Part-time farming has been increasing steadily in China. It is currently the largest segment among all the farm sectors in the country. Based on rural household survey data in Taipusi County as a case site ofecologica...Part-time farming has been increasing steadily in China. It is currently the largest segment among all the farm sectors in the country. Based on rural household survey data in Taipusi County as a case site ofecologically-vulnerable areas in North China, we firstly classify farm households into four types according to the proportion of non-farm income in total income, and then compare their agricultural land use patterns to empirically examine the impacts of part-time farming on agricultural land use in this area. The results suggest that non-farming households rent out all their land and give up farming, and this satisfies the expectation of other households to expand land area. The crop planting structure was not significantly different among the households, which reflected the farmers＇ will to pursuit labor productivity. Part-time farming households invest more capital and materials than full-time faming households because the income derived from non-farm employment relaxes the financial constraint of households. However, the amount of labor input of part-time farming households tends to be less, and farming practices are dominated by the elderly, female and laborers withrelative low educations.Yields of crops and the benefit of agricultural land use incline to reduce, which suggest that the potential of land use productivity is more elastic to labor inputs than capital inputs in the study area.展开更多
This paper focuses on the design of fixtures for NP2 and NP4 cylinder heads on a horizontal machining center of flexible machining automatic lines.It began with an analysis of the diagrams of part processing and worki...This paper focuses on the design of fixtures for NP2 and NP4 cylinder heads on a horizontal machining center of flexible machining automatic lines.It began with an analysis of the diagrams of part processing and working procedure which formed the basis for the design of the processing technology scheme,a selection of suitable machine tools,and the setting of processing parameters.Fixtures tailored to the chosen machine tools were then designed to meet the processing requirements.Additional aspects of the project included the design of part drawings,calculation of working time quota,design of auxiliary guides,support clamping,and hydraulic circuits,all aimed at fulfilling practical production requirements.展开更多
基金the National Natural Science Foundation of China (Grant no. 40971062)
文摘Part-time farming has been increasing steadily in China. It is currently the largest segment among all the farm sectors in the country. Based on rural household survey data in Taipusi County as a case site ofecologically-vulnerable areas in North China, we firstly classify farm households into four types according to the proportion of non-farm income in total income, and then compare their agricultural land use patterns to empirically examine the impacts of part-time farming on agricultural land use in this area. The results suggest that non-farming households rent out all their land and give up farming, and this satisfies the expectation of other households to expand land area. The crop planting structure was not significantly different among the households, which reflected the farmers＇ will to pursuit labor productivity. Part-time farming households invest more capital and materials than full-time faming households because the income derived from non-farm employment relaxes the financial constraint of households. However, the amount of labor input of part-time farming households tends to be less, and farming practices are dominated by the elderly, female and laborers withrelative low educations.Yields of crops and the benefit of agricultural land use incline to reduce, which suggest that the potential of land use productivity is more elastic to labor inputs than capital inputs in the study area.
文摘This paper focuses on the design of fixtures for NP2 and NP4 cylinder heads on a horizontal machining center of flexible machining automatic lines.It began with an analysis of the diagrams of part processing and working procedure which formed the basis for the design of the processing technology scheme,a selection of suitable machine tools,and the setting of processing parameters.Fixtures tailored to the chosen machine tools were then designed to meet the processing requirements.Additional aspects of the project included the design of part drawings,calculation of working time quota,design of auxiliary guides,support clamping,and hydraulic circuits,all aimed at fulfilling practical production requirements.
