International Journal of Engineering
Volume:34 Issue: 3, Mar 2021

The combustion chamber's internal refractory in Imam Khomeini Oil Refinery Company (IKORC) was damaged in several parts, requiring operating conditions and re-inspecting the design of the combustion chamber using CFD. Simplify the combustion chamber 3D simulation, decrease in the number of calculations, the symmetry principle was applied in the simulation. The results, independent of the mesh network, were investigated via increasing the mesh nodes. The one-stage, two-stage, multi-stage and overall mechanisms, which were designated, were examined and compared to actual measured data and a calculation error of less than 8% was obtained. Ultimately, selecting overall mechanisms, the simulation results, streams mixing and length of the chamber were scrutinized, and as a result, the current design was approved. The temperature and velocity of the flows in the combustion chamber were investigated. In the combustion chamber, the farther we are from the burners, the more uniform the velocity and temperature profiles also become as the wall temperature increases. The rate of combustion reaction was evaluated with the temperature of different points in the combustion chamber. The results showed that the combustion chamber wall's temperature is in the appropriate range and has not suffered any thermal damage. Unlike the combustion chamber wall, the burner wall (at the mixing point) has an unauthorized temperature; there is the possibility of thermal damage that can be eliminated by changing the number of currents. Unsuitable thermal profiles also showed large amounts of oxygen in the exhaust gas indicated that the steam boiler performance is far from the optimal condition and specific changes would be required in the air streams. Streamline demonstrated that the primary air stream was more effective for decreasing CO and NOX amounts in the outlet stream. The secondary air stream was also significant to prevent thermal damage to the internal coating and reduce safety hazards.

In this study, AgI-ZnO/chitosan nanocomposite was synthesized and then was coated on 2×40×200 glass plates under UVA irradiation for the removal of toluene from air streams. The AgI-ZnO/chitosan Nanocomposite was characterized using XRD, SEM, FTIR and BET techniques. The analyses showed Zn and Ag were added to the composite structure with weight percentages of 32.02 and 7.31, respectively. The results confirmed that the AgI-ZnO/chitosan nanocomposite was successfully synthetized. According to the results, the photocatalytic process was able to remove 74.6% of toluene at an air flow rate of 1 L/min after 3.3 min. Also, by increasing the passing flow rate from 0.3 to 1.5 L/min through the photocatalytic reactor, the process efficiency for toluene removal increased. The toluene removal efficiency decreased with increasing relative humidity with respect to time. Moreover, increasing relative humidity decreased the photocatalyst capacity for the removal of the target pollutants. The results implied that the initial toluene concentration in the inlet stream played a key role on the photocatalysis of toluene and by further increase in the pollutant concentration higher than 20 ppm, its performance decreased dramatically. Therefore, the proposed process can be used and an effective technique for the removal of toluene from the polluted air stream under UV irradiation and increasing temperature up to 60 °C could increase its performance.

Building information modeling (BIM) has attracted considerable interest in the area of 4D simulation. The performance and benefits of the 4D simulation can be affected by different factors, such as the organizational integration of the teams involved in the project and the models’ content, which is recognized as the maturity level of BIM. Despite the various advantages of implementing 4D BIM and the significance of obtaining the full potential of 4D simulation, there is a scant number of researches that have considered this issue. Thus, this study aims not only to assess the relationship between the performance of 4D simulation and different maturity levels but also to clarify the required Level of Development (LOD) and maturity level in BIM application to synchronize the BIM implementation process with its expected benefits. For this purpose, the differences in gained benefits of implementing 4D BIM in various projects, which had different BIM maturity levels, were examined. The results showed that promoting the integration of the BIM implementation process, considering suitable LOD for modeling, and clarifying the expectation from different parts of a project lead to an enhancement in the performance of BIM 4D simulation.

Glass is a stiff material with brittle structural behaviour. Hence, it is usually a material mostly decorative or simply structurally supported, and it is hardly ever a load-bearing element within a structure. Although in recent years there have been several experiments in its use in civil engineering, to date little data has been collected or design methodologies disseminated. The present study proposes the innovative concept of considering glass as a structural material, cooperating within a structural system thanks to the adhesive joining technique. In detail, the case of a GFRP structural beam element subjected to bending is herein considered. The evaluation of the stiffness of the mentioned element is compared with that of the same element reinforced with glass plates of different thicknesses. The results show the possibility to increase the global stiffness of the structural element. These outcomes are validated by FEM analysis, which showed excellent agreement with the analytical ones. The effectiveness of the reinforced system, thanks to the considerable stiffness characteristics, allows both the use of glass and the respect of the requirements related to the displacements of the structural elements in their service life.

