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INDONESIA
Journal of Engineering and Technological Sciences
Published by Institut Teknologi Bandung
ISSN : 23375779     EISSN : 23385502     DOI : -
Core Subject : Engineering,
Engineering
Journal of Engineering and Technological Sciences 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. Starting from Vol. 35, No. 1, 2003, full articles published are available online at http://journal.itb.ac.id, and indexed by Scopus, Index Copernicus, Google Scholar, DOAJ, GetCITED, NewJour, Open J-Gate, The Elektronische Zeitschriftenbibliothek EZB by University Library of Regensburg, EBSCO Open Science Directory, Ei Compendex, Chemical Abstract Service (CAS) and Zurich Open Repository and Archive Journal Database. Publication History Formerly known as: ITB Journal of Engineering Science (2007 – 2012) Proceedings ITB on Engineering Science (2003 - 2007) Proceedings ITB (1961 - 2002)
Arjuna Subject : -
Articles 1,267 Documents
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Increasing the Yield of Powder and Bioactive Materials during Extraction and Spray Drying of Dragon Fruit Skin Extracts Dian Shofinita; Yazid Bindar; Tjokorde Walmiki Samadhi; Najwa Shufia Choliq; Arwinda Aprillia Jaelawijaya
Journal of Engineering and Technological Sciences Vol. 53 No. 6 (2021)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2021.53.6.12

Abstract

One potential utilization of dragon fruit skin is to produce bioactive materials as natural antioxidants and colorants for the food industry by extraction and spray drying. This study investigated the quality (total phenolic compounds/TPC, betacyanin and betaxanthin contents, and antioxidant activity) of the extracts and spray-dried products, and the quantity (powder yield) obtained by the use of different types and amounts of spray drying agents. Two drying agents were introduced during spray drying, i.e. maltodextrin and whey protein isolate (WPI). The result showed that a lower extraction solvent to solid ratio may result in a lower yield of TPC, betacyanin and betaxanthin contents, and also in antioxidant activity of the dragon fruit skin extract. In addition, maltodextrin and WPI were found to be able to significantly increase the yield from spray drying. The highest yield (72.7 ± 8.4%) was obtained with the use of 40% maltodextrin as drying agent, while the control yielded 9.5 ± 1.8%. Furthermore, it was found that the spray-dried product could recover more than 90% of the TPC and betacyanin in the extracts, which indicates that spray drying may be suitable for heat-sensitive materials.
The Effect of Acids on Alkaloid Yield in Pressurized Water Extraction of Narcissus Pseudonarcissus Orchidea Rachmaniah; Jaap van Spronsen; Robert Verpoorte; Geert Jan Witkamp
Journal of Engineering and Technological Sciences Vol. 53 No. 6 (2021)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2021.53.6.8

Abstract

Pressurized water (PW) extraction of galanthamine from Narcissus pseudonarcissus bulbs was performed. The obtained yield was compared with the yield from conventional acidified water extraction and methanolic Soxhlet extraction. Both PW and conventional acidified water extraction were followed by a subsequent purification step for the alkaloids. The PW extraction (70 °C, 150 bar, 45 min) yielded as much galanthamine as methanolic-Soxhlet extraction (ca. 3.50 mg/g). Meanwhile, acid-base extraction with 1% of HBr (v/v) at 65 °C for 3 h gave a lower yield (ca. 2.65 mg/g). A higher PW temperature did not significantly increase the galanthamine yield. Pressure increase is not necessary since more water-soluble compounds such as proteins and polysaccharides are co-extracted, resulting in high viscosity of the water extract solution, which hampers the filtration process. Hence, the acidity of the solution is highly important both in the case of PW extraction and acidified water extraction. Besides galanthamine, the total alkaloid profile following Narcissus alkaloids was also obtained. Lycoramine, O-methyloduline, norgalanthamine, epi-norgalanthamine, narwedine, oduline, haemanthamine, O-methyllycorenine, and a haemanthamine derivate were identified. Although a high yield was obtained from PW extraction, the further purification needs to be improved to obtain an economically feasible industrial extraction process.
The Potential of Corncobs in Producing Reduced Graphene Oxide as a Semiconductor Material Kusuma Wardhani Mas'udah; Ahmad Taufiq; Sunaryono Sunaryono
Journal of Engineering and Technological Sciences Vol. 54 No. 2 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.2.1

Abstract

A simple chemical approach was developed to synthesize reduced graphene oxide (RGO) from corncob waste through the acid-base method with the addition of PEG-2000 at specific concentrations. The morphology and structure of RGO were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The process of reduction and quality of RGO were examined carefully with UV-Vis spectroscopy, infrared spectroscopy, and X-ray diffractometry. Based on the treatment and characterization, the diffraction data showed a prominent peak of RGO at a 2-theta position of 24.01°. The existence of C=C functional groups was detected in aromatic compound groups and alkene functional groups in aliphatic hydrocarbon compounds by infrared spectroscopy. The use of corncobs as the main raw material synthesized by an environmentally friendly route has tremendous potential in producing RGO that can be used as an efficient semiconductor material.
Microwave Absorbing Material of Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) with Broadband Characteristic at X-band Frequency Yohanes Edi Gunanto; Henni Sitompul; Maya Puspitasari Izaak; Yosep Sarwanto; Wisnu Ari Adi
Journal of Engineering and Technological Sciences Vol. 54 No. 2 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.2.2

