In order to save manpower and time costs,and to achieve simultaneous detection of multiple animal-derived components in meat and meat products,this study used multiple nucleotide polymorphism(MNP)marker technology bas...In order to save manpower and time costs,and to achieve simultaneous detection of multiple animal-derived components in meat and meat products,this study used multiple nucleotide polymorphism(MNP)marker technology based on the principle of high-throughput sequencing,and established a multi-locus 10 animalderived components identification method of cattle,goat,sheep,donkey,horse,chicken,duck,goose,pigeon,quail in meat and meat products.The specific loci of each species could be detected and the species could be accurately identified,including 5 loci for cattle and duck,3 loci for sheep,9 loci for chicken and horse,10 loci for goose and pigeon,6 loci for quail and 1 locus for donkey and goat,and an adulteration model was established to simulate commercially available samples.The results showed that the method established in this study had high throughput,good repeatability and accuracy,and was able to identify 10 animalderived components simultaneously with 100%repeatability accuracy.The detection limit was 0.1%(m/m)in simulated samples of chicken,duck and horse.Using the method established in this study to test commercially available samples,4 samples from 14 commercially available samples were detected to be inconsistent with the labels,of which 2 did not contain the target ingredient and 2 were adulterated with small amounts of other ingredients.展开更多
Since the room-temperature detector CdZnTe(CZT) has advantages in terms of detection efficiency,energy resolution, and size, it has been extensively used to detect X-rays and gamma-rays. So far, nuclear radiation dete...Since the room-temperature detector CdZnTe(CZT) has advantages in terms of detection efficiency,energy resolution, and size, it has been extensively used to detect X-rays and gamma-rays. So far, nuclear radiation detectors such as cerium chloride doped with lanthanum bromide(LaBr_3(Ce)), thallium doped with cesium iodide(sI(Tl)), thallium doped with sodium iodide(NaI(Tl)),and high-purity germanium(HPGe) primarily use the spectroscopy-dose rate function(G(E)) to achieve the accurate measurement of air kerma rate(K_a) and ambient dose equivalent rate(H*(10)). However, the spectroscopy-dose rate function has been rarely measured for a CZT detector. In this study, we performed spectrum measurement using a hemispherical CZT detector in a radiation protection standards laboratory. The spectroscopy-dose rate function G(E) of the CZT detector was calculated using the least-squares method combined with the standard dose rate at the measurement position. The results showed that the hemispherical CZT detector could complete the measurement of air kerma rate(K_a) and ambient dose equivalent rate(H*(10)) by using the G(E) function at energies between 48 keV and 1.25 MeV, and the relative intrinsic errors were, respectively, controlled within ± 2. 3 and ± 2. 1%.展开更多
The relationship between the secondary carbide precipitation and transformation of the 3Cr15Mo1V1.5 white iron and abrasion resistance was investigated by using optical microscope （OM）, transmission electron microsc...The relationship between the secondary carbide precipitation and transformation of the 3Cr15Mo1V1.5 white iron and abrasion resistance was investigated by using optical microscope （OM）, transmission electron microscopy （TEM） and X-ray diffrac- tion （XRD）. The results show that the properties of secondary carbides precipitated at holding stage play an important role in the abrasion resistance. After certain holding time at 833 K subcritical treatment, the grainy （Fe, Cr）23C6 carbide precipitated and the fresh martensite transformed at the holding stage for 3Cr15Mo1V1.5 white iron improve the bulk hardness and abrasion resistance of the alloy. Prolonging holding time, MoC and （Cr, V）2C precipitations cause the secondary hardening peak and the corresponding better abrasion resistance. Finally, granular （Fe, Cr）23C6 carbide in situ transforms into laminar M3C carbide and the matrix structure transforms into pearlitic matrix. These changes weaken hardness and abrasion resistance of the alloy sharply.展开更多
A 20 degree of the freedom model of the micro-suspended monorail is established to analyze a new type of the vehicle system named micro-suspended monorail.The formula of the tire is established by using the magic form...A 20 degree of the freedom model of the micro-suspended monorail is established to analyze a new type of the vehicle system named micro-suspended monorail.The formula of the tire is established by using the magic formula.Through the modal analysis of the vehicle,the modes of the vehicle are obtained,and resonance has little effect on the vehicle.When the vehicle moves in a right turn curve,it yaws in the clockwise direction.Under the action of the guidewheel(stable wheel)force,the front bogie yaws clockwise but the rear one yaws counterclockwise.Moreover,the two bogies and the car body roll during the curve passing process of the vehicle.When the vehicle speed is high enough,the left drive wheel will derail and the anti-overturning moments are provided by the stable wheels.Then,the car body yaws in the counterclockwise direction when it moves out of the curve.In the simulation of the vehicle passing the curve,the clearance between the guide wheel and rail surface will lead to a fatal impact on the bogie.At the same time,the dynamic response of the vehicle under the crosswind is tested.The vehicle will not overturn due to the crosswind.Finally,the collision of adjacent vehicles is analyzed.The results show that there is an intermittent collision force between two vehicles due to the vehicle's non synchronous pitch motion.展开更多
