cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Open data hackathon as a tool for increased engagement of Generation Z: to hack or not to hack?
Creators: name: Nikiforova, Anastasija
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computers and Society (cs.CY)
subject: Social and Information Networks (cs.SI)
subject: FOS: Computer and information sciences

description: A hackathon is known as a form of civic innovation in which participants representing citizens can point out existing problems or social needs and propose a solution. Given the high social, technical, and economic potential of open government data, the concept of open data hackathons is becoming popular around the world. This concept has become popular in Latvia with the annual hackathons organized for a specific cluster of citizens called Generation Z. Contrary to the general opinion, the organizer suggests that the main goal of open data hackathons to raise an awareness of OGD has been achieved, and there has been a debate about the need to continue them. This study presents the latest findings on the role of open data hackathons and the benefits that they can bring to both the society, participants, and government.
Advanced Concepts for Improved Light Management in Solar Cells and Modules
Creators: name: Backes, A.
name: Adamovic, N.
name: Meinhardt, G.
name: Schmid, U.
Publisher: name: WIP
Year: 2011
Subjects: Components for PV Systems
PV Modules

description: 26th European Photovoltaic Solar Energy Conference and Exhibition; 3340-3344
description: An enhanced performance of Photovoltaic Modules can be achieved by increasing the cell efficiency or by
lowering the losses on module level. Basically, output power is lost when part of the incident light does not reach the
solar cell. Optical elements inside the module shall redirect that light which otherwise would fall on the gap areas
between cells or onto the metallization grid, respectively. To reduce these losses to a minimum, different designs of
optical elements preferentially realized with hot embossing technique are investigated systematically by means of
simulations. Furthermore, typically solar modules do not trace the sun movement. As the performance of optical elements
is strongly related to the angle under which light incidents on the surface, the simulation model comprises several light
sources, mimicking the daily movement of the sun. Under these conditions two micromachined, optical structures are
evaluated with respect to fabrication tolerances occurring during hot embossing, such as lateral misalignment, tilting,
shrinkage and edge rounding. Finally, a new concept to realize an advanced optics featuring a gradient in refractive index
in the packaging material is presented.
Selective Doping Method for Crystalline Silicon Solar Cells with Continuous Wave Laser and Light Absorption Layer
Creators: name: Kim, K.H.
name: Lee, S.J.
name: Ku, Y.M.
name: Jang, J.
name: Cho, Y.H.
Publisher: name: WIP-Munich
Year: 2010
Subjects: Wafer-Based Silicon Solar Cells and Materials Technology
Mono- and Multicrystalline Silicon Materials and Cells

description: 25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain; 1955-1957
description: Laser doping with absorption layer has been investigated for photovoltaic applications. For
fabrication of selectively doped regions, we adopted an absorption layer on top of phosphosilicate glass layer
which was produced together with furnace diffusion. The laser beam is changed into thermal energy at the
absorption layer and heats the surface of c-Si. During the laser irradiation, the phosphosilicate glass layer serves
as dopant source. By this method, without complete melting the surface of c-Si, the sheet resistances of 48 or 52
Ω/ were obtained at the laser power of 45 W and laser scan speed of 150 - 190 mm/s. Although absorption layer
formation resulted in narrow process window, our result shows a potential for photovoltaic applications
There might be giants: unseen Jupiter-mass planets as sculptors of tightly-packed planetary systems
Creators: name: Hands, T. O.
name: Alexander, R. D.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The limited completeness of the Kepler sample for planets with orbital periods $\gtrsim$ 1 yr leaves open the possibility that exoplanetary systems may host undetected giant planets. Should such planets exist, their dynamical interactions with the inner planets may prove vital in sculpting the final orbital configurations of these systems. Using an $N$-body code with additional forces to emulate the effects of a protoplanetary disc, we perform simulations of the assembly of compact systems of super-Earth-mass planets with unseen giant companions. The simulated systems are analogous to Kepler-11 or Kepler-32 in that they contain 4 or 5 inner super-Earths, but our systems also contain longer-period giant companions which are unlikely to have been detected by Kepler. We find that giant companions tend to break widely-spaced, first-order mean-motion resonances, allowing the inner planets to migrate into tighter resonances. This leads to more compact architectures and increases the occurrence rate of Laplace resonant chains.
description: 7 pages, 3 figures, 3 tables, accepted for publication in MNRAS
Clustering and flocking of repulsive chiral active particles with non-reciprocal couplings
Creators: name: Kreienkamp, Kim L.
name: Klapp, Sabine H. L.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Recently, non-reciprocal systems have become a focus of growing interest. Examples occur in soft and active matter, but also in engineered quantum materials and neural (brain) networks. Here, we investigate the impact of non-reciprocity on the collective behavior of a system of (dry) chiral active matter. Specifically, we consider a mixture of "circle swimmers" with steric interactions and non-reciprocal alignment couplings. Based on hydrodynamic equations which we derive from a set of Langevin equations, we explore the interplay of non-reciprocity, finite size, and chirality. We first consider, as a reference, one-species systems with reciprocal couplings. Based on a linear stability analysis and numerical simulations, we here observe three different types of collective behavior, that is, flocking, motility-induced phase separation, and a combination of both. Turning then to a non-reciprocal system, we find that non-reciprocity can turn otherwise stationary instabilities into oscillatory ones, affect the relative orientation of flocks, and, crucially, change the general type of instability. This illustrates the drastic impact of non-reciprocity and chirality on the emergent collective dynamics of active matter systems, with potentially far-reaching biological implications.
Influence of Spectral Irradiance Distribution and Module Temperature on the Outdoor Performance of Some Thin Film PV Module Technologies
Creators: name: Nofuentes Garrido, G.
name: Alonso-Abella, M.
name: Muñoz, J.V.
name: García-Domingo, B.
name: Fuentes, M.
name: De La Casa Higueras, J.
name: Chenlo, F.
Publisher: name: WIP
Year: 2011
Subjects: Components for PV Systems
PV Modules

