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Koleksiyondaki öğeler
- MakaleYalnız künye2011Scopus SJRQ1Effects of backfill on seismic behavior of rectangular tanks
Livaoglu, Ramazan; Cakir, Tufan; Dogangun, Adem; Aytekin, Mustafa
The reliability and/or stability of the lifeline structures against failure under seismic loads are of critical concern, and must be studied carefully. Therefore, the main objective of this paper is to demonstrate the commonly encountered backfill effects on the dynamic response of rectangular tanks. However, only the exterior wall of the tank which interacts with both the backfill and fluid is tackled, as each part of the structure shows considerable differences in terms of both the load bearing mechanisms and the geometrical and positional differences. Finite element analyses are employed, taking into consideration the fluid-wall-backfill interaction. The analyses are conducted to observe whether or not both backfill and wall behavior can be affected by variation of the internal friction angle. For that purpose, some comparisons are made on vertical displacements of the backfill, roof displacements, stress responses, etc., by means of internal friction angle variations of the backfill from 25 degrees to 40 degrees. Consequently, it is observed that the variations on maximum vertical displacements are affected considerably. In contrast, the maximum stress responses are affected partially. However, the inertial effects of the backfill show that pseudo-static approximations may be insufficient to understand the dynamic behavior of the backfill-wall-fluid system. (C) 2011 Elsevier Ltd. All rights reserved.
AtıfWoS25OpenAlex23
İncele - BildiriAçık Erişim2015Vibration Control of a Column Using a Gyroscope
Ünker, F.; Çuvalci, O.
In this paper, the characteristics of a vibration control system utilizing a gyro and its effectiveness in the control of the motion subjected to a seismic ground motion acceleration were studied. Lambda gyro design was presented as a vibration absorber for reduction of the column vibration, which has a potential for application to towers, high-rise buildings and other structures. The non-linear motions of the gyro-column system and the equations of motion for the system are derived following energy (Lagrange) based approaches and examples provided. On the other hand, the effect of the angular velocity of the gyroscope is studied, and it is shown that the angular velocity (spin velocity) Omega of gyroscope has a significant effect on the behavior of the dynamic motion. It is also shown how the damper and spring due to the motion between the suporting gimbal and tip mass influence the dynamic behavior of the gyroscope. (C) 2015 The Authors. Published by Elsevier Ltd.
AtıfWoS5İncele - MakaleYalnız künye2015Scopus SJRQ3DRY SLIDING WEAR PROPERTIES OF Al-7Si-4Zn-(0-5)Cu ALLOYS
Alemdag, Y.; Beder, M.
In this study, one ternary Al-7Si-4Zn and five quaternary Al-7Si-4Zn-(1-5) Cu alloys were synthesised by permanent mould casting. Dry sliding friction and wear properties of the alloys were investigated by using ball-on-disc type tester after determining their microstructure and mechanical properties. The microstructure of the Al-7Si-4Zn alloy consisted of aluminium-rich alpha-dendrites, eutectic and primary silicon particles. Addition of copper less than 2% had no considerable effect on the microstructure of ternary alloy, but when the copper content exceeded this level the theta (CuAl2) phase formed in the microstructure of the quaternary alloys. The tensile strength and hardness of the alloys and microhardness of alpha-phase increased with increasing amount of copper but their percentage of elongation decreased with it. Copper addition up to 3% reduced the friction coefficient and volume loss of the alloys, above which they showed an increase. The wear surfaces of the alloys were characterised by smearing and de-lamination, but smearing appeared to be the dominant mechanism for their wear. The highest wear resistance was obtained with the Al-7Si-4Zn-3Cu alloy while the Al-7Si-4Zn alloy had the lowest wear resistance among the alloys tested.
