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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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Model Predictive Control for Linear Complementarity and Extended Linear Complementarity Systems Riyanto, Bambang; Hakim, Ibrahin
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 (396.209 KB) | DOI: 10.5614/itbj.eng.sci.2005.37.2.4

Abstract

 In this paper, we propose model predictive control method for linear complementarity and extended linear complementarity systems by formulating optimization along prediction horizon as mixed integer quadratic program. Such systems contain interaction between continuous dynamics and discrete event systems, and therefore, can be categorized as hybrid systems. As linear complementarity and extended linear complementarity systems finds applications in different research areas, such as impact mechanical systems, traffic control and process control, this work will contribute to the development of control design method for those areas as well, as shown by three given examples.
An LPC Excitation Model using Wavelets Langi, Armein Z.R.
Journal of Engineering and Technological Sciences Vol 40, No 2 (2008)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (191.851 KB) | DOI: 10.5614/itbj.eng.sci.2008.40.2.1

Abstract

This  paper  presents  a  new  model  of  linear  predictive  coding  (LPC) excitation  using  wavelets  for  speech  signals.   The  LPC  excitation   becomes  a linear combination of a set of self-  similar, orthonormal, band-pass signals with time localization and constant bandwidth in a logarithmic scale. Thus, the set of the  coefficients  in  the  linear  combination  represents  the  LPC  excitation.  The discrete  wavelet  transform  (DWT)  obtains  the  coefficients,  having  several asymmetrical  and  non-uniform  distribution  properties  that  are  attractive  for speech processing and compression. The properties include magnitude dependent sensitivity, scale dependent sensitivity, and limited frame length, which can be used  for  having  low  bit-rate  speech.  We  show  that  eliminating  8.97%  highest magnitude  coefficients  degrades  speech  quality  down  to  1.49dB  SNR,  while eliminating  27.51%  lowest  magnitude  coefficient  maintain  speech  quality  at  a level of 27.42 dB SNR. Furthermore eliminating 6.25% coefficients located at a scale associated with 175-630 Hz band severely degrades speech quality down to 4.20 dB SNR. Finally, our results show that optimal frame length for telephony applications is among 32, 64, or 128 samples.
Two-dimensional Model of Ciliwung River Flood in DKI Jakarta for Development of the Regional Flood Index Map Formánek, Adam; Silasari, Rasmiaditya; Kusuma, M. Syahril Badri; Kardhana, Hadi
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 (335.983 KB) | DOI: 10.5614/j.eng.technol.sci.2013.45.3.7

Abstract

The objective of this study was to present a sophisticated method of developing supporting material for flood control implementation in DKI Jakarta. High flow rates in the Ciliwung River flowing through Jakarta regularly causes extensive flooding in the rainy season. The affected area comprises highly densely populated villages. For developing an efficient early warning system in view of decreasing the vulnerability of the locations a flood index map has to be available. This study analyses the development of a flood risk map of the inundation area based on a two-dimensional modeling using FESWMS. The reference event used for the model was the most recent significant flood in 2007. The resulting solution represents flood characteristics such as inundation area, inundation depth and flow velocity. Model verification was performed by confrontation of the results with survey data. The model solution was overlaid with a street map of Jakarta. Finally, alternatives for flood mitigation measures are discussed.
Statistical Evaluation of Non-Agglomerating Coating for Granulated Natural Asphalt Samadhi, Tjokorde Walmiki; Putrawan, I Dewa Gede Arsa; Prabowo, Bambang Eko; Dwitawidi, Alinda
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 (586.67 KB) | DOI: 10.5614/itbj.eng.sci.2011.43.1.4

Abstract

Agglomeration of granulated Buton natural asphalt during storage is of major concern in its large-scale commercial application. This work develops a simple test method to evaluate the performance of agglomeration-resistant coating for granulated Buton asphalt, consisting of water-based polymeric primary coating and mineral-based secondary coating. The method uses a static load cell to measure the agglomerated granule count fraction under simulated storage conditions. A 24-1 fractional factorial experiment with two replications is employed to evaluate the effect of coating drying temperature, drying time, asphalt to secondary coating mass ratio, and secondary coating type on the agglomerated count fraction at ambient temperature and 60 oC. The test is able to measure a statistically significant increase in agglomeration resistance when the coating is applied, with an agglomerated fraction of 17.5% at 60 oC. The test identifies asphalt to secondary coating weight ratio as a significant factor, with an ANOVA p-value much lower than other effects. A decrease in this mass ratio from 5:1 to 5:2 increases the agglomeration, which is hypothesized to be attributed to the hydrated cementitious phase between granular external surfaces. More work is needed to identify the acceptable fraction of agglomerated granules.
Removal of Phosphate from Synthetic Aqueous Solution by Adsorption with Dolomite from Padalarang Nugroho, Fadjari Lucia; Mulyatna, Lili; Situmeang, Anggi Doli Wiranata
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 (774.093 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.4.5

