PROBABILISTIC SAFETY OF ESTUARY VESSELS BASED ON NONLINEAR ROLLING IN WIND AND WAVES

2021 ◽  
Vol 152 (A1) ◽  
Author(s):  
I Bačkalov
Keyword(s):  
Safety Assessment ◽  
Irregular Waves ◽  
Classical Approach ◽  
Safety Regulations ◽  
Wind Gusts ◽  
General Investigation ◽  
Significant Step ◽  
Nonlinear Rolling ◽  
Vessel Motion ◽  
Ship Safety

The author was previously involved in the development of the risk-based stability analysis which is now further extended, and used for the safety assessment of estuary container vessels subjected to stochastic action of beam wind and irregular waves. The study was motivated by the new set of safety regulations for estuary vessels issued by Belgian authorities in cooperation with Lloyd’s Register. These regulations introduce very innovative probabilistic ideas to ship stability regulations, and therefore present a significant step forward compared to the classical approach. Still, they do not account properly some important influences, such as wind gusts and motion nonlinearities, so considerably simplify the problem. The present investigation models the vessel motion much more realistically, analyzes the influence of beam wind and beam waves on the probability of a stability failure, and argues whether simplifications proposed by the regulations were justified. It is believed that presented method is not limited to the safety of estuary vessels only, but also gives important guidelines for a more general investigation of ship safety in wind and waves.

PROBABILISTIC SAFETY OF ESTUARY VESSELS BASED ON NONLINEAR ROLLING IN WIND AND WAVES

2021 ◽  
Vol 152 (A3) ◽  
Author(s):  
I Bačkalov
Keyword(s):  
Safety Regulations ◽  
Linear Approach ◽  
Scientific Background ◽  
Non Linear ◽  
Significant Step ◽  
General Improvement ◽  
Nonlinear Rolling ◽  
The Stability ◽  
Ship Safety ◽  
Probabilistic Safety

In the first place the discusser would like to congratulate Dr. Bačkalov with his paper, in which he assesses the new Belgian safety regulations for estuary vessels by means of a non-linear approach taking account the effect of a combination of beam waves and unsteady beam wind. The results presented are based on a solid, scientific background, and the author’s approach as published in former papers can be considered as the base of a promising methodology for evaluating the stability and safety of a vessel in waves and wind. As the discusser has supported the Belgian federal authorities in defining the methodology and formulating the present regulations, it is a pleasure to learn that the implementation of the latter is considered as a significant step in the general improvement of ship safety regulations.

Structural Safety Assessment of a 1100 TEU Container Ship, Based on a Enhanced Long Term Fatigue Analysis

2014 ◽  
Vol 1036 ◽  
pp. 935-940
Author(s):  
Leonard Domnisoru ◽  
Ionica Rubanenco ◽  
Mihaela Amoraritei
Keyword(s):  
Safety Assessment ◽  
Safety Evaluation ◽  
Irregular Waves ◽  
Structural Safety ◽  
Random Wave ◽  
Wave Loads ◽  
Strength Assessment ◽  
Integrated Method ◽  
Hydroelastic Response

This paper is focused on an enhanced integrated method for structural safety assessment of maritime ships under extreme random wave loads. In this study is considered an 1100 TEU container test ship, with speed range 0 to 18 knots. The most comprehensive criteria for ships structural safety evaluation over the whole exploitation life is based on the long term ship structures analysis, that includes: stress hot-spots evaluation by 3D/1D-FEM hull models, computation of short term ship dynamic response induced by irregular waves, long term fatigue structure assessment. The analysis is enhanced by taking into account the ships speed influence on hydroelastic response. The study includes a comparative analysis on two scenarios for the correlation between the ships speed and waves intensity. The standard constant ship speed scenario and CENTEC scenario, with total speed loss at extreme waves condition, are considered. Instead of 20 years ship exploitation life estimated by classification societies rules from the long term structural safety criteria, the enhanced method has predicted more restrictive values of 14.4-15.7 years. The numerical analyses are based on own software and user subroutines. The study made possible to have a more realistic approach of ships structural strength assessment, for elastic and faster ships as container carriers, in compare to the standard one based only on naval rules, delivering a method with higher confidence in the designed structural safety.

