International Journal of Engineering
Volume:29 Issue: 1, Jan 2016

In the present work, nano-NaX zeolite and micro-NaX zeolite were synthesized via hydrothermal method. Then, the adsorption capacities and isotherms of pure gases CO2 and CH4 on the synthesized zeolite nanoparticles were determined at three temperatures of 288, 298 and 308 K and various pressures from 1 up to 20 bar. Adsorption capacities of CO2 on the nano-sized zeolites NaX were higher than CH4. The selectivity of CO2/CH4 of the nano-sized zeolites NaX was 5.47 at 288 K and pressure of about 20 bar. The results of the experimental data followed the Langmuir Frendlich adsorption isotherm. Reduction of the particle size from micrometer to nanometer resulted in increasing the adsorption capacity for carbon dioxide on the X zeolite nanoparticles about 28% (from 5.067 to 6.536 mmol/g) at 288 K and 20 bar.

Non-Structural elements such as mechanical, electrical and architectural elements always posses serious damage potentials during earthquakes. Degree of damage imposed by the non-structural elements is not usually measured by the physical damages caused, but more so by the amount of the economical and functional disruptions created in a built environment. This phenomenon is enhanced where the functional performance criteria used for the specific site should be of higher standards, meaning for example the “immediate use” criteriaIn order to account for this sort of possible interruptions and plan for the worst case scenario during an earthquake in a thermal power plant in Iran. A study was carried out to evaluate the seismic vulnerability status of non-structural components of the main control building in this power plant. Level one and two assessment methods, namely; rapid and detailed evaluations were used. Three main documents considered for this evaluation were the MCEER, FEMA-310 and FEMA-356 recommendations. The method used and the results obtained which are classified into four hazard levels namely; very high, high, intermediate and low are to be presented in this paper.

Bend existence causes changes in the flow pattern, velocity and the water surface profile. The ability to simulate three-dimensional flow pattern is an important and significant issues in curved channel. In the present study, using three-dimensional model of computational fluid dynamics (CFD) and artificial neural network (ANN) model of multi-Layer perceptron (MLP), two velocities and pressure variables on the channel bed with 90º sharp bend is predicted and compared. Also extensive experimental work has been conducted to measure the flow variables in this bend. Experimental results are used to train and test the neural network model accordingly. Comparison of the numerical with experimental results show that CFD model with average Root Mean Square Error (RMSE), 0.02 and 0.13 and ANN model with R2 (determination coefficient) value, 0.984 and 0.99 to predict velocity and pressure respectively, has reasonable accuracy. Also, velocity pattern and flow pressure with both numerical (CFD and ANN) models at any point of the field channel is predictable. Comparison of the CFD and ANN models show that the ANN model with the average value of Mean Absolute Error (MAE), 0.048 to CFD model with the average MAE, 0.06 in prediction of velocity and pressure has more accuracy. The present neural network with less time and cost in designing and implementation of curved channels than other expensive and time consuming experimental and computational models can be used.

In this paper a simple tool for seismic design of steel structures for a selected ductility level is presented. For this purpose, a consistent set of earthquakes is selected and sorted based on the maximum acceleration of ground surface. The selected records are applied as the base motion to a single-degree-of-freedom system with strain hardening and the maximum response acceleration is determined for three levels of ductility. The response results of the nonlinear dynamic analysis are presented in the shape of the maximum acceleration of the system versus the peak ground acceleration for a certain ductility demand. Using these graphs, the maximum acceleration and base shear of the system are calculated by accounting for its nonlinear behavior, hence eliminating the need for the response modification factor. This is the main advantage of the presented diagrams for nonlinear seismic design of steel moment frames.

Magnetic resonance imaging (MRI) is one of the most powerful techniques to study the internal structure of the body. MRI image quality is affected by various noises. Noises in MRI are usually thermal and mainly due to the motion of charged particles in the coil. Noise in MRI images also cause a limitation in the study of visual images as well as computer analysis of the images. In this paper, first, it is proved that probability density function (PDF) of MRI images is rician because of the process of image capturing and MRI hardware. Based on the review of later works in this area, it is determined that rician denoising in wavelet domain is better. Then, it is concluded that the remaining noise in the final output of the conventional methods in wavelet domain, is Gaussian and can be greatly reduced with a Gaussian adaptive filter. Based on this estimation, a Gaussian filter designed and the output image was filtered again. The results showed that the final image quality will improve considerably. As a conclusion, in similar situations, our proposed algorithm is always better than the others.

This paper studies power management in a grid-tied hybrid energy system consisting of photovoltaic array, wind turbine, fuel cell, electrolyzer, hydrogen storage tank and a combinational heating system to supply the thermal and electrical demand of a building. Moreover, the hybrid system is capable of exchanging power with local grid. Thus, variable daily buying and selling tariffs are also taken into account so as to cover a wide range of operational conditions. The thermal demand is supplied by both electric heating system and the fuel cell exhaust heat. The paper formulates the matter in the form of a nonlinear constrained optimization problem and then evaluates several well-known heuristic optimization techniques. The performance of each of these algorithms is discussed in detail and the elite algorithm is introduced. Furthermore, the effect of the initial charge of the hydrogen storage tank on total operation cost and also charge remained are fully discussed. In order to fulfill this intention, a novel criterion is presented to determine the optimal initial charge. The validation of the results will be implemented based on simulations.

