Journal of Mathematical and Fundamental Sciences <p><img class="imgdesc" src="" alt="" width="173" height="220" /></p> <p style="text-align: justify;"><em>Journal of Mathematical and Fundamental Sciences </em>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. New submissions of mathematics articles starting in January 2020 are required to focus on applied mathematics with real relevance to the field of natural sciences.</p> <p style="text-align: justify;">Starting from Vol. 1, No. 1, 1961, full articles published are available online at ITB Journals and indexed by <a href=";origin=recordpage">Scopus</a>, <a href=";ISSN=2337-5760">Web of Science (Emerging Sources Citation Index) - Clarivate Analytics</a>, <a href=";tip=sid&amp;clean=0">Scimago JR</a>, <a href="">Directory of Open Access Journals (DOAJ)</a>, <a href=";user=xdqQsgUAAAAJ&amp;view_op=list_works&amp;sortby=pubdate">Google Scholar</a>, <a href=",p24780956,3.html">Index Copernicus</a>, <a href=";colors=7&amp;lang=en&amp;jq_type1=QS&amp;jq_term1=journal+of+mathematical+and+fundamental+sciences">The Elektronische Zeitschriftenbibliothek (EZB) by University Library of Regensburg</a>, <a href=";Find=Journal+of+Mathematical+fundamental+Sciences&amp;GetResourcesBy=QuickSearch&amp;resourceTypeName=allTitles&amp;resourceType=&amp;radioButtonChanged=">EBSCO Open Science Directory</a>, <a href="">ASEAN Citation Index</a>, <a href="">Garba Rujukan Digital (Garuda)</a> and <a href="">Science and Technology Index (SINTA)</a>.</p> <p style="text-align: justify;">The journal has been also accredited for five years based on The Decree of Directorate General of Research and Development Strengthening, Ministry of Research, Technology and Higher Education of the Republic of Indonesia <a href="">No. 030/E/KPT/2018</a>, dated on October 24th, 2018.</p> <p style="text-align: justify;">Published by Institute for Research and Community Services, Institut Teknologi Bandung, in collaboration with <a href="">Indonesian Chemical Society (Himpunan Kimia Indonesia - HKI)</a>.</p> <p>ISSN: 2337-5760; E-ISSN: 2338-5510</p> <p><strong><u>Publication History</u></strong></p> <p><strong>Formerly known as:</strong></p> <ul> <li>ITB Journal of Science (2008 - 2012)</li> <li>Proceedings ITB Science and Technology (2003 - 2007)</li> <li>Proceedings ITB (1961 - 2002)</li> </ul> <p>Back issues also can be read online at</p> <p><a title="SCImago Journal &amp; Country Rank" href=";tip=sid&amp;exact=no"><img src=";title=true" alt="SCImago Journal &amp; Country Rank" border="0" /></a></p> en-US (Prof. Dr. A. Agung Nugroho) (Muhamad Abdurachman Saleh) Fri, 01 Apr 2022 00:00:00 +0700 OJS 60 Dielectric Meta-lattices with Tunable Reflectivity <p class="Abstract">We report a study on the reflective performance of a dielectric meta-lattice formed by a one-dimensional periodic arrangement of silicon nanotubes. It was found that switching from transparent state to reflective state can be done by simply varying one optical parameter of the meta-lattice. The meta-lattice was shown to be capable of providing near-zero and near-unity reflectance at any desired wavelength, even in oblique incidence cases. The results are thus very promising for the development of future optical devices.</p> Suhandoko Dwi Isro, Agoes Soehianie, Alexander Agustinus Iskandar Copyright (c) 2022 Journal of Mathematical and Fundamental Sciences Mon, 28 Feb 2022 00:00:00 +0700 Analytical Solution for Bending and Free Vibrations of an Orthotropic Nanoplate based on the New Modified Couple Stress Theory and the Third-order Plate Theory <p>In the present work, the equations of motion of a thin orthotropic nanoplate were obtained based on the new modified couple stress theory and the third-order shear deformation plate theory. The nanoplate was considered as a size-dependent orthotropic plate. The governing equations were derived using the dynamic version of Hamilton’s principle and natural boundary conditions were formulated. An analytical solution in the form of a double Fourier series was obtained for a simply supported rectangular nanoplate. The eigenvalue problem was set and solved. It was analytically shown that the displacements of the median surface points in the plane of the plate do not depend on the material length scale parameters in the same directions; these in-plane directional displacements depend on the material length scale parameter in the out-of-plane direction only. On the other hand, the out-of-plane directional displacement depends on the length scale parameter in the plane directions only. The cross-section rotation angles depend on all length scale parameters. It was shown that the size-dependent parameters only have a noticeable effect on the deformed state of the plate if their order is not less than the order (<em>plate height</em>)<sup>-1</sup>.