Journal of Engineering and Technological Sciences <p style="text-align: justify;"><img class="imgdesc" src="" alt="" /><p style="text-align: justify;"><em>Journal of Engineering and Technological Sciences</em> welcomes full research articles in the area of Engineering Sciences from the following subject areas: Aerospace Engineering, Biotechnology, Chemical Engineering, Civil Engineering, Electrical Engineering, Engineering Physics, Environmental Engineering, Industrial Engineering, Information Engineering, Mechanical Engineering, Material Science and Engineering, Manufacturing Processes, Microelectronics, Mining Engineering, Petroleum Engineering, and other application of physical, biological, chemical and mathematical sciences in engineering. Authors are invited to submit articles that have not been published previously and are not under consideration elsewhere.</p><p style="text-align: justify;">Starting from Vol. 35, No. 1, 2003, full articles published are available online at, and indexed by <a href=";tip=sid&amp;clean=0">Scopus (2020:Q3)</a>, <a href=",p24780957,3.html">Index Copernicus</a>, <a href=";hl=id">Google Scholar</a>, <a href="">DOAJ</a>, <a title="Journal of Engineering and Technological Sciences" href=";tip=sid&amp;clean=0" target="_blank" rel="noopener">The Elektronische Zeitschriftenbibliothek EZB by University Library of Regensburg</a>, <a href=";Find=Journal+of+Engineering+and+Technological+Sciences&amp;SearchType=Contains">EBSCO Open Science Directory</a>, <a href="">Ei Compendex</a>, Chemical Abstract Service (CAS), <a href="">Zurich Open Repository and Archive Journal Database</a>, <a href=";Full=*journal%20of%20engineering%20and%20technological%20sciences">Emerging Sources Citation Index</a> and <a href=";mod=viewjournal&amp;journal=7390">Indonesian Publication Index.</a></p><p style="text-align: justify;">The journal has been also accredited for five years based on The Decree of Directorate General of Research and Development Strengthening, Ministry of Research, Technology and Higher Education of the Republic of Indonesia No. 30/E/KPT/2018, for Volume 50 No.1, 2018 until Volume 54 No. 6, 2022.</p><p>ISSN: <a href="">2337-5779</a>, E-ISSN: <a href="">2338-5502</a></p><p style="text-align: justify;">Published by the Institute for Research and Community Services, Institut Teknologi Bandung, in collaboration with <a href="">Indonesian Engineering Association (<em>Persatuan Insinyur Indonesia-PII</em>).</a></p><span style="text-decoration: underline;"><strong>Publication History</strong></span><p><strong>Formerly known as:</strong></p><ul><li>ITB Journal of Engineering Science (2007 - 2012)</li><li>Proceedings ITB on Engineering Science (2003 - 2007)</li><li>Proceedings ITB (1961 - 2002)</li></ul><p>Back issues can be read online at: <a href=""></a></p><p><span style="text-decoration: underline;"><strong>Scimago Journal Ranking</strong></span></p><a title="SCImago Journal &amp; Country Rank" href=";tip=sid&amp;exact=no"><img src=";title=true" alt="SCImago Journal &amp; Country Rank" border="0" /></a><p> Institute for Research and Community Services, Institut Teknologi Bandung en-US Journal of Engineering and Technological Sciences 2337-5779 Free Convection of Ag/H2O Nanofluid in Square Cavity with Different Position and Orientation of Egg Shaped Cylinder <p>A numerical simulation was conducted to study the free convection of Ag/H<sub>2</sub>O nanofluid between a square cavity with cold walls and an egg shaped cylinder with a hot wall. Utilizing the egg equation, dimensionless governing equations were solved using the Galerkin Finite Element Method (GFEM). In this work, several parameters were studied, i.e. Rayleigh number (10<sup>3 </sup>≤ Ra ≤ 10<sup>6</sup>), volume fraction (0 ≤ <em>φ </em>≤ 0.05), position (-0.2 ≤ <em>Y </em>≤ 0.2), and orientation angle (-90°<sup> </sup>≤ <em>γ </em>≤ 90°). The numerical results are presented as streamline contours, isotherm contours, and local and average Nusselt numbers. Moreover, the results were used to analyze the fluids’ structure, temperature distribution, and heat transfer rate. The numerical results confirmed that the stream intensity value increased with an increase of the Rayleigh number as well as the movement of the cylinder towards the bottom wall for all values of the orientation angle. Variation of the vertical position of the cylinder inside the cavity had a noticeable effect on , which increased by 50% at <em>γ </em>= -90°, and by 58% at <em>γ </em>= -45°. However, at Y = -0.2, increased by 58% at <em>γ </em>= -45° and decreased by 7% at <em>γ </em>= -90°. The highest heat transfer rate was obtained at high Rayleigh number (Ra = 10<sup>6</sup>), volume fraction (<em>φ </em>= 0.05), negative position (<em>Y </em>= -0.2), and the highest positive orientation angle (<em>γ </em>= 90°).