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INDONESIA
Makara Journal of Technology
Published by Universitas Indonesia
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Core Subject : Science,
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Articles 8 Documents
Search results for , issue " Vol 20, No 1 (2016)" : 8 Documents clear
A Comparison of American, Norwegian, and Russian Standards in Calculating the Wall Thickness of Submarine Gas Pipeline Dianita, Cindy; Dmitrieva, Tatyana Vladimirovna
Makara Journal of Technology Vol 20, No 1 (2016)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v20i1.3287

Abstract

One of the key issues in the pipeline design is wall thickness calculation. This paper highlights a comparison of wall thickness calculation methods of submarine gas pipeline based on Norwegian Standard (DNV-OS-F101), Indonesian Standard SNI 3474 which refers to American Standard(ASME B31.8), and Russian Standard (VN39-1.9-005-98). A calculation of wall thickness for a submarine gas pipeline in Indonesia (pressure 12 MPa, external diameter 668 mm) gives the results of 18.2 mm (VN39-1.9-005-98), 16 mm (ASME B31.8), and 13.5 mm (DNV-OS-F101).The design formula of hoop stress due to internal pressure is interpreted in different ways for every standard. Only Norwegian Standard requires calculating hoop stresses in the inner surface, which leads to a decreased value of the wall thickness. Furthermore, the calculation of collapse factor dueto external pressure is only regulated in Americanand Norwegian Standards while Russian Standard uses that factor as an intermediate parameter in calculating local buckling. For propagation buckling, either Russian or American Standard explains empirical formula of critical hydrostatics pressure as the input in propagation buckling calculation. This formula is almost similar to the empirical formula of Norwegian Standard. From the comparison of these standards, DNV OS-F101 gives more stringent requirements than others
Texture Analysis using The Neutron Diffraction Method on The Non Standardized Austenitic Steel Process by Machining,Annealing, and Rolling Priyanto, Tri Hardi; Parikin, Parikin; Li, Meijuan
Makara Journal of Technology Vol 20, No 1 (2016)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v20i1.3254

Abstract

Austenitic steel is one type of stainless steel which is widely used in the industry. Many studies on  austenitic stainless steel have been performed to determine the physicalproperties using various types of equipment and methods. In this study, the neutron diffraction method is used to characterize the materials which have been made from  minerals extracted from the mines in Indonesia. The materials consist of a granular ferro-scrap, nickel, ferro-chrome, ferro-manganese, and ferro-silicon added with a little titanium. Characterization of the materials was carried out in threeprocesses, namely: machining, annealing, and rolling. Experimental results obtained from the machining process generally produces a texture in the 〈100〉direction. From the machining to annealing process, the texture index decreases from 3.0164 to 2.434.Texture strength in the machining process (BA2N sample) is  8.13 mrd and it then decreases to 6.99 in the annealing process (A2DO sample). In the annealing process the three-component texture appears, cube-on-edge type texture{110}〈001〉, cube-type texture {001}〈100〉, and brass-type {110}〈112〉. The texture is very strong leading to the direction of orientation {100}〈001〉, while the {011}〈100〉is weaker than that of the {001}, and texture withorientation {110}〈112〉is weak. In the annealing process stress release occurred, and this was shown by more randomly pole compared to stress release by the machining process. In the rolling process a brass-type texture{110}〈112〉with a spread towards the goss-type texture {110}〈001〉 appeared,  and  the  brass  component  is markedly  reinforced  compared  to  the undeformed state (before rolling). Moreover, the presence of an additional {110} component was observed at the center of the (110) pole figure. The pole density of three components increases withthe increasing degree of thickness reduction. By increasing degrees of rolling from 81% to 87%, the value of orientation distribution function increases by a factor aboutthree times. 
Maneuverability of Ships with small Draught in Steady Wind Paroka, Daeng; Muhammad, Andi Haris; Asri, Syamsul
Makara Journal of Technology Vol 20, No 1 (2016)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v20i1.296

