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Challenges, Trends, And The Role Of Lstm In Ai-Based Predictive Maintenance Of Electrolyzers For Solar Hydrogen Systems: A Review, Yani Koerniawan Kuatno, Muhamad Zahim Sujod Sep 2026

Challenges, Trends, And The Role Of Lstm In Ai-Based Predictive Maintenance Of Electrolyzers For Solar Hydrogen Systems: A Review, Yani Koerniawan Kuatno, Muhamad Zahim Sujod

Turkish Journal of Electrical Engineering and Computer Sciences

The transition toward low-carbon energy systems has increased interest in hydrogen as a clean energy carrier, with solar-driven water electrolysis emerging as a promising technology due to its high efficiency and compatibility with renewable energy sources. However, dynamic operating conditions and intermittent renewable input accelerate electrolyzer degradation, reducing reliability and system lifespan. Predictive maintenance (PdM), supported by artificial intelligence (AI), offers a data-driven approach to anticipate failures and improve operational durability. This review systematically investigates AI-based PdM approaches for electrolyzers, with an emphasis on long short-term memory (LSTM) networks and Internet of things (IoT) integration. Following PRISMA 2020 guidelines, 35 …


Dynamic Focal Loss Adjustment For Railway Defect Detection, Mehmet Koç, Ridvan Özdemi̇r, Ömer Gerek Sep 2026

Dynamic Focal Loss Adjustment For Railway Defect Detection, Mehmet Koç, Ridvan Özdemi̇r, Ömer Gerek

Turkish Journal of Electrical Engineering and Computer Sciences

Railway infrastructure is critical to the safe and efficient operation of transportation systems, and the early detection of defects is essential for preventing catastrophic failures. Automated defect detection methods are therefore crucial for maintaining continuous safety while reducing maintenance costs. Although Focal Loss is widely used in object detection under class-imbalanced conditions, its fixed α parameter may limit its effectiveness in detecting rare defects. In this study, we propose an adaptive α-tuned Focal Loss approach that dynamically adjusts class weights based on average precision (AP) values. By iteratively optimizing α without relying on gradient-based optimization, the proposed method improves the …


Relative Rate Observer-Based Online Tuning Mechanism For Single-Input Interval Type-2 Fuzzy Pid Controllers, Oqba Aldreiei, Cenk Ulu, Mert Can Kurucu, Müjde Güzelkaya Sep 2026

Relative Rate Observer-Based Online Tuning Mechanism For Single-Input Interval Type-2 Fuzzy Pid Controllers, Oqba Aldreiei, Cenk Ulu, Mert Can Kurucu, Müjde Güzelkaya

Turkish Journal of Electrical Engineering and Computer Sciences

The characteristics of the footprint of uncertainty (FOU) in interval type-2 membership functions (IT2-MFs) are crucial to the performance and robustness of interval type-2 fuzzy controllers (IT2-FCs). However, existing IT2-FC design approaches mostly use fixed FOU structures. This study proposes an online membership function (MF) adjustment mechanism for a single-input interval type-2 fuzzy PID controller (SIT2-FPID)  that adjusts the FOU of the antecedent MFs and weights of the consequent MFs, respectively, to achieve high performance and robustness. The proposed online adjustment mechanism consists of a relative rate observer (RRO), a two-input rule-base adjustment system, and a first-order smoothing filter. The …


Cuip-X25: A Real-World Network Intrusion Dataset For Next-Generation Ai-Driven Security, Arshad Iqbal, Sohail Asghar Sep 2026

Cuip-X25: A Real-World Network Intrusion Dataset For Next-Generation Ai-Driven Security, Arshad Iqbal, Sohail Asghar

