International Journal of Engineering
Volume:25 Issue: 1, Mar 2012

Pseudomonas aeruginosa BBRC-10036 was used for lipase production. The organism secreted the enzyme extracellulary. In order to purify the enzyme, precipitation was done first, and then this lipase has been purified by Ion exchange Chromatography leading to 2.3-fold purification and 11.47% recovery. Lipase from P.aeruginosa was entrapped into Ca-alginate gel beads and effect of independent variables such as alginate concentration (%w/v), CaCl2 concentration (M) and enzyme load (%v/v) on immobilization yield and activity of immobilized enzyme were investigated. Media optimization for immobilization of lipase was carried out by Response Surface Methodology. The optimum conditions were as follows: sodium alginate concentration 2.5% (w/v), calcium chloride concentration 2.5(M) and enzyme load 50% (v/v). At those conditions, the highest immobilization yield and the optimum activity of immobilized enzyme, respectively, obtained were 93.65% and 2.64 unit/gr(IME).

An experimental approach was carried out to study the time development and extension of scouring around a circular pier protected by a collar. The experiments included the study of scouring around an unprotected pier as well as the pier protected with collars located at different levels. Width of collars was 3 times the pier diameter. It was found that with collars, though the scour depth and the rate of scouring decrease, extent of the scour hole increases. Number of collars and their levels are effective factors on the equilibrium depth and extension of scouring. Different collar arrangements were tested for an optimum result. Best results were found with one collar at the bed level and another one at one pier diameter below the bed level. In this arrangement, scouring did not penetrate below the lower collar even after 200 hours. Therefore, with the lower collar at 1D below the bed level scour depth reduced by more than 50% whereas, the area of scouring increased by 30% compared with an unprotected pier.

The concept of floating submerged tunnels becomes increasingly attractive idea to cross the straits. The structural solution in these bridges includes buoyancy force on tunnel body plus tension in mooring tethers. This paper investigates the effect of submergence on the dynamic response of submerged floating tunnels due to moving load. The inertial effect of the fluid on the submerged structure is accounted for by evaluating the added mass in deep and shallow waters. Then the effect of moving load velocity on the dynamic amplification factor for mid span displacement is evaluated. The results show that while the inertial effect of fluid reduces the critical velocity, closely spaced tethers provides a means to increase this velocity and could be used to control the moving load effect. Although increasing the tether stiffness increases the critical velocity, at the same time it results in the escalation of the impact factor. It is also found that for tunnels of long in length the contribution of higher modes in the response becomes more and more important and closeness to the seabed in shallow strait crossings can result in the amplification of the moving load effect.

In this paper, nonlinear behavior of strengthened steel plate shear walls (SPSWs) by FRP laminates theoretically and numerically has been investigated. In the first part, a new method, “the composite-plate frame Interaction (C-PFI) method”, has been introduced to predict the shear behavior of the composite steel plate shear wall systems (CSPSWs). In the second part, several models of one-story unstiffened and strengthened SPSWs have been simulated in finite element software, and all specimens are subjected to quasi-static cyclic loading. Comparison between results of FEM method and C-PFI method show that theoretical formulations can properly predict nonlinear behavior of CSPSWs. FEM results show that with strengthening infill steel plate on the steel plate shear walls, yield strength, ultimate shear capacity and secant stiffness of SPSWs can be significantly increased. Moreover, in the all strengthened SPSW the amount of cumulative dissipated energy were increased.

