SHAPE Project Vortex Bladeless: Parallel multi-code coupling for Fluid-Structure Interaction in Wind Energy Generation

Vortex-Bladeless is a Spanish SME whose objective is to develop a new concept of wind turbine without blades called Vortex or vorticity wind turbine. This design represents a new paradigm in wind energy and aims to eliminate or reduce many of the existing problems in conventional generators. Due to the significant difference in the project concept, its scope is different from conventional wind turbines. It is particularly suitable for offshore configuration and it could be exploited in wind farms and in environments usually closed to existing ones due to the presence of high intensity winds. The device is composed of a single structural component, and given its morphological simplicity, its manufacturing, transport, storage and installation has clear advantages. The new wind turbine design has no bearings, gears, etcetera, so the maintenance requirements could be drastically reduced and their lifespan is expected to be higher than traditional wind turbines. It is clear that the proposed device is of prime interest, and that scientific investigation of the response of this wind energy generator under different operation scenarios is highly desirable. Thus, the objective of this SHAPE project is to develop the needed tools to simulate Fluid-Structure Interaction (FSI) problems and to reproduce the experimental results for scaled models of the Vortex-Bladeless device. In order to do so the Alya code, developed at the Barcelona Supercomputing Center, is adapted to perform the Fluid-Structure Interaction (FSI) problem simulation. The obtained numerical results match satisfactorily with the experimental results reported.This work was financially supported by the PRACE project funded in part by the EU’s Horizon 2020 research and innovation programme (2014-2020) under grant agreement 653838.Postprint (published version

SFC based multi-partitioning for accurate load balancing of CFD simulations

International audienceIn the context of multi-physics simulations on unstructured and heterogeneous meshes, generating well-balanced partitions is not trivial. The computing cost per mesh element in different phases of the simulation depends on various factors such as its type, its connectivity with neighboring elements or its layout in memory with respect to them, which determines the data locality. Moreover, if different types of discretization methods or computing devices are combined, the performance variability across the domain increases. Due to all these factors, evaluate a representative computing cost per mesh element, to generate well-balanced partitions, is a difficult task. Nonetheless, load balancing is a critical aspect of the efficient use of extreme scale systems since idle-times can represent a huge waste of resources, particularly when a single process delays the overall simulation. In this context, we present some improvements carried out on an in-house geometric mesh par-titioner based on the Hilbert Space-Filling Curve. We have previously tested its effectiveness by partitioning meshes with up to 30 million elements in a few tenths of milliseconds using up to 4096 CPU cores, and we have leveraged its performance to develop an autotuning approach to adjust the load balancing according to runtime measurements. In this paper, we address the problem of having different load distributions in different phases of the simulation, particularly in the matrix assembly and in the solution of the linear system. We consider a multi-partition approach to ensure a proper load balance in all the phases. The initial results presented show the potential of this strategy

The cooperative parallel: A discussion about run-time schedulers for nested parallelism

Nested parallelism is a well-known parallelization strategy to exploit irregular parallelism in HPC applications. This strategy also fits in critical real-time embedded systems, composed of a set of concurrent functionalities. In this case, nested parallelism can be used to further exploit the parallelism of each functionality. However, current run-time implementations of nested parallelism can produce inefficiencies and load imbalance. Moreover, in critical real-time embedded systems, it may lead to incorrect executions due to, for instance, a work non-conserving scheduler. In both cases, the reason is that the teams of OpenMP threads are a black-box for the scheduler, i.e., the scheduler that assigns OpenMP threads and tasks to the set of available computing resources is agnostic to the internal execution of each team. This paper proposes a new run-time scheduler that considers dynamic information of the OpenMP threads and tasks running within several concurrent teams, i.e., concurrent parallel regions. This information may include the existence of OpenMP threads waiting in a barrier and the priority of tasks ready to execute. By making the concurrent parallel regions to cooperate, the shared computing resources can be better controlled and a work conserving and priority driven scheduler can be guaranteed.Peer ReviewedPostprint (author's final draft

The UALE project : a cross-sectional approach for trends in HIV/STI prevalence among key populations attending STI clinics in Guatemala

To describe and compare trends in prevalence, sexual behaviour and HIV transmission knowledge data related to sexually transmitted infections (STI) and HIV in patients attending three STI clinics over an 8-year period in Escuintla Department, Guatemala. STI clinic attendees were classified into transmission groups as follows: female sex workers (FSW), men who have sex with men (MSM) and 'high-risk heterosexuals' (HRH). Annual cross-sectional analysis and multivariable Poisson regression adjusted for sociodemographic variables were used for prevalence comparisons and adjusted prevalence trends for HIV/STI outcomes and used for adjusted trends in proportions in sexual behaviour and HIV transmission knowledge outcomes. Endocervical swabs were obtained to detect trichomonas, chlamydia and neisseria infections. Serologies for syphilis and HIV were performed using rapid tests. For reactive HIV samples, positivity was confirmed by an ELISA. All reactive syphilis samples were further confirmed for diagnosis of active syphilis disease. From a total of 4027 clinic attendees, 3213 (79.78%) were FSW, 229 (5.69%) were MSM and 585 (14.53%) were HRH. The proportion of FSW, MSM and HRH who had a single visit was 56.42%, 57.23% and 91.10%, respectively. Overall, HIV prevalence was 2.10% in FSW, 8.17% in MSM and 4.12% in HRH. Prevalence trends in HIV and syphilis decreased in FSW. Prevalence trends in gonorrhoea did not decrease over time neither in FSW nor in HRH. Chlamydia and trichomonas infections in HRH showed an increase prevalence trend. In FSW, trends in condom use in last sexual intercourse with regular and occasional clients were above 93%. FSW show a decreasing trend in HIV, syphilis and chlamydia prevalence. Gonorrhoea prevalence in FSW and HRH did not decrease over time. HRH is a hard to engage population with low follow-up rates and high potential to act as a bridge population

Effects of Milled Maize Stalks on the Productive Response of Grazing Dairy Cows.

