Ingeniería Mecánica

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  • Artículo de Publicación Periódica
    An arbitrary order Mixed Virtual Element formulation for coupled multi-dimensional flow problems
    (2022-03) Benedetto, Matías Fernando; Borio, Andrea; Kyburg, Felix E.; Scialò, Stefano; Mollica, Juan
    "Discrete Fracture and Matrix (DFM) models describe fractured porous media as complex sets of 2D planar polygons embedded in a 3D matrix representing the surrounding porous medium. The numerical simulation of the flow in a DFM requires the discretization of partial differential equations on the three dimensional matrix, the planar fractures and the one dimensional fracture intersections, and suitable coupling conditions between entities of different dimensionality need to be added at the various interfaces to close the problem. The present work proposes an arbitrary order implementation of the Virtual Element method in mixed formulation for such multidimensional problems. Details on effective strategies for mesh generation are discussed and implementation aspects are addressed. Several numerical results in various contexts are provided, which showcase the applicability of the method to flow simulations in complex multidimensional domains."
  • Artículo de Publicación Periódica
    Analytical models integrated with satellite images for optimized pest management
    (2016) Bright, L. Zack; Handley, Michael; Chien, Isabel; Curi, Sebastián; Anders Brownworth, L.; D'hers, Sebastián; Bernier, Ulrich R.; Gurman, Pablo; Elman, Noel M.
    "The global field protection (GFP) was developed to protect and optimize pest management resources integrating satellite images for precise field demarcation with physical models of controlled release devices of pesticides to protect large fields. The GFP was implemented using a graphical user interface to aid the end-user to select location and define an arbitrary perimeter for protection. The system provides coordinates of drop points for the controlled release devices which can be delivered using drone technology, e.g. unmanned air vehicles. In this work, we present the first proof of concept of this technology. A vast number of pest management applications can benefit from this work, including prevention against vector-borne diseases as well as protection of large agriculture fields."
  • Artículo de Publicación Periódica
    A combined experimental-computational approach for spatial protection efficacy assessment of controlled release devices against mosquitoes (Anopheles)
    (2018-03) Bernier, Ulrich R.; Kline, Daniel L.; Abad Vázquez, Agustín; Perry, Melynda; Cohnstaedt, Lee W.; Gurman, Pablo; D'hers, Sebastián; Elman, Noel M.
    "This work describes the use of entomological studies combined with in silico models (computer simulations derived from numerical models) to assess the efficacy of a novel device for controlled release of spatial repellents. Controlled Release Devices (CRDs) were tested with different concentrations of metofluthrin and tested against An. quadrimaculatus mosquitoes using arm-in cage, semi-field, and outdoor studies. Arm-in-cage trials showed an approximate mean values for mosquito knockdown of 40% and mosquito bite reduction of 80% for the optimal metofluthrin formulation for a 15-minute trial. Semi-field outdoor studies showed a mean mortality of a 50% for 24 hour trial and 75% for a 48 hour trial for optimal concentrations. Outdoors studies showed an approximate mean mortality rate of 50% for a 24 hour trial for optimal concentrations. Numerical simulations based on Computational Fluid Dynamics (CFD) were performed in order to obtain spatial concentration profiles for 24 hour and 48 hour periods. Experimental results were correlated with simulation results in order to obtain a functional model that linked mosquito mortality with the estimated spatial concentration for a given period of time. Such correlation provides a powerful insight in predicting the effectiveness of the CRDs as a vector-control tool. While CRDs represent an alternative to current spatial repellent delivery methods, such as coils, candles, electric repellents, and passive emanators based on impregnated strips, the presented method can be applied to any spatial vector control treatment by correlating entomological endpoints, i.e. mortality, with in-silico simulations to predict overall efficacy. The presented work therefore presents a new methodology for improving design, development and deployment of vector-control tools to reduce transmission of vector-borne diseases, including malaria and dengue."
  • Artículo de Publicación Periódica
    Rapid reconstitution packages (RRPs) for stable storage and delivery of glucagon
    (2019-06) D'hers, Sebastián; Abad Vázquez, Agustín; Gurman, Pablo; Elman, Noel M.
    "Current emergency injectors of glucagon require manual reconstitution, which involves several steps that may lead to dosage errors. Rapid reconstitution packages (RRPs) are new devices, designed using computational fluid dynamics (CFD) to optimize fluid mixing, integrating physical properties of active pharmaceutical ingredients (APIs), excipients and diluents. RRPs improve drug stability for long-term storage and ease of delivery. Device prototypes were manufactured using advanced stereolithography apparatus (SLA) 3D printing technology. Reconstitution of glucagon with RRPs was evaluated by highperformance liquid chromatography (HPLC) and optical spectroscopy methods. Enzyme-linked immunosorbent assays were performed to test in vitro activity. Experimental results showed that RRPs effectively reconstituted glucagon even after exposure to 60 °C for a 24-h period. RRPs exhibited improved performance at maintaining drug stability compared to lyophilized glucagon stored in a standard glass vial under the same temperature conditions. RRPs represent a portable platform for rapid reconstitution of lyophilized drugs, compatible with standard syringes available in any clinical setting. The RRP provides an alternative to manual reconstitution process, especially designed for medical emergencies."
  • Artículo de Publicación Periódica
    A technical, environmental and financial analysis of hybrid buses used for public transport
    (2018-04) Orbaiz, Pedro; Dijk, Nicolás van; Cosentino, Santiago; Oxenford, Nicolás; Carignano, Mauro G.; Nigro, Norberto M.
