641 research outputs found
Nearest transfer effects of working memory training: A comparison of two programs focused on working memory updating
This study analyzed the mechanisms involved in possible transfer effects for two different working memory updating (WMU) training programs administered to young adults and based on two updating paradigms: n-back and arithmetical updating. The influence of practice distribution on transfer effects was also explored by including two training regimens: massed and spaced practice. Performance on different WMU tasks more or less structurally similar to the tasks used in the training was assessed to analyze the nearest transfer effects. Near and far transfer effects were tested using complex working memory (WM) and fluid intelligence tasks. The results showed that the WMU training produced gains in only some of the WMU tasks structurally similar to those used in the training, not in those lacking the same structure, or in WM or fluid intelligence tasks. These limited nearest transfer effects suggest that gains could be due to the acquisition of a specific strategy appropriate for the task during the training rather than to any improvement in the updating process per se. Performance did not differ depending on the training regimen
BIM-based LCSA application in early design stages using IFC
Life Cycle Sustainability Assessment (LCSA) is an integrated method that combines environmental, economic, and social assessments. Its methodological development remains under discussion, mainly regarding the building design. This paper aims to provide a systematic, interoperable, and open-source approach towards implementing LCSA in Building Information Modelling (BIM) in five steps. A harmonized data structure that enriches BIM objects is proposed. Automation in the principal evaluation step is provided by integrating new parameters into the current Industry Foundation Classes (IFC4). A Dynamo script verifies its utility in a case study in Spain using real-time calculations and visualizations. Two alternative structural systems are assessed, and identification is made of the lowest CO2 emitter, the lowest cost, and the most beneficial system for local employment. The approach can be employed to evaluate other indicators and building systems in other countries. Challenges and limitations in the standardization and harmonization of the three dimensions are identified
Significance of the particle physical properties and the Geldart group in the use of correlations for the prediction of minimum fluidization velocity of biomass–sand binary mixtures
The present study explores the relevance of the physical properties of biomass particles on the determination of the minimum fluidization velocity (U-mf) of binary mixtures. Fluidization experiments were performed in a cold flow unit with diverse biomasses mixed with sand in different mass fractions. Gas velocity and pressure drop across the bed were used to determine U-mf. Different correlations reported in the literature were evaluated on their ability to accurately predict U-mf of the mixtures. Results showed satisfactory predictions when appropriately identifying correlations according to the corresponding Geldart groups for the biomass particles. This perspective opens new possibilities toward the generalization of correlation factors and helps in improving the accuracy of the prediction for highly heterogeneous mixtures. The methodology also allows the analysis of mixtures for which the experimental approach is difficult, such as those including char particle, with the only requirement of carefully measuring the physical properties of the particles
REDES NEURONALES EN LA PREDICCI 3N DE MICRO-CLIMA, ZONA DE ESTUDIO LA HECHICERA M\uc9RIDA, VENEZUELA
Se desarroll\uf3 una Red Neuronal Artificial (RNA) con capacidad para realizar predicciones clim\ue1ticas a corto plazo, entrenada con datos a intervalos de 15 min durante 454 d\uedas, de una estaci\uf3n climatol\uf3gica ubicada en La Hechicera M\ue9rida-Venezuela (1896 msnm). Para el entrenamiento y su validaci\uf3n se usaron patrones simulados que contienen variaciones diarias de la radiancia y la temperatura. Se eligieron 3 funciones de prueba tales como el Seno, Coseno y los Polinomios de Legendre Pl(x). La (RNA) p.ej, puede predecir el intervalo (0,1] usando s\uf3lo como entrada el intervalo [-1,0] de la correspondiente derivada P\ub4l (x) del polinomio. En la fase de producci\uf3n con datos reales, se encontr\uf3 que la red es capaz de predecir la temperatura con un 5% de error en el rango horario [12:15 a 06:15] pm, s\uf3lo con los datos de temperatura en el rango [6:00 a 12:00) am. Igualmente al predecir temperatura a partir de radiancia (5 %), radiancia-radiancia (16 %). Se considera viable el uso de (RNA) para la predicci\uf3n de micro-clima a corto plazo, pudiendo extender su uso a otras localidades, lo que podr\ueda ser \ufatil para el desarrollo de planes de prevenci\uf3n de desastres, per\uedodos de siembra y en la predicci\uf3n de oferta de energ\ueda en plantas e\uf3licas y solares.
Palabras clave: microclima, redes neuronales, predicci\uf3n de microclima, predicci\uf3n clim\ue1tica.
