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Towards Safety Based Design Procedure for Ships
Bakker, Marijn,Boonstra, Hotze,Engelhard, Wim,Daman, Bart The Society of Naval Architects of Korea 2001 Journal of ship and ocean technology Vol.5 No.3
Present-day rules and regulations for the design and construction of ships are almost without exemption of a prescriptive and deterministic nature. Often it is argued that this situation is far from ideal; it does no right to the advances, which have been made during the past decades in engineering tools in marine technology, both in methodology and in computational power. Within IMO this has been realized for some time and has resulted in proposals to use Formal Safety Assessment(FSA) as a tool to improve and to modernize the rule making process. The present paper makes use of elements of the FSA methodology, but instead of working towards generic regulations or requirements, a Risk Assessment Approach, not unlike a 'safety case'; valid for a certain ship or type of ship is worked out. Delft University of Technology investigated the application of safely assessment procedures in ship design, in co-operation with Anthony Veder Shipowners and safety experts from Safely Service Center BV. The ship considered is a semi-pressurized-fully refrigerated LPG carrier. On the basis of the assumption that a major accident occurs, various accident, scenarios were considered and assessed, which would impair the safety of the carrier. In a so-called Risk Matrix, in which accident frequencies versus the consequence of the scenarios are depicted, the calculated risks all appeared lo be in the ALARP('as low as reasonable practicable') region. A number of design alternatives were compared, both on safety merits and cost-effectiveness. The experience gained with this scenario-based approach will be used to establish a set of general requirements for safety assessment techniques in ship design. In the view that assessment results will be most probably presented in a quasi-quantified manner, the requirements are concerned with uniformity of both the safety assessment. These requirements make it possible that valid comparison between various assessment studies can be made. Safety assessment, founded on these requirements, provides a validated and helpful source of data during the coming years, and provides naval architects and engineers with tools experience and data for safety assessment procedures in ship design. However a lot of effort has to be spent in order to make the methods applicable in day-to-day practice.
Effect of Co/Ni ratios in cobalt nickel mixed oxide catalysts on methane combustion
Lim, T.H.,Cho, S.J.,Yang, H.S.,Engelhard, M.,Kim, D.H. Elsevier 2015 Applied Catalysis A Vol.505 No.-
A series of cobalt nickel mixed oxide catalysts with the varying ratios of Co to Ni, prepared by co-precipitation method, were applied to methane combustion. Among the various ratios, cobalt nickel mixed oxides having the ratios of Co to Ni of (50:50) and (67:33) demonstrate the highest activity for methane combustion. Structural analysis obtained from X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) evidently demonstrates that CoNi (50:50) and (67:33) samples consist of NiCo<SUB>2</SUB>O<SUB>4</SUB> and NiO phase and, more importantly, NiCo<SUB>2</SUB>O<SUB>4</SUB> spinel structure is largely distorted, which is attributed to the insertion of Ni<SUP>2+</SUP> ions into octahedral sites in Co<SUB>3</SUB>O<SUB>4</SUB> spinel structure. Such structural disorder results in the enhanced portion of surface oxygen species, thus leading to the improved reducibility of the catalysts in the low temperature region as evidenced by temperature programmed reduction by hydrogen (H<SUB>2</SUB> TPR) and X-ray photoelectron spectroscopy (XPS) O 1s results. They prove that structural disorder in cobalt nickel mixed oxides enhances the catalytic performance for methane combustion. Thus, it is concluded that a strong relationship between structural property and activity in cobalt nickel mixed oxide for methane combustion exists and, more importantly, distorted NiCo<SUB>2</SUB>O<SUB>4</SUB> spinel structure is found to be an active site for methane combustion.
Saslow, Sarah A.,Um, Wooyong,Pearce, Carolyn I.,Engelhard, Mark H.,Bowden, Mark E.,Lukens, Wayne,Leavy, Ian I.,Riley, Brian J.,Kim, Dong-Sang,Schweiger, Michael J.,Kruger, Albert A. American Chemical Society 2017 Environmental science & technology Vol.51 No.15
<P>Technetium (Tc) remains a priority remediation concern due to persistent challenges, including mobilization due to rapid reoxidation of immobilized Tc, and competing comingled contaminants, e.g., Cr(VI), that inhibit Tc(VII) reduction and incorporation into stable mineral phases. Here Fe(OH)(2)(s) is investigated as a comprehensive solution for overcoming these challenges, by serving as both the reductant, (Fe(II)), and the immobilization agent to form Tc-incorporated magnetite (Fe3O4). Trace metal analysis suggests removal of Tc(VII) and Cr(VI) from solution occurs simultaneously; however, complete removal and reduction of Cr(VI) is achieved earlier than the removal/reduction of comingled Tc(VII). Bulk oxidation state analysis of the final magnetite solid phase by XANES shows that the majority of Tc is Tc(IV), which is corroborated by XPS measurements. Furthermore, EXAFS results show successful, albeit partial, Tc(IV) incorporation into magnetite octahedral sites. Cr XPS analysis indicates reduction to Cr(III) and the formation of a Cr-incorporated spinel, Cr2O3, and Cr(OH)(3) phases. Spinel (modeled as Fe3O4), goethite (alpha-FeOOH), and feroxyhyte (delta-FeOOH) are detected in all reacted final solid phase samples analyzed by XRD. Incorporation of Tc(IV) has little effect on the spinel lattice structure. Reaction of Fe(OH)(2)(s) in the presence of Cr(III) results in the formation of a spinel phase that is a solid solution between magnetite (Fe3O4) and chromite (FeCr2O4).</P>
Belsey, Natalie A.,Cant, David J. H.,Minelli, Caterina,Araujo, Joyce R.,Bock, Bernd,Brü,ner, Philipp,Castner, David G.,Ceccone, Giacomo,Counsell, Jonathan D. P.,Dietrich, Paul M.,Engelhard, Mark American Chemical Society 2016 The Journal of Physical Chemistry Part C Vol.120 No.42
<P>We report the results of a Versailles Project on Advanced Materials and Standards (VAMAS) interlaboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS. Degradation during transportation, storage, or sample preparation resulted in a variability in thickness of 53%. The calculation method chosen by XPS participants contributed a variability of 67%. However, variability of 12% was achieved for the samples deposited using a single method and by choosing photoelectron peaks that were not adversely affected by instrumental transmission effects. The study identified a need for more consistency in instrumental transmission functions and relative sensitivity factors since this contributed a variability of 33%. The results from the LEIS participants were more consistent, with variability of less than 10% in thickness, and this is mostly due to a common method of data analysis. The calculation was performed using a model developed for uniform, flat films, and some participants employed a correction factor to account for the sample geometry, which appears warranted based upon a simulation of LEIS data from one of the participants and comparison to the XPS results.</P>