Manufacturing systems with a production dependent failure rate: structure of optimality

This report provides the structure of a policy minimizing a long term, average, expected, backlog/inventory cost for a fluid model, single machine, single product manufacturing system subject to a failure/repair Markov process, where the failure rate is a piecewise constant function of the production rate. This policy generalizes previous results and confirms several conjectures reported in the literature, providing an interesting insight into the problem

Establishing Italian Jazz on the International Scene 1960-1980: Four Case Studies: Nunzio Rotondo, Giorgio Gaslini, Enrico Rava, Perigeo

This paper sheds new light on the developments in Italian jazz in the two decades 1960-1980. It opens by touching on context and antecedents: the relationships with Italian musical traditions in early American jazz, the acceptance and refusal of jazz by Italian cultural institutions and movements before 1960, and the late '50s key developments both in jazz and arts/media. In the early '60s, Italian jazz was characterized by two small scenes with marked differences in Rome and Milan and with a few further relevant events. An active and well rooted specialist magazine (Musica Jazz) provides relatively good documentation on these beginnings, quite detached from other general movements in music. By the end of the decade several ideological, cultural, political ruptures will have changed this panorama, and while Italian jazz was active in these changes, its exponents also had to deal with the complex situation they created from the point of view of artistic challenges, working conditions, and relationships with the recording industry. In order to discuss these changes and the different strategies adopted by musicians, four case studies will be examined to gain a better understanding of the process. Nunzio Rotondo, while almost unknown outside of Italy, was one of the first Italian musicians to successfully perform internationally after the war. He subsequently worked within the Rome jazz scene, with limited exposure both live and on record. Giorgio Gaslini's ground-breaking work of the late 50s, his training in ‘classical' music, and his unflagging commitment to exploration made him a personality similar to Portal and Gulda. However, his artistic successes did not close the chasm between ‘serious' music and jazz in Italy. Enrico Rava took the opposite road to Rotondo, widely performing abroad and paying dues in Buenos Aires, New York, and Paris before gaining acceptance worldwide and in his own country. He has been instrumental in the creation of an international image of Italian jazz and even of an Italian sound, opening the doors to many others. Perigeo was a ‘jazz-rock' group of the early 70s. Their recordings are still extremely popular. The reaction to their music by the jazz establishment and then their curt dismissal by the industry led to their disbanding, after which the single members—Franco D'Andrea, Claudio Fasoli, Giovanni Tommaso—produced and still produce some of the most exciting Italian jazz

Topology in full QCD at high temperature: a multicanonical approach

We investigate the topological properties of $N_f = 2+1$ QCD with physical quark masses, at temperatures around 500 MeV. With the aim of obtaining a reliable sampling of topological modes in a regime where the fluctuations of the topological charge $Q$ are very rare, we adopt a multicanonical approach, adding a bias potential to the action which enhances the probability of suppressed topological sectors. This method permits to gain up to three orders of magnitude in computational power in the explored temperature regime. Results at different lattice spacings and physical spatial volumes reveal no significant finite size effects and the presence, instead, of large finite cut-off effects, with the topological susceptibility which decreases by 3-4 orders of magnitude while moving from $a \simeq 0.06$ fm towards the continuum limit. The continuum extrapolation is in agreeement with previous lattice determinations with smaller uncertainties but obtained based on ansatzes justified by several theoretical assumptions. The parameter $b_2$, related to the fourth order coefficient in the Taylor expansion of the free energy density $f(\theta)$, has instead a smooth continuum extrapolation which is in agreement with the dilute instanton gas approximation (DIGA); moreover, a direct measurement of the relative weights of the different topological sectors gives an even stronger support to the validity of DIGA.Comment: 23 pages, 13 figure

