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INDONESIA
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 1,267 Documents
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Realization of a Second Harmonic Antenna for Rural Communications* Adit Kurniawan; Ahmad Hasyim; Yuyu Wahyu
Journal of Engineering and Technological Sciences Vol. 38 No. 2 (2006)
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.2006.38.2.2

Abstract

In this research, an active antenna operated at the second harmonic frequency is investigated, and is implemented using microstrip antenna material. The antenna consists of a FET oscillator which plays as a fundamental frequency oscillator and a frequency multiplier, and a patch antenna resonated at the second harmonic frequency as the radiator. A maximum second-harmonic output power can be extracted when the load impedance of the oscillator is optimized both at the fundamental and at the second harmonic frequencies. A rectangular patch antenna is used to radiate the second harmonic output power from the oscillator. The patch impedance is matched resistively at the second harmonic frequency. The patch antenna is fabricated using Diclad 522 microstrip substrates (relative permitivity r = 2.5) with a dielectric thickness of 1.57 mm. A GaAs FET AT-8250 transistor is used as an oscillator and a frequency multiplier and acts as the active component. Fundamental frequency is designed at 2,4 GHz band, so that the second harmonic frequency operates at 4,8 GHz band. The frequency is chosen to facilitate and to extend the needs of communications in rural areas using the unlicensed Industrial Scientific, and Medical (ISM) band. Operating the communication infrastructures intended for the use at 2.4 GHz band at its second harmonic frequency, is intended to alleviate interference levels at 2.4 GHz.
Biomarker as an Indicator of River Water Quality Degradation Dwina Roosmini; Indah Rachmatiah; Suharyanto Suharyanto; Agus Soedomo; Fajar Hadisantosa
Journal of Engineering and Technological Sciences Vol. 38 No. 2 (2006)
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.2006.38.2.3

Abstract

Generally physical and chemical methods are use in river water quality monitoring; currently biomarker is developed as alternative biomonitoring method. The aim of this study is to look at the probability using aquatic species in monitoring river water pollutants exposure. This study was done by using Hyposarcus pardalis as biomarker to analyze river water quality in Upstream Citarum River. Hyposarcus pardalis were taken along the river at five sampling point and look at the Cu and Zn concentration. Results from this study show that there was an indication that river water quality has been degrading along the river from upstream to downstream. Zn concentration in Hyposarcus pardalis were increasing as well as Cu concentration. The increase of Zn concentration in Hyposarcus pardalis indicating that the river was polluted by Zn. Secondary data and observation at sampling location shown that textile was the dominant industry which may contribute the Zn concentration in river as they received the effluent. Cu is use in metal coating process, as well as textile industry metal industries were identified at Majalaya, Bantar Panjang, Dayeuh Kolot and Katapang in Bandung-Indonesia. As a receiving water from many activities along the river, upstream Citarum River water quality become degrading as the increasing of heavy metal Zn and Cu concentration in Hyposarcus pardalis.
Deformation Study of Papandayan Volcano using GPS Survey Method and Its Correlation with Seismic Data Observation Dina A. Sarsito; Heri Andreas; Hasanuddin Z. Abidin; Muhammad Gamal; Ony K. Suganda; Muhammad Hendrasto
Journal of Engineering and Technological Sciences Vol. 38 No. 2 (2006)
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.2006.38.2.4

Abstract

Papandayan volcano located in the southern part of Garut regency, around 70 km away from Bandung city, West Java. Many methods carried out to monitoring the activities of volcano, both continuously or periodically, one of the monitoring method is periodically GPS survey. Basically those surveys are carried out to understand the pattern and velocity of displacement which occurred in the volcano body, both horizontally and vertically, and also others deformation elements such as; translation, rotation and dilatation. The Mogi modeling was also used to determine the location and volume of the pressure source which caused deformation of volcano body. By comparing seismic activity and the deformation reveal from GPS measurement, before, during and after eruption, it could be understood there is a correlation between the seismicity and its deformation. These studies is hoping that GPS measurement in Papandayan volcano could be one of supported method to determine the volcano activities, at least in Papandayan volcano.
The Identification of Fishing Ground Area with MODIS Satellite Image (Case Study: South Coast of West Java) Dudung Muhally Hakim; Ketut Wikantika; Nengah Widiadnyana; Asmi M. Napitu; Soni Darmawan
Journal of Engineering and Technological Sciences Vol. 38 No. 2 (2006)
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.2006.38.2.5

Abstract

 According to UNCLOS, Indonesian marine territorial covers an area equal to around 2.8 million square kilometers inner archipelagic seas. Though the Indonesian water region is very wide, the resource within it is not yet been exploited optimally. Indonesia still has problems that have to be copped with, including identification of marine fishing ground areas. This report proposes a technology to make the fish-catching be more efficient and effective with the help of MODIS satellite image in term of Surface Temperature and chlorophyll-a computation. Data conversion from digital number to Water Brightness Temperature are performed. The determination of potential fishing ground area were conducted based on temperature and chlorophyll-a parameters which serve as an indicator of upwelling and observations were carried out on parameters which show this phenomenon. Based on the result, during May 2004 the upwelling process were not happened yet, and it seems to occur in June 2004. It showes by the decreasing of water temperature in South Coast of West Java particularly between the border of West Java and Central of Java. This phenomenon acts as an indicator for the raising of primer productivity and will takes about one month after upwelling to the bloom of phytoplankton.
Effects of Fracture Parameters in an Anisotropy Model on P-Wave Azimuthal Amplitude Responses Fatkhan Fatkhan
Journal of Engineering and Technological Sciences Vol. 38 No. 2 (2006)
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.2006.38.2.6

