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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
 67   68   69   70   71 
H∞ Estimation Approach to Active Noise Control: Theory, Algorithm and Real-Time Implementation Bambang Riyanto
Journal of Engineering and Technological Sciences Vol. 35 No. 2 (2003)
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.2003.35.2.5

Abstract

This paper presents an H∞ estimation approach to active control of acoustic noise inside an enclosure. It is shown how H∞ filter theory and algorithm can be effectively applied to active noise control to provide important robustness property. Real-time implementation of the algorithm is performed on Digital Signal Processor. Experimental comparison to conventional FxLMS algorithm for active noise control is presented for both single channel and multichannel cases. While providing some new results, this paper also serves as a brief review on H∞ filter theory and on active noise control.
A Low-Dimensional Model for the Maximal Amplification Factor of Bichromatic Wave Groups W. N. Tan; Andonowati Andonowati
Journal of Engineering and Technological Sciences Vol. 35 No. 2 (2003)
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.2003.35.2.4

Abstract

We consider a low-dimensional model derived from the nonlinear-Schrödinger equation that describes the evolution of a special class of surface gravity wave groups, namely bichromatic waves. The model takes only two modes into account, namely the primary mode and the third order mode which is known to be most relevant for bichromatic waves with small frequency difference. Given an initial condition, an analytical expression for the maximal amplitude of the evolution of this initial wave group according to the model can be readily obtained. The aim of this investigation is to predict the amplification factor defined as the quotient between the maximal amplitude over all time & space and the initial maximal amplitude. Although this is a problem of general interest, as a case study, initial conditions in the form of a bichromatic wave group are taken. Using the low dimensional model it is found that the least upper bound of the maximal amplification factor for this bichromatic wave group is √2. To validate the analytical results of this model, a numerical simulation on the full model is also performed. As can be expected, good agreement is observed between analytical and numerical solutions for a certain range of parameters; when the initial amplitude is not too large, or when the difference of frequency is not too small. The results are relevant and motivated for the generation of waves in hydrodynamic laboratories.
Structure Refinement of Five Layers Aurivillius Compound: Ba4Bi2Nb2Ti3O18 Ismunandar Ismu; Edi Mikrianto
Journal of Engineering and Technological Sciences Vol. 36 No. 1 (2004)
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.2004.36.1.4

Abstract

The room temperature structures of the five layers Aurivillius phase Ba4Bi2Nb2Ti3O18 has been refined from X-ray powder diffraction data using the Rietveld method. The structures consist of [Bi2O2]2+ layers interleaved with perovskite-like [Ba4Nb2Ti3O16]2- blocks. The oxides was found to be orthorhombic (SG B2cb); a = 5.5017(8), b = 5.5031(8), c = 50.363(3) Ã…, Rp = 25.53 Rwp = 35.54 Rexp = 29.30 RBragg = 9.92. The structural features of the compound is found similar to that of other layered Aurivillius compounds. Using the available structural data the ferroelectric properties could be explained and strategies to find good ferroelectric materials could be inferred.
Controller Reduction of Parameter Dependent Systems Widowati Widowati; Bambang Riyanto; Roberd Saragih
Journal of Engineering and Technological Sciences Vol. 36 No. 1 (2004)
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.2004.36.1.3

Abstract

This paper proposes a controller reduction of linear parameter dependent systems. A measure of the degradation is derived for the parameter dependent closed-loop performance caused by applying the reduced-order parameter dependent controller. This measure can be obtained by extending the degradation of the closed-loop performance of the balanced truncation of the corresponding time invariant systems. To verify the performance of the reduced-order controller, an application of the proposed controller reduction method to vertical acceleration of a missile is presented.
Development of a Chirp Stimulus PC-Based Auditory Brainstem Response Audiometer Ali Al-Afsaa; Soegijardjo Soegijoko
Journal of Engineering and Technological Sciences Vol. 36 No. 1 (2004)
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.2004.36.1.6

Abstract

Hearing losses during infancy and childhood have many negative future effects and impacts on the child life and productivity. The earlier detection of hearing losses, the earlier medical intervention and then the greater benefit of remediation will be. During this research a PC-based audiometer is designed and, currently, the audiometer prototype is in its final development steps. It is based on the auditory brainstem response (ABR) method. Chirp stimuli instead of traditional click stimuli will be used to invoke the ABR signal. The stimulus is designed to synchronize the hair cells movement when it spreads out over the cochlea. In addition to the available hardware utilization (PC and PCI board), the efforts confined to design and implement a hardware prototype and to develop a software package that enables the system to behave as ABR audiometer. By using such a method and chirp stimulus, it is expected to be able to detect hearing impairment (sensorineural) in the first few days of the life and conduct hearing test at low frequency of stimulus. Currently, the intended chirp stimulus has been successfully generated and the implemented module is able to amplify a signal (on the order of ABR signal) to a recordable level. Moreover, a NI-DAQ data acquisition board has been chosen to implement the PC-prototype interface.
Filtered-X Radial Basis Function Neural Networks for Active Noise Control Bambang Riyanto; Lazuardi Anggono; Kenko Uchida
Journal of Engineering and Technological Sciences Vol. 36 No. 1 (2004)
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.2004.36.1.2