The JNC Generic URL Research Program - Providing a Knowledge Base to Support both Implementer and Regulator in Japan

2006 ◽  
Vol 932 ◽  
Author(s):  
Hiroyuki Umeki ◽  
Kazuhiko Shimizu ◽  
Toshihiro Seo ◽  
Akira Kitamura ◽  
Hirohisa Ishikawa
Keyword(s):  
Knowledge Base ◽  
Safety Assessment ◽  
Atomic Energy Commission ◽  
Phase 1 ◽  
Site Characterization ◽  
Crystalline Rock ◽  
Know How ◽  
Safety Regulations ◽  
Site Characteristics ◽  
Underground Research Laboratory

ABSTRACTIn accordance with the R&D framework specified by the Atomic Energy Commission of Japan in 2000 for the implementing phase of HLW disposal, the Japan Nuclear Cycle Development Institute (JNC) continues to be responsible for R&D activities aimed at enhancing the reliability of disposal technologies and safety assessment methodologies and associated databases. JNC has thus been actively promoting technical R&D with a view to contributing to both the implementation of disposal and the formulation of safety regulations.One of JNC's key roles is to establish and demonstrate site characterization methodologies based on investigations in two purpose-built generic URL (underground research laboratory) projects: one at Mizunami in crystalline rock and the other at Horonobe in sedimentary rock.Through the surface-based investigations in the Mizunami and Horonobe projects (phase 1), integration of work from different disciplines into a “geosynthesis” has been illustrated and is planned to be developed further in the underground facilities at these sites (phases 2 and 3). These projects also serve for developing and testing the tools and methodologies required for site characterization. Further know-how will be gained through participation in foreign underground laboratory projects, transfer of experience from these projects to Japan and tailoring it to Japanese conditions and requirements.This experience represents an important knowledge base, which is obviously important for the implementer but is also needed by the regulator, in order to assess how key site characteristics are derived and what uncertainties are associated with this process.

Time basis ship safety assessment model for a novel ship design

2013 ◽  
Vol 59 ◽  
pp. 179-189 ◽  
Author(s):  
Hee Jin Kang ◽  
Young-Soon Yang ◽  
Jin Choi ◽  
Jong-Kap Lee ◽  
Dongkon Lee
Keyword(s):  
Safety Assessment ◽  
Ship Design ◽  
Assessment Model ◽  
Time Basis ◽  
Ship Safety

Air traffic safety management: ANSP perspective

2021 ◽  
Vol 132 ◽  
pp. 19-28
Author(s):  
Dolores Gracja PIWEK
Keyword(s):  
Traffic Safety ◽  
Safety Assessment ◽  
Safety Management ◽  
Air Traffic ◽  
Hazard Identification ◽  
Assessment Methodology ◽  
Voluntary Reporting ◽  
Safety Regulations ◽  
Dynamic Growth ◽  
Navigation Service

The dynamic growth of air operations in the airspace is related to air traffic threats, which obliges aviation organizations to predict them and develop a proactive safety management strategy. The study aimed to analyze how the air navigation service provider (ANSP) implements the safety management system's assumptions in the event of a constant increase in air traffic and whether these activities contribute to achieving the assumed parameters (indicators) of safety. For this purpose, a critical analysis of the literature was carried out, supplemented with interviews conducted among these institutions' representatives. The best tools for implementing the safety management system's objectives, including hazard identification and risk management by ANSP, were identified. These are the safety assessment methodology for changes in functional systems SAM (Safety Assessment Methodology), the mandatory and voluntary reporting of aviation occurrences, and the RAMS risk assessment mark sheets. It should be noted, however, that the change management process concerns primarily planned changes. Simultaneously, there is insufficient information on how to deal with unplanned changes, and the safety culture requires intensified activities in the form of training of operational personnel. Besides, safety regulations require constant updating, and safety management models adapt to a continually changing environment.