Abstract

Wind force and moment may force a ship to drastically decrease its speed and use a large drift angle as well as a large rudder angle in order to maintain its course. Shipswith a small draught might have more risk in maneuvering to its point of view compared with a ship with a larger draught. This paper discusses maneuverability of a ship with a small draught in steady wind. The effect of wind on ship speed, drift angle, and rudder angle are investigated in a steady state condition. Five different ratios of wind velocity to ship speed from 1.0 to 20.0 are used in the simulation. The variation in wind direction is examined from 0°to 180°. Results of the numerical simulation show that thewind has a significant effect on the reduction in ship speed with a wind direction less than 100°. The drift angle increases due to increasing wind velocity in the same wind direction. Wind direction also has a significant effect on the drift angle especially when the wind direction is less than 140°. The same phenomenon was found for the rudder angle. The necessary rudder angle is greater than the maximum rudder angle of the ship when the wind direction is 60°with a wind velocity to ship speed ratio of 20 or more.
Multi-Project Scheduling Cost Optimization in a Machine Manufacturer Engineer-to-Order Farizal, Farizal; Rachman, Amar; Tandean, Tifani; Sudarto, Sumarsono; Takahashi, Katsuhiko
Makara Journal of Technology Vol 20, No 1 (2016)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v20i1.3256

Abstract

This  paper  discusses  the  utilization  of  mixed  integer  linear programming  (MILP)  model  to  optimize  cost for multiproject scheduling in a  machine  maker company. The  objective is to minimize total project’s penalty cost and labor cost. The model formulated shows how to achieve theobjective i.e. whether to use outsourcing or overtime to finish all projects.  The  model  of  multi-project  scheduling  was solved  by  Branch  &  Bound  algorithm coded  in  Lingo 14.0 software.  The  case  study  shows  that  if  a company  wants  to  minimize  lateness,  it  should  use  overtime instead of outsourcing, which minimize total lateness of projects by 144 days or 73.5%. Whereas, if a company wants to optimize cost, they  should  use  outsourcing  instead  of  overtime,  which  reduces total  cost  of  about  10,873,000  IDR or  28.5%. These results indicate that the model developed is applicable for optimizing multi-project scheduling.
Thermal Properties, Crystallinity, and Oxygen Permeability of Na-montmorillonite Reinforced Plasticized Poly(lactic acid) Film Yuniarto, Kurniawan; Purwanto, Yohanes Aris; Purwanto, Setyo; Welt, Bruce A.; Purwadaria, Hadi Karia; Sunarti, Titi Candra
Makara Journal of Technology Vol 20, No 1 (2016)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v20i1.3105

Abstract

Introducing unmodified organically clay/Na-montmorillonite (Na-MMT) was applied into plasticized poly(lactic acid) PLA  to  produce  film  composites  by direct  casting.  Film  composite  structure,  the  crystallinity  degree  and  form, and thermal  properties  were  carried  out  using  X-ray  diffraction  and differential  scanning  calorimetry.  The effect  of NaMMT  to  the  tortuous path  and  the  crystallinity  degree  in  the  plasticized  film  composites  were calculated  in oxygen barrier  properties.  Chromatogram  film  composites resulted  in  an  intercalated  structure  that  showed  peak diffraction angle shift at about 0.2o. Then, a peak diffraction pattern was indicated in  Î±-form crystal structure. Plasticized PLA has a crystallinity degree at 34%, and the addition of  Na-MMT increased to 52%. Glass transition temperature improved from 53 °C to 57 °C, and melting temperature remained stable at 167 °C. Filling Na-MMT into plasticized PLA caused to enhance a tortuous path about 28% and improved the oxygen permeability to 80%. As a result, the addition of NaMMT of 3% into plasticized PLA during  film composite preparation using the mixing method resulted in balancing properties related to the crystallinity degree, thermal properties, and oxygen barrier properties. 
Discrete Power Control in Heterogenous Networks Hardjawana, Wibowo; Vucetic, Branka
Makara Journal of Technology Vol 20, No 1 (2016)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v20i1.3121

