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Publication Abstracts Marine Operation for Cold Climate COTech301:Limitations
Related to Marine Operations in the Barents Sea Ove
T. Gudmestad Department of
Mechanical and Structural Engineering and Material Science, University of Stavanger, Stavanger, 4036, Norway Abstract.
Some
marine activities in the Barents Sea are normally ongoing year-round;
others are dependent on limited weather windows. The limitations for
the marine operations are the special weather conditions
characterized by unpredictable Polar Low situations during the fall,
winter and spring seasons, as well as cold temperatures that also are
causing sea spray icing and the potential for drifting ice in certain
parts of the Sea. It must also be realized that large distances
combined with challenging meteorological and oceanographic criteria
as well as darkness during the winter period represents a concern for
evacuation and rescue, should it be necessary to abandon ships and
platforms. The long distances to the locations farthest away from
shore are, furthermore, out of reach of helicopter assistance. These
aspects make it necessary to conduct hazard identification studies
and to include all relevant historical knowledge in the hazard
identification session, prior to the execution of marine operations
in the Barents Sea Keywords - Barents Sea, Hazard identification, Marine activities, Operational limitations, Risk avareness. COTech302:
Implications
caused by SARex on the implementation of the IMO polar code on
survival at sea K E Solberg GMC
Maritime AS Abstract.
The International Code for
Ships Operating in Polar waters goes into effect on 01 January 2018
for all ships. This puts additional strain on vessel owners and
operators as they will have to comply
with an additional set of requirements. This includes the functional
requirement of a minimum of 5 days survival time. The SARex exercise
has elaborated on the issue of survival in close cooperation with the
different stakeholders associated with the marine industry. Being an
objective third party is important when organizing and executing
these activities as all of the stakeholders has different agendas and
priorities. Developing sustainable solutions is a balancing act,
incorporating economic and political aspects as well as technology
and requires a mutual common understanding of the mechanism involved. Keywords:
Cold
Climate Marine Operation, International Maritime Organization (IMO),
Polar Code, Risk, SARex, Stakeholders. COTech303:
On weather limitations for safe marine operations in the
Barents Sea A P Orimolade,
Ove T. Gudmestad Department of
Mechanical and Structural Engineering and Materials Science, Abstract. The Barents Sea wave conditions and the weather
conditions that often accompany fully developed polar lows are
presented in this paper. The studies on the extreme waves showed that
the extreme waves in the Barents Sea decreases as we move further
north. The Barents Sea wave conditions are found to be more
accessible for marine operations in the summer months compared to the
North Sea and the Norwegian Sea wave conditions. However, the quality
of actual weather forecasts and the contribution of long periodic
swells to the total sea in the Barents Sea could negate the longer
weather windows observed in the area. Further, the weather conditions
that often accompany fully developed polar lows represent limitations
to marine operations in the Barents Sea. It was found that the
significant wave height in polar lows could be up to 9 m. In
addition, snow and ice accretion in polar lows are deemed operation
and safety hazards. Overall,
marine operation may not be carried out within the period when a
polar low is likely to occur. Keywords—
Barents
Sea, Marine operations, Polar lows, Snow and ice accretion, Waves. COTech304:
A practical guideline for human
error assessment: A causal model A Z Ayele1,
2,
A Barabadi2. 1Faculty of Engineering, Østfold University College,
Fredrikstad, Norway Abstract. To
meet the availability target and reduce system downtime, effective
maintenance have a great importance. However, maintenance performance
is greatly affected in complex ways by human factors. Hence, to have
an effective maintenance operation, these factors needs to be
assessed and quantified. To avoid the inadequacies of traditional
human error assessment (HEA) approaches, the application of Bayesian
Networks (BN) is gaining popularity. The main purpose of this paper
is to propose a HEA framework based on the BN for maintenance
operation. The proposed framework aids for assessing the effects of
human performance influencing factors on the likelihood of human
error during maintenance activities. Further, the paper investigates
how operational issues must be considered in system failure-rate
analysis, maintenance planning, and prediction of human error in pre-
and post-maintenance operations. The goal is to assess how
performance monitoring and evaluation of human factors can effect
better operation and maintenance.
Keywords—Bayesian Network, Human error, Maintenance,
Performance influencing factors, Causal model COTech305:
Limit
cycle oscillations at resonances: For
systems subjected to nonlinear damping or external forces. Karina
Hellevik and Ove T. Gudmestad Department
of Mechanical and Structural Engineering and Material Science, Abstract.
This
paper deals with limit cycles in one degree of freedom systems. The
van der Pol equation is an example of an equation describing systems
with clear limit cycles in the phase space (displacement-velocity 2
dimensional plane). In this paper, it is shown that a system with
nonlinear loading, representing the drag load acting on structures in
an oscillatory flow (the drag term of the Morison equation), will in
fact exhibit limit cycles at resonance and at higher order
resonances. These limit cycles are stable, and model self-excited
oscillations. As the damping in the systems is linear and constant,
the drag loading will to some degree work as negative damping. The
consequences of the existence of these limit cycles are that systems
starting at lesser amplitudes in the phase plane will exhibit
increased amplitudes until the limit cycle is obtained. Keywords:
Limit
cycles, Nonlinearity, Morison drag loading, Negative damping.
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