Materials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Design and Simulation of a Novel Hetero-junction Bipolar Transistor with Gate-Controlled Current Gain43344015998710.5829/ije.2023.36.03c.01ENA. Hoonan MehrabaniElectrical Engineering Department, Shahrood University of Technology, Shahrood, IranA. FattahElectrical Engineering Department, Shahrood University of Technology, Shahrood, IranE. RahimiElectrical Engineering Department, Shahrood University of Technology, Shahrood, IranJournal Article20220102A new structure for SiGe Hetero-junction Bipolar transistor (HBT) is designed and simulated using Silvaco simulator. The considered extra terminal gives the ability to control the transistor's current gain. By applying voltage to the gate terminal, the base effective width would be controlled. Decrement of the Base width yields to the carrier recombination rate reduction, let the emitted electrons to have higher chance to reach the collector. Considering extra terminal have two approaches. One is to improve the current gain of the transistor by applying a constant voltage to the gate and the other is to modify the characteristics of the transistor in such a way that the current gain became optimized. The current gain of the transistor without any gate voltage is about 50V, which increases to 750 for high and 50,000 for low collector currents with the gate voltage variation consideration. In addition, our final proposed gate-controlled HBT with a large gate over the base and collector has the breakdown voltage of 8V and the cut-off frequency of about 11 GHz. The maximum FoM of 1200 is achieved using the proposed structure.https://www.ije.ir/article_159987_963ae7e91776cf754c1723524c122206.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Performance Evaluation of Weighted Feedback Based UPQC under Various Power Quality Issues44144915788010.5829/ije.2023.36.03c.02ENK. BhavyaDepartment of Electrical & Electronics Engineering, JNTUK, Kakinada, India0000-0002-3498-6192P. V. V. Rama RaoDepartment of Electrical & Electronics Engineering, Maturi Venkata Subba Rao (M.V.S.R) Engineering College, Hyderabad, IndiaL. Ravi SrinivasDepartment of Electrical & Electronics Engineering, Gudlavalleru Engineering College, Gudlavalleru, IndiaJournal Article20220209Power efficiency is one of the big issues in the energy sector today. It becomes much more critical with the advent of sophisticated and complex systems, whose output is highly dependent on the efficiency of the power supply. Electronic systems are extremely vulnerable to disturbances, so industrial loads are less tolerant to power quality issues like voltage dips, voltage sags, voltage flickers, harmonics, and load unbalance, among others. For custom power applications, a variety of highly modular controllers that take advantage of newly available power electronics components are currently on the market. This paper introduces the concept of a unified power quality conditioner based on the VSC theorem, which is used to increase power quality. Capacitor banks, a series-active filter, and a shunt active filter make up the model. Negative-sequence current and harmonics are primarily compensated by series-active and shunt-active filters, while capacitor banks are used to compensate the reactive power of power frequency. This paper also includes using a weighted feedback algorithm to manage the PCC parameters as well as the UPQC performance. The proposed architecture has been put through its paces with a variety of distributed systems and fault scenarios. The entire framework was designed and analyzed with the help of MATLAB simulink and code.https://www.ije.ir/article_157880_040da657ebc33f13e314388be0b55179.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Experimental Investigation of the Effects of using Waste Rubber Ash on Mechanical Properties of Plain Concrete45045615997710.5829/ije.2023.36.03c.03ENH. NikkhahDepartment of Civil Engineering, Babol Noshirvani University of Technology, Babol, IranH. R. TavakoliDepartment of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran0000-0001-5298-6199N. FallahDepartment of Civil Engineering, Babol Noshirvani University of Technology, Babol, IranJournal Article20220418In this study, the effects of using rubber ash on the mechanical properties of plain concrete were experimentally investigated. The main purpose of this study was to determine the proper fraction of rubber ash to be utilized in concrete by investigating the mechanical properties of concrete such as elasticity modulus, compressive strength, tensile strength, bending strength, and fresh concrete slump. Four different fractions of rubber ash (2.5, 5, 7.5 and 10% of cement weight) were added to the concrete mixture. Based on the results achieved from the tests conducted on the specimens, it could be deduced that adding rubber ash to concrete considerably increased compressive and bending strength and reduced the slump flow. It also increased tensile strength and elasticity modulus at a lower level.https://www.ije.ir/article_159977_90ed681a503856887729a18c7075a90e.