This study analyzed the spatio-temporal variability of air quality data for six standard air pollutants(Particulate Matter 2.5(PM2.5),Particulate Matter 10(PM10),SO2,NO2,CO,and O3)in the Sichuan Basin(SCB),China from ...This study analyzed the spatio-temporal variability of air quality data for six standard air pollutants(Particulate Matter 2.5(PM2.5),Particulate Matter 10(PM10),SO2,NO2,CO,and O3)in the Sichuan Basin(SCB),China from 2015 to 2018 in relation to the formation of haze using conventional meteorological data(temperature,wind speed,and relative humidity),satellite data(fire point data,vertical profiles of aerosol subtypes,and aerosol optical depth),planetary boundary layer height,and backward trajectories.The results indicated that the spatio-temporal evolution of the air quality index(AQI)had notable seasonality for the pollution severity in descending order:winter,spring,summer,and autumn.Autumn and winter severe haze events occurred in November and January,respectively,and were caused by higher local pollution emissions under stagnant air conditions.Spring severe haze events occurred in May and were caused by dust from Northwest China and local regions.Severe summer haze events occurred in July and were caused by local burning.Therefore,the analyses showed that local burning,stagnant meteorological conditions,air mass transport and anthropogenic pollution emissions played a key role in haze in the SCB.This study provides scientific insights for fully analyzing heavy air pollution in SCB,China,and also provides a scientific basis for pollution research in regions of complex terrain as basins and mountains.展开更多
Effect of cryogenic treatment on the microstructure, hardening behavior and abrasion resistance of 14Cr2Mn2V high chromium cast iron （HCCI） subjected to subcritical treatment was investigated. The results show that ...Effect of cryogenic treatment on the microstructure, hardening behavior and abrasion resistance of 14Cr2Mn2V high chromium cast iron （HCCI） subjected to subcritical treatment was investigated. The results show that cryogenic treatment after subcritical treatment can obviously improve the hardness and abrasion resistance of HCCI because abundant retained austenite is transformed into martensite and fine secondary carbides E（Fe, Cr）23 C6 ] precipitate. The amount of martensite and precipitated secondary carbide in HCCI experiencing subcritical treatment followed by cryogenic treatment was more than that experiencing the subcritical treatment followed by air cooling. When the abrasion resistance of HCCI reaches the maximum, its microstructure contains about 15 % retained austenite. Cryogenic treatment can further reduce the austenite content but the retained austenite cannot be transformed in to martensite completely.展开更多
Photocatalysis is considered a promising technique for removal of pollutants from indoor air.However,the low selectivity and limited recyclability of photocatalysts in powder form currently limit their practical appli...Photocatalysis is considered a promising technique for removal of pollutants from indoor air.However,the low selectivity and limited recyclability of photocatalysts in powder form currently limit their practical application.In this work,we reported the successful preparation of a monolithic tungsten oxide(WO3)/graphene oxide(GO)aerogel photocatalyst through a cost‐effective freeze‐drying method.GO not only acts as a macroscopic support,but also increases the catalyst surface area from 46 to 57 m2/g,enhances the light absorption in the visible‐light region,and raises the separation efficiency of photogenerated electron‐hole pairs.The Obtained WO3/GO aerogel exhibited an outstanding visible‐light photocatalytic degradation rate of nitric oxide of 51%,which was 3.3 times that of pristine WO3 powder.In addition,the aerogel displayed excellent selectivity,with a generation fraction of toxic nitrogen dioxide of as low as 0.5%.This work presents a facile synthesis route to fabricate a monolithic WO3/GO aerogel photocatalyst with great promise for air purification.展开更多
Aiming at the safety problems of botanical pesticides currently ignored, the paper analyzes the unsafe factors existing in botanical pesticides from the three aspects of active ingredients, inactive ingredients and un...Aiming at the safety problems of botanical pesticides currently ignored, the paper analyzes the unsafe factors existing in botanical pesticides from the three aspects of active ingredients, inactive ingredients and unregistered active ingredients, in order to provide a scientific reference for the safe use and effective su- pervision of botanical pesticides.展开更多
Si-PIN photodetectors having features such as low cost,small size,low weight,low voltage,and low power consumption are widely used as radiation detectors in electronic personal dosimeters(EPDs).The technical parameter...Si-PIN photodetectors having features such as low cost,small size,low weight,low voltage,and low power consumption are widely used as radiation detectors in electronic personal dosimeters(EPDs).The technical parameters of EPDs based on the Si-PIN photodetectors include photon energy response(PER),angular response,inherent error,and dose rate linearity.Among them,PER is a key parameter for evaluation of EPD measurement accuracy.At present,owing to the limitations of volume,power consumption,and EPD cost,the PER is usually corrected by a combination of single-channel counting techniques and filtering material methods.However,the above-mentioned methods have problems such as poor PER and low measurement accuracy.To solve such problems,in this study,a 1024-channel spectrometry system using a Si-PIN photodetector was developed and fullspectrum measurement in the reference radiation fields was conducted for radiation protection.The measurement results using the few-channel spectroscopy dose method showed that the PER could be controlled within±14%and±2%under the conditions of two and three energy intervals,respectively,with different channel numbers.The PER measured at 0°angle of radiation incidence meets the-29%to+67%requirements of IEC 61526:2010.Meanwhile,the channel number and counts-to-dose conversion factors formed in the experiment can be integrated into an EPD.展开更多
