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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 695 Documents
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A Singular Perturbation Problem for Steady State Conversion of Methane Oxidation in a Reverse Flow Reactor Aang Nuryaman; Agus Yodi Gunawan; Kuntjoro Adji Sidarto; Yogi Wibisono Budhi
Journal of Mathematical and Fundamental Sciences Vol. 44 No. 3 (2012)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2012.44.3.7

Abstract

The governing equations describing methane oxidation in a reverse flow reactor are given by a set of convective-diffusion equations with a nonlinear reaction term, where temperature and methane conversion are dependent variables. In this study, the process is assumed to be a one-dimensional pseudohomogeneous model and takes place with a certain reaction rate in which thewhole process ofthereactor is still workable. Thus, the reaction rate can proceed at a fixed temperature. Under these conditions, we can restrict ourselves to solving the equations for the conversion only. From the available data, it turns out that the ratio of the diffusion term to the reaction term is small. Hence, this ratio is considered as a small parameter in our model and this leads to a singular perturbation problem. Numerical difficulties will be found in the vicinity of a small parameter in front of a higher order term. Here, we present an analytical solutionby means of matched asymptotic expansions. The result shows that, up to and including the first order of approximation, the solution is in agreement with the exact and numerical solutions of the boundary value problem.
Properties of Polymer Electrolyte Membranes Prepared by Blending Sulfonated Polystyrene with Lignosulfonate Siang Tandi Gonggo; Cynthia L. Radiman; Bunbun Bundjali; I Made Arcana
Journal of Mathematical and Fundamental Sciences Vol. 44 No. 3 (2012)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2012.44.3.8

Abstract

A polymer electrolyte membrane widely used in PEMFCs and DMFCs is a perfluorosulfonated membrane (the Nafion membrane). This perfluorosulfonated membrane material exhibits good chemical stability and proton conductivity, but it is very expensive and difficult to recycle. There is a high methanol crossover in DMFCs that causes a decrease in efficiency and performance of the fuel cell, so that a polymer electrolyte membrane with a low methanol crossover is needed as a substitute for the Nafion membrane. One of the materials that can be used as a polymer electrolyte membrane is the polyblends from sulfonated polystyrene-lignosulfonate (SPS-LS). Such polyblends were prepared by casting a polymer solution and characterized as polyelectrolyte membrane for DMFCs. The SPS was prepared by sulfonation of polystyrene with acetyl sulfate as the sulfonating agent. The membranes of the SPS-LS were characterized by analysis of functional groups, mechanical properties and methanol permeability. The maximum mechanical properties of the SPS-LS membrane were observed at an LS ratio of 7.5%. However, the methanol permeability of the membrane increased with the increase of the LS ratio in the SPS-LS membranes. The properties of the membranes, especially their mechanical properties and methanol permeability, were close to that of Nafion® 117 membrane, so SPS-LS membranes have high potential for use as polymer electrolyte membrane for direct methanol fuel cells.
Estimasi Model Parametrik Komponen Feedback, Feedforward, dan Nois pada Sistem Lup Tertutup dengan Teknik Extended Least Square Harijono A. Tjokronegoro
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 1 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.1.1

Abstract

In this paper is considered a direct estimation technique of model parameters of components (subsystems) of a feedback system using an extended least squares algorithm. There are three components of system may be estimated, feedback, feedforward, and noise. It has been assumed that the system considered was linear and time invariant. A common estimation technique for closed loop system is indirect, and under assumption that only one component will be estimated while the other components in the closed loop are known. The analysis shows that the proposed technique is unnbias. In the proposed structure, one of the components in the closed loop system maybe unstable, as long as the closed loop system is stable.
Kinerja Bioreaktor Hibrid Anaerob dengan Media Batu untuk Pengolahan Air Buangan yang Mengandung Molase Mindriany Syafila; Asis H. Djajadiningrat; Marisa Handajani
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 1 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.1.2

Abstract

Anaerobic hybrid bioreactor is a combination of suspended and attached growth systems. Stone was used as the microorganism attachment media. The feeding solution was made from molasses diluted to COD concentration of 10,000, 20,000, 30,000 and 40,000 mg/L. The hydraulic detention time was 30 hours and the height ratio between suspended and attached growth system was 0.5. The result shows that the organic concentration seems to be on of the determining factors. Furthermore, since the methane production was still low enough, it seems that the process has not achieved its optimum condition for methanogenic stage.  
Computer Model Development on Contact-Stabilization Wastewater Treatment Systems Priana Sudjono; Park Sang Sook; A. Cahyo
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 1 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.1.3

