bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lunar Dome
Authors: Stimpfle Bernd 
Published: August 2020

AbstractIm Jahre 1969 brachte Apollo 11 die ersten Menschen auf den Mond. Anlässlich des 50‐jährigen Jubiläums wurde eine Roadshow konzipiert, die durch mehrere Städte der Vereinigten Staaten von Amerika reisen sollte. Hierfür wurde ein großes mobiles Theaterzelt mit 1 600 Sitzplätzen entwickelt. Als fliegender Bau besteht dieses Zelt aus Einzelelementen, die auf schnellen Aufbau und leichten Transport optimiert sind. Eine bogengestützte Hauptmembrane, eine elastisch gelagerte Projektionskuppel und eine große ETFE‐Fassade bilden die verschiedenen Hüllen und nehmen dem Projekt den Zeltcharakter. Anpassbare Fußelemente, verankert mit langen Erdnägeln, dienen als flexible Gründung für die verschiedenen Aufstellorte. Im Sommer 2019 stand das temporäre Theater für „Apollo 11 – the immersive live show“ in Pasadena, Kalifornien.
Wärmetransport und andere bauphysikalische Aspekte im Membranbau
Authors: Liebhart Heiko , Cremers Jan , Mirbach David , Marx Hannes 
Published: August 2020

AbstractDer vorliegende Artikel gibt einen Überblick über einige laufende und abgeschlossene Forschungsprojekte auf dem Gebiet des Membranbaus an der Hochschule für Technik (HFT) Stuttgart. Eine zentrale Herausforderung im Membranbau ist die Beeinflussung des radiativen Wärmeeintrags bzw. des Wärmeverlustes durch die Gebäudehülle zur energieeffizienten Gewährleistung einer komfortablen Raumtemperierung für die Nutzer ohne nennenswerte Beeinträchtigung der Tageslichtqualität. An der HFT wurde diese Fragestellung mit unterschiedlichen Ansätzen im Rahmen mehrerer Forschungsprojekte messtechnisch und numerisch behandelt. Im Projekt SoFt wurde die Vereinbarkeit von Dämmwirkung und Lichtdurchlässigkeit untersucht und mit der Dachkonstruktion einer Sporthalle realisiert. Im Rahmen des Projekts FMESG wurde eine statische, winkelselektive Verschattungseinheit nach dem Vorbild eines Sheddachs entworfen, numerisch untersucht und bis zum Prototypenstadium entwickelt. Der Einfluss von Oberflächenbeschichtung niedriger Emissivität auf die Wärmeströme durch ETFE‐Gebäudehüllenelemente wurde im Projekt Follow‐e2 adressiert und mit den Mitteln der dynamischen Gebäudesimulation numerisch untersucht. Das Potenzial zur Reduzierung des Energiebedarfs von Gebäuden durch dynamische Verschattung mittels elektrochromer Elemente wurde im Projekt FLEX‐G mit den Mitteln numerischer Gebäudesimulation und heuristischer Optimierungsverfahren untersucht.
Natural products present neurotrophic properties in neurons of the limbic system in aging rodents
Authors: Flores Gonzalo , Flores‐Gómez Gabriel Daniel , Díaz Alfonso , Penagos‐Corzo Julio César , Iannitti Tommaso , Morales‐Medina Julio César 
Published: August 2020

AbstractAging is a complex process that can lead to neurodegeneration and, consequently, several pathologies, including dementia. Physiological aging leads to changes in several body organs, including those of the central nervous system (CNS). Morphological changes in the CNS and particularly the brain result in motor and cognitive deficits affecting learning and memory and the circadian cycle. Characterizing neural modifications is critical to designing new therapies to target aging and associated pathologies. In this review, we compared aging to the changes occurring within the brain and particularly the limbic system. Then, we focused on key natural compounds, apamin, cerebrolysin, Curcuma longa, resveratrol, and N‐PEP‐12, which have shown neurotrophic effects particularly in the limbic system. Finally, we drew our conclusions delineating future perspectives for the development of novel natural therapeutics to ameliorate aging‐related processes.
Total coliform and Escherichia coli in microplastic biofilms grown in wastewater and inactivation by peracetic acid
Authors: Boni William , Parrish Kathleen , Patil Shreya , Fahrenfeld Nicole L. 
Published: August 2020

