International Journal of Engineering
Volume:31 Issue: 7, Jul 2018

The capture efficiency of the small aerosol particle is strongly influenced by the structure of fibrous layers. This study presents particle deposition and dendrite formation on different arrangements of binary fibers. 2-D numerical simulation is performed using the open source software of OpenFOAM. In the instantaneous filtration of a single fiber, obtained results are in good agreement with the existing model. Results showed that addition of nanofiber to microfiber led to high capture efficiency for the particle size 50nm at the cross arrangement with fibers distance 2µm. When particle gets larger, i.e. 150 nm, binary fibers have higher capture efficiency and pressure drop than the single microfiber at all arrangements, especially for the fibers distance 1.5 µm. Therefore, the good fibers arrangement here seems the cross arrangement with the high capture efficiency, average pressure drop and fibers distance 2 µm.

This research paper describes the study of combined effect of Fly Ash (FA) and Rice Husk Ash (RHA) on properties of concrete as partial replacement of Ordinary Portland Cement (OPC). These by-products are having high pozzolanic reactivity. In this research, the composition of mix was used with 10% RHA along with 10, 20 and 30% FA as partial replacement of cement. In this study, the compressive strength, workability, durability performance, and microstructure of concrete were examined. The microstructures of the concrete sample were analyzed by Scanning Electron Microscope (SEM) and elemental contents by Energy Dispersive X-ray (EDX). The test results showed that the highest compressive strength was achieved by 10%RHA and 20%FA used and beyond that, the strength was shown similar to control concrete mix (CM). The Ultrasonic Pulse Velocity (UPV) test result values were above the 4.5km/s; hence it may be considered as excellent concrete as per IS code for all mix. Response Surface Methodology (RSM) was adopted for optimizing experimental data. Regression equation was yielded by the application of RSM relating response variables to input parameters. This method aids in predicting the experimental results accurately with an acceptable range of error. This type of concrete mix is very effective in enhancing the mechanical and durability properties of concrete by saving cement and cost. It also makes concrete sustainable as it reduces environmental problems.

In structural analysis, the base of structures is usually assumed to be completely rigid. However, the combination of foundation and the subsurface soil, makes in fact a flexible-base for the soil-structure system. It is well-known that the structural responses can be significantly affected by incorporating the Soil-structure Interaction (SSI) effects. The aim of the present study is to provide more accurate structural responses analysis by considering the influence of SSI. It is noteworthy that the input ground motion records imposed to the combination of the soil, foundation and structure were selected in a such way that their characteristics were completely matched with the subsurface soil of structures. For this purpose, 3, 6, 9, 12, 15, 18 and 20-storey structures resting on a shallow foundation were selected and the concept of Beam on Nonlinear Winkler Foundation (BNWF) model is employed. The seismic responses of these structures were calculated based on the five different types of soil and the outcomes were compared with those from fixed-base structures. A set of 35 ground motion excitations recorded on different soil types, is selected which categorized to 5 sets consist of 7 records. Non-Linear Response History Analysis (NL-RHA) was performed and radiation damping considered for all of the structures and soil types. The results clearly showed that the inter-storey drift ratio was reduced in lower stories considering SSI effects. These effects are strongly increased, especially with increasing the slenderness ratio of the structures and softening the subsurface soil. Finally, the period lengthening ratio of studied structures, for various soil types was investigated.

In this study, through series of shaking table tests and statistical analysis, the efficiency of Uniform Tuned Liquid Column Damper (UTLCD) in structures resting on loose soils, considering soil-structure interaction was investigated. The soil beneath the structure is loose sandy soil. The Laminar Shear Box (LSB) as a soil container was adopted and the scaled form of the prototype structure namely model structure using scaling laws was built. Applying selected earthquake record the top story displacement of the soil-structure model was obtained. In the rest of the tests, the soil-structure model was equipped with UTLCD and tested. 3 different in sizes of UTLCDs, each with different blocking ratio and frequencies was used. To implement tests, completely randomized factorial design, with factors of Blocking ratio, Frequency and Type of the UTLCD was adopted. Through statistical analysis of the experimental tests was demonstrated that the mentioned factors are effective in response of the structure. Using Response Surface Methodology (RSM), the optimum values of the factors to minimize the top story displacement has been found. In this study it was demonstrated that, due to low reduction in structural responses (in average 12 percent), the optimum UTLCD is not efficient enough in controlling structures resting on loose soils.

