A service station plays an important role in the petroleum product distribution terminal. With the increase in petroleum consumption in China, the inventory theory should be applied in the stock control of service st...A service station plays an important role in the petroleum product distribution terminal. With the increase in petroleum consumption in China, the inventory theory should be applied in the stock control of service stations. In this paper the inventory theory including its background and characteristics is introduced. At the same time, the application of the theory in some trades today, especially in petroleum trade, is analyzed. Then (s, S) stochastic model is advanced, which is established according to the principle of operational research and, based on this model, a sample is given, which discusses the details of application in the stock control of service stations. The sample is simplified but implies the validity of the model in optimizing the storage of petroleum products in the market.展开更多
In order to minimize the total cost of the retailer, an optimal replenishment cycle is studied by considering the deteriorating product, two-level trade credits, the limited storage capacity of their own warehouse and...In order to minimize the total cost of the retailer, an optimal replenishment cycle is studied by considering the deteriorating product, two-level trade credits, the limited storage capacity of their own warehouse and credit-linked order quantity simultaneously. A two-echelon supply chain model, which consists of a supplier and a retailer, is established. Then, the retailer＇s optimal replenishment cycle under all the cases are derived by using the optimization theory and method. On the basis of these, the effects of system parameters on the optimal replenishment cycle are examined by using the numerical studies. The results show that, when the retailer＇s trade credit period is longer （shorter） than the customer＇s trade credit period, the optimal replenishment cycle should he increased （decreased） as the retailer＇s trade credit period increases; if the minimum order quantity is high （low）, the optimal replenishment cycle should be increased （not changed） as the minimum order quantity increases.展开更多
Mexico is a large producer of table grape （Vitis vinifera L.） and therefore it is important to develop protocols to store the grape varieties germplasm. The objective of the present work was to design a protocol for...Mexico is a large producer of table grape （Vitis vinifera L.） and therefore it is important to develop protocols to store the grape varieties germplasm. The objective of the present work was to design a protocol for the cryopreservation by vitrification of zygotic embryos of V. vinifera cv. ＂Red Globe＂ and evaluate possible epigenetics changes. The plant vitrification solution 2 （PVS2） was utilized before the utilization of liquid nitrogen （LN）. The effect of this protocol on embryo viability was tested by the triphenyl-tetrazolium chloride solution, as well as by the in vitro development of grape embryos into plantlet. A cDNA expression library of grape zygotic embryos was created to isolate expressed sequence tags of several DNA methyltrasferases. Gene expression of domains rearranged methyltransferase type 1 （DMR1） and DNA （cytosine-5）-methyltransferase 1 （MET1-2） isozymes was analyzed by quantitative reverse transcriptase PCR. The optimal conditions for vitrification were 10 min in 50% PVS2, followed by I0 min in 100% PVS2. Under these conditions, about 30% of plantlet was obtained from embryos after cryopreservation. It was recorded a reduction in the MET1-2 gene expression, which plays a role in the maintenance of DNA methylation. It is possible to cryopreserve viable grape zygotic embryos, although the treatment seems to induce alterations in the normal DNA methylation pattern of the zygotic embryo genome.展开更多
文摘A service station plays an important role in the petroleum product distribution terminal. With the increase in petroleum consumption in China, the inventory theory should be applied in the stock control of service stations. In this paper the inventory theory including its background and characteristics is introduced. At the same time, the application of the theory in some trades today, especially in petroleum trade, is analyzed. Then (s, S) stochastic model is advanced, which is established according to the principle of operational research and, based on this model, a sample is given, which discusses the details of application in the stock control of service stations. The sample is simplified but implies the validity of the model in optimizing the storage of petroleum products in the market.
基金The National Natural Science Foundation of China(No.71371003,71001025,71390333)
文摘In order to minimize the total cost of the retailer, an optimal replenishment cycle is studied by considering the deteriorating product, two-level trade credits, the limited storage capacity of their own warehouse and credit-linked order quantity simultaneously. A two-echelon supply chain model, which consists of a supplier and a retailer, is established. Then, the retailer＇s optimal replenishment cycle under all the cases are derived by using the optimization theory and method. On the basis of these, the effects of system parameters on the optimal replenishment cycle are examined by using the numerical studies. The results show that, when the retailer＇s trade credit period is longer （shorter） than the customer＇s trade credit period, the optimal replenishment cycle should he increased （decreased） as the retailer＇s trade credit period increases; if the minimum order quantity is high （low）, the optimal replenishment cycle should be increased （not changed） as the minimum order quantity increases.
文摘Mexico is a large producer of table grape （Vitis vinifera L.） and therefore it is important to develop protocols to store the grape varieties germplasm. The objective of the present work was to design a protocol for the cryopreservation by vitrification of zygotic embryos of V. vinifera cv. ＂Red Globe＂ and evaluate possible epigenetics changes. The plant vitrification solution 2 （PVS2） was utilized before the utilization of liquid nitrogen （LN）. The effect of this protocol on embryo viability was tested by the triphenyl-tetrazolium chloride solution, as well as by the in vitro development of grape embryos into plantlet. A cDNA expression library of grape zygotic embryos was created to isolate expressed sequence tags of several DNA methyltrasferases. Gene expression of domains rearranged methyltransferase type 1 （DMR1） and DNA （cytosine-5）-methyltransferase 1 （MET1-2） isozymes was analyzed by quantitative reverse transcriptase PCR. The optimal conditions for vitrification were 10 min in 50% PVS2, followed by I0 min in 100% PVS2. Under these conditions, about 30% of plantlet was obtained from embryos after cryopreservation. It was recorded a reduction in the MET1-2 gene expression, which plays a role in the maintenance of DNA methylation. It is possible to cryopreserve viable grape zygotic embryos, although the treatment seems to induce alterations in the normal DNA methylation pattern of the zygotic embryo genome.