Abstract

This paper presents active control of acoustic noise using radial basis function (RBF) networks and its digital signal processor (DSP) real-time implementation. The neural control system consists of two stages: first, identification (modeling) of secondary path of the active noise control using RBF networks and its learning algorithm, and secondly neural control of primary path based on neural model obtained in the first stage. A tapped delay line is introduced in front of controller neural, and another tapped delay line is inserted between controller neural networks and model neural networks. A new algorithm referred to as Filtered X-RBF is proposed to account for secondary path effects of the control system arising in active noise control. The resulting algorithm turns out to be the filtered-X version of the standard RBF learning algorithm. We address centralized and decentralized controller configurations and their DSP implementation is carried out. Effectiveness of the neural controller is demonstrated by applying the algorithm to active noise control within a 3 dimension enclosure to generate quiet zones around error microphones. Results of the real-time experiments show that 10-23 dB noise attenuation is produced with moderate transient response.
Experimental Study on the Sensitive Emission Lines Intensities of Metal Samples Using Laser Ablation Technique and Its Comparison to Arc Discharge Technique Eko Susilowati; Tjung Jie Lie; Hendrik Kurniawan
Journal of Engineering and Technological Sciences Vol. 36 No. 1 (2004)
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.2004.36.1.1

Abstract

An experimental study has been carried out to measure the sensitive emission lines intensities of several metal samples (copper, zinc, silver, gold, gallium, nickel, silicone and iron) using laser ablation technique conducted in low pressure surrounding gas by means of Laser Induced Shock Wave Plasma Spectroscopy (LISPS) and in atmospheric pressure region using Laser Induced Breakdown Spectroscopy (LIBS). In both cases the Nd-YAG laser was operated at its fundamental wavelength of 1.064 nm with pulse duration of 8 ns and its intensity tightly focused on the metal samples in helium or air as an ambient gas. The laser energy was fixed at approximately 100 mJ using a set of neutral density filters placed tilted in front of the laser output window. The result of the intensity measurements showed a good agreement which those obtained using arc discharge technique as shown in Massachusetts Institute of Technology Wavelength Table. Further evaluation of these results on the basis of standard deviation leads to the conclusion that LISPS is more favorable for quantitative analysis compared to LIBS. It was further shown that replacing air by helium gas at low pressure improve to some extent the LISPS reproducibility and sensitivity.
Synthesis of Narrow Polydispersity Block Copolymers of PtBA-PS by Novel RAFT Polymerization Technique M. Arcana; K. Nagesh; Ramakrisnan Rama
Journal of Engineering and Technological Sciences Vol. 36 No. 1 (2004)
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.2004.36.1.5

Abstract

The synthesis of narrow disperse polystyrene (PS) and poly-t-butylacrylate (PtBA) was carried out by copolymerization using benzyldithiobenzoate as the chain transfer agent (CTA). Benzyl dithiobenzoate as a reversible addition-fragmentation chain transfer (RAFT) agent has high transfer coefficient in polymerization of styrene to produce PS with higher molecular weight than that of calculated, in contrary with polymerization of t-butylacrylate to produce PtBA. These results were attributed to instability the benzyl dithiobenzoate as RAFT agent under the reaction conditions. PS as a macro-CTA is not active for t-butylacrylate polymerization due to low transfer coefficient. On the other hand PtBA as the macro-CTA is active to polymerize styrene to produce PtBA-PS block copolymer with high transfer coefficient if PtBA as macro-CTA have narrow polydispersity. The RAFT agent appears to degrade over a period of time when it is left at room temperature, which was evident from the results of PtBA.
Simple Fabrication of Carbon Nanotubes from Ethanol using an Ultrasonic Spray Pyrolysis Mikrajuddin Abdullah; Ferry Iskandar; Kikuo Okuyama
Journal of Engineering and Technological Sciences Vol. 36 No. 2 (2004)
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.2004.36.2.3

Abstract

Carbon nanotubes of diameter (20"“100 nm) are synthesized by pyrolyzing a sprayed solution of Fe(C5H5)2 and C2H5OH in an Ar atmosphere at relatively low temperatures (around 800 oC). The tubular structures consist of highly crystalline nested graphene cylinders (<200 concentric tubes). Tube diameter can be controlled by varying the furnace temperature, carrier gas flow rate and the Fe:C ratio within the precursor solution. This low cost route for the synthesis of carbon nanotubes is advantageous due the low pyrolytic temperature, safety, processable in atmospheric pressure, and scalable.
Zinc Oxide Nanoparticles Prepared By a Simple Heating: Effect of Polymer Addition and Polymer Absence on the Morphology Mikrajuddin Abdullah; Kikuo Okuyama
Journal of Engineering and Technological Sciences Vol. 36 No. 2 (2004)
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.2004.36.2.5

Abstract

Zinc oxide (ZnO) nanoparticles were prepared by a simple heating of precursors in a furnace at temperatures of below 1000°C in an air environment. If zinc nitrate was used as precursor, polymer (e.g., polyethylene glycol (PEG)) must be added into the precursor to produce ZnO in nanometer size. The absence of polymer led to the presence of several micrometer-sized flakes. In addition, the heating temperatures must be higher than 500°C to completely decompose the organic material in final product. However, if zinc acetate was used as precursor, nanometer-sized ZnO having a high crystallinity can be obtained even when the polymer was absent. Interestingly, we also found that heating at low temperatures (e.g. 400°C) resulted in ZnO nanorods with an elongation ratio of around 5. This method is rapid, economically efficient, and readily scalable for industrial applications.

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