International Journal of Engineering
Volume:26 Issue: 5, May 2013

Three common pretreatment processes based on dilute sulfuric acid, dilute sodium hydroxide and heat treatment (autoclaving) followed by enzymatic hydrolysis were evaluated to provide comparative performance data. Among them, the best result was obtained when the pretreatment of rice husk was carried out with 3% of NaOH solution. The pretreatment of rice husk with NaOH substantially increased the lignin removal, enzymatic digestibility of cellulose, the accessibility of cellulose and fermentable sugar production. The highest glucose concentration, glucose yield and ethanol concentration were 14.54 g/L, 59.6% and 6.22 g/L; which were 5.44, 3.77 and 6.15 times higher than the untreated control samples, respectively. Moreover, the SEM analysis of the pretreated sample illustrated significant physical changes of the rice husk after NaOH pretreatment.

Due to changeable nature of the industrial wastewaters, proper operation of an industrial wastewater treatment plant is of prior importance in order to keep the process stability at the desired conditions. In this mean, simulation of the treatment system behavior using artificial neural network (ANN) can be an effective tool. This paper evaluates long term performance and process stability of a full-scale integrated industrial wastewater treatment system (Faraman’s industrial estate, Kermanshah) in removing organic matter over a 2-year operation. The wastewater treatment system is composed of static screens, an equalization tank, an aerobic biological tower (TF) and an activated sludge (AS) reactor. Multilayer Feed-forward Networks of ANN was used to forecast the process performance of AS system. In this study, mixed liquor suspended solids (MLSS) (mg/l) and organic loading rate (OLR) (kg COD/m3.d) were selected as input parameters and TSS removal, COD removal and sludge volume index (SVI) as output parameters. The results showed a very good agreement between the actual and modeled data (R2 0.9). The ANN models provided a robust tool for prediction the performance of wastewater treatment plants and as a result, the online monitoring parameters could be applied on prediction of effluent.

Highly ordered mesoporous MCM-41silica with hexagonal structure was synthesized using extracted amorphous silica from sedge (Carex riparia) ash. Obtained mesoporous materials functionalized by 3-(Aminopropyl) trimethoxysilane (APTMS) and their structures characterized by means of X-ray diffraction (XRD), nitrogen adsorption-desorption, thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. As-synthesized material were applied for adsorption of Cd(II) metal ions from aqueous solution in batch and fixed bed column systems. Batch adsorption process was carried out to evaluate initial ion concentrations, sorbent dose, contact time, pH and temperature. The equilibrium data were analyzed using the Langmuir and Freundlich isotherm by nonlinear regression analysis. The kinetics study reviled that data from the experiments fitted well to the pseudo-second order equation than pseudo-first order. Thermodynamic parameters reviled that the adsorption process strongly depended on temperature and the adsorption capacity increased by increasing the temperature of the system, indicating the endothermic behavior and spontaneous nature of adsorption. For continuous adsorption experiments, NH2-MCM-41 adsorbent was used and breakthrough curves were analyzed at different bed heights, flow rates and initial metal ion concentrations. The Thomas and bed depth service time (BDST) models were used to determine the kinetic constants and to predict the breakthrough curves of each component.

Subcritical water extraction (SWE) of essential oil from Matricaria Chamomilla L. (M. Chamomilla L.) was performed and compared with conventional method including hydro distillation. The percentage of main extracted components of different temperatures (100, 125, 150 and 175 oc) and water flow rates (1, 2 and 4 ml/min) were investigated at 20 bar pressure and 0.50 mm mean particle size in SWE. The separation and identification of the components were carried out by gas chromatography (GC)-flame ionization detection and GC-mass spectrometry. The best operating conditions for the SWE of M. Chamomilla L. were determined to be at 150 oc temperature and 4 ml/min flow rate for 120 min extraction time. In comparison with hydro distillation method, the SWE method resulted in a more valuable essential oil with respect to the oxygenated components.

The structural and bleaching properties of nitric acid-activated Nteje clay was studied to investigate its ability to serve as an alternative to the high cost imported bleaching earth. The clay was mined, sun-dried, grinded, and reacted with different concentrations of nitric acid, ranging from 2 mol.L-1 to 15 mol.L-1. The un-activated and activated samples were characterized to study the structural effects of the activation process. The activated samples were employed in bleaching palm oil under controlled conditions of the process variables. The characterization results showed that the surface area, cation exchange capacity (CEC), and oil retention properties of the activated samples were affected by the activation reaction. The surface area increased to about 4 times (288.8 m2.g-1) the initial value (68.5 m2.g-1), while the CEC decreased from 154 to 65 meg.100-1g-1 with acid activation. The bleaching studies revealed that the activated clay samples adsorbed color pigments from palm oil more than the un-treated clay sample, with the bleaching efficiency of the sample activated using 13 mol.L-1 HNO3 increased from 37.82 % to 89.76 %. This study has shown that nitric acid can favourable be employed in activation of Nteje clay to improve its bleaching ability and that the activated samples can serve as an alternative to the imported bleaching earths.