The paper considers the application of waste sorption material utilization and pumpkin seed husks formed during the extraction of heavy metal ions from aqueous solutions, as a combustible additive to clay mixtures in production of the porous ceramics. In this regard, this study evluates the effects of different amounts (2-8%) of the spent sorption material in the charge composition with changes in the physical and mechanical properties of ceramic samples obtained by firing at temperatures of 950-1050 ° C. One finding is that the combustion of the organic additive is accompanied by the formation of voids and the release of gases with the formation of pores in the ceramic piece. Another finding is that all clay mixtures with a combustible additive allow the production of porous ceramics to meet the requirements for compressive strength, porosity, density, water absorption and linear shrinkage. It is recommended using 4 % of combustive additive in order to obtain optimal properties in terms of density and strength. During the testing of the developed porous ceramics for heavy metal leaching, the material does not pose an environmental hazard. Finally, the results of this study are applicable for the construction of internal partitions and household buildings.

This paper represents the parametric effects on slump and compressive strength of aluminosilicate based Geopolymer concrete using by Taguchi method. A total of nine mix proportions were considered to evaluate the effect of sodium hydroxide (NaOH) solution, Solution/Binder (SB) ratio and the percentage of superplasticizer. Results indicated that the highest slump of 165 mm and 28 days compressive strength of 68.37 MPa was obtained for aluminosilicate based Geopolymer concrete with the superplasticizer, Solution to Binder (SB) ratio and extra water) parameters. By using the selected (Signal-to-Noise (SN) ratio graphs, the best combination of parameters for slump and compressive strength properties was also obtained. The mix with the best combination of parameters was considered and partially replaced with silica fume and rice husk ash. The inclusion of additional silica (in form of silica fume and rice husk ash as Ground Granulated Blast Furnace Slag (GGBFS) replacement), most significantly influenced the slump and compressive strength properties.

Rapid urbanization and requirement of infrastructure, stable construction sites are not available. Therefore, there is a dire need for improvement of marginal soils to be used as a construction material. However, weak soils comprise of saturated clays, fine silts, and loose sand, which are susceptible to failure and pose problems of stability. Therefore, this research aims to study the strength and microstructural behavior of soft soils treated with nano-alumina (Al2O3) additive. In this study, Al2O3 of different percentages (0.5, 1.0, 1.5, and 2.0%) by dry weight of soil was added to a clayey soil and subjected to compaction and unconfined compression strength tests. The compaction tests showed that nano-Al2O3 (< 2.0%) stabilized soils exhibit higher unit weight and lower water content compared to untreated soils. This may be attributed due to the fact that nano-materials possess higher unit weight compared to untreated soils and these materials occupy the pore spaces in-between the soil grains, which reduce soil porosity and increase the shear strength. The unconfined compressive strength test on cured treated soil specimens showed a significant increase in shear strength on the addition of nano-alumina. The scanning electron microscopic analysis on untreated and treated soil specimens showed that untreated soil samples exhibit a compact array of clay grains and nano-material treated soil display closely packed and condensed fine structure, which authenticates an increase in shear strength. Thus, with the addition of Al2O3, there has been a significant improvement in the engineering properties of soft soils.

Recently, a significant number of construction projects that have not been completed in Iraq have a negative impact on stakeholders, the economy, and the environment. The traditional method fails to manage the reconstruction of existing buildings Building Information Modelling (BIM) is a new technology that has helped to improve many aspects of the construction industry. The purpose of this study use BIM technology to reconstruct unfinished projects, and energy performance assessment to minimize the environmental effect of buildings, the use of Building Information Modeling technology could reduce significantly time, and cost. The research idea will be applying to one of the projects in Iraq. the results concluded that applying BIM in the project will significantly reduce the cost of energy of buildings when they are appropriately used in the renovation. Results concluded that using BIM technology and Green Building Studio (GBS) efficient tool for the simulation of building energy and optimization of take-off quantities as accurately as possible.

