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Journal of Engineering and Technological Sciences
ISSN : 23375779     EISSN : 23385502     DOI : -
Core Subject : 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 10 Documents
Search results for , issue " Vol 46, No 4 (2014)" : 10 Documents clear
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.
Depositional Environment of the Sangkarewang Oil Shale, Ombilin Basin, Indonesia Anggayana, Komang; Widayat, Agus Haris; Widodo, Sri
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 (1035.745 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.4.6

Abstract

Five samples from 56 m long drill core of lacustrine Sangkarewang oil shale have been studied by means of petrography and organic geochemistry to investigate the organic matter composition and depositional environments of the shale. The organic matter consists of abundant lamalginite (30%, v/v) and very limited amount of vitrinite, suggesting aquatic depositional environments with minor terrestrial influence. Organic geochemical analysis exhibits the dominance of pristane, phytane, and generally n-alkanes compounds. These compounds might originate mostly from aquatic photosynthetic organisms. The oil shale was likely deposited in anoxic lake environments, suggested by the presence of framboidal pyrite (6%, v/v) and preserved organic matter with total organic carbon (TOC) about 4.9%. The pristane/phytane ratio is relatively high about 3.9 and thought as source sensitive rather than redox sensitive. Hopanoid and aryl isoprenoid compounds are present in minor amounts. The latter compounds are interpreted to be derived from green sulfur bacteria dwelling in anoxic and the presence of H2S in bottom water.
Identifying Contractors’ Planned Quality Costs in Indonesian Construction Projects Marzuki, Puti F.; Wisridani, M.
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 (714.028 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.4.2

Abstract

In  a very competitive construction industry, quality costs have to be measured  to  be  able  to  identify  potential  quality  problem  areas  and  to  focus attention  on  work  output  improvement  opportunities.  The  awareness  of contractors on the importance of quality costs could be reflected in the extent of their  quality  costs  planning.  This  paper  presents  an  identification  of  planned quality  costs  in  three  construction  projects  executed  by  two  large  Indonesian contractors,  a  state-owned  company  and  a  private  company  in  Jakarta.  The objective is to enable the contractors to elaborate their quality costs planning and thereby improve their work output based on the findi ngs. Quality  costs  are  first grouped into  three  categories: prevention, appraisal,  and  failure  costs.  Based on the  works  of  previous  researchers,  a  list  of  quality  management  activities  that should be covered in each quality costs category is then created. The contractors’ planned quality costs data  for each category are  identified and  collected through interviews  and  questionnaire  surveys  that   refer  to  the  list.  Quality  costs  are expressed  as  a  percentage  of  contract  value.  It  is  revealed  that  although  large contractors  already  have  certain  knowledge  on  quality  costs  in  construction projects,  these costs are  not planned in a structured way  through an analysis of systematic  quality  costs  records.  Through  cost  categorization  it  is  also  shown that higher prevention and appraisal costs lead to lower failure costs.  It is then concluded  that  a  lot  of  work  is  still  to  be  done  by  the  contractors  to  set  up  a quality  costs  recording  system  which  can  serve  as  a  basis  for  their  quality improvement planning.
Core Spreading Vortex Method for Simulating 3D Flows Around Bluff Bodies Zuhal, Lavi Rizki; Dung, Duong V.; Sepnov, Alex J.; Muhammad, Hari
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 (1641.249 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.4.7

Abstract

This paper presents the development of core spreading vortex element method, which is a mesh-free method, for simulating 3D viscous flow over bluff bodies. The developed method simulates external flow around complex geometry by tracking local velocities and vorticities of particles introduced within the fluid domain. The viscous effect is modeled using core spreading method coupled with the splitting spatial adaption scheme, and a smoothing interpolation scheme for overlapping issue and population control, respectively. The particle’s velocity is calculated using Biot-Savart formulation. To accelerate computation, Fast Multipole Method (FMM) is employed. The solver is validated, for both unbounded and bounded flows at low Reynolds numbers, using a number of benchmark problems. For unbounded case, simulation of the collision of two vortex rings was performed. To test the performance of the method in simulating bounded flow problem, simulation of flow around a sphere was carried out. The results are found to be in good agreement with those reported in literatures and also simulations using other diffusion model.
Adjustment of Daily Activities: the Influence of Smartphone Adoption on the Travel Pattern of Mobile Professionals in the Greater Jakarta Area Christin, Gloriani Novita; Tamin, Ofyar Z.; Santosa, Idwan; Miharja, Miming
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 (703.367 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.4.4

