A NEW FINITE ELEMENT APPROXIMATION OF A STATE-CONSTRAINED OPTIMAL CONTROL PROBLEM

In this paper, we study numerical methods for an optimal control problem with pointwise state constraints. The traditional approaches often need to deal with the deltasingularity in the dual equation, which causes many difficulties in its theoretical analysis and numerical approximation. In our new approach we reformulate the state-constrained optimal control as a constrained minimization problems only involving the state, whose optimality condition is characterized by a fourth order elliptic variational inequality. Then direct numerical algorithms （nonconforming finite element approximation） are proposed for the inequality, and error estimates of the finite element approximation are derived. Numerical experiments illustrate the effectiveness of the new approach.     

Diffuse reflectance determination of Malachite Green using polyurethane foam as solid support and sodium dodecylsulfate as counter ion

This paper reports the use of polyurethane foam (PUF) as solid support for diffuse reflectance spectrophotometric determination of Malachite Green (MG), a well known cationic dye used as biocide in the aquaculture industry, using sodium dodecylsulfate (SDS) as a counter ion. The method was based on the formation of an ionic-pair between the dye and the anionic surfactant SDS, which was sorbed onto PUF surface, where the diffuse reflectance was measured at 635 nm. Several parameters that could affect the performance of the system were evaluated. As expected, the SDS concentration presented strong influence on the analytical signal because the PUF was able to retain only the ionic-pair. The pH influenced the analytical signal, which was more intense in the acidic/neutral range, while the ionic strength only influenced the kinetic of the MG (as MG-SDS ionic-pair) sorption. The methodology was employed in the determination of MG in river waters and a recovery test was performed to test the accuracy of the procedure. Recovery percentages between 98.7 and 107% were observed when 60 or 80 μg L(-1) of MG were added to the samples.     

Manual cleaving of anodically bonded silicon/glass wafers

Packaging technologies are a great issue in MEMS/NEMS fabrication. Moreover, silicon to glass anodic bonding is a common boding technique for MEMS/NEMS packaging. Hence, dicing the wafer into individual devices is a real challenge for fragile structures. This investigation shows an extension of the manual cleaving dicing for bonded silicon/glass wafers. The designed structure with no coincident anchors between silicon and glass avoids that the fracture expands toward the interior of the device during manual cleaving. Highest stresses are localized on the anchors, causing the fracture in those points. This method was experimentally tested to dice anodically bonded silicon-glass wafers.     

Local observations of phase singularities in optical fields in waveguide structures

A linear copolymer made of two reciprocally attracting N-monomer blocks collapses to a compact phase through a novel transition, whose exponents are determined with extensive Monte Carlo simulations in two and three dimensions. In the former case, an identification with the statistical geometry of suitable percolation paths allows one to predict that the number of contacts between the blocks grows like N9/16. In the compact phase the blocks are mixed and, in two dimensions, also zipped, in such a way to form a spiral, double chain structure.     

Influencing the angular emission of a single molecule

We present the first experimental proof for the influence of a nearby nanosized metal object on the angular photon emission by a single molecule. Using a novel angular sensitive detection scheme, we directly quantify the redirection of angular emission for different molecular dipole orientations as an object is scanned laterally over the molecule at different heights. An excellent agreement between experiments and 2D-numerical simulations is found for molecules oriented perpendicular to the sample, whereas, for parallel orientations, the observed behavior contradicts the calculated behavior.