Turkish Journal of Electrical Engineering and Computer Sciences

The efficacy of artificial intelligence (AI) in intrusion detection systems (IDS) is critically dependent on high-fidelity training data. However, as detailed in the manuscript's literature review, existing benchmark datasets are predominantly synthetic, outdated, or imbalanced and fail to capture the complexity of the contemporary threat landscape. To bridge this gap, this study introduces CUIP-X25, a novel real-world cyber-attack dataset captured over a four-month period using a dionaea honeypot deployed on a public network. Unlike synthetic alternatives, this dataset provides an authentic representation of modern adversarial tactics, techniques, and procedures, encompassing 3.16 million real events across ten distinct attack categories, including …


Robust Load Frequency Control For Multiarea Electrical Power Systems Via Analytical Proportional-Integral-Derivative Plus Second Order Derivative Controller Design, Yavuz Güler, Mustafa Nalbantoğlu, Ibrahim Kaya Sep 2026

Robust Load Frequency Control For Multiarea Electrical Power Systems Via Analytical Proportional-Integral-Derivative Plus Second Order Derivative Controller Design, Yavuz Güler, Mustafa Nalbantoğlu, Ibrahim Kaya

Turkish Journal of Electrical Engineering and Computer Sciences

This research presents a proportional-integral-derivative plus second order derivative (PIDD2) controller design based on the Direct Synthesis Method (DSM) for load frequency control (LFC) of interconnected power systems. The parameters of the proposed PIDD2 controller are determined using the DSM, which offers an analytical approach for tuning. The design approaches have been developed specifically for single, two, and three-area power systems, encompassing nonreheated and reheated thermal turbines. In the proposed design method, the best values of PIDD2 controller parameters were found by using a multicriteria objective function that includes the integral of absolute error (IAE) and settling time. In response …


Boundary Layer Sliding Mode Control Strategy For Variable-Speed Compressor In Deep Freezers: Experimental Validation Of Energy Efficiency And Freezing Capacity, Sertan Aksoy, Kami̇l Çeti̇n, Sezai̇ Taşkin Sep 2026

Boundary Layer Sliding Mode Control Strategy For Variable-Speed Compressor In Deep Freezers: Experimental Validation Of Energy Efficiency And Freezing Capacity, Sertan Aksoy, Kami̇l Çeti̇n, Sezai̇ Taşkin

Turkish Journal of Electrical Engineering and Computer Sciences

This study presents the design and experimental validation of a nonlinear sliding mode controller developed for a deep freezer equipped with a variable-speed compressor. The proposed control strategy aims to minimize energy consumption while maintaining rapid and stable cooling performance under varying ambient conditions. A detailed thermal model of the deep freezer was established using an equivalent resistance–capacitance network representation, enabling precise analysis of temperature dynamics. The sliding mode-based control algorithm dynamically adjusts the compressor’s operating frequency according to temperature deviation, ambient conditions, and time-dependent factors, providing robust performance without requiring parameter retuning for different models. Beyond theoretical-based analysis, a …


Empowering Edge Intelligence Through Reparameterized Lightweight Transformers And Distributed Inference, Hosein Esmaeili, Mohammad Ali Afshar Kazemi, Reza Radfar, Nazanin Pilevari Sep 2026

Empowering Edge Intelligence Through Reparameterized Lightweight Transformers And Distributed Inference, Hosein Esmaeili, Mohammad Ali Afshar Kazemi, Reza Radfar, Nazanin Pilevari

Turkish Journal of Electrical Engineering and Computer Sciences

Deploying advanced transformer-based models on resource-constrained edge devices remains a significant challenge due to their high memory footprint and substantial compute requirements. In this paper, we propose a reparameterized transformer framework that integrates High-Rank Factorization (HRF) during training, layer merging at inference, and dynamic, load-balanced distributed inference across multiple devices. To further reduce resource usage, our framework supports mixed-precision quantization down to 4-bit, enabling flexible accuracy–latency–energy trade-offs. Experimental evaluations on the ESC-50 environmental sound dataset demonstrate that our method matches or exceeds the performance of larger baseline models while using 20–30% fewer parameters, achieving up to 48% latency reduction in …