For scanning transmission proton microscopy tomography,to compare cell images of the proton stopping power and relative electron density,two cell phantoms are designed and simulated by code FLUKA.The cell images are r...For scanning transmission proton microscopy tomography,to compare cell images of the proton stopping power and relative electron density,two cell phantoms are designed and simulated by code FLUKA.The cell images are reconstructed by the filtered back projection algorithm,and compared with their tomography imaging.The images of stopping power and relative electron density slightly vary with proton energies,but the internal images are of clear with high resolution.The organic glass image of relative electron density reveals the resolution power of proton tomography.Also,the simulation results reflect effects of the boundary enhancement,the weak artifacts,and the internal structure border extension by multiple scattering.So using proton tomography to analyze internal structure of a cell is a superior.展开更多
The wettability of leaf surface,commonly represented by contact angle(CA),affects various physiological and physical processes.The present study aims to better understand the wettability of tea leaves and elucidate it...The wettability of leaf surface,commonly represented by contact angle(CA),affects various physiological and physical processes.The present study aims to better understand the wettability of tea leaves and elucidate its influence on the energy barrier of the droplet condensation process.The CA values of different leaf ages(young,mature and old)of five famous tea cultivars(Maolu,longjing 43,Huangjinya,Zhongcha 108 and Anji Baicha)were measured via the sessile drop method,and the micro-morphology of two cultivars leaves(Maolu,Zhongcha 108)was investigated by a 3D super depth-of-field digital microscope.Specifically,two radically distinctive types of CA trends were observed,one was the decreased firstly and then increased slightly with the increase of leaf age,while the other stayed constant.The valley depth or maximum height(RZ)of Maolu leaf surface increased with the leaf age while the RZ of Zhongcha 108 leaf remained unchanged by comparing the microscopic features.The Maolu mature leaf CA decline attributed to the young leaf was hydrophilic(θ<90°),and it was considered that surface structures like folds and pits on old leaf played a crucial role in making CA increased.Small deviation in CA can lead to significant error in calculation of the contact angle function of energy barrier in phase change.It will have great significant for simulating and better understanding the formation of frost on tea leaves.展开更多
Fuel cell electric vehicles hold great promise for a diverse range of applications in reducing greenhouse gas emissions.In power fuel cell systems,hydrogen fuel serves as an energy vector.To ensure its suitability,it ...Fuel cell electric vehicles hold great promise for a diverse range of applications in reducing greenhouse gas emissions.In power fuel cell systems,hydrogen fuel serves as an energy vector.To ensure its suitability,it is necessary for the quality of hydrogen to adhere to the standards set by ISO 14687:2019,which sets maximum limits for 14 impurities in hydrogen,aiming to prevent any degradation of fuel cell performance.Ammonia(NH_(3))is a prominent pollutant in fuel cells,and accurate measurements of its concentration are crucial for hydrogen fuel cell quantity.In this study,a novel detection platform was developed for determining NH_(3)in real hydrogen samples.The online analysis platform integrates a self-developed online dilution module with a Fourier transform infrared spectrometer(ODM-FTIR).The ODM-FTIR can be operated fully automatically with remote operation.Under the optimum conditions,this method achieved a wide linear range between(50∼1000)nmol/mol.The limit of detection(LOD)was as low as 2 nmol/mol with a relative standard deviation(RSD,n=7)of 3.6%at a content of 50 nmol/mol.To ensure that the quality of the hydrogen products meets the requirement of proton exchange membrane fuel cell vehicles(PEMFCV),the developed ODM-FTIR system was applied to monitor the NH_(3)content in Chengdu Hydrogen Energy Co.,Ltd.for 21 days during Chengdu 2021 FISU World University Games.The proposed method retains several unique advantages,including a low detection limit,excellent repeatability,high accuracy,high speed,good stability,and calibration flexibility.It is an effective analytical method for accurately quantifying NH_(3)in hydrogen,especially suitable for online analysis.It also provides a new idea for the analysis of other impurity components in hydrogen.展开更多
Agricultural investment project selection is a complex multi-criteria decision-making problem,as agricultural projects are easily influenced by various risk factors,and the evaluation information provided by decisionm...Agricultural investment project selection is a complex multi-criteria decision-making problem,as agricultural projects are easily influenced by various risk factors,and the evaluation information provided by decisionmakers usually involves uncertainty and inconsistency.Existing literature primarily employed direct preference elicitation methods to address such issues,necessitating a great cognitive effort on the part of decision-makers during evaluation,specifically,determining the weights of criteria.In this study,we propose an indirect preference elicitation method,known as a preference disaggregation method,to learn decision-maker preference models fromdecision examples.To enhance evaluation ease,decision-makers merely need to compare pairs of alternatives with which they are familiar,also known as reference alternatives.Probabilistic linguistic preference relations are employed to account for the presence of incomplete and uncertain information in such pairwise comparisons.To address the inconsistency among a group of decision-makers,we develop a pair of 0-1mixed integer programming models that consider both the semantics of linguistic terms and the belief degrees of decision-makers.Finally,we conduct a case study and comparative analysis.Results reveal the effectiveness of the proposed model in solving agricultural investment project selection problems with uncertain and inconsistent decision information.展开更多
