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INDONESIA
Jurnal Matematika & Sains
Published by Institut Teknologi Bandung
ISSN : -     EISSN : -     DOI : -
Core Subject : Education,
Mathematics
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Articles 339 Documents
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Pengaruh Korelasi Antar Respon pada Model Multinomial Logit Jaka Nugraha; Suryo Guritno; Sri Haryatmi
Jurnal Matematika & Sains Vol 14, No 3 (2009)
Publisher : Institut Teknologi Bandung

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Abstract

Model multinomial logit (MNL) disusun berdasarkan asumsi bahwa komponen erornya berdistribusi nilai ekstrim tipe I (Gumbel) dan saling independen. Dengan asumsi ini, persamaan probabilitas pada masing-masing pilihan berbentuk persamaan tertutup dan konsisten dengan utilitas acak (random utility). Telah dilakukan penyelidikan pengaruh besarnya korelasi antar respon terhadap estimator. Disimpulkan bahwa, jika terdapat korelasi antar respons, estimator maksimum likelihood pada MNL menjadi bias.
Simulation of Baroclinic Current Pattern in Eastern Indonesian Region using Three-Dimensional Model Syamsul Rizal; Ichsan Setiawan; Muhammad Muhammad; Taufiq Iskandar; Mulyadi Abdul Wahid
Jurnal Matematika & Sains Vol 14, No 4 (2009)
Publisher : Institut Teknologi Bandung

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Abstract

In this investigation, the currents in Eastern Indonesian region are simulated by using the equations of motion (Navier-Stokes Equation). These equations are solved by the Hamburg Shelf Ocean Model (HAMSOM). Two cases are carried out, i.e. in the condition of west monsoon (February 1994) and east monsoon (August 1994). The simulation results are discussed for surface current, currents at 100-200 m, and the bottom current. In general, the results obtained agrees well with the work of Wyrtki, 1961 and Ahmat et al., 1995, but less with the work of Gordon and McClean, 1999.
Studi Sifat Termal Prekursor In(TMHD)3 untuk Menumbuhkan Lapisan Tipis In2O3 dengan Teknik MOCVD Horasdia Saragih; Hasniah Aliah; Euis Sustini; Sukirno Sukirno
Jurnal Matematika & Sains Vol 14, No 4 (2009)
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Abstract

The In2O3 thin films have been deposited on quartz substrate by MOCVD technique using In(TMHD)3 as a metal organic precurcor. Thermal properties of In(TMHD)3 have been investigated by analyses of TG-DTA curve and FTIR spectrum to determine the value of In2O3 deposition parameters. Based on TG-DTA curve and FTIR spectrum analyses, we find that: (1) melting point of In(TMHD)3 powder is 175 °C; (2) In(TMHD)3 powder starts to evaporate at 184 °C; (3) partial oxidation of In(TMHD)3 in Ar/atmosfer accur at 260 °C; and (4) dissosiation of TMHD ligand from indium metal element happened in the temperature range of 300 °C - 400 °C. Following these results, we maintaned growth condition for deposition of In2O3: the temperature of In(TMHD)3 bubbler (Tb) = 200 °C; the pressure of In(TMHD)3 bubbler (Pb) = 260 Torr; the rate of argon gas flow to carry out the vapor of In(TMHD)3 = 50 sccm; the rate of oxygen gas = 50 sccm; and temperature of substrate = 300 °C. In 120 minutes, the thickness of deposited In2O3 thin films, the rate of deposition and the roughness of film surface are about 0.2 µm, 1.6x10-3 µm/menit and 70 nm, respectively.
Konversi Eugenol dan Isoeugenol menjadi 2-Metoksi-4-propilfenol melalui Reaksi Hidrogenasi Menggunakan Katalis Logam Pt, Pd, dan Ni dalam Zeolit Asep Kadarohman; Hardjono Sastrohamidjojo; Muhamad Muchalal
Jurnal Matematika & Sains Vol 14, No 4 (2009)
Publisher : Institut Teknologi Bandung

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Abstract

2-Methoxy-4-propylphenol is a subtance which could be used to synthesize 1,2-dimethoxy-4-propylbenzena, male fruit fly pheromone (Dacus dorsalis Hendel) which was 50% more effective than methyl eugenol. 2-Methoxy-4-propylphenol could be synthesized from eugenol or isoeugenol by hydrogenation due to their similar structures. This research investigated the conversion selectivity of eugenol or isoeugenol hydrogenation to 2-methoxy-4-propylphenol. The hydrogenation was conducted using various catalyst and metal concentrations of Pt, Pd, and Ni, either in a single form or in combination which was impregnated on X or Y zeolites. The products were analyzed by GC, GC-MS, and FTIR. The result indicated that eugenol was easily hydrogenated than isoeugenol. Pd/Y as a catalyst was more effective than Ni/Y, Pt/Y or combined metal (Pt,Pd,Ni)/X. The highest conversion selectivity occured in 6% catalyst of Pd(10%)/Y that produced 98.24% of 2-methoxy-4-propylphenol.
Stereoselektivitas Reaksi Aldol dalam Sintesis C1-C12 Senyawa Epotilon Muharram Muharram; Dieter Schinzer
Jurnal Matematika & Sains Vol 14, No 4 (2009)
Publisher : Institut Teknologi Bandung

