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.     

Elastic behavior of glass-like functionally graded infinite hollow cylinder under hydrostatic loads using finite element method

A glass-like (viscoelastic) functionally graded cylinder is studied by using finite element method to investigate the mechanical responses. A subroutine is developed by using ANSYS parametric design language (APDL) to simulate two nonlinearities, which are the variation of material properties with respect to time and position. The cylinder is made of two different viscoelastic materials, namely, pure material one at inner and pure material two at outer surfaces. The material properties are assumed to be presented by simple power law distribution and moreover, bulk and shear moduli are varying with respect to time using the kernel functions depicted regarding Prony series. It is shown that the hoop stresses take the same values at the mean radius (middle of the thickness) for different values of time and grading index. It is found that the radial stress decreases to certain values for specific grading index and then by increasing the grading index it increases to maximum value that related to pure material cylinder. It is shown that unlike the zero axial stress in pure material cylinders, it varies along the thickness from minimum to maximum at inner and outer surfaces, respectively. It is concluded that the viscoelastic functionally graded (VFG) materials play an important role in steady and transient response of hollow cylinder under hydrostatic load.     

Distinguishing condition curve for radial gates

Identifying the free or submerged flow condition and the threshold between the two regimes is vital for accurate flow measurement through a gate. In this paper, analytical findings about distinguishing condition curve of radial gates are presented. The generality of the available calibration methods of the radial gates has been analyzed. Then, based on the assumption of starting the transition zone right at the interception point of the free and submerged flow relationships, a comprehensive equation is developed to distinguish the flow condition through a radial gate. Using ample high quality available experimental data, the accuracy of the proposed distinguishing curve was verified. The results indicated that the proposed distinguishing curve accurately identified observed flow condition data. Finally, by defining a suitable sensitivity index, the effects of downstream channel width, energy loss through the gate, Reynolds number, and contraction coefficient on the distinguishing condition curve have been evaluated. Also, the results promise the application of the proposed method for situations where only one of some parallel radial gates is operating under the submerged flow condition.     

Heteropolyacids: An Efficient Catalyst for Synthesis of CL-20

CL-20, a high-energy material with a cage-like structure, is considered the most powerful explosive today. It is usually prepared via nitration with concentrated nitric and sulfuric acid, but this technique pollutes the environment. In this article, CL-20 was synthesized by nitration of 2,6,8,12-tetraacetyl 2,4,6,8,10,12-hexaazatetracyclo[5,5,0,0^3,11,0^5,9]dodecane (TAIW) using a clean nitrating agent, heteropolyacids. Using the new nitrating agent caused the elimination of concentrated sulfuric acid during the reaction. This is an environmentally friendly technique.     

CFD simulation and experimental study for two-phase flow through the trickle bed reactors, sock and dense loaded by trilobe catalysts

In this study single and two phase flow through the trickle bed reactor loaded with a two different loading manner, sock and dense, have been investigated numerically and experimentally. The CT-scan imaging and an image processing code have been used for investigation of radial porosity distribution of trilobe catalyst in sock and dense loading procedure in trickle bed reactors and two different correlations have been proposed. These correlations were used in a single and two phase CFD code for prediction of pressure drop of gas flow in dry and prewet trilobe catalyst packed bed and also pressure drop and dynamic liquid holdup for two phase flow. In addition, these variables were studied experimentally with a laboratory scale trickle bed reactor. The results of CFD simulations show a very good agreement with experimental data.     

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...     

Calciothermic co-reduction of TiO2-Cr2O3 oxides in molten CaCl2: Effect of particle size of starting materials

In this research, the effect of particle size of starting materials (TiO₂ and Cr₂O₃) was investigated on calciothermic co-reduction of oxides and in-situ dissolution of the CaO by-product in molten CaCl₂. The particle size of starting oxides, molar ratio of molten salt and holding time of reaction at elevated temperature affected the progress of reduction reactions and the remaining oxygen. In the best optimized condition, the remaining oxygen in the obtained TiCr₂ was 1020 and 802 ppm using 388 and 120 nm particle sizes of starting oxides, respectively. The formation of TiCr₂ in calciothermic co-reduction process was considered to be mutual diffusion phenomena. Also, the kinetics of hydrogen adsorption for the co-reduced sample was better than that of the arc-melted sample. Particle sizes of the obtained products decreased with-the decrease of the particle sizes of the starting oxides.     

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.     

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.