ABSTRACT
An Artificial Neural Network (RNA) was developed with capacity to make short-term climatic predictions, trained with data at intervals of 15 min for 454 days in a climatological station located in La Hechicera M\ue9rida-Venezuela (1896 masl). For training and validation, were used simulated patterns that contain daily variations of radiance and temperature. Three test functions were chosen such as the Sine, Cosine and the Legendre Polynomials Pl(x). The (RNA) e.g, can predict the interval (0,1] using only as input the interval [-1,0] of the corresponding derivative P\ub4l (x) of the polynomial. In the production phase with real data, it was found that the network is able to predict the temperature with approx. 5% error in the hourly range [12:15 to 06:15] pm, only with the temperature data in the range [6:00 to 12:00) am. Also, when predicting temperature from radiance (5%), radiance-radiance (16%). The use of (RNA) for the prediction of micro-climate in the short term is considered feasible, being able to extend its use to other localities, which could be useful for the development of disaster prevention plans, sowing periods, prediction of energy supply in wind and solar power stations.
Key words: microclimate, neuronal network, microclimate prediction, climatic prediction. <br
Effective drag on spheres immersed in a fluidized bed at minimum fluidization—Influence of bulk solids properties
The aims of this work are to elucidate the effects that bulk solids properties have on the effective drag experienced by large spheres immersed in an emulsion of group-B solids under minimum fluidization conditions and to analyze the ways in which the different suspensions react towards different applied shear rates. To investigate this, magnetic particle tracking was applied to resolve the trajectory of falling-sphere measurements in which the size, density, and sphericity of the bulk solids were varied as well as the size and density of the spherical tracers. The resulting experimental scope included both rising and sinking tracers as well as full segregation and in-bed stagnation of the tracers. The set-up provided highly resolved tracer trajectories, from which the drag experienced by the sphere can be calculated. For sinking tracers, the results showed that an increase in bulk solids size, angularity, and density reduced the terminal velocity of the sphere. This effect correlated well with the bed expansion and Hausner ratio, indicating that a reduced void space among the bulk solids is the main reason for the increase in motion resistance. At lower shear rates, namely, during the de-acceleration towards the stagnant state, beds of larger, more angular, or denser bulk solids yield lower levels of shear stress. The angle of repose of the bulk solids correlated with the rate at which the emulsion thins with increasing shear rate. For rising tracers, shear stress did not show any significant dependency on the properties of the bulk solids
Rheological effects of a gas fluidized bed emulsion on falling and rising spheres
To enable the mechanistic description of the mixing of larger particles in gas-fluidized beds in models (e.g. fuel particles in combustors), knowledge about the rheology of the bed emulsion is required. Here, it is crucial to determine the drag on large fuel-alike particles. This work presents the experimental work on the fate of 13 different solid spheres falling or rising through a bed of air and glass beads at minimum fluidization. The trajectories of the tracer are highly resolved (sampling rate of 200 Hz) by means of magnetic particle tracking, this previously unmet accuracy allows disclosing the complex rheological behavior of gas-solids fluidized bed emulsions in terms of drag on immersed objects. The trajectories reveal that none of the tracers reach terminal velocity during their fall and rise through the bed. The shear stress is obtained through the drag force by solving the equation of motion for the tracer. The data reveal particularities of the bed rheology and clear differences of its effect on rising and falling particles. When studying the shear stress over the characteristic shear rate of each tracer, it can be seen that the stress of the bed on the tracers is dominated by a yield stress, with a somewhat smaller contribution of the shear stress. For rising tracers this last contribution is almost negligible. The falling tracers show strong interaction with the bed emulsion, resulting in a fluctuating shear stress, which increases with tracer size and density. The stagnation of some tracers at low shear rates reveals a viscoplastic behavior of the bed emulsion, exhibiting a typical yield stress that showing a clear dependence on the tracer diameter and buoyant density. The concept of yield gravity is used in order to introduce a normalized shear stress which provides additional verification of the experimental observations in relation to the influence of tracer size and relative density on the shear stress
The Paradigms of Industry 4.0 and Circular Economy as Enabling Drivers for the Competitiveness of Businesses and Territories: The Case of an Italian Ceramic Tiles Manufacturing Company
Sustainable development and the circular economy are two important issues for the future
and the competitiveness of businesses. The programs for the integration of sustainability into
industrial activities include the reconfiguration of production processes with a view to reducing their
impact on the natural system, the development of new eco-sustainable products and the redesign
of the business model. This paradigm shift requires the participation and commitment of different
stakeholder groups and industry can completely redesign supply chains, aiming at resource efficiency
