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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
 99   100   101   102   103 
The Sensitivity of Aerodynamic Forces to Multi-parameters in a Bird-like Flapping Wing Changtao Ding; Yuanjun Lv; Min Lu
Journal of Engineering and Technological Sciences Vol. 50 No. 5 (2018)
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.2018.50.5.5

Abstract

The sensitivity of aerodynamic forces in a bird-like flapping wing was numerically studied by analyzing the aerodynamic force states under different parameters. First, the physical model and the kinematic model of the bird-like flapping wing were separately established. Then the aerodynamic force model was established and some important parameters were analyzed by adopting the Taguchi orthogonal method. Finally, a simulation was carried out, from which the order of the parameters was separately determined according to the parameters' effect on lift or thrust. The results showed that increasing the flapping frequency is one of the most important ways to increase lift and thrust. The lift can be increased by increasing the flight velocity, while the thrust can be increased by increasing the maximum flapping angle. The lift or the thrust becomes larger when the incidence angle is approximately or .
DBSA-Catalyzed Sewage Sludge Conversion into Biodiesel in a CSTR: RSM Optimization and RTD Study Ali A. Jazie
Journal of Engineering and Technological Sciences Vol. 51 No. 4 (2019)
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.2019.51.4.6

Abstract

Sewage sludge from the primary stage of a wastewater treatment plant (WWTP) in Al-Diwaniyah City was direct-transesterified to biodiesel using  dodecylbenzenesulfonic acid catalyst in a system with two continuously stirred tank reactors. The response surface and the central cube design methodologies were used to optimize the parameters affecting the biodiesel yield. The optimum conditions for the process in this study were found to be (residence time: 90 min; catalyst loading 8 wt%; methanol/oil ratio: 18; reaction temperature: 368.15 K). Under the optimum process conditions a biodiesel yield of 96.51% was obtained. The experimental residence time distribution (RTD) was calculated and compartment models were applied for the two-tank reactor system. In the CSTR, a dead zone of (10 liter) was estimated. The independent analysis of fatty acids in the sewage showed that the lipids consisted primarily of palmitic acid (C16:0 = 37.86), oleic acid (C18:1 cis-9 = 19.72) and stearic acid (C18:0 = 17.32), and the acid value was (2.44 mg KOH/g). The properties of the biodiesel produced were comparable with the ASTM D-6751-2 standard and the properties of mineral diesel.
Non-linear Numerical Modeling of Partially Pre-stressed Beam-column Sub-assemblages Made of Reactive Powder Concrete Bambang Budiono; Siti Aisyah Nurjannah; Iswandi Imran
Journal of Engineering and Technological Sciences Vol. 51 No. 1 (2019)
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.2019.51.1.3

Abstract

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.
Minimizing Electricity Fuel Cost of Thermal Generating Units by Using Improved Firefly Algorithm Thang Trung Nguyen; Bao Quoc Nguyen; Phuong Duy Nguyen; Chiem Trong Hien
Journal of Engineering and Technological Sciences Vol. 51 No. 1 (2019)
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.2019.51.1.9

Abstract

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.
Performance Enhancement by Using Wet Pad in Vapor Compression Cooling System Maki H. Zaidan; Thamir K. Ibrahim; Aadel A. R. Alkumait
Journal of Engineering and Technological Sciences Vol. 51 No. 1 (2019)
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.2019.51.1.4

Abstract

Vapor compression cooling systems are widely used in hot and dry climates where the atmospheric temperature in summer reaches around 48 °C and the relative humidity can be below 20%. These cooling systems normally use environmentally friendly gases that do not harm the ozone layer. These systems work with high gas pressure, which consumes high energy and leads to a low coefficient of performance when compared to cooling systems that do not use an environmentally friendly gas. Theoretical and experimental studies have been conducted to find a suitable solution for the performance improvement of this type of cooling system. A possible solution is to lower the temperature of the air before it enters the condenser of the compression cooling system by passing it through a wet pad. The water evaporates due to the latent heat that is withdrawn from the wet pad. The air temperature is reduced to about 11 °C before it enters the condenser of the compression cooling system. This enhancement increases the cooling capacity of the vapor compression cycle by nearly 20% and increases the coefficient of performance by 15%, in addition to reducing the consumed electricity up to 15%. In conclusion, the proposed method of adding a wet pad can significantly enhance the performance of the vapor compression cooling system.
Settlement Evaluation of a Concrete Face Rock-Fill Dam (CFRD) Using a Back-Analysis Method Based on Measurement Results (A Case Study of Siah-Bisheh Dam) Mohammad Ali Abedian; Farhang Farrokhi; Reza Rasouli
Journal of Engineering and Technological Sciences Vol. 50 No. 4 (2018)
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.2018.50.4.5

Abstract

The behavior of the Siah-Bisheh concrete face rock-fill dam in Mazandaran, Iran was investigated. Numerical analyses were performed before construction to evaluate the stability and predict the deformation of the dam. The material properties were chosen based on the results of geotechnical investigations. The amounts for deformation and settlement of the concrete surface were also calculated with the numerical model. The information from a number of geotechnical instruments was collected after construction and analyzed to measure settlement at different sections of the dam. The locations of the different deformations and their values are presented with various contours. The data were analyzed and used to revise the original numerical model of the dam. Following that, the long-term stability of the dam was evaluated, using parameters that were modified based on the measurement data. A comparison of the results from the numerical analysis and the values obtained from the dam settlement measurement showed that the initial results from the numerical model were much higher than the real values. It also showed that the number of construction layers used in the modeling of the dam had a significant effect on the obtained maximum amount of deformation.
Mechanical Behavior of Dam Foundation with Vertical Sand Drain, Case Study: Sombar Dam Mohammed Shaker Mahmood; Ali Akhtarpour; Ameer Abdulridha Ajmi Alali
Journal of Engineering and Technological Sciences Vol. 51 No. 3 (2019)
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.2019.51.3.6

