Search Results (280)

This paper presents a practical and communication-independent energy management system (EMS) for a DC microgrid supply within the firezone of a cruise ship. The proposed approach prioritizes operational reliability and fault tolerance under emergency conditions, where communication availability and control complexity should be minimized. The proposed DC microgrid integrates photovoltaic systems (PVs), fuel cell systems (FCs), and lithium-iron-phosphate (LFP) battery energy storage systems (BESSs), coordinated through a rule-based EMS combined with droop-controlled converters. The electrical topology considered in this study is a collaborative development of the project consortium of the publicly funded project Sustainable DC Systems (SuSy), featuring a novel configuration with two independent horizontal busbars for the Cabin Area Distribution (CAD) and Technical Area Distribution (TAD). The EMS can manage two operational scenarios: (i) regular operation, with two decentralized droop controls where power generation is distributed among all generators based on their respective capacities, and a power curtailment strategy is applied to prevent overcharging of BESSs; and (ii) irregular operation, where a fault on one of the vertical busbars triggers the use of reserved battery storage capacity on both sides of the ship and activates load-shedding to ensure continued operation of critical loads and sustain grid functionality. The effectiveness of the proposed architecture is validated through detailed MATLAB/Simulink simulations. Under regular conditions, the EMS achieves stable voltage regulation, balanced power sharing, and efficient energy curtailment. During fault conditions, the battery storage on both sides successfully supports the critical loads. The fuel cells are operated in power-controlled mode effectively up to their full rated 6$\mathrm{k}$$\mathrm{W}$ capacity while the DC bus voltage stabilization is ensured by the battery energy storage systems. These results validate the proposed EMS as a robust and low-complexity solution for maritime DC microgrids, offering stable voltage regulation, effective load prioritization, and resilient operation of critical loads. Full article

Cruise ship manufacturing is a high-tech, complex industry where development depends on coordination across stages and organizations. We advance the coordination literature by treating the supply chain, industry chain, and value chain as a complex system, and by linking cross-chain coordination to high-quality development in a way that is comparable to theoretical debates on capability building and productivity-oriented development. Empirically, we collect city-level panel data for ten Chinese cruise port cities from 2008 to 2023 and combine a coupling–coordination framework with a panel data qualitative comparative analysis (PD-QCA) to capture both coordination dynamics and configurational causality. Our results show substantial heterogeneity in coordination trajectories, which can be grouped into decline–recovery, high-level stability, and persistent decline/high-variability patterns. We also show that high coupling does not guarantee high-quality outcomes, which are jointly shaped by industrial foundations, high-end value creation, and innovation capacity. Moreover, we identify two main pathways: an anchoring pathway that depends on output capacity and resource inputs, and an optimizing pathway that mainly relies on investment intensity, demand-side output, and value efficiency, with cross-chain coordination acting as an enabling condition that helps improve cross-chain matching. Full article

Cruise ships and superyachts have experienced significant global expansion throughout the 21st century. Although the growth in cruise passenger numbers was temporarily disrupted by the COVID-19 pandemic, occupancy rates have since rebounded and even exceeded pre-pandemic levels. This study highlights the significant environmental impact of cruise ships and luxury yachts, particularly in terms of air emissions and marine pollution. Emission levels associated with different fuel types and marine engines are analysed, including the average emissions generated by the Norwegian Cruise Line fleet while docked in ports, as well as the estimated emission reductions achievable through the implementation of onshore power supply systems. To identify environmentally preferable fuel options, a hybrid ANN/MCDM framework is applied. The weighting coefficients of eight evaluation criteria are determined using the Artificial Neural Network/Extreme Learning Machine (ANN/ELM) model, ensuring an objective and data-driven assessment of their relative importance. The ANN/ELM model was trained using emission and fuel-related data collected from the literature and industry reports, and its performance was validated using standard validation procedures, achieving satisfactory predictive accuracy for determining the weighting coefficients. The final ranking of eight fuel alternatives is subsequently performed using the Ranking Alternatives by Weighting of Evaluated Criteria (RAWEC) method. The considered alternatives include conventional and emerging marine fuels currently used in practice or under technological development (A₁–A₈), while the optimization criteria (C₁–C₈) encompass major air pollutants (CO₂, NOx, SOx, CO, PM, CH₄), the fuel cost-to-consumption ratio, and the potential impact on water pollution. The water pollution criterion is assessed qualitatively using the Saaty scale. The integrated ANN/ELM–RAWEC approach enables a systematic comparison of marine fuels and supports the identification of options with the lowest overall environmental impact. Full article