Abstract

The presence of phosphate in wastewaters can cause eutrophication of surface  water bodies leading  to algal-blooming  in the aquatic environment and degradation  of  water  quality.  Phosphate  removal  from  wastewaters  by conventional biological treatment removes only 10-30% of the phosphate, whilst chemical  treatment  using  precipitants  such  as  calcium  or  iron  salts,  although effective,  is  expensive  and  produces  water-rich  sludge  which  must  be  further treated.  Hence,  phosphate  removal  by  adsorption  in  the  form  of  Ca -phosphate has been proposed as an alternative to the more traditional methods. This study investigated the feasibility of using dolomite–a common sedimentary rock–from Padalarang, West Java, Indonesia  as the  adsorbent  for the removal of phosphate from synthetic aqueous solution. Chemical analysis revealed that the Padalarang dolomite  contains  33.6-36.2%  CaO.  Batch  experiments  at  room  temperature indicated  that  optimum  removal  of  phosphate  was  achieved  at pH  9.  At  25°C , where  increasing  concentrations  of  phosphate  (10–100  mg/L)  increased phosphate  adsorption  (2.15-31.3  mg/g)  by  the  dolomite.  The  adsorption  of phosphate could be described by the Langmuir isotherm model, with constants Qm= 476.19 mg/g, K L= 0,00106 L/mg and equilibrium parameter (R L): 0.904  – 0.989. Phosphate adsorption by dolomite not only permits its removal but also its  potential recovery for reuse.
Linear Parameter-Varying Versus Linear Time-Invariant Reduced-Order Controller Design for Turboprop Aircraft Dynamics Widowati, Widowati; Riyanto, Bambang; Muhammad, Hari
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 (379.994 KB) | DOI: 10.5614/itbj.eng.sci.2012.44.2.5

Abstract

The  applicability  of  parameter-varying  reduced-order  controllers  to aircraft  models  is  proposed.  A  generalization  of  the  balanced  singular perturbation method of the linear time-invariant (LTI) system was used to reduce the order of  the  linear parameter-varying (LPV) system. Based on the reducedorder model, a  low-order  LPV  controller  was  designed  using  the H∞ synthesis technique.  The  performance  of  the  reduced-order  controller  was  examined  by applying  it  to  the  lateral-directional  control  of  a  20th-order  aircraft  model. Furthermore, the time responses of the closed-loop system with  several reducedorder LPV controllers and  a  reduced-order LTI controller  were  compared.  The simulation results  show that an  ,  8th -order LPV controller can maintain stability and  provide  the  same  level  of  closed-loop  system  performance  as  a  full-order LPV  controller.  This  was  not  the  case  with  the  reduced-order  LTI  controller, which  cannot  maintain  stability  and  performance  for  all  allowable  parameter trajectories.
The Effect of CaO and MgO as Expanding Additives to Improve Cement Isolation Strength under HPHT Exposure Rubiandini, Rubi; Siregar, Septoratno; Suhascaryo, Nur; Efrial, Deny
Journal of Engineering and Technological Sciences Vol 37, No 1 (2005)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (894.368 KB) | DOI: 10.5614/itbj.eng.sci.2005.37.1.3

