Sakarya University of Applied Sciences AXSIS
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Tribological investigation of the new combustion chamber with wall-guided fuel injection in a diesel engine
No full textReducing pollutants and increasing thermal efficiency in internal combustion engines is possible by creating better air-fuel mixtures and optimizing the combustion process. In this context, a new combustion chamber providing directed fuel injection was used in a single cylinder diesel engine with a standard combustion chamber. Thus, it was aimed to investigate the tribological behavior of engines with different combustion chambers on long-term engine operation. In engine experiments using two different combustion chambers, the engine was operated at 100 h and partial load. The results of the study showed that changes in combustion chamber structure closely modify engine tribology under the same engine and operating conditions (compression ratio, spray angle and amount, speed, etc.). Looking at the cylinder surfaces examined under an optical microscope, the new combustion chamber showed abrasive wear lines with lower intensity than the standard combustion chamber, while SEM/EDX analysis of the piston ring surfaces showed a similar result. Especially when the analysis of the second ring used in the standard combustion chamber is examined, abrasion occurred in a wider area. Abrasive wear lines were found to be longer, especially in the first ring of the new combustion chamber. It is considered that combustion parameters and exhaust formation processes bring about load/temperature variations of engine lubricating oil and engine components in a chain reaction. This has been found to change the wear levels in engine components and could directly contribute to engine life
A hybrid failure analysis model design for marine engineering systems: A case study on alternative propulsion system
No full textMarine engineering systems have a fundamental role in ensuring the efficiency, safety, and sustainability of maritime transportation. The performance and reliability of these systems, particularly propulsion systems, are of paramount importance. This paper introduces a pioneering hybrid failure analysis model that integrate the Variable Weighted Synthesis Analytic Hierarchy Process (VWS-AHP) with the conventional Failure Mode and Effect Analysis (FMEA) methodology. The primary objective is to enhance the comprehension of failure modes within marine engineering systems, particularly focusing on alternative propulsion systems. While conventional FMEA is a widely employed methodology for analysis of failure modes, its capacity and effectiveness can be further augmented by integrating complementary techniques. The proposed hybrid model combines the robustness of FMEA in identifying failure modes with the VWS-AHP method's ability to handle complex decision-making scenarios involving multiple criteria and varying levels of importance. This integration affords a comprehensive framework to assess failure risks, prioritize critical failure pathways, and evaluate the potential impacts of failures in marine engineering systems. To demonstrate the applicability of the proposed model, we conduct a case study on an alternative propulsion system. The outcomes of the case study showcase the efficacy of the hybrid model in enhancing FMEA
Welding strength prediction in nuts to sheets joints: machine learning and ANFIS comparative analysis
No full textThis study uses machine learning algorithms and the Adaptive Neuro-Fuzzy Inference System (ANFIS) to predict welding strength in DD13 sheet metal joints with AISI 1010 nuts. The objective is to optimize industrial welding processes and improve quality control. The study investigates weld current, time, and hold time as critical input variables for joint integrity. The performance of different ML algorithms, including linear regression, random forest regression, ridge regression, Bayesian regression, K-Nearest Neighbors regression, decision tree regression, and ANFIS, are evaluated. Training and testing data consist of welding parameters and corresponding strength measurements. Performance metrics such as R2 score, mean absolute error (MAE), mean squared error (MSE), and root mean square error (RMSE) are used to assess the predictive capabilities. Random forest regression is the most efficient algorithm, with a high R2 score of 0.992 and minimal errors. ANFIS also exhibits comparable performance, highlighting its efficacy in this context. These findings can be useful for optimizing welding parameters in industrial settings, potentially leading to improved quality control and weld strength, particularly in automotive applications. Using ML and ANFIS, industries can make informed decisions to optimize welding processes and ensure joint integrity, ultimately meeting the rigorous demands of demanding applications. © The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature 2024
Development of immobilized peroxidase on amino-functionalized magnetic MgFe2O4 nanoparticles for antioxidant activity and decolorization
No full textThis investigation aims to immobilize peroxidase onto 3-aminopropyltriethoxysilane (APTES)-functionalized MgFe2O4 magnetic nanoparticles to increase enzyme stability, efficiency, and recyclability. The synthesized samples were analyzed using X-ray diffraction, Fourier transform infrared spectroscopy, Thermogravimetric analysis, Vibrating sample magnetometer, and Scanning electron microscopy. The free and immobilized peroxidase were examined against different pH and temperatures as well as storage time and reuse. The immobilized peroxidase maintained 52 % of its initial activity after 10 consecutive measurements thanks to easy magnetic separation. In addition, antioxidant activity was increased by immobilizing the peroxidase to the MgFe2O4 magnetic nanoparticles. Congo red dye removal for peroxidase immobilized MgFe2O4-APTES was found to be 98.6 % for 240 min. Also, it showed approximately two times more dye decolorization efficiency compared to MgFe2O4 and APTES modified MgFe2O4. Finally, the immobilized peroxidase was studied by a decolorization study of congo red. So, we believe that the immobilized peroxidase on magnetic nanoparticles reported in this study may be utilized in diverse biotechnology, industrial, and environmental practices
