Factorization and feedback stabilization for nonlinear systems

We establish the equivalence of internal input-out stability for two feedback configurations of a nonlinear, time-varying plant P for which a related plant G is assumed to have a factorization G = R with both R and R⁻¹ incrementally stable; this extends a factorization principle for stabilizability previously given only for the linear, time-invariant case. As an application of a special case we recover a version of the Youla parametrization of stabilizing compensators for the nonlinear case previously presented in the literature. We use degree theory to parametrize a collection of solutions of the H_∞-control problem for the case of a 1-gain stable or lossless plant. In the case of a plant G having a J-inner-outer factorization, this last result combined with the above-mentioned factorization principle leads to results on the H_∞-control problem for P.     

Quest for sustainable bio‐production and recovery of butanol as a promising solution to fossil fuel

Biobutanol has conventionally been generated by fermentation of carbohydrates derived from biomass (starch or sugar‐based feedstock, such as corn) using Clostridia strains (mainly C. beijerinckii and C. acetobutylicum) under anaerobic conditions in batch mode. Under these premises, it has been tough for the acetone–butanol–ethanol fermentation to compete with petro‐butanol production from an energy efficiency and material consumption standpoint. Challenges for butanol production from biomass comprised high cost of feedstock, scarcity of hyper‐butanol producing bacteria and low butanol yield, volumetric productivity and titre, leading to high water usage and separation‐purification costs. This article is an up‐to‐date review on several under explored sections, such as optimization of fermenter feed, microbial culture responsible for solvent production (co‐culture techniques and electro‐biochemical process), latest recovery techniques and the studies integrating in situ continuous fermentation processes. Biobutanol refinery way forward should build upon the use of low‐cost lignocellulosic matter and zero cost organic wastes and by‐products from food, agriculture, forestry, fermentation and paper industries as feedstock; optimized fermentation of such diversified feed with appropriate hyper‐butanol producing strains in biofilm reactors and integration of fermentation step with hybrid high butanol‐selective recovery techniques. Copyright © 2015 John Wiley & Sons, Ltd.     

Comparative study of toxic chlorophenolic compounds generated in various bleaching sequences of wheat straw pulp

This study compared the chlorophenolic compounds generated during the bleaching of wheat straw pulp. The six different bleaching sequences used in present study were: (i) chlorine-extraction-hypo (CEH); (ii) persulphate-peroxide-chlorine-extraction-hypo (Px-P-CEH); (iii) oxygen-chlorine-extraction-hypo (OCEH); (iv) chlorine dioxide-extraction-chlorine dioxide (DED); (v) persulphate-peroxide-chlorine dioxide-extraction-chlorine dioxide (Px-P-DED); and (vi) oxygen-chlorine dioxide-extraction-chlorine dioxide (ODED) bleaching. The concentrations of a large number of identified chlorophenolic compounds often exceed their threshold concentrations in CEH effluent. Therefore, the untreated effluent generated from the CEH bleaching sequence of wheat straw pulp can be considered toxic. Prebleaching (PxP) reduces the generation of chlorophenolic compounds by 36 % in the (PxP)CEH sequence. Oxygen prebleaching reduces the generation of chlorophenolic compounds by 86 % in the OCEH bleaching effluent. The PxP also reduces the generation of chlorophenolic compounds by 46 % in the (PxP)DED bleaching sequence and oxygen delignification substantially reduces the generation of the compounds by 78 %.     

Bulk modulus and hardness of chalcopyrite structured solids

The bulk modulus and microhardness can be represented by an empirical linear relation that is a simple function of melting temperature T_m, atomic volume Ω and product of ionic charges (Z₁Z₂Z₃). Values of bulk modulus B and microhardness H of A^IB^IIIC₂^VI and A^IIB^IVC₂^V chalcopyrite semiconductors exhibit a linear relationship when plotted against the k_BT_m/Ω (k_B = Boltzmann's constant), but fall on two straight lines according to the product of ionic charges of the compounds. This correlation is similar in form to other correlations in the literature for diffusion data of materials that indicate the significance of the melting temperature as a scaling or lattice dynamic properties of materials. The calculated results are compared with available experimental data and previous calculations based on phenomenological models.     