A new detection system consisted of a flame ionization detector（FID） and a sulfur chemiluminescence detector（SCD） was developed for sensitive and interference free determination of total sulfur in natural gas by n...A new detection system consisted of a flame ionization detector（FID） and a sulfur chemiluminescence detector（SCD） was developed for sensitive and interference free determination of total sulfur in natural gas by non-separation gas chromatography. In this system, sulfur containing compounds and hydrocarbons were firstly burned in the FID using oxygen rich flame and converted to SO_2, CO_2 and H_2O, respectively. The products from FID were transported into the SCD with hydrogen rich atmosphere wherein only SO_2 could be reduced to SO and reacted with O_3 to produce characteristic chemiluminescence. Therefore, the chemiluminescence of CO found in conventional SCD were eliminated because CO_2 could not be reduced to CO under these conditions. The experimental parameters were systematically investigated. Limit of detection obtained by the proposed system is better than 0.5 mmol/mol for total sulfur and superior to those previously reported. The proposed method not only retains the advantages of the conventional SCD but also provides several unique advantages including no hydrocarbon interference, better stability, and easier calculation. The utility of this technique was demonstrated by the determination of total sulfur in real samples and two certified reference materials（GBW 06332 and GBW（E） 061320）.展开更多
An electronic personal dosimeter mainly uses a Si-PIN photodiode as X-and gamma-ray detectors.The photon energy response of this instrument is inconsistent in the case of no correction,which seriously affects the accu...An electronic personal dosimeter mainly uses a Si-PIN photodiode as X-and gamma-ray detectors.The photon energy response of this instrument is inconsistent in the case of no correction,which seriously affects the accurate monitoring of personal dose equivalent H_p(10)parameters for radiation workers.For this reason,in this paper we propose a method of combining composite screen detection technology,multichannel measurement technology,and the channel ratio method to achieve accurate measurement of the personal dose equivalent parameters.According to China National Standard GB/T 13161-2003 and National Verification Regulation JJG 1009-2006,the instrument was tested in the energy range between 48 keV and 1.25 MeV.The experimental results showed that the difference of energy response to ^(137)C_S corrected by the new method was almost constant within ±6.0%,which fulfilled the ±30% requirement of GB/T 13161-2003 and JJG1009-2006.Meanwhile,the method proposed obtained energy information regarding the radiation field.展开更多
Hydrogen fuel cells are among the promising energy sources worldwide,which could accomplish cyclic production of energy and avoid the emission of green-house or contaminative byproducts.However,sulfur compounds(SCs)ev...Hydrogen fuel cells are among the promising energy sources worldwide,which could accomplish cyclic production of energy and avoid the emission of green-house or contaminative byproducts.However,sulfur compounds(SCs)even at trace level(nmol/mol)are usually involved in cell construction and further H_(2)production,which would cause degradation of the catalysts and shorten the lifetime of the fuel cells.Moreover,the highly reactive SCs could cause varied species and concentrations of them in complex matrices,so online rather than offline analysis of SCs in H_(2)would be preferred.In this context,we developed a new system combining online cryogenic preconcentration of nine SCs and subsequent determination by GC-SCD(sulfur chemiluminescent detector),with the correlation coefficients of the calibration curves higher than 0.999,calculated limits of detection no higher than 0.050 nmol/mol,analytical time around 30 min per sample,and satisfactory precision and accuracy(RSD<5%and SD<15%).The analytical performance was much better than or at least comparable to the previously reported and the developed system was successfully applied for real sample analysis.展开更多
The sensitivity of ethanol sensor is of paramount importance in a variety of areas,including chemical production with ethanol,alcohol testing for driving safety,etc.Herein,α-Fe_(2)O_(3) nano-cylinders with atomic car...The sensitivity of ethanol sensor is of paramount importance in a variety of areas,including chemical production with ethanol,alcohol testing for driving safety,etc.Herein,α-Fe_(2)O_(3) nano-cylinders with atomic carbon layers are synthesized,for the first time,through in-situ catalytic chemical vapor deposition combined with hydrothermal techniques for the detection of ethanol.The reported α-Fe_(2)O_(3)@C nano-cylinders with double surficial strain effects deliver an ethanol detection sensitivity of 8 times as compared with α-Fe_(2)O_(3) nano-cylinders,10 times higher as compared with its detection sensitivity to ammonia,para-xylene,methanol and benzene.The sensor also exhibits over-14-day operation stability and the minimum detection limit of 10 ppm.To our best knowledge,the performances surpass those of previously reported α-Fe_(2)O_(3).Such attractive performances are attributed to the enhanced charge transfer in α-Fe_(2)O_(3) owing to the double surficial strain effects of α-Fe_(2)O_(3)@C nano-cylinders and the efficient adsorption of ethanol with atomic carbon layers.展开更多
Deflectometry is a non-contact and rapid detection method with high sensitivity,which can be utilized in the areas of three-dimensional(3D)reconstruction,surface quality detection,and defect location.It has important ...Deflectometry is a non-contact and rapid detection method with high sensitivity,which can be utilized in the areas of three-dimensional(3D)reconstruction,surface quality detection,and defect location.It has important applications in the automotive industry,optical parts manufacturing,and other fields.Classical deflectometry methods require the integration of slope data to reconstruct the absolute surface shape.However,the integration procedure is error-prone due to the accumulation of random errors into large shape deviations,resulting in inaccurate measurement results.In this paper,we extract the position of the centerline of the bright fringe from the stripe image and find the center of the fringe line point by point.Using the principle of triangulation,the 3D data for the object’s shaped surface can be obtained.In addition,infrared light enhances specular reflection,resulting in better deflectometry performance than that of visible light.Experiments show that the proposed method is sensitive to the changes in height and can roughly restore the surface topography of the object without calibration.展开更多