A dual-halo dual-dielectric triple-material cylindrical-gate-all-around/surrounding gate (DH-DD-TM-CGAA/SG) MOSFET has been proposed and an analytical model for the transconductance-to-drain current ratio (TDCR) has been developed. It is verified that incorporation of dual-halo with dual-dielectric and triple-material results in enhancing the device performance in terms of improved TDCR. The effect on TDCR is analyzed for variations in device parameters like oxide thickness, silicon thickness, channel doping concentration, channel length and drain bias.The results show that larger value of gm/Id can be obtained in proposed device in comparison to other existing triple material structures which makes it suitable for micropower applications. The analytical results of the developed gm/Id model strongly agrees with the simulated results obtained from TCAD Silvaco.

Fast and accurate transient response is the main requirement in electric machine position control. Conventional cascade control structure has sluggish response due to the limitation of inner control loop bandwidth. In this paper, in order to decrease the Permanent Magnet Synchronous Motor (PMSM) transient response time it can be used reference model using feed-forward signals. In this structure, feed-forward signals generated by simplified model of permanent magnet synchronous motor. In this paper, feed-forward signals generated are emplyed in model predictive control; which are combined with conventional cascade control structure. Using this approach, a fast transient response and satisfactory tracking ability will be guaranteed. The proposed method is compared with the model reference method and conventional cascade structure. Simulation results showed a good performance of proposed method related to both methods. Verification of simulation results were carried out by experimental results

This paper presents the design optimization of axial flux surface mounted Permanent Magnet Brushless DC motor based on genetic algorithm for an electrical vehicle application. The rating of the motor calculated form vehicle dynamics is 250 W, 150 rpm. The axial flux surface mounted Permanent Magnet Brushless DC (PMBLDC) motor was designed to fit in the rim of the wheel. There are several design variables e.g. air gap flux density, slot loading, magnet spacer width, ratio of outer to inner diameter, air gap length, current density and space factor). The main contribution in the present work is to propose the best combination of design variables obtained using genetic algorithm (GA) optimization technique and design of motor based on optimized design variables. Final validation is carried out with the help of 3-D finite element analysis (FEA) for GA based constraint and unconstraint design. The entire procedure based on GA is explained with the help of block diagram. Efficiency of the axial flux surface mounted PMBLDC motor is enhanced from 88.15 to 91.5 % using GA based design optimization. Proposed optimization technique and methodology will be useful for performance improvement of any nonlinear engineering design involving various design variables for specific application.

The coordination problem of relief items’ distribution operations is essential in humanitarian relief chains. If the coordination is proper, it will improve the response phase to the crisis. In order to improve the coordination in humanitarian relief chains, distribution and warehousing operations of relief items were outsourced to the third-party logistics. In this paper, the procurement-distribution coordination problem in a humanitarian relief chain was studied by the information-sharing mechanism. For this purpose, three decision-making modes, including decentralized, centralized, and coordinated, were formulated to minimize the total cost of the relief chain in the form of mathematical modeling under uncertainty. In a decentralized model, humanitarian relief chains are independent of one another and pursue their own goals. In a centralized model, a central agent manages all activities, and in a coordinated model, independent members are communicated using the information-sharing mechanism. To illustrate the validity of the proposed model, the problem was implemented in the form of a numerical example. The results showed that the chain cost is high in the decentralized mode, total chain costs were reduced in the coordinated mode, and relief items were sent to affected areas without any shortage.

