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Journal of Mathematical and Fundamental Sciences
Published by Institut Teknologi Bandung
ISSN : 23375760     EISSN : 23385510     DOI : https://doi.org/10.5614/j.math.fund.sci.
Core Subject : Science, Education,
Astronomy Chemistry Earth & Planetary Sciences Mathematics Physics
Journal of Mathematical and Fundamental Sciences welcomes full research articles in the area of Mathematics and Natural Sciences from the following subject areas: Astronomy, Chemistry, Earth Sciences (Geodesy, Geology, Geophysics, Oceanography, Meteorology), Life Sciences (Agriculture, Biochemistry, Biology, Health, Medical, Pharmacy), Mathematics, Physics, and Statistics.
Arjuna Subject : Matematika - Matematika (Lain-Lain)
Articles 7 Documents
 1 
Search results for , issue "Vol. 38 No. 2 (2006)" : 7 Documents clear
Pelarutan Besi Selektif pada Korosi Baja Karbon dalam Larutan Buffer Asetat, Natrium Bikarbonat - CO2 Jenuh Bunbun Bundjali; N. M. Surdia; Oei Ban Liang; Bambang Ariwahjoedi
Journal of Mathematical and Fundamental Sciences Vol. 38 No. 2 (2006)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2006.38.2.5

Abstract

 This work has investigate conditions which allow pitting corrosion of carbon steel in acetate buffered test solutions of pH 3.82, 4.12, 5.12 and 6.12, 0.2 M NaOAc and standard brine solutions, all of which contains 100 mg/L sodium bicarbonate and saturated with CO2. Corrosion rates is determined by corrosion wheel and corrosion bubble tests, while surface morphology is observed by electron microscopy (SEM) and metallographic optical microscopy, whereas surface deterioration as well as corroded lattice structure of the steel is monitored through measurements by X-ray Diffraction (XRD) patterns. The X-ray Diffraction Patterns of corroded carbon steel in any of the above test solutions exhibit a decrease in relative intensity of 110 and 200 lattice planes and an increase in the 211 lattice plane. The extent of decrease of the diffracted X-ray intensities increases with the increase in the percentage of corroded carbon steel coupon weight loss. This might reflect a selective dissolution of iron atoms situated in both lattice planes. It is suspected that this observation is due to the fact that 211 lattice plane has the smallest percentage of atomic occupancy among the three, thus it might have the greatest chance to be inserted with carbon atoms which in turn gives a protective effect toward iron atoms against further dissolution. Although, the corrosion process starts from the surface phase, this experiment reveals that X-ray diffraction pattern of the three lattice planes could be employed as some sort of carbon steel corrosion indicator. Consequently, corrosion inhibitor performance could be deduced from its ability to maintain diffraction pattern of the initial carbon steel specimen.
Pengaruh Mutasi D802N pada Aktivitas Polimerase DNA Pol I ITB-1 L. Ambarsari; F. Madayanti; M. R. Moeis; Akhmaloka Akhmaloka
Journal of Mathematical and Fundamental Sciences Vol. 38 No. 2 (2006)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2006.38.2.1

Abstract

D802N mutant gene of DNA Pol I ITB-1 was constructed and expressed in Escherichia coli. The crude enzyme was characterized and compared to that the wild-type. The optimum pH and temperature of the mutant was slightly differences with those the wild-type. The optimum pH and temperature of the mutant were 9.0 and 50oC, while the wild-type were 7.4 and 65oC, respectively. The differences of the above properties were followed by decreasing of specific activities of the mutant (1.34 unit/mg protein) 2.7 times lower to that the wild-type (3.71 unit/mg protein). Meanwhile the catalytic efficiency (kcat/Km ) of the mutant decreased 2 times lower compared to that the wild-type. Mutation at D802N of DNA pol I ITB-1 caused decreasing on the mutant affinity to the substrate and thus loss activity and instability of the enzyme.
Pengukuran Medan Magnet Lemah Menggunakan Sensor Magnetik Fluxgate dengan Satu Koil Pick-Up Mitra Djamal; Rahmondia Nanda Setiadi
Journal of Mathematical and Fundamental Sciences Vol. 38 No. 2 (2006)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2006.38.2.2