description: 26th European Photovoltaic Solar Energy Conference and Exhibition; 3351-3354
description: The outdoor performance of thin film PV modules is more difficult to predict than crystalline silicon
ones owing to the higher sensitivity to the spectral distribution of the former when compared with the latter, among
some other factors. This paper shows the early results –from April to August 2011- of a 24-month experimental
campaign that is still taking place at present in the city of Jaén (Spain) in which the outdoor electrical behaviour of
four modules of different thin film technologies (a-Si, CIS, CdTe and a-Si/μc-Si) is being assessed. For each one of
the tested modules, contour graphs of their performance ratio (PR) as a function of module temperature and average
photon energy (APE) are shown. A strong dependence of PR on APE is noticeable at module temperatures below
some 45º C so that as a general trend, the module performance improves as APE increases. However, PR seems to
show little sensitivity to this parameter at module temperatures above this threshold. This could lead to consider the
impact of APE on thin film module performance as a second-order effect in sunny and hot climates. However, the
limited amount of data available suggests using these results cautiously: more conclusive results are to be obtained
when the entire experimental campaign is completed.
Unifying Dynamical and Structural Stability of Equilibriums
Creators: name: Arnoldi, Jean-François
name: Haegeman, Bart
Publisher: name: arXiv
Year: 2016
Subjects: subject: Dynamical Systems (math.DS)
subject: Mathematical Physics (math-ph)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: FOS: Biological sciences
subject: 93D20, 92B05

description: We exhibit a fundamental relationship between measures of dynamical and structural stability of equilibriums, arising from real dynamical systems. We show that dynamical stability, quantified via systems local response to external perturbations, coincides with the minimal internal perturbation able to destabilize the equilibrium. First, by reformulating a result of control theory, we explain that harmonic external perturbations reflect the spectral sensitivity of the Jacobian matrix at the equilibrium, with respect to constant changes of its coefficients. However, for this equivalence to hold, imaginary changes of the Jacobian's coefficients have to be allowed. The connection with dynamical stability is thus lost for real dynamical systems. We show that this issue can be avoided, thus recovering the fundamental link between dynamical and structural stability, by considering stochastic noise as external and internal perturbations. More precisely, we demonstrate that a system's local response to white-noise perturbations directly reflects the intensity of internal white noise that it can accommodate before asymptotic mean-square stability of the equilibrium is lost.
description: 13 pages, 2 figures
Optimization Strategy for Facade Integrated PV Trackers as Demonstrated in Solar Decathlon 2007
Creators: name: Wolf, J.
name: Steiner, L.
name: Hartkopf, T.
name: Spinnler, M.
name: Sattelmayer, T.
Publisher: name: WIP-Munich
Year: 2008
Subjects: PV Systems
PV Applications in the Built Environment