Abstract

In this study, hexaferrite Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) was synthesized and characterized, which can be applied as microwave absorber in the X-band frequency range. It is a potential candidate for a radar absorbing material for microwave absorption, particularly for use in anti-radar paint in the defense sector. Samples were prepared using solid state reaction synthesis with high energy milling. After sintering at the right temperature, the samples were characterized using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a vibrating-sample magnetometer (VSM) and vector network analysis (VNA). The XRD characterization results indicated that all samples were in phase and had a hexagonal lattice structure with a P63/mmc space group and a crystallite size between 38 and 45 nm. The surface morphology of the characterization results using SEM showed a heterogeneous particle shape with particle sizes ranging from 140 to 200 nm. Substitution of Ti4+ ions for Fe3+ ions by Zn2+ ions resulted in a decrease of the magnetic saturation (Ms), the magnetic remanence, and the sample’s coercivity field. With a sample thickness of 1.5 mm, the VNA results confirmed that the ability to absorb microwaves and bandwidth will increase along with increase of the substitution value x. The reflection loss value was about -13.3 dB at a frequency of around 11 GHz, with a bandwidth of 1.4 GHz for the sample with x = 1.0 composition.
Risk Assessment and Fractionation of Cadmium Contamination in Sediment of Saguling Lake in West Java Indonesia Dwina Roosmini; Eka Wardhani; Suprihanto Notodarmojo
Journal of Engineering and Technological Sciences Vol. 54 No. 2 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.2.3

Abstract

This research focused on the speciation and distribution patterns of cadmium in surface sediment from Saguling Lake, which is located in the Upper Citarum River. Organic compounds and heavy metals from anthropogenic activities in the watershed have contaminated the river. Sample from the upper layer of the sediment from Saguling Lake were taken from 12 locations, representing the dry and the rainy seasons in the period 2015-2018. Sediment cadmium (Cd) classification was conducted through a sequential extraction technique to determine Cd’s bioavailability and its risk to the water environment. During the rainy season, the total Cd concentration in the upper layer of the sediment was higher than during the dry season. The average dry and rainy season concentrations were 11.12 ± 2.16 mg/kg and 14.82 ± 1.48 mg/kgm in the sampling locations, distributed differently with the following order of the largest to the smallest concentration: 10B > 1A > 4 > 3 > 2 > 1B > 10A > 7 > 9 > 5 > 6 > 8 for the dry season, and 4 > 1A > 1B > 2 > 7 > 5 > 9 > 3 > 6 > 10A > 8 > 10B for the rainy season. All sampling locations (>60%) showed Cd in the resistant fraction, indicating no significant anthropogenic input of Cd into the surface sediment but more geological input due to high erosion. The values of RAC, ICF, and GFC indicate that the Cd in the surface sediment can be categorized as low risk.
An Environment-Friendly Rock Excavation Method Ze Gan; Xi Yang; Yunpeng Zhang; Xu Wu; Jie Wang
Journal of Engineering and Technological Sciences Vol. 54 No. 2 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.2.12

Abstract

Blasting is used as an economical tool for rock excavation in mines. However, part of the explosive energy is converted into elastic waves, resulting in ground vibration and excessive vibration, which may cause damage to nearby buildings. Meanwhile, toxic gases are also produced during the explosion. In this paper, an environment-friendly method for rock excavation is proposed. A series of vibration tests were conducted, and the peak particle velocity was monitored. The results showed that the proposed method can replace the conventional blasting method in mines. Besides that, the vibration caused by the proposed method is much smaller than by the conventional method. By adjusting the direction of the high-pressure gas injection, buildings around the mine can be protected well from vibration. Also, the production of toxic gases during excavation will no longer be a problem. Thus, a milder environmental impact can be achieved. However, the rocks excavated by the proposed method are relatively large, which still need to be broken further. On this issue, further study is required.
Kinetics and Characterization of Microalgae Biofuel by Microwave-assisted Pyrolysis Using Activated Carbon Viqhi Aswie; Lailatul Qadariyah; Mahfud Mahfud
Journal of Engineering and Technological Sciences Vol. 54 No. 2 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.2.7

