Feedback active noise control based on transform-domain forward–backward LMS predictor

In this paper, a new feedback active noise control (FBANC) system based on the transform-domain forward–backward LMS (TFBLMS) predictor has been proposed. The new ANC system employs the TFBLMS predictor for its main-path (MP) predictor as well as for the noise canceller. To overcome the ill effect of the primary noise field, which acts as an observation noise for the secondary-path (SP) identification, the noise canceller is used. As the main-path predictor is based on the TFBLMS, its convergence rate improves due to its input orthogonalization. Further, its FBLMS nature reduces misadjustment. The use of TFBLMS predictor for noise canceller also gives a good prediction of primary noise at a faster rate, enabling improved SP identification. This improved SP identification indirectly aids the MP predictor to achieve an improved performance. A new filtered-x LMS structure has been proposed to realize the new MP predictor to accommodate the TFBLMS algorithm. The TFBLMS algorithm is applied directly to the noise canceller for SP identification. The proposed new ANC system has been found to have a significantly better noise reduction (by 14.6 dB) over the FBANC system based on tapped delay line time-domain FBLMS algorithm.     

On the flow of an electrically conducting nonlocal viscous fluid between parallel plates in the presence of a transverse magnetic field in magnetohydrodynamics

A continuum theory is constructed for the flow of an electrically conducting nonlocal viscous fluid between two nonconducting parallel plates. The flow is subject to the influence of a transverse magnetic field. The effects of long range or nonlocal interactions at a material point in the fluid arising from all material points in the rest of the fluid are taken into account by means of a nonlocal influence function. Equations of motion governing the nonlocal viscous flow are derived from localized forms of global balance laws and constitutive equations appropriate for electromagnetically active media. These field equations are analytically solved for the nonlocal velocity and the nonlocal stress fields. The effects of varying the magnetic field strength on the shear stress are investigated. The effects of such variations on the shear stress exerted on the walls of microscopic channels are also determined. Numerical computations are provided for these results.     

Uptake of decontaminating agent from aqueous solution: a study on adsorption behaviour of oxalic acid over Al-MCM-41 adsorbents

Hydrothermal method was followed to synthesis the mesoporous Al-MCM-41 (Si/Al = 25, 50, 75 and 100) and Si-MCM-41 molecular sieves using a cetyltrimethylammonium bromide as a surfactant and the materials were unambiguously characterized by XRD, N₂ sorption studies, ²⁷Al MAS-NMR and TEM. The removal of oxalic acid from aqueous solution was studied through an adsorption process because oxalic acid may cause complexes with radioactive cations during decontamination operation in nuclear industry, which resulting in interferences in their removal by conventional treatment. Adsorption of oxalic acid over Al-MCM-41 shows the applicability of Langmuir isotherm and follows first order kinetics. The effects of parameters such as contact time, concentration of oxalic acid, adsorbents (various Si/Al ratios of Al-MCM-41, Si-MCM-41 and activated charcoal) and pH have been investigated to yield higher removal of oxalic acid. The percentage of oxalic acid adsorbed per unit gram of adsorbent for Al-MCM-41 at Si/Al = 100, 75, 50 and 25, Si-MCM-41, and activated charcoal are 34.6, 40.9, 51.4, 61.3, 16.1 and 60, respectively. Retainment of crystallinity and absence of structural collapse of Al-MCM-41 after desorption and adsorption of oxalic acid, respectively has been achieved in this study.     

Hydrogen production by alcoholysis of sodium borohydride

Alcoholysis of sodium borohydride offers advantages due to reduction in number of steps for recycling of sodium borohydride, elimination of freezing problems that are associated with the use of water, fast generation of hydrogen, etc. Methanol was used to liberate hydrogen from sodium borohydride. The influence of the amount of solvent, substrate concentration, temperature and catalyst on the kinetics of alcoholysis reaction in non‐stabilized sodium borohydride has been examined in the present study. The reaction was found to be first order with respect to substrate concentration and zero order with respect to solvent concentration. Effect of soluble metal salts, metal powder and metal boride as catalysts on hydrogen generation rate has also been investigated. It was found that NiCl₂, Ni₂B and RuCl₃ were effective catalysts and hydrogen generation proceeds with high efficiency in the presence of these catalysts. Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of mixture composition and hardware on the performance of a single stage JT refrigerator

The specific refrigeration effect that can be obtained in a single stage mixed refrigerant Joule–Thomson refrigerator is strongly dependent on the composition of mixture used. Comprehensive methods have been developed over the last two decades to determine the mixture composition that results in the highest exergy efficiency or the refrigeration produced. However, what is not well known is the relationship between the mixture composition and the hardware, which ultimately decides the performance of the refrigerator. Experiments were conducted with seven different nitrogen–hydrocarbon mixtures in a single stage JT refrigerator to understand the effect of both composition and hardware on the performance of the refrigerator, the results of which are presented in this paper.     

Informatics for combinatorial materials science

Combinatorial experiments aim to create large amounts of data and information, and managing that data is a challenge. This article will focus on how to scientifically interpret the data generated from combinatorial experiments and high-throughput screening.     

Friction coefficient analysis of multicomponent solute transport through polymer membranes

A new analysis is presented of the relations between the multicomponent diffusion coefficients and the classical Kedem–Katchalsky coefficients which describe solute transport in membranes. This analysis is applied to binary and ternary systems and shows the importance of system nonideality in the calculation of solute diffusion coefficients. It is shown that the solute permeability coefficients can be calculated from independent knowledge of the nonideal thermodynamic activity coefficients and the multicomponent diffusion coefficients of the system. © 1996 John Wiley & Sons, Inc.     

Performance modelling of three parallel sorting algorithms on a pipelined transputer network

The implementation of three parallel sorting algorithms, namely binary sort, odd-even transposition sort and bitonic sort, on a network of transputers is analysed in the paper. The variation in the performance of these algorithms as the number of processors and sort size are changed is investigated. Experimental results show that when up to eight transputers are used, connected as a linear pipeline configuration, all three algorithms can achieve reasonable speedup ratios. The bitonic sort, binary sort odd-even transposition sort achieve speedup ratios of 5, 4.4 and 4, respectively, when eight processors are used to sort 100,000 integers. Analytical models are derived which can be used to predict the performance of the three algorithms when a linear pipeline configuration is used. The predicted performance of the algorithms is compared with the experimental performance in order to validate the model. When the models are used to predict the performance using 16 transputers, it is found that the speedup does not significantly improve compared to the performance achieved with eight transputers. This shows that interprocessor communication has a significant effect on the algorithmic performance when a larger number of processors are used. The conclusions reinforce the fact that the binary and bitonic sorting algorithms are not well-suited to a linear pipeline configuration and that they may perform better if a different topology were used, for example a mesh or a cube connection scheme. Further, the analytical technique used for performance modelling as elaborated in the paper can be employed profitably for other multiprocessor systems as well.