scholarly journals Simulation Modeling of a Ship Propulsion System in Wavesfor Control Purposes

2021 ◽  
Vol 10 (1) ◽  
pp. 36
Author(s):  
Maria Acanfora ◽  
Marco Altosole ◽  
Flavio Balsamo ◽  
Luca Micoli ◽  
Ugo Campora
Keyword(s):  
Dynamic Instability ◽  
Dynamic Performance ◽  
Weather Conditions ◽  
Propulsion System ◽  
Point Of View ◽  
Ship Motions ◽  
Electric Motors ◽  
Parametric Roll ◽  
Linear Behavior ◽  
Engine Dynamic

The article deals with a simulation approach to the representation of the ship motions in waves, interacting with the propulsion system behavior (diesel engine and propeller). The final goal is the development of a simulator, as complete as possible, that allows the analysis of the main engine thermodynamics in different sea conditions, also in the unfavorable event of dynamic instability of the hull, and the correct management of the other propulsion components. This latter aspect is particularly interesting in some of the last new energy solutions for decarbonization of ships, concerning, for example, auxiliary electric motors, powered by batteries, to support the traditional diesel-mechanical propulsion (especially in heavy weather conditions). From this point of view, a proper analysis of the engine dynamic performance, affected by particular sea states, is fundamental for a smart management and control of shaft generators/auxiliary electric motors, batteries, etc. To this end, the work presents and highlights the main features of a ship simulator, suitable for the study of the new propulsion solutions that are emerging in maritime transport. Some representative results will point out the complex non-linear behavior of the propulsion plant in waves. Moreover, a parametric roll scenario will be investigated, in order to highlight the capability of the conceived simulator in modeling the effects of the dynamic instability of the hull on the propulsion plant.

scholarly journals Smoothing warships movements based on wavelets

2013 ◽  
Vol 6 (12) ◽  
pp. 51
Author(s):  
J.M. Riola ◽  
J.M. Girón ◽  
J.J. Díaz
Keyword(s):  
Weather Conditions ◽  
Point Of View ◽  
Ship Motions ◽  
Main Question ◽  
Measurement Systems ◽  
Quiescent Period ◽  
Wave Measurement ◽  
Key Issues ◽  
The Waves ◽  
Initial Measurement

In seakeeping terminology, the Quiescent Period is known as the period of calm in rough waters to allow the ship to perform operations such as landing aircrafts and unmanned aerial vehicles (UAVs), aswell as the entry of landing crafts in the basin. Quiescence refers to the interval of time where all ship motions are within acceptable limits to perform a desired activity. Among the key issues for Quiescent Period Prediction is to be able to measure waves from a suitable distance and predict ship motions in response to waves encountered; both aspects are crucial and must be taken into account. Many of the opearations performed at sea are carried under severe weather conditions, as a result of this situation there is a need to determine this called “window of opportunity” that allows carrying them out. The paper aims to explain from the point of view of Quiescent Period Prediction, the most promising wave measurement systems, which are currently based on radar, but the main question is that if we want predictions a few seconds ahead, it will be appropriate to measure waves at a distance of some hundreds of meters, describing the new mathematical model based on wavelets in determining the spread of the waves from their initial measurement until they reach the vessel.

Effectiveness of Flood Protection Project Valuation Methods

2015 ◽  
Vol 10 (3) ◽  
pp. 275-289
Author(s):  
Tadeusz Liziński ◽  
Marcin Bukowski ◽  
Anna Wróblewska
Keyword(s):  
Essential Element ◽  
Weather Conditions ◽  
Point Of View ◽  
Flood Protection ◽  
Costs And Benefits ◽  
Protection Measures ◽  
Investment Projects ◽  
Market Values ◽  
Project Valuation ◽  
The Subject

