AIM:To explore the causal relationship between several possible behavioral factors and high myopia(HM)using multivariable Mendelian randomization(MVMR)approach and to find the mediators among them with mediation analy...AIM:To explore the causal relationship between several possible behavioral factors and high myopia(HM)using multivariable Mendelian randomization(MVMR)approach and to find the mediators among them with mediation analysis.METHODS:The causal effects of several behavioral factors,including screen time,education time,time spent outdoors,and physical activity,on the risk of HM using univariable Mendelian randomization(MR)and MVMR analyses were first assessed.Genome-wide association study summary statistics of serum metabolites were also used in mediation analysis to determine the extent to which serum metabolites mediate the effects of behavioral factors on HM.RESULTS:MR analyses indicated that both increased time spent outdoors and a higher frequency of moderate physical activity significantly reduced the risk of HM.Further MVMR analysis confirmed that moderate physical activity independently contributed to a lower risk of HM.Additionally,MR analyses identified 13 serum metabolites significantly associated with HM,of which 12 were lipids and one was an amino acid derivative.Mediation analysis revealed that six lipid metabolites mediated the protective effects of moderate physical activity on HM,with the highest mediation proportion observed for 1-(1-enyl-palmitoyl)-GPC(p-16:0;30.83%).CONCLUSION:This study suggests that in addition to outdoor time,moderate physical activity habits may have an independent protective effect against HM and pointed to lipid metabolites as priority targets for the prevention due to low physical activity.These results emphasize the importance of physical activity and metabolic health in HM and underscore the need for further study of these complex associations.展开更多
Objectives:Adolescents’aggression is widely studied,the underlying heterogeneity of aggression among rural Chinese boarding students remains unexplored.This study investigates the latent profiles of Chinese rural boa...Objectives:Adolescents’aggression is widely studied,the underlying heterogeneity of aggression among rural Chinese boarding students remains unexplored.This study investigates the latent profiles of Chinese rural boarding junior high school students’aggression and its correlations with moral disengagement and preference for solitude.Methods:A cross-sectional survey was conducted from 04–22 April 2022,using a convenient sampling method among 516 junior high school students from six Chinese rural boarding schools.The survey included the Aggression Questionnaire,the Moral Disengagement Scale(MDS),and the Preference for Solitude Scale(PSS).Results:Participants were divided into three latent profiles:low(36.0%),medium(50.9%),and high aggression levels(13.1%).Compared with low aggression,students who felt left-behind(minors who stay in the rural areas while one or both parents migrated to the urban areas for the work)accounted for a larger proportion in the medium aggression profile.The higher the grade level and the lower the educational level of the students’parents,the greater proportion of students in the medium and high aggression profiles.Additionally,students with high moral disengagement and preference for solitude showed a significant association with the medium aggression and high aggression profiles.Conclusions:The results demonstrate the significant group heterogeneity of aggression groups in Chinese rural boarding junior high school students.Targeted prevention and intervention measures can be carried out according to feeling left-behind,grade level,parents’education,and MDS and PSS scores.展开更多
In modern wireless communication and electromagnetic control,automatic modulationclassification(AMC)of orthogonal frequency division multiplexing(OFDM)signals plays animportant role.However,under Doppler frequency shi...In modern wireless communication and electromagnetic control,automatic modulationclassification(AMC)of orthogonal frequency division multiplexing(OFDM)signals plays animportant role.However,under Doppler frequency shift and complex multipath channel conditions,extracting discriminative features from high-order modulation signals and ensuring model inter-pretability remain challenging.To address these issues,this paper proposes a Fourier attention net-work(FAttNet),which combines an attention mechanism with a Fourier analysis network(FAN).Specifically,the method directly converts the input signal to the frequency domain using the FAN,thereby obtaining frequency features that reflect the periodic variations in amplitude and phase.Abuilt-in attention mechanism then automatically calculates the weights for each frequency band,focusing on the most discriminative components.This approach improves both classification accu-racy and model interpretability.Experimental validation was conducted via high-order modulationsimulation using an RF testbed.The results show that under three different Doppler frequencyshifts and complex multipath channel conditions,with a signal-to-noise ratio of 10 dB,the classifi-cation accuracy can reach 89.1%,90.4%and 90%,all of which are superior to the current main-stream methods.The proposed approach offers practical value for dynamic spectrum access and sig-nal security detection,and it makes important theoretical contributions to the application of deeplearning in complex electromagnetic signal recognition.展开更多
Period and space distribution characteristics of high temperature (above 35 ℃) at 7 weather stations in Shenyang City from 1951 to 2008 were analyzed in this study.The results revealed that the occurrence period of h...Period and space distribution characteristics of high temperature (above 35 ℃) at 7 weather stations in Shenyang City from 1951 to 2008 were analyzed in this study.The results revealed that the occurrence period of high temperature in northern Shenyang was longer than the southern and eastern parts.The northwestern part had the most days of high temperature,the southeastern part came next,and the mid-eastern and southwestern parts had the least.The distribution characteristics of high temperature period were increasing frequency,enhanced intensity and expanded range after 1990s.The occurrence frequency of high temperature was the highest in June and the lowest in August.The hot late summer weather in the middle period of August in 2009 was caused by anomaly atmospheric circulation and subtropical high pressure (stronger and the more westward).展开更多
