A Comparison between the Thermomechanical and Structural Changes in Textured PET Yarns after Superheated Steam and Dry Heat Treatment

Karakas, Hale-Canbaz The Korean Fiber Society 2004 Fibers and polymers Vol.5 No.1

PET yarns textured at different texturing conditions were treated with superheated steam or dry heat at different temperatures for different times. The effects of the treatment conditions on the thermomechanical and structural changes of the yarn were examined by shrinkage, X-ray diffraction and birefringence measurements. With increase in superheated steam temperature, the crystalline orientation factor and birefringence decreased, whereas crystal size increased. Dry heat treatment had a smaller effect on shrinkage and structural properties in comparison with superheated steam treatment. The additional shrinkage after texturing process was investigated. The effect of heat-setting in both media was more significant at $200^{\circ}C$. The time dependence of the properties was not linear.

A consistent FEM-Vlasov model for hyperbolic cooling towers on layered soil under unsymmetrical wind load

Karakas, Ali I.,Ozgan, Korhan,Daloglu, Ayse T. Techno-Press 2016 Wind and Structures, An International Journal (WAS Vol.22 No.6

In this paper, the analysis of hyperbolic cooling tower on elastic subsoil exposed to unsymmetrical wind loading is presented. Modified Vlasov foundation model is used to determine the soil parameters as a function of vertical deformation profile within subsoil. The iterative parameter updating procedure involves the use of Open Application Programming Interface (OAPI) feature of SAP2000 to provide two way data flow during execution. A computing tool coded in MATLAB employing OAPI is used to perform the analysis of hyperbolic cooling tower with supporting columns over a hollow annular raft founded on elastic subsoil. The analysis of such complex soil-structure system is investigated under self-weight and unsymmetrical wind load. The response of the cooling tower on elastic subsoil is compared with that of a tower that its supporting raft foundation is treated as fixed at the base. The results show that the effect of subsoil on the behavior of cooling tower is considerable at the top and bottom of the wall as well as supporting columns and raft foundation. The application of a full-size cooling tower has demonstrated that the procedure is simple, fast and can easily be implemented in practice.

A novel reference model for dental scanning system evaluation: analysis of five intraoral scanners

Irina Karakas-Stupar,Nicola Ursula Zitzmann,Tim Joda 대한치과보철학회 2022 The Journal of Advanced Prosthodontics Vol.14 No.2

PURPOSE. The aim of this in vitro study was to investigate the accuracy (trueness and precision) of five intraoral scanners (IOS) using a novel reference model for standardized performance evaluation. MATERIALS AND METHODS. Five IOSs (Medit i500, Omnicam, Primescan, Trios 3, Trios 4) were used to digitize the reference model, which represented a simplified full-arch situation with four abutment teeth. Each IOS was used five times by an experienced operator, resulting in 25 STL (Standard Tessellation Language) files. STL data were imported into 3D software (Final Surface®) and examined for inter- and intra-group analyses. Deviations in the parameter matching error were calculated. ANOVA F-test and Kruskal-Wallis test were applied for inter-group comparisons (α = .05); and the coefficient of variation (CV) was calculated for intra-group comparisons (in % ± SD). RESULTS. Primescan (matching error value: 0.015), Trios 3 (0.016), and Trios 4 (0.018) revealed comparable results with significantly higher accuracy compared to Medit i500 (0.035) and Omnicam (0.028) (P < .001). For intra-group comparison, Trios 4 demonstrated the most homogenous results (CV 15.8%). CONCLUSION. The novel reference model investigated in this study can be used to assess the performance of dental scanning technologies in the daily routine setting and in research settings.

Acute Dystonia after Using Single Dose Duloxetine: Case Report

Gorkem Karakas,Ugurlu,Sinay Onen,Deniz BayindirLi,Ali Caykoylu 대한신경정신의학회 2013 PSYCHIATRY INVESTIGATION Vol.10 No.1

Duloxetine is a balanced and potent serotonin and noradrenaline reuptake inhibitor which is known to be effective in depression and anxiety disorders. The common adverse effects include dry mouth, nausea, insomnia, somnolence, dizziness and constipation. Reported adverse effects of the extra pyramidal symptoms (EPS) are rare. In this case, a patient who suffered from acute dystonia, after only one dose of 30 mg duloxetine is presented.

Application of graded harmonic FE in the analysis of 2D-FGM axisymmetric structures

Ali I. Karakas,Ayse T. Daloglu 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.3

A graded harmonic finite element formulation based on three-dimensional elasticity theory is developed for the structural analysis of 2D functionally graded axisymmetric structures. The mechanical properties of the axisymmetric solid structures composed of two different metals and ceramics are assumed to vary in radial and axial directions according to power law variations as a function of the volume fractions of the constituents. The material properties of the graded element are calculated at the integration points. Effects of material distribution profile on the static deformation, natural frequency and dynamic response analyses of particular axisymmetric solid structures are investigated by changing the power law exponents. It is observed that the displacements, stresses and natural frequencies are severely affected by the variation of axial and radial power law exponents. Good accuracy is obtained with fewer elements in the present study since Fourier series expansion eliminates the need of finite element mesh in circumferential direction and continuous material property distribution within the elements improves accuracy without refining the mesh size in axial and radial directions.

