1,721,319 research outputs found
ASPECTS OF A RELIABILITY CALCULATION PERFORMED ON AN OIL TANKER
No full textThe paper presents some results of a reliability analysis carried out on a 150,000 DWT double hull tanker.
The analysis is performed according to a second level reliability procedure and a description is contained of the stochastic model for the considered variables. In particular, a detailed comparison is made on the results obtained with various degrees of approximation in the model for sea loads.
A typical route between Northern Europe and the Persic Gulf via the Suez Channel is considered in the study, which is relative to a period of one year. In the description of loading and operational conditions, use is made of detailed records available from the owner, regarding the first year of activity of the ship.
The ultimate collapse value of the hull girder in its “as-built” condition and the failure mode due to vertical bending moment are considered in the collapse equation.
The present work gives an indication on the procedure that can be followed in the reliability analysis of a ship, as well as on the values of the reliability index obtained for an existing,
typical and well designed oil tanker in a typical route. Such values can be used for future comparisons between different design solutions or practices.
The results of the present study can also be used to calibrate a first order reliability model (partial safety factor format)
RELIABILITY ANALYSIS OF THE PRIMARY STRENGHT OF AN OIL TANKER - COMBINATION OF VERTICAL AND HORIZONTAL WAVE-INDUCED LOAD EFFECTS
No full textA procedure is presented to perform a second order reliability-based structural analysis of the mid ship
section of a vessel. The procedure accounts for the combination of the vertical and horizontal components of
the wave induced bending moment as well as of the still water bending moment, in order to determine the
actual angle gamma formed with the vertical plane by the total resultant bending moment.
The ultimate strength of the midship section is considered as a function of the same angle.
The proposed analysis is applied to a double hull tanker on a particular route (Persic Gulf - North Europe
and ballast return trip) and directional scatter diagrams are used for the description of the sea states
encountered during the voyage.
The results are compared to those obtained on the same test case with a simpler model, which takes into
account only the vertical components of loads and strength. The comparison shows that the introduction in
the load model of the horizontal component of the bending moment does not reduce the structural reliability
of the considered oil tanker ship. Such result is to be related to the shape of the curve of hull girder ultimate
strength as a function of gamma, which shows a local minimum for pure vertical bending moment: in the examined
case, the most dangerous condition is obtained in such situation
Electrochemical Preparation of a Composite Gold-Cobalt Electrode and its Electrocatalytic Activity in Alkaline Medium
No full textAbstract: A chemically modified electrode composed of cobalt(III) oxyhydroxide film dispersed on the gold substrate (Au-Co) was characterised by cyclic voltammetry. Electrochemical deposition of the cobalt film was accomplished by cycling the potential between 0.0 V and 1.1 V (vs. saturated calomel electrode (SCE)) in 0.1 M acetate solution (at pH 7.3) containing 10 mM CoCl2. The effects of several experimental parameters (pH, applied potentials, etc.) on the film formation and growth were evaluated. The electrochemical behaviour of the Au-Co composite electrode was investigated in alkaline medium. The film appears uniform and compact and shows good electrical conductivity and electrochemical activity towards the oxidation of several scarcely electroactive organic molecules. The concomitant presence on the electrode surface of both active catalysts leads to a wide range of potential applications where a significant electrochemical activity towards the electrooxidation of several classes of organic compounds is observed. (C) 1999 Elsevier Science Ltd. All rights reserved
Anodic Electrodeposition of Conducting Cobalt Oxyhydroxide Films on a Gold Surface. XPS Study and Electrochemical Behaviour in Neutral and Alkaline Solution
No full textAbstract: A novel chemically modified electrode prepared by anodic electrodeposition of cobalt (III) film on the gold electrode substrate (Au-Co) was characterised by cyclic voltammetry and XPS techniques in both neutral and alkaline medium. Cobalt oxyhydroxide film was deposited by cycling the potential between 0.0 and 1.1 V versus SCE in 0.1 M sodium acetate solutions containing 10 mM CoCl2. The electrocatalytic properties of the Au-Co electrode were investigated in alkaline medium using glucose as a model compound. A comparative XPS study of bare gold, bare cobalt and Au-Co electrodes after electrochemical treatment in neutral and alkaline solutions has been carried out. A detailed XPS analysis of the Au4f(7.2), Co2p(3.2), O1s and C1s regions was performed to check the chemical composition of the Au-Co electrode upon electrochemical treatments. Film deposition is attributed to growth of conducting and compact CoOOH oxyhydroxide with significant insertion of carbonyl groups within the electrodeposited layer. The prolonged electrochemical treatment in alkaline medium produces a good stabilization of the Co-III oxyhydroxide film, with a dominant O1s feature at about 532.4 eV of BE corresponding to a non-stoichiometric surface oxygen. The absence of CoO species proves good conducting properties of the cobalt film and the absence of any passivation effects on the catalytic performance. (C) 1999 Elsevier Science S.A. All rights reserved
Electrocatalysis of ascorbic acid on the glassy carbon electrode chemically modified with polyaniline films
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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