</p> Atheer Saad Hashim Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-08-31 2021-08-31 53 4 210409 210409 10.5614/j.eng.technol.sci.2021.53.4.9 Application of Nonlinear Finite Element Analysis on Shear-Critical Reinforced Concrete Beams <p class="Abstract">This paper presents the application of a smeared fixed crack approach for nonlinear finite element analysis of shear-critical reinforced concrete beams. The experimental data was adopted from tests undertaken on twelve reinforced concrete beams by Bresler and Scordelis in 1963, and from duplicate tests undertaken by Vecchio and Shim in 2004. To this end, all beams were modeled in 3D using the software package ATENA-GiD. In the modeling, the nonlinear behaviors of the concrete were represented by fracture-plastic constitutive models, which were formulated within the smeared crack and crack/crush band approaches. The applicability of nonlinear analysis was demonstrated through accurate simulations of the full load-deflection responses, underlying mechanisms, crack patterns, and failure modes of all 24 beams. Detailed documentation of the results is presented to demonstrate the potential and practical value of nonlinear finite element analysis in providing an informed assessment of the safety and performance of reinforced concrete structures.</p> Asdam Tambusay Priyo Suprobo Benny Suryanto Warren Don Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-08-31 2021-08-31 53 4 210408 210408 10.5614/j.eng.technol.sci.2021.53.4.8 Finite Element Simulation of Vacuum Preloading at Palembang – Indralaya Toll Project <p>Methods for the prediction of soil behavior during the application of vacuum preloading are available but have not been used precisely and have not been proven yet in Indonesia. There are two common approaches to vacuum preloading simulation, based on the application of a uniform external load to the vacuum area, and based on suddenly lowering the groundwater level to create vacuum conditions, respectively. This affects the settlement, lateral deformation, and pore pressure predictions. The objective of this research was to improve the prediction of soil behavior based on high-quality field data by using state of the art vacuum preloading simulations. The results were compared with those of a series of instrumentation equipment, i.e. a settlement plate, an extensometer, and a piezometer. This research used data from the Palembang-Indralaya Toll Road, a section of the Trans Sumatera Toll Road that is approximately 22 km long and has an embankment height of about 4 m to 9 m. It was built over a swampy soft soil area, using vacuum preloading to improve the soil. Axisymmetric analysis of vacuum preloading was conducted for a single-drain system, plane-strain analysis was conducted for single- and multiple-drain systems, and 3D analysis was conducted for single-drain, multiple-drain, and cluster-drain systems. The results show that the proposed method produced a good correlation between the predicted data and the recorded monitoring data.</p> Herwan Dermawan Bigman M. Hutapea Endra Susila Masyhur Irsyam Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-09-02 2021-09-02 53 4 210410 210410 10.5614/j.eng.technol.sci.2021.53.4.10 Development of Laboratory-scale Lamb Wave-based Health Monitoring System for Laminated Composites <p>This paper presents the development process of a laboratory-scale Lamb wave-based structural health monitoring (SHM) system for laminated composite plates. Piezoelectric patches are used in pairs as actuator/sensor to evaluate the time of flight (TOF), i.e. the time difference between the transmitted/received signals of a damaged plate and those of a healthy plate. The damage detection scheme is enabled by means of evaluating the TOF from at least three actuator/receiver pairs. In this work, experiments were performed on two GFRP plates, one healthy and the other one with artificial delamination. Nine piezoelectric transducers were mounted on each plate and the detection of the delamination location was demonstrated, using 4 pairs and 20 pairs of actuators/sensors. The combinations of fewer and more actuators/sensor pairs both provided a damage location that was in good agreement with the artificial damage location. The developed SHM system using simple and affordable equipment is suitable for supporting fundamental studies on damage detection, such as the development of an algorithm for location detection using the optimum number of actuator/sensor pairs.</p> Leonardo Gunawan Muhammad Hamzah Farrasamulya Andi Kuswoyo Tatacipta Dirgantara Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-08-31 2021-08-31 53 4 210407 210407 10.5614/j.eng.technol.sci.2021.53.4.7 The Investigation of Machinability and Surface Properties of Aluminium Alloy Matrix Composites <p>Aluminum matrix composites (AMCs) are crucial to the progress of composite application areas due to their remarkable mechanical properties. Their usage has expanded into different fields such as the aerospace, automobile, and defense industries. The present study used wrought Al alloy AA6061 as the matrix, while ilmenite (FeTiO<sub>3</sub>) particles were used as reinforcement at different weight percentages to prepare metal matrix composites. One of the most economical and simple casting routes among the several available fabrication techniques for the preparation of composites is the stir casting method, which was applied in the present investigation to prepare the AMCs. The machinability of the fabricated composites and the surface roughness property after machining were studied to understand the effect of speed and feed during machining. The results showed that an increase in speed decreased the cutting forces and the surface roughness. Meanwhile, an increase in surface roughness was observed with an increase in feed.