    "This paper presents a technical, financial and environmental analysis of four different hybrid buses operated under Buenos Aires driving conditions. A conventional diesel bus is used as reference and three electric hybrids equipped with different energy storage technologies, Li-Ion, NiMH batteries and double layer capacitors (ultracapacitors), are evaluated, along with a hydraulic hybrid platform which uses high-pressure accumulators as its energy buffer. The operating conditions of the buses are set using real driving GPS data collected from various bus routes within the city. The different vehicle platforms are modeled on AUTONOMIE SA and validated by comparing the obtained fuel consumption results to those reported by local transport authorities and values found in the literature. The embedded energy and CO2 emissions of each platform are estimated using GREET and the total cost of ownership of each vehicle is calculated and compared to that of the conventional bus. Furthermore, aging models are proposed to evaluate the life duration of the batteries and ultracapacitors. Results show that, independent of the energy storage technology, the fuel economy performance of all hybrids is highly dependent on the size and configuration of the powertrain and energy storage components. When optimized, all hybrids achieve significant fuel consumption reductions compared to a conventional diesel bus, however, the ultracapacitor based system seems to outperform the other technologies. The battery based electric buses achieve similar fuel consumption reductions, but the NiMH based batteries shows a considerably shorter life expectancy. This has a significant impact on both the economic and environmental performance of this vehicle. The life cycle emission analysis shows that, given the high fuel consumption of a conventional bus, the additional embedded CO2 emissions of the hybrid vehicles are offseted by the achieved reduction of in-service CO2 emissions due to fuel consumption reductions. Regarding the economic performance of the different platforms, results show that the fuel savings achieved by all hybrids displace the higher capital costs required. Overall, all hybrid buses show a strong potential to reduce both CO2 emissions and costs, resulting in negative costs of CO2 abatement."
  • Artículo de Publicación Periódica
    Controlled release spatial repellent devices (CRDs) as novel tools against malaria transmission: a semi‑field study in Macha, Zambia
    (2018-11) Stevenson, Jennifer C.; Simubali, Limonty; Mudenda, Twig; Cardol, Esther; Bernier, Ulrich R.; Abad Vázquez, Agustín; Thuma, Philip E.; Norris, Douglas E.; Perry, Melynda; Kline, Daniel L.; Cohnstaedt, Lee W.; Gurman, Pablo; D'hers, Sebastián; Elman, Noel M.
    "The emergence of mosquitoes that can avoid indoor-deployed interventions, such as treated bed nets and indoor residual spraying, threatens the mainstay of malaria control in Zambia. Furthermore, the requirement for high coverage of these tools poses operational challenges. Spatial repellents are being assessed to supplement these vector control tools, but limitations exist in the residual effect of the repellent and the need for external power or heat for diffusion of the volatiles."
  • Artículo de Publicación Periódica
    Microfluidic device concept based on microoscillator dynamics at a liquid–liquid interface
    (2008) Allievi, Alejandro
    "Oscillating microbeams and microplates have been used extensively as sensing components for property detection in fluids. In liquids, their quality factor Q is drastically decreased, thus affecting a microsensor’s resolution. To improve the Q-factor, we present a novel concept based on the positive use of surface tension on a mechanical oscillator composed of a microbeam–microplate assembly suspended at a liquid–liquid interface in a microfluidic channel. An analytical model is developed to investigate rotational dynamics of such an assembly..."
  • Artículo de Publicación Periódica
    Hybridisation effect on operating costs and optimal sizing of components for hybrid electric vehicles
    (2017-07) Carignano, Mauro G.; Nigro, Norberto M.; Junco, Sergio; Orbaiz, Pedro
    "Reductions of fuel consumption and gas emissions count among the main advantages of hybrid electric vehicles (HEV). It is well known that the level of hybridisation has a large influence on the fuel consumption, the manufacturing cost and the battery lifetime. Therefore, a proper selection of the size of components could be the result of a trade-off between them. This paper provides models and a methodology to address the sizing of components of a HEV. Specifically the work is focused on the series architecture with internal combustion engine and battery. The sizing criteria are oriented to reduce the operating costs, in which are included the fuel consumption and the battery-life consumption. Finally, the methodology proposed is applied in a case study. It corresponds to a real hybrid electric bus operating under urban driving conditions. Simulation results show that the best solutions are obtained by oversizing the battery with respect to power requirements."
  • Artículo de Publicación Periódica
    Planar nozzles for controllable microthrusters
    (2017) Pedreira, Patricio; Lauretta, Juan Ricardo; D'hers, Sebastián
    "Orbital maneuvering of microsatellite and nanosatellite requirements can be efficiently addressed by planar nozzles, in which realtime thrust control is gained actuating on the nozzle throat area. In the present work, the method of characteristics is used to design a hypersonic contour; then, the resulting profile is laser cut, assembled, and built into a propulsion system to finally perform tests in a vacuum chamber under several working conditions. Results are used to validate the profile and modeling assumptions and investigate overall behavior. Tests showed that thrust-inlet pressure ratio is a linear function of separation between nozzle contours and that no additional losses are introduced in the system. The corresponding design/manufacture/assembly tools can be used to a provide low-cost/low-weight controllable propulsion systems to the small-satellite industry with no efficiency loss."