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Imam Mukhlash
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Departemen Matematika, Gedung F Lantai II, Kampus ITS, Keputih, Sukolilo-Surabaya 60111 Jawa Timur, Indonesia Phone: +62 31-5943354 Email:ijcsam.matematika@its.ac.id
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International Journal of Computing Science and Applied Mathematics-IJCSAM
Published by Institut Teknologi Sepuluh Nopember Surabaya
ISSN : -     EISSN : 24775401     DOI : -
Core Subject : Education,
Mathematics
IJCSAM (International Journal of Computing Science and Applied Mathematics) is an open access journal publishing advanced results in the fields of computations, science and applied mathematics, as mentioned explicitly in the scope of the journal. The journal is geared towards dissemination of original research and practical contributions by both scientists and engineers, from both academia and industry. IJCSAM (International Journal of Computing Science and Applied Mathematics) is a journal published by Pusat Publikasi Ilmiah LPPM, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia.
Arjuna Subject : Matematika - Matematika Terapan
Articles 6 Documents
 1 
Search results for , issue "vol. 12 no. 1 (2026)" : 6 Documents clear
Disturbance Estimation for Unmanned Surface Vehicles using a Nonlinear Disturbance Observer Emilta Friska Juniar; Tahiyatul Asfihani
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 12 No. 1 (2026)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

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Abstract

An Unmanned Surface Vehicle (USV) is a maritime transportation system designed to operate autonomously. However, in complex marine environments, the vessel is subjected to external disturbances such as wind, ocean currents, and waves that can affect the stability and robustness of its motion control system. This study aims to estimate these disturbances in real time using a Nonlinear Disturbance Observer (NDO) and to utilize the estimated disturbances to update the predictive model in a Disturbance Compensating–Nonlinear Model Predictive Control (DC-NMPC) framework. The estimation considers two types of disturbances: constant disturbances representing steady wind and current forces, and periodic disturbances representing wave effects modeled as sinusoidal functions. These disturbances affect the sway velocity (v) and yaw velocity (r) of the vessel. Simulation results show that the NDO is capable of reconstructing the actual disturbances with bounded and consistent estimation errors. This is indicated by RMSE values of 0.0070 for d1 and 0.0605 for d2 under the tested disturbance scenario. The estimation performance remains consistent under variations of the observer gain matrix, indicating observer stability. Increasing the gain improves the estimation response speed but slightly increases the error, revealing a trade-off between responsiveness and estimation accuracy. Furthermore, the observer is able to track time-varying sinusoidal disturbances, demonstrating robustness against dynamic environmental disturbances. These results indicate thatNDO-based disturbance estimation can enhance the robustness of USV motion control under environmental disturbances.
Heterogeneous Correlation Mapping between Rainfall Variability in Lake Toba and Indian Ocean Sea Surface Temperature Mohamad Khoirun Najib; Sri Nurdiati
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 12 No. 1 (2026)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

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Abstract

Rainfall variability in the Lake Toba watershed of North Sumatra is influenced by large-scale ocean–atmosphere in-teractions, particularly those involving sea surface temperatures (SST) in the Indian Ocean. This study applies Heterogeneous Correlation Mapping (HCM) to examine the spatially varying relationship between monthly rainfall at 13 meteorological stations and SST over the Indian Ocean warm pool (5°S–10°N, 60°E–80°E) during 1981–2014. Singular Value Decomposition (SVD) is employed to extract dominant coupled modes of SST–rainfall variability. Results indicate that a six-month lag yields the strongest coupling, with the leading mode explaining 88.5% of the total variance. A clear spatial heterogeneity is observed: stations such as Lumban Julu and Silaen exhibit stronger SST–rainfall correlations, while others show weaker responses, likely due to topographic and local climatic modulation. These findings underscore the importance of accounting for spatial and temporal structures in hydroclimatic teleconnection analysis and offer insights for improving seasonal rainfall prediction in mountainous tropical regions
Quantization-Aware Training for Man-in-the-Middle Attacks Detection in IoT Application Dyah Ayu Suci Ilhami; Aji Gautama Putrada; Farah Afianti
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 12 No. 1 (2026)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

