The Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS) will scan thousands of square degrees of the northern sky with a unique set of 56 filters using the dedicated 2.55 m ...Javalambre Survey Telescope (JST) at the Javalambre Astrophysical Observatory. Prior to the installation of the main camera (4.2 deg 2 field-of-view with 1.2 Gpixels), the JST was equipped with the JPAS-Pathfinder, a one CCD camera with a 0.3 deg 2 field-of-view and plate scale of 0.23 arcsec pixel −1 . To demonstrate the scientific potential of J-PAS, the JPAS-Pathfinder camera was used to perform miniJPAS, a ∼1 deg 2 survey of the AEGIS field (along the Extended Groth Strip). The field was observed with the 56 J-PAS filters, which include 54 narrow band ( FWHM ∼ 145 Å) and two broader filters extending to the UV and the near-infrared, complemented by the u , g , r , i SDSS broad band filters. In this miniJPAS survey overview paper, we present the miniJPAS data set (images and catalogs), as we highlight key aspects and applications of these unique spectro-photometric data and describe how to access the public data products. The data parameters reach depths of mag AB ≃ 22−23.5 in the 54 narrow band filters and up to 24 in the broader filters (5 σ in a 3″ aperture). The miniJPAS primary catalog contains more than 64 000 sources detected in the r band and with matched photometry in all other bands. This catalog is 99% complete at r = 23.6 ( r = 22.7) mag for point-like (extended) sources. We show that our photometric redshifts have an accuracy better than 1% for all sources up to r = 22.5, and a precision of ≤0.3% for a subset consisting of about half of the sample. On this basis, we outline several scientific applications of our data, including the study of spatially-resolved stellar populations of nearby galaxies, the analysis of the large scale structure up to z ∼ 0.9, and the detection of large numbers of clusters and groups. Sub-percent redshift precision can also be reached for quasars, allowing for the study of the large-scale structure to be pushed to z > 2. The miniJPAS survey demonstrates the capability of the J-PAS filter system to accurately characterize a broad variety of sources and paves the way for the upcoming arrival of J-PAS, which will multiply this data by three orders of magnitude.
•The performance of a triple concentric-tube heat exchanger has been conducted.•ANN model was validated using a huge databank including 181 experimental datasets.•Nine different corrugation types ...were used in the inner tube of the heat exchanger.•A highly viscous fluid, typical of food industry, was used as heat transfer fluid.•The mean relative error between experimental and ANN results was lower than 4%.
This work presents a model of Artificial Neural Networks (ANNs) capable of accurately predicting the heat transfer rate and pressure drop in a triple concentric-tube heat exchanger (TTHX) with corrugated and non-corrugated inner tubes and involving a fluid typically used in the food industry. Pitch and depth are varied in the case of corrugated tubes. The ANN model was developed and validated using a huge databank including 181 experimental datasets. The best training algorithm is the Bayesian regulation. A back-propagation algorithm, which is considered to be the most common learning method for ANNs, is used in the training and testing of the network. Different network configurations were tested, and the optimum ANN configuration consisted of a network with two hidden layers with 15 and 21 nodes in the first and second layer, respectively. The ANNs results were found to be in good agreement with the experimental data, with the absolute average relative deviation (AARD) being below 1.91% for the heat transfer coefficient and below 3.82% for the pressure drop, respectively. The simplicity of the developed ANN model and its low levels of error for a huge experimental databank are some of the key features of the model.
•The performance of a double tube heat exchanger with inserted TTEs was characterized.•Novel Nu and f correlations were developed using 320 experimental datasets.•Nine different TTE-spacer ...configurations were experimentally tested.•A highly viscous fluid, typical of the food industry, was used as the heat transfer fluid.
The aim of this paper was to study the influence on thermo-hydraulic performance of different configurations of regularly spaced twisted tape elements (TTEs) inserted into a smooth double tube heat exchanger (DTHX). In order to emulate the behavior of high-viscosity food-industry fluids, a 60° brix solution of water and sugar was used as the Heat Transfer Fluid (HTF). A total of 320 experimental tests were carried out, varying the flow velocity (Reynolds number) and the TTE configuration. We report the results from nine different configurations, including different twisted tape element pitches and free-space lengths. Finally, the results from each case were correlated for Nusselt number and friction factor using the minimum variance methodology. The agreement between the results obtained from the experimental data and those obtained from the proposed correlations is reasonable, with an absolute average relative derivation of less than 9.5% for the heat transfer rate and 15% for the friction factor.