Abstract

Installing vertical sand drains is a traditional dam foundation consolidation solution that is economical and provides good drainage efficiency. Vertical sand drains can shorten the path of water flow inside the soil and speeds up soil consolidation. This study investigated the effect of sand drains in the foundation of the Sombar Dam in Iran on its mechanical behavior. The Sombar Dam is a project to control flooding and provide agricultural water to Gholaman city in northeastern Iran. The investigation included the mechanical behavior of the dam with vertical sand drains. The studied parameters were drain diameter, depth and spacing in addition to the vertical-to-horizontal permeability ratio (ky/kx) of the foundation soil during the time of construction of the dam using a Mohr-Coulomb (MC) model in the software application GeoStudio. The results revealed that reducing the drain spacing (increasing the number of drains) and increasing the depth and diameter of the drains led to an increase of the settlement rate (up to 90%) and the stability of the dam over a shorter period of time (24 months) compared to no drain condition. With a decrease in the ratio of vertical-to-horizontal permeability (ky/kx = 0.1) for all drain parameters there was a decrease in the value of the dam settlement rate and the safety factor.
Production of Biopolymer Polyhydroxyalkanoates (PHA) by Extreme Halophilic Marine Archaea Haloferax mediterranei in Medium with Varying Phosphorus Concentration Susiana Melanie; James B. Winterburn; Hary Devianto
Journal of Engineering and Technological Sciences Vol. 50 No. 2 (2018)
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.2017.50.2.7

Abstract

The development of plastics production from biodegradable resources such as polyhydroxyalkanoates (PHAs) is important due to the increasing demand for plastics. PHAs occur as intracellular solid materials produced by microorganisms as a result of an excess of carbon source and a limitation of nutrients. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) or PHBV, as one of the PHAs, is a combination of two homopolymers, namely poly-3-hydroxybutyrates (PHB) and poly-3-hydroxyvalerates (PHV). This study aimed to investigate the effect of the phosphorus concentration on the production of PHAs by Haloferax mediterranei. It is possible that phosphorus deficiency may affect the length of the HV chains in the copolymer structure and thus influence the copolymer properties. The experiment was done in triplicate at laboratory scale by culturing H. mediterranei in medium with phosphorus limitation using various phosphorus concentrations. During cultivation, the optical density, phosphorus concentration, pH, and dry cell weight were observed. The PHBV product was collected and analyzed using gas chromatography. The result shows that medium with a phosphorus concentration of 0.5 g/L produced higher PHAs than the other phosphorus concentrations. The accumulated PHA was 0.95 g/L with 15.6% of dry biomass and yield YPHA/S of 0.1 g/g.
A Novel Algorithm for Effective Vibration Control of Portal Frames Iraj Toloue; Mohd Shahir Liew; Indra Sati Hamonangan Harahap; Hsiu Eik Lee
Journal of Engineering and Technological Sciences Vol. 50 No. 3 (2018)
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.2018.50.3.1

Abstract

Severe vibrations such as earthquakes threaten to demolish or cause damage to built structures during their lifetime. Mitigation of such damage can be done by using control devices such as actuators. In this paper, an algorithm is proposed to analyze the nonlinear behavior of a portal frame supported by an actuator. The results were compared with those for a frame without actuator. The algorithm was developed in accordance with the Timoshenko beam element theory. ANSYS verified the results for the cases of a frame supported by a damper element and a frame without actuator. The results support the efficiency of the algorithm in reducing frame vibration and top-node displacement.
Three-dimensional DC Resistivity Modeling using Galerkin Finite Element Method Composed by Tetrahedral Elements Wahyu Srigutomo; Hairil Anwar; Eleonora Agustine; Harry Mahardika
Journal of Engineering and Technological Sciences Vol. 51 No. 4 (2019)
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.2019.51.4.5

Abstract

Successful interpretation of DC resistivity data depends on the availability of a proper forward modeling scheme. In this study, a three-dimensional DC resistivity forward modeling scheme was developed using the finite element method. The finite element equations were obtained using a weakened form of the weighted-residual method called the Galerkin method. Discretization of the modeling domain was carried out by dividing it into smaller three-dimensional blocks and subdividing each block into five tetrahedral elements. A linear interpolation function was employed and elemental linear equations were set up, followed by formation of global matrix systems of equation and incorporation of proper boundary conditions. The conjugate gradient method was applied to solve the global system of equations, which in this study was proven to be more efficient than a direct solver, contributing to a 67% time reduction. Using a Wenner array configuration, comparison with theoretical calculation of the electric potential for a homogeneous model yielded a relative error of 3.66%. To confirm the applicability of this forward modeling scheme, apparent resistivity profiles for several basic three-dimensional subsurface resistivity models were compared with the analytical profiles, yielding an acceptable level of fitting.

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