Due to lack of theory of elasticity, estimation of ultimate torsional strength of reinforcement concrete beams is a difficult task. Therefore, the finite element methods could be applied for determination of strength of concrete beams. Furthermore, for complicated, highly nonlinear and ambiguous status, artificial neural networks are appropriate tools for prediction of behavior of such states. The main purpose of this paper is evaluation of ultimate torsional strength of rectangular concrete beams using two different approaches: nonlinear finite element modeling and artificial neural network prediction. This aim is achieved by creating a three-dimensional finite element models that employing the brittle failure criterion of concrete and an artificial neural network which training is carried out through experimental data. Numerical modeling is accomplished using the commercial software and its validation is exhibited by selected data from experimental tests. The test specimens were solid rectangular beams that were subjected to pure torsion. All of the experimental data for training of the network has been comprised. Data are divided into three categories: training, testing and validating. Three-layer perceptron network with a back propagation error algorithm is used for training. This study shows that, the results of numerical models are more accurate than neural network models to predict torsional strength of reinforced concrete beams.

A prismatic beam made of a behaviorally nonlinear material situated on nonlinear elastic foundation is analyzed under a moving harmonic load moving with a known velocity. The vibration equation of motion is derived using Hamilton principle and Euler Lagrange equation. The amplitude of vibration, circular frequency, bending moment, stress and deflection of the beam can be calculated by the presented solution. Considering the response of the beam, in the sense of its resonance, it is found that there is no critical velocity when the behavior of the beam and foundation material is assumed to be physically nonlinear, and in this case there are finite values for the deflection, stress and bending moment of the beam.

Regarding the reported capabilities and the simplifications of the smoothed particle hydrodynamics (SPH) method, as a mesh-free technique in numerical simulations of the deformation processes, a 2-D approach on cold rolling process was provided. Using and examining SPH on rolling process not only caused some minor developments on SPH techniques but revealed some physical realities. The chosen test case for rolling is an aluminum strip: Al 6061. In this way, the rolls assumed to behave as rigid bodies and, the aluminum strip assumed to behave as an elastic-plastic continuum. In order to achieve the required assurance of the employed technique, the computed stress distribution patterns were compared with those reported from a finite element study, and the results showed good agreements. Moreover, as the final main test, the effect of some affective parameters; roll diameter, percentage of thickness reduction of the strip, and the rolling speed has been studied. In current study not only some developments of using the SPH technique were achieved, but also, could present the capability of the SPH for more simple numerical approaches for such complicated deformation processes

In the present study, a modified Structure Function was introduced. In this modified Structure Function model, the coefficient of model was computed dynamically base on the coherent structure in the flow field. The ability of this Modified Structure Function was investigated for complex flow over a square cylinder in free stream and a low aspect ratio cylinder confined in a channel. The Results was compared with experimental data, standard structure function and Coherent Structure Model which use a dynamically method to computed the coefficient of Smagorinsky model based on coherent structure in the flow field. The results show that Modified Structure Function improved the stability and accuracy of simulation in comparison to Coherent Structure Model and standard structure function model.

An investigation has been made to analyze the effects of viscous dissipation on the heat transfer characteristics for both hydro-dynamically and thermally fully developed, laminar shear driven flow between two infinitely long parallel plates, where the upper plate is moving in an axial direction at a constant speed. On the basis of some routine assumptions made in the literature, a close form analytical expression of Nusselt numbers for the flow of Newtonian fluid with constant properties has been developed for three different cases of constant heat flux boundary conditions. In the analysis, focus is on the viscous dissipative effect due to the shear produced by the moving upper plate apart from the viscous heating due to internal fluid friction for the flow of a Newtonian fluid.

In this study, a real and significant industrial problem in a steam power plant was investigated. Reheater tubes in boilers are under the creep and the fireside corrosion mechanism that cause some of them to fail. Since the estimation of probability of failure (PoF) and remaining life (RL) is expensive and time consuming in the deterministic methods, in this work they were evaluated using structural reliability analysis and distribution analysis based on in-site tests and selecting an appropriate limit state function (LSF).The criterion used for this purpose is based on the creep lifetime model and uncertainties. Sensitivity analysis was also studied in this research. The considered relationship among three affecting parameters on boiler tube failure including time, creep and fireside corrosion leads to evaluating RL besides PoF as well as obtaining PoF and RL simultaneously by selecting an appropriate time-based LSF. Most accurate results were achieved based on obtained PoF and RL values which cause to provide more reliable results for economic planning of future inspection periods. This leads to significant cost savings and operational safety improvements. A new software package, named RALA was developed via programming in Matlab. The obtained results are in good agreement with all data gained from the practical experiments in the power plant based on the previous studies.

In the most application of nozzle with gas-liquid two-phase flow, the quality of mixture in exhaust of nozzle is the most important parameter as well as the flow velocity. On the other hand, in some industrial application, such as water injection in forced induction (turbocharged or supercharged) internal combustion engine the spray quality is the main goal of designing. In this case and for improving of injection performance the air-water two phase nozzle injection flow is more remarkable subject. There are two ways for this purpose, premixed or un-premixed air-water in entrance of the nozzle. In both cases, the nozzle not only has to accelerate gas and liquid to extra high velocity, but also it is supposed to have a high quality mixture in exhaust of nozzle. In this study, the turbulent gas-liquid two-phase premixed/un-premixed flow through the nozzle is simulated by the Eulerian-Lagrangian approach. The gas phase is treated as a continuum by solving the time-averaged Navier-Stokes equations, while the liquid as a dispersed phase is solved by tracking a large number of droplets through the calculated flow field. The pressure, velocity and Mach number profiles as well as air flow-rates and particle residence time inside the nozzle for various back pressure values have been computed. This work has been validated by comparison of pressure profiles and air flow-rates between simulated results and available experimental results for un-premixed nozzle flow.