•Consciousness is linked to the complexity of distributed interactions within the human brain.•Complexity of structural and functional patterns is detectable with fractal dimension (FD).•A Fractal ...Dimension Index (FDI) is computed combining integration FD and differentiation FD.•FDI is significantly lower in sleep and sedation when compared to wakefulness.•FDI provides an almost perfect intra-subject discrimination between conscious and unconscious states.
Knowing whether a subject is conscious or not is a current challenge with a deep potential clinical impact. Recent theoretical considerations suggest that consciousness is linked to the complexity of distributed interactions within the corticothalamic system. The fractal dimension (FD) is a quantitative parameter that has been extensively used to analyse the complexity of structural and functional patterns of the human brain. In this study we investigate FD to assess whether it can discriminate between consciousness and different states of unconsciousness in healthy individuals.
We study 69 high-density electroencephalogram (hd-EEG) measurements after transcranial magnetic stimulation (TMS) in 18 healthy subjects progressing from wakefulness to non-rapid eye movement (NREM) sleep and sedation induced by different anaesthetic agents (xenon and propofol). We quantify the integration of thalamocortical networks by calculating the FD of a spatiotemporal voxelization obtained from the locations of all sources that are significantly activated by the perturbation (4DFD). Moreover, we study the temporal evolution of the evoked spatial distributions and compute a measure of the differentiation of the response by means of the Higuchi FD (HFD). Finally, a Fractal Dimension Index (FDI) of perturbational complexity is computed as the product of both quantities: integration FD (4DFD) and differentiation FD (HFD).
We found that FDI is significantly lower in sleep and sedation when compared to wakefulness and provides an almost perfect intra-subject discrimination between conscious and unconscious states.
These results support the combination of FD measures of cortical integration and cortical differentiation as a novel paradigm of tracking complex spatiotemporal dynamics in the brain that could provide further insights into the link between complexity and the brain's capacity to sustain consciousness.
In this study, 3-D numerical simulations were carried out to analyse the influence of geometrical parameters for eight spirally inner corrugated tubes at turbulent flow (Re=25×103) in a double pipe ...heat exchanger. As a novelty, different combinations of pitch and height in a 3-D inward corrugated tube numerical model were analysed and validated with an experimental setup. This had not previously been conducted in a double pipe heat exchanger. Furthermore, the numerical model included the entire geometry of the heat exchanger, with dimensions of the computational domain similar to those used in actual commercial applications. Grid independence analysis of the numerical solution was performed based on a 3-D unstructured tetrahedral mesh scheme, considering the Realizable k−ε turbulence model. Case 8, with the highest corrugation height (H/D=0.05) and the lowest helical pitch (P/D=0.682) presented the highest pressure drops in both inner and annular tubes, being 4.15 and 1.27 times higher in the inner tube and in the annulus side than in the smooth tube, respectively. Regarding heat transfer, Case 9, with the smallest helical pitch and an intermediate corrugation height (H/D=0.041) obtained the highest number of transfer units (NTU) value, which, under the experimental conditions of this work, resulted in an increase of 29% compared with the smooth tube. In Cases 7 and 9, the inner tubes showed optimal results when considering the combined influence of the enhanced heat transfer performance and pressure drop using the performance evaluation criteria (PEC).
•Numerical simulation of double pipe heat exchanger with eight inner corrugated tubes.•High computational cost model including the entire geometry of the heat exchanger.•Good agreement obtained between numerical and experimental results.•The corrugation increases the efficiency of the heat exchanger up to 23%.
•Bubbling fluidized and spouted beds with concentrated solar energy are compared.•Two simple numerical models to analyze the behavior of both technologies are shown.•Both technologies are suitable ...for CSP plants employing solid particles.•Spouted bed permits to extend the range of particles sizes to be used.•This work studies features like energy distribution, temperature, velocity influence.
This paper presents two simple numerical models to analyze the behavior of two different fluidization technologies with concentrated solar energy on the top of the bed. A bubbling fluidized bed, which operates with low particle size (Geldart A-B particles with dp=0.1-0.5 mm) and a spouted bed, which uses particles with larger sizes (Geldart D with dp≳1 mm). Two cases were studied with the same mass of particles (150 kg), considering the same incident solar radiation concentrated on the top of the bed (50 kW).
The results obtained indicate that the airflow rate in the bubbling fluidized bed has a notable effect on the maximum temperature reached in the bed. Increasing the airflow rate (from 1.5 to 2.5 times the minimum fluidization velocity), the maximum temperature reached in the bed is reduced from 950 to 750 K. In the spouted bed, higher temperatures are reached (over 1000 K), although it takes almost 4 times longer for the temperature to be reached than in the bubbling bed. Consequently, the charging efficiency, defined as the energy stored in the particles divided by the solar energy concentrated on the bed, are similar for both cases.
