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This paper rates a series of factors that managers believe influence the on‐time delivery of rail transportation for shippers of grain and grocery products. These variables are empirically tested through a series of statistical techniques. On‐time performance is found to be dependent on a combination of route, situation, and patronage variables. Railroad efforts to reduce or simplify terminal operations are supported by the findings of this study. The feeling expressed by some distribution managers concerning the hopelessness of affecting on‐time performance is partially confirmed although several positive guidelines for action are offered. Finally, claims that larger carrier size yields better service are not supported by this study.
Air carriers and aircraft manufacturers are investing in technologies and strategies to reduce fuel consumption and associated emissions. This chapter reviews related…
Air carriers and aircraft manufacturers are investing in technologies and strategies to reduce fuel consumption and associated emissions. This chapter reviews related issues to assess airline fuel efficiency and offers various empirical evidences from our recent work that focuses on the U.S. domestic passenger air transportation system. We begin with a general presentation of four methods (ratio-based, deterministic frontier, stochastic frontier, and data envelopment analysis) and three perspectives for assessing airline fuel efficiencies, the latter covering consideration of only mainline carrier operations, mainline–subsidiary relations, and airline routing circuity. Airline fuel efficiency results in the short run, in particular the correlations of the results from using different methods and considering different perspectives, are discussed. For the long-term efficiency, we present the development of a stochastic frontier model to investigate individual airline fuel efficiency and system overall evolution between 1990 and 2012. Insight about the association of fuel efficiency with market entry, exit, and airline mergers is also obtained.
The purpose of this paper is to present a novel delay-bounded and power-efficient routing for in-network data aggregation, called DPIDA, which aims to ensure a compromise…
The purpose of this paper is to present a novel delay-bounded and power-efficient routing for in-network data aggregation, called DPIDA, which aims to ensure a compromise between the energy consumed during the collection of data sensed by a set of source sensor nodes and their timely delivery to the sink node.
Based on the ant-colony-optimization metaheuristic, the proposal establishes a routing structure that maximizes the number of overlapping routes and minimizes the total transmission power while ensuring delay-bounded paths and a symmetric transmission power assignment to reliably deliver the sensed data.
The proposal was extensively compared to two other known protocols regarding different keys factors. Simulation results, including topology snapshots, show the ability of DPIDA to ensure the energy–latency tradeoff. They also show the superiority of DPIDA compared to the two considered protocols.
This paper presents a novel ant-based protocol that uses in-network data aggregation and transmission power-adjustment techniques to conserve the energy of nodes while ensuring delay-bounded paths and a reliable deliverance of data which is ensured by providing a symmetric transmission power assignment.
The purpose of this paper is to examine whether or not driver life, carrier performance, and customer service can be improved as a result of the use of a technique called…
The purpose of this paper is to examine whether or not driver life, carrier performance, and customer service can be improved as a result of the use of a technique called yard‐stacking in the truckload trucking industry. The technique seeks to find ways to provide level freight availability during normal weekly cycles in an effort to seek improvement relative to all constituencies.
Simulation is used to examine the use of yard‐stacking on Fridays to provide additional freight on weekends, which is generally much less available than on weekdays. In this technique, before being dispatched on Friday for a long‐haul, a driver initially picks up a load to make a short “dray” move from the customer site to the carrier's closest terminal yard. During the weekend, another driver picks up the drayed load. In this research, we evaluate the potential of weekend yard‐stacking under a variety of scenarios.
The paper shows that a carrier's adaptation of weekend freight leveling can be beneficial to both trucking companies and their customers, while remaining relatively neutral to drivers.
Carriers may be able to utilize Friday yard‐stacking to improve their cost efficiency, driver satisfaction and customer performance.
This research extends the knowledge base of truckload freight imbalance problems. It was industrially motivated by J.B. Hunt Transport, Inc., one of the world's largest truckload carriers, who provided freight data and conceptual guidance.
The connectivity provided by full-service network carriers under the umbrella of airline alliances is increasingly challenged by the services of Middle Eastern airlines…
The connectivity provided by full-service network carriers under the umbrella of airline alliances is increasingly challenged by the services of Middle Eastern airlines via their own hubs, and the rise of new passenger strategies like self-connectivity. While these two developments can potentially benefit consumers with more services and lower fares, the rise of Middle East carriers has been met with opposition by EU and US airlines that call for increased protectionism. In addition, only a few airports in the world actively support self-connections. In this context, this study aims to investigate (1) the markets in which Middle East carriers exert a stronger dominance in terms of the number of passenger connections, (2) whether EU, US, or Asian hubs provide a competitive quality of connectivity in terms of travel time, and (3) whether a significant potential for self-connections is hidden at major airports worldwide. To that end, several datasets of passenger bookings (MIDT), airline schedules, and minimum connecting times between 2012 and 2015 are combined in a connections-building methodology that delivers six market-specific airport connectivity indicators for our benchmarking exercise. Our findings show that although European and some Asian hubs have lost traffic in global markets, they remain competitive from a quality perspective. US hubs have maintained their market share and competitive position. Finally, we identify the airports and airlines with the highest potential to provide self-connecting travel options, which can become an attractive new source of revenue for the parties involved.