AbstractMicroplastics (MP) have been proposed as a vector for pathogenic microorganisms in the freshwater environment. The objectives of this study were (a) to compare the fecal indicator growth in biofilms on MP and material control microparticles incubated in different wastewater fractions and (b) to compare MP biofilm, natural microparticle biofilm, and planktonic cell susceptibility to disinfection by peracetic acid (PAA). Biofilms were grown on high‐density polyethylene, low‐density polyethylene, polypropylene MP, or wood chips (as a material control) and incubated in either wastewater influent or pre‐disinfection secondary effluent. Reactors were disinfected with PAA, biofilms were dislodged, and total coliform and Escherichia coli were cultivated. Fecal indicators were quantifiable in both MP and wood biofilms incubated in the wastewater influent but only on the wood biofilms incubated in secondary wastewater effluent. More total coliform grew in the wood biofilms than MP biofilms, and the biofilms grown on MP and woodchips were more resistant to disinfection than planktonic bacteria. Thus, it may be possible to refer to the disinfection literature for fecal indicators in biofilm on other particles to predict behavior on MP. Treatments that remove particles in general would help reduce the potential for fecal indicator bypass of disinfection.Practitioner points

MP biofilm had lower concentrations of fecal indicators than wood biofilm

Biofilm on MP was not more resistant to disinfection than wood biofilm

Biofilms, regardless of substrate, were more resistant to disinfection than planktonic organisms
Muslim NGOs, Zakat and the Provision of Social Welfare in Sub-Saharan Africa: An Introduction
Authors: Weiss Holger 
Published: August 2020

AbstractThis chapter outlines the articulations and actions of Muslim NGOs with a special focus on their instrumentalization of Islamic social finance instruments, namely sadaqa or voluntary almsgiving and donations and zakat or mandatory almsgiving in contemporary sub-Saharan Africa. Zakat constitutes a form of vertical philanthropy in all cases above as it is formal, structuralized and institutionalized. Sadaqa, in turn, corresponds to horizontal philanthropy as it is organized through private, personalized and informal ways, commonly through self-help groups or mosque funds. However, there has been an expansion of vertical forms of philanthropy during the last decade due to the establishment of private foundations, trusts and corporate foundations by High Net-Worth Individuals or ‘Muslim entrepreneurs’ as well as community chests and foundations in many sub-Saharan countries. Various studies estimate that zakat amounts from USD 200 billion to USD 1 trillion per annum across the world or around USD 187 million among countries in the Organisation of Islamic Cooperation (OIC). Therefore, not only Muslim states but also Muslim NGOs have turned their interest to mobilize zakat for poverty alleviation in Muslim majority countries as well as for international development and humanitarian projects.
Stabilised Hybrid Discontinuous Galerkin Methods for the Stokes Problem with Non-standard Boundary Conditions
Authors: Barrenechea Gabriel R. , Bosy Michał , Dolean Victorita 
Published: August 2020

AbstractIn several studies it has been observed that, when using stabilised
$$\mathbb {P}_k^{}\times \mathbb {P}_k^{}$$

ℙ

k

×

ℙ

k

elements for both velocity and pressure, the error for the pressure is smaller, or even of a higher order in some cases, than the one obtained when using inf-sup stable
$$\mathbb {P}_k^{}\times \mathbb {P}_{k-1}^{}$$

ℙ

k

×

ℙ

k
−
1

(although no formal proof of either of these facts has been given). This increase in polynomial order requires the introduction of stabilising terms, since the finite element pairs used do not guarantee the inf-sup condition. With this motivation, we apply the stabilisation approach to the hybrid discontinuous Galerkin discretisation for the Stokes problem with non-standard boundary conditions.
RBF Based CWENO Method
Authors: Hesthaven Jan S. , Mönkeberg Fabian , Zaninelli Sara 
Published: August 2020

AbstractSolving hyperbolic conservation laws on general grids can be important to reduce the computational complexity and increase accuracy in many applications. However, the use of non-uniform grids can introduce challenges when using high-order methods. We propose to use a Central WENO (CWENO) scheme based on radial basis function (RBF) interpolation, which is applicable to scattered data. We develop a smoothness indicator, based on RBFs, and CWENO specific weights which depend on the mesh size of the grid to construct an arbitrarily high order RBF-CWENO method. We evaluate the method with multiple examples in one dimension.
A Conservative Hybrid Method for Darcy Flow
Authors: Jain Varun , Fisser Joël , Palha Artur , Gerritsma Marc 
Published: August 2020