Optimal design of a wind turbine supporting system accounting for soil-structure interaction

Ali I. Karakas,Ayse T. Daloglu 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.3

This study examines how the interaction between soil and a wind turbine’s supporting system affects the optimal design. The supporting system resting on an elastic soil foundation consists of a steel conical tower and a concrete circular raft foundation, and it is subjected to wind loads. The material cost of the supporting system is aimed to be minimized employing various metaheuristic optimization algorithms including teaching-learning based optimization (TLBO). To include the influence of the soil in the optimization process, modified Vlasov and Gazetas elastic soil models are integrated into the optimization algorithms using the application programing interface (API) feature of the structural analysis program providing two-way data flow. As far as the optimal designs are considered, the best minimum cost design is achieved for the TLBO algorithm, and the modified Vlasov model makes the design economical compared with the simple Gazetas and infinitely rigid soil models. Especially, the optimum design dimensions of the raft foundation extremely reduce when the Vlasov realistic soil reactions are included in the optimum analysis. Additionally, as the designated design wind speed is decreased, the beneficial impact of soil interaction on the optimum material cost diminishes.

A consistent FEM-Vlasov model for hyperbolic cooling towers on layered soil under unsymmetrical wind load

Ali I. Karakas,Korhan Ozgan,Ayse T. Daloglu 한국풍공학회 2016 Wind and Structures, An International Journal (WAS Vol.22 No.6

In this paper, the analysis of hyperbolic cooling tower on elastic subsoil exposed to unsymmetrical wind loading is presented. Modified Vlasov foundation model is used to determine the soil parameters as a function of vertical deformation profile within subsoil. The iterative parameter updating procedure involves the use of Open Application Programming Interface (OAPI) feature of SAP2000 to provide two way data flow during execution. A computing tool coded in MATLAB employing OAPI is used to perform the analysis of hyperbolic cooling tower with supporting columns over a hollow annular raft founded on elastic subsoil. The analysis of such complex soil-structure system is investigated under self-weight and unsymmetrical wind load. The response of the cooling tower on elastic subsoil is compared with that of a tower that its supporting raft foundation is treated as fixed at the base. The results show that the effect of subsoil on the behavior of cooling tower is considerable at the top and bottom of the wall as well as supporting columns and raft foundation. The application of a full-size cooling tower has demonstrated that the procedure is simple, fast and can easily be implemented in practice.

Effects of Varying Levels of Whole Cottonseed on Blood, Milk and Rumen Parameters of Dairy Cows

Oguz, F. Karakas,Oguz, M.N.,Buyukoglu, T.,Sahinduran, S. Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.6

Four lactating Holstein cows were used in a $4{\times}4$ Latin-square design to determine the effects of various levels of whole cottonseed (WCS) in diets on parameters including milk (yield and fat content), rumen fluid (pH, ammonia and TVFA) and blood (${\beta}$-carotene, vit. A, vit. E, urea, $NH_3$, Ca, P and Mg levels). Cows consumed 0, 1, 2 or 3 kg WCS per day. No significant differences were observed among the groups on analysed parameters except plasma vitamin E concentration. In addition, when the amount of cottonseed was increased, milk yield and milk fat content also tended to increase but this increase was not statistically significant. In conclusion, feeding of WCS up to 3 kg per day with ad libitum maize silage did not cause negative effects on milk yield, milk fat and blood vitamin levels in the short term in dairy cows.

Physical and Comfort Properties of the Hoisery Knit Product Containing Intermingled Nylon Elastomeric Yarn

Ucar, Nuray,Karakas, Hale,Sen, Sibel The Korean Fiber Society 2007 Fibers and polymers Vol.8 No.5

There are several studies related with knitted fabric containing elastomeric yarn. These studies have been carried out only on fabrics containing naked elastomeric yarn, i.e., without intermingling. And most of them have focused on dimensional and extension-recovery properties of the fabric. Of course, intermingling yarn parameters such as number of knots and draw-ratio will affect the properties and performance of the fabrics. This paper presents a study about the effect of draw-ratio and number of knots, which are important parameters in intermingled nylon-elastomeric yarns, on the physical and comfort properties of hosiery knit products. To see the relationship and significance, bivariate correlation analysis and analysis of variance have been carried out. It has been seen that increase of draw ratio and number of knots lead to an increase in dimensional change, stitch density, fabric weight, and lead to a decrease in fabric spirality, abrasion, fabric wicking (wickability in course direction is less than that of wale direction). Fabric thickness increases with an increase in draw ratio and a decrease in number of knots. The number of knots and the draw-ratio do not affect the fabric drying rate. However, an increase in the draw ratio and the number of knots result in an increase in initial water content before beginning the drying process. But, an increase in initial water content is not so high as to affect the drying rate.

PHYSICAL AND CHEMICAL PROPERTIES OF PLANETARY NEBULAE WITH WR-TYPE NUCLEI

DANEHKAR, ASHKBIZ,WESSON, ROGER,KARAKAS, AMANDA I.,PARKER, QUENTIN A. The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

We have carried out optical spectroscopic measurements of emission lines for a sample of Galactic planetary nebulae with Wolf-Rayet (WR) stars and weak emission-line stars (wels). The plasma diagnostics and elemental abundance analysis have been done using both collisionally excited lines (CELs) and optical recombination lines (ORLs). It was found that the abundance discrepancy factors ($ADF{\equiv}ORL/CEL$) are closely correlated with the difference between temperatures derived from forbidden lines and those from $He\;{\small{I}}$ recombination lines, implying the existence of H-deficient materials embedded in the nebula. The $H{\beta}$ surface brightness correlations suggest that they might be also related to the nebular evolution.