Efficient and dynamic verifiable multi-keyword searchable symmetric encryption with full security

Multimedia Tools and Applications - Increasing the popularity of cloud computing raises the importance of efforts to improve the services of this paradigm. Searching over encrypted data is a...     

Simultaneous heavy paraffin dehydrogenation and hydrogenation of nitrobenzene in a linear alkyl benzene plant

In the current study, a novel thermally coupled reactor with radial-flow pattern named as Radial Flow-Coupling Reactor (RF-CR) is modeled for heavy paraffin dehydrogenation. In this novel structure, the cross-section area of the Radial Flow-Tubular Reactor is sliced into some subsections. The necessary heat for heavy paraffin dehydrogenation in the endothermic side is supplied by the catalytic nitrobenzene hydrogenation in the exothermic side. The results of modeling represent 12.4 tons per day enhancement in the olefin production rate in comparison with non-coupling configuration using the same catalyst loading and duty. Besides, aniline as an additional valuable product is produced ～17.45 tons per day in exothermic side of RF-CR.     

Thermo elastic analysis of a functionally graded rotating disk with small and large deflections

A functionally graded (FG) rotating disk with axisymmetric bending and steady-state thermal loading is studied. The material properties of the disk are assumed to be graded in the direction of the thickness by a power law distribution of volume fractions of the constituents. First-order shear deformation Mindlin plate and von Karman theories are employed. New set of equilibrium equations with small and large deflections are developed. Using small deflection theory an exact solution for displacement field is given. Solutions are obtained in series form in case of large deflection. Mechanical responses are compared small deflection versus large deflection as well as homogeneous versus FG disks. It is observed that for particular values of the grading index n of material properties mechanical responses in FG disk can be smaller than in a homogeneous disk. It is seen that given the non-dimensional maximum vertical displacement w_max/h close to 0.4 for a homogeneous (full-ceramic in this study) disk greater errors in the mechanical responses for FG disks would be introduced if one uses small deflection theory.     

Multilayered optical OFDM for high spectral efficiency in visible light communication system

Photonic Network Communications - This paper presents two new schemes for improving the spectral efficiency of an optical orthogonal frequency-division multiplexing-based visible light...     

Hydrogels with Acid Groups for Removal of Copper(II) and Lead(II) Ions

Acrylamide-maleic acid (AAM-MA) hydrogels having high acid group content prepared with different maleic acid ratios were used for the removal of Cu(II) and Pb(II) ions from aqueous solutions in competitive and noncompetitive conditions. The effects of pH, time, and initial metal ion concentration on the metal ion adsorption capacity were investigated. The adsorption isotherm models were applied on experimental data and it is shown that the Freundlich equation was the best model for Cu(II) ion while the Langmuir isotherm model was the best one for Pb(II) ion. The stability constants of acrylamide-maleic acid hydrogel-Cu(II) and Pb(II) complexes were also determined by van den Berg/Ruzic transformation, and K values obtained were 1.60 × 10³ and 1.81 × 10³ for Cu(II) and Pb(II) ions, respectively. The experiments under competitive conditions showed that the hydrogels prefered Pb(II) ion and this preference increased with increasing of carboxylic acid group content (AGC) of polymers. It is stated that these hydrogels can be regenerated efficiently (>95%) and used repeatedly.     

Structural, Theoretical and Multinuclear NMR Study of a New Polymeric Mercury(II) Complex with an Ambidentate Phosphorus Ylide

The reactions of phosphorus ylides of the type Ph₃P=C(H)C(O)R [R = 2,4-dichlorophenyl (L ¹ ) and 4-isopropylphenyl (L ² )] with HgX₂ [X = Cl (1, 4), Br (2, 5) and I (3, 6)] salts using methanol as a solvent are reported. Single crystal X-ray analysis carried out on L ¹ , 2 and 3 and reveals the presence of a novel polymeric structure for 2 and a centrosymmeteric dimeric structure for 3. The complexes have been studied by elemental analyses, IR, ¹H and ³¹P NMR spectroscopy. On the basis of DFT calculations, the formation of [Hg₂Br₆]^2? anions in 2 has a key role in the formation of the polymeric structure; and, the formation of [Hg₂L₂I₄] molecule thermodynamically is about 25 kcal/mol more favorable than the corresponding [Hg₂L₂Br₄] molecule.     

Separation of methane from different gas mixtures using modified silicon carbide nanosheet: Micro and macro scale numerical studies

This research discusses the separation of methane gas from three different gas mixtures, CH₄/H₂S, CH₄/N₂ and CH₄/CO₂, using a modified silicon carbide nanosheet (SiCNS) membrane using both molecular dynamics (MD) and computational fluid dynamics (CFD) methods. The research examines the effects of different structures of the SiCNSs on the separation of these gas mixtures. Various parameters including the potential of the mean force, separation factor, permeation rate, selectivity and diffusivity are discussed in detail. Our MD simulations showed that the separation of CH₄/H₂S, and CH₄/CO₂ mixtures was successful, while simulation demonstrated a poor result for the CH₄/N₂ mixture. The effect of temperature on the diffusivity of gas is also discussed, and a correlation is introduced for diffusivity as a function of temperature. The evaluated value for diffusivity is then used in the CFD method to investigate the permeation rate of gas mixtures.     

Development of a technology orientated programming system for industrial robots

The disassembly of used goods is characterized by strongly varying quantities and a wide range of different kinds and states of products. Furthermore, the requirements of a disassembly system are determined by the disassembly object, by the process as well as by the disassembly system itself. As a result of the high labor costs in industrial countries and the huge amount of used goods, an automated disassembly is favored for the industrial disassembly. New methods for the programming of industrial robots have to be developed because the costs for a programming of small lot sizes are a key factor of the economic efficiency of small and medium sized enterprises (SME). In this paper an off-line programming environment for programming of industrial robots in the field of automated disassembly is presented. The exemplary implementation is realized at a pilot disassembly system, which was built up at the Institut für Werkzeugmaschinen und Fabrikbetrieb (IWF) of the Technische Universität Berlin.     

Evaluation of gasoline evaporation during the tank splash loading by CFD techniques

This paper presents a CFD simulation of gasoline evaporation during the splash loading of gasoline tank. The volume of fluid based (VOF) interface tracking method in conjunction with a mass transfer model was used. Evaporation rate was determined by a source term at the interface. The effect of different parameters such as loading velocity, temperature and initial vapor mass fraction on gasoline lost was determined. The results show that by increasing the loading velocity, the total evaporated mass decreases. Based on CFD simulations a correlation has been proposed to evaluate the amount of gasoline losses during the fuel tank splash loading.     

Electrokinetic dewatering of Turkish glass sand plant tailings

In this study, the dewatering of glass sand plant tailings from Mersin, Turkey was investigated using an electrokinetic technique. The particle size (d(80)) of the solid waste material tested was less than 0.020 mm and consisted mainly of silica, orthoclase, alumina, potassium and iron oxides. In current plant practice, Larox high-pressure filters are used to produce a filter cake containing 22-25% moisture. As an alternative, a laboratory-scale dewatering pond using an electrokinetic technique was designed and a final product (cake) containing 34% moisture was obtained after 24h treatment using 14.6 V direct current applied for 40 min. When the treatment continued up to 48 h, a firm-to-hard cake was produced.