BACKGROUND Recent research has underscored the potentially protective role of dietary antioxidants against chronic conditions,such as cardiovascular diseases and stroke.The composite dietary antioxidant index(CDAI),wh...BACKGROUND Recent research has underscored the potentially protective role of dietary antioxidants against chronic conditions,such as cardiovascular diseases and stroke.The composite dietary antioxidant index(CDAI),which reflects the overall intake of key dietary antioxidants,has been identified as a crucial metric for exploring this relationship.Although previous research has shown a negative correlation between CDAI levels and stroke risk in prediabetic individuals,there remains a substantial gap in understanding this association among individuals with diabetes,who are at an inherently greater risk for cerebrovascular events.AIM To investigate the association between CDAI and stroke risk in individuals with diabetes.METHODS Using a cross-sectional study design,this investigation analyzed data from the National Health and Nutrition Examination Survey spanning from 2003 to 2018 that included 6735 participants aged over 20 years with diabetes.The CDAI was calculated from 24-h dietary recalls to assess intake of key antioxidants:Vitamins A,C,and E;carotenoids;selenium;and zinc.Multivariate logistic regression and restricted cubic spline analysis were used to rigorously examine the relationship between CDAI and stroke risk.RESULTS The participant cohort,with an average age of 59.5 years and a slight male majority,reflected the broader demographic characteristics of individuals with diabetes.The analysis revealed a strong inverse relationship between CDAI levels and stroke risk.Remarkably,those in the highest quintile of CDAI demonstrated a 43%lower prevalence of stroke compared to those in the lowest quintile,even after adjustments for various confounders.This finding not only highlights the negative association between CDAI and stroke risk but also underscores the significant potential of antioxidant-rich diets in reducing stroke prevalence among patients with diabetes.CONCLUSION Our findings suggested that CDAI was inversely associated with stroke prevalence among patients with diabetes.These results suggest incorporating antioxidant-rich foods into dietary regimens as a potential strategy for stroke prevention.展开更多
BACKGROUND Dietary fiber(DF)intake may have a protective effect against type 2 diabetes(T2D);however,its relationship with diabetic kidney disease(DKD)remains unclear.AIM To investigate the potential association betwe...BACKGROUND Dietary fiber(DF)intake may have a protective effect against type 2 diabetes(T2D);however,its relationship with diabetic kidney disease(DKD)remains unclear.AIM To investigate the potential association between DF intake and the prevalence of DKD in individuals diagnosed with T2D.METHODS This cross-sectional study used data from the National Health and Nutrition Examination Survey collected between 2005 and 2018.DF intake was assessed through 24-h dietary recall interviews,and DKD diagnosis in individuals with T2D was based on predefined criteria,including albuminuria,impaired glomerular filtration rate,or a combination of both.Logistic regression analysis was used to assess the association between DF intake and DKD,and comprehensive subgroup and sensitivity analyses were performed.RESULTS Among the 6032 participants,38.4%had DKD.With lower DF intake-T1(≤6.4 g/1000 kcal/day)-as a reference,the adjusted odds ratio for DF and DKD for levels T2(6.5-10.0 g/1000 kcal/day)and T3(≥10.1 g/1000 kcal/day)were 0.97(95%CI:0.84-1.12,P=0.674)and 0.79(95%CI:0.68-0.92,P=0.002),respectively.The subgroup analysis yielded consistent results across various demographic and health-related subgroups,with no statistically significant interactions(all P>0.05).CONCLUSION In United States adults with T2D,increased DF intake may be related to reduced DKD incidence.Further research is required to confirm these findings.展开更多