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Performance Assessment of Ductile Detailing Code-Based Reinforced Concrete Special Moment Resisting Frames45746415959710.5829/ije.2023.36.03c.04ENS. ChilukaDepartment of Civil Engineering, Vardhaman College of Engineering, Hyderabad, Telangana, India0000-0001-8170-7689P. OgguDepartment of Civil Engineering, Vardhaman College of Engineering, Hyderabad, Telangana, India0000-0001-8379-2813Journal Article20220708Reinforced concrete (RC) buildings make up the majority of Indian building stocks. Structural elements of these buildings are often designed limited to non-ductile detailing. With a very low building replacement rate, many Indian buildings are vulnerable to earthquakes and pose a significant risk to lives, properties and economic activities. This paper examines the effectiveness of ductile-detailing in mitigating the seismic collapse risk by analyzing the behaviour of a four-storey RC Special Moment Resisting Frame (RC SMRF) using the latest codes of ductile detailing. It also aims to quantify the impact of lateral force resisting system detailing on the performance and cost of RC SMRF buildings and its benefits. The present study emphasizes the effect of ductile detailing on three fundamental aspects of the structure – safety, stability and economy. Two four-storeyed building models – one without ductile detailing and the other with ductile detailing are designed and then analyzed using non-linear static analysis. The results of this study represent the behaviour of ductile-detailed and non-ductile-detailed buildings in terms of pushover curves, and hinge behaviour and identify the mode of final failure. In extension to that, a cost-benefit analysis is done to study the benefits of ductile detailing with the increased cost. The marginal increase in initial cost associated with ductile detailing is significantly outweighed by the resulting savings in the repair and downtime costs during the service life of the building.https://www.ije.ir/article_159597_597cb9073854d9ca41149609441f7bed.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Assessing Potential Performance of GPS and Galileo in Context of Broadcast Precise Orbits and Clock Corrections46547215914410.5829/ije.2023.36.03c.05END. KunaAdvanced GNSS Research Laboratory, Department of ECE, University College of Engineering, Osmania University, Telangana, India0000000192810737P. Naveen KumarAdvanced GNSS Research Laboratory, Department of ECE, University College of Engineering, Osmania University, Telangana, India0000-0003-2023-4755Journal Article20220813The global navigation satellite system (GNSS) is becoming a vital positioning technology across various services. The ephemeris quality is one of the factors that directly impact the user's position accuracy. Some applications, such as investigations into Earth's crustal dynamics, need more precise ephemeris data than broadcast ephemeris. Several institutions, such as the international GNSS service (IGS), have developed precise orbital services to enable these applications. Unfortunately, data rates for such precise orbits are often confined to 15 minutes. In this paper, in order to generate precise ephemeris with the broadcast sampling period, the well-known Lagrange interpolation method is used. Furthermore, a comparative GPS and Galileo position analysis corresponding to the broadcast and precise ephemeris over a typical day in September 2021 is presented. To get insight into comparative positioning analysis over Hyderabad Station, the ENU (East-North-Up) directional errors, satellite visibility and horizontal accuracy parameters are considered. Based on the numerical analysis, standalone Galileo has similar capabilities to GPS, and it can be used in Multi-GNSS over India and its surrounding areas. This work may help in the development of single- or dual-frequency GNSS receivers for civilian navigation services.https://www.ije.ir/article_159144_5f7d32aa19b70aa409bfd0b0dc7c10f8.