Combined with ultrasonic pulse-echo technique, reflection spectrum analysis was introduced to evaluate TiAl and 40Cr diffusion bonding quality. Frequency dependence of reflection coefficient was used to distinguish pe...Combined with ultrasonic pulse-echo technique, reflection spectrum analysis was introduced to evaluate TiAl and 40Cr diffusion bonding quality. Frequency dependence of reflection coefficient was used to distinguish perfect bonding from imperfect bonding. It is found that the reflection coefficient from perfect bonding interface does not vary with frequency. When the size of imperfections is much smaller than the wavelength of ultrasound, the reflection coeffwient depends on frequency. When the size of imperfections is the same order of or even larger than the wavelength of ultrasound, the reflection coeffwient does not exhibit frequency dependence. However the amplitude of imperfect interface is higher than the amplitude of perfect bonding interface. A combination of reflection spectrum analysis and ultrasonic pulse-echo technique provides more accurate information about the bonding quality of dissimilar materials.展开更多
Two kinds of nanopowders were studied.One is NiFe 2O 4 spherical nanopowders which have different particle sizes.Another is ZnO nanopowders including two series of spherical particles and tetrapod nanowhiskers.Throu...Two kinds of nanopowders were studied.One is NiFe 2O 4 spherical nanopowders which have different particle sizes.Another is ZnO nanopowders including two series of spherical particles and tetrapod nanowhiskers.Through measuring the infrared diffuse reflection spectra of nanopowders,it can be found that the particle size and morphology affect the infrared diffuse reflection spectra.For the NiFe 2O 4 nanopowders the smaller the particle size,the larger the K-M value.And when the particle size is large enough,the effect of the particle size on infrared diffuse reflection spectra would disappear.For the ZnO nanopowders the effects of the particle size and morphology are more special.The effect of the particle sizes of tetrapod whisker nanopowders on infrared diffuse reflection spectra is more than that of spherical nanopowders.展开更多
The excitation and emission spectra, the relaxation time of principal spectral lines and multi-diffused reflection spectra in LaOCl: Er, LaOCl: Ho powder samples were measured. The diffused absorption spectrum was der...The excitation and emission spectra, the relaxation time of principal spectral lines and multi-diffused reflection spectra in LaOCl: Er, LaOCl: Ho powder samples were measured. The diffused absorption spectrum was derived from the multi-diffused reflection spectrum. According to Judd-Ofelt theory,the intensity parameters, radiative transition probabilities and quantum efficiencies of luminescence emission were calculated. Then comparison with erbium and holmium doped floride glass and other matrices were made.展开更多
The optical properties of fresh maize tissues determine how light interacts with fresh maize cobs,which in turn affects the measured spectral signals and model accuracy.In this paper,a simulation model was developed t...The optical properties of fresh maize tissues determine how light interacts with fresh maize cobs,which in turn affects the measured spectral signals and model accuracy.In this paper,a simulation model was developed to invert the optical properties of fresh maize cobs and evaluate the effects of different optical layouts on the accuracy of modeling predictions.First,the uniformity of detector irradiation at various distances(10 mm,20 mm,30 mm,40 mm,50 mm)and angles(30°,45°,60°)with different optical properties was analyzed using optical simulation methods.Then,the spectra of fresh maize cobs were collected at different light source angles and detection distances,and the spectral area polarization was calculated.Finally,the optical properties of the cob were estimated by establishing a link between irradiation uniformity and spectral area polarization,which resolved the distribution of light flux in edible maize cobs under different optical structures.The results show that the model of light transport mimicking the organizational structure of maize cob has been successfully simulated.The estimated optical properties of the cob are:absorption A=37%,transmission T=20%,and diffuse reflectance D=40%.This verifies that the accuracy and precision of the prediction model for the water content of fresh maize are best achieved under an optical structure with a detection distance of 40 mm and a light source angle of 45°.The establishment of the simulation model provides theoretical support for near-infrared detection of the intrinsic quality of fresh maize.展开更多
Fructus cnidii （Chinese name shechuangzi） is the fruit produced by Cnidium monnieri （L.） Cusson （Umbelliferae）. It is a perennial herb that is used to treat skin-related diseases and gynecopathyell. Recent pharm...Fructus cnidii （Chinese name shechuangzi） is the fruit produced by Cnidium monnieri （L.） Cusson （Umbelliferae）. It is a perennial herb that is used to treat skin-related diseases and gynecopathyell. Recent pharmacological studies have revealed crude extracts or components isolated from fructus cnidii possess antiallergic, antipruritic, antidermatophytic, antibacterial, antifungal, and antiosteoporotic activities. Osthole and imperatorin are the major compounds present in shechuangzi. They are often used as standards for the evaluation of the quality of shechuangzi products.展开更多
文摘Combined with ultrasonic pulse-echo technique, reflection spectrum analysis was introduced to evaluate TiAl and 40Cr diffusion bonding quality. Frequency dependence of reflection coefficient was used to distinguish perfect bonding from imperfect bonding. It is found that the reflection coefficient from perfect bonding interface does not vary with frequency. When the size of imperfections is much smaller than the wavelength of ultrasound, the reflection coeffwient depends on frequency. When the size of imperfections is the same order of or even larger than the wavelength of ultrasound, the reflection coeffwient does not exhibit frequency dependence. However the amplitude of imperfect interface is higher than the amplitude of perfect bonding interface. A combination of reflection spectrum analysis and ultrasonic pulse-echo technique provides more accurate information about the bonding quality of dissimilar materials.