Calculations on the dynamics of the reaction O( 1 D) + HBr --+ OH Br are performed on the ab initio potential energy surfaces (PESs) of the ground state given by Peterson [Peterson K A J. Chem. Phys. 113 4598 ...Calculations on the dynamics of the reaction O( 1 D) + HBr --+ OH Br are performed on the ab initio potential energy surfaces (PESs) of the ground state given by Peterson [Peterson K A J. Chem. Phys. 113 4598 (2000)] using the quasi classical trajectory (QCT) method. The product distribution of the dihedral angle, P (φr), and that of the angle between k and j, P (Or), are presented in three dimensions. Moreover, we also investigate the reagent vibrational excitation effects on the two polarization-dependent generalized differential cross sections (PDDCS), PDDCS00 and PDDCS20, in the center- of-mass frame. The results indicate that the vector properties are sensitive to the reagent vibrational quantum number.展开更多
BACKGROUND Separation of the pubic symphysis can occur during the peripartum period.Relaxin(RLX)is a hormone primarily secreted by the corpus luteum that can mediate hemodynamic changes during pregnancy as well as loo...BACKGROUND Separation of the pubic symphysis can occur during the peripartum period.Relaxin(RLX)is a hormone primarily secreted by the corpus luteum that can mediate hemodynamic changes during pregnancy as well as loosen the pelvic ligaments.However,it is unknown whether RLX is associated with peripartum pubic symphysis separation and if the association is affected by other factors.AIM To study the association between RLX and peripartum pubic symphysis separation and evaluate other factors that might affect this association.METHODS We performed a cross-sectional study of pregnant women between April 2019 and January 2020.Baseline demographic characteristics,including gestational age,weight,neonatal weight,delivery mode and duration of the first and second stages of labor,were recorded.The clinical symptoms were used as a screening index during pregnancy,and the patients with pubic symphysis and inguinal pain were examined by color Doppler ultrasonography to determine whether there was pubic symphysis separation.Serum RLX concentrations were evaluated 1 d after delivery using an enzyme-linked immunosorbent assay,and pubic symphysis separation was diagnosed based on postpartum X-ray examination.We used an independent-sample t test to analyze the association between serum RLX levels and peripartum pubic symphysis separation.Multivariate regression analysis was used to evaluate whether the association between RLX and peripartum pubic symphysis separation was confounded by other factors,and the association between RLX and the severity of pubic symphysis separation was also assessed.We used Pearson correlation analysis to determine the factors related to RLX levels as well as the correlation between the degree of pubic symphysis separation and activities of daily living(ADL)and pain.RESULTS A total of 54 women were enrolled in the study,with 15 exhibiting(observational group)and 39 not exhibiting(control group)peripartum pubic symphysis separation.There were no statistically significant differences in terms of maternal age,gestational age,pre-pregnancy weight,weight gain during pregnancy,delivery modes,or duration of the first or second stages of labor between the 2 groups.We did,however,note a statistically significant difference in serum RLX concentrations and neonatal weight between the observational and control groups(122.3±0.7μg/mL vs 170.4±42.3μg/mL,P<0.05;3676.000±521.725 g vs 3379.487±402.420 g,P<0.05,respectively).Multivariate regression analyses showed that serum RLX level[odds ratio(OR):1.022)and neonatal weight(OR:1.002)were associated with pubic symphysis separation peripartum.The degree of separation of the pubic symphysis was negatively correlated with ADL and positively correlated with pain.There was no statistically significant association between serum RLX levels and the severity of pubic symphysis separation after adjusting for confounding factors.CONCLUSION Serum RLX levels and neonatal weight were associated with the occurrence,but not the severity,of peripartum pubic symphysis separation.展开更多