The use of fractal geometry in designing antenna has been a resent topic of interest. Fractal shape has their own unique characteristics that the improved antenna performance can be achieved without degrading the antenna properties. Modern telecommunication system requires antenna having wider bandwidth and reduced size. Fractal antennas have become a hot topic of interest for the antenna designers because of their unique features like compact size, multi band operation etc. Now a days, the size of electronic system has decreased drastically whereas functionality has increased. The antennas have not experienced that evolution. Wireless communications have progressed very rapidly in recent years, and many mobile units are becoming smaller and smaller. To meet the miniaturization requirement, the antennas employed in mobile terminals must have their dimensions reduced accordingly. Several researchers studied and suggested the incorporation of fractal antenna is advantageous as the space filling properties of antenna leads to the miniaturization of the antenna. Fractals have non-integral dimensions and their space filling capability could be used for miniaturizing antenna size. Fractal antennas have improved Impedance, improved SWR (standing wave ratio) performance on a reduced physical area when compared to non fractal Euclidean geometries. In many cases, the use of fractal element antennas can simplify circuit design. Often fractal antenna, do not require any matching components to achieve multiband or broadband performance. Perturbation could be applied to shape of fractal antenna to make it to resonate at different frequency. Another beneficial factor of fractal antennas is that they are in form of a PCB.The objective here is to give the description of designing and simulation of a microstrip patch Fractal Antenna. The behavior and properties of this antenna are investigated and compared with the simple microstrip patch antenna. Different iterations were considered to miniaturize the size of antenna without degrading the antenna performances. In theoretical design procedure, numerical simulation was performed using software Ansoft HFSS v 11.

In acceptance sampling plans, the decisions on either accepting or rejecting a specific batch is still a challenging problem. In order to provide a desired level of protection for customers as well as manufacturers, in this paper, a new acceptance sampling design is proposed to accept or reject a batch based on Bayesian modeling to update the distribution function of the percentage of nonconforming items. Moreover, to determine the required sample size the backwards induction methodology of the decision tree approach is utilized. A sensitivity analysis that is carried out on the parameters of the proposed methodology shows the optimal solution is affected by initial values of the parameters. Furthermore, an optimal design is determined when there is a limited time and budget available and hence the maximum sample size is specified in advance.

In this paper, a dynamic optimization approach for optimal choice of energy carriers in thermal power plants is proposed that analyzes the substitution of energy carriers in short-term planning of a power plant.The model is based on the linear programming method with the objective of minimizing costs under constraints of resource availability, energy balances, environmental regulations and electricity production needs.The restriction of resource availability in cold months (due to the depletion of gas pressure)is also considered.This research tries to demonstrate the application of a model for the determination of efficient substitutes and optimization of their consumption in two thermal power plants in Iran as case studies. In these case studies, the reasonable solutions for dynamic planning of substitution of energy carriers in two power plants have been obtained. Furthermore in this paper, the effect of uncertainties in the fuel price on the a model is examined. Thus, a fuzzy linear programming model with fuzzy objective coefficients is formulated and finally for one of the power plants, the model is solved as a case study and its results are compared with the results of the crisp model.

The optimal shape of a two dimensional turbulator above an isothermal flat plate is found by using numerical simulation. The turbulent boundary layer over the flat plate was disrupted at various situations by inserting a quadrilateral bar where the boundary layer thickness kept more than three times greater than the insert\\\'s height. As a result, the overall heat transfer coefficient of the wall as well as the skin friction coefficient was altered. The single objective Genetic Algorithm (GA) coupled with the modified Teach-t code were employed to optimize the shape and distance of the obstacle from the plate. When the optimal geometry employed, the mean heat transfer coefficient is enhanced by more than 51% over the affected area. Flow features around the quad, each makes its own contribution to the heat transfer change. The stagnation point formed on the frontal face of the body accounts for the slight decrease in the heat transfer coefficient, while the jet underneath the obstacle followed by the developing boundary layer are responsible for the sudden increase of the heat transfer coefficient. However, the downstream wake zone makes the main and widespread contribution.

The final hot strip profile is a superposition of the roll initial crown, the roll bending and flattening crown, the roll wearing crown and the roll thermal crown. In this research, linear regression models are proposed to predict the roll force, the roll wearing crown and the roll thermal crown using experimental data provided by Mobarake Steel Complex (MSC). The short beam theory based on elasticity approach is also used to predict the roll bending and flattening crown. Finally, the work roll initial crown in order to obtain desired strip profile in hot rolling is predicted utilizing a computer programming. The obtained initial crowns are then used for seven stands of an actual roll schedule for hot strip mill of MSC. The measured strip profile shows a good agreement with the desired one for the mentioned mill.