A fiber-optic Fabry-Perot hydrogen sensor was developed by measuring the fringe contrast changes at different hydrogen concentrations. The experimental results indicated that the sensing performance with the Pd-Y film...A fiber-optic Fabry-Perot hydrogen sensor was developed by measuring the fringe contrast changes at different hydrogen concentrations. The experimental results indicated that the sensing performance with the Pd-Y film was better than that with the Pd film. A fringe contrast with a decrease of 0.5 dB was detected with a hydrogen concentration change from 0% to 5.5%. The temperature response of the sensor was also measured.展开更多
基金financially supported by National Key R&D Program(2021YFF0701905)。
文摘In order to save manpower and time costs,and to achieve simultaneous detection of multiple animal-derived components in meat and meat products,this study used multiple nucleotide polymorphism(MNP)marker technology based on the principle of high-throughput sequencing,and established a multi-locus 10 animalderived components identification method of cattle,goat,sheep,donkey,horse,chicken,duck,goose,pigeon,quail in meat and meat products.The specific loci of each species could be detected and the species could be accurately identified,including 5 loci for cattle and duck,3 loci for sheep,9 loci for chicken and horse,10 loci for goose and pigeon,6 loci for quail and 1 locus for donkey and goat,and an adulteration model was established to simulate commercially available samples.The results showed that the method established in this study had high throughput,good repeatability and accuracy,and was able to identify 10 animalderived components simultaneously with 100%repeatability accuracy.The detection limit was 0.1%(m/m)in simulated samples of chicken,duck and horse.Using the method established in this study to test commercially available samples,4 samples from 14 commercially available samples were detected to be inconsistent with the labels,of which 2 did not contain the target ingredient and 2 were adulterated with small amounts of other ingredients.
基金supported by the National Key Scientific Instruments to Develop Dedicated(Nos.2013YQ090811 and 2016YFF0103800)
文摘Since the room-temperature detector CdZnTe(CZT) has advantages in terms of detection efficiency,energy resolution, and size, it has been extensively used to detect X-rays and gamma-rays. So far, nuclear radiation detectors such as cerium chloride doped with lanthanum bromide(LaBr_3(Ce)), thallium doped with cesium iodide(sI(Tl)), thallium doped with sodium iodide(NaI(Tl)),and high-purity germanium(HPGe) primarily use the spectroscopy-dose rate function(G(E)) to achieve the accurate measurement of air kerma rate(K_a) and ambient dose equivalent rate(H*(10)). However, the spectroscopy-dose rate function has been rarely measured for a CZT detector. In this study, we performed spectrum measurement using a hemispherical CZT detector in a radiation protection standards laboratory. The spectroscopy-dose rate function G(E) of the CZT detector was calculated using the least-squares method combined with the standard dose rate at the measurement position. The results showed that the hemispherical CZT detector could complete the measurement of air kerma rate(K_a) and ambient dose equivalent rate(H*(10)) by using the G(E) function at energies between 48 keV and 1.25 MeV, and the relative intrinsic errors were, respectively, controlled within ± 2. 3 and ± 2. 1%.
文摘The relationship between the secondary carbide precipitation and transformation of the 3Cr15Mo1V1.5 white iron and abrasion resistance was investigated by using optical microscope （OM）, transmission electron microscopy （TEM） and X-ray diffrac- tion （XRD）. The results show that the properties of secondary carbides precipitated at holding stage play an important role in the abrasion resistance. After certain holding time at 833 K subcritical treatment, the grainy （Fe, Cr）23C6 carbide precipitated and the fresh martensite transformed at the holding stage for 3Cr15Mo1V1.5 white iron improve the bulk hardness and abrasion resistance of the alloy. Prolonging holding time, MoC and （Cr, V）2C precipitations cause the secondary hardening peak and the corresponding better abrasion resistance. Finally, granular （Fe, Cr）23C6 carbide in situ transforms into laminar M3C carbide and the matrix structure transforms into pearlitic matrix. These changes weaken hardness and abrasion resistance of the alloy sharply.
基金The National Key Research and Development Program of China(No.2018YFB1201702)the Program of State Key Laboratory of Traction Power(No.2018TPL_T11)the Fundamental Research Funds for the Central Universities(No.2682017CX009).
文摘A 20 degree of the freedom model of the micro-suspended monorail is established to analyze a new type of the vehicle system named micro-suspended monorail.The formula of the tire is established by using the magic formula.Through the modal analysis of the vehicle,the modes of the vehicle are obtained,and resonance has little effect on the vehicle.When the vehicle moves in a right turn curve,it yaws in the clockwise direction.Under the action of the guidewheel(stable wheel)force,the front bogie yaws clockwise but the rear one yaws counterclockwise.Moreover,the two bogies and the car body roll during the curve passing process of the vehicle.When the vehicle speed is high enough,the left drive wheel will derail and the anti-overturning moments are provided by the stable wheels.Then,the car body yaws in the counterclockwise direction when it moves out of the curve.In the simulation of the vehicle passing the curve,the clearance between the guide wheel and rail surface will lead to a fatal impact on the bogie.At the same time,the dynamic response of the vehicle under the crosswind is tested.The vehicle will not overturn due to the crosswind.Finally,the collision of adjacent vehicles is analyzed.The results show that there is an intermittent collision force between two vehicles due to the vehicle's non synchronous pitch motion.