Abstract

The reaction kinetics and the effect of power on microwave-assisted pyrolysis (MAP) in converting microalgae to biofuel were investigated to determine the decomposition mechanism and then characterize the best product. The resulting product consisted of three phases, namely liquid phase (bio-oil), solid residue (char), and uncondensable gas products. The results showed that the optimal increase in microwave power obtained was 20.57% with a 600-watt microwave power condition, a reaction time of 20 minutes, a microwave absorber to microalgae ratio of 1:6, and a heating rate of 25.96 K/min (600 watts). The reaction kinetics evaluated in the best condition showed a second-order reaction with activition energy (Ea) and pre-exponential factor (A) at 35.5971 kJ/moles and 2,606.75/minute, respectively. The characteristics of the biofuel product obtained were 1.01 gr/mL density, viscosity 10.97 cP, and pH 9.30. In addition, based on GC-MS analysis, the bio-oil contained aliphatic, aromatic, phenol, FAME, and polycyclic aromatic hydrocarbon (PAH) organic compounds. These results indicate that MAP has the potential to be developed as an alternative production process for biofuels.
Experimental and Numerical Analysis of Carbon/Epoxy Composite Plate Subject to Low-Velocity Impact Muhamad Giri Suada; Hendri Syamsudin; Haroen Romadon
Journal of Engineering and Technological Sciences Vol. 54 No. 2 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.2.4

Abstract

The present work compared experimental and finite element analysis on the low-velocity impact response of a carbon/epoxy composite plate. Finite element analysis was based on the utilization of cohesive zone elements with the Benzeggagh-Kenane fracture criterion to predict the initiation and propagation of delamination. A Kirchhoff based formulation of a continuum shell element was used to model the stiffness of each lamina and the Hashim-Rotem damage mechanism to predict damages in every lamina. Five specimens of a 16-layer uni-directional carbon/epoxy composite plate with fiber orientation [+45°/90°/-45°/0°/+45°/90°/-45°/0°] s were subjected to low-velocity impact with a single energy value of 2.75 Joule/mm. The experimental results were then compared to the finite element results. Good agreement was achieved for the size and shape of the total projected delamination and visual damage to the top and bottom surface in the form of matrix and fiber failure. Slight differences were found for the dynamic response in the impact force history. Furthermore, a significant difference was found for the quantity of absorbed energy.
Engineering Properties of Palm Oil Clinker Fine-Modified Asphaltic Concrete Mixtures Nura Shehu Aliyu Yaro; Madzlan Napiah; Muslich Hartadi Sutanto; Aliyu Usman; Intan Kumalasari Mizwar; Aliyu Mani Umar
Journal of Engineering and Technological Sciences Vol. 54 No. 2 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.2.5

Abstract

Palm oil clinker (POC) is a non-biodegradable palm mill by-product typically discarded in dumpsites. This study analyzed the performance of POC powder (POCF) as bitumen modifier in terms of conventional and engineering properties of bitumen and asphalt mixture. For the study, base bitumen of 60/70 penetration grade was utilized and different POCF dosages (0, 2, 4, 6, and 8% by weight of bitumen) were added. The base bitumen was effectively modified with POCF and then characterized. The conventional and engineering properties of the modified bitumen and asphalt mixtures were assessed. From the characterization results, the formation of Si-O crystalline structure and a new Si-OH functional group was identified. Furthermore, a meandering pattern was observed due to the modification of the base bitumen with POCF. Based on the conventional test results it was revealed that the addition of POCF to the base bitumen resulted in a stiffer blend compared to unmodified bitumen. The addition of POCF improved the modified mixtures’ Marshall stability relative to the unmodified mixtures. Analysis of variance (ANOVA) and regression modeling showed the influence and significance of POCF-MB, with R2 values of (95-99%). Finally, the 4-6% POCF dosage was found to be the optimum dosage, yielding the best performance in terms of the engineering properties evaluated.
A New Mechanical Analysis of a Crankshaft-connecting Rod Dynamics Using Lagrange’s Trigonometric Identities Hasan H. Ali; Firas M. Abdulsattar; Ahmed W. Mustafa
Journal of Engineering and Technological Sciences Vol. 54 No. 2 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.2.9

Abstract

The main objective of this study was to conduct a new and simple but accurate analysis of the dynamics of a crankshaft-connecting rod system based on Lagrange’s trigonometric identities. Actual and equivalent connecting rod mass approximations of single- and multi-cylinder reciprocating engines were studied. Several examples were studied to demonstrate the dynamics of the system. Lagrange’s trigonometric identities were used to simplify the model, while MATLAB was used to obtain the results. For both the proposed reduced model and the full model, the resultant forces and torques of an actual and an equivalent connecting rod mass were compared. The results showed that the proposed reduced model gives force and torque results that match the results of the full model very well. It was shown that the largest torque imbalance resultant on the crankshaft was exerted by the two-cylinder engine. In addition, it was shown that the largest external forces resultant acting in the x-direction was exerted by the one-cylinder engine. The results also revealed that the resultant of external forces acting in the y-direction was zero for multi-cylinder engines. The relative error, which mainly occurred at the points of maximum force and torque, ranged from about 1% to about 15%.

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