Taking into account competitive markets, manufacturers attend more customer’s personalization. Accordingly, build-to-order systems have been given more attention in recent years. In these systems, the customer is a very important asset for us and has been paid less attention in the previous studies. This paper introduces a new build-to-order problem in the supply chain. This study focuses on both manufacturer's profit and customer's utility simultaneously where demand is dependent on customer's utility. The customer's utility is a behavior based upon utility function that depends on quality and price and customer's preferences. The new bi-objective non-linear problem is a multi-period, multi-product and three-echelon supply chain in order to increase manufacturer's profit and customer's utility simultaneously. Solving the complicated problem, two multi-objective meta-heuristics, namely non-dominated ranked genetic algorithm (NRGA) and non-dominated sorting genetic algorithm (NSGA-II), were used to solve the given problem. Finally, the outcomes obtained by these meta-heuristics are analyzed.

Due to the rapid development of technology in recent years, market competition and customer expectations have increased more than ever. In this situation, it is vital for businesses survival to determine the appropriate policy for inventory control, pricing, and routing, and decisions regarding each of them are often made separately. If the products have a perishable nature, it will be more important to determ ine the above policies. For integration of the decision-making concerning the three key components of the supply chain ,i.e. pricing, routing, and inventory control, two mathematical models were developed for a two-echelon supply chain of perishable items with direct shipment, where fixed lifetime is assumed in one model and random lifetime in another, so that profit is maximized. The proposed mathematical model was solved using the CPLEX solver package of the GAMS software for specification of the optimal policy of the supply chain. The results demonstrated that the CPU time needed for solving the mathematical model for perishable items with random lifetime was less than that for fixed lifetime, while the value of the objective function for products with fixed lifetime was greater than that for products with random lifetime.

Natural gas-diesel dual fuel combustion is a beneficial strategy for achieving high efficient and low emissions operation in compression ignition engines, especially in genset application heavy duty diesel engine at rated power. This study aims to investigate a dual fuel engine performance and emissions using premixed natural gas and early direct injection of diesel fuel. Due to the different reactivities of natural gas and diesel fuels, the mentioned dual fuel combustion is based on reactivity controlled compression igniton (RCCI) which is introduced whitin the cylinder. A six-cylinder direct injection (DI) diesel engine was properly modified to run on dual-fuel mode. Based on experimental study, comparative results are given for various operating modes; conventional diesel mode, convential dual-fuel mode, and RCCI mode; revealing the effect of combustion mode on performance and emission characteristics in a compression ignition engine. The results show that the conventional dual fuel combustion reduces nitrogen oxides (NOx) emissions but suffers from higher carbon monoxide (CO) and unburned hydrocarbon (HC) emissions in compared to conventional diesel mode at part load condition. Results of detailed assessment of different dual fuel modes with CFD model coupled with chemical kinetic mechanism reaveled that RCCI strategy led to higher combustion efficiency as well as lower HC and CO emissions compared to conventional dual fuel combustion at part load condition.

Polymer matrix composites used in different industrial applications due to their enhanced mechanical properties and lightweight. However, these materials are subjected to friction and wear situations in some industrial and automobile applications. Therefore, there is a need to investigate the wear properties of polymer matrix composite materials. This article emphasizes the dry abrasive wear behavior of a hybrid glass/carbon ([GCGGC]S) composite. The mechanical and wear properties of the composite was evaluated and compared with maiden glass and carbon fiber reinforced polymer composite. Design of experiment of Box-Behnken type was adopted to perform the experiments. Response surface methodology (RSM) was employed to optimize the experimental parameters to minimize the specific wear rate of the composites. A second order mathematical model was developed. The model has predicted the optimum input parameters for minimum specific wear rate of 18.847×10-3 mm3/Nm for the hybrid ([GCGGC]S) composite. Furthermore, the model predicted specific wear rate value was validated with experimental one and found a close agreement between them.