Abstract

In heterogeneous networks (HetNets) where femtocellbase stations (FBSs) are deployed within the radiocoverage of macrocell base stations (MBSs) to increase network capacity, co-channel interference limits overall system performance with  universal  frequency  reuse.  This  paper investigates  new  distributed  downlink  discrete  power control  scheme  for FBSs  in  HetNets  with  FBSs cooperation.  The  objective  of  the  proposed  power control  scheme  is  to  maximize  the number of simultaneous FBSs transmissions in a single transmission wireless channel where each FBS is  allowed to transmit only if the signal-to-interference-noise ratio (SINR) requirements for both FBSs and MBS users are satisfied. We apply a stochastic learning automata technique to FBSs where each FBS is treated  as a learning automaton and maintains a probability vector to select its discrete transmit power. During the learning process, each FBS adjusts its probability  vector based  on  the  feedback  from  FGW that  indicates  the  number  of  FBSs  transmissions  that can  be supported under the SINR requirement constraints ofFUEs and MUEs. Simulation results show the proposed algorithm can  achieve  more than  twice  the  number  of simultaneous  FBS  transmissions  achieved  by  existing schemes  in  the literature.
Analysis of Arm Movement Prediction by Using the Electroencephalography Signal Darmakusuma, Reza; Prihatmanto, Ary Setijadi; Indrayanto, Adi; Mengko, Tati Latifah; Andarini, Lidwina Ayu; Idrus, Achmad Furqon
Makara Journal of Technology Vol 20, No 1 (2016)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v20i1.3282

Abstract

Various technological approaches have been developed in order to help those people who are unfortunateenough to be afflicted with different types of paralysis which limit them in performing their daily life activitiesindependently. One of the proposed technologies is the Brain-Computer Interface (BCI). The BCI system uses electroencephalography (EEG) which is generated by the subject’s mental activityas input, and converts it into commands. Some previous experiments have shown the capability of the BCI system to predict the movement intention before the actual movement is onset. Thus research has predicted the movement by discriminating between data in the “rest” condition, wherethere is no movement intention, with “pre-movement” condition, where movement intention is detected before actual movement occurs. This experiment, however, was done to analyze the system for which machine learning was applied to data obtained in a continuous time interval, between 3 seconds before the movement was detected until 1 second after the actual movement was onset. This experiment shows that the system can discriminate the “pre-movement” condition and “rest” condition by using the EEG signal in 7-30 Hzwhere the Mu and Beta rhythm can be discovered with an average True Positive Rate (TPR) value of 0.64 ± 0.11 and an average False Positive Rate (FPR) of 0.17 ± 0.08. This experiment also shows that by using EEG signals obtained nearing the movement onset, the system has higher TPR or a detection rate in predicting the movement intention.
Residual Strength Analysisof Asymmetrically Damaged Ship Hull GirderUsing Beam Finite Element Method Muis Alie, Muhammad Zubair
Makara Journal of Technology Vol 20, No 1 (2016)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v20i1.3252

Abstract

The objective of the present study is to analyze the residual strength of asymmetrically damaged ship hull girder under longitudinal bending. Beam Finite Element Method isused for the assessment of the residual strength of two single hull bulk carriers (Ship B1 and Ship B4) and a three-cargo-hold model of a single-side Panamax Bulk Carrierin hogging and sagging conditions. The Smith’s  method  is  adopted  and  implemented  into  Beam  Finite  Element Method. An efficient solution procedure is applied; i.e. by assuming the cross section remains plane, the vertical bending moment is applied to the  cross section  and  three-cargo-hold  model. As a fundamental  case,  the  damage is simply  created  by removing the elements from the cross section, neglecting any welding residual stress and initial imperfection. Also no crack  extension  is considered.  The  result  obtained  by  Beam  Finite  Element  Method  so-called Beam-HULLST is compared to the progressive collapse analysis obtained by HULLST for the validation of the present work. Then, for the three-hold-model, the Beam-HULLST is used to investigate the effect of the rotation of the netral axisboth intact and damage condition taking the one and five frame spaces into account. 

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