International Journal of Engineering
Volume:34 Issue: 8, Aug 2021

The decision tree is one of the most important algorithms in the classification which offers a comprehensible model of data. In building a tree we may encounter a memory limitation. The present study aimed to implement an incremental scalable approach based on fast splitting and present pruning to construct the decision tree on a large dataset as the complexity of the tree decreases. The proposed algorithm constructs the decision tree without storing the entire dataset in the primary memory by using a minimum number of parameters. Furthermore, the J-max Pre pruning method was used to reduce the complexity with acceptable results. Experimental results show that this approach can create a balance between the accuracy and complexity of the tree and overcome the difficulties of the complexity of the tree. In spite of the appropriate accuracy and time, the proposed algorithm could produce a decision tree with less complexity on the large dataset.

Electrically conductive composite adhesives containing 70, 75 and 85 wt% of filler particles (Cu@Ag) and polymer matrix were prepared. Thermal stability and morphology of the prepared adhesives were examined using TG (Thermo-Gravimetry), DSC (Differential Scanning Calorimetry), and Scanning Electron Microscope(SEM) techniques. In the next step, a transistor-based electrical circuit using self-biased common-emitter combination was made from the prepared conductive adhesive as well as a copper board. All of the prepared boards were subjected to DC (8-30 V) and AC (1 kHz) currents to evaluate their performance. For these circuits, parameters such as transistor operating points and the voltage gain of the amplifier, were measured. TG and DSC analyses showed that increasing the filler amount from 70 to 85 wt%, reduces the weight loss of the adhesive from 15.48 to 11.35 wt%. Also, effect of increasing the silver amount in Cu@Ag particles on the thermal stability of adhesives at temperatures below 350 °C showed that by increasing of the amount of silver from 20 to 40 wt%, has a negligible effect on weight change (about 2 wt% at 250 °C). Both samples showed almost the same overall weight loss at 350 °C. Evaluation of circuit performance showed that the changes in circuit width (1, 1.5, and 2 mm) has no significant effect on the V–I characteristics and voltage gain. The value of these two parameters for all three circuits and also the copper board circuit were the same which indicates the high conductivity of the prepared conductive adhesive.

Chitosan (CH) and cellulose are the most abundant biopolymer which can be utilized for hazardous dye removal. By incorporating TiO2 onto cellulose/CH matrix, our research aims to achieved higher metanil yellow removal by means of synergetic adsorption/photodegradation mechanisms. The cellulose particles were extracted from wild grass (Imperata cylindrica L.) to obtain grass-derived cellulose (GC). Simple blending method was used to prepare TiO2/GC/CH, in which the composition was determined by simple additive weighting method (SAW). TiO2/GC/CH was characterized by means of tensile strength test (also used for SAW), Fourier Transform-Infrared (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Metanil yellow removal using TiO2/GC/CH work the best at acidic pH range. The removal follows the pseudo-second-order kinetic (R2 = 0.99699) and Langmuir isotherm (R2 = 0.99786) modellings. Higher qm obtained from the metanil yellow removal under UV irradiation (qm = 171.5266) proves the synergism between adsorption and photodegradation.

The application of biodegradable substances for the improvement of weak soil has given better results in the field of geotechnical engineering. These substances are fermented and extracted from vegetation. It reduced the void ratio, thickness of absorbed water and maximize the compaction.   Terrazyme contains natural protein. It is non-toxic and eco-friendly. It is soluble in water. The black cotton soil is highly plastic with swelling potential. Reduction in moisture causes shrinking, leads to differential settlement of the foundation. This will results in damage to the structure. This paper presents experimental work on black cotton soil reinforced with Terrazyme. Various proportions of Terrazyme were mixed with black cotton soil to evaluate the engineering properties of soil. The change in index properties and strength parameters were assessed by experiments on treated and untreated soil. Atterberg limits, free swell index, compaction test, triaxial tests were performed. Experimental results show a reduction in liquid limit, plasticity index, free swell index, optimum moisture content, and compression index. Triaxial tests showed improvement in cohesion and angle of shearing resistance. The optimum dosage of Terrazyme was found 2% by weight of dry soil.

