Global Transport Research Articles

Geopolitical risk and sustainable shipping: a quantitative approach

ABSTRACT Shipping is pivotal for global trade and by extension, the global economy. In recent decades the industry has been striving for sustainable development, as it battles with an arsenal of issues, including its environmental footprint, efficiency, and profitability. At the same time, the international nature of the maritime industry renders it extremely sensitive to geopolitical issues, as the recent conflict in Ukraine revealed. The latter has influenced a battery of topics ranging from global energy supply and demand, food security, and diplomacy, among others. One of these includes global trade and shipping patterns. This research focuses on data collected with reference to shipping intensity to investigate the exact connection between geopolitical risk and shipping. The results point to a strong relationship, thus providing empirical evidence of the sensitivity of shipping to geopolitics. The findings of this study aspire to assist towards preventative policies that can help the maritime industry become more economically sustainable.

An Optimization Approach to Berth Allocation Problems

The berth allocation problem determining the berthing time and position for incoming vessels in port operations has garnered increased attention within the global transportation network. This study focuses on the berth allocation problem with a continuous quay and dynamic vessel arrivals. With the overarching goal of enhancing service quality and optimizing berth utilization rates, this article proposes a mathematical programming model that minimizes the total waiting time of vessels and the overall completion time of vessel service. The formulated model is a mixed-integer linear programming problem that deterministic optimization techniques can globally solve. For large-scale problems, this study develops a genetic algorithm optimization approach to improve computational efficiency in reaching a near-optimal solution. Several numerical experiments are conducted to demonstrate the effectiveness and efficiency of the proposed approach.

Quantifying the probability of a successful marine bioinvasion due to source-destination risk factors.

The increasing spread of marine non-indigenous species (NIS) due to the growth in global shipping traffic is causing widespread concern for the ecological and economic impacts of marine bioinvasions. Risk management authorities need tools to identify pathways and source regions of priority concern to better target efforts for preventing NIS introduction. The probability of a successful NIS introduction is affected by the likelihood that a marine species entrained in a transport vector will survive the voyage between origin and destination locations and establish an independently reproducing population at the destination. Three important risk factors are voyage duration, range of environmental conditions encountered during transit and environmental similarity between origin and destination. In this study, we aimed for a globally comprehensive approach to assembling quantifications of source-destination risk factors from every potential origin to every potential destination. To derive estimates of voyage-related marine biosecurity risk, we used computer-simulated vessel paths between pairs of ecoprovinces in the Marine Ecoregions Of the World biogeographic classification system. We used the physical length of each path to calculate voyage duration risk and the cross-latitudinal extent of the path to calculate voyage path risk. Environmental similarity risk was based on comparing annual average sea surface temperature and salinity within each ecoprovince to those of other ecoprovinces. We derived three separate sets of risk quantifications, one each for voyage duration, voyage path and environmental similarity. Our quantifications can be applied to studies that require source-destination risk estimates. They can be used separately or combined, depending on the importance of the types of source-destination risks that might be relevant to particular scientific or risk management questions or applications.

Driving forward together: The common intention of Indonesians in different residential areas to use autonomous vehicles

Despite the significant benefits of Autonomous Vehicles (AVs) for global transportation, Indonesia's diverse geographical landscape encounter unique adoption challenges due to infrastructural shortcomings and economic limitations. This study explores the adoption of AVs in Indonesia, considering its potential market and crucial role in AV and Electric Vehicle supply chains. Drawing upon the Technology Acceptance Model (TAM) and the Unified Theory of Acceptance and Use of Technology (UTAUT), we assessed AV acceptance across Indonesia's Metropolitan Cities, frontier regions (“3T”), and the New National Capital City (IKN) areas. Using a cross-sectional study design, we distributed an online questionnaire, focusing on demographics, perceived safety, transport mode changes, and behavioral intention towards AVs, based on TAM and UTAUT factors. From 1,255 valid responses, we found significant influences of gender (t (1253) = 4.22), safety perceptions (F (2,1252) = 52.373), and transport mode frequency (F (4, 1250) = 6.662) on AVs adoption intentions. Both TAM and UTAUT models were moderately effective in explaining willingness to use AVs (R2 = 34% and 48%, respectively). TAM highlighted perceived usefulness (β = 0.421) and ease of use (β = 0.540), while UTAUT emphasized effort expectancy (β = 0.317) and social influence (β = 0.240). However, the findings from the multigroup analysis did not corroborate the role of residential areas in determining the intention to use AVs. These findings offer crucial insights for developing AV promotion strategies, creating user-friendly designs, and formulating supportive policies for AV adoption in diverse Indonesian regions.

