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Makara Journal of Technology
Published by Universitas Indonesia
ISSN : 23552786     EISSN : 23564539     DOI : https://doi.org/10.7454/mjt
Core Subject : Science, Engineering,
Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Electrical & Electronics Engineering Engineering Materials Science & Nanotechnology Mechanical Engineering
MAKARA Journal of Technology is a peer-reviewed multidisciplinary journal committed to the advancement of scholarly knowledge and research findings of the several branches of Engineering and Technology. The Journal publishes new results, original articles, reviews, and research notes whose content and approach are of interest to a wide range of scholars. It also offers rapid dissemination. MAKARA Journal of Technology covers the recent research in several branches of engineering and technology include Electrical & Electronics Engineering, Computer Engineering, Mechanical Engineering, Chemical & Bioprocess Engineering, Material & Metallurgical Engineering, Industrial Engineering, Civil & Architecture Engineering, and Marine Engineering. Criteria used in determining acceptability of contributions include newsworthiness to a substantial part of the engineering & technology and the effect of rapid publication on the research of others. This journal, published three times each year, is where readers look for the advancement of discoveries in engineering and technology.
Arjuna Subject : Teknik (semua kategori) - Teknik (Lain-Lain)
Articles 8 Documents
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Search results for , issue "Vol. 24, No. 3" : 8 Documents clear
A Density Functional Theory Study on using Montmorillonite to Reduce Air Pollution Wungu, Triati Dewi Kencana; Yusfi, Meqorry; Suprijadi, Suprijadi
Makara Journal of Technology Vol. 24, No. 3
Publisher : UI Scholars Hub

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Abstract

In this study, density functional theory (DFT) method is used to investigate the possibility of using a smectite clay mineral called montmorillonite (MMT) in reducing heavy metals, such as Cd, through Cd adsorption. The mechanism of Cd adsorption in MMT is observed theoretically, and the tetrahedrally isomorphic substitution on the upper layer of MMT is considered to observe the role of Al and Fe in strengthening Cd adsorption. Two types of MMT are modeled in this study: Al-MMT and Fe-MMT. The Al-MMT means that Al substitutes one atom in the upper tetrahedral layer of MMT, while Fe-MMT means that Fe substitutes one atom in the upper tetrahedral layer of MMT. According to the DFT calculation, Cd is adsorbed relatively strongly to Al-MMT compared with Fe-MMT, with Cd adsorption energy of –4.55 eV and –2.43 eV for Al-MMT and Fe-MMT, respectively. The density-of-state analysis shows that Cd helps reduce the gap between the highest valence-band energy and lowest conduction-band energy of Al-MMT and Fe-MMT. Thus, Cd/Al-MMT and Cd/Fe-MMT behave in a manner similar to a semiconductor.
Mechanical Alloying-assisted Coating of Fe–Al Powders on Steel Substrate Noviyanto, Alfian; Harjanto, Sri; Widayatno, Wahyu Bambang; Wismogroho, Agus Sukarto; Amal, Muhamad Ikhlasul; Rochman, Nurul Taufiqu
Makara Journal of Technology Vol. 24, No. 3
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Abstract

The coating layer of Fe–Al powders on the steel substrate was prepared by mechanical alloying at room temperature. Fe, Al, and the steel substrates were milled with high-energy ball milling for 32 h with a ball-to-powder ratio of 8 in an argon atmosphere to prevent oxidation during milling. Although mechanical alloying was performed for 32 h, no new phases were observed after mechanical alloying, as analyzed by X-ray diffraction. However, the crystallite size of the milled powders for 32 h decreased by factor two compared with the initial powders. Scanning electron micrographs showed that the coating layers formed >8 h after mechanical alloying. The intermetallic Fe3Al formed after the substrate was annealed at 500 ℃.
Influence of Lithium Bromide on Electrical Properties in Bio-based Polymer Electrolytes Fuzlin, Ahmad Faizrin; Sahraoui, Bouchta; Samsudin, Ahmad Salihin
Makara Journal of Technology Vol. 24, No. 3
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This research presents the influence of lithium bromide (LiBr) on the electrical properties of alginate in bio-based polymer electrolytes (BBPEs) system. Bio-based alginate was prepared using the solution casting technique with various LiBr compositions. The ionic conductivity and electrical properties of the prepared BBPEs samples were studied using electrical impedance spectroscopy over a frequency range of 50 Hz–1 MHz. A maximum ionic conductivity of 7.46 × 10−5 S cm-1 was obtained for a sample containing 15 wt. % lithium bromide-doped alginate BBPEs at ambient temperature (303 K). The electrical analysis revealed that the most conductive sample based on alginate-LiBr BBPEs has optimum dielectric constant and loss, which significantly increases as temperature increases. The dielectric properties show that all alginate-LiBr BBPEs are in non-Debye behavior conditions, where no single relaxation occurs in the present system.
Performance of Free-space Optical Communication Systems using Optical Amplifiers under Amplify-forward and Amplify-received Configurations Darusalam, Ucuk; Raj, Arockia Bazil; Zulkifli, Fitri Yuli; Priambodo, Purnomo Sidi; Rahardjo, Eko Tjipto
Makara Journal of Technology Vol. 24, No. 3
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Abstract

