将李群理论用于金融问题中出现的数学模型的微分方程,研究了Zero-Coupon bond pricing模型.求出了该模型的单参数李点对称及它相应的群伴随表达式,由此求得该模型允许的一维李群的子代数的最优系统并且利用最优系统构造该模型相应的微...将李群理论用于金融问题中出现的数学模型的微分方程,研究了Zero-Coupon bond pricing模型.求出了该模型的单参数李点对称及它相应的群伴随表达式,由此求得该模型允许的一维李群的子代数的最优系统并且利用最优系统构造该模型相应的微分方程的一些特殊的不同类的闭解.展开更多
Issuing coupons is a common marketing tool for business to increase demand and create profits. Mooncake coupons are among the most popular coupons in China. However, such popularity has sparked heated debate nationwid...Issuing coupons is a common marketing tool for business to increase demand and create profits. Mooncake coupons are among the most popular coupons in China. However, such popularity has sparked heated debate nationwide. In this regard,the paper studies the phenomenon through game theory model that deals with the relationship between mooncake makers,as for their efforts in balancing the number of coupons issued and the amount of mooncakes actually produced,and scalpers,as for the repurchase discount they enjoy, to finally bring a win-win situation. For mooncake makers to print more coupons than their actual production capacities while keeping the risks under control,a prior agreement should be made with the scalpers to set certain rules,among which the variable k is particularly important.展开更多
The effect of the presence of Ni in solution as Ni-EDTA complex in lithiated water at roon temperature and pH 10.5 on the formation of ferrite coating on carbon steel surface was studie in an autoclave at 523 K for 12...The effect of the presence of Ni in solution as Ni-EDTA complex in lithiated water at roon temperature and pH 10.5 on the formation of ferrite coating on carbon steel surface was studie in an autoclave at 523 K for 12 days at different Ni concentrations with varying amounts of free EDTA. The Ni-ferrite coating was characterized by XRD, SIMS and XPS and also bulk chemical analysis by AAS and UV-visible spectrophotometer. The chemical composition of Ni-ferrite coating showed variation with depth acro5s solution-oxide interface to oxide-metal interface.The content of Ni in the oxide coating on the surface near solution-oxide intedece was found to be higher than the average Ni content estimated by analysis after descaling the coating展开更多
Commercially processed foods become contaminated with Listeria monocytogenes in post-processing environments where favorable conditions help the bacteria thrive. The US Food and Drug Administration has approved Lauric...Commercially processed foods become contaminated with Listeria monocytogenes in post-processing environments where favorable conditions help the bacteria thrive. The US Food and Drug Administration has approved Lauric arginate (LAE) as generally recognized as safe (GRAS) for certain food applications. This study evaluated the efficacy of Mirenat-N (LAE dissolved in food-grade propylene glycol) against L. monocytogenes on food contact surfaces. A three-strain cocktail of L. monocytogenes was used to inoculate 24 polished stainless steel coupons with three treatments, 100 ppm and 200 ppm solutions of LAE and water (control);two sub-treatments of high (6 log CFU/ml) and low (4 log CFU/ml) inoculum levels;and two contact times of 5 and 15 min. Attached bacteria were dislodged by vortexing coupons for 1 min with 20 g of 3-mm solid glass beads in 10 ml of 0.1% peptone diluent, and bacterial populations were calculated by plating onto modified oxford medium (MOX) and thin agar layer MOX (TALMOX). The 100 ppm treatment showed average reductions of 1.38 and 2.57 log CFU/coupon at the low inoculum level and 0.37 and 0.62 log CFU/coupon at high inoculum levels, after 5 and 15 min exposure, respectively. For 200 ppm at the high inoculum level, 1.23 and 1.88 log CFU/coupon reductions were seen for 5 and 15 min, respectively;the low inoculum level at 5 and 15 min exposure showed reductions of ≤1.5 log CFU/coupon. The 100 ppm LAE treatment was more effective at low inoculum levels for 5 and 15 min contact times and may be used to control low levels of contamination of L. monocytogenes on food contact surfaces.展开更多
Heat exchanger is an important equipment used in process industries for cooling and heating purposes. Its design configuration which involves the flow of cold and hot fluids within the exchanger subjects it to corrosi...Heat exchanger is an important equipment used in process industries for cooling and heating purposes. Its design configuration which involves the flow of cold and hot fluids within the exchanger subjects it to corrosion attack. The article utilized the principle of mass and energy conservation in the development of weight and temperature models to study the effect of corrosion on mild steel coupon inside the exchanger containing water and Mono ethanol amine (MEA). The models developed were resolved analytically using Laplace Transform and simulated using Excel as simulation tool and data obtained from experiment in the laboratory to obtain profiles of weight loss and temperature as a function of time. The weight loss and performance of mild steel under various corrosive conditions were examined which indicates the effect of corrosion on the mild steel heat exchanger in water and MEA media. The result shows that water is more corrosive than MEA at higher temperatures and at lower temperatures of 35°C and 1 atm, MEA has inhibitive properties than water as indicated by the weight loss result with time. The comparative analysis between the results obtained from the model simulation and experimental results shows that the result obtained from the model is more reliable and demonstrated better performance characteristics as it clearly shows mild steel heat exchanger experiences more corrosive effect in water medium than MEA at higher temperatures. And at lower temperatures, MEA becomes more inhibitive and less corrosive than water. The model simulation results correlate with various literatures and hence, it is valid for future referencing.展开更多
基金National Natural Science Foundation of China(No.71572110)
文摘Issuing coupons is a common marketing tool for business to increase demand and create profits. Mooncake coupons are among the most popular coupons in China. However, such popularity has sparked heated debate nationwide. In this regard,the paper studies the phenomenon through game theory model that deals with the relationship between mooncake makers,as for their efforts in balancing the number of coupons issued and the amount of mooncakes actually produced,and scalpers,as for the repurchase discount they enjoy, to finally bring a win-win situation. For mooncake makers to print more coupons than their actual production capacities while keeping the risks under control,a prior agreement should be made with the scalpers to set certain rules,among which the variable k is particularly important.