AtıfWoS6İncele - MakaleAçık Erişim2016Evaluation of forest management plans in conjunction with the cadastral information: The case of Agva and Beykoz, Istanbul
Cakir, Gunay; Guler, Alptug; Zengin, Hayati; Degermenci, Ahmet Salih
Determination of land ownership and boundaries is one of the most important purposes of the urban and rural land laws. There can be some boundary problems while preparing forestry area of any urban area when there is not consistency between the borders constructed by different state organizations like land cadastre, forest cadastre and forest management and planning teams. This study aims to illustrate these conflicts in forestry applications process of two different areas (Agva and Beykoz) having different characteristics. The study was carried out in Agva and Beykoz districts in the province of Istanbul and focused on the integration in the land and forest cadastral systems. The Beykoz and Agva Forest Planning Units have different characteristics in terms of population (urban and rural) and social impacts. Analyses of the data obtained from the field studies which it was utilized for the investigation of the data obtained from various base maps, were carried out using GIS software. Many inhabitants of the villages in the Agva Planning Unit had migrated from the district. Thus, in accordance with Boundary Law number of 6831 part of 2/B some parcels of villages in Agva were determined to be acting forest and were reassigned as forest land. In Beykoz, however, areas of this nature were few and the destruction of the forests was great. The spatial analysis of the study made it possible to remove discrepancies occurring in the cadastral situation by preparing forest management plans. Consequently, if land cadastre and forest cadastre units carry out work in coordination to determine the cadastral situation, a basis for forest management plans can be established and cadastral problems greatly reduced.
- MakaleYalnız künye2022Scopus SJRQ2Investigating the Influence of Joint Reinforcements of Portland Cement Concrete Slabs Under Asphalt Concrete Overlays on Vertical Deflections Using Accelerated Pavement Testing
Seferoglu, Mehmet Tevfik; Seferoglu, Aysegul Gunes; Çelik, Muhammet; Akpinar, Muhammet Vefa
Joint gaps between slabs in underlying Portland cement concrete (PCC) pavements are critical factors in the life span of asphalt concrete (AC) overlays. Therefore, being informed about the vertical deflections that may occur around the joints is important. In this study the joints were reinforced with three different materials: ethylene propylene diene monomer (i.e., rubber joint filler [RJF] reinforcement), bitumen-based sealant (i.e., rubber plate [RP] reinforcement), and steel plate (SP) (i.e., SP reinforcement), to limit the vertical movement of the underlying PCC. Tests were conducted at the accelerated pavement testing facility for two different AC overlay thicknesses, 50 mm and 100 mm, during 100,000 passages to investigate the influence of AC overlay thickness variations on slab vertical deflections and to also evaluate types of joint reinforcement on slab vertical deflections. For 50-mm thick AC overlay, the most effective joint reinforcements to prevent deformations caused by loading were RP, RJF, and SP; for a 100-mm thickness, this was determined to be RJF, SP, and RP, respectively.
AtıfWoS1OpenAlex2İncele - BildiriYalnız künye2007Sizing of a spherical shell as variable thickness under dynamicloads
Asçi, Nurcan; Uysal, Habib; Uzman, Omit
In this paper, optimization of a spherical shell under various dynamic loads is investigated. The aim of this optimization problem is to minimize the volume of the shell. Design variables are corner thicknesses of each finite element. Constraints are stresses obtained from von Mises stress criterion not to exceed the yield stress in corner nodal points of each finite element at the top and bottom surfaces of shell and thicknesses are restricted not to be less than 2.5 mm. In addition to shell's own weight, the vertical loads with equal intensity are applied at the nodal points on the upper edge of spherical shell, varying with respect to time function P(t). Time varying load vector is considered three different cases such as step, step after ramp and impulse functions. A program is coded with MapleV for optimization of spherical shell and finite element package program ANSYS is used for structural analysis. Obtained results are presented in graphical and tabular form. Finally, concluded remarks are given.
