Cavitation instabilities in turbo-machinery such as cavitation surge and rotating cavitation are usually explained by the quasi-steady characteristics of cavitation, mass flow gain factor and cavitation compliance. However, there are certain cases when it is required to take account of unsteady characteristics. As an example of such cases, cavitation surge in industrial centrifugal pump caused ...

Aims. The effect of frequency-dependent AGN core positions (“core-shifts”) on radio Very Long Baseline Interferometry (VLBI) global astrometry measurements is investigated. Methods. The basic equations relating to VLBI astrometry are reviewed, including the effects of source structure. A power-law representation of core-shifts, based on both observations and theoretical considerations of jet co...

We propose methods to track natural variations in the characteristics of the vocal-tract system from speech signals. We are especially interested in the cases where these characteristics vary over time, as happens in dynamic sounds such as consonant-vowel transitions. We show that the selection of appropriate analysis segments is crucial in these methods, and we propose a selection based on est...

On 18 November 1993, we observed the QSO 1150+812 and the BL Lac object 1803+784, nearly 15 apart on the sky, with a VLBI array, simultaneously recording at 8.4 and 2.3 GHz. Using difference astrometry techniques, we determined the coordinates of 1803+784 relative to those of 1150+812 to be ∆α = 6 7 33. 18469± 0. 00020 ∆δ = −2 30′ 25. 13557± 0. 00075 These standard errors contain estimated cont...

where • Ai is the amplitude of the i th useful signal; • τi is the code phase delay introduced by the transmission channel; • ci(t − τi) is the spreading sequence which is given by the product of several terms and it is assumed to take value in the set {−1, 1}; • di(t − τi) is the navigation message, Binary Phase Shift Keying (BPSK) modulated, containing satellite data, each binary unit is call...

A new group-delay based spectral domain is explored for representation of speech signals and for extraction of robust features. The spectrum is computed using the group-delay functions defined on the autocorrelation of a short segment of speech. The features derived from this spectrum are easy to compute and are robust to the background noise. The invariance of the spectral shape to noise in th...

An optimized fundamental frequency (F0) trajectory extraction method, which alleviates systematic F0 glitches at vowelnasal boundaries and in the vicinity of consonants, is introduced. The proposed method employes minimum phase group delay compensation for apparent F0 modulations due to variations in their corresponding vocal tract transfer functions. This method can also be considered as an im...

S U M M A R Y I calculate three-dimensional (3-D) sensitivity kernels of multimode surface wave observables in radially anisotropic earth media for perturbations in wave speeds αH, αV, βH, βV and η as well as in density ρ. The 3-D phase-delay and amplitude kernels are formulated based upon Born approximation in the framework of surface wave mode summation, fully accounting for cross-branch mode...

Beam-steering techniques are required to fully exploit terahertz imaging systems. We propose and model a device employing artificial dielectric techniques to provide a variable phase-control medium. The device consists of two interlocking artificial dielectric surfaces that are initially aligned parallel to each other. By mechanically introducing a relative tilt between the plates, a transmitte...

A compact ultra-wideband microstrip-fed planar monopole antenna with dual band-notch characteristic is presented. Dual notched frequency bands are achieved by embedding an M-slot in the radiating patch and a W-slot in the ground beneath the feeding line. And the characteristics of the dual band-notched can be controlled by adjusting the length and position of the corresponding slot. Experimenta...