Axion phenomenology and θ\theta-dependence from Nf=2+1N_f = 2+1 lattice QCD

We investigate the topological properties of $N_f = 2+1$ QCD with physical quark masses, both at zero and finite temperature. We adopt stout improved staggered fermions and explore a range of lattice spacings $a \sim 0.05 - 0.12$ fm. At zero temperature we estimate both finite size and finite cut-off effects, comparing our continuum extrapolated results for the topological susceptibility $\chi$ with predictions from chiral perturbation theory. At finite temperature, we explore a region going from $T_c$ up to around $4\, T_c$, where we provide continuum extrapolated results for the topological susceptibility and for the fourth moment of the topological charge distribution. While the latter converges to the dilute instanton gas prediction the former differs strongly both in the size and in the temperature dependence. This results in a shift of the axion dark matter window of almost one order of magnitude with respect to the instanton computation.Comment: 24 pages, 12 figures, 5 tables, final version published in JHE

Recent progress on QCD inputs for axion phenomenology

The properties of the QCD axion are strictly related to the dependence of strong interactions on the topological parameter theta. We present a determination of the topological properties of QCD for temperatures up to around 600 MeV, obtained by lattice QCD simulations with 2+1 flavors and physical quark masses. Numerical results for the topological susceptibility, when compared to instanton gas computations, differ both in size and in the temperature dependence. We discuss the implications of such findings for axion phenomenology, also in comparison to similar studies in the literature, and the prospects for future investigations.Comment: Invited talk at XII Quark Confinement, 29 August - 3 September, 2016, Thessaloniki, Greece, 9 pages, 6 figure

Network Security Supported by Arguments

Argumentation has been proved as a simple yet powerful approach to manage conflicts in reasoning with the purpose to find subsets of ?surviving? arguments. Our intent is to exploit such form of resolution to support the? administration of security in complex systems, e.g., in case threat countermeasures are in conflict with non-functional requirements. The proposed formalisation is able to find the required security controls and explicitly provide arguments supporting this selection. Therefore, an explanation automatically comes as part of the suggested solution, facilitating human comprehension

Semiring-based Specification Approaches for Quantitative Security

Our goal is to provide different semiring-based formal tools for the specification of security requirements: we quantitatively enhance the open-system approach, according to which a system is partially specified. Therefore, we suppose the existence of an unknown and possibly malicious agent that interacts in parallel with the system. Two specification frameworks are designed along two different (but still related) lines. First, by comparing the behaviour of a system with the expected one, or by checking if such system satisfies some security requirements: we investigate a novel approximate behavioural-equivalence for comparing processes behaviour, thus extending the Generalised Non Deducibility on Composition (GNDC) approach with scores. As a second result, we equip a modal logic with semiring values with the purpose to have a weight related to the satisfaction of a formula that specifies some requested property. Finally, we generalise the classical partial model-checking function, and we name it as quantitative partial model-checking in such a way to point out the necessary and sufficient conditions that a system has to satisfy in order to be considered as secure, with respect to a fixed security/functionality threshold-value

Radiative corrections to decay amplitudes in lattice QCD

The precision of lattice QCD computations of many quantities has reached such a precision that isospin-breaking corrections, including electromagnetism, must be included if further progress is to be made in extracting fundamental information, such as the values of Cabibbo-Kobayashi-Maskawa matrix elements, from experimental measurements. We discuss the framework for including radiative corrections in leptonic and semileptonic decays of hadrons, including the treatment of infrared divergences. We briefly review isospin breaking in leptonic decays and present the first numerical results for the ratio $\Gamma(K_{\mu2})/\Gamma(\pi_{\mu2})$ in which these corrections have been included. We also discuss the additional theoretical issues which arise when including electromagnetic corrections to semileptonic decays, such as $K_{\ell3}$ decays. The separate definition of strong isospin-breaking effects and those due to electromagnetism requires a convention. We define and advocate conventions based on hadronic schemes, in which a chosen set of hadronic quantities, hadronic masses for example, are set equal in QCD and in QCD+QED. This is in contrast with schemes which have been largely used to date, in which the renormalised $\alpha_s(\mu)$ and quark masses are set equal in QCD and in QCD+QED in some renormalisation scheme and at some scale $\mu$.Comment: Presented at the 36th Annual International Symposium on Lattice Field Theory (Lattice2018), Michigan State University, July 22nd - 28th 201