A CMOS adaptive RF front-end receiver for wireless applications

The performance of signal-processing algorithms implemented in hardware depends on the efficiency of datapath, memory speed and address computation. Pattern of data access in signal-processing applications is complex and it is desirable to execute the innermost loop of a kernel in a single-clock cycle. This necessitates the generation of typically three addresses per clock: two addresses for data sample/coefficient and one for the storage of processed data. Most of the Reconfigurable Processors, designed for multimedia, focus on mapping the multimedia applications written in a high-level language directly on to the reconfigurable fabric, implying the use of same datapath resources for kernel processing and address generation. This results in inconsistent and non-optimal use of finite datapath resources. Presence of a set of dedicated, efficient Address Generator Units (AGUs) helps in better utilisation of the datapath elements by using them only for kernel operations; and will certainly enhance the performance. This article focuses on the design and application-specific integrated circuit implementation of address generators for complex addressing modes required by multimedia signal-processing kernels. A novel algorithm and hardware for AGU is developed for accessing data and coefficients in a bit-reversed order for fast Fourier transform kernel spanning over log?₂ N stages, AGUs for zig-zag-ordered data access for entropy coding after Discrete Cosine Transform (DCT), convolution kernels with stored/streaming data, accessing data for motion estimation using the block-matching technique and other conventional addressing modes. When mapped to hardware, they scale linearly in gate complexity with increase in the size.     

Local convex directions for Hurwitz stable polynomials

A condition for a polynomial p(s) to be a local convex direction for a Hurwitz stable polynomial q(s) is derived. The condition is in terms of polynomials associated with the even and odd parts of p(s) and q ( s), and constitutes a generalization of Rantzer's phase-growth condition for global convex directions. It is used to determine convex directions for certain subsets of Hurwitz stable polynomials     

All-Group IV Transferable Membrane Mid-Infrared Photodetectors

Semiconductor membranes emerged as a versatile class of nanomaterials to control lattice strain and engineer complex heterostructures enabling a variety of innovative applications. With this perspective, herein this platform is exploited to tune simultaneously the lattice parameter and bandgap energy in group IV GeSn semiconductor alloys. As Sn content is increased to reach a direct bandgap, these semiconductors become metastable and typically compressively strained. It is shown that the relaxation in released membranes extends the absorption wavelength range deeper in the mid-infrared. Fully released Ge_0.83Sn_0.17 membranes are integrated on silicon and used in the fabrication of broadband photodetectors operating at room temperature with a record wavelength cutoff of 4.6  µ m, without compromising the performance at shorter wavelengths down to 2.3  µ m. These membrane devices are characterized by two orders of magnitude reduction in dark current as compared to as-grown strained epitaxial layers. A variety of experimental tools and optimized calculations are used to discuss the crystalline quality, composition uniformity, lattice strain, and the electronic band structure of the investigated materials and devices. The ability to engineer all-group IV transferable mid-infrared photodetectors lays the groundwork to implement scalable and flexible sensing and imaging technologies exploiting these integrative, silicon-compatible strained-relaxed GeSn membranes.     

An efficient artificial bee colony algorithm with application to nonlinear predictive control

In this paper a constrained nonlinear predictive control algorithm, that uses the artificial bee colony (ABC) algorithm to solve the optimization problem, is proposed. The main objective is to derive a simple and efficient control algorithm that can solve the nonlinear constrained optimization problem with minimal computational time. Indeed, a modified version, enhancing the exploring and the exploitation capabilities, of the ABC algorithm is proposed and used to design a nonlinear constrained predictive controller. This version allows addressing the premature and the slow convergence drawbacks of the standard ABC algorithm, using a modified search equation, a well-known organized distribution mechanism for the initial population and a new equation for the limit parameter. A convergence statistical analysis of the proposed algorithm, using some well-known benchmark functions is presented and compared with several other variants of the ABC algorithm. To demonstrate the efficiency of the proposed algorithm in solving engineering problems, the constrained nonlinear predictive control of the model of a Multi-Input Multi-Output industrial boiler is considered. The control performances of the proposed ABC algorithm-based controller are also compared to those obtained using some variants of the ABC algorithms.     

A new method for the computation of all stabilizing controllers of a given order

A new method is given for computing the set of all stabilizing controllers of a given order for linear, time invariant, scalar plants. The method is based on a generalized Hermite–Biehler theorem and the successive application of a modified constant gain stabilizing algorithm to subsidiary plants. It is applicable to both continuous and discrete time systems.     

Phase transformations in nickel sulphide: Microstructures and mechanisms

Nickel sulphide inclusions are known to be responsible for delayed fracture in tempered glasses due to phase transformation within the inclusion. Microstructural identification of the phase transformation mechanisms in the Ni–S system close to the NiS composition were carried out on a series of partially transformed states. Observations allow to investigate the morphological evolution during transformation, the phase orientation relationships and the first stages of the transformation were investigated by optical microscopy, electron backscatter diffraction, and scanning and transmission electron microscopy. The transformation mechanisms change significantly with the change in sulphur content of the α-NiS phase. Massive transformation is observed for near-stoichiometric composition. For overstoichiometric composition, the transformation is controlled by a long-range diffusion mechanism. The influence of stoichiometry and impurities (Fe) on the microstructural evolution and transformation mechanisms has also been studied.     

A temporal-based SVM approach for the detection and identification of pollutant gases in a gas mixture

Applied Intelligence - Air toxicity and pollution phenomena are on the rise across the planet. Thus, the detection and control of gas pollution are nowadays major economic and environmental...