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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)
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Articles 7 Documents
 1 
Search results for , issue "Vol. 41 No. 2 (2009)" : 7 Documents clear
Geometry Effect Investigation on a Conical Chamber with Porous Media Boundary Condition Using Computational Fluid Dynamic (CFD) Technique Yazid Bindar
Journal of Engineering and Technological Sciences Vol. 41 No. 2 (2009)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.eng.sci.2009.41.2.1

Abstract

The present study is an attempt to introduce  a  method for optimizing the  geometry  of  a  unit  process.  The  comprehensive  unit  process  performances are generated by a  CFD engine. The CFD engine can simulate the unit process performances  at  whatever  conditions.  Both  design  geometry  and  operating variables were used on the CFD simulation. The burden on a simplified process was taken out from CFD simulation. A complex geometry of a unit process is represented  by  a  secondary  reformer.  A  secondary  reformer  has  a  conical chamber  as a space to undergo  a  combustion reaction before entering  a  catalyst bed. This complexity is added by the boundary  on a  porous solid surface as the top surface of  the catalyst bed. The  conical  angle affects the flow pattern inside the  conical chamber  having a porous solid surface as its  base. The  conical  angle above  65° results  the  disappearing  of  the recirculation  flow.  The  inlet  distance from  the  porous  solid  surface  also  can  exhibit  different  characteristics  of recirculation  flow.  The  closer  the  distance  to  the  porous  solid  surface,  the stronger the recirculation is. The inlet velocity values have no significant effect on  the  flow  pattern.  The  introduction  of  a  solid  volume  inside  the  geometry creates distortion in the flow pattern. In the application, the inserted solid volume is equivalent to a burner. It means that the use of the burner inherently produces some problems of the flow distribution.
Vortex-induced Vibration of a Flexible Free-hanging Circular Cantilever R. W. Prastianto; K. Otsuka; Y. Ikeda
Journal of Engineering and Technological Sciences Vol. 41 No. 2 (2009)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.eng.sci.2009.41.2.2

Abstract

The  behavior  of  a  free-hanging  riser  of  floating  offshore  structures would be different from  a  typical at-sea-floor-terminated riser type of oil or gas platforms.  For the design purpose, the present study  was intended to incorporate some  important  factors  of the riser conditions  (i.e.  bidirectional vibration,  freeend condition, and spanwise variation of response amplitude) for investigating its dynamics  characteristics.  An  experimental  investigation  on  time-dependent motion  of  a  flexible free-hanging circular cantilever  subjected to uniform crossflows has been carried out.  The  free-end condition  cantilever has  a  34.4  aspect ratio  and  a  low  mass ratio  of  about  1.24. The  cylinder  freely  oscillates in both inline  and  transverse  to  the  flow.  Reynolds  number  varied  from  10,800  to 37,800.  The "jump  phenomenon"  was found in the inline motion  of the cylinder that agrees well with an existing  comparable work.  At high flow velocities, the 3rd  higher  harmonic  frequencies  of  the  cylinder  transverse  response  became predominant that produce quite different motion  characteristics  compared to the other  existing  comparable  works  with  2-dimensional  bottom-end  condition. Generally, the results suggested that the flexible free-hanging cantilever generate different  vortex  wake  mode  than  either,  a  uniform  (a  short-rigid  flexiblymounted cylinder) or a linear amplitude variation along the span  case (a  pivoted cylinder)
A Field Observation on Lightning Performance Improvement of Overhead Distribution Lines Reynaldo Zoro; Ryan Mefiardhi; Syarif Hidayat; Redy Mardiana
Journal of Engineering and Technological Sciences Vol. 41 No. 2 (2009)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.eng.sci.2009.41.2.3

Abstract

Two feeders of 20 kV overhead distribution lines which are located in a high lightning density area are chosen to be observed as a field study due to their  good  lightning  performance  after  improvement  of  lightning  protection system.  These  two  feeders  used  the  new  overhead  ground  wire  and  new  line arrester  equipped  with  lightning  counter  on  the  main  lines.  The  significant reduced  of  lines  outages  are  reported.  Study  was  carried  out  to  observe  these improvements  by  comparing  to  the  other  two  feeders  line  which  are  not improved and not equipped yet with the ground wire and line arrester. These two feeders  located  in  the  nearby  area.  Two  cameras  were  installed  to  record  the trajectory of the lightning strikes  on the improved lines. Lightning peak currents are  measured  using  magnetic  tape  measurement  system  installed  on  the grounding  lead  of  lightning  arrester.  Lightning  overvoltage  calculations  are carried out by using several scenarios based on observation results and historical lightning data derived from lightning detection network. Lightning overvoltages caused by indirect or direct strikes are analyzed to get the lightning performance of  the  lines.  The  best  scenario  was  chosen  and  performance  of  the  lines  were improved significantly by installing overhead ground wire and improvement of lightning arrester installation. 
Determining Conjugate Points of An Aerial Photograph Stereopairs Using Separate Channel Mean Value Technique Andri Hernandi; D. Muhally Hakim; Irawan Seomarto; Agung Budiharto; Emalia Emalia
Journal of Engineering and Technological Sciences Vol. 41 No. 2 (2009)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.eng.sci.2009.41.2.4

