On the Littlewood-Richardson rule for almost skew-shapes

We describe combinatorially the coefficients occurring in the irreducible decomposition of the Weyl module associated with an almost skew-shape belonging to the family .

The proof uses the fundamental exact sequence for almost skew-shapes to initiate an inductive procedure which ultimately reduces to the classical Littlewood-Richardson rule for skew partitions.

     

Integral transport theory for test particles in the presence of a time-dependent conservative force

Summary An integral space-independent transport theory for test particles diffusing by collision against the field particles of an unbounded homogeneous host medium, and in the presence of a time-dependent external conservative force, is developed in the paper. Both the cases of a general and of a separable scattering-creation kernel are considered. Functional and constructive features of the theory are also discussed with particular regard to these case of/v-cross sections. Curves, representing the distribution function of the test particles considered and evaluated according to an appropriate specialization of the physical inputs, are shown.

---

Sommario In questo lavoro viene formulata una teoria integrale del trasporto, spazialmente uniforme, per particelle cavia, che diffondono per collisione contro le particelle campo di un mezzo omogeneo infinito, ed in presenza di una forza conservativa esterna dipendente dal tempo. Vengono considerati sia il caso di un nucleo di scattering-creazione di tipo generale che il caso di nucleo separabile. Vengono anche discusse proprietà funzionali e costruttive della teoria proposta, con particolare riguardo al caso di sezioni d'urto del tipo 1/v. Sono riportate curve rappresentanti la funzione di distribuzione delle particelle cavia considerate e calculate per una opportuna specifica dei parametri fisici di interesse.

---

---

On leave of absence from Abteilung für Mathematische Physik, Universität Ulm, 7900 Ulm, BRD, in the frame of the Italian National Research Council's (C. N. R.), Visiting Professor Program.     

Improved formulation,branch-and-cut and tabu search heuristic for single loop material flow system design

The single loop material flow system design is a combinatorial optimization problem, arising in material handling system design, which amounts to designing an unidirectional loop flow pattern as well as to locate pickup and delivery stations. The objective is to minimize the time required to carry out all material flow movements between cells. In this paper, we develop valid inequalities for a previously proposed formulation. The valid inequalities are then embedded into a branch-and-cut framework which is shown to solve much larger instances to optimality than those reported in the literature. A tailored tabu search heuristic is also illustrated and computationally assessed.     

ITERATIVE ILU PRECONDITIONERS FOR LINEAR SYSTEMS AND EIGENPROBLEMS

Iterative ILU factorizations are constructed,analyzed and applied as preconditioners to solve both linear systems and eigenproblems.The computational kernels of these novel Iterative ILU factorizations are sparse matrix-matrix multiplications,which are easy and efficient to implement on both serial and parallel computer architectures and can take full advantage of existing matrix-matrix multiplication codes.We also introduce level-based and threshold-based algorithms in order to enhance the accuracy of the proposed Iterative ILU factorizations.The results of several numerical experiments illustrate the efficiency of the proposed preconditioners to solve both linear systems and eigenvalue problems.     

Density profiles of charged test particles diffusing in a slab of finite thickness

Summary In the paper a detailed study of the diffusion of charged test particles in the interior of a slab of finite thickness is carried out upon a suitable functional formulation of the stationary Boltzmann equation. Either the boundary effects and the action of an external conservative force are accounted for. Numerical results for the shape function and the total density of the test particles considered are at last reported for an appropriate specialization of the relevant physical parameters.

---

Sommario Nel presente lavoro viene sviluppato-tramite una opportuna formulazione funzionale dell'equazione di Boltzmann nel caso stazionario — uno studio dettagliato della diffusione di particelle cavia cariche all'interno di una lastra piana di spessore finito. Sia gli effetti del contorno che l'azione esercitata da una forza conservativa esterna sono portati in conto. In corrispondenza di una appropriata specifica dei parametri fisici di interesse vengono infine illustrati i risultati numerici ottenuti per la funzione di forma e per la densità totale delle particelle cavia considerate.

---

---

Work performed during the preparation of the thesis for the degree of Dottore in Nuclear Engineering.     

Third-Order Phase Transition: Random Matrices and Screened Coulomb Gas with Hard Walls

Journal of Statistical Physics - Consider the free energy of a d-dimensional gas in canonical equilibrium under pairwise repulsive interaction and global confinement, in presence of a volume...     

Drawing parameters optimization for birefringence reduction in optical fibers

The impact of the drawing process on the stress-induced birefringence in optical fiber is experimentally analyzed. By means of the photoelastic tomographic technique, residual internal stresses are measured in fiber samples drawn under different conditions of temperature, drawing tension and speed. From measured residual stress distributions, the stress-induced birefringence and beatlength are mathematically derived and compared, proving that an effective birefringence reduction can be obtained by a proper choice of drawing parameters.     

Effect of thermal treatment under high pressure on the quality of a meat sauce

Abstract

It is known that pressure alone is not able to make shelf-stable any food stored in room conditions. Acid products are normally spoiled by enzymes, and low acid products are spoiled even by spore-forming micro-organisms. To overcome the problem the role of heat in the process has been re-evaluated and the possibility of destroying at the same time spores and enzymes has been found. This work compares the effect of sterilisation by High Pressure Processing (HPP) with one of the conventional retort processing techniques. Two batches of meat sauce were kept in room conditions over a year and their quality was evaluated periodically during the shelf life simulation. The physico-chemical characteristics of the retorted ones showed a progressive appearance of the typical thermal damage. The High Pressure Sterilised samples on the contrary showed limited damage, related to the unavoidable pre-heating. Their quality markers were constant over the shelf life evaluated period.     

Non-simple blow-up solutions for the Neumann two-dimensional sinh-Gordon equation

For the Neumann sinh-Gordon equation on the unit ball

Realistic one-particle density matrix and single-particle description of nuclei

Starting from the experimental data on elastic electron scattering, realistic one-particle density matrices for ¹⁶O and ⁴⁰Ca are obtained, both with fractional occupation numbers and full occupation of the first A natural orbitals. A phenomenological single-nucleon Hamiltonian is then constructed and diagonalized. The deduced single-particle energies are compared with those obtained in the Hartree-Fock approximation. The consistency of all experimental data concerning the ground state is checked with the aid of a sum rule for the total binding energy involving only the one-particle density matrix and the hole energies.