In this study, a fractal, Y-shaped dual-mode resonator bandpass filter (BPF) with input-output cross-coupling is introduced. A parallel-coupling feed structure with a cross coupling has been used to generate two transmission zeroes (TZs) near the lower and upper cutoff frequency that can effectively improve the passband edge selectivity. Also, a fractal shaped based on conventional diamond and square is located. Current density and equivalent model is also given depending on the odd/even excitation resonance condition. The demonstrated filter with a compact size of 0.5*18.3mm2 exhibits a fractal bandwidth of 67% centred as 6GHz (f0) within the 4 to 8GHz bandwidth and minimum insertion loss of 0.3 dB, maximum return loss of 13,15.7dB and flat group delay around 0.3ns that is candidate for use in commercial communications satellites (C-Band).

With a focus on investigations in the area of overactuated spacecraft, a new high-performance robust three-axis finite-time attitude control approach, which is organized in connection with the quaternion based estimation scheme is proposed in the present research with respect to state-of-the-art. The approach proposed here is realized based upon double closed loops to deal with the angular rates of the system, in the inner loop, and also the rotational angles of the system in line with the corresponding quaternion, in the outer loop, synchronously. With this goal, a combination of linear and its non-linear terms through the sliding mode control approach and also the proportional derivative based linear quadratic regulator control approach is organized. There is the white measurement noise to be realized the outcomes in such real situations, where it is coped with through the optimal estimation scheme to be designed, correspondingly. The results are organized with regard to the pulse modulation synthesis through the technique of the pulse width pulse frequency to manage a set of on-off reaction thrusters, as long as the control allocation is employed to handle the aforementioned overactuated system under control. The effectiveness of the approach investigated is finally considered in line with a series of the experiments to be tangibly verified.

In this study, montmorillonite (MMT) modified with a cationic surfactant (Hexadecyl trimethyl ammonium bromide, (HDTMA)) was used for the removal of methyl red (MR) from aqueous solution. The effect of different parameters like surfactant loading rate, contact time, pH, adsorbent dosage and initial MR content was investigated on the sorption. The sorption capacity was increased by increasing the surfactants loading rate up to 120% cation exchange capacity (CEC) of the MMT. The optimum uptake capacity of the sorbent (84.28 mg/g) was achieved within 30 min at pH of 6. The experimental data of the sorption was well fitted by pseudo-second-order kinetic and Freundlich isotherm models. The results showed that the HDTMA-MMT can be applied as an effective and inexpensive sorbent for the removal of MR from aqueous solution.

The purpose of this study is to consider an international facility location problem under uncertainty and present an integrated model for strategic and operational planning. The paper offers two methodologies for the location selection decision. First, the extended VIKOR method for decision making problem with interval numbers is presented as a methodology for strategic evaluation of potential countries based on international economic indicators available in the Global Competitiveness Report. Then, regarding these assessments and several quantitative factors, a set covering multi-objective optimization model is presented to consider additional operational criteria in decision making process. An efficient approach for location finding and a novel application of combined VIKOR and global criterion methods can be considered as the main contributions of this paper. Incorporating the theories of international economics in Operations Research models is another contribution of the paper.

The scientific importance of nanocomposites is being increased due to their improved properties. This paper is divided into two parts. First, Al-Al2O3 nanocomposite was produced by using ball milling technique followed by cold compaction and sintering. Microstructure and morphology studies were done through SEM, TEM, and EDX analyses on the produced powder. The mechanical properties of the produced composite were determined by the tensile test. Also, nano-indentation experiment was conducted on the produced composite to determine its hardness. Second, a 2-D axisymmetry model was implemented in ANSYS software to simulate the nano-indentation experiment on pure aluminum and Al-Al2O3 nanocomposite. A conical indenter with 70.3◦ was considered in simulations. The results show that, a homogenous distribution of the reinforcement in the matrix was achieved after 20 h milling. The elastic modulus, yield strength, and the hardness of the produced composite were increased compared to the pure metal. The finite element (FE) simulation results showed a good agreement with the experimental results for nano-indentation experiment. The scatter of the FE results from the experimental results in the pure metal was smaller than that observed for the nanocomposite.

Flash-boiling atomization is one of the most effective means of generating a fine and narrow-dispersed spray. Unless its complexity, its potential has not been fully realized. In this paper, a three dimensional chamber has been modeled with a straight fuel injector. Effect of flash-boiling has been investigated by computational fluid dynamics (CFD) techniques. A finite volume approach with the standard k–ε turbulence model has been used to carry out all the computations. The dimensions of studied vortex tubes are kept the same for all models. Finally, some results of the CFD models are validated by the available experimental data which show reasonable agreement, and other ones are compared qualitatively. It is confirmed that flash-boiling effectively accelerates the atomization and vaporization of fuel droplets.