基金Under the auspices of National Key R&D Program of China(No.2017YFC0601505)National Natural Science Foundation of China(No.41672325,41602334)Opening Fund of Geomathematics Key Laboratory of Sichuan Province(scsxdz2019zd01)。
文摘This study analyzed the spatio-temporal variability of air quality data for six standard air pollutants(Particulate Matter 2.5(PM2.5),Particulate Matter 10(PM10),SO2,NO2,CO,and O3)in the Sichuan Basin(SCB),China from 2015 to 2018 in relation to the formation of haze using conventional meteorological data(temperature,wind speed,and relative humidity),satellite data(fire point data,vertical profiles of aerosol subtypes,and aerosol optical depth),planetary boundary layer height,and backward trajectories.The results indicated that the spatio-temporal evolution of the air quality index(AQI)had notable seasonality for the pollution severity in descending order:winter,spring,summer,and autumn.Autumn and winter severe haze events occurred in November and January,respectively,and were caused by higher local pollution emissions under stagnant air conditions.Spring severe haze events occurred in May and were caused by dust from Northwest China and local regions.Severe summer haze events occurred in July and were caused by local burning.Therefore,the analyses showed that local burning,stagnant meteorological conditions,air mass transport and anthropogenic pollution emissions played a key role in haze in the SCB.This study provides scientific insights for fully analyzing heavy air pollution in SCB,China,and also provides a scientific basis for pollution research in regions of complex terrain as basins and mountains.
文摘Effect of cryogenic treatment on the microstructure, hardening behavior and abrasion resistance of 14Cr2Mn2V high chromium cast iron （HCCI） subjected to subcritical treatment was investigated. The results show that cryogenic treatment after subcritical treatment can obviously improve the hardness and abrasion resistance of HCCI because abundant retained austenite is transformed into martensite and fine secondary carbides E（Fe, Cr）23 C6 ] precipitate. The amount of martensite and precipitated secondary carbide in HCCI experiencing subcritical treatment followed by cryogenic treatment was more than that experiencing the subcritical treatment followed by air cooling. When the abrasion resistance of HCCI reaches the maximum, its microstructure contains about 15 % retained austenite. Cryogenic treatment can further reduce the austenite content but the retained austenite cannot be transformed in to martensite completely.
文摘Photocatalysis is considered a promising technique for removal of pollutants from indoor air.However,the low selectivity and limited recyclability of photocatalysts in powder form currently limit their practical application.In this work,we reported the successful preparation of a monolithic tungsten oxide(WO3)/graphene oxide(GO)aerogel photocatalyst through a cost‐effective freeze‐drying method.GO not only acts as a macroscopic support,but also increases the catalyst surface area from 46 to 57 m2/g,enhances the light absorption in the visible‐light region,and raises the separation efficiency of photogenerated electron‐hole pairs.The Obtained WO3/GO aerogel exhibited an outstanding visible‐light photocatalytic degradation rate of nitric oxide of 51%,which was 3.3 times that of pristine WO3 powder.In addition,the aerogel displayed excellent selectivity,with a generation fraction of toxic nitrogen dioxide of as low as 0.5%.This work presents a facile synthesis route to fabricate a monolithic WO3/GO aerogel photocatalyst with great promise for air purification.
基金Supported by National Innovation Project(2009IM032500)Science and Technology Supporting Program of Sichuan Province(2009NZ0015)
文摘Aiming at the safety problems of botanical pesticides currently ignored, the paper analyzes the unsafe factors existing in botanical pesticides from the three aspects of active ingredients, inactive ingredients and unregistered active ingredients, in order to provide a scientific reference for the safe use and effective su- pervision of botanical pesticides.
基金This work was partly supported by the National Key Scientific Instruments to Develop Dedicated Program(Nos.2013YQ090811 and 2016YFF0103800)the National Key Research and Development Program(No.2017YFF0211100).
文摘Si-PIN photodetectors having features such as low cost,small size,low weight,low voltage,and low power consumption are widely used as radiation detectors in electronic personal dosimeters(EPDs).The technical parameters of EPDs based on the Si-PIN photodetectors include photon energy response(PER),angular response,inherent error,and dose rate linearity.Among them,PER is a key parameter for evaluation of EPD measurement accuracy.At present,owing to the limitations of volume,power consumption,and EPD cost,the PER is usually corrected by a combination of single-channel counting techniques and filtering material methods.However,the above-mentioned methods have problems such as poor PER and low measurement accuracy.To solve such problems,in this study,a 1024-channel spectrometry system using a Si-PIN photodetector was developed and fullspectrum measurement in the reference radiation fields was conducted for radiation protection.The measurement results using the few-channel spectroscopy dose method showed that the PER could be controlled within±14%and±2%under the conditions of two and three energy intervals,respectively,with different channel numbers.The PER measured at 0°angle of radiation incidence meets the-29%to+67%requirements of IEC 61526:2010.Meanwhile,the channel number and counts-to-dose conversion factors formed in the experiment can be integrated into an EPD.
基金Supported by National Natural Science Foundation(No.10775101)
文摘For scanning transmission proton microscopy tomography,to compare cell images of the proton stopping power and relative electron density,two cell phantoms are designed and simulated by code FLUKA.The cell images are reconstructed by the filtered back projection algorithm,and compared with their tomography imaging.The images of stopping power and relative electron density slightly vary with proton energies,but the internal images are of clear with high resolution.The organic glass image of relative electron density reveals the resolution power of proton tomography.Also,the simulation results reflect effects of the boundary enhancement,the weak artifacts,and the internal structure border extension by multiple scattering.So using proton tomography to analyze internal structure of a cell is a superior.
