In the past few decades,high-speed trains have witnessed tremendous and vigorous development with the appearance of the oil crisis and industrialization,which became a significant trend in the transportation industry ...In the past few decades,high-speed trains have witnessed tremendous and vigorous development with the appearance of the oil crisis and industrialization,which became a significant trend in the transportation industry the world over.With the increase of high-speed railway mileage,the amount of high-speed train has grown sharply,the service life of the trains has increased gradually and the components of the vehicle traction system have become worn and aged as a result.Therefore,advanced maintenance technology and its application are key factors to reduce maintenance cost,human resource input and ensure safe,stable and reliable operation of trains.This paper summarizes and discusses the development,application mode,maintenance management and maintenance technology of high-speed railways of the major countries in the world,especially discusses the condition-based maintenance and the key technology of the traction electrical system,and offers the prospect of research direction and the development of traction maintenance technology.展开更多
Porous oxide ceramics are widely used in extreme working conditions owing to their excellent resistance to high temperatures and corrosion.However,sintering is an inevitable process applied to ceramics,from the green ...Porous oxide ceramics are widely used in extreme working conditions owing to their excellent resistance to high temperatures and corrosion.However,sintering is an inevitable process applied to ceramics,from the green body to the final product.The highly complex structures exacerbate the shrinkage-induced ir-regular deformation and crack formation in the sintering process.A pioneering approach is developed in this study to achieve zero shrinkage for porous alumina ceramics during multistep sintering,using a combination of active fillers-ZrAl 3 and Al 75 Si 25.The response surface method is used to optimize the material compositions and sintering process,to achieve shrinkages of less than 0.05%for the entire pro-cess.The sintering expansion mechanism is investigated by analyzing the pyrolysis and microstructures of samples at different temperatures.The combination of ZrAl 3 and Al 75 Si 25 can attain the continuous expansion of the matrix in a wide temperature range of 600-1400°C.Furthermore,typical alumina com-ponents are fabricated and used to verify the effectiveness of the proposed approach.Owing to shrinkage suppression,the profile deviation of the samples is less than 0.1 mm,and the proportion of microcracks is reduced by 97.8%.The suggested approach shows potential applications in near-net,low-defect fabrica-tion of complex fine ceramic components.展开更多
Objective: This study aimed to investigate the association between single-nucleotide polymorphisms (SNPs) ofPCSK1 (proprotein convertase subtilisin/kexin type 1) related to obesity and nonalcoholic fatty liver disease...Objective: This study aimed to investigate the association between single-nucleotide polymorphisms (SNPs) ofPCSK1 (proprotein convertase subtilisin/kexin type 1) related to obesity and nonalcoholic fatty liver disease (NAFLD).Methods: In this case-control observational study, four candidate SNPs (rs6234, rs155971, rs6232, rs3811951) ofPCSK1 were genotyped in 732 NAFLD patients and 823 healthy control participants, all of whom were of ethnic Han Chinese descent. All participants came from Shanghai, China, and joined our study during 2015 to 2016. The frequencies of each allele and genotype, paired linkage disequilibrium, and haplotype were calculated on the SHEsis platform. In addition to SHEsis, five different genetic models (codominant, dominant, recessive, overdominant, and log-additive) were employed to identify the correlation between genotype frequency and NAFLD. This study was approved by the Medical Ethics Committee of Shanghai University of Traditional Chinese Medicine (approved No. 2017LCSY069).Results: In a comparison of NAFLD patients and healthy participants, none of the fourPCSK1 SNPs were significantly correlated with the occurrence of NAFLD (P>0.05), in either genotypic or allelic distribution. The recessive model of rs3811951 appeared to show a correlation (odds ratio=1.077;95% confidence interval=0.924-1.256;P=0.04), but there was no statistical significance after Bonferroni correction (Pcorr>0.0125).Conclusions: Four obesity-relatedPCSK1 SNPs (rs6234, rs155971, rs6232, rs3811951) showed no significant correlation with the development of NAFLD in a Han Chinese population.展开更多
基金supported by Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ130)the Natural Science Foundation of Fujian Province,China(2021J01577)。
文摘In the past few decades,high-speed trains have witnessed tremendous and vigorous development with the appearance of the oil crisis and industrialization,which became a significant trend in the transportation industry the world over.With the increase of high-speed railway mileage,the amount of high-speed train has grown sharply,the service life of the trains has increased gradually and the components of the vehicle traction system have become worn and aged as a result.Therefore,advanced maintenance technology and its application are key factors to reduce maintenance cost,human resource input and ensure safe,stable and reliable operation of trains.This paper summarizes and discusses the development,application mode,maintenance management and maintenance technology of high-speed railways of the major countries in the world,especially discusses the condition-based maintenance and the key technology of the traction electrical system,and offers the prospect of research direction and the development of traction maintenance technology.