description: 23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 3315-3320
description: The Solar Decathlon joins 20 college and university teams in a competition to design, build, and operate the most attractive and energy-efficient solar-powered house. Technische Universität Darmstadt, Germany, was one of two European competitors and Overall Winner 2007 in this event. The present paper describes design and energy concept of the Solar Home focussing on its innovative solar façade. Together with a student group of TU
München, louvers of window shutters in the south, east- and west façades were equipped with a-Si PV modules and are tracked towards the sun elevation angle. By jury and visitors of SD 07, this façade was valued as a milestone in aesthetic and energy-efficient BiPV. Design of the microlouver system together with its control and tracking mechanism is described in detail. A topic of major interest is the solar energy yield gained by the solar louvers. Thus, optimum tracking strategies including tracking angles and time steps of west, east and south oriented louvers are presented. An experimentally validated test program was used for predicting the yearly PV energy yield for both Darmstadt and Washington locations. A risk analysis for the competition week as well as a short description of experiences during the competition round off the study.
Capacity of Entanglement for Non-local Hamiltonian
Creators: name: Shrimali, Divyansh
name: Bhowmick, Swapnil
name: Pandey, Vivek
name: Pati, Arun Kumar
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The notion of capacity of entanglement is the quantum information theoretic counterpart of the heat capacity which is defined as the second cumulant of the entanglement spectrum. Given any bipartite pure state, we can define the capacity of entanglement as the variance of the modular Hamiltonian in the reduced state of any of the subsystems. Here, we study the dynamics of this quantity under non-local Hamiltonian. Specifically, we address the question: Given an arbitrary non-local Hamiltonian what is the capacity of entanglement that the system can possess? As an useful application, we show that the quantum speed limit for creating the entanglement is not only governed by the fluctuation in the non-local Hamiltonian, but also depends inversely on the time average of square root of the capacity of entanglement. Furthermore, we discuss this quantity for a general self-inverse Hamiltonian and provide a bound on the rate of the capacity of entanglement. Towards the end, we generalise the capacity of entanglement for bipartite mixed states based on the relative entropy of entanglement and show that the above definition reduces to the capacity of entanglement for pure bipartite states. Our results can have several applications in diverse areas of physics.
description: 12 pages, 4 figures, comments are welcome
Fluxograma comparativo de recebimento e envio de artigos em consonância com as práticas de Ciência Aberta
Creators: name: Sousa, Marcos Eduardo de
Publisher: name: Zenodo
Year: 2022
Subjects: Ciência Aberta
preprint
dados de pesquisa
abertura de avaliação

description: O presente fluxograma visa mostrar a diferença entre o envio de artigos para periódicos no sistema tradicional (mantendo o anonimato do autor) e utilizando algumas dimensões de Ciência Aberta (preprint, dados de pesquisa e abertura de avaliação). São apresentados os fluxogramas a partir da perspectiva do autor e da equipe editorial. Além disso, buscou-se alinhar as opções, de modo a potencializar a capacidade de comparação entre as práticas. Esta ferramenta visa contribuir nos esclarecimentos das divergências de processos editoriais que estão envolvidos em cada modalidade. O arquivo de extensão *.drawio é editável através da extensão draw.io do diagrams.net, via Google Drive,
Periodic Texturing of Thin Film Silicon Solar Cell Superstrates
Creators: name: Van Erven, A.J.M.
name: Rutten, J.
name: Van Der Hofstad, G.
name: De Groot, H.
name: Peeters, P.
name: De Ruijter, J.
name: Borg, H.
name: Solntsev, S.
name: Isabella, O.
name: Zeman, M.
name: Rajeswaran, G.
name: Arya, R.
Publisher: name: WIP-Munich
Year: 2009
Subjects: Thin Films Solar Cells
Amorphous and Microcrystalline Silicon Solar Cells

description: 24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 2668-2671
description: In order to enhance light trapping in thin film crystalline silicon solar cells OM&T is investigating the possible
benefits of using periodic texturing next to random textured superstrates. One dimensional gratings
groove height were therefore optically characterized and used as substrates for
TCO growth morphology on these textured samples was in
ZnO:Al was measured by 4-point probe. The
cells was tested with a reference solar cell process which is being developed at OM&T. The short circuit current density of
Si:H solar cells on these gratings is characterized as a function of grating period and height and compared with cells on flat
(no texture) and Asahi U-type superstrates.
First Detection of $^3$He$^+$ in the Planetary Nebula IC$\,$418
Creators: name: Guzman-Ramirez, L.
name: Rizzo, J. R.
name: Zijlstra, A. A.
name: García-Miró, C.
name: Morisset, C.
name: Gray, M. D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The $^3$He isotope is important to many fields of astrophysics, including stellar evolution, chemical evolution, and cosmology. The isotope is produced in low-mass stars which evolve through the planetary nebula (PN) phase. $^3$He abundances in PNe can help test models of the chemical evolution of the Galaxy. We present the detection of the $^3$He$^+$ emission line using the single dish Deep Space Station 63, towards the PN IC$\,$418. We derived a $^3$He/H abundance in the range 1.74$\pm$0.8$\times$10$^{-3}$ to 5.8$\pm$1.7$\times$10$^{-3}$, depending on whether part of the line arises in an outer ionized halo. The lower value for $^3$He/H ratio approaches values predicted by stellar models which include thermohaline mixing, but requires that large amounts of $^3$He are produced inside low-mass stars which enrich the interstellar medium (ISM). However, this over-predicts the $^3$He abundance in HII regions, the ISM, and proto-solar grains, which is known to be of the order of 10$^{-5}$. This discrepancy questions our understanding of the evolution of the $^3$He, from circumstellar environments to the ISM.
description: 5 pages, 4 figures, accepted for publication in the Monthly Notices of the Royal Astronomical Society Letters
Images of graded polynomials on matrix algebras
Creators: name: Centrone, Lucio
name: de Mello, Thiago Castilho
Publisher: name: arXiv
Year: 2022
Subjects: subject: Rings and Algebras (math.RA)
subject: FOS: Mathematics
subject: 16R50, 16W50, 16R99, 16R10