Abstract

Computer model is developed to relate parameters that determine the performance of a contact-stabilization system. Based on mass and substrate balance in the system, relationships between the variables are developed, then simulations using various values of the parameters can produce trend lines indicating the behavior of a system as well as the required conditions to reach an expected performance. When the operating conditions, such as recycled sludge and wasted sludge are changed, the model demonstrates alterations of the performance consistent to the developed mathematical relationships. Additionally, the computer model shows that the results could produce further explanation on phenomena of biological processes in contact-stabilization systems.
Tinggi Maksimum Selubung Paket Gelombang Bikromatik Wuryansari Muharini Kusumawinahyu; Andonowati Andonowati
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 1 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.1.4

Abstract

Previous numerical and experimental investigations found that some envelopes of bichromatics surface water waves show deformation during their propagation along the wave tank in Hydrodinamic Laboratory. In this paper we present investigation on the maximum amplitudes of bichromatics envelopes at every position along the tank, to observe the amplification factor of a signal deformation . As we consider a signaling problem, a spatial Nonlinear Schrodinger (sp-NLS) model is used here. The profiles of waves envelope as a function of time and space are computed numerically from this model. Investigations are done for some different amplitudes and frequencies of bichromatics envelopes at wave generator to show that these two parameters affect the amplification factor and the periode of maximum amplitudes of envelopes.
A Note Concerning Hamilton Cycles in Some Classes of Grid Graphs A. N.M. Salman; E. T. Baskoro; H. J. Broersma
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 1 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.1.5

Abstract

A graph G is called hamiltonian if it contains a Hamilton cycle, i.e. a cycle containing all vertices. Deciding whether a given graph has a Hamilton cycle is an NP-complete problem. But, it is a polynomial problem within some special graph classes. In this paper we consider three classes of grid graphs, namely rectangular grid graph, eta grid graph and omega grid graph. Our main result characterizes which of these graphs are hamiltonian.
Polychromatic Source Excitable and Enhanced Green Photoluminescence of ZnO Nanoparticles Dispersed in High Molecular Weight Polymer Matrix Mikrajuddin Abdullah
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 1 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.1.6

Abstract

Composite of zinc oxide (ZnO) nanoparticles in polyethylene glycol (PEG) has been produced by mixing the as prepared ZnO colloid with a solution of PEG in ethanol. ZnO colloid was produced by hydrolizing zinc acetate in ethanol solution. The produced composite exhibits a wide band excitation spectra compared to ZnO colloid to allow the excitation using a wide range excitation wavelength for producing high green luminescence intensity. Since ZnO nanoparticles were trapped in a matrix of polymer (solid phase) no further growing as well as agglomeration process took place (as observed in ZnO colloid) so that the shape and positions of excitation and luminescence spectra were time independent. Heating the prepared composite results an increase in the luminescence intensity due the increase in the ZnO nanoparticles concentration in the heated composites.
Analisis Dinamik Tegasan Purba pada Satuan Batuan Paleogen – Neogen di Daerah Pacitan dan Sekitarnya, Provinsi Jawa Timur Ditinjau dari Studi Sesar Minor dan Kekar Tektonik C. I. Abdullah; N. A. Magetsari; H. S. Purwanto
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 2 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.2.3

Abstract

There are four trends of geological structures in the region of Pacitan and its closed surrounding, as the result of the tectonic deformation which occured during the Tertiary up to Quaternary. Those trends of geological structures are classified as fault groups in the direction of NW - SE (N3100E - N3300E), N - S (N3500E - N0100E), NE - SW (N0450E - N0500E), and E - W (N0800E). The result of the paleostress reconstruction based on the minor faults and shear fractures, point to three axis direction of principle stress: First, Early Miocene Stress with the 1 direction between 150, N1640E - 090, N1700E. The respective stress caused the formation of fault in the direction of NW - SE and fold structures. Second, Middle Miocene Stress with the 1 direction between 160, N1920E "“ 150, N1960E , which caused the formation of fault in the direction of NE - SW and N - E. Third, Plio-Pleistocene Stress with the 1 direction 140, N1980E. This latest stress caused the reactivation of the fault groups which occurred previously.
Bergenin, Suatu Dihidroisokumarin dari Kayu dan Kulit Batang Shorea Stenoptera Burck§ Euis Holisotan Hakim; Rudiyansyah Rudiyansyah; Iqbal Musthapa; Koichi Takeya
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 2 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.2.1

Abstract

Bergenin, a dihydroisocoumarin derivative of glucopyranosyl gallic acid had been isolated for the first time from ethyl acetate extracts of the heartwood and tree bark, together with (-)-α-viniferin from the tree bark of Shorea stenoptera. The structure of bergenin was elucidated based on analysis of spectroscopic data UV, IR, MS, 1H and 13C NMR. Bergenin showed weak cytotoxic activity against murine leukemia P-388 cells (IC50 >100 μg/mL), and also weak toxicity against Artemia salina shrimps (LC50 >500 μg/mL).

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