On the Efficiency Impacts of Berthing Priority Provision

Facing intensified interport competition in the global container shipping market, an increasing number of ports choose to offer berthing priority for carriers to increase their attractiveness. This study is the first to theoretically analyze the efficiency impacts of such prioritization. Specifically, this study models the steady-state dynamics for each terminal in a biterminal port as a prioritized queuing system. We explore the equilibrated shipping flow distribution and resulting total system cost (i.e., bunker consumption cost and waiting time cost) with and without priority provision, along with their major analytical properties. Then, we examine the “second-order” effects of these priority schemes on just-in-time (JIT) arrivals, an increasingly popular green port management tool. Specifically, we investigate how the equilibrium state associated with JIT arrivals could change with priority berthing. These analyses generate some interesting results, including (1) the total system cost increases or remains unchanged when a priority scheme is implemented under a symmetric port with equal service capacities for both terminals; (2) under the asymmetric biterminal case, however, it is also possible that berth prioritization could reduce the total system cost, and such phenomenon occurs only if the terminal which offers prioritization owns larger service capacity; (3) the results indicate that the “price of prioritization” could reach [Formula: see text] in port operation when the berth loading is heavy, implying that priority provision may significantly harm the operational efficiency; and (4) lastly, priority provision has a negative second-order effect on JIT strategies in a symmetric port, and such negative effect may neutralize the positive ones. Those theoretical results are validated by numerical experiments, and some of them are also supported by empirical data. The results provide important practical implications for the decision making of the port (or terminal) agencies. Funding: This work was supported by the National Natural Science Foundation of China [Grants 72371143 and 72188101]. Supplemental Material: The online appendix is available at https://doi.org/10.1287/trsc.2022.0411 .

Do shipping alliances affect freight rates? Evidence from global satellite ship data

Shipping alliances (SAs) can facilitate their members’ coordination on price and capacity decisions. Although this helps reduce the oversupply of capacity and cutthroat competition during market downturns, the possible freight rate increase due to potential collusion among member shipping lines is another concern. This study aims to empirically investigate the impacts of SAs on container freight rates on nine major shipping corridors for the period from 2015 to 2020. To measure market concentration, data from a satellite-based Automatic Information System (AIS) is used to identify liner shipping companies' services in each market. We propose to use the alliance-level Herfindahl-Hirschman Index (HHI) and Concentration Ratio Index (CR) to measure market concentration. Then we used the simulated market concentration measures as the instrumental variable to address the endogeneity issue between freight rates and alliances’ market share. The main finding is that both alliance-level HHI and CR are negatively associated with freight rates, implying that SAs may help reduce prices. This finding provides new insights for antitrust authorities when investigating alliance applications in the liner shipping sector.

Marine trading sector in Singapore

The marine trading sector in Singapore is a cornerstone of the nation's economy, strategically positioned at the crossroads of major global shipping routes. This report thoroughly explores the worldwide importance of Singapore's maritime trade, highlighting its pivotal role in facilitating the movement of goods and commodities. Singapore's impact on global maritime trade remains significant, propelled by its exceptional port facilities, streamlined logistics infrastructure, and advantageous geographic location. Moreover, the report emphasizes the crucial role played by the Strait of Malacca, acting as a vital maritime passage where a considerable portion of global trade passes through. Understanding the intricacies of Singapore's marine sector and recognizing the strategic importance of the Strait of Malacca is imperative for comprehending the nation's impact on global trade dynamics. This underscores Singapore's continuous involvement as a key player in the complex web of international commerce

Using a bottom-up method to assess cruise ship activity impacts on emissions during 2019–2020 in China

