The Effect of the Cutting Parameters on Performance of WEDM

Tosun, Nihat The Korean Society of Mechanical Engineers 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.6

In this study, variations of cutting performance with pulse time, open circuit voltage, wire speed and dielectric fluid pressure were experimentally investigated in Wire Electrical Discharge Machining (WEDM) process. Brass wire with 0.25 mm diameter and AISI 4140 steel with 10 mm thickness were used as tool and work materials in the experiments. The cutting performance outputs considered in this study were surface roughness and cutting speed. It is found experimentally that increasing pulse time, open circuit voltage, wire speed and dielectric fluid pressure increase the surface roughness and cutting speed. The variation of cutting speed and surface roughness with cutting parameters is modeled by using a regression analysis method. Then, for WEDM with multi-cutting performance outputs, an optimization work is performed using this mathematical models. In addition, the importance of the cutting parameters on the cutting performance outputs is determined by using the variance analysis (ANOVA).

Distributed Database Design using Evolutionary Algorithms

Tosun, Umut The Korea Institute of Information and Commucation 2014 Journal of communications and networks Vol.16 No.4

The performance of a distributed database system depends particularly on the site-allocation of the fragments. Queries access different fragments among the sites, and an originating site exists for each query. A data allocation algorithm should distribute the fragments to minimize the transfer and settlement costs of executing the query plans. The primary cost for a data allocation algorithm is the cost of the data transmission across the network. The data allocation problem in a distributed database is NP-complete, and scalable evolutionary algorithms were developed to minimize the execution costs of the query plans. In this paper, quadratic assignment problem heuristics were designed and implemented for the data allocation problem. The proposed algorithms find near-optimal solutions for the data allocation problem. In addition to the fast ant colony, robust tabu search, and genetic algorithm solutions to this problem, we propose a fast and scalable hybrid genetic multi-start tabu search algorithm that outperforms the other well-known heuristics in terms of execution time and solution quality.

Comparison of the Effects of 13-cis Retinoic Acid and Melatonin on the Viabilities of SH-SY5Y Neuroblastoma Cell Line

Tosun, Murat,Soysal, Yasemin,Mas, Nuket Gocmen,Karabekir, Hamit Selim The Korean Neurosurgical Society 2015 Journal of Korean neurosurgical society Vol.57 No.3

Objective : Neuroblastoma is one of common childhood tumors. Although its mortality is very high, there is no effective treatment yet. The aim of this project is to evaluate cytotoxic effects of melatonin (MLT) an endogen hormone and 13-cis retinoic acid (13-cis-RA) also named as isotretinoin an analogue of vitamin A on neuroblastoma SH-SY5Y cell line. Methods : In this study, SH-SY5Y cell line was used. After cell culture, the cells were exposed to different doses of MLT and 13-cis-RA. 24 and 48 hours later. While the viabilities was estimated with MTT cell viability assay test, apoptotic indexes were calculated after staining with TUNEL based apoptosis kit. Results : It was observed that MLT has very effective cytotoxic potential than 13-cis-RA on neuroblastoma cell line. At the same time, when MLT and 13-cis-RA were combined, this effect was potentiated. On the other hand, it was found that the effect of 13-cis-RA individually on neuroblastoma cells was very slight. Conclusion : We suggest that in the treatment of patient with neuroblastoma, MLT is very effective and also this effect can be augmented by combination with 13-cis-RA.

Comparison of superb microvascular imaging and shear wave elastography for assessing liver fibrosis in chronic hepatitis B

Mesude Tosun,Hande Uslu 대한초음파의학회 2022 ULTRASONOGRAPHY Vol.41 No.2

Purpose: The present study investigated the effectiveness and applicability of superb microvascular imaging (SMI) in determining the degree of liver fibrosis noninvasively in comparison with shear wave elastography (SWE).Methods: Ninety-eight consecutive patients with chronic hepatitis B who underwent ultrasound (US)-guided needle biopsy were examined using US combined with SMI and SWE. The predictive performance of the two US techniques in staging liver fibrosis and inflammation was compared with reference to the histological findings obtained from liver biopsy. The intraobserver and interobserver reproducibility of SMI in vascularity scores were evaluated.Results: SWE values and SMI vascular scores were statistically significantly different among fibrosis stages (χ²(3)=76.3, χ²(3)=81.5, P<0.001). The SWE and SMI models significantly predicted fibrosis stages separately, and SMI scores alone predicted fibrosis stages better than SWE values (50.1% for SWE, 63.5% for SMI, P<0.001). A model with both SMI scores and SWE values together explained 73.2% of variance in fibrosis stages. When other clinical and laboratory predictors were added to the model (81.5%, P<0.001), SWE values and SMI scores remained the main predictors of fibrosis stages. SWE and SMI were also applicable in predicting inflammatory grades, explaining 31% and 34% of variance, respectively, and 37.7% when used together (P<0.001).Conclusion: Both SWE and SMI had good diagnostic performance in determining the degree of liver fibrosis in chronic hepatitis B patients. The efficacy of SMI was better than that of SWE. SMI can improve diagnostic performance for staging liver fibrosis and shows potential for estimating necroinflammation of the liver.

