1,781 research outputs found
HiPhom -: HIgh order Projection-based HOMogenisation for advection diffusion reaction problems
We propose a new model reduction technique for multiscale scalar transport
problems that exhibit dominant axial dynamics. To this aim, we rely on the
separation of variables to combine a Hierarchical Model (HiMod) reduction with
a two-scale asymptotic expansion. We extend the two-scale asymptotic expansion
to an arbitrary order and exploit the high-order correctors to define the HiMod
modal basis, which approximates the transverse dynamics of the flow, while we
adopt a finite element discretisation to model the leading stream. The
resulting method, which is named HiPhom (HIgh-order
Projection-based HOMogEnisation), is successfully assessed both in steady and
unsteady advection-diffusion-reaction settings. The numerical results confirm
the very good performance of HiPhom, which improves the accuracy
and the convergence rate of HiMod and extends the reliability of the standard
homogenised solution to transient and pre-asymptotic regimes
Comparison between Energy Simulation and Monitoring Data in an Office Building
One of the most important steps in the retrofitting process of a building is to understand its pre-retrofitting stage energy performance. The best choice for carrying this out is by means of a calibrated building energy simulation (BES) model. Then, the testing of different retrofitting solutions in the validated model allows for quantifying the improvements that may be obtained, in order to choose the most suitable solution. In this work, based on the available detailed building drawings, constructive details, building operational data and the data sets obtained on a minute basis (for a whole year) from a dedicated energy monitoring system, the calibration of an in-use office building energy model has been carried out. It has been possible to construct a detailed white box model based on Design Builder software. Then, comparing the model output for indoor air temperature, lighting consumption and heating consumption against the monitored data, some of the building envelope parameters and inner building inertia of the model were fine tuned to obtain fits fulfilling the ASHRAE criteria. Problems found during this fitting process and how they are solved are explained in detail. The model calibration is firstly performed on an hourly basis for a typical winter and summer week; then, the whole year results of the simulation are compared against the monitored data. The results show a good agreement for indoor temperature, lighting and heating consumption compared with the ASHRAE criteria for the mean bias error (MBE).This research was supported by the A2PBEER project âAffordable and Adaptable Public Buildings through Energy Efficient Retrofittingâ under grant number 609060 funded by the European Commission for providing resources for the monitoring system.
The APC was funded by the Spanish Ministry of Science, Innovation and Universities and the European Regional Development Fund through the project called âInvestigation of monitoring techniques of occupied buildings for their thermal characterization and methodology to identify their key performance indicatorsâ, project
reference: RTI2018-096296-B-C22 (MCIU/AEI/FEDER, UE)
Comparison between Energy Simulation and Monitoring Data in an Office Building
One of the most important steps in the retrofitting process of a building is to understand its pre-retrofitting stage energy performance. The best choice for carrying this out is by means of a calibrated building energy simulation (BES) model. Then, the testing of different retrofitting solutions in the validated model allows for quantifying the improvements that may be obtained, in order to choose the most suitable solution. In this work, based on the available detailed building drawings, constructive details, building operational data and the data sets obtained on a minute basis (for a whole year) from a dedicated energy monitoring system, the calibration of an in-use office building energy model has been carried out. It has been possible to construct a detailed white box model based on Design Builder software. Then, comparing the model output for indoor air temperature, lighting consumption and heating consumption against the monitored data, some of the building envelope parameters and inner building inertia of the model were fine tuned to obtain fits fulfilling the ASHRAE criteria. Problems found during this fitting process and how they are solved are explained in detail. The model calibration is firstly performed on an hourly basis for a typical winter and summer week; then, the whole year results of the simulation are compared against the monitored data. The results show a good agreement for indoor temperature, lighting and heating consumption compared with the ASHRAE criteria for the mean bias error (MBE).This research was supported by the A2PBEER project âAffordable and Adaptable Public Buildings through Energy Efficient Retrofittingâ under grant number 609060 funded by the European Commission for providing resources for the monitoring system. The APC was funded by the Spanish Ministry of Science, Innovation and Universities and the European Regional Development Fund through the project called âInvestigation of monitoring techniques of occupied buildings for their thermal characterization and methodology to identify their key performance indicatorsâ, project reference: RTI2018-096296-B-C22 (MCIU/AEI/FEDER, UE)
Multi-Scale Modelling of Aggregation of TiO2 Nanoparticle Suspensions in Water
Titanium dioxide nanoparticles have risen concerns about their possible toxicity and the European Food Safety Authority recently banned the use of TiO2 nano-additive in food products. Following the intent of relating nanomaterials atomic structure with their toxicity without having to conduct large-scale experiments on living organisms, we investigate the aggregation of titanium dioxide nanoparticles using a multi-scale technique: starting from ab initio Density Functional Theory to get an accurate determination of the energetics and electronic structure, we switch to classical Molecular Dynamics simulations to calculate the Potential of Mean Force for the connection of two identical nanoparticles in water; the fitting of the latter by a set of mathematical equations is the key for the upscale. Lastly, we perform Brownian Dynamics simulations where each nanoparticle is a spherical bead. This coarsening strategy allows studying the aggregation of a few thousand nanoparticles. Applying this novel procedure, we find three new molecular descriptors, namely, the aggregation free energy and two numerical parameters used to correct the observed deviation from the aggregation kinetics described by the Smoluchowski theory. Ultimately, molecular descriptors can be fed into QSAR models to predict the toxicity of a material knowing its physicochemical properties, enabling safe design strategies
