical study was performed to evaluate the characteristics of combined heat transfer of radiation, conduction and convection in indirect near infrared ray （N/R） heating chamber. The effects of important design parameters such as the shape of heat absorbing cylinder and heat releasing fin on the pressure drop and heat transfer coefficient were analyzed with different Reynolds numbers. The Reynolds numbers were varied from 103 to 3x106, which was defined based on the hydraulic diameter of the heat absorbing cylinder. Analyses were performed to obtain the inner and outer flow and the temperature distributions in the heat absorbing cylinder and the rates of radiation heat transfer and convection heat transfer. As the Reynolds number increases, the convection heat transfer rate is increased while the radiation heat transfer rate is decreased. The average convection heat transfer rate follows a power rule of the Reynolds number. Addition of three-dimensional heat releasing fin to the outside of the heat absorbing cylinder enhances the convection heat transfer.
基金supported by the National Natural Science Foundation of China(No.51874280)the Fundamental Research Funds for the Central Universities(No.2021ZDPY0211)+2 种基金the Graduate Innovation Program of China University of Mining and Technology(No.2023WLKXJ046)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX23_2811)the Project of Liaoning Provincial Department of Education(No.JYTMS20231458).
文摘The infrared radiation temperature(IRT)variation concerning stress and crack evolution of rocks is a critical focus in rock mechanics domain and engineering disaster warning.In this paper,a methodology to extract the key IRT features related to stress and crack evolution of loaded rocks is proposed.Specifically,the wavelet denoising and reconstruction in thermal image sequence(WDRTIS)method is employed to eliminate temporal noise in thermal image sequences.Subsequently,the adaptive partition temperature drift correction(APTDC)method is introduced to alleviate temperature drift.On this basis,the spatial noise correction method based on threshold segmentation and adaptive median filtering(OTSU-AMF)is proposed to extract the key IRT features associated with microcracks of loaded rocks.Following temperature drift correction,IRT provides an estimation of the thermoelastic factor in rocks,typically around 5.29×10^(-5) MPa^(-1) for sandstones.Results reveal that the high-temperature concentrated region in cumulative thermal images of crack evolution(TICE)can elucidate the spatiotemporal evolution of localized damage.Additionally,heat dissipation of crack evolution(HDCE)acquired from TICE quantifies the progressive failure process of rocks.The proposed methodology enhances the reliability of IRT monitoring results and provides an innovative approach for conducting research in rock mechanics and monitoring engineering disasters.
文摘Far infrared(FIR)radiation(3-100µm)is an electromagnetic spectrum commonly studied for biological effects.This article aims to discuss using Far infrared radiation with sub-division(4-24µm)of this waveband to stimulate tissues and cells and is considered an effective therapeutic modality for specific medical disorders.The IR application as a medical therapy has advanced rapidly in recent years.For example,IR therapy like IR-emitting apparel and materials that can be run solely by body heat(does not need an external power supply)have been developed.New methods for providing FIR radiation to the human body have emerged due to technological advancements.Specialty saunas and lamps that emit pure FIR radiation have become effective,safe,and widely used therapeutic sources.Fibers infused with thermide,FIR emitting ceramic nanomaterials and knitted into fabrics are used as clothes and apparel to produce FIR radiation and benefit from its effects.A deeper understanding of FIR's significant innovations and biological implications could aid in improving therapeutic efficacy or developing new methods that use FIR wavelengths.
基金support of the National Natural Science Foundation of China(Nos.52003248 and 82004001)the China Postdoctoral Science Foundation(Nos.2018M642780 and 2021T140613)+1 种基金the Open-ing Project of State Key Laboratory of Polymer Materials Engineer-ing(Sichuan University)(No.sklpme2019-4-31)the Key Research and Development and Promotion projects of Henan Province(No.202102210032)are gratefully acknowledged.
文摘Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical conductivity,high solar absorptivity,and low infrared emissivity at the same time are rare in na-ture,which are highly anticipated and of great significance for highly efficient electric/solar heating.In this work,we demonstrate that Ti_(3)C_(2)T_(x) MXene with low IR emissivity(14.5%)fills the gap in the absence of the above materials,exhibiting a remarkable electric/solar heating performance.The saturated heating temperature of Ti_(3)C_(2)T_(x) film reaches a record-high value of 201°C at a low driving voltage of 1.5 V,and reaches 84.3°C under practical solar irradiation(750 W/m^(2))with a high solar to the thermal conversion efficiency of 75.3%,which is far superior to other reported materials.Meanwhile,the low IR emissivity endows Ti_(3)C_(2)T_(x) with a remarkable passive radiative heating capability of 7.0°C,ensuring zero-energy heating without electric/solar energy supply.The intrinsic characteristic of high electrical conductivity,high solar absorptivity,and low IR emissivity makes Ti_(3)C_(2)T_(x) unique existence in nature,which is highly promising for all-day and all-weather energy-saving heating.
文摘随着大面阵、长线列、双/多色、数字化红外探测器技术的不断发展,杜瓦的尺寸和结构复杂程度逐步增加。计算辐射漏热时,传统的方法一般将杜瓦简化为同轴圆筒模型,导致计算误差较大。为提高杜瓦辐射漏热的计算精度,对主要的角系数计算方法进行分析,基于蒙特卡洛原理,采用3D Studio Max(3ds Max)建模,提取模型信息编写程序,得到了一种适用性较强的杜瓦结构通用角系数计算程序。为了检验计算程序的正确性,计算了三种典型模型的角系数和相对误差,计算结果表明随着能束数量的增加,相对误差可控制在1%~-1%之间。最后,计算了某型杜瓦的角系数并给出了其中的12个,对于紧凑结构的杜瓦,蒙特卡洛法是一种高效的计算方法,当能束数量达到万条的量级就可以得到有统计意义的结果。
文摘The temperature distributions on the helicopter airframe and in the exhaust plume are affected seriously by the engine exhaust system, rotor downwash and solar irradiance. To precisely simulate temperature distribution on the helicopter airframe and in the exhaust plume, the effects of rotor downwash and solar irradiance are considered in three-dimensional flow and heat transfer calculation under helicopter hovering. Based on the temperature distribution, a forward-backward ray tracing method is used to calculate the helicopter infrared （IR） radiation intensity. A numerical study is conducted on a fictitious helicopter model with an integrated exhaust system-tail airframe configuration, and the thermal and infrared radiation characteristics are analyzed.
文摘A parameterized radiation and cloud model developed at the University of Utah,U.S.A.has been used to compute the atmospheric radiative properties in Zhangye area during the pilot experiment of HEIFE in September of 1988.Some characteristics of atmospheric radiative heating fields during the autumn in Zhangye area have been analysed,and some questions that merit attention in the future observation are also discussed in this paper.
