![]() The paper describes the proposed method in details, and illustrates it with the study of a ship-shaped floating unit in a sea-state of relevance for the fatigue design of mooring systems (steep waves, low return period). From the wave elevation, and estimated load time series, the difference-frequency QTF is finally estimated by a cross-bi-spectral analysis, including a new treatment of statistical noise. Then, by deconvolution and optimization, LF damping and added-mass loads, as well as a response-independent wave excitation load, can be evaluated. The resulting system can be successively tuned to different frequency ranges of interest. The method is based on an active stationkeeping system that enables to accurately control external boundary conditions applied on the floating structure in a wave basin. ![]() We present here an empirical method that reliably estimates the oscillators parameters and quadratic transfer function (QTF) used in such models. ![]() Low-frequency (LF) motions of floating structures are commonly modeled as the response of an oscillator to a second-order wave excitation. Copyright © 2015 by the International Society of Offshore and Polar Engineers (ISOPE). This requires that a single irregular time series with force measurements on a fixed structure should be incorporated in the experimental test program when the estimation of the QTF is of interest. It is recommended to apply the method based on a measured wave force signal on a fixed structure. The method was found in general to be applicable for estimating the QTF. ![]() For the floating structure some discrepancies were seen between measured and reconstructed motions. For the real case example where wave force measurements from the fixed structure was applied a good agreement was found between measured forces and those reconstructed based on the estimated QTF. The synthetic test signal showed that the method is capable of reproducing the test QTF. The method was validated by three test cases: 1) a synthetic response signal generated based on a known QTF, 2) a measured force signal on a fixed structure, and 3) a measured surge displacement signal on a floating moored structure. The aim is to develop a practical engineering tool that, based on a limited number of irregular sea states, can estimate the QTF for a floating structure. In the present study, a method based on a time-domain analysis of measurements of forces or motion responses of a floating structure was implemented. This is a time consuming and tedious approach. One method for experimental determination of the QTF involves a large number of bi-chromatic wave conditions in order to cover the two-dimensional frequency space that defines the QTF. This serves as input in the design phase of e.g. With the QTF for a specific floating moored structure the slow drift forces acting on the structure can be estimated. MACH classification society rules.This paper describes and validates a method for estimating quadratic transfer functions (QTF) for floating structures based on model experiments with irregular wave loading.She was built to RINA (Registro Italiano Navale) C ✠ HULL Her water tanks store around 2,800 Litres of fresh water. Powered by twin diesel MTU (16V 2000 M93) 2,434hp engines, she comfortably cruises at 24 knots, reaches a maximum speed of 28 knots. Range & Performanceīuilt with a GRP hull and GRP superstructure, with teak decks, she has impressive speed and great efficiency thanks to her planing hull. Her features include WiFi and air conditioning. She is also capable of carrying up to 4 crew onboard to ensure a relaxed luxury yacht experience. Xwave has been designed to comfortably accommodate up to 10 guests in 5 suites comprising one cabin that can operate as twin or double. This luxury vessel's exterior design is the work of Francesco Paszkowski Design. Her interior is styled by design house Marty Lowe and she was delivered to her owner in July 2018. The 32.2m/105'8" motor yacht 'Xwave' was built by Sanlorenzo in Italy at their Ameglia shipyard. ![]()
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