This study was aimed to examine geographical stability of generation frequency norms for semantic categories in Russian language. Participants from three different regions of Russia carried out a standard procedure for generating exemplars of 45 semantic categories. For each exemplar, overall generation frequency was calculated in each of three regions. Correlations of generation frequency data...

Diode lasers are becoming increasingly important in length metrology. We demonstrate construction of a simple single-frequency diode laser 632,8 nm, used as a frequency standard in the laser interferometers. We present two different systems applied for frequency stabilization of diode laser . For diode laser used as the secondary standard, the system stabilizes diode temperature, the frequency ...

Abstract. We compare inviscid stability conditions obtained by Lewicka for large-amplitude shock wave patterns with “slow eigenvalue”, or low-frequency, stability conditions obtained by Lin and Schecter through a vanishing viscosity analysis of the Dafermos regularization. Under the structural condition that scattering coefficients for each component wave are positive, we show that BV and L inv...

Digital filters for recursively computing the discrete Fourier transform (DFT) and estimating the frequency spectrum of sampled signals are examined, with an emphasis on magnitude-response and numerical stability. In this tutorial-style treatment, existing recursive techniques are reviewed, explained and compared within a coherent framework; some fresh insights are provided and new enhancements...

Background and Objectives: Virtual inertia control, as a component of a virtual synchronous generator, is used for the implementation of synchronous generator behaviour in microgrids. In microgrids that include high-capacity distributed generation resources, in addition to virtual inertia, virtual damping can also lead to improvement of frequency stability of the microgrid. The purpose of the c...

This paper deals with stability of a certain class of fractional order linear and nonlinear systems. The stability is investigated in the time domain and the frequency domain. The general stability conditions and several illustrative examples are presented as well.

Distributed generations (DG’s), based on both synchronous generators (SG’s) and fast inverters, are incorporated to improve power quality and reliability of power grids. These DG’s, however, may cause voltage and frequency stability issues due to weakness in power distribution networks. Weakness not only means significant ratios between resistance and reactance components in impedances (lossy),...

We present conditions, some necessary and some suucient, valid under weak assumptions , for robust stability and uniform robust stability of uncertain linear time-invariant systems with linear time-invariant uncertainties that are block-diagonal, with known frequency-dependent norm bounds on the diagonal blocks. Small-theorems with frequency-independent uncertainty bounds are recovered as speci...

In this paper we introduce new bounds for robust stability analysis with real parameter uncertainty. The approach is based on an absolute stability criterion that excludes the Nyquist plot from a paraboloidal region containing the point -1 +j0. Transformation of this criterion to the case of norm-bounded uncertainty leads to a stability criterion in terms of the octomorphic, or figure-eight sha...