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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
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Miscibility Development Computation in Enhanced Oil Recovery by Flare Gas Flooding Samadhi, Tjokorde Walmiki; Siagian, Utjok W.R.; Budiono, Angga P.
Journal of Engineering and Technological Sciences Vol 44, No 3 (2012)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (251.227 KB) | DOI: 10.5614/itbj.eng.sci.2012.44.3.5

Abstract

The use of flare gas as injection gas in miscible gas flooding enhanced oil  recovery  (MGF-EOR)  presents  a  potential  synergy  between  oil  production improvement  and  greenhouse  gases  emission  mitigation.  This  work  is  a preliminary evaluation of the feasibility of miscible flare gas injection based on phase behavior computations of  a model oil (43% n-C5H12 : 57% n-C16H34) and a model flare gas (91% CH4  : 9% C2H6). The computations employed the multiple mixing-cell  model  with  Peng-Robinson  and  PC-SAFT  equations  of  state,  and compared the minimum miscibility pressure (MMP) value in the cases of flare gas  injection  and  CO2  injection.  For  CO2  injection,  both  equations  of  state produced  MMP  values  close  to  the  measured  value  of  10.55  MPa.  Flare  gas injection MMP values were predicted to be 3.6-4.5 times those of CO2  injection. This very high MMP implies high gas compression costs, and may compromise the  integrity  of  the  reservoir.  Subsequent  studies  shall  explore  the  gas -oil miscibility  behavior  of  mixtures  of  flare  gas  with  intermediate  hydrocarbon gases and  CO2,  in  order to  identify  a suitable approach for rendering flare  gas feasible as an injection gas in MGF-EOR.
The Use of GPR in Delineating an Iron Sand Boundary and the Determination of Its Electromagnetic Wave Velocity: A Case Study in Jepara, Central Java Bijaksana, S.; Rusyanti, I.; T. Taib, M. I.; Pasasa, L. A.; Andreas, A. S.
Journal of Engineering and Technological Sciences Vol 37, No 2 (2005)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1138.177 KB) | DOI: 10.5614/itbj.eng.sci.2005.37.2.1

Abstract

 Exploring the vertical extent of iron sand deposit is challenging as conventional geophysical methods (electrical resistivity, geomagnetic, and seismic refraction) are inappropriate and unsuccessful in delineating the iron sand deposit from the bedrock. Ground-penetrating radar (GPR) offers a solution to the above problem as radar is not affected negatively by the physical properties of iron sand. In the year 2003, a RAMAC’s GPR survey was carried out in the coast of Bayuran in the Regency of Jepara, Central Java to map the distribution of sub-bottom iron sand. The sand is highly magnetic. The survey used 100 MHz antennas. The survey is also complimented by a novel method in determining the electromagnetic (EM) wave velocity of iron sand. Combination of reflection profiling and CMP sounding was deployed. Results of CMP sounding were processed using CMP-semblance analysis that produces the RMS velocity in velocity-time spectra. The RMS velocity is then converted to interval velocity using Dix’s formula and is found to be about 135 mm/ns. Meanwhile, combination of magnetic susceptibility, relative permittivity, and dissipation factors produces radiowaves velocity of iron sand as a function of frequency. The velocities of radiowaves estimated from laboratory match that estimated from CMP analysis.
Application of Wavelet LPC Excitation Model for Speech Compression Langi, Armein Z.R.
Journal of Engineering and Technological Sciences Vol 40, No 1 (2008)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (233.045 KB) | DOI: 10.5614/itbj.eng.sci.2008.40.1.1

Abstract

This paper presents an application of linear predictive coding (LPC) excitation wavelet models for low bit- rate, high-quality speech compression. The compression scheme exploits the model properties, especially magnitude dependent sensitivity, scale dependent sensitivity, and limited frame length. We use the wavelet model in an open-loop dither based codebook scheme. With t his approach, the compression yields a signal-to-noise ratio of at least 11 dB at rates of 5 kbit/s and.
Performance Evaluation of Steel Fibres in Rice Husk Ash Substituted Concretes Sivakumar, A.; Sounthararajan, V.M.
Journal of Engineering and Technological Sciences Vol 45, No 3 (2013)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2787.861 KB) | DOI: 10.5614/j.eng.technol.sci.2013.45.3.4

