等温输油管线设计技术经济分析

本文从费用最省的角度出发,建立了计算等温输油管线最优技术参数的数学模型,并给出了数学模型的求解方法。     

Integrated scheduling and inventory management of an oil products distribution system

The oil supply chain is facing new challenges due to emerging issues such as new alternative energy sources, oil sources scarcity, and price variability with high impact on demand and production and profit margins reduction. Additionally, the existence of large, complex and world wide spread businesses implies a complex system to be managed where distribution can be seen as one of the key areas that needs to be efficiently and effectively managed. Different types of distribution modes characterize the oil supply chain where the pipeline mode is one of the most complex to operate when having multiproduct characteristics. This paper addresses the planning of a generic oil derivatives transportation system characterized by a multiproduct pipeline that connects a single refinery to a storage tank farm. Two alternative mixed integer linear programming models (MILP) that aim to attain a set of planning objectives such as fulfilling costumers’ demands (which is mandatory) while minimizing the medium flow rate are developed. Additionally, final inventory levels are avoided to be excessively low. A real world scenario of a Portuguese company is used to validate and compare the two alternative MILP models developed in this paper.     

中国西部天然气产业经济政策研究

根据我国天然气产业发展的实际情况 ,借鉴国外天然气产业在项目投资、税收、价格政策以及管理等方面的成功经验 ,分析我国天然气工业发展所面临的问题 ,对我国西部大开发标志性工程项目“西气东输”工程建设和运营的相关经济政策进行了探讨 ,提出了有益于我国天然气工业经济发展的一些具体政策和措施。     

Addressing the School-to-Prison Pipeline: Examining Micro- and Macro-Level Variables that Affect School Disengagement and Subsequent Felonies

Abstract

This study examines the School-to-Prison Pipeline (STPP) by identifying individual legal and extra-legal variables and school-level factors that predict juvenile/criminal justice involvement using 2006–2012 matched data from education and justice systems (n?=?21,457). The role of school disengagement is also assessed, measuring unexcused absences that follow suspensions in the previous academic year. For the court-involved subsample (n?=?7349), after controlling for student behavior, demographic, and school-level factors; extra-legal racial differences remain a significant factor in determining higher counts of felonies with African American and Multi-racial students at increased likelihood (1.65 and 1.86 times, respectively for the higher latent class) of juvenile/criminal justice involvement as compared with White students. And, although White students were found to either be more disengaged or equally disengaged when compared with students of color, sharp differences in criminal justice involvement and outcomes exist by race/ethnicity. These findings suggest that addressing the STPP will require future research and focus on more than individual-level behaviors (school disengagement and school-based offenses) and attention to the impact of extra-legal variables and systemic implicit bias.     

从里海“BTC”石油管道建成后看中国——哈萨克斯坦石油管线建设

里海“BTC”石油运输管道的建成有力地改变了里海、中亚地区的地缘政治、经济。从其管道建设的走向上来看,以美国为首的西方国家和俄罗斯为争夺里海的地缘政治的角逐愈发明显,这条管道对于中哈石油的管道建设,以及以后的石油运输都会带来很大影响,作为中国的石油战略必须为此加强预见性的工作。