[ Objective] The paper was to operate the application and promotion of non-pesticide replacing high-toxic pesticides techniques in Kunming City, and to analyze its benefit. [ Method ] Through application and promotion...[ Objective] The paper was to operate the application and promotion of non-pesticide replacing high-toxic pesticides techniques in Kunming City, and to analyze its benefit. [ Method ] Through application and promotion of frequency trembler grid lamps, sticking plate trapping technology, construction of treatment ponds for field waste vegetable leaves, standardized （accurate） cultivation techniques, cultivation techniques of disease-resistant varieties and diverse cultivation technologies, the promotion benefit of non-pesticide replacing high-toxic pesticides techniques was comprehensively investigated and evaluated. [ Result ] The appli- cation and promotion area of non-pesticide replacing high-toxic pesticides techniques in Kunming City during 2006 -2010 reached 94 667 hm2. The investigation on control efforts and quantitative analysis of cost/benefit showed that the beneficial result of application and promotion of non-pesticide replacing high-toxic pesticides techniques was higher than the direct benefit of application and promotion of traditional pesticide replacing techniques. This improvement innovated the traditional pesticide replacing method in replacement work of high-toxic pesticides, reducing the usage volume of pesticide in Kunming City. [ Conclusion] The application and promotion of non-pesticide replacing high-toxic pesticides techniques improved the economic, social and ecological benefit of replacement work of high-toxic pesticides, protected the agricultural ecological environment and promoted the sustainable development of agricultural production.展开更多
China is physically and socio-economically susceptible to global warming-derived high temperature extremes because of its vast area and high urban population density. This article presents a scenario-based analysis me...China is physically and socio-economically susceptible to global warming-derived high temperature extremes because of its vast area and high urban population density. This article presents a scenario-based analysis method for high temperature extremes aimed at illustrating the latter＇s hazardous potential and exposure across China. Based on probability analysis, high temperature extreme scenarios with return periods of 5, 10, 20, and 50 years were designed, with a high temperature hazard index calculated by integrating two differen- tially-weighted extreme temperature indices （maximum temperature and high temperature days）. To perform the exposure analysis, a land use map was employed to determine the spatial distribution of susceptible human activities under the different scenarios. The results indicate that there are two heat-prone regions and a sub-hotspot occupying a relatively small land area. However, the societal and economic consequences of such an environmental im- pact upon the North China Plain and middle/lower Yangtze River Basin would be substantial due to the concentration of human activities in these areas.展开更多
In a continuous casting process, it is essential to prevent the surface defects which are caused by the mold powder entrapments. It is well known that the decrease in the molten steel flow velocity just under the free...In a continuous casting process, it is essential to prevent the surface defects which are caused by the mold powder entrapments. It is well known that the decrease in the molten steel flow velocity just under the free surface is one of the most effective methods for the prevention of mold powder entrapments. For this purpose, the electro-magnetic level stabilizer （EMLS） has been developed, which is applied to a low frequency alternating magnetic field moving from the narrow face of the mold to the mold center below the nozzle exits. In this study, the effect of the EMLS on the molten steel flow is investigated. Numerical simulation of the electromagnetic field and the molten steel flow in a mold were carried out. Simulation results indicate that, due to the electromagnetic force, the molten steel is forced to flow toward the magnetic field traveling direction in the region where the magnetic field is imposed. The molten steel flow is decelerated in proportion to the imposed electromagnetic force. Consequently, the molten steel flows toward the mold center near the free surface with a smaller imposed electromagnetic force, and it flows toward the nozzle at the nozzle side and toward the narrow face at the narrow face side with a larger imposed electromagnetic force. However, the magnitude of the electromagnetic force is decided by the current intensity and frequency, a suitable imposed electric current can be chosen to minimize the flow velocity and also the amount of mold powder entrapments.展开更多
To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numeric...To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numerical simulation was carried out.The tempo-spatial damage characteristics of rock mass were analyzed.The evolution laws of MS source parameters during the formation of a rock collapse controlled by high geostress and geological structure were investigated.Additionally,a three-dimensional DEM model of the underground powerhouse caverns was built to reveal the deformation characteristics of rock mass.The results indicated that the MS events induced by excavation of high geostress underground powerhouse caverns occurred frequently.The large-stake crown of the main powerhouse was the main damage area.Prior to the rock collapse,the MS event count and accumulated energy release increased rapidly,while the apparent stress sharply increased and then decreased.The amount and proportion of shear and mixed MS events remarkably increased.The maximum displacement was generally located near the spandrel areas.The MS monitoring data and numerical simulation were in good agreement,which can provide significant references for damage evaluation and disaster forecasting in high geostress underground powerhouse caverns.展开更多
AIM:To evaluate the global trends in and explore hotspots of high myopia(HM)research.METHODS:This bibliometric analysis was used to reveal the publication trends in HM research field based on the Web of Science Core C...AIM:To evaluate the global trends in and explore hotspots of high myopia(HM)research.METHODS:This bibliometric analysis was used to reveal the publication trends in HM research field based on the Web of Science Core Collection(WoSCC).VOSviewer version 1.6.13 software was used to analyze the data and construct a knowledge map including the yearly publication number,journals,countries,international collaborations,authors,research hotspots,and intellectual base in HM.RESULTS:The search engine found 3544 peer-reviewed publications on HM between 2010 and 2019,and the yearly research output substantially elevated over the past decade.China is the top publishing country,and Sun Yatsen University was the most active academic institution.Jonas JB is the top publishing scientist,and Investigative Ophthalmology and Visual Science(IOVS)was the most productive journal.The highest cited references mainly focused on epidemiology and management.The keywords formed 6 clusters:1)refractive surgery;2)etiology and clinical characteristics;3)the mechanism of eye growth;4)management for myopic maculopathy;5)vitrectomy surgical treatment;6)myopia-associated glaucoma-like optic neuropathy.CONCLUSION:The evaluation of development trends based on the data extracted from WoSCC can provide valuable information and guidance for ophthalmologists and public health researchers to improve management procedures in HM field.展开更多
