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INDONESIA
Makara Journal of Technology
Published by Universitas Indonesia
ISSN : -     EISSN : -     DOI : -
Core Subject : Science,
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Articles 6 Documents
Search results for , issue " Vol 7, No 1 (2003)" : 6 Documents clear
Photocatalytic Treatment of Heavy Metal Waste Cr(VI) withTiO2 Photocatalyst Slamet, Slamet; Syakur, Riyadi; Danumulyo, Wahyu
Makara Journal of Technology Vol 7, No 1 (2003)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v7i1.58

Abstract

The photocatalytic reduction of hexavalent chromium/Cr(VI) using TiO2 and copper-doped TiO2 as photocatalysts have been studied in stirred tank and circulating photoreactors. All photocatalysts were characterized with FTIR (Fourier Transform Infra Red), BET (Brunauer-Emmett-Teller), XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscope). TiO2 Merck and Degussa P-25 are the commercial photocatalysts used to compare the photocatalytic activity of all the prepared catalysts. Blank test experiments as well as the effect of dopants, EDTA (ethylenediaminetetraacetic acid) and activated carbon addition were studied. Cr(VI) reduction on various pH and initial Cr(VI) concentration were also conducted. The results of the experiments showed that the addition of EDTA as a hole scavenger can increases the activity of all catalysts at about 10%. Rate of Cr(VI) photoreduction is more feasible at low pH and low initial Cr(VI) concentration. The addition of activated carbon (AC) increases the photocatalytic activity at about 5% due to the synergy effect between catalyst and AC. Pure TiO2 powder prepared from TiCl4 has the highest activity in reducing Cr(VI) with the conversion of 80% due to the high crystalline (anatase) and surface area. Photoreduction of Cr(VI) over TiO2 film photocatalyst in circulating photoreactor has not shown a significant result yet. Therefore it is needed to improve furthermore the photoreactor system especially for the film type photocatalyst.
Influence of Strain Rate and Temperature of Hot Tension Testing on Mechanical Properties of Medium Carbon Steel S48C Priadi, Dedi; Setyadi, Iwan; Siradj, Eddy
Makara Journal of Technology Vol 7, No 1 (2003)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v7i1.59

Abstract

The characterization of S48C by hot tension testing was done to understanding the influence of temperature and strain rate for S48C flow stress, that close relationship with its forge ability. The hot tension testing was performed on temperatures and strain rates variation (T 850, 900, 950 0C and έ 0,01;1 s-1). The result of hot tension testing showed that increasing temperature decreases ultimate tensile strength (UTS) and flow stress of S48C. The higher decreasing of UTS is on 950 0C about 85% from room temperature condition, while the higher decreasing of flow stress has occurred on 950 0C about 31 % compare to conditions of temperature 850 0C, strain 0,23 & strain rate (έ)1 second-1 and about 27% compare to the same conditions but έ= 0,01 second-1 . For increasing strain rate from 0,01 to 1 second-1 on the temperature range (850-950 0C) increases UTS about 33 - 50 % and flow stress about 46-53%.
Study About High Influence Doping to Base Resistance and Bandgap Narrowing at Si/Si1-xGex/Si Heterojunction Bipolar Transistor Fadhol, Achmad
Makara Journal of Technology Vol 7, No 1 (2003)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v7i1.60

Abstract

Heterojunction is a link formed bedween two semiconductor materials and differend bandgap which has thinness under 50nm and grow the mixture of plate SiGe as bases. The link is an abrupt link or graded one. In this research learnt formulation of doping concentration influence to basis resistance and bandgap narrowing through Si/Si1-xGex/Si Heterojunction Bipolar Transistor with abrupt emitter-basis link, besides taking care to mobility and basis wide to basis resistance, it is also influence of mole fraction to bandgap power. From the result shows that doping concentration addition of NB=5.1018 cm-3 to NB=5.1020 cm-3 in basis can decrease resistance basis value about 3.6%, increase bandgap narrowing about 0.126, and increase collector current density for about 1.36 times to Ge 24%.
Phase Composition Analysis Using Rietveld Methode and Its Influence To The Hardness Of Ti-Si-N Nanocomposites Moto, Keba; Setiarini, Lia; Abubakar, Zufar
Makara Journal of Technology Vol 7, No 1 (2003)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v7i1.61

Abstract

XRD data of nanocomposites Ti-Si-N have been analysed using GSAS based on Rietveld Method in order to identifyphases and their composition as well as its influence on the hardness of these nanocomposites. Several new phaseshave been found in the sample beside the nc-TiN/a-Si3N4& a-/nc-TiSi2 that have been known widely. From the obtainedcrystalline phase, after the calculation of amorf Si3N4 and TiSi2 phase fraction, it is found that the optimum hardness can be reached when the fraction of a-Si3N4 phase around 8 wt.%
Development and Analysis of Geographic Information System for Electricity Network (Case Study: Surabaya Industrial Estate Rungkut in Surabaya). Awalin, Lilik; Sukojo, Bangun
Makara Journal of Technology Vol 7, No 1 (2003)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v7i1.57

Abstract

Geographic Information System (GIS) is a system of data which has spatial base. This may be cause has ability to process and analysis data quickly. The ability of GIS will be able to process the alternative in decision making. The need of electric power grows until recent time along with the existence of industrial sector expansion and land use expansion claim better service, large and balance stock of electric power. GIS is a solution for planning and managing data base system, for quickly service and professional service to consumer in Surabaya Industrial Estate Rungkut (SIER) Area. By using Arc View to process the data which has spatial base, and supported by energy and voltage data in Surabaya Industrial Estate Rungkut area, the resistance, current, voltage regulation, energy losses supplied by Surabaya Industrial Estate Rungkut can be calculated. The existence of GIS technology can assist the work process in operator level and the balance of electrical power efficiency.
Application of Remote Sensing and Geographic Information System Methods for Land Using Difference Sukojo, Bangun; Susilowati, Diah
Makara Journal of Technology Vol 7, No 1 (2003)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v7i1.62

Abstract

Land using difference analysis has been done using remote sensing and Geographic Information System (GIS) methods. Identification of land using difference was conducted using map overlaying process of 1990s (digitized scalling 1:50.000) and 1997s land using map (interpreted from Landsat TM (Thematic Mapper) Image 1997) with UTM (Universal Transverse Mercator) coordinate. Image enhancement was done through histogram equalization with supervised classification devided into 7 classes: rice field, settlement, dry field, industry, pond, sport field and bush. Land using difference and river pollution BOD (Biological Oxygen Demand), COD (Chemical Oxygen Demand) and TSS (Total Suspended Solid) analysis were done through GIS to get database in spasial link and tabular format. Land Using difference was done based on division segment of Kali Surabaya contour as reference. The result shows that there were changes on land using from 1990 until 1997 that rice field reduced by 5.72 %; settlement increased by 15,16 %; dry field increased by 0.54 %; industry increased by 36.67 % and bush reduced by 26.67 %. Water pollution analysis results which was done using multiple linier regression show both BOD (determinant coefficient 56 %) and TSS (determinant coefficient 65 %) are affected by difference in land using, but COD (determinant coefficient 24 %) is not affected.

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