</p> Priyadarsini Morampudi Venkata Ramana V.S.N. Koona Bhavani Amrita M V Srinivas Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-09-10 2021-09-10 53 4 210412 210412 10.5614/j.eng.technol.sci.2021.53.4.12 LSCF-CuO as Promising Cathode for IT SOFC <p class="Abstract">Infiltration of copper oxide towards LSCF was done in order to enhance cathode performance due to superior properties, including high electrical conductivity and high catalytic activity for the oxygen reduction reaction. Samples were synthesized at different temperatures using the sol-gel route. The TGA results showed that LSCF achieved complete perovskite formation when calcined above 600 °C and DTA showed the formation of lattice oxygen at 550<sup> </sup>°C. XRD analysis showed no shifted peaks and nano size levels were achieved when samples were calcined at 700 °C and 800<sup> </sup>°C. SEM and BET showed similar analysis patterns, where the particle size increased as the calcining temperature was increased. EIS analysis further verified that the polarization resistance of the sample calcined at 700 °C was as small as 0.161 Ω, compared to 1.524 Ω with a calcination temperature of 800 °C. The activation energy of LSCF-CuO was found to be 122.2 kJ/mol, which is much lower than for conventional LSCF.</p> Ahmad Fuzamy Bin Mohd Abd Fatah Mohamad Nazri Murat Noorashrina A. Hamid Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-09-07 2021-09-07 53 4 210411 210411 10.5614/j.eng.technol.sci.2021.53.4.11 On Minimal Second-order IIR Bandpass Filters with Constrained Poles and Zeros <p class="Abstract">In this paper, several forms of infinite impulse response (IIR) bandpass filters with constrained poles and zeros are presented and compared. The comparison includes the filter structure, the frequency ranges and a number of controlled parameters that affect computational efforts. Using the relationship between bandpass and notch filters, the two presented filters were originally developed for notch filters. This paper also proposes a second-order IIR bandpass filter structure that constrains poles and zeros and can be used as a minimal parameter adaptive digital second-order filter. The proposed filter has a wider frequency range and more flexibility in the range values of the adaptation parameters.</p> Endra Joelianto Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-08-03 2021-08-03 53 4 210401 210401 10.5614/j.eng.technol.sci.2021.53.4.1 Theoretical Study of Direct Carbon Dioxide Conversion to Formic Acid on Transition Metal-doped Subnanometer Palladium Clusters <p>We studied the direct conversion of CO<sub>2</sub> to HCOOH through hydrogenation reaction without the presence of base additives on the transition metal-doped subnanometer palladium (Pd<sub>7</sub>) cluster (Pd<sub>x</sub>M: M = Cu, Ni, Rh) by using a combination of density functional theory and microkinetic calculations. It was shown that the CO<sub>2</sub> hydrogenation on Pd<sub>7</sub> and Pd<sub>6</sub>M clusters are more selective towards the formate pathway to produce HCOOH than the reverse water gas shift pathway to produce CO. Inclusion of Ni and Rh doping in the subnanometer Pd<sub>7</sub> cluster could successfully enhance the turnover frequency (TOF) for CO<sub>2</sub> hydrogenation to formic acid at low temperature. The order of TOF for formic acid formation is as follows: Pd<sub>6</sub>Ni &gt; Pd<sub>6</sub>Rh &gt; Pd<sub>7</sub> &gt; Pd<sub>6</sub>Cu. This order can be explained by the trend of the activation energy of CO<sub>2</sub> hydrogenation to formate (HCOO<sup>*</sup>). The Pd<sub>6</sub>Ni cluster has the highest TOF value because it has the lowest activation energy for the formate formation reaction. The Pd<sub>6</sub>Ni system also has a superior TOF profile for HCOOH formation compared to several metal surfaces in low and high-temperature regions. This finding suggests that the subnanometer Pd<sub>x</sub>Ni cluster is a promising catalyst candidate for direct CO<sub>2</sub> hydrogenation to formic acid.