In recent decades, cruise tourism has emerged as a key economic driver for port cities, while simultaneously intensifying environmental pressures and socio-spatial inequalities. Despite growing scholarly attention, research exploring how these pressures are distributed within urban contexts and how they interact with pre-existing vulnerability patterns remains scarce. This study addresses this gap by proposing a GIS-based integrated methodological framework, the Port-city Risk Integrated Spatial Method (PRISM), applied to the Mediterranean port city of Malaga, Spain. The approach combines socio-demographic indicators and data related to spatial amenities with environmental pressures from cruise ship emissions to construct an Urban Socio-Environmental Complexity Index. Emission scenarios for peak cruise days were estimated using a bottom-up methodology and spatialized through atmospheric dispersion modeling, enabling their integration with exposure, vulnerability, and urban capacity indicators. The results reveal marked intra-urban heterogeneity and highlight the emergence of cumulative risk hotspots in areas adjacent to the port and along prevailing inland dispersion corridors. This study demonstrates the potential of integrated spatial indices as decision support tools for urban planning, offering a replicable framework for other port cities facing similar tourism-driven transformations. Full article

To enhance fleet replenishment efficiency and ensure navigational safety, this paper investigates the Underway Replenishment Routing Problem (URRP), focusing on the dynamic characteristics of receiving ships. Mathematical models for replenishment ship travel time and formation vessel speed adjustment are formulated, explicitly considering navigational state transitions and formation stability (risk control). Consequently, a dynamic route optimization model is constructed to provide intelligent decision support for fleet commanders. An intelligent optimization algorithm, the Hybrid Genetic Algorithm with Adaptive Variable Neighborhood Search (HGA-AVNS), is proposed to solve this model. Computational results demonstrate that the proposed approach outperforms the traditional empirical replenishment strategy, validating its effectiveness in enhancing maritime safety and operational efficiency. Extensive sensitivity analyses further reveal that under the strict premise of maintaining formation stability, appropriately reducing the cruise speed can offset the increase in overall speed over ground (SOG) induced by following ocean currents, thereby preventing systematic time loss. Additionally, fine-tuning the execution timing of sudden tactical turning based on the replenishment ship’s real-time operational status can further maximize overall replenishment efficiency without compromising navigational safety. Full article

Marine-related activities contribute significantly to plastic pollution in oceans worldwide, particularly in regions located along international maritime routes such as Türkiye. The Dardanelles serves as a major maritime gateway connecting the Aegean Sea with both the Sea of Marmara and the Black Sea, enabling heavy vessel traffic that subsequently disperses plastic pollutants across large areas of the Mediterranean and beyond. Therefore, for the first time, this study applied material flow analysis to estimate potential sources and pathways of macro- and microplastics from 12 vessel categories, including fishing fleets, merchant ships, cruise liners, and military vessels in the Northern Aegean Sea. This approach provides insight into the range of sources and pathways, highlights priority areas for mitigation, and identifies additional knowledge gaps. Through material flow analysis–based estimations, general macro- and microplastic waste is found to be the largest contributor to marine plastic pollution, with an average of 14,965 tons/year, followed by antifouling particles at 5848.5 tons/year. Overall, this study presents a comprehensive evaluation of vessel-derived plastic pollution in a strategically significant maritime corridor and emphasizes its potential implications for the broader marine eco-system. Full article

