Design problem solved by optimal control theory

In this paper we present an application to airfoil design of an optimum design method based on optimal control theory. The method used here transforms the design problem by way of a change of variable into an optimal control problem for a distributed system with Neumann boundary control. This results in a set of variational inequalities which is solved by adding a penalty term to the differential equation. This is in turn solved by a finite element method.     

Motion by mean curvature by scaling a nonlocal equation: Convergence at all times in the two-dimensional case

The convergence to a motion by mean curvature by diffusively scaling a nonlocal evolution equation, describing the macroscopic behavior of a ferromagnetic spin system with Kac interaction and Glauber dynamics has recently been proved. The convergence is proven up to the times when the motion by curvature is regular. Here we show the convergence at all times in the two-dimensional case. Since, in this case, the only singularity is the shrinking to a point of a closed curve, we verify that the curve actually disappears past the singularity.     

Mössbauer study of elemental substitution in Nd18Fe76B6 alloy

Fe-rich Nd-Fe-B permanent magnetic materials are of great technological interest because of their superior magnetic properties such as coercivity and large energy products. These properties can be further enhanced by the substitution of Nd or Fe. We are presenting the results of atomic replacement of iron by Ga, Dy, Nb and Si, in the base material N₁₈Fe_{7 6}B₆, obtained by Mössbauer spectroscopy. It is observed that the net magnetization decreases for all compositions with the substitution of these elements.     

Cation distribution in Ni-substituted Mn-ferrites by Mössbauer technique

The neutron spectra of one outer (#10) and two inner (#2 and #3) sites of the Dalhousie University SLOWPOKE-2 reactor (DUSR) have been calibrated for the k ₀-based neutron activation analysis (k ₀-NAA). The parameters determined include the cadmium ratio (R _Cd), epithermal neutron flux shape factor (), subcadmium-to-epithermal neutron flux ratio (f), thermal-to-fast neutron flux ratio (f _F), modified spectral index r()(T_n/T₀)^1/2, Westcott g _Lu(T _n)-factor, and absolute neutron temperature (T _n). The a-values of -0.0098±0.0045 and -0.0425±0.0047 and -0.0422±0.0053 and f-values of 57.1±2.2 and 18.8±0.4 and 18.9±0.4 were obtained for the sites #10, #2 and #3, respectively. The modified spectral index (MSI), g _Lu(T _n)-factor, and T _n have been determined for the handling of non 1/v (n,) reactions. The accuracy of the method was evaluated by analyzing reference materials.