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Journal of Engineering and Technological Sciences

JETS
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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 â€“ 2012) Proceedings ITB on Engineering Science (2003 - 2007) Proceedings ITB (1961 - 2002)

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Articles 1,267 Documents

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A Strategy for Sustainable Development: Using Nanotechnology for Solar Energy in Buildings (Case Study Parand Town) Mahdi Nejad, Jamal-e-Din; Asadpour, Faezeh
Journal of Engineering and Technological Sciences Vol 51, No 1 (2019)
Publisher : ITB Journal Publisher, LPPM ITB

Solar energy is a source of free and clean energy that has no harmful environmental effects. Simple applications of new technologies such as nanotechnology are a cost-effective way of using renewable energy, which has led many industries to invest in this area. In this descriptive-analytical study the utilization of solar energy in a hot and dry region of Iran was investigated as a useful and safe resource for supplying the energy needed for the construction of Parand town, considering the available climatic potentials. The statistical population in this study was a group of inhabitants of Parand town, employees of the Tehran Construction Engineering Organization and experts in the field, from which 384 participants were selected by simple random sampling. After collecting field information through a questionnaire, the relationships between the variables of the study were tested by SPSS. The result of the study showed that the most important achievements of using nanotechnology for solar energy in view of the sustainable development of building construction from the participants’ perspective were photovoltaic coating on building roofs (58.7% of the participants’ responses), nano solar water heaters (57.4% of responses) and active solar cell dryers (22.1% of responses) respectively.

Effects of Grinding Process on the Properties of the Coal Bottom Ash and Cement Paste Mangi, Sajjad Ali; Wan Ibrahim, Mohd Haziman; Jamaluddin, Norwati; Arshad, Mohd Fadzil; Memon, Sheeraz Ahmed; Shahidan, Shahiron
Journal of Engineering and Technological Sciences Vol 51, No 1 (2019)
Publisher : ITB Journal Publisher, LPPM ITB

The grinding process is necessary to convert original coal bottom ash (CBA) into a powder form. The aim of this study is to evaluate the grinding process effects on physical properties of CBA, it influences on consistency and setting time of cement paste and to predict it potentiality based on chemical characteristics to reduce the alkali-silica reaction (ASR) in concrete. The CBA is the by-product of coal based thermal power plant. Due to high production of electricity in Malaysia, the excess amount of CBA has been produced annually and it causes the environmental problems. Therefore, it is necessary to come up with advanced solutions for that pollution. This study considered the different grinding periods i.e. 2, 10, 20, and 40hrs as to produce different particle fineness. It was perceived through the laboratory findings that the more the grinding period, finer the particle sizes. Besides that, cement paste with 10, 20 and 30% of ground CBA as a substitute of ordinary portland cement (OPC) by weight was prepared, it was observed that the consistency of OPC paste increases with the addition of ground CBA. Moreover, initial and final setting time of cement paste containing ground CBA was observed higher than the OPC paste. Hence, based on experimental analysis and energy efficiency scenario, grinding period of 20hrs with specific surface area 3835.75 cm2/g is suggested for the future studies.

Overview of Health Impacts due to Haze Pollution in Johor, Malaysia Hanafi, Nur H.; Hassim, Mimi Haryani; Noor, Zainura Z.
Journal of Engineering and Technological Sciences Vol 50, No 6 (2018)
Publisher : ITB Journal Publisher, LPPM ITB

Haze pollution is one of the major environmental issues caused by aerosols, having brought about a history of heavy smog pollution events like the London smog in 1952 and the Los Angeles smog in the 1960s. However, in Malaysia, haze events are attributed to forest and peat fires in Kalimantan and Southern Sumatra, Indonesia. The burned biomass basically contains concentrated particulate matters that are hazardous to health among susceptible population groups. Based on the extensive literature review conducted, the small number of available local studies on the health effects of air pollution in Malaysia conducted so far focused on air pollution sciences. In this paper, a comprehensive overview of studies done on the impacts of haze on health conditions among populations in Malaysia is presented. The result shows that the number of upper respiratory tract infection cases was directly proportional to the particulate matter concentration and Air Pollution Index value in Johor in the years 2014 and 2015. Particulate matteris the major contributor in the formation of heavy hazes and is more likely to initiate detrimental health effects compared to other inhalable particles due to their size, large area, and strong activity, making them more likely to carry harmful substances causing a higher number of infected patients with upper respiratory tract infections.

