197,673 research outputs found
Inventory for a Reverse Journey. Photographic Image and Found Object - An investigation of travel and material transformation as a paradigm of artist's practice: Ed Ruscha, Douglas Huebler, Bas jan Ader, Jimmie Durham, Gustav Metzger, Kurt Schwitters & Cian Quayle.
No full textInventory for Reverse Journey is the title of a collection of photographic artefacts and found objects, which I have collected over the last twenty years. The title refers to one specific type of artist's journey, which is applicable to the `chronotope' of my archive, as a `metaphorical journey in space and time' (Bakhtin 1981, p. 81). The `city',`provincial town', `road', `threshold' and `interior' are recurrent motifs, which Bakhtin fused together to describe the historical evolution of the novel in relation to its different genres. Bakhtin's motifs are expanded as the basis of an evolutionary nomenclature of the artist's-journey, as a form of spatial mapping and identity formation. Alongside other sources from literature (Alain Robbe-Grillet), cinema (Michelangelo Antonioni), psychoanalysis (Kierkegaard) and critical theory (Walter Benjamin) I have developed a theoretical framework, which initially originated in an empirical process, that is reflected in the antecedents of this project. The research process, as a journey itself, has concretised this approach within a systems-based practice. This is mirrored in the work of the artists under investigation, as their differences and similarities are highlighted within a broad contextual analysis. Accordingly the tone of the writing shifts its register at different points in the thesis.
My journey is just one example of several paradigmatic formations of `travel' as a strategy, which investigates the work of six different artists, as a voluntary or involuntary form of exile. A deskilled use of the photographic image is examined in the work of Ed Ruscha, Douglas Huebler and Bas jan Ader in the spatial mapping of their chosen locations. The work of these artists manifests travel, as a strategy, in a benign form of regional and expatriate exile. The investigation shifts its focus from the New World to Europe, where the work of Jimmie Durham, Gustav Metzger and Kurt Schwitters is analysed in relation to their transformation of found objects and materials, and their relationship with a former 'home'. Their position registers different degrees of the `impossibility of return' to a point of origin, which exists in the mind rather than as a physical location. The transience of their work, and use of disparate materials, is counterbalanced by their physical presence in the work. Conversely Ader, Huebler and Ruscha are linked by a scale of decreasing visibility, as they are sublimated within their work in the formation of, what is now construed as, a unique photographic presence. The starting point for which is a return to the formative years of conceptualism in the 1960's, which set the scene for Durham and Metzger from the 1970's onwards. The spectre of Schwitters practice of forming (Formung) and unforming (Entformung) is significant for my analysis of the dematerialisation of the art-work and artist, by processes of series and repetition, distance and proximity, movement and stasis. Although `travel' is a ubiquitous term, I continue to use it as a portmanteau, which carries with it the themes and `salient' features of a typology of artist's journeys. In a moment of perceived obsolescence as digital information systems engender a culture of `selective-amnesia', these thoughts have informed my work, which runs parallel to the artist case-studies, and the material transformation of the photographic image and found object
An alternative SPH formulation: ADER-WENO-SPH
No full textWe present a new class of fully-discrete one-step SPH schemes based on a mesh-free ADER (Arbitrary DERivatives in space and time) reconstruction on moving particles in multiple space dimensions. In particular, the new SPH scheme computes mesh-free and local high order accurate polynomials in space and time to evaluate numerical fluxes at the midpoint between two interaction particles with a proper Riemann solver within the general SPH framework of Vila (1999) for nonlinear systems of hyperbolic conservation laws. The new scheme has been carefully tested against reference solutions for both the compressible Euler and the magneto-hydrodynamics (MHD) equations. The capability of the proposed scheme to accurately capture shocks and rarefaction waves for 1D and 2D problems with minimal amount of diffusion has been demonstrated. Via numerical evidence it has been shown that the new fully-discrete one-step ADER-WENO-SPH method is computationally more efficient than WENO-SPH schemes based on classical Runge–Kutta time-stepping. This is mainly due to the fact that with ADER timestepping the expensive stencil and neighbor search needs to be done only once per time step, while with Runge–Kutta time integrators the neighbor and stencil search is needed in each Runge–Kutta stage again
The myelinogenic potential of transplanted neural precursor cells
No full textAder M. The myelinogenic potential of transplanted neural precursor cells. Bielefeld; 2000
DeC and ADER: Similarities, Differences and a Unified Framework
No full textIn this paper, we demonstrate that the explicit ADER approach as it is used inter alia in
Zanotti et al. (Comput Fluids 118:204–224, 2015) can be seen as a special interpretation of the
deferred correction (DeC) method as introduced in Dutt et al. (BIT Numer Math 40(2):241–
266, 2000). By using this fact, we are able to embed ADER in a theoretical background of
time integration schemes and prove the relation between the accuracy order and the number
of iterations which are needed to reach the desired order. Next, we extend our investigation to
stiff ODEs, treating these source terms implicitly. Some differences in the interpretation and