The behavior of ship engine encountering stormy waters with different sea wavelengths has been investigated. In this study, a mathematical model is developed using governing equations for various parts of the ship, that is the hull, engine, power transmission shafts from the engine to the propeller also the propeller of the ship itself were implemented in MATLAB/ Simulink software environment. The model consists of the torsional vibrations of the transmission shafts; this enables a more accurate analysis of the engine behavior which is the source of power generation in the ship's propulsion system. The simulation results showed that the wavelength of sea waves has a significant effect on the dynamic performance of the engine. In this research, the effect of different ratios of wavelength to ship length (λ/LPp ) including 0.5, 1, 1.5 and 2 in violent stormy sea conditions with a wave height of 11.5 m and wind speed of 28.5 m/s has been investigated. The results showed that with the exception of λ/LPp of 1.5, at another ratios of λ/LPp , changes in engine performance parameters such as torque, fuel and air consumption, CO2 emission and power are decreasing with increasing wavelength. Most variations in engine speed are related to λ/LPp of 2. The results showed that by reducing the wavelength, the period of oscillations is reduced. As the ratio of wavelength to ship length increases, the number of oscillating points in the engine behavior increases and the lowest number of oscillating points can be seen at λ/LPp of 1.5. This study highlights the importance of effects of sea wavelengths as one of the most important physical parameters of the sea which should not be ignored in the design phase of the ship propulsion system and engine selection.

Face recognition has become a crucial topic in recent decades, which offers important opportunities for applications in security surveillance, human-computer interaction, and forensics. However, it poses challenges, including uncontrolled environments, large datasets, and insufficiency of training data. In this paper, a face recognition system is proposed to iron out the above problems with a new framework based on a hashing function in a three-stage filtering approach. At the first stage, candidate subjects are chosen using the Locality-Sensitive Hashing (LSH) function. We employ a voting system to select candidates via disregarding a large number of dissimilar identities considering their local features. At the second stage, a robust image hashing based on Discrete Cosine Transform (DCT) coefficients is used to further refine the candidate images in terms of global visual information. Finally, the test image is recognized among selected identities using other visual information, resulting in further accuracy gains. Extensive experiments on FERET, AR, and ORL datasets show that the proposed method outperforms with a significant improvement in accuracy over the state-of-the-art methods.

With the industrial revolution, many inventions have been introduced with many solid waste materials in returns. This study investigates the potential recycling of waste plastic sheets, made from low-density polyethylene, as asphalt modifier in the paving mixture. The shredded plastic sheet was used in the asphalt mixture via the wet process. The dosage rate was set up to 9 % by weight of asphalt binder (0, 3, 6, and 9)%. The experimental program was designed to assess the mechanical properties (Marshall stability and flow, and volumetric properties), durability, and short-term aging of asphalt mixtures, in addition to economical assessment. The test results revealed the applicability of using this solid waste material in paving construction as a surface layer, since its usage enhances the pavement performance by increasing stability, index of retained strength, and volumetric characteristics before and after aging as well as saving in cost. The best enhancement can be achieved with 6% of recycled low-density polyethylene.

The metal-organic frameworks (MOFs) due to their large specific surface area and high biocompatibility are suitable as carriers for drug delivery systems (DDSs). In the present study, doxorubicin (DOX) as an anticancer drug was loaded into the UiO-66-NH2 MOFs to decrease the adverse side effects of pristine DOX use and to increase its efficiency through the controlled release of DOX from MOFs. The MOFs were synthesized via microwave heating method and characterized using X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett- Teller analysis. The drug loading efficiency, drug release profiles from synthesized MOFs and pharmacokinetic studies were investigated. The biocompatibility of drug-loaded-UiO-66-NH2 MOFs was also evaluated by their incubation in L929 normal fibroblast cells. The average particle sizes of UiO-66-NH2 MOFs and DOX loaded-MOFs were found to be 175 nm, and 200 nm respectively. The Brunauer-Emmett- Teller surface area of UiO-66-NH2 MOFs and DOX (100 μg mL-1) loaded-UiO-66-NH2 MOFs were estimated to be 1052 m2g-1, and 121 m2g-1, respectively. The synthesized MOFs exhibited high capability for the controlled release of DOX from MOFs as a pH sensitive carrier. The DOX release data were best described using Korsmeyer-Peppas pharmacokinetic model (R2≥0.985). The cell viability of synthesized MOFs against fibroblast normal cells was found to be higher than 90%. It could be concluded that the UiO-66-NH2 MOFs could be used as an effective pH sensitive carrier for loading anticancer drugs.

