For the safety protection of passengers when train crashes occur, special structures are crucially needed as a kind of indispensable energy absorbing device. With the help of the structures, crash kinetic-energy can b...For the safety protection of passengers when train crashes occur, special structures are crucially needed as a kind of indispensable energy absorbing device. With the help of the structures, crash kinetic-energy can be completely absorbed or dissipated for the aim of safety. Two composite structures(circumscribed circle structure and inscribed circle structure) were constructed. In addition, comparison and optimization of the crashworthy characteristic of the two structures were carried out based on the method of explicit finite element analysis(FEA) and Kriging surrogate model. According to the result of Kriging surrogate model, conclusions can be safely drawn that the specific energy absorption(SEA) and ratio of specific energy absorption to initial peak force(REAF) of circumscribed circle structure are lager than those of inscribed circle structure under the same design parameters. In other words, circumscribed circle structure has better performances with higher energy-absorbing ability and lower initial peak force. Besides, error analysis was adopted and the result of which indicates that the Kriging surrogate model has high nonlinear fitting precision. What is more, the SEA and REAF optimum values of the two structures have been obtained through analysis, and the crushing results have been illustrated when the two structures reach optimum SEA and REAF.展开更多
According to the practical conditions of coal roadway in Changcun Coal Mine of Lu＇an Mining Group, the deformation of rock surrounding roadway was experimentally studied by means of thermal infrared （TIP,） imaging ...According to the practical conditions of coal roadway in Changcun Coal Mine of Lu＇an Mining Group, the deformation of rock surrounding roadway was experimentally studied by means of thermal infrared （TIP,） imaging system in the process of confined compressions. It is found that the model surface TIR temperature （TIRT） changes with the increase of load. Furthermore, TIRT changes non-synchronously in different ranges such as the roof, floor, wall, corners and bolted ranges. The TIRT is higher in the location of stress concentration and bolted ranges than that in the location of stress relaxation and broken ranges. The interaction ranges of bolt and rock are determined preliminarily according to the corresponding relationship of TIRT fields and the strain fields of the surrounding rock. The new method of TIR image processing has been proved to be effective for the study of bolt support and observation of roadway stability under mine pressure.展开更多
infants.Methods:Systematic searches in PubMed,EMBASE,The Cochrane Library,Web of Science,Chinese biomedical literature database,China National Knowledge Infrastructure,Wanfang medical and VIP database were performed f...infants.Methods:Systematic searches in PubMed,EMBASE,The Cochrane Library,Web of Science,Chinese biomedical literature database,China National Knowledge Infrastructure,Wanfang medical and VIP database were performed for randomized controlled trials(RCTs)or quasi-RCTs which explored the effects of FICare mode on growth and development of premature infants in neonatal intensive care unit.Then,meta-analysis was performed by RevMan 5.3 after two independent investigators screened the literature,extracted the data and evaluated the risk of bias of all included studies.Results:A total of 14 articles were included,including 3120 preterm infants and their families.Meta-analysis showed that compared with the traditional management mode,FICare mode can effectively improve the growth rate of premature infants'weight[Weight mean difference(WMD)=4.02,95%CI(2.47,5.56),P<0.001],increase sleep time[WMD=3.25,95%CI(2.05,4.44),P<0.001],improve breastfeeding rate[RR=1.38,95%CI(1.15,1.64),P<0.001],reduce readmission rate[Relative risk(RR)=0.49,95%CI(0.33,0.71),P<0.001],promote the development of the nervous system[WMD=3.96,95%CI(3.18,4.74),P<0.001],improve nursing skills of Premature infants'parents[WMD=17.40,95%CI(13.64,21.1),P<0.001],reduce the influence of maternal and infant separation on parents'emotions.Conclusion:FICare mode can effectively promote the growth and development of premature infants and alleviate the harm caused by the separation of mother and infants.Limited by the quality and region of the included studies,the appeal conclusion still needs to be tested by more high-quality studies.展开更多
基金Projects(51405516,U1334208)supported by the National Natural Science Foundation of ChinaProject(2013GK2001)supported by the Science and Technology Program for Hunan Provincial Science and Technology Department,ChinaProject(2013zzts040)supported by the Graduate Degree Thesis Innovation Foundation of Central South University,China
文摘For the safety protection of passengers when train crashes occur, special structures are crucially needed as a kind of indispensable energy absorbing device. With the help of the structures, crash kinetic-energy can be completely absorbed or dissipated for the aim of safety. Two composite structures(circumscribed circle structure and inscribed circle structure) were constructed. In addition, comparison and optimization of the crashworthy characteristic of the two structures were carried out based on the method of explicit finite element analysis(FEA) and Kriging surrogate model. According to the result of Kriging surrogate model, conclusions can be safely drawn that the specific energy absorption(SEA) and ratio of specific energy absorption to initial peak force(REAF) of circumscribed circle structure are lager than those of inscribed circle structure under the same design parameters. In other words, circumscribed circle structure has better performances with higher energy-absorbing ability and lower initial peak force. Besides, error analysis was adopted and the result of which indicates that the Kriging surrogate model has high nonlinear fitting precision. What is more, the SEA and REAF optimum values of the two structures have been obtained through analysis, and the crushing results have been illustrated when the two structures reach optimum SEA and REAF.
基金Projects 50374069 supported by National Natural Science Foundation of China and 2002CB412701 supported by 973 of China
文摘According to the practical conditions of coal roadway in Changcun Coal Mine of Lu＇an Mining Group, the deformation of rock surrounding roadway was experimentally studied by means of thermal infrared （TIP,） imaging system in the process of confined compressions. It is found that the model surface TIR temperature （TIRT） changes with the increase of load. Furthermore, TIRT changes non-synchronously in different ranges such as the roof, floor, wall, corners and bolted ranges. The TIRT is higher in the location of stress concentration and bolted ranges than that in the location of stress relaxation and broken ranges. The interaction ranges of bolt and rock are determined preliminarily according to the corresponding relationship of TIRT fields and the strain fields of the surrounding rock. The new method of TIR image processing has been proved to be effective for the study of bolt support and observation of roadway stability under mine pressure.
文摘infants.Methods:Systematic searches in PubMed,EMBASE,The Cochrane Library,Web of Science,Chinese biomedical literature database,China National Knowledge Infrastructure,Wanfang medical and VIP database were performed for randomized controlled trials(RCTs)or quasi-RCTs which explored the effects of FICare mode on growth and development of premature infants in neonatal intensive care unit.Then,meta-analysis was performed by RevMan 5.3 after two independent investigators screened the literature,extracted the data and evaluated the risk of bias of all included studies.Results:A total of 14 articles were included,including 3120 preterm infants and their families.Meta-analysis showed that compared with the traditional management mode,FICare mode can effectively improve the growth rate of premature infants'weight[Weight mean difference(WMD)=4.02,95%CI(2.47,5.56),P<0.001],increase sleep time[WMD=3.25,95%CI(2.05,4.44),P<0.001],improve breastfeeding rate[RR=1.38,95%CI(1.15,1.64),P<0.001],reduce readmission rate[Relative risk(RR)=0.49,95%CI(0.33,0.71),P<0.001],promote the development of the nervous system[WMD=3.96,95%CI(3.18,4.74),P<0.001],improve nursing skills of Premature infants'parents[WMD=17.40,95%CI(13.64,21.1),P<0.001],reduce the influence of maternal and infant separation on parents'emotions.Conclusion:FICare mode can effectively promote the growth and development of premature infants and alleviate the harm caused by the separation of mother and infants.Limited by the quality and region of the included studies,the appeal conclusion still needs to be tested by more high-quality studies.
