Annular Seals of High Energy Centrifugal Pumps: Presentation of Full Scale Measurement

Prediction of rotordynamic behavior for high energy concentration centrifugal pumps is a challenging task which still imposes considerable difficulties. While the mechanical modeling of the rotor is solved most satisfactorily by finite element techniques, accurate boundary conditions for arbitrary operating conditions are known for journal bearings only. Little information is available on the reactive forces of annular seals, such as neck ring and interstage seals and balance pistons, and on the impeller interaction forces. The present focus is to establish reliable boundary conditions at annular seals. For this purpose, a full scale test machine was set up and smooth and serrated seal configurations measured. Dimensionless coefficients are presented and compared with a state of the art theory

Employing dynamic fuzzy membership functions to assess environmental performance in the supplier selection process

The proposed system illustrates that logic fuzzy can be used to aid management in assessing a supplier's environmental performance in the supplier selection process. A user-centred hierarchical system employing scalable fuzzy membership functions implement human priorities in the supplier selection process, with particular focus on a supplier's environmental performance. Traditionally, when evaluating supplier performance, companies have considered criteria such as price, quality, flexibility, etc. These criteria are of varying importance to individual companies pertaining to their own specific objectives. However, with environmental pressures increasing, many companies have begun to give more attention to environmental issues and, in particular, to their suppliers’ environmental performance. The framework presented here was developed to introduce efficiently environmental criteria into the existing supplier selection process and to reflect on its relevant importance to individual companies. The system presented attempts to simulate the human preference given to particular supplier selection criteria with particular focus on environmental issues when considering supplier selection. The system considers environmental data from multiple aspects of a suppliers business, and based on the relevant impact this will have on a Buying Organization, a decision is reached on the suitability of the supplier. This enables a particular supplier's strengths and weaknesses to be considered as well as considering their significance and relevance to the Buying OrganizationPeer reviewe

Landauer's principle in multipartite open quantum system dynamics

We investigate the link between information and thermodynamics embodied by Landauer's principle in the open dynamics of a multipartite quantum system. Such irreversible dynamics is described in terms of a collisional model with a finite temperature reservoir. We demonstrate that Landauer's principle holds, for such a configuration, in a form that involves the flow of heat dissipated into the environment and the rate of change of the entropy of the system. Quite remarkably, such a principle for {\it heat and entropy power} can be explicitly linked to the rate of creation of correlations among the elements of the multipartite system and, in turn, the non-Markovian nature of their reduced evolution. Such features are illustrated in two exemplary cases.Comment: 5 pages, 3 figures, RevTeX4-1; Accepted for publication in Phys. Rev. Let

Surface-Plasmon-Assisted Photoelectrochemical Reduction of CO2 and NO3− on Nanostructured Silver Electrodes

Electrochemical reduction of carbon dioxide (CO2) typically suffers from low selectivity and poor reaction rates that necessitate high overpotentials, which impede its possible application for CO2 capture, sequestration, or carbon-based fuel production. New strategies to address these issues include the utilization of photoexcited charge carriers to overcome activation barriers for reactions that produce desirable products. This study demonstrates surface-plasmon-enhanced photoelectrochemical reduction of CO2 and nitrate (NO3−) on silver nanostructured electrodes. The observed photocurrent likely originates from a resonant charge transfer between the photogenerated plasmonic hot electrons and the lowest unoccupied molecular orbital (MO) acceptor energy levels of adsorbed CO2, NO3−, or their reductive intermediates. The observed differences in the resonant effects at the Ag electrode with respect to electrode potential and photon energy for CO2 versus NO3− reduction suggest that plasmonic hot-carriers interact selectively with specific MO acceptor energy levels of adsorbed surface species such as CO2, NO3−, or their reductive intermediates. This unique plasmon-assisted charge generation and transfer mechanism can be used to increase yield, efficiency, and selectivity of various photoelectrochemical processes

Directing Selectivity of Electrochemical Carbon Dioxide Reduction Using Plasmonics

Catalysts for electrochemical carbon dioxide reduction in aqueous electrolytes suffer from high energy input requirements, competition with hydrogen evolution from water reduction, and low product selectivity. Theory suggests that plasmonic catalysts can be tuned to selectively lower the energy barrier for a specific reaction in a set of competitive reactions, but there has been little experimental evidence demonstrating plasmon-driven selectivity in complicated multielectron electrochemical processes. Here, the photoactivity at a plasmonically active silver thin film electrode at small cathodic potentials selectively generates carbon monoxide while simultaneously suppressing hydrogen production. At larger cathodic potentials, the photoactivity promotes production of methanol and formate. Methanol production is observed only under illumination, not in dark conditions. The preference of the plasmonic activity for carbon dioxide reduction over hydrogen evolution and the ability to tune plasmonic activity with voltage demonstrates that plasmonics provide a promising approach to promote complex electrochemical reactions over other competing reactions

Important Considerations in Plasmon-Enhanced Electrochemical Conversion at Voltage-Biased Electrodes.

In this perspective we compare plasmon-enhanced electrochemical conversion (PEEC) with photoelectrochemistry (PEC). PEEC is the oxidation or reduction of a reactant at the illuminated surface of a plasmonic metal (or other conductive material) while a potential bias is applied. PEC uses solar light to generate photoexcited electron-hole pairs to drive an electrochemical reaction at a biased or unbiased semiconductor photoelectrode. The mechanism of photoexcitation of charge carriers is different between PEEC and PEC. Here we explore how this difference affects the response of PEEC and PEC systems to changes in light, temperature, and surface morphology of the photoelectrode

Can we improve the prediction of hip fracture by assessing bone structure using shape and appearance modelling?

