•A convex closed-form mathematical programming model is proposed based on queueing theory to minimize CO2 emission by optimizing the number of quay cranes (QCs).•The analytical solution of the number ...of QCs is obtained by the proposed model.•It is found that the optimal number of QCs increases with the expected arrival rate of AGVs and the mean fuel consumption per AGV per hour, but decreases with the mean queue service rate of QCs and the electricity consumption per QC per hour.
Quay cranes (QCs) play a significant role in CO2 emission of the operations of global supply chains, since huge global container traffic requires a considerable number of handing operations of QCs. The traditional studies of QC assignment mainly aim to investigate the scheduling efficiency of QCs and seldom touch on CO2 emission or other green transportation objectives and the resulting models are normally mixed-integer programming (MIP) problems and solved by heuristic algorithms. In this paper, a convex mathematical programming model is proposed for the QC assignment problem, in which the queueing theory is used to model the queueing behavior of automatic guided vehicles (AGVs). The objective of the proposed model is to minimize CO2 emission during an unloading process of containers from QCs to AGVs by optimizing the number of QCs. The analytical solution of the number of QCs is obtained to the proposed model. It is found that the optimal number of QCs increases with the expected arrival rate of AGVs and the mean fuel consumption per AGV per hour but it decreases with the mean queue service rate of QCs and the electricity consumption per QC per hour.
The global shipping industry still frequently faces the problems of low profitability and excessive capacity despite the claimed benefits of capacity sharing between alliance members. This paper ...investigates capacity sharing within shipping alliance members and its impacts on social welfare under stochastic demand. The dynamic game models constructed in this study examine four scenarios based on whether the alliance members share their surplus capacities and whether their pricing is flexible (their prices are determined before or after the demand realization). The results suggest that flexible pricing always harms the social welfare while capacity sharing improves the social welfare. Without capacity sharing, the government's subsidy or tax is needed when the carriers' service substitute degree is low or high, respectively. If the carriers agree with capacity sharing, the tax is needed under flexible pricing while neither subsidy nor tax is needed under the inflexible pricing. This paper provides explanations on the low profits of the shipping lines with their pricing and alliance strategies. Moreover, the policy implications identified in this study can provide support for governments to make their regulation on carriers.
This paper adopts a simple but valid value-at-risk (VaR) approach to measuring the risk in the dry bulk shipping market by means of Baltic Dry Index (BDI). To have a better understanding of the risk ...in the dry bulk shipping market, this paper uses the stock market and the crude oil market as two reference markets. Available rich datasets enable a non-parametric historical simulation experiment on the risk in the dry bulk shipping market. The bellwether phenomenon in the dry bulk shipping market is explored both qualitatively and quantitatively. The experiment indicates that the dry bulk shipping market becomes the riskiest one among the aforementioned markets after the Subprime Mortgage Crisis that started in the USA in the early 2008. Furthermore, this paper identifies the information transmission mechanisms between the dry bulk shipping market and the reference markets by employing a multivariate quantile model and an impulse-response method, and explores and compares risk spillover effects of the global stock market and the crude oil market on the dry bulk shipping market before and after the financial crisis. Results reveal that spillover effects between the referred markets change after the Subprime Mortgage Crisis in terms of intensity.
The operations of yard cranes, external trucks and internal trucks in a maritime container terminal have an important impact on the operational efficiency of the terminal. A multi-objective ...optimization model is formulated in this paper, with a novel truck-based partition strategy, for a multiple-yard-crane scheduling problem, whose objective is to minimize both total longitudinal distance of yard cranes and total waiting time of internal and external trucks. The proposed model solves the truck assignment subproblem and the yard crane routing subproblem simultaneously to figure out how the trucks are to be served in an optimal manner by each yard crane and the optimal rank of each truck by which each yard crane provides container handling services in order. The effectiveness of the integrated truck-based and block-based scheduling strategies is validated by comparing with the existing strategies. Both the integrated block-based and the integrated truck-based scheduling strategies balance the two conflicting objectives better than the prioritized scheduling strategy and the first-come-first-served scheduling strategy. Numerical experiments shows that the advantage of the two integrated strategies is related to the ratio of the number of yard cranes to the number of container blocks. Some implications for port operation policy are also discussed.
We form portfolios consisting of diverse quarterly forward freight agreement (FFA) contracts to maximize the market participant's expected utility. The empirical findings indicate that individual FFA ...returns display clear autocorrelation, seasonality, fat tail, and heteroscedasticity. The multivariate positively skewed t copula is suggested for constructing maximum utility FFA portfolios, implying that the constituent FFA returns exhibit higher correlations when they rise together. The out‐of‐sample trading strategy performance metrics and various robustness checks further indicate that the aforementioned copula performs best and robustly for all portfolios. These findings provide profound methodological and managerial implications for market participants to improve risk management.
Public transport passenger demand is inevitably made non-uniform because of spatial and temporal land use planning. This non-uniformity warrants the use of public transport operational strategies to ...attain operating efficiency. The optimization of these strategies is commonly being done from the operator perspective, and indirectly from the user perspective. However, the environmental perspective of these strategies, in terms of vehicle's emission, has not been investigated. This study proposed a methodology to analyze the benefits of using transit operational strategies to reduce operating cost and eventually also to reduce undesirable emissions. First, a strategy-based optimization model is established to minimize the number of transit vehicles required. Four candidate operational strategies are considered in this model, including full route operation (FRO), short turn, limited stop, and a combination of limited stop and short turn. Second, the pollutant emissions of transit vehicles are estimated by the MOVES emission model. The developed methodology is applied to a real life case study in Dalian, China. Results show that the use of operational strategies can not only significantly save the number of vehicles by 12.5%, but also reduce emissions of pollutants (i.e., CO2, HC, CO, NOx, PM2.5) by approximately 13%, compared with applying FRO strategy exclusively. In addition, both benefits can be further enhanced through the use of an efficient payment mode (e.g., off-board or contactless card) or improving bus performance in deceleration/acceleration as well as doors opening and closing at a stop.
