This paper aims to evaluate the stochastic response of steel columns subjected to blast loads using the modified single degree of freedom(MSDOF)method,which assessed towards the conventional single degree of freedom(S...This paper aims to evaluate the stochastic response of steel columns subjected to blast loads using the modified single degree of freedom(MSDOF)method,which assessed towards the conventional single degree of freedom(SDOF)and the experimentally validated Finite Element(FE)methods(LSDYNA).For this purpose,special atten-tion is given to calculating the response of H-shaped steel columns under blast.The damage amount is determined based on the support rotation criterion,which is expressed as a function of their maximum lateral mid-span dis-placement.To account for uncertainties in input parameters and obtain the failure probability,the Monte Carlo simulation(MCS)method is employed,complemented by the Latin Hypercube Sampling(LHS)method to reduce the number of simulations.A parametric analysis is hence performed to examine the effect of several input pa-rameters(including both deterministic and probabilistic parameters)on the probability of column damage as a function of support rotation.First,the MSDOF method confirms its higher accuracy in estimating the probability of column damage due to blast,compared to the conventional SDOF.The collected results also show that un-certainties of several input parameters have significant effects on the column behavior.In particular,geometric parameters(including cross-sectional characteristics,boundary conditions and column length)have major effect on the corresponding column response,in the same way of input blast load parameters and material properties.展开更多
The effects of heat treatment on the microstructure of modified cast high chromium high carbon AISI D3 steel were studied. The modified AISI D3 steel was developed by replacing part of chromium with niobium and titani...The effects of heat treatment on the microstructure of modified cast high chromium high carbon AISI D3 steel were studied. The modified AISI D3 steel was developed by replacing part of chromium with niobium and titanium, in which chromium carbide was partially replaced with MC carbides. The cast samples produced by investment casting were heat treated under different conditions. The microstructures of the samples were studied by optical microscope and scanning electron microscope equipped with EDS analyzer. To determine the optimized homogenizing process, the effects of homogenizing treatment on the microstructure and the morphology of carbides were also studied. The results show that the MC carbides are not changed in shape and amounts during high temperature homogenizing, whereas the M3C carbides are reduced in amount and become semiglobular in shape, and the homogeneity of microstructure is improved.展开更多
BACKGROUND： Breast arterial calcification is a frequently benign finding on mammography that usually is not reported. An increasing attention has been formed to determine the association between breast arterial calci...BACKGROUND： Breast arterial calcification is a frequently benign finding on mammography that usually is not reported. An increasing attention has been formed to determine the association between breast arterial calcification （BAC） and Coronary artery disease. In the current study we have aimed to evaluate the relationship between BAC on mammography with coronary CT angiography findings. METHODS： The case control study was carried out on 60 women; 30 CAD and 30 healthy subjects as control, admitted to Golestan hospital radiology department. The mammography was performed in two views; Craniocaudal （CC） view and mediolateral oblique （MLO） and BAC was graded based on the severity and extent of calcifications. Coronary Arterial Calcification （CAC） were scored by Agatston criteria. RESULTS： Overly, 36 patients （60%） were positive for BAC. Twenty six out of them （72%） were CAD. There was a positive significant correlation between BAC and CAD. The sensitivity and specificity of BAC for CAD were 69% and 47%, respectively. Moreover, the severe BAC scores were significantly higher in CAD patients than non-CAD. CONCLUSION： Our findings in line with several previous studies indicated the positive significant association between BAC and CAD occurrence. While the sensitivity and specificity of BAC in diagnosis of CAD is low, suggested the using of BAC just as a CAD risk factor. The relatively low sample size is the major limitation of the study.展开更多
文摘This paper aims to evaluate the stochastic response of steel columns subjected to blast loads using the modified single degree of freedom(MSDOF)method,which assessed towards the conventional single degree of freedom(SDOF)and the experimentally validated Finite Element(FE)methods(LSDYNA).For this purpose,special atten-tion is given to calculating the response of H-shaped steel columns under blast.The damage amount is determined based on the support rotation criterion,which is expressed as a function of their maximum lateral mid-span dis-placement.To account for uncertainties in input parameters and obtain the failure probability,the Monte Carlo simulation(MCS)method is employed,complemented by the Latin Hypercube Sampling(LHS)method to reduce the number of simulations.A parametric analysis is hence performed to examine the effect of several input pa-rameters(including both deterministic and probabilistic parameters)on the probability of column damage as a function of support rotation.First,the MSDOF method confirms its higher accuracy in estimating the probability of column damage due to blast,compared to the conventional SDOF.The collected results also show that un-certainties of several input parameters have significant effects on the column behavior.In particular,geometric parameters(including cross-sectional characteristics,boundary conditions and column length)have major effect on the corresponding column response,in the same way of input blast load parameters and material properties.
文摘The effects of heat treatment on the microstructure of modified cast high chromium high carbon AISI D3 steel were studied. The modified AISI D3 steel was developed by replacing part of chromium with niobium and titanium, in which chromium carbide was partially replaced with MC carbides. The cast samples produced by investment casting were heat treated under different conditions. The microstructures of the samples were studied by optical microscope and scanning electron microscope equipped with EDS analyzer. To determine the optimized homogenizing process, the effects of homogenizing treatment on the microstructure and the morphology of carbides were also studied. The results show that the MC carbides are not changed in shape and amounts during high temperature homogenizing, whereas the M3C carbides are reduced in amount and become semiglobular in shape, and the homogeneity of microstructure is improved.
文摘BACKGROUND： Breast arterial calcification is a frequently benign finding on mammography that usually is not reported. An increasing attention has been formed to determine the association between breast arterial calcification （BAC） and Coronary artery disease. In the current study we have aimed to evaluate the relationship between BAC on mammography with coronary CT angiography findings. METHODS： The case control study was carried out on 60 women; 30 CAD and 30 healthy subjects as control, admitted to Golestan hospital radiology department. The mammography was performed in two views; Craniocaudal （CC） view and mediolateral oblique （MLO） and BAC was graded based on the severity and extent of calcifications. Coronary Arterial Calcification （CAC） were scored by Agatston criteria. RESULTS： Overly, 36 patients （60%） were positive for BAC. Twenty six out of them （72%） were CAD. There was a positive significant correlation between BAC and CAD. The sensitivity and specificity of BAC for CAD were 69% and 47%, respectively. Moreover, the severe BAC scores were significantly higher in CAD patients than non-CAD. CONCLUSION： Our findings in line with several previous studies indicated the positive significant association between BAC and CAD occurrence. While the sensitivity and specificity of BAC in diagnosis of CAD is low, suggested the using of BAC just as a CAD risk factor. The relatively low sample size is the major limitation of the study.
