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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Design and hydrodynamic performance of trimaran displacement ships

Zhang, Junwu January 1997 (has links)
To meet the demands for increasing the speed and improving the seakeeping behaviour of commercial and naval ships, this thesis investigates a new type of ship configuration - The Trimaran Displacement Ship, it features a slender centre hull and two small side hulls. The design methodology and hydrodynamic performance of this new ship concept has been investigated through design studies, model experiments and theoretical analysis. Potential advantages of the trimaran ship are, lower wavemaking resistance at high speed, larger deck area, and improved seakeeping behaviour compared with existing ship types. Firstly, existing marine vessel types, both monohulls and multihulls, are reviewed with regard to their advantages and limitations. The new trimaran concept and its background is then described from its initiation by a desire of inheriting advantages and avoiding limitations of these existing ship types. Namely, achieving the low resistance of slender monohulls and large deck area of multihulls, whilst eliminating the speed limit of conventional monohulls and the stiff roll motion of catamarans. The review of the trimaran ships design studies shows the potential applications of this new concept in commercial and naval roles. The feasibility of the new concept and the methodology required for its design are investigated through the concept design studies of. a trimaran fast ferry (Figure 1) and the hull form design for a trimaran model ship (Figure 2) for seakeeping experiments. This provides an initial view on the design procedure and basic design considerations for the trimaran ship. The parametric study in the trimaran ferry design gives the basic parameters for trimaran hull forms. Hydrodynamic performance of the trimaran ship has been investigated through model experiments and theoretical analysis on seakeeping, resistance, and manoeuvrability. Good agreements between theoretical predictions and model experiments have been achieved. This shows the merit of the computer programs developed during the investigation so they can be used in future trimaran ship designs for hydrodynamic performance assessments. A three dimensional theory is used in the trimaran motion analysis. Roll damping characteristics of the trimaran ship has been examined by including viscous effects in roll damping which can be derived either by simulating damping data from free decay experiments or by direct computation, that has been shown to improve the roll motion predictions. Systematic investigation into the wavemaking resistance of the trimaran ship reveals the relationship between the side hull configuration and the resistance performance. Wave cancellation effects can be achieved when the side hulls are appropriately located to further reduce the wavemaking resistance of the trimaran ship. A manoeuvrability study concentrated on the effect of the side hulls on the turning ability of the trimaran ship as well as the effect of side hull propulsion. Following the hydrodynamic analysis of the trimaran ship, the design procedure and general considerations in trimaran ship design distinctive from other ship types are proposed and discussed with particular reference to stability and hydrodynamic performance. Trimaran hull form options are also discussed alongside some other design considerations. The thesis concludes that the new trimaran displacement ship shows superior characteristics in some hydrodynamic aspects over existing marine vessels, particularly in resistance and seakeeping, and therefore there is no reason why this novel concept can not be translated into real ships.
2

Προηγμένος ευρετικός έλεγχος πλοίου

Φώτου, Φώτιος 04 December 2012 (has links)
Στο πλαίσιο αυτής της διπλωματικής εργασίας μελετήθηκε το σύστημα του πλοίου και η απόκρισή του σε διάφορες εισόδους και αναπτύχθηκε κατάλληλη μέθοδο ελέγχου σύμφωνα με τη δεδομένη πειραματική διάταξη. Ο στόχος του ελεγκτή είναι από ένα αρχικό τυχαίο σημείο με αρχικό τυχαίο προσανατολισμό το πλοίο να προσεγγίσει ένα τελικό επιθυμητό σημείο και να σταθεροποιηθεί σε όσο δυνατόν μικρότερη απόσταση από αυτό.Για την επίτευξη αυτού του στόχου υλοποιήθηκε εμπειρικός ελεγκτής πρόσω δράσης. / This thesis adresses the control of a ship vessel. To accomplish this goal, the response of a model vessel to several control actions was recorded and a control algorithm based on this response was developed. The final goal was to approach a desired point on the horizontal plane having started from a random point and having random orientation at the starting point .
3

