Decibell: A novel approach to the ORM software in Java

DeciBell is an open source and free tool developed to tackle in a uniform and structured way the problem of Java and SQL cooperation (available at http://github.com/hampos/DeciBell). In DeciBell, Java classes are related to relational database entities automatically and in a transparent way as far as the background operations are concerned. So, on one hand, non-expert users can work on Java code exclusively while expert ones are able to focus on more algorithmic aspects of the problem they try to solve rather than be wasted with trivial database management issues. In contrast to the existing O.R.M. programs, DeciBell does not require any configuration files or composite query structures, but only a proper annotation of certain fields of the classes. This annotation is carried out by means of the Java Annotations which is a modern trend in Java programming. Among its supported facilities, DeciBell supports primary keys (single and multiple), foreign keys, constraints, one-to-one, one- to-many, and many-to-many relations and all these using pure Java predicates and no SQL or other Query Languages

Off-equilibrium scaling behaviors across first-order transitions

We study off-equilibrium behaviors at first-order transitions (FOTs) driven by a time dependence of the temperature across the transition point Tc, such as the linear behavior T(t)/Tc = 1 - t/ts where ts is a time scale. In particular, we investigate the possibility of nontrivial off-equilibrium scaling behaviors in the regime of slow changes, corresponding to large ts, analogous to those arising at continuous transitions, which lead to the so-called Kibble-Zurek mechanism. We consider the 2D Potts models which provide an ideal theoretical laboratory to investigate issues related to FOTs driven by thermal fluctuations. We put forward general ansatzes for off-equilibrium scaling behaviors around the time t=0 corresponding to Tc. Then we present numerical results for the q=10 and q=20 Potts models. We show that phenomena analogous to the Kibble-Zurek off-equilibrium scaling emerge also at FOTs with relaxational dynamics, when appropriate boundary conditions are considered, such as mixed boundary conditions favoring different phases at the opposite sides of the system, which enforce an interface in the system.Comment: 11 pages, some more ref

Renormalization of Supersymmetric QCD on the Lattice

We perform a pilot study of the perturbative renormalization of a Supersymmetric gauge theory with matter fields on the lattice. As a specific example, we consider Supersymmetric ${\cal N}{=}1$ QCD (SQCD). We study the self-energies of all particles which appear in this theory, as well as the renormalization of the coupling constant. To this end we compute, perturbatively to one-loop, the relevant two-point and three-point Green's functions using both dimensional and lattice regularizations. Our lattice formulation involves the Wilson discretization for the gluino and quark fields; for gluons we employ the Wilson gauge action; for scalar fields (squarks) we use naive discretization. The gauge group that we consider is $SU(N_c)$, while the number of colors, $N_c$, the number of flavors, $N_f$, and the gauge parameter, $\alpha$, are left unspecified. We obtain analytic expressions for the renormalization factors of the coupling constant ($Z_g$) and of the quark ($Z_\psi$), gluon ($Z_u$), gluino ($Z_\lambda$), squark ($Z_{A_\pm}$), and ghost ($Z_c$) fields on the lattice. We also compute the critical values of the gluino, quark and squark masses. Finally, we address the mixing which occurs among squark degrees of freedom beyond tree level: we calculate the corresponding mixing matrix which is necessary in order to disentangle the components of the squark field via an additional finite renormalization.Comment: 8 pages, 6 figures, Lattice 201

Stabilising Model Predictive Control for Discrete-time Fractional-order Systems

In this paper we propose a model predictive control scheme for constrained fractional-order discrete-time systems. We prove that all constraints are satisfied at all time instants and we prescribe conditions for the origin to be an asymptotically stable equilibrium point of the controlled system. We employ a finite-dimensional approximation of the original infinite-dimensional dynamics for which the approximation error can become arbitrarily small. We use the approximate dynamics to design a tube-based model predictive controller which steers the system state to a neighbourhood of the origin of controlled size. We finally derive stability conditions for the MPC-controlled system which are computationally tractable and account for the infinite dimensional nature of the fractional-order system and the state and input constraints. The proposed control methodology guarantees asymptotic stability of the discrete-time fractional order system, satisfaction of the prescribed constraints and recursive feasibility