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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 6 Documents
 1 
Search results for , issue "Vol. 37 No. 2 (2005)" : 6 Documents clear
Biodegradation of Poly(R,S)-β-hydroxybutyrate and its copolymer with δ-Valerolactone Synthesized by Aluminoxane Catalyst M. Arcana; B. Tanajaya; B. Anwar; C. L. Radiman; M. A. Sulfikar
Journal of Mathematical and Fundamental Sciences Vol. 37 No. 2 (2005)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2005.37.2.1

Abstract

Poly(R,S)-β-hydroxybutyrate (PHB) and its copolymers with δ-valerolactone were synthesized by ring-opening copolymerization of (R,S)-β-butyrolactone (β-BL) and δ-valerolactone (δ-VL) monomers in the presence of a tetraisobutyldialuminoxane catalyst. The biodegradability of these polymers by using activated sludge was studied in an aerobic medium. The objective of this work was to determine the influence of structure and crystallinity of polymers on their degree of biodegradation and initial degradation rate. It was shown that the degradation rate for bacterial P(R)-HB with 100 % (R) isotactic structure was the highest and the final biodegradation was reached around 94 % after incubation time of 35 days. Whereas the final biodegradation about 88 % was obtained for atactic P(R,S)-β-HB synthesized by using aluminoxane catalyst. The influence of the structure and crystallinity on the initial biodegradation rate were observed for the copolymers in various composition of comonomers. All these copolymers with the PHB ratio more than 10 % exhibit highly degree of biodegradation, about 85 % after 35 days of incubation time.
Studi Eksperimental Perbandingan Nilai Faktor Reduksi (φ) Profil Baja Tabung Kotak di Indonesia Nawir Rasidi
Journal of Mathematical and Fundamental Sciences Vol. 37 No. 2 (2005)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2005.37.2.5

Abstract

At present, structural designing in Indonesia uses the value of reduction factor (φ) according to LRFD-AISC regulation (Load and Resistance Factor Design – American Institute of Steel Construction). It is understood that different condition in Indonesia requires different approach, therefore this research attempted to determine a specific value of reduction factor (φ).The research observes the compression and flexural behavior of profile steel boxes (2x4) cm with length 75 cm and 65 cm for compression and flexural test, respectively. This test collects resistance data that are stress, area of steel, load and modulus of elasticity. The result of flexural test with reliability index (β) = 3 obtained the value of reduction factor of flexure φb = 0.8823 and φ = 0.5195 for compression test. Difference between this value and that of LRFD-AISC code were caused by nominal mean value-mean value ration, coefficient of variation (Ω), and the distribution used in the calculation. In addition, different reliability index of 2.5, 2, and 1.5 were also calculated for comparison. It is concluded that greater value of reduction factor (φ) could be obtained with smaller reliability index (β).
Studi Pengaruh Konsentrasi Co pada Struktur Kristal dan Respon Photoluminescence Film Tipis Ti1-xCoxO2 yang Ditumbuhkan dengan Teknik MOCVD Horasdia Saragih; Pepen Arifin; Mohamad Barmawi
Journal of Mathematical and Fundamental Sciences Vol. 37 No. 2 (2005)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2005.37.2.2

Abstract

 Ti1-xCoxO2 thin films have been deposited on Si substrate by MOCVD technique. Thin films were synthesized by a single plane orientation structure of anatase-213 at various to Co concentartions up to 5,77%. Photoluminescence emission spectra of thin films showed a maximum peak at the energy of 2.8 eV. These energies did not change when increasing Co concentration in the Ti1-xCoxO2 thin films up to 5.77%. The patterns of spectrum emission only differ on the intensity and broadness of spectra. Broading occurs towards the higher energy of 2.8 eV, while the intensities were increased with increasing of Co concentration.
Simulasi Pemohonan Listrik (Electrical Treeing) pada Isolasi Polimer dengan Menggunakan Metode Cellular Automata Suwarno Suwarno; Ronald P. Hutahean
Journal of Mathematical and Fundamental Sciences Vol. 37 No. 2 (2005)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2005.37.2.3

