Suppression system for offshore cylinders under vortex induced vibration

Vortex Induced Vibration (VIV) is a major challenge in the design of tubular members under second order wave effects. Providing helical strakes have proven to eliminate presence of VIV, but at the cost of increased drag. Two different approaches of VIV suppression are discussed in the present study and compared. Concept of suppressing vibration by tripping the boundary layer of incoming flow using stripping wires is experimentally investigated. It is seen that the position at which boundary separates has an important role in response behavior of the cylinder. Effect of lock-in point at higher reduced velocities is quantified. Alternative study is also carried out by disrupting the correlation of flow in a stepped cylinder where an abrupt change in diameter in imposed by design. For comparison, vibration of stepped cylinder, attached with tripping wire is also examined. Results from the studies showed VIV suppression under both the independent configurations but a significant improvement is seen in the latter case

Stereospecific and regioselective catalytic epoxidation of alkenes by a novel ruthenium(II) complex under aerobic conditions

Epoxidation of alkenes by molecular oxygen is effected in high yields by catalysis of RuCl2(biox)2 using isobutyraldehyde as the co-reductant: the reaction is stereospecific and regioselective

Proline and benzylpenicillin derivatives grafted into mesoporous MCM-41: novel organic-inorganic hybrid catalysts for direct aldol reaction

New organic-inorganic hybrid catalysts were synthesized by covalent grafting of proline and benzylpenicillin derivatives into mesoporous MCM-41. These catalysts were extensively characterized using FT-IR,13C CP MAS solid state NMR, XRD and TEM techniques. These were used as catalysts for direct, asymmetric aldol reaction between acetone and activated aromatic aldehydes. In the reaction of 4-nitro and 4-fluoro benzaldehyde, the aldol products were obtained in 36% and 59%ee respectively. The catalysts were reusable with neither significant drop in enantioselectivity nor loss of mesostructure. An attempt was made to substantiate the proposed 'enamine' mechanism for direct aldol reaction by trapping the intermediate between proline-MCM-41 and acetone

Efficient Web Service Discovery and Selection Model

Selection of an optimal web service is a challenging task due to the uncertainty of Quality of Service, which is the deciding factor to identify the accurate web service. Several discovery mechanisms have proposed but most of the research work does not consider the non-functional characteristics called Quality of service. The proposed model for web service selection combines two techniques. First, with Skyline method reduce the search space by filtering the redundant service and secondly to calculate the Relevancy function to normalize the skyline services. The experimental results show that the proposed technique outperforms the existing method

Propargyloxycarbonyl (Poc) amino acid chlorides as efficient coupling reagents for the synthesis of 100% diastereopure peptides and resin bound tetrathiomolybdate as an effective deblocking agent for the Poc group

Synthesis of short peptides using propargyloxycarbonyl amino acid chlorides as effective coupling reagents and polymer supported tetrathiomolybdate as an efficient deblocking agent are reported

Learning user modelling strategies for adaptive referring expression generation in spoken dialogue systems

We address the problem of dynamic user modelling for referring expression generation in spoken dialogue systems, i.e how a spoken dialogue system should choose referring expressions to refer to domain entities to users with different levels of domain expertise, whose domain knowledge is initially unknown to the system. We approach this problem using a statistical planning framework: Reinforcement Learning techniques in Markov Decision Processes (MDP). We present a new reinforcement learning framework to learn user modelling strategies for adaptive referring expression generation (REG) in resource scarce domains (i.e. where no large corpus exists for learning). As a part of the framework, we present novel user simulation models that are sensitive to the referring expressions used by the system and are able to simulate users with different levels of domain knowledge. Such models are shown to simulate real user behaviour more closely than baseline user simulation models. In contrast to previous approaches to user adaptive systems, we do not assume that the user’s domain knowledge is available to the system before the conversation starts. We show that using a small corpus of non-adaptive dialogues it is possible to learn an adaptive user modelling policy in resource scarce domains using our framework. We also show that the learned user modelling strategies performed better in terms of adaptation than hand-coded baselines policies on both simulated and real users. With real users, the learned policy produced around 20% increase in adaptation in comparison to the best performing hand-coded adaptive baseline. We also show that adaptation to user’s domain knowledge results in improving task success (99.47% for learned policy vs 84.7% for hand-coded baseline) and reducing dialogue time of the conversation (11% relative difference). This is because users found it easier to identify domain objects when the system used adaptive referring expressions during the conversations

Applications of Propargyl Esters of Amino Acids in Solution-Phase Peptide Synthesis

Propargyl esters are employed as effective protecting groups for the carboxyl group during solution-phase peptide synthesis. The propargyl ester groups can be introduced onto free amino acids by treating them with propargyl alcohol saturated with HCl. The reaction between propargyl groups and tetrathiomolybdate is exploited to deblock the propargyl esters. The removal of the propargyl group with the neutral reagent tetrathiomolybdate ensures that most of the other protecting groups used in peptide synthesis are untouched. Both acid labile and base labile protecting groups can be removed in the presence of a propargyl ester. Amino acids protected as propargyl esters are employed to synthesize di- to tetrapeptides in solution-phase demonstrating the possible synthetic utilities of the methodology. The methodology described here could be a valuable addition to currently available strategies for peptide synthesis

Propargyloxycarbonyl as a protecting group for the side chains of serine, threonine and tyrosine

Propargyloxycarbonyl group is used as a protecting group for the hydroxyl groups of serine, threonine and tyrosine. The propargyloxycarbonyl derivatives of these hydroxy amino acids are stable to acidic and basic reagents commonly employed in peptide synthesis. The deprotection of the O-Poc derivatives using tetrathiomolybdate does not affect commonly used protecting groups such as N-Boc, N-Cbz, N-Fmoc, methyl and benzyl esters. The di-and tripeptides synthesized using O-Poc derivatives of serine, threonine and tyrosine are stable, isolable compounds and give the hydroxy peptides in good yields when treated with tetrathiomolybdate

A highly chemoselective reduction of isosorbide-2,5-dinitrate mediated by Tetrathiomolybdate

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