The characteristics of regional high temperature(HT) weather in 2013 and 2003 and their causes were studied using daily maximum temperature data, National Center for Environmental Prediction(NCEP) reanalysis data, and...The characteristics of regional high temperature(HT) weather in 2013 and 2003 and their causes were studied using daily maximum temperature data, National Center for Environmental Prediction(NCEP) reanalysis data, and outgoing longwave radiation(OLR) data. For these two years of HT weather, there were many similar characteristics, such as their long duration, wide range, high intensity, and severe influence. However, there were also three obvious differences: firstly, in 2013, the major area where HT weather occurred was farther north than in 2003; secondly, the HT weather in South China and the southeast area of Jiangnan in 2013 lasted fewer days than in 2003, but in other areas it lasted for more days than in 2003; thirdly, the intensity of the HT weather in 2013 was also stronger in the north and weaker in the south, similar to that of the duration. A strong and stable western Pacific subtropical high(WPSH), a continental warm high, and the distribution of the warm center in the lower troposphere played important roles in the HT weather formation. Several probable causes for the differences are that the cold air was weaker, the WPSH was farther north, and the tropical convective systems were stronger in 2013 than in 2003. Finally, a preliminary cause analysis of the WPSH anomaly was presented.展开更多
Repeated train passages bring detrimental effects on train operations,especially at high speeds.In this study,a computational model consisting of moving train vehicles,track structure,and track foundation is used to i...Repeated train passages bring detrimental effects on train operations,especially at high speeds.In this study,a computational model consisting of moving train vehicles,track structure,and track foundation is used to investigate the stress distribution in the track substructure and underlying soil,particularly when the train speed approaches the critical speed via 2.5D finite element method.The numerical model has been validated by in-situ test results from a ballasted high-speed railway.The computational results reveal that the substructure is shown to be effective in reducing the stresses transmitted to the ground;however,a simple Boussinesq approximation is proved to be inaccurate because it cannot properly take account of the effect of multi-layered substructures and train speeds.It is acceptable to assume a simplified smooth track in the analysis model for determining the maximum stresses and displacements for a low-speed railway(≤100 km/h)but,for a high-speed one,the dynamic amplification effect of track irregularities must also be considered in subgrade design.Analysis of the stress paths revealed that the load speed and track irregularity increase the likelihood of failure for the subgrade;track irregularity can induce many times of principal stress rotations even under a simple single moving load.展开更多
By utilizing the current finite element program ANSYS, two types of finite element models (FEM), the beam model (BM) and shell model (SM), are established for the nonlinear stability analysis of a practical rigid fram...By utilizing the current finite element program ANSYS, two types of finite element models (FEM), the beam model (BM) and shell model (SM), are established for the nonlinear stability analysis of a practical rigid frame bridge—Longtanhe Great Bridge. In these analyses, geometrical and material nonlinearities are simultaneously taken into account. For geometrical nonlinearity, updated Lagrangian formulations are adopted to derive the tangent stiffness matrix. In order to simulate the nonlinear behavior of the plastic hinge of the piers, the multi lines spring element COMBIN39 is used in the SM while the bilinear rotational spring element COMBIN40 is employed in the BM. Numerical calculations show that satisfying results can be obtained in the stability analysis of the bridge when the double coupling nonlinearity effects are considered. In addition, the conclusion is significant for practical engineering.展开更多
To study active heat insulation roadway in high temperature mines,the typical high temperature roadway of−965 m in Zhujidong Coal Mine of Anhui,China,is selected as prototype.The ANSYS numerical simulation method is u...To study active heat insulation roadway in high temperature mines,the typical high temperature roadway of−965 m in Zhujidong Coal Mine of Anhui,China,is selected as prototype.The ANSYS numerical simulation method is used for sensitivity analysis of heat insulation layer with different thermal conductivity and thickness,as well as surrounding rock with different thermal conductivity and temperature on a heat-adjusting zone radius,surrounding rock temperature field and wall temperature.The results show that the heat-adjusting zone radius will entirely be in the right power index relationship to the ventilation time.Decrease in thermal conductivity and increase in thickness of insulation layer can effectively reduce the disturbance of airflow on the surrounding rock temperature,hence,beneficial for decreasing wall temperature.This favourable trend significantly decreases with ventilation time,increase in thermal conductivity and temperature of surrounding rock,heat-adjusting zone radius,surrounding rock temperature field,and wall temperature.Sensitivity analysis shows that the thermal physical properties of surrounding rock determine the temperature distribution of the roadway,hence,temperature of surrounding rock is considered as the most sensitive factor of all influencing factors.For the spray layer,thermal conductivity is more sensitive,compared to thickness.It is concluded that increase in the spray layer thickness is not as beneficial as using low thermal conductivity insulation material.Therefore,roadway preferential consideration should be given to the rocks with low temperature and thermal conductivity.The application of the insulation layer has positive significance for the thermal environment control in mine roadway,however,increase in the layer thickness without restriction has a limited effect on the thermal insulation.展开更多
Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was...Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was established;the fluid-structure couplingof water jet and coal was implemented by penalty function and convection calculation.The dynamic process of coal breaking under a water jet was simulated and analyzed bycombining the united fracture criteria of the maximum tensile strain and the maximal shearstrain in the two cases of damage to coal and damage failure to coal.展开更多
Although it is well known that cloud cavitation shows unsteady behavior with the growing motion of an attached cavity, the shedding motion of a cloud, the collapsing motion of the cloud shed downstream and a reentrant...Although it is well known that cloud cavitation shows unsteady behavior with the growing motion of an attached cavity, the shedding motion of a cloud, the collapsing motion of the cloud shed downstream and a reentrant motion in flow fields such as on a 2-D hydrofoil and in a convergent- divergent channel with a rectangular cross-section, observations for the periodic behavior of cloud cavitation in a cylindrical nozzle with a convergent-divergent part, which is mainly used in an industrial field, have hardly been conducted. From engineering viewpoints, it is important to elucidate the mechanism of periodic cavitation behavior in a cylindrical nozzle. In this study, a high-speed observation technique with an image analysis technique was applied to the cloud cavitation behavior in the nozzle to make clear the mechanism of unsteady behavior. As a result, it was observed in the nozzle that the periodic behavior occurs in the cloud cavitation and pressure waves form at the collapse of clouds shed downstream. Also, it was found through the image analysis based on the present technique that the pressure wave plays a role as a trigger mechanism to cause a reentrant motion at the downstream end of an attached cavity.展开更多