Maritime transport is essential for global trade, yet ship emissions remain a major source of air pollution in coastal and port areas, with potential impacts on local air quality and human health. Cruise ships are particularly relevant in urban ports because, beyond propulsion, they require a continuous onboard energy supply for hotel services while berthed. This study develops a bottom-up emission inventory for cruise ship calls at Istanbul Galataport during the 2024 season, estimating CO₂ as a greenhouse gas (GHG) and NO_x, SO_x, and particulate matter (PM) as air-quality pollutants generated during manoeuvring and hotelling phases. Ship technical characteristics (engine type, installed main and auxiliary power, engine speed class, and year of build) were obtained from the IHS database, while port call activity data were provided by the terminal operator. Emission factors were primarily based on the IMO Third Greenhouse Gas Study and complemented with established literature sources to address missing vessel information and ensure methodological consistency. Results indicate that hotelling dominates total emissions, reflecting the high auxiliary power demand during berths. Results show that total annual emissions from 164 cruise ship calls amount to approximately 31,360 t·y⁻¹ of CO₂, 370 t·y⁻¹ of NO_x, 350 t·y⁻¹ of SO_x, and 44 t·y⁻¹ of PM. Hotelling operations account for the dominant share of emissions, contributing more than 90% of total CO₂ and the majority of NO_x and SO_x emissions, due to sustained auxiliary engine demand during berth stays. These findings confirm that cruise ship activity represents a significant localized emission source in densely populated port environments and provide a quantitative baseline for evaluating mitigation measures such as shore power, cleaner fuels, and operational strategies aimed at reducing at-berth emissions. Full article

This paper proposes a physics-informed hybrid digital CO₂ emission-control technology for maritime transport, designed for adaptive ship speed optimization along a predefined geographical route between two ports, discretized into quasi-stationary segments and evaluated under forecasted metocean conditions, subject to economic and regulatory constraints associated with maritime decarbonization. The framework integrates two exact optimization methods, Backtracking (BT) and Dynamic Programming (DP), with a reinforcement learning approach based on Proximal Policy Optimization (PPO), operating on a unified physical, economic, and regulatory modeling core. By reducing propulsion fuel demand, the system acts as an upstream CO₂ emission-control mechanism for ship propulsion. This operational stabilization of the engine load creates favourable boundary conditions for advanced combustion processes and reduces the volumetric flow of exhaust gas, thereby lowering the technical burden on potential post-combustion carbon capture systems. Segment-wise speed profiles are optimized subject to propulsion limits, Estimated Time of Arrival (ETA) feasibility, and regulatory constraints, including the Carbon Intensity Indicator (CII), the European Union Emissions Trading System (EU ETS) and FuelEU Maritime. The physics-based propulsion and energy model is validated using full-scale operational data from four real voyages of an oil/chemical tanker. A detailed case study on the Milazzo–Motril route demonstrates that adaptive speed optimization consistently outperforms conventional cruise operation. Exact optimization methods achieve voyage time reductions of approximately 10% and fuel and CO₂ emission reductions of about 9–10%. The reinforcement learning approach provides the best overall performance, reducing voyage time by approximately 15% and achieving fuel savings and CO₂ emission reductions of about 13%. At the route level, the Carbon Intensity Indicator is reduced by approximately 10% for the exact methods and by about 13% for PPO. Backtracking and Dynamic Programming converge to nearly identical globally optimal solutions within the discretized decision space, while PPO identifies solutions located on the most favourable region of the cost–time Pareto front. By benchmarking reinforcement learning against exact discrete solvers within a shared physics-informed structure, the proposed digital platform provides transparent validation of learning-based optimization and offers a scalable decision-support technology for pre-fixture evaluation of fixed-route voyages. The system enables quantitative assessment of CO₂ emissions, ETA feasibility, and regulatory exposure (CII, EU ETS, FuelEU Maritime penalties) prior to transport contracting, thereby supporting economically and environmentally informed operational decisions. Full article