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Compaction Quality Control of Coarse-grained Soils Using Dynamic Penetration Test Results through Correlation with Relative Compaction Percentages47348016037510.5829/ije.2023.36.03c.06ENS. M. S. GhorashiUniversity of Qom, Faculty of Engineering, Civil Engineering Department, Qom, IranM. KhodaparastUniversity of Qom, Faculty of Engineering, Civil Engineering Department, Qom, IranM. Khodajooyan QomiIsfahan University of Technology, Faculty of Civil Engineering, Isfahan, IranJournal Article20220819In this study, in order to control the compaction quality of the coarse-grained soils used in sub-base and base layers of several road construction projects, the dynamic penetration test (DPT) has been conducted on 50 locations using both dynamic penetrometer of light (DPL) and dynamic penetrometer of medium (DPM). First, in order to obtain the results independently from the penetrometer type, the dynamic cone resistance (<em>q<sub>d</sub></em>) values were calculated in each location based on hammer blows of both DPL and DPM. Next, the average values of <em>q<sub>d</sub></em> obtained by both the penetrometers, were correlated with the percentages of relative compaction (<em>RC</em>) in the same location obtained by performing the sand cone test on location and modified proctor test in laboratory. Accordingly, it was extracted a power correlation between the <em>q<sub>d</sub></em> values and <em>RC</em> percentages, with the determination coefficient (<em>R<sup>2</sup></em>) of about 0.64. Then, for considering the effect of soil grains size using the median particle size (<em>D<sub>50</sub></em>), a more accurate power correlation was obtained which as a result, the <em>R<sup>2</sup></em> value enhanced to 0.89. Furthermore, in order to consider the soil vertical stresses caused by depth of testing as well as obtaining a normalized relationship, the <em>q<sub>d</sub></em> values were divided by the<em> </em>vertical stresses and correlated with the <em>RC</em> percentages. Afterwards, regarding the effect of soils grains size and also their gradation properties, this time by using the dimensionless coefficients of uniformity (<em>Cu</em>) and curvature (<em>Cc</em>), it was extracted an other normalized power correlation. The results showed that the <em>R<sup>2</sup></em><sup> </sup>value enhanced from about 0.49 to 0.92.https://www.ije.ir/article_160375_ad76fbe0876fe8f3820a44de68786fd1.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Viscosity Analysis of Water-based Copper Oxide Nanofluids48148916084510.5829/ije.2023.36.03c.07ENJ. SinghDr. SSB UICET, Panjab University, Chandigarh, IndiaR. KumarDepartment of Mechanical Engineering, UIET, Panjab University, Chandigarh, IndiaH. KumarDepartment of Mechanical Engineering, UIET, Panjab University, Chandigarh, IndiaM. GuptaDepartment of Mechanical Engineering, GJUST, Hissar, Haryana, IndiaJournal Article20221016In this paper, the effects of weight concentration of nanoparticles and temperature on the viscosity of water-based copper oxide nanofluids have been studied experimentally using analysis of variance (ANOVA)-based two-factor three-level (2<sup>3</sup>) factorial design. The results show that a maximum increase of 23.12% in viscosity is observed at 30°C temperature as the weight concentration of nanoparticles increases from 0.03 to 0.3wt.%. Whereas the temperature increases from 30 to 60°C, the viscosity decreases up to 46.19% in the case of 0.3wt.% nanofluid. Temperature is found to be more dominant than the concentration of nanoparticles. The optimum value of viscosity (0.513 mPa.s) is found at concentrations of 0.1wt.% and 60°C temperature with an 18.72% enhancement in viscosity as compared to the base fluid. The experimental and model values of viscosity have been compared with the predictions of the proposed equation for viscosity. The experimentally measured results are found near the proposed results whereas the model underestimates the viscosity in the case of all nanofluids. The maximum underestimation of 25.92 % was observed in the case of 0.3wt.% nanofluid at 60°C temperature. https://www.ije.ir/article_160845_48ccf8b95f925d12a5f49ea806deb19e.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Variations of Organic Loading Rate on Tofu Wastewater Degradation using Upflow Anaerobic Sludge Blanket Reactor by Modified Stover-Kincannon Model49049616100110.5829/ije.2023.36.03c.08ENF. BatubaraDepartment of Chemical Engineering, Universitas Sumatera Utara, Jalan Almamater Kampus USU, Medan, IndonesiaM. TurmuziDepartment of Chemical Engineering, Universitas Sumatera Utara, Jalan Almamater Kampus USU, Medan, IndonesiaI. IrvanDepartment of Chemical Engineering, Universitas Sumatera Utara, Jalan Almamater Kampus USU, Medan, IndonesiaN. YanqorithaDepartment of Industrial Engineering, Universitas Prima Indonesia, Medan, Indonesia0000-0002-6864-4609Journal Article20220226This research aims to examine the varians of organic loading rate (OLR) on degradation of tofu wastewater using the hybrid upflow anaerobic sludge blanket (hybrid UASB) reactor using the modified kinetic model of Stover Kincannon. This reactor was operated at OLRs variation of 1.5-12 kg COD m<sup>-3</sup> d<sup>-1</sup> and