Comparative Study of Bacterial Cellulose Film Dried Using Microwave and Air Convection Heating Indriyati, I.; Irmawati, Yuyun; Puspitasari, Tita
Journal of Engineering and Technological Sciences Vol 51, No 1 (2019)
Publisher : ITB Journal Publisher, LPPM ITB

An investigation was conducted to analyze and compare the properties of bacterial cellulose (BC) films dried using microwave and air convection heating. Prior to the drying process, 90% of the water content inside the BC pellicles was removed through vacuum filtration. After that, the required drying time was only 3-5 min using microwave heating, 95% shorter than that observed for air convection heating. The properties of the BC sheets were characterized by Fourier transform infrared (FTIR), X-ray diffractometer (XRD), color difference meter, and tensile tester machine. The results showed that the structure of the BC films was the same for the BC films dried by microwave and air convection heating, i.e. cellulose I, as observed from FTIR spectra and XRD diagrams. Moreover, their color (L*, a*, and b* values) and mechanical properties were also almost identical. However, a slightly lower crystallinity and a higher swelling degree were observed for the BC film dried using microwave heating. These results suggest that microwave heating could be an alternative method of drying BC pellicles in order to shorten the processing time and reduce energy consumption when compared to air convection heating.

Cutter Load Distribution Analysis and Crown Shape Optimal Design of Complex Curved PDC Bit Pei, Ju
Journal of Engineering and Technological Sciences Vol 51, No 1 (2019)
Publisher : ITB Journal Publisher, LPPM ITB

When drilling in hard rock formations, the wear of the complex curved PDC bit is extremely uneven. To solve this problem, a numerical simulation method was used to analyze the load distribution law of the cutters and the crown shape of the complex curved PDC bit was optimized. The simulation results showed that: 1) along the radial direction of the bit, the axial load on the cutters increased first and then decreased, while the radial load decreased first and then increased; 2) the axial load on the cutters was the largest at the nose and taper area of the bit, while the radial load on the cutters was the largest at the center and shoulder area of the bit; 3) the influence of the inner cone angle on the cutting load was mainly concentrated in the bit crown’s inner cone area, while the influence of the outer arc radius on the cutting load was mainly concentrated in the bit crown nose and taper areas. Based on these conclusions, the crown shape of the complex curved PDC bit was optimized and a field test was carried out. The test results showed that, compared with the original complex curved PDC bit, the average bit life and drilling efficiency of the new designed bit was increased by 20% and 18%, respectively, especially in hard rock drilling. The average drilling efficiency of the new designed bit was increased by 50%.

Development of Instant Microbial Starter for Production of Fermented Cassava Flour: Effect of Vacuum Drying Temperature, Carrier Media, and Storage Temperature Kresnowati, Made Tri Ari Penia; Bindar, Yazid; Rahmina, Fathya
Journal of Engineering and Technological Sciences Vol 50, No 6 (2018)
Publisher : ITB Journal Publisher, LPPM ITB

Cassava is an important crop for tropical countries such as Nigeria, Brazil, Thailand, and Indonesia. The potential utilization of cassava in the food industry can be enhanced by processing cassava into fermented cassava flour (fercaf), which has been shown to have a neutral color and aroma as well as low cyanogenic content. The use of specific microbial starter in the cassava chip fermentation for fercaf production will direct the fermentation process, maintaining a high quality of the produced flour. Thereby, the availability of an easy-to-use microbial starter is important for the production of fermented cassava flour. The aim of this study was to evaluate vacuum drying methods in the preparation of microbial starter for fermented cassava flour production. In particular, the effects of carrier media, drying and storage temperature on cell viability in dry starter were tested. The results showed that different methods should be applied to different microbial species. Bacillus subtilis and Aspergillus Oryza should be prepared using fercaf as the carrier media at a drying temperature of 55 °C, whereas Lactobacillus plantarum starter should be prepared using skim milk as the carrier media at a drying temperatur of 40°C. Apart from B. subtilis, the starters should be stored in a refrigerator.

