•Hydrokinetic turbine model designed to optimize the operation at low water velocity.•Experimental tests in a channel with different water upstream velocities.•Peak power depends on the upstream ...velocity and is linked to the blockage intensity.•Results are similar to those obtained by using the Momentum Actuator Disk theory.•A relation between turbine performance and channel slope has been obtained.
Small tidal turbines are considered economical and reliable for distributed electricity generation. Low initial cost and ease of installation make them cover all sides of the economic viability triangle in the energy market. However, operating these turbines under realistic tidal velocities remains a great challenge. The work presented herein involves the design and assessment of a micro vertical axis hydrokinetic turbine, operating at low water velocities. The blade profile, solidity and aspect ratio of the turbine model have been selected looking for a self-starting and efficient operation. Thanks to the continuous development in the additive manufacturing technology, the model can be precisely fabricated at a fraction of the cost offered by traditional machining technologies. Experiments have been performed at three flow rates with a range of inlet velocities from 0.3 to 0.7 m/s. Power curves have been obtained for each operating condition, from zero load up to the point of maximum power. Additionally, the non-dimensional tip speed ratio and power coefficient have been used to compare the performance of the different parameters. It has been found that the upstream velocity has the most obvious effect on the turbine performance, and that the peak power coefficient is linked to the intensification in the blockage ratio. Furthermore, the actuator disc theory adjusted for open channel flow has been compared and found in consonance with the experimental results. This theory has also been employed to define the turbine efficiency which, from 0.45 m/s upwards, is over 70%, and as high as 81%. Finally, the performance in an inclined channel has been analysed, finding the correlations of the maximum power points and their corresponding tip speed ratios as a function of the slope.
The design of lightweight, thermally activated concrete floor systems offers the opportunity to simultaneously tackle two of the most urgent challenges currently faced by the built environment: ...reducing the use of concrete, responsible for 5–8% of global carbon emissions, and implementing energy-efficient cooling strategies to mitigate the consequences of extreme heat events. This paper introduces a novel chilled concrete ceiling technology integrated into the structural floor slab. This system reduces embodied carbon and enhances operational performance through rigorous structural-thermal shape optimization. As a radiant ceiling with embedded water pipes, the system's cooling capacity improves due to the extended exposed surface provided by the shaping. Additionally, condensation risk decreases as thermal comfort is reached through warmer surface temperatures.
Two cooling-dominated climates and five slab geometries are analyzed using a multi-objective optimization approach, achieving Pareto optimal designs that reduce their embodied carbon by up to 52.5% while achieving 12–14% operational savings relative to conventional prismatic floors. The latter can be reduced by as much as 22–32% at the expense of lowering the embodied savings to 30%. Further, this work introduces a novel method for simulating shaped thermally activated surfaces in Building Energy Modeling (BEM) platforms. An equivalent flat slab model is proposed to transfer the complex 3-D heat transfer processes captured by numerical Conjugate Heat Transfer (CHT) methods into annual, climate-specific simulations. This solution offers a flexible and modular framework that allows architects and engineers to replicate the structural-thermal analysis conducted in this work for other locations and geometries of interest.
•Shaped chilled ceilings achieve combined embodied and operational carbon savings.•MOO reveals lightweight floors with high cooling capacity and low condensation risk.•A novel method allows simulating shaped thermally activated surfaces in BEM tools.•The optimal ceiling geometry varies across climates and life-span expectancies.
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•Small hydrokinetic turbine that obtains energy from low velocity water streams.•The current blockage is a key factor on the turbine performance.•Cross-flow simple design based on ...commercial components coupled on a vertical axis.•Tested experimentally on a Hydrodynamic Water.•Experimental results were complemented by simulations of a CFD numerical model.