基金funded by the Key Research and Development Program of Jiangsu Province(BE2021340)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(21KJB210019)+3 种基金the Jiangsu Postdoctoral Science Foundation(2021K614C)the Key Laboratory of Modern Agricultural Equipment and Technology,Jiangsu University(MAET202119)the Project of Postgraduate Innovation of Jiangsu Province(KYCX22_3683)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD-2018-87).
文摘The wettability of leaf surface,commonly represented by contact angle(CA),affects various physiological and physical processes.The present study aims to better understand the wettability of tea leaves and elucidate its influence on the energy barrier of the droplet condensation process.The CA values of different leaf ages(young,mature and old)of five famous tea cultivars(Maolu,longjing 43,Huangjinya,Zhongcha 108 and Anji Baicha)were measured via the sessile drop method,and the micro-morphology of two cultivars leaves(Maolu,Zhongcha 108)was investigated by a 3D super depth-of-field digital microscope.Specifically,two radically distinctive types of CA trends were observed,one was the decreased firstly and then increased slightly with the increase of leaf age,while the other stayed constant.The valley depth or maximum height(RZ)of Maolu leaf surface increased with the leaf age while the RZ of Zhongcha 108 leaf remained unchanged by comparing the microscopic features.The Maolu mature leaf CA decline attributed to the young leaf was hydrophilic(θ<90°),and it was considered that surface structures like folds and pits on old leaf played a crucial role in making CA increased.Small deviation in CA can lead to significant error in calculation of the contact angle function of energy barrier in phase change.It will have great significant for simulating and better understanding the formation of frost on tea leaves.
基金financial support by Sichuan Science and Technology,China(No.2023YFG0070).
文摘Fuel cell electric vehicles hold great promise for a diverse range of applications in reducing greenhouse gas emissions.In power fuel cell systems,hydrogen fuel serves as an energy vector.To ensure its suitability,it is necessary for the quality of hydrogen to adhere to the standards set by ISO 14687:2019,which sets maximum limits for 14 impurities in hydrogen,aiming to prevent any degradation of fuel cell performance.Ammonia(NH_(3))is a prominent pollutant in fuel cells,and accurate measurements of its concentration are crucial for hydrogen fuel cell quantity.In this study,a novel detection platform was developed for determining NH_(3)in real hydrogen samples.The online analysis platform integrates a self-developed online dilution module with a Fourier transform infrared spectrometer(ODM-FTIR).The ODM-FTIR can be operated fully automatically with remote operation.Under the optimum conditions,this method achieved a wide linear range between(50∼1000)nmol/mol.The limit of detection(LOD)was as low as 2 nmol/mol with a relative standard deviation(RSD,n=7)of 3.6%at a content of 50 nmol/mol.To ensure that the quality of the hydrogen products meets the requirement of proton exchange membrane fuel cell vehicles(PEMFCV),the developed ODM-FTIR system was applied to monitor the NH_(3)content in Chengdu Hydrogen Energy Co.,Ltd.for 21 days during Chengdu 2021 FISU World University Games.The proposed method retains several unique advantages,including a low detection limit,excellent repeatability,high accuracy,high speed,good stability,and calibration flexibility.It is an effective analytical method for accurately quantifying NH_(3)in hydrogen,especially suitable for online analysis.It also provides a new idea for the analysis of other impurity components in hydrogen.
文摘Agricultural investment project selection is a complex multi-criteria decision-making problem,as agricultural projects are easily influenced by various risk factors,and the evaluation information provided by decisionmakers usually involves uncertainty and inconsistency.Existing literature primarily employed direct preference elicitation methods to address such issues,necessitating a great cognitive effort on the part of decision-makers during evaluation,specifically,determining the weights of criteria.In this study,we propose an indirect preference elicitation method,known as a preference disaggregation method,to learn decision-maker preference models fromdecision examples.To enhance evaluation ease,decision-makers merely need to compare pairs of alternatives with which they are familiar,also known as reference alternatives.Probabilistic linguistic preference relations are employed to account for the presence of incomplete and uncertain information in such pairwise comparisons.To address the inconsistency among a group of decision-makers,we develop a pair of 0-1mixed integer programming models that consider both the semantics of linguistic terms and the belief degrees of decision-makers.Finally,we conduct a case study and comparative analysis.Results reveal the effectiveness of the proposed model in solving agricultural investment project selection problems with uncertain and inconsistent decision information.
基金the National Science and Technology Supporting Plan(No.2013BAK12B04)for financial support
文摘A new detection system consisted of a flame ionization detector（FID） and a sulfur chemiluminescence detector（SCD） was developed for sensitive and interference free determination of total sulfur in natural gas by non-separation gas chromatography. In this system, sulfur containing compounds and hydrocarbons were firstly burned in the FID using oxygen rich flame and converted to SO_2, CO_2 and H_2O, respectively. The products from FID were transported into the SCD with hydrogen rich atmosphere wherein only SO_2 could be reduced to SO and reacted with O_3 to produce characteristic chemiluminescence. Therefore, the chemiluminescence of CO found in conventional SCD were eliminated because CO_2 could not be reduced to CO under these conditions. The experimental parameters were systematically investigated. Limit of detection obtained by the proposed system is better than 0.5 mmol/mol for total sulfur and superior to those previously reported. The proposed method not only retains the advantages of the conventional SCD but also provides several unique advantages including no hydrocarbon interference, better stability, and easier calculation. The utility of this technique was demonstrated by the determination of total sulfur in real samples and two certified reference materials（GBW 06332 and GBW（E） 061320）.
