International Journal of Engineering
Volume:35 Issue: 3, Mar 2022

Single Point Incremental Forming (SPIF) process is a novel approach of flexible sheet metal forming method in which 3D component can be allowed to form. The process is characterized by die less flexible, lower lead time and higher formability as compare to conventional stamping process. In the present work involves set of experiments of 1 mm thick Ti6Al4V sheet using the friction stir SPIF process at room temperature and investigating the effect of wall angle, speed, feed and step size on formability of sheet. The results revealed that, the maximum formability of frustum cone specimen was obtained at wall angle of 45° and wall angle is the most significant parameter. With increase in wall angle and feed, the formability of sheet blank decreases while increases in tool rotational speed, the formability found to increase. In addition, it is also observed that, there was no significant influence of step size on formability of sheet.

Air circulation plays a vital role in the comfort of passengers in a bus, being a non-AC bus without any aid from the air conditioning system. The circulation of air is utterly dependent on the design of the bus and the natural flow of air. However, to optimize the flow of air inside the bus, a study on the design of the bus is needed. In this regard, experimental work was carried out to achieve uniform airflow by redesigning the coach into an aerodynamic shape. The openings are provided at the leading edge of the bus to evaluate the best possibility for air to circulate in the bus. Three openings were provided at the leading edge of the bus, the first and second openings were mere openings, and the third opening was fitted with a roof vent providing three different geometric patterns to airflow. The initial boundary conditions were developed by considering that all windows and doors of the bus are closed. The scaling ratio of 1:20 was considered for modeling the bus. The experiments were conducted in the wind tunnel test rig. It was observed from the experimentation that the velocity of the air was considered to be the most influencing parameter for optimal air circulation. The velocities of 21.96 m/s and 22.68 m/s were obtained inside bus. The obtained experimental velocities were validated with results obtained by the Computational Fluid Dynamics (CFD). It was observed that a deviation of 5% for the given velocity of 20 m/s.

Drilling fluids are a vital part of every successful well construction operation. Water based fluids are used commonly due to better environmental compatibility, lower cost and easier preparation. In offshore drilling, sea water can be used as the basis of water based fluids. Salinity of sea water restricts application of some additives. For example, bentonite settles in saline environments. In this study, a synthetic water is prepared based on Persian Gulf sea water. Bentonite, pre-hydrated bentonite and attapulgite suspensions were developed based on fresh water and prepared synthetic water. Rheological and filtration properties of fluids were tested to check their performance in synthetic sea water. Results of filtration measurements showed a thick mud cake and high filtration volume in pre-hydrated bentonite fluids. In the case of attapulgite, filtration volume of suspensions in synthetic water increased comparing to suspensions in fresh water. However, filtration properties were acceptable. Study on rheological properties revealed that Herschel-Bulkley model can predict rheological properties with a good accuracy. This is the case for suspensions in both fresh and sea waters. Also it was seen that all suspension had a flow behavior index less than 1, showing their shear thinning character. By increasing clay concentrations, higher consistency index, yield stress and gel strength values were reported. At higher clay concentration a stronger three-dimensional network of clay particles in aqueous environment and consequently a stronger gel structure were formed. Overall, it can be concluded that attapulgite can be used in the saline environment of Persian Gulf sea water.

In this research, the heat treatment and production of high-strength advanced TRIP 1150 steel were investigated and then the mechanical properties of the welds of this steel were evaluated by spot welding. For this purpose, the effect of rolling process and heat treatment of alloy steel sheets to achieve the ultra-high strength TRIP 1150 steel microstructure was discussed. Microstructural examinations by Scanning Electron Microscopy (SEM) identified ferrite with bainite phases and martensite in matrix. The microstructural characteristics were examined using SEM microscopy with EBSD analysis. The EBSD results showed that the type and orientation of the grains changed and the fraction of high-angle to low-angle boundaries in the present steel varied due to the presence of different phases. The EBSD results showed the acceptable rate of primary austenite in the structure according to the phaseology of this method. Having desirable mechanical properties was one of the most important results of this study, which at the same time maintained impact resistance and mechanical strength.

Regarding the issue of green chemistry and the vision of human sustainability, a novel corrosion inhibitor for API 5L carbon steel was explored from Eucheuma seaweed algae. The inhibiting performance of Eucheuma extract was studied by electrochemical measurement such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). In this work, FTIR also employed to confirm the main phenolic compounds of Eucheuma extract. Electrochemical measurement result inidcated that the Eucheuma extract was an efficient corrosion inhibitor in reducing corrosion attack of API 5L carbon steel in hydrocholoric acid medium. The improved corrosion resistance is attributed to the complicate items including extract concentration and holding time. It was found that the Eucheuma extract was a mixed type corrosion inhibitor that inhibit both the cathodic and anodic corrosion reaction. This study was helpful to discover the seaweed algae that was abundant in Indonesian’s marine for inhibiting corrosion of API 5L carbon steel in aggressive environment.