Projects for flood protection are increasingly the subject of investment projects in the field of water management. This is related to the increasing frequency of worldwide threats caused by extreme weather conditions, including extremely high rainfall causing floods. Technical and nontechnical flood protection measures are also increasing in importance. In the decision-making process, it is necessary to take into account both the costs and benefits of avoiding losses, including an analysis of social benefits, whose valuation of non-market goods is an essential element. A comprehensive account of projects in the field of flood protection based on the estimated costs and benefits of the investment allows the economic efficiency from a general social point of view to be determined. Previous evaluations of the effectiveness of investment projects have mainly taken into account only categories and market values. The aim of the article is to identify the possibilities to expand the values of non-market assessments and categories formulated on the basis of the theoretical economics of the environment. 

scholarly journals Design and Field Validation of a Low Power Wireless Sensor Node for Structural Health Monitoring

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1050
Author(s):  
Federico Zanelli ◽  
Francesco Castelli-Dezza ◽  
Davide Tarsitano ◽  
Marco Mauri ◽  
Maria Laura Bacci ◽  
...  
Keyword(s):  
Low Power ◽  
Sensor Node ◽  
Weather Conditions ◽  
Point Of View ◽  
Design Stage ◽  
Monitoring Systems ◽  
Wireless Sensor Node ◽  
Process Data ◽  
Fatigue Life Estimation ◽  
Remaining Fatigue Life

Smart monitoring systems are currently gaining more attention and are being employed in several technological areas. These devices are particularly appreciated in the structural field, where the collected data are used with purposes of real time alarm generation and remaining fatigue life estimation. Furthermore, monitoring systems allow one to take advantage of predictive maintenance logics that are nowadays essential tools for mechanical and civil structures. In this context, a smart wireless node has been designed and developed. The sensor node main tasks are to carry out accelerometric measurements, to process data on-board, and to send wirelessly synthetic information. A deep analysis of the design stage is carried out, both in terms of hardware and software development. A key role is played by energy harvesting integrated in the device, which represents a peculiar feature and it is thanks to this solution and to the adoption of low power components that the node is essentially autonomous from an energy point of view. Some prototypes have been assembled and tested in a laboratory in order to check the design features. Finally, a field test on a real structure under extreme weather conditions has been performed in order to assess the accuracy and reliability of the sensors.

Aero-engine dynamic model based on an improved compact propulsion system dynamic model

2021 ◽  
pp. 095965182098408
Author(s):  
Qiangang Zheng ◽  
Yong Wang ◽  
Chongwen Jin ◽  
Haibo Zhang
Keyword(s):  
Dynamic Model ◽  
Propulsion System ◽  
System Dynamic ◽  
Inlet Temperature ◽  
System Dynamic Model ◽  
Component Level ◽  
Engine Model ◽  
Surge Margin ◽  
Aero Engine ◽  
Engine Dynamic

The modern advanced aero-engine control methods are onboard dynamic model–based algorithms. In this article, a novel aero-engine dynamic modeling method based on improved compact propulsion system dynamic model is proposed. The aero-engine model is divided into inlet, core engine, surge margin and nozzle models for establishing sub-model in the compact propulsion system dynamic model. The model of core engine is state variable model. The models of inlet, surge margin and nozzle are nonlinear models which are similar to the component level model. A new scheduling scheme for basepoint control vector, basepoint state vector and basepoint output vector which considers the change of engine total inlet temperature is proposed to improve engine model accuracy especially the steady. The online feedback correction of measurable parameters is adopted to improve the steady and dynamic accuracy of model. The modeling errors of improved compact propulsion system dynamic model remain unchanged when engine total inlet temperature of different conditions are the same or changes small. The model accuracy of compact propulsion system dynamic model, especially the measurable parameters, is improved by online feedback correction. Moreover, the real-time performance of compact propulsion system dynamic model and improved compact propulsion system dynamic model are much better than component level model.