Abstract

The  swift  augmentation  in  the  adoption  of  smartphones,  the  gadget that  resulted  from  the  convergence  of  Information  and  Communication Technology  (ICT),  potentially  transforms  peoples  life  in  myriad  dimensions. One  potential  change  induced  by  smartphones,  is  how  people  restructure  their daily agenda and consecutively influence their travel pattern. To understand it, this study theoretically reviews  mobile professional work, smartphone adoption, and how people conduct their mobile interaction, planning and execution of daily activities. Mobile professionals, the  cohort of professionals  that spend more than 20% of their total working time moving  around out  of  their work environment; they  are  important  beneficiaries  of  smartphones  and   have  been  chosen  as  the target of  this  study. Empirical results of mobile professionals´ experiences in the Greater Jakarta Area are presented at this juncture. Furthermore, their adjustment of  activities  as  a  dynamic  response  to  receiving  extensive  information  via smartphones  is  also  analysed.  The  results  indicate  that  there  is  a  strong adjustment  of  daily  activities  by  mobile  professionals.  Through  those  changes, the transformation of daily travel patterns  related to the activity is  also  brought about by the use of this high-end ICT contrivance.
A New Approach to Blending and Loading Problem of Molten Aluminum Li, Jianhua; Xing, Wei
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 (166.877 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.4.8

Abstract

The  problems  of  blending  electrolyzer  and  multi-constraint optimization  of  electrolytic  aluminum  scheduling  in  the  electrolytic  aluminum production process were addressed.  Based on a mathematical model analysis, a novel  hybrid  optimization  algorithm  is  proposed  for  optimization  of  blending together  the  molten aluminum  in different  electrolytic cells. An affinity degree function  was  designed  to  represent  the  path  of  aluminum  scheduling.  The mutation  operators  were  designed  to  implement  the  transformation  of electrolyzer combination and change the route of loading. A typical optimization example from an aluminum plant in northwest China is given in this paper, the results of which demonstrate the effectiveness of the proposed method.
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.
Optimal Overhaul-Replacement Policies for Repairable Machine Sold with Warranty Soemadi, Kusmaningrum; Iskandar, Bermawi P.; Taroepratjeka, Harsono
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 (810.73 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.4.9

Abstract

This research deals with an overhaul-replacement policy for a repairable machine sold with Free Replacement Warranty (FRW). The machine will be used for a finite horizon, T (T <), and evaluated at a fixed interval, s (s< T). At each evaluation point, the buyer considers three alternative decisions i.e. Keep the machine, Overhaul it, or Replace it with a new identical one. An overhaul can reduce the machine age virtually, but not to a point that the machine is as good as new. If the machine fails during the warranty period, it is rectified at no cost to the buyer. Any failure occurring before and after the expiry of the warranty is restored by minimal repair. An overhaul-replacement policy is formulated for such machines by using dynamic programming approach to obtain the buyer’s optimal policy. The results show that a significant rejuvenation effect due to overhaul may extend the length of machine life cycle and delay the replacement decision. In contrast, the warranty stimulates early machine replacement and by then increases the replacement frequencies for a certain range of replacement cost. This demonstrates that to minimize the total ownership cost over T the buyer needs to consider the minimal repair cost reduction due to rejuvenation effect of overhaul as well as the warranty benefit due to replacement. Numerical examples are presented for both illustrating the optimal policy and describing the behavior of the optimal solution.
Skin Region Segmentation based on the Average Preprocessed Image of Multicolor Face Image Sequence Wei, Li; He, Xianbo; Jiao, Fangyuan
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 (104.804 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.4.3

Abstract

For face images with unbalance color and light, this paper proposed a method of skin region segmentation based on preprocessing of multicolor face image sequence. In this method, the multicolor face images of the sequence were preprocessed to remove color offset and uneven brightness. Then the color informations of preprocessed face images were jointly used for taking the average to remove noise and smooth the face image. Finally, for the average preprocessed face image, based on the established ellipse skin model, the skin region segmentation was realized. Experiments show that, this method had good performance.
Cover Vol. 46 No.4, 2014 Technological Sciences, Journal of Engineering and
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 (4209.961 KB)

Abstract

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