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INDONESIA
Jurnal Matematika & Sains
Published by Institut Teknologi Bandung
ISSN : -     EISSN : -     DOI : -
Core Subject : Education,
Mathematics
Arjuna Subject : -
Articles 7 Documents
 1 
Search results for , issue " Vol 8, No 2 (2003)" : 7 Documents clear
Solar Cycle Variations and its Effects on El Niño/La Niña Behaviour Iratius Radiman; Dhani Herdiwidjaja; Zadrach L. Dupe; Chatief Kunjaya; Muhammad Irfan Hakim
Jurnal Matematika & Sains Vol 8, No 2 (2003)
Publisher : Institut Teknologi Bandung

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Abstract

Variations in the Solar Cycle has been known for a long time. The Solar Cycle is observed to vary from 14 to 8 years in length. The reconstructions of the annual solar total irradiance since the beginning of Maunder Minimum (from year 1600) to year 2000 show that there are envelopes of groups sunspot numbers. The intensities delineated by the envelopes are consistent with the range of CaII brightness. The timelength of the envelopes corresponds to long term variabilities such as the Gleissberg Cycle of 88 and 124 years period. A close correlation between total irradiance and sunspot number from 1610 to 2000 is found to be 0.88. Although the work of Labitzke and van Loon has clearly shown the existence of an oscillation in many atmospheric parameters with a period in the vicinity of 11 years and a phase that is related to that of solar activity, there is reluctance to accept a relationship to the 11-year solar cycle. Therefore this study aimed to pursue the investigations further by determining the correlation coefficients to lower trophospheric layers. Our studies reveal to results, which we summarized as follows: A weak correlation at 27 month delay is found between solar activities and the El Niño/La Niña phenomena. The next El Niño/La Niña event is expected to occur from year 2002 until mid 2003. A major change in the pattern of the solar cycle since 1700 appears. The sun is seen to be more frequent in its active states over the last 100 years. The length of the cycle is becoming shorter. The solar cycles modulate from 5, 8, 12 and 25-year period obtained from its total irradiance plot. The 5-year period coincides very well within the El Niño/La Niña period of 2 to 7-year. The El Niño/La Niña phenomenon has a 10-12 month duration. Every El Niño/La Niña event is separated from 24 to 84 months duration in an irregular pattern. Every El Niño/La Niña event is unique. These conclusions are drawn after decomposing the SST Anomaly Index through applied Fourier Transform. The effect of the solar cycle variations is to generate long period harmonics in the coming El Niño/La Niña events. We expect that more variability in climate will occur in the coming decade.
Konsumsi Oksigen, Kadar Hb Darah, Dan Pertumbuhan Ikan Mas, Cyprinus carpio, Diberi Pakan Campuran Ampas Kelapa Darmadi Goenarso; Suripto Suripto; K I Susanthi
Jurnal Matematika & Sains Vol 8, No 2 (2003)
Publisher : Institut Teknologi Bandung

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Abstract

A laboratory experiment on carp (Cyprinus carpio) given a shredded coconut mixed diet has been conducted. Carp aged 4 – 5 months (n = 50; weight = 24,46-25,78 g), were kept individually in each aquarium (50x30x30 cm). The waste shredded coconut was mixed with commercial fish feed. Five concentrations (w/w) of mixed diet were given as treatment, i.e.: 30% (P30), 40% (P40), 50% (P50), and 60% (P60). Controlled fish was only given commercial feed. The experiment was done within 10 weeks with five replicates. Fish were fed twice daily as much as 10% of body weight. Measurements on oxygen consumption rate and body weight were done weekly. The fish were kept from food for 24 hours prior to measurements. The hemoglobin concentration was measured at the beginning and at the end of the experiment only. ANOVA was used for statistical tests. Results showed that the oxygen consumption rate of the treated fish was not different from the controlled fish. Relative growth rate decreased significantly. The average growth rate of fish treated with P30, P40, P50, P60, were respectively 0.042%, 0.041%, 0.031% and 0.018%. Growth rate of controlled fish was 0.104%. There was n o difference on the hemoglobin concentration measured at the end of the experiment (7.89 mg/dl) compared to the value at the start (7.91 mg/dl) of the experiment. It can be concluded that waste shredded coconut mixed diet might be used as fish feed. However, some improvements should be done on the composition of nutrition in the diet to increase the fish growth rate.
Peranan Pengelompokan Samar dalam Prediksi Kekeringan di Indonesia Berkaitan dengan ENSO dan IOD The Houw Liong; Bannu Bannu; P M Siregar
Jurnal Matematika & Sains Vol 8, No 2 (2003)
Publisher : Institut Teknologi Bandung

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Abstract

In general drought in Indonesia can be predicted from intensities of El Nino that can be defined by using time series of sea surface anomaly on Pacific Ocean (SSTA 3.4). It can be shown that when El Nino with strong intensities occur then more than 65% regions in Indonesia the precipitations are below normal (drought in Indonesia). The correlation between strong El Nino intensities and percentages of regions in Indonesia with precipitations below normal are high, but when the intensities are weak the correlations are low. In this case other phenomena such as on Indian Ocean Dipole Mode (IOD) can contribute to drought in Indonesia. Clustering of climatic regions in Indonesia based on monthly rainfall pattern using fuzzy set, fuzzy relations or Kohonen’s neural network will help to clarify drought on these regions. It can be shown that climatic regions in Indonesia can be clustered based on monthly rainfall patterns that are strongly influence by Australian monsoon which is known as North Australia Indonesian Monsoon (NAIM) and Maritime Continent (MC) which has equatorial precipitation characteristic. The climatic clustering is based on the ground that ENSO and IOD are regional atmospheric dynamic so the clustering should be based on average monthly pattern or geopotential height. The east MC and NAIM will be influence strongly by ENSO and the western MC especially south Sumatra and west Java is influence also by IOD.
Pengaruh Variasi Berat Molekul Polietilen Glikol terhadap Sifat Mekanik Poliuretan Eli Rohaeti; N M Surdia
Jurnal Matematika & Sains Vol 8, No 2 (2003)
Publisher : Institut Teknologi Bandung