The decarbonization of large cruise ships is challenged by their extreme and tightly coupled electrical, thermal, and cooling demands. This study investigates a liquid hydrogen (LH₂)-based tri-generation system for cruise ships that simultaneously supplies electricity, heat, and cooling. Key novelties include the use of LH₂ as the onboard energy carrier for large cruise ships, the recovery of cooling energy from LH₂, a dynamic control strategy that synergistically modulates PEM fuel cell utilization to regulate downstream catalytic burner heat generation and balance heat and electricity generation and demand, and the first full-scale cruise-ship model of such a system, including hydrogen consumption and onboard storage sizing. A dynamic system-level model is applied to a representative 7-day voyage of a large cruise ship. The results show that the proposed system can meet combined peak demands of approximately 61 MW while achieving overall system efficiencies approaching 75%. Compared to traditional marine diesel-based power plants, the LH₂-based tri-generation configuration improves system efficiency by more than 20 percentage points. Total hydrogen consumption is estimated at approximately 240 t, which can be reduced by about 20% through shore-to-ship power, yielding a system volume comparable to that of a conventional diesel-based power plant. These results demonstrate the technical feasibility and system-level advantages of LH₂-based tri-generation for zero-emission cruise ships. Full article

Using computational fluid dynamics (CFD) coupled with the volume of fluid (VOF) method, we developed an analytical framework to quantify free-surface suction around ship hulls. The DTMB 5415 benchmark hull was employed to investigate the mechanisms by which underwater tail fins influence surface wake dynamics. We systematically evaluated the effects of tail-fin span on hydrodynamic drag and free-surface suction across the investigated speed range. Within the Froude number range of 0.05–0.45, underwater tail fins reduced air entrainment by optimizing hull attitude and attenuating stern waves. Free-surface suction capacity exhibited a positive correlation with vessel speed and a negative correlation with tail-fin span length. At Fr = 0.45, the free-surface suction capacity of the bare hull was 13.78 times greater than that at Fr = 0.15. At this speed, the L₄ tail-fin configuration achieved a 13.292% reduction in free-surface suction. In contrast, the L₂ tail-fin configuration provided a suction reduction of only 9.98%. The optimal tail-fin span represents a trade-off between drag reduction and wake suppression, as longer spans do not necessarily yield superior performance. Under cruise conditions (Fr = 0.25–0.35), the L₂ tail-fin configuration exhibited optimal performance, achieving a 5.292% reduction in drag and a 13.492% reduction in free-surface suction. Across the tested Froude number range of 0.05–0.45, underwater tail fins simultaneously improved hydrodynamic performance and reduced free-surface suction, thereby effectively suppressing bubble wake formation. Full article

The decarbonization of shipping and the transformation towards digitally assisted or automated ship operation require new methods to analyze, predict, and optimize energy demand during maneuvering. The SimPleShip-SigMa sub-project of Hochschule Wismar developed and validated a comprehensive simulation-based framework combining real-time capable fast-time simulation of ship motion, detailed thermodynamic engine modeling, and hybrid data exchange via Functional Mock-up Units (FMU/FMI). The approach enables consistent coupling between navigation-related and machinery-related simulations and supports energy-optimized decision-making on the bridge. Operational relevance and validation of use cases were supported through collaboration with Carnival Maritime GmbH, providing practical feedback on large passenger-ship operations. The study presents the architecture of the simulation environment, the implementation of energy- and emission-prediction models, and the result of validation runs and simulator-based trials. The developed method was applied to a virtual cruise-ship scenario representing a confined coastal environment similar to the Geiranger Fjord. The work builds upon earlier research on simulation-augmented maneuvering and extends it toward a modular digital-twin concept linking hydrodynamic and thermodynamic models. The paper concludes with an outlook on applying the system for crew training, on-board support, and gradual automation of sustainable ship operations. Full article

