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INDONESIA
Jurnal Matematika & Sains
Published by Institut Teknologi Bandung
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Core Subject : Education,
Mathematics
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Articles 339 Documents
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Geometri Bintang Berotasi Pada Keadaan Ambang Iwan Setiawan; Muhammad Farchani Rosyid
Jurnal Matematika & Sains Vol 15, No 3 (2010)
Publisher : Institut Teknologi Bandung

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Abstract

The mechanical equilibrium configuration of rotating stars is discussed through Roche model. In our study, the stars are assumed to rotate rigidly, while their geometry are determined by the use of their equipotential surfaces. The critical state is achieved by a rotating star, when its total gravitational force vanishes. There are two posibilities for a star to be in its critical state: either its effective gravitational force vanishes or it exceeds the Eddington limit. The meridional section of rotating stars of various masses and angular velocity are determined.
Perbandingan Hasil Atenuasi Tomografi 3D Menggunakan Metoda Spectral Fitting & Spectral Ratio Dalam Usaha Pemetaan Bawah Permukaan (Studi Kasus Gunung Guntur) Awali Priyono; Gede Suantika; Sri Widiyantoro
Jurnal Matematika & Sains Vol 15, No 3 (2010)
Publisher : Institut Teknologi Bandung

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Abstract

Spectral fitting and spectral ratio methods are tested to estimate the Q value or attenuation in the effort on imaging the subsurface structure using three-dimensional tomographic inversion techniques. In this study, we used microearthquakes data around Mount Guntur that was collected from 1995 until 2007 that consist of 4800 seismograms. Analyses using the spectral fitting and spectral ratio methods generally depict the same anomalous areas. Studies using P and S waves indicate that the area of high attenuation corresponds to the area of low velocity that extending from mount Guntur to Kamojang caldera. In terms of the image quality, it can be seen that the attenuation derived using the spectral ratio of S wave has the same pattern with the one derived using P wave. This is due to the attenuation of S wave, which was derived directly from the P-wave. The Q value in the spectral ratio method depends on the width of the frequency window taken and the effect of noise in the determination the slope of the linear relationship between the natural logarithm of spectral ratio with frequency. The result of the spectral fitting analysis shows that the pattern of S wave attenuation image is different from the pattern inferred from the P wave data, because each attenuation image has been determined separately and does not depend on each other. Since the sensitivity of the values of Qp and Qs are important in fluid rock identification, the determination of Qs should not depend directly on Qp. With the various reasons above and more influential factor in estimating the value of Q using spectral ratio, the spectral fitting method is more recommendable to be employed to determine the value of Q.
A New Method for Dual Fully Fuzzy Linear Systems by use LU Factorizations of the Coefficient Matrix Mashadi Mashadi
Jurnal Matematika & Sains Vol 15, No 3 (2010)
Publisher : Institut Teknologi Bandung

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Abstract

In this paper we will discuss an alternative way to solve dual fully fuzzy linear system of the form . Next we crisp coefficient matrix  and  through form LU factorizations and we will construct a simple algorithm for the solution of these system. Finally we will illustrate our method by solving some examples.
Electrical Characteristics and Annealing Effect on Al/n-GaSb Schottky Diode Doped Using DMTe Ari Handono Ramelan; Harjana Harjana; Pepen Arifin; Ewa Goldys
Jurnal Matematika & Sains Vol 15, No 3 (2010)
Publisher : Institut Teknologi Bandung

