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Experimental analysis of the combustion and performance of using n-butanol/n-heptane blends at different compression ratios in a SI-HCCI engine
Full text linkIn this study, the use of n-butanol at different compression ratios and different lambda values in a single cylinder homogeneous charge compression ignition engine was investigated experimentally. A spark ignited-mode converted Ricardo Hydra with variable compression ratio was used as the test engine. The findings are presented as a working map. In this study, imep maps, in-cylinder pressure and rate of heat release change, start of combustion, combustion duration, indicated thermal efficiency, maximum pressure rise rate and emissions were explained in detail. The addition of n-butanol to high reactivity n-heptane allowed the control of the homogeneous charge compression ignition combustion phase. The oxidation reactions were slowed down and most of the combustion took place around the top dead center. This allowed the achievement of an indicated thermal efficiency in the range of 35% to 44% and simultaneous reduction of carbonmonoxide and hydrocarbon emissions. Although the widest operating range was obtained with the reference neat n-heptane, by increasing compression ratio, the operating range of n-butanol-containing blend fuels could also be extended. Low reactivity n-butanol also partially reduced knocking, which is a major problem of homogeneous charge compression ignition combustion. Compared to the reference neat n-heptane, hydrocarbon emissions could be reduced by an average of 50% when using B60 fuel. This study clearly demonstrated that n-butanol is an ideal fuel type for homogeneous charge compression ignition engines.Scientific Research Projects Coor-dination Unit of Afyon Kocatepe University [22, FEN.BI bull; L.47]This study was supported by the Scientific Research Projects Coor-dination Unit of Afyon Kocatepe University under project number 22. FEN.BI center dot L.47. The authors express their sincere gratitude for the support provided by this institution
A lossless floating capacitance multiplier based on the single DDCC-
Full text linkIn this paper, a new lossless floating capacitance multiplier (FCM) using a single inverting type differential difference current conveyor (DDCC-) is proposed. Only 16 MOS transistors are used in the internal structure of the DDCC-. The proposed FCM includes a canonical number of passive components. Passive element matching requirements are unnecessary for the proposed FCM. The proposed FCM exhibits low power dissipation, and for a multiplication factor of 500, its operating frequency range extends from approximately 22 mHz to 500 kHz. Simulation results indicate that the operating frequency range remains unaffected with the temperature variations. The proposed FCM is tested in the application example and experimentally with AD844s. All simulations by using the SPICE program are accomplished.Scientific Research Projects at Pamukkale University in Turkiye [2023UBDIP001]This work was supported in part by the Scientific Research Projects at Pamukkale University in Turkiye under Grant number 2023UBDIP001
Evaluating zero-carbon measures through a probabilistic hesitant fuzzy LOPCOW and WISP approach
No full textClimate change is a pressing issue globally, and countries are implementing zero-carbon measures (ZCMs) to combat it. The ranking of such measures is essential, as it facilitates policymakers in preparing action plans for sustainability. As a variant of the hesitant fuzzy set (HFS), the probabilistic hesitant fuzzy set (PHFS) is utilized, which considers both hesitancy during rating and the associated confidence level for each value. Logarithmic percentage change-driven objective weighting (LOPCOW) and simple weighted sum product (WISP) are cuttingedge weighting and ranking methods for multi-criteria decision-making (MCDM), respectively. This study aims to rank ZCMs to achieve SDG13 via a novel integrated LOPCOW-WISP multi-criteria method with PHFSs. So far, there has been no work on developing LOPCOW and WISP methods under PHFSs, and no PHFS-driven research has evaluated ZCMs. Regarding the findings, sustainable agriculture is the foremost measure, followed by research and innovation and decarbonizing industry. Sensitivity and comparison analyses are further conducted to realize the method's robustness. The findings can also help to shape the practical and future end-use vision for energy resources, allowing for significant advantages while incurring zero-carbon emissions costs. Policymakers can readily use this framework in logical decision-making processes. Furthermore, the study proposes an ideal measurement method that prioritizes technological, agricultural, and research and development factors, along with concerns like energy efficiency, to achieve the goal of zero-carbon emissions
