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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 689 Documents
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Direct Method Solution of 3-D Magnetotelluric Modeling Using Vector Finite Element Method Rudy Prihantoro; Doddy Sutarno; Nurhasan Nurhasan
Journal of Mathematical and Fundamental Sciences Vol. 51 No. 1 (2019)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2019.51.1.7

Abstract

As exploration is forced into more difficult areas with complex three-dimensional (3-D) structural environments, the importance of 3-D magnetotelluric (MT) modeling is essential for the correct interpretation of MT data. To reduce the complexity of the calculations introduced by 3-D models, iterative forward calculation of MT response functions is used as basis for inversion of 3-D MT data. This paper proposes an alternative procedure for making reliable 3-D MT modeling codes for forward calculation that is not only effective but also accurate. This is accomplished by using a direct method to solve the linear systems arising from the discretization process in the vector finite element approach. The vector finite element method is known for its capability of overcoming difficulties in modeling caused by possible jumps of normal components across discontinuities of material properties. Meanwhile, by using a direct method rather than an iterative method, the process of solving the linear equations does not suffer from slow convergence. Here, we present a comparison between our modeling codes and codes based on a different approach. In the resulting 3-D MT responses it was found that the proposed method has high accuracy.
Enhancing the Stability of Lanczos-type Algorithms by Embedding Interpolation and Extrapolation for the Solution of Systems of Linear Equations Maharani Maharani; Abdelah Salhi; Rifka Amelia Suharto
Journal of Mathematical and Fundamental Sciences Vol. 50 No. 2 (2018)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2018.50.2.4

Abstract

A new method to treat the inherent instability of Lanczos-type algorithms is introduced. It enables us to capture the properties of the sequence of iterates generated by a Lanczos-type algorithm by interpolating on this sequence of points. The interpolation model found is then used to generate a point that is outside the range. It is expected that this new point will link up the rest of the sequence of points generated by the Lanczos-type algorithm if breakdown does not occur. However, because we assume that the interpolation model captures the properties of the Lanczos sequence, the new point belongs to that sequence since it is generated by the model. This paper introduces the so-called Embedded Interpolation and Extrapolation Model in Lanczos-type Algorithms (EIEMLA). The model was implemented in algorithms A13/B6 and A13/B13, which are new variants of the Lanczos algorithm. Individually, these algorithms perform badly on high dimensional systems of linear equations (SLEs). However, with the embedded interpolation and extrapolation models, EIEM A13/B6 and EIEM A13/B13, a substantial improvement in the performance on SLEs with up to 105 variables can be achieved.
The Study of Effect of Toxic Metal on Plant Growth Dynamics with Time Lag: A Two-Compartment Model Preety Kalra; Pankaj Kumar
Journal of Mathematical and Fundamental Sciences Vol. 50 No. 3 (2018)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2018.50.3.2

Abstract

A two-compartment mathematical model is proposed for the study of individual plant growth dynamics with time lag due to the presence of toxic metals in the soil. It is assumed in the model that nutrient uptake by the roots is hindered by the presence of the toxic metals. It is further assumed that there is less transfer of nutrients from the root compartment to the shoot compartment due to the toxic metals. However, the nutrient concentration decreases in the root compartment as well as in the shoot compartment, resulting in a decrease of the structural dry weight of the roots and shoots respectively. This effect was studied by considering time lag in the utilization coefficient of the nutrient concentration in the roots in the presence of toxic metals. It is further assumed in the model that the nutrient use efficiency is also affected by the presence of toxic metals, resulting in a decrease of the structural dry weight of the shoots. The inclusion of time lag results in the disturbance of the interior equilibrium stability and Hopf bifurcation occurs for a critical value of the delay parameter. This entire phenomenon was captured by numerical simulation.
Tree Community Structure and Composition of a One-Hectare Permanent Plot in the Montane Zone of Mount Kerinci, Kerinci Seblat National Park, Jambi Endah Sulistyawati; Taufikurrahman Nasution; Dian Rosleine; Dian Cahyana Putra
Journal of Mathematical and Fundamental Sciences Vol. 50 No. 3 (2018)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2018.50.3.7