description: The aim of this paper is to start the study of images of graded polynomials on full matrix algebras. We work with the matrix algebra $M_n(K)$ over a field $K$ endowed with its canonical $\mathbb{Z}_n$-grading (Vasilovsky's grading). We explicitly determine the possibilities for the linear span of the image of a multilinear graded polynomial over the field $\mathbb Q$ of rational numbers and state an analogue of the L'vov-Kaplansky conjecture about images of multilinear graded polynomials on $n\times n$ matrices, where $n$ is a prime number. We confirm such conjecture for polynomials of degree 2 over $M_n(K)$ when $K$ is a quadratically closed field of characteristic zero or greater than $n$ and for polynomials of arbitrary degree over matrices of order 2. We also determine all the possible images of semi-homogeneous graded polynomials evaluated on $M_2(K)$.
description: 17 pages; comments are welcome
Recombination in the Depletion Region of Actual Si Solar Cells
Creators: name: Abenante, L.
name: Tucci, M.
Publisher: name: WIP
Year: 2011
Subjects: Advanced Photovoltaics : New Concepts and Ultra-High Efficiency
Fundamental Studies

description: 26th European Photovoltaic Solar Energy Conference and Exhibition; 285-289
description: Expressing the SRH-recombination rate, U, in the volume of a p-n junction depletion region (JDR)
according to Sah, Noyce, Shockley (SNS) and Choo allows deriving a new expression for recombination current
density, J2, that is a function of the recombination velocity, S2, at a surface, which is located in a narrow region
around the position of the maximum U-value. The value of ideality factor n2, in both the expression for U and
new expression for J2, is not fixed. Measured dark and light J-V curves of four Si solar cells are fitted by adjusting
n2 and cell resistances in the double exponential model for direct current density at values that do not vary
with applied bias. The saturation current density, J1, is calculated at n1=1. J2 is calculated by both integrating U
over the JDR and using the new expression. The values for transport parameters are previously extracted from
measured quantum efficiency. In two devices, the integral of U is capable of giving the fit-values of J2. In these
cells, the new expression is evaluated at the fit-value for J2 resulting in very low S2-values. In the remaining cells,
the integral of U gives unfit J2-values at any n2-value. In these devices, the fit-values of J2 are obtained with the
new expression at assigned values for S2. Consistent with the literature, the fit-values of n2 vary from 1.7 to 3.9.
In the cells, where it cannot be calculated with the integral of U, the maximum S2 is 976 cm/s at n2=3.9. In these
cases, J2 appears to be determined by surfaces that are much more recombining than the p-n junction interface.
Effect on Electron-Beam Treatment of Al2O3 Doped ZnO Thin Films Prepared by RF Sputtering Method for Solar Cells Application
Creators: name: Kim, H.
name: Kim, Y.
name: Jeong, C.
Publisher: name: WIP
Year: 2011
Subjects: Thin Film Solar Cells
CIS and Related Ternary and Quaternary Thin Film Solar Cells

description: 26th European Photovoltaic Solar Energy Conference and Exhibition; 2936-2938
description: The effect on electron-beam treatment of 2wt% Al2O3 doped ZnO (AZO) thin films by RF sputtering
method were investigated for solar cells application. Thickness of as-deposited films was 250nm and 500nm, respectively,
and then they were instantly treated by exposure of electron beam, varying with exposure time of 60~300sec. and e-beam
intensity range of 1.0~2.5keV. As-deposited and e-beam treated samples were investigated, using X-ray diffraction
method (XRD), Hall effect measurement, and scanning electron microscope (SEM), for finding the optimized results of
AZO films. For samples with 250nm thick, properties’s variation wasn’t shown. On the other hand, crystallity of samples
was improved and grain size was bigger at AZO films of 500nm thick. E-beam treatment could be a good candidate
through surface modification and planarization for improvement of properties in AZO films.
Dynamical chiral magnetic current and instability in Weyl semimetals
Creators: name: Amitani, Tatsuya
name: Nishida, Yusuke
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Weyl semimetals realize massless relativistic fermions with two Weyl nodes separated in energy and momentum space, whose low-energy physics is described by Dirac fermions with an axial gauge constant. Here, we study their electromagnetic linear responses based on the effective field theory and on the chiral kinetic theory. Although the static chiral magnetic effect is canceled by the Chern-Simons current under the Pauli-Villars regularization, a dynamical magnetic field is found capable of driving an electric current along its direction, with the total transported charge being independent of temperature and chemical potential for a uniform field. We also incorporate dissipation in the relaxation-time approximation and study collective excitations coupled with Maxwell electromagnetic fields when Weyl node populations deviate from equilibrium. Their dispersion relations at low frequency and long wavelength are determined only by electric, chiral magnetic, and anomalous Hall conductivities, which predict unstable modes leading to anisotropic generation of electromagnetic waves oriented to the direction of Weyl node separation.
description: 6 pages, 4 figures; (v2) instability analysis modified by improving the relaxation-time approximation; (v3) published version
Influence of Evaporation Rate, Substrate Temperature and Process Chamber Pressure on the Microstructure of CdTe Layers
Creators: name: Häfner, K.
name: Morgner, H.
name: Zywitzki, O.
name: Modes, T.
name: Metzner, C.
name: Siepchen, B.
name: Späth, B.
name: Grimm, M.
Publisher: name: WIP
Year: 2011
Subjects: Thin Film Solar Cells
CdTe Solar Cells