</p> Marina Barulina, Dmitry Kondratov, Sofia Galkina, Olga Markelova Copyright (c) 2022 Journal of Mathematical and Fundamental Sciences Mon, 28 Feb 2022 00:00:00 +0700 Prediction of Carbon Monoxide Concentration with Variation of Support Vector Regression Kernel Parameter Value <p lang="en-US" align="justify">Human and industrial activities produce air pollutants that can cause a decline in air quality. In urban areas, transportation activities are the main source of air pollution. One of the emitted air pollutants produced by transportation is carbon monoxide (CO). The understanding of CO concentration is crucial since its overabundance beyond a certain limit will have a negative impact on human health and the environment. In this study, the support vector regression (SVR) method was used to predict CO concentration. The purpose of this study was to predict the hourly CO concentration in the Ujung Berung district, Bandung City, West Java, Indonesia with optimal prediction accuracy. An experiment was carried out by modeling the CO concentration with varying kernel parameter values to obtain accurate prediction results. The suitability of the values between error (<em>ɛ</em>), a trade-off constant (<em>C</em>), and variation mismatch (<em>γ</em>) is vital to obtain optimal prediction results. The results showed that the best prediction accuracy value was 97.68% with kernel parameter values <em>ɛ</em> = 0.02, <em>γ</em> = 30, and <em>C</em> = 0.006. These results may lead to proper decision making on environmental issues and can improve air pollution control strategies.</p> Halawa Ernwati, Yazid Bindar, Acep Purqon, Wahyu Srigutomo Copyright (c) 2022 Journal of Mathematical and Fundamental Sciences Wed, 02 Mar 2022 00:00:00 +0700 Vulnerability of Primary Productivity and Its Carbon Use Efficiency to Unfavorable Climatic Conditions in Jambi Province, Indonesia <p>Climatic conditions and land cover play crucial roles in influencing the process of carbon uptake through vegetation. This study aimed to analyze the effect of climate variability on carbon uptake of four different land covers in Jambi Province, Indonesia. The four land cover types studied were: forest, shrub, grass, and irrigated soybean, based on Community Land Model version 5. Forest was found to have the highest net primary production (NPP) compared to the other land covers. Seasonal climate variability showed no major effect on NPP and gross primary production (GPP). However, GPP and NPP experienced significant declines during El Niño Southern Oscillation (ENSO), particularly in 2015. Carbon use efficiency (CUE = NPP/GPP) was also affected by ENSO, where CUE decreased during El Niño, particularly in October and November with an increased number of days without rainfall. In addition, the difference between latent (LE) and sensible heat (H) flux, denoted as (LE-H), decreased from August to November. This difference was highly correlated with NPP. This result indicates that when water supply is low, stomata will close, thereby reducing photosynthesis and transpiration, and allocating more of the available energy to sensible heat flux rather than latent heat flux.</p> Ummu Ma'rufah, Tania June, Ashehad Ashween Ali, Akhmad Faqih, Yonny Koesmaryono, Christian Stiegler, Alexander Knohl Copyright (c) 2022 Journal of Mathematical and Fundamental Sciences Wed, 01 Jun 2022 00:00:00 +0700 Trade Credit Policies for Supplier, Manufacturer, and Retailer: An Imperfect Production-Inventory System with Rework <p>In this study, we developed a trade credit policy for a three-layer supply chain consisting of a supplier, a manufacturer and a retailer. We propose an optimal production rate and selling price for the manufacturer and the retailer under an imperfect production system. The suggested coordination policy optimizes the profit of each supply chain member. Two models were formulated for two real-life strategies respectively. The first one is a collaborative (integrated) system and the second one is a Stackelberg leadership system. Both strategies were analyzed for various credit periods, respectively offered by the supplier to the manufacturer, by the manufacturer to the retailer, and by the retailer to the customers, by considering price-sensitive demand and a certain replenishment rate. Finally, we concluded which strategy will be better for inventory management under the given restrictions in the form of propositions. The concavity property for the net profit function was established with respect to the selling price and the production rate, which was also described graphically and analyzed by numerical examples.</p> Atmaram Nigwal, Uttam Kumar Khedlekar, Leena Sharma, Neelesh Gupta Copyright (c) 2022 Journal of Mathematical and Fundamental Sciences Sun, 05 Jun 2022 00:00:00 +0700 Piper crocatum Ameliorates APAP-Induced Hepatotoxicity through Antioxidant and Anti-Inflammatory Mechanisms <p>Cirrhosis is a serious hepatic disease that occurs worldwide and is caused by progressive fibrosis in the liver. Free radicals are the major cause of reactive oxygen species (ROS) generation, which affects the balance of the liver metabolism. <em>Piper crocatum</em>, commonly called red betel, is widely used in ethnomedicine because it has biological capabilities, including antioxidant and anti-inflammatory properties. The present study was undertaken to examine the possibility of hepaprotective activity of red betel extract on acetaminophen (APAP)-induced HepG2 cells as the cirrhosis <em>in vitro</em> model. Assessment of red betel extract (RBE) was performed using the colorimetric method for the quantification of LDH, AST, and ALT. As preliminary study, a cytotoxicity assay was performed at various RBE concentrations (100.00; 50.00; 25.00; 12.50; 6.25; 3.13 μg/ml) using an MTS assay to decide the safe concentration based on cell viability. The RBE treatment did not affect cell viability, even at a high concentration (100 µg/ml, p &gt; 0.05). RBE at concentrations 25 and 100 µg/ml successfully reduced LDH, AST, and ALT activities in the hepatotoxic model in a dose-dependent manner. In the APAP-induced hepatotoxicity model, RBE positively indicated a hepatoprotective effect and cell amelioration by a decrease in hepatotoxic markers.