Optimization of Restoration Paths of Power System after Blackout

2013 ◽  
Vol 347-350 ◽  
pp. 1467-1472
Author(s):  
Wen Wei Huang ◽  
Gang Yao ◽  
Xiao Yan Qiu ◽  
Nian Liu ◽  
Guang Tang Chen
Keyword(s):  
Power System ◽  
Transmission Lines ◽  
Reactive Power ◽  
Minimum Spanning Tree ◽  
Operation Time ◽  
Combinatorial Problem ◽  
Weather Conditions ◽  
Recovery Process ◽  
Point Of View ◽  
Improved Genetic Algorithm

Optimization of restoration paths of power system after blackout is a multi-stage, multi-target, multi-variable combinatorial problem in the power system restoration. This paper presents a reasonable model and effectually method. The proposed model is considered as a typical partial minimum spanning tree problem from the mathematical point of view which considering all kinds of constraints. Improved data envelopment analysis (DEA) was used to get the weight which considering line charging reactive power, weather conditions, operation time and betweenness of transmission lines. The improved genetic algorithm method is employed to solve this problem. Finally, an example is given which proves the strategy of the line restoration can effectively handle the uncertainty of the system recovery process, to guarantee the system successfully restored after the catastrophic accidents.

Dynamic Instability in Quartering Seas—Part III: Nonlinear Effects on Periodic Motions

1997 ◽  
Vol 41 (03) ◽  
pp. 210-223 ◽  
Author(s):  
K. J. Spyrou
Keyword(s):  
Periodic Motion ◽  
Horizontal Plane ◽  
Dynamic Instability ◽  
Parametric Instability ◽  
Nonlinear Effects ◽  
Ship Motions ◽  
Nonlinear Phenomena ◽  
Specific Sequence ◽  
The Stability ◽  
Two Stages

The loss of stability of the horizontal-plane periodic motion of a steered ship in waves is investigated. In earlier reports we referred to the possibility of a broaching mechanism that will be intrinsic to the periodic mode, whereby there will exist no need for the ship to go through the surf-riding stage. However, about this point the discussion was essentially conjectural. In order to provide substance we present here a theoretical approach that is organized in two stages: Initially, we demonstrate the existence of a mechanism of parametric instability of yaw on the basis of a rudimentary, single-degree model of maneuvering motion in waves. Then, with a more elaborate model, we identify the underlying nonlinear phenomena that govern the large-amplitude horizontal ship motions, considering the ship as a multi-degree, nonlinear oscillator. Our analysis brings to light a very specific sequence of phenomena leading to cumulative broaching that involves a change in the stability of the ordinary periodic motion on the horizontal plane, a transition towards subharmonic response and, ultimately, a sudden jump to resonance. Possible means for controlling the onset of such undesirable behavior are also investigated.

A Probabilistic Study of the Simultaneous Effect of Ship Motions on the Cargo Shifting Onboard

1996 ◽  
Vol 33 (01) ◽  
pp. 25-34
Author(s):  
Jianbo Hua
Keyword(s):  
Transfer Functions ◽  
Simulation Method ◽  
Point Of View ◽  
Roll Angle ◽  
Ship Motions ◽  
Vertical Acceleration ◽  
Simultaneous Effect ◽  
Strip Theory ◽  
Probabilistic Study ◽  
Mean Wave Period

Cargo movement aboard ship can occur even in waves that produce only moderate rolling motion. It is caused when the simultaneous effect of vertical acceleration, horizontal acceleration and roll motion on the cargo onboard—defined as the equivalent roll angle—becomes sufficiently large for the problem to develop. In this paper, an analytical expression is derived for the probabilistic calculation of the equivalent roll angle, which has a nonlinear characteristic. Also, a so-called indirect time-domain simulation method is described for calculating the problem. Both methods are based on motion transfer functions calculated according to strip theory. The calculations presented here show both methods to be in good agreement. A probabilistic calculation of the equivalent roll angle of a roll-on/roll-off (RO/RO) ship is carried out using the two methods and focusing on parameters such as significant wave height, mean wave period, ship speed, and relative course angle. It is proved from the point of view of probability that the nonlinearity of equivalent roll angle results in a magnifying effect on its extreme value. The calculation shows also that in severe wave conditions large peak values of equivalent roll greater than 35 deg can be experienced by the studied RO/RO ship.

scholarly journals Analysis of Wave Energy Conversion with Dynamic Systems Theory