Intensive Care Nurses’ Pain Management Experiences within the Framework of the Biopsychosocial-Spiritual Model in Türkiye: A Qualitative Approach
No full textPain, which includes biological, psychological, social and spiritual factors, is a common symptom experienced by patients in intensive care. This study aimed to uncover intensive care nurses’ perspectives on pain management strategies, employing the biopsychosocial-spiritual model as the guiding framework. This research employed a descriptive qualitative method, engaging participants from diverse locations across five provinces and eight different institutions. The study involved 16 intensive care nurses and utilized semi-structured online Zoom interviews. Data analysis was conducted using Braun and Clarke’s six stages, and reporting followed the consolidated criteria for qualitative studies. The answers of the nurses were grouped under four themes and six subthemes: (1) biological interventions, (2) psychological interventions, (3) social interventions: involving families in the process and (4) spiritual interventions: support religious activities. This study shows that intensive care nurses benefit from many practices in pain management. These interventions included medication management and ensuring physical comfort in the biological factor, distracting activities and being with the patient in the psychological factor, involving the family in care in the social factor and providing an environment that supports the patient’s religious needs under the spiritual factor. © The Author(s) 2025
Insights into the high-temperature oxidation and electrochemical corrosion behavior of Si alloyed TiAl alloys and the prediction of corrosion behavior using machine learning approaches
No full textThis study investigates the oxidation and electrochemical corrosion resistance of at% Ti-46Al, Ti-46Al-1Si and Ti-46Al-2Si alloys. Ti-46Al-2Si alloy presented the least tendency for high-temperature oxidation, followed by Ti-46Al-1Si and then Ti-46Al. This result indicates that Si addition plays a key role in enhancing oxidation resistance, which is characterized by the lowest oxidation rate constant and the constitution of a relatively denser and more adherent oxide scale that may serve as a barrier to the ingress of oxygen into the substrate. In the comparison of corrosion performance among all the alloys tested, the Ti-46Al-2Si alloy presented notable results, exhibiting the lowest corrosion rate (Rcorr) value of 0.1199 mm/year. According to the electrochemical impedance spectroscopy (EIS) results, incorporating Si yielded a raised phase maximum and a broadened phase angle. Mott-Schottky analysis indicates that the surface film developed on Ti-46Al-2Si alloy has the least defect density, indicating that the corrosion behavior of the alloy is influenced by the incorporation of Si in a positive way. This study also focuses on predicting the corrosion behavior of TiAl alloys by adopting machine learning (ML) approach. Machine learning algorithms including extra trees (ET), random forest (RF), CatBoost and decision tree (DT) have been successfully employed to predict the corrosion behavior of the alloys. The extra trees regressor model has the highest predictive accuracy for all alloys. Additionally, the current study reveals the potential of machine learning models to predict corrosion behavior. © 2025 Elsevier B.V
Unveiling the NLO Potential of New Zn (II) Complex of 6-Methylpyridine-2-Carboxaldehyde: Experimental/DFT Study on Spectral, Static, and Frequency-Dependent Linear/Nonlinear Optical Parameters
No full textOngoing exploration focuses on synthesizing and characterizing coordination compounds to improve the design of nonlinear optical (NLO)-based materials. In this regard, to examine spectral and static/frequency–dependent linear/NLO parameters, the new Zn (II) complex {[Zn(6-MePyAld)2(Cl)]; 6-MePyAld: 6-methylpyridine-2-carboxaldehyde} was synthesized and characterized by using 1H and 13C NMR, mass (LC-HRMS), powder XRD, and FTIR spectra. The electronic features of synthesized complex were investigated by considering the TD-CAM-B3LYP/ and TD-M06L/6-311G(d,p)//LanL2DZ levels of time-dependent density functional theory (TD-DFT). Moreover, the theoretical linear optical (LO), second-, and third-order NLO susceptibility tensors/polarization (χ(1)/P(1), χ(2)/P(2), χ(3)/P(3)) parameters for the Zn (II) complex were computed using the DFT/M06L and DFT/CAM-B3LYP levels. The external electric field (E), polarization (P), and electric displacement (D) values of the Zn (II) complex were also calculated using the same DFT levels. To investigate microscopic LO (isotropic polarizability /, and anisotropic polarizability (∆α (0;0)/∆α (−ω;ω)) and second-/third-order NLO (/// and ) parameters for the Zn (II) complex, the DFT/M06L and DFT/CAM-B3LYP levels in the gas phase were used. The ∆α (0;0), ∆α (−ω;ω), , , and for Zn (II) complex were computed at 17.288 × 10−24, 21.782 × 10−24, 14.692 × 10−30, 466.80 × 10−30, and 210.79 × 10−30 esu, respectively, by using the DFT/CAM-B3LYP level. Moreover, the / and in the gas phase computed at the DFT/CAM-B3LYP level for Zn (II) complex were obtained at 129.74 × 10−36, 3997.6 × 10−36, and −886.60 × 10−36 esu, in turn. According to the CAM-B3LYP level, the value is 8.65 and 18.53 times higher than the values of para-nitroaniline (pNA) and urea, respectively. The obtained static/dynamic β and γ values of Zn (II) complex are greater than those of urea and pNA. Zn (II) complex exhibited remarkably microscopic second-order and particularly third-order NLO features. It is predicted that our study will shed light on NLO materials that might be used in telecommunication and optoelectronics. © 2024 John Wiley & Sons Ltd