文摘Two kinds of nanopowders were studied.One is NiFe 2O 4 spherical nanopowders which have different particle sizes.Another is ZnO nanopowders including two series of spherical particles and tetrapod nanowhiskers.Through measuring the infrared diffuse reflection spectra of nanopowders,it can be found that the particle size and morphology affect the infrared diffuse reflection spectra.For the NiFe 2O 4 nanopowders the smaller the particle size,the larger the K-M value.And when the particle size is large enough,the effect of the particle size on infrared diffuse reflection spectra would disappear.For the ZnO nanopowders the effects of the particle size and morphology are more special.The effect of the particle sizes of tetrapod whisker nanopowders on infrared diffuse reflection spectra is more than that of spherical nanopowders.
文摘The excitation and emission spectra, the relaxation time of principal spectral lines and multi-diffused reflection spectra in LaOCl: Er, LaOCl: Ho powder samples were measured. The diffused absorption spectrum was derived from the multi-diffused reflection spectrum. According to Judd-Ofelt theory,the intensity parameters, radiative transition probabilities and quantum efficiencies of luminescence emission were calculated. Then comparison with erbium and holmium doped floride glass and other matrices were made.
基金National Key Research and Development Program of China(Grant No.2023YFD2001301)the Independent Research and Development Project of Academy of Agricultural Planning and Engineering,Ministry of Agriculture and Rural Affairs(Grant No.SP202402)the Key Laboratory of Agro-Products Primary Processing,Ministry of Agriculture and Rural Affairs(Grant No.KLAPPP2024-01).
文摘The optical properties of fresh maize tissues determine how light interacts with fresh maize cobs,which in turn affects the measured spectral signals and model accuracy.In this paper,a simulation model was developed to invert the optical properties of fresh maize cobs and evaluate the effects of different optical layouts on the accuracy of modeling predictions.First,the uniformity of detector irradiation at various distances(10 mm,20 mm,30 mm,40 mm,50 mm)and angles(30°,45°,60°)with different optical properties was analyzed using optical simulation methods.Then,the spectra of fresh maize cobs were collected at different light source angles and detection distances,and the spectral area polarization was calculated.Finally,the optical properties of the cob were estimated by establishing a link between irradiation uniformity and spectral area polarization,which resolved the distribution of light flux in edible maize cobs under different optical structures.The results show that the model of light transport mimicking the organizational structure of maize cob has been successfully simulated.The estimated optical properties of the cob are:absorption A=37%,transmission T=20%,and diffuse reflectance D=40%.This verifies that the accuracy and precision of the prediction model for the water content of fresh maize are best achieved under an optical structure with a detection distance of 40 mm and a light source angle of 45°.The establishment of the simulation model provides theoretical support for near-infrared detection of the intrinsic quality of fresh maize.
基金Supported by the Talented Young Pressional Foundation of Jilin Province(No 2005123)
文摘Fructus cnidii （Chinese name shechuangzi） is the fruit produced by Cnidium monnieri （L.） Cusson （Umbelliferae）. It is a perennial herb that is used to treat skin-related diseases and gynecopathyell. Recent pharmacological studies have revealed crude extracts or components isolated from fructus cnidii possess antiallergic, antipruritic, antidermatophytic, antibacterial, antifungal, and antiosteoporotic activities. Osthole and imperatorin are the major compounds present in shechuangzi. They are often used as standards for the evaluation of the quality of shechuangzi products.