The productive response of grazing dairy cows was evaluated, using milled corn stalks in the diet. The study was developed in two different settings, in Ecuador (Costa and Sierra regions). On the coast farm (29.1 ha), cows grazed on Bermuda grass (Cynodon nlemfuensis) and Guinea grass (Panicum maximum) with several types of legumes (Lysicarpus, Centrosema, Desmodium, Galactia), supplemented with corn stalks cv. INIAP 125. The animals received 0.46 kg beginning at 3 kg, and milled maize stalks in 30 and 28-day periods, respectively (M-30 and M-28), and control without stalks for 36 days (M-0). The farm in the other region (14.2 ha) had 23 cows grazing on Kikuyo grass (P. clandestinum) and ryegrass-white clover (L. perenne and whole maize stalks and T. (60-70% ripe grain), at a rate of 18 kg green/cow/day for 48 days; and balanced supplement, at a rate of 0.5 kg/ milk liter, after the fourth kilogram, along with minerals. In both cases the forage had effects (P < 0.05) on cow response. In the Sierra area, the increase was 1.68 kg/cow, and in the coast, it was 1.1 and 2.5 kg/cow). Maize stalks served as a nutritional complement for poorly consumed grass areas in both regions; milk production/animal was increased, and the costs were reduced

Leucaena leucocephala cv Perú in Association with Graminaceae in Dryland Conditions for Final Bovine Fattening Stage

To evaluate the factors that affect efficiency in a Leucaena leucocephala cv Perú association, with pastures for bovine fattening, 22 Zebu fattening cycles were studied on a farm of the Rectangulo Livestock Company, in Camagüey, Cuba, between 2002 and 2012. The local soil is brown without carbonates. The climate is tropical humid, and the annual precipitation average is 1 183mm. The factors evaluated were food balance, duration of the fattening cycle, and quantity of animals/cycle. The daily weight gain and expenses/income per operation were also analyzed. The pasture and Leucaena percentages were determined by plant counts. Food balances were estimated. The final value of the population of Leucaena cv Perú was 93% (P <0.05), with an increase in common Bermuda grass and other pastures. Short duration tests showed much higher gains (P <0.05), with values above 1.0 kg/animal/day. The number of animal/cycle (P <0.05) produced higher gains with fewer animals. Forest-grazing in association with Leucaena leucocephala cv Perú-graminaceae under dryland conditions produced mean daily gains above 0.800 kg/animal/day in the final stage of fattening bulls, based on food balances with adequate biological and economic results. The best behavior was observed in the shortest cycles, where the highest final weight/animal values were achieved, with fewer expenses and higher income

Bio-economic Impact of Strategic Changes in Murrah River Buffalo Management

The aim of this paper was to evaluate the effects of changes in the strategy to manage the bio-economic efficiency of a Murrah Buffalo production system in the province of Camagüey, Cuba, located 21º north and 77º west, 217 meters above sea level. The climate is tropical humid (Aw) of plains. The mean annual precipitations were 1 180 mm (71% between May and October), the temperatures were between 24 and 29 °C. The soil is brown, without carbonates, and brown-red fersiallitic. The system comprises 5 100 ha and has 536 workers/year. A strategy to introduce management changes in agro-technical, food, reproductive, replacement, health, salary policy, and training was implemented as part of an innovation package with a systemic and participatory approach. The evaluation lasted eight years, and it was critical to increase dairy production in more than 200 000 kg/year in 2012, in comparison to 2004, with improvements in natality and reduction of operational expenses of the system. It was concluded that the strategy had a determining effect on the system's indicators

Risk Factors for Ocular Infection with Chlamydia trachomatis in Children 6 Months following Mass Treatment in Tanzania

Trachoma control programs aim for high coverage of endemic communities with oral azithromycin to reduce the pool of infection with Chlamydia trachomatis. However, even with high coverage, infection is seen following treatment. In four communities in Tanzania, we followed every child aged under ten years from baseline through treatment to six months post-treatment. We determined who had infection at baseline and who still had or developed infection six months later. Coverage was over 95% in children in these communities, and infection in these children decreased by over 50% at six months. The study found that, at baseline, uninfected children who were treated had prevalence of infection at 6 months of 6%, but infected children who were treated had prevalence of infection of 22% at 6 months. Other risk factors for infection at 6 months included living in a household with other infected children, and living in a household with untreated children. Our data suggest that households with untreated children might be targeted for more intensive follow up to increase coverage and reduce subsequent infection in the community