Measurement-Aware Zero-Phase Iterative Learning Control For Robust Regulation Of Nonideal Boost Converters In Electric Vehicle Fast Charging, Aytaç Altan, Mohammed S. Alzaidi, Cağfer Yanarateş Sep 2026

Measurement-Aware Zero-Phase Iterative Learning Control For Robust Regulation Of Nonideal Boost Converters In Electric Vehicle Fast Charging, Aytaç Altan, Mohammed S. Alzaidi, Cağfer Yanarateş

Turkish Journal of Electrical Engineering and Computer Sciences

Integrating battery energy storage with DC-DC boost converters for electric vehicle fast charging exposes the regulator to ageing-induced parameter drift, periodic load pulses, and, critically, the nonidealities in the output-voltage sensing chain. This paper proposes a measurement-aware, zero-phase iterative learning control scheme for robust output-voltage regulation of a nonideal boost converter whose parameters are matched to those of a commercial Texas Instruments TPS6102x battery regulator. The controller combines an inner proportional-integral stabilizing loop with an outer zero-phase learning law that updates a feedforward correction based on the sensor-captured output trajectory; a forward-backward robustness filter suppresses the amplification of measurement noise …


Cover And Contents Sep 2026

Cover And Contents

Turkish Journal of Zoology

No abstract provided.


Revealing Cryptic Lineage Diversity In The Persian Gulf And Oman Sea Groupers (Perciformes: Epinephelidae): Phylogenetic And Species Delimitation Insights, Ehsan Damadi, Faezeh Yazdani Moghaddam, Masoumeh Gholipour Cheshm Gilak, Mehdi Ghanbarifardi Sep 2026

Revealing Cryptic Lineage Diversity In The Persian Gulf And Oman Sea Groupers (Perciformes: Epinephelidae): Phylogenetic And Species Delimitation Insights, Ehsan Damadi, Faezeh Yazdani Moghaddam, Masoumeh Gholipour Cheshm Gilak, Mehdi Ghanbarifardi

Turkish Journal of Zoology

Groupers (Epinephelidae) are a taxon of great commercial interest due to their large body size and high market value, and are also an important ecological species for biodiversity conservation in coral reef ecosystems. Despite their importance, phenotypic convergence among species generally leads to incorrect taxonomic identification, an issue enhanced by molecular studies revealing the presence of a high cryptic diversity and complicating conventional systematic frameworks. Herein, grouper species diversity in the ecologically heterogeneous Persian Gulf and Oman Sea was investigated to resolve taxonomic ambiguities and assess patterns of cryptic diversity. Mitochondrial COI gene sequencing was used in conjunction with integrative …


Cover And Contents Sep 2026

Cover And Contents

Turkish Journal of Electrical Engineering and Computer Sciences

No abstract provided.


A Binary Multiobjective Hippopotamus Optimization Algorithm For Feature Selection In Phishing Website Detection, Fatima Belmessaoud, Sofiane Maza, Djaafar Zouache Sep 2026

A Binary Multiobjective Hippopotamus Optimization Algorithm For Feature Selection In Phishing Website Detection, Fatima Belmessaoud, Sofiane Maza, Djaafar Zouache

Turkish Journal of Electrical Engineering and Computer Sciences

Phishing website detection remains a major challenge in cybersecurity as attackers continuously develop new techniques to deceive users. Identifying the most informative features from large datasets is essential to improve classification accuracy while reducing computational complexity. Feature selection is therefore widely addressed using metaheuristic optimization techniques due to their flexibility and global search capability. In this study, we propose a Binary Multiobjective Hippopotamus Optimization Algorithm (B-MOHOA) for feature selection in phishing website detection. The proposed method simultaneously optimizes two conflicting objectives: maximizing classification accuracy and minimizing the number of selected features. Unlike many existing studies that mainly focus on transfer …


Range–Angle-Dependent Oam Beamforming With A Concentric Helical Circular Fda, Uğur Yeşi̇lyurt Sep 2026

