Flexural behaviour of square UHPC-filled hollow steel section beams

Soner Guler,Alperen Çopur,Metin Aydogan 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.43 No.2

This paper presents an experimental investigation of the flexural behavior of square hollow steel section (HSS) beams subjected to pure bending. Totally six unfilled and nine ultra high performance concrete (UHPC)-filled HSS beams were tested under four-point bending until failure. The effects of the steel tube thickness, the yield strength of the steel tube and the strength of concrete on moment capacity, curvature, and ductility of UHPC-filled HSS beams were examined. The performance indices named relative ductility index (RDI) and strength increasing factor (SIF) were investigated with regard to different height-to-thickness ratio of the specimens. The flexural strengths obtained from the tests were compared with the values predicted by Eurocode 4, AISC-LRFD and CIDECT design codes. The results showed that the increase in the moment capacity and the corresponding curvature is much greater for thinner HSS beams than thicker ones. Eurocode 4 and AISC-LRFD predict the ultimate moment capacity of the all UHPC-filled HSS beams conservatively.

Can continuous positive airway pressure improve lower urinary tract symptoms and erectile dysfunction in male patients with severe obstructive sleep apnea syndrome?

Soner Coban,Aygul Gunes,Abdullah Gul,Ali Riza Turkoglu,Muhammet Guzelsoy,Murat Ozturk,Osman Akyuz,Ozgur Ekici 대한비뇨의학회 2020 Investigative and Clinical Urology Vol.61 No.6

Purpose: We aimed to investigate the effect of continuous positive airway pressure (CPAP) administered for the treatment of obstructive upper airway on lower urinary tract symptoms and erectile dysfunction in male patients. Materials and Methods: A total of 626 male with suspected obstructive sleep apnea syndrome (OSAS) were evaluated prospectively. Nocturnal polysomnography tests were administered to the male. After application of the exclusion criteria, 54 patients with severe OSAS (Apnea-Hypopnea Index ≥30) were included in the study. International Prostate Symptom Score (IPSS), International Index of Erectile Function (IIEF-15), and nocturia were assessed in all patients before and after CPAP therapy, and prostate volume, total prostate-specific antigen (tPSA), and uroflowmetric measurements were assessed in patients aged >40 years. Results: The mean age of the 54 patients was 47.06±11.15 years. Post-treatment IIEF scores were better than pre-treatment scores (24.27±7.58 vs. 22.68±8.65, p=0.014). IPSS values, nocturia, and uroflowmetric outcomes significantly improved after CPAP therapy (p<0.05). On the other hand, mean values of body mass index, tPSA, prostate volume, and postvoid residual urine volume did not differ significantly after treatment. Conclusions: CPAP therapy improves lower urinary tract symptoms, nocturia, and erectile dysfunction in male with severe OSAS.

Nonlinear finite element modeling of FRP-wrapped UHPC columns

Soner Guler,Alperen Çopur,Metin Aydogan 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.4

The primary aim of this study is to develop a three dimensional finite element (FE) model to predict the axial stress-strain relationship and ultimate strength of the FRP-wrapped UHPC columns by comparing experimental results. The reliability of four selected confinement models and three design codes such as ACI-440, CSA-S806-02, and ISIS CANADA is also evaluated in terms of agreement with the experimental results. Totally 6 unconfined and 36 different types of the FRP-wrapped UHPC columns are tested under monotonic axial compression. The values of ultimate strengths of FRP-wrapped UHPC columns obtained from the experimental results are compared and verified with finite element (FE) analysis results and the design codes mentioned above. The concrete damage plasticity model (CDPM) in Abaqus is utilized to represent the confined behavior of the UHPC. The results indicate that agreement between the test results and the non-linear FE analysis results is highly satisfactory. The CSA-S806-02 design code is considered more reliable than the ACI-440 and the ISIS CANADA design codes to calculate the ultimate strength of the FRP-wrapped UHPC columns. None of the selected confinement models that are developed for FRP-wrapped low and normal strength concrete columns can safely predict the ultimate strength of FRP-wrapped UHPC columns.

