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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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Improved Predictive Power Control Algorithms to Increase CDMA System Capacity Kurniawan, A.; Iskandar, Iskandar; Machdar, Sayid
Journal of Engineering and Technological Sciences Vol 41, No 2 (2009)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (276.786 KB) | DOI: 10.5614/itbj.eng.sci.2009.41.2.7

Abstract

In  this  paper  capacity  of  CDMA  system  is  evaluated  using  an improved  algorithm  of  channel  prediction-based  power  control  in  Rayleigh fading  channel environments. One  of the most serious problems which degrades the performance of power control algorithm is the effect of feedback delay. To overcome the effect of feedback delay, power control algorithm relies on channel prediction techniques, which utilize the correlation property of the past  channel measurements.  In  CDMA  power  control,  however,  the  correlation  property  of channel  measurements  is destroyed  because the  transmit power  is continuously updated  for  each  power  control  interval.  In  order  to  restore  the  correlation property of the channel,  the past  channel measurements  are compensated  for by the  same  factors  that  were  given  by  power  updating  for   each  power  control interval. The prediction algorithm in this paper is proposed using the least mean square  (LMS) technique. The result shows that the capacity of CDMA systems increase  significantly  when  the  improved  predictive  algorithm  is  used. Numerical evaluation shows that CDMA capacity increases by more than 40 % for fixed step algorithm and more than 50 % for variable step algorithm when the proposed algorithm is employed. 
Uplift of Kelud Volcano Prior to the November 2007 Eruption as Observed by L-Band Insar Lubis, Ashar Muda
Journal of Engineering and Technological Sciences Vol 46, No 3 (2014)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1811.632 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.3.1

Abstract

Kelud volcano, a stratovolcano with summit elevation of 1731 m above sea level, is considered to be one of the most dangerous volcanoes in Java, Indonesia. Kelud volcano erupts frequently, with the most recent eruption occurred on November 3, 2007. Therefore, volcano monitoring, especially detecting precursory signals prior to an eruption, is important for hazard mitigation for Kelud volcano. Interferometric Synthetic Aperture Radar (InSAR) has been proven to bea powerful tool for investigating earth-surface deformation. Hence, we applied D-InSAR (differential InSAR) in an effort to identify pre-eruptive deformation of Kelud volcano before November 2007 eruption. SAR images, L band ALOS-PALSAR, were used to construct 3 coherent interferograms between January to May 2007. We used the D-InSAR technique to remove topographic effects from interferometry images. During the interval observation, we detected a continuous inflation with a maximum line-of-sight (LOS) displacement of 11cm. Uplift of Kelud volcano was also observed by the tiltmeter 1-2 months prior to the November 2007 eruption. We interpret this inflation as a manifestation of increased volume of magmatic material in the shallow reservoir and magmatic migration towards the surface, indicating an imminent eruption. This study confirms that InSAR technique is a valuable tool for monitoring volcano towards better hazard mitigations.
A New Control Method to Reduce the Low-Frequency Output Current Ripple of AC-DC Converters by Using Virtual Inductor Dahono, Pekik Argo
Journal of Engineering and Technological Sciences Vol 44, No 1 (2012)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (508.577 KB) | DOI: 10.5614/itbj.eng.sci.2012.44.1.4

Abstract

A new concept of virtual inductor to reduce the low-frequency dc output current ripple of ac-dc converters is introduced in this paper. Virtual inductor is defined as an additional control algorithm that changes the system behavior into the one that has an additional inductor connected on it. The virtual nature of the inductor makes the inductance can be designed without weight and volume restrictions. How to use the virtual inductor to improve the performance of converter current controller is discussed in this paper. Several simulated and experimental results are included to show the validity of the proposed concept.
Gas Deliverability Model with Different Vertical Wells Properties Mucharam, L.; Sukarno, P.; Siregar, S.; Syihab, Z.; Soewono, E.; Apri, M.; Irzal, F.
Journal of Engineering and Technological Sciences Vol 35, No 2 (2003)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (851.743 KB) | DOI: 10.5614/itbj.eng.sci.2003.35.2.3