description: 26th European Photovoltaic Solar Energy Conference and Exhibition; 3052-3054
description: The growth of CdTe thin film solar cell devices by close spaced sublimation (CSS) was systematically
investigated. CdTe thin films were deposited onto CdS coated FTO (fluorine doped tin oxide) glass substrates with
varying substrate temperature (300…500°C) and pressures of nitrogen (1.8x10-3 mbar, 6.7x10-2 mbar). The
microstructure of the films were examined before and after activation treatment with a high-resolution field emission
scanning electron microscope (FE-SEM) on ion beam prepared cross sections. It was observed that the grain size and
grain morphology are strongly dependent on the substrate temperature. From this investigation it is possible to define
two temperature regions in which compact CdTe layers with low porosity can be deposited. In contrast, little
influence of the chamber pressure on the grain size could be observed in the range examined.
Selfcomplementary quantum channels
Creators: name: Smaczynski, Marek
name: Roga, Wojciech
name: Zyczkowski, Karol
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Selfcomplementary quantum channels are characterized by such an interaction between the principal quantum system and the environment that leads to the same output states of both interacting systems. These maps can describe approximate quantum copy machines, as perfect copying of an unknown quantum state is not possible due to the celebrated no-cloning theorem. We provide here a parametrization of a large class of selfcomplementary channels and analyze their properties. Selfcomplementary channels preserve some residual coherences and residual entanglement. Investigating some measures of non-Markovianity we show that time evolution under selfcomplementary channels is highly non-Markovian.
description: 23 pages, 4 figures
Semiclassical spectrum of a Jordanian deformation of $AdS_5 \times S^5$
Creators: name: Borsato, Riccardo
name: Driezen, Sibylle
name: García, Juan Miguel Nieto
name: Wyss, Leander
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study a Jordanian deformation of the $AdS_5 \times S^5$ superstring that preserves 12 superisometries. It is an example of homogeneous Yang-Baxter deformations, a class that generalises TsT deformations to the non-abelian case. Many of the attractive features of TsT carry over to this more general class, from the possibility of generating new supergravity solutions to the preservation of worldsheet integrability. In this paper, we exploit the fact that the deformed $σ$-model with periodic boundary conditions can be reformulated as an undeformed one with twisted boundary conditions, to discuss the construction of the classical spectral curve and its semi-classical quantisation. First, we find global coordinates for the deformed background, and identify the global time corresponding to the energy that should be computed in the spectral problem. Using the curve of the twisted model, we obtain the one-loop correction to the energy of a particular solution, and we find that the charge encoding the twisted boundary conditions does not receive an anomalous correction. Finally, we give evidence suggesting that the unimodular version of the deformation (giving rise to a supergravity background) and the non-unimodular one (whose background does not solve the supergravity equations) have the same spectrum at least to one-loop.
description: 57 pages, 5 appendices, 1 figure; v2: published version in PRD, added clarifications (particularly on superisometries, shifts of spin, and choice of cut-off) and references, fixed typos, v3: fixed relative sign in eq (2.7)
Investigation of the Minority Carrier Lifetime Reduction during Industrial DC-Sputtering of Metal Seed Layers
Creators: name: Reinwand, D.
name: Graf, M.
name: Hartmann, P.
name: Preu, R.
name: Trassl, R.
Publisher: name: WIP-Munich
Year: 2010
Subjects: Wafer-Based Silicon Solar Cells and Materials Technology
Mono- and Multicrystalline Silicon Materials and Cells

