1,600 research outputs found
Experimental characterization and multi-physics simulation of a triple-junction cell in a novel hybrid III:V concentrator photovoltaic–thermoelectric receiver design with secondary optical element
A lattice-matched monolithic triple-junction Concentrator Photovoltaic cell (InGa(0.495)P/GaIn(0.012)As/Ge) was electrically and thermally interfaced to a Thermoelectric Peltier module. A single optical design secondary lens was bonded to the CPV-TE receiver. The hybrid SILO-CPV-TE solar energy harvesting device was electrically, thermally and theoretically investigated. The electrical performance data for the cell under variable irradiance and cell temperature conditions were measured using the integrated thermoelectric module as both a temperature sensor and as a solid-state heat pump. The cell was electrically characterised under standard test conditions (1000 W/m2 irradiance, 25°C temperature and AM1.5G spectrum) for comparison with literature data. Transient multiphysics simulations in ANSYS CFX 15.0 were carried out to calculate cell temperatures and to determine the short circuit current and temperature coefficient in a scaling law. The optimization was used to determine 15 model parameters for the component sub-cells within the triple-junction cell at STC with a MATLAB scaling law. The root-mean-square error in electrical currents between measurement and simulations was 0.66%
Influence of the sodium/proton replacement on the structural, morphological and photocatalytic properties of titanate nanotubes
Titanate nanotubes (TNT) with different sodium contents have been synthesised
using a hydrothermal approach and a swift and highly controllable post-washing
processes. The influence of the sodium/proton replacement on the structural and
morphological characteristics of the prepared materials was analysed. Different
optical behaviour was observed depending on the Na+/H+ samples' content. A band
gap energy of 3.27\pm0.03 eV was estimated for the material with higher sodium
content while a value of 2.81\pm0.02 eV was inferred for the most protonated
material, which therefore exhibits an absorption edge in the near visible
region. The point of zero charge of the materials was determined and the
influence of the sodium content on the adsorption of both cationic and anionic
organic dyes was studied. The photocatalytic performance of the TNT samples was
evaluated in the rhodamine 6G degradation process. Best photodegradation
results were obtained when using the most protonated material as catalyst,
although this material has shown the lowest R6G adsorption capability.Comment: 22 pages, 8 figures, accepted for publication in Journal of
Photochemistry and Photobiology A: Chemistr
Graviton plus vector boson production to NLO in QCD at the LHC
We present the next-to-leading order QCD corrections to the associated
production of the vector gauge boson () and the graviton in the large
extra dimension model at the LHC. We estimate the impact of the QCD corrections
on the total cross sections as well as the differential distributions of the
gauge bosons and find that they are significant. We also study the dependence
of the cross sections on the arbitrary factorization scale and show the
reduction in the scale uncertainties at NLO level. Further, we discuss the
ultraviolet sensitivity of the theoretical predictions.Comment: 51 pages and 27 figure
Large eddy simulation of a turbulent non-premixed propane-air reacting flame in a cylindrical combustor
Large Eddy Simulation (LES) is applied to investigate the turbulent non-premixed combustion flow, including species concentrations and temperature, in a cylindrical combustor. Gaseous propane (C3H8) is injected through a circular nozzle which is attached at the centre of the combustor inlet. Preheated air with a temperature of 773 K is supplied through the annulus surrounding of this fuel nozzle. In LES a spatial filtering is applied to the governing equations to separate the flow field into large-scale and small-scale eddies. The large-scale eddies which carry most of the turbulent energy are resolved explicitly, while the unresolved small-scale eddies are modelled using the Smagorinsky model with Cs = 0.1 as well as dynamically calibrated Cs. The filtered values of the species mass fraction, temperature and density, which are the functions of the mixture fraction (conserved scalar), are determined by integration over a beta probability density function (β-PDF). The computational results are compared with those of the experimental investigation conducted by Nishida and Mukohara. According to this experiment, the overall equivalence ratio of 0.6, which is calculated from the ratio of the air flow rate supplied to the combustion chamber to that of the stoichiometric reaction, is kept constant so that the turbulent combustion at the fuel nozzle exit starts under the fuel-rich conditions
Accelerating cycle expansions by dynamical conjugacy
Periodic orbit theory provides two important functions---the dynamical zeta
function and the spectral determinant for the calculation of dynamical averages
in a nonlinear system. Their cycle expansions converge rapidly when the system
is uniformly hyperbolic but greatly slowed down in the presence of
non-hyperbolicity. We find that the slow convergence can be associated with
singularities in the natural measure. A properly designed coordinate
transformation may remove these singularities and results in a dynamically
conjugate system where fast convergence is restored. The technique is
successfully demonstrated on several examples of one-dimensional maps and some
remaining challenges are discussed
Theoretical investigations of a highly mismatched interface: the case of SiC/Si(001)
Using first principles, classical potentials, and elasticity theory, we
investigated the structure of a semiconductor/semiconductor interface with a
high lattice mismatch, SiC/Si(001). Among several tested possible
configurations, a heterostructure with (i) a misfit dislocation network pinned
at the interface and (ii) reconstructed dislocation cores with a carbon
substoichiometry is found to be the most stable one. The importance of the slab
approximation in first-principles calculations is discussed and estimated by
combining classical potential techniques and elasticity theory. For the most
stable configuration, an estimate of the interface energy is given. Finally,
the electronic structure is investigated and discussed in relation with the
dislocation array structure. Interface states, localized in the heterostructure
gap and located on dislocation cores, are identified
Purely-long-range bound states of HeHe
We predict the presence and positions of purely-long-range bound states of
HeHe near the atomic
limits. The results of the full multichannel and approximate models are
compared, and we assess the sensitivity of the bound states to atomic
parameters characterizing the potentials. Photoassociation to these
purely-long-range molecular bound states may improve the knowledge of the
scattering length associated with the collisions of two ultracold
spin-polarized He atoms, which is important for studies of
Bose-Einstein condensates.Comment: 16 pages, 5 figure
A Pontine Region is a Neural Correlate of the Human Affective Processing Network
The in vivo neural activity of the pons during the perception of affective stimuli has not been studied despite the strong implications of its role in affective processing. To examine the activity of the pons during the viewing of affective stimuli, and to verify its functional and structural connectivity with other affective neural correlates, a multimodal magnetic resonance imaging methodology was employed in this study. We observed the in vivo activity of the pons when viewing affective stimuli. Furthermore, small-world connectivity indicated that the functional connectivity (FC) between the pons and the cortico-limbic affective regions was meaningful, with the coefficient λ being positively associated with self-reported emotional reactivity. The FC between the pons and the cortico-limbic-striatal areas was related to self-reported negative affect. Corroborating this finding was the observation that the tract passing through the pons and the left hippocampus was negatively related to self-reported positive affect and positively correlated with emotional reactivity. Our findings support the framework that the pons works conjunctively with the distributed cortico-limbic-striatal systems in shaping individuals' affective states and reactivity. Our work paves the path for future research on the contribution of the pons to the precipitation and maintenance of affective disorders.published_or_final_versio
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