</p> I Nyoman Ehrich Lister, Chrismis Novalinda Ginting, Ermi Girsang, Adek Amansyah, Linda Chiuman, Ni Luh Wisma Eka Yanti, Wahyu Setia Widodo, Dewani Tediana Yusepany, Rizal Rizal, Wahyu Widowati Copyright (c) 2022 Journal of Mathematical and Fundamental Sciences Tue, 21 Jun 2022 00:00:00 +0700 Flower Pollination and Elitism Algorithms for Inversion of TDEM Data <p>Hybridization of algorithms can enhance the overall search capabilities to get the optimal solution. The aim of this study was to invert Time Domain Electromagnetic (TDEM) data using the Flower Pollination Algorithm (FPA) as a new inversion scheme technique. FPA was originally inspired by the fertilization process of flowers, in which pollen transfer grains from male flowers to female flowers. The modeling of TDEM data was done by combining the FPA and elitism (eFPA) techniques. The applicability was tested on forward modeling data and observed data in MATLAB 2017a. In testing the algorithm, we used a model from homogeneous half space to a multi-layer model using different parameters (resistivity and thickness). In addition, in the inversion process, we used field data with various starting model approaches. Based on the results of the TDEM data modeling, FPA and eFPA can both be applied as algorithmic techniques for inversion modeling of TDEM data. The eFPA technique gave better results than FPA.</p> Widodo Widodo, Farkhan Raflesia, Susanti Awaliyah, Setianingsih Setianingsih, Djoko Santoso, Wahyudi Parnadi, Fatkhan Fatkhan Copyright (c) 2022 Journal of Mathematical and Fundamental Sciences Tue, 30 Aug 2022 00:00:00 +0700 Basin Study in Atambua, West Timor, Indonesia from Gravity Data <p>Timor Island, Indonesia has complex geological structures related to its tectonic history. There is an existing subsurface geological model that is based on geophysical data. It is limited to the regional crustal scale and has a relatively low spatial resolution. The objective of our study was to delineate the sedimentary basin configuration of the area, both laterally and vertically, based on gravity data. Spectral analysis of the Bouguer anomaly allowed for anomaly enhancement by wavenumber domain filtering. Two main basins were identified from elongated low gravity anomalies that follow a SW-NE trend, i.e., the Central Basin and the Atambua Basin. The 2½D gravity modeling of selected profiles perpendicular to the regional structural direction revealed the sedimentary fills of the basins and the basement based on their densities. The Bobonaro mélanges and Viqueque sequences dominate and overlay the syn-rift (Kekneno sequences) and post-rift (Kolbano sequences) with varying lithology. These para-autochthon sediments are dominated by shale and carbonaceous rocks. Their respective thicknesses and depths of burial imply the possibility of hydrocarbon generation. The underlying basement may be associated with the Australian crust protruding from the south.</p> Edy Wijanarko, Ilham Arisbaya, Prihadi Sumintadireja, Warsa, Hendra Grandis Copyright (c) 2022 Journal of Mathematical and Fundamental Sciences Fri, 02 Sep 2022 00:00:00 +0700 Backward Bifurcation Emerging from a Mathematical Model of African Animal Trypanosomiasis Disease in White Rhino Populations <p>This paper introduces a mathematical model for African animal trypanosomiasis (AAT) in white rhino and tsetse fly populations. The model accommodates two types of interventions, namely infection detection and ground spraying. The dynamical system properties were thoroughly investigated to show the existence of equilibrium points, backward bifurcation, and how they are related to the basic reproduction number. We found that there is a chance that AAT may die out from the population if the basic reproduction number is smaller than one. However, the possible existence of backward bifurcation implies a condition where we may have a stable endemic equilibrium, even when the basic reproduction number is smaller than one. Hence, the basic reproduction number is no longer sufficient to guarantee the disappearance of AAT from the population. Our sensitivity analysis on the basic reproduction number showed that the interventions of infection detection and ground spraying have good potential to eradicate AAT from the population. To analyze the most effective intervention as time-dependent variable, we reconstructed our model as an optimal control problem. Numerical simulations on various scenarios were conducted for the optimal control problem. Cost-effectiveness analysis using the Average Cost-Effectiveness Ratio (ACER) and the Incremental Cost-Effectiveness Ratio (ICER) methods was performed. From the cost-effectiveness analysis, we found that ground spraying is the most cost-effective intervention to combat the spread of AAT in white rhino populations.</p> Dipo Aldila, Tama Windyhani Copyright (c) 2022 Journal of Mathematical and Fundamental Sciences Mon, 12 Sep 2022 00:00:00 +0700