Abstract

We present here a gas deliverability computational model for single reservoir with multi wells. The questions of how long the gas delivery can be sustained and how to estimate the plateau time are discussed here. In order to answer such a question, in this case, a coupling method which consists of material balance method and gas flow equation method is developed by assuming no water influx in the reservoir. Given the rate and the minimum pressure of gas at the processing plant, the gas pressure at the wellhead and at the bottom hole can be obtained. From here, the estimation of the gas deliverability can be done. In this paper we obtain a computational method which gives direct computation for pressure drop from the processing plant to the wells, taking into account different well behavior. Here AOF technique is used for obtaining gas rate in each well. Further Tian & Adewumi correlation is applied for pressure drop model along vertical and horizontal pipes and Runge-Kutta method is chosen to compute the well head and bottom hole pressures in each well which then being used to estimate the plateau times. We obtain here direct computational scheme of gas deliverability from reservoir to processing plant for single reservoir with multi-wells properties. Computational results give different profiles (i.e. gas rate, plateau and production time, etc) for each well. Further by selecting proper flow rate reduction, the flow distribution after plateau time to sustain the delivery is computed for each well.
Realization of a Second Harmonic Antenna for Rural Communications* Kurniawan, Adit; Hasyim, Ahmad; Wahyu, Yuyu
Journal of Engineering and Technological Sciences Vol 38, No 2 (2006)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (471.507 KB) | 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.
Set Up and Calibration of a Spatial Tool for Simulating River Discharge of Western Java in Recent Decades: Preliminary Results and Assessments Poerbandono, Poerbandono; Ward, Philip J.; Julian, Miga M.
Journal of Engineering and Technological Sciences Vol 41, No 1 (2009)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (629.791 KB) | DOI: 10.5614/itbj.eng.sci.2009.41.1.4

Abstract

This  paper  discusses  a  study  of  the  application  of  global  spatiotemporal climate datasets and the hydrological model STREAM   (Spatial Tools for River Basin Environmental Analysis and Management Options). In the study, set up and calibration  of STREAM for  the reconstruction of monthly discharge for several locations in the western part of Java, Indonesia, for the period 1983 -2002 are carried out. The set up includes the preparation of monthly precipitation and temperature datasets, a digital elevation model of the domain being studied, and maps of land cover and soil water holding capacity. Discharge observations from  six  stations  located  mostly  in  the  upper  parts  of  major  watersheds  in  the domain  are  used  to  calibrate  the  model  by  comparing  simulated  and  observed discharge variables. The model performs reasonably well.  Comparison  between computed and observed mean monthly discharges yield correlation coefficients ranging from 0.72 to 0.93. The  computed mean annual discharge in five out of six  observation  stations  ranges  between  -8  and  5%  with  respect  to  the  mean annual  observed  discharge.  This  study  offers  a  tool  which  can  be  used  for reconstructing historical discharge
Structured Mathematical Modeling of Industrial Boiler Aziz, Abdullah Nur; Nazaruddin, Yul Yunazwin; Siregar, Parsaulian; Bindar, Yazid
Journal of Engineering and Technological Sciences Vol 46, No 1 (2014)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (728.325 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.1.7

Abstract

As a major utility system in industry, boilers consume a large portion of the total energy and costs. Significant reduction of boiler cost operation can be gained through improvements in efficiency. In accomplishing such a goal, an adequate dynamic model that comprehensively reflects boiler characteristics is required. This paper outlines the idea of developing a mathematical model of a water-tube industrial boiler based on first principles guided by the bond graph method in its derivation. The model describes the temperature dynamics of the boiler subsystems such as economizer, steam drum, desuperheater, and superheater. The mathematical model was examined using industrial boiler performance test data.It can be used to build a boiler simulator or help operators run a boiler effectively.
Sorption and Degradation Capacity of Natural Estrogens in Freshwater Environmental System in Japan Desmiarti, Reni; Li, Fu-Sheng
Journal of Engineering and Technological Sciences Vol 43, No 2 (2011)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (145.037 KB) | DOI: 10.5614/itbj.eng.sci.2011.43.2.6