Range–Angle-Dependent Oam Beamforming With A Concentric Helical Circular Fda, Uğur Yeşi̇lyurt

Turkish Journal of Electrical Engineering and Computer Sciences

Secure and spatially selective wireless transmission requires orbital angular momentum (OAM) beams that are confined to a specific range and angle, rather than propagating indefinitely along the beam axis. In this paper, a concentric helical circular frequency diverse array (CHCFDA) is proposed to generate range–angle-dependent OAM beams without requiring external phase shifters. The helical element positioning inherently provides the necessary interelement phase distribution through physical step height, while logarithmically increasing frequency offsets are applied across concentric rings—and optionally across individual elements—to eliminate range periodicity and achieve a single, well-focused OAM beam exclusively at the target location. Both linear and logarithmic …


Zoonotic Fish Parasites That Pose Risks To Human Health In Türkiye, Ahmet Özer Sep 2026

Zoonotic Fish Parasites That Pose Risks To Human Health In Türkiye, Ahmet Özer

Turkish Journal of Zoology

Fish-borne zoonotic diseases have been documented as the causative agents of considerable problems for humans on a global scale. This paper, for the first time, reveals the current zoonotic parasites of fish from wild and cultured hosts in marine, freshwater, and aquarium environments, as well as in native, endemic, and introduced hosts across different geographical areas and seas in Türkiye, based on published data to date. According to the latest global reports, zoonotic fish parasites in Türkiye are dominated by nematodes (17 species), trematodes (11 species), and cestodes (four species), followed by acanthocephalans (two species) and myxozoans (two species). The …


Otolith Morphological Variations Reveal Intraspecific Diversity In Two-Spot Barb, Pethia Ticto (Hamilton, 1822), Inhabiting The Riverine Ecosystem, Insha Hassan, Lubna Yasmeen, Mohd Sadiq, Ameer Hamza, Mohammad Afzal Khan Sep 2026

Otolith Morphological Variations Reveal Intraspecific Diversity In Two-Spot Barb, Pethia Ticto (Hamilton, 1822), Inhabiting The Riverine Ecosystem, Insha Hassan, Lubna Yasmeen, Mohd Sadiq, Ameer Hamza, Mohammad Afzal Khan

Turkish Journal of Zoology

The intraspecific variation in otolith wavelet coefficients, contours, and morphometric variables (six size and nine shape indices) was analyzed to discriminate stock variation in Pethia ticto collected from four selected sites along the River Ganga (Narora, Kanpur, Varanasi, and Bhagalpur). The wavelet coefficients extracted revealed symmetrical yet site-specific contour variations, particularly along the rostral, dorsal, and posterior margins, with the fourth-level wavelet explaining 98% of the cumulative accuracy and being selected for contour analysis. Permutational analysis of multivariate dispersion (PERMDISP) (F = 6.11, p = 0.002) and permutational multivariate analysis of variance (PERMANOVA) (F = 8.42, R2 = 0.179, p …


Toxicokinetics And Multibiomarker Assessment Of Coexposure To Sulfamethoxazole And  Titanium Dioxide Nanoparticles In Cyprinus Carpio, Nazish Iftikhar, Rabeea Zafar, Imran Hashmi, Asma Jamil, Christopher Joseph Martyniuk, Munib Ahmed Shafique Sep 2026

Toxicokinetics And Multibiomarker Assessment Of Coexposure To Sulfamethoxazole And  Titanium Dioxide Nanoparticles In Cyprinus Carpio, Nazish Iftikhar, Rabeea Zafar, Imran Hashmi, Asma Jamil, Christopher Joseph Martyniuk, Munib Ahmed Shafique

Turkish Journal of Zoology

The combined effects of pharmaceuticals and nanoparticles (NPs) on aquatic organisms remain insufficiently characterized. The present study examined toxicokinetics and multibiomarker responses of Cyprinus carpio (common carp) following exposure to sulfamethoxazole (SMX) and titanium dioxide (TiO₂) NPs. Juvenile fish were treated with SMX (25, 50, and 100 μg/L) alone and in combination with 1.5 mg/L TiO₂ NPs (96 h). TiO₂ NPs had a significant effect on the bioaccumulation of SMX in muscle tissues, with SMX reaching peak concentrations of 2286.54 ng/g in the 100 μg/L SMX + 1.5 mg/L TiO₂ NPs group after 72 h, compared to 1477.2 ng/g with …


Cover And Contents Sep 2026

Cover And Contents

Turkish Journal of Botany

No abstract provided.


