Wrocław University of Technology

About: Wrocław University of Technology is a education organization based out in Wrocław, Poland. It is known for research contribution in the topics: Laser & Fuzzy logic. The organization has 13115 authors who have published 31279 publications receiving 338694 citations.

Electronic structure and magneto-optics of self-assembled quantum dots

Abstract: The electronic structure of lens-shaped self-assembled quantum dots is studied as a function of the dot size, the confining potential, and the magnetic field. The parabolic confining potential and its corresponding energy spectrum are shown to be an excellent approximation. The magnetoexciton spectrum is calculated and compared with recent experiments. \textcopyright{} 1996 The American Physical Society.

Cost-sensitive decision tree ensembles for effective imbalanced classification

Abstract: Real-life datasets are often imbalanced, that is, there are significantly more training samples available for some classes than for others, and consequently the conventional aim of reducing overall classification accuracy is not appropriate when dealing with such problems. Various approaches have been introduced in the literature to deal with imbalanced datasets, and are typically based on oversampling, undersampling or cost-sensitive classification. In this paper, we introduce an effective ensemble of cost-sensitive decision trees for imbalanced classification. Base classifiers are constructed according to a given cost matrix, but are trained on random feature subspaces to ensure sufficient diversity of the ensemble members. We employ an evolutionary algorithm for simultaneous classifier selection and assignment of committee member weights for the fusion process. Our proposed algorithm is evaluated on a variety of benchmark datasets, and is confirmed to lead to improved recognition of the minority class, to be capable of outperforming other state-of-the-art algorithms, and hence to represent a useful and effective approach for dealing with imbalanced datasets.

Estimates of Heat Kernel of Fractional Laplacian Perturbed by Gradient Operators

Abstract: We construct a continuous transition density of the semigroup generated by $${\Delta^{\alpha/2} + b(x)\cdot abla}$$ for $${1 < \alpha < 2, d\ge 1}$$ and b in the Kato class $${\mathcal{K}_d^{\alpha-1}}$$ on $${\mathbb{R}^d}$$ . For small time the transition density is comparable with that of the fractional Laplacian.