Development of bimetal-grown multi-scale carbon micro-nanofibers as an immobilizing matrix for enzymes in biosensor applications

This study describes the development of a novel bimetal (Fe and Cu)-grown hierarchical web of carbon micro-nanofiber-based electrode for biosensor applications, in particular to detect glucose in liquids. Carbon nanofibers (CNFs) are grown on activated carbon microfibers (ACFs) by chemical vapor deposition (CVD) using Cu and Fe as the metal catalysts. The transition metal-fiber composite is used as the working electrode of a biosensor applied to detect glucose in liquids. In such a bi-nanometal-grown multi-scale web of ACF/CNF, Cu nanoparticles adhere to the ACF-surface, whereas Fe nanoparticles used to catalyze the growth of nanofibers attach to the CNF tips. By ultrasonication, Fe nanoparticles are dislodged from the tips of the CNFs. Glucose oxidase (GOx) is subsequently immobilized on the tips by adsorption. The dispersion of Cu nanoparticles at the substrate surface results in increased conductivity, facilitating electron transfer from the glucose solution to the ACF surface during the enzymatic reaction with glucose. The prepared Cu-ACF/CNF/GOx electrode is characterized for various surface and physicochemical properties by different analytical techniques, including scanning electron microscopy (SEM), electron dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), BET surface area analysis, and transmission electron microscopy (TEM). The electrochemical tests show that the prepared electrode has fast response current, electrochemical stability, and high electron transfer rate, corroborated by CV and calibration curves. The prepared transition metal-based carbon electrode in this study is cost-effective, simple to develop, and has a stable immobilization matrix for enzymes.     

IRS-1C data application in watershed characterization and management

Watershed characterization and management aims at the optimum utilization of land and water resources on a sustained basis. For a precise inventory of a watershed, components like drainage density and pattern, slope percentage and direction, physiography, soils, land use and land cover, were visually interpreted using the geocoded false colour composites (FCCs) of IRS-1B LISS II and IRS-1C LISS III at 1:50 000 scale. The land use and land cover study indicates that the major land utilization types are single crop (28.8%); double crop (14.3%); scrub land (43.1%); degraded notified/open forest (7.2%); rock outcrop (3.8%) and water bodies (2.8%). The dominant soils are loamy-skeletal, Lithic Ustorthents; loamy-skeletal, Lithic Ustochrepts; fine calcareous, Typic Ustochrepts; fine, Vertic Ustochrepts, and very fine, Typic Haplusterts. The soils are grouped into IIIs, IIIes, IVes and VIes land capability classes; N1, N2, S1, S2 and S3 soil site suitability classes and Wt 1.2, Wt 1.3, Wt 2.5, Wt 3.4 and Wt 3.5 soil degradation classes. Based on soil types, percentage slope, drainage density, bifurcation ratio and constant channel maintenance ratio, the soil conservation modules like field bunding, contour bunding, Nala lining and Nala plug/cement check dams were erected. Soil conservation modules, particularly field bunding/ contour bunding improved the moisture status in soils of subdued plateau and upper pediment and resulted in a better harvest of crops under monocropping. Grading and terracing of lower pediments helped to harvest run-off into farm ponds for further recycling of water for agro-horticultural crops. Nala lining and Nala plug/cement check dams in the valley regions have helped in improving the irrigation potential for crops under double cropping system and agroforestry on the plateau top by further reducing the denudation process.     

Stumbling Blocks in Cloud Computing Adoption Pathway： A Charter

Cloud computing is currently an embryonic domain in the area of information technology that possesses the power of transforming the way information technology （IT） services are delivered and maintained in the business world. Pay as per the usage kind of cost structure coupled with delivery of computing services through internet makes cloud computing an exciting and potential growth oriented information technology model compared with conventional computing services delivery models. Various additional features like scalability, flexibility and easy deployment process creates a window for the organizations even relatively smaller in size to get benefitted by the highly advanced ＆ modern technologies without incurring substantial cost. In spite of so many benefits of this new delivery model, concerns are beginning to grow about how safe an environment it is. Despite of all the hype surrounding the cloud, enterprise customers are still reluctant to deploy their business in the cloud. Security is one of the major issues which reduces the growth of cloud computing and complications with data privacy and data protection continue to plague the market. Other related concerns associated with the adoption of cloud computing include trust on service providers, loss of control and compliance issues. This paper is an attempt to explore security ＆ trust issues linked with cloud computing adoption in the Small and Medium Enterprises （SME） sector.