Über Derivate des Diacetonalkamins

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A meta-control algorithm for generating approximate solutions to binary integer programming problems

Binary integer program problems, which are known to be difficult to solve, have long been an important research area. We use a new approach with continualization techniques to find approximate solutions to binary integer programming problems. The algorithm constructs a sequence of approximations to a solution using a meta-control approach that has low polynomial time complexity. The algorithm is illustrated with a BIP example.     

Geometrically constrained walls

We address the effect of extreme geometry on a non-convex variational problem. The analysis is motivated by recent investigations of magnetic domain walls trapped by sharp thin necks. To capture the essential issues in the simplest possible setting, we focus on a scalar variational problem with a symmetric double well potential, whose spatial domain is a dumbell with a sharp neck. Our main results are (a) the existence of local minimizers representing geometrically constrained walls, and (b) an asymptotic characterization of the wall profile. Our analysis uses methods similar to Γ-convergence; in particular, the wall profile minimizes a certain “reduced problem” – the limit of the original problem, suitably rescaled near the neck. The structure of the wall depends critically on the choice of scaling, specifically the ratio between length and width of the neck.     

Synthesis of benzimidazoles from 1,1-dibromoethenes

A mild and efficient method for the preparation of substituted benzimidazoles from 1,1-dibromoethenes and o-diaminobenzenes is described. The reaction employs DABCO as the base and NMP as the solvent. A variety of substitutions on both 2-aryl-1,1-dibromoethenes and o-diaminobenzenes are tolerated. This new procedure is carried out under mildly basic conditions, which may provide a complementary route to the existing preparations of benzimidazoles.     

Über die Sextupel von geraden Linien,welche von sämmtlichen Punkten einer cubischen Fläche als sechs Tangenten eines Kegelschnitts gesehen werden

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Über einige Derivate des Diacetonalkamins

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Phase control of a nano-structured light-harvesting architecture

Efficient solar-energy harvesting is fundamental to solar cell technology. Much research effort has been devoted to the construction of new light-harvesting structures, including the use of semiconductor quantum dots (QDs), to improve the widespread availability of solar cells. In this research, a new light-harvesting architecture is developed, which utilizes quantum dots. The proposed architecture is composed of quantum phase-locked loops (QPLLs) to enhance the harvesting efficiency of QD solar cells by utilizing feedback control principles. The purpose of QPLL is to synchronize the phases of monochromatic light harvested by the antenna systems. This paper addresses deterministic modeling and control formulation of the QPLL within our conceptual framework. The QPLL consists of a tracking controller and a proportional–integral (PI) regulator. The QPLLs are simulated with external fluctuations to evaluate the performance of the controllers. Simulation results show that the tracking controller achieves robust and satisfactory performance. The PI regulator is more sensitive to external fluctuations and the nominal operating point. Our results demonstrate the possibility of improving light-harvesting efficiency by utilizing feedback control principles.     

Die Darstellung von Aminoalkoholen aus ungesättigten Methylketonen

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