2019 ◽  
Vol 103 ◽  
pp. 02003
Author(s):  
Sorin Ciortan ◽  
Eugen Rusu
Keyword(s):  
Dynamic System ◽  
Energy Conversion ◽  
Wave Energy ◽  
Prediction Models ◽  
Weather Conditions ◽  
Point Of View ◽  
The Black Sea ◽  
Time Range ◽  
Wave Energy Conversion ◽  
Dynamic System Theory

In wave energy conversion one of the most important steps is building scenarios about long term efficiency, taking into account that several factors are involved. Based on the assumption that actually the weather conditions show important modifications year by year, analyses of wave power evolution during the exploitation time range must rely on both prediction models and on several options for the conversion device. From this point of view, the wave energy conversion process can be considered a dynamic system. The dynamic system theory based methodology approach systems behaviour through relationships between systems components. Comparing to usual scientific approaches, which try to decompose the analyzed system, this methodology offers a view of entire system behaviour The paper presents a method for building scenarios of wave energy conversion, in the nearshore of the Black Sea, based on a model which includes also forecasts of the weather influence.

scholarly journals Waiting for Breakthrough in Conventional Submarine’s Prime Movers

2019 ◽  
Vol 8 (1) ◽  
pp. 37-45
Author(s):  
Tomasz Lus
Keyword(s):  
Diesel Engines ◽  
Technological Development ◽  
High Reliability ◽  
Lithium Ion ◽  
Armed Forces ◽  
Propulsion System ◽  
Point Of View ◽  
Statistical Research ◽  
Heavy Load ◽  
Most Significant Change

Submarines, as a very expensive and sophisticated type of weaponry, are being intensively exploited by the armed forces of many countries. This means that submarines are sent ever longer patrols, sometimes to distant regions. To meet such requirements, submarine sub-systems and components must have high reliability and operational readiness indicators. Among the many machines and devices found on submarines, the ones that generate, store, and consume energy (mainly electricity) deserve special attention. The largest energy consumers on the submarine are the components of its propulsion system. One of the most complicated and loaded devices on board submarine is a power generator with a diesel engine driving it, on whose continuous and reliable work the safe performance of tasks depends. According to statistical research, despite its importance for the process of performing tasks by submarines, diesel engines are still the least reliable devices on submarines. Despite the constant technological development of piston engines, their work in very difficult conditions under heavy load and at high counter-pressure at the exhaust outlet promotes their malfunction and damage. From this point of view, the development of charge air systems for submarine diesel engines based on the construction experience of MTU Company is described in the paper. The classification of submarines, their propulsion systems, and the working conditions of engines on submarines are presented in the paper. Air-Independent Propulsion (AIP) systems with their applications on chosen submarines are also described. The most significant change in submarine propulsion system observed in 2018, transition from lead-acid to lithium-ion batteries, is also presented.

scholarly journals Dynamic response mitigation of floating wind turbine platforms using tuned liquid column dampers

2015 ◽  
Vol 373 (2035) ◽  
pp. 20140079 ◽  
Author(s):  
V. Jaksic ◽  
C. S. Wright ◽  
J. Murphy ◽  
C. Afeef ◽  
S. F. Ali ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Dynamic Performance ◽  
Weather Conditions ◽  
Liquid Column ◽  
Dynamic Responses ◽  
Floating Structure ◽  
Energy Devices ◽  
Wave Basin ◽  
Liquid Column Dampers ◽  
Output Only

In this paper, we experimentally study and compare the effects of three combinations of multiple tuned liquid column dampers (MTLCDs) on the dynamic performance of a model floating tension-leg platform (TLP) structure in a wave basin. The structural stability and safety of the floating structure during operation and maintenance is of concern for the performance of a renewable energy device that it might be supporting. The dynamic responses of the structure should thus be limited for these renewable energy devices to perform as intended. This issue is particularly important during the operation of a TLP in extreme weather conditions. Tuned liquid column dampers (TLCDs) can use the power of sloshing water to reduce surge motions of a floating TLP exposed to wind and waves. This paper demonstrates the potential of MTLCDs in reducing dynamic responses of a scaled TLP model through an experimental study. The potential of using output-only statistical markers for monitoring changes in structural conditions is also investigated through the application of a delay vector variance (DVV) marker for different conditions of control for the experiments.

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