[Objective] The research aimed to study the reason of local heavy rainstorm forecast error in the subtropical high control. [Method] Started from summarizing the reason of forecast error, by using the conventional gro...[Objective] The research aimed to study the reason of local heavy rainstorm forecast error in the subtropical high control. [Method] Started from summarizing the reason of forecast error, by using the conventional ground observation data, the upper air sounding data, T639, T213 and European Center (ECMWF) numerical prediction product data, GFS precipitation forecast product of U.S. National Center for Environmental Prediction, the weather situation, physical quantity field in a heavy rainstorm process which happened in the north of Shaoyang at night on August 5, 2010 were fully analyzed. Based on the numerical analysis forecast product data, the reason of heavy rainstorm forecast error in the subtropical high was comprehensively analyzed by using the comparison and analysis method of forecast and actual situation. [Result] The forecasters didn’t deeply and carefully analyze the weather situation. On the surface, 500 hPa was controlled by the subtropical high, but there was the weak shear line in 700 and 850 hPa. Moreover, they neglected the influences of weak cold air and easterlies wave. The subtropical high quickly weakened, and the system adjustment was too quick. The wind field variations in 850, 700 and 500 hPa which were forecasted by ECMWF had the big error with the actual situation. It was by east about 2 longitudes than the actual situation. In summer forecast, they only considered the intensity and position variations of 500 hPa subtropical high, and neglected the situation variations in the middle, low levels and on the ground. It was the most key element which caused the rainstorm forecast error in the subtropical high. The forecast error of numerical forecast products on the height field situation variation was big. The precipitation forecasts of Japan FSAS, U.S. National Center for Environmental Prediction GFS, T639 and T213 were all small. The humidity field forecast value of T639 was small. In the rainstorm forecast, the local rainstorm forecast index and method weren’t used in the forecast practice. In the precipitation forecast process, they only paid attention to the score prediction of station and didn’t value the non-site prediction. Some important physical quantity factors weren’t carefully studied. [Conclusion] The research provided the reference basis for the forecast and early warning of local heavy rainstorm.展开更多
1 INTRODUCTION In summer, different assembly of the intensity, location and vertical structure of the subtropical high and the earlier/later time of its seasonal northwards jump bring about different precipitation pat...1 INTRODUCTION In summer, different assembly of the intensity, location and vertical structure of the subtropical high and the earlier/later time of its seasonal northwards jump bring about different precipitation patterns over China. Therefore, subtropical high activity and its cause during the occurrence of extreme climatic event over China and the cause of China drought/flood are studied to improve weather forecasting.展开更多
High frequency transformer is used in many applications among the Switch Mode Power Supply (SMPS), high voltage pulse power and etc can be mentioned. Regarding that the core of these transformers is often the ferrite ...High frequency transformer is used in many applications among the Switch Mode Power Supply (SMPS), high voltage pulse power and etc can be mentioned. Regarding that the core of these transformers is often the ferrite core;their functions partly depend on this core characteristic. One of the characteristics of the ferrite core is thermal behavior that should be paid attention to because it affects the transformer function and causes heat generation. In this paper, a typical high frequency transformer with ferrite core is designed and simulated in ANSYS software. Temperature rise due to winding current (Joule-heat) is considered as heat generation source for thermal behavior analysis of the transformer. In this simulation, the temperature rise and heat distribution are studied and the effects of parameters such as flux density, winding loss value, using a fan to cool the winding and core and thermal conductivity are investigated.展开更多
Objective:To develop the representative fingerprint for the quality control of placenta polypeptide injection.Methods:The chromatographic separation was performed using a Phenomenex Gemini C18 column(250 mm 4.6 mm,5 m...Objective:To develop the representative fingerprint for the quality control of placenta polypeptide injection.Methods:The chromatographic separation was performed using a Phenomenex Gemini C18 column(250 mm 4.6 mm,5 mm)maintained at 301C.0.1%aqueous trifiuoroacetic acid(Solvent A)and acetonitrile contained 0.1%TFA(Solvent B)were used as mobile phase with a gradient elution.Detection wavelength was 280 nm with the sample injection volume of 50 mL;the fiow rate was 1.0 mL/min.The fingerprints of different samples were investigated by similarity analysis.Results:Nine peaks were identified as the characteristic common peaks.The similarities of the fingerprints of the 10 batches of samples were above 0.992.Conclusion:This method showed high precision and good repeatability,and provided the basis for the improvement of the quality control of placenta polypeptide injection.展开更多
Alpha linolenic acid(ALA)is an essential polyunsaturated fatty acids that can improve human health.Rapeseed is the second largest oil crop in the world but the ALA content in its seed fatty acids is only about 10%.Two...Alpha linolenic acid(ALA)is an essential polyunsaturated fatty acids that can improve human health.Rapeseed is the second largest oil crop in the world but the ALA content in its seed fatty acids is only about 10%.Two rapeseed germplasms YH25005 and R8Q10 with high content(up to 21%)ALA were developed by intervarietal crossing.They were used as the maternal parent(P_(1))when crossed with a low ALA parent SW(P2)to produce the seeds of the F1 hybrid,F2,and backcrosses to P1(BCP1)and P2(BCP2).A multigeneration joint segregation analysis was conducted to determine major gene t polygene effects of the content of three major unsaturated fatty acids including oleic(OA),linoleic(LA)and ALA.The results showed that,although some genes favorable to ALA accumulation were not allelic in R8Q10 and YH25005,all the inheritances of OA,LA and ALA in YH25005×SW and R8Q10×SW followed a genetic model of‘two pairs of additive major genes t additive-dominant polygenes’.It is suggested that the contents of OA,LA and ALA are closely related and the major genes in the parent SW containing loss-of-function mutations in FAD2 and FAD3 loci had strong effect to reduce ALA and elevate OA.However,total genetic effect of the polygenes was greater than that of the two major genes,especial on ALA content.It indicated that it is necessary to employ a larger F2 population to find the plant that accumulate enough minor-effect polygenes for high ALA content.The results are useful for high ALA rapeseed breeding and future work of gene mapping.展开更多
基金Supported by the Central High Level Hospital Clinical Research Funding(No.BJ-2024-089).
