Numerical study on the internal flow field of a reversible turbine during continuous guide vane closing

The unsteady flow field in a reversible pump-turbine is investigated during the continuous load rejection using a 3D computational fluid dynamic analysis. Numerical calculations are carried out using the detached eddy simulation (DES) turbulence model and a new approach involving automatic mesh motion. In this way, the instability of the flow field is analyzed by continuously changing the guide vane openings from the best efficiency point (BEP). Unsteady flow characteristics are described by post-processing signals for several monitoring points including mass flow, torque, head and pressure in the frequency and time-frequency domains. The formation of vortices of different scales is observed from the origin to further enlargement and stabilization; the effect of the rotating structures on the flow passage is analyzed, and the influence of unsteady flow development on the performance of the turbine is investigated. Finally, the evolution during the period of load rejection is characterized in order to determine the hydrodynamic conditions causing the vibrations in the machine

Development of an open source environment for the aero-structural optimization of wind turbines

An advanced open source optimization environment, for the design of Horizontal and Vertical Axis Wind Turbines, is hereby presented: several geometric parameters can be used as design variables while the proposed objective functions allow to run a multi-disciplinary study considering structural and aerodynamic analysis and the impact of the design on the total cost. In order to improve the performances of the considered wind turbine model, the airfoils can be parametrized in serveral ways and both in-house functions and open source tools are integrated in the optimization environment, based on DAKOTA. A BEM code evaluates the aerodynamic performances of the HAWT blades and it can be coupled with both FEM analysis and functions for the analysis of the cost of energy. The open source CFD code OpenFOAM has also been included, as a module, in the overall environment: a CFD analysis can be run in an completely automatic way, from the denition of the geometry, through the generation of the mesh and the solving phase to the post-processing analysis. The proposed optimization environment succeeded in improving the performances of both the considered Horizontal and Vertical Axis Wind Turbines in terms of structural, aerodynamic and cost objective functions

PV-PCM integration in glazed building. Co-simulation and genetic optimization study

The study describes a multi-objective optimization algorithm for an innovative integration of forced ventilated PV-PCM modules in glazed fa\ue7ade buildings: the aim is to identify and optimize the parameters that most affect thermal and energy performances. 1-D model, finite difference method FDM, thermal resistances technique and enthalpy method were applied to describe different fa\ue7ade solutions and transient thermal performance of PCM. The coupling between the PV-PCM fa\ue7ade code implemented in MATLAB and the TRNSYS software was developed to estimate the dynamic thermal energy profiles. An exploratory step has also been considered prior to the optimization algorithm: it evaluates the energy profiles before and after the application of PCM to PV module integrated in glazed building. The optimization analysis investigate parameters such as ventilation flow rates and time schedule to obtain the best combination suiting the PCM performance and external-internal loads. A group of solution were identified on the Pareto front. Savings in thermal loads for the best individual reached 26.4% while the best in temperature increment in operating temperatures was recorded as 6.8% comparing to the design set temperature

Activation of the Thiazide-Sensitive Sodium-Chloride Cotransporter by Beta3-Adrenoreceptor in the Distal Convoluted Tubule

We previously showed that the beta-3 adrenergic receptor (BAR3) is expressed in most segments of the nephron where its agonism promotes a potent antidiuretic effect. We localized BAR3 in distal convoluted tubule (DCT) cells expressing the thiazide-sensitive sodium-chloride cotransporter (NCC). Aim of this study is to investigate the possible functional role of BAR3 on NCC modulation in DCT cells. Here, we found that, in mice, the knockout of BAR3 was paralleled by a significant attenuation of NCC phosphorylation, paralleled by reduced expression and activation of STE-20/SPS1-related proline-alanine-rich kinase (SPAK) and WNKs the main kinases involved in NCC activation. Conversely, in BAR1/2 knockout mice, we found reduced NCC abundance with no changes in the phosphorylation state of NCC. Moreover, selective BAR3 agonism promotes both SPAK and NCC activation in wild-type mouse kidney slices. In conclusion, our findings suggest a novel role for BAR3 in the regulation of NCC in DCT

Performance, environmental, and mobility analysis of large capacity fast rotorcraft configurations for the European regional air traffic market

Fast, large rotorcraft are of interest in the future European air transport system due to their runway independent operation and potential mobility improvements for the passenger. Both a tiltrotor and a coaxial compound concept model were developed for a 70 passenger, 500 NM design mission that would compete with regional fixed-wing aircraft. These models were flown along virtual trajectories representing possible use-cases and assessed for environmental performance in comparison to an in-service baseline aircraft using comparable engine technology levels. Further, the travel time and mobility improvement available to the intermodal transport network through the inclusion of these concept rotorcraft was examined with promising results. Future work is suggested to address the shortfall in environmental performance

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Development of an open source environment for the aero-structural optimization of wind turbines

