Hasil untuk "Naval architecture. Shipbuilding. Marine engineering"

Bo-Ram Kim, Jeongmin Cheon

This study investigates the impact of reducing waiting times for port berth on improving the Carbon Intensity Indicator (CII) ratings of Korean-flagged container ships. As the International Maritime Organization (IMO)’s CII regulation mandates corrective actions for poorly rated ships for Greenhouse Gas (GHG) reduction in international shipping, the analysis focuses on container ships with projected D or E ratings by 2035. Using Automatic Identification System (AIS) data from ships, this study identifies annual waiting times and simulates changes in CII ratings under scenarios of reduced waiting times (30%, 50%, 70%, and 100%). The relationship between ship speed and fuel consumption was established by analyzing the recent literature, and the CII improvement was evaluated based on IMO Data Collection System (DCS) 2022 data. The results show that a 30% reduction in waiting time can lower CO₂ emissions by 12.18% and improve the CII rating by one or two levels for approximately half of the sample ships. However, a 50% reduction or more is required to maintain improved ratings beyond 2030. The findings highlight the significance of just-in-time (JIT) practices in minimizing latency and enhancing regulatory compliance. The policy recommendations advocate for prioritizing port call optimization and recommend the adoption of JIT as a measure to achieve the IMO’s GHG reduction targets.

Liangyong Chu, Jiachen Lin, Xiyao Xu et al.

With the rapid advancement of battery technology, new energy hybrid tugboats have been progressively adopted. In order to align with the trend of electrifying tugboat fleets, a mixed-integer linear programming (MILP) model for the joint scheduling of new energy hybrid tugboats and berths has been established. The model incorporates the constraint imposed by the limited number of tugboat charging connectors. The objective is to minimize the total cost over the scheduling horizon, including ship waiting, delayed-departure costs, and the operating costs of both conventional diesel and hybrid tugboats. In light of the characteristics inherent to the problem, a hybrid solution approach combining CPLEX with a heuristic-enhanced whale optimization algorithm (WOA) is employed to solve the model. A case study was conducted using data on the energy consumption of tugboats at Xiamen Port. The effectiveness of the model and algorithm was then verified through a series of small-scale instance experiments. Finally, a comprehensive sensitivity analysis of key parameters is finally conducted, including the number of tugboat charging connectors, battery capacity, and charging rate. This analysis provides valuable guidance for port tugboat operations.

Yuanyuan Zhang, Guangyu Li, Jianfeng Zhu et al.

The presence of sea ice threatens low ice-class vessels’ navigation safety in the Arctic, and traditional Navigation Risk Assessment Models based on sea ice parameters have been widely used to guide safe passages for ships operating in ice regions. However, these models mainly rely on empirical coefficients, and the accuracy of these models in identifying sea ice navigation risk remains insufficiently validated. Therefore, under the binary classification framework, this study used Automatic Identification System (AIS) data along the Northeast Passage (NEP) as positive samples, manual interpretation non-navigable data as negative samples, a total of 10 machine learning (ML) models were employed to capture the complex relationships between ice conditions and navigation risk for Polar Class (PC) 6 and Open Water (OW) vessels. The results showed that compared to traditional Navigation Risk Assessment Models, most of the 10 ML models exhibited significantly improved classification accuracy, which was especially pronounced when classifying samples of PC6 vessel. This study also revealed that the navigability of the East Siberian Sea (ESS) and the Vilkitsky Strait along the NEP is relatively poor, particularly during the month when sea ice melts and reforms, requiring special attention. The navigation risk output by ML models is strongly determined by sea ice thickness. These findings offer valuable insights for enhancing the safety and efficiency of Arctic maritime transport.

Shijie LI, Taixu LIU, Jialun LIU et al.