文摘AIM:To explore the causal relationship between several possible behavioral factors and high myopia(HM)using multivariable Mendelian randomization(MVMR)approach and to find the mediators among them with mediation analysis.METHODS:The causal effects of several behavioral factors,including screen time,education time,time spent outdoors,and physical activity,on the risk of HM using univariable Mendelian randomization(MR)and MVMR analyses were first assessed.Genome-wide association study summary statistics of serum metabolites were also used in mediation analysis to determine the extent to which serum metabolites mediate the effects of behavioral factors on HM.RESULTS:MR analyses indicated that both increased time spent outdoors and a higher frequency of moderate physical activity significantly reduced the risk of HM.Further MVMR analysis confirmed that moderate physical activity independently contributed to a lower risk of HM.Additionally,MR analyses identified 13 serum metabolites significantly associated with HM,of which 12 were lipids and one was an amino acid derivative.Mediation analysis revealed that six lipid metabolites mediated the protective effects of moderate physical activity on HM,with the highest mediation proportion observed for 1-(1-enyl-palmitoyl)-GPC(p-16:0;30.83%).CONCLUSION:This study suggests that in addition to outdoor time,moderate physical activity habits may have an independent protective effect against HM and pointed to lipid metabolites as priority targets for the prevention due to low physical activity.These results emphasize the importance of physical activity and metabolic health in HM and underscore the need for further study of these complex associations.
基金the General project of the“14th Five-Year Plan”of Education Science of Gansu Province in 2023:“Research on the Integration Strategy of Rural Primary School Labor Education and Other Disciplines under the Background of Rural Revitalization”(Project number:GS[2023]GHB1420)Gansu Provincial University Curriculum Ideological and Political Demonstration Project“Exploration and Practice of Ideological and Political Courses in Pre-School EducationMajors from the Perspective of Three Educations:A Case study of Pre-School EducationHistory”(Project No.:GSkcsz-2021-094).
文摘Objectives:Adolescents’aggression is widely studied,the underlying heterogeneity of aggression among rural Chinese boarding students remains unexplored.This study investigates the latent profiles of Chinese rural boarding junior high school students’aggression and its correlations with moral disengagement and preference for solitude.Methods:A cross-sectional survey was conducted from 04–22 April 2022,using a convenient sampling method among 516 junior high school students from six Chinese rural boarding schools.The survey included the Aggression Questionnaire,the Moral Disengagement Scale(MDS),and the Preference for Solitude Scale(PSS).Results:Participants were divided into three latent profiles:low(36.0%),medium(50.9%),and high aggression levels(13.1%).Compared with low aggression,students who felt left-behind(minors who stay in the rural areas while one or both parents migrated to the urban areas for the work)accounted for a larger proportion in the medium aggression profile.The higher the grade level and the lower the educational level of the students’parents,the greater proportion of students in the medium and high aggression profiles.Additionally,students with high moral disengagement and preference for solitude showed a significant association with the medium aggression and high aggression profiles.Conclusions:The results demonstrate the significant group heterogeneity of aggression groups in Chinese rural boarding junior high school students.Targeted prevention and intervention measures can be carried out according to feeling left-behind,grade level,parents’education,and MDS and PSS scores.
基金supported by the National Natural Science Foundation of China(No.62027801).
文摘In modern wireless communication and electromagnetic control,automatic modulationclassification(AMC)of orthogonal frequency division multiplexing(OFDM)signals plays animportant role.However,under Doppler frequency shift and complex multipath channel conditions,extracting discriminative features from high-order modulation signals and ensuring model inter-pretability remain challenging.To address these issues,this paper proposes a Fourier attention net-work(FAttNet),which combines an attention mechanism with a Fourier analysis network(FAN).Specifically,the method directly converts the input signal to the frequency domain using the FAN,thereby obtaining frequency features that reflect the periodic variations in amplitude and phase.Abuilt-in attention mechanism then automatically calculates the weights for each frequency band,focusing on the most discriminative components.This approach improves both classification accu-racy and model interpretability.Experimental validation was conducted via high-order modulationsimulation using an RF testbed.The results show that under three different Doppler frequencyshifts and complex multipath channel conditions,with a signal-to-noise ratio of 10 dB,the classifi-cation accuracy can reach 89.1%,90.4%and 90%,all of which are superior to the current main-stream methods.The proposed approach offers practical value for dynamic spectrum access and sig-nal security detection,and it makes important theoretical contributions to the application of deeplearning in complex electromagnetic signal recognition.
文摘Period and space distribution characteristics of high temperature (above 35 ℃) at 7 weather stations in Shenyang City from 1951 to 2008 were analyzed in this study.The results revealed that the occurrence period of high temperature in northern Shenyang was longer than the southern and eastern parts.The northwestern part had the most days of high temperature,the southeastern part came next,and the mid-eastern and southwestern parts had the least.The distribution characteristics of high temperature period were increasing frequency,enhanced intensity and expanded range after 1990s.The occurrence frequency of high temperature was the highest in June and the lowest in August.The hot late summer weather in the middle period of August in 2009 was caused by anomaly atmospheric circulation and subtropical high pressure (stronger and the more westward).
