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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14411/18

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Optimizing Drone-Based Humanitarian Relief in Post-Disaster Scenarios: A Hybrid MCDM and Maximum Coverage Approach
(Springer Heidelberg, 2026-05-02) Vural, Danisment
This study proposes a novel hybrid decision-making framework that integrates expert-driven supply prioritization via the Stepwise Weight Assessment Ratio Analysis (SWARA) method with an operationally constrained Maximum Coverage Problem (MCP) model to optimize drone-based humanitarian logistics in post-disaster scenarios. Grounded in a real-world case study of the 2023 Kahramanmaraş earthquake, the model systematically elicits expert preferences to rank critical supplies such as food, medical items, and cold chain products, and embeds these weights directly into a constrained MCP formulation. The model incorporates drone-specific operational limits, including battery consumption, payload capacity, and round-trip feasibility, to ensure realistic deployment strategies. Results show that scenario configurations with four to five strategically located drone bases, each equipped with four to five drones, can increase the achieved priority-weighted delivered quantity by up to 35-40% compared to minimal base-drone configurations within the proposed model framework. Moreover, the proposed framework improves responsiveness by prioritizing urgent deliveries and supporting more timely allocation decisions under operational constraints. Unlike traditional MCP approaches that rely on static weights, this method offers a context-sensitive and scalable optimization model informed by field expertise. The findings underscore the potential of structured expert-based weighting combined with operational optimization to enhance the efficiency and responsiveness of drone-assisted disaster relief systems.
A New Conservative Numerical Method for Strongly Coupled Nonlinear Schrödinger Equations
(Springer Heidelberg, 2025-09-30) Ors, Ridvan Fatih; Koroglu, Canan; Aydin, Ayhan
In this paper, a numerical method based on the conservative finite difference scheme is constructed to numerically solve the strongly coupled nonlinear Schr & ouml;dinger (SCNLS) equation. Conservative properties such as energy and mass of the SCNLS equation have been proven. In particular a fourth-order central difference scheme is used to discretize the the spatial derivative and a second-order Crank-Nicolson type discretization is used to discretize the temporal derivative. It has been shown that the proposed scheme preserves the discrete mass and energy. The existence of discrete solution is also investigated. Several numerical results are given to demonstrate the preservation properties of the new method. Also, the effect of the linear coupling parameters on the evolution of solitary waves is investigated.
Factors Influencing the Transition Time From Psoriasis to Psoriatic Arthritis: A Real-World Multicenter Analysis
(Springer Heidelberg, 2025-09-09) Kilic, Gamze; Kilic, Erkan; Tekeoglu, Ibrahim; Sargin, Betul; Cengiz, Gizem; Balta, Nihan Cuzdan; Nas, Kemal
To identify clinical and demographic predictors associated with the timing of transition from psoriasis (PsO) to psoriatic arthritis (PsA), and to compare the characteristics of patients with concurrent PsO-PsA onset versus those with prolonged transition. A multi-center, observational study was conducted using data from the Turkish League Against Rheumatism (TLAR) network including PsA patients fulfilling CASPAR criteria. Patients were categorized into two groups: Group 1 (concurrent PsO and PsA onset within +/- 1 year) and Group 2 (prolonged transition to PsA, > 1 year after PsO). Demographic, clinical, and laboratory characteristics, disease activity, and patient-reported outcomes were compared between groups. Logistic regression was employed to determine independent predictors of prolonged transition. Among 799 patients (mean age 46.8 +/- 12.3 years), 237 (29.7%) had concurrent onset and 562 (70.3%) had a prolonged transition, with a mean PsO-to-PsA interval of 12.9 +/- 9.6 years. Depression (p = 0.005) and fatigue levels (p = 0.011) were significantly higher in patients with prolonged transition to PsA. Multivariate analysis revealed that scalp psoriasis (OR = 7.162), nail psoriasis (OR = 3.270), family history of PsO (OR = 1.813), and enthesitis ever (OR = 2.187) were associated with prolonged transition. Conversely, family history of PsA (OR = 0.421) and older age at PsO onset (OR = 0.957) predicted shorter transition. Prolonged transition from PsO to PsA is influenced by distinct clinical and demographic factors. Scalp/nail psoriasis, family history of PsO, and enthesitis ever may signal higher risk for prolonged PsA onset. Recognizing these markers can support timely referral and intervention, minimizing diagnostic delay and improving long-term patient outcomes.