Free vibration characteristics of polymer composite plates reinforced by graphene nanosheets employing the Eringen nonlocal elasticity theory were investigated. Theoretical formulations are derived based on Hamilton’s principle implementing linear orthotropic constitutive equations of lamina while the behavior of nanostructure points affected by all other nonlocal points is also taken into account. For obtaining the mechanical properties, a new modified Halpin–Tsai model is employed. Governing equations are solved by developing an efficient analytical solution. The accuracy of the presented method is examined, by comparing the results with literature in which a good agreement is observed. Effects of different boundary conditions, volume fraction, graphene sheets orientation angle and Eringen nonlocal parameter on frequency of nanocomposite are analyzed. Effects of the presence of vacancy defects in the nanosheet on the behavior of reinforced composites were also studied. The results illustrate that by increasing the nonlocal parameter the natural frequency showed a decreasing trend while by increasing the graphene sheet’s volume fraction, natural frequencies significantly increased. It could be concluded that the orientation angle variations in graphene sheets, did not play an important role on the natural frequency of nanocomposite as well as degradation of properties resulted in from vacancy defects.

Present work aims at multi-mechanical surface treatment of Ti-6Al-4V based-miniplate implant manufactured by electrical discharge machining (EDM) for biomedical use. Mechanical surface treatment consists of consequent use of ultrasonic cleaning, rotary tumbler polishing, and brushing. Surface layers are analyzed employing scanning electron microscopy and energy dispersive X-ray spectroscopy. All methods employed are capable of removing surface layer of transformed material created by EDM. These mechanical methods can provide the surface roughness of the miniplate in moderately rough category. Ultrasonic cleaning and rotary tumbler polishing took the significant increase of surface roughness with 90 and 67%, respectively. Furthermore, the brushing technique became the best benchmark for reducing the contamination of Cupper (Cu) on the surface of Ti-6Al-4V implants compared to ultrasonic cleaning and rotary tumbler polishing which hardly gave any impact and took the toxicity effect on both MTT Assay and direct toxicity tests.

In this paper a general analytical solution is obtained to find stress distribution in a finite elastic plate with a circular or square hole subjected to arbitrary biaxial partial loading using modified boundary condition by assuming plane stress conditions. The method employed is based on solution of circular hole in finite rectangular plate. This plate is mapped to circular ones and the partial loading is transformed to new boundaries as form of triangular functions. The Airy stress functions are selected according to these triangular functions and the unknown factors of Airy stress functions are derived by applying boundary conditions. The stresses in this plate with circular hole are mapped to plate with square hole using Muskhelishvili’s complex variable method. The results of this method are compared with theoretical solution of infinite plate and finite elemnt method solution of finite plate. The results showed the dimensions of plate and square hole and length of biaxial partial loading affected on Von Mises stress around the square hole. Von Mises stress increases around the square hole by decreasing length of the plate or increasing hole’s area.

In the present study, the effect of material and process parameters on the morphological and hardness properties of friction stir process (FSP) acrylonitrile butadiene styrene (ABS) were investigated. For this purpose, firstly ABS polymeric sheets were injection molded. Then a slot with predetermined depth and width was created on sheets using a horizontal milling machine. Nano type (nanoclay, nano Fe2O3, and multi-walled carbon nanotube), rotational speed and transverse speed of FSP tool was selected as input paramete of the experiment in three levels. Design of experiments was carried out according to Taguchi L9 orthogonal array. Then aforementioned three types of nano particles were added to the slots and the specimens were friction stir processed in different conditions using a simple cylindrical tool on a vertical milling machine. In the next step, the hardness tests were conducted on the FSP sections of the samples. It was found that addition of nano particles causes an increase in the surface hardness of polymeric samples. Also, it was observed that the samples with multi-walled carbon nanotubes as a reinforcement had the highest value of hardness. Scanning electron microscopy (SEM) tests were carried out on the FSP sections of specimens. Obtained SEM images indicated that processing conditions have a significant effect on the nano particles dispersion in the polymeric matrix.