- MakaleAçık Erişim2011A Different Cause of Trauma: Injury by a Mole Gun
Türkmen, Suha; Aktas, Aydin; Karaca, Yunus; Türedi, Suleyman; Gündüz, Abdulkadir
Although injuries caused by the home-made weapons such as mole guns, which are intended to fight off moles, are rare in Turkey they do still happen. They generally involve minor accidents and cause simple injuries to the hand. In this case we present a patient who involves a trauma to the left hand with fragmental fracture of the first metacarpal caused while checking whether a mole gun had fired or not. This injury is an example of an accident related to primitive, home- made weapons, used particularly in rural areas.
- MakaleYalnız künye2013Scopus SJRQ3COMPARATIVE INVESTIGATION THE USE OF METHANOL AND METHYL TERTIARY BUTYL ETHER IN GASOLINE ON ENGINE PERFORMANCE, CO EMISSIONS AND FUEL COST
Sezer, Ismet; Bilgin, Atilla
This study is concerned with investigating experimentally the effects of methanol and Methyl tert-Butyl Ether (MTBE) blending to base gasoline on the performance CO emissions and fuel cost of a spark ignition (SI) engine. The fuel blends were prepared by addition 5, 10, 15, and 20 vol % of methanol and MTBE with a specified amount of base gasoline. The methanol- and MTBE-gasoline blends were designated as M5, M10, M15, M20, and MTBE5, MTBE10, MTBE15, MTBE20, respectively. Experiments were conducted under various engine speeds, spark timings (STs), and compression ratios (CRs). The engine was operated under wide-open throttle conditions. The results of the study showed that the M5 and MTBE10 blends yield the best engine performance in terms of the brake mean effective pressure (bmep), while the M20 and MTBE15 blends are the best performers in terms of brake thermal efficiency (bte). Moreover, M20 and MTBE10 blends give the minimum CO emission values. The economical analysis performed in the study is based on both the current blending fuel prices in Turkey and brake specific fuel consumption (bsfc) of the engine while using gasoline, methanol-gasoline, and MTBE-gasoline blends. It was obtained that, in contrast to the improvement of engine performance, efficiency and CO emissions, methanol and MTBE blends caused increases in fuel costs because of the expensive methanol and MTBE prices in Turkey. Uncertainty analysis was also performed in this study, and it was found that; the uncertainties in the measurement devices do not have noticeable influences on the variations of engine characteristics.
AtıfWoS3İncele - MakaleYalnız künye2019DETERMINING THE RELATIONSHIP BETWEEN POSTOPERATIVE PAIN AND THE RISK OF FALLS IN OLDER ADULTS
Sayilan, Aylin Aydin; Kulakaç, Nursen; Saltan, Asuman
Introduction: Pain and falling are substantial components of older adults' life. Despite the presence of several plausible mechanisms for pain to contribute to falling, very few studies have investigated this relationship in older adults. This study was designed to determine the relationship between falls associated and postoperative pain in surgical patients aged over 65 years. Material and methods: This cross sectional and descriptive study was conducted at a public hospital between January and June, 2018. The study population consisted of postoperative patients aged 65 years and over, hospitalised in the Urology, General Surgery, and Orthopaedic clinics between the study dates. After demographic knowledge was collected, the Itaki Fall Risk Scale and Visual Analogue Scale were used for the risk of falling and pain level assessments, respectively. Results: The mean age of the participants was 72.14 +/- 8.85 years. A statistically significant relationship was observed between pain levels and the risk of falling in the postoperative period (rho = 0.000). The risk of falling increased in line with pain levels. Patients who were single (rho = 0.01), who had no social security (rho = 0.002), and with chronic disease had a significantly higher risk of falling (rho = 0.003). Conclusions: Pain in older adults may increase the risk of falling after surgery. In clinical and academic studies, it is recommended that pain assessments be included in older adults for the risk of postoperative fall.
