Data mining for recommender systems has gained a lot of interest in the recent years. ”ECML/PKDD Discovery Challenge 2011” was organized to improve current recommender system of the VideoLectures.Net website. Two main tasks of the challenge simulate new-user and new-item recommendation (cold-start mode) and clickstream based recommendation (normal mode). This paper provides detailed description...

Various applications of quantum algebraic techniques in nuclear structure physics, such as the suq(2) rotator model and its extensions, the use of deformed bosons in the description of pairing correlations, and the construction of deformed exactly soluble models (Interacting Boson Model, Moszkowski model) are briefly reviewed. Emphasis is put in the study of the symmetries of the anisotropic qu...

The deformed Virasoro algebra plays a similar role for deformed conformal fields as the Virasoro algebra in the usual string and conformal field theories. We show that there exists a physical theory, the discrete-time QFT, in which framework the deformations of (super)Virasoro algebra constructed earlier on an abstract mathematical background emerge. Specifically, the deformed Virasoro and supe...

the purpose of this paper is to studying nonlinear k-ε turbulence models and its advantages in internal combustion engines, since the standard k-ε model is incapable of representing the anisotropy of turbulence intensities and fails to express the reynolds stresses adequately in rotating flows. therefore, this model is not only incapable of expressing the anisotropy of turbulence in an engine c...

Given function values on a domain D0 , possibly with noise, we examine the possibility of extending the function to a larger domain D,D0 ⊂ D. In addition to smoothness at the boundary of D0 , the extension to D \ D0 should also inherit behavioral trends of the function on D0 , such as growth and decay or even oscillations. The approach chosen here is based upon the framework of linear models, u...

It is a well-known theorem in linear models that the idempotency of a matrix is a sufficient and necessary condition for a quadratic form in normal variates to have a chi-square distribution, but its proofs in the early literature were incorrect or incomplete. Driscoll (1999) provided an improved proof, and this article presents a simple proof. More importantly, we establish and prove a general...