COVID-19 has had a serious impact on the development of the global shipping industry, especially since the impact on the cruise tourism industry was unprecedented. This study took cruise ships sailing in China ECA, China Exclusive Economic Zone (EEZ), Yangtze River main line, and Xijiang River main line Chinese waters as an example to analyze the key changes in cruise ship emissions during the pandemic. Automatic identification system (AIS) data, vessel static data, and emission control regional data are used to conduct a comprehensive analysis of cruise ship emissions from multiple perspectives such as a port-to-regional comparison. As such, a vessel emission model (i.e., a bottom-up method) is constructed in this research for predicting China ECA and EEZ cruise ship emissions. Compared with 2019, the cruise activities sailing in China's Emission Control Area (ECA) are mainly at berth, and the emissions of cruise ships have dropped significantly, with SOx emissions reduced by 59.11%. In addition, this study also calculates the carbon emissions of China's regional cruises, supplementing China's cruise carbon pool. The research results suggest that cruise operators may improve fuel efficiency, decrease vessel speed, improve routing and scheduling, and enhance fleet management in order to further mitigate the negative effects of the cruise tourism industry on the marine environment.

Soft TQM for competitive advantage in the transportation sector: investigating green human resource management and stakeholder integration

PurposeRecent trends in total quality management (TQM) argue in favor of incorporating environmental concerns into TQM and considering external stakeholders. The aim of this study is to bring environmental consciousness in the soft TQM dimension of human resource management (HRM) and assess its interrelationship with stakeholder integration towards achieving a competitive advantage.Design/methodology/approachAn empirical study was conducted in the transportation sector, specifically targeting managers in Greek shipping companies involved in global cargo transport and vessel operations. A structured questionnaire was administered, yielding 109 responses. The collected data were analyzed using partial least squares structural equation modeling.FindingsThe findings reveal the positive effect of both green HRM (GHRM) and stakeholder integration on the innovation differentiation advantage and market differentiation advantage of shipping companies. Results confirm the complementary (partial) mediating effect of GHRM in the relationship between stakeholder integration and both types of competitive advantage.Research limitations/implicationsThe primary limitation resides in data collection exclusively from shipping companies in Greece. A longitudinal approach would be beneficial for examining how the relationship between variables changes over time.Practical implicationsThe findings of the study could assist shipping managers in their decisions to allocate resources for developing GHRM practices and for involving stakeholders in organizational practices to overcome competition.Originality/valueThis study contributes to the discourse on TQM by empirically investigating the combined impact of GHRM and stakeholder integration on competitive advantage – an aspect that has been relatively overlooked in existing literature.

Development of the tangent linear and adjoint models of the global online chemical transport model MPAS-CO2 v7.3

Abstract. We describe the development of the tangent linear (TL) and adjoint models of the Model for Prediction Across Scales (MPAS)-CO2 transport model, which is a global online chemical transport model developed upon the non-hydrostatic Model for Prediction Across Scales – Atmosphere (MPAS-A). The primary goal is to make the model system a valuable research tool for investigating atmospheric carbon transport and inverse modeling. First, we develop the TL code, encompassing all CO2 transport processes within the MPAS-CO2 forward model. Then, we construct the adjoint model using a combined strategy involving re-calculation and storage of the essential meteorological variables needed for CO2 transport. This strategy allows the adjoint model to undertake a long-period integration with moderate memory demands. To ensure accuracy, the TL and adjoint models undergo vigorous verifications through a series of standard tests. The adjoint model, through backward-in-time integration, calculates the sensitivity of atmospheric CO2 observations to surface CO2 fluxes and the initial atmospheric CO2 mixing ratio. To demonstrate the utility of the newly developed adjoint model, we conduct simulations for two types of atmospheric CO2 observations, namely the tower-based in situ CO2 mixing ratio and satellite-derived column-averaged CO2 mixing ratio (XCO2). A comparison between the sensitivity to surface flux calculated by the MPAS-CO2 adjoint model with its counterpart from CarbonTracker–Lagrange (CT-L) reveals a spatial agreement but notable magnitude differences. These differences, particularly evident for XCO2, might be attributed to the two model systems' differences in the simulation configuration, spatial resolution, and treatment of vertical mixing processes. Moreover, this comparison highlights the substantial loss of information in the atmospheric CO2 observations due to CT-L's spatial domain limitation. Furthermore, the adjoint sensitivity analysis demonstrates that the sensitivities to both surface flux and initial CO2 conditions spread out throughout the entire Northern Hemisphere within a month. MPAS-CO2 forward, TL, and adjoint models stand out for their calculation efficiency and variable-resolution capability, making them competitive in computational cost. In conclusion, the successful development of the MPAS-CO2 TL and adjoint models, and their integration into the MPAS-CO2 system, establish the possibility of using MPAS's unique features in atmospheric CO2 transport sensitivity studies and in inverse modeling with advanced methods such as variational data assimilation.