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Abstract

Synthesis of polyurethane was carried out by using diisocyanate monomer, (methylene-4,4’-diphenyldiisocyanate (MDI) and polyether monomer polyethylene glycol (PEG). The synthesis of polyurethane was undertaken by varying the molecular weight of PEG. The effect of molecular weight of PEG on the mechanical properties of polyurethane was observed. The variation of molecular weight of PEG was 200, 400, and 1000. Polymerization reaction was carried out at room temperature with a mol ratio of MDI to PEG was 1.17. The mechanical properties of polyurethane were characterized using AGS-500D Shimadzu tensile testing machine, with a cross head speed of 50 mm/minutes. The tensile test showed that increasing molecular weight of PEG used in the synthesis of polyurethane resulted in decreasing of the tensile strength at break of polyurethane, and increasing of elongation at break. The elasticity modulus was 92.21 kPa for polyurethane based on PEG 200; 8.96 kPa for polyurethane based on PEG 400; and 0.27 kPa for polyurethane based on PEG 1000.
Penggunaan Enzim Selulase-Hemiselulase pada Proses Deinking Kertas Koran Bekas Jenni Rismijana; Iin Naomi Indriani; Tutus Pitriyani
Jurnal Matematika & Sains Vol 8, No 2 (2003)
Publisher : Institut Teknologi Bandung

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Abstract

Deinking process of old newspaper by using cellulase-hemicellulase has been done. The old newspaper was beated, then at 4 % consistency, pH 5, and temperature 400 C, an enzyme was added with the dosage of 0,05-1,5 %. After reacting for 60 minutes the mixture was diluted and collector was added to catch the ink particles and then followed float for 20 minutes. The floating particle was scraped and the fibre was washed with fresh water until neutral pH and made as a sheet with 55 g/m2 grammage. A part of the fibre was bleached with peroxide before made as a sheet The optical and the physical properties including a dirt count, brightness, opacity, tensile index, tear index and elongation were tested. The experiment results showed the increase in the optical and the physical properties from the deinking sheet product. After bleaching process the optical properties increased, but the physical properties tended to decrease. The use of enzyme at 1% dosage gave the best result. The 0,05% enzyme dosage for the unbleached deiked pulp and 0,5% enzyme dosage for the bleached deiked pulp was able to fulfil the terms specification of newspaper according to SNI 14-0091-1998.
Magnetic, Mössbauer, and Electronic Spectral Properties of Bis(1,2,4-triazole)triazolatoiron(II) Trifluoromethanesulphonate Monohydrate Kristian H Sugiyarto
Jurnal Matematika & Sains Vol 8, No 2 (2003)
Publisher : Institut Teknologi Bandung

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Abstract

Salt of [Fe(trzH)2(trz)][CF3SO3].H2O (where trzH = 1,2,4- triazole, and trz = triazolato, that is deprotonated 1,2,4-triazole anion) has been successfully isolated as white powder. Its magnetic, Mössbauer and electronic spectral properties are temperature dependent and reveal that the salt exhibits thermally spin state, singlet 1A1g ( .s)lquintet 5T2g (h.s), transition in iron(II). The transition is relatively abrupt, incomplete down to ~ 89 K and without hysteresis. The room-temperature electronic spectrum of the salt reveals a high-spin ligand field band which is split into two at about 11000 cm-1 and 13000 cm-1. At low temperature, the intensity of the high-spin ligand field band is reduced significantly and a strong low-spin ligand field band appears at about 18500 cm-1. The change in pattern of the spectrum is associated with the thermochromic behaviour, being white at room temperature but violet at the low one. The X-ray diffractogram suggests that the salt be isostructure to the corresponding hexafluorophosphate salt, [Fe(trzH)2(trz)][PF6], which is also white and high-spin at room temperature but pink-violet and low-spin at the low one.
Perubahan Bentuk pada Perambatan Signal Bi-kromatik dan Pengaruhnya terhadap Amplitudo Maksimum Marwan Marwan; Andonowati Andonowati
Jurnal Matematika & Sains Vol 8, No 2 (2003)
Publisher : Institut Teknologi Bandung

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Abstract

We consider the signal propagation from a wave generation often simulated in hydrodynamic laboratories. As a particular case, we will study a deformation from the evolution of a bi-chromatic signal. The signal is a superposition of two mono-chromatics with different of frequencies. We use a KdV equation with exact dispersion as a model for uni-directional surface gravity waves. Using a direct expansion in the form of power series of the elevation signal amplitude gives a result to resonance in the third order. We correct this expansion using a modified Linstead-Poincare technique. From this, a non linear dispersion relating the wave number, amplitude and frequency can be derived. If the frequency different between the two mono-chromatics forming the bi-chromatics signal is small then the effect of third order side bands can dominate the second order terms. The coefficient of these terms contain an expression in the form of ()2/κqq. Deformations of bi-chromatic signal are significantly effected by this non linear dispersion as well as the side band terms. In this paper we will study the deformation of bi-chromatic signal propagation through the new approach called Maximal Temporal Amplitude (MTA).

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