AtıfWoS1İncele - MakaleYayıncıda açık erişim2023PSYCHOLOGICAL EFFECTS AND PSYCHOLOGICAL RESILIENCE OF THE COVID-19 OUTBREAK IN TURKEY
Ulutasdemir, Nilgun; Yigitalp Rencber, Sureyya; Öztürk Çopur, Ebru
The population of the cross-sectional and descriptive study consisted of individuals living in Turkey between 19 May and 19 July 2020. Due to the pandemic, 3035 people who agreed to participate in the research were reached via online survey method. Sociodemographic data form and Beck's Anxiety Inventory were used as data collection tools. 59.1% of the participants in the study are women and the average age is 35.16 +/- 13.4. 0.8% of individuals stated that they were infected with coronavirus, 21.4% stated that they had a family member or close circle affected by coronavirus disease, 6.3% stated that they had relatives who died from this disease, and 9.9% stated that they applied for quarantine as a suspected patient. While 89.3% of individuals stated that they stayed at home, 79.2% stated that they had been away from home for the last two weeks. It was found that the mean scores of Beck's Anxiety Inventory were higher in women, those in the older age group, those who were married, those with higher education levels, and those who perceived their socioeconomic status as low. In this study, it was determined that individuals living in Turkey experienced high levels of anxiety due to coronavirus.
- MakaleYalnız künye2024Scopus SJRQ4Efficacy of transarterial chemoembolization treatment with 30-60-μm microspheres in patients with hepatocellular carcinoma
Tonkaz, Mehmet; Nas, Omer Fatih; Erkal Tonkaz, Duygu; Inecikli, Mehmet Fatih; Ongen, Gokhan; Ozkaya, Guven
Background: Chemoembolization with small drug-eluting microspheres is widely used in the treatment of hepatocellular carcinoma (HCC). Objectives: This study aimed to evaluate the efficacy and safety of transarterial chemoembolization with doxorubicin-eluting 30-60-mu m microspheres (DEB-TACE) in patients with Barcelona Clinic Liver Cancer (BCLC) stage A and B HCC. Materials and methods: In this single-center study, 88 patients with HCC (BCLC A/B: 15.9%/84.1%) who underwent 137 DEB-TACE sessions between January 2015 and December 2020 were retrospectively assessed. Response to treatment was assessed 4-8 weeks after each DEB-TACE procedure according to mRECIST (Modified Response Evaluation Criteria in Solid Tumors) criteria. Progression-free survival (PFS), time to progression (TTP), overall survival (OS), and adverse events were recorded. Results: In 88 patients (84.1% males; median age, 66.0 years; range, 22-83), the median follow-up was 17 months (range, 2-64). Eight patients (9.1%) had a complete response, 42 (47.8%) had partial regression, 10 (11.3%) had stable disease, and 28 (31.8%) had progressive disease. There was a statistically significant difference between serum alpha-fetoprotein (AFP) levels before and after DEB-TACE treatment (p < 0.001). The median OS was 17 months (95% confidence interval [CI], 10.3-23.7). Cox regression analyses found that preprocedural serum AFP level (400+ vs. < 400; p = 0.024), Child Pugh classification (B vs. A; p = 0.019), and number of DEB-TACE sessions (1 vs. > 1; p = 0.003) were independent risk factors affecting OS. The median PFS was 8 months (95% CI, 5.8-10.2) and TTP was 6 months (1-14 months). Conclusion: Chemoembolization with 30-60-mu m microspheres is an effective and safe treatment for HCC. The number of DEB-TACE sessions is also one of the factors affecting OS.