Turkish Version of Kolcaba's Immobilization Comfort Questionnaire: A Validity and Reliability Study

Betül Tosun,Ozlem Aslan,Servet Tunay,Aygül Akyüz,Hüseyin Ozkan,Dogan Bek,Semra Açıksoz 한국간호과학회 2015 Asian Nursing Research Vol.9 No.4

Purpose: The purpose of this study was to determine the validity and reliability of the Turkish version of the Immobilization Comfort Questionnaire (ICQ). Methods: The sample used in this methodological study consisted of 121 patients undergoing lower extremity arthroscopy in a training and research hospital. The validity study of the questionnaire assessed language validity, structural validity and criterion validity. Structural validity was evaluated via exploratory factor analysis. Criterion validity was evaluated by assessing the correlation between the visual analog scale (VAS) scores (i.e., the comfort and pain VAS scores) and the ICQ scores using Spearman's correlation test. The Kaiser-Meyer-Olkin coefficient and Bartlett's test of sphericity were used to determine the suitability of the data for factor analysis. Internal consistency was evaluated to determine reliability. The data were analyzed with SPSS version 15.00 for Windows. Descriptive statistics were presented as frequencies, percentages, means and standard deviations. A p value .05 was considered statistically significant. Results: A moderate positive correlation was found between the ICQ scores and the VAS comfort scores; a moderate negative correlation was found between the ICQ and the VAS pain measures in the criterion validity analysis. Cronbach a values of .75 and .82 were found for the first and second measurements, respectively. Conclusions: The findings of this study reveal that the ICQ is a valid and reliable tool for assessing the comfort of patients in Turkey who are immobilized because of lower extremity orthopedic problems.

Evaluating the bond strength between concrete substrate and repair mortars with full-factorial analysis

Kamile Tosun Felekoglu,Burcu Felekoglu,A. Serdar Tasan,Burak Felekoglu 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.5

Concrete structures need repairing due to various reasons such as deteriorative effects, overloading, poor quality of workmanship and design failures. Cement based repair mortars are the most widely used solutions for concrete repair applications. Various factors may affect the bond strength between concrete substrate and repair mortars. In this paper, the effects of polymer additives, strength of the concrete substrate, surface roughness, surface wetness and aging on the bond between concrete substrate and repair mortar has been investigated. Full factorial experimental design is employed to investigate the main and interaction effects of these factors on the bond strength. Analysis of variance (ANOVA) under design of experiments (DOE) in Minitab 14 Statistical Software is used for the analysis. Results showed that the interaction bond strength is higher when the application surface is wet and strength of the concrete substrate is comparatively high. According to the results obtained from the analysis, the most effective repair mortar additive in terms of bonding efficiency was styrene butadiene rubber (SBR) within the investigated polymers and test conditions. This bonding ability improvement can be attributed to the self-flowing ability, high flexural strength and comparatively low air content of SBR modified repair mortars. On the other hand, styrene acrylate rubber (SAR) modified mortars was found incompatible with the concrete substrate.

The Effect of the Cutting Parameters on Performance of WEDM

Nihat Tosun 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.6

In this study, variations of cutting performance with pulse time, open circuit voltage, wire speed and dielectric tluid pressure were experimentally investigated in Wire Electrical Discharge Machining (WEDM) process. Brass wire with 0.25 mm diameter and AISI 4140 steel with 10 mm thickness were used as tool and work materials in the experiments. The cutting performance outputs considered in this study were surface roughness and cutting speed. It is found experimentally that increasing pulse time, open circuit voltage, wire speed and dielectric tluid pressure increase the surface roughness and cutting speed. The variation of cutting speed and surface roughness with cutting parameters is modeled by using a regression analysis method. Then, for WE OM with multi-cutting performance outputs, an optimization work is performed using this mathematical models. In addition, the importance of the cutting parameters on the cutting performance outputs is determined by using the variance analysis (ANOV A).