Abstract

In  the  development  of  digital  photogrammetric  system,  automatic image matching process play an important role. The automatic image matching is  used  in  finding  the  conjugate  points  of  an  aerial  photograph  stereopair automatically.  This  matching  technique  gives  quite  significant  contribution especially  in  the  development  of  3D  photogrammetry  in  an  attempt  to  get  the exact and precise topographic information during the stereo restitution. There are two image matching methods that have been so far developed, i.e. the area based system  for  gray  level  environment  and  the  feature  based  system  for  natural feature  environment.  This  research  is  trying  to  implement  the  area  based matching  with  normalized  cross  correlation  technique  to  get  the  correlation coefficient between the spectral value of the left image and its pair on the right. Based  on  the  previous  researches,  the  use  of  color  image  could  increase  the quality  of  matching.  One  of  the  color  image  matching  technique  is  known  as Separate Channel Mean Value. In order to be able to see the performance of the technique, a number of sampling areas with various different characteristics have been  chosen,  i.e.  the  heterogeneous,  homogeneous,  texture,  shadow,   and contrast. The  result  shows  the  highest  similarity  measure  is  obtained  on  heterogeneous sample area at size of all reference and search image, i.e. (11 pixels x 11 pixels) and   (23  pixels  x  23  pixels).  In  these  area  the  correlation  coefficient  reached more than 0.7 and the highest percentage of similarity measure is obtained. The average of total similarity  measure of conjugate images in the sampling image area  only  reach  about  41.43  %  of  success.  Therefore,  this  technique  has  a weakness and some treatment to overcome the problems is still needed.
Estimation of Bank Erosion Due to Reservoir Operation in Cascade (Case Study: Citarum Cascade Reservoir) Sri Legowo; Iwan K. Hadihardaja; Azmeri Azmeri
Journal of Engineering and Technological Sciences Vol. 41 No. 2 (2009)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.eng.sci.2009.41.2.5

Abstract

Sedimentation  is  such  a  crucial  issue  to  be  noted  once  the accumulated  sediment  begins  to  fill  the  reservoir  dead  storage,  this  will  then influence the long-term reservoir operation. The sediment accumulated requires a serious attention for it may influence the storage capacity and other reservoir management  of  activities.  The  continuous  inflow  of  sediment  to  the  reservoir will decrease the capacity of reservoir storage, the reservoir value in use, and the useful  age  of  reservoir.  Because  of  that,  the  rate  of  the  sediment  needs  to  be delayed as possible. In this research, the delay of the sediment rate is considered based on the rate of flow of landslide of the reservoir slope. The rate of flow of the sliding slope can be minimized by way of each reservoir autonomous efforts. This  effort  can  be  performed  through;  the  regulation  of  fluctuating  rate  of reservoir surface current that does not cause suddenly  drawdown  and upraising as well. The research model is compiled using the searching technique of Non Linear Programming (NLP). The  rate  of  bank  erosion  for  the  reservoir  variates  from  0.0009  to  0.0048 MCM/year, which is no sigrificant value to threaten the life time of reservoir.Mean  while  the   rate  of  watershed  sediment  has  a  significant  value,  i.e:  3,02  MCM/year  for  Saguling  that  causes  to  fullfill  the  storage  capacity  in  40  next years (from years 2008). 
A Substractive Clustering Based Fuzzy Hybrid Reference Control Design for Transient Response Improvement of PID Controller Endra Joelianto; Parlindungan H. Sitanggang
Journal of Engineering and Technological Sciences Vol. 41 No. 2 (2009)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.eng.sci.2009.41.2.6

Abstract

The  well  known  PID  controller  has  inherent  limitations  in  fulfilling simultaneously the conflicting control design objectives.  Parameters of the tuned PID  controller  should  trade  off  the  requirement  of  tracking  set-point performances,  disturbance  rejection  and  stability  robustness.  Combination  of hybrid  reference  control  (HRC)  with  PID  controller  results  in  the  transient response  performances can be independently achieved without deteriorating the disturbance  rejection  properties  and  the  stability  robustness  requirement.  This paper proposes a fuzzy based HRC where the membership functions of the fuzzy logic  system  are  obtained  by  using  a  substractive  clustering  technique.  The proposed  method  guarantees  the  transient  response  performances  satisfaction while preserving the stability robustness of the closed loop system controlled by the  PID  controller  with  effective  and  systematic  procedures  in  designing  the fuzzy hybrid reference control system.
Improved Predictive Power Control Algorithms to Increase CDMA System Capacity A. Kurniawan; Iskandar Iskandar; Sayid Machdar
Journal of Engineering and Technological Sciences Vol. 41 No. 2 (2009)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.eng.sci.2009.41.2.7

Abstract

In  this  paper  capacity  of  CDMA  system  is  evaluated  using  an improved  algorithm  of  channel  prediction-based  power  control  in  Rayleigh fading  channel environments. One  of the most serious problems which degrades the performance of power control algorithm is the effect of feedback delay. To overcome the effect of feedback delay, power control algorithm relies on channel prediction techniques, which utilize the correlation property of the past  channel measurements.  In  CDMA  power  control,  however,  the  correlation  property  of channel  measurements  is destroyed  because the  transmit power  is continuously updated  for  each  power  control  interval.  In  order  to  restore  the  correlation property of the channel,  the past  channel measurements  are compensated  for by the  same  factors  that  were  given  by  power  updating  for   each  power  control interval. The prediction algorithm in this paper is proposed using the least mean square  (LMS) technique. The result shows that the capacity of CDMA systems increase  significantly  when  the  improved  predictive  algorithm  is  used. Numerical evaluation shows that CDMA capacity increases by more than 40 % for fixed step algorithm and more than 50 % for variable step algorithm when the proposed algorithm is employed. 

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