Effects of the strain rate on cement paste, mortar and concrete were studied. A modified SHPB testing technique with fl attened Brazilian disc（FBD） specimen was developed to measure the dynamic tensile stress-strain...Effects of the strain rate on cement paste, mortar and concrete were studied. A modified SHPB testing technique with fl attened Brazilian disc（FBD） specimen was developed to measure the dynamic tensile stress-strain curve of materials. A pulse-shaped split Hopkinson pressure bar（SHPB） was employed to determine the dynamic tensile mechanical responses and failure behavior of materials under valid dynamic testing conditions. Quasi-static experiments were conducted to study material strain rate sensitivity. Strain rate sensitivity of the materials was measured in terms of the stress-strain curve, elastic modulus, tensile strength and critical strain at peak stress. Empirical relations between dynamic increase factor（DIF） and the material properties were derived and presented.展开更多
This paper aims to research the effects of combined application of humic acid and urea on the wheat yield and yield component,and establish rational fertilizer application scheme of wheat. Split plot experiment was ad...This paper aims to research the effects of combined application of humic acid and urea on the wheat yield and yield component,and establish rational fertilizer application scheme of wheat. Split plot experiment was adopted. Two types of phosphorus fertilizer( adding humic acid or not) was assigned to the main plot,and four types of top dressing modes( different amount of urea and humic acid urea) were used in subplots. Effects of combined application of humic acid and urea on the wheat yield and yield component were researched. 375 kg / ha ordinary DAP + 150 kg / ha urea was used as base fertilizer; topdressing of 300 kg / ha urea humate could effectively promote the plant height,leaf area coefficient and aboveground dry matter amount. Adding humic acid in urea in topdressing significantly enhanced the wheat yield and economic coefficient of wheat. Adding humic acid in urea in topdressing has better effects of yield increasing than base fertilizer,and can be used for large scale extension.展开更多
基金Funded by the National Natural Science Foundation of China(No.51509078)the Natural Science Foundation of Jiangsu Province(No.BK20150820)
文摘Effects of the strain rate on cement paste, mortar and concrete were studied. A modified SHPB testing technique with fl attened Brazilian disc（FBD） specimen was developed to measure the dynamic tensile stress-strain curve of materials. A pulse-shaped split Hopkinson pressure bar（SHPB） was employed to determine the dynamic tensile mechanical responses and failure behavior of materials under valid dynamic testing conditions. Quasi-static experiments were conducted to study material strain rate sensitivity. Strain rate sensitivity of the materials was measured in terms of the stress-strain curve, elastic modulus, tensile strength and critical strain at peak stress. Empirical relations between dynamic increase factor（DIF） and the material properties were derived and presented.
基金Supported by National Modern Agricultural Industrial Technological System Foundation of the Ministry of Agriculture(CARS-3)
文摘This paper aims to research the effects of combined application of humic acid and urea on the wheat yield and yield component,and establish rational fertilizer application scheme of wheat. Split plot experiment was adopted. Two types of phosphorus fertilizer( adding humic acid or not) was assigned to the main plot,and four types of top dressing modes( different amount of urea and humic acid urea) were used in subplots. Effects of combined application of humic acid and urea on the wheat yield and yield component were researched. 375 kg / ha ordinary DAP + 150 kg / ha urea was used as base fertilizer; topdressing of 300 kg / ha urea humate could effectively promote the plant height,leaf area coefficient and aboveground dry matter amount. Adding humic acid in urea in topdressing significantly enhanced the wheat yield and economic coefficient of wheat. Adding humic acid in urea in topdressing has better effects of yield increasing than base fertilizer,and can be used for large scale extension.