AIM: To determine hepatitis C virus (HCV) seropreva- lence and its genotypes, and to identify the factors associated with HCV infection. METHODS: This cross-sectional study, conducted in two prisons (one male and...AIM: To determine hepatitis C virus (HCV) seropreva- lence and its genotypes, and to identify the factors associated with HCV infection. METHODS: This cross-sectional study, conducted in two prisons (one male and one female) in the State of Ser- gipe, Brazil, comprised 422 subjects. All of the prisoners underwent a rapid test for the detection of HCV antibod- ies. Patient~ with a positive result were tested for anti- HCV by enzyme linked immunosorbent assay and for HCV RNA by qualitative polymerase chain reaction (PCR). The virus genotype was defined in every serum sample that presented positive for PCR-HCV. In order to determine the factors independently associated with positive serol- ogy for HCV, multivariate logistic regression was used. RESULTS: HCV seroprevalence was 3.1%. Of the 13 subjects with positive anti-HCV, 11 had viremia confirmed by PCR. Of these, 90.9% had genotype 1. A total of 43 (10.2%) were injecting drug users, and HCV seroprevalence in this subgroup was 20.6%. The variable most strongly associated with positive serology for HCV was use of injecting drugs [odds ratio (OR), 23.3; 95% confidence interval (CI), 6.0-90.8]. Age over 30 years (OR, 5.5; 95%CI, 1.1-29.2), history of syphilis (OR, 9.8; 95%CI, 1.7-55.2) and history of household contact with HCV positive individual (OR, 14.1; 95%CI, 2.3-85.4) were also independently associated with HCV infection. CONCLUSION: Most of the HCV transmissions result from parenteral exposure. However, there is evidence to suggest a role for sex and household contact with an infected subject in virus transmission.展开更多
Three-Coulomb-wave method is employed to treat the process of (e, 2e) simultaneous ion- ization and excitation to the n=2 state of helium, with radial and angular correlated wave-function of He target. The triple di...Three-Coulomb-wave method is employed to treat the process of (e, 2e) simultaneous ion- ization and excitation to the n=2 state of helium, with radial and angular correlated wave-function of He target. The triple differential cross sections are calculated and analyzed in very asymmetric coplanar geometry at incident energies of 5.50, 1.50 and 0.57 keV. Results are compared with the absolute measurements and the theoretical first and second Born approximation. The present triply differential cross section (TDCS) is found to be in good agreement with experimental data qualitatively. The distinguishing feature noted in TDCS structure is the presence of intense recoil peak that for certain parameters is even larger than the binary peak, an unusual feature for the single-ionization process at high and intermediate energies.展开更多
A large sample crosssectional survey was conducted to draw the possible relationship between green tea drinking and the mortality of hepatocellular carcinoma(HCC). The results showed that the tea drinking rate and tea...A large sample crosssectional survey was conducted to draw the possible relationship between green tea drinking and the mortality of hepatocellular carcinoma(HCC). The results showed that the tea drinking rate and tea consumption in various male populations had significant negative relationship with the death rate of HCC, and the correlation coefficients were -0.92 and -0.91 respectively. The accumulative death rate of HCC was 120.05 per 100 000 in teadrinking population and 245.53 per 100 000 in nontea drinking population. The same results were observed after adjusting the confounding factors such as tobacco smoking and alcohol drinking by using stratified analysis method. The paper suggested that tea drinking may have cancerpreventive and carcinogenesis inhibition effect.展开更多
Image interpolation of cross-sections is one of the key steps of medical visualization, and the cubic convolution interpolation is usually employed due to its good tradeoff between computational cost and accuracy, how...Image interpolation of cross-sections is one of the key steps of medical visualization, and the cubic convolution interpolation is usually employed due to its good tradeoff between computational cost and accuracy, however, sometimes its accuracy can still not meet the requirement. Aimed at the problem, in this paper, the interpolation principle based cubic convolution is firstly analyzed systematically, and then essential relationship among the different cubic convolution interpolation methods is clarified. Lastly, a novel cross-section interpolation method for medical images that is based on the optimal parameter of sharp control is presented. The method takes full advantage of the local characteristic of medical images, and the optimized sharp control parameter is obtained by the iterative computation, and then the cross-section interpolation is performed by the cubic convolution with the optimized parameter in one time.The experimental results show that the method presented in the paper not only can improve the interpolation accuracy effectively, but also is robust.展开更多
