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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 6 Documents
 1 
Search results for , issue "Vol. 44 No. 2 (2012)" : 6 Documents clear
Optimization of Laccase Production using White Rot Fungi and Agricultural Wastes in Solid-State Fermentation Hendro Risdianto; Elis Sofianti; Sri Harjati Suhardi; Tjandra Setiadi
Journal of Engineering and Technological Sciences Vol. 44 No. 2 (2012)
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.2012.44.2.1

Abstract

Abstract. Laccase has been produced in a solid-state fermentation (SSF) process using white rot fungi and various  lignocellulose-based substrates.  The white  rot fungi  used  were  Marasmius  sp.,  Trametes  hirsuta,  Trametes  versicolor  and Phanerochaete  crysosporium.  The  solid  substrates  employed  in  this  research were collected from  agricultural  waste, specifically  empty fruit bunches (EFB), rice  straw,  corncobs  and  rice  husks.  The  objective  of  this  research  was  to determine  the  most  promising  fungus,  the  best  solid  substrate  and  the  optimal conditions for the production of laccase.  The  results showed that  Marasmius  sp. on all solid substrates displayed  a  higher laccase activity than that of  any  other strain  of  white  rot  fungi.  Marasmius  sp.  and  a  solid  substrate  of  rice  straw demonstrated  the  highest  laccase  activity  of  1116.11  U/L  on  day  10.  Three significant  factors,  i.e.  pH,  temperature  and  yeast  extract  concentration,  were studied by  the  response surface method on laccase production using  Marasmius sp.  and rice straw. The optimized conditions were  a  pH, temperature and yeast extract concentration of 4.9, 31ºC and 0.36 g/L,  respectively.  The fermentation of  Marasmius  sp.  in  SSF  on agricultural  waste  shows  a  great  potential  for  the production of laccase.
Optimization of Vertical Well Placement for Oil Field Development Based on Basic Reservoir Rock Properties using a Genetic Algorithm Tutuka Ariadji; Pudjo Sukarno; Kuntjoro Adji Sidarto; Edy Soewono; Lala Septem Riza; Kenny David
Journal of Engineering and Technological Sciences Vol. 44 No. 2 (2012)
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.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.
A Buffer Stock Model to Ensure Price Stabilization and Availability of Seasonal Staple Foods under Free Trade Considerations Wahyudi Sutopo; Senator Nur Bahagia; Andi Cakravastia; T.M.A. Arisamadhi
Journal of Engineering and Technological Sciences Vol. 44 No. 2 (2012)
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.2012.44.2.3

Abstract

Price  volatility  and  scarcity  have  become  a  great  problem  in  the distribution  system  of  seasonal  staple  foods  produced  by  the  agricultural industry.  There  is  a  salient  supply  disparity  during  the  harvest  and  planting seasons.  This  condition  could  cause  disadvantages  to  stakeholders  such  as producers,  wholesalers,  consumers,  and  government.  This  paper  proposes  a buffer  stock  model  under  free-trade  considerations  to  substitute  quantitative restrictions  and  tariffs  with  an  indirect  market  intervention   instrument.  This instrument  was  developed  using  a  buffer  stock  scheme  in  accordance  with  a  warehouse receipt system  (WRS) and  a  collateral management system.  A  public service  institution  for  staple  food  buffer  stock   (BLUPP)  is  proposed  as  the wholesaler's competitor,  with  as main responsibility   to ensure price stabilization and availability of staple food. Multi-criteria decision-making is formulated as a single  objective  mixed  integer  non-linear  programming  (MINLP)  model.  The results  shows  that  the  proposed  model  can  be  applied  to  solve  the  distribution problem  and  can  give  more  promising  outcomes  than  its  counterpart,  direct market intervention.
A New Obstacle Avoidance Method for Service Robots in Indoor Environments Widodo Budiharto; Ari Santoso; Djoko Purwanto; Achmad Jazidie
Journal of Engineering and Technological Sciences Vol. 44 No. 2 (2012)
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.2012.44.2.4

Abstract

The objective of this paper is to propose an obstacle avoidance method for  service  robots  in  indoor  environments  using  vision  and  ultrasonic  sensors. For  this research,  the  service  robot  was  programmed  to  deliver  a  drinking  cup from a specified starting point to the recognized customer. We have developed three main modules: one for face recognition, one for obstacle detection, and one for avoidance maneuvering. The obstacle avoidance system is based on an edg edetection  method  using  information  from  the  landmark  and  planned-path generation. Speed, direction and distance of the moving obstacle are measured using  vision  and  distance  sensors  in  order  for  the robot  to  make  an avoidance maneuver. Algorithms for obstacle avoidance are proposed and a new geometric model is introduced for making good avoidance maneuvers. The main aim of this research is to provide a complete mechanism for obstacle avoidance by vision based service robots, where common obstacle avoidance methods, such as PVM, do  not  provide  such  a  feature.  We  present the results  of  an  experiment  with  a service  robot  in  which  the  proposed  method  was  implemented,  after  which  its performance is evaluated.
Linear Parameter-Varying Versus Linear Time-Invariant Reduced-Order Controller Design for Turboprop Aircraft Dynamics Widowati Widowati; Bambang Riyanto; Hari Muhammad
Journal of Engineering and Technological Sciences Vol. 44 No. 2 (2012)
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.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.
Estimation of Slip Distribution of the 2007 Bengkulu Earthquake from GPS Observations Using the LeastSquares Inversion Method Moehammad Awaluddin; Irwan Meilano; Sri Widiyantoro
Journal of Engineering and Technological Sciences Vol. 44 No. 2 (2012)
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.2012.44.2.6

Abstract

Continuous  Global  Positioning  System  (GPS)  observations  showed significant  crustal  displacements  as  a  result  of  the  Bengkulu  earthquake occurring on September 12, 2007. A maximum horizontal displacement of 2.11 m was observed at PRKB station, while the vertical component at BSAT station was lifted up with a maximum of 0.73 m, and the vertical component at LAIS station had subsided  "“0.97 m. Adding more constraints on the inversion for the Bengkulu earthquake slip distribution inferred from GPS observations can help solve  the  underdetermined  least-squares  inversion.  Checkerboard  tests  were performed  to  help  conduct  the  weighting  for  constraining  the  inversion.  The inversion calculation yielded an optimal value for the slip distribution by giving the smoothing constraint a weight of 0.001 and the slip constraint a weight of = 0 at the edge of the earthquake rupture area. The maximum co-seismic slip of the optimal inversion calculation was 5.12 m at the lower area of PRKB station and BSAT station. The seismic moment calculated from the optimal slip distribution was 7.14 x 1021 Nm, which is equivalent to a magnitude of 8.5.

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