Red Light Accelerates Adventitious Root Primordium Initiation And Differentiation In Phoebe Bournei Cuttings By Modulating Auxin Signaling And Hormonal Balance, Yuewang Niu, Yuanyang Bi, Chenyu Gong, Shipin Chen Sep 2026

Red Light Accelerates Adventitious Root Primordium Initiation And Differentiation In Phoebe Bournei Cuttings By Modulating Auxin Signaling And Hormonal Balance, Yuewang Niu, Yuanyang Bi, Chenyu Gong, Shipin Chen

Turkish Journal of Botany

Adventitious root formation in stem cuttings of Phoebe bournei, an economically and ecologically significant woody species, is a major bottleneck in clonal propagation. To elucidate the impact of spectral quality on early adventitious root development, we characterized the morphological, hormonal, and transcriptomic dynamics of primordium initiation and differentiation under white, red, and blue light. Under red light, cuttings exhibited the earliest and most pronounced formation of white filamentous structures at lenticels, indicative of root primordium initiation, as early as 20 days after cutting, whereas white and blue light treatments showed delayed responses. Paraffin section analysis confirmed the induced origin of …


Involvement Of Melatonin In The Regulation Of Reactive Oxygen Species Levels In Plants, Bariş Uzi̇lday, Oğuzhan Yilmaz, Tolga Yalçinkaya, Zehra Özgecan Tanyolaç, İsmai̇l Türkan, Rengi̇n Özgür Uzi̇lday Sep 2026

Involvement Of Melatonin In The Regulation Of Reactive Oxygen Species Levels In Plants, Bariş Uzi̇lday, Oğuzhan Yilmaz, Tolga Yalçinkaya, Zehra Özgecan Tanyolaç, İsmai̇l Türkan, Rengi̇n Özgür Uzi̇lday

Turkish Journal of Botany

Abiotic stress conditions impair plant metabolism partly by inducing the excessive production of reactive oxygen species (ROS). Melatonin, a multifunctional indoleamine, has emerged as an important regulator of plant responses to oxidative stress. This review highlights recent findings on the interactions among phytomelatonin, ROS homeostasis, antioxidant metabolism, photosynthetic protection, stress priming, and abiotic stress tolerance. We discuss how melatonin modulates the antioxidative response under diverse stress conditions and evaluate its effects on photosynthetic performance, ROS signaling, and membrane stability. Special attention is given to priming studies showing that melatonin pretreatment can improve stress tolerance. Emerging evidence from plant tissue culture …


Complete Chloroplast Genome Analysis Of Critically Endangered Endemic Prangos Denticulata And Insights Into Its Evolutionary Dynamics, Ayşenur Bozkurt, Doğa Seli̇n Kayihan, Hali̇s Batuhan Ünal, Ceyhun Kayihan Sep 2026

Complete Chloroplast Genome Analysis Of Critically Endangered Endemic Prangos Denticulata And Insights Into Its Evolutionary Dynamics, Ayşenur Bozkurt, Doğa Seli̇n Kayihan, Hali̇s Batuhan Ünal, Ceyhun Kayihan