In order to study the mechanics behavior of a thin-walled box continuous girder with variable crosssections,using potential variation theories,considering the effect of shear lag of flange’s stress and the nonlinear ...In order to study the mechanics behavior of a thin-walled box continuous girder with variable crosssections,using potential variation theories,considering the effect of shear lag of flange’s stress and the nonlinear geometry of vertical displacement,and evolving five generalized displacements with the spline function,the large deflection problem of the thin-walled box continuous girder with variable cross-section was transformed to a nonlinear algebraic equation,which was solved using the Newton-Raphon iterative method.The results of the calculation show that different shear lag warp functions to the cantilever,top and bottom plate should be taken to analyze the mechanics behavior of the thin-walled box continuous girder reliably.The thin-walled box continuous girder with variable cross-sections has more reasonable stress state and is more adaptable for the longitudinal change of internal forces than that with equal crosssections.The effect of large deflection on the stress and displacement of the thin-walled box continuous girder with variable cross-sections depends on the values of the load.展开更多
In this paper,a DG(Discontinuous Galerkin)method which has been widely employed in CFD(Computational Fluid Dynamics)is used to solve the twodimensional time-domain Maxwell’s equations for complex geometries on unstru...In this paper,a DG(Discontinuous Galerkin)method which has been widely employed in CFD(Computational Fluid Dynamics)is used to solve the twodimensional time-domain Maxwell’s equations for complex geometries on unstructured mesh.The element interfaces on solid boundary are treated in both curved way and straight way.Numerical tests are performed for both benchmark problems and complex cases with varying orders on a series of grids,where the high-order convergence in accuracy can be observed.Both the curved and the straight solid boundary implementation can give accurate RCS(Radar Cross-Section)results with sufficiently small mesh size,but the curved solid boundary implementation can significantly improve the accuracy when using relatively large mesh size.More importantly,this CFD-based high-order DG method for the Maxwell’s equations is very suitable for complex geometries.展开更多
Two LICET transitions in Cs-Sr systems are suggested and the results of numerical calculations of the transition probability and collisional crosssection are obtained respectively from our four-level model and the con...Two LICET transitions in Cs-Sr systems are suggested and the results of numerical calculations of the transition probability and collisional crosssection are obtained respectively from our four-level model and the conventional three-level model. Comparisons of these results prove the theoretical prediction that if the frequency difference ω21, is comparable to ω43, the three-level theory has great error in describing the LICET transition, while the four-level theory can describe all cases of LICET process perfectly.展开更多
This paper is the first contribution towards the rigorous justification of asymptotic 1D models for the time-domain simulation of the propagation of electromagnetic waves in coaxial cables.Our general objective is to ...This paper is the first contribution towards the rigorous justification of asymptotic 1D models for the time-domain simulation of the propagation of electromagnetic waves in coaxial cables.Our general objective is to derive error estimates between the"exact"solution of the full 3D model and the"approximate"solution of the 1D model known as the Telegraphist’s equation.展开更多
基金Supported by Strategic Priority Research Program of Chinese Academy of Sciences,No.XDB38010100Construction and Validation of an Early Identification System for Cardiovascular Disease Associated with Glucose Metabolism Disorders,No.202204295107020026Science and Technology Projects in Guangzhou,No.2023A04J1087.