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Abstract

Issues in securing the resilience of Deep Learning models and operational problems related to model size and latency in the Internet of Things (IoT) environment, especially when applied to devices with limited resources, can be overcome by implementing a modified Quantization-Aware Training (QAT) model based on IDS and an autoencoder. This research proposes the use of QAT to achieve operational efficiency while strengthening the detection model’s resilience against data manipulation in MiTM attacks. By integrating QAT, the model not only becomes lighter for edge devices but also more capable of maintaining detection integrity even when model weights are compromised. The research was conducted using the CICIoT2023 dataset, and the output of the advanced QAT model was then applied to resource-constrained IoT devices, namely the Raspberry Pi 3. The methodology began with data collection, followed by data preprocessing, which was then normalized before being fed into the IDS and autoencoder techniques. After the autoencoder model was successfully created, the QAT model was developed so that it remained unchanged or even improved when implemented on the Raspberry Pi 3. With the application of QAT modifications, an 80.43% reduction in model size and an 11.2% increase in model inference speed were confirmed. Furthermore, when faced with QAT model weight corruption of up to 20%, the F1-score value remained stable at 100%. These results show that the QAT model is highly effective at improving model reliability and maintaining the resilience of deep learning models against MiTM attacks, even under limited conditions.
Numerical Study of Vortex Shedding Control Using Viscoelastic Flow Over an Elliptical Cylinder Annisa Dwi Sulistyaningtyas; Basuki Widodo; Chairul Imron; Hanim Faizah
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 12 No. 1 (2026)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

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Abstract

Vortex-Induced Vibration (VIV) mitigation is a critical issue in engineering systems involving bluff bodies subjected to fluid flow. This study presents a numerical investigation of viscoelastic fluid flow over an elliptical cylinder as a passive control strategy to suppress vortex shedding. The governing continuity, momentum, and energy equations for an incompressible viscoelastic fluid are formulated and solved using an implicit finite difference method. The viscoelastic behavior of the fluid is incorporated through a nonlinear constitutive model, and the resulting system of equations is transformed into a dimensionless form to facilitate analysis. The study focuses on the effects of key parameters, including the viscoelastic parameter K, the Prandtl number P r, and the geometric aspect ratio a/b of the elliptical cylinder. Numerical simulations are performed using MATLAB to evaluate the resulting velocity and temperature distributions within the boundary layer region. The results indicate that increasing the viscoelastic parameter significantly reduces the peak velocity near the wall and weakens the velocity gradient, leading to a decrease in shear stress. In addition, higher viscoelasticity contributes to a thicker momentum and thermal boundary layer, which reduces the rate of heat transfer from the surface. Furthermore, variations in the Prandtl number and aspect ratio are found to influence the localization of thermal and momentum transport. Higher values of P r result in thinner thermal boundary layers and enhanced temperature gradients near the surface, while changes in a/b primarily affect the near-wall flow structure. Overall, the combined effects of viscoelasticity and geometric modification demonstrate a strong potential for attenuating vortex shedding and reducing the likelihood and intensity of VIV. These findings provide valuable insights for the design of engineering systems involving non-Newtonian fluids and flow-induced vibrations.
Optimal Incentive Mechanism for ISO 9001 Quality Audit: A Mechanism Design Approach Jani Rahardjo; I Nyoman Sutapa; Togar Wiliater Soloan Panjaitan
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 12 No. 1 (2026)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

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Abstract

This paper develops a principal–agent model for ISO 9001:2015 quality audit in a manufacturing company, where the auditee is an informed agent and the auditor is a principal who designs an incentive-compatible audit mechanism. The proposed mechanism combines self-reported performance, risk-based audit probabilities, and quadratic penalties on deviations between reported and verified performance. We establish explicit mathematical conditions for incentive compatibility and individual rationality that guarantee truthful reporting and substantive compliance as the optimal strategy for the auditee. The mechanism is shown to be constrained Pareto optimal within a natural class of audit contracts: no alternative contract can increase the auditor’s expected utility without reducing the agent’s utility, given the informational constraints. We prove the uniqueness of this optimal solution given a maximum feasible penalty. A parametric sensitivity analysis and a case study from the Indonesian manufacturing sector illustrate how the choice of audit probability, certification benefit, and penalty parameter can transform a symbolic certification regime into an equilibrium with genuine quality improvement and credible ISO 9001 implementation
Graphs with Large Locating Rainbow Vertex Connection Number Tita Maryati; Fawwaz Fakhrurrozi Hadiputra
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 12 No. 1 (2026)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

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Abstract

The locating rainbow vertex connection number of G, denoted by rvcl(G), is the least positive integer k such that there exists a k-coloring of G that ensures G is rainbow vertex-connected and each vertex has a distinct rainbow code. To learn how this parameter behave in graphs, it is natural to consider the extremal case. In this paper, we investigate several graphs with the difference of its order and its locating rainbow vertex connection number is not larger than three, i.e. rvcl(G) ∈ {n, n − 1, n − 2, n − 3} for graphs of order n.Furthermore, we demonstrate the existence of a graph with arbitrary large difference of its partition dimension and its locating rainbow vertex connection number. The study provides an overview of some structures that distinguishability under chromatic constraints becomes most costly, as in large number of colors needed.

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