ObjectiveThis study aims to solve the problem of path-following control under environmental disturbances and model uncertainties, especially the effects of external wind and wave environments. MethodBased on a model predictive control (MPC) controller, improved model-free adaptive control (IMFAC) is introduced as the path following control compensator. The error between the ship's actual state and predicted state is corrected to solve the problem of the insufficient accuracy of the model under environmental disturbances such as sudden crosswinds and external wind waves, thereby improving the precision of path-following control. ResultsShip path-following control simulation experiments are conducted with a scaled-down KVLCC2 ship model. As the results show, compared with traditional MPC control, the MPC-IMFAC method reduces the maximum absolute heading error of the ship by 25.4% under sudden disturbances, and the average absolute heading error decreases by 2.6% under time-varying environmental disturbances. ConclusionThe simulation results verify that this control method possesses superior anti-interference ability while ensuring path-following control accuracy.

Wei RUAN, Hai HUANG, Jianying HONG et al.

Due to the poor bias repeatability and large random noise of a micro electro mechanical system (MEMS), the Allan variance was used to analyze the random angle walk of MEMS. The information fusion algorithm of array gyro was designed by using Allan variance identification value and weighted least square method, which could effectively reduce the random angle walk and respond to the true angular rate in real time under both static and dynamic conditions. For the constant drift of MEMS gyro, a two-position calibration scheme was designed combined with the observability of the error of the inertial navigation system, so as to complete system-level calibration of constant drift. Simulation results show that the method proposed in this paper effectively reduces the random angle walk and the constant drift of MEMS gyro and significantly improves the inertial measurement accuracy of MEMS.

Tabassum Rasul, Koena Mukherjee

This paper showcases a data-driven non-linear adaptive controller design employing an unfalsification approach to attain optimal estimates for unknown parameters in an autonomous underwater vehicle (AUV). These estimates are applied to the controller to enable precise trajectory tracking. The controller design presented is capable of adapting to parametric changes and uncertainties while fulfilling the desired performance criteria using an effective parameter update method of unfalsification. The results were validated through simulations conducted using MATLAB/SIMULINK.

CHEN Nü, XU Wenhao, WU Biao, CHEN Xiaowen, HOU Dongwei

In order to investigate the evolution of pore structures in cementitious materials, a statistical model is proposed by taking the cement paste as a random dispersion system of two-phase medium. Simultaneously, the μic platform is employed to simulate the cement hydration. The results obtained from the simulation and the disperse models are compared with each other, and further analysis on calculation conditions and parameters of the disperse models are conducted. The pore size distribution obtained from polydisperse hard sphere model is very close to the simulation in completely dispersion condition. Taking into account the cross and agglomeration effects of hydrated products, the calculation results of the monodisperse concentric-shell model are more consistent to the simulations. Considering the flocculation of cement particles in initial state, the monodisperse hard model is closer to the simulation results. This paper offers a new insight from the viewpoints of mathematics and physics to understand and describe the pore structures of cementitious materials.

Mengxiang Li, Guo Wang, Kun Liu et al.

The safety assessment of ship cargo securing systems is of significant importance in preventing casualties, vessel instability, and economic losses resulting from the failure of securing systems during transportation in adverse sea conditions. In this study, an independently designed cylindrical cargo securing scheme with supporting structures was adopted for investigation. Utilizing a sway device, three-degree-of-freedom coupled motion encountered during ship transportation was obtained, and data regarding changes in the support forces at the foundations and tension forces in the lashing ropes were collected. Subsequently, numerical simulations were conducted using the multibody dynamics software ADAMS 2020. The results obtained from the simulations were compared with the experimental data. The overall tendencies were accurately predicted in the numerical analysis. It was observed that the difference of the peak support forces between the numerical simulation results and the experimental data were within a 10% margin. In terms of the lashing ropes, the difference was limited, within 9%. These findings demonstrate that numerical simulation techniques can provide valuable insights for verifying the safety of practical cargo securing systems.

Zhenquan Wei, Jinfeng Ma, Gaowen He et al.