AbstractWe present a hybrid mimetic spectral element formulation for Darcy flow. The discrete representations for (1) conservation of mass, and (2) inter-element continuity, are topological relations that lead to sparse matrix systems. These constraints are independent of the element size and shape, and thus invariant under mesh transformations. The resultant algebraic system is extremely sparse even for high degree polynomial basis. Furthermore, the system can be efficiently assembled and solved for each element separately.
High-Order Mesh Generation Based on Optimal Affine Combinations of Nodal Positions
Authors: Stees Mike , Shontz Suzanne M. 
Published: August 2020

AbstractIn this paper, we propose a new optimization-based method for high-order mesh generation. Our proposed method is based on affine combinations of nodal positions. For each interior node in the high-order straight-sided mesh, a set of weights that relates the node to its neighbors is calculated. After the high-order boundary nodes are curved to conform with the true boundary, the interior nodes are moved based on the generated weights and the new boundary positions. We present results from applying our method to several aerospace engineering geometries in 2D and 3D which demonstrate the capabilities of our method.
Sparse Spectral-Element Methods for the Helically Reduced Einstein Equations
Authors: Lau Stephen R. 
Published: August 2020

AbstractWe describe ongoing work towards construction—via multidomain, modal, spectral methods—of helically symmetric spacetimes representing binary neutron stars. Adopting “particle” models, we focus here on solution of the helically reduced Einstein equations. These models allow us to remove the complication of a stellar fluid. However, the choice of inner boundary conditions for these models is also a stubborn issue. We examine this issue and its effect on the “harmonic gauge”.
On the Order Reduction of Entropy Stable DGSEM for the Compressible Euler Equations
Authors: Hindenlang Florian J. , Gassner Gregor J. 
Published: August 2020

AbstractIs the experimental order of convergence lower when using the entropy stable DGSEM-LGL variant? Recently, a debate on the question of the convergence behavior of the entropy stable nodal collocation discontinuous Galerkin spectral element method (DGSEM) with Legendre-Gauss-Lobatto nodes has emerged. Whereas it is well documented that the entropy conservative variant with no additional interface dissipation shows an odd-even behavior when testing its experimental convergence order, the results in the literature are less clear regarding the entropy stable version of the DGSEM-LGL, where explicit Riemann solver type dissipation is added at the element interfaces. We contribute to the ongoing discussion and present numerical experiments for the compressible Euler equations, where we investigate the effect of the choice of the numerical surface flux function. In our experiments, it turns out that the choice of the numerical surface flux has an impact on the convergence order. Penalty type numerical fluxes with high dissipation in all waves, such as the LLF and the HLL flux, appear to affect the convergence order negatively for odd polynomial degrees N, in contrast to the entropy conserving variant, where even polynomial degrees N are negatively affected. This behavior is more pronounced in low Mach number settings. In contrast, for numerical surface fluxes with less dissipative behavior in the contact wave such as e.g. Roe’s flux, the HLLC flux and the entropy conservative flux augmented with 5-wave matrix dissipation, optimal convergence rate of N + 1 independent of the Mach number is observed.
Two Decades Old Entropy Stable Method for the Euler Equations Revisited
Authors: Sjögreen Björn , Yee H. C. 
Published: August 2020

AbstractThe objective of this paper is to prove for the first time that the entropy split scheme of Olsson and Oliger (Energy and maximum norm estimates for nonlinear conservation laws. RIACS Technical Report 94.01, 1994; Gerritsen and Olsson, J Comput Phys 129:245–262, 1996; Yee et al., J Comput Phys 162:33–81, 2000) is the recent definition of an entropy stable method for central differencing with SBP operators for both periodic and non-periodic boundary conditions for nonlinear Euler equations. The proof is to replace the spatial derivatives by summation-by-parts (SBP) difference operators in the entropy split form of the equations using the physical entropy of the Euler equations. The numerical boundary closure follows directly from the SBP operator. No additional numerical boundary procedure is required. In contrast, Tadmor-type entropy conserving schemes Tadmor (Acta Numer 12:451–512, 2003) using mathematical entropies do not naturally come with a numerical boundary closure and a generalized SBP operator has to be developed Roanocha (J Comput Phys 362:20–48, 2018).
A Mimetic Spectral Element Method for Free Surface Flows
Authors: Nielsen L. , Gervang B. 
Published: August 2020