Interfacial interactions in electrospun PVA-MC/MXene nanofibers: A route to enhanced dielectric and antimicrobial properties
Full text linkThis study comprehensively investigates the structural, electrical, biological, and functional properties of electrospun PVA-MC/MXene fiber nanocomposites prepared by incorporating MXene into a polyvinyl alcohol (PVA)-methyl cellulose (MC) matrix. The inclusion of MXene notably refined the fiber morphology, reducing the average diameter from 214 nm to 86 nm at a 5 wt% MXene concentration. EDX-MAP analyses confirmed homogeneous elemental distribution at 5 wt%, while Ti clustering was observed at 10 wt%. Surface characterization revealed enhanced hydrophilicity, with the contact angle decreasing from 55.2 degrees to 49.2 degrees and total surface free energy increasing from 59.02 mN/m to 64.33 mN/m. Thermal analyses indicated improved stability, as the onset degradation temperature rose from 290 degrees C to 315 degrees C and the glass transition temperature from 110 degrees C to 121 degrees C. The dielectric constant (epsilon') increased to 10.5 with 10 wt% MXene, consistent with interfacial polarization governed by the Maxwell-Wagner-Sillars mechanism. AC conductivity improved from 10(-8) S/cm at 10(3) Hz to 10(-5) S/cm at 10(6) Hz. Biologically, DPPH radical scavenging efficiency reached 53 %, showing a similar to 20 % enhancement over pristine PVA-MC. Antimicrobial activity also increased, with inhibition zones expanding from 12 mm to 15 mm for E. coli and from 9 mm to 14 mm for C. albicans. Overall, PVA-MC/MXene nanocomposites exhibit superior dielectric, thermal, and biological characteristics, making them promising candidates for applications in energy storage, biomedical coatings, wound dressings, smart sensors, and filtration systems.Afyon Kocatepe University Scientific Research Projects Coordination UnitThis study has been supported by the Afyon Kocatepe University Scientific Research Projects Coordination Unit. The Project Number is 25.FENED.05
A novel three-segment solar radiation forecasting model
No full textThe alteration of solar radiation data is dependent to stochastic and deterministic internal features. Deterministic feature is caused by solar geometry and movements in the nature whereas, the stochastic features are composed from random atmospheric events. It is considered that, focusing on these features separately will increase the accuracy of forecasting. Therefore, in this study, a new solar radiation estimation model was developed by considering these intrinsic features separately. While dealing the deterministic part, the hours without sunlight were determined using corresponding extraterrestrial solar information of region. On the other hand, the sudden changes in sun set and rise times are considered separately. Finally, a similar pattern-based approach was developed to capture stochastic changes. In this way a three-segmented prediction model is proposed. The accuracy of the proposed model has been tested and the accuracy results have been compared with other models in the literature in terms of different benchmarks. The results indicate that, proposed model can predict data quite accurately.Scientific and Technological Research Council of Trkiye (TUBITAK) [123E624]; TUBITAKThis study was supported by the Scientific and Technological Research Council of Turkiye (TUBITAK) with project number 123E624. We would like to thank TUBITAK for its support to the project. We would also like to thank them for providing the data used in the study from the 5th Regional Directorate of Meteorology
Quantile-frequency dependence between US sector stock indices and macro-financial indicators: A quantile coherence approach
No full textThis study explores the quantile-frequency linkages between U.S. sectoral stock indices and four macro-financial indicators: market volatility (VIX), geopolitical risk (GPR), inflation expectations (T5YIE), and the yield curve (T10Y3M), using the Quantile Coherence (QC) framework. The method captures nonlinear and asymmetric interactions across quantiles and horizons. The dataset covers daily observations from January 2016 to July 2025, encompassing episodes such as Brexit, the China-U.S. trade war, and recent geopolitical conflicts. Results reveal strong sectoral heterogeneity: dependence on VIX is predominantly negative in the short term during bullish phases, with reversals at longer horizons; the influence of GPR is asymmetric and forwardlooking; inflation expectations, captured by T5YIE, show a stable long-run positive association with all sectors; while the yield curve (T10Y3M) generates systematic long-term co-movements, with leadership alternating between financial indicators and sector indices across regimes. These findings demonstrate uneven sectoral responses to macro-financial drivers and provide guidance for risk management and portfolio design in uncertain environments