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Abstract

The electrical properties of Al/n-GaSb Schottky diodes, doped with 1.4 × 1018 cm−3 (tellurium) were examined.  C-V (capacitance-voltage) measurements at 300 K show barrier heights of 0.63 eV, compared to 0.59 eV determined from room temperature I-V (current-voltage)  measurements. The voltage and frequency dependence on the capacitance is due to the ideality factor of the Schottky barrier and due to a high series resistance.  At low frequency the measured capacitance is dominated by the depletion capacitance of the Al/n-GaSb Schottky diode which is bias-dependent and frequency-dependent. The diode shows a strong temperature dependence of ideality factor from approximately 3.6 at room temperature to as high as 6.7 at 140 K.  There may be a small portion of the device nonideality attributable to generation-recombination currents due to deep levels in GaSb. The barrier height decreased from 0.57 eV to 0.35 eV for the sample annealed at 300oC for 1 minute.
Pengaruh Gangguan pada Perubahan Prioritas dan Indeks Konsistensi Matriks Perbandingan Berpasangan dalam Analytical Hierarchy Process Hanni Garminia; Moh. Hafiyusholeh; Pudji Astuti
Jurnal Matematika & Sains Vol 15, No 3 (2010)
Publisher : Institut Teknologi Bandung

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A pairwise comparison matrix (PCM) is a matrix arising in Analytical Hierarchy Process (AHP). The application of the AHP as a decision problem tool gives rise to pairwise comparison matrices (PCM). In this work we investigate sufficient conditions on the disturbance which results in reversal of the rank order of the decision alternatives while the PCM  remains consistent.
New Extremal Self-dual Codes of Length 36 Djoko Suprijanto; Bagus Ilman
Jurnal Matematika & Sains Vol 15, No 3 (2010)
Publisher : Institut Teknologi Bandung

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A paper of Conway and Sloane (1990) gives the putative weight enumerators of extremal self-dual codes for length n £ 64 and n = 72. The construction of such codes with putative weight enumerator has been one of the fundamental problems in Coding Theory. In this paper, we construct new extremal binary self-dual codes of length 36. We show that there are at least 17 inequivalent extremal binary self-dual codes of parameter  [36, 18, 8]. Our invention upgrades the previous known result provided by Conway and Sloane (1990), Harada (1999), and Kim (2001).
Influence of Artocarpus communis Leave Extract on the Physical Characteristic of Pellet Heni Rachmawati; Tjandrawati Mozef; Shafiqah Adam
Jurnal Matematika & Sains Vol 15, No 3 (2010)
Publisher : Institut Teknologi Bandung

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Abstract

Artocarpus communis (Forst.) is popularly known in English as breadfruit tree because of the bread-like texture of its edible fruits. The leaves are potential for fever and liver disorders and it also possesses significant anti-platelet and anti-inflammatory activities. The aim of this study is to formulate ethyl acetate extract of Artocarpus communis leaves into a solid dosage form. Pelletization was developed to formulate the extract. The formula was prepared using various ratios of extract (5, 10, 15 and 20 %) with PVP as a binder and Avicel pH101 as a filler. The influence of extract concentration was studied on the pellet characteristics. Pellet was prepared by extrusion-spheronization technique. In order to produce pellet with optimum diameter (500-900 µm), the moisture of the extrudates must be around 40%, with spheronizer speed of 800-900 rpm for 1.5 minutes. In particular for flow property, all pellets containing more than 5% of Artocarpus communis leaf extract were better (> 8 g/s) over blank pellets (< 4 g/s). In conclusion, the presence of extract in the pellet formulas improved the physical characteristic of pellet. The self binding property of the extract is suggested as a key parameter for this improvement.
Isomerisasi Linoleat dalam Minyak Jarak Hasil Dehidrasi Menjadi Linoleat Terkonjugasi dan Pemisahannya dengan Kromatografi Kolom Fasa Diam Silika Gel yang Diimpregnasi Perak Nitrat Marham Sitorus; Sanusi Ibrahim; Hazli Nurdin; Djaswir Darwis
Jurnal Matematika & Sains Vol 16, No 1 (2011)
Publisher : Institut Teknologi Bandung