AbstractWe derive a compatible high order discretization method that relies heavily on the underlying geometric structure and obeys the topological sequences for 2D free surface flows with fully submerged structures. The flow is assumed inviscid and irrotational. This allows us to write the continuity and Navier–Stokes equations using a velocity potential as a Laplace equation and the differential form of the unsteady Bernoulli’s equation. We use a mixed variational formulation and results confirm the theoretical results that we obtain global and local divergence free solutions.
Spectral/hp Methodology Study for iLES-SVV on an Ahmed Body
Authors: Buscariolo Filipe F. , Sherwin Spencer J. , Assi Gustavo R. S. , Meneghini Julio R. 
Published: August 2020

AbstractThe Ahmed Body is one of the most widely studied bluff bodies used for automotive conceptual studies and Computational Fluid Dynamics (CFD) software validation. With the advances of the computational processing capacity and improvement in computing costs, high-fidelity turbulence models, such as Detached Eddies Simulation (DES) and Large Eddies Simulation (LES), are becoming a reality for industrial cases, as studied by Buscariolo et al. (Analysis of turbulence models applied to CFD drag simulations of a small hatchback vehicle. SAE Paper 2016-36-0201, Society of Automotive Engineers, 2016), evaluating DES models to automotive applications.
An Explicit Mapped Tent Pitching Scheme for Maxwell Equations
Authors: Gopalakrishnan Jay , Hochsteger Matthias , Schöberl Joachim , Wintersteiger Christoph 
Published: August 2020

AbstractWe present a new numerical method for solving time dependent Maxwell equations, which is also suitable for general linear hyperbolic equations. It is based on an unstructured partitioning of the spacetime domain into tent-shaped regions that respect causality. Provided that an approximate solution is available at the tent bottom, the equation can be locally evolved up to the top of the tent. By mapping tents to a domain which is a tensor product of a spatial domain with a time interval, it is possible to construct a fully explicit scheme that advances the solution through unstructured meshes. This work highlights a difficulty that arises when standard explicit Runge Kutta schemes are used in this context and proposes an alternative structure-aware Taylor time-stepping technique. Thus explicit methods are constructed that allow variable time steps and local refinements without compromising high order accuracy in space and time. These Mapped Tent Pitching (MTP) schemes lead to highly parallel algorithms, which utilize modern computer architectures extremely well.
Viscous Diffusion Effects in the Eigenanalysis of (Hybridisable) DG Methods
Authors: Moura Rodrigo C. , Fernandez Pablo , Mengaldo Gianmarco , Sherwin Spencer J. 
Published: August 2020

AbstractWe present the first eigenanalysis of hybridisable discontinuous Galerkin (HDG) schemes for the advection-diffusion equation in one dimension. This study is also one of the first to include viscous diffusion effects in the eigenanalysis of discontinuous spectral element methods. The interplay between upwind dissipation and viscous diffusion is discussed and preliminary insights deemed relevant to (under-resolved) turbulence computation approaches are presented.
A Review of Regular Decompositions of Vector Fields: Continuous, Discrete, and Structure-Preserving
Authors: Hiptmair Ralf , Pechstein Clemens 
Published: August 2020

AbstractWe elaborate so-called regular decompositions of vector fields on a three-dimensional Lipschitz domain where the field and its rotation/divergence belong to L2 and where the tangential/normal component of the field vanishes on a sufficiently smooth “Dirichlet” part of the boundary. We impose no restrictions on the topology of the domain, its boundary, or the Dirichlet boundary parts.The field is split into a regular vector field, whose Cartesian components lie in H1 and vanish on the Dirichlet boundary, and a remainder contained in the kernel of the rotation/divergence operator. The decomposition is proved to be stable not only in the natural norms, but also with respect to the L2 norm. Besides, for special cases of mixed boundary conditions, we show the existence of H1-regular potentials that characterize the range of the rotation and divergence operator.We conclude with results on discrete counterparts of regular decompositions for spaces of low-order discrete differential forms on simplicial meshes. Essentially, all results for function spaces carry over, though local correction terms may be necessary. These discrete regular decompositions have become an important tool in finite element exterior calculus (FEEC) and for the construction of preconditioners.
Spectral Galerkin Method for Solving Helmholtz and Laplace Dirichlet Problems on Multiple Open Arcs
Authors: Jerez-Hanckes Carlos , Pinto José 
Published: August 2020

AbstractWe present a spectral numerical scheme for solving Helmholtz and Laplace problems with Dirichlet boundary conditions on an unbounded non-Lipschitz domain
$$\mathbb {R}^2 \backslash \overline {\Gamma }$$