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Abstract

The retrosynthesis analysis shows that the synthesis of epothilone is built from three main fragments, which are ethyl ketone 5, thiazole 3, and aldehyde 4 fragments. The three fragments are coupled by aldol reaction, esterification or macrolactonisation, and olefin-epoxide metathesis. The aldol reaction was conducted in synthesis of C1-C12 epothilone from ethyl ketone 5 and chiral aldehyde 4a with highly stereoselective (97% ee) at temperature -78 °C and used lithium diisopropylamine (LDA) as a base. The ethyl ketone was synthesized from the α-bromoester 10 and diethyl ketone 11 with a good yield in each of eight stages of reaction. The chiral aldehyde 4a was synthesized from 6-heptenoic acid 19 through  six steps reaction and Evans-Auxiliary 21.
Effects of Temperature, UV Radiation, and Soaking Time (in Drinking Water) to Histidine-Bentonite Adsorbent’s Performance Anna Permanasari
Jurnal Matematika & Sains Vol 14, No 4 (2009)
Publisher : Institut Teknologi Bandung

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Abstract

Bentonite material modified by amino acid (amino-bentonite) is a save adsorbent for drinking water management. It can be used to adsorb organic/pesticides residues from water. Amino-bentonite adsorbed organic/pesticides residue pollutants in the water effectively. Histidine-bentonite is one of amino-bentonites that has successfully synthesized, and was proven as the effective adsorbent and showed high capacity of pesticides adsorption. Effects of temperature, UV radiation, and soaking time (in drinking water) to histidine-bentonite adsorbents performance has been examined utilizing UV, FTIR, XRD , and SEM techniques. The result showed that histidine-bentonite stable in 25-30 oC range of waters temperature, unstable to UV radiation, and could not be soaked in water more than a week because of the faster bacteria growth than without histidine-bentonite it self.
Efektivitas Asam Glutamat Sebagai Inhibitor Korosi pada Baja Karbon dalam Larutan NaCl 1% Ni Ketut Ketis; Deana Wahyuningrum; Sadijah Achmad; Bunbun Bundjali
Jurnal Matematika & Sains Vol 15, No 1 (2010)
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Abstract

Corrosion towards the inner parts of oilfield pipelines is one of most disturbing problems in oil and gas industries.  Amino acid and its derivatives have potent as corrosion inhibitor, including glutamic acid, which has been studied within this research project.  The effectivity of glutamic acid as corrosion inhibitor towards carbon steel in 1% (w/v) NaCl solution saturated by CO2 has been determined utilizing Tafel method with the optimization of glutamic acid concentration, pH, and temperature of tested medium.  Glutamic acid showed the highest corrosion inhibition efficiency at room temperature (26oC), which is 48.19% at the concentration of 8 ppm in 1% NaCl solution and pH 6.5.  The presence of acetate buffer solution in the medium that was being tested and at the temperature higher than room temperature has caused glutamic acid at the concentration of 8 ppm became ineffective to be applied as corrosion inhibitor.
Eksistensi Interpolan Deret Ganda Sinusoida Endang Rusyaman; Hendra Gunawan; Asep Kuswandi Supriatna; Rustam Effendy Siregar
Jurnal Matematika & Sains Vol 15, No 1 (2010)
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This paper presents a sufficient condition for the existence of a sinusoidal double series interpolant, that is the function of the form a double Fourier sine series that passes some arbitrary points  (xi, yj, cij), with 0 < xi < 1, dan 0 < yj < 1. The proof is carried out by decomposing the matrix that contains two variables into the multiplication of two matrices each of which contains one variable only, and showing that both matrices are nonsingular.
Search for New Astronomical Site in Indonesia: II. Transparency of Tropical Atmosphere Taufiq Hidayat; Putra Mahasena; Budi Dermawan
Jurnal Matematika & Sains Vol 15, No 1 (2010)
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We present a theoretical model of atmospheric transparencies for tropical region of Indonesia in the framework of developing multi-wavelength astronomical observations. The wavelengths of interest are radio, infrared, and optical domains. Beside science objectives, sky transparencies are needed to determine the corresponding wavelength band to be optimized in the observatory design. A clear sky condition is then assumed in the model and a line-by-line radiative transfer code is used at high spectral resolution.  The results, combined with study on meteorological satellite data, are utilized to provide various information to select the best possible sites for a new astronomical observatory in Indonesia. 
Search for New Astronomical Site in Indonesia : I. Global Atmospheric Parameters Taufiq Hidayat; Putra Mahasena; Budi Dermawan
Jurnal Matematika & Sains Vol 15, No 1 (2010)
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Abstract

We present initial studies to search for the best possible sites for an astronomical observatory in Indonesia. Since the country occupies a vast geographical area, in so doing, we analyzed a number of basic atmospheric parameters based on GMS-NOAA meteorological satellite data at a low spatial resolution to identify some interesting feasible locations. The selected parameters are outgoing long wave radiation, temperature, precipitation, relative humidity, precipitable water, and wind profile, mostly available for a period of several decades. The data are averaged over 30 years to obtain a monthly average profile of Indonesian meteorological situation. The results suggest that regions of Nusa Tenggara Timur could offer promising sites and is merit to be explored further. 

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