Abstract

The potential use of supplementary cementitious materials in plain cement concrete for improving concrete properties has been a growing concern in recent years. In addition, the effective strengthening of the matrix by fibre reinforcements to avoid brittle failure is another requirement for plain concrete. This provided the motivation for exploring the benefits of rice husk ash (RHA) as a cement replacement material and the addition of steel fibres for reducing brittleness in concrete. The rice husk ash used in this study was the residue of burnt raw rice husk sintered in a muffle furnace at 800 °C. The fine particle size of the rice husk ash provided an early pozzolanic reaction upon cement hydration and thus resulted in high cementing efficiency. This paper reports a systematic evaluation of the mechanical properties of rice husk ash substituted concrete mixtures containing RHA as a partial cement substitute at replacement levels of 10% and 20% by weight of cement, with different dosages of steel fibres. Our experimental results demonstrated that 10% RHA substitution led to improved compressive properties compared to plain concrete. The highest increase of split tensile and flexural strength was reported in the case of RHA substituted concrete with steel fibre added.
The Influence of Pt Atomic Ratio in the Activity PtNi/C Nanocatalysts for the PEMFC Rusnaeni, Nenen; Purwanto W., Widodo; Nasikin, Mohammad; Hendrajaya, Lilik
Journal of Engineering and Technological Sciences Vol 43, No 1 (2011)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (502.344 KB) | DOI: 10.5614/itbj.eng.sci.2011.43.1.1

Abstract

Pt-Ni/C alloy nanocatalysts synthesized by polyol method with different atomic ratio are investigated to enhance activity of the oxygen reduction reaction (ORR) for fuel cell applications. Prepared catalysts are characterized by various techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM-EDX), and cyclic voltammetry (CV). XRD analysis shows that all prepared catalysts with different atomic ratio exhibit face centered cubic and have smaller lattice parameters than pure Pt catalyst. The mean particle size of the catalysts are between 4.3 to 6.3 nm. Cyclic voltammograms with scan rate 5 mV s-1 at 25oC obtain range the electrochemical active surface (EAS) between 40 to 164 cm2/mgPt, mass activity (MA) and specific activity (SA) of nanocatalysts PtNi/C in the potential range 900 mV versus RHE between 3.61 to 8.42 mA/mgPt, and 0.05 to 0.09.
Seismic Performance and Application of Sandwiched Buckling-Restrained Braces and Dual-Core Self-Centering Braces Chou, Chung-Che; Chung, Ping-Ting; Chen, Ying-Chuan
Journal of Engineering and Technological Sciences Vol 46, No 4 (2014)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1255.561 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.4.1

Abstract

This paper first presents cyclic test results  and  the  application  of  the proposed sandwiched buckling-restrained brace (BRB).  The proposed BRB can be easily  disassembled  in the field.  This  provides  an opportunity for inspection of  the  core  after  a  large  earthquake.  The  mechanics  and  cyclic  behavior  of  a novel  steel  dual-core  self-centering  brace  (SCB)  are  then  proposed  and introduced, followed by  the  testing of  a  dual-core SCB  in order  to evaluate  its cyclic  performance.  Both  braces  achieve  an  excellent  target  lateral  drift performance  of  up to 2.5%,  thus  satisfying  the seismic requirement by  the  AISC Seismic Provisions 2010.
Optimization of Vertical Well Placement for Oil Field Development Based on Basic Reservoir Rock Properties using a Genetic Algorithm Ariadji, Tutuka; Sukarno, Pudjo; Sidarto, Kuntjoro Adji; Soewono, Edy; Riza, Lala Septem; David, Kenny
Journal of Engineering and Technological Sciences Vol 44, No 2 (2012)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (552.057 KB) | DOI: 10.5614/itbj.eng.sci.2012.44.2.2

Abstract

Comparing the quality of basic reservoir rock properties is a common practice  to  locate  new  infill  or  development  wells  for  optimizing  oil  field development using reservoir simulation. The conventional technique employs a manual  trial-and-error  process  to  find  new  well  locations,  which  proves  to  be time-consuming, especially for large fields. Concerning this practical matter, an alternative in the form of a robust technique is introduced in order to reduce time and  effort  in  finding  new  well  locations  capable  of  producing  the  highest  oil recovery. The objective of this research was to apply a genetic algorithm (GA) for determining well locations using reservoir simulation, in order to avoid the conventional  manual  trial-and-error  method.  This  GA  involved  the  basic  rock properties,  i.e.  porosity,  permeability,  and  oil  saturation,  of  each  grid  block obtained from a reservoir simulation model, to which a newly generated fitness function was applied, formulated by translating common engineering  practice in reservoir  simulation  into  a  mathematical  equation  and  then  into  a  computer program. The maximum fitness value indicates the best grid location for a new well. In order to validate the proposed GA method and evaluate the performance of the program, two fields with different production profile characteristics were used, fields X and Y. The proposed method proved to be a robust and accurate method to find the best new well locations for oil field development. The key to the success of the proposed  GA method lies in the formulation of the objective functions.
Comparison of the Stochastic Models for Double-Differenced GPS Measurements Darmawan, Dudy; Kimata, Fumiaki
Journal of Engineering and Technological Sciences Vol 36, No 2 (2004)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (496.892 KB) | DOI: 10.5614/10.5614/itbj.eng.sci.2004.36.2.1