Turkish Journal of Botany

Prangos denticulata (Apiaceae) is a critically endangered and narrowly endemic species restricted to Ankara, Türkiye. To provide genomic resources for its conservation and evolutionary study, we sequenced, assembled, and annotated its complete chloroplast genome using short-read next-generation sequencing. The circular plastome was 153,486 bp in length, exhibiting the typical quadripartite structure with a large single-copy (86,440 bp), small single-copy (17,894 bp), and two inverted repeats (49,152 bp), and an overall GC content of 37.8%. A total of 116 genes were identified, including 92 protein-coding, 31 tRNA, and 5 rRNA genes, of which 20 contained introns. Comparative analyses with P. trifida, …


Drought Priming Improves Waterlogging Tolerance In Alfalfa, But Less Effectively Than Waterlogging Priming, Gürkan Demi̇rkol, Ni̇lüfer Kara Sep 2026

Drought Priming Improves Waterlogging Tolerance In Alfalfa, But Less Effectively Than Waterlogging Priming, Gürkan Demi̇rkol, Ni̇lüfer Kara

Turkish Journal of Botany

Waterlogging severely restricts growth and productivity in alfalfa (Medicago sativa L.), necessitating effective strategies to improve stress tolerance. This study investigated whether drought priming or waterlogging priming could enhance tolerance to subsequent waterlogging stress in the alfalfa cultivar “Bilensoy-80”. Plants were subjected to drought priming, waterlogging priming, or no priming prior to progressive waterlogging stress for 0, 4, 8, 12, 16, and 20 days. Waterlogging priming consistently alleviated growth inhibition, maintained chlorophyll content, and reduced oxidative damage under prolonged stress. Drought priming was associated with partial cross-tolerance, particularly through improved root growth, plant water status, and oxidative stress responses, although …


Cover And Contents Sep 2026

Cover And Contents

Turkish Journal of Mathematics

No abstract provided.


Generalized Spectral Bound For Quasi-Twisted Codes, Buket Özkaya Sep 2026

Generalized Spectral Bound For Quasi-Twisted Codes, Buket Özkaya

Turkish Journal of Mathematics

Minimum distance bounds play a central role in the analysis of algebraic codes. For cyclic and constacyclic codes, several bounds based on their zero set have been developed. However, analogous results for quasi-twisted (QT) codes are comparatively limited. In this paper, we further investigate the spectral theory of QT codes and derive a general spectral bound on their minimum distance. Our bound unifies and generalizes previously known spectral bounds for quasi-cyclic (QC) and QT codes, and contains them as special cases. We present a new proof technique and show that the bound can be formulated with respect to an arbitrary …


A Novel Iterative Algorithm For Approximating Common Fixed Points Of Generalized Α-Nonexpansive Multivalued Mappings In Kohlenbach Hyperbolic Spaces, Makbule Kaplan Özekes Sep 2026

A Novel Iterative Algorithm For Approximating Common Fixed Points Of Generalized Α-Nonexpansive Multivalued Mappings In Kohlenbach Hyperbolic Spaces, Makbule Kaplan Özekes

Turkish Journal of Mathematics

In this paper, we propose a new iterative scheme involving three multivalued mappings in Kohlenbach hyperbolic spaces. Strong and ∆-convergence theorems are established for approximating common fixed points of nonexpansive multivalued mappings under suitable conditions. A numerical example is also presented to illustrate the efficiency and faster convergence of the proposed method. The results obtained extend and unify several related contributions in the existing literature.


On Families Of Finsler Metrics, İsmai̇l Sağlam, Ken'ichi Ohshika, Athanase Papadopoulos Sep 2026

On Families Of Finsler Metrics, İsmai̇l Sağlam, Ken'ichi Ohshika, Athanase Papadopoulos

Turkish Journal of Mathematics

In this paper, we answer some natural questions concerning symmetrisation and more general combinations of Finsler metrics, with a view to applications to Funk and Hilbert geometries and metrics on Teichmüller spaces. The metrics on Teichmüller space that we consider are the Thurston metric and the earthquake metric, both introduced by Thurston. The first metric has been thoroughly studied over the last couple of decades, and the second over the last few years. The Funk metric and its symmetrisation, the Hilbert metric, are classical metrics that have been investigated in the contexts of hyperbolic geometry and geometric function theory and, …