基金the National Natural Science Foun-dation of China(No.52005392)the National Science and Tech-nology Major Project(No.J2019-Ⅶ−0013-0153)the Fundamental Research Funds for the Central Universities,and the Youth Innova-tion Team of Shaanxi Universities.
文摘Porous oxide ceramics are widely used in extreme working conditions owing to their excellent resistance to high temperatures and corrosion.However,sintering is an inevitable process applied to ceramics,from the green body to the final product.The highly complex structures exacerbate the shrinkage-induced ir-regular deformation and crack formation in the sintering process.A pioneering approach is developed in this study to achieve zero shrinkage for porous alumina ceramics during multistep sintering,using a combination of active fillers-ZrAl 3 and Al 75 Si 25.The response surface method is used to optimize the material compositions and sintering process,to achieve shrinkages of less than 0.05%for the entire pro-cess.The sintering expansion mechanism is investigated by analyzing the pyrolysis and microstructures of samples at different temperatures.The combination of ZrAl 3 and Al 75 Si 25 can attain the continuous expansion of the matrix in a wide temperature range of 600-1400°C.Furthermore,typical alumina com-ponents are fabricated and used to verify the effectiveness of the proposed approach.Owing to shrinkage suppression,the profile deviation of the samples is less than 0.1 mm,and the proportion of microcracks is reduced by 97.8%.The suggested approach shows potential applications in near-net,low-defect fabrica-tion of complex fine ceramic components.
基金Innovation Funding in Shanghai(Nos.20JC1418600 and 18JC1413100)National Nature Science Foundation of China(Nos.82071262 and 81671326)+2 种基金Natural Science Foundation of Shanghai(Nos.20ZR1427200 and 20511101900)Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX01)Shanghai Leading Academic Discipline Project(No.B205).
文摘Objective: This study aimed to investigate the association between single-nucleotide polymorphisms (SNPs) ofPCSK1 (proprotein convertase subtilisin/kexin type 1) related to obesity and nonalcoholic fatty liver disease (NAFLD).Methods: In this case-control observational study, four candidate SNPs (rs6234, rs155971, rs6232, rs3811951) ofPCSK1 were genotyped in 732 NAFLD patients and 823 healthy control participants, all of whom were of ethnic Han Chinese descent. All participants came from Shanghai, China, and joined our study during 2015 to 2016. The frequencies of each allele and genotype, paired linkage disequilibrium, and haplotype were calculated on the SHEsis platform. In addition to SHEsis, five different genetic models (codominant, dominant, recessive, overdominant, and log-additive) were employed to identify the correlation between genotype frequency and NAFLD. This study was approved by the Medical Ethics Committee of Shanghai University of Traditional Chinese Medicine (approved No. 2017LCSY069).Results: In a comparison of NAFLD patients and healthy participants, none of the fourPCSK1 SNPs were significantly correlated with the occurrence of NAFLD (P>0.05), in either genotypic or allelic distribution. The recessive model of rs3811951 appeared to show a correlation (odds ratio=1.077;95% confidence interval=0.924-1.256;P=0.04), but there was no statistical significance after Bonferroni correction (Pcorr>0.0125).Conclusions: Four obesity-relatedPCSK1 SNPs (rs6234, rs155971, rs6232, rs3811951) showed no significant correlation with the development of NAFLD in a Han Chinese population.