description: 25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain; 1908-1911
description: This works presents the first results of the investigation of the minority carrier lifetime reduction
during industrial sputtering of metal seed layers for front side metallization of crystalline silicon solar cells with
respect to the cathode performance and the exposure time. Furthermore a method to avoid the reduction of the effective
lifetime during sputtering is demonstrated as well as the determination of the ion energy input with the retarding
field analysis. All investigations were done by using a new pilot system for inline sputtering. Because of
the deposition from below different concepts for substrate holders were used to minimize shadowing effects.
Compared to previous investigations a possibility to avoid the lifetime reduction was determined. This underlines
the possibility of sputtering for front side metallization.
Stochastic interpolation of sparsely sampled time series by a superstatistical random process and its synthesis in Fourier and wavelet space
Creators: name: Lübke, Jeremiah
name: Friedrich, Jan
name: Grauer, Rainer
Publisher: name: arXiv
Year: 2022
Subjects: subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Computational Physics (physics.comp-ph)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We present a novel method for stochastic interpolation of sparsely sampled time signals based on a superstatistical random process generated from a multivariate Gaussian scale mixture. In comparison to other stochastic interpolation methods such as Gaussian process regression, our method possesses strong multifractal properties and is thus applicable to a broad range of real-world time series, e.g. from solar wind or atmospheric turbulence. Furthermore, we provide a sampling algorithm in terms of a mixing procedure that consists of generating a 1 + 1-dimensional field u(t, ξ), where each Gaussian component uξ(t) is synthesized with identical underlying noise but different covariance function Cξ(t,s) parameterized by a log-normally distributed parameter ξ. Due to the Gaussianity of each component uξ(t), we can exploit standard sampling alogrithms such as Fourier or wavelet methods and, most importantly, methods to constrain the process on the sparse measurement points. The scale mixture u(t) is then initialized by assigning each point in time t a ξ(t) and therefore a specific value from u(t, ξ), where the time-dependent parameter ξ(t) follows a log-normal process with a large correlation time scale compared to the correlation time of u(t, ξ). We juxtapose Fourier and wavelet methods and show that a multiwavelet-based hierarchical approximation of the interpolating paths, which produce a sparse covariance structure, provide an adequate method to locally interpolate large and sparse datasets.
description: 25 pages, 14 figures
16.7% Efficient Solar Cell Using Electromagnetic Casting (EMC) Multicrystalline Silicon Wafers in an Industrial Type Solar Cell Process
Creators: name: Barton, P.C.
name: Coletti, G.
name: Veltkamp, T.
name: Nakagawa, K.
Publisher: name: WIP-Munich
Year: 2010
Subjects: Wafer-Based Silicon Solar Cells and Materials Technology
Mono- and Multicrystalline Silicon Materials and Cells

description: 25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain; 1921-1923
description: Purpose of the work is to understand the efficiency performance of EMC p-type mc-Si wafers from 18
different positions along the axis of growth of a 2,000kg, 35cmx35cm cross section, 7m long ingot. The 35cm x 35cm
mold yields 2x2 or 4 corner 156mm x 156mm size wafers. The multicrystalline wafers have been produced by the
electromagnetic casting (EMC) method. This EMC method uses an electromagnetic field to confine the melt from the
mold wall by electromagnetic force, F=JxB, and to melt silicon by induction heating. This technique enables semicontinuous
casting by melting the charged material at the top and solidifying the molten material at the bottom of the melt
without contact to the crucible wall. The solar cells were produced using a state of the art screen-print industrial type
solar cell process . A mc-Si group produced by conventional mc-Si production method was included for reference. The
average efficiency of the EMC produced wafers from bottom to top was 16,5% with a maximum exceeding 16,7%.
Growing massive black holes through super-critical accretion of stellar-mass seeds
Creators: name: Lupi, A.
name: Haardt, F.
name: Dotti, M.
name: Fiacconi, D.
name: Mayer, L.
name: Madau, P.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The rapid assembly of the massive black holes that power the luminous quasars observed at $z \sim 6-7$ remains a puzzle. Various direct collapse models have been proposed to head-start black hole growth from initial seeds with masses $\sim 10^5\,\rm M_\odot$, which can then reach a billion solar mass while accreting at the Eddington limit. Here we propose an alternative scenario based on radiatively inefficient super-critical accretion of stellar-mass holes embedded in the gaseous circum-nuclear discs (CNDs) expected to exist in the cores of high redshift galaxies. Our sub-pc resolution hydrodynamical simulations show that stellar-mass holes orbiting within the central 100 pc of the CND bind to very high density gas clumps that arise from the fragmentation of the surrounding gas. Owing to the large reservoir of dense cold gas available, a stellar-mass black hole allowed to grow at super-Eddington rates according to the "slim disc" solution can increase its mass by 3 orders of magnitudes within a few million years. These findings are supported by simulations run with two different hydro codes, RAMSES based on the Adaptive Mesh Refinement technique and GIZMO based on a new Lagrangian Godunov-type method, and with similar, but not identical, sub-grid recipes for star formation, supernova feedback, black hole accretion and feedback. The low radiative efficiency of super-critical accretion flows are instrumental to the rapid mass growth of our black holes, as they imply modest radiative heating of the surrounding nuclear environment.
description: 12 pages, 8 figures, 2 tables. Accepted for publication in MNRAS
Automated Characterisation of Multi-Junction Thin Film Silicon Solar Cells
Creators: name: Bliss, M.
name: Hibberd, C.
name: Qiu, Y.
name: Betts, T.R.
name: Gottschalg, R.
Publisher: name: WIP-Munich
Year: 2009
Subjects: Thin Films Solar Cells
Amorphous and Microcrystalline Silicon Solar Cells

