In this paper, the relationship model between the oil volume and the vertically tilting parameter (α), the horizontally tilting parameter (β) and the displayed height of oil (h*) is first constructed with the tilted...In this paper, the relationship model between the oil volume and the vertically tilting parameter (α), the horizontally tilting parameter (β) and the displayed height of oil (h*) is first constructed with the tilted oil tank. Then, based on the data of the oil output volume at different time of day, an optimization model of oil-volume marking with tilted oil tank is established. Finally, parameters α = 2.2° and β = 3.05° are estimated by using nonlinear least squares method and the marking number of the tank-volume meter is given.展开更多
This study explores the reasons underlying the frequent appearance of ＂marking problem＂ during the production of double-walled copper-brazed steel tubes. To this end, we compared two types of copper-coated steel str...This study explores the reasons underlying the frequent appearance of ＂marking problem＂ during the production of double-walled copper-brazed steel tubes. To this end, we compared two types of copper-coated steel strips, of which one has almost no problem during production, whereas the other has higher number of incidences of ＂marking problem＂. We analyzed the chemical composition,mechanical properties,the cross-sectional metallographs, and surface quality of the trimmed edge in both types of specimen. After the roll forming process, the bonding condition between the steel layers of the tubes before and after brazing process has also been examined. Results indicate that the chemical composition and mechanical properties of the two kinds of strips are similar; however, the edge quality of the trimmed strips is significantly different. It is believed that the irregular shape of the edge portions in the strips will be more pronounced during the bevel treatment. Consequently, smooth and tight seams cannot be guaranteed by such uneven beveled edges,which lead to higher number of incidences of ＂marking problem＂ during production.展开更多
As one of America’s first and foremost realists and humorist,Mark Twain,usually wrote aout his own personal experiences and things he knew about from firsthand experience.Among his books,The Adventures of Huckleberry...As one of America’s first and foremost realists and humorist,Mark Twain,usually wrote aout his own personal experiences and things he knew about from firsthand experience.Among his books,The Adventures of Huckleberry Finn has been considered the greatest one.In this paper I would argue that the Adventures of Huckleberry Finn is not merely a child’s story.It’s a book for the discerning adult.twain gives his young hero very adult problems.Actually,what are the adult problems of the young hero?What does it implied behind Huck’s adventures? This article aims to answer these questions and give more and deep analysis of Huck’s advetures.展开更多
1 引言
Petri网理论是由联邦德国的Carl Adam Petri于1962年在其博士论文中提出的一种建模方法.最初的网理论称为条件/事件网(CE-nets).在随后的几年中,人们对新的网模型、网的基本概念及分析方法等进行了大量的研究.其中最有影响的是位...1 引言
Petri网理论是由联邦德国的Carl Adam Petri于1962年在其博士论文中提出的一种建模方法.最初的网理论称为条件/事件网(CE-nets).在随后的几年中,人们对新的网模型、网的基本概念及分析方法等进行了大量的研究.其中最有影响的是位置/变迁网(PT-nets),PT-nets后来命名为Petri网(Petri Net).这些早期的网模型在理论上都归结为基本网(EN-nets).研究者通过对PT-nets进行了扩展,在网中增加了变迁的优先级、时间延迟、全程变量等一些概念以满足解决实际应用建模的具体要求.展开更多
文摘In this paper, the relationship model between the oil volume and the vertically tilting parameter (α), the horizontally tilting parameter (β) and the displayed height of oil (h*) is first constructed with the tilted oil tank. Then, based on the data of the oil output volume at different time of day, an optimization model of oil-volume marking with tilted oil tank is established. Finally, parameters α = 2.2° and β = 3.05° are estimated by using nonlinear least squares method and the marking number of the tank-volume meter is given.
文摘This study explores the reasons underlying the frequent appearance of ＂marking problem＂ during the production of double-walled copper-brazed steel tubes. To this end, we compared two types of copper-coated steel strips, of which one has almost no problem during production, whereas the other has higher number of incidences of ＂marking problem＂. We analyzed the chemical composition,mechanical properties,the cross-sectional metallographs, and surface quality of the trimmed edge in both types of specimen. After the roll forming process, the bonding condition between the steel layers of the tubes before and after brazing process has also been examined. Results indicate that the chemical composition and mechanical properties of the two kinds of strips are similar; however, the edge quality of the trimmed strips is significantly different. It is believed that the irregular shape of the edge portions in the strips will be more pronounced during the bevel treatment. Consequently, smooth and tight seams cannot be guaranteed by such uneven beveled edges,which lead to higher number of incidences of ＂marking problem＂ during production.
文摘As one of America’s first and foremost realists and humorist,Mark Twain,usually wrote aout his own personal experiences and things he knew about from firsthand experience.Among his books,The Adventures of Huckleberry Finn has been considered the greatest one.In this paper I would argue that the Adventures of Huckleberry Finn is not merely a child’s story.It’s a book for the discerning adult.twain gives his young hero very adult problems.Actually,what are the adult problems of the young hero?What does it implied behind Huck’s adventures? This article aims to answer these questions and give more and deep analysis of Huck’s advetures.