Fuel cell electric long-haul truck evaluation for sustainable transport via a novel Pythagorean fuzzy sets-driven tool
No full textFossil fuel-powered trucks and vehicles used in road freight transportation play a notable role in the emission of greenhouse gases. Although the road vehicle industry's use of renewable energy is promising in terms of sustainability, the vehicle manufacturing industry's initiatives are still in their infancy. Moreover, existing studies on using electric and renewable energies in transportation have primarily focused on electric automobiles. Considering these research and practice gaps, this work investigates the selection of the most proper fuel cell electric long-haul trucks (FCETs) to restructure the Turkish fleet of long-haul trucks operating nationwide concerning sustainability. However, assessing these vehicles is challenging, as they are produced based on new and advanced technology, with severe and highly complicated uncertainties. Thus, this paper suggests a Pythagorean fuzzy distance measure-based weighted integrated sum product (WISP) with the integration of the symmetry point of criteria (SPC) and relative closeness coefficient (RCC)-based weighting methods. Surprisingly, and unlike the findings of earlier works, the acquired conclusions indicate that refueling time (0.1161) is the most influential factor for FCET selection, followed by range (0.0837) and torque (0.0785) among the 14 criteria. Besides, the first alternative (R1) outperforms the other options, followed by R5 and R7. Finally, robustness and validity checks ensured the consistency, stability, and practicality of the conclusions. The research can guide manufacturers who produce FCETs and aim to enhance the quality and desirability of their products. Furthermore, practitioners and researchers can utilize the proposed model to solve challenging decision-making problems
Effect of graphite based solid lubricant on noise and braking performance in polymer composite brake friction materials
No full textPurposeThis study aims to investigate and evaluate the effects of graphite, used at different ratios as a solid lubricant in brake pads, on both braking/wear performance, a traditional focus, and braking noise, a crucial comfort criterion.Design/methodology/approachIn this study, brake pad samples containing graphite at different weight ratios (5%, 10%, 15% and 20%) were developed. The physical properties of these samples were determined. Tribological performance (friction coefficient and wear loss) was determined following the ASTM G99 standard at 50 N load and 10,800 m sliding distance. Sound levels generated during braking were measured in decibels (dB). To investigate the wear mechanisms and surface morphology, the worn surfaces of the samples were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy.FindingsAccording to the research results, increasing graphite addition decreased the coefficient of friction. However, it was observed that the coefficient of friction exhibited a more stable behavior as the graphite content increased. One of the most significant findings was the consistent decrease in average noise level as the graphite content increased. The best performance in terms of wear resistance was observed in the sample containing 5% graphite.Originality/valueThis study provides a comprehensive approach that examines the effect of graphite used in brake pad formulations on tribological properties and correlates it with noise performance. The findings reveal that a higher graphite content can provide significantly quieter braking at the expense of an acceptable coefficient of friction and wear loss. This provides critical information for brake pad designers to optimize the balance between performance and comfort (noise) and adds value to the literature review
Targeted and cost-efficient solar cleaning: A novel RTVA approach to robotic path planning