Shallow-water carbonate rocks constitute a crucial component of large guyots, arising in distinct environments and harboring valuable insights into the evolutionary stages of seamount islands as well as the tectonic conditions of the underlying oceanic plate. Laser Ablation Multi-Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) was used to conduct in situ U–Pb isotope dating of carbonate minerals with low uranium content collected from Weijia Guyot. This dating approach yielded crucial evidence for the vertical development of the seamount. Our study indicates that shallow-water carbonate rocks in Weijia Guyot had a temporal range between 91 My and 137 My. The carbonate rocks underwent two growth phases, Hauterivian to Barremian and Cenomanian to Turonian, with a hiatus of approximately 20 My. Since the Hauterivian age, the shield volcano of Weijia Guyot is essentially complete, with its seamount top exposed at or near sea level and receiving its first stage of shallow-water carbonate sedimentation. Based on the dating of both shallow-water carbonate rocks and hawaiite within the Weijia Guyot, it is inferred that approximately 10 My elapsed from shield-building volcanism to late alkalic volcanism. During the Turonian age, the main reason for the second phase of shallow-water carbonate rocks in the seamounts was the regional tectonic uplift triggered by the drift of the Weijia Guyot along with the Pacific Plate toward the Society hotspot.

Charalampos Nikolaos Roukounis, Vasiliki K. Tsoukala, Vassilios A. Tsihrintzis

The aim of this study is to assess the resilience of coastal urban areas and their exposure to sea-level rise and coastal flooding, using the proposed Coastal Resilience Index (CResI). The CResI is an innovative combination of diverse characteristics. It includes 19 parameters and is implemented using GIS techniques. The parameters included in the CResI are classified into six category factors (geomorphology, flooding, wave exposition, land use, socioeconomic, and infrastructure/functional). The Analytic Hierarchy Process is used to assign weights and rank the parameters. The framework is tested in the southwest waterfront of the Athens Metropolitan Area in Greece. The study identified that around 25% of the coastal area could be at risk of coastal flooding in the upcoming years, including areas in both the metropolitan and suburban environments. As a result, the need for adaptation measures cannot be overlooked.

Zhang Wanchao, Zhu Yang, Liu Shuxu et al.

To obtain the mechanical energy of waves from arbitrary directions, the vibration absorbers of wave energy converters (WEC) are usually vertically axisymmetric. In such case, the wave-body interaction hydrodynamics is an essential research topic to obtain high-efficiency wave energy. In this paper, a semi-analytical method of decomposing the complex axisymmetric boundary into several ring-shaped stepped surfaces based upon the boundary approximation method (BAM) is introduced and examined. The hydrodynamic loads and parameters, such as the wave excitation forces, added mass and radiation damping of the vertical axisymmetric oscillating buoys, can then be achieved by using the new boundary discretisation method. The calculations of the wave forces and hydrodynamic coefficients show good convergence with the number of discretisation increases. Comparison between the constringent results and the results of the conventional method also verifies the feasibility of the method. Then, simulations and comparisons of the hydrodynamic forces, motions and wave power conversions of the buoys with series draught and displacement ratios in regular and irregular waves are conducted. The calculation results show that the geometrical shape has a great effect on the hydrodynamic and wave power conversion performance of the absorber. In regular waves, though the concave buoy has the lowest wave conversion efficiency, it has the largest frequency bandwidth for a given draught ratio, while in irregular waves, for a given draught ratio, the truncated cylindrical buoy has the best wave power conversion, and for a given displacement of the buoy, the concave buoy shows the best wave power conversion ability.

Alessandro Zambon, Lorenzo Moro, Jeffrey Brown et al.

Polar navigation entails challenges that affect the continuation of ship operations in severe ice conditions. Due to ice-propeller interaction, propulsion shafting segments are often at a high risk of failure. Efficient methods for shaft line design are hence needed to ensure the safety of ice-going vessels and propulsion reliability. To this end, full-scale measurements have proven essential to support the development of ship-design tools and updated safety regulations for ice-going vessels. This paper presents a unique integrated measurement system that employs measuring equipment to monitor Polar-Class vessel performance and shaft line dynamics during ice navigation. The system was installed on board the Canadian Coast Guard (CCG) icebreaker Henry Larsen. This experimental concept aims to monitor the shaft’s torque and thrust fluctuations during ice navigation to obtain information about the ship’s propulsion efficiency. In the paper, we describe the arrangement of the measurement system and the components it features. Finally, we present preliminary datasets acquired during two icebreaking expeditions. This work is framed into a broader research project, which includes the long-term objective to determine a correlation between sea ice conditions and the dynamic response of shaft lines.

Iosif Progoulakis, Nikitas Nikitakos, Paul Rohmeyer et al.

