International Journal of Engineering
Year:2016 | Volume:29 | Issue:3 (TRANSACTIONS C: ASPECTS)|Papers Count:17

In this work, polyvinylchloride (PVC) membrane was prepared via casting solution technique and phase inversion method. N, N dimethylacetamide (DMAC) was used as primary solvent and tetrahydrofuran (THF) was used as a co-solvent. The effects of parameters such as membrane thickness, evaporation time of casting film before immersion precipitation and addition of polyethylenglchol (PEG) on PVC membrane were studied in terms of deionized water flux (DIW), tensile strength, phase inversion time in non-solvent, water content, permeability flux, salt rejection and antifouling properties.The results revealed that DIW decreased with increasing of membrane thickness and prior evaporation time of casting film. The phase inversion time increased with increase of membrane thickness and prior evaporation time. Tensile strength of fabricated membranes increased sharply while evaporation time was increased. The results showed the reduction of water content percent with increase of casting film evaporation time. Addition of PEG from 1 to 4 % wt improved flux sharply from 1.04 to 13.62 (L/m2.h). Rejection results showed reducing trend of salt rejection for fabricated membrane with different concentrations of PEG, except at the concentration of 3% wt PEG.The results clearly showed more stable permeation flux during filtration process for blend PVC/PEG membranes compared to PVC one.

In this work, the hydrodynamic behavior of a Kuhni extraction column has been investigated experimentally. The experiments were carried out in the absence of mass transfer for two different standard chemical systems. In the experiments operating variables including agitation speed, flow rate of both liquid phases and interfacial tension have been studied. Sauter-mean drop diameter, flooding velocity and holdup at flooding have been measured in the Kuhni column. The results showed that Sauter-mean diameter are strongly affected by agitation speed and interfacial tension whereas the effects of continuous phase and dispersed phase flow rates are negligible. Two rigorous empirical correlations are proposed for predicting flooding velocities and Sauter-mean drop diameterwith mean deviation of 5.7% and 7.2%, respectively. The mean drop size correlation is a function of column geometry, operating conditions and physical properties of liquid systems. Good agreement between predictions and experiments is found for all operating conditions investigated.

In this research, thin film heterogeneous cation exchange membrane was prepared by interfacial polymerization of polyacrylic acid-co-iron nickel oxide nanoparticles on PVC based substrate. Spectra analysis confirmed graft polymerization conclusively. The SEM images showed that polymerized layer covers the membranes by simple gel network entanglement. Results exhibited that membrane water content was decreased by graft polymerization of PAA/Fe2NiO4 nanoparticles on membrane surface.Membrane potential, transport number and permselectivity all were declined initially by PAA interfacial polymerization in NaCl ionic solution and then began to increase. The membrane transport number and permselectivity showed decreasing trend in bivalent (BaCl2) ionic solution. The sodium flux and permeability were improved sharply by PAA graft polymerization on membrane surface and then decreased slightly by graft polymerization of PAA/Fe2NiO4 nanoparticles. Different behavior was found for barium flux and permeability. Membrane areal electrical resistance was also decreased by introducing interfacial graft polymerization on membrane surface.

The demand for sustainable alternative construction materials to cement in modern technology cannot be underemphasized. This paper presents a non-fired green brick with an agriculture residue namely, rice husk. Although, high plasticity brown clay deposits are widely distributed in Malaysia and rice husk is a well known agriculture residue, research works on non-fired green brick with rice husk are relatively scarce. This research aims to investigate the strength development in non-fired bricks containing various amounts of rice husk. To achieve such aim, compression and flexural tests were conducted to evaluate compressive and flexural strengths of non-fired bricks. A series of brick specimens were cast with varying rice husk percentages. The test specimens were naturally sun dried. The effects of rice husk percentage (9-15%) and drying age (1, 7, 14, 21, and 28 days) on Atterberg limits; compressive strength; water absorption and flexural strength were investigated. The results indicate that, 12% rice husk is the optimum content to reach maximum 28-day compressive and flexural strengths of 10.4 MPa and 3.5 MPa, respectively. The results further showed that rice husk higher than 12% leads lower strength than control bricks for all the ages. In summary, it has been observed that rice husk enables a rapid strength development, enhancing the compressive and flexural strengths of the bricks. The results developed in this research work can contribute a cost-effective design of non-fired green brick as a sustainable building material.