implementation can be found. Using DeC yields typically a much simpler implementation,
while ADER benefits from a higher accuracy, at least for our numerical simulations. Then,
we also focus on the PDE case and present common space-time discretizations using DeC
and ADER in closed forms. Finally, in the numerical section we investigate A-stability for
the ADER approach—this is done for the first time up to our knowledge—for different order
using several basis functions and compare them with the DeC ansatz. Then, we compare the
performance of ADER and DeC for stiff and non-stiff ODEs and verify our analysis focusing
on two basic hyperbolic problems
High order entropy preserving ADER-DG schemes
No full textInternational audienceIn this paper, we develop a fully discrete entropy preserving ADER-Discontinuous Galerkin (ADER-DG) method. To obtain this desired result, we equip the space part of the method with entropy correction terms that balance the entropy production in space, inspired by the work of Abgrall. Whereas for the time-discretization we apply the relaxation approach introduced by Ketcheson that allows to modify the timestep to preserve the entropy to machineprecision. Up to our knowledge, it is the first time that a provable fully discrete entropy preserving ADER-DG scheme is constructed. We verify our theoretical results with various numerical simulations
The Derivative Riemann Problem: The basis for high order ADER Schemes
No full textThe corner stone of arbitrary high order schemes (ADER schemes) is the solution of the derivative Riemann problem at the element interfaces, a generalization of the classical Riemann problem first used by Godunov in 1959 to construct a first-order upwind numerical method for hyperbolic systems. The derivative Riemann problem extends the possible initial conditions to piecewise smooth functions, separated by a discontinuity at the interface. In the finite volume framework, these piecewise smooth functions are obtained from cell averages by a high order non-oscillatory WENO reconstruction, allowing hence the construction of non-oscillatory methods with uniform high order of accuracy in space and time
Histoire de l'expédition d'Egypte et de Syrie
No full textpar M. Ader ; revue, pour les détails stratégiques, par M. le Général BeauvaisGeschenkexlibris-Etikette: "Aus der Bibliothek von Oberstdivisionär Eugen Bircher Aarau der Bibliothek der Eidgenössischen Technischen Hochschule geschenkt" 002125367_0001 Exemplar der ETH-BI
DeC and ADER: Similarities, Differences and a Unified Framework
No full textIn this paper, we demonstrate that the explicit ADER approach as it is used
inter alia in [1] can be seen as a special interpretation of the deferred
correction (DeC) method as introduced in [2]. By using this fact, we are able
to embed ADER in a theoretical background of time integration schemes and prove
the relation between the accuracy order and the number of iterations which are
needed to reach the desired order. Next, we extend our investigation to stiff
ODEs, treating these source terms implicitly. Some differences in the
interpretation and implementation can be found. Using DeC yields typically a
much simpler implementation, while ADER benefits from a higher accuracy, at
least for our numerical simulations. Then, we also focus on the PDE case and
present common space-time discretizations using DeC and ADER in closed forms.
Finally, in the numerical section we investigate A-stability for the ADER
approach - this is done for the first time up to our knowledge - for different
order using several basis functions and compare them with the DeC ansatz. Then,
we compare the performance of ADER and DeC for stiff and non-stiff ODEs and
verify our analysis focusing on two basic hyperbolic problems.
[1] O. Zanotti, F. Fambri, M. Dumbser, and A. Hidalgo. Space-time adaptive
ader discontinuous galerkin finite element schemes with a posteriori sub-cell
finite volume limiting. Computers & Fluids, 118:204-224, 2015.
[2] A. Dutt, L. Greengard, and V. Rokhlin. Spectral Deferred Correction
Methods for Ordinary Differential Equations. BIT Numerical Mathematics,
40(2):241-266, 2000
On improving the efficiency of ADER methods
No full textThe (modern) arbitrary derivative (ADER) approach is a popular technique for
the numerical solution of differential problems based on iteratively solving an
implicit discretization of their weak formulation. In this work, focusing on an
ODE context, we investigate several strategies to improve this approach. Our
initial emphasis is on the order of accuracy of the method in connection with
the polynomial discretization of the weak formulation. We demonstrate that
precise choices lead to higher-order convergences in comparison to the existing
literature. Then, we put ADER methods into a Deferred Correction (DeC)
formalism. This allows to determine the optimal number of iterations, which is
equal to the formal order of accuracy of the method, and to introduce efficient
-adaptive modifications. These are defined by matching the order of accuracy
achieved and the degree of the polynomial reconstruction at each iteration. We
provide analytical and numerical results, including the stability analysis of
the new modified methods, the investigation of the computational efficiency, an
application to adaptivity and an application to hyperbolic PDEs with a Spectral
Difference (SD) space discretization
ADER-WENO Finite volume schemes with adaptive mesh refinement for hyperbolic problems
No full textIn this work it is presented an ADER-WENO approach for hyperbolic problems in the context of the finite volume method, using adaptive mesh refinement. ADER approach is of great interest for time integration since it achieves an arbitrary order of accuracyin a single time step. This is a joint work with M. Dumbser and O. Zanotti from the University of Trento (Italy)
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