- Derleme MakaleYalnız künye2011Scopus SJRQ1Development of hydropower energy in Turkey: The case of Coruh river basin
Akpinar, Adem; Kömürcü, Murat Ihsan; Kankal, Murat
The main objective in doing the present study is to investigate the sustainable development of hydropower plants in the Coruh river basin of Turkey, which is least problem river of Turkey in respect to international cooperation as compared with Turkey's other trans-boundary waters. Initial studies concerning the hydropower production potential in Coruh basin had been carried out by Turkish authorities in the late 1960s. Total installed power capacity and annual average energy generation of 37 dams and run of river (without storage) hydropower plants developed at various project stages by The Electrical Power Resources Survey and Development Administration (EiE) in Coruh basin are 3132.70 MW and 10.55 TWh/yr, respectively. Today, this generation value corresponds 6.45% of Turkey's energy consumption in 2006 while it meets 6.3% of total electricity energy production of Turkey which is equal to 167.9 TINh/yr in 2006. Besides, this potential developed at various project stages in Coruh basin will provide 24.1% of Turkey's hydroelectric energy generation being equal to 43.8 TWh/yr in 2006. (C) 2010 Elsevier Ltd. All rights reserved.
AtıfWoS40OpenAlex54İncele - MakaleYalnız künye2011Scopus SJRQ1Determination of proper peaking time for Ultra-LEGe detector
Karabidak, S. M.; Kaya, S.; Çevik, U.; Çelik, A.
Reducing count losses and pile-up pulse effects in quantitative and qualitative analysis is necessary for accuracy of analysis. Therefore, the proper peaking time for particular detector systems is important. The characteristic X-rays emitted from pure some elements were detected by using an Ultra-LEGe detector connecting a Tennelec TC 244 spectroscopy amplifier at different peaking time modes. Overall pulse widths were determined by an HM 203-7 oscilloscope connecting amplifier. The proper peaking time for Ultra-LEGe is determined as 3.84 mu s. (C) 2011 Elsevier Ltd. All rights reserved.
AtıfWoS6OpenAlex9İncele - MakaleYalnız künye2018Scopus SJRQ2The effect of quench-aging on the mechanical properties of Zn-27Al-1Cu alloy
Aydin, Murat; Senaslan, Fatih
The ternary alloy Zn-27Al-1Cu was produced by permanent mold casting. As-cast alloy was aged for different periods after being subjected to solution treatment followed by water quenching. The microstructure, mechanical properties and fatigue behavior of as-cast and heat-treated alloy were then investigated. The quench-aging eliminated the as-cast dendritic structure and produced a uniform microstructure consisting of large grains combined with precipitates. The hardness and tensile strength generally increased, whereas the ductility slightly decreased with aging time. Under all conditions, the longest fatigue life was obtained from the alloy that had been aged for 0.5 h, while the alloy which had been aged for 10 h exhibited the shortest. The fatigue properties were found to be more dependent on impact toughness and elongation, rather than tensile strength.
AtıfWoS1OpenAlex1İncele - MakaleAçık Erişim2024Evaluation of Antioxidant Properties of Wild and Cultivated Blueberry Leaves and Their Phenolic Compound
Okan, Onur Tolga; Ulusoy, Esra; Öz, Mehmet; Deniz, Ilhan
Aim of study: This study aimed to investigate the antioxidant activity and polyphenol and flavonoid content of blueberry leaves, which could have positive effects on human health. Area of study: The research was conducted in three cities of Turkiye's Karadeniz region, where blueberry cultivation is prevalent: Giresun, Trabzon, and Rize. Material and method: In this study, 29 blueberry leaves (27 cultivated and two wild) were selected as sample materials. The total phenolic content (Folin-Ciocalteu method), total flavonoid content (aluminum (III) chloride method), and total antioxidant capacity (DPPH and FRAP) of the samples were analyzed. Phenolic characterization was performed using HPLC. Main results: The total phenolic content varied between 8.36 and 121.61 mg GAE/g, whereas the total flavonoid content ranged from 0.91 to 3.07 mg QE/g. The results revealed that blueberry leaves had high antioxidant activity and contained considerable amounts of polyphenols and flavonoids. Chlorogenic acid was identified as the dominant compound in all leaves samples. Research highlights: These findings indicate that blueberry leaves could be a valuable source of antioxidants in the food and cosmetic industries, comparable to the fruit itself.