基金Supported by Non-pesticide Replacing High-toxic Pesticides Project in Yunnan Province (ynzz-200733)~~
文摘[ Objective] The paper was to operate the application and promotion of non-pesticide replacing high-toxic pesticides techniques in Kunming City, and to analyze its benefit. [ Method ] Through application and promotion of frequency trembler grid lamps, sticking plate trapping technology, construction of treatment ponds for field waste vegetable leaves, standardized （accurate） cultivation techniques, cultivation techniques of disease-resistant varieties and diverse cultivation technologies, the promotion benefit of non-pesticide replacing high-toxic pesticides techniques was comprehensively investigated and evaluated. [ Result ] The appli- cation and promotion area of non-pesticide replacing high-toxic pesticides techniques in Kunming City during 2006 -2010 reached 94 667 hm2. The investigation on control efforts and quantitative analysis of cost/benefit showed that the beneficial result of application and promotion of non-pesticide replacing high-toxic pesticides techniques was higher than the direct benefit of application and promotion of traditional pesticide replacing techniques. This improvement innovated the traditional pesticide replacing method in replacement work of high-toxic pesticides, reducing the usage volume of pesticide in Kunming City. [ Conclusion] The application and promotion of non-pesticide replacing high-toxic pesticides techniques improved the economic, social and ecological benefit of replacement work of high-toxic pesticides, protected the agricultural ecological environment and promoted the sustainable development of agricultural production.
基金National Natural Science Foundation of China, No.41071324 No.41201550+5 种基金 No.40730526 Humanities and Social Sciences Project from the Ministry of Education, No.12YJCZtt257 The Innovation Program of Shanghai Municipal Education Commission, No. 13YZ061 No.13ZZ035 Open Fund of Key Laboratory of Geographic Information Science, East China Normal University, No.KLGIS2011A04 The Fundamental Re- search Funds for the Central Universities, and the Key Subject Development Project of the Shanghai Munici- pal Education Commission, No.J50402
文摘China is physically and socio-economically susceptible to global warming-derived high temperature extremes because of its vast area and high urban population density. This article presents a scenario-based analysis method for high temperature extremes aimed at illustrating the latter＇s hazardous potential and exposure across China. Based on probability analysis, high temperature extreme scenarios with return periods of 5, 10, 20, and 50 years were designed, with a high temperature hazard index calculated by integrating two differen- tially-weighted extreme temperature indices （maximum temperature and high temperature days）. To perform the exposure analysis, a land use map was employed to determine the spatial distribution of susceptible human activities under the different scenarios. The results indicate that there are two heat-prone regions and a sub-hotspot occupying a relatively small land area. However, the societal and economic consequences of such an environmental im- pact upon the North China Plain and middle/lower Yangtze River Basin would be substantial due to the concentration of human activities in these areas.
文摘In a continuous casting process, it is essential to prevent the surface defects which are caused by the mold powder entrapments. It is well known that the decrease in the molten steel flow velocity just under the free surface is one of the most effective methods for the prevention of mold powder entrapments. For this purpose, the electro-magnetic level stabilizer （EMLS） has been developed, which is applied to a low frequency alternating magnetic field moving from the narrow face of the mold to the mold center below the nozzle exits. In this study, the effect of the EMLS on the molten steel flow is investigated. Numerical simulation of the electromagnetic field and the molten steel flow in a mold were carried out. Simulation results indicate that, due to the electromagnetic force, the molten steel is forced to flow toward the magnetic field traveling direction in the region where the magnetic field is imposed. The molten steel flow is decelerated in proportion to the imposed electromagnetic force. Consequently, the molten steel flows toward the mold center near the free surface with a smaller imposed electromagnetic force, and it flows toward the nozzle at the nozzle side and toward the narrow face at the narrow face side with a larger imposed electromagnetic force. However, the magnitude of the electromagnetic force is decided by the current intensity and frequency, a suitable imposed electric current can be chosen to minimize the flow velocity and also the amount of mold powder entrapments.
基金Project(2017YFC1501100)supported by the National Key R&D Program of ChinaProjects(51809221,51679158)supported by the National Natural Science Foundation of China。
文摘To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numerical simulation was carried out.The tempo-spatial damage characteristics of rock mass were analyzed.The evolution laws of MS source parameters during the formation of a rock collapse controlled by high geostress and geological structure were investigated.Additionally,a three-dimensional DEM model of the underground powerhouse caverns was built to reveal the deformation characteristics of rock mass.The results indicated that the MS events induced by excavation of high geostress underground powerhouse caverns occurred frequently.The large-stake crown of the main powerhouse was the main damage area.Prior to the rock collapse,the MS event count and accumulated energy release increased rapidly,while the apparent stress sharply increased and then decreased.The amount and proportion of shear and mixed MS events remarkably increased.The maximum displacement was generally located near the spandrel areas.The MS monitoring data and numerical simulation were in good agreement,which can provide significant references for damage evaluation and disaster forecasting in high geostress underground powerhouse caverns.
基金Supported by Natural Science Key Research Project of the Education Department of Liaoning Province(No.ZD2020003)Natural Science Foundation of Liaoning Province(No.2019-MS-376)。
文摘AIM:To evaluate the global trends in and explore hotspots of high myopia(HM)research.METHODS:This bibliometric analysis was used to reveal the publication trends in HM research field based on the Web of Science Core Collection(WoSCC).VOSviewer version 1.6.13 software was used to analyze the data and construct a knowledge map including the yearly publication number,journals,countries,international collaborations,authors,research hotspots,and intellectual base in HM.RESULTS:The search engine found 3544 peer-reviewed publications on HM between 2010 and 2019,and the yearly research output substantially elevated over the past decade.China is the top publishing country,and Sun Yatsen University was the most active academic institution.Jonas JB is the top publishing scientist,and Investigative Ophthalmology and Visual Science(IOVS)was the most productive journal.The highest cited references mainly focused on epidemiology and management.The keywords formed 6 clusters:1)refractive surgery;2)etiology and clinical characteristics;3)the mechanism of eye growth;4)management for myopic maculopathy;5)vitrectomy surgical treatment;6)myopia-associated glaucoma-like optic neuropathy.CONCLUSION:The evaluation of development trends based on the data extracted from WoSCC can provide valuable information and guidance for ophthalmologists and public health researchers to improve management procedures in HM field.