Axial behavior of FRP-wrapped circular ultra-high performance concrete specimens

Soner Guler 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.6

Ultra-High Performance Concrete (UHPC) is an innovative new material that, in comparison to conventional concretes, has high compressive strength and excellent ductility properties achieved through the addition of randomly dispersed short fibers to the concrete mix. This study presents the results of an experimental investigation on the behavior of axially loaded UHPC short circular columns wrapped with Carbon-FRP (CFRP), Glass-FRP (GFRP), and Aramid-FRP (AFRP) sheets. Six plain and 36 different types of FRP-wrapped UHPC columns with a diameter of 100 mm and a length of 200 mm were tested under monotonic axial compression. To predict the ultimate strength of the FRP-wrapped UHPC columns, a simple confinement model is presented and compared with four selected confinement models from the literature that have been developed for low and normal strength concrete columns. The results show that the FRP sheets can significantly enhance the ultimate strength and strain capacity of the UHPC columns. The average greatest increase in the ultimate strength and strain for the CFRP- and GFRP-wrapped UHPC columns was 48% and 128%, respectively, compared to that of their unconfined counterparts. All the selected confinement models overestimated the ultimate strength of the FRP-wrapped UHPC columns.

Leaching kinetics of colemanite in potassium hydrogen sulphate solutions

Soner Kuslu,Rovsen Guliyev,Turan Calban,Sabri Colak 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.1

The aim of the study was to investigate the dissolution kinetics of colemanite in potassium hydrogen sulphate solutions in a mechanical agitation system and to declare an alternative reactant to produce boric acid. Reaction temperature, concentration of potassium hydrogen sulphate, stirring speed, solid/liquid ratio and colemanite particle size were selected as parameters on the dissolution rate of colemanite. The experimental results were successfully correlated by linear regression using Statistica Package Program. Dissolution curves were evaluated in order to test shrinking core models for solid–fluid systems. It was observed that increase in the reaction temperature and decrease in the solid/liquid ratio causes an increase the dissolution rate of colemanite. The dissolution extent is highly increased with increase the stirring speed rate between 100 and 500 rpm and the dissolution extent is slowly increased with increase the stirring speed between 500 and 700 rpm in experimental conditions. The activation energy was found to be 26.34 kJ/mol. The leaching of colemanite was controlled by diffusion through the product (or ash) layer. The rate expression associated with the dissolution rate of colemanite depending on the parameters chosen may be summarized as follows: 1 3(1 X)^2/3+2(1 X)=10.41X<i>C</i>^1.01×<i>W</i>^1.55×<i>D</i>^1.43×(<i>S/L</i>)^0.60×<i>e</i>^(26.34/RT)×<i>t.

Thermoelastic Transition Kinetics of a Gamma Irradiated CuZnAl Shape Memory Alloy

Soner Ozgen,Cengiz Tatar 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.6

Many types of shape memory alloys have been used in nuclear reactors and aerospace applications where they are exposed to high levels of various kinds of radiation. The effect of gamma irradiation on the transformation kinetics of thermoelastic transformations in a shape memory CuZnAl alloy was investigated by differential scanning calorimetry (DSC) with heating/cooling rates of 10, 20, 30 and 40 °C/min. Irradiation doses of 10, 20, 30 and 40 kGy were applied to the samples of the alloy. Changes in Gibbs free energies,entropies and elastic energies were calculated. Reverse transition temperatures As and Af systematically decreased with increasing doses, although forward transition temperatures Ms and Mf underwent a minimum value at a dose of 20 kGy. Hysteresis in the transition temperatures changed as an inverse parabolic function of the irradiation dose. The activation energies of transformations were calculated by using Kissinger and Osawa methods.

Non-Price Competition in the Port Sector: A Case Study of Ports in Turkey

Soner ESMER,Hong-Oanh NGUYEN,Yapa Mahinda BANDARA,Kazım YENİ 한국해운물류학회 2016 The Asian journal of shipping and Logistics Vol.32 No.1

Although the port sector has been facing increasing competition, there is limited research on how ports compete using non-price competition strategies. There are a few studies on non-price competition in the port sector. However they mainly focus on the marketing aspect. This paper seeks to fill this gap in the literature, especially from a combined marketing-economic perspective. Especially the paper’s main objective is to identify the determinants of non-price competition in the port sector and evaluate their effect on various aspects of non-price competition. We start with a general conceptual framework to explain how competition in the sector can be affected by various factors and then propose an analytical framework on non-price competition. The analytical model is then used to support the design of a survey questionnaire. Next, hypothesis tests are conducted using exploratory factor analysis (EFA) and structural equation modeling (SEM) and data collected from a survey of Turkish ports. Based on the analysis results, the implications for port management and future research are also discussed.