</p> Adhitya Gandaryus Saputro Arifin Luthfi Maulana Fine Dwinita Aprilyanti Hermawan Kresno Dipojono Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-08-03 2021-08-03 53 4 210402 210402 10.5614/j.eng.technol.sci.2021.53.4.2 Characteristics of Silica Nanoparticles from Rice Husk as Influenced by Surface Modification with Used Solvent Containing Silane <p>Silica extracted from rice husk (silica nanoparticles, Si-NP RHA) has great potential for industrial use, particularly as filler in the rubber industry. However, silica is poorly dispersed in the matrix and needs to be modified by a silane linking agent (bis-(3-triethoxysilylpropyl) tetrasulfane (TESPT)) to improve its mixing properties. As a result, a large amount of used solvent containing silane TESPT is produced. This study aimed to evaluate the surface modification of silica nanoparticles from rice husk employing this used solvent and to characterize the particles’ physical properties. Silica nanoparticles were extracted from rice husk using a sol-gel method. FTIR spectography demonstrated that the TESPT on fresh solvent and the used solvent were successfully grafted onto the surface of Si-NP RHA. Si-NP RHA modified by Two Step Modification (TSM) employing used solvent had strong absorption peaks at wave numbers of 2927.94 cm<sup>-1</sup> and 1446.61 cm<sup>-1</sup>, which are associated with vibration of the ‑CH<sub>2</sub> group and deforming vibration of the -C-H group in TESPT compounds. Likewise, Si-NP RHA modified with One Step Modification (OSM), either using fresh solvent or the used solvent, exhibited absorption peaks at wave numbers 2935.66 cm<sup>-1</sup> and 1404.18 cm<sup>-1</sup>. The result showed that the used solvent still effectively modified the silica nanoparticle surface. </p> Kendri Wahyuningsih Sri Yuliani Hoerudin Hoerudin Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-08-03 2021-08-03 53 4 210403 210403 10.5614/j.eng.technol.sci.2021.53.4.3 COVID-19 Prevention: Role of Activated Carbon <p>Recently, Coronavirus Disease 2019 (COVID-19) has brought the whole world into a pandemic condition, where the number of infected cases and deaths is exponentially high. A number of vaccines are available for this novel virus, but these are in the preliminary stage and are also not available to everyone. As the virus is very contagious, protection and prevention are the best way to survive and get rid of this disease. The virus affects the human body by entering through the nose, mouth, and eyes, so face protection with an appropriate mask is highly advisable. Combined masks made with activated carbon (AC) can effectively adsorb the virus because of its high surface area and broad functional groups. Such combined masks can also control coronavirus transmission by capturing harmful gases and smoke as they help in decreasing the spread of the virus</p> Md Sumon Reza ABM Kamrul Hasan Abu Saleh Ahmed Shammya Afroze Muhammad Saifullah Abu Bakar Shafi Noor Islam Abul Kalam Azad Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-08-03 2021-08-03 53 4 210404 210404 10.5614/j.eng.technol.sci.2021.53.4.4 An Analytical and Experimental Evaluation of a Heat Sink Under Constant Heat Flow and Forced Convection Heat Transfer <p>In this study, the exact transient differential equation was used to calculate the convection heat loss in a heat sink with a rectangular cross section fin. The result of the analytic solution was compared to the result from experiments conducted on a standard heat sink. The experiments were performed at a constant heat flow of 9000 W/m<sup>2</sup> and a low airflow rate ranging from 12 to 100 cm<sup>3</sup>/s in seven steps. The comparative results showed that while there was good agreement between the experimental result and the exact solution, the average error ratio increased with an increase of the airflow rate. However, the maximum average error ratio between the experimental result and the exact solution did not exceed 6.4%. The maximum temperature distribution in the heat sink was obtained at a time of 900 s in all experiments.</p> Ehsan Fadhil Abbas Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-08-19 2021-08-19 53 4 210405 210405 10.5614/j.eng.technol.sci.2021.53.4.5 Redesign of a Biomechanical Energy Regeneration-based Robotic Ankle Prosthesis using Indonesian Gait Data <p class="Abstract">In this research, the robotic ankle design from Arizona State University (ASU) known as SPARKy was redesigned to accommodate the specific needs of Indonesian people. Most active prosthetic legs are designed based on gait parameters for people from Western countries, which may differ for people from other cultures that have a different anthropometry and economic background. Indonesians have smaller actuating power characteristics compared to people from Western cultures due to their smaller average weight and body height. Thus, the applied design strategy took advantage of a biomechanical energy regeneration scheme to reduce the actuator input power requirement and the relatively smaller mechanical power of the typical Indonesian ankle to create a potentially affordable robotic ankle with a smaller actuator that meets the technical specifications. The specifications of the powered prosthetic ankle were determined through the same methods used by SPARKy. Only one low-level control system, to actuate normal walking, was designed and tested on a fully assembled robotic ankle. The test results indicated a promising low-level control, where the robotic ankle can follow the predetermined trajectory required to actuate normal walking based on Indonesian gait data.</p> Edgar Buwana Sutawika I. Indrawanto F. Ferryanto Sandro Mihradi Andi Isra Mahyuddin Copyright (c) 2021 Journal of Engineering and Technological Sciences 2021-08-10 2021-08-10 53 4 210406 210406 10.5614/j.eng.technol.sci.2021.53.4.6