Browsing by Author "Yilmaz D."

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Climate-related spatial reduction risk of agricultural lands on the Mediterranean coast in Türkiye and scenario-based modelling of urban growth
(2023-01-01) Isinkaralar O.; Isinkaralar K.; Yilmaz D.
Digital mapping and predicting the urban growth: integrating scenarios into cellular automata—Markov chain modeling
(2022-12-01) Isinkaralar O.; Varol C.; Yilmaz D.
Predictive modeling and land use/land cover change studies in complex systems are well advanced. Cellular automata (CA)-Markov chain (MC) can be defined as one frequently preferred method for this purpose. This paper aims to adapt the CA-MC model to the simulation of residential areas in the city. The proposed method was tested in the city center of Kastamonu, Türkiye, using four time periods: 1985, 2011, 2015, and 2021. Spatio-temporal change maps were produced using ArcGIS 10.0 software. Land use simulation of the urban center, including residence units for 2031 and 2057, was performed using the integrated CA-MC technique. The method’s suitability was demonstrated with the Kappa index of agreement values (Kstandart: 0.93; Klocation: 0.98; Kno: 0.98; and KlocationStrata: 0.95). Within the scope of the study, two different scenarios were designed as short term (S1) and long term (S2). According to the predictions for 2031, there was a residential area increase of 15% in S1 and 29% in S2. When we reach 2057, these growth values were measured as 50% according to S1 and 72% according to S2.
Effects of nozzle structural parameters on yarn hairiness in jetring spinning system
(2020-01-01) Gulsevincler E.; Usal M.; Yilmaz D.
In this study, the effects of the performance of air nozzles called jetring, which can be connected to a conventional ring spinning machine, over the yarn hairiness values were investigated. To determine the lowest yarn hairiness value, experimental and statistical studies were carried out on various nozzle structural parameters. The response surface methodology was used to optimize the yarn hairiness value. In the experiment, 100% cotton Ne 30/1 yarns were produced. In all jetring yarn productions, the air pressure was kept at 125 kPa (gauge). Hairiness results were analyzed using ANOVA in the Design Expert 11.0 program. Nozzle structural configuration that provided the lowest yarn hairiness according to the statistical model was as follows: twisting chamber diameter Ø2 mm, injector diameter Ø0.5 mm and injector angle 35° as determined. Ne 30/1 100% cotton yarns produced with this nozzle structural configuration, yarn hairiness values were reduced by 12%.
Increasing university students’ awareness about winter sports
(2020-02-29) Eski T.; Ozbal A.F.; Yilmaz D.
The aim of this study is to determine awareness levels of university students attending School of Physical Education and Sports about winter sports and to examine the effects of the training program applied within the scope of the study on their cognitive, affective, psychomotor and overall awareness. The study used single-group pre-test and post-test experimental design, which is a quantitative research approach. The participants of the study were 21 students studying Kastamonu University School of Physical Education and Sports. The data collection tools used in the study were ‘Personal Information Form’, which includes questions to obtain data about their demographic information, and ‘Winter Sports Awareness Scale’. The data collected was analysed by using SPSS 20 software. According to the results of the analysis, the changes in cognitive awareness, psychomotor awareness and overall awareness levels according to pre-test and post-test scores were found to be significant while affective awareness levels were not significant.
Modular jet-ring yarn spinning system
(2020-01-01) Gulsevincler E.; Usal M.R.; Yilmaz D.
In this study, a modular nozzle design was developed in which the twist chamber diameter, injector diameter, injector angle and the number of injectors of the nozzle can be optionally changed without the need of conventional manufacturing methods. The developed modular nozzle was compared with conventional nozzles taking into account both experimental and numerical analysis results. Experimental performance tests were conducted on the yarn quality achieved using air twist, which is the subject of the application of the nozzle. In the experimental study, conventional nozzles with the same structural configurations were produced to determine modular nozzle performance. In all jet-ring yarn productions, the air pressure was set at two different values: 75 kPa and 125 kPa (gauge). Yarn hairiness, irregularity and imperfection tests were carried out using an Uster Tester 3. Tensile properties (percentage of elongation and tenacity measured as cN/tex) tests were carried out using an Uster Tensorapid. In the numerical analysis, an Ansys CFX 18.0 computational fluid dynamics program was used for both conventional nozzle and modular nozzle configurations. All parametric study configurations were set separately using an SST turbulence model. Comparing the flow parameters of yarn hairiness (CFD analysis), it was found that increasing vorticity or helicity real eigen values reduced yarn hairiness.
The effect of humidified air on yarn properties in a jet-ring spinning system
(2020-01-01) Gulsevincler E.; Usal M.R.; Yilmaz D.
In this study, the effect of 100% atmospheric relative humidity on yarn properties was investigated using jetring nozzles and compared with the yarn properties of yarns produced with air operated jet-ring nozzles under normal conditions. As a humidification system, a pneumatic conditioner, also known as a lubricant, was used in pneumatic systems. This conditioner was connected just before the pneumatic distributor that supplies air to the nozzles. The tube in stage 2 of the conditioner was filled with pure water at room temperature (25 °C ± 2 °C). The air conditioner dose was adjusted to 100% atmospheric relative humidity. The use of humidified air to jet-ring nozzles had a slight positive effect on all yarn properties (yarn hairiness, yarn irregularity, yarn elongation and yarn tenacity). According to the results, it resulted in a 1% to 3% improvement in yarn quality. This study is the first example and an original study in this field, as there is no study using humidified air in existing jet-ring air nozzle studies. It was proven in this study that humidified air results in a slight improvement in yarn properties.
The effects of structural parameters on tangentially injected highly swirling turbulent tube air flow
(2019-08-01) Gulsevincler E.; Usal M.R.; Yilmaz D.
In the textile industry, air-jet nozzles known as Jetring, Nozzlering, Compact-jet and Siro-jet are used for the final spinning of the yarn. The air flow, which determines the yarn quality and other yarn properties, depends on the flow parameters such as pressure, mass flow rate, and the structural parameters of the air jet nozzle which acting on the flow parameters. In this study, SST turbulence model was selected and 225 kPa (absolute) total pressure was applied to the nozzle injectors. Approximately 2,500,000 tetrahedral elements are used for any geometry in the mesh prepared for parametric study. All parameters solved in ANSYS CFX 18.0 with used parametric study. The structural parameters were subjected to parametric CFD analysis and different flow parameters such as mass flow, swirling number, geometric swirling number, Reynolds number, vorticity, helicity real eigen, velocity, velocity w (z-axis velocity, i.e. twisting chamber axis), total pressure, flow pressure were compared.
Yarn evenness parameters optimization in jetring spinning process
(2020-04-02) Gulsevincler E.; Usal M.R.; Yilmaz D.
In this study, the effects of air nozzles called jetring or nozzlering, on yarn quality which is used as an additional process in conventional ring spinning machines have been investigated. The response surface methodology (RSM) was used to investigate the yarn properties value. In the experiment, Ne30/1 100% cotton fibers were used. In all jetring yarn productions, the air pressure was kept at 125 kPa (gauge). In all samples, the nozzle length was kept 27 mm and twisting chamber diameter was kept Ø2mm. The number of injectors has been kept constant as 4 pieces. Giving the best yarn quality as a result of RSM, injector diameter Ø0.5 mm and injector angle 35° as determined. With this nozzle structural configuration, yarn hairiness values were reduced by 9.2% but yarn irregularity values were increased by 0.7%, yarn elongation values were decreased by 6.2% and yarn tenacity (cN/tex) values decreased to 5.6.