An advanced open source optimization environment, for the design of Horizontal and Vertical Axis Wind Turbines, is hereby presented: several geometric parameters can be used as design variables while the proposed objective functions allow to run a multi-disciplinary study considering structural and aerodynamic analysis and the impact of the design on the total cost. In order to improve the performances of the considered wind turbine model, the airfoils can be parametrized in serveral ways and both in-house functions and open source tools are integrated in the optimization environment, based on DAKOTA. A BEM code evaluates the aerodynamic performances of the HAWT blades and it can be coupled with both FEM analysis and functions for the analysis of the cost of energy. The open source CFD code OpenFOAM has also been included, as a module, in the overall environment: a CFD analysis can be run in an completely automatic way, from the denition of the geometry, through the generation of the mesh and the solving phase to the post-processing analysis. The proposed optimization environment succeeded in improving the performances of both the considered Horizontal and Vertical Axis Wind Turbines in terms of structural, aerodynamic and cost objective functions.Nella tesi è presentato un ambiente avanzato per l'ottimizzazione delle turbine eoliche sia ad asse orizzontale che verticale. Le variabili di design sono rappresentate da diversi parametri geometrici mentre le funzioni obiettivo implementate permettono di eseguire un’analisi multidisciplinare considerando gli aspetti strutturali, aerodinamici e l'impatto del design sul costo complessivo. Allo scopo di aumentare le prestazioni delle turbine considerate, i profili aerodinamici possono essere parametrizzati in diversi modi. Diverse funzioni appositamente sviluppate e tools open source sono stati integrati nell'ambiente di ottimizzazione, basato su DAKOTA. Un codice BEM valuta le prestazioni aerodinamiche dei modelli ad asse orizzontale e può essere accoppiato sia con codici FEM, sia con funzioni allo scopo di valutare il costo dell’energia. Il codice CFD open source OpenFOAM è stato incluso, come modulo, nell’ambiente: un analisi CFD può essere eseguita in un modo completamente automatico dalla definizione della geometria, generazione della mesh, fase di risoluzione numerica all’analisi dei risultati. L’ambiente di ottimizzazione proposto ha dimostrato di poter migliorare le prestazioni di entrambi i modelli di turbina eolica considerati, in termini di obiettivi strutturali, aerodinamici e di costo

Wind turbine research activity at University of Padova

COMETES research group of University of Padova presents its research activities regarding design and numerical analysis of wind turbines. The main topics treated are: development of 1D BEM and 2D-3D CFD models, aero-structural analysis and multi-objective optimisations, implementation of fully automatic OpenSource environment for HAWT / VAWT aerodynamic analysis and unsteady CFD simulation of wind turbine operating under gust conditions

PV-PCM system integrated into a double skin façade. A Genetic optimization based study for the PCM type selection

This paper reports the results of a genetic optimisation based numerical analysis of a PV-PCM system integrated into a double skin façade. The aim of the research activity was to develop and test the performance of a proposed simulation approach to identify the optimal configuration of the PCM layer, in terms of temperature transition range, and thickness, to assure the best energy performance of the façade system. Furthermore, because of the intimate relationship between the PCM’s features and the ventilated cavity to define the performance of the façade system, the domain of exploration included as variable the airflow rate and ventilation schedule. The evaluation of the performances of the PV-PCM glazed facade is carried through an onpurpose developed, transient 1-D (with finite difference method) heat transfer model, which integrates a suitable representation of the PCM’s system (through the so-called enthalpy method) to include the thermophysical behviour of such a type of materials. This numerical model is implemented in MATLAB and coupled to TRNSYS in order to calculate the dynamic thermal energy profiles of a fictitious building equipped with such a façade. The subsequent single objective optimization is based on a genetic algorithm, which looks for the best PCM type and schedule of ventilation in order to optimize the summer thermal energy performance in two case-study cities, Venice and Chicago. The results show how the proposed genetic optimisation algorithm is capable of identifying the most suitable configuration (that differs in each climate) after a relatively small number of generations (ca. 25). Furthermore, the optimisation approach used in this study leads to the identification of configurations capable of assuring a reduction in the cooling energy need (objective function) in the range 28% to 19 %, when compared to non-optimal configurations, for the two case-study cities

Extensive Validation of HAWT Unsteady Modelling Using BEM and CFD

The present work aims to present two different approaches to model the unsteady aerodynamics of horizontal-axis wind turbines (HAWTs). A complete and extensive comparison has been established between the results obtained using a low-fidelity calculation tool, as the Blade Element Momentum (BEM), and a high-fidelity technique, as the Computational Fluid Dynamics (CFD). Regarding the first calculation strategy, an accurate revision in polar diagrams calculation and the implementation of yaw and dynamic stall routines have endowed the BEM code to predict the machine performance under unsteady flow conditions. In order to achieve an accurate validation, the proposed BEM solver has been tested on AOC 15/50 and NREL Phase VI wind turbines. Referring to CFD techniques, a three-dimensional unsteady model has been improved to study the aerodynamic behaviour of the machine in case of yawed incoming wind