Influence of Wind Flows on Surface O3 Variation over a Coastal Province in Southeast China

Surface ozone (O3) is influenced not only by anthropogenic emissions but also by meteorological factors, with wind direction being one of the most overlooked factors. Here, we combine the observational data of both O3 and wind flow to compare the variation in surface O3 with wind direction between coastal and inland regions of Fujian, a province in the southeast coast of China with complicated topography. We further conduct a numerical simulation using a global chemical transport model, GEOS-Chem, to interpret the observational results, explore the linkages between these O3 variations and wind flows, and identify the dominant processes for the occurrence of high O3 that varies with wind flows. The results from the observations over 2015–2021 suggest that, over coastal regions, surface O3 concentrations show a strong dependence on wind flow changes. On average, during the daytime, when southeasterly winds prevail, the mean of O3 concentrations reaches 83.5 μg/m3, which is 5.0 μg/m3 higher than its baseline values (the mean O3 concentrations), while the northwesterly winds tend to reduce surface O3 by 6.4 μg/m3. The positive O3 anomalies with southeasterly wind are higher in the autumn and summer than in the spring and winter. During the nighttime, the onshore northeasterly winds are associated with enhanced O3 levels, likely due to the airmass containing less NO2, alleviating the titration effects. Over inland regions, however, surface O3 variations are less sensitive to wind flow changes. The GEOS-Chem simulations show that the prevailing southeasterly and southwesterly winds lead to the positive anomaly of chemical reactions of O3 over coastal regions, suggesting enhanced photochemical production rates. Furthermore, southeasterly winds also aid in transporting more O3 from the outer regions into the coastal regions of Fujian, which jointly results in elevated surface O3 when southeasterly winds dominates. When affected by wind flows in different directions, the chemical reaction and transport in the inland regions do not exhibit significant differences regarding their impact on O3. This could be one of the reasons for the difference in O3 distribution between coastal and inland regions. This study could help to deepen our understanding of O3 pollution and aid in providing an effective warning of high-O3 episodes.

Future Ozone Changes and Their Impacts on Vegetation and Human Health in China Under the Shared Socio‐Economic Pathways

AbstractOzone concentrations in China are increasing in recent years and future changes of ozone and their impacts have attracted much attention. We use global chemical transport model (GEOS‐Chem) to simulate the surface ozone concentrations in China in 2020 and 2050 under four Shared Socio‐economic Pathways and evaluate the impacts of future ozone pollution on vegetation and premature mortality in four polluted regions (Beijing–Tianjin–Hebei, BTH; Yangtze River Delta, YRD; Pearl River Delta, PRD; Sichuan Basin, SCB) and three major crop growing areas (Huang–Huai–Hai, HHH; Northeast Plain, NEP; middle and lower reaches of Yangtze River, MLRY) in China. The changes of simulated seasonal maximum daily 8‐hr average (MDA8) ozone from 2020 to 2050 (−15.5 to +11.9 ppbv) are significant under SSP126 (low forcing pathway) and SSP245 (medium forcing pathway) scenarios in all regions due to large changes of emissions. MDA8 ozone in summer 2050 will be above the WHO guidelines (100 μg/m3) in BTH, YRD, HHH and MLRY under four scenarios. By 2050, W126 (vegetative ozone exposure index) in summer will be much above the maximum of US secondary standard (21 ppm‐h) in HHH under SSP245, SSP370 (medium to high forcing pathway) and SSP585 (high forcing pathway) scenarios, and in MLRY under SSP370 and SSP585 scenarios. Annual ozone‐related deaths for people over 30 years old will mainly decrease in four polluted areas from 2020 to 2050 under SSPs scenarios, but only increase much under SSP245 scenario in BTH (+3.1 to +4.2 thousand) and YRD (+1.1 to +1.6 thousand).