Helmet are essential for preventing head injuries in bikers. Traffic laws are applied in most countries to bikers who don’t wear a helmet. Manually checking bikers for the usage of a helmet is a very costly and tedious task. In this regard, several helmet detection methods were developed in literature for detecting bikers violating the law in recent years. This paper proposes an image processing method based on the Local Binary Pattern (LBP), Local Variance (LV), and Histogram of Oriented Gradient (HOG) descriptors for detection of bikers without a helmet. The innovation of the proposed method is mainly on the feature extraction step, which leads the classification towards appropriately discriminating between the two classes of helmet and non-helmet. The experimental results show our method is superior to the existing methods for helmet detection. The accuracy of the proposed helmet detection method is 98.03% using the Support Vector Machine classifier.

Synchronous reluctance motors, despite their cost-effective types and wide range of speed, generally have a considerable torque ripple due to changes in magnetic resistance between the flux barriers and the stator teeth. Given the numerous possible rotor combinations with different forms of flux barriers, designing an optimal synchronous reluctance motor without the use of mathematical equations and a clear algorithm will be very time-consuming. In this study, a comprehensive method is used to design a synchronous reluctance motor with an external rotor and a flux barrier shape adopted from the behavior of fluids around a solid rotor. According to the new topology, an external rotor synchronous reluctance motor is designed. Multi-objective Taguchi optimization algorithm based on finite element analysis (FEM) is used to maximize the average torque and reduce the torque ripple.This motor is designed for 300 W electric scooters with a six-pole rotor, a 36-slot stator, and a distributed winding. Finally, a prototype of the proposed motor is constructed to validate the results of simulations. The experimental results confirm the accuracy of the design method.

In this paper, a new radial basis function network-based model predictive control (RBFN-MPC) is presented to control the steam temperature of a power plant boiler. For the first time in this paper the Laguerre polynomials are used to obtain local boiler models based on different load modes. Recursive least square (RLS) method is used as observer of the Laguerre polynomials coefficient. Then a new locally recurrent radial basis function neural network with self-organizing mechanism is used to model these local transfer function and it used to estimate the boiler future behavior. The recurrent RBFN tracks system is dynamic online and updates the model. In this recurrent RBFN, the output of hidden layer nodes at the past moment is used in modelling, So the boiler model behaves exactly like a real boiler. Various uncertainties have been added to the boiler and these uncertainties are immediately recognized by the recurrent RBFN. In the simulation, the proposed method has been compared with traditional MPC (based on boiler mathematical model). Simulation results showed that the recurrent RBFN-based MPC perform better than mathematical model-based MPC. This is due to the neural network's online tracking of boiler dynamics, while in the traditional way the model is always constant. As the amount of uncertainty increases, the difference between our proposed method and existing methods can clearly be observed.

Helicopter unmanned aerial vehicle (HUAV) are an ideal platform for academic researchs. Abilities of this vehicle to take off and landing vertically while performing hover flight and various flight maneuvers have made them proper vehicles for a wide range of applications. This paper suggests a model-based fault detection and isolation for HUAV in hover mode. Moreover in HUAV, roll, pitch and yaw actuator faults are coupled and affect each other, hence, we need a method that decouples them and also separates fault from disturbance. For this purpose, a robust unknown input observer (UIO) is designed to detect bias fault and also catastrophic fault such as stuck in actuators of HUAV. The robust UIO isolates roll and pitch actuator faults from yaw actuator fault. The novelty of this manuscript is the design of two UIO observers to detect and decouple the faults of helicopter actuators, one for lateral and longitudinal actuators and the other for pedal actuator. Also, the proposed method is compared with extended Kalman filter (EKF). Simulation results show effectiveness of the proposed method for detection and isolation of actuator faults with less number of observers and it is able to decouple fault and disturbance effects.

