Generalized Twin Support Vector Machines

Neural Processing Letters - In this paper, we propose two efficient approaches of twin support vector machines (TWSVM). The first approach is to reformulate the TWSVM formulation by introducing...     

Orthonormal Bernoulli polynomials for space–time fractal-fractional modified Benjamin–Bona–Mahony type equations

Engineering with Computers - In this study, a new fractal-fractional (FF) derivative is defined by coupling the local conformable derivative and non-local Caputo fractional derivative. Using the...     

Secret image sharing based on cellular automata and steganography

Recently Lin and Tsai [Secret image sharing with steganography and authentication, The Journal of Systems and Software 73 (2004) 405-414] and Yang et al. [Improvements of image sharing with steganography and authentication, The Journal of Systems and Software 80 (2007) 1070-1076] proposed secret image sharing schemes combining steganography and authentication based on Shamir's polynomials. The schemes divide a secret image into some shadows which are then embedded in cover images in order to produce stego images for distributing among participants. To achieve better authentication ability Chang et al. [Sharing secrets in stego images with authentication, Pattern Recognition 41 (2008) 3130-3137] proposed in 2008 an improved scheme which enhances the visual quality of the stego images as well and the probability of successful verification for a fake stego block is 1/16.In this paper, we employ linear cellular automata, digital signatures, and hash functions to propose a novel (t,n)-threshold image sharing scheme with steganographic properties in which a double authentication mechanism is introduced which can detect tampering with probability 255/256. Employing cellular automata instead of Shamir's polynomials not only improves computational complexity from to O(n) but obviates the need to modify pixels of cover images unnecessarily. Compared to previous methods [C. Lin, W. Tsai, Secret image sharing with steganography and authentication, The Journal of Systems and Software 73 (2004) 405-414; C. Yang, T. Chen, K. Yu, C. Wang, Improvements of image sharing with steganography and authentication, The Journal of Systems and Software 80 (2007) 1070-1076; C. Chang, Y. Hsieh, C. Lin, Sharing secrets in stego images with authentication, Pattern Recognition 41 (2008) 3130-3137], we use fewer number of bits in each pixel of cover images for embedding data so that a better visual quality is guaranteed. We further present some experimental results.     

Oxidase-Peroxidase sequential polymerization for removal of a dye from contaminated water by horseradish peroxidase (HRP)/glucose oxidase (GOx)/polyurethane hybrid catalyst

Horseradish peroxidase (HRP) and glucose oxidase (GOx) were co-immobilized on polyurethane, and the resulting HRP/GOx/polyurethane biocatalyst was characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDAX) mapping techniques. The prepared biocatalyst was used for removal of acid orange 7 as model azo dye. The required H₂O₂ for activation of HRP was in-situ produced using GOx to prevent deactivation of HRP in the presence of excess chemical H₂O₂. Central composite design (CCD) was applied for modeling and optimization of parameters affecting the activity of prepared biocatalyst. Under the optimum conditions, removal efficiency of the azo dye was predicted to be 87.47%, which was in good agreement with the experimental value (89.69%). In addition, the performance of the prepared biocatalyst for removal of two other dyes with different structure was investigated at the optimum conditions, and a removal efficiency of 91.56% and 95.25% was obtained for removal of methylene blue and malachite green, respectively. The results demonstrated that the resultant HRP/GOx/Polyurethane biocatalyst was able to decrease the chemical oxygen demand (COD) of a textile effluent from 740mg/L to 96mg/L, indicating that the prepared biocatalyst is an effective enzymatic system for treatment of real wastewater.     

Increasing ethylene production as a high value hydrocarbon in Fischer-Tropsch (FT) reactor: A concept reactor for combining FT with oxidative coupling of methane

The paper proposes a concept configuration of reactors for coupling OCM and FTS, and presents systematic simulation results. FTS section is a combination of fixed bed and membrane fluidized bed reactor, and feed of the FT reactor is supplied by OCM. The reactor configuration is compared with the consecutive reactors of OCM and one fixed bed FT reactor. Effects of CH₄/O₂ ratio, percent of N₂ in the feed, contact time, and input temperature on the yield of ethylene and valuable hydrocarbons are studied. The results show that compared with one FTS reactor configuration, the dual FTS reactor configuration is more effective and thus gives much higher product yields. Furthermore, a main decrease is observed in the formation of CO₂ and CH₄.     

Identification of time-varying linear and bilinear systems via Fourier series

A method for identification of time-varying linear systems and bilinear systems is proposed. The method is based upon expanding various time functions in the system as their truncated Fourier series, using the operational matrices for integration and product and hence reducing the problem into a set of algebraic equations. The method is computationally attractive, and applications are demonstrated through illustrative examples.     

Calculation of effectiveness factor for multiple claus reactions with single-step rate-controlling

Most of the bountiful literature on the calculation of effectiveness factors for catalyst particles deals with relatively simple reactions and kinetics. The performance of catalyst particles in the industrially important, modified Claus reaction introduces multiple reactions, sulphur vapour equilibria, non-linear kinetics and limiting thermodynamic conversions into the calculation of local effectiveness factors. This analysis demonstrates a means for generating local effectiveness factors, during reactor design calculations by the use of a single calculated curve of versus a modified Thiele parameter for spherical particles.