Forward extrusion experiments of as-cast AZ31 magnesium alloy were conducted at different temperatures and different extrusion ratios using the as-cast billets with and without homogenizing treatment.The mechanical pr...Forward extrusion experiments of as-cast AZ31 magnesium alloy were conducted at different temperatures and different extrusion ratios using the as-cast billets with and without homogenizing treatment.The mechanical properties of pre-and post-extrusion of the two kinds of billets were investigated.Experimental results show that the mechanical properties of post-extrusion of the two kinds of billets all are obviously improved compared with those of pre-extrusion.The elongation of post-extrusion using the billet with homogenizing is higher than that without homogenizing,but the tensile strength is lower than that without homogenizing.When the extrusion ratio increases,the elongation and tensile strength of post-extrusion of two kinds of billets all will increase obviously.When the extrusion temperature of billet without homogenizing increases,the tensile strength of post-extrusion will decrease obviously and the elongation of post-extrusion will change to a small extent.For the billet with homogenizing,the tensile strength of post-extrusion will decrease in some sort when extrusion temperature increases.展开更多
The place of the oil palm, Elaeis guineensis Jacq., in the market for fats of vegetable commodities makes it a strategic plant which requires continuous improvement. In this context, it seems appropriate to better des...The place of the oil palm, Elaeis guineensis Jacq., in the market for fats of vegetable commodities makes it a strategic plant which requires continuous improvement. In this context, it seems appropriate to better describe the effects of the Sh gene in the developing fruit. This study aims to set a benchmark for the development of the seed in the natural palm （Elaeis guineensis var. dura） Thus the growth and development of the two major seed tissues were monitored every two weeks from pollination to maturity of the fruit. The results show that the endosperm is still liquid six weeks after pollination. It then begins an accelerated development which leads it, 11 weeks later, to completely fill the seed cavity, with an average mass of 0.81 g. This mass remains stable until the maturity of the fruit. The embryo is only visible when the endosperm is gelatinous, around 70 DPP （days post-pollination）. It then has an average length of 1.00 mm. At 126 DPP, the embryo has finished growing and measures 2.82 mm on average. This length also remains stable until 168 DPP （3.04 mm）. In perspective, a detailed follow-up of the development of the zygote from the pollination to 100 DPP is proposed. In parallel, the analysis of the chemical composition of the endosperm between 100 DPP and 168 DPP is necessary. These two complementary studies will allow to better specifying the benchmark of seed development in Elaeis guineensis var. dura.展开更多
In this paper,based on the adjacency matrix of the network and its powers,the formulas are derived for theshortest path and the average path length,and an effective algorithm is presented.Furthermore,an example is pro...In this paper,based on the adjacency matrix of the network and its powers,the formulas are derived for theshortest path and the average path length,and an effective algorithm is presented.Furthermore,an example is providedto demonstrate the proposed method.展开更多
基金Projects(50605059,50735005)supported by the National Natural Science Foundation of ChinaProject(2009081012)supported by International Cooperation of Shanxi Province,ChinaProject(20090319ZX)supported by Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province,China
文摘Forward extrusion experiments of as-cast AZ31 magnesium alloy were conducted at different temperatures and different extrusion ratios using the as-cast billets with and without homogenizing treatment.The mechanical properties of pre-and post-extrusion of the two kinds of billets were investigated.Experimental results show that the mechanical properties of post-extrusion of the two kinds of billets all are obviously improved compared with those of pre-extrusion.The elongation of post-extrusion using the billet with homogenizing is higher than that without homogenizing,but the tensile strength is lower than that without homogenizing.When the extrusion ratio increases,the elongation and tensile strength of post-extrusion of two kinds of billets all will increase obviously.When the extrusion temperature of billet without homogenizing increases,the tensile strength of post-extrusion will decrease obviously and the elongation of post-extrusion will change to a small extent.For the billet with homogenizing,the tensile strength of post-extrusion will decrease in some sort when extrusion temperature increases.
文摘The place of the oil palm, Elaeis guineensis Jacq., in the market for fats of vegetable commodities makes it a strategic plant which requires continuous improvement. In this context, it seems appropriate to better describe the effects of the Sh gene in the developing fruit. This study aims to set a benchmark for the development of the seed in the natural palm （Elaeis guineensis var. dura） Thus the growth and development of the two major seed tissues were monitored every two weeks from pollination to maturity of the fruit. The results show that the endosperm is still liquid six weeks after pollination. It then begins an accelerated development which leads it, 11 weeks later, to completely fill the seed cavity, with an average mass of 0.81 g. This mass remains stable until the maturity of the fruit. The embryo is only visible when the endosperm is gelatinous, around 70 DPP （days post-pollination）. It then has an average length of 1.00 mm. At 126 DPP, the embryo has finished growing and measures 2.82 mm on average. This length also remains stable until 168 DPP （3.04 mm）. In perspective, a detailed follow-up of the development of the zygote from the pollination to 100 DPP is proposed. In parallel, the analysis of the chemical composition of the endosperm between 100 DPP and 168 DPP is necessary. These two complementary studies will allow to better specifying the benchmark of seed development in Elaeis guineensis var. dura.
基金National Natural Science Foundation of China under the Key Project under Grant Nos.10635040 and 60774073the Natural Science Foundation of Jiangsu Province of China under Grant No.BK2007075
文摘In this paper,based on the adjacency matrix of the network and its powers,the formulas are derived for theshortest path and the average path length,and an effective algorithm is presented.Furthermore,an example is providedto demonstrate the proposed method.