No full textThe efficiency of photovoltaic systems can be significantly compromised by surface soiling, leading to substantial energy losses. While autonomous cleaning systems are increasingly deployed, most existing approaches rely on uniform surface cleaning or time-based scheduling, often ignoring the uneven distribution of contaminants. In this study, a contamination-aware robotic cleaning system is developed, integrating real-time image processing, environmental sensing, and energy-efficient path planning. The system identifies soiled regions through vision-based analysis and schedules cleaning actions according to environmental conditions. A novel routing algorithm, the Recursive Tabular Validation Algorithm, is introduced to solve the Traveling Salesman Problem in the context of partial and targeted cleaning. Unlike conventional heuristics that optimize the visit order, this algorithm prioritizes edge selection and employs a recursive table validation mechanism combined with path-intersection analysis to eliminate suboptimal routes. The prototype comprises four 25 W photovoltaic panels, and scalability simulations were conducted to evaluate algorithmic performance under larger problem sizes. Experimental results demonstrate a 19 % reduction in cleaning energy consumption, with the proposed algorithm outperforming the Nearest Neighbor and the Nearest Neighbor +2-Opt combinations by 17 % and 15 %, respectively. By prioritizing energy-aware route planning and condition-based cleaning, this study introduces a novel contribution to the field of autonomous PV maintenance systems and offers a scalable solution for enhancing the operational efficiency of solar farms.Afyon Kocatepe University Scientific Research Projects Commission [22.FEN.BIL.27]This study was supported by Afyon Kocatepe University Scientific Research Projects Commission within the scope of project number 22.FEN.BIL.27
Determination of D-Dimer, Cystatin-C and Pancreatic lipase values in cats with panleukopenia
No full textBu çalışmada, panlökopenili kedilerde, pankreatik lipaz, d-dimer ve sistatin c değerlerinin belirlenmesi amaçlandı. Araştırmanın materyalini farklı ırk, yaş ve cinsiyetteki feline panlökopeni tanısı konulan 20 kedi ile sağlıklı 6 kedi oluşturdu. Klinik bulgular ile gelen hasta kedilere klinik muayene ve laboratuvar testleri ile kesin tanıya gidilmiştir. Hasta kedilerin tam kan sayısı incelendiğinde total lökosit sayısında belirgin düşüş saptandı. Kontrol ve çalışma grubu kedilerde Panreatik Lipaz, D-Dimer ve Sistatin C biyokimyasal değerlerinin belirlenebilmesi için numuneler antikoagulantsız kan tüplerine alınarak elde edilen kan serum örneklerinde parametrelerin değerleri Wondfo Fine Care Plus cihazı ile saptandı. Yapılan analizlerde kontrol grubuna kıyasla çalışma grubu kedilerde Pankreatik Lipaz seviyeleri anlamlı derecede yüksek bulundu. Yine kontrol grubu ile çalışma grubu kediler karşılaştırıldığında panlökopeni hastalığının d-dimer seviyelerinde istatistiksel olarak anlamlı bir artış olmasa da rakamsal olarak artış olduğu tespit edildi. Son olarak yine kontrol ve çalışma grubundaki kediler kıyaslandığında kan sistatin-c değerinde önemli ve anlamlı bir değişme olmadığı belirlendi. Sonuç olarak bu çalışmada panlökopenili kedilerin pankreatik lipaz değerleri önemli ölçüde artmış olup hastalığın tanısında diğer yapılan tetkikler ile beraber ek bir biyobelirteç olabileceği kanısına varıldı. D-dimer seviyelerinin ise istatistiksel olarak anlamlı yükselmemesine karşın rakamsal değişikliklerin de göz önünde bulundurulması gerekliliği kanısına varıldı. Anahtar Kelimeler : Panlökopeni, Pankreatik Lipaz, D-dimer, Sistatin-c, Kedi, PankreatitThe aim of this study was to determine the pancreatic lipase, d-dimer and cystatin c values in cats with panleukopenia. The material of the study consisted of 20 cats diagnosed with feline panleukopenia and 6 healthy cats of different breeds, ages and genders. Definitive diagnosis was made with clinical examination and laboratory tests in sick cats that presented with clinical findings. When the complete blood count of sick cats was examined, a significant decrease in the total leukocyte count was detected. In order to determine the biochemical values of Pancreatic Lipase, D-Dimer and Cystatin C in the control and study group cats, the samples were taken into blood tubes without anticoagulant and the values of the parameters were determined in the blood serum samples obtained with the Wondfo Fine Care Plus device. In the analyses performed, Pancreatic Lipase levels were found to be significantly higher in the study group cats compared to the control group. Again, when the control group and the study group cats were compared, it was determined that there was a numerical increase, although there was no statistically significant increase in the d-dimer levels of panleukopenia. Finally, when the cats in the control and study groups were compared, it was determined that there was no significant and meaningful change in the blood cystatin-c value. As a result, in this study, the pancreatic lipase values of cats with panleukopenia were significantly increased and it was concluded that it could be an additional biomarker in the diagnosis of the disease together with other examinations. Although the D-dimer levels did not increase statistically significantly, it was concluded that numerical changes should also be taken into consideration. Keywords: Panleukopenia, Pancreatic Lipase, D-dimer, Cystatin-c, Cat, Pancreatiti