Distributed Database Design using Evolutionary Algorithms

Umut Tosun 한국통신학회 2014 Journal of communications and networks Vol.16 No.4

The performance of a distributed database system dependsparticularly on the site-allocation of the fragments. Queriesaccess different fragments among the sites, and an originatingsite exists for each query. A data allocation algorithm shoulddistribute the fragments to minimize the transfer and settlementcosts of executing the query plans. The primary cost for a dataallocation algorithm is the cost of the data transmission across thenetwork. The data allocation problem in a distributed database isNP-complete, and scalable evolutionary algorithms were developedto minimize the execution costs of the query plans. In this paper,quadratic assignment problem heuristics were designed and implementedfor the data allocation problem. The proposed algorithmsfind near-optimal solutions for the data allocation problem. Inaddition to the fast ant colony, robust tabu search, and geneticalgorithm solutions to this problem, we propose a fast and scalablehybrid genetic multi-start tabu search algorithm that outperformsthe other well-known heuristics in terms of execution time andsolution quality.

Removal of Exhaust Gas with Advanced Solar Photocatalytic Asphalt Applications

Hümeyra Bolakar Tosun,Alper Alver,Emine Baştürk 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.1

Air pollution in developing and developed countries, especially in urban and industrial areas, is one of the biggest problems of the world. Air pollution can lead to various adverse outcomes such as condensation of the greenhouse effect, acid rain and public health problems. The most significant source of environmental pollution in urban areas is road transportation. This study aimed to determine the effectiveness of solar photocatalytic asphalt materials in reducing the air pollution problem (NOx-nitrogen oxides) caused by the vehicles. The photocatalytic asphalt material, which can be enhanced by solar rays, was produced by applying nano titanium dioxide (TiO2) to asphalt pavements under suitable heat treatment using the spraying and direct additive methods. Scanning electron microscopy and X-ray diffraction analyses were performed to determine the physicochemical and morphological characteristics of the material. Following the characterization study, the photocatalytic activity capacities of the asphalt material produced by both methods was determined. Experiments on NOx removal were carried out under different conditions including catalyst dosage, humidity, temperature, initial NOx concentration and contact time. According to the results, conventional asphalt pavements and TiO2 photocatalytic asphalt pavements were compared in terms of NOx removal efficiency. The optimum conditions were determined as follows: catalyst utilization method = spraying modification, catalyst dosage = 1.5 g/L, humidity = 35%, temperature = 25°C and, initial pollutant concentration CO = 2,500 ppm, NO = 750 ppm, NO2 = 75 ppm and NOx = 825 ppm. In conclusion, it was determined that photocatalysts can be used functionally to solve environmental problems and the solar radiation could be used for the removal of nitrogen and oxide derivatives successfully.

Effects of different topical anesthetics on pain from needle insertion and injection, and the influence of anxiety in patients awaiting endodontic treatment

Aksoy Fatih,Tosun Samet 대한치과보존학회 2022 Restorative Dentistry & Endodontics Vol.47 No.3

Objectives This study aimed to evaluate the effects of 5% lidocaine and 2.5% lidocaine/2.5% prilocaine topical anesthetic on pain during needle insertion and infiltration injection in the labial mucosa of anterior maxillary teeth, and to assess the relationship between patients’ anxiety and pain scores. Materials and Methods The Modified Dental Anxiety Scale questionnaire was applied and recorded. Patients were randomly divided into 4 groups (n = 30), as follows: G1 group: 5% lidocaine and placebo for 1 minute, G2 group: 2.5% lidocaine/2.5% prilocaine and placebo for 1 minute, G3 group: 5% lidocaine and placebo for 3 minutes, and G4 group: 2.5% lidocaine/2.5% prilocaine and placebo for 3 minutes. Before the application of topical anesthesia, one side was randomly selected as the topical anesthesia and the contralateral side as the placebo. The pain levels were measured with Visual Analog Scale (VAS) immediately after needle insertion and injection and were compared. The correlation between anxiety and pain scores was analyzed. Results Administration of 5% lidocaine for 1 minute had significantly higher pain scores for both insertion and infiltration injection than the other groups (p < 0.05). There was a significant moderate positive correlation between dental anxiety and the injection-induced VAS pain score in the placebo side in all groups (p < 0.05). Conclusions Topical anesthetics significantly reduced the pain caused by both needle insertion and injection pain in comparison to the placebo side. The pain scores of patients with dental anxiety were lower on the topical anesthesia compared to the placebo side. Trial Registration Thai Clinical Trials Registry Identifier: TCTR20201217002