MCRA noise estimation for KLT-VRE-based speech enhancement

A new signal subspace-based approach is proposed for the enhancement of speech corrupted by a high level of noise. Conventional subspace-based methods use the minimum mean square error criterion to optimize the Karhunen-Loève Transform (KLT). In non-stationary noisy environments, the selection of the optimal order of the KLT-based speech enhancement model is a critical issue. Indeed, estimation of the relevant subspace dimensions depends on the environmental conditions that may change unpredictably. Therefore, a drastic KLT-based dimension reduction may induce the loss of relevant components of speech and conversely, a reconstruction using a higher order of the KLT model will be ineffective to remove the noise. The method presented in this paper uses a Variance of Reconstruction Error (VRE) criterion to optimally select the KLT order model. A prominent point of this subspace method is that it incorporates the Minima Controlled Recursive Averaging (MCRA) to estimate the noise Power Spectral Density (PSD) used in the gain function. Three variants of the VRE combined with MCRA methods are implemented and compared, namely the VRE-MCRA, VRE-MCRA2 and VRE-IMCRA. Objective measures show that VRE-based approaches achieve a lower signal distortion and a higher noise reduction than existing enhancement methods.     

Effects of High Hydrostatic Pressure Processing on Hen Egg Compounds and Egg Products

High hydrostatic pressure (HHP), used alone or with other processes, is an emerging technology increasingly used in the food industry to improve microbial safety, and the functionality and bioactive properties of food products. HHP provides a way to reduce energy requirements for food processing and may contribute to improved energy efficiency in the food industry. Hen egg is used by the food industry to formulate many food products. To improve the microbiological safety of egg and egg‐derived products, HHP processing is an attractive alternative to heat‐ pasteurization and a potential technology. However, HHP treatment induces structural modifications of egg components (such as proteins) which could positively or negatively affect the physicochemical and functional properties of egg‐derived products. Improving our knowledge regarding the potential of HHP in the egg industry will add value to the final food products and increase profitability for egg producers and the food industry.     

Line-to-line Voltage Space Vector Modulation for Neutral-point Clamped Multi-level Converter with DC-link Capacitor Voltage Balancing Using Redundant Vectors

This article presents space vector modulation of line-to-line voltage for the three-phase neutral-point clamped n-level converter with DC-link capacitor voltage balancing using redundant vectors. The developed modulation strategy is based on an equivalent matrix structure of the neutral-point clamped n-level converter. The relation between the 3 × (n – 1) switching functions of the matrix converter and gate signals of transistors of the neutral-point clamped n-level converter is given. A line-to-line space vector modulation strategy for a matrix inverter is used to obtain the switching function. For one switching function, there is more than one combination to produce each output voltage. Thus, redundancies of different switch configurations for generation of intermediate voltages are used to limit the deviation of capacitor voltages. The gate signals of the neutral-point clamped n-level converter can be calculated by inversing the modeling parts. Here, line-to-line voltage space vector modulation for a neutral-point clamped n-level converter is designed without using a Parks transform. Moreover, n × (n – 1) redundant vectors are used for DC bus voltage balancing. To highlight the performances of the developed modulation strategy, simulation results are given for five- and seven-level neutral-point clamped converters. Experimental results are given for a neutral-point clamped three-level converter.     

Comparison of stochastic methods with respect to performance and reliability of low‐temperature gas separation processes

In this paper, the performances of two popular stochastic methods, the genetic algorithm (GA) and simulated annealing (SA), are verified in the optimization of low‐temperature gas separation processes. While the feasibility of GA optimization of low‐temperature processes has recently been addressed, our work studied the quality of GA solutions. Having optimized the solutions of three different case studies, it was observed that SA is more robust and reliable than GA when applied to such systems, and by adjusting the key parameters in the SA method, the optimization process can avoid pre‐mature convergence and is able to give the best near‐global results.     

Polymer Grafting by Inkjet Printing: A Direct Chemical Writing Toolset

Among all the patterning techniques, inkjet printing has lately become a reliable technique at micrometer scale to produce localized modifications on material surfaces. Printing of polymer on material surface however leads to adsorbed patterns with poor adhesion. To overcome this drawback, a new process combining for the first time inkjet printing and an efficient covalent polymer grafting method was developed. This latter method is based on a photo‐assisted reduction of aryldiazonium salt/acrylate monomer ink, derived from the already published GraftFast process. In order to demonstrate its versatility, this new localized polymer grafting process is here combined as an example with the ligand induced electroless plating (LIEP) process to obtain metal interconnects onto flexible and transparent substrates with excellent mechanical and electrical properties for applications in flexible electronics devices.     

Experimental Study for the Performance of the Solar Distiller

This article describes the experimental results obtained by the solar distiller by specifying the radiative properties of materials, the analysis of various types of losses in the system and the establishment of the energy assessment of the system being the main question to consider. The experiment was undertaken in Tlemcen-Algeria by working out a solar distiller in order to measure the various temperatures of the system. Salt was added to study the negotiable effect of the salinity of water on solar distillation and it is noted that the production of distilled water decreases with salinity. The distiller is forwarded to a constant global solar flow. Experimental results obtained in heat transfer of natural convection in the pure and simultaneous heat and mass transfer, proven that these phenomena are in the boundary layer. This enables people to admit that the existence of a stagnant zone inside of distiller is called the ＂buffer zones＂.     

Robust Arabic speech recognition in noisy environments using prosodic features and formant

This paper investigates the contribution of formants and prosodic features such as pitch and energy in Arabic speech recognition under real-life conditions. Our speech recognition system based on Hidden Markov Models (HMMs) is implemented using the HTK Toolkit. The front-end of the system combines features based on conventional Mel-Frequency Cepstral Coefficient (MFFC), prosodic information and formants. The experiments are performed on the ARADIGIT corpus which is a database of Arabic spoken words. The obtained results show that the resulting multivariate feature vectors, in noisy environment, lead to a significant improvement, up to 27%, in word accuracy relative the word accuracy obtained from the state-of-the-art MFCC-based system.