Bioactive compounds from Norway spruce bark: comparison among sustainable extraction techniques for potential food applications
6openInternationalItalian coauthor/editorPicea abies (L.) Karst, (Norway spruce) bark, generally considered as wood industry waste, could potentially be used as a valuable source of antioxidants for food applications. In this study, supercritical fluid extraction (SFE), pressurized liquid extraction (PLE), and ultrasound-assisted extraction (UAE) were carried out in order to recover bioactive compounds from bark of Norway spruce. Obtained results show that PLE with ethanol as solvent was the most effective method for extracting total flavonoid compounds (21.14 ± 1.42 mg quercetin gâ1 sample) and consequently exerted the highest antioxidant activity measured by 2,2âČ-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (257.11 ± 13.31 mg Trolox gâ1 sample). On the other hand, UAE extract contained the maximum phenolic concentration (54.97 ± 2.00 mg gallic acid gâ1 sample) and the most interesting antioxidant activity measured by the ferric-reducing antioxidant power (580.25 ± 25.18 ”mol FeSO4 gâ1 sample). Additionally, PLE and UAE have demonstrated great efficiency in the extraction of trans-resveratrol, quantified by HPLC (0.19 and 0.29 mg trans-RSV gâ1 sample, respectively)openSpinelli, Sara; Costa, Cristina; Conte, Amalia; La Porta, Nicola; Padalino, Lucia; Del Nobile, Matteo AlessandroSpinelli, S.; Costa, C.; Conte, A.; La Porta, N.; Padalino, L.; Del Nobile, M.A
Emergence of non-Fickian transport in truncated pluri-Gaussian permeability fields
We present a numerical simulation study of advectiveâdiffusive scalar transport in three-dimensional high-contrast discontinuous permeability fields, generated with a truncated pluri-Gaussian geostatistical approach. The numerical experiments are run with an Eulerian approach using a novel unified numerical framework based on the finite-volume library OpenFOAMÂź(Weller et al. in Comput Phys 12(6):620â631, 1998), for (1) generating random pluri-Gaussian porous media, (2) solving the steady state Darcy-scale flow, (3) solving the advection diffusion equation, (4) computing post-processing quantities such as first order statistics, spatial probability density functions and breakthrough curves. A range of permeability contrasts, correlation lengths, and PĂ©clet numbers are tested to assess their relative weight on transport control and for the first time, the deviation of a calibrated macrodispersive model from the Fickian transport is quantified. We identify a hierarchy of non-Fickian transport triggering factors. From the tested scenarios, permeability contrast is the main controlling parameter for the anomalous transport behaviour as it enhances the generation of preferential flow paths which are characterised by high advective flow velocities. The PĂ©clet number and the characteristic length at which facies transitions are observed as secondary factors
Dietary Neurotransmitters: A Narrative Review on Current Knowledge
Foods are natural sources of substances that may exert crucial effects on the nervous system in humans. Some of these substances are the neurotransmitters (NTs) acetylcholine (ACh), the modified amino acids glutamate and Îł-aminobutyric acid (GABA), and the biogenic amines dopamine, serotonin (5-HT), and histamine. In neuropsychiatry, progressive integration of dietary approaches in clinical routine made it necessary to discern the more about some of these dietary NTs. Relevant books and literature from PubMed and Scopus databases were searched for data on food sources of Ach, glutamate, GABA, dopamine, 5-HT, and histamine. Different animal foods, fruits, edible plants, roots, and botanicals were reported to contain NTs. These substances can either be naturally present, as part of essential metabolic processes and ecological interactions, or derive from controlled/uncontrolled food technology processes. Ripening time, methods of preservation and cooking, and microbial activity further contributes to NTs. Moreover, gut microbiota are considerable sources of NTs. However, the significance of dietary NTs intake needs to be further investigated as there are no significant data on their bioavailability, neuronal/non neuronal effects, or clinical implications. Evidence-based interventions studies should be encouraged
Optimized quantum nondemolition measurement of a field quadrature
We suggest an interferometric scheme assisted by squeezing and linear
feedback to realize the whole class of field-quadrature quantum nondemolition
measurements, from Von Neumann projective measurement to fully non-destructive
non-informative one. In our setup, the signal under investigation is mixed with
a squeezed probe in an interferometer and, at the output, one of the two modes
is revealed through homodyne detection. The second beam is then
amplitude-modulated according to the outcome of the measurement, and finally
squeezed according to the transmittivity of the interferometer. Using strongly
squeezed or anti-squeezed probes respectively, one achieves either a projective
measurement, i.e. homodyne statistics arbitrarily close to the intrinsic
quadrature distribution of the signal, and conditional outputs approaching the
corresponding eigenstates, or fully non-destructive one, characterized by an
almost uniform homodyne statistics, and by an output state arbitrarily close to
the input signal. By varying the squeezing between these two extremes, or
simply by tuning the internal phase-shift of the interferometer, the whole set
of intermediate cases can also be obtained. In particular, an optimal quantum
nondemolition measurement of quadrature can be achieved, which minimizes the
information gain versus state disturbance trade-off
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