Spectral interpretation of the fast tabular technique for fixed-polarity Reed-Muller expressions

This paper presents a uniform spectral approach to the fast tabular technique for generating fixed polarity Reed–Muller expressions. Basic operations in the tabular technique are described through the discrete dyadic convolution. The presented results can be extended to various polynomial expansions of discrete functions.     

Modeling and analysis of single-phase induction machines withdynamic phasors

In this paper we present applications of the phasor-dynamic (or generalized averaging) modeling technique to single-phase induction machines. We are interested in a derivation of large and small-signal models, as this class of machines exemplifies electromechanical systems in which lack of symmetry in the magnetic field produced by the windings prevents the use of standard simplifying assumptions (such as the smoothness of the electromagnetic torque). In the process we derive equivalent circuits that do not require superposition-type assumptions common in the literature. The simplest of these circuits coincides with the standard one. We also present and quantify refinements that could be useful for evaluation of efficiency, and in estimation and control of single-phase induction machines     

Partial unit memory-based turbo codes

The performance of partial unit memory-based turbo codes (PUM-TC) with standard convolutional-based turbo codes (RSC-TC) are analysed and compared. Resulting extrinsic information transfer charts indicate that the proposed PUM-based codes have higher mutual information during iterative decoding than the equivalent RSC-TC for the same SNR, i.e. the output of the decoders provides a better approximation of the decoded bits. It is shown that the PUM-TC outperforms known equivalent RSC-TC at the error-floor region, with comparable performance in the waterfall region.     

A survey of configurable, component-based operating systems forembedded applications

Component-based software is becoming an increasingly popular technology as a means for creating complex software systems by assembling off-the-shelf building blocks. However, many of the component-based methodologies that use large components fail to address issues of size, real-time performance, power, and cost, as well as problems associated with the configuration process itself. These issues are critical for using components in embedded systems     

Real-time motion compensation, image formation and image enhancement of moving targets in ISAR and SAR using S-methodbased approach

The commonly used technique for inverse synthetic aperture radar (ISAR)/synthetic aperture radar signal analysis is a two-dimensional Fourier transform (FT), which results in an image of the target's reflectivity mapped onto a range and cross-range plane. However, in cases where the line-of-sight projections of the target's point velocities change or there is uncompensated movement within the coherent integration time, the FT produces blurred images. For target recognition applications, mainly those in military surveillance and reconnaissance operations, a blurred ISAR image has to be refocused quickly so that it can be used for real-time target identification. Two standard techniques used for improvement of blurred ISAR images are motion compensation and the use of quadratic time-frequency representations. Both are computationally intensive. The authors present an effective quadratic time-frequency representation, the S-method. This approach performs better than the Fourier transform method by drastically improving images of fast manoeuvring targets and by increasing the SNR in both low and high noise environments. These advantages are a result of the S-method's ability to automatically compensate for quadratic and all even higher-order phase terms. Thus, targets with constant acceleration will undergo full motion compensation and their point scatterers will each be localised. It should be noted that the source of the quadratic term can come not only from acceleration, but also from non-uniform rotational motion and the cosine term in wide-angle imaging. The method is also computationally simple, requiring only slight modifications to the existing FT-based algorithm. The effectiveness of the S-method is demonstrated through application to simulated and experimental data sets.     

Fast controller for a unity-power-factor PWM rectifier

This paper presents an analog implementation of a fast controller for a unity-power-factor (UPF) PWM rectifier. The best settling times of many popular controllers for this type of power converter are on the order of a few line cycles, corresponding to bandwidths under 20 Hz. The fast controller demonstrated in this paper can exercise control action at a rate comparable to the switching frequency rather than the line frequency. In order to accomplish this while maintaining unity power factor during steady-state operation, the fast controller employs a ripple-feedback cancellation scheme     

Integrated optical pickup system for axial dual focus

We propose an optical pickup that acquires data from both layers of a dual-layer digital versatile disk simultaneously. An adaptive optical element that uses liquid crystals creates two axial foci separated by a spacing of 55 mum, which is the distance between the two layers. The spacing between the foci can be varied by the adaptive element. The separation of the reflected light into TE and TM polarized light, corresponding to each of the layers, is made by dielectric gratings that are characterized by high aspect ratios. Electron-beam lithography and reactive ion etching techniques were used to produce the submicrometer structures. All fabricated elements were assembled in a pickup system, whose properties were measured.     

ADRC in output and error form: connection, equivalence, performance

In this work, we investigate two specific linear ADRC structures, namely output- and error-based. The former is considered a “standard” version of ADRC, a title obtained primarily thanks to its simplicity and effectiveness, which have spurred its adoption across multiple industries. The latter is found to be especially appealing to practitioners as its feedback error-driven structure bares similarities to conventional control solutions, like PI and PID. In this paper, we describe newly found connections between the two considered ADRC structures, which allowed us to formally establish conditions for their equivalence. Furthermore, the conducted comprehensive performance comparison between output- and error-based ADRCs has facilitated the identification of specific modules within them, which can now be conveniently used as building blocks, thus aiding the control designers in customizing ADRC-based solutions and making them most suitable for their applications.     

Structure of Naturally Coloured Cottons

Previous work on the morphology of naturally coloured green cottons has suggested that the secondary wall of the fibres consists of alternate layers of cellulose and a waxy organic substance called suberin. The work described in this paper has shown that modem varieties of green cotton do contain a large proportion of suberin. Data from fibre swelling is consistent with alternate layers of suberin and cellulose in the secondary wall. The naturally coloured fibres have a lower tenacity and work of rupture than conventional white fibres although they have an acceptable level of textile properties. The crystallinity of the coloured fibres is lower than of white cotton, but the cellulose has the Cellulose I structure normally found in cotton.