Video magnification is a computational procedure to reveal subtle variations during video frames that are invisible to the naked eye. A new spatio-temporal method which makes use of connectivity based mapping of the wavelet sub-bands is introduced here for exaggerating of small motions during video frames. In this method, firstly the wavelet transformed frames are mapped to connectivity space and then decomposed into different spatial frequency bands by applying Laplacian Pyramid to determine the pixels having more chance to be a part of a movement. Finally each candidate is partially magnified based on its time history. The performance of the proposed method is evaluated on real videos which contain several subtle motions. Parameters for performance evaluation are presented and obtained results are compared with one of the state-of-the-art video magnification methods. Increased true positive rate parallel with simultaneous decrease in false positive rate confirms the effectiveness of the proposed method in amplifying subtle motions.

This paper is focused on a novel design of stepped diaphragm for MEMS capacitive pressure sensor used in tire pressure monitoring system. The structure of sensor diaphragm plays a key role for determining the sensitivity of the sensor and the non-linearity of the output. First, the structures of two capacitive pressure sensors with clamped square flat diaphragms, with different thicknesses are investigated and their sensitivity and non-linearity are compared together. Finally, for increasing the sensitivity and linearity, a new capacitive pressure sensor with a stepped diaphragm is introduced. A numerical solution for determination of the accurate sensitivity of the sensor is presented. The results show that the sensitivity of the sensor is increased from 0.063 fF/KPa in flat diaphragm to 0.107 fF/KPa in stepped diaphragm and also the non-linearity is decreased from 2.37 to 1.857%. In this design, the sensor sensitivity and output linearity are increased simultaneously

Diffusion tensor imaging (DTI) MRI is a noninvasive imaging method of the cerebral tissues whose fibers directions are not evaluated correctly in the regions of the crossing fibers. For the same reason, the high angular resolution diffusion images (HARDI) are used for estimation of the fiber direction in each voxel. One of the main methods to specify the direction of fibers is usage of the spherical deconvolution. The spherical deconvolution is a method which is very sensitive to noise and creates negative values in the orientation distribution function (ODF) of the fiber. To solve this problem, methods such as Laplace-Beltrami regularized spherical deconvolution (LB-SD), the gradient based spherical deconvolution (GB-SD) and the constrained spherical deconvolution (CSD) are used. In this paper, the method for SD based on Wiener filter (WB-SD) is presented. Regarding the results, the direction of the crossing fibers is specified correctly. The proposed algorithm has specified the direction of the fibers as zero degree with 4.9 standard deviation and 89.9 degree with 3.6 standard deviation against two crossing fibers with 90 degree angle.

In this article a new method is introduced for distinguishing roots and background based on their digital curvelet transform in minirhizotron images. In the proposed method, the nonlinear mapping is applied to sub-band curvelet components followed by boundary detection using energy optimization concept. The curvelet transform has the excellent capability in detecting roots with different orientations and contrasts, thanks to its better sparse representation and more directionality feature than existing approaches. Furthermore, adapting the parameters of the mapping function due to curvelet coefficients is very beneficial for magnifying weak ridges as well as better compatibility with different minirhizotron images. Performance of the proposed method is evaluated on several minirhizotron images in two different scenarios. In the first scenario, images contain several roots, while the second scenario belongs to no-root images, which increases the chance of false detections. The results show that the detection rate of the proposed method is 4 to 27 percent better than its alternatives, in presence of zero false detection. Furthermore, it is shown that better characterization of roots by proposed algorithm does not lead to extract more false objects compared to the results of the other examined algorithms.