Abstract

Cementing is one of the most important parts in oil-well drilling. Recent development in oil-well drilling technology has led to a more problematic case in cementing. High temperature cementing is one of the problems. High temperature cementing may cover steam recovery wells, geothermal wells and ultra deep wells.The use of expanding cements as an effort to improve the sealing efficacy of annulus cementing has been considered for a long time as a promising solution to the existing problems. CaO and MgO have been proposed as two of the most effective additives to create excellent expanding cement.The purpose of this study is to find the effect of adding up burnt pure CaO and MgO to the value of compressive strength and shear bond strength of API class G cement in high pressure and high temperature condition. The method that we used within this research is an evaluation of the data taken from a simulator that simulated within temperature range of 100 – 250 oC and pressure of 2000 psi.The conclusion is taken according to the results which saying that the addition of burnt pure CaO and MgO would increase the shear bond strength and the compressive strength on specific condition up to 200 oC temperature. The addition won’t be effective for the condition of 250 oC temperature. The behavior of cement strength was also influenced by the length of curing time.Further more, research on expanding cement needs to be developed and extended whether to vary its compositions, temperatures, or curing time conditions. The compatibility when mixed with other additives together with silica flour has not yet been figured out.
Crack Initiation Assessment of Wearing Course Asphalt Mixtures Using Aggregate Gradation Characteristic Haryanto, Iman; Takahashi, O
Journal of Engineering and Technological Sciences Vol 39, No 1 (2007)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (172.703 KB) | DOI: 10.5614/itbj.eng.sci.2007.39.1.3

Abstract

At normal service temperatures, wearing course asphalt mixtures may have ductile cracking. Aggregate gradation characteristic is important to avoid the premature cracking. The present study discusses a relationship between the characteristic of aggregate gradation and crack resistance of wearing course mixtures. Asphalt mixture specimens were prepared using different types of aggregate gradation. The Bailey method was employed in order to recognize the characteristic of aggregate gradations. Notched semi circular bending test was conducted to obtain the critical J integral (Jc). The coarse aggregate (CA) ratio and the fine graded fine aggregate coarse (FG FAc) ratio defined by the Bailey method were introduced to recognize the effect of aggregate gradation type on Jc. The result was decreasing the Jc value with increasing the CA ratio and FG FAc ratio. Satisfying the current Bailey criterion on the CA ratio for stone mastic asphalt mixtures and setting FG FAc of fine graded HMA mixtures near 0.4 seem useful in order to obtain HMA mixtures with a high Jc. The present study also discusses spherical aggregates assembly models as an aid to illustrate development of the aggregates interlocking, which influences to the cracking.
The Influence of Cross-Sectional Shape and Orientation of Micropillar Surface on Microdroplet Formation by a Dewetting Process Dwiyantoro, Bambang Arip; Chau, Shiu-Wu
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 (433.184 KB) | DOI: 10.5614/j.eng.technol.sci.2013.45.2.5

Abstract

In this study the dewetting process on micropillars of three different cross-sectional shapes, i.e. circular, square and triangular, was numerically investigated. The influence of the orientation of the triangular and square micropillars on the dewetting behavior was also studied. The numerical simulations showed that the cross-sectional shapes of the micropillars and their orientation play an important role in determining the flow pattern of the dewetting process, especially the evolution and movement of the meniscus across the micropillar before a microdroplet is formed. The diameter of the microdroplets is mainly determined by the capillary effect, viscous drag and fluid inertia contributed by the peeling rate and the thickness of the water layer above the micropillar. The numerical results also indicate that the hydraulic diameter of the micropillars (Dp) is one of the parameters governing the size of the microdroplets formed on the top surface of the micropillars after the dewetting process, while the microdroplet diameter is almost insensitive to the cross-sectional shape and orientation of the micropillars. The dimensionless diameter of the microdroplets (d) can then be expressed as a function of a dimensionless group, i.e. the Ohnesorge number (Oh), the capillary number (Ca), the dimensionless liquid thickness (H), and the contact angle (q).
Closed Form Solution of Synchronous Machine Short Circuit Transients Sianipar, Gibson H.M.
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 (373.645 KB) | DOI: 10.5614/itbj.eng.sci.2010.42.1.7

Abstract

This  paper  presents  the  closed  form  solution   of  the  synchronous machine  transients undergoing short circuit. That analytic formulation has been derived  based  on  linearity  and  balanced  conditions  of  the  fault.  Even  though restrictive, the proposed method will serve somehow or other as a new resource for  EMTP  productivity.  Indisputably  superior, the  closed-form  formulation has some  features  inimitable  by  discretization  such  as  continuity,  accuracy  and absolute numerical stability. Moreover, it enables us to calculate states at one specific  instant  independent  of  previous  states  or  a  snapshot,  which  any discretization methods cannot do.

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