and circularity. Developments in key ICT technologies, such as the Internet of Things (IoT), help
this systemic transition. This paper explores the phases of the transition from a linear to a circular
economy and proposes a procedure for introducing the principles of sustainability (environmental,
economic and social) in a manufacturing environment, through the design of a new Circular Business
Model (CBM). The new procedure has been tested and validated in an Italian company producing
ceramic tiles, using the digitalization of the production processes of the Industry 4.0 environment, to
implement the impact assessment tools (LCA\u2014Life Cycle Assessment, LCC\u2014Life Cycle Costing and
S-LCA\u2014Social Life Cycle Assessment) and the business intelligence systems to provide appropriate
sustainability performance indicators essential for the definition of the new CBM
Techno-Economic Assessment of Calcium Looping for Thermochemical Energy Storage with CO2 Capture
The cyclic carbonation-calcination of CaCO3 in fluidized bed reactors not only offers a possibility for CO2 capture but can at the same time be implemented for thermochemical energy storage (TCES), a feature which will play an important role in a future that has an increasing share of non-dispatchable variable electricity generation (e.g., from wind and solar power). This paper provides a techno-economic assessment of an industrial-scale calcium looping (CaL) process with simultaneous TCES and CO2 capture. The process is assumed to make profit by selling dispatchable electricity and by providing CO2 capture services to a certain nearby emitter (i.e., transport and storage of CO2 are not accounted). Thus, the process is connected to two other facilities located nearby: a renewable non-dispatchable energy source that charges the storage and a plant from which the CO2 in its flue gas flow is captured while discharging the storage and producing dispatchable electricity. The process, which offers the possibility of long-term storage at ambient temperature without any significant energy loss, is herein sized for a given daily energy input under certain boundary conditions, which mandate that the charging section runs steadily for one 12-h period per day and that the discharging section can provide a steady output during 24 h per day. Intercoupled mass and energy balances of the process are computed for the different process elements, followed by the sizing of the main process equipment, after which the economics of the process are computed through cost functions widely used and validated in literature. The economic viability of the process is assessed through the breakeven electricity price (BESP), payback period (PBP), and as cost per ton of CO2 captured. The cost of the renewable energy is excluded from the study, although its potential impact on the process costs if included in the system is assessed. The sensitivities of the computed costs to the main process and economic parameters are also assessed. The results show that for the most realistic economic projections, the BESP ranges from 141 to −20 /tCO2-captured. The cost of investment in the fluidized bed reactors accounts for most of the computed capital expenses, while an increase in the degree of conversion in the carbonator is identified as a technical goal of major importance for reducing the global cost
BALANCING A MECHANIZED HARVESTING SYSTEM USING DISCRETE EVENT SIMULATION
Se analiz\uf3 un sistema de cosecha mecanizado, operando en una faena
a tala rasa de pino radiata y conformado por un feller buncher, un
skidder con garra, un procesador y un trineum\ue1tico. Un Modelo de
Simulaci\uf3n de Eventos Discretos (MSED) fue desarrollado con el
prop\uf3sito de balancear el sistema. El proceso mecanizado de madera
fue el limitante del sistema de acuerdo con los resultados del estudio
de tiempos, entonces este proceso fue apoyado agregando a 3 operadores
de motosierra para alcanzar una producci\uf3n de 60,82
m3/Hora-M\ue1quina (HM) en la configuraci\uf3n propuesta. Simulado
el madereo se determin\uf3 que para balancear la producci\uf3n
obtenida en proceso, el skidder con garra deb\ueda operar a una
distancia promedio de madereo (DPM) de 80 m, realizando una
detenci\uf3n para completar una carga de cuatro fustes. Finalmente,
el feller buncher puede usar hasta 1,6 minutos adicionales para formar
las pilas que permitan lograr la producci\uf3n esperada para el
sistema. De acuerdo con la experimentaci\uf3n de simulaci\uf3n se
por\ueda lograr una producci\uf3n del sistema de 60,39 m3/HM, si
todas las modificaciones propuestas en volteo, apilado, madereo y
proceso son realizadas.A mechanized harvest system was analysed, working in a radiata pine
clear cut operation and compound by a feller buncher, a grapple
skidder, a grapple processor and a three-wheeler. A Discrete \u2013
Event Simulation Model was built with the goal to balance the system.
The mechanized wood processing was the bottleneck according to the time
study results, then this process was supported adding 3 chain saw
felling operators to reach a yield of 60.82 m3/Productive Machine-Hour
(PMH) in the configuration proposal. Also the simulated skidding was
done, operating the grapple skidder at 80 m Average Skidding Distance
(ASD) with one loading stop at a bunch for four stems to balance the
obtained processing yield. Finally, the feller buncher can spend 1.6
extra minutes grouping the modify bunches to accomplish the expected
yield of the system. The simulation experiment gives 60.39 m3/PMH
expected yield of the system if all the proposed modifications in
felling, bunching, skidding and processing are done
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