1,721,317 research outputs found
Hydor-impact, fluid-structure interaction and structural response of modern racing yacht
No full textIn recent years, faster, lighter and bigger are the key issues in a modern racing yachtfor extreme performance. As a result, many yachts have experienced various structuralfailures caused by the hydrodynamic impact or ’hydro-impact’ phenomenon byslamming.The structural failure by hydro-impact originates from the facts that the externalhydro-impact load and fluid structure interaction effect is somewhat misled and whenapplying the load into current structural design, the ’dynamic’ load is typically, manipulatedin a ’static’ way with fluid structure interaction effect, generally, ignored.In this thesis, the hydro-impact load by slamming, its fluid structure interaction effectand dynamic response of the local structure of the yacht are studied.Firstly, to acquire insight into the hydro-impact phenomenon, a series of drop testsand seakeeping-slamming tests are carried out with various sensing instruments ofpressure transducers, accelerometer and ’slam patch system’ - a specific applicationform of generally known pressure panel - are installed. The slam patch system isdesigned and implemented to investigate the hydro-impact loads and fluid structureinteraction effect of slamming. Afterward, the measured hydro-impact loads are summarisedvia statistical manipulations with regard to pressure and duration time.Secondly, impact pressure by the rules and regulations of various organisations areprovided to compare it with the experimental results and structural response calculations.The applicability of the rules and regulations on the high performance racingyacht is also pointed out.Finally, the manipulated loads are used as input data to simulate the transientresponse of local structure of the yacht structure.Throughout this study, the dynamic and fluid structure interaction effect by hydroimpactphenomenon on local composite structure can be easily visualised and calculatedin a conservative way through conventional finite element analysis work
Characterisation and suppression of chattering in impacting structures
No full textThe study of impact oscillators is based on bifurcation theory as a condition monitor. Impact motion is characterised by parameters such as driving frequency and clearance. The possible bifurcations (period-doubling, saddle node and grazing) are investigated. Different types of impact chattering (complete, incomplete, periodic, chaotic and intermittent chattering) are found in different driving frequency regions. These dynamics are interpreted using impact maps and Poincaré maps, and impact resonance is predicted using analytic and numerical methods. Schemes for suppression of impact resonance are introduced using isolation subsystems. The characteristics of impact phenomena and the suppression schemes presented in this thesis are validated experimentally using a cantilever beam with an inelastic endstop.</p
Seeds of Distrust: Conflicts over Sustainable Development in a Local Fracking Policy Network in New York State
No full textPursuing economic, environmental and social sustainability requires networks endowed with persistent relationships between stakeholders. Networks serve as the vehicle to coordinate diverse policy goals among stakeholders. Within the networks, stakeholders inevitably experience some level of distrust due to the complexity and uncertainty of the unstructured problems on the sustainability. However, little is known about why stakeholders often distrust with one another in the networks. By analysing a local fracking policy network in NYS, we suggest that distrust is influenced by incongruent ecological worldviews, policy goals incongruence in the triple bottom line of sustainability, characterization framing, policy communications and knowledge exchange.1
Characterization of RNA Aptamers to C5 protein, the Protein Component of Escherichia coli RNase P
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Interaction of poly(A) polymerase with cyclophilin: possible involvement of cyclophilin in polyadenylation of pre-mRNA
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