Abstract

Information on tree community structure and composition is needed in forest management and restoration. These data can be obtained using a permanent plot for studying forest dynamics, including species-specific characteristics. These characteristics are useful in the identification of native species for commercial and restoration purposes. This study aimed to describe the tree community structure and composition of a one-hectare permanent plot in the montane zone of Mount Kerinci. Data collection was conducted from July to August 2016 on Mount Kerinci, Jambi. A plot was established at 2,182-2,258 m above sea level and subdivided into 100 subplots. All trees ≥ 10 cm DBH were tagged and measured. Twenty-eight species, 18 genera, 20 families, 570 individuals and Shannon index 2.89 were identified. Most of the potential species richness was covered on the research site. Syzygium lineatum was the species with the highest importance value and Myrtaceae had the highest family importance level. The study area was dominated by slow growing species that characterize primary forests. The population structure indicated a good capacity of forest regeneration, while the vertical structure formed a stratification consisting of three strata. The dominant large trees and 5 hyperdominant trees according to total biomass contribution were identified. These species are an important priority in forest management and restoration. 
Multi-wavelength Fibril Dynamics and Oscillations above Sunspot-II Wave Propagation Signature Emanuel Sungging Mumpuni; Dhani Herdiwijaya; Mitra Djamal; Thomas Djamaluddin
Journal of Mathematical and Fundamental Sciences Vol. 50 No. 3 (2018)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2018.50.3.4

Abstract

In this work, the dynamics of one particular fibril were investigated through high-resolution multi-wavelength images with high cadence obtained from the Dutch Open Telescope. Based on exceptional observation data of Active Region 10789, 13th July 2005, we investigated the alternating fibril pattern using tomography of the multi-wavelength band, consisting of the hydrogen alpha line center and also the blue wing, the calcium II H line, and the G-band. Phase difference and coherence analyses were conducted for several points along the fibril and (k, ω) analysis was conducted to understand the wave interaction and its mechanism in the propagation process. Our findings suggest short- to long-period transitions along the fibril with coherence in 10-min oscillations in the penumbra.
Respective Influences of Indian Ocean Dipole and El Niño-Southern Oscillation on Indonesian Precipitation Deni Okta Lestari; Edy Sutriyono; Sabaruddin Sabaruddin; Iskhaq Iskandar
Journal of Mathematical and Fundamental Sciences Vol. 50 No. 3 (2018)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2018.50.3.3

Abstract

The respective influences of the Indian Ocean Dipole (IOD) and El Niño-Southern Oscillation (ENSO) on Indonesian precipitation were evaluated using monthly precipitation data from the Global Precipitation Climatology Centre (GPCC) for January 1948 to December 2013. Simultaneous correlation between seasonal precipitation anomalies and climate indices for these two types of climate modes revealed that IOD events have a significant correlation with the precipitation over southern Sumatra, Java, southern Kalimantan, the Nusa Tenggara Islands, some parts of Sulawesi and eastern Papua. Meanwhile, ENSO events have a significant correlation with the precipitation over southern Sumatra, Java, Kalimantan, Sulawesi, and Papua. Droughts during the dry season (JJA and SON) typically occur when a positive IOD event simultaneously occurs with an El Niño event associated with anomalous low SST observed in the Indonesian seas and the southeastern equatorial Indian Ocean. Low SST anomalies lead to low-level wind divergence and reduce water vapor in the lower atmosphere, supress atmospheric convection over the Indonesian region and then cause a decrease in precipitation.
Unexpected Dimer from Demethylization Reaction of Eugenol under Acidic Conditions Anita Alni; Meilisa Dara Puspita; Didin Mujahidin
Journal of Mathematical and Fundamental Sciences Vol. 51 No. 1 (2019)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2019.51.1.5

