[en] Methods: of computational physics developed at JINR for investigation of models of complex physical processes in different fields of theoretical physics are considered. A general mathematical formulation of equations for the models under study is given, numerical methods are described, and information on developed program packages is presented. Particular models of physical processes are discussed. Results: of their numerical study are demonstrated.

[en] In this study, the dynamic analysis of nuclear power reactor components are investigated

[en] Short communication

No abstract available

[en] High-precision methods are developed to evaluate eigenvalues for all states |m,N right-angle of the x^2m anharmonic oscillators with m from 2 to 6, for all values of the anharmonicity parameter. There are three basic steps: rescaling to introduce a length scale natural to the problem; use of fifth-order JWKB to generate an accurate starting estimate of the rescaled energy; and shifted (resolvent-based) Lanczos algorithm to sharpen the initial JWKB estimate. JWKB itself gives 33-figure accuracy for N greater than 1500 (for m=2) to 3500 (for m=6). With the JWKB starting energy, the shifted Lanczos algorithm converges to 33 figures in 3 iterations or less for all states. These methods are used in a study of the systematics of anharmonic-oscillator spectra and of the physical effects of the rescaling transformation. copyright 1999 Academic Press, Inc

[en] A Comment on the Letter by Josuea de Carvalho and Carmen P.C. Prado, Phys.Rev.Lett. 84, 4006 (2000). The authors of the Letter offer a Reply

[en] The aim of this paper is to present the results of the analysis of a Darrieus-type cross flow water turbine in bare and shrouded configurations. Numerical results are compared to experimental data and differences found in values are also highlighted. The benefit of the introduction of a channelling device, which generates an efficiency increment factor varying from 2 to 5, depending on the configuration, is discussed.

[en] Highlights: • CFD and CSM codes are coupled. • Validation on Vattenfall Rod Vibration Experiment are performed. • Vibrations from an external load are modelled. • Comparative analyses have been performed.

[en] Investigating the dynamics of a network of oscillatory systems is a timely and urgent topic. Phase synchronization has proven paradigmatic to study emergent collective behavior within a network. Defining the phase dynamics, however, is not a trivial task. The literature provides an arsenal of solutions, but results are scattered and their formulation is far from standardized. Here, we present, in a unified language, a catalogue of popular techniques for deriving the phase dynamics of coupled oscillators. Traditionally, approaches to phase reduction address the (weakly) perturbed dynamics of an oscillator. They fall into three classes. (i) Many phase reduction techniques start off with a Hopf normal form description, thereby providing mathematical rigor. There, the caveat is to first derive the proper normal form. We explicate several ways to do that, both analytically and (semi-)numerically. (ii) Other analytic techniques capitalize on time scale separation and/or averaging over cyclic variables. While appealing for their more intuitive implementation, they often lack accuracy. (iii) Direct numerical approaches help to identify oscillatory behavior but may limit an overarching view how the reduced phase dynamics depends on model parameters. After illustrating and reviewing the necessary mathematical details for single oscillators, we turn to networks of coupled oscillators as the central issue of this report. We show in detail how the concepts of phase reduction for single oscillators can be extended and applied to oscillator networks. Again, we distinguish between numerical and analytic phase reduction techniques. As the latter dwell on a network normal form, we also discuss associated reduction methods. To illustrate benefits and pitfalls of the different phase reduction techniques, we apply them point-by-point to two classic examples: networks of Brusselators and a more elaborate model of coupled Wilson–Cowan oscillators. The reduction of complex oscillatory systems is crucial for numerical analyses but more so for analytical estimates and model prediction. The most common reduction is towards phase oscillator networks that have proven successful in describing not only the transition between incoherence and global synchronization, but also in predicting the existence of less trivial network states. Many of these predictions have been confirmed in experiments. As we show, however, the phase dynamics depends to large extent on the employed phase reduction technique. In view of current and future trends, we also provide an overview of various methods for augmented phase reduction as well as for phase–amplitude reduction. Weindicate how these techniques can be extended to oscillator networks and, hence, may allow for an improved derivation of the phase dynamics of coupled oscillators.

[en] It is an open question if there are leakage-free entangling Fibonacci braiding gates. In this article, we give a construction of a large family of leakage-free braiding gates which are then proved to be non-entangling. We also conducted brute-force numerical searches for braids with a word-length up to seven and found no leakage-free entangling gates. These suggest the negative for the conjecture. On the other hand, we provide a much simpler protocol to generate approximately leakage-free entangling Fibonacci braiding gates than existing algorithms in the literature. (paper)