HRT of 12 - 24 hours for 328 days. Higher COD removal efficiency of 86.41% and biogas production of 7700 mL were achieved at OLR 4.8 kg COD m<sup>-3</sup> d<sup>-1</sup> and HRT 24 hours on 140 days. Modified Stover-Kincannon model was observed and matched data sets were obtained. The kinetic values of model obtained at HRT variations, the parameters K<sub>B</sub> and μ<sub>max</sub> were 3.7, 12.97, 2.42 mgL<sup>-1</sup> d<sup>-1</sup> and 0.59, 9.41, 0.014 mgL<sup>-1</sup> d<sup>-1</sup>, respectively. This model was a plot of the inverse of the removal rate, versus inverse of the total loading rate resulted in a straight line. It showed that the Stover-Kincannon Model is the rate of substrate removal was affected by the organic load rate (OLR) that flowed into the hybrid UASB reactor.https://www.ije.ir/article_161001_4569602c1f473000acfd7ad31b963a6f.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Improving the Position Accuracy of Rover Receiver using Differential Positioning in Indian Regional Navigation Satellite System49750415998810.5829/ije.2023.36.03c.09ENK. Madhu KrishnaAdvanced GNSS Research Laboratory, Department of ECE, University College of Engineering, Osmania University, Hyderabad, IndiaP. Naveen KumarAdvanced GNSS Research Laboratory, Department of ECE, University College of Engineering, Osmania University, Hyderabad, IndiaJournal Article20220819Navigation with Indian Constellation (NavIC) is the Indian Regional Navigation Satellite System (IRNSS) developed by Indian Space Research Organization (ISRO) to provide the position and navigation services for Indian region. NavIC or IRNSS is individual satellite constellation which has seven satellites covering the Indian subcontinent. Accuracy of NavIC standalone is insufficient in certain applications such as civil aviation. To improve the position accuracy performance of NavIC system, differential positioning technique is utilized. In this paper, differential positioning is carried out, considering two IGS (IRNSS-GPS-SBAS) receivers (one as reference station and the other as rover), which are capable of receiving IRNSS signals from 7 satellites, GPS signals from 12 satellites, SBAS signals from 2 satellites. Here, NavIC constellation alone is considered for the analysis. The differential positioning is carried out using the pseudorange measurements on L5 (1176.45 MHz), S1 (2492.028 MHz) and dual (L5 and S1 both) and accuracies are compared in terms of the statistical parameters Circular Error Probability (CEP), Distance Root Mean Square (DRMS), 2DRMS (twice the DRMS). The improvement in the horizontal accuracy (2DRMS) of the rover using pseudorange measurements on L5 is observed to be 78.81%, on S1 it is 69.14 % and using dual frequency (L5 and S1 both) it is 80.73% when compared to NavIC standalone.https://www.ije.ir/article_159988_001b15ca2abc3192311a6a13371df9a2.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Improving the Accuracy of Brain Tumor Identification in Magnetic Resonanceaging using Super-pixel and Fast Primal Dual Algorithm50551216175410.5829/ije.2023.36.03c.10ENM. EmadiFaculty of Electrical Engineering, Mobarakeh Branch, Islamic Azad University, Mobarakeh, Isfahan, Iran0000_0001_6976_4250Z. Jafarian DehkordiFaculty of Software Engineering, Najaf Abad Branch, Islamic Azad University, Najaf Abad, Isfahan, IranM. Iranpour MobarakehDepartment of Computer Engineering and IT, Payam Noor University, Tehran, Iran0000-0003-3009-6093Journal Article20220315Brain tumors are one of the most common causes of death that have been widely investigated by scholars in research areas, including care and prevention. Despite various empirical studies on the brain tumor segmentatin, there is still a need for further investigation. This fact is more needed in the automatic methods of brain tumors detection. In the present study, a new method for improving brain tumor segmentation accuracy based on super-pixel and fast primal dual (PD) algorithms has been proposed. The proposed method detects brain tumor tissue in Flair-MRI imaging in BRATS2012 dataset. This method detects the primary borders of tumors using a super-pixel algorithm, and improves brain tumor borders using fast PD in Markov random field optimization. Then, post-processing processes are used to delete white brain areas. Finally, an active contour algorithm was employed to display tumor area. Different experiments were carried on the proposed method and qualitative and quantitative criteria such as dice similarity measure, accuracy and F-measure were used for evaluation. The obtained results showed the efficiency of the proposed method, such that in the accuracy and sensitivity of 86.59 and 88.57% and F1-Measure 86.37 were obtained, respectively.https://www.ije.ir/article_161754_ed4c1af855306abc44c3744ed8c53359.