High-speed maglev train is considered an ideal vehicle in the 21st Century. The travel mechanism as an important part of the train, bears and delivers a variety of vertical and horizontal alternating load in operation. It affects the operation safety of the train directly, so key components of the travel mechanism should be under fatigue strength test by fatigue test machine. The paper proposed a variable frequency pump control fatigue test machine for high-speed maglev train. It simplified the structure and improved the stability and reliability by using variable frequency pump control technology to regulate the velocity of the motion of hydraulic cylinder. Introducing the operating principle of the system, established the simulation model including frequency converter, electromotor and hydraulic system. The system performance in the cases of variable load and variable speed is analyzed with the SIMULINK of MATLAB. The system is verified correct and feasible by comparing simulation results with the actual situations. Finally, control performance of the model system was optimized by using PID closed-loop controller as well. The variable frequency pump control fatigue test machine achieved high response and high energy efficiency, so it is suitable for fatigue test application.

Deep drawing process is one of the most applicable methods in producing industrial parts. In this process, the initial blank deforms to final product using a rigid punch and die. In this investigation, the effect of deep drawing process parameters of brass/steel laminated sheet composites on required forming force has been investigated. The process simulated using finite element method (FEM) and then validated by using experimental results. Afterward, the effect of process parameters including friction coefficient between punch and sheet (punch friction), friction coefficient between die and sheet (die friction), blank holder force and the initial blank diameter all in three different levels investigated using design of experiments (DOE) by Taguchi method. Based on four selected parameters in three levels, experiments performed by Taguchi L9 orthogonal array and then the maximum punch force of each experiment was obtained using validated FE model. Signal to noise (S/N) analysis demonstrated that the die friction is the most important parameter in deep drawing of brass/steel laminated sheet that by its reduction, the maximum punch force decreases. Also, analysis of variance (ANOVA) results illustrated that the die friction and initial blank diameter are involved 53.1 and 43.4% of contribution on maximum punch force, respectively.

Literature about entropy generation analysis of a wavy enclosure is surprisingly scarce. In this paper, a FORTRAN code using an explicit finite-volume method is provided for estimating the entropy production due to the natural convection heat transfer in a cosine wavy absorber solar collector. The volumetric entropy generation terms -both the heat transfer term and the friction term, were straightly calculated. The solution was conducted assuming the isothermal boundary conditions of the absorber and the cover of solar collector. The results were obtained for Rayleigh numbers from 10 to 105. The simulation results were compared with a flat plate absorber. It was found that, with increasing the cosine wave amplitude, the collector enclosure irreversibility decreases.

In this study, the mixing phenomena in a physical model and fluid dynamics in a copper converter were experimentally investigated using a physical model. The physical model is a 1:5 horizontal tank made of Plexiglas. The mixing phenomena were characterized by experimentally measuring the mixing time using a tracer dispersion technique. Moreover, the effects of the air flow rate and lance submergence on the slopping in the model were studied. The experiments were carried out for the air flow rates of 10, 15, 17 and 20 l/min with the lance submergences of 8.5, 9.5, 10.5 and 11.5 cm. The results showed that the mixing time decreased with increasing both air flow rate and lance submergence. In addition, the slopping reduced as the lance submergence increased while the air flow rate decreased. Based on the results of the mixing time and the slopping, an optimum condition for air injection was obtained which not only ensured the sufficient mixing, but also resulted in less slopping in the model. Furthermore, the mixing times were evaluated in terms of the specific mixing power. A correlation was established for estimating the mixing time in the model with respect to the specific mixing power.

The primary job of cement is a critical step in successful well completion. To achieve effective cementing job, complete mud removal from the annular space is recommended. Spacer and flushers are used widely to achieve this goal. This study is about weighted cement spacer systems containing a surfactant package, weighting agent and rheological modifiers. Weighted spacer systems are utilized when a high formation fluid pressure is expected inside the wellbore. A testing program is conducted in laboratory to determine the spacer fluid rheological properties at different temperatures. The measured rheological properties are estimated using the known rheological models. Each model is firstly optimized using genetic algorithm as an optimization tool and then the rheological properties are modeled. The performance of the genetic algorithm is then tested by comparing the real laboratory data and modeled data. The results show that the polymer based spacer systems are better described using Herschel Bulkley Model. Also, it is concluded that the genetic algorithm with a good formulation can be used as an effective optimization tool to predict the rheological properties of the spacer systems.

Natural indicators of the electrical polarity of a direct current (DC) source is limited to semiconductor based diodes and transistors. Recently a novel bio-natural indicator of the polarity of a DC source have been reported. Mimosa Pudica or sensitive plant is found to be a natural detector of a DC source polarity, however the mechanism underlying this phenomenon is not known. This paper aims to develop a physical and engineering based model to explain the mechanism of this phenomenon. This model suggests that spatial placement of ion release sites along the pathway of electric signal is crucial to obtain polarity effects. A combination of this spatial placement of ion release sites and a delay in the opening of K+ ion channel with respect to Cl- ion channel can explain this one-way switch behavior.