32 research outputs found
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Solvent extraction of thorium from nitrate solutions by dibutyl butylphosphonate in Isopar H
Solvent extraction of thorium by 30 vol % dibutyl butylphosphonate-70 vol % Isopar H from salted and nonsalted nitric acid solutions was studied. Thorium distribution coefficients D/sub Th/'s were obtained for nitric acid solutions of approx. 0.3 to approx. 12 N and for solutions of 1 and 2 M NH/sub 4/NO/sub 3/ over the HNO/sub 3/ concentration range of approx. 0.5 to approx. 9 N. The nitric acid solution D/sub Th/'s varied from approx. 4.3 at the lowest acidity, increased to a maximum of approx. 40 at approx. 3-4 N H/sup +/, and then gradually decreased to approx. 18 at approx. 11.5 N H/sup +/. The solutions containing 1 and 2 M NH/sub 4/NO/sub 3/ gave definite salting-out effects with D/sub Th/'s of 79 to 90, respectively, at the lowest acidities; these values then decreased with acidity increases to those of the nonsalted acid solutions at approx. 5 N HNO/sub 3/ and paralleled the acid solution values up to approx. 12 N
On blade matching following batch production
Wind turbine blades are usually made in batches and then matched in pairs or triples to form the rotor. This paper considers matching with the aim of avoiding or reducing the need for further adjustment of, say, the blade mass. Matching is considered optimal when it minimises the sum of the squared differences in the chosen matching parameter for all blade pairs or triples in a batch. It is proved that use of a simple parameter such as blade mass, or centre of mass, leads to optimal matching by ordering in terms of that parameter. More complex matching based on, say, minimising the eccentricity of the centre of mass, causes the parameter for one blade to depend on at least one other blade. Then ordering does not necessarily produce the optimal matching but, in all cases considered, it comes very close. A branch and bound algorithm is developed for complex matching and is shown to provide the optimal matching in a realistic time for batches of at least 20 blades
The role of perceptions of task difficulty in relation to self-perceptions of ability, intrinsic value, attainment value, and performance
Privacy Preserving Reputation Management in Social Networks
International audienceReputation management is a powerful security tool that helps establish the trustworthiness of users in online applications. One of the most successful use of reputation systems is in e-commerce web sites such as eBay.com and Amazon.com which use reputation systems to root out fraudulent sellers. Reputation systems can also play an important role in social networks to enforce various security requirements. For example, a reputation system can help filter fake user profiles. However, a major challenge in developing reputation systems for social networks is that users often hesitate to publicly rate fellow users or friends due to the fear of retaliation. This trend prevents a reputation system from accurately computing reputation scores. Privacy preserving reputation systems hide the individual ratings of users about others and only reveal the aggregated community reputation score thus allowing users to rate without the fear of retaliation. In this chapter, we describe privacy preserving reputation management in social networks and the associated challenges. In particular we will look at privacy preserving reputation management in decentralized social networks, where there is no central authority or trusted third parties, thus making the task of preserving privacy particularly challenging