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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 10, No 1 (2006)" : 8 Documents clear
Modeling of Coupled-Tank System Using Fuzzy Takagi-Sugeno Model Subiantoro, Aries
Makara Journal of Technology Vol 10, No 1 (2006)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v10i1.108

Abstract

This paper describes modeling of coupled tank system based on data measurement using fuzzy Takagi-Sugeno model. The fuzzy clustering method of Gustafson-Kessel algorithm is used to classify input-output data into several clusters based on distance similarity of a member of input-output data from center of cluster. The formed clusters are projected orthonormally into each linguistic variables of premise part to determine membership function of fuzzy Takagi-Sugeno model. By estimating data in each cluster, the consequent parameters of fuzzy Takagi-Sugeno model are calculated using weighted least-squares method. The resulted fuzzy Takagi-Sugeno model is validated by using model performance parameters variance-accounted-for (VAF) and root mean square (RMS) as performance indicators. The simulation results show that the fuzzy Takagi-Sugeno model is able to mimic nonlinear characteristic of coupled-tank system with good value of model performance indicators.
On The Performance of Imt-2000 Communication Link Based on Stratospheric Platforms Iskandar, Iskandar; Shimamoto, Shigeru
Makara Journal of Technology Vol 10, No 1 (2006)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v10i1.104

Abstract

A new means for providing wireless communication has been currently proposed. It is based on aerial vehicle known as High Altitude Platform or Stratospheric Platforms (SPF). The SPF will be operated at an altitude of 17-22 km above the ground. Therefore, the channel condition may be different compared with those of the conventional terrestrial or satellite wireless channel. In this paper, the channel propagation characteristic of such a system is firstly investigated by means of ray tracing algorithm. We emphasize our investigation in a typical urban environment, in which the mobile users mostly exist. We developed building block model for simulation based on building height distribution, which is obtained from measurement inside Tokyo. As a result, propagation loss model and Ricean channel parameter for the SPF channel is reported in different scenarios. By using this result we then estimate the required transmitted power of SPF to serve the mobile users in a several transmission rate that is used in IMT-2000 services. Finally, an evaluation of BER of IMT-2000 link is performed in order to estimate the system level performance. From this evaluation, the main contribution of this paper is to clearly show the critical limitations of both power requirement as well as system level performance of mobile communication IMT-2000 by using the concept of the SPF.
Design of Induction Motor Drive Without Velocity Sensor Using Current Vector Controller with Full and Reduced Observer Moving to DQ Axis Gunawan, Ridwan; Yusivar, Feri; Wahab, Wahidin; Kadir, Zuhal
Makara Journal of Technology Vol 10, No 1 (2006)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v10i1.109

Abstract

The observer is used in estimation velocity sensor usually in α-β axis, therefore this situation will need an extra transformation when we want to add compensator because the flux model is in direct and quadrature-axis dq. Every used the transformation to make possible emerge an error. So in this simulation is used a method to estimate the velocity of induction motor drive with observer that is moved to dq-axis. The model of actual motor used is in alfa-beta axis, but the observer use the motor models in rotor flux oriented control (RFOC).This matter, also to prove that the different models of motor drives can be used between the actual and estimated one. The simulation results with C-MEX S-function Matlab/Simulink 6.5 to show that the full order observer in dq axis gives better performance than the reduced order observer.
Analysis of Technical Energy Losses By Using Simulation Betrianis, Betrianis; Herawan, Randite
Makara Journal of Technology Vol 10, No 1 (2006)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v10i1.105

Abstract

Model is a representation of a system. Through model, it can be easier to forecast and control the changing of each element system. Electricity distribution is also a system. Losses are general problem that exist in a distribution network system. But with the right methods, specifically technical energy losses can be reduced in order to increase the efficiency. By making model of the distribution network, the value of technical energy losses in the whole network as well as in every line can be observed. Simulation can also be used to see all losses reduction alternatives. By comparing results from each alternatives, the best alternative, which gives best result can be decided and implemented.
Hybrid Identification System with ARX and Fast Fourier Transform in Application of a Quarter of Vehicle Half Active Suspension Lysbetti, Noveri; Rajagukguk, Antonius
Makara Journal of Technology Vol 10, No 1 (2006)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v10i1.110