Evaluating the effect of donor anxiety levels and lifestyle characteristics on the activation of platelet concentrates

Soner Yılmaz,İbrahim Eker,Elif Elçi,Aysel Pekel,Rıza Aytaç Çetinkaya,Aytekin Ünlü,Cengizhan Açıkel,İsmail Yaşar Avcı 대한혈액학회 2019 Blood Research Vol.54 No.4

BackgroundSmoking, alcohol use, performing regular physical exercise, dietary habits, and anxiety level may cause platelet activation. We aimed to evaluate the anxiety levels, smoking sta-tus, alcohol intake, and sportive habits of donors, and determine their impact on the qual-ity of apheresis-platelets.MethodsState and Transient Anxiety Inventory (STAI) was used to determine the level of donors’anxiety. STAI has two subscales: S-anxiety scale (STAI-I) and T-anxiety scale (STAI-II), each comprising 20 questions rated on a 4-point Likert scale. Data on smoking, alcohol con-sumption, and performing regular physical exercise were obtained from a questionnaire filled out before donation. Flow cytometric analysis was used to quantify activated platelets.ResultsThe STAI-I level of 86 participants was normal, while that of 12 was higher. No significant difference was found in the active platelet absolute count [1.8×1011 (2.7) and 1.4×1011 (1.3), respectively; P=0.665] between donors with normal STAI-I levels and those with higher STAI-I levels. Of 98 donors, 42 had normal STAI-II levels, while 56 had higher STAI-II levels. No significant difference was found in the active platelet absolute count [2.3×1011 (3.1) and 1.5×1011 (2.3), respectively; P=0.224] between donors with normal STAI-II levels and those with higher STAI-II levels. Platelet counts of individuals who perform regular physical exercise were significantly higher than those of individuals who did not perform regular physical exercise (6.3±1.4×1011 vs. 5.5±1.4×1011).ConclusionThe quality of apheresis platelets is not affected by anxiety levels and lifestyle character-istics of blood donors. There is no need to organize apheresis blood donor pool consider-ing with these subjects.

A Simulation for Optimum Terminal Truck Number in a Turkish Port Based on Lean and Green Concept

Soner ESMER,Ismail Bilge CETIN,Okan TUNA 한국해운물류학회 2010 The Asian journal of shipping and Logistics Vol.26 No.2

Ports, from the simple physical sea/land interface they once used to be, have uccessively turned into commerce and industrial centers, then into logistics and distribution platforms, and are now becoming intermodal nodes in international supply chains networks, the ef ciency of which now drives trade competitiveness. With her distinguished location, logistics infrastructure and well quali ed manpower, Turkey has the potential of being a hub country in her region. However, in order to achieve this potential, Turkish ports have to consider both lean and green approaches in their business strategies. Lean system design is the most important initial step for cargo handling operation in order to reach green operation. At this point, the study has aimed to analyze a Turkish container terminal both in terms of lean and green dimensions. Due to the constraints of data, however, the study has only focused on the cargo handling operations. A simulation model has been used to determine the optimum number of ontainer handling equipment to increase the lean capabilities of a Turkish port. Besides, the environmental damage caused by handling equipment in cargo handling operations has been discussed through the study, and the optimal number of equipment minimizing the environment damage has been reached.

3-Arm PEG Based Amphiphilic Polymer Sorbents for Polar and Non-Polar Liquids

Soner Kizil,Hayal Bulbul Sonmez 한국고분자학회 2019 Macromolecular Research Vol.27 No.11

Crosslinked polymer gels are gaining technological and industrial attention due to their sophisticated application features. Herein, a highly effective amphiphilic polymeric network capable of absorbing polar and nonpolar solvents was produced using hydrophilic glycerol ethoxylate, a member of star type polyethylene glycol (s- PEG), and different hydrophobic organosilane monomers by bulk polymerization as utilized under an inert atmosphere. In this context, the preparation of amphiphilic polymeric networks was achieved by the reaction between hydroxyl terminated s- PEG and ethoxysilane terminated organosilane without using any initiator, activator or a catalyst. SEM, FTIR, 13C and 29Si CPMAS NMR and TGA are used for morphological, structural and thermal characterization of the prepared materials. Likewise, the absorption behavior of amphiphilic polymeric networks was determined by measuring their swelling ratios in polar and nonpolar solvents. Because of having a hydrophobic and hydrophilic structure in their 3D polymeric structure, the obtained polymeric networks behave as an organogel in oil medium, while they can prepared as a hydrogel in aqueous medium. The effect of crosslinker’s difference on the swelling capacity of sorbent were researched by comparing different molecular weight of monomers, and it was found that the molecular structure of organosilane monomers had significant influence on the swelling ability of obtained amphiphilic sorbents. By the use of easy preparations, not needing extra agents for the synthesis, having high and quick absorption abilities in organic solvents showed that the resulting amphiphilic sorbent have potential as absorbents for different organic solvents. Also, the degradable features of amphiphilic polymer networks in water open up optimum application opportunities for additional uses, such as with drug delivery agents.