Evaluation of Ship Recycling Industry in View of Present Global Circumstances and Way Forward

Ship recycling, commonly referred to as ship dismantling, is an inherently sustainable practice with global implications. It involves the reverse engineering process of disassembling obsolete ships to recover reusable materials in a safe and environmentally friendly manner. Over the past two decades, ships have predominantly been beached in South Asian countries such as Bangladesh, India, China, and Pakistan, allowing local yards to dismantle vessels with moderate preventive measures and substantial manual labor. Ship recycling stands as a significant and environmentally conscious industry, witnessing the annual recycling of approximately 1000 obsolete ships globally. Currently, this industry is predominantly led by three South Asian countries—India, Bangladesh, and Pakistan. In Bangladesh, the industry commenced with the dismantling of stranded ships, evolving into a large and profitable sector that generates substantial employment opportunities for thousands of semi-skilled workers in poverty-prone areas. While the ship recycling industry presents opportunities, it also poses challenges for coastal zone management, encompassing environmental, law enforcement, and worker safety concerns. The surge in demand for ship recycling has prompted increased regulatory scrutiny at both national and international levels. This pressure culminated in the development of the Hong Kong International Convention (HKC) by the IMO in 2009, mandating safety and environmental protection standards at recycling yards. Achieving a perfectly green ship recycling process in line with European standards is inherently costly. However, a viable and almost green ship recycling approach, integrating the current common practice of beaching methods in Asian countries, is entirely feasible. Despite limitations and challenges, the industry significantly contributes to Bangladesh's GDP and the overall socio-economic landscape. Currently, there has been a visible reduction in Bangladesh's market share due to stringent environmental regulations, while competitors have experienced increases. This study represents an analytical effort to evaluate the current global ship recycling scenario, exploring its potential, challenges, and the future trajectory of both local and global ship recycling industries.

The Stirring Tropics: Theory of Moisture Mode–Hadley Cell Interactions

Abstract Interactions between large-scale waves and the Hadley cell are examined using a linear two-layer model on an f plane. A linear meridional moisture gradient determines the strength of the idealized Hadley cell. The trade winds are in thermal wind balance with a weak temperature gradient (WTG). The mean meridional moisture gradient is unstable to synoptic-scale (horizontal scale of ∼1000 km) moisture modes that are advected westward by the trade winds, reminiscent of oceanic tropical depression–like waves. Meridional moisture advection causes the moisture modes to grow from “moisture-vortex instability” (MVI), resulting in a poleward eddy moisture flux that flattens the zonal-mean meridional moisture gradient, thereby weakening the Hadley cell. The amplification of waves at the expense of the zonal-mean meridional moisture gradient implies a downscale latent energy cascade. The eddy moisture flux is opposed by a regeneration of the meridional moisture gradient by the Hadley cell. These Hadley cell–moisture mode interactions are reminiscent of quasigeostrophic interactions, except that wave activity is due to column moisture variance rather than potential vorticity variance. The interactions can result in predator–prey cycles in moisture mode activity and Hadley cell strength that are akin to ITCZ breakdown. It is proposed that moisture modes are the tropical analog to midlatitude baroclinic waves. MVI is analogous to baroclinic instability, stirring latent energy in the same way that dry baroclinic eddies stir sensible heat. These results indicate that moisture modes stabilize the Hadley cell and may be as important as the latter in global energy transport. Significance Statement The tropics are characterized by steady circulations such as the Hadley cell as well as a menagerie of tropical weather systems. Despite progress in our understanding of both, little is known about how the mean circulations and the weather systems interact with one another. Here we show that tropical waves can grow by extracting moisture from the Hadley cell, thereby weakening it. They also transport moisture to higher latitudes. Our results challenge the notion that the Hadley cell is the sole transporter of energy out of the tropics and instead favor a view where tropical waves are also essential for the global energy balance. They dry the humid regions and moisten the drier regions via stirring.

