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AbstractWe study the use of deep learning techniques to reconstruct the kinematics of the neutral current deep inelastic scattering (DIS) process in electron–proton collisions. In particular, we use simulated data from the ZEUS experiment at the HERA accelerator facility, and train deep neural networks to reconstruct the kinematic variables $$Q^2$$ Q 2 and x. Our approach is based on the information used in the classical construction methods, the measurements of the scattered lepton, and the hadronic final state in the detector, but is enhanced through correlations and patterns revealed with the simulated data sets. We show that, with the appropriate selection of a training set, the neural networks sufficiently surpass all classical reconstruction methods on most of the kinematic range considered. Rapid access to large samples of simulated data and the ability of neural networks to effectively extract information from large data sets, both suggest that deep learning techniques to reconstruct DIS kinematics can serve as a rigorous method to combine and outperform the classical reconstruction methods.

Abstract For understanding and improving the performance of industrial Si solar cells, it helps to quantify the losses in the various device parts very precisely, because this enhances the predictive power of roadmaps deduced from such analysis. We show how the precision of commonly applied methods for measuring the saturation current density, J0, can be noticeably improved. Firstly, two methods are compared for determining the optical properties of the samples specifically made for lifetime measurements. Secondly, it is evaluated, which excess carrier density level is best to choose for extracting J0 of the various device regions. Thirdly, the bulk lifetime is extracted by a combination of measurements and modeling of the surface passivation.

Abstract Ventilation systems are of vital importance for buildings, not only to provide acceptable thermal conditions and air quality for occupants, but also with regards to energy usage. Impinging jets can be encountered in many ventilation strategies which have major impacts on the acoustic environment and energy performance. The self-sustaining tones can be generated in such applications where a feedback loop is installed in the system. This phenomenon is explained by the corollary of Howe who shows that the origin of noise in such configurations can be attributed to fluid rotations. Howe highlights the role of phase conditions between the vorticity, the velocity of the flow and the acoustic velocity for the optimization of energy transfers between the turbulent kinetic energy and the sound field. In this work, we use 2D-PIV technique and a microphone respectively to measure the kinematic fields simultaneously with the acoustic generation for a rectangular jet impinging on a slotted plate. This study aims to investigate the transfers between the turbulent kinetic energy and the sound field for two Reynolds numbers presenting a high and a low noise levels. It is shown that phase conditions are necessary for the optimization of energy transfer which allows the installation of the self-sustained loop in the flow. It was found also that the change of the aerodynamic mode which is directly related to the self-sustained frequency amplifies the sound intensity and promotes the transfer of energy to the acoustic field.

In this paper, we study the nonlinear Klein-Gordon equation coupled with a Maxwell equation. Using the energy method, we obtain a local existence result for the Cauchy problem.

Fresnel lenses are widely used in concentrating photovoltaic (CPV) systems as primary optical elements focusing sunlight onto small solar cells or onto entrance apertures of secondary optical elements attached to the solar cells. Calculations using the Young-Maggi-Rubinowicz theory of diffraction yield analytical expressions for the amount of light spilling outside these target areas due to diffraction at the edges of the concentrator Fresnel lenses. Explicit equations are given for the diffraction loss due to planar Fresnel lenses with small prisms and due to arbitrarily shaped Fresnel lenses. Furthermore, the cases of illumination by monochromatic, polychromatic, totally spatially coherent and partially spatially coherent light (e.g. from the solar disc) are treated, resulting in analytical formulae. Examples using realistic values show losses due to diffraction of up to several percent.

Coarse-grained silicon films for crystalline silicon thin-film solar cells have been prepared by zone melting recrystallization. A zone melting heater was modified to obtain better temperature homogeneity of the sample and higher reproducibility of the melt process. Various substrate materials of different purity and surface roughness have been tested concerning their suitability for, silicon deposition, zone melting and solar cell process. Solar cell efficiencies up to 10.5% could be achieved on silicon sheets from powder, capped by an intermediate layer. Silicon films on SiAlON ceramics were successfully processed to solar cells by a completely dry solar cell process.

Lattice Boltzmann simulations were carried out to investigate the noise mitigation mechanisms of a 3-D printed porous trailing-edge insert, elucidating the link between noise reduction and material permeability. The porous insert is based on a unit cell resembling a lattice of diamond atoms. It replaces the last 20 % chord of a NACA 0018 at zero angle-of-attack. A partially blocked insert is considered by adding a solid partition between 84 % and 96 % of the aerofoil chord. The regular porous insert achieves a substantial noise reduction at low frequencies, although a slight noise increase is found at high frequencies. The partially blocked porous insert exhibits a lower noise reduction level, but the noise emission at mid-to-high frequency is slightly affected. The segment of the porous insert near the tip plays a dominant role in promoting noise mitigation, whereas the solid-porous junction contributes, in addition to the rough surface, towards the high-frequency excess noise. The current study demonstrates the existence of an entrance length associated with the porous material geometry, which is linked to the pressure release process that is responsible for promoting noise mitigation. This process is characterised by the aerodynamic interaction between pressure fluctuations across the porous medium, which is found at locations where the porous insert thickness is less than twice the entrance length. Present results also suggest that the noise attenuation level is related to both the chordwise extent of the porous insert and the streamwise turbulent length scale. The porous inserts also cause a slight drag increase compared to their solid counterpart.