基金supported by the Major Meteorological Industry Standard Program of China Meteorological Administration (Grant No. QX/T-2012-24)
文摘The characteristics of regional high temperature(HT) weather in 2013 and 2003 and their causes were studied using daily maximum temperature data, National Center for Environmental Prediction(NCEP) reanalysis data, and outgoing longwave radiation(OLR) data. For these two years of HT weather, there were many similar characteristics, such as their long duration, wide range, high intensity, and severe influence. However, there were also three obvious differences: firstly, in 2013, the major area where HT weather occurred was farther north than in 2003; secondly, the HT weather in South China and the southeast area of Jiangnan in 2013 lasted fewer days than in 2003, but in other areas it lasted for more days than in 2003; thirdly, the intensity of the HT weather in 2013 was also stronger in the north and weaker in the south, similar to that of the duration. A strong and stable western Pacific subtropical high(WPSH), a continental warm high, and the distribution of the warm center in the lower troposphere played important roles in the HT weather formation. Several probable causes for the differences are that the cold air was weaker, the WPSH was farther north, and the tropical convective systems were stronger in 2013 than in 2003. Finally, a preliminary cause analysis of the WPSH anomaly was presented.
基金the National Natural Science Foundation of China(No.52108308)the Start-up Fund of Fuzhou University(No.0050-510086 GXRC-20024)+1 种基金the Young Scientist Program of Fujian Provincial Natural Science Foundation of China(No.2020J05107)the Foundation of MOE Key Laboratory of Soft Soils and Geoenviromental Engineering,Zhejiang University,China(No.2020P05)。
文摘Repeated train passages bring detrimental effects on train operations,especially at high speeds.In this study,a computational model consisting of moving train vehicles,track structure,and track foundation is used to investigate the stress distribution in the track substructure and underlying soil,particularly when the train speed approaches the critical speed via 2.5D finite element method.The numerical model has been validated by in-situ test results from a ballasted high-speed railway.The computational results reveal that the substructure is shown to be effective in reducing the stresses transmitted to the ground;however,a simple Boussinesq approximation is proved to be inaccurate because it cannot properly take account of the effect of multi-layered substructures and train speeds.It is acceptable to assume a simplified smooth track in the analysis model for determining the maximum stresses and displacements for a low-speed railway(≤100 km/h)but,for a high-speed one,the dynamic amplification effect of track irregularities must also be considered in subgrade design.Analysis of the stress paths revealed that the load speed and track irregularity increase the likelihood of failure for the subgrade;track irregularity can induce many times of principal stress rotations even under a simple single moving load.
文摘By utilizing the current finite element program ANSYS, two types of finite element models (FEM), the beam model (BM) and shell model (SM), are established for the nonlinear stability analysis of a practical rigid frame bridge—Longtanhe Great Bridge. In these analyses, geometrical and material nonlinearities are simultaneously taken into account. For geometrical nonlinearity, updated Lagrangian formulations are adopted to derive the tangent stiffness matrix. In order to simulate the nonlinear behavior of the plastic hinge of the piers, the multi lines spring element COMBIN39 is used in the SM while the bilinear rotational spring element COMBIN40 is employed in the BM. Numerical calculations show that satisfying results can be obtained in the stability analysis of the bridge when the double coupling nonlinearity effects are considered. In addition, the conclusion is significant for practical engineering.
基金This work was supported by the National Natural Science Foundation of China(51774011)Funding Project of Anhui University of Science and Technology(QN2019115)Introduced Research Funding of Anhui University of Science and Technology(13190022).
文摘To study active heat insulation roadway in high temperature mines,the typical high temperature roadway of−965 m in Zhujidong Coal Mine of Anhui,China,is selected as prototype.The ANSYS numerical simulation method is used for sensitivity analysis of heat insulation layer with different thermal conductivity and thickness,as well as surrounding rock with different thermal conductivity and temperature on a heat-adjusting zone radius,surrounding rock temperature field and wall temperature.The results show that the heat-adjusting zone radius will entirely be in the right power index relationship to the ventilation time.Decrease in thermal conductivity and increase in thickness of insulation layer can effectively reduce the disturbance of airflow on the surrounding rock temperature,hence,beneficial for decreasing wall temperature.This favourable trend significantly decreases with ventilation time,increase in thermal conductivity and temperature of surrounding rock,heat-adjusting zone radius,surrounding rock temperature field,and wall temperature.Sensitivity analysis shows that the thermal physical properties of surrounding rock determine the temperature distribution of the roadway,hence,temperature of surrounding rock is considered as the most sensitive factor of all influencing factors.For the spray layer,thermal conductivity is more sensitive,compared to thickness.It is concluded that increase in the spray layer thickness is not as beneficial as using low thermal conductivity insulation material.Therefore,roadway preferential consideration should be given to the rocks with low temperature and thermal conductivity.The application of the insulation layer has positive significance for the thermal environment control in mine roadway,however,increase in the layer thickness without restriction has a limited effect on the thermal insulation.
基金Supported by the National Basic Research Program of China(973 Program)(2005CB221504)the National Natural Science Foundation of China(50534080)the National Science and Technology Supporting Program of China(the 11th Five-Year Program)(2006BAK03B03)
文摘Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was established;the fluid-structure couplingof water jet and coal was implemented by penalty function and convection calculation.The dynamic process of coal breaking under a water jet was simulated and analyzed bycombining the united fracture criteria of the maximum tensile strain and the maximal shearstrain in the two cases of damage to coal and damage failure to coal.
