1435 research outputs found
Sort by
Staggered fermions simulations on GPUs
No full textSUMMARY We present our implementation of the RHMC algorithm for staggered fermions on
Graphics Processing Units using the NVIDIA CUDA programming language. While
previous studies exclusively deal with the Dirac matrix inversion problem, our
code performs the complete MD trajectory on the GPU. After pointing out the
main bottlenecks and how to circumvent them, we discuss the performance of our
code
Non-Abelian vortex dynamics: Effective world-sheet action
No full textThe low-energy vortex effective action is constructed in a wide class of
systems in a color-flavor locked vacuum, which generalizes the results found
earlier in the context of U(N) models. It describes the weak fluctuations of
the non-Abelian orientational moduli on the vortex worldsheet. For instance,
for the minimum vortex in SO(2N) x U(1) or USp(2N) x U(1) gauge theories, the
effective action found is a two-dimensional sigma model living on the Hermitian
symmetric spaces SO(2N)/U(N) or USp(2N)/U(N), respectively. The fluctuating
moduli have the structure of that of a quantum particle state in spinor
representations of the GNO dual of the color-flavor SO(2N) or USp(2N) symmetry,
i.e. of SO(2N) or of SO(2N+1). Applied to the benchmark U(N) model our
procedure reproduces the known CP(N-1) worldsheet action; our recipe allows us
to obtain also the effective vortex action for some higher-winding vortices in
U(N) and SO(2N) theories
Rotational sensitivity of the "G-Pisa" gyrolaser
No full textG-Pisa is an experiment investigating the possibility to operate a high
sensitivity laser gyroscope with area less than for improving the
performances of the mirrors suspensions of the gravitational wave antenna
Virgo. The experimental set-up consists in a He-Ne ring laser with a 4 mirrors
square cavity. The laser is pumped by an RF discharge where the RF oscillator
includes the laser plasma in order to reach a better stability. The contrast of
the Sagnac fringes is typically above 50% and a stable regime has been reached
with the laser operating both single mode or multimode. The effect of hydrogen
contamination on the laser was also checked. A low-frequency sensitivity, below
, in the range of has been
measured
Ottimizzazione della produzione tramite software di scheduling
No full textRiassunto: Automazione della pianificazione della produzione tramite un software di scheduling: definizioni e applicazione. A partire da una classificazione dell’architettura delle linee produttive, viene proposto un caso applicativo per mostrare le potenzialità degli algoritmi di simulazione delle sequenze di operazioni su un determinato parco macchine. Summary: Production planning automation by a scheduling software. Overview of the architecture of production lines, case study and potential of simulation algorithms for the sequence of operations on a given set of machines
Left invertibility of discrete systems with finite inputs and quantized output
Get PDFThe aim of this paper is to address left invertibility for dynamical systems with inputs and outputs in discrete sets. We study systems which evolve in discrete time within a continuous state-space; quantized outputs are generated by the system according to a given partition of the state-space, while inputs are arbitrary sequences of symbols in a finite alphabet, which are associated to specific actions on the system. Our main results are obtained under some contractivity hypotheses. The problem of left invertibility, i.e. recovering an unknown input sequence from the knowledge of the corresponding output string, is addressed using the theory of Iterated Function Systems (IFS), a tool developed for the study of fractals. We show how the IFS naturally associated to a system and the geometric properties of its attractor are linked to the invertibility property of the system. Our main result is a necessary and sufficient condition for left invertibility and uniform left invertibility for joint contractive systems. In addition, an algorithm is proposed to recover inputs from output strings. A few examples are presented to illustrate the application of the proposed method
Left invertibility of output-quantized systems: an application to cryptography
No full textIn this paper a secure communication method is proposed, based on left invertibility of output-quantized dynamical systems. The sender uses an output-quantized linear system with a feedback function to encode messages, which are sequences of inputs of the system. So left invertibility property enables the receiver to recover the messages. The secret key is formed by the system’s parameters, including the feedback function. The use of quantization makes the cryptographic system work exactly, and without asymptotic estimates. Simulations of encoding-decoding procedure and results about security of the method are finally shown
Optimizing bulk data transfers using network measurements: a practical case
No full textSUMMARY The quality of the connectivity provided by the network infrastructure of a Grid is a crucial factor to guarantee the accessibility of Grid services, schedulate efficiently processing and data transfer activity on the Grid and meet QoS expectations. Yet most Grid application do not take into consideration the expected performance of the network resources they plan to use. In this paper we describe the effective use of a Grid Monitoring framework, whose measurements are used to introduce network aware features in a legacy application.
We use GlueDomains, a network monitoring framework oriented to Grid infrastructures that measures a small (although possibly extensible) set of network parameters. Such framework works off the shelf with minimal administrative effort, is reliable, and has a negligible impact on
system operation. The deployment covers a Metropolitan Grid infrastructure, aimed at supporting a data intensive eScience application. We describe a real use case consisting of bulk data trasfers during the operation of the Grid for the Virgo experiment
Thermal Monopole Condensation and Confinement in finite temperature Yang-Mills Theories
No full textWe investigate the connection between Color Confinement and thermal Abelian
monopoles populating the deconfined phase of SU(2) Yang-Mills theory, by
studying how the statistical properties of the monopole ensemble change as the
confinement/deconfinement temperature is approached from above. In particular
we study the distribution of monopole currents with multiple wrappings in the
Euclidean time direction, corresponding to two or more particle permutations,
and show that multiple wrappings increase as the deconfinement temperature is
approached from above, in a way compatible with a condensation of such objects
happening right at the deconfining transition. We also address the question of
the thermal monopole mass, showing that different definitions give consistent
results only around the transition, where the monopole mass goes down and
becomes of the order of the critical temperature itself
A Benamou-Brenier approach to branched transport
No full textSUMMARY The problem of branched transportation aims to describe the movement of
masses when, due to concavity effects, they have the interest to travel
together as much as possible, because the cost for a path of lengt
Weak Optimal Controls in Coefficients for Linear Elliptic Problems
No full textSUMMARY In this paper we study an optimal control problem associated to a linear
degenerate elliptic equation with mixed boundary conditions. The equations of
this type can exhibit the Lavrentieff phenomenon and non-uniqueness of weak
solutions. We adopt the weight function as a control in . Using
the direct method in the Calculus of variations, we discuss the solvability of
this optimal control problem in the class of weak admissible solutions