GOVERNOR ELECTRONICS FOR DIESEL ENGINES : High availability platform for real-time control and advanced fuel efficiency algorithms

Holmström, Johnny January 2013 (has links)
Fossil fuel is a rare commodity and the combustion of this fuel results in negative environmental effects. This paper evaluates and validates the electronics needed to run intelligent algorithms to lower the fuel consumption for commercial vessels. This is done by integrating advanced fuel saving functions into an electronic device that controls the fuel injection of large diesel engines, as known as a diesel engine governor. The control system is classified as a safety critical system. This means that the electronics needs to be designed for fail safe operation. To allow for future research and development, the platform needs flexibility in respect to hardware reconfiguration and software changes, i.e. this is the basis for a system that allows for hardware-software co-design. For efficient installation and easy commissioning, the system shall allow for auto-calibration combined with programmable jumper selections to attain a cost effective solution. The computation of the fuel saving algorithm require accurate data to build a model of the vessels motions. This is achieved by integrating state of the art sensors and a multitude of communication interfaces. Among other things gyroscopes contra accelerometers where evaluated to find the best solution in respect to cost and performance. This design replace the current product DEGO III. The new product requires the same functionality and shall allow for more functions. Focus has been spent on communication, methods of accruing sensor data and more computation speed. In creating a new generation of a product there are tasks like selecting components, questions pertaining to layout of the printed circuit board and an evaluation of supply chains. The manufacturing aspects are considered to rationalize production and testing. / Fossila bränslen är en dyrbar råvara och förbränningen av detta bränsle leder till negativa miljöeffekter. Detta papper utvärderar och verifierar elektroniken som behövs för att beräkna intelligenta algoritmer som minskar bränsle konsumtionen för kommersiella fartyg. Detta görs genom att sammanfoga avancerade funktioner i en och samma elektroniska enhet som kontrollerar bränsle insprutningen på stora diesel motorer, denna elektronik är känd som en varvtals regulator. Kontroll systemet är klassificerat som ett säkerhetskritiskt system. Detta betyder att elektroniken måste utformas för att vara felsäker. För att tillåta framtida forskning och utveckling behöver plattformen vara flexibel. Den ska tillåta konfiguration av hårdvara och mjukvara ändringar. Samverkan mellan hårdvara och mjukvara. För effektiv installation samt drifttagning, måste systemet vara automat-kalibrerande och utrustat med programmerbara byglingar som möjliggör en kostnadseffektiv lösning. Beräkningen av bränsle optimeringen behöver en detaljerad modell av fartygets rörelse. Detta möjliggörs genom att integrera moderna sensorer och en mängd olika kommunikationsmedier. Bland annat så utvärderades gyroskop kontra accelerometrar för att hitta den bästa lösningen i förhållande till kostnad och kvalitet. Denna design ersätter den nuvarande produkten DEGO III. Den nya produkten behöver samma funktionalitet samt en mängd nya funktioner. Fokus har varit kommunikation, metoder för att samla sensordata och ökad beräknings kraft. När en ny generation av en produkt ska utvecklas finns uppgifter så som att välja komponenter, frågor gällande mönsterkorts layout och en utvärdering av leverantörs källor. Tillverkningen av prototypen inkluderar utvärdering av produktions metoder för att effektivisera tillverkning och verifiering.
4

Modeling, optimization and environmental assessment of electrified marine vessels