文摘The effect of the presence of Ni in solution as Ni-EDTA complex in lithiated water at roon temperature and pH 10.5 on the formation of ferrite coating on carbon steel surface was studie in an autoclave at 523 K for 12 days at different Ni concentrations with varying amounts of free EDTA. The Ni-ferrite coating was characterized by XRD, SIMS and XPS and also bulk chemical analysis by AAS and UV-visible spectrophotometer. The chemical composition of Ni-ferrite coating showed variation with depth acro5s solution-oxide interface to oxide-metal interface.The content of Ni in the oxide coating on the surface near solution-oxide intedece was found to be higher than the average Ni content estimated by analysis after descaling the coating
文摘Commercially processed foods become contaminated with Listeria monocytogenes in post-processing environments where favorable conditions help the bacteria thrive. The US Food and Drug Administration has approved Lauric arginate (LAE) as generally recognized as safe (GRAS) for certain food applications. This study evaluated the efficacy of Mirenat-N (LAE dissolved in food-grade propylene glycol) against L. monocytogenes on food contact surfaces. A three-strain cocktail of L. monocytogenes was used to inoculate 24 polished stainless steel coupons with three treatments, 100 ppm and 200 ppm solutions of LAE and water (control);two sub-treatments of high (6 log CFU/ml) and low (4 log CFU/ml) inoculum levels;and two contact times of 5 and 15 min. Attached bacteria were dislodged by vortexing coupons for 1 min with 20 g of 3-mm solid glass beads in 10 ml of 0.1% peptone diluent, and bacterial populations were calculated by plating onto modified oxford medium (MOX) and thin agar layer MOX (TALMOX). The 100 ppm treatment showed average reductions of 1.38 and 2.57 log CFU/coupon at the low inoculum level and 0.37 and 0.62 log CFU/coupon at high inoculum levels, after 5 and 15 min exposure, respectively. For 200 ppm at the high inoculum level, 1.23 and 1.88 log CFU/coupon reductions were seen for 5 and 15 min, respectively;the low inoculum level at 5 and 15 min exposure showed reductions of ≤1.5 log CFU/coupon. The 100 ppm LAE treatment was more effective at low inoculum levels for 5 and 15 min contact times and may be used to control low levels of contamination of L. monocytogenes on food contact surfaces.
文摘Heat exchanger is an important equipment used in process industries for cooling and heating purposes. Its design configuration which involves the flow of cold and hot fluids within the exchanger subjects it to corrosion attack. The article utilized the principle of mass and energy conservation in the development of weight and temperature models to study the effect of corrosion on mild steel coupon inside the exchanger containing water and Mono ethanol amine (MEA). The models developed were resolved analytically using Laplace Transform and simulated using Excel as simulation tool and data obtained from experiment in the laboratory to obtain profiles of weight loss and temperature as a function of time. The weight loss and performance of mild steel under various corrosive conditions were examined which indicates the effect of corrosion on the mild steel heat exchanger in water and MEA media. The result shows that water is more corrosive than MEA at higher temperatures and at lower temperatures of 35°C and 1 atm, MEA has inhibitive properties than water as indicated by the weight loss result with time. The comparative analysis between the results obtained from the model simulation and experimental results shows that the result obtained from the model is more reliable and demonstrated better performance characteristics as it clearly shows mild steel heat exchanger experiences more corrosive effect in water medium than MEA at higher temperatures. And at lower temperatures, MEA becomes more inhibitive and less corrosive than water. The model simulation results correlate with various literatures and hence, it is valid for future referencing.