Investigating the Co-Movement and Asymmetric Relationships of Oil Prices on the Shipping Stock Returns: Evidence from Three Shipping-Flagged Companies from Germany, South Korea, and Taiwan.

In the last 2 years, there has been a significant upswing in oil prices, leading to a decline in economic activity and demand. This trend holds substantial implications for the global economy, particularly within the emerging business landscape. Among the influential risk factors impacting the returns of shipping stocks, none looms larger than the volatility in oil prices. Yet, only a limited number of studies have explored the complex relationship between oil price shocks and the dynamics of the liner shipping industry, with specific focus on uncertainty linkages and potential diversification strategies. This study aims to investigate the co-movements and asymmetric associations between oil prices (specifically, West Texas Intermediate and Brent) and the stock returns of three prominent shipping companies from Germany, South Korea, and Taiwan. The results unequivocally highlight the indispensable role of oil prices in shaping both short-term and long-term shipping stock returns. In addition, the research underscores the statistical significance of exchange rates and interest rates in influencing these returns, with their effects varying across different time horizons. Notably, shipping stock prices exhibit heightened sensitivity to positive movements in oil prices, while exchange rates and interest rates exert contrasting impacts, one being positive and the other negative. These findings collectively illuminate the profound influence of market sentiment regarding crucial economic indicators within the global shipping sector.

Global burden of all cause-specific injuries among children and adolescents from 1990 to 2019: a prospective cohort study.

To assess the burden and change in incidence, death, and disability-adjusted life years (DALYs) for all-cause-specific injuries among children and adolescents in 204 countries and territories between 1990 and 2019. Data were extracted from the Global Burden of Disease, Injury, and Risk Factor Study 2019 (GBD 2019). Global, regional, and country-level age-standardized rate (per 100000) of incidence (ASRI), mortality (ASRM), and DALYs (ASRD) with 95% uncertainty interval (95% UI) of injuries were estimated by age, sex, socio-demographic index (SDI), and all-cause-specific injuries from 1990 to 2019. Overall, the ASRI, ASRM, and ASRD of injury were 9006.18 (95% UI: 7459.74-10918.04), 23.04 (20.00-26.50), and 2020.19 (1759.47-2318.64) among children and adolescents worldwide in 2019, respectively. All the above indicators showed a downward trend from 1990 to 2019. In level 2 cause of injury, both the global transport injury and unintentional injury declined during the study years, while self-harm and interpersonal violence-related injury showed an increasing trend. High SDI regions had higher ASRI of injuries, but low SDI regions had higher ASRM and ASRD of injuries globally in 2019. Males had a higher burden of injuries than those in females. The ASRI of injuries is higher in adolescents aged 15-19 years, whereas the mortality and DALYs rate are higher among children under 5 years old. Moreover, adolescents aged 15-19 years and individuals living in Central Asia, Middle East, and Africa had higher ASRI, ASRM, and ASRD of injuries owing to self-harm and interpersonal violence. Generally, falls and road traffic injuries are the leading cause of injury among the population aged 0-19 years worldwide, but self-harm, interpersonal violence, and conflict and terrorism are also leading types of injuries in some regions, particularly in Low-Income Countries and Middle-Income Countries. Injury remains a major global public health problem among children and adolescents, although its burden at the worldwide level showed a decreasing trend from 1990 to 2019. Of concern, the burden of injuries caused by transport injuries, and unintentional injuries has shown a downward trend in most countries, while the burden caused by self-harm and interpersonal violence has shown an upward trend in most countries. These findings suggest that more targeted and specific strategies to prevent the burden of injuries should be reoriented, and our study provides important findings for decision-makers and healthcare providers to reduce injury burden among children and adolescents.

Supergranule aggregation: a Prandtl number-independent feature of constant heat flux-driven convection flows

Supergranule aggregation, i.e. the gradual aggregation of convection cells to horizontally extended networks of flow structures, is a unique feature of constant heat flux-driven turbulent convection. In the present study, we address the question if this mechanism of self-organisation of the flow is present for any fluid. Therefore, we analyse three-dimensional Rayleigh–Bénard convection at a fixed Rayleigh number ${Ra} \approx 2.0 \times 10^{5}$ across $4$ orders of Prandtl numbers ${Pr} \in [10^{-2}, 10^{2}]$ by means of direct numerical simulations in horizontally extended periodic domains with aspect ratio $\varGamma = 60$ . Our study confirms the omnipresence of the mechanism of supergranule aggregation for the entire range of investigated fluids. Moreover, we analyse the effect of ${Pr}$ on the global heat and momentum transport, and clarify the role of a potential stable stratification in the bulk of the fluid layer. The ubiquity of the investigated mechanism of flow self-organisation underlines its relevance for pattern formation in geophysical and astrophysical convection flows, the latter of which are often driven by prescribed heat fluxes.

