1,720,996 research outputs found
A new calculation technique for onboard progressive flooding simulation
No full textDuring a flooding emergency, the master has to take hard decisions with serious impact on passengers and crew safety. A fast and reliable time domain simulation of the progressive flooding process can significantly aid the master in choosing the right counteractions immediately after the damage occurrence. In last decades many methods to simulate progressive flooding have been developed with increasing precision, but most of them require too much computational effort being not suitable for a direct onboard application. This paper presents a novel quasi-static simulation technique capable to provide accurate results in a reasonable calculation time. The analytical solution of the linearised system of governing differential equations allows to extend the time step over the intrinsic limits of numerical integration methods without affecting accuracy. The approach has been compared with numerical integration of non-linear system of equations and a recent pressure correction technique on a box-barge test case available in the literature
Big data opportunities for the port and maritime transport sector in the Adriatic region
Full text linkBig data technologies offer new opportunities for the port and maritime industry in both freight and passengers transport. In order to ensure the success of a new big data project in a specific environment, it is essential to assess the benefits and the efforts required by its implementation. The present work addresses this topic for a specific area: the Adriatic region. Several relevant stakeholders from the selected area have been inquired to assess the relevance and deployment difficulties for a set of promising big data technologies. The study provides a picture of the current state and the future outlook for the Adriatic region, being useful for local operators and a valuable example to be replicated in other contexts
Prediction of Manoeuvring Characteristics in the Concept Design of a Destroyer
Full text linkManoeuvring is one of the fundamental qualities of the ship. It has a direct impact on the operability of the unit and therefore on the shipowner’s perception of quality. Furthermore, the manoeuvrability forecasting models are extremely sensitive to the geometry of the hull and appendages and thus closely related with the type of the unit. In this article, an innovative methodology for predicting the manoeuvring characteristics during the conceptual design phase is presented. It may be applied to all types of vessels, especially those requiring a specific study of manoeuvrability, such as fast hulls. Here, a destroyer has been considered. Starting from 15 hulls geometries, a fleet of 225 ships has been generated, by changing systematically the ratio L/B, B/T and the block coefficient CB. This way a 3-dimensional Central Composite Circumscribed (CCC) has been obtained, that comprehends a total of 15 experimental points for each base hull. Manoeuvring calculations has been performed on each vessel of the fleet and the main manoeuvring dimensionless quantities has been related to some simple variables, known during the conceptual phase. With a greedy approach, the adjusted coefficient of determination R2 has been maximized. This way, from the collected data, the best possible linear models for manoeuvring characteristics are obtained. This is because no statistical significance filtering of the variables is performed, as instead happens in the classic stepwise approach
On the Effect of Uncertainties on Onboard Progressive Flooding Simulation
No full textNowadays, the quasi-static techniques devoted to progressive flooding simulation are present in the literature. Most of them can be applied onboard to support crew decisions after a flooding casualty. However, in real scenarios, the input parameters, adopted to carry out time domain simulations, are often not accurately assessed or even unknown. The aim of this paper is to study the effect of these uncertainties affecting the damage geometry, the ship geometry and the loading condition at damage occurrence. A sensitivity study on the relevant input parameters has been carried out on a box-shape barge, showing that most of them have a strong influence on progressive flooding simulation. Regarding damage geometry which is directly connected to damage detection algorithms, the internal subdivision geometry has a stronger impact compared with damage location and area. Further study is required, especially when internal spaces are connected by small openings. Nevertheless, the paper highlights the importance of an accurate preparation of ship model and assessment of loading condition, providing some insights on these problems
Extreme loads determination on complex slender structures
No full textFor the dimensioning of particular structures like stingers or generic tubular elements for offshore industry, it is usual to predict the extreme values of wave induced loads. Both for model test and calculations, the traditionally adopted methods of analysis are based on Weibull distribution. The necessity to investigate severe sea state conditions together with the increased complexity of the structure is an evident source of non-linearities in the exciting force peaks distribution. In the specific, the adoption of a standard Weibull approach is not indicated for accurately predict the extreme loads. The adoption of more accurate distributions suitable to capture peaks non-linearity will ensure to overcome or capture possible multi-modal behaviour of the considered population. These enhanced techniques can be used not only for model test results analysis, but also for results coming from preliminary hydrodynamic calculations (CFD). In the present work, two different methodologies based on Mixed Weibull and Generalised Pareto distributions will be applied to the results obtained for a stinger geometry, where Morison theory is adopted to evaluate wave loads considering shield effects between the single tubular elements