The Dynamic Job Shop (DJS) scheduling problem is one of the most complex forms of machine scheduling. This problem is one of NP-Hard problems for solving which numerous heuristic and metaheuristic methods have so far been presented. Genetic Algorithms (GA) are one of these methods successfully applied to these problems. In these approaches, of course, avoiding premature convergence, better quality and robustness of solutions is still among the challenging arguments. The adapting of GA operators in amount and range of coverage can operate as an efficient approach in improving its effectiveness. In the proposed GA (GAIA), (1) the adapting in the amount of operators’ algorithm based on the solutions’ tangent rate for premature convergence is done. Then, (2) the adapting in the range of coverage of operators’ algorithm, in first step, happens by operators convergence on Bottleneck Recourses (BR) (which was detected initially) and, in the next step, occurs by operators convergence on the elite solutions so that the search process focuses on more probable areas than the whole space of solution. Comparing the problem results in the static state with the results of other available methods in the literature indicated high efficiency of the proposed method.

Currently, the research on emergency supplies distribution and decision models mostly focus on deterministic models and exact algorithm. A few of studies have been done on the multi-level distribution network and metaheuristic algorithm. In this paper, random processes theory is adopted to establish emergency supplies distribution and decision model for multi-level network. By analyzing the characteristics of the model, a modified discrete particle swarm optimization metaheuristic algorithm (MBPSO) is proposed to solve the problem. In MBPSO, appropriate degradation mechanism and parallel global search structure is designed. MBPSO has capability of global optimum search and fast convergence property for hybrid integer programming model with multi-constrained and weighted single objective.

This paper aims to find the efficient state of hybrid electric vehicle (HEV) by simultaneous optimization of the control strategy and the power train. The power transmission employed in this vehicle is a power-split continuously variable transmission (CVT) which uses several fixed ratio mechanisms. After describing this transmission, the rules of electric assist control strategy are introduced. A modification on this strategy is proposed to decrease the start/stop frequency of the engine and electric motor. Afterwards, an optimization on the HEV’s power train size, power-split CVT and the control strategy is accomplished with the aim of minimizing the vehicle fuel consumption and emissions. The optimization results are some Pareto-optimal points which are tradeoff solutions between fuel consumption and emissions. Finally, in order to intuitively demonstrate the optimality of the optimization results, the Pareto points for the case of considering two objectives are shown.

To overcome the space limitation of orifice-type and capillary restrictors in hybrid bearings, a kind of atypical long orifice-type restrictor is proposed and its experimental model is established. Through the analysis of the structure and flow rate of orifice-type restrictor and capillary restrictor, a long orifice-type restrictor and a feasible experimental modeling method are presented by use of orifice plate instead of the whole bearing. The flow rate of water film restrictors are tested under the aspect ratio of 4-10 and the pressure difference of 1.5-5.5 MPa and the experimental model of long orifice-type restrictor is established. The result shows that the restrictor of atypical structures needs to be modeled by experiment. The flow discipline of atypical restrictor is approximate to typical orifice-type restrictor and the throttling model is a nearly turbulent model.

In this paper, in order to limit the liquid sloshing effect on lateral dynamic of an articulated vehicle carrying liquid, an active roll control system is proposed. First, a sixteen-degrees-of-freedom nonlinear dynamic model of an articulated vehicle is developed then, using TruckSim software the model is validated. Next, the dynamic interaction of the fluid cargo with the vehicle, by integrating a quasidynamic slosh model with a tractor semitrailer model is investigated. In order to design the control system, sliding mode control is used. Also, to investigate the rollover stability of the vehicle, lateral load transfer ratio is considered as an important factor. The dynamic system performance for different filled volumes is exhibited in stepsteer and slalom standard maneuvers. The simulation results show that the proposed roll control system performs appropriately in target control achievement and lateral load transfer ratio reduction.