This study focusses on studying soaking and leaching effects on gypseous soil at both static and dynamic conditions. The soil used was Natural gypseous soil with 50% gypsum. Three parameters were studied (deformation ratio, dissolve gypsum salts and hydraulic conductivity) in both static and dynamic conditions. 20 tests were caried by laboratory model manufactured locally. A platform base connected to loading frame was designed in a manner that allow free movement provided for dynamic test, as in earth quake. Results of experimental work reviled that the deformation ratio S/B (settlement /footing width) for sample subjected to 30 seconds vibration was 15 times that of sample without vibration. On the other hand, 70% of hydraulic conductivity was achieved at the first 10 minutes leaching for model subjected to 30 seconds vibration. That reflects the effect of earth quack on structures constructed on such problematic soil. Author recommend to take cautions when constructing footings beside any dynamic soars specially in gypseous soil.

ZnO nanoparticles were prepared by direct thermal decomposition of the precursor [contain: Zn4(SO4)(OH)6.H2O and ZnO] in air for 1 h at 875°C. The pH of the precursor solution was set on 6 and 11 by the controlled addition of the NH3•H2O solution. The as-prepared materials were characterized by X-ray diffraction (XRD), infrared spectrum (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). According to the analyses, the ZnO nanoparticles were pure with both rod-like and spherical shapes which were synthesized using chloride and sulfate solutions, respectively. Moreover, the average diameter of spherical ZnO synthesized at pH=6 was around 85±5 nm, while, in an average, the nanorods had 980 nm in diameter and 2.2 μm in length. The average nanorods at pH=11 were 760 nm in diameter and 3.3 μm in length, while the average particle size of spherical particles was around 112±5 nm. The TEM and SEM image showed the morphology of spherical and nanorods particles. The reaction temperature of all steps during the synthesis of ZnO nanopowders shifted to the higher temperature, as the pH of the starting solution increased from 6 to 11. Due to the simplicity, the present method could be proposed as a convenient way to produce pure ZnO nanoparticles using ZnSO4 and ZnCl2 solutions without using any toxic and organic chemicals.

In this paper, the whale optimization algorithm is proposed for harmonics elimination in a cascaded multilevel inverter. In selective harmonic elimination pulse width modulation, the selected low-order harmonics are eliminated by solving nonlinear equations, while the fundamental of output waveform is adjusted to a desired value. In this paper, whale optimization algorithm is applied to a 7-level cascaded H-bridge inverter to solve the equations. Also, it was validated by experimental results, since this algorithm has an ability to search in entire solution space, the probability of catching a global best solution is very high. This method has higher accuracy and probability of convergence than the genetic algorithm. The optimization and comparison of whale optimization algorithm and genetic algorithm have been done in MATLAB software. A 1 kW prototype of this converter is built and the results are presented. The effectiveness and the theoretical analysis of this method are verified through both simulation and experimental results

As a natural stone aggregate, resources are reducing at a high rate due to the large concrete use. For the search of substitute material for natural aggregates, in recent years coconut shells are used in the concrete field. Reinforced cement concrete (RCC) portal frames are a very common structural element and used for resisting lateral loads. In this research single bay, RCC portal frames made with coconut shell concrete (CSC) are tested under lateral load and cyclic push-pull load. The results are compared with frames made with conventional concrete (CC). Four prototype bare frames cast in that two frames made with CSC and two with CC. Behavior and characteristics like load capacity, deflection, crack formation, concrete strain, stiffness, and ductility are studied. It was found that under cyclic push-pull load CSC frames are comparable with CC frames rather than under lateral load. The amount of deflection and strains are observed in the CSC frame is comparatively more than in CC frames. Stiffness and ductility also observed more in CSC frames than CC frames.

