Methanogenic fermentation of scots pine (Pinus sylvestris) sawdust: Enhancement by physicochemical pretreatment

The three major polymeric components of Scots Pine sawdust–lignin, hemicellulose and cellulose–represent potential substrates for methanogenic fermentation although, in the absence of physicochemical pretreatment, low digestibility was demonstrated even after protracted incubation (18 months). Acid (H₂SO₄) and alkali (NaOH) pretreatments mediated different effects although, in general, the rates and percent solubilisations increased with concentration, temperature, pressure and time, either singly or in combination. Individual methanogenic fermentations with the hydrolysates and residual solids showed that although 3.3% more methane resulted from the H₂SO₄ hydrolysate than the corresponding NaOH hydrolysate, in total, 7% more methane was generated from the two alkali fractions than from the corresponding acid fractions. The results thus exemplified that choice of a specific physicochemical strategy must be made in conjunction with the expected yield from the selected fraction(s).     

Approved algorithmic security enhancement of stream cipher for advanced mobile communications

ABSTRACT

Confidentiality and integrity processes are based on SNOW and ZUC algorithms. These standardized algorithms are designed by the 3rd Generation Partnership Project (3GPP) for advanced mobile communication systems. Each algorithm has two S-boxes in its nonlinear layer structure. This paper proposes three different approaches to enhance the security level of both algorithms. The first approach aims to select the best combination of two S-boxes in the nonlinear part of each algorithm. Results showed that the best randomness properties are achieved by combining the Feistel structure (S1-box) and Rijndael (S2-box) in the SNOW algorithm and New Rijndael (S1-box) and Rijndael (S2-box) in the ZUC algorithm. The second approach aims to increase the nonlinearity and complexity of these algorithms by selecting a strong S-box to cascade the best-existing two S-boxes for both algorithms. The third approach is an extension of the former, based on a dynamic reform of such S-boxes as a function of the “Authentication Token” to increase the computational complexity of the upgraded two algorithms. These proposed upgrades are simulated by C language and tested successfully for their statistical properties using the standard NIST SP 800-22 test suite.     

Synthesis,structural, linear and nonlinear optical properties of chromium doped SnO2 thin films

The present work concentrates on some physical investigation of the undoped and Cr doped SnO₂ thin films deposited onto precleaned glass substrates by the spray pyrolysis system. The physical properties of the undoped and Cr doped SnO₂ thin films were investigated by the X-ray diffraction (XRD), atomic force electron microscope (AFM), field emission scanning electron microscope (FESEM), four-probe method and double beam spectrophotometer. The undoped and Cr doped SnO₂ films display a polycrystalline nature with orthorhombic crystal structure. The linear optical constants energy gap E_g, refractive index n, absorption coefficient α, static refractive index n_o, oscillation energy E_o, dispersion energy E_d and the Urbach energy of the undoped and Cr doped SnO₂ thin films were evaluated. The investigated films exhibit a direct energy gap and their values decrease with the increasing of Cr doping content while the Urbach energy follows a reverse behavior. On the other hand, the nonlinear optical constants (third-order nonlinear susceptibility ${\mathit{\chi }}^{(3)}$ and nonlinear refractive index n₂) have been increased with increasing the Cr doping content. Finally, it has been found that the sheet resistance and conductivity of the synthesized thin films were enhanced by increasing the Cr doping content. The 5?wt% Cr doped SnO₂ thin film has a high value of the figure of merit among other films.     

Fault diagnosis system for tapped power transmission lines

This paper presents a design for a fault diagnosis system (FDS) for tapped HV/EHV power transmission lines. These lines have two different protection zones. The proposed approach reduces the cost and the complexity of the FDS for these types of lines. The FDS consists basically of fifteen artificial neural networks (ANNs). The FDS basic objectives are mainly: (1) the detection of the system fault; (2) the localization of the faulted zone; (3) the classification of the fault type; and finally (4) the identification of the faulted phase. This FDS is structured in a three hierarchical levels. In the first level, a preprocessing unit to the input data is performed. An ANN, in the second level, is designed in order to detect and zone localize the line faults. In the third level, two zone diagnosis systems (ZDS) are designed. Each ZDS is dedicated to one zone and consists of seven parallel-cascaded ANN's. Four-parallel ANN's are designed in order to achieve the fault type classification. While, the other three cascaded ANN's are designed mainly for the selection of the faulted phase. A smoothing unit is also configured to smooth out the output response of the proposed FDS.     

