A New Tuned Mass Damper Design Method based on Transfer Functions

Huseyin Cetin,Ersin Aydin 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.10

Tuned mass damper (TMD) is an effective passive device in reducing harmful vibrations as long as they are designed correctly. An optimal TMD design method is proposed based on transfer functions and also differential evolution (DE) algorithm is used. The method includes optimization of all parameters which are the mass, stiffness and damping coefficients of a TMD. By using random vibration theory, the mean-square of top floor absolute acceleration, top floor displacement and the sum of mean-squares of interstorey drifts have been chosen as objective functions to be minimized with respect to upper and lower limits of TMD parameters. In the classical design, the mass is usually chosen by the designer to find the optimum values of the stiffness and damping coefficient. In addition to optimizing stiffness and damping coefficients, in this study TMD mass quantity is also optimized by using DE algorithm to minimize objective functions for TMD design. After that, structure system with TMD is tested under six near fault and three far fault ground motions by evaluating responses of the structure. The results obtained here are compared with the methods available in the literature for verification. Numerical results show that the proposed method iseffective for optimal TMD design.

Evaluation of Changes in Peripheric Biomarkers Related to Blood Brain Barrier Damage in Patients with Schizophrenia and Their Correlation with Symptoms

Ece Yazla,Huseyin Kayadibi,Ihsan Cetin,Unsal Aydinoglu,Mehmet Emrah Karadere 대한정신약물학회 2022 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.20 No.3

Objective: The aim of the study was to evaluate the levels of peripheric biomarkers that have been associated with blood brain barrier (BBB) damage in healthy controls and two groups of patients with schizophrenia, those who received typical-atypical antipsychotics and those who received only atypical antipsychotics. Additionally, we sought relationships between these biomarkers and schizophrenia symptoms. Methods: This study was conducted with the inclusion of 41 healthy volunteers and 75 patients with schizophrenia. The biomarkers measured to evaluate BBB injury were as follows: spectrin breakdown product 145 (SBDP145), spectrin breakdown product 150 (SBDP150), ubiquitin carboxy terminal hydrolase L1 (UCHL1), ubiquitin ligase cullin-3 (cullin), occludin and claudin, which were measured via ELISA. Symptoms of patients with schizophrenia were evaluated with the Scale for the Assessment of Positive Symptoms (SAPS), Scale for the Assessment of Negative Symptoms, the Clinical Global Impression Scale (CGI), and the general assessment of functionality (GAF). Results: Compared to controls, SBDP145 (p = 0.022) and cullin (p = 0.046) levels were significantly higher in patients with schizophrenia receiving atypical antipsychotic treatment. SBDP150 levels were lower in the combination treatment group compared to the control group (p = 0.022). Claudin (p = 0.804), occludin (p = 0.058) and UCHL1 (p = 0.715) levels were similar among groups. In recipients of combination treatment, SBDP145 levels were found to be positively correlated with SAPS-total (r = 0.440, p = 0.036) and SAPS-delusions (r = 0.494, p = 0.017) scores. Conclusion: The relationships demonstrated in this study indicate that more comprehensive research is needed to understand whether BBB defects contribute to clinical characteristics in patients with schizophrenia.

Metastatic Melanoma of the Common Bile Duct Presented with Dyspepsia

Omer Faruk Cetiner,Huseyin Emre Dundar,Sinem Kantarcioglu-Coskun,Serkan Torun,Salih Tokmak 대한소화기학회 2024 대한소화기학회지 Vol.83 No.4

Malignant melanoma (MM) is an aggressive tumor that can metastasize to any organ, but biliary tract metastasis is scarce. We describe a very rare case of MM metastasis to the common bile duct (CBD), presented with only dyspeptic symptoms. The patient had mildly elevated alkaline phosphatase and gamma-glutamyl transferase levels. Magnetic resonance cholangiopancreatography demonstrated a dilated common bile duct with a distal stricture. The MM diagnosis was established with the ampulla of Vater biopsy specimens obtained by endoscopic retrograde cholangiopancreatography (ERCP), and the patient’s symptoms were resolved after biliary stenting. Both primary CBD cancer and other cancer types like MM that metastasize to CBD can cause obstruction and can be manifested only by dyspeptic symptoms. MM metastasis to CBD can cause obstruction manifested only by dyspeptic symptoms without obstructive jaundice. ERCP can be employed as a promising option for treatment and diagnosis. New-onset dyspeptic symptoms in patients with a history of MM should be investigated thoroughly, especially in the context of biliary metastasis.