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Growth Media Optimization for Production of Alkaline Protease from Industrial Wastewater using Bacillus subtilis PTCC 125451352216351810.5829/ije.2023.36.03c.11ENZ. JafariBiotechnology Research Laboratory, Faculty of Chemical Engineering, Babol Noshirvani University of Technology, Babol, IranG. Najafpour DarziBiotechnology Research Laboratory, Faculty of Chemical Engineering, Babol Noshirvani University of Technology, Babol, IranH. ZareDepartment of Chemical Engineering, Buein Zahra Technical University, Buein Zahra, Qazvin, Iran0000-0003-0784-660XJournal Article20220805Alkaline proteases are widely used in industrial processes due to their high pH tolerance and thermal stability. In present work, the protease producing ability of <em>Bacillus</em> strains (<em>Bacillus subtilis</em> PTCC 1254, <em>B. subtilis</em> PTCC 1156 and <em>B. subtilis</em> PTCC 1715) was studied. <em>B<strong>.</strong> subtilis</em> PTCC 1254 showed the highest proteolytic activity and therefore, the strain was selected as the biological agent in the submerged fermentation. Cell growth kinetic model was investigated using Malthus and Logistic equations, which were relatively well fitted to the experimental data. The maximum specific growth rate for Malthus and Logistic models were 0.187 and 0.377 h<sup>-1</sup>, respectively. The optimum culture conditions were defined as follows: pH 9, temperature 37°C, fermentation time 72 h, agitation speed 150 rpm and 4%<strong><em> </em></strong>inoculum with medium contained 1 g/l CaCl<sub>2</sub>, 0.6 g/l K<sub>2</sub>HPO<sub>4</sub>, 1<strong><em> </em></strong>g/l KH<sub>2</sub>PO<sub>4</sub>, 0.2 g/l MgSO<sub>4</sub>.7H<sub>2</sub>O, 2 g/l sugarcane bagasse and 4 g/l corn bran as carbon and nitrogen sources. A 25% v/v industrial wastewater containing starchy waste was used as main substrate. Under optimum conditions, maximum alkaline protease activity of 117.43 U/ml was achieved. Also, the obtained protease was able to remove blood stain from cotton fabric and hydrolyze gelatin of X-ray film. Thus, this protease showed potential applications in detergent and photographic industries.https://www.ije.ir/article_163518_5f5f71a25f83b769a0cb3a6b29b8098a.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Fabrication of Aluminum 5083/SiC Surface Composite on Tungsten Inert Gas Weld Joint by Novel Direct Friction Stir Processing Technique52353116327310.5829/ije.2023.36.03c.12ENK. D. TandelSardar Vallabhbhai National Institute of Technology, Surat, India0000-0002-5986-2903J. V. MenghaniSardar Vallabhbhai National Institute of Technology, Surat, IndiaJournal Article20221125For the creation of surface reinforcement particles in the metal matrix, friction stir processing is frequently utilized. Formation of aluminum/SiC surface composite on Tungsten Inert Gas (TIG) butt weld of Al5083 by a novel technique of direct friction stir processing (DFSP) using a hollow tool is successfully demonstrated in this present work. Deposition of SiC in the stir zone of DFSP was confirmed by X-Ray diffraction (XRD) method. Micro analysis of weld joint was achieved using metallographic microscope and scanning electron microscope (SEM). Microstructure of stir zone of DFSP shows finely distributed SiC reinforcement particles in aluminum matrix. Absence of detrimental intermetallics was confirmed by energy dispersive spectroscopy (EDS) analysis. Tensile strength of DFSPed specimen was found to be 227.3 MPa which is 19.5% lower than UTS of autogenous TIG weld specimen. Microhardness of SZ of DFSP was found to be increased from TIG weld microhardness of 86 Hv to 107 Hv due to presence of SiC particles.https://www.ije.ir/article_163273_81f34be68a8d0cde51f4c0346eedc2db.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Synthesis of Hard Layer by Titanium Addition During Welding Process and Quenched Directly53253916397710.5829/ije.2023.36.03c.13ENS. SyaripuddinDepartment of Mechanical Engineering, Universitas Negeri Jakarta, Jakarta, IndonesiaS. SopiyanDepartment of Mechanical Engineering, Universitas Negeri Jakarta, Jakarta, IndonesiaS. AdityaDepartment of Mechanical Engineering, Universitas Negeri Jakarta, Jakarta, IndonesiaS. D. YudantoResearch Center for Metallurgy - National Research and Innovation Agency, Serpong, Indonesia0000-0001-9388-2986F. B. SusetyoDepartment of Mechanical Engineering, Universitas Negeri Jakarta, Jakarta, Indonesia0000-0003-2473-7595Journal Article20221202Enhance the surface hardness of materials usually conducted through a hardfacing technique. Hardfacing is popular, whereby materials with better properties are deposited over cheaper bulk material. This work fabricated hard layers by adding titanium (Ti) wire