In the present work, an inverse analysis of combined radiation and laminar forced convection heat transfer in a two-dimensional channel with variable cross sections is performed. The conjugate gradient method is used to find the temperature distribution over the heater surface to satisfy the prescribed temperature and heat flux distributions over the design surface. The fluid is considered to be a gray participating medium with absorption, emission and isotropic scattering. The discrete ordinate method is used to solve the radiative transfer equation. The effect of radiation-conduction parameter is studied on the amount of heat transfer from the heater surface.

The axial force measurement plays an important role in tool designing and identification of its restrictions. Also, it is vital in design of machine mechanism and optimization of welding process parameters. In this study, a friction stir welded butt joint on AA7075-T651 aluminum alloy plate is investigated. With change of some parameters, factors including axial force, mechanical properties, microhardness and weld morphology, are studied. For measuring the axial force, load cell was utilized and a servohydraulic machine was applied to evaluate the mechanical properties. The results show that by increasing the welding speed and in the same rotational rate, the axial force and microhardness increase but the weld appearance quality decreases. However, by increasing the rotational rate in the same welding speed, there is not any certain relationship among the axial force, hardness and weld morphology. Also, by changing the tool tilt angle from zero to 2.5 degrees, the weld morphological feature is enhanced. The results illustrate that the proper change in welding speed and tool rotational rate have great effects on optimizing the welding friction stir process.

In the present study, small scale effect on critical buckling loads of triangular nano-composite plates under uniform in-plane compression is studied. Since at nano-scale the structure of the plate is discrete and the long-range cohesive forces become important, the size dependent nonlocal elasticity theory is employed to develop an equivalent continuum plate model for this nanostructure incorporating the change in its mechanical behavior. Two parameter Winkler-Pasternak elastic medium is used to precisely model the elastic behavior of the matrix surrounding the nano-plate. The governing stability equations are then derived using the classical plate theory and the principle of virtual work for a perfect uniform triangular nano-plate composite system. The well-known numerical Galerkin method is then used as the basis for the solution in conjunction with the areal coordinates system. The solution procedure views the entire nano-composite plate as a single super element which can be of general shape. Effects of nonlocal parameter, length, aspect ratio, mode number, anisotropy, edge supports and elastic medium on buckling loads are investigated. All of these parameters are seen to have significant effect on the stability characteristics of nano-composite plate. It is shown that the results depend obviously on the non-locality of buckled nano-composite plate, especially at very small dimensions, small aspect ratios, higher mode numbers, higher anisotropy and stiffer edge supports. Also it is seen that the medium parameters, especially the Winkler parameter, have significant influence on the small scale effect and can decrease or increase it. Also, it is seen that the classical continuum mechanics overestimates the results which can lead to deficient design and analysis of these widely used nanostructures. The results from current study can be used in design, analysis and optimization of different nano-devices such as nano-electro-mechanical systems (NEMS) utilizing nano-composite plates as load-bearing components. Although it is seen that nano-fillers, here the nano-plates, increase the stiffness of the whole nano-composite, by increasing the bending rigidities, on the other hand it is shown in this study that the small scale effect or the nonlocal effect decreases the critical loads of the nano-composite system. Thus, the nonlocal effect plays a key role in the design of these nanostructures and must be attended and comprehensively studied to avoid the failure of the nanostructure. Further, the solution employed here is general and can be applied to nano-composite plates with arbitrary shapes which is an asset in structural optimization.

This paper examines the generation and propagation of a third order solitary water wave along the channel. To study the wave propagation phenomenon, here, firstly the meshless Incompressible Smoothed Particle Hydrodynamics (ISPH) numerical method is described. Secondly, the boundary condition handling method, discretization, timestep selection and geometry provitions are presented.The numerical model is then used to simulate solitary wave propagation along the fixed depth channel.Here two still water depths of h=0.2m and h=0.3m are assumed and the dimensionless height of desired wave ranging from e=0.1 to e=0.6 are simulated. The numerical results are compared with analytical data in terms of free surface displacements, fluid particle velocity, phase speed, flow field counters and some other wave parameters. In general, the numerical model gives satisfactory results for the wave kinematics.