Exploring a Flooding-Sensors-Agnostic Prediction of the Damage Consequences Based on Machine Learning
Full text linkRecently, progressive flooding simulations have been applied onboard to support decisions during emergencies based on the outcomes of flooding sensors. However, only a small part of the existing fleet of passenger ships is equipped with flooding sensors. In order to ease the installation of emergency decision support systems on older vessels, a flooding-sensor-agnostic solution is advisable to reduce retrofit cost. In this work, the machine learning algorithms trained with databases of progressive flooding simulations are employed to assess the main consequences of a damage scenario (final fate, flooded compartments, time-to-flood). Among the others, several classification techniques are here tested using as predictors only the time evolution of the ship floating position (heel, trim and sinkage). The proposed method has been applied to a box-shaped barge showing promising results. The promising results obtained applying the bagged decision trees and weighted k-nearest neighbours suggests that this new approach can be the base for a new generation of onboard decision support systems
A Comparison of Different Linearized Formulations for Progressive Flooding Simulations in Full-Scale
Full text linkIn the framework of Industry 4.0, simulation plays a key role in processing sensors data to predict the future behaviour of a complex system. Aiming to increase ship efficiency and safety, simulations can be used in normal conditions but also during an emergency. In this context, progressive flooding simulations can be applied onboard large passenger ships to support master decisions after a collision or grounding casualty. Among the methods present in literature, the techniques based on linearized differential equations have been recently proposed and tested in model-scale. Here, the effects of three different linearized techniques are studied on a large passenger ship. The main issues connected to different mathematical formulations are highlighted, to enhance the reliability of the onboard progressive flooding simulation and better exploit data collected by sensors to increase ship safety in the framework of Shipping 4.0
Limiting Environment Determination for an Offshore Vessel
No full textThe design of an offshore vessel requires the combination of multiple aspects typical of naval architecture and marine engineering. Between them, the definition of environmental loads and excitation is relevant, since it is required to evaluate motion operability, dynamic positioning capability and structure dimensions. These three topics traditionally refer to independent analyses and are treated in separate design stages. Moreover, the techniques and the calculations performed to asses the performances of the vessel under design differ topic by topic, referring to different limiting environmental conditions. This paper presents a comparison between the different limiting environment determination for the assessment of ship motion, dynamic positioning and maximum design loads for structures. In particular, advanced analysis methods are applied on a reference vessel to highlight the differences between station keeping, sea keeping and structural loads limiting environment. A combined representation of station keeping and seakeeping data is then used to compare the vessel operability issues with recommended design loads
Ship design assessment through virtual prototypes
Full text linkAbstract
The traditional design process has been developed, through time, by trial and error, following an evolutive approach. By following this procedure,
the design team focused its attention on only one conceptual design alternative at a time, which is perfected step by step until the expected
outcome is obtained. Nevertheless nowadays, due to the high complexity of ships and increasingly stringent operational requirements, this
approach appears to be obsolete in a market where cost and time reduction is a fundamental parameter. Indeed, to be competitive in the
shipbuilding market, very accurate information should be available since the beginning of the process, to allow the design team a 360-degree
exploration of a high number of alternatives and then identify the best design solution in no time.
In this paper a new, rational, design process, necessary to raise efficiency and effectiveness of ship design, is presented. By using a multi-purpose
design software, the authors were able to create a Virtual Prototype of a case study ship with ease and little training, obtaining, since early-stage
design phases, some outputs of interest (such as longitudinally weight distribution of ship structures, preliminary midship section, GZ curves and
powering curves) without great computational efforts. The most important benefit of using only one multipurpose software instead of multiple
specific ones lies in the elimination of remarking activities for switching from one software to another, reducing loss of data’s risks during the
process
The use of Bluetooth Beacons in Maritime Emergencies Mobile safety and security - DigLogs pilot project by University of Trieste
Full text linkThe aim of this paper is to research and describe how the use of mobile technologies can help in reducing the time required for the ship evacuation and abandonment procedures, as it was identified within the scope of 2014 - 2020 Interreg V-A Italy - Croatia CBC Programme “Digitalising Logistics processes - DIGLOGS” project. Furthermore, main findings and opportunities for proving technical feasibility will be identified and presented along with a carefully selected and envisaged test scenario chosen to compare the standard evacuation time with the one related to the adoption of the mobile technologies, the final goal being the streamlined evacuation procedures, and the increase of the ship's security and target group stakeholders' satisfaction
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