during the welding process. This research used low-carbon steel as the base material, wire optime Ti grade 1 for Ti addition, and an HV 600 electrode with a diameter of 3.2 mm for filler metal. A single-layer weld was conducted with SMAW (positive polarity and 90 A). The samples were directly quenched in a different solution after welding. The properties of the weld layer were examined phase, structure, microstructure, macrostructure, and hardness using optical emission spectroscopy (OES), x-ray diffraction (XRD), an optical microscope, a digital camera, and a hardness device, respectively. Adding titanium (Ti) to the weld layer and quenching the samples after welding in the solution enhances the hardness. This phenomenon is attributed to different phase compositions, oxides, and microstructures. A fine dispersion of small particles and oxide amount is important in increasing hardness. There is no cracking in the weld and base metal. In conclusion, samples BNTiO and BNTiM are recommended for lathe-cutting tools.https://www.ije.ir/article_163977_c5f7a4254f40e62e955e66e9f81277db.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Numerical Analysis on Flow Characteristics of Gas-liquid Two-phase Flow in a Vertical Pipe with Downward Stream54054716364410.5829/ije.2023.36.03c.14ENS. HasanpourMechanical Engineering Department, Faculty of Engineering, Urmia University, Urmia, IranI. MirzaeeMechanical Engineering Department, Faculty of Engineering, Urmia University, Urmia, IranM. KhalilianMechanical Engineering Department, Faculty of Engineering, Urmia University, Urmia, IranJournal Article20221119Through this paper, a 3D simulation together with experimental observation was conducted to study two-phase flow in a vertical tube. OpenFOAM software was employed to analyze air and water. Main flow stream was downward which was considered to be within a vertical pipe of 10 mm in diameter. Study included two inputs for flows: upper input for water and side input for air. Several states with various mass fluxes for both water and air were studied. Based on physics of the issue, numerical simulation was considered to be time-dependent. Obtained results showed that when air velocity occupied lower values, air momentum cannot overcome water momentum leading in small slugs. When airflow velocity was more than water flow rate, it dominated water flow and consequently could affect mainstream direction. Also, velocity graphs on centerline represented that going forward in time, velocity magnitude experiences a significant value of fluctuations and large oscillations occur next to outlet. Comparing experimental and numerical results, approximately 9% differences can be found which showed suitable agreement. Results showed that at initial steps, void fraction faces a significant jump in values. Intensity of this change in void fraction values was higher in lower water velocity. Indeed, by increment of water velocity, inertial forces associated with liquid phase find a dominant role in overall hydrodynamics of the gas-liquid flow. Also, it is obvious that flowing manner in cases 1, 2, and 3 are similar but after case 4, flow pattern varies. These changes are more considerable in cases 5 and 6.https://www.ije.ir/article_163644_f93579e138cd6c4f3060e1b976857b84.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Experimental Analysis and Physical Mechanism Investigation of Al2O3 Effect on New and Aged Transformer Oil Properties54855716406610.5829/ije.2023.36.03c.15ENA. H. MashhadzadehDepartment of Electrical Engineering, Gorgan Branch, Islamic Azad University, Gorgan, IranS. M. SeyyedbarzegarDepartment of Electrical Engineering, Shahrood University of Technology, Shahrood, IranA. SamaniDepartment of Electrical Engineering, Islamic Azad University, Science and Research Branch, Tehran, IranJournal Article20221021Al<sub>2</sub>O<sub>3</sub> nanoparticles were used to improve the performance of the vital properties of transformer oil (TO) under normal operating conditions and when subjected to thermal aging. Different weight percentages of Al<sub>2</sub>O<sub>3</sub> in the TO were considered to maximize the breakdown voltage (BDV). Al<sub>2</sub>O<sub>3</sub> nanofluid (NF) increases the BDV by 116% (31.1 kV to 67.4 kV) and the heat transfer by 33.4%, and also minimizes partial discharge (PD) by 66%. The reduction of PD is also related to the ability of Al<sub>2</sub>O<sub>3</sub> to adsorb hydrogen and acetylene, two oil-soluble gases that are effective in PD. Even Al<sub>2</sub>O<sub>3</sub>NF was more resistant to water content in TO. BDV for TO and Al<sub>2</sub>O<sub>3</sub>NF, when water content increased to more than 30 ppm, were reduced by 57% and 19%, respectively. According to Arrhenius equation, both samples were placed at 120°C for 29 days to age samples (equivalent to about 30 years). Aged Al<sub>2</sub>O<sub>3</sub>NF has continued its exceptional performance and improved BDV by 121% compared to aged TO, and also Al<sub>2</sub>O<sub>3</sub>NF showed its capacity well and improved PD compared to aged TO by 71%. All the favorable properties of Al<sub>2</sub>O<sub>3</sub>NF are conditional on the stability of Al<sub>2</sub>O<sub>3</sub>. FESEM confirms the stability of Al<sub>2</sub>O<sub>3</sub>.https://www.ije.ir/article_164066_e2baa7a7593127955335227ad4adbf8a.