The soft γ–ray source GX 1+4 has been regularly monitored by the SIGMA telescope on board GRANAT since 1990. The accumulated data provides both period and spectral information on this source in the 35–150 keV range. The SIGMA telescope also allows a determination of a pulsed fraction. We report here on the last six years of the SIGMA data on GX 1+4. The general spin down trend is confirmed and ...

We compare the delta lenses, also known as d-lenses, of Diskin et al. with the c-lenses, known to be equivalent to opfibrations, already studied by the authors. Contrary to expectation a c-lens is a d-lens but not conversely. This result is surprising because d-lenses appear to provide the same information as c-lenses, and some more besides, suggesting that the implication would be the reverse ...

The goal of this tutorial is to provide a compact yet comprehensive introduction to service design in the wind energy business. The tutorial aims at giving the participants the theoretical and practical background in design principles considering the spedific domains the services are designed for. During the life demonstration it is shown how different services can be integrated transparently i...

Classical delta-sigma modulation gains resolution through temporal oversampling by using a high-speed, low-resolution quantizer and shaping the resulting quantization errors out of the signal band. Likewise, spatial delta-sigma modulation is often used in image halftoning to create high-visual-quality binary images. We consider combining spatial and temporal delta-sigma modulation to reduce tem...

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A novel application and generalization of sigma–delta ( ) modulation has emerged in three-phase power-electronic converters. A conventional modulator with scalar signals and binary quantizer is generalized to a modulator with vector signals and a hexagonal quantizer. Indeed, power-electronic switching states may be thought of as determining the quantizer outputs. The output spectrum is a key pe...

A review on the current state of mode physics in classical pulsators is presented. Two, currently in use, time-dependent convection models are compared and their applications on mode stability are discussed with particular emphasis on the location of the Delta Scuti instability strip.

Six Sigma provides an effective mechanism to focus on customer requirements, through improvement of process quality. In the Global Engineering Development Center of Tata Consultancy Services (TCS – GEDC) at Chennai, India, Six Sigma projects are being carried out with the objective of improving on time delivery, product quality and in-process quality. This paper describes the application of the...