文摘BACKGROUND Recent research has underscored the potentially protective role of dietary antioxidants against chronic conditions,such as cardiovascular diseases and stroke.The composite dietary antioxidant index(CDAI),which reflects the overall intake of key dietary antioxidants,has been identified as a crucial metric for exploring this relationship.Although previous research has shown a negative correlation between CDAI levels and stroke risk in prediabetic individuals,there remains a substantial gap in understanding this association among individuals with diabetes,who are at an inherently greater risk for cerebrovascular events.AIM To investigate the association between CDAI and stroke risk in individuals with diabetes.METHODS Using a cross-sectional study design,this investigation analyzed data from the National Health and Nutrition Examination Survey spanning from 2003 to 2018 that included 6735 participants aged over 20 years with diabetes.The CDAI was calculated from 24-h dietary recalls to assess intake of key antioxidants:Vitamins A,C,and E;carotenoids;selenium;and zinc.Multivariate logistic regression and restricted cubic spline analysis were used to rigorously examine the relationship between CDAI and stroke risk.RESULTS The participant cohort,with an average age of 59.5 years and a slight male majority,reflected the broader demographic characteristics of individuals with diabetes.The analysis revealed a strong inverse relationship between CDAI levels and stroke risk.Remarkably,those in the highest quintile of CDAI demonstrated a 43%lower prevalence of stroke compared to those in the lowest quintile,even after adjustments for various confounders.This finding not only highlights the negative association between CDAI and stroke risk but also underscores the significant potential of antioxidant-rich diets in reducing stroke prevalence among patients with diabetes.CONCLUSION Our findings suggested that CDAI was inversely associated with stroke prevalence among patients with diabetes.These results suggest incorporating antioxidant-rich foods into dietary regimens as a potential strategy for stroke prevention.
文摘BACKGROUND Dietary fiber(DF)intake may have a protective effect against type 2 diabetes(T2D);however,its relationship with diabetic kidney disease(DKD)remains unclear.AIM To investigate the potential association between DF intake and the prevalence of DKD in individuals diagnosed with T2D.METHODS This cross-sectional study used data from the National Health and Nutrition Examination Survey collected between 2005 and 2018.DF intake was assessed through 24-h dietary recall interviews,and DKD diagnosis in individuals with T2D was based on predefined criteria,including albuminuria,impaired glomerular filtration rate,or a combination of both.Logistic regression analysis was used to assess the association between DF intake and DKD,and comprehensive subgroup and sensitivity analyses were performed.RESULTS Among the 6032 participants,38.4%had DKD.With lower DF intake-T1(≤6.4 g/1000 kcal/day)-as a reference,the adjusted odds ratio for DF and DKD for levels T2(6.5-10.0 g/1000 kcal/day)and T3(≥10.1 g/1000 kcal/day)were 0.97(95%CI:0.84-1.12,P=0.674)and 0.79(95%CI:0.68-0.92,P=0.002),respectively.The subgroup analysis yielded consistent results across various demographic and health-related subgroups,with no statistically significant interactions(all P>0.05).CONCLUSION In United States adults with T2D,increased DF intake may be related to reduced DKD incidence.Further research is required to confirm these findings.
基金supported by the Natural Science Fund from Jilin University,China(Grant No.419080106440)the Chinese National Fusion Project for ITER(GrantNo.2010GB104003)the National Natural Science Foundation of China(Grant No.10974069)
文摘Calculations on the dynamics of the reaction O( 1 D) + HBr --+ OH Br are performed on the ab initio potential energy surfaces (PESs) of the ground state given by Peterson [Peterson K A J. Chem. Phys. 113 4598 (2000)] using the quasi classical trajectory (QCT) method. The product distribution of the dihedral angle, P (φr), and that of the angle between k and j, P (Or), are presented in three dimensions. Moreover, we also investigate the reagent vibrational excitation effects on the two polarization-dependent generalized differential cross sections (PDDCS), PDDCS00 and PDDCS20, in the center- of-mass frame. The results indicate that the vector properties are sensitive to the reagent vibrational quantum number.
基金The Science and Technology Development Plan of Taian,No.2018NS0203.