Roll forming process is used for manufacturing sheet metal parts by successive bending and creating the final shape with gradual deformation. In this article, deformation of a pre-punched sheet due to the roll forming process was studied. Two main defects in the roll forming process are ovality of holes and bow defect. The ovality of the hole is influenced by the process parameters including sheet strength, thickness, initial hole diameter and distance of hole center to lateral edge. Due to the roll forming process, the sheet undesirably bent along longitudinal direction to a slight curved part which called bow defect. Also, the magnitude of product’s curvature along longitudinal direction (bow defect) was measured. The experimental tests were conducted on ASTM 230, 275 and 340 galvanized steels. The results showed that increase in the yield strength elongates the hole along rolling direction and shortened the hole perpendicular to rolling dimension. Therefore, the ovality of hole increases by increasing the yield strength. Also, similar trends were observed by increasing the thickness and the distance between hole center and lateral edge. The results showed that the bow defect decreases by increasing the material yield strength, while with increase in the sheet thickness, initial hole diameter and hole distance from lateral edge the bow defect was increased.

To obtain a higher heat transfer in the low Reynolds number flows, wavy channels are often employed in myriad engineering applications. In this study, the geometry of grooves shapes is parameterized by means of four angles. By changing these parameters new geometries are generated and numerical simulations are carried out for internal fully developed flow and heat transfer. Results are compared with those of rectangular grooved channel. Two different Prandtl numbers, i.e. 0.7 and 5, were investigated while Reynolds number varies from 50 to 300. An element-based finite volume method (EBFVM) is used to discretize the governing equations. Results reveal that that both heat transfer performance and average Nusselt number of rectangular grooved channel were higher than those of other geometries.

Influence of the stacking sequences of hybrid composites on the tensile strength, flexural strength, inter-laminar shear strength (ILSS) and impact energy was investigated. The hybrid glass-basalt-carbon/polyester composite laminates were processed by hand lay-up procedure at room temperature. The fracture surface of the composite laminates after the tension and flexural test was examined by scanning electron micrograph (SEM). The results show that the best mechanical properties were obtained for the composite laminates S5 at stacking sequences [C/B/C/B/C]; where the tensile strength, flexural strength, and ILSS were 148 MPa, 448 MPa, and 25 MPa, respectively. This decline in mechanical properties attributed to the good interfacial bonding between the fibres and the matrix in this configuration. On the other hand, the largest impact strength (43.70 kJ/mm2) was clearly observed for laminates S2 at the stacking sequences [C/G/C/G/C] compared to other laminates simply due to the high stiffness and strength of the carbon fabrics.

The feasibility and parameters optimization of AA5183 aluminum cladding on AISI 1018 steel by electro spark microwelding (ESM) and the corrosion resistance of the clad plate were investigated. The optimum conditions were found as 15 A, 10%, 800 Hz and 2500 rpm for P, D, F and R factors, respectively. Confirmation test under optimum conditions showed that the model can be effectively used to predict the corrosion resistance of the aluminum clad steel. It appeared that higher cooling rates in the ESM process reduced the formation of detrimental precipitates owing to high intrinsic mutual affinity of Al and Fe. Excessive increase in the cooling rates was found to have a correlation to crack formation and reduced the corrosion resistance. Corrosion resistance of AA5183 aluminum clad AISI 1018 steel samples fabricated by ESM was a result of a compromise between the cooling rate and crack formation considerations in the clad.

The article considers the issue of reducing the influence of clayless mud components on the filtration parameters of the reservoir. In the composition of such solutions, calcium carbonate of various fractions is often added as a weighting and colmatizing additive. It is generally accepted that weighting bridging agents are sufficiently inert substances and their addition does not affect the rheological parameters of drilling fluids. Assessment of the fractional composition effect of carbonate weighting agents on the structural-rheological parameters of the biopolymer drilling mud used for drilling productive reservoirs was made in the paper. Six types of carbonate weighting agents with an average particle size of 5 to 150 μm were evaluated during the study. Rheological curves were constructed and the obtained results are analyzed. Also the article reviews four main methods for selecting fractional composition of the weighting agents. doi: 10.5829/ije.2018.31.07a.21