A Simulation Model for a Hybrid-Electric Craft in Restricted Waters

Sustainable mobility is one of the most challenging issues for passenger transport inside environmental protected areas and ecologically fragile environments. To reduce the pollutant emissions, the adoption of electric or hybrid-electric solutions for crafts propulsion is a suitable option for green navigation. However, the operation in restricted basin leads also to specific critical issues for the vessel sailing, as dealing with shallow or restricted waters and transit under low air-gap bridges. The combination of these constraints with the adoption of a hybrid-electric propulsion system increases the design difficulties also for a small craft, requiring the use of advanced simulation models to assess the vessel performances. This work presents a simulation model for a small passenger craft that will operate in the Grado Lagoon. The model combines the hydrodynamic issues of manoeuvring and propulsion in restricted water with the simulation of the electric loads and capacity of the energy storage system installed onboard. The simulations performed with the developed simulation system are in accordance with data measured during trials on a prototype of the vessel. The developed model is a powerful tool for designers in order to rapidly assess the green capabilities of new projects since the early design stages

MaxHadoop: An Efficient Scalable Emulation Tool to Test SDN Protocols in Emulated Hadoop Environments

AbstractThis paper presents MaxHadoop, a flexible and scalable emulation tool, which allows the efficient and accurate emulation of Hadoop environments over Software Defined Networks (SDNs). Hadoop has been designed to manage endless data-streams over networks, making it a tailored candidate to support the new class of network services belonging to Big Data. The development of Hadoop is contemporary with the evolution of networks towards the new architectures "Software Defined." To create our emulation environment, tailored to SDNs, we employ MaxiNet, given its capability of emulating large-scale SDNs. We make it possible to emulate realistic Hadoop scenarios on large-scale SDNs using low-cost commodity hardware, by resolving a few key limitations of MaxiNet through appropriate configuration settings. We validate the MaxHadoop emulator by executing two benchmarks, namely WordCount and TeraSort, to evaluate a set of Key Performance Indicators. The tests' outcomes evidence that MaxHadoop outperforms other existing emulation tools running over commodity hardware. Finally, we show the potentiality of MaxHadoop by utilizing it to perform a comparison of SDN-based network protocols

SRTP assessment of passenger ships: a simulation tool

Recent years have seen increasing attention being paid towards the problems related to safety and security onboard ships. As a result, the International Maritime Organization has issued several new Regulations regarding ships\u2019 systems that must be considered during the vessel design phases. In particular, one of the most important approaches introduced by this set of rules consists of the Safe Return to Port (SRtP) concept: basically, the ship itself represents its best lifeboat. Essential systems on-board passenger ships shall be designed in order to both guarantee their functionality and allow the return of the ship to the nearest port during specific emergency situations. Consequently, it is evident that designers should pay great attention to these systems since the early stages of the project. In this framework, proper IT design tools able to simulate systems functionality can represent a valuable aid to ensure compliance with the SRtP requirements. In this paper, the basic principles of SRtP Regulations are thoroughly presented. Furthermore, an IT tool, specifically implemented to address the suggested design approach for ship systems, is analyzed

A Simulation Model for Hybrid-Electric Inland Waterway Passenger Vessels

The increasing focus on air pollution reduction for transportation systems requires to adopt new technologies and innovative solutions to limit vehicles emissions. In case of inland waterway transportation (IWT), once vessels have to operate close to urban areas or in natural reserves, the necessity to provide a \u2019green navigation\u2019 is of primary importance. With this specific aim, especially for small crafts, the adoption of an hybrid-electric power system grant a significant pollution reduction, leading also to a possible Zero Emission Mode (ZEM) navigation. However, the particular configuration of inland waterways makes the estimation of vessels\u2019 hydrodynamic performances harder compared to a seagoing ship, because of restricted waters effects, affecting both resistance and manoeuvring characteristics. For this purpose, time domain simulation program has been developed to estimate the effective power demand of an inland vessel during a specific route. The program has been tested on the specific case of a passenger vessel designed for the Grado lagoon, where all the reference route bathymetric data were available. By means of the simulations it has been possible to state whether the vessel is suitable to operate in ZEM mode during the service

Limiting Environment Determination for an Offshore Vessel

The 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

Integrated ship design: an innovative methodological approach enabled by new generation computer tools

Ships currently built in the western market, and in particular in Italy, can be considered highly complex and technological. The main products of this market are passenger ships, military ships, mega-yachts, and offshore supply vessels. As opposed to what happens for other vehicles of comparable complexity and cost (i.e., airplanes), the time available to deliver a ship is rather limited. The design process of large complex ships, therefore, requires a long and resource-intensive development cycle. Indeed, it must foresee both the compliance with specific technical and regulatory requirements and the containment of ship\u2019s CAPital EXpenditure and OPerating EXpense. Moreover, particular attention must be given to decisions made during the early-stage design, because of their large impact on ship functionality and overall configuration. In order to reduce execution times and costs, computer tools are currently used. However, since they very often are not integrated, time-consuming remaking activities, able to reduce the design robustness, are necessary. To overcome this issue, several software have been developed to implement the innovative integrated design methodology. In this paper, after a review of both the modern ship acquisition process and the computer tools available on market, a new methodological approach is presented. Specifically, it is shown how the integrated use of new design tools can lead to the rapid and undemanding implementation of a ship\u2019s virtual prototype, in order to enable the proof-of-concept of new technologies, already in the early-stage design

Early-Design Issues of a Gas Propelled Escort Tug

Tethered escort of ships is performed by specially designed tugs linked by a tow-line to a strong point aft of the assisted ship. In fact, the tug is called to control the course and speed of the assisted ship in an emergency situation), so reducing the risk of grounding or collision. A substantial number of studies about ship casualties shows the grounding as the predominant accident when the ship is approaching the harbour or narrow fairways. In order to take part in escort operations, a tug must be provided with the additional service notation escort tug, which confirms its specific capabilities in accordance with particular stability criteria that will be harmonised by International Maritime Organisation from 2020. In case the tug should be propelled with Liquefied Natural Gas, then dedicated issues related to containment system should be solved. Through this paper, an overview will be given upon the possible escort operations that an escort tug could face during his operational life, together with the possible types/configurations of tugs that can be used for this kind of operations. Moreover an example will be given on the determination of escort performances by means of a self developed code on a sample tug

Integrated Ship Design and CSI Modeling: A New Methodology for Comparing Onboard Electrical Distributions in the Early-Stage Design

In recent years, the MVDC distribution has been proposed as a viable solution for the redesign of the shipboard Integrated Power System (IPS). Indeed, there are relevant advantages promised by the innovative DC concept, among others a desirable reduction in the electric power system size. For providing a virtual proof-of-concept of this technology, parametric and interactive 3D models can be developed by a new Computer System Integrator (CSI) software. The latter may give the possibility to quantify the expected onboard benefits (i.e. increase of pay load) already during the early-stage design, thus opening interesting evaluation since the very first stage of ship design. By exploiting the capabilities offered by the integrated design methodology, a comparative analysis between a conventional MVAC electrical distribution and innovative MVAC/MVDC hybrid systems is performed in this paper. In particular, a significant Main Vertical Zone of a large cruise ship is modeled by the CSI software for providing a detailed comparison (volumes/weights) among the power distribution architectures (MVAC vs hybrid MVAC/MVDC)

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