description: 24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 2672-2678
description: Accurate measurements and calibration of amorphous silicon and micromorph multi-junction solar
cells poses a major challenge. Device measurements with commonly used single-lamp solar simulators can be
associated with large uncertainties, as small changes in the simulator light can lead to significant non-linear
differences in the current production of the device under test. To properly characterise multi-junction solar cells, a
multi-source or spectrally adjustable solar simulator is required. This way, the spectral distribution of the simulator
can be changed and stacked cells can be current matched. However, the methods available are somewhat slow, as
they require the measurement of a quantum efficiency, and difficult to operate when done manually.
This paper presents a method for automated characterisation of multi-junction and single-junction solar cells. Its key
element is a fitting method for the spectral response from device measurements at different spectra. The automated
approach is underlined with a simulated measurement of a double junction amorphous silicon cell. Simulations reflect
the capabilities of the LED-based solar simulator prototype developed at CREST. Results show that the method is
able to deliver high accuracy without the need for additional spectral response measurement systems or closely
matched reference cells. Single- and multi-junction device calibration methods are briefly reviewed and the
automated approach is described in detail including its potential error sources and requirements.
Sub-Inertial Gravity Modes in the B8V Star KIC 7760680 Reveal Moderate Core Overshooting and Low Vertical Diffusive Mixing
Creators: name: Moravveji, Ehsan
name: Townsend, Richard H. D.
name: Aerts, Conny
name: Mathis, Stephane
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: KIC 7760680 is so far the richest slowly pulsating B star, by exhibiting 36 consecutive dipole ($\ell=1$) gravity (g-) modes. The monotonically decreasing period spacing of the series, in addition to the local dips in the pattern confirm that KIC 7760680 is a moderate rotator, with clear mode trapping in chemically inhomogeneous layers. We employ the traditional approximation of rotation to incorporate rotational effects on g-mode frequencies. Our detailed forward asteroseismic modelling of this g-mode series reveals that KIC 7760680 is a moderately rotating B star with mass $\sim3.25$ M$_\odot$. By simultaneously matching the slope of the period spacing, and the number of modes in the observed frequency range, we deduce that the equatorial rotation frequency of KIC 7760680 is 0.4805 day$^{-1}$, which is 26\% of its Roche break up frequency. The relative deviation of the model frequencies and those observed is less than one percent. We succeed to tightly constrain the exponentially-decaying convective core overshooting parameter to $f_{\rm ov}\approx0.024\pm0.001$. This means that convective core overshooting can coexist with moderate rotation. Moreover, models with exponentially-decaying overshoot from the core outperform those with the classical step-function overshoot. The best value for extra diffusive mixing in the radiatively stable envelope is confined to $\log D_{\rm ext}\approx0.75\pm0.25$ (with $D_{\rm ext}$ in cm$^2$ sec$^{-1}$), which is notably smaller than theoretical predictions.
description: 12 Figures, 2 Tables, all data publicly available for download; accepted for publication in Astrophysical Journal
Mapping Quantum Efficiency Measurements: a Tool for Large Area Module Optimization
Creators: name: Losio, P.A.
name: Caglar, O.
name: Knauss, H.
name: Sutterlueti, J.
name: Kluth, O.
Publisher: name: WIP-Munich
Year: 2009
Subjects: Thin Films Solar Cells
Amorphous and Microcrystalline Silicon Solar Cells

description: 24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 2689-2691
description: Large area (1.4 m2) thin film photovoltaic modules require precise control of the deposition uniformity.
Most metrology tools focus either on the spatially resolved measurement of single layers or on the measurement of
the performance of a module as a whole. We present a new tool to map the quantum efficiency of a module. Mapping
quantum efficiency measurements of large area modules combines the well known functionality of quantum
efficiency measurements with spatially resolved information. This unique combination enables in-depth optimization
of both a-Si:H and tandem a-Si:H/μc-Si modules. This paper shows examples of the application of mapping QE
measurements at OC Oerlikon Solar.
Regular black holes, universes without singularities, and phantom-scalar field transitions
Creators: name: Chataignier, Leonardo
name: Kamenshchik, Alexander Yu.
name: Tronconi, Alessandro
name: Venturi, Giovanni
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We consider a procedure of elimination of cosmological singularities similar to that suggested in the recent paper by Simpson and Visser for the construction of regular black holes. It is shown that by imposing a non-singular cosmological evolution with a bounce in a flat Friedmann universe filled with a minimally coupled scalar field, we obtain a transition between the standard scalar field and its phantom counterpart. In this case, the potential of the scalar field has a non-analyticity of the cusp type. This result is also readily reproduced in the case of an anisotropic Bianchi I universe. We have also found a spherically symmetric static solution of the Einstein equations, free of singularities and sustained by a scalar field.
description: slightly expanded, with updated references and conceptual clarifications. Matches the published version
Economics of Depositing Azo-Front TCO Coatings with High Wall Thickness Rotary Sintered Ceramic Targets
Creators: name: Lippens, P.
name: Haldemann, M.
name: Van Rompaey, Y.
name: Leitner, K.
Publisher: name: WIP
Year: 2011
Subjects: Thin Film Solar Cells
CIS and Related Ternary and Quaternary Thin Film Solar Cells

