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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
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Journal of Mathematical and Fundamental Sciences
Journal Prestige (SJR): 0.173
Citation Impact (citeScore): 1
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Print) 2337-5760
Published by Institut Teknologi Bandung Homepage  [12 journals]
  • Dielectric Meta-lattices with Tunable Reflectivity

    • Authors: Suhandoko Dwi Isro, Soehianie Agoes, Alexander Agustinus Iskandar
      Pages: 1 - 10
      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.
      PubDate: 2022-04-01
      DOI: 10.5614/j.math.fund.sci.2022.54.1.1
      Issue No: Vol. 54, No. 1 (2022)
  • 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

    • Authors: Marina Barulina, Dmitry Kondratov, Sofia Galkina, Olga Markelova
      Pages: 11 - 38
      Abstract: 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 (plate height)-1.
      PubDate: 2022-02-28
      DOI: 10.5614/j.math.fund.sci.2022.54.1.2
      Issue No: Vol. 54, No. 1 (2022)
  • Prediction of Carbon Monoxide Concentration with Variation of Support
           Vector Regression Kernel Parameter Value

    • Authors: Halawa Ernwati, Yazid Bindar, Acep Purqon, Wahyu Srigutomo
      Pages: 39 - 53
      Abstract: 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 (ɛ), a trade-off constant (C), and variation mismatch (γ) is vital to obtain optimal prediction results. The results showed that the best prediction accuracy value was 97.68% with kernel parameter values ɛ = 0.02, γ = 30, and C = 0.006. These results may lead to proper decision making on environmental issues and can improve air pollution control strategies.
      PubDate: 2022-03-02
      DOI: 10.5614/j.math.fund.sci.2022.54.1.3
      Issue No: Vol. 54, No. 1 (2022)
  • Vulnerability of Primary Productivity and Its Carbon Use Efficiency to
           Unfavorable Climatic Conditions in Jambi Province, Indonesia

    • Authors: Ummu Ma'rufah, Tania June, Ashehad Ashween Ali, Akhmad Faqih, Yonny Koesmaryono, Christian Stiegler, Alexander Knohl
      Pages: 54 - 75
      Abstract: 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.
      PubDate: 2022-06-01
      DOI: 10.5614/j.math.fund.sci.2022.54.1.4
      Issue No: Vol. 54, No. 1 (2022)
  • Trade Credit Policies for Supplier, Manufacturer, and Retailer: An
           Imperfect Production-Inventory System with Rework

    • Authors: Atmaram Nigwal, Uttam Kumar Khedlekar, Leena Sharma, Neelesh Gupta
      Pages: 76 - 108
      Abstract: 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.
      PubDate: 2022-06-05
      DOI: 10.5614/j.math.fund.sci.2022.54.1.5
      Issue No: Vol. 54, No. 1 (2022)
  • Piper crocatum Ameliorates APAP-Induced Hepatotoxicity through Antioxidant
           and Anti-Inflammatory Mechanisms

    • Authors: 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
      Pages: 109 - 120
      Abstract: 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. Piper crocatum, 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 in vitro 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 > 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.
      PubDate: 2022-06-21
      DOI: 10.5614/j.math.fund.sci.2022.54.1.6
      Issue No: Vol. 54, No. 1 (2022)
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