Search results for " Freedom"
showing 10 items of 346 documents
Numerical simulations and experimental measurements of the stress intensity factor in perforated plates
2008
A numerical procedure, which combines two hybrid finite element formulations, was developed to analyse the stress intensity factors in cracked perforated plates with a periodic distribution of holes and square representative volume elements. The accuracy of the method in predicting the stress intensity factor was verified by a comparison with experimental measurements, carried out by a photoelasticity method, and by commercial finite element software. Several simulations were executed by varying both the crack length and the hole diameters, and the effects of the holes on the stress intensity factor are illustrated. The method shows high accuracy and efficiency, as small differences were ob…
Entanglement of photons in their dual wave-particle nature
2017
Wave-particle duality is the most fundamental description of the nature of a quantum object, which behaves like a classical particle or wave depending on the measurement apparatus. On the other hand, entanglement represents nonclassical correlations of composite quantum systems, being also a key resource in quantum information. Despite the very recent observations of wave-particle superposition and entanglement, whether these two fundamental traits of quantum mechanics can emerge simultaneously remains an open issue. Here we introduce and experimentally realize a scheme that deterministically generates entanglement between the wave and particle states of two photons. The elementary tool all…
Metric-affine f(R,T) theories of gravity and their applications
2018
We study $f(R,T)$ theories of gravity, where $T$ is the trace of the energy-momentum tensor ${T}_{\ensuremath{\mu}\ensuremath{\nu}}$, with independent metric and affine connection (metric-affine theories). We find that the resulting field equations share a close resemblance with their metric-affine $f(R)$ relatives once an effective energy-momentum tensor is introduced. As a result, the metric field equations are second-order and no new propagating degrees of freedom arise as compared to GR, which contrasts with the metric formulation of these theories, where a dynamical scalar degree of freedom is present. Analogously to its metric counterpart, the field equations impose the nonconservatio…
2018
Abstract We show that a Wilson-type discretization of the Gross–Neveu model, a fermionic N -flavor quantum field theory displaying asymptotic freedom and chiral symmetry breaking, can serve as a playground to explore correlated symmetry-protected phases of matter using techniques borrowed from high-energy physics. A large- N study, both in the Hamiltonian and Euclidean formalisms, yields a phase diagram with trivial, topological, and symmetry-broken phases separated by critical lines that meet at a tri-critical point. We benchmark these predictions using tools from condensed matter and quantum information science, which show that the large- N method captures the essence of the phase diagram…
Dark, Cold, and Noisy: Constraining Secluded Hidden Sectors with Gravitational Waves
2018
We explore gravitational wave signals arising from first-order phase transitions occurring in a secluded hidden sector, allowing for the possibility that the hidden sector may have a different temperature than the Standard Model sector. We present the sensitivity to such scenarios for both current and future gravitational wave detectors in a model-independent fashion. Since secluded hidden sectors are of particular interest for dark matter models at the MeV scale or below, we pay special attention to the reach of pulsar timing arrays. Cosmological constraints on light degrees of freedom restrict the number of sub-MeV particles in a hidden sector, as well as the hidden sector temperature. Ne…
Diffuse solar radiation statistics for Italy
1981
Abstract In this paper diffuse radiation is correlated with usually measured or more easy computable quantities in order to have a larger number of data available for the various applications of solar energy. Here are used two types of correlation: (a) diffuse radiation as a function of global and extraterrestrial radiation; (b) diffuse radiation as a function of ralative sunshine and extraterrestrial radiation. On the basis of the above correlations, empirical equations have been proposed and their coefficients have been calculated by fitting the experimental data of three Italian stations. The degree of accuracy of the fit has been estimated by a coefficient introduced and called by us “r…
Determination of the threshold of the break-up of invariant tori in a class of three frequency Hamiltonian systems
2001
We consider a class of Hamiltonians with three degrees of freedom that can be mapped into quasi-periodically driven pendulums. The purpose of this paper is to determine the threshold of the break-up of invariant tori with a specific frequency vector. We apply two techniques: the frequency map analysis and renormalization-group methods. The renormalization transformation acting on a Hamiltonian is a canonical change of coordinates which is a combination of a partial elimination of the irrelevant modes of the Hamiltonian and a rescaling of phase space around the considered torus. We give numerical evidence that the critical coupling at which the renormalization transformation starts to diverg…
Glass transition for dipolar hard spheres: A mode-coupling approach
1998
Abstract We apply the self-consistent mode-coupling equations, which were recently derived for molecular liquids, to a system of dipolar hard spheres. Making use of the direct correlation function in a mean spherical approximation and with a restriction of the rotational quantum number 1 to zero and one, we find three different phases in the η—T phase space. η and T denote the packing fraction and the temperature respectively. There is one phase where both the transitional degrees of freedom (TDOFs) and the orientational degrees of freedom (ODOFs) are ergodic (liquid), another phase with frozen TDOFs and ergodic ODOFs, and a third phase where TDOFs and ODOFs are frozen (glass). The dynamica…
Stability and Chaos
2010
In this chapter we study a larger class of dynamical systems that include but go beyond Hamiltonian systems. We are interested, on the one hand, in dissipative systems, i.e. systems that lose energy through frictional forces or into which energy is fed from exterior sources, and, on the other hand, in discrete, or discretized, systems such as those generated by studying flows by means of the Poincare mapping. The occurence of dissipation implies that the system is coupled to other, external systems, in a controllable manner. The strength of such couplings appears in the set of solutions, usually in the form of parameters. If these parameters are varied it may happen that the flow undergoes …