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Comparative Analysis of Web Hosting Server Performance55856416497710.5829/ije.2023.36.03c.16ENE. B. SetiawanFaculty of Engineering and Computer Science, Universitas Komputer Indonesia, Bandung, Indonesia0000-0001-9275-8959A. SetiyadiFaculty of Engineering and Computer Science, Universitas Komputer Indonesia, Bandung, IndonesiaJournal Article20221211This research discusses the comparison performance of different hosting servers. The hosting server that is used as a comparison consists of four types. Namely, Indonesian shared hosting servers, foreign shared hosting servers, Indonesian virtual private servers, and foreign virtual private servers. The parameters tested in this study are load time, domain name system, connection, and secure socket layer. The tools used for testing the performance comparison of the hosting server are Dotcom-Tools, Pingdom.com, Webpage Test, and sitespeed. The results of this comparison can be an input for potential users who have plans to online their applications using a hosting server. The total value of web server hosting Indonesian shared hosting servers (SH I) is 28.975 milliseconds (ms), foreign shared hosting servers (SH LN) are 8.267 ms, Indonesian virtual private servers (VPS I) are 14.195 ms, Foreign virtual private servers (VPS LN) are 11.835 ms. This research concludes that foreign shared hosting servers (SH LN) are the best web hosting servers because, on some of the parameters tested, this server has the best value because it gets the lowest value with 8.267 ms.https://www.ije.ir/article_164977_85efcb463fbd3bd01208077fade8da82.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Equilibrium of Ammonia (NH3) and Ammonium (NH4+) during Microalgae Harvesting using Electrocoagulation56557216586710.5829/ije.2023.36.03c.17ENP. PurwonoDoctoral Program of Environmental Sciences, School of Postgraduate Studies, Diponegoro University, Semarang, IndonesiaH. HadiyantoDoctoral Program of Environmental Sciences, School of Postgraduate Studies, Diponegoro University, Semarang, IndonesiaCenter of Biomass and Renewable Energy (CBIORE), Chemical Engineering Department, Diponegoro University, Semarang, Indonesia0000-0003-0074-7078M. A. BudihardjoDepartment of Environmental Engineering, Faculty of Engineering, Diponegoro University, Semarang, IndonesiaJournal Article20221111Harvesting microalgae is an important process in gaining biomass while the remaining water is still rich in nutrients. These nutrients, mainly nitrogen and phosphorous, could cause eutrophication of water bodies (rivers, lakes, and oceans) and ecosystem degradation if discharged directly without proper treatment. Electrocoagulation (EC) is one of the harvesting methods and has several advantages: ease of operation, fast harvesting, adaptability, environmental friendliness, and low footprint. However, EC method for harvesting microalgae has the potential in producing ammonia, which is undesirable due to its threat to the environment. The purpose of this study is to establish the equilibrium of ammonium (NH<sub>4</sub><sup>+</sup>) and ammonia (NH<sub>3</sub>) during <em>Dunaliella salina</em> harvesting. The harvesting was conducted using EC with a variation of 20 volts, 30 min, and 400 rpm. The result shows that the harvesting efficiency can reach 93.72% after 5 min of processing, decreasing the concentration of inorganic nitrogen compounds in total ammonia nitrogen (TAN) to 98.80%.https://www.ije.ir/article_165867_40206f519e0c20413e60125f77c81cc3.