For robot path planning the weld seam positions need to be known in advance as the industrial robot generally work in teach and playback mode. Since the welding of the pipe is not done completely on the straight line (the nature of the pipe) and the test tube under the machine is moving, the symmetry of the two probes in relation to the welding site is very important during the test and quick tracking is required to set the probes. The use of image processing and machine vision techniques is very efficient in optimizing seamless welding radia. In designing the algorithms used, an attempt has been made to reduce the environmental conditions and unstable industrial situation well in order to track the weld seam with an acceptable speed. New approach has been used to access the central line of the weld seam area. The algorithm is designed to be implemented in a real environment and has very good results. One of the advantages of this method is the reduction of measurement error and the elimination of mechanical and electrical sensors in non-destructive tests.

In this paper, strengthening of RC beams with self-consolodating concrete (SCC) jacket containing glass fiber (GF) and fiber-silica fume composite gel (FSCG) were investigated. FSCG can use as a substitute for a part of the cement that contains silica fume powder, polypropylene fibers, superplasticizer, concrete waterproof, and some other admixtures. In order to evaluate the performance of the proposed jacket, twelve beams were strengthened and a control beam was made. The variables included the amount of glass fibers consumed in the jacket (0, 0.25, 0.5, 0.75, 1 and 1.25% by volume) and the amount of FSCG gel (0 and 7.5%), respectively. Fresh and hardened concrete properties and flexural capacity of RC beams were investigated. The use of FSCG in RC jackets can compensate well for the deficiency in strength due to the GF entry into the concrete matrix. High affinity of these materials improve the cohesion between cement and GFs. RC jackets containing GF and FSCG increased the beams' energy absorption capacity by about 89 to 463%, depending on the percentages of GFs. RC jacket containing GF and FSCG delays the growth of the primary crack and it can significantly increase the maximum load. Also, GFRP sheets have poorer performance compared to the proposed method due to separation from the surface of the strengthened beams, and their load-bearing capacity and energy absorption are lower.

Underreamed piles with one or more bulbs have been widely used in almost all types of soil to support a range of structures. In some cases, in addition to vertical compressive or uplift loads, piles must withstand a considerable lateral load. A 3-D finite element study using ABAQUS software was conducted to examine the behavior of underreamed piles in clay soil under pure lateral, pure uplift, and combined uplift and lateral loads. In this study, pile (L/D) ratios of 11.66, 15, 20, and 25 were considered by adjusting the pile length to simulate the behavior of rigid and flexible piles. The piles were modeled as a linear elastic material, and the soil behavior was simulated using the Drucker-Prager constitutive model. The findings show that the lateral resistance of piles with (L/D) ratios of 11.66 and 15 increased slightly when underreamed piles were used. However, no change in lateral resistance was observed for underreamed piles with (L/D) ratios of 20 and 25 compared with straight piles. The uplift capacity of underreamed piles was significantly greater than that of a straight pile. The lateral capacity was marginally influenced by the prior uplift loading, such that it decreased for a rigid underreamed pile, and increased for a flexible underreamed pile.

In the present study, the effects of pin geometry and tool rotational speed on the microstructure and mechanical characteristics of the AA2024-O FSSW joint were investigated. Two different types of pin geometries, namely cylindrical and step pins, and three different rotational speeds of 900, 1400, and 1800 rpm were used in the friction stir spot welding joint. The microstructure observation, hardness measurements, and shear tests were done. Results show that both pin geometry and rotational speed give a remarkable effect on the microstructure and maximum shear load of the weld joints. For both pin geometries, the hook height and width of the fully bonded region (FBR) increase by increasing the rotational speed. The weld joint produced by a cylindrical pin exhibits higher values in the hook height and width of the FBR than using a step pin. Furthermore, the highest value in a maximum shear load is obtained at a rotation speed of 1400 rpm for both cylindrical and step pins. Another finding is that the maximum shear loads of FSSW joints produced with a cylindrical pin are higher than that made using a step pin.