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The main component of dehydrated castor oil (DCO) is linoleic and conjugated linoleic acid (CLA) as triglyseride forms.  This research aim is to find out suitable method for linoleic isomerization of DCO into CLA. Isomerization method must be made chemoselective in order to prevent safonification and transesterification. Isomerization method with 2M NaOH in n-butanol, 1% KOH (w/v) without solvent and irradiated by microwave with iodine as an initiator were tested respectively. CLA was seperated by using column chromatography that AgNO3 impregnated silica gel as a stationary phase. Seperation was based on the differences of coordination bond strenght between the double bond and silver ion. Its  the more unsaturation and trans isomer the more srongly the molecule is retained. Gradient elution was carried out by various ratio of hexane and acetone (v/v) e. g : 97.5 : 2.5, 95 : 5, 90 : 10, 80 : 20, 70 : 30 and  60: 40 with  8 x 5 mL. Each of fraction was analyzed by using TLC and the spot detection was made by UV lamp. The results was  analyzed by using GC, FTIR, UV and GC - MS and Its compared with the standard data. The best isomerization  was  conducted  by microwave irradiated using iodine as an initiator with a conversion factor of 1.97 %.  Seperation of CLA could be made by column chromatography that AgNO3 impregnated silica gel as a stationary phase. The best result  was conducted by eluting with 95: 5 (v/v) of hexane-acetone. The compositions of seperated  were:  0,91% (9c-2c) linoleic, 43.59% (9c/t-12t/c) linoleic, 18.58% (9c/t-1t/c)CLA, 3.46% (9t-11t) linoleic, 19.19%(9t- 1t) CLA and 0.86% ricinoleic.  The ratio of CLA : linoleic prepared was  0.77 : 1 or 70, 32 % compared to the standar with the proportions of 1.45:1.
Sintesis dan Penentuan Sifat Feroelektrik Senyawa Oksida Logam Berstruktur Aurivillius Pb2Bi3Ti3,5W0,5O15 Edi Mikrianto; Dwi Rasy Mujiyanti; Taufiqurohman Taufiqurohman
Jurnal Matematika & Sains Vol 16, No 1 (2011)
Publisher : Institut Teknologi Bandung

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Abstract

Senyawa oksida logam berstruktur Aurivillius Pb2Bi3Ti3,5W0,5O15 (PBTW) telah disintesis pada kisaran suhu 900 - 950 oC dengan metode reaksi fasa padat. Difraktogram hasil analisis XRD dibandingkan dengan database PDF (Powder Diffraction File) menggunakan Program Phasanx dan penelusuran difraksi menggunakan program Rietica dengan metode Rietveld. Hasil penelitian menunjukkan bahwa parameter sel oksida Aurivillius PBTW yaitu a = 5,2453 Å; b = 5,5363 Å; c = 41,6342 Å dengan grup ruang A21am dan sistem kristal ortorombik. Berdasarkan hasil pengukuran sifat feroelektrik didapatkan bahwa senyawa hasil sintesis dari oksida logam berstruktur Aurivillius tipe PBTW menunjukkan adanya pola histerisis. Nilai polarisasi remanen Pr(+) oksida Aurivillius tipe PBTW sebesar 12,4 C/cm2, dengan nilai Kef dan kapansitansinya 423.132 dan 489,788 nF.
30–75-day Sea Level Variations in The Equatorial Indian Ocean as Observed by Satellite Altimeter Iskhaq Iskandar
Jurnal Matematika & Sains Vol 16, No 1 (2011)
Publisher : Institut Teknologi Bandung

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Abstract

Basin-wide structure of intraseasonal sea level variations in the equatorial Indian Ocean is investigated using satellite altimeter data. The spectral analysis reveals that the intraseasonal sea level variations are dominated by the 30-75-day oscillations. The spatial amplitude structures of the intraseasonal sea level inferred from the complex empirical orthogonal function (CEOF) analysis show a typical structure of equatorial Kelvin and off-equatorial Rossby waves. Moreover, the spatial phase structures of the CEOF mode reveal eastward propagating signal. The estimated phase speed does not correspond exactly to that of one particular baroclinic modes though it falls within the range expected for the first three baroclinic modes in the Indian Ocean. This may suggest that the propagating signals do not involve a single baroclinic mode, but instead the first, second and possibly higher baroclinic modes.

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