447 research outputs found

    Numerical framework for transcritical real-fluid reacting flow simulations using the flamelet progress variable approach

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    An extension to the classical FPV model is developed for transcritical real-fluid combustion simulations in the context of finite volume, fully compressible, explicit solvers. A double-flux model is developed for transcritical flows to eliminate the spurious pressure oscillations. A hybrid scheme with entropy-stable flux correction is formulated to robustly represent large density ratios. The thermodynamics for ideal-gas values is modeled by a linearized specific heat ratio model. Parameters needed for the cubic EoS are pre-tabulated for the evaluation of departure functions and a quadratic expression is used to recover the attraction parameter. The novelty of the proposed approach lies in the ability to account for pressure and temperature variations from the baseline table. Cryogenic LOX/GH2 mixing and reacting cases are performed to demonstrate the capability of the proposed approach in multidimensional simulations. The proposed combustion model and numerical schemes are directly applicable for LES simulations of real applications under transcritical conditions.Comment: 55th AIAA Aerospace Sciences Meeting, Dallas, T

    Is Venice an ideal habitat for Legionella pneumophila?

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    Introduction. Legionella bacterium manifests itself in Legion- naire?s disease and Pontiac fever, it is mainly found and trans- mitted by aerosol produced in cooling towers, water distribution plants and medical equipment, and it affects mainly elder persons in poor health. Methods. The population of Venice Local Health Unit was divided in two areas of study and the incidence of legionellosis in residents of Venice historical centre (Distretto Sanitario 1) and in residents of the mainland and coastal areas (Distretti Sanitari 2, 3, 4) was calculated. The cases were those notified to the Public Health Unit by law, and the population of residents was that of the eligible for health care in the archives of the Local Health Unit. Only cases of legionellosis in residents who had not travelled in the 10 days previous of the onset of disease, and not related to nosocomial clusters were considered. The standardized incidence ratio was then calculated and confidence interval were defined by Poisson distribution. Results. Given the population of the two areas, 59801 in Distretto Sanitario 1 and 237555 in Distretti 2, 3, 4, the raw incidence of disease is respectively 87 per 100000 and 20 per 100000 in time 2002-2010. The standardized incidence ratio for the population of Distretto Sanitario 1 vs the remaining population is 4.3. Discussion. The difference in risk of getting the disease in this two residential areas geographically very close, is probably related to the different buildings? characteristics, old and difficult to main- tain in Venice historical centre

    Redefining the technical and organizationalcompetences of children vaccination clinics in order to improve performance. A practical experience at the ULSS 12 Venetian Public Health and Hygiene Service

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    Introduction. Since Regione Veneto suspended compulsory vaccination for children in 2008, and because of an increasing disaffection of parents to the vaccine practice, the vaccination rates have been slowly but steadily decreasing. The aim of this study was to analyze internal and external factors of immuniza- tion reduction and to implement potential solutions of the prob- lem. Methods. Servizio Igiene e Sanita? Pubblica of ULSS 12 Venezi- ana (SISP ? Hygiene and Public Health Service) analyzed and addressed both, the reasons of parents who do not vaccinate their children and the internal problems regarding vaccination clinics management, information to families, procedures and guidelines and, in general, the communication skills of the vaccination staff. Results. A positive trend in vaccination rates was observed, espe- cially in Venice historical centre. Moreover the staff reported a better working atmosphere and benefit from sharing common goals and procedures, even though the workforce was reduced of about 30% in terms of equivalent unit (EU). Discussion. The continuous quality improvement method fol- lowed in this experience led to a steady increase in vaccination coverage in all territorial clinics, to a better adhesion of guide- lines and standard operating procedures and to a general pro- fessional empowerment of SISP staff. The service now offered to the population is better and more efficient, since the workforce has been reduced. Future goals are to improve information about vaccinations among the population

    Parallelized Incomplete Poisson Preconditioner in Cloth Simulation

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    Efficient cloth simulation is an important problem for interactive applications that involve virtual humans, such as computer games. A common aspect of many methods that have been developed to simulate cloth is a linear system of equations, which is commonly solved using conjugate gradient or multi-grid approaches. In this paper, we introduce to the computer gaming community a recently proposed preconditioner, the incomplete Poisson preconditioner, for conjugate gradient solvers. We show that the parallelized incomplete Poisson preconditioner (PIPP) performs as well as the current state-of-the-art preconditioners, while being much more amenable to standard thread-level parallelism. We demonstrate our results on an 8-core Apple* Mac* Pro and a 32-core code name Emerald Ridge system
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