Openings of RC deep beams can be used to pass electrical, mechanical, and architectural equipment. These openings can reduce the bearing capacity. Previous studies showed that carbon fiber reinforced polymer (CFRP) sheets could influence RC deep beams' ductility and bearing capacity. In this laboratory reearch, the the impact of aramid and glass fiber reinforced polymer (AFRP and GFRP) sheets on the retrofitting of RC deep beams with the circular opening was investigated. Their response was compared with the performance of CFRP sheets. Depending on the layers (1, 2 and, 3), AFRP, GFRP, and GFRP sheets increased the maximum load of the beams by about 65 to 94%, 87 to 130%, and 133 to 196%, respectively. In RC deep beams retrofitted with GFRP sheets, the sheet separation from the beam surface decreased with expanding the number of layers. The CFRP sheets debonded from the beam surface at the supports along the center of the circular opening. CFRP showed much better performance in energy absorption capacity and load capacity than AFRP and GFRP. The CFRP were debonded from the beam surface at the moment of rupture. However, no significant separation was observed in RC deep beams retrofitted with AFRP and GFRP sheets. SEM images of the cores specimens showed that the fracture surface of the specimens extracted from the beam retrofitted with GFRP and CFRP sheets was much rougher than the control specimen, which indicates a stronger bond between the concrete components.

Neural networks are powerful tools for evaluating the thermophysical characteristics of nanofluids to reduce the cost and time of experiments. Dynamic viscosity is an important property in nanofluids that usually needs to be accurately computed in heat transfer and nanofluid flow problems. In this paper, the rheological properties of nanofluid phase change material containing mesoporous silica nanoparticles are predicted by the artificial neural networks (ANNs) method based on the experimental database reported in literature. Experimental inputs include nanoparticle mass fractions (0-5 wt.%), temperatures (35-55℃), and shear rates (10-200 s-1), and targets include dynamic viscosities and shear stresses. A multilayer perceptron feedforward neural network with Levenberg-Marquardt back-propagation training algorithm is utilized to predict rheological properties. The optimal network architecture consists of 22 neurons in the hidden layer based on the minimum mean square error (MSE). The results showed that the developed ANN has an MSE of 6.67×10-4 and 6.55×10-3 for the training and test dataset, respectively. The predicted dynamic viscosity and shear stress also have the maximum relative error of 6.26% and 0.418%, respectively.

Competition among supply chains is an essential factor to be considered in determining supply chain strategies. Furthermore, due to an imbalance in market share, one of the supply chains may have a higher power to manipulate the market and usually play the role of the leader in the market. In this paper, two leader-follower supply chains consisting of one manufacturer and one retailer are considered. In-chain competition is addressed besides the chain-to-chain competition in which the retailer is the leader and the manufacturer is the follower. The competition elements are price and service, which are investigated in three different scenarios: decentralized leader-decentralized follower, integrated leader-decentralized follower, and decentralized leader-integrated follower. Using the backward induction, we start the solving process from the follower supply chain and derive the follower’s best response function. Then the leader strategies are examined after the substitution of the follower’s best response function in leader profit function. Finally, we analyze the effects of the price competition intensity, service investment coefficient, and the potential market size of both chains on the equilibrium values in all three scenarios. The results show that increasing the price competition intensity will decrease the profit of the leading supply chain. In contrast, small values of price competition intensity are beneficial for the follower supply chain. Further, the first scenario has the most retail and wholesale price while the integrated supply chains have the most service level.

In this paper, to fabricate a pin-shaped bipolar plate for a proton exchange membrane fuel cell, the deformation behavior of a thin 8111 aluminum alloy sheet by the hot metal gas forming (HMGF) process was investigated. The effect of gas pressure, forming time, pin diameter, pin height, and die fillet radius on the specimen profiles, as well as the thickness distribution were analyzed by finite element method using ABAQUS 6.10 software. In addition, experimental tests were performed to validate numerical outputs. The results indicated that the sheet thinning rate grew sharply by the gas pressure exceeding 4 MPa. The specimens were cracked following decreasing the die fillet radius to 0.1 mm. Furthermore, the die filling rate was high at the beginning of forming time and then diminished gradually after 1000 sec. Moreover, the thickness reduced sharply by augmenting the ratio of pin height to diameter to over 0.4. Finally, perfect specimens were produced in experiments, which verified the feasibility of fabricating a pin-shaped bipolar plate out of a thin AA8111 sheet by the HMGF process.