文摘BACKGROUND Separation of the pubic symphysis can occur during the peripartum period.Relaxin(RLX)is a hormone primarily secreted by the corpus luteum that can mediate hemodynamic changes during pregnancy as well as loosen the pelvic ligaments.However,it is unknown whether RLX is associated with peripartum pubic symphysis separation and if the association is affected by other factors.AIM To study the association between RLX and peripartum pubic symphysis separation and evaluate other factors that might affect this association.METHODS We performed a cross-sectional study of pregnant women between April 2019 and January 2020.Baseline demographic characteristics,including gestational age,weight,neonatal weight,delivery mode and duration of the first and second stages of labor,were recorded.The clinical symptoms were used as a screening index during pregnancy,and the patients with pubic symphysis and inguinal pain were examined by color Doppler ultrasonography to determine whether there was pubic symphysis separation.Serum RLX concentrations were evaluated 1 d after delivery using an enzyme-linked immunosorbent assay,and pubic symphysis separation was diagnosed based on postpartum X-ray examination.We used an independent-sample t test to analyze the association between serum RLX levels and peripartum pubic symphysis separation.Multivariate regression analysis was used to evaluate whether the association between RLX and peripartum pubic symphysis separation was confounded by other factors,and the association between RLX and the severity of pubic symphysis separation was also assessed.We used Pearson correlation analysis to determine the factors related to RLX levels as well as the correlation between the degree of pubic symphysis separation and activities of daily living(ADL)and pain.RESULTS A total of 54 women were enrolled in the study,with 15 exhibiting(observational group)and 39 not exhibiting(control group)peripartum pubic symphysis separation.There were no statistically significant differences in terms of maternal age,gestational age,pre-pregnancy weight,weight gain during pregnancy,delivery modes,or duration of the first or second stages of labor between the 2 groups.We did,however,note a statistically significant difference in serum RLX concentrations and neonatal weight between the observational and control groups(122.3±0.7μg/mL vs 170.4±42.3μg/mL,P<0.05;3676.000±521.725 g vs 3379.487±402.420 g,P<0.05,respectively).Multivariate regression analyses showed that serum RLX level[odds ratio(OR):1.022)and neonatal weight(OR:1.002)were associated with pubic symphysis separation peripartum.The degree of separation of the pubic symphysis was negatively correlated with ADL and positively correlated with pain.There was no statistically significant association between serum RLX levels and the severity of pubic symphysis separation after adjusting for confounding factors.CONCLUSION Serum RLX levels and neonatal weight were associated with the occurrence,but not the severity,of peripartum pubic symphysis separation.
文摘AIM: To determine hepatitis C virus (HCV) seropreva- lence and its genotypes, and to identify the factors associated with HCV infection. METHODS: This cross-sectional study, conducted in two prisons (one male and one female) in the State of Ser- gipe, Brazil, comprised 422 subjects. All of the prisoners underwent a rapid test for the detection of HCV antibod- ies. Patient~ with a positive result were tested for anti- HCV by enzyme linked immunosorbent assay and for HCV RNA by qualitative polymerase chain reaction (PCR). The virus genotype was defined in every serum sample that presented positive for PCR-HCV. In order to determine the factors independently associated with positive serol- ogy for HCV, multivariate logistic regression was used. RESULTS: HCV seroprevalence was 3.1%. Of the 13 subjects with positive anti-HCV, 11 had viremia confirmed by PCR. Of these, 90.9% had genotype 1. A total of 43 (10.2%) were injecting drug users, and HCV seroprevalence in this subgroup was 20.6%. The variable most strongly associated with positive serology for HCV was use of injecting drugs [odds ratio (OR), 23.3; 95% confidence interval (CI), 6.0-90.8]. Age over 30 years (OR, 5.5; 95%CI, 1.1-29.2), history of syphilis (OR, 9.8; 95%CI, 1.7-55.2) and history of household contact with HCV positive individual (OR, 14.1; 95%CI, 2.3-85.4) were also independently associated with HCV infection. CONCLUSION: Most of the HCV transmissions result from parenteral exposure. However, there is evidence to suggest a role for sex and household contact with an infected subject in virus transmission.
文摘Three-Coulomb-wave method is employed to treat the process of (e, 2e) simultaneous ion- ization and excitation to the n=2 state of helium, with radial and angular correlated wave-function of He target. The triple differential cross sections are calculated and analyzed in very asymmetric coplanar geometry at incident energies of 5.50, 1.50 and 0.57 keV. Results are compared with the absolute measurements and the theoretical first and second Born approximation. The present triply differential cross section (TDCS) is found to be in good agreement with experimental data qualitatively. The distinguishing feature noted in TDCS structure is the presence of intense recoil peak that for certain parameters is even larger than the binary peak, an unusual feature for the single-ionization process at high and intermediate energies.