ℝ

2

∖

Γ

¯

, where Γ is a finite collection of open arcs. Through an indirect method, a first kind formulation is derived whose variational form is discretized using weighted Chebyshev polynomials. This choice of basis allows for exponential convergence rates under smoothness assumptions. Moreover, by implementing a simple compression algorithm, we are able to efficiently account for large numbers of arcs as well as a wide wavenumber range.
An hp-Adaptive Iterative Linearization Discontinuous-Galerkin FEM for Quasilinear Elliptic Boundary Value Problems
Authors: Houston Paul , Wihler Thomas P. 
Published: August 2020

AbstractIn this article we consider the a posteriori error analysis of hp-version discontinuous Galerkin finite element methods for the numerical solution of a second-order quasilinear elliptic boundary value problem of strongly monotone type. In particular, we employ and analyze a practical solution scheme based on exploiting a discrete Kačanov iterative linearization. The resulting a posteriori error bound explicitly takes into account the three sources of error: discretization, linearization, and linear solver errors. Numerical experiments are presented to demonstrate the practical performance of the proposed hp-adaptive refinement strategy.
Erosion Wear Evaluation Using Nektar+ +
Authors: Mejía Manuel F. , Serson Douglas , Moura Rodrigo C. , Carmo Bruno S. , Escobar-Vargas Jorge , González-Mancera Andrés 
Published: August 2020

AbstractErosion wear is the loss of mass on the surface of a solid body in contact with a moving fluid. When the fluid under study has solid particulate material or sediments, the erosion could be significant (Kulu and Kleis, Solid particle erosion: occurrence, prediction and control. Springer, London, 2008; Karimi and Schmid, Wear 156(1):33–47, 1992). Several studies (Karimi and Schmid, Wear 156(1):33–47, 1992; Neopane and Cervantes, Global J Res Eng Mech Mech Eng 11:17–26, 2011; Zeng et al., Proc IMechE 231(3):182–196, 2017; Padhy and Saini, Energy 39(1):286–293, 2012; Bajracharya et al., Wear 264(3–4):177–184, 2008; Kumar and Saini, Renew Sust Energ Rev 14(1):374–383, 2010; Xiao et al., J Hydrodyn B 19(3):356–364, 2007; Zhu et al., Nucl Eng Des 273:396–411, 2014; Chongji et al., IOP Conf Ser Earth Environ Sci 22(5):052019, 2014; Finnie and Kabil, Wear 8(1):60–69, 1965; Finnie, Wear 3(2):87–103, 1960; Finnie, Wear 19(1): 81–90, 1972) have been developed to investigate this phenomenon. Nevertheless, few attention has been paid to influence of small eddies during the erosion process, limiting the accuracy of the results in the simulation. The use of spectral element methods can allow increasing accuracy in the simulation due to the potential to consider these smaller scales.To the best of the authors’ knowledge, there is no work that uses high order methods to evaluate erosion wear rate. This research aim is to assess the impact of higher resolution methods on the prediction of erosion wear rate and distribution. Nektar+ + is a framework to solve partial differential equations using spectral/hp element method (Cantwell et al., Comput Phys Commun 192:205–219, 2015). This work presents a methodology to model erosion wear in Nektar+ +, with the creation of two modules. The first one is for the particle tracking evaluation and the record of impact on the walls of interest. The second one implements the Hutchings and Finnie models (Finnie, Wear 3(2):87–103, 1960; Finnie, Wear 19(1):81–90, 1972; Padhy and Saini, Renew Sust Energ Rev 12(7):1974–1987, 2008; Dutta, Bulle-effect and its implications for morphodynamics of river diversions. Ph.D. Thesis. University of Illinois at Urbana-Champaign, 2017) to predict the material removal rate as a function of the velocity and the angle of impact of each particle, the particle diameter and density, and the hardness relationship between particles and the wall. At the end, the particles trajectories and erosion distribution on walls are obtained. To assess effectiveness of the methodology a Backward Facing Step was investigate and the erosion patterns were found.
DIRK Schemes with High Weak Stage Order
Authors: Ketcheson David I. , Seibold Benjamin , Shirokoff David , Zhou Dong 
Published: August 2020

AbstractRunge-Kutta time-stepping methods in general suffer from order reduction: the observed order of convergence may be less than the formal order when applied to certain stiff problems. Order reduction can be avoided by using methods with high stage order. However, diagonally-implicit Runge-Kutta (DIRK) schemes are limited to low stage order. In this paper we explore a weak stage order criterion, which for initial boundary value problems also serves to avoid order reduction, and which is compatible with a DIRK structure. We provide specific DIRK schemes of weak stage order up to 3, and demonstrate their performance in various examples.