In an ever-evolving technological industry, the oil and gas sector is already moving forward through the adaptation of Industry 4.0 and the adaptation of advanced cyber technologies through Oil and Gas 4.0. As IT/OT (information technology/operational technology) systems are evolving technologically, so are the cyber security threats faced by the offshore oil and gas assets. This paper aims to raise the awareness of cyber security threats and the organizational and technical measures that need to be adopted by the oil and gas industry for remote and complex assets in the upstream sector. A comprehensive literature review covering the areas of new IT/OT systems integration and cyber security risk analysis and management is presented. The results of a survey on the subject of cyber security for offshore oil and gas assets are also presented, and they provide valuable insight into the current industry culture and the perception of cyber security concepts. The importance of organizational culture, personnel training and involvement, as well as corporate engagement and support in the subject of cyber security is highlighted.

Fenghui Han, Zhe Wang, Hefu Zhang et al.

Temperature is a key variable to evaluate the energy consumption and thermodynamic performance of traditional marine auxiliary machinery, chillers and piping systems. In particular, for the cryogenic storage tanks and fuel gas supply systems of LNG ships, explosion-proof and low-temperature-resistance properties bring new challenges to the onboard temperature measurement and monitoring. In order to promote the development of high-performance and safer monitoring systems for LNG ships, this paper adopted fiber Bragg grating (FBG) technology to ensure the measurement safety and accuracy of temperature sensors, and performs a series of experiments in a large temperature range on the chiller, pipeline, and cryogenic storage tank of an LNG ship and their long-term reliabilities. Firstly, the principle and composition of the designed FBG temperature sensors are introduced in detail, and the measurement accuracy and range of different metal-coated optical fibers were tested in a large temperature range and compared against the traditional thermistors. Then, the effects of different operating conditions of the LNG marine chiller system and cryogenic storage tank on the temperature measurements were investigated. In addition, the drift degrees of the optical fibers and industrial thermistors were analyzed to figure out their reliabilities for long-term temperature measurements. The results showed that for the long-period (16 months) monitoring of LNG ships in a large temperature range (105–315 K) under different shipping conditions, the optical temperature measurement based on FBG technology has sufficient accuracy and dynamic sensitivity with a higher safety than the traditional thermoelectric measurement. Besides, the ship vibration, ambient humidity, and great temperature changes have little impact on its measurement reliability and drifts. This research can provide references and technical supports to the performance testing systems of LNG ships and other relevant vessels with stricter safety standards.

Ognjen Bonacci, Duje Bonacci, Matko Patekar et al.

The Adriatic Sea and its coastal region have experienced significant environmental changes in recent decades, aggravated by climate change. The most prominent effects of climate change (namely, an increase in sea surface and air temperature together with changes in the precipitation regime) could have an adverse effect on social and environmental processes. In this study, we analyzed the time series of sea surface temperature and air temperature measured at three meteorological stations in the Croatian part of the Adriatic Sea. To assess the trends and variations in the time series of sea surface and air temperature, different statistical methods were employed, i.e., linear and quadratic regressions, Mann–Kendall test, Rescaled Adjusted Partial Sums method, and autocorrelation. The results evidenced increasing trends in the mean annual sea surface temperature and air temperature; furthermore, sudden variations in values were observed in 1998 and 1992, respectively. Increasing trends in the mean monthly sea surface temperature and air temperature occurred in the warmer parts of the year (from March to August). The results of this study could provide a foundation for stakeholders, decision–makers, and other scientists for developing effective measures to mitigate the negative effects of climate change in the scattered environment of the Adriatic islands and coastal region.

