16 research outputs found
Geometric model of black hole quantum -portrait, extradimensions and thermodynamics
Recently a short scale modified black hole metric, known as holographic
metric, has been proposed in order to capture the self-complete character of
gravity. In this paper we show that such a metric can reproduce some geometric
features expected from the quantum -portrait beyond the semi-classical
limit. We show that for a generic this corresponds to having an effective
energy momentum tensor in Einstein equations or, equivalently, non-local terms
in the gravity action. We also consider the higher dimensional extension of the
metric and the case of an AdS cosmological term. We provide a detailed
thermodynamic analysis of both cases, with particular reference to the
repercussions on the Hawking-Page phase transition.Comment: 36 pages, 8 figures, invited paper to the special issue "Entropy in
Quantum Gravity and Quantum Cosmology" edited by R. Garattini for the journal
"Entropy", accepted for publication; v2 version matching that published on
the journa
Analog Computing for Molecular Dynamics
Modern analog computers are ideally suited to solving large systems of
ordinary differential equations at high speed with low energy consumtion and
limited accuracy. In this article, we survey N-body physics, applied to a
simple water model inspired by force fields which are popular in molecular
dynamics. We demonstrate a setup which simulate a single water molecule in
time. To the best of our knowledge such a simulation has never been done on
analog computers before. Important implementation aspects of the model, such as
scaling, data range and circuit design, are highlighted. We also analyze the
performance and compare the solution with a numerical approach.Comment: 9 pages, 9 figures, submitted to Emerging Topics in Computing, IEEE
Tran
Solving Partial Differential Equations with Monte Carlo / Random Walk on an Analog-Digital Hybrid Computer
Current digital computers are about to hit basic physical boundaries with
respect to integration density, clock frequencies, and particularly energy
consumption. This requires the application of new computing paradigms, such as
quantum and analog computing in the near future. Although neither quantum nor
analog computer are general purpose computers they will play an important role
as co-processors to offload certain classes of compute intensive tasks from
classic digital computers, thereby not only reducing run time but also and
foremost power consumption.
In this work, we describe a random walk approach to the solution of certain
types of partial differential equations which is well suited for combinations
of digital and analog computers (hybrid computers). The experiments were
performed on an Analog Paradigm Model-1 analog computer attached to a digital
computer by means of a hybrid interface. At the end we give some estimates of
speedups and power consumption obtainable by using future analog computers on
chip.Comment: 9 pages, 7 figures. Proceeding for the MikroSystemTechnik Kongress
2023 (VDE Verlag MST Kongress 2023
ExaHyPE: An engine for parallel dynamically adaptive simulations of wave problems
ExaHyPE (“An Exascale Hyperbolic PDE Engine”) is a software engine for solving systems of first-order hyperbolic partial differential equations (PDEs). Hyperbolic PDEs are typically derived from the conservation laws of physics and are useful in a wide range of application areas. Applications powered by ExaHyPE can be run on a student’s laptop, but are also able to exploit thousands of processor cores on state-of-the-art supercomputers. The engine is able to dynamically increase the accuracy of the simulation using adaptive mesh refinement where required. Due to the robustness and shock capturing abilities of ExaHyPE’s numerical methods, users of the engine can simulate linear and non-linear hyperbolic PDEs with very high accuracy. Users can tailor the engine to their particular PDE by specifying evolved quantities, fluxes, and source terms. A complete simulation code for a new hyperbolic PDE can often be realised within a few hours — a task that, traditionally, can take weeks, months, often years for researchers starting from scratch. In this paper, we showcase ExaHyPE’s workflow and capabilities through real-world scenarios from our two main application areas: seismology and astrophysics