•We investigate the ship routing and freight assignment problem for liner shipping.•The problem is formulated as a time-space network-based mathematical program.•A Lagrangian relaxation-based ...decomposition algorithm is proposed.•The proposed framework is empirically applied to a northern sea route (NSR) case.•Empirical results identify the factors that affect the practicability of NSR.
In recent years, the Northern Sea Route (NSR) has attracted significant attention with respect to liner shipping. In this research, we propose a general time-space network-based mathematical formulation to analyze the ship routing and freight assignment problem in liner shipping and apply it to NSR planning problem. To solve the resulting program, we propose a Lagrangian relaxation-based decomposition algorithm that facilitates the network features. Empirical results show that navigation skill, bunker price, delay penalty and service commitment are the primary factors that affect the NSR’s commercial practicability.
Long-term monitoring of sea turtle aggregations is critical for understanding the impacts of environmental changes on their population health and habitat suitability. Brunei Bay is a significant ...foraging ground for green turtles in the South China Sea. We analyzed the body size, hematology and body condition of green turtles for their health status in their foraging ground in Brunei Bay over a period of nine years (2011–2019). Additionally, we used mitochondrial DNA (mtDNA) to evaluate changes in the size and genetic composition of green turtle aggregations. Our findings revealed that the size composition of the green turtle population varied seasonally, but there were no significant temporal changes in genetic and size compositions. Hematology parameters and Fulton’s body condition index were consistent with those reported for apparently healthy green turtles. Furthermore, we found that blood reference intervals indicated the turtles were healthy. These results provide valuable baseline data for future comparisons with other foraging aggregations and for long-term monitoring of green turtles in Brunei Bay.
In recent years, the landscape ecological security of Xishuangbanna in southwest China has become an essential factor affecting the cross-border ecological security in South Asia and Southeast Asia. ...Based on the change of land use in Xishuangbanna, with the help of "3S" technology, landscape ecology theory, and gray prediction model, the spatial and developmental trends of landscape ecological security in Xishuangbanna from 1996-2030 could be determined. In more than 20 years, the woodland landscape area in Xishuangbanna decreased, and the fragmentation of construction land has increased overall. In 1996, the overall landscape ecological safety was good, with 63.5% of the total area of grade I and II. In 2003, the proportion of the grade I and grade II areas decreased, with landscape ecological security problems appearing. In 2010, the overall landscape ecological security area reached 74.5%, the largest proportion in more than 20 years. The grade V area accounted for only 9% and was mainly distributed on the border of Menghai County and central Jinghong City. In 2017, The grade IV and V areas was further increased, and the ecological security problem intensified. The prediction results showed that from 2023 to 2030, the regions of grades I and II increased, but the proportion of level V regions increased. Furthermore, the grade IV transformed to grade V rapidly, reaching its highest value in more than 20 years. From 1996 to 2030, the landscape ecological security space significantly evolved, showing an evident "east-south" trend in movement and eventually shifting to the southeast.
Agency theory suggests that managerial mischief may occur when the interests of owners and managers diverge and that a solution to this agency problem is alignment of owner and agent interests ...through agent compensation and equity ownership. We develop the theoretical concept of CEO return and measure and estimate financial alignment as the relationship between CEO and shareholder returns. Our results, based on this new conceptualization and corresponding measurement, suggest stronger alignment than reported in previous work. The magnitude of this alignment is associated with subsequent firm performance, but in ways not clearly articulated or tested in prior research.
•We measure the vulnerability of European air transport to major airport closures.•Our model relocates disrupted passengers to minimum-delay itineraries.•Results challenge the link between airport ...centrality and network damage.•Access to local surrogates and alliance overlap reduce airport criticality.•Inter-alliance cooperation can improve the quality of relocation.
This paper analyzes the vulnerability of the European air transport network to major airport closures from the perspective of the delays imposed to disrupted airline passengers. Using an MIDT dataset on passenger itineraries flown during February 2013, full-day individual closures of the 25 busiest European airports are simulated and disrupted passengers then relocated to minimum-delay itineraries. Aggregate delays are used to rank the criticality of each airport to the network, with the possibility of disaggregating the impact across geographical markets. The results provide useful reference values for the development of policies aimed at improving the resilience of air transport networks.
•Vehicle Automation and Communication Systems (VACS) are reviewed.•A VACS taxonomy is proposed from a motorway traffic management perspective.•VACS are classified regarding enabled/foreseen functions ...and level of autonomy.•VACS are analysed regarding relevance for future motorway traffic management.•VACS-related future challenges are outlined and discussed.
During the last decade, there has been an enormous interdisciplinary effort by the automobile industry and numerous research institutions worldwide towards the development, testing and employment of a variety of Vehicle Automation and Communication Systems (VACS) with the main aims to improve road safety and driver convenience. Some VACS, however, have a direct impact on road efficiency as well and could therefore be exploited to relieve road networks from the significant congestion problems and their negative consequences for travel times, safety, fuel consumption, the environment and the quality of life in general. In other words, some of the available VACS could also be used as novel or innovative sensors, actuators and tools towards a new era of traffic management. This paper provides an overview of proposed and available VACS and discusses their perspectives from the motorway traffic management point of view. Classifications of the different systems in this respect are also provided, while SWOT (Strengths–Weaknesses–Opportunities–Threats) analyses are used to identify specific exploitation ways. Current trends and future perspectives of VACS within a motorway traffic management context are finally summarised.
The benefit of investment advice depends on the quality of advice and the investor's counterfactual portfolio. We use changes in the Oregon University System Optional Retirement Plan to highlight the ...impact of plan design on the counterfactual portfolios of advice seekers. When brokers are available and target date funds (TDFs) are not, brokers help participants with high predicted demand for advice bear market risk, but they recommend higher-commission options. When brokers are removed and TDFs are added, new high-predicted-demand participants primarily invest in TDFs, which offer similar market risk but higher Sharpe ratios than the broker-advised portfolios within our sample.
•This study determines the prospective multimodal transportation hubs in the BRI network.•A multi-methodological approach based on network centrality measures and gravity model is proposed.•This ...study integrates air, rail, and maritime mode of transportation in the BRI network.•The importance of air transportation network in the BRI network is demonstrated.•Analytical result suggests primary cities in the BRI network for enhancing international trading outreach.
As the Belt and Road Initiative (BRI) takes root, the Air Transportation Network (ATN) is gaining prominence, as evidenced by the Air Silk Road Initiative proposed in 2017. However, the ATN of the BRI countries and its integration with maritime and rail transport have not been studied. This paper analyzes the network structure of the ATN of the BRI countries. A multi-layer weighted betweenness metric is used to rank the centrality of the hubs in the network based on the connectivity, distance, and traffic between the airports. Using the centrality ranking of the airports to reflect the distribution of traffic demand in the BRI countries, a gravity model is then applied to quantify the centrality of the maritime and rail hubs. Mapping these hubs to their home cities, this paper assesses the current state of the multimodal transport hubs and recommends new hubs to increase the international trading reach of the BRI.
Does public transportation reduce vehicle congestion? Using a regression-discontinuity framework, we examine the effect of six subway openings on short-run congestion in Beijing between 2009 and ...2015. We find that vehicle congestion drops sharply immediately after new subway openings. In our central specification, each of the subway openings decreased delay times by an average of 15% in the short run over the city of Beijing.
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