Citation - WoS: 7
Citation - Scopus: 7
Characterization of Bi12sio20< Single Crystal: Understanding Structural and Thermal Properties
(Springer Heidelberg, 2024-09-17) Altuntas, G.; Isik, M.; Gasanly, N. M.
This study presents a thorough examination of the structural and thermal characteristics of Bi12SiO20 crystal. X-ray diffraction (XRD) analysis was employed to investigate the crystallographic structure, while scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were utilized to ascertain morphological features and elemental composition, respectively. The XRD spectrum exhibited numerous peaks corresponding to the cubic crystalline structure. Thermal behavior was investigated through thermal gravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Within the crystal, negligible weight loss was observed up to 750 degrees C, followed by weight loss processes occurring in the temperature ranges of 750-919 degrees C and above 919 degrees C. The 2% weight loss in the range of 750-919 degrees C was associated with the decomposition process, and the activation energy of this process was found to be 199 kJ/mol considering Coats-Redfern expression. A significant weight loss was observed in the region above 919 C-o and was associated with the decomposition of the Bi12SiO20 compound and/or the melting processes of the components of the Bi12SiO20 compound. Three endothermic peaks were observed in the DTA plot. Additionally, DSC measurements conducted under varied heating rates indicated endothermic crystallization process around 348 degrees C, with an activation energy of 522 kJ/mol determined through the Kissenger equation. These findings present valuable details regarding the crystal's structural configuration, morphological attributes, and decomposition/phase transitions, thereby illuminating its potential applications across various fields.
Citation - WoS: 30
Citation - Scopus: 38
A Guide for Validation of Fe-Simulations in Bulk Metal Forming
(Springer Heidelberg, 2005) Tekkaya, AE; Manufacturing Engineering
Numerical analysis of metal forming processes is an everyday practice in industry. Forming loads, material flow, forming defects such as underfills, laps, and even cracks, stresses in dies and punches, as well as product properties like new hardness distribution, dimensional accuracies, and residual stresses are predicted by numerical analysis and used for technology generation. Most of the numerical analysis is done by the finite element method made available for engineers and technicians by numerous powerful commercial software packages. These software packages act as black-boxes and usually hide the complicated numerical procedures and even their crucial parameters from the applier. Therefore, the question arises during industrial applications: how accurate is the simulation, and how can the results be assessed? The aim of this paper is to provide a guideline to assess the results of metal forming simulations. Although some ideas are valid for any metal forming process, bulk forming is the primary concern. The paper will address firstly the possible sources of error in a finite element analysis of bulk forming processes. Then, some useful elementary knowledge will be summarized. Various levels of validation such as result and ability validation and assessment will be discussed. Finally, interpretation of results will be treated. In this content also some suggestions will be given.
Citation - Scopus: 1
Assessment and Improvement of Elementary Force Computations for Cold Forward Rod Extrusion
(Springer Heidelberg, 2005) Öcal, M; Egemen, N; Tekkaya, AE; Egemen, Mete; Manufacturing Engineering
Two commonly used analytical force computation methods for cold forward rod extrusion are evaluated by means of precise finite element computations. The upperbound model by Avitzur based on the spherical velocity field and the model by Siebel based on a quasi-upper-bound solution are considered. It has been found that the pure deformation forces obtained by summing the ideal force and shear force terms deviate between +25% and -20% from the finite element solutions. Larger deviations, however, occur for the Coulomb-friction term in the container. A new model based on an elasto-static analysis combined with numerical analysis is suggested to compute this term. This new model supplies also the accurate pressure distribution within the container.
Citation - WoS: 3
Citation - Scopus: 3
Optical Characterization of Nabi(moo4)2< Crystal by Spectroscopic Ellipsometry
(Springer Heidelberg, 2024-08-12) Guler, I.; Isik, M.; Gasanly, N. M.
