Wyniki wyszukiwania - BazTech

1

Estimation of hydrodynamic coefficients from results of real ship sea trials

Kim D.

Polish Maritime Research

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2018

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nr 4

65--72

EN

This paper suggests an estimation method for ship’s hydrodynamic coefficients, which is based on the system identification method that calculates an optimum value in a mathematical way. For the purpose of modelling existing ships, this study collects real ship sea trial data as benchmarks. Prior to the optimization, a sensitivity analysis is carried out for easy and effective optimization. The simulation results using optimized coefficients agree well with corresponding benchmarks. Following this, with various trim and draught conditions, this study suggests new estimation formulas that concern all trim and draught conditions. Simulation results applying the estimation formulas are satisfactory in regard to a corresponding benchmark, compared to a result obtained by using an existing regression formula.

2

Numerical Analysis for the Dynamic Forces and Operational Risk Accomplished for a “Hiload DP1” Unit Docked to MT “Navion Anglia” at Sea Waves

Rutkowski G.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2014

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Vol. 8 no. 4

505--512

EN

In this paper author depicts the results of the sea trials of the operational test of a Hiload technology at sea waves with the numerical analysis for the dynamic forces and operational risk. The research was carried out on board MT “Navion Anglia” which was engaged in a towing operation through the Atlantic Ocean with a “Hiload DP1” prototype unit docked on her portside alongside, with different ship’s draft and in different weather conditions. Additionally in this paper author presents the methods that can be used for estimating the safety factor SF against sliding and/or operational risk for the towing and/or manoeuvring operation with a “Hiload DP1” unit docked alongside at the open sea.

3

Examination of the co-operation between echosounder and motion sensor during sea trials

Szymczak W., Buszman K.

Hydroacoustics

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2009

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Vol. 12

217-226

EN

Sea trials with parametric echosounder SES-2000 Compact needs precise information about sounded area of the seafloor. Because of narrow beam both in horizontal and vertical surface each change of antenna position have high influence for results and analyze of measured data. Vessel has to be equipped with a special device, such as multibeam echosounder, to obtain more information about seafloor sounding which is an addition for basic measurements units. Information about bottom topography, from where sounding pulse comes, may give many useful data necessary to correct analyze by echosounder user. There are also parameters such as roll, pitch and heave, which have to be complied. These variables have an influence for shape and echo level. The last parameter analyzed in this article is a difference between vessels heading and bearing. This information comes from heading sensor and GPS receiver.

4

Bistatic sonars: sea trials, laboratory experiments and future surveys

Blondel P., Pace N. G.

Archives of Acoustics

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2009

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Vol. 34, No. 1

95-109

EN

Bistatic sonars use separate transmitter and receiver(s), optimising the information received from seabed/target(s) scattering. Laboratory experiments are ideal to understand scattering processes and to optimise data collection strategies. They can be full-scale or scaled down. In the latter case, the influence on bistatic scattering processes needs to be carefully weighed, to validate the transition to full-scale experiments. This is particularly relevant as sea trials are expensive, difficult to conduct, and generally impossible to repeat. This article presents the results from: (1) scaled experiments on bare seabed and targets, performed at Bath and other places; (2) full-scale experiments in the GESMA submarine pens during the EC-SITAR project and (3) sea trials from similar experiments in Italy and Sweden. These results are put into the wider context of other international efforts. These three approaches (scaled and full-scale experiments plus sea trials) can be used in synergy. This has important implications for future experiments, the design of surveys and instruments, and analyses of past/future acoustic datasets.

5

Ship Manoeuvring Auxiliary Differential Equations for Optimal Sea Trials Programme Design

Artyszuk J.

Zeszyty Naukowe / Akademia Morska w Szczecinie

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2005

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nr 6 (78)

11-20

EN

The present study compactly demonstrates the drift-nondimensional yaw correlation limit for a wide range of accelerated turning tests and zigzag tests based on manoeuvring simulation. Next, the problem of tracking an arbitrary drift angle-nondimensional yaw velocity trajectory (important in the identification of hull hydrodynamic forces) is solved by means of two differential equations with derivatives versus drift angle. Finally, additional valuable sets of differential equations are formulated with the travelled distance or heading as an independent variable - most of manoeuvring commands relate to those parameters, as to be easily observed and having both navigational and hydrodynamic significance.

PL

Przedstawiono kilka wartościowych równań różniczkowych ruchu, które są pomocne przy projektowaniu prób morskich zawierających najwięcej informacji potrzebnych w identyfikacji lub weryfikacji matematycznego modelu manewrowania. W odniesieniu do znanych manewrów, dobrym przykładem jest tutaj pełna gama prób przyspieszonej cyrkulacji lub wężowych. Podano również rozwiązanie problemu sterowań koniecznych do osiągnięcia zadanej trajektorii kąt dryfu względna prędkość kątowa.