Vibration measurement and vulnerability analysis of a power plant cooling system

Anil, Ozgur,Akbas, Sami Oguzhan,Kantar, Erkan,Gel, A. Cem Techno-Press 2013 Smart Structures and Systems, An International Jou Vol.11 No.2

During the service life of a structure, design complications and unexpected events may induce unforeseen vibrations. These vibrations can be generated by malfunctioning machinery or machines that are modified or placed without considering the original structural design because of a change in the intended use of the structure. Significant vibrations occurred at a natural gas plant cooling structure during its operation due to cavitation effect within the hydraulic system. This study presents findings obtained from the in-situ vibration measurements and following finite-element analyses of the cooling structure. Comments are made on the updated performance level and damage state of the structure using the results of these measurements and corresponding numerical analyses. An attempt was also made to assess the applicability of traditional displacement-based vulnerability estimation methods in the health monitoring of structures under vibrations with a character different from those due to seismic excitations.

Low velocity impact behavior of concrete beam strengthened with CFRP strip

Erkan Kantar,Özgür Anil 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.12 No.3

Nowadays CFRP (Carbon Fiber Reinforced Polymer) became widely used materials for the strengthening and retrofitting of structures. Many experimental and analytical studies are encountered at literature about strengthening beams by using this kind of materials against static loads and cyclic loads such as earthquake or wind loading for investigating their behavior. But authors did not found any study about strengthening of RC beams by using CFRP against low velocity impact and investigating their behavior. For these reasons an experimental study is conducted on totally ten strengthened RC beams. Impact loading is applied on to specimens by using an impact loading system that is designed by authors. Investigated parameters were concrete compression strength and drop height. Two different sets of specimens with different concrete compression strength tested under the impact loading that are applied by dropping constant weight hammer from five different heights. The acceleration arises from the impact loading is measured against time. The change of velocity, displacement and energy are calculated for all specimens. The failure modes of the specimens with normal and high concrete compression strength are observed under the loading of constant weight impact hammer that are dropped from different heights. Impact behaviors of beams are positively affected from the strengthening with CFRP. Measured accelerations, the number of drops up to failure and dissipated energy are increased. Finite element analysis that are made by using ABAQUS software is used for the simulation of experiments, and model gave compatible results with experiments.

A Study on Finding Optimum Parameters of a Diamagnetically Driven Untethered Microrobot

Anil Demircali,Kadir Erkan,Huseyin Uvet 한국자기학회 2017 Journal of Magnetics Vol.22 No.4

In this study, we present a theoretical and numeric analysis of an untethered microrobot manipulation technique that can be used in a liquid environment. A microrobot, which is levitated on a pyrolytic graphite surface, allows us to achieve high precision positioning (at nano level) and control with lower external magnetic force requirements due to stabilizing manner of its locomotion. Stabilizing microrobot is controlled via a single “lifter magnet” as a driving force that is placed on an automatic micro-stage in order to provide stable-motion about x, y and z axes. The presented microrobot is designed for single cell manipulation and transportation operations in liquid medium. It can be used in different experimental setups such as lab-on-a-chips, petri dishes. Here, a new approach to determine an optimal experimental setup of the diamagnetically levitated microrobot, which provides the most effective and possible microrobot control, is explained with FEM (Finite Element Method) analysis and required background information. For such untethered microrobot control experiments in a FEM program, determination of the size of materials used, selection criteria, required magnetic force effects, and optimum pyrolytic graphite sizes are discussed in detail. To do that, our proposed analysis method suggests how to construct such an FEM model parametrically in COMSOL<SUP>®</SUP>. Before starting the experimental work, the effects of the material and dimensions of each element forming the system on the microrobot are discussed in detail. Moreover, the manipulation technique which revealed the theoretical infrastructure is compared with the numerical calculations and the results are shown to be compatible with each other.

Vibration measurement and vulnerability analysis of a power plant cooling system

Özgür ANIL,Sami Oğuzhan AKBAŞ,Erkan KANTAR,A. Cem GEL 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.11 No.2

During the service life of a structure, design complications and unexpected events may induce unforeseen vibrations. These vibrations can be generated by malfunctioning machinery or machines that are modified or placed without considering the original structural design because of a change in the intended use of the structure. Significant vibrations occurred at a natural gas plant cooling structure during its operation due to cavitation effect within the hydraulic system. This study presents findings obtained from the in-situ vibration measurements and following finite-element analyses of the cooling structure. Comments are made on the updated performance level and damage state of the structure using the results of these measurements and corresponding numerical analyses. An attempt was also made to assess the applicability of traditional displacement-based vulnerability estimation methods in the health monitoring of structures under vibrations with a character different from those due to seismic excitations.

Inflammatory biomarkers may predict response to phosphodiesterase type 5 inhibitor treatment in patients with erectile dysfunction

Metin Kilic,Anil Erkan,Salim Zengin,Gokce Dundar,Caglar Boyaci 대한비뇨의학회 2023 Investigative and Clinical Urology Vol.64 No.4

Purpose: In this study, we aimed to evaluate the clinical utility of the neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), lymphocyte/monocyte ratio (LMR), and monocyte/high-density lipoprotein cholesterol ratio (MHR) in predicting response to a phosphodiesterase type 5 inhibitor (PDE5i) when used as the first-line medical treatment of erectile dysfunction (ED). Materials and Methods: This study prospectively included 185 patients who were diagnosed with ED and started PDE5i treatment. After PDE5i treatment, 107 (57.8%) patients with an International Index of Erectile Function-5 (IIEF-5) score below 22 were assigned to Group 1, and 78 (42.2%) patients with an IIEF-5 score of 22 or above were assigned to Group 2. The outcome measures of the study were demographic characteristics and inflammation markers between the groups. Results: The mean IIEF-5 change after PDE5i treatment was 6.1±4.2 points in Group 1 and 11.5±3.2 points in Group 2 (p=0.001). The mean age was 54.6±9.2 years in Group 1 and 47.8±10.3 years in Group 2 (p<0.001), and the median fasting blood glucose values of Groups 1 and 2 were 105 (36) mg/dL and 97 (23) mg/dL, respectively (p=0.010). The LMR and MHR values were 2.39±0.23 and 13.8±7, respectively, for Group 1, and 2.03±0.22 and 17±6.6, respectively, for Group 2 (p=0.044 and p=0.002, respectively). On multivariable analysis, younger age and increased MHR were independent predictors of benefit from PDE5i treatment. Conclusions: This study showed that only MHR as an inflammatory biomarker was an independent predictor for response to PDE5i in the treatment of ED. Also, several factors were predictive of treatment failure.

Estimation of compression strength of polypropylene fibre reinforced concrete using artificial neural networks

R. Tugrul Eredm,Erkan Kantar,Engin Gucuyen,Özgür ANIL 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.5

In this study, Artificial Neural Networks (ANN) analysis is used to predict the compression strength of polypropylene fibre mixed concrete. Polypropylene fibre admixture increases the compression strength of concrete to a certain extent according to mix proportion. This proportion and homogenous distribution are important parameters on compression strength. Determination of compression strength of fibre mixed concrete is significant due to the veridicality of capacity calculations. Plenty of experiments shall be completed to state the compression strength of concrete which have different fibre admixture. In each case, it is known that performing the laboratory experiments is costly and time-consuming. Therefore, ANN analysis is used to predict the 7 and 28 days of compression strength values. For this purpose, 156 test specimens are produced that have 26 different types of fibre admixture. While the results of 120 specimens are used for training process, 36 of them are separated for test process in ANN analysis to determine the validity of experimental results. Finally, it is seen that ANN analysis predicts the compression strength of concrete successfully.