文摘Although it is well known that cloud cavitation shows unsteady behavior with the growing motion of an attached cavity, the shedding motion of a cloud, the collapsing motion of the cloud shed downstream and a reentrant motion in flow fields such as on a 2-D hydrofoil and in a convergent- divergent channel with a rectangular cross-section, observations for the periodic behavior of cloud cavitation in a cylindrical nozzle with a convergent-divergent part, which is mainly used in an industrial field, have hardly been conducted. From engineering viewpoints, it is important to elucidate the mechanism of periodic cavitation behavior in a cylindrical nozzle. In this study, a high-speed observation technique with an image analysis technique was applied to the cloud cavitation behavior in the nozzle to make clear the mechanism of unsteady behavior. As a result, it was observed in the nozzle that the periodic behavior occurs in the cloud cavitation and pressure waves form at the collapse of clouds shed downstream. Also, it was found through the image analysis based on the present technique that the pressure wave plays a role as a trigger mechanism to cause a reentrant motion at the downstream end of an attached cavity.
文摘[Objective] The research aimed to study the reason of local heavy rainstorm forecast error in the subtropical high control. [Method] Started from summarizing the reason of forecast error, by using the conventional ground observation data, the upper air sounding data, T639, T213 and European Center (ECMWF) numerical prediction product data, GFS precipitation forecast product of U.S. National Center for Environmental Prediction, the weather situation, physical quantity field in a heavy rainstorm process which happened in the north of Shaoyang at night on August 5, 2010 were fully analyzed. Based on the numerical analysis forecast product data, the reason of heavy rainstorm forecast error in the subtropical high was comprehensively analyzed by using the comparison and analysis method of forecast and actual situation. [Result] The forecasters didn’t deeply and carefully analyze the weather situation. On the surface, 500 hPa was controlled by the subtropical high, but there was the weak shear line in 700 and 850 hPa. Moreover, they neglected the influences of weak cold air and easterlies wave. The subtropical high quickly weakened, and the system adjustment was too quick. The wind field variations in 850, 700 and 500 hPa which were forecasted by ECMWF had the big error with the actual situation. It was by east about 2 longitudes than the actual situation. In summer forecast, they only considered the intensity and position variations of 500 hPa subtropical high, and neglected the situation variations in the middle, low levels and on the ground. It was the most key element which caused the rainstorm forecast error in the subtropical high. The forecast error of numerical forecast products on the height field situation variation was big. The precipitation forecasts of Japan FSAS, U.S. National Center for Environmental Prediction GFS, T639 and T213 were all small. The humidity field forecast value of T639 was small. In the rainstorm forecast, the local rainstorm forecast index and method weren’t used in the forecast practice. In the precipitation forecast process, they only paid attention to the score prediction of station and didn’t value the non-site prediction. Some important physical quantity factors weren’t carefully studied. [Conclusion] The research provided the reference basis for the forecast and early warning of local heavy rainstorm.
基金Research on Floods-Causing Heavy Rains in the Valley of Huaihe River in 2003, a projectfrom the National Meteorological Center
文摘1 INTRODUCTION In summer, different assembly of the intensity, location and vertical structure of the subtropical high and the earlier/later time of its seasonal northwards jump bring about different precipitation patterns over China. Therefore, subtropical high activity and its cause during the occurrence of extreme climatic event over China and the cause of China drought/flood are studied to improve weather forecasting.
文摘High frequency transformer is used in many applications among the Switch Mode Power Supply (SMPS), high voltage pulse power and etc can be mentioned. Regarding that the core of these transformers is often the ferrite core;their functions partly depend on this core characteristic. One of the characteristics of the ferrite core is thermal behavior that should be paid attention to because it affects the transformer function and causes heat generation. In this paper, a typical high frequency transformer with ferrite core is designed and simulated in ANSYS software. Temperature rise due to winding current (Joule-heat) is considered as heat generation source for thermal behavior analysis of the transformer. In this simulation, the temperature rise and heat distribution are studied and the effects of parameters such as flux density, winding loss value, using a fan to cool the winding and core and thermal conductivity are investigated.
文摘Objective:To develop the representative fingerprint for the quality control of placenta polypeptide injection.Methods:The chromatographic separation was performed using a Phenomenex Gemini C18 column(250 mm 4.6 mm,5 mm)maintained at 301C.0.1%aqueous trifiuoroacetic acid(Solvent A)and acetonitrile contained 0.1%TFA(Solvent B)were used as mobile phase with a gradient elution.Detection wavelength was 280 nm with the sample injection volume of 50 mL;the fiow rate was 1.0 mL/min.The fingerprints of different samples were investigated by similarity analysis.Results:Nine peaks were identified as the characteristic common peaks.The similarities of the fingerprints of the 10 batches of samples were above 0.992.Conclusion:This method showed high precision and good repeatability,and provided the basis for the improvement of the quality control of placenta polypeptide injection.
基金supported by the project of Key R&D plans of Shaanxi Province(2021NY-074)Yangling Seed Industry Innovation Plan.
文摘Alpha linolenic acid(ALA)is an essential polyunsaturated fatty acids that can improve human health.Rapeseed is the second largest oil crop in the world but the ALA content in its seed fatty acids is only about 10%.Two rapeseed germplasms YH25005 and R8Q10 with high content(up to 21%)ALA were developed by intervarietal crossing.They were used as the maternal parent(P_(1))when crossed with a low ALA parent SW(P2)to produce the seeds of the F1 hybrid,F2,and backcrosses to P1(BCP1)and P2(BCP2).A multigeneration joint segregation analysis was conducted to determine major gene t polygene effects of the content of three major unsaturated fatty acids including oleic(OA),linoleic(LA)and ALA.The results showed that,although some genes favorable to ALA accumulation were not allelic in R8Q10 and YH25005,all the inheritances of OA,LA and ALA in YH25005×SW and R8Q10×SW followed a genetic model of‘two pairs of additive major genes t additive-dominant polygenes’.It is suggested that the contents of OA,LA and ALA are closely related and the major genes in the parent SW containing loss-of-function mutations in FAD2 and FAD3 loci had strong effect to reduce ALA and elevate OA.However,total genetic effect of the polygenes was greater than that of the two major genes,especial on ALA content.It indicated that it is necessary to employ a larger F2 population to find the plant that accumulate enough minor-effect polygenes for high ALA content.The results are useful for high ALA rapeseed breeding and future work of gene mapping.