The compound NaBi(MoO4)(2) has garnered significant interest in optoelectronic fields. This study employs spectroscopic ellipsometry to thoroughly examine the linear and nonlinear optical characteristics of NaBi(MoO4)(2) crystals, offering detailed insights into their optical behavior. Our investigation presents a precise method for discerning the crystal's spectral features, revealing the spectral variations of key optical parameters such as refractive index, extinction coefficient, dielectric function, and absorption coefficient within the 1.2-5.0 eV range. Through analysis, we determined optical attributes including bandgap energy, critical point energy, and single oscillator parameters. Additionally, we explored the nonlinear optical properties of NaBi(MoO4)(2), unveiling potential applications such as optoelectronic devices, frequency conversion, and optical sensors. This study enhances comprehension of optical properties of NaBi(MoO4)(2), underscoring its significance in future optical and electronic advancements.
Citation - WoS: 26
Citation - Scopus: 36
Web Accessibility in Turkey: Awareness, Understanding and Practices of User Experience Professionals
(Springer Heidelberg, 2017-12-05) Inal, Yavuz; Rizvanoglu, Kerem; Yesilada, Yeliz
Ensuring web accessibility for all is not an easy task and requires the awareness, understanding and practices of people with different roles. User experience professionals (UXPs) play an important role in ensuring web accessibility for all. However, in Turkey, there is no research concerning the status of the awareness, understanding and common practices of UXPs. The overall goal of the present work was to offer an assessment of the current situation in Turkey to suggest areas of improvement and changes to advance web accessibility practices. To meet this goal, we conducted an online survey. The results of this survey show that UXPs believe they have enough training and education in web accessibility; however, they are not familiar with web accessibility standards and assistive technologies used by people with disabilities. They do not work with people with disabilities in their studies on usability, and they do not consider web accessibility in their projects. Our findings also show that UXPs have a top-down approach to web accessibility and they think that it is the responsibility of project managers to make web applications accessible. In brief, the study showed that UXPs in Turkey need to be better educated and trained on web accessibility, and organizations need to realize that both top-down and bottom-up approaches are required to ensure accessibility of the web for all.
Citation - WoS: 22
Citation - Scopus: 35
An Ontology-Based Security Risk Management Model for Information Systems
(Springer Heidelberg, 2020-04-23) Arogundade, Oluwasefunmi T.; Abayomi-Alli, Adebayo; Misra, Sanjay
Security risk management is a knowledge-intensive procedure that requires monitoring and capturing relevant information that can assist in making the right decision by managers. In this paper, a semantically enhanced model for security management during the information system lifetime is proposed. The model supports the continuous collection of identified threat behaviours from the intrusion detection system, filtering and analysis of the threats within a time snapshot and re-appraiser of IS security countermeasures which involves the security administrator (S-Admin), managers, IS and security management system as stakeholders. The probe agent categorizes the security threats identified by the IDS using the developed ontology-driven knowledge base, while the likelihood of threats occurring in real time was obtained using long-term frequency probability. The case-based reasoning paradigm is employed for the security solution reasoning of identified threat risk. The suggested security solutions are based on CASE base built on existing threat ontology. The re-appraiser is based on the success likelihood of potential ongoing threats. The system facilitates management decision with regard to security control selection so that they can have a maximum Return on Security Investment. The proposed Collect-Probe-Analyse-Reason-Reappraise model is illustrated using an e-banking system.
An Elaboration of the Cai-Xu Result on (p, q)-integers
(Springer Heidelberg, 2020-02-03) Ostrovska, Sofiya
The investigation of the (p, q)-Bernstein operators put forth the problem of finding the conditions when a sequence of (p, q)-integers tends to infinity. This is crucial for justifying the convergence results pertaining to the (p, q)-operators. Recently, Cai and Xu found a necessary and sufficient condition on sequences {p(n)} and {q(n)}, where 0 < q(n) < p(n) <= 1, to guarantee that a sequence of (p(n), q(n))-integers tends to infinity. This article presents an elaborated version of their result.

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