Design optimisation of a screw compressor with a focus on rotor depth: A computational fluid dynamics approach
No full textThe increasing demand for enhanced performance and reliability in twin-screw compressors necessitates the application of advanced optimisation tools to improve performance. This study employs response surface methodology (RSM) to optimise the profile parameters of a standard 5/6 compressor, specifically targeting reduction in specific power. Key factors such as axis distance between rotors and female rotor outer diameter, which define the rotor depth, were included in the present optimisation process. Following the optimisation of the rotor profile, port optimisation was also conducted using the same methodology. A multi-chamber thermodynamic analysis was performed with SCORG™ software, which allowed for the calculation of geometric values and thermodynamic quantities. The results of the rotor optimisation revealed notable improvements: a 4.30 % reduction in specific power, a 2.73 % increase in volumetric efficiency, a 3.93 % enhancement in adiabatic efficiency, and a 2.88 % rise in volumetric flow rate compared to the reference design. After port optimisation, both volumetric and adiabatic efficiencies of the optimised rotor profile remained comparable, while specific power was further reduced by 1.37 %. To validate the performance of the optimised compressor, computational fluid dynamics (CFD) analysis was conducted using a conformal mesh generated by SCORG™ and ANSYS CFX multiphase solver. The maximum deviation between the optimal results from SCORG™ and CFD was only 0.19 %, indicating strong agreement between the two methodologies. This study highlights the significant impact of optimisation techniques on the performance of twin-screw compressors. © 2024 Elsevier Ltd and II
Synthesis, microstructure and radiation protection properties of B2O3–ZnO–K2CO3–PbO ceramic glass system: experimental and theoretical assessment
No full textCeramic glass is a versatile solid-state material engineered to blend the transparency of glass and the thermal stability of ceramics. This fusion has applications in various technological fields with major considerations like radiation protection, durability, heat resistance, and transparency. İn this study, three different B2O3 ceramic glasses comprising varying amounts of ZnO–K2CO3–PbO (BP ceramic glass) were produced, characterized and scanned with electron microscopy. Energy dispersive spectroscopy (EDS) was deployed to find the elemental composition of prepared samples. The radiation protection parameters such as Mass attenuation coefficient (MAC), Linear attenuation coefficient (LAC), Mean free path (MFP), Effective electron density (Neff), Tenth value layer (TVL), Half Value layer (HVL), Effective atomic number (Zeff), Exposure buildup factor (EBF), Equivalent atomic number (Zeq) and Energy absorption build-up factor (EABF) of B2O3–ZnO–K2CO3–PbO (BP) glass–ceramic systems were investigated by using Phy-X/PSD software. The result shows that the micropores increase with an increase in PbO. The density of BP1, BP2, and BP3 were 2.57, 2.36, and 2.19, respectively. The MAC of BP ceramic glass varies as BP1 > BP2 > BP3, implying that BP1 with higher density and greater PbO content is more efficient in radiation protection mostly at lower photon energy. The findings of this research present credible insights applicable to high-performance ceramic glass design for radiation protection in radiotherapy, nuclear power plants, radioactive waste confinement and other related applications. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025
Finite elements investigations of the effect of different parameters on the retrofitted RC beams with anchored FRP plate
No full textFiber-composites constructed of reinforced polymer have recently acquired popularity as an alternative to other traditional materials used in construction reinforcement. These composites are remarkable because of their low weight, high tensile strength compared to its weight ratio, corrosion resistance, and ease of installation in strengthening and retrofitting structural parts. In this work, using the ABAQUS analytical program’s finite element algorithm to analyze 279 models, the effects of multiple parameters on the behavior of RC beams externally bonded and retrofitted with one of three types of polymeric fibers were investigated. This was achieved by modeling a quarter of the complete beams using the beams’ symmetry, where the cohesive bond model of the FRP-concrete interface and the isotropic elastic characteristics of FRP were applied. Good agreement was found between experimental data and numerical results when the material models were adopted with experimental work. Investigations indicate that a typical collapse happens when the cohesive bond breaks, and that while increasing the shear or concrete strength improves the allowable loading capacity, but it does not completely prevent the debonding failure of the beam. U-wrap anchor applications at the end of external bonding are a partial solution to the problem of early collapse in the more rigid fibers, like carbon fiber polymers. The effect of using U-wrap anchors to reduce early collapse varies depending on the stiffness of the fiber; it is effective in the least rigid fibers, like glass fiber-reinforced polymers, but less effective by increasing the stiffness of the fibers, like aramid fiber-reinforced polymers. Furthermore, increasing the U-wrap anchor width is more effective in eliminating the debonding than increasing its height. Copyright © 2025 Techno-Press, Ltd