Obtaining electrical energy from water streams with velocities below one meter per second using hydrokinetic turbines presents an important challenge as it is significantly lower than the range of operations (higher than two meters per second) offered by units currently commercialized. This research goes one step further than the state-of-the-art studies regarding the degree to which energy extraction is influenced by the water flow blockage caused by turbines in water flows; presenting that blockage as a key factor in the procurement of electrical energy using hydrokinetic micro turbines from low-velocity flowing water. Primarily, it describes the design and characterization of a small vertical-axis cross-flow hydrokinetic turbine whose dimensions maximize the blockage of the water circulating in a channel at very low velocity. For the turbine characterization, a model has been tested experimentally in a water tunnel with different flow rates and complemented by simulations under the same conditions using an adjusted computational fluid dynamics model. The experimental tests contemplate the measuring of the turbine’s electrical power, hydraulic coefficient and rotational speeds. The simulations of the numerical model facilitate the procurement of the corresponding water pressure and velocity fields. Further analysis has allowed for a closer examination of the different type of forces exerted on the faces of the blades as well as their position. Upon even closer inspection there appear to be a variety of possible scenarios contingent on the turbine load.
In spite of their increasing popularity, managing the use of wind turbines has been exceptionally challenging. Through computational prognostics, Sentient Science determined that current operating ...lifetime for a large number of turbines is only between five to thirteen years. Initial estimates indicate that savings of $150,000 per turbine per gearbox replacement can be achieved using physics-based long-term prognostics, leading to a substantial return of investment for wind farm operators. However, long-term prognostics require a precise determination of the loads in all six degrees of freedom occurred on the drive-train. One of these loads—torque—can be directly estimated in situ from the historical data provided by the Supervisory Control and Data Acquisition (SCADA) system. In many cases, the historical data only provides 10-min statistical values, and a common practice of reliability analysts is the calculation of torque using only 10-min averages. Disregarding the load fluctuation within 10-min intervals of recorded SCADA introduces a loss of accuracy in the resulting torque histogram that is indeed meaningful for an accurate life prognostic. This paper introduces a novel improved-accuracy method for calculation of torque histograms based on SCADA. Using 10-min distributions of power output and rotor speed, this method is able to successfully reconstruct the distribution of instantaneous torque in between 10-min intervals of recorded SCADA. The method predicts a high-torque region more dispersed that the current method used in the industry, which introduces substantially different results when used in life prognostics. Using this method in the lifing of a GE 1.5 SLE wind turbine, it is shown that the error in predicted L50 is reduced by 10.1%.
•A novel, increased-accuracy method for calculation of fatigue load based on SCADA.•A statistical model of the instantaneous torque within intervals of recorded SCADA.•Recommendations for the numerical implementation of this method.•Inaccuracy of the method currently used in the industry is evidenced.
Aims
Biliary atresia (BA) is characterized by intrahepatic inflammation and rapid progression of liver fibrosis. Galectin‐3, a beta‐galactoside binding protein, is a key regulator of inflammation and ...fibrosis. The aim of this study was to characterize circulating and hepatic Galectin‐3 levels in children with BA.
Methods
Plasma and liver samples were obtained from children with early BA at time of Kasai hepatoportoenterostomy, late BA at time of transplant, early and late other cholestatic liver diseases (CLD), and controls. Plasma Galectin‐3 was measured using standard enzyme‐linked immunoassay. Liver tissue was analyzed with multiplex immunohistochemistry and quantified using whole slide analysis. Statistical comparisons were made using nonparametric testing.
Results
Plasma Galectin‐3 in late BA was significantly higher than in early BA (20.82 12.45–30.46 vs. 11.30 8.74–16.83 ng/mL, p = 0.0096). Galectin‐3 levels correlated with markers of disease severity and interleukin‐6. There were significantly more Galectin‐3+ M2 macrophages in late BA in comparison to late other CLD (162 157–233 vs. 49 33–59 cells/mm2, p = 0.03). The number of Galectin‐3+ M2 macrophages correlated with the number of activated hepatic stellate cells and bile duct proliferation.
Conclusions
Plasma Galectin‐3 is higher in late BA at time of transplant in comparison to early BA at time of Kasai. The number of Galectin‐3 expressing M2 macrophages in late BA is elevated relative to late other CLD and was associated with other prognostic histological findings. Galectin‐3 targeted therapy may be beneficial in slowing disease progression to cirrhosis in children with BA.
Biliary atresia is a congenital disease that leads to cirrhosis in children due to lack of bile flow from the liver. Galectin‐3 is a novel biomarker that is increased in more advanced stages of the disease and correlates with other markers of disease severity and inflammation. Galectin‐3, therefore, could represent a new therapeutic target to increase transplant‐free survival in this patient population.
