International Journal of Engineering
Volume:23 Issue: 2, May 2010

Pectin from two different plant sources: apple and sugar beet was studied. Apple pectinwas modified by chemical treatments such as: acid, alkali and ammonia, so as to obtain an ester level equal to or less than 50 %, which is described as low methoxyl (LM) pectin. LM pectin form gels with significant characteristic. In this study, de-esterification of apple pectin with acid treatment resulted in gel specification with higher molecular weight and viscosity. Acid treatment resulted in pectin with average molecular weight of 32000 Dalton. Pectin was extracted from sugar beet pulp by acid and alkali treatments. The quality of gel formation and water uptake was improved using sugar source (glucose), CaCl2 and peroxidase enzymes. The optimal levels of materials in formation of gelwith high water absorption capacity were: Glucose 5 %, Pectin 15 %, CaCl2 80mg/g, and enzyme unit 170 U/g pectin. The level of ingredients responsible for gel hardness was related to sugar content (glucose) of 15 %.

Carbon dioxide causes green house effect and has been considered as a pollutant source for safe environment. Since combustion of fossil fuel may create tremendous amount of carbon dioxide, detecting any pollutant sources would be important to eliminate the origin of pollution sources. Evaluation of smoke dispersion generated by the power plant utilizing fossil fuel is the objective of this paper. The concentration of NOx and SOx in the soil till a distance of 15 km from Neka power plant, have been analyzed. The maximum concentrations of SOx and NOx in the distance of 2.5 to 4 km from the power plant were 0.13 and 0.36 ppm, respectively. Replacement of fossil fuel (fuel no. 6, Mazout) bynatural gas may increase NOx concentration in the atmosphere; however the use of natural gas was recommend by environmental protection agencies as clean fuel. Use of natural gas may not be an actual solution for prevention of NOx pollution.

Motion-JPEG is a common video format for compression of motion images with highquality using JPEG standard for each frame of the video. During transmission through a noisy channel some blocks of data are lost or corrupted, and the quality of decompression frames decreased. In this paper, for reconstruction of these blocks, several temporal-domain, spatial-domain, and frequency-domain error concealment methods are investigated. Then a novel method is proposed for recovery of channel errors with a mixture of temporal-domain and frequency-domain error concealment methods. To reconstruct the missed blocks in the proposed novel method, when two successive frames are similar, a proposed two phase block matching algorithm is performed intemporal-domain. When two successive frames are different, our proposed method reconstructs the missed block by the estimation of DC and AC coefficient, in frequency-domain. The proposed method and the other similar methods are simulated for different noise and quality factors. The results of quality measurements are indicated that in all tested video sequences, the proposed method shows higher quality in reconstruction of missed blocks.

Cobalt Oxide/ Zinc Oxide nanocomposite was synthesized by dropwise addition ofCo(NO)3.6H2O and Zn(NO3)2.4H2O solutions to KOH solution at different temperatures followed by calcination at 300ºC for 4 h. The morphology and structure of nanoparticles and the influence of temperature on particle size were studied using scanning electron microscopy (SEM) and X-Ray Diffraction (XRD). Minimum particle size was obtained before calcination at 70ºC. In addition, the spherical, semispherical and flake-shaped nanoparticles were observed at ambient temperature. On the other hand, Co(OH)2 was transformed to Co3O4, ZnO flakes were eliminated, and particle size changed during calcination. Synthesized samples at 50ºC and 70ºC showed an increase size after calcinations; however, elimination of flakes during calcination caused particle size reduction forsynthesized sample at ambient temperature.

In this research, the effect of two process control agent: methanol (liquid state) and stearic acid (solid state) on mechanical alloying process of Ti and Al with equal at%(Ti50Al50) were investigated. Phase transformation at presence of two PCA was: at first, powder mixture was transformed to a metastable solid solution of Al in Ti lattice (disordered hcp) and then transformed to amorphous phase with increasing the alloying time. The results showed that the state and type of PCA is effective in expedition of mechanical alloying process. The metastable solid solution phase (dis. hcp) at presence of methanol was achieved more quickly than stearic acid was used. Changes in grain size, lattice strain, weight recovered and impurity content of milling parameters at presence of two different PCA were studied. At last with annealed of last product of alloying, the TiAl(γ) phase with high purity and nanostructured form were produced.

In this research, the Planetary mill was used for mechanical alloying (MA) of Ti and Alpowder mixture with equal at% (Ti50Al50). The effect of various factors, such as process control agent (PCA), speed of rotation of vial and ball-to-powder weight ratio, on process were studied and the best condition to synthesis the alloy was determined. Study on X-ray diffraction (XRD) patterns showed that at primary hours of milling, the powder mixture transmitted to metastable solid solution phase and with increasing the alloying time, that phase transformed to an amorphous, ultra fine grain and homogenous phase. Changes in grain size, lattice strain and impurity content during alloying and various condition were studied and at last with annealing of the product, the TiAl (γ) phase with high purity and nanostructered form was produced

Dynamic Analysis of an axially moving cable with time dependent tension and velocity isstudied in this paper. Tension force and the moving speed are assumed to be harmonic.It is found that there exists a specific value of speed in which natural frequency of the system approaches zero. This specific speed for such a critical condition is called critical speed and it will be proved that increasing the cable tension increases critical speed of the moving cable. Multiple-Scales perturbation technique is used to discretize the nonlinear equations of motions. Critical speeds are then obtained in which vibrations of motion become unstable. Stability analysis is carried out for different sets of excitation frequency. Dynamic responses of the system are calculated using Galerkin’s method. Acomprehensive parametric study is carried out and effects of different parameters like the moving speed and tension force on the responses are studied both in frequency and time domain.

In this paper, using 2-D theory of elasticity, a closed-form solution is presented for stressdistributions and displacements of a FG curved beam under shear force at its free end. The material properties are assumed to vary continuously through the radial direction based on a simple power law model and Poisson’s ratio is supposed to be constant. In order to verify the solution, it is shown that all stress and displacement relations are converted to those of a homogenous curved beam when the inhomogeneity constant approaches zero. The effects of inhomogeneity on stress distributions areinvestigated. It is shown that specified stress distribution profiles can be obtained by changing the variation of volume fraction of constituents. It is observed that for a specific value of inhomogeneity constant, a proper stress distribution along the radial direction is obtained for designing purposes.

In this article, an exact analytical solution for thermal buckling analysis of thin functionallygraded (FG) rectangular plates is presented. Based on the classical plate theory and using the principle of minimum total potential energy, the stability equations are obtained. Since the material properties in FG materials are functions of the coordinates (specially the thickness), the stability equations are coupled in terms of in-plane and out-of plane displacements. Introducing a new analytical method, the coupled stability equations are converted into independent equations. It is assumed that the plate is simplysupported on two opposite edges and has arbitrary boundary conditions along the other edges, so the Levy solution is considered. Two types of thermal loads, uniform and non-linear temperature rise through the thickness are considered as the loading conditions. Finally, the effect of aspect ratio, thickness to side ratio, index of FGM and boundary conditions on the critical buckling temperature of FG rectangular plates are discussed in details.