Overall Performance Evaluation and Functional Analysis of Egyptian Starch Manufacturing Plants

The present paper outlines the approach and principal results of a full-fledged performance evaluation and functional analysis program conducted at the Egyptian Starch and Glucose Company that has been wholly documented elsewhere [12]. The ultimate goal of the program is to come up with well-defined and appropriate courses of action to improve products quality, plant productivity and overall economy. The paper also reports the results of additional computer work that has been undertaken to enhance the applicability of the results. The adopted methodology for applying the developed computer material balance (MASSBAL) in the evaluation program and in analysing the impacts of stepwise improvements in the individual plant sectors of concern is also presented.     

Simultaneous identification of Robin coefficient and heat flux in an elliptic system

In this paper, we shall derive and propose an efficient algorithm for simultaneously reconstructing the Robin coefficient and heat flux in an elliptic system from part of the boundary measurements. The uniqueness of the simultaneous identification is demonstrated. The ill-posed inverse problem is formulated into an output least-squares nonlinear and non-convex minimization with Tikhonov regularization, while the regularizing effects of the regularized system are justified. The Levenberg–Marquardt method is applied to change the non-convex minimization into convex minimization, which will be solved by surrogate functional method so as to get the explicit expression of the minimizer. Numerical experiments are provided to show the accuracy and efficiency of the algorithm.     

Flotation of α-iron(III) oxide by cetyltrimethylammonium bromide and its activation by phosphates

The zero point of charge, z.p.c., of chemically prepared α-Fe₂O₃ was found at pH 6.9. The adsorption isotherms of cetyltrimethylammonium bromide, CTAB, had a Langmuir shape and shifted to higher adsorption density as the pH increased above the z.p.c. The variation of the adsorption plateau with pH could be correlated with the change in ζ potential accompanying the adsorption of CTAB. The graphs of the recovery of α-Fe₂O₃ floated by CTAB plotted against its equilibrium concentration exhibited maxima, which became higher as the pH increased from 6 to 10. The adsorption capacity of α-Fe₂O₃ for phosphate ions markedly decreased and their desorption increased as the pH increased. The drop in ζ potential of α-Fe₂O₃ in phosphate solution became smaller as the pH increased. In presence of phosphate ions, the adsorption capacity of α-Fe₂O₃ for CTAB markedly increased at pH 6, the enhancement becoming less marked as the pH increased. The enhancement paralleled the phosphate adsorption. In presence of phosphate ions, the recovery of α-Fe₂O₃ floated by CTAB was higher, the activation decreasing as the pH increased. The maximum recovery was shifted to lower CTAB concentration compared to the recovery of unactivated α-Fe₂O₃.     

A Relaxed Gradient Based Algorithm for Solving Extended Sylvester‐Conjugate Matrix Equations

In this paper, a relaxed gradient based algorithm for solving extended Sylvester‐conjugate matrix equations by considering a relaxation parameter is proposed. The convergence analysis of the algorithm is investigated. Theoretical analysis shows that the new method converges under certain assumptions. A numerical example is given to illustrate effectiveness of the proposed method and to test its efficiency compared with an existing one.     

Exploring the next neighbourhood relationship in amorphous alloys utilizing atom probe tomography

A new algorithm is developed to explore the next neighbourhood atomic vicinity from the analysed data obtained using the tomographic atom probe (TAP) technique. The presented algorithm allows to calculate the atomic distances among different next neighbours of different elements as applied to bulk amorphous alloys. The results obtained for Pd55 Cu23 P22 bulk amorphous alloys show reasonable consistency to already available data from different diffraction techniques. The Pd-Pd atoms have highest probability to be a next neighbour than others. The established view that P is not a direct next neighbour to each other is also manifested from these results. Normalizing the distances of the next neighbours to the first neighbour distance in this particular amorphous system possesses a definite order for all elemental correlations. Furthermore, the algorithm was processed for different critical reconstruction parameters to explore the corresponding effect on the distance distribution of next neighbouring atoms. The minor changes in the product of the geometric factor and the evaporation field of the sample does not make any egregious difference on the next neighbourhood evaluation (NNE).