Deciphering the crucial interactions among genes is one of the key issues in understanding the fundamental molecular and intracellular mechanisms of cell. Computational modeling of gene regulatory networks can be used as a powerful tool in various fields of molecular biomedicine such as identification of metabolic, regulator, and signal transduction pathways, analysis of complex genetic diseases, and drug discovery. In this paper, an optimal Boolean approach is proposed for computational modeling of gene regulatory networks from temporal gene expression profile. In this method, the optimal values of the Boolean thresholds of gene expression signals and the parameters of the interaction patterns between target and regulator genes are all designed as a mixed-integer nonlinear programming solved by Genetic Algorithm. To evaluate the performance of the proposed scheme, it has been applied to a well-known time course microarray data and gene regulatory network of Saccharomyces Cerevisiae from the literature. The reference network has 11 genes, 9 targets, and 61 regulatory interactions, and the original transcriptional dataset includes 18 timepoints for each gene expression signal. In this case study, the proposed computational model contains 142 unknown parameters that are optimally determined through optimization. The results demonstrate the efficiency of the proposed approach.

Additive manufacturing of ceramics via stereolithography method is a promising way to fabricate high-resolution ceramic parts with complex geometry, which is hard to obtain with traditional ceramic shaping methods. In order to shape the ceramics with the Digital Light Processing (DLP), a mixture of photocurable resin and ceramic powders, called ink, must be prepared. In this paper, the printability of the Alumina-glass inks, with different solid contents, prepared by two mixing methods, having long and short mixing durations, was investigated. In order to evaluate the printability of inks, the rheological behavior of suspensions was investigated, and printing parameters such as curing time and layer thickness were changed. The ceramic-resin suspensions were prepared via 24-hour ball-milling and 10,000 rpm mechanical homogenizing. The suspension containing 60 wt% solid content and prepared by mechanical homogenizing showed the best stability with 8% sedimentation within 4 days and the lowest viscosity of 1.37 Pa.s at shear rates of 30 s-1, exhibiting a suitable viscosity for DLP printing. Therefore, a mechanical homogenizer can be a promising and quick method for mixing by simultaneously providing appropriate rheology and printability.

The purpose of this paper is to explore dimensions of open government in tax affairs organization of Iran country as a governmental organization. Three main factors of policy, culture, and technology were identified after investigating open government's plan in the United States of America, Austria, Mexico countries and the conducted interviews with experts in three fields of information technology, Executive, and legal. Four subfactors of internal directive, legal, strategic planning, and performance for policy and five subfactors of security, tools, open government program, data, and infrastructure for technology and six sub-factors of employees readiness, communicational channels, knowledge management, changes management, agency stakeholders, and participatory activities were considered for culture. A structured interview was conducted with three experts in legal, information technology and administrative fields for initial evaluation and finding new factors. The statistical population in this research was considered among Tax Affairs Organization of Iran country's employees. The mentioned pattern was evaluated based on partial least squares approach and confirmed at strong level after extracting information from the distributed questionnaires. Three factors of policy, technology and culture have effect on open government and between them culture has the main priority.

This paper proposes an efficient method to identify the importance of transmission network components from the network’s reliability perspective. The proposed method is able to reveal the weak points of the network and can be employed as useful tool by power system planners to identify where investments should be made to increase the overall system reliability. The proposed approach has two main stages, including evaluation of the network contingency states and a sensitivity analysis which shows the link between reliability of each component and overall system reliability. Unlike the similar methods in this area and with the help of two reasonable simplifications, the proposed method can be employed to real transmission networks with acceptable computational burden. The proposed method is implemented on two test systems including the IEEE Reliability Test System (IEEE RTS) and the Roy Billinton Test System (RBTS). The obtained results demonstrate the efficiency of the proposed approach.