Abstract

In a control system problem, identification system mechanism is a absolute thing, especially in adaptation controlling to disturbance changing. For that case, is needed an identification method which can identify the changing of disturbance in that system. The aim of this research is to give an alternative in system/plant identification which is a combination (hybrid) of ARX and Fast Fourier Transform. So, it is needed an algorithm design for identification process. In this case, the designed algorithm will be implemented in software that works based on Matlab. The result of car mass 500Kg in seventh second with first way disturbance is the biggest frequency at this time. Operation frequency produced is 27.4889Hz, estimation model magnitude is 1.3431E-006 and estimation model phase is -86.8307. The result of car mass 1000Kg in 15th-second, with second way disturbance is the biggest frequency at this time. Operation frequency produced is 3.9270Hz, estimation model magnitude is 1.1780E-006 and estimation model phase is 131,5950. These results show that as lighter car mass when disturbance happened by road surface, as bigger the operation frequency happen.
Effect of Firing Temperature and Holding Time on Characterization of Al/SiC Metal Matrix Composites Produced by Pressureless Infiltration. Zulfia, Anne; Ariati, Myrna
Makara Journal of Technology Vol 10, No 1 (2006)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v10i1.106

Abstract

 The production of Al-SiC metal matrix composite can be carried out by pressureless metal infiltration processs (PRIMEX). The experiment was conducted using aluminium AC2B ingot as a matrix and 50%Vf SiC powder as a reinforcement which is mixed with  10% Mg powder for wetting agent. The variables of this experiment are holding time and firing temperature to investigate the effect of these conditions on mechanical properties of Al-SiC metal matrix composites. Holding time was conducted for 2,5,8,10,12 hours and firing temperatures was 750, 800, 900, 1000, 1100°C respectively.. The composites produced are analysed both mechanical properties and metalography such as densities, porosities, hardness, as well as wear rate. The results showed that the longer holding time and increasing firing temperature will increase mechanical properties of Al-SiC metal matrix composites, and it is found that the optimum mechanical properties at 1000°C for 10 hour.
Development of Fiber-Optic Humidity Sensor Probe with Gelatin Cladding Maddu, Akhiruddin; Modjahidin, Kun; Sardy, Sar; Zain, Hamdani
Makara Journal of Technology Vol 10, No 1 (2006)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v10i1.111

Abstract

Humidity sensor based on optical fiber with gelatin cladding has been developed. In this humidity sensor probe, the origin cladding of optical fiber is replaced by gelatin coating as humidity sensitive cladding. Testing of the optical fiber sensor probe was conducted by measuring of light intensity transmitted on the optical fiber probe for each variation of different humidity treatments. Response of the optical fiber sensor probe measured from 42%RH to 99%RH, the results show an optical transmission curve varied with relative humidity (RH). Optical transmission in the optical fiber probe increase with RH value at a specific wavelength range, that is from green to red spectrum bands (500 nm - 700 nm), where a significant variation from 600 nm to 650 nm in yellow to red spectrum bands. Wavelength where is a maximum intensity of optical transmission occurs at 610 nm. Therefore, the optical fiber humidity sensor probe could response humidity form 42%RH to 99%RH with the best response in humidity range of 60%RH to 72%RH that is have a good  linearity and sensitivity
Modification of Bonding Strength Test of WC HVOF Thermal Spray Coating on Rocket Nozzle Sofyan, Bondan; Pardede, Haposan; Stefano, Marizki; Sofyan, Edi
Makara Journal of Technology Vol 10, No 1 (2006)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v10i1.107

Abstract

One way to reduce structural weight of RX-100 rocket is by modifying the nozzle material and processing. Nozzle is the main target in weight reduction due to the fact that it contributes 30 % to the total weight of the structur. An alternative for this is by substitution of massive graphite, which is currently used as thermal protector in the nozzle, with thin layer of HVOF (High Velocity Oxy-Fuel) thermal spray layer. This paper presents the characterization of nozzle base material as well as the modification of bonding strength test, by designing additional jig to facilitate testing processes while maintaining level of test accuracy. The results showed that the material used for  RX-100 rocket nozzle is confirmed to be S45C steel. Modification of the bonding strength test was conducted by utilizing chains, which improve test flexibility and maintains level of accuracy of the test.

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