Abstract

Recently, polymeric insulating materials are widely used for high voltage cables. During operation, a field enhancement sites such as void and protrusion may exist in the polymeric insulation. Degradation of the insulation may occur and the so-called electrical treeing will grow. The electrical treeing appears in the polymeric insulation in the form of tree-like structure with very fine cylindrical channels similar to the trunks and branches in an actual tree. The appearance of an electrical treeing is a sign that a harmful degradation is developing in the insulation. In order to avoid the electrical treeing to occur in the polymeric insulation and for diagnosing of the condition, it is important to know the behavior of the electrical treeing and the correlation with the insulation materials. This paper reports a computer simulation results of the behavior of the electrical treeing using Cellular Automata. The simulation was done in polymeric materials with various critical electric fields. The simulation results showed that selection of polymeric insulating materials with high critical field is a very important step in the design of insulation.
Pengolahan Citra Obyek dari Balik Penghambur dengan Metoda Optik (Tapis Ruang) dan Metoda Digital (“Or Minimum”) E. Juliastuti; A. Handojo; Bambang S. P. Abednego; Moedji Raharto
Journal of Mathematical and Fundamental Sciences Vol. 37 No. 2 (2005)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2005.37.2.6

Abstract

 In this paper, optical and digital methods are combined to improve the quality of the image obtained through a scattering medium. The optical method, using simply an imaging positive lens and a small circular spatial filter, succeded in the first stage to form an observable image.Two criteria were adopted to evaluate the quality of the image in the optical method. The first is Peak Signal-to-Noise Ratio (PSNR), the second is the correlation coefficient between the original image and the processed scattered image. It was found that PSNR decreased at a larger diameter of the spatial filter. The optimum correlation coefficient (0.368) was found at a filter diameter of 1.6 mm.Next, the digital image processing was conducted using the assumption that the scattering medium always moved randomly. Involving different diameters of the spatial filter, the image was recorded with a CCD camera connected to a computer. For each diameter, the image was recorded many times, each time with a different position of the scattering medium. The images were then processed with the so-called “Or Minimumâ and the averaging method.In the “Or Minimumâ method, the gray level of the same pixel position of all images was compared to find its minimum value. The ensemble of pixels having the minimum gray level constitutes a new image. In the averaging method, the average gray level in each pixel position was computed from a number of images.It appeared that the “Or Minimumâ method yielded the best improvement in PSNR (the largest being 4.00 dB) compared to the averaging method (1.04 dB). The improvement of the correlation coefficient was up to 0.072 in the “Or Minimumâ method and 0.05 in the averaging method.
Aspek Geodetik Penegasan Batas Darat Indonesia dan Papua New Guinea: Status dan Permasalahannnya Silvester Sari Sai; Hasanuddin Z. Abidin; Sobar Sutisna
Journal of Mathematical and Fundamental Sciences Vol. 37 No. 2 (2005)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2005.37.2.4

Abstract

Technical problems of land boundary between Indonesia and Papua New Guinea are related to delimitation and demarcation process that has been done by two countries. The process did not explicitly the datum and reference frame being used in reconstructing of monuments border pursuant to the agreement of meridian in article-1 of boundary agreement of 1973. The uncertainty about the datum caused demarcation process has been done using different datum. The datums are astronomic and geodetic datum. The combination of the coordinate derives from respectively datum to reconstruct the agreement of meridian caused technical problems and implication to status of land boundary of both countries. This paper investigates about status and technical problems of land boundary between Indonesia and Papua New Guinea and its alternative solution. Investigation is done using the boundary monuments coordinate given by GPS survey of 2004 and boundary monuments coordinate pursuant to boundary agreement of 1973 and result of demarcation survey of 1983-1991. This paper is sum up with some conclusions and recommendation.

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