文摘A large sample crosssectional survey was conducted to draw the possible relationship between green tea drinking and the mortality of hepatocellular carcinoma(HCC). The results showed that the tea drinking rate and tea consumption in various male populations had significant negative relationship with the death rate of HCC, and the correlation coefficients were -0.92 and -0.91 respectively. The accumulative death rate of HCC was 120.05 per 100 000 in teadrinking population and 245.53 per 100 000 in nontea drinking population. The same results were observed after adjusting the confounding factors such as tobacco smoking and alcohol drinking by using stratified analysis method. The paper suggested that tea drinking may have cancerpreventive and carcinogenesis inhibition effect.
文摘Image interpolation of cross-sections is one of the key steps of medical visualization, and the cubic convolution interpolation is usually employed due to its good tradeoff between computational cost and accuracy, however, sometimes its accuracy can still not meet the requirement. Aimed at the problem, in this paper, the interpolation principle based cubic convolution is firstly analyzed systematically, and then essential relationship among the different cubic convolution interpolation methods is clarified. Lastly, a novel cross-section interpolation method for medical images that is based on the optimal parameter of sharp control is presented. The method takes full advantage of the local characteristic of medical images, and the optimized sharp control parameter is obtained by the iterative computation, and then the cross-section interpolation is performed by the cubic convolution with the optimized parameter in one time.The experimental results show that the method presented in the paper not only can improve the interpolation accuracy effectively, but also is robust.
文摘In order to study the mechanics behavior of a thin-walled box continuous girder with variable crosssections,using potential variation theories,considering the effect of shear lag of flange’s stress and the nonlinear geometry of vertical displacement,and evolving five generalized displacements with the spline function,the large deflection problem of the thin-walled box continuous girder with variable cross-section was transformed to a nonlinear algebraic equation,which was solved using the Newton-Raphon iterative method.The results of the calculation show that different shear lag warp functions to the cantilever,top and bottom plate should be taken to analyze the mechanics behavior of the thin-walled box continuous girder reliably.The thin-walled box continuous girder with variable cross-sections has more reasonable stress state and is more adaptable for the longitudinal change of internal forces than that with equal crosssections.The effect of large deflection on the stress and displacement of the thin-walled box continuous girder with variable cross-sections depends on the values of the load.
基金National Natural Science Foundation of China:No.11272152 and Aeronautical Science Foundation of China:No.20101552018.
文摘In this paper,a DG(Discontinuous Galerkin)method which has been widely employed in CFD(Computational Fluid Dynamics)is used to solve the twodimensional time-domain Maxwell’s equations for complex geometries on unstructured mesh.The element interfaces on solid boundary are treated in both curved way and straight way.Numerical tests are performed for both benchmark problems and complex cases with varying orders on a series of grids,where the high-order convergence in accuracy can be observed.Both the curved and the straight solid boundary implementation can give accurate RCS(Radar Cross-Section)results with sufficiently small mesh size,but the curved solid boundary implementation can significantly improve the accuracy when using relatively large mesh size.More importantly,this CFD-based high-order DG method for the Maxwell’s equations is very suitable for complex geometries.
文摘Two LICET transitions in Cs-Sr systems are suggested and the results of numerical calculations of the transition probability and collisional crosssection are obtained respectively from our four-level model and the conventional three-level model. Comparisons of these results prove the theoretical prediction that if the frequency difference ω21, is comparable to ω43, the three-level theory has great error in describing the LICET transition, while the four-level theory can describe all cases of LICET process perfectly.
文摘This paper is the first contribution towards the rigorous justification of asymptotic 1D models for the time-domain simulation of the propagation of electromagnetic waves in coaxial cables.Our general objective is to derive error estimates between the"exact"solution of the full 3D model and the"approximate"solution of the 1D model known as the Telegraphist’s equation.