Control of the flow past a sphere in a turbulent boundary layer using O-ring

Abdulkerim Okbaz,Muammer Ozgoren,Cetin Canpolat,Besir Sahin,Huseyin Akilli 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.35 No.1

This research work presents an experimental study's outcomes to reveal the impact of an O-ring on the flow control over a sphere placed in a turbulent boundary layer. The investigation is performed quantitatively and qualitatively using particle image velocimetry (PIV) and dye visualization. The sphere model having a diamater of 42.5 mm is located in a turbulent boundary layer flow over a smooth plate for gap ratios of 0≤G/D≤1.5 at Reynolds number of 5 × 103 . Flow characteristics, including patterns of instantaneous vorticity, streaklines, time-averaged streamlines, velocity vectors, velocity fluctuations, Reynolds stress correlations, and turbulence kinetic energy (<TKE>), are compared and discussed for a naked sphere and spheres having O-rings. The boundary layer velocity gradient and proximity of the sphere to the flat plate profoundly influence the flow dynamics. At proximity ratios of G/D=0.1 and 0.25, a wall jet is formed between lower side of the sphere and flat plate, and velocity fluctuations increase in regions close to the wall. At G/D=0.25, the jet flow also induces local flow separations on the flat plate. At higher proximity ratios, the velocity gradient of the boundary layer causes asymmetries in the mean flow characteristics and turbulence values in the wake region. It is observed that the O-ring with various placement angles (θ) on the sphere has a considerable alteration in the flow structure and turbulence statistics on the wake. At lower placement angles, where the O-ring is closer to the forward stagnation point of the sphere, the flow control performance of the O-ring is limited; however, its impact on the flow separation becomes pronounced as it is moved away from the forward stagnation point. At G/D=1.50 for O-ring diameters of 4.7 (2 mm) and 7 (3 mm) percent of the sphere diameter, the -ring exhibits remarkable flow control at θ=50° and θ=55° before laminar flow separation occurrence on the sphere surface, respectively. This conclusion is yielded from narrowed wakes and reductions in turbulence statistics compared to the naked sphere model. The O-ring with a diameter of 3 mm and placement angle of 50° exhibits the most effective flow control. It decreases, in sequence, streamwise velocity fluctuations and length of wake recovery region by 45% and 40%, respectively, which can be evaluated as source of decrement in drag force.

Relation between Left Atrial Remodeling in Young Patients with Cryptogenic Stroke and Normal Inter-atrial Anatomy

Mustafa Gökhan Vural,Suha Cetin,Murat Yilmaz,Ramazan Akdemir,Huseyin Gunduz 대한뇌졸중학회 2015 Journal of stroke Vol.17 No.3

Background and Purpose To investigate an association between left atrial (LA) structural and P wave dispersion (PWD) during sinus rhythm, and electrical remodeling in cryptogenic stroke (CS) patients. Methods Forty CS patients and 40 age- and sex-matched healthy controls were enrolled. P wave calculations were based on 12-lead electrocardiography (ECG) at a 50-mm/s-paper speed with an amplitude of 10 mm/mV. Difference between the maximum and minimum P wave duration was the P wave dispersion (PWD=Pmax-Pmin). LA deformation was evaluated by speckle tracking echocardiography within 3 days of the acute event. Results PWD was 30.1±7.0 ms and 27.4±3.5 ms in CS and control group (P=0.02), whereas LA maximum volume index [LAVImax] was 20.4±4.5 mL/m2 and 19.9±2.4 mL/m2 in CS and control group, respectively (P=0.04). While global peak LA strain was [pLA-S] (LA reservoir function) 41.4±6.3% and 44.5±7.1% in CS and control group, (P=0.04), global peak late diastolic strain rate values [pLA-SRa] (LA pump function) were 2.5±0.4% and 2.9±0.5% in CS and control group, respectively (P=0.001). A mild and a strong negative correlation between global pLA-S and LAVImax (r=-0.49; P<0.01), and between PWD and global pLA-S (r=-0.52; P<0.01), respectively, was observed in CS. Conclusions Increased PWD is associated with impaired LA mechanical functions and enlargement, and involved in the pathophysiology of AF or an AF-like physiology in CS.

Association between Sarcopenia and Cognitive Functions in Older Individuals: A Cross-Sectional Study

Busra Yigit,Can Oner,Huseyin Cetin,Engin Ersin Simsek 대한노인병학회 2022 Annals of geriatric medicine and research Vol.26 No.2

Background: Sarcopenia and cognitive disorders are frequently observed in older individuals. This study investigated the relationship between sarcopenia and cognitive function in this population. Methods: This cross-sectional study included 201 participants aged >65 years in Istanbul between July 1, 2020 and January 31, 2021. We screened all participants using the SARC-F (strength, assistance with walking, rising from a chair, climbing stairs, and falls) questionnaire to determine the risk of sarcopenia. Handgrip strength and skeletal muscle mass of participants at risk were measured to diagnose sarcopenia. Sarcopenia severity was evaluated using a 4-m walking speed test. We evaluated the cognitive status of participants using the Standardized Mini-Mental Test (SMMT) and the Standardized Mini-Mental Test for the Untrained (SMMT-E). Results: It was found that 10.9% (n=22) of participants was risky for sarcopenia and 6.0% (n=12) and 33.3% (n=4) had definite and severe sarcopenia, respectively. Examination of the association between cognitive impairment and SARC-F showed that 8.6% (n=14) of participants with normal cognitive function were at risk of sarcopenia compared to 20.5% (n=8) of participants with cognitive impairment (p=0.045). Evaluation of the relationship between cognitive function and sarcopenia status showed that 3.7% (n=6) of participants with normal cognitive function had sarcopenia compared to 15.4% (n=6) among participants with cognitive impairment (p=0.006). Conclusion: The rate of sarcopenia was significantly higher in older individuals with cognitive than those with normal cognitive functions.