Over the years many shipping lines have established terminal operation companies, with some set up as independent firms. However, port authorities and local governments have not always welcomed ...external investment and control with open arms. The economic implications and each stakeholder's best strategies remain unclear. This study develops an analytical model in order to study the effects of vertical integration, with a focus on shipping lines' investment in ports' capacity. Modelling results suggest that vertical integration between terminal operator and a shipping line leads to higher port capacity, port charge, market output and consumer surplus. It also reduces delay costs. All these results suggest that vertical integration can be an important source of synergy for the maritime industry. Although vertical integration increases the participating carrier's output at the expenses of non-integrating rival shipping firms, our numerical analysis suggests that the overall social welfare is likely to increase. Preliminary empirical tests confirm that vertically integrated ports handle more traffic volumes and are associated with better infrastructure and equipment. Therefore, port authorities and government regulators should carefully review the market competition status as well as port expansion plans.
•We conducted a quantitative analysis of intelligent SCA technology over the past 20 years using bibliometric methods and data portrait techniques and traced earlier literature for a systematic ...review.•We identified the hotspots and research frontiers of intelligent ship collision avoidance in maritime transportation.•We discussed the contributions, innovations, and trends of future research in intelligent ship collision avoidance.
With the increasing promotion of digital technology, safety issues faced by rush ships in the maritime industry have once again received attention. Ship collision avoidance (SCA) is not only a hot topic in the shipping industry but also an eye-catching issue in the development of intelligent ships. This paper provides a bibliometric and systematic overview of the literature on SCA to assist researchers in understanding the frontiers and recent trends of SCA. Based on the bibliographic portrait, a classification and grading study was conducted on the literature to provide a systematic review of it. A screening process was conducted on 851 relevant articles related to SCA and published in 2004–2023 in the Web of Science (WoS) database, and 526 highly relevant and high-quality papers were selected. Then, CiteSpace, VOSviewer software, and data visualization techniques were used to conduct a bibliographic portrait analysis on the selected papers. The evidence from these systematic literature reviews revealed the close collaboration relationships among researchers, research institutions, and countries or regions in the field of SCA studying shortly. Furthermore, the frontiers of the research on SCA were focused on three aspects, i.e. research subjects, technological methods, and novel algorithms in intelligent SCA. COLREG is a problem that must be considered in intelligent SCA. The future trends in intelligent SCA were explored and SCA technology was introduced from artificial intelligence (AI) so as to meet the safety requirement of maritime autonomous surface ships. AI algorithms such as machine learning and deep learning are key technologies for SCA. This research provides a theoretical basis and implementation directions of the research on SCA. The hybrid encounters between traditional ships and intelligent ships, as well as multi-ship encounters in narrow waterways, will be the focal points of attention in the future.
Drones are receiving popularity with time due to their advanced mobility. Although they were initially deployed for military purposes, they now have a wide array of applications in various public and ...private sectors. Further deployment of drones can promote the global economic recovery from the COVID-19 pandemic. Even though drones offer a number of advantages, they have limited flying time and weight carrying capacity. Effective drone schedules may assist with overcoming such limitations. Drone scheduling is associated with optimization of drone flight paths and may include other features, such as determination of arrival time at each node, utilization of drones, battery capacity considerations, and battery recharging considerations. A number of studies on drone scheduling have been published over the past years. However, there is a lack of a systematic literature survey that provides a holistic overview of the drone scheduling problem, existing tendencies, main research limitations, and future research needs. Therefore, this study conducts an extensive survey of the scientific literature that assessed drone scheduling. The collected studies are grouped into different categories, including general drone scheduling, drone scheduling for delivery of goods, drone scheduling for monitoring, and drone scheduling with recharge considerations. A detailed review of the collected studies is presented for each of the categories. Representative mathematical models are provided for each category of studies, accompanied by a summary of findings, existing gaps in the state-of-the-art, and future research needs. The outcomes of this research are expected to assist the relevant stakeholders with an effective drone schedule design.
•We investigate the manufacturers’ timing decisions to adopt green technology under the subsidy policies.•The policy design is a call option exercised by the government and constrained by the ...manufacturer’s IC and PC.•The optimal subsidy exhibits a stepwise structure depending on the demand promotion and the manufacturer’s effort cost.•ESP and OSP are equivalent under complete information.Under incomplete information, two policies lead to the same timing if the demand is high and ESP needs a larger budget.
In order to encourage manufacturers to replace traditional high-emission equipment with new ones powered by green technology, alternative regulations, notably equipment subsidy policy (ESP) and operation subsidy policy (OSP), have been proposed to align manufacturers’ decisions with governments’ objectives. This study investigates manufacturers’ timing decisions to adopt green technology under ESP and OSP. In our study the market demand is dynamically stochastic, and the certain demand promotion is observable only by the manufacturer and can be promoted by inserting costly effort. A principal-agent model is developed in which the regulation on the adoption timing is specified as a call option exercised by the government and constrained by the manufacturer's incentive compatibility (IC), participation constraint (PC), ex ante IC, and ex ante PC. We find that the optimal subsidy policies exhibit stepwise structures, which depend solely on the demand promotion under complete information, and on the demand promotion as well as the manufacturer's effort cost under incomplete information. The optimal ESP and OSP are equivalent under complete information. Under incomplete information, these two policies lead to the same adoption timing if the demand is high, although ESP may require a larger subsidy budget. Otherwise, ESP promotes earlier adoption than OSP.
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