A Comparison Among Alternatives to Assess FPSO Roll Damping via Model Testing

2014 ◽  
Author(s):  
Allan C. de Oliveira ◽  
Antonio Carlos Fernandes ◽  
Anderson R. W. Soares
Keyword(s):  
Model Test ◽  
Model Testing ◽  
Lessons Learned ◽  
Irregular Waves ◽  
Roll Damping ◽  
Test Specifications ◽  
Nonlinear Rolling ◽  
Decay Tests ◽  
Standard Strategy ◽  
Statistic Approach

The prediction of the nonlinear rolling motions of a FPSO with extended bilge keels stills a challenging problem. Despite recent advantages in CFD computations, the use of model testing is considered the standard strategy for roll damping assessments. There are different ways to assess the roll damping via model testing and the three most common are the use of decay tests, tests in regular and irregular waves. The comparison among those different kinds of tests may present incoherent results, sometimes, introducing the question of which methodology is the most appropriated in those scenarios, with impact in model test specifications. Decay tests are the easiest and the most economical way for roll assessments, but they are usually considered inaccurate compared to the other test types. Recent researches, however, have shown that a statistic approach which utilizes several decay data from the same model and loading condition improves the damping predictions. This paper provides comparisons of damping predictions from different test types based in extensive model test campaigns. It also addresses the issues and the lessons learned during the campaigns to obtain the FPSO damping database.

scholarly journals Wind and Gravity in Shaping Picea Trunks

2020 ◽  
Author(s):  
Markku Larjavaara ◽  
Mikko Auvinen ◽  
Anu Kantola ◽  
Annikki Mäkelä
Keyword(s):  
Dense Layer ◽  
Bending Moments ◽  
Large Eddy Simulation Model ◽  
Wind Speeds ◽  
Eddy Simulation ◽  
Wind Gusts ◽  
Biomechanical Modelling ◽  
Large Eddy ◽  
Significant Step ◽  
Biomechanical Approach

Abstract Background:Understanding why trunks (tree stems) are the size that they are is important. However, this understanding is fragmented into isolated schools of thought and has been far from complete. Realistic calculations on minimum trunk diameters needed to resist bending moments caused by wind and gravity would be a significant step forward. However, advancements using this biomechanical approach have been delayed by difficulties in modelling wind gusts. We felled and measured five Norway spruces (Picea abies) in an unthinned monoculture in southeastern Finland planted 67 years earlier. We focused on forces working on storm-bent (maximally bent) trees caused by gravity and the strongest gust in a one-hour simulation with a large-eddy simulation model. Results:The three largest trees resisted mean above-canopy wind speeds ranging from 10.2 m s-1 to 12.7 m s-1 (3.3-fold in the gust), but the two smallest were well protected by a dense layer of leaves from the bending tops of larger trees, and could have resisted stronger winds. Gravity caused approximately one quarter of the critical bending moments. Conclusions:Our biomechanical modelling of trunk taper based on wind and gravity leads to diameters close to those measured, and we discuss the potential causes of the deviations. This approach could also be used to model tree biomasses and how those may change with changing climate.

scholarly journals Wind and Gravity in Shaping Picea Trunks

2021 ◽  
Author(s):  
Markku Larjavaara ◽  
Mikko Auvinen ◽  
Anu Kantola ◽  
Annikki Mäkelä
Keyword(s):  
Picea Abies ◽  
Dense Layer ◽  
Bending Moments ◽  
Large Eddy Simulation Model ◽  
Wind Speeds ◽  
Eddy Simulation ◽  
Wind Gusts ◽  
Large Eddy ◽  
Significant Step ◽  
Biomechanical Approach

Abstract Understanding why trunks (tree stems) are the size that they are is important. However, this understanding is fragmented into isolated schools of thought and has been far from complete. Realistic calculations on minimum trunk diameters needed to resist bending moments caused by wind and gravity would be a significant step forward. However, advancements using this biomechanical approach have been delayed by difficulties in modelling bending of trunks and wind gusts. We felled and measured five Norway spruces (Picea abies) in an unthinned monoculture in southeastern Finland planted 67 years earlier. We focused on forces working on storm-bent (maximally bent) trees caused by gravity and the strongest gust in a one-hour simulation with a large-eddy simulation model. The weakest points along the trunks of the three largest trees resisted mean above-canopy wind speeds ranging from 10.2 m s-1 to 12.7 m s-1 (3.3-fold in the strongest gust), but the two smallest were well protected by a dense layer of leaves from the bending tops of larger trees, and could have resisted stronger winds. Gravity caused approximately one quarter of the critical bending moments. The wind that breaks the trunks in their weakest points is close to breaking them in other points, supporting importance of bending moments caused by wind and gravity in evolution of trunk taper. This approach could also be used to model tree biomasses and how those may change with changing climate.

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