Abstract

Double-differenced GPS carrier phase measurements are commonly used in GPS precise positioning applications and processed with algorithms based on the least-squares (LS) principle. In order to apply the LS principle, one needs to define properly both the functional and stochastic models. Whilst the functional model for precise GPS positioning is sufficiently well known, realistic stochastic modeling is still a difficult task to accomplish in practice. Incorrect stochastic models for double-differenced GPS measurements will lead to unreliable estimates for ambiguity resolution and, eventually, it will bias positioning results. The common assumption when we construct the stochastic model is that all raw GPS measurements are independent and have the same variances. In fact, this is not realistic, since due to varying noise levels measurements obtained from different GPS satellites cannot have the same accuracy. A realistic stochastic modeling should be able to capture the ordinary noises in the observables.In order to specify a realistic stochastic model for precise relative GPS positioning applications, in this paper the performance of three stochastic models namely the commonly used model or the standard model, the outer product of residual data vector model and Minimum Norm Quadratic Unbiased Estimation (MINQUE) are examined and effects of each the proposed model on statistic for ambiguity search and positioning accuracy are compared. The results indicate that the MINQUE model tends to perform better than the other models. Using the MINQUE model, the reliability of the ambiguity resolution and the statistics of the baseline components can be improved. It may suggest that the MINQUE model, which is based on modern statistical theory, is capable of capturing the ordinary noises.
Velocity versus Offset (VVO) Estimation Using Local Event Correlation and Its Application in Seismic Processing & Analysis Supriyono, S.; Priyono, Awali; Triyoso, Wahyu; Mardiyan, Hilman
Journal of Engineering and Technological Sciences Vol 45, No 2 (2013)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (559.019 KB) | DOI: 10.5614/j.eng.technol.sci.2013.45.2.2

Abstract

Conventional velocity analysis is usually done in a relatively spare grid, for instance every half kilometers, during the processing of seismic data. It is very laborious work and very subjective. To deliver an accurate velocity picking, processing geophysicists must have a good understanding of geological background of area being analyzed and experiences. Velocity errors often occur during picking. Proper quality control and checking are a must. A good and reliable velocity field is very important in seismic processing for achieving high-quality seismic images as well as for delivering an accurate depth conversion. The new method presented here, was developed to correct velocity errors automatically by means of residual velocity correction, and to produce an offset-dependent RMS velocity field at the same time. The method is data driven, based on the normal move out equation (NMO) and measuring the local even correlation between adjacent traces. The stacking velocity is derived simply by averaging the velocity field. The proposed method was tested on synthetic and real data examples with good result. The velocity field has certain characteristics related to hydrocarbon presence. Supriyono (2011 and 2012) developed a new DHI method using velocity gradient attributes by cross-plotting the velocity versus offset (VVO). The velocity gradient exhibits high anomalous values in the presence of gas.
Analysis and Minimization of Output Current Ripple of Multiphase Carrier-Based PWM Inverters Dahono, Pekik Argo
Journal of Engineering and Technological Sciences Vol 42, No 1 (2010)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (274.069 KB) | DOI: 10.5614/itbj.eng.sci.2010.42.1.4

Abstract

Analysis  and  minimization  of  output  current  ripple  of  multiphase carrier-based PWM  inverters are presented in this paper.  Analytical expression of rms value of output current ripple of multiphase PWM inverters as a function of the reference signal is first derived. Based on this expression, it is shown that a pure sinusoidal signal is the optimum reference signal that results in minimum output  current  ripple.  Different  to  three-phase  PWM  inverters,  injection  of harmonics  into  the  sinusoidal  reference  signal  is  neither  necessary  nor  useful. The  rms  values  of  output  current  ripple  of  5-,  7-,  and  9-phase  PWM  inverters under various reference signals are compared. Experimental results are included to show the validity of the analysis method.

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