description: 26th European Photovoltaic Solar Energy Conference and Exhibition; 2939-2942
description: Aluminium doped zinc-oxide (AZO) is the front transparent conductor of choice for CIGS PV
products. Whereas the majority of rigid thin film Si PV modules on glass are today still being manufactured with non
sputter deposited F:SnO2 (fluorine doped tin-oxide, FTO) coated glass, also here sputter deposited AZO is making
inroads as the front TCO. In both of these applications, the market is moving towards rotary ceramic targets with very
high wall thicknesses (even up to 20 mm). The manufacturing of such ceramic targets by plasma spraying is only
possible up to wall thicknesses of about 9 mm. Therefore, thick walled (14 – 20 mm) AZO ceramic targets can only
be made by bonding multiple cylindrical sintered segments on a backing tube. In this work, a comparison between
deposition behaviour and obtained coating characteristics will be presented for AZO-1 % thin films using either 13
mm or 20 mm sintered ceramic AZO targets. In addition, the total coating costs in either of both cases will be
compared. Part of this work has been performed in the framework of the EU-FP7 project SiliconLight.
Quantitative spectroscopy of B-type supergiants
Creators: name: Weßmayer, D.
name: Przybilla, N.
name: Butler, K.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Context. B-type supergiants are versatile tools to address various astrophysical topics, ranging from stellar atmospheres over stellar and galactic evolution to the cosmic distance scale. Aims. A hybrid non-LTE approach - line-blanketed model atmospheres computed under the assumption of local thermodynamic equilibrium (LTE) in combination with line formation calculations that account for deviations from LTE - is tested for quantitative analyses of B-type supergiants with masses $M<30 M_{\odot}$, characterising a sample of 14 Galactic objects. Methods. Hydrostatic plane-parallel atmospheric structures and synthetic spectra computed with Kurucz's Atlas12 code together with the non-LTE line-formation codes Detail/Surface are compared to results from full non-LTE calculations with Tlusty, and the effects of turbulent pressure on the models are investigated. High-resolution spectra are analysed for atmospheric parameters, using Stark-broadened hydrogen lines and multiple metal ionisation equilibria, and for elemental abundances. Fundamental stellar parameters are derived by considering stellar evolution tracks and Gaia EDR3 parallaxes. Interstellar reddening towards the target stars is determined by matching model spectral energy distributions to observed ones. Results. Our hybrid non-LTE approach turns out to be equivalent to hydrostatic full non-LTE modelling for the deeper photospheric layers of the B-type supergiants considered. Turbulent pressure can become relevant for microturbulent velocities larger than 10 km s$^{-1}$. High precision and accuracy is achieved for all derived parameters by bringing multiple indicators to agreement simultaneously. Abundances for chemical species (He, C, N, O, Ne, Mg, Al, Si, S, Ar, Fe) are derived with uncertainties of 0.05 to 0.10 dex. The derived ratios N/C vs. N/O tightly follow the predictions from Geneva stellar evolution models.
description: 32 pages, 24 figures, Accepted for publication in Astronomy & Astrophysics, Data: https://doi.org/10.5281/zenodo.6802567
Optimal Mounting Strategy for Single-Axis Tracking Non-Concentrating PV in Europe
Creators: name: Huld, T.
name: Suri, M.
name: Cebecauer, T.
name: Dunlop, E.
Publisher: name: WIP-Munich
Year: 2008
Subjects: PV Systems
Grid-connected Applications

description: 23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 3253-3257
description: We present a map-based method for estimating the yearly solar irradiation received by a PV modules mounted on a sun-tracker with a single axis of movement. The method finds the annual in-plane irradiation and calculates the optimum angle of inclination for a vertical-axis system with inclined modules or an inclined-axis system with the plane of the modules parallel to the axis of rotation. The approach is applied to the PVGIS climate database extending the European Subcontinent. Results indicate that optimised 1-axis tracking systems perform almost as well as a full 2-axis sun-tracking system. We also demonstrate that the use of such tracking systems is particularly advantageous at high latitudes (above 60° North), allowing tracking systems there to have the same yield as systems located in Central Europe.
Evaluation of the Bethe logarithm: from atom to chemical reaction
Creators: name: Ferenc, Dávid
name: Mátyus, Edit
Publisher: name: arXiv
Year: 2022
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: A general computational scheme for the (non-relativistic) Bethe logarithm is developed opening the route to `routine' evaluation of the leading-order quantum electrodynamics correction (QED) relevant for spectroscopic applications for small polyatomic and polyelectronic molecular systems. The implementation relies on Schwartz' method and minimization of a Hylleraas functional. In relation with electronically excited states, a projection technique is considered, which ensures positive definiteness of the functional over the entire parameter (photon momentum) range. Using this implementation, the Bethe logarithm is converged to a relative precision better than 1:10$^3$ for selected electronic states of the two-electron H$_2$ and H$_3^+$, and the three-electron He$_2^+$ and H+H$_2$ molecular systems. The present work focuses at nuclear configurations near the local minimum of the potential energy surface, but the computations can be repeated also for other structures.