A Tabu Search Heuristic for a Full-Load, Multi-Terminal, Vehicle Scheduling Problem with Backhauling and Time Windows

The problem considered is the full-load pickup and delivery problem with time windows (PDPTW), and heterogeneous products and vehicles, where the assignment of pickup points to requests is not predetermined. Elements associated with tabu search, such as diversification by reversion to junctions and the use of soft aspiration criteria, are embedded into our tabu search implementation. This metaheuristic is evaluated using random instances and selected data from a construction company in the U.K. The obtained results are compared against lower bounds from LP relaxation and also solutions from an existing multi-level heuristic.     

New determination method of the neutron diffraction system resolution at the Algerian Es-Salam research reactor

The aim of this article is to determine the resolution of the neutron diffraction system (NDS) installed around the Algerian Es Salam research reactor. By using a new method based on neutron radiography technique we have measured the beam divergence at the exit of Soller Collimator (α₂) and hence determine effective collimations. The determination of the adequate resolution of our NDS is performed on experimental results obtained from neutron diffraction patterns for different collimation divergences (α₂) and (α₃) values obtained from several apertures sizes (S ₂) and (S ₃).     

Uncertainty principles for the weinstein transform

The Weinstein transform satisfies some uncertainty principles similar to the Euclidean Fourier transform. A generalization and a variant of Cowling-Price theorem, Miyachi’s theorem, Beurling’s theorem, and Donoho-Stark’s uncertainty principle are obtained for the Weinstein transform.     

Asymptotic analysis of equilibrium states for rotating turbulent flows

The equilibrium states of homogeneous turbulence simultaneously subjected to a mean velocity gradient and a rotation are examined by using asymptotic analysis. The present work is concerned with the asymptotic behavior of quantities such as the turbulent kinetic energy and its dissipation rate associated with the fixed point (/kS)=0, whereS is the shear rate. The classical form of the model transport equation for (Hanjalic and Launder, 1972) is used. The present analysis shows that, asymptotically, the turbulent kinetic energy (a) undergoes a power-law decay with time for (P/)<1, (b) is independent of time for (P/)=1, (c) undergoes a power-law growth with time for 1<(P/)<(C ₂–1), and (d) is represented by an exponential law versus time for (P/)=(C ₂–1)/(C ₁–1) and (/kS)>0 whereP is the production rate. For the commonly used second-order models the equilibrium solutions forP/,II, andIII (whereII andIII are respectively the second and third invariants of the anisotropy tensor) depend on the rotation number when (P/kS)=(/kS)=0. The variation of (P/kS) andII versusR given by the second-order model of Yakhot and Orzag are compared with results of Rapid Distortion Theory corrected for decay (Townsend, 1970).     

Numerical investigation of incompressible fluid flow and heat transfer around a rotating circular cylinder

The heat transfer and air flow around an unconfined heated rotating circular cylinder is investigated numerically for varying rotation rates (α = 0–6) in the Reynolds number range of 20–200. The numerical calculations are carried out by using a finite volume method based commercial computational fluid dynamics solver FLUENT. The successive changes in the flow pattern are studied as a function of the rotation rate. Suppression of vortex shedding occurs as the rotation rate increases (α > 2). A second kind of instability appears for higher rotation speed where a series of counter-clockwise vortices is shed in the upper shear layer. The rotation attenuates the secondary instability and increases the critical Reynolds number for the appearance of this instability. Besides, time-averaged (lift and drag coefficients and Nusselt number) results are obtained and compared with the literature data. A good agreement has been obtained for both the local and averaged values.     

Universal soliton pattern formations in passively mode-locked fiber lasers

We investigate multiple-soliton pattern formations in a figure-of-eight passively mode-locked fiber laser. Operation in the anomalous dispersion regime with a double-clad fiber amplifier allows generation of up to several hundreds of solitons per round trip. We report the observation of remarkable soliton distributions: soliton gas, soliton liquid, soliton polycrystal, and soliton crystal, thus indicating the universality of such complexes.