Calculation of Peak Particle Velocity Caused by Blasting Vibration in Step Topography Yang, Xi
Journal of Engineering and Technological Sciences Vol 50, No 6 (2018)
Publisher : ITB Journal Publisher, LPPM ITB

High ground vibrations not only adversely affect the integrity of the structures in a mine area but also create inconvenience for the nearby population. In order to protect the Sanyou Mine slope in Tangshan, China from blasting vibration, the peak particle velocity in step topography must be accurately calculated. At present, the reflection coefficient of the stress wave at free interface is not considered in the equation for calculating the peak particle velocity in step topography. Therefore the accuracy of the peak particle velocity calculation is decreased in the side direction when the reflection coefficient changes. In this study, a 3D finite element analysis was employed for modeling of the blasting vibration. A series of field-testing experiments was conducted to measure the peak particle velocity. Then the reflection coefficient of the stress wave was calculated. Based on this, the principle of the peak particle velocity in step topography was explained. In addition, the application range of the equation in step topography was determined and a new equation for peak particle velocity calculation in step topography is proposed based on the numerical simulation analysis and field-testing experiment.

Minimizing Electricity Fuel Cost of Thermal Generating Units by Using Improved Firefly Algorithm Nguyen, Thang Trung; Nguyen, Bao Quoc; Nguyen, Phuong Duy; Hien, Chiem Trong
Journal of Engineering and Technological Sciences Vol 51, No 1 (2019)
Publisher : ITB Journal Publisher, LPPM ITB

This paper presents the application of an improved firefly algorithm (IFA) for minimizing total electricity generation fuel cost while all loads are supplied by thermal generating units. The proposed IFA was developed by combining two proposed improvements of the firefly algorithm (FA), i.e. improvement of the distance between two considered solutions and improvement of the new-solution production technique. The effect of each proposed improvement on the conventional firefly algorithm (FA) and the performance of IFA were investigated in two study cases, i.e. single- and multi-fuel option based thermal generating units. In the first case, three different systems with three, six and twenty units were employed, while a ten-unit system with four different loads was tested in the second case. The comparison results between IFA and existing methods, including three other FA variants, revealed that the two proposed improvements of FA are very efficient and make IFA a very promising meta-heuristic algorithm for minimizing fuel cost of thermal generating units.

Non-linear Numerical Modeling of Partially Pre-stressed Beam-column Sub-assemblages Made of Reactive Powder Concrete Budiono, Bambang; Nurjannah, Siti Aisyah; Imran, Iswandi
Journal of Engineering and Technological Sciences Vol 51, No 1 (2019)
Publisher : ITB Journal Publisher, LPPM ITB

Three partially pre-stressed interior beam-column sub-assemblages (SI) and two partially pre-stressed exterior beam-column sub-assemblages (SE) made of reactive powder concrete as test specimens were numerically modeled using a finite element program. The objective of this study was to investigate the behavior of the SI and SE numerical models. The numerical model inputs were: material data, details of test specimen dimensions, and test specimen reinforcements. The numerical models were subjected to the same loads as those applied experimentally. The numerical modeling results were hysteretic and backbone curves and stress distribution contours. The numerical model outputs showed good similarity with the experimental results. The stress distribution contours of the numerical models correlated with the crack patterns in the joint zone of the test specimens. The behavior of the SI numerical models differed from the SE numerical models due to various stresses on the beam plastic joints and the joint zones.

Influence of Electrode Distance on Electrical Energy Production of Microbial Fuel Cell using Tapioca Wastewater Harimawan, Ardiyan; Devianto, Hary; Al-Aziz, Rd. Habib R. M. T.; Shofinita, Dian; Setiadi, Tjandra
Journal of Engineering and Technological Sciences Vol 50, No 6 (2018)
Publisher : ITB Journal Publisher, LPPM ITB

Microbial fuel cell is one alternative technology that can be used to simultaneously solve problems related with wastewater production and energy demand. This study investigates the influence of electrode distance on power density in microbial fuel cell using tapioca wastewater. Graphite sheet without metal catalyst was used for both electrodes, separated by Nafion membranes. Four variations of electrode distance were used. MFC with highest electrode distance give the highest equilibrium OCV (676 mV), while the MFC with shortest electrode distance give the highest power density (7.74 mW/m2). EIS measurement suggested that the charge transfer resistance is dominant in all MFC configuration. Wastewater COD removal were in the range of 35-46 %, which were in accordance with the power density for all MFC.

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