On The Monoid Of Partial Order-Preserving Transformations Of A Finite Chain Whose Domains And Ranges Are Intervals, Hayrullah Ayik, Vítor H. Fernandes, Emrah H. Korkmaz Sep 2026

On The Monoid Of Partial Order-Preserving Transformations Of A Finite Chain Whose Domains And Ranges Are Intervals, Hayrullah Ayik, Vítor H. Fernandes, Emrah H. Korkmaz

Turkish Journal of Mathematics

In this paper, we consider the monoid PIOn of all partial order-preserving transformations on a chain with n elements whose domains and ranges are intervals, along with its submonoid PIOn− of order-decreasing transformations. Our main aim is to give presentations for PIOn− and PIOn. Moreover, for both monoids, we describe regular elements and determine their ranks, cardinalities and the numbers of idempotents and nilpotents.


On The Generalized Cesàro Sequence Spaces And Some Of Their Properties, Uğur Gönüllü, Faruk Polat, Martin Richard Weber Sep 2026

On The Generalized Cesàro Sequence Spaces And Some Of Their Properties, Uğur Gönüllü, Faruk Polat, Martin Richard Weber

Turkish Journal of Mathematics

Let Ct = (cnm)n,m∈ℕ denote the generalized Cesàro matrix defined by cnm = tn−m/n for m ≤ n and t ∈ [0, 1], and cnm = 0 otherwise. For each q ∈ [1, ∞), the associated generalized Cesàro sequence spaces cesqt are introduced. These spaces form Banach lattices under the coordinatewise order, equipped with a naturally defined order continuous norm. We prove that cesqt = cesq0 for all t ∈ [0, 1) and q ∈ [1, ∞), implying that the space …


A Note On The Periodic Orbits Of Wolbachia Spread Dynamics In Mosquito Populations In Periodic Environments, Jose S. Cánovas Sep 2026

A Note On The Periodic Orbits Of Wolbachia Spread Dynamics In Mosquito Populations In Periodic Environments, Jose S. Cánovas

Turkish Journal of Mathematics

We consider the periodic model introduced by B. Zheng and J. Yu, and disprove the conjectures on the number of periodic orbits the model can have. We rebuild the conjecture to prove that for periodic sequences of maps of any period, the number of nonzero periodic trajectories is bounded by two.


Characterizations Of Bi-Riordan Arrays, Nai̇m Tuğlu, Fatma Yeşi̇l Baran Sep 2026

Characterizations Of Bi-Riordan Arrays, Nai̇m Tuğlu, Fatma Yeşi̇l Baran

Turkish Journal of Mathematics

In this study, we introduce the concept of a bi-Riordan array. As part of this construction, we define new composition and power operations. We then establish an analogue of the well-known fundamental theorem of Riordan arrays (FTRA), which we call the fundamental theorem of bi-Riordan arrays. Next, we show that the product of two bi-Riordan matrices is again a bi-Riordan matrix. Using this product structure, we prove that the set of bi-Riordan matrices forms a monoid.


Exponential Stability For A Strongly Damped Wave Equation With Distributed Internal Delay, Manal Alotaibi, Nasser-Eddine Tatar, Waled Al-Khulaif Sep 2026

Exponential Stability For A Strongly Damped Wave Equation With Distributed Internal Delay, Manal Alotaibi, Nasser-Eddine Tatar, Waled Al-Khulaif

Turkish Journal of Mathematics

This paper investigates the exponential stability of a strongly damped wave equation subject to an internal distributed time delay. Two distinct analytical frameworks are developed: the first employs a modified energy method based on auxiliary functionals, while the second introduces a transformation that rewrites the delay term as the derivative of a convolution integral. Both approaches yield explicit decay conditions and establish exponential convergence of the energy under weaker assumptions on the damping coefficient and the delay kernel. Notably, the transformation method allows for a wider class of admissible delay weights than those permitted by classical techniques. Numerical simulations based …