In-transit perishable product inspection

We determine the value of monitoring perishable freight in-transit for a single vehicle traveling from an origin to a destination. We develop a computationally practical approach for determining the optimal expected cost function and an optimal policy, based on an infinite horizon partially observed Markov decision process model. Structural properties of the optimal expected cost function and optimal policy are determined. These results can lend insight when deciding whether to acquire the capacity to monitor freight status in transit and what actions to take, based on the data from the in-transit monitoring, that optimally increase expected supply chain productivity.     

清代食盐流通体制中“引岸制”之分析

清政府采取"引岸制"食盐运销体制,赋予一些商人食盐垄断权,商人因之获得暴利,国家只对盐商进行管理和征税,从而使财政得到保证,进而形成了官商相互勾结共分盐利的局面。"引岸制"虽然在最初满足了国家财政和商人逐利的目的,但最终的结果是食盐商品成本上升,价格高昂,流通阻滞,进而导致国家政治进一步衰败,法制进一步瓦解。     

优化物流运营效率下的交通运输规划模式探究

在前人研究的基础之上,对优化物流运营效率下的交通运输规划模式做了大体的介绍,分析了我国现阶段物流交通运输规划模式,指出其不足之处,然后对优化物流运营效率下的交通运输规划模式做出展望。     

物流运输运作成本控制研究分析——以某化工公司为例

从运输成本的构成入手,分析了影响运输成本因素、物流成本与运输成本之间的关系,在此基础之上,以上海某化工企业为例,分析研究了进行物流系统优化过程中运输成本控制的方法和采取的具体策略。     

探讨交通运输机械针对性维修策略与应用

根据当前我国交通运输机械针对性维修的整体发展状况,分析了我国交通运输机械维修的发展方向,从而进一步探讨了现代交通运输机械维修的策略和具体技术应用所遇到的挑战及总体发展趋势,并针对具体维修策略,提出一些关于交通运输机械针对性维修方面的具体措施和发展思路。     

Transportation rates and plant location in oligopolistic competition with sequential entry

This paper examines the impact of quantity-discounted transportation rates on location patterns of oligopolistic competition with sequential entry. When transportation rates are constant, Hwang and Mai (1990) show that the entrant locates at the same point as the existing firms if the production function exhibits constant returns to scale. The entrant will locate farther away from (closer to) the market than the existing firms do if the production function exhibits increasing (decreasing) returns to scale. This paper shows that Hwang and Mai's results need not hold when transportation rates are a function of quantity shipped and distance traveled.     

倏逝波在一维氧化硅亚微米波导线中传输特性的研究

[HTK]基于光学倏逝波原理的光纤或波导传感器是目前光学传感器领域的重要发展方向之一,而倏逝波在其中的传输特性是决定该类传感器敏感特性的关键因数.利用倏逝场理论分析了直径102～103nm的一维氧化硅亚微米光波导在其直径与外部介质(折射率)变化时倏逝波的穿透深度.实验结果表明,亚微米光波导的传输损耗将随着波导尺寸和外部环境折射率的变化而变化,倏逝波的传输方式非常适用于高灵敏度探测,可应用于光化学传感器和生物化学传感器的设计.     

Evolution of the international air transportation country network from 2002 to 2013

In this research, we analyze the evolution of the international air transportation country network from 2002 to 2013 with two perspectives: The network’s physical topology and the functional network with traffic information. Our analysis shows that the network is scale-free and has the small-world property. The evolution of triadic properties suggests that the network gears towards symmetric, transitive closure. We find that United States, Great Britain, and France are critical from both perspectives; Surprisingly, South Africa is particularly critical from topological point of view. Furthermore, topological and functional criticality are highly correlated to the GDP of a country.     

How air transport connects the world – A new metric of air connectivity and its evolution between 1990 and 2012

To understand as to how scheduled air services link a region to other markets, we develop connectivity and hub centrality metrics. These metrics measure the quality of all scheduled air services in terms of frequency, detours, layover time and destination quality using a valuation scale being derived from observed passenger behavior. By computing yearly scores for 1990 to 2012, we analyze the geography of and trends in worldwide connectivity and hub centrality. While we observe significant growth of aggregate connectivity, the trends are heterogeneous with regard to the type of connectivity as well as time and location.     

论铁路货运向现代物流转变

随着我国高铁的快速建设，以及铁路货运机制的不断改革，铁路货运发展现代物流存在非常好的机遇。铁路运输为了提高市场份额，适应市场需求，应采取众多改革方针。通过运用SWOT方法，对我国铁路货运发展现代物流进行了分析，指出了其存在的优势、劣势、机遇与威胁，并提出铁路货运在发挥自身优势、优化货运组织的同时，要充分利用路网资源，进一步加强铁路货运改革，优化两端运输组织，完善“门到门”物流运输，积极拓展铁路货运增值业务，大力发展协同运输，为铁路货运发展现代物流提供有力保证。