With the growth of digital technology in the stage of industrial revolution 4.0, the demand for broadcasting large amounts of information to last mile users has increased. Free-space optical (FSO) communication is one of the telecommunication platforms that has shown immense potential in meeting the demand for information broadcasting. In this work, the performance of FSO communication based on wavelength division multiplexing with a data rate of 80 Gbps is investigated through simulations. The configuration of optical amplifiers in the FSO system is set up on the basis of the amplify-forward and amplify-received configurations to expand the network. The investigation is aimed at identifying the best optical signal amplification between an erbium-doped fiber amplifier (EDFA) and a semiconductor optical amplifier (SOA) under an atmospheric channel. Simulation results show that the EDFA performs better than the SOA in terms of the optical signal amplification for eight channels of the C band. The maximum optical propagation path length under the atmospheric channel for the amplify-forward and -received schemes using the EDFA is 1.7 km, with the bit error rate achieved at 10−6.
ISO 9001:2015 Risk-based Thinking: A Framework using Fuzzy-Support Vector Machine Corpuz, Ralph Sherwin A.
Makara Journal of Technology Vol. 24, No. 3
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Risk-based thinking (RBT) is one of the distinct new features of the International Organization for Standardization 9001:2015. Interestingly, the standard does not prescribe any tools. Hence, organizations are puzzled as to the extent of conformance. Some organizations have adopted formal tools. However, these tools seem insufficient in linking the standard into an evidence-based decision support system. To resolve gaps in RBT implementation, this paper proposes a framework based on fuzzy inference system (FIS) and support vector machine (SVM) to automate risk analysis and evaluation, proposal and verification of action plans, and prediction of the feasibility of risks and opportunities according to text patterns. Modeling results indicate that the framework has no significant difference in terms of accuracy compared with the conventional method. Both FIS-1 and FIS-2 models, however, are statistically significantly faster at 3.26 and 1.15 s, respectively. Meanwhile, the SVM model, whose text classification features are not evident in the conventional method, has a 97.16% classification accuracy and 2.6% confusion error during training, and 95% classification accuracy during testing. Results affirm that FIS and SVM are efficient tools in feasibly conforming with the RBT requirements of the ISO 9001:2015 international standard.
Influence of the Shaping Process on the Tensile Properties of Steel Reinforcement Bars Carbon Steel Grades BJTP24 and BJTS40 Handika, Nuraziz; Idhar, Ridha Amalia; Sjah, Jessica; Arijoeni, Essy; Tjahjono, Elly
Makara Journal of Technology Vol. 24, No. 3
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According to the current applicable national standard in Indonesia, i.e. SNI 07 2529 1991, in addition to the limitation on the loading rate, the steel bar must be reduced, formed, or lathed, as part of the shaping process of samples. This study determined and compared the effect of the shaping process on the yield strength, ultimate strength, and percent elongation by conducting tensile tests of steel bar grade BJTS40, i.e. deformed bar type of steel, and grade BJTP24, i.e., plain bar type of steel. Three diameters of the deformed bar (BJTS40) and one diameter of the plain bar (BJTP24) were used. Samples of the bars were taken randomly from a local distributor in the Greater Jakarta area. Each 1 m of the bar is divided into two, i.e. one end being the non-shaped sample and the other end being the shaped sample. Tensile tests of these two sides were conducted. This study determined that the shaping process influences the results of the tensile test, particularly the variation of percent elongation. Moreover, the effects of the shaping process can be inferred from the high coefficients of variation of yield strength (4.33%) and ultimate strength (2.40%) of the shaped sample. The results of this study, which elucidate the effects of the shaping process on tensile tests, can be used as an information resource in engineering practice.
Ionic Conductiviy of Alginate-NH4Cl Polymer Electrolyte Khan, Nurhasniza Mamajan; Ali, Noor Saadiah Mohd; Fuzlin, Ahmad Faizrin Ahmad; Samsudin, Ahmad Salihin
Makara Journal of Technology Vol. 24, No. 3
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Abstract

This study aims to produce a solid biopolymer electrolyte (SBE) by doping ammonium chloride (NH4Cl) into alginate. Solution casting was used to prepare the alginate–NH4Cl SBE system. Electrical impedance spectroscopy was performed to analyze the electrical properties of the SBE under the applied frequency range of 50 Hz–1 MHz. The incorporation of 8 wt.% NH4Cl enhances the ionic conductivity of the SBE up to 3.18 × 10-7 S/cm at ambient room temperature. Fourier transform infrared spectroscopy shows that complexation occurs between the hydroxyl (-OH), carboxylate (COO-) and ether linkage (C-O-C) functional groups due to the formation of inter- and intra-molecular hydrogen bonds between the biopolymer and the ionic dopant. The dielectric constant and dielectric loss increase with increasing dopant composition, thereby increasing the number of charge carriers and ionic mobility.
Use of Viscoplastic Damper for Improving the Resistance of Steel Frames to Blast Loading Abdollahzadeh, Gholamreza; Faghihmaleki, Hadi; Jamnani, Hamed Hamidi; Bardar, Atefeh Ebrahimi
Makara Journal of Technology Vol. 24, No. 3
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In this paper, we evaluated the effect of viscoplastic dampers on the response of steel frames under blast loading. We used SAP2000 software and link elements to investigate the responses of nine-story steel frames with and without dampers. The proposed viscoplastic damper is a new type of viscous damper. The application of this damper is based on the availability of its constituent materials. The damper acts as a viscoelastic damper at low levels of vibration, but it acts as a combination of viscoelastic operator and metal-yielding device at extreme levels of vibration. With respect to the height of the structure, the need for the correct distribution is underlined, which is addressed by developing a non-uniform loading at the height of the structure. We used A.T.-Blast software program to measure the required parameters to calculate the pressure coming from the blast. The comparison of the simulation results with and without dampers demonstrated about 33% reduction in responses with respect to the top floor displacements and about 59% reduction in modeling the nine-story steel frame with brass and bending moments at column bases, which represents the optimal operation of viscoplastic damper in steel frame under blast loading. It is demonstrated that using viscoplastic damper with brace improves the blast resistance of structures.

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