Although word-of-mouth (WOM) intention has been studied as an outcome variable of some constructs such as loyalty, satisfaction, and trust in retail businesses but less attention has been given to the investigating the effect of sensory experience on customer WOM intention. Since studying concurrently the effects of sensory experience on customer emotions and customer WOM intention in retail chain stores are rare, the purpose of this paper is to study how customer sensory experience affect customer WOM intention in retail chain stores, considering the mediating role of customer emotions. For this purpose, 306 valid questionnaires were collected and analyzed from customers of one of the largest and oldest retail chain stores in Iran (ETKA chain stores). The proposed conceptual model of this research is developed on the basis of S-O-R model. Structural Equation Modeling (SEM) and multiple regression analysis used to examine the conceptual model of research. This model has been tested using the Partial Least Squares (PLS) approach by SmartPLS software. The results demonstrate that customer sensory experience directly and significantly affects customer emotions. It was also found that the direct effect of customer sensory experience on customer WOM intention is not very considerable but customer sensory experience indirectly affects customer WOM intention through customer emotions, satisfaction, and loyalty. In addition, regression analysis demonstrates that among the five sensory experiences (taste, touch, sight, sound, and smell), taste has the most effect on customer positive emotions. After taste experience, touch, sight, and sound have the most effect on customer positive emotions, respectively. Similarly, it was found that taste and touch experiences have negative and significant effect on customer negative emotions, and the effect of taste experience is stronger than the effect of touch experience.

Removing of arsenic and antimony from electrolyte of copper electrorefining plant by cooling treatment is the subject of current study. In this regards, the temperature of various electrolyte samples reduce to 5, 10, 15 and 20 °C and hold at different times without any turbulency. Experimental results reveal that decreasing the temperature of the electrolyte, facilitate the deposition of As and Sb in the form of AsO5Sb, AsO4Sb and As2O3 as the white precipitate at a critical time. Also, in the case of the electrolyte retention times exceed than the critical time, the copper content of electrolyte precipitate as blue phase. Typically, it is possible to remove 27 wt.% of Sb and 6 wt.% of As by the cooling of the electrolyte to 5 ᵒC after 8 h. It seems that due to the biocompatibility, the lack of need to the complex technology and its simplicity, the proposed method is a suitable alternative to the common approaches for the removal of antimony and arsenic from industrial electrolyte

In this study, the effect of silver clusters deposition was investigated on optical, wettability and surface properties of diamond-like carbon (DLC) films. Silver clusters and DLC films were deposited on Ni-Cu (70.4-29.6;W/W) alloy substrates by ion beam sputtering deposition (IBSD) technique. Optical and structural properties were measured using UV-visible spectroscopy and Raman spectroscopy, respectively. The wettability and surface free energy of films were determined by the contact angle (CA) measurements. Raman spectra of DLC thin film with 121±6nm thickness without accumulated Ag showed that the size of the graphite crystallites with sp 2 bands (La) was 3.36Å by the ID/IG ratio equal to 0.062 with large optical band gap equal 3eV extracted from Tauc relation. The results of the deposition Ag in the various ion beam energy between 0.6 to 2keV showed the Ag clusters were accumulated uniformity on the surface of DLC films at 0.9keV.  The volume percentage of silver clusters was varied from 5.0±2.01 to 16.3±1.4. The variation was caused by controlling the screen voltage and the deposition time. The CA of the deposited films increases from 79°±2 to 95°±2 as well as the reflection values in the visible and near-infrared region due to the increase in the Ag concentration in the surface of DLC films; while the surface free energy decrease from 86±1 to 66±2mJ/m2  and the optical transmittance is almost constant. Our results demonstrate that the deposition of silver particles on DLC films is potentially useful for biomedical applications having good hydrophobic characteristics without causing a destructive effect on the optical properties of DLC films.

The present study describes the effect of friction welding process on mechanical and metallurgical properties of AISI 304 steel. The joints were made by direct drive friction welding (DDFW) machine, while the characteristics of friction welded joints were evaluated by macro-microstructure, microhardness, tensile test with 4 mm and 6 mm effective diameter, and scanning electron microscope (SEM). The results showed severe flash formation at stationary side related to rotating side, highly plastically deformed zone (HPDZ) was revealed at the interface with large dimension of 110 µm. Maximum microhardness values were recorded at welded center and increased from peripheral to central zones. Reducing ratio of ultimate tensile strength (UTS) and ductility for welded joint related to AISI 304 were 86 and 67%, respectively. Tensile fractures occurred adjacent to the interface at thermo-mechanically affected zone (TMAZ). Fracture morphologies by SEM were discovered cleavage features and mostly ductile mode with micro-porosities of different forms and dimensions

Photocatalytic removal of water and air pollution has received much attention today. Many photocatalysts based on semiconductors have been developed and used. Binary and even ternary composites have been developed to solve the drawback of semiconductors, including high band gaps and short life time of charge carriers. In this study, a three-component composite of TiO2/CuO/WO3 was synthesized by adding WO3 to TiO2/CuO. Their structural properties were evaluated by analyzes X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and diffusive reflectance spectra (DRS) and their performance by methylene orange dye removal. The results of XRD and SEM analysis showed purity and uniform distribution of elements. The combination of TiO2/10%CuO and 15%WO3 with band gap 2.66 eV showed the highest rate constant of dye removal (0.0301 min-1).