AtıfWoS2OpenAlex2İncele - MakaleAçık Erişim2011Scopus SJRQ1On the numerical solution of the model for HIV infection of CD4+ T cells
Merdan, Mehmet; Gökdogan, Ahmet; Yildirim, Ahmet
In this article, a variational iteration method (VIM) is performed to give approximate and analytical solutions of nonlinear ordinary differential equation systems such as a model for HIV infection of CD4(+) T cells. A modified VIM (MVIM), based on the use of Fade approximants is proposed. Some plots are presented to show the reliability and simplicity of the methods. (C) 2011 Elsevier Ltd. All rights reserved.
AtıfWoS66OpenAlex91İncele - Derleme MakaleYalnız künye2012Scopus SJRQ1RETRACTED: Regional sustainable water and energy development projects: A case of Southeastern Anatolia Project (GAP) in Turkey (Retracted article. See vol. 83, pg. 173, 2018)
Akpinar, A.; Kaygusuz, K.
Southeastern Anatolia Project (GAP) region in Turkey is rich in water for irrigation and hydroelectric power. The Euphrates and Tigris Rivers represent over 28% of the nation's water supply by rivers, and the economically irrigable areas in the region make up 20% of those for the entry country. Turkey has a total gross hydropower potential of 433 GWh/yr, but only 125 GWh/yr of the total hydroelectric potential of Turkey can be economically used. By the construction of new hydropower plants, 36% of the economically usable potential of the country would be tapped. The GAP region has a 22% share of the country's total hydroelectric potential, with plans for 22 dams and 19 hydroelectric power plants. Once completed, 27 billion kWh of electricity will be generated annually. (C) 2011 Elsevier Ltd. All rights reserved.
AtıfWoS11OpenAlex15İncele - MakaleAçık Erişim2015INVESTIGATION OF MECHANICAL PROPERTIES OF MAGNETO-RHEOLOGICAL ETHYLENE PROPYLENE DIENE MONOMER AND NATURAL RUBBER TYPE SYNTHETIC RUBBERS FOR BOTH ISOTROPIC AND ANISOTROPIC SITUATIONS
Mazlum, Ugur; Gümrük, Recep
Magneto-rheological (MR) materials are in a smart material class that has the rheological properties to be quickly and reversibly controlled with the external magnetic field applications. Considering the technological developments the rubber-like smart materials has had a more functional usage area with magneto-rheological effect. This study investigates the axial mechanical properties of magneto-rheological Ethylene Propylene Diene Monomer (EPDM) and Natural Rubber (NR) type synthetic rubbers for isotropic and anisotropic situations. Also, these composite materials were built by means of hot press systems as either isotropic or anisotropic using magnetic field application after addition of ferromagnetic powders. The influence of magnetic field was investigated. In this study, NR rubber was found to be more susceptible in terms of smart material properties unlike EPDM synthetic rubber.
- MakaleYalnız künye2013Antioxidant Analysis Methods and Some Non-Wood Forest Plant Products as Sources of Antioxidants in Eastern Black Sea Region
Okan, Onur Tolga; Varlibas, Hulya; Öz, Mehmet; Deniz, Ilhan
Eastern Black Sea region has wide genetically plant diversity due to physical and different climatic characteristic. These plants, which are potential source of antioxidants, prevent the oxidative stres caused by oxygen and photons at the same time. Interest of antioxidant compound has been increased for last years. The reason of this, it is believed that an increased intake of food, which is rich in natural antioxidant, is associated with a lower risk of degenerative diseases. In this study, 10 plants, which are sources of antioxidant and marketable in Eastern Black Sea region, were chosen. Antioxidant activity and potentials use area of these plants were examined. Moreover, antioxidant compounds and determination of antioxidant activity methods were discussed.
AtıfWoS15İncele - BildiriYalnız künye2017Symmetric and Asymmetric Relationship Between Military Expenditures and Economic Growth in NATO-27: A Panel Bootstrap Granger Causality Approach
Ünver, Mustafa; Türedi, Salih; Topal, Mehmet Hanefi
