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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 Ketebalan Lapisan Aktif terhadap Karakteristik Sel Surya Berbasis a-Si:H yang Ditumbuhkan dengan Teknik HWC-VHF-PECVD Ida Usman; Toto Winata
Jurnal Matematika & Sains Vol 13, No 4 (2008)
Publisher : Institut Teknologi Bandung

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Abstract

The HWC-VHF-PECVD (Hot Wire Cell Very High Frequency Plasma Enhanced Chemical Vapor Deposition) technique has been developed for silicon thin film deposition. The developed technique was also used to fabricate the hydrogenated amorphous silicon (a-Si:H) based p-i-n solar cells with varied active layer (i-layer) thickness. Based on the measurement result of current-voltage (I-V) characteristic of resulted solar cells, it is known that the conversion efficiencies are influenced by the i-layer thickness of each solar cell. In this research, the highest conversion efficiency of 9,39 % was achieved from solar cell with i-layer of 5500 Å thickness. All of solar cell parameters decrease as the ilayer thickness increases to 6000 Å, which were probably affected by the serial resistance increases that marked by the degradation of fill factor value.
Struktur Modul Hasil Bagi dari Modul Dedekind Hanni Garminia; Pudji Astuti; Irawati Irawati
Jurnal Matematika & Sains Vol 13, No 4 (2008)
Publisher : Institut Teknologi Bandung

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Abstract

It is well known that the quotient ring of a Dedekind prime ring is a Dedekind prime ring. In this article we generalize the property of Dedekind ring to a module over a commutative ring. Particularly we show that the quotient module of a Dedekind module is a Dedekind module.
Spektrum Gstar(1;1) Nunung Nurhayati; Udjianna Sekteria Pasaribu; Dudung Muhally Hakim; Oki Neswan
Jurnal Matematika & Sains Vol 13, No 4 (2008)
Publisher : Institut Teknologi Bandung

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Abstract

In this paper we formulate the spectrum (spectral density matrix) of the stationary GSTAR(1;1) model by considering the model as VMA( ∞). The spectrum can be obtained by following steps: represent the model as an VMA( ∞) and convert the model to the backward operator form, then substitute the coefficient model to the spectrum of VMA( ∞) model. The procedure of finding spectrum of GSTAR(1;1) which parameters are given, is illustrated by a two dimensional GSTAR(1;1) model.
Estimating Hyperbolic Decline Curves Parameters Sri Wahyuningsih; Sutawanir Darwis; Agus Yodi Gunawan; Kurni Permadi
Jurnal Matematika & Sains Vol 13, No 4 (2008)
Publisher : Institut Teknologi Bandung

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Abstract

The decline curve analysis refers to the estimation of some measure of well performance. The linearization of Arps hyperbolic decline curves leads to the estimation of initial value of decline exponent. This work proposes a graphical method to estimate the initial value of decline exponent and a binomial expansion to estimate the decline rate and the initial production value. The graphical approach is used to determine the initial value of the decline exponent for binomial expansion of hyperbolic Arps equations. Experimental study from some small data sets shows that our proposed method is capable in reducing the number of iterations needed in binomial linearization of hyperbolic decline curves. The main contribution of this work is a development of initial decline exponent estimation using graphical approach where the traditional approach is based on trial and error. Bias in estimating the initial values can produce large number of iterations in estimating the decline exponent. The proposed method is successfully reduce the number of iterations in estimating the decline exponent. Experimentally, this study indicates the existence of lower bound of decline exponent b* for each iteration using hyperbolic binomial expansion.  
Pengaruh Kepadatan Awal Inokulum terhadap Kualitas Kultur Chaetoceros gracilis (Schütt) pada Sistem Batch Gede Suantika; Pingkan Adityawati; Dea Indriani Astuti; Yusup Sofyan
Jurnal Matematika & Sains Vol 14, No 1 (2009)
Publisher : Institut Teknologi Bandung

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Abstract

Chaetoceros gracilis (Schütt) is a common live food used in white shrimp Litopenaeus vanamei larviculture that is commonly produced by using batch culture system. The aim of this study was to evaluate the effect of different initial densities inoculums to obtain the optimum quality of C. gracilis culture in batch culture system. Based on the result from step 1, the highest cell density of 9,85x106 ± 5,00x105 cells/mL was obtained in the culture with inoculum initial density of 1,0x105 cells/mL. At step 2, the highest cell density of 9,87 x 106 ± 2,00 x 105 cells/mL was obtained in the culture with inoculum initial density of 1,0x105 cells/mL and it was significantly (p
Penumbuhan Lapisan Tipis mc-Si:H Tipe-P dengan Metode HW-PECVD untuk Aplikasi Sel Surya Jasruddin Daud Malago; Abdul Haris; Helmi Helmi
Jurnal Matematika & Sains Vol 14, No 1 (2009)
Publisher : Institut Teknologi Bandung