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301A Hybrid Approach to Sentiment Analysis of Iranian Stock Market User’s Opinions57358416576610.5829/ije.2023.36.03c.18ENM. AhangariDepartment of Computer Engineering, Faculty of Engineering, Golestan University, Gorgan, IranA. SebtiDepartment of Computer Engineering, Faculty of Engineering, Golestan University, Gorgan, IranJournal Article20221214With the significant growth of social media, individuals and organizations are increasingly using public opinion in these media to make their own decisions. The purpose of sentiment analysis is to automatically extract people’s sentiments from those social networks. Social networks related to financial markets, including stock markets, have recently attracted the attention of many individuals and organizations. people in these networks share their opinions and ideas about each share in the form of a post or tweet. In fact, sentiment analysis in this field is the assessment of people’s attitude towards each share. There are different approaches in sentiment analysis, in this article, a hybrid approach is proposed for sentiment analysis. In this way the feature vector used in machine learning is obtained from a lexicon that is automatically extracted from user’s tweets. This lexicon is made by using stock price information related to user’s opinion. Also, by using the next day’s price information of each share, amendments were suggested to this lexicon. Therefore, the lexicon generated for the feature vector was constructed in three ways, and all three methods reported about an 8% improvement over the baseline method in terms of F-score. The baseline method that is considered for this work, is the Persian version of SentiStrength lexicon which is designed for general purpose.https://www.ije.ir/article_165766_c51cc49bc3e54c8db8d19aeb099b7cb2.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301An Enhanced McCormick Envelopes to Represent Kron's Loss Formula58559316640510.5829/ije.2023.36.03c.19ENH. SharifzadehDepartment of Electrical and Computer Engineering, Hakim Sabzevari University, Sabzevar, Iran0000-0002-8661-0947Journal Article20220128Recently, some researchers have employed the McCormick envelopes method to convexify some NP-hard optimization problems with bilinear terms. However, few publications concentrate on its variants to derive a more tight convex relaxation for practical applications. This paper proposes a new viewpoint on Kron’s loss formula, also known as the B-matrix formula, as an equation having bilinear terms. Relying on the perspective, we transform the loss equation to some linear constraints using an enhanced McCormick relaxation. In the technique, the domain of bilinear variables is divided into some smaller parts to improve the relaxation tightness. Some case studies with different nonconvex terms are considered to verify the effectiveness of the enhanced envelopes for capturing Kron’s loss formula. The findings from the numerical simulations suggest that the proposed approach can represent Kron’s loss equation precisely. Moreover, the method performs more effectively than the other methods available in the literature as it usually converges to more optimal solutions.https://www.ije.ir/article_166405_954713ab757943f9308f8be042320941.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249536320230301Application of a Novel Optimization Algorithm in Design of Lead Rubber Bearing Isolation Systems for Seismic Rehabilitation of Building Structures59460316586910.5829/ije.2023.36.03c.20ENF. MehriDepartment of Civil Engineering, University of Bonab, Bonab, East Azerbaijan, IranS. MollaeiDepartment of Civil Engineering, University of Bonab, Bonab, East Azerbaijan, Iran0000-0001-6592-179XE. Noroozinejad FarsangiFaculty of Civil and Surveying Engineering, Graduate University of Advanced Technology, Kerman, Iran0000-0002-2790-526XM. BabaeiDepartment of Civil Engineering, University of Bonab, Bonab, East Azerbaijan, Iran0000-0002-4627-1768F. GhahramaniDepartment of Civil Engineering, Urmia University, Urmia, IranJournal Article20230103Various mechanical and geometrical parameters have different effects on the isolation system's performance. Thus, a sensitivity study of the isolated structures' behavior is an essential matter. In this regard, the isolation systems should be designed using optimization approaches to consider the effects of the different factors. In this study, the optimal design of the lead rubber bearing (LRB) seismic isolation was conducted by considering mass irregularity and near-fault seismic excitation effects. Also, sensitivity analysis of the behavior of the considered isolated buildings was implemented concerning the mechanical parameters of the LRB system. A nonlinear time history dynamic analysis was used here, and the design optimization of the LRB isolator was programmed using the newly introduced grasshopper optimization algorithm (GOA). The main purpose was to investigate the ability of the GOA to optimize the design parameters of the LRB-isolated frames. The results proved the desirable ability of the GOA to solve optimal design problems for isolation systems. Also, the sensitivity analysis of the seismic behavior of LRB base-isolated structures showed that the yield base shear index had the most important effects. Also, the mass irregularity parameter showed a negligible influence.https://www.ije.ir/article_165869_539748c51f6237981bb4f0c0c1d4af82.pdf