基金supported by the National Key Scientific Instruments To Develop Dedicated(2013YQ090811)
文摘An electronic personal dosimeter mainly uses a Si-PIN photodiode as X-and gamma-ray detectors.The photon energy response of this instrument is inconsistent in the case of no correction,which seriously affects the accurate monitoring of personal dose equivalent H_p(10)parameters for radiation workers.For this reason,in this paper we propose a method of combining composite screen detection technology,multichannel measurement technology,and the channel ratio method to achieve accurate measurement of the personal dose equivalent parameters.According to China National Standard GB/T 13161-2003 and National Verification Regulation JJG 1009-2006,the instrument was tested in the energy range between 48 keV and 1.25 MeV.The experimental results showed that the difference of energy response to ^(137)C_S corrected by the new method was almost constant within ±6.0%,which fulfilled the ±30% requirement of GB/T 13161-2003 and JJG1009-2006.Meanwhile,the method proposed obtained energy information regarding the radiation field.
基金the financial support to this work by Sichuan Science and Technology,China(Nos.2019ZDZX0035&2018TZDZX0008)the Ministry of Education through the 111 Project(No.B17030).
文摘Hydrogen fuel cells are among the promising energy sources worldwide,which could accomplish cyclic production of energy and avoid the emission of green-house or contaminative byproducts.However,sulfur compounds(SCs)even at trace level(nmol/mol)are usually involved in cell construction and further H_(2)production,which would cause degradation of the catalysts and shorten the lifetime of the fuel cells.Moreover,the highly reactive SCs could cause varied species and concentrations of them in complex matrices,so online rather than offline analysis of SCs in H_(2)would be preferred.In this context,we developed a new system combining online cryogenic preconcentration of nine SCs and subsequent determination by GC-SCD(sulfur chemiluminescent detector),with the correlation coefficients of the calibration curves higher than 0.999,calculated limits of detection no higher than 0.050 nmol/mol,analytical time around 30 min per sample,and satisfactory precision and accuracy(RSD<5%and SD<15%).The analytical performance was much better than or at least comparable to the previously reported and the developed system was successfully applied for real sample analysis.
基金financially supported by National Natural Science Foundation of China (No.51972045)the FundamentalResearch Funds for the Chinese Central Universities,China (No.ZYGX2019J025)Sichuan Science and Technology Program (No.2020JDRC0015 and No.2020JDRC0045)。
文摘The sensitivity of ethanol sensor is of paramount importance in a variety of areas,including chemical production with ethanol,alcohol testing for driving safety,etc.Herein,α-Fe_(2)O_(3) nano-cylinders with atomic carbon layers are synthesized,for the first time,through in-situ catalytic chemical vapor deposition combined with hydrothermal techniques for the detection of ethanol.The reported α-Fe_(2)O_(3)@C nano-cylinders with double surficial strain effects deliver an ethanol detection sensitivity of 8 times as compared with α-Fe_(2)O_(3) nano-cylinders,10 times higher as compared with its detection sensitivity to ammonia,para-xylene,methanol and benzene.The sensor also exhibits over-14-day operation stability and the minimum detection limit of 10 ppm.To our best knowledge,the performances surpass those of previously reported α-Fe_(2)O_(3).Such attractive performances are attributed to the enhanced charge transfer in α-Fe_(2)O_(3) owing to the double surficial strain effects of α-Fe_(2)O_(3)@C nano-cylinders and the efficient adsorption of ethanol with atomic carbon layers.
基金supported by the Talent Project of Chengdu Technological University,China(Grant No.2023RC013).
文摘Deflectometry is a non-contact and rapid detection method with high sensitivity,which can be utilized in the areas of three-dimensional(3D)reconstruction,surface quality detection,and defect location.It has important applications in the automotive industry,optical parts manufacturing,and other fields.Classical deflectometry methods require the integration of slope data to reconstruct the absolute surface shape.However,the integration procedure is error-prone due to the accumulation of random errors into large shape deviations,resulting in inaccurate measurement results.In this paper,we extract the position of the centerline of the bright fringe from the stripe image and find the center of the fringe line point by point.Using the principle of triangulation,the 3D data for the object’s shaped surface can be obtained.In addition,infrared light enhances specular reflection,resulting in better deflectometry performance than that of visible light.Experiments show that the proposed method is sensitive to the changes in height and can roughly restore the surface topography of the object without calibration.
基金This work is supported by the National Natural Science Foundation of China （61107073, 61107072, and 61290312）, Fundamental Research Funds for the Central Universities （ZYGX2011J002）, Research Fund for the Doctoral Program of Higher Education of China （20110185120020）, Program for Changjiang Scholars and Innovative Research Team in University （PCSIRT, IRT1218）, and the 111 Project （B 14039）.
文摘A fiber-optic Fabry-Perot hydrogen sensor was developed by measuring the fringe contrast changes at different hydrogen concentrations. The experimental results indicated that the sensing performance with the Pd-Y film was better than that with the Pd film. A fringe contrast with a decrease of 0.5 dB was detected with a hydrogen concentration change from 0% to 5.5%. The temperature response of the sensor was also measured.