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Thin film of microcrystal silicon hydrogenated (μC-Si:H) p-type has been successfully grown in a hot-wire plasma enhanced chemical vapor deposition (HW-PECVD) by using silane gas (SiH4) and diborane (B2H6) diluted in 10% H2 respectively as gas resources. The resulted thin film have optical band gap decreased from 1.88 eV to 1.50 eV as the dopant concentration increased from 0.50% to 0.20% on filament voltage of 4.5 volt and RF power of 100 watt. Dark and photo conductivities of the film were found significantly high, in the order of 10-8-10-6 Scm-1 and 10-5-10-3 Scm-1 respectively. The conductivity is two order higher than thin film a-Si:H p-type grown using PECVD technique without hot-wire. It is concluded that the thin film produced in this study is suitable for solar cell application and other microelectronic devices
Gelation Model for Porosity Dependent Fluid Permeability in Porous Materials Mikrajuddin Abdullah; Khairurrijal Khairurrijal
Jurnal Matematika & Sains Vol 14, No 1 (2009)
Publisher : Institut Teknologi Bandung

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Abstract

A statistical theory of gel formation in a polymer matrix was used to explain the dependence of liquid permeability in porous materials. A porous material was modeled as a dispersion of bubbles in a solid matrix. Bubbles were treated as monomers and formation of infinite connected bubbles was treated as the formation of gels in polymer. The theoretical predictions were in agreement with the observed data for basalt andesits. The model can easily predict the percolation threshold of porosity at which the permeability increases suddenly, which depends on the effective number of nearest bubbles around a selected bubble. Around the percolation threshold, the permeability satisfies a scaling relationship with a critical exponent of t » 1.2. It is also identified that the critical exponent and fractal dimension of pores, D, satisfy t » 0.8 (1 + 1/D).
Pengaruh Komposisi Asam Bis(2-Etilheksil)Fosfat (D2EHPA) dan Tributil Fosfat (TBP) dalam Resin Amberlite Xad-16 terhadap Sorpsion-Ion La(III), Nd(III) dan Gd(III) Ibnu Khaldun; Buchari Buchari; Muhammad Bachri Amran; Aminudin Sulaeman
Jurnal Matematika & Sains Vol 14, No 1 (2009)
Publisher : Institut Teknologi Bandung

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Abstract

Sorption of La(III), Nd(III), and Gd(III) ions with solven-timpregnated resins using bis(2-ethylhexyl)phosphoric acid (D2EHPA) and tributhylphosphate (TBP) as extractants and Amberlite XAD-16 as a polymeric support has been studied. The impregnated resins containing various amounts of extractants have been prepared by the wet and dry methods. The effects of pH, types, of extractant, extractant content (extractants/resin ratios of 10/90, 20/80, 50/50, 60/40 wt.%) and contact time on sorption of those metalic ions have been investigated by batch method. The sorption capacity of Amberlite XAD-16 resin previously prepared by the wet method with a 60/40 extractant/resin mass ratio for TBP, D2EHPA/TBP, and D2EHPA were 104.3 mg/g, 99.1 mg/g and 86.2 mg/g resin, respectively. Meanwhile, sorption capacity of Amberlite XAD-16 resin previously prepared by dry method was found to be 645 mg/g; 419.16 mg/g, and 386.9 mg/g resin, respectively. The sorption percentage of the studied metal ions was within the range of 90- 99% for TBP, D2EHPA/TBP and D2EHPA XAD-16 resins at 20/80 extractant/resin mass ratio.
Sintesis Turunan Eusiderin A dan Evaluasi Aktifitas Antimakan terhadap Hama Tanaman, Epilachna sparsa Syamsurizal Syamsurizal; Afrida Afrida
Jurnal Matematika & Sains Vol 14, No 1 (2009)
Publisher : Institut Teknologi Bandung

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Abstract

Eusiderin A(1) which isolated from bulian wood (Eusideroxylon zwagery) was converted into five congeners (2- 6) which designed on account of the clogP smaller than 1. The structures of these five compounds were determined based on their spectroscopic data including 1H- NMR, 1H-1H-COSY, and NOESY spectra and mass spectra. The antifeedant activity and the brine shrimp lethality test against Artemia salina were evaluated to demostrate that 2, 3 and 6 increased significantly the antifeedant activity than eusiderin A, while the compounds(2-6) were classified as non toxic.
Dinamika Paket Gelombang Elektron yang Menerobos Penghalang Trapesium dengan Ketebalan Nanometer Maharati Hamida; Khairurrijal Khairurrijal; Mikrajuddin Abdullah
Jurnal Matematika & Sains Vol 11, No 2 (2006)
Publisher : Institut Teknologi Bandung

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Abstract

A simulation of the dynamics of electrone wave packet tunneling through a potential barrier in a MOS (metal-oxide-semiconductor) diode was performed by solving the time-dependent Schrödinger equation using the finite difference method. The wave packet is initially located in the semiconductor layer then moves toward to the oxide layer and probably tunnels through and/or is reflected by the oxide layer. The wave packet is deformed when it reaches the oxide layer. It is found that the higher the wave packet energy, the faster the wave packet moves and the higher the probability of transmitting the wave packet for the same bias voltage. It was also found that at low energy, the increase of bias voltage does not increase significantly the probability of finding the transmitted wave packet. At high energy, however, the probability of finding the transmitted wave packet becomes higher with increasing the bias voltage.

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