Phase Change Materials (PCMs) have been receiving increased attention, due to their capacity to store large amounts of thermal energy in narrow temperature ranges. This property makes them ideal for ...passive heat storage in the envelopes of buildings. To study the influence of PCMs in external building walls, a one-dimensional transient heat transfer model has been developed and solved numerically using a finite difference technique. Different external building wall configurations were analyzed for a typical building wall by varying the location of the PCM layer, the orientation of the wall, the ambient conditions and the phase transition temperature of the PCM.
The integration of a PCM layer into a building wall diminished the amplitude of the instantaneous heat flux through the wall when the melting temperature of the PCM was properly selected according to the season and wall orientation. Conversely, the results of the work show that there is no significant reduction in the total heat lost during winter regardless of the wall orientation or PCM transition temperature. Higher differences were observed in the heat gained during the summer period, due to the elevated solar radiation fluxes. The high thermal inertia of the wall implies that the inclusion of a PCM layer increases the thermal load during the day while decreasing the thermal load during the night.
► A comparative simulation of a building wall with and without PCMs has been conducted. ► PCM is selected according with the season, the wall orientation and the melting temperature. ► PCM in a building wall help to diminish the internal air temperature swings and to regulate the heat transfer.
Although there is an extensive literature on the study of the neural correlates of consciousness (NCC) this is a subject that is far from being considered over. In this paper we present a novel ...experimental paradigm, based on binocular rivalry, to study internally and externally generated conscious experiences. We called this procedure bimodal rivalry. In addition, and assuming the non-linear nature of the EEG signals, we propose the use of fractal dimension to characterize the complexity of the EEG signal associated with each percept. Analysis of the data showed a significant difference in complexity between the internally generated and externally generated percepts. Moreover, EEG complexity was dissimilar for externally generated auditory and visual percepts. These results support fractal dimension analyses as a new tool to characterize conscious perception.
Patients with schizophrenia have often been considered to be "in their own world". However, this casual observation has not been proven by scientific evidence so far. This can be explained because ...scientific research has usually addressed cognition related to the processing of external stimuli, but only recently have efforts been made to explain thoughts, images and feelings not directly related to the external environment. This internally directed cognition has been called mind wandering. In this paper, we have explored mind wandering in schizophrenia under the hypothesis that a predominance of mind wandering would be a core dysfunction in this disorder. To this end, we collected verbal reports and measured electrophysiological signals from patients with schizophrenia spectrum disorders and matched healthy controls while they were presented with segments of films. The results showed that mind wandering was more frequent in patients than in controls. This higher frequency of mind wandering did not correlate with deficits in attentional, memory or executive functioning. In addition, mind wandering in patients was characterized by a different pattern of Electroencephalography (EEG) complexity in patients than in controls, leading to the suggestion that mind wandering in schizophrenia could be of a different nature. These findings could have relevant implications for the conceptualization of this severe mental disorder.
This work presents the economic modeling and analysis of a thermoelectric steam power plant (SPP) cooled with an air-cooled heat exchanger (ACHX) and using an absorption refrigeration system (ARS) as ...an intermediary, as discussed in Salgado et al., 2017. This novel configuration has the advantage of not consuming fresh water in the cooling system, which is of special interest in locations where water is scarce or expensive. Based on the thermodynamic analysis of this SPP configuration (considering three different power ranges: 5 MW, 50 MW, and 200 MW, and different ambient temperatures from 5°C to 40°C), economic and sensitivity analyses were conducted to determine the cost-effectiveness and profitability of the power plant. Finally, a comparative analysis was conducted to test the economic outcomes of the SPPs using the proposed ARS compared with conventional refrigeration devices based on water cooling and dry cooling technologies. The results show that conventional evaporative cooling towers are the best solution from an economic perspective. Nevertheless, in regions where water is not easily accessible, the proposed ARS achieves better economic outcomes than the conventional ACHX when the ambient temperature is beyond the range of 17.5°C–22.5°C, depending on the power rating of the plant.
•Economic and profitability assessment of ARS as heat rejection in power cycles.•ARS solution as appropriate alternative for warm and water-scarce locations.•Comparative analysis with conventional refrigeration devices.•Sensitivity analysis of the key parameters affecting the economic performance.•Parametric analysis for optimal electricity spot price and water-fuel costs.
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