Abstract

The  sorption  and  the  degradation  capacity  of  natural  estrogens  in freshwater  environmental  system  in  Japan  were  performed.  Batch  experiments were examined in water-sediment suspensions using six layers of sediment under aerobic and anaerobic conditions. The results indicated that the water-sediment partition coefficient of E1 (KdE1) was higher than E2 (KdE2). The degradation rate of E1 (kE1) was smaller than E2 (kE2). Under aerobic and anaerobic conditions, E1  was  formed  from  E2.  The  degradation  rate  of  E2  (kE2)  from  the  surface  to bottom of sediment layers was estimated fell in the range from 0.114 to 0.026 h-1 and 0.05 to 0.014 h-1  under aerobic and anaerobic conditions, respectively. 
The Effect of Tin Addition to ZnO Nanosheet Thin Films for Ethanol and Isopropyl Alcohol Sensor Applications Yuliarto, Brian; Julia, Sri; Wulan S., Ni Luh; Iqbal, Muhammad; Ramadhani, Muhammad F.; Nugraha, N.
Journal of Engineering and Technological Sciences Vol 47, No 1 (2015)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (998.718 KB) | DOI: 10.5614/j.eng.technol.sci.2015.47.1.6

Abstract

The requirements of green environmental and public health monitoring have become stricter along with greater world attention for global warming. The most common pollutants in the environment that need tightened control are volatile organic compounds (VOC). Compared to other kinds of sensors, semiconductor sensors have certain advantages,  including high sensitivity, fast response, simplicity, high reliability and low cost. In this work, ZnO and Sn-doped ZnO nanostructure materials with high surface nanosheet areas were synthesized using chemical bath deposition. The X-ray diffraction patterns  could be indexed  according to  crystallinity  mainly to a hexagonal wurzite ZnO structure. The scanning electron microscopy (SEM) results showed that in all samples, the thin films after the addition of Sn consisted of many kinds of microstructure patterns on a nanoscale, with various sheet shapes. The sensor performance characterizations showed that VOC levels as low as 3 vol% of isopropyl alcohol (IPA) and ethanol could be detected at sensitivities of 83.86% and 85.57%, respectively. The highest sensitivity of all sensors was found at an Sn doping of 1.4 at%. This high sensor sensitivity is a result of the high surface area and Sn doping, which in turn produced a higher absorption of the targeted gas.
The Power Consumption Performance of an Orbiting Screw Solid-Solid Mixer Senda, Semuel Pati; Renanto, Renanto; Roesyadi, Achmad; Sumaryono, Wahono; Bindar, Yazid
Journal of Engineering and Technological Sciences Vol 44, No 3 (2012)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (564.15 KB) | DOI: 10.5614/itbj.eng.sci.2012.44.3.6

Abstract

In this work we have investigated mixing in a modified orbiting screw mixer  (MOSM)  designed  for  solid-solid mixing.  Mixing  was  carried  out  using urea powder and natural zeolite powder (UZ) of three varying particle sizes (50-60, 60-80 and 80 mesh). Power consumption was calculated from the measured torque of orbit and screw, obtained from computerized records. It was found that the  mixing  process  in  the  modified  orbiting  screw  mixer  with  air  injection required a lower power consumption for each particle-size group when compared to mixing without air injection. With UZ mixing in MOSM with  air injection, the lowest E was obtained for  the 60-80 mesh particle-size group  (4,297 Joule/kg-1),whereas when mixing without  air injection, the value was  10,296 J/kg. The best mixing  operation in this experiment was achieved at NFr  =  1.18x10-3 and in the range  of  values  NRe≈  8.77x107 to  2.63x108.  Moreover,  in this  study,  we  have developed  an  equation  to  estimate the  power  consumption required  for  mixing and determined its correlation with dimensionless numbers.

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