The reliability of data driven prognostics algorithms severely depends on the volume of data. Therefore in case of limited data availability, life estimations usually are not acceptable; because the quantity of run to failure data is not sufficient to train prognostics model efficiently. To board this problem, a life clustering prognostics (LCP) framework is proposed. LCP regenerates the train data at different ages and outcomes to increment of the training data volume. So, the method is useful for limited data conditions. In this research, initially LCP performance is studied in normal situation is; successively robustness of the framework under limited data conditions is considered. For this purpose, a case study on turbofan engines is performed. The accuracy for the proposed LCP approach is 71% and better than other approaches. The prognostics accuracy is compared in various situations of data deficiency for the case study. The prognostic measures remain almost unchanged when the training data is even one third. Successively, prognostics accuracy decreases with a slight slope; so that when the training data drops from 100 to 5%, the accuracy of the results drops 26%. The results indicates the robustness of the proposed algorithm in limited data situation. The main contribution of this paper include: (1) The effectiveness of life clustering idea for use in prognostics algorithms is proven; (2) A step-by-step framework for LCP is provided; (3) A robustness analysis is performed for the proposed prognostics algorithm.

Friction welding is a solid-state welding process that generates heat through mechanical friction between workpieces in relative motion to one another, with the addition of a lateral force called "upset" to plastically displace and fuse the materials. One of the key problems during modeling solid-state welding processes is the implementation of the friction model. Coulomb friction model was proposed by researchers for computational solid mechanics (CSMs) modeling of the process, however this law is based on the sliding motion. Norton friction model is also proposed by others, while simplifications and limitations are caused in coincidence with reality. In this paper, Norton friction model is modified to be employed in a computational solid mechanics model of inertia welding. A continuous remeshing technique is used to avoid the mesh distortion problem. Consequently, successful prediction of the temperature distribution, thermal history, equivalent plastic deformation, axial shortening and stress distribution is made. The comparisons between the results of this study and the literature showed that implementing the proposed methodology leads to achieving high accuracy results.

This paper investigates size-dependent vibrations of stepped nanobeams taken into account surface elasticity theory. To do this, the nanobeams are modeled as stepped beams and size-dependent governing vibration equations are derived considering compatibility conditions in stepped sections. Then, an analytical solution is developed to simulate natural frequencies and mode shapes of the nanobeam with various surface properties. Also, a backward procedure is proposed to verify the obtained results and calculate size-dependent effective surface modulus. The results indicate that surface effects and appropriate steps selection have noticeable impact on natural frequencies of non-uniform nanobeams. Also, the stepped modeling of the nanobeam became more important for longer and slender ones. Moreover, despite uniform nanobeams, the mode shapes of the non-uniform nanobeams are also extremely dependent on the surface effects.

This paper presents an experimental investigation on the nonlinear nature of the dynamic geomechanical characteristics of a clastic rock (sandstone). Rock samples of 7.5 mm in diameter and 15.6 mm in length were prepared. Rock properties were identified. Firstly, the limits of the rock linear elasticity zone were defined during quasistatic loading and uniaxial compressive strength determination at the Tinius Hounsfield rig. Secondly, the small experimental custom-built rig was designed to study the nonlinear nature of the Young’s modulus in the zone of linear elasticity. At the rig the sample was stationary preloaded. The dynamic load was generated by a piezoelectric actuator powered with a signal generator. The displacement of rock sample surfaces was recorded by a laser sensor and an eddy current probe. The dynamic experiments were conducted at the load amplitude ranging from 50 to 250 N for each of frequencies of 25 Hz and 40 Hz. It was found that the dynamic Young’s modulus increased with amplitude for all the frequencies studied. The newly developed experimental rig allows to investigate elastic moduli dispersion of rocks at the strain up to 10-3 under vibrations with frequency up to 40 Hz.