Abstract

Eugenol is an alkenyl phenol compound obtained as an essential oil from different parts of the clove such as its leaves and flowers. The essential oil from cloves can contain up to 90% eugenol, which is mainly responsible for its aroma. Eugenol is an interesting compound due to its simplicity and richness in functionalities, making it a valuable building block in synthesis. One of the key steps in eugenol transformation is demethylation to produce a hydroxycavicol. Demethylation is commonly carried out using a nucleophilic or an acidic method. In this study, a simple yet reliable nucleophilic method for demethylation using lithium chloride (LiCl) was attempted. The product was characterized by NMR, FTIR and HRMS spectroscopy. The absence of a methoxy signal at 3.5-4 ppm in the 1H NMR spectrum suggests that demethylation was successful. The HRMS result showed m/z 149.0596, confirming the formation of product. The demethylation reaction under acidic conditions formed a dimer of eugenol with the methoxy group still intact. This was supported by the 1H NMR data, which showed methoxy signals at 3.85 and 3.82 ppm and integration in the aromatic region, which suggests a dimer structure. 
Efficient Alternative Method for Computing Multivariate Resultant Formation Surajo Sulaiman; Noraini Aris; Shamsatun Nahar Ahmad
Journal of Mathematical and Fundamental Sciences Vol. 51 No. 1 (2019)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2019.51.1.2

Abstract

In elimination theory, the matrix method of computing resultant remains the most popular due to its less computational complexity compared to Groebner basis and set characteristics approaches. However, for a matrix method to be effective, the size and the nature of elements of the matrix play an important role, since if the resultant is not an exact resultant, it has to be  extracted from the determinant of the corresponding resultant matrix.. In this paper, a new resultant matrix is proposed. The proposed construction consists of four blocks, one of the blocks uses an entry formula of computing a Dixon matrix, while, two of the blocks use a mapping from the Jouanolou's method and the last block consists of only zero elements. The new formulation is computed without intermediate cancelling terms which reduces the complexity of the construction and enhances its effectiveness.
Flavonoid Compounds from the Herb of Krokot (Lygodium microphyllum) and their antioxidant activity against DPPH Hadi Kuncoro; Kindi Farabi; Laode Rijai; Euis Julaeha; Unang Supratman; Yoshihito Shiono
Journal of Mathematical and Fundamental Sciences Vol. 50 No. 2 (2018)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2018.50.2.7

Abstract

Six flavonoid compounds, kaempferol (1), quercetin (2), acacetin (3), quercetin-3-O-β-D-glucopyranoside (4), kaempferol-3-O-β-D-glucopyranoside (5), and isorhamnetin-3-O-β-D-glucopyranoside (6), were isolated from the methanol extract of the Lygodium microphyllum herb. The chemical structures of compounds 1-6 were identified on the basis of spectroscopic evidence and comparison with previously reported spectral data. Compounds 1-6 were isolated for first time from this plant. Their antioxidant activity against DPPH (2,2-Diphenyl-1-picrylhydrazyl) was evaluated. Among the compounds, quercetin (2) showed high antioxidant activity with IC50 values of 6.94 ± 0.03 μg/mL.
B-emission Stars in Southern Sky Observed in Bosscha Observatory: Spectroscopic Study of Hα Spectral Line Variability Aprilia Aprilia; Hakim Luthfi Malasan; Geavani Eva Ramadhania; Agus Triono Puri Jatmiko; Mochamad Irfan; Dhimaz Gilang Ramadhan; Ade Nur Istiqomah; Evan Irawan Akbar
Journal of Mathematical and Fundamental Sciences Vol. 51 No. 3 (2019)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2019.51.3.3

Abstract

Hα line variations of 8 B-emission (Be) stars are presented. Stars that are listed in the Bright Star Catalogue were observed in 2009 at the Bosscha Observatory, Lembang, Indonesia. It was found that 4 stars showed phase changing from Be double-peaked to Be single-peaked emission line profiles, 1 showed single-peaked to double-peaked profiles, 1 showed double-peaked to B-normal, while two other stars did not show phase changing. The stars also showed variations in the V/R and E/C values, which represent the strength of the emission lines. The phase changes were detected from a comparison of the observed data to the current data in the BeSS database.

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