Abstract
The ability of mesoscale environmental monitoring networks to collect spatially unbiased observations and to detect mesoscale environmental phenomena is radically determined by the spatial ...configuration of the network. However, there is lack of an objective, practical, and amenable method for guiding the spatial configuration of multifunctional, long-term mesoscale networks. The objective of this study is to present and demonstrate the application of a new method based on computational geometry that identifies the optimal location of future monitoring stations by finding the largest unmonitored area of the network. The computation of the method is first illustrated using the spatial distribution of the Kansas Mesonet as a case-study scenario and is then applied to several statewide and nationwide mesoscale networks in the United States. The proposed geometric method was effective to generate a long-term road map with the location of future monitoring stations. The geometric method seamlessly integrated with georeferenced data to identify the largest unmonitored areas with frequent occurrence of wildland fires and severe drought and to identify underrepresented soil types. Spatially dense statewide mesoscale networks with >120 stations across the studied U.S. states resulted in largest unmonitored areas of about 60
2
km
2
, whereas nationwide networks had largest unmonitored areas of 500
2
–600
2
km
2
. The proposed method based on the geometric arrangement of network stations can be used by scientists, network managers, and state climatologists to improve the spatial representability of existing networks, better plan the allocation of limited resources, and increase the preparedness potential of mesoscale networks.
Resumo O artigo aborda como organizações do movimento ambientalista conseguiram estabelecer a moratória da soja na Amazônia brasileira. Articula a perspectiva dos Campos de Ação Estratégica (CAEs) ...com ideias da teoria dos movimentos sociais, abordando os mercados como construções culturais, políticas e históricas. Uma pesquisa qualitativa foi realizada usando dados de múltiplas fontes. Debatendo com autores que conceituaram as estruturas de oportunidades políticas (EOPs) dos mercados, demonstramos que estas podem ser mais bem compreendidas como um conjunto de CAEs interconectados. Para lidar com EOPs fechadas na Amazônia brasileira, as organizações ambientalistas tiveram que mudar estrategicamente a escala de sua atuação e internacionalizar seus protestos, identificando e aproveitando as aberturas em setores e empresas na Europa e pressionando-as a usarem sua força para transformar as práticas das principais tradings de soja.
Abstract The paper addresses how environmental movement organizations were able to establish the soy moratorium in the Brazilian Amazon. It combines the Strategic Action Field (SAFs) perspective with ideas of social movements theory, addressing markets as cultural, political and historical constructions. Qualitative research was conducted using data from multiple sources. Debating with authors who conceptualized the political opportunity structures (POS) of markets, we demonstrate that these may be better understood as an ensemble of interconnected SAFs. In order to deal with closed POS in the Amazon, environmental organizations had to strategically shift the scale and internationalize their protests, identifying and taking advantage of openings in European sectors and companies and pressuring them into using their force to transform the practices of major soy traders.
•Hydraulic model of Nalón River using HEC-RAS and open source geographical data.•Two sections with peak values of hydraulic annual energy.•Micro turbine tidal array to generate energy for an ...intelligent lighting system.•Definition and operation strategy of a Lighting Smart Grid along river mouth.
Tidal energy has significant potential yet to be developed. Sizeable investments, operating costs and environmental impact are barriers that have to date restricted its development. However, microturbine arrays which are viable in coastal locations can help minimize the initial investment as well as operating costs and environmental impact. This paper puts forward a complete smart grid design based on tidal microturbine arrays following a methodology that includes a selection of optimal locations, the design of smart grid tidal generation and consumption components. The methodology has been applied to the estuary of the Nalón River. For the evaluation of the tidal resource and determination of the optimum locations free license software is used to simulate a one-dimensional flow. In order to achieve this, a geometrical model of the river mouth using open source geographic data and nautical information has been built. The results demonstrate high water velocities throughout the year as well as high tidal energy potential in zones that make the installation of a smart grid feasible. This smart grid includes a microturbine tidal array to generate energy and an intelligent Lighting Smart Grid system to light a promenade along the river mouth depicted as an application of the energy produced.
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