The efficient and timely management of human evacuation during emergency events is an important area of research where the Internet of Things (IoT) can be of great value. Significant areas of application for optimum evacuation strategies include buildings, sports arenas, cultural venues, such as museums and concert halls, and ships that carry passengers, such as cruise ships. In many cases, the evacuation process is complicated by constraints on space and movement, such as corridors, staircases, and passageways, that can cause congestion and slow the evacuation process. In such circumstances, the Internet of Things (IoT) can be used to sense the presence of evacuees in different locations, to sense hazards and congestion, to assist in making decisions based on sensing to guide the evacuees dynamically in the most effective direction to limit or eliminate congestion and maximize safety, and notify to the passengers the directions they should take or whether they should stop and wait, through signaling with active IoT devices that can include voice and visual indications and signposts. This paper uses an analytical queueing network approach to analyze an emergency evacuation system, and suggests the use of the Pull Policy, which employs the IoT to direct evacuees in a manner that reduces downstream congestion by signalling them to move forward when the preceding evacuees exit the system. The IoT-based Pull Policy is analyzed using a realistic representation of evacuation from an existing commercial cruise ship, with a queueing network model that also allows for a computationally very efficient comparison of different routing rules with wide-ranging variations in speed parameters of each of the individual evacuees.Numerical examples are used to demonstrate its value for the timely evacuation of passengers within the confined space of a cruise ship. Full article

European and national maritime regulations, aimed at promoting navigation powered by alternative fuels, highlight the need to explore the adoption of various alternative fuel options for maritime transport. This assessment should consider both technical and practical aspects, particularly for freight and passenger services, within the national context in which the sector operates. This document provides a detailed analysis of what is available on the market and the expected results between 2030 and 2050 for the conversion of routes using alternative fuel vessels, both in terms of investment and operational costs. Assessments of vessel fuelling needs were conducted, identifying the potential of different fuels on several key Italian routes, reconstructing their technical characteristics and considering the uncertainty associated with potential changes in fuelling costs (over the life of the vessels) and technological progress. Full article

In the construction of large cruise ships, the restricted deck space and dense obstacles create a strongly coupled problem between path planning and sequence optimization during prefabricated cabin boarding operations, significantly impairing overall installation efficiency. To coordinately optimize the boarding sequence of multiple cabins and minimize operational conflicts, this study proposes a dual-layer coordinated planning methodology. The lower layer generates feasible paths satisfying kinematic and contour-based obstacle avoidance constraints through optimal control theory, while the upper layer introduces a dynamic priority evaluation mechanism based on grid mapping and an “enclosure factor”, combined with a reverse planning strategy to dynamically adjust the cabin boarding sequence. Through iterative feedback between path feasibility and sequence efficiency, the proposed method effectively resolves the strong coupling between sequencing and path planning. Case validation demonstrates that the proposed approach significantly reduces total installation time compared to conventional sequence planning methods, proving its effectiveness and practical value in enhancing the efficiency of coordinated multi-cabin installation. Full article

It is recognized that a ship’s performance, speed, fuel consumption, and resistance are impacted by the marine environment. The magnitude of this effect, which can be altered by ship design and operational conditions, necessitates added resistance calculations for optimizing these phases. Ship designers can generate efficient hull forms and operators can make sound navigational decisions to reduce emissions within the service zone. For this research, air and wave resistances were calculated using the KCS hull form with a superstructure during a simulated voyage in the North Pacific Ocean. To verify the results, data from towing tank tests available in the literature were used, along with calm water resistance calculations obtained from a computational fluid dynamics (CFD) analysis conducted for this study. When transporting 3600 loaded containers, sea conditions at model-scale impact the ship’s power requirements, leading to air resistance from the superstructure (aerodynamic) and hull resistance from head waves. This research compares the increased wave and air resistance with calm water resistance to provide important insights into the main engine power requirements when traveling in this region. Cruising between 14 and 18 knots generates 8–11% added resistance when encountering head waves at Sea State 5. Full article