Abstract

The study showed that the presence of vertically aligned fractures in reservoir rock could possibly be inferred through analysis of P-wave reflectivity variations with azimuth. The azimuthal amplitude responses measured at an interface separating overburden anisotropy and fractured rock rely on several parameters that can be decomposed into the background rock and the fracture contributions.The effect of fracture porosity on P-wave azimuthal amplitude response is small for moderate incidence angles. For fluid filled fractures P-wave anisotropy is mildly affected. For dry fractures the difference in P-wave anisotropy between low and high fracture porosities is high. This suggests that an assumption of overburden isotropy may result in a large error in predicting the fluid type and saturation.
Chemical Characterization of Flour Fractions from Five Yam (Dioscorea alata) Cultivars in Indonesia Lula Nadia; M. Aman Wirakartakusumah; Nuri Andarwulan; Eko Hari Purnomo; Takahiro Noda; Koji Ishiguro
Journal of Engineering and Technological Sciences Vol. 47 No. 1 (2015)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2015.47.1.7

Abstract

The purpose of this study was to investigate the influence of particle size on  the  chemical properties  of yam flour  in five  cultivars, yellow/YY, orange/OY, light purple/LPY, purple/PY, and dark purple/DPY. With a mesh sieve, three  flour fractions  were separated according to particle size:  small (128.6-139.7 µm), medium (228.7-257.9 µm), and large (475.4-596.3 µm). The content of moisture (6.81-11.26 %db) and lipids (4.48-9.85 %db) decreased with the increase of particle size, while proteins (4.48-9.85 %db) and carbohydrates (78.12-83.76 %db) were not influenced by particle size. Folin-Ciocalteu reagent and chlorogenic acid were used as standard to investigate the total phenolic compounds  in  the  yam  flour,  and  high-performance liquid chromatography (HPLC) was used to investigate the anthocyanin and carotene contents. It was found that there was no size influence on the content of phenolics (0.27-2.82%db), anthocyanin (2.25-15.27  mg/100g db) in LPY, PY, DPY  or  carotene (23.75-132.12 mg/100g db) in YY, OY. The differences in chemical composition were due to differences in particle size and heat treatment, but may also have been caused by the different composition of the milling process.
Bacteria as Self-Healing Agent in Mortar Cracks Ananto Nugroho; Iman Satyarno; Subyakto Subyakto
Journal of Engineering and Technological Sciences Vol. 47 No. 3 (2015)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2015.47.3.4

Abstract

This study was aimed at finding the possibility to apply Bacillus subtilis integrated into mortar matrix to act as a self-healing agent to seal cracks. Bacterial spores at concentrations of 104, 105, and 106 cells/ml were directly added into pulverized fly ash as medium to protect bacteria in high alkaline conditions. The results show that the addition of Bacillus subtilis spores into the mortar mixture enhanced the compressive strength, especially at a cell concentration of 105 cells/ml. The bacterial mortar had a small ability to recover the stiffness of the mortar, amounting to 34.85% of its original stiffness. The effectiveness of crack sealant and resistance to water flow were limited to a maximum crack width size of 0.22 mm. Physical observation showed that the bacterial mortar is characterized by calcite precipitation as a product of ureolytic bacteria. The quantity and distribution of calcite precipitate depended on the precipitation weight, gravity direction and oxygen availability. Meanwhile, chemical analysis using XRD and EDX showed that the bacterial mortar had a better crystallinity.
Depositional Environment of the Sangkarewang Oil Shale, Ombilin Basin, Indonesia Komang Anggayana; Agus Haris Widayat; Sri Widodo
Journal of Engineering and Technological Sciences Vol. 46 No. 4 (2014)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | 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.
On the Development of a Nomogram for Alkali Activated Fly Ash Material (AAFAM) Mixtures Partogi H. Simatupang; Iswandi Imran; Ivindra Pane; Bambang Sunendar
Journal of Engineering and Technological Sciences Vol. 47 No. 3 (2015)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2015.47.3.1

Abstract

Alkali activated fly ash material (AAFAM) has become the most promising material to substitute materials based on ordinary Portland cement (OPC). However, there is no available nomogram for AAFAM mixtures. In contrast, there are many rational methods available in the literature to make paste, mortar and concrete with OPC based materials, such as Monteiro-Helene's nomogram, which uses Abram's law, Lyse's law and Molinari's law. This paper presents a study to construct such a nomogram for AAFAM mixtures by first conducting experiments on the  paste and mortar phases. The procedure of Monteiro-Helene's nomogram was adopted in this formulation. The first step in this direction was to find a close relationship between the strength and paste composition of the material that can be used as a substitute for Abram's law. The second step  was  to construct the equivalent  of  Lyse's and Molinari's relationships by varying the sand and fly ash contents. The results show that it is possible to make a nomogram for AAFAM mixtures such as the one for OPC based materials. Class F fly ash and its mortar phase were used to construct the nomogram. In addition, the  mortar  samples  that were  used to build the nomogram had similar solidification products according to their microscopic characteristics.
Optimal Overhaul-Replacement Policies for Repairable Machine Sold with Warranty Kusmaningrum Soemadi; Bermawi P. Iskandar; Harsono Taroepratjeka
Journal of Engineering and Technological Sciences Vol. 46 No. 4 (2014)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | 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 <ï‚¥), 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.

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