Manouchehrinia, Babak 21 December 2018 (has links)
Electrified Vehicles (EVs), including Hybrid Electric Vehicles (HEVs) and Pure Electric Vehicles (PEVs), can provide substantial improvements in energy efficiency, emission reduction, and lifecycle cost over conventional vehicles solely powered by Internal Combustion Engines (ICE). Progress on electrification of marine vessels has been made, but the pace has been impacted by factors such as the different operational load profile of vessels, relatively small production levels and longer or varied lifetimes. In this dissertation, hybrid electric and pure electric propulsion system designs for fishing boats and passenger ferries are studied based on in-field acquired operational data. A new integrated marine propulsion system modeling and simulation method and a dedicated mobile data acquisition system have been introduced to analyze the energy efficiency, emission reduction, and lifecycle costs of new or retrofitted fishing boats and passenger ferries with hybrid electric and pure electric powertrains. Following the automotive industry Model Based Design (MBD) approach, modeling and simulation of electrified vessels using the acquired operation profile have been carried out using backward and forward-facing methods. Series hybrid electric and pure electric powertrain system designs with powertrain component models and rule-based system control, including a properly sized electric Energy Storage System (ESS) with a Supercapacitor (SC) or battery, have been studied. The total CO2 equivalent (CO2e) or Greenhouse Gas (GHG) emissions and lifecycle costs of various new, electrified vessel propulsion system designs have been evaluated. Clean propulsion system solutions for fishing boats and passenger ferries with detailed powertrain system and control system designs are given which provide a foundation for further research and development. This dissertation also addresses the environmental impact of Natural Gas (NG) as a transportation fuel, particularly for marine transportation use. A systematic evaluation of GHG emissions is provided for the upstream fuel supply chain of natural gas fuel in British Columbia (BC), Canada. The Liquefied Natural Gas (LNG) lifecycle GHG emissions produced in both the upstream supply chain and the downstream vessel propulsion are estimated quantitatively using manufacturer data and propulsion system models of marine vessels. Extensive data have been collected from oil and gas companies that have active operations in BC to determine the upstream supply chain GHG emissions of the NG fuel under three scenarios. The energy efficiency and emissions of natural gas engines are compared with traditional diesel fuel marine engines and generators. The results obtained indicate that LNG fuel can lower CO2e by 10% to 28% with reduced local air pollutants such as sulfur oxides and particulates, compared to conventional diesel fuel. However, engine methane slip during combustion should be monitored as it can have a significant impact on the GHG emissions and so offset the environmental benefits of LNG. / Graduate
5

Ocean Waves Estimation : An Artificial Intelligence Approach

Ramberg, Andreas January 2017 (has links)
This thesis aims to solve the mathematical inverse problem of characterizing sea waves based on the responses obtained from a marine vessel sailing under certain sea conditions. By researching this problem the thesis contributes to the marine industry by improving products that are using ocean behavior for controlling ship's dynamics. Knowledge about the current state of the sea, such as the wave frequency and height, is important for navigation, control, and for the safety of a vessel. This information can be retrieved from specialized weather reports. However, such information is not at all time possible to obtain during a voyage, and if so usually comes with a certain delay. Therefore this thesis seeks solutions that can estimate on-line the waves' state using methods in the field of Artificial Intelligence. The specific investigation methods are Transfer Functions augmented with Genetic Algorithm, Artificial Neural Networks and Case-Based Reasoning. These methods have been configured and validated using the n-fold cross validation method. All the methods have been tested with an actual implementation. The algorithms have been trained with data acquired from a marine simulation program developed in Simulink. The methods have also been trained and tested using monitored data acquired from an actual ship sailing on the Baltic Sea as well as wave data obtained from a buoy located nearby the vessel's route. The proposed methods have been compared with state-of-the art reports in order evaluate the novelty of the research and its potential applications in industry. The results in this thesis show that the proposed methods can in fact be used for solving the inverse problem. It was also found that among the investigated methods it is the Transfer Function augmented with Genetic Algorithm which yields best results. This Master Thesis is conducted under the Master of Engineering Program in Robotics at Mälardalens högskola in Västerås, Sweden. The thesis was proposed by Q-TAGG R&D AB in Västerås, Sweden, a company which specializes in marine vessel dynamics research.

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