A hybrid prediction model of vessel trajectory based on attention mechanism and CNN-GRU

With the increase in global shipping volumes and the complexity of maritime transport systems, vessel trajectory prediction serves an important tool in improving maritime safety. However, most existing vessel trajectory prediction methods focus on a single feature and unable fuse high-dimensional features. To solve these problems, CNN-GRU model with a hybrid attention mechanism (AM) is proposed based on Automatic Identification System (AIS) data. First convolutional neural network (CNN) is proposed to extract the spatio-temporal information of the trajectory data. Then a gated recurrent unit (GRU) is designed to extract the temporal relationship of the trajectories. Finally, AM is introduced to learn the deep-level features and predict the vessel trajectories. To validate the effectiveness of the model, experiments are conducted on three real AIS datasets. In comparison with other models, the method has a high trajectory prediction accuracy.

Na2.5Cr0.5Zr0.5Cl6: A New Halide-Based Fast Sodium-Ion Conductor.

All-solid-state batteries employing solid electrolytes (SEs) have received widespread attention due to their high safety. Recently, lithium halides are intensively investigated as promising SEs while their sodium counterparts are less studied. Herein, a new sodium-ion conductor with a chemical formula of Na2.5Cr0.5Zr0.5Cl6 is reported, which exhibits high room temperature ionic conductivity of 0.1 mScm-1 with low migration energy barrier of ≈0.41eV. Na2.5Cr0.5Zr0.5Cl6 has a Fm-3m structure with 41.67mol.% of cationic vacancies owing to the occupation of Cr (8.33mol.%) and Zr (8.33mol.%) ions at Na sites. Supercell calculations show that the lowest columbic energy configuration has Cr/Zr/V (where V is the vacancy) clusters in the structure. Nonetheless, the clusters have mixed effects on the sodium ion conduction pathway, based on the Bond Valence Energy Landscape calculation. A global 3D Na-ion transport percolation network can be revealed in the lowest energy supercell. Effective pathways are connected through the NaCl6 and VCl6 nodes. Besides, Raman spectroscopy and 23Na solid-state nuclear magnetic resonance spectroscopy further prove the tunable structure of the SEs with different Cr to Zr ratios. The optimization between the concentration of Na+ and vacancies is crucial to create an improved network of Na+ diffusion channels.

Regional Sources and CH4 Seasonal Cycle in Central Siberia and the Arctic: Observations and Numerical Calculations

Contributions of anthropogenic and wetland methane emissions in Northern Eurasia (>40° N) and Russia into the near-surface CH4 abundance are quantified using GEOS-chem global chemical transport model at ZOTTO, Teriberka, and Tiksi measurement sites. Numerical results agree well with the proposed semianalytical solution, in which the total contribution (atmospheric response) in the CH4 level at a given site is decomposed into direct (synoptic) and global terms. On an advection timescale corresponding to a synoptic time interval, the annual average direct contribution of Russian anthropogenic emissions into the CH4 mixing ratio measured at ZOTTO (38.6 ppbv) is more than twice as large as that for Western Europe sources (17.7 ppbv). For the Arctic sites, the anthropogenic inputs from Russian and European sources are roughly similar (19.5 and 12.4 ppbv, respectively). The input from continental sources into near-surface methane abundance and its annual variations at the Arctic sites are generally lower compared to those at the ZOTTO site due to larger transport times from upstream CH4 source regions. Model-based atmospheric responses in methane levels at the Teriberka and Tiksi sites to continental CH4 sources are found to be very close owing to the relatively homogeneous (circumpolar) spatial distributions of the anthropogenic and biogenic signals at high latitudes.