In this research, a new cost-effective carbon source of medium was provided in terms of high-efficiency growth from Arthrospira maxima. Sugarcane molasses was used in two different modes (alternative and additive) at four different concentrations (0, 0.5, 1.0 and 1.5 gL-1) to determine the effect of new carbon source versus its standard carbon source of Zarrouk’s medium (NaHCO3). The experimental results were analyzed by Taguchi L8 method as a statistical technique. The highest biomass production obtained when sugarcane molasses was added as an alternative source, which was 5.31 times higher than the usual Zarrouk's media. Furthermore, final biomass concentration increased with increasing molasses concentration from 0 to 1.5 gL-1 in this group. At highest concentration, phycocyanin (at 0.11 and 0.12 gL-1), allophycocyanin (at 0.13 and 0.12 gL-1), carotenoids (at 2340 and 2535 mgL-1), chlorophyll a (at 23.83 and 24.83 mgL-1), and chlorophyll b (at 0.343 and 2.99 mgL-1) obtained when molasses were added as an additive and alternative sources, respectively. Finally, the replacement of standard carbon sources of medium with sugarcane molasses had the potential possibility in order to reduce the production costs of Arthrospira maxima growth.

In this paper, a neural third-order sliding mode-direct torque control (NTOSM-DTC) for an asynchronous generator (AG) based dual-rotor wind turbine (DRWT) is proposed. The classical DTC strategy with traditional proportional-integral (PI) controllers has been widely applied to induction machines in recent years due to the high characteristics that it provides in comparison with the classical DTC switching technique. Meanwhile, it has a major drawback that are the significant current, rotor flux and torque ripples generated by the traditional PI controllers. To overcome these drawbacks, the improvement of this control technique by removing these controllers is designed in this paper. The proposed intelligenet nonlinear control technique is based on replacing the classical PI controllers with neural TOSM controllers which will have the same inputs as these controllers. The simulation was performed in Matlab software, and the results obtained make it possible to evaluate the characteristics of the proposed intelligenet nonlinear control technique over the traditional one.

The most important structural part of steel structures is the connections of the building frame. Tests conducted by the American Steel Institute have led to the introduction of prequalified connections, which is a good reference for designing connections in steel structures. In this paper, four bolted stiffened and unstiffened extended end-plate connections have been studied by numerical analysis with ABAQUS software. In this study, to examine the effect of bolt pre-tension rarely studied, a coefficient of pre-tension force, introduced based on the Iranian Steel Structures Design Regulations as well as the US Steel Design Regulations, has been considered. These connections have been modeled cyclically and in a displacement control manner. The cyclic behavior of the connections, dissipated energy, the resisting moment as well as the stress and strain distribution in the connection have been investigated. According to the results, by creating a pre-tension force in the bolts, the resisting moment of the connection would increase. The rate of growth of this resistance in the unstiffened connections was greater than that of the stiffened connections. The maximum increase in resistance was about 27% for the unstiffened connection and about 25% for the stiffened connection. The dissipated energy for the connections also increased with the increment of bolt pre-tension. The energy dissipation incremental rate was enhanced to a maximum of about 31% for the unstiffened connection and up to a maximum of about 24% for the stiffened connection.

In the present study, we numerically investigated the twin turbulent jets characteristics and turbulent quantities when a solid object is placed between the two nozzles. The two jets are assumed to be isothermal, incompressible and fully developed. Turbulence is modeled by the k-e Realizable model. The set of Reynolds averaged Navier Stokes equations are solved iteratively by the Fluent software. The numerical model is validated with the experimental results available in the literature. For many Reynolds numbers, it was found that velocities and its gradients decay along the longitudinal direction. The placement of a solid object between the twin jet affects the flow structure behind nozzles due to the curvature effect of the solid object. The converging region is disappeared and the combined points axial position increases with Reynolds number. The evolution is almost linearly with an increase in Reynolds number. The effect of  turbulence intensity at the exit of the nozzle is also examined. For a fixed Reynolds number, the axial combined position increases almost linearly with turbulence intensity.

Brake pads play very important role in the safety of Automobiles as they control the speed of the vehicle. Therefore manufacturing aspects of the brake pads and improvement in their performance are studied in this paper. Experiments are designed based on Taguchi’s L9 orthogonal array. Manufacturing pressure, temperature and time are taken into consideration as process variables. Nine sets of experiments were conducted. Each experiment consisted of distinct combination process variables. Thus Brake pads with Kevlar and Lapinus fibers as a reinforcement and Epoxy resin as a binder, Barium sulfate as a filler and Aluminium oxide as a friction modifier were manufactured using the hot compression method during each experiment. Friction and Wear performance was accessed by the measurement of the Coefficient of friction and weight loss during the trial on the pin on disc apparatus. Specific wear rate was obtained by measuring the differences in density and weight values before and after the trial run.The required values of process parameters i.e. Pressure (500 Psi), Time (8 mins.) and Temperature (180 oC) which give optimum values of coefficient of friction and Wears were determined using Grey relational analysis.