Abstract

A magnetic sensor has been developed for measuring a very low magnetic field. The sensor consists of two primary coils (excitation coil) and one secondary coil (pick-up coil). Primary coil that wound at ferromagnetic core is made symmetry each other. Whereas secondary coil is wound to both of cores. Primary coil drives the core until it saturated. The generated magnetic field from excitation have the contrary direction, so if there is no external magnetic field, the magnetic field inside the secondary coil is symmetry, but if there is an external magnetic field, there will be magnetic field changes inside secondary coil. These changes will induce secondary coil, as a consequence, there will be an induction voltage that acts as signal at the ends of secondary coil. The signal is then differentiated, amplified, inserted to controlled rectifier, integrated, and amplified for the last time. From measurement results, it can be obtained that magnetic sensor can measure magnetic field in the range of measurement from -40 μT to 40 μT, with sensitivity about 346.47 mV/μT and relative error less than 4%.
Sistem Kendali Fuzzy Bertipe-2 Interval dengan Struktur Adaptif Beracuan Model Bambang Riyanto; Wakhyu Dwiono
Journal of Mathematical and Fundamental Sciences Vol. 38 No. 2 (2006)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2006.38.2.7

Abstract

Adaptive fuzzy controller is a fuzzy controller that has ability to change its parameters when the plant's operating conditions vary. In this paper, design and implementation of model reference adaptive fuzzy control are presented. Interval type-2 fuzzy logic controller with PD-like action is employed and its performance is studied. The fuzzy controller structure is applied to control an inverted pendulum. Simulation and experimental study shows that by using similar membership function, fuzzy rules and scaling, interval type-2 adaptive fuzzy logic controller provides better control system performance compared to type-1 fuzzy controller.
Studi Penumbuhan Film Tipis Ti1-xCoxO2 dengan Teknik MOCVD Menggunakan Prekursor Titanium (IV) Isopropoxide dan Tris (2,2,6,6-tetramethyl-3, 5-heptanedionato) Cobalt (III) Horasdia Saragih; Edy Supriyanto; Pepen Arifin; Mohammad Barmawi
Journal of Mathematical and Fundamental Sciences Vol. 38 No. 2 (2006)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2006.38.2.3

Abstract

The Ti1-xCoxO2 thin films have been grown by MOCVD technique using titanium (IV) isopropoxide (TTIP) and tris (2,2,6,6-tetramethyl-3, 5-heptanedionato) Cobalt (III) [Co(TMHD)3] powder precursors. The tetrahydrofuran (THF) were used as a solvent to get a Co(TMHD)3 solution. Characteristics of precursor and growth parameters were investigated. The Co concentration in thin films were varied. The room temperature ferromagnetic properties of Ti1-xCoxO2 thin films were obtained. Solubility of Co atom in TiO2 lattice were found at about 11%. The surface morphology of films are homogen and relatively smooth.
Beam Positions Optimization to Achieve Improved CT Images with Limited Data Rena Widita
Journal of Mathematical and Fundamental Sciences Vol. 38 No. 2 (2006)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2006.38.2.4

Abstract

 In radiotherapy planning, margins are used to account for the uncertainties due to internal organ and patient motion as well as set-up error. Improvement in radiotherapy treatments may be achieved by reducing the set-up uncertainty and thus treatment margins allowing a higher dose to be delivered to the target volume. It is important to be able to verify the success of the treatment by determining the position of patient and the dose deposited in the patient at each fraction. One possibility for achieving this would be to collect limited information while the patient is on the treatment couch. The aim of this study is to develop a method for determining intelligent angles to use to reconstruct an image for dose verification.A method optimizing the angles based on an objective function is required. The methods developed here are based on image correlation and projection correlation that have been investigated previously. Two optimization methods, deterministic and stochastic (simulated annealing), were also assessed. The effectiveness and practicality of each of these combinations were compared.
Pemodelan TEC Regional dari Data GPS Stasiun Tetap di Indonesia dan Sekitarnya Buldan Muslim; Hasanuddin Z. Abidin; The Houw Liong; Wedyanto Kuntjoro; Cecep Subarya; Heri Andreas; M. Gamal
Journal of Mathematical and Fundamental Sciences Vol. 38 No. 2 (2006)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2006.38.2.6

Abstract

 Ionosphere affect propagation of electromagnetic waves through it by adding a transmission delay time. In GPS positioning and navigation, ionospheric delay is largest source of error after error from Selective Availability (SA) was turned off. For GPS positioning precisely ionospheric effect must be estimated so ionospheric correction can be determinated to eliminate ionospheric effect on GPS observation. In positioning by using GPS single frequency, ionospheric correction can be obtained from GPS dual frequency receiver at reference station or model. This paper describes method of determination and modeling of regional total electron content (TEC) from continuous GPS station in Indonesia and it's around. Spatial model of TEC at certain time is estimated by using polynomial function. Diurnal variation of polynomial model coefficient at certain hour from 00.00 "“ 23.00 UT is estimated with Fourier expansion.

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