The permanent magnet machine has attracted much attention due to its high torque density at low speed and simple configuration. This feature is due to many magnetic pole pairs that flux in the air gap can be significantly changed with the smallest motion of the moving. In this paper, a linear dual stator flux reversal permanent magnet machine (LDSFRPMM) with toroidal winding is presented, which magnets embedded with Halbach and simple array on the translator and stator, respectively. The innovation of this structure over a conventional machine is the addition of a magnet between the stator teeth with the appropriate magnetic orientation, and finding the best width of permanent magnet on the stator and a change of the type of winding from the concentrated to the toroidal. By implementing these changes on a conventional machine, the main parameters of the machine such as back electromotive force (EMF), thrust force, power factor and permanent magnetic (PM) flux are increased which improves the performance of the proposed machine.

Due to widespread usage of induction motor (IM) in various industries, the requirement for its condition monitoring have been considerably raised. It is essential to detect faults that happened in IMs in a short time with high accuracy because they may cause considerable financial losses. Bearing faults contribute to a large percentage of IM failures. In this paper, vibration signal is analyzed for getting reliable indicator for faulty modes of the bearings of the IMs. The proper direction for measuring the vibration signal is analyzed first. This analysis shows that the fault-related vibration frequency components along the Z-axis, i.e. the axis perpendicular to the motor's installing surface, usually have the largest magnitude. Thus, it is recommended to measure the vibration signal in the Z-axis. Then, the bearing fault diagnosis using the vibration signal is investigated in various scenarios. The results confirm that the vibration indicators are not sensitive to environmental parameters like temperature and also load variation of the IM but the severity of the fault has a considerable influence on them.

Aluminium – copper alloys have a wide range of industrial applications especially in military vehicles, rocket fins and aerospace. Solidification plays a vital role in controlling, the mechanical and tribological properties, and influencing the microstructure of metallic alloys in general and aluminium alloys in particular. Therefore, the researchers have made many efforts to figure out the solidification behaviour of Al-Cu alloys. Despite all these endeavors, however, the behavior is not yet fully understood. This research aims to investigate the effect of cooling rate on the microstructure, mechanical and tribological properties of aluminium-copper cast alloys (Al-Cu alloys) under dry sliding conditions. Four cooling rates were achieved by using four various steel moulds made of different thicknesses and one of them was surrounded with green sand, to get a lower cooling rate, with the same respective mould hole geometries. The microstructure results showed that the grain size increases with decreasing the cooling rate. While the hardness increased largely due to the refinement of the microstructure. Finally, it was concluded that the wear rate increases with decreasing the cooling rate, and this due to the reduction in hardness.

Due to the cursive-ness and high variability of Persian scripts, the segmentation of handwritten words into sub-words is still a challenging task. These issues could be addressed in a holistic approach by sidestepping segmentation at the character level. In this paper, an end-to-end holistic method based on deep convolutional neural network is proposed to recognize off-line Persian handwritten words. The proposed model uses only five convolutional layers and two fully connected layers for classifying word images effectively, which can lead to a substantial reduction in parameters. The effect of various pooling strategies is also investigated in this paper. The primary goal of this article is to ignore handcrafted feature extraction and attain a generalized and stable word recognition system. The presented model is assessed using two famous handwritten Persian word databases called Sadri and IRANSHAHR. The recognition accuracies were obtained at 98.6% and 94.6%, on Sadri and IRANSHAHR datasets respectively, and outperformed the state-of-the-art methods.

Multi-hole orifices have better performance than single-hole orifices. In this paper, multi-objective optimization of multi-hole orifices is performed using a Fluid-Solid Interaction (FSI) analysis and multi-objective genetic algorithm (NSGA II). In all numerical analysis, the governing equations of the solid and the governing equations of the fluid are carried out for orifice and fluid around orifice respectively. All calculations are made for a 16-hole orifice with circular holes. The design variable in the optimization process is the distance between the holes of the orifice and thus the amount of shrinkage or expansion of the orifice geometry. The objective functions are the pressure drop created on the sides of the orifice, the deformation and tension created in the orifice structure, which should be maximized, minimized and minimized respectively. In the results section, the Pareto front are presented which represent useful information for designing the multi-hole orifices geometry, and five orifices are also introduced as final design options that have better performance. The results of the sensitivity analysis of the various parameters are also presented and discussed in detail in the multi-hole orifices.