B. Zaman

The International Conference on Marine Technology, which is more popular known as SENTA, is an annual conference organized by the Faculty of Marine Technology, Institut Teknologi Sepuluh Nopember (ITS) Surabaya, Indonesia. Since 2001, the Faculty of Marine Technology – ITS has organized the annual SENTA conference, formerly known as Seminar Nasional Teknologi dan Aplikasi Kelautan (National Conference on Marine Technology and Application), which provided a regular forum for researchers and engineers in Marine Technology in Indonesia. Then in 2016, SENTA conference has turned into an international conference in order to expand its research network. Due to the Covid-19 pandemic situation, The 5th International Conference on Marine Technology (SENTA 2020) held virtually on 8 December 2020. All honourable authors contributed to the conference through submissions of their research papers on all topics related to “Transformation from Archipelagic into Maritime States for Prosperous Indonesia”, including, but not limited to: Naval Architecture, Ship Production and Material Technology, Marine Robotics and Digital Ship Technology, Marine and Safety Engineering, Marine Renewable Energy, Offshore and Coastal Engineering, Shipping, Port and Maritime Logistic, also Maritime Education Training. All of the authors presented their manuscript in two plenary sessions divided into eight rooms according to their topics through zoom platform. Each author delivered their presentation for about 12 minutes. On behalf of SENTA committee, I would like to extend gratitude to all the authors who contribute to the submission of the result of their latest research. The committee of SENTA received 113 submissions. From those submissions, there were 78 papers that were presented in SENTA 2020. All the accepted paper has passed the criteria and has been reviewed by the reviewer and then the authors has revised it according to the reviews. 73 papers were accepted for publication. Also, I would like to express my grateful to the Technical Program Committee and the reviewers for their support in the reviewing process to keep the quality of manuscripts. List of Program Committees, Organizing Committees, reviewers, Organizer, Supporter are available in this pdf.

Beatrice Fenu, Valentino Attanasio, Pietro Casalone et al.

The energy innovation scenario sees hybrid wind-wave platforms as a promising technology for reducing the variability of the power output and for the minimization of the cost of offshore marine renewable installations. This article presents a model that describes the installation of a 5 MW wind turbine on a floating platform designed by Fincantieri and equipped with gyroscopic stabilization. The use of gyros allows for the delivery of platform stabilization by damping the wave and wind induced motion on the floater and at the same time producing extra power. Shetland Island was chosen as the reference site because of its particularly harsh weather. Final results show that the total production of power in moderate and medium climate conditions is considerable thanks to the installation of the gyro, together with a significant stabilization of the platform in terms of pitching angle and nacelle acceleration.

Toshio Yamazu, Koshi Haraguchi, Takahiko Inoue et al.

We have developed new a deep-towed seismic streamer for sub-bottom profiling. To obtain a high-resolution seismic signal, this streamer can be operated at depths of up to 2000 m, and state-of-the-art technology is adopted with electronics circuits, that can withstand high pressures of up to 22 MPa. The streamer houses an ultra-low noise pre-amplifier, micro-processor, AD convertor, high precision clock, gain controller, and other circuitry in an oil-filled vessel. The high S/N ratio gives us high-resolution seismic images. The streamer comprises several catenated single modules and the recorded acoustic data are transmitted to the control computer with the Ethernet protocol. This makes the length of the streamer cable, and the number of hydrophones, flexible. For instance, we can use both single-channel and multi-channel streamers in the same system. Up to 24-channels can be catenated.

Antonio Chinhenha, Janusz Mindykowski

This paper deals with the assessment methodology for the impact of combined cycle plant characteristics on the quality of the produced electrical power. The aim of this work is to develop the assessment methodology with the use of an algorithm based on a flowchart of the system. The research methodology includes an analysis of the non-steady state phenomena with use of a MATLAB-Simulink environment and an analysis of the steady-state phenomena based on the theoretical calculations and analytical models of a combined cycle plant of the COGES type, connected with the processes of producing and converting of thermal and electrical power in the considered systems. A key point of the study is to check that the voltage frequency modulation on the shaft of the gas turbine is included in the limits defined by the appropriate requirements of the related IEEE Std 45TM-2002 standard.

Rozmarynowski Bogdan, Mikulski Tomasz

The paper deals with sensitivity and reliability applications to numerical studies of an off-shore platform model. Structural parameters and sea conditions are referred to the Baltic jack-up drilling platform. The sudy aims at the influence of particular basic variables on static and dynamic response as well as the probability of failure due to water waves and wind loads. The paper presents the sensitivity approach to a generalized eigenvalue problem and evaluation of the performace functions. The first order time-invariant problems of structural reliability analysis are under concern.