Copyright 2013 Elsevier B.V., All rights reserved.Peer reviewedPreprin

In Situ ATR-SEIRAS of Carbon Dioxide Reduction at a Plasmonic Silver Cathode.

Illumination of a voltage-biased plasmonic Ag cathode during CO2 reduction results in a suppression of the H2 evolution reaction while enhancing CO2 reduction. This effect has been shown to be photonic rather than thermal, but the exact plasmonic mechanism is unknown. Here, we conduct an in situ ATR-SEIRAS (attenuated total reflectance-surface-enhanced infrared absorption spectroscopy) study of a sputtered thin film Ag cathode on a Ge ATR crystal in CO2-saturated 0.1 M KHCO3 over a range of potentials under both dark and illuminated (365 nm, 125 mW cm-2) conditions to elucidate the nature of this plasmonic enhancement. We find that the onset potential of CO2 reduction to adsorbed CO on the Ag surface is -0.25 VRHE and is identical in the light and the dark. As the production of gaseous CO is detected in the light near this onset potential but is not observed in the dark until -0.5 VRHE, we conclude that the light must be assisting the desorption of CO from the surface. Furthermore, the HCO3- wavenumber and peak area increase immediately upon illumination, precluding a thermal effect. We propose that the enhanced local electric field that results from the localized surface plasmon resonance (LSPR) is strengthening the HCO3- bond, further increasing the local pH. This would account for the decrease in H2 formation and increase the CO2 reduction products in the light

Algorithmic Bayesian Persuasion

Persuasion, defined as the act of exploiting an informational advantage in order to effect the decisions of others, is ubiquitous. Indeed, persuasive communication has been estimated to account for almost a third of all economic activity in the US. This paper examines persuasion through a computational lens, focusing on what is perhaps the most basic and fundamental model in this space: the celebrated Bayesian persuasion model of Kamenica and Gentzkow. Here there are two players, a sender and a receiver. The receiver must take one of a number of actions with a-priori unknown payoff, and the sender has access to additional information regarding the payoffs. The sender can commit to revealing a noisy signal regarding the realization of the payoffs of various actions, and would like to do so as to maximize her own payoff assuming a perfectly rational receiver. We examine the sender's optimization task in three of the most natural input models for this problem, and essentially pin down its computational complexity in each. When the payoff distributions of the different actions are i.i.d. and given explicitly, we exhibit a polynomial-time (exact) algorithm, and a "simple" $(1-1/e)$-approximation algorithm. Our optimal scheme for the i.i.d. setting involves an analogy to auction theory, and makes use of Border's characterization of the space of reduced-forms for single-item auctions. When action payoffs are independent but non-identical with marginal distributions given explicitly, we show that it is #P-hard to compute the optimal expected sender utility. Finally, we consider a general (possibly correlated) joint distribution of action payoffs presented by a black box sampling oracle, and exhibit a fully polynomial-time approximation scheme (FPTAS) with a bi-criteria guarantee. We show that this result is the best possible in the black-box model for information-theoretic reasons

Positive impacts on rural and regional workforce from the first seven cohorts of James Cook University medical graduates

Introduction: The regionally-based James Cook University (JCU) School of Medicine aims to meet its mission to address the health needs of the region by combining selection and curriculum strategies shown to increase rural career recruitment outcomes. The School has graduated 536 students in its first seven cohorts from 2005 to 2011. This paper presents the early career practice locations and the specialty training undertaken by these cohorts, and describes the association between later practice location with both hometown at application and internship location. Methods: 'Hometown at application' data for JCU Bachelor of Medicine, Bachelor of Surgery (MBBS) graduates was retrieved from administrative databases held by the university, while postgraduate location and career data were obtained either from personal contact via email, telephone, Facebook or electronically from the Australian Health Practitioner Regulation Authority website. Practice location was described across Australian Standard Geographical Classification Remoteness Area (RA) categories. Results: Data for the primary practice location of 536 JCU MBBS graduates across postgraduate years (PGY) 1 to 7 is 99% complete. A total of 65% of JCU graduates undertook their internship in non-metropolitan locations including 20% in RA 2 and 44% in RA 3–5, a pattern of practice different to that of other Australian clinicians. For the internship year, 'non-metropolitan-origin' JCU MBBS graduates predominantly worked in RA 2–5 locations, while 'metropolitan origin' graduates were more likely to work in major cities. However, by PGY 7, the distribution of 'rural' and 'metropolitan' origin JCU graduates across RA categories was similar. The RA category of internship location – either 'metropolitan' (RA 1) or 'non-metropolitan' (RA 2–5) – was associated with the location of subsequent practice across PGY 2–7. Conclusions: This comprehensive data set provides the first real evidence from one of Australia's new medical schools on actual postgraduate practice location, as compared to 'intent to practice'. The geographic profile by RA of JCU graduates' hometown and patterns of postgraduate practice is different to that of other Australian medical students and doctors. This early evidence supports the JCU model of distributed non-metropolitan medical education, and suggests more regionally-located internship and specialty training places would further increase the medical workforce in northern and/or rural Australia. The workforce impact of the seven cohorts of graduates in this study is starting to be felt in rural and regional Australia, and, if these trends continue, will result in significant workforce improvements over the next decade. These results support further investment in regional and rural medical education