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Alaa A. Abdelrahman,Ismail Esen,Cevat Özarpa,Ramy Shaltout,Mohamed A Eltaher,Amr E. Assie 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.4
The goal of this manuscript is to develop a nonclassical size dependent model to study and analyze the dynamic behaviour of the perforated Reddy nanobeam under moving load including the length scale and microstructure effects, that not considered before. The kinematic assumption of the third order shear deformation beam theory in conjunction with modified continuum constitutive equation of nonlocal strain gradient (NLSG) elasticity are proposed to derive the equation of motion of nanobeam included size scale (nonlocal) and microstructure (strain gradient) effects. Mathematical expressions for the equivalent geometrical parameters due to the perforation process of regular squared pattern are developed. Based on the virtual work principle, the governing equations of motion of perforated Reddy nanobeams are derived. Based on Navier's approach, an analytical solution procedure is developed to obtain free and forced vibration response under moving load. The developed methodology is verified and checked with previous works. Impacts of perforation, moving load velocity, microstructure parameter and nonlocal size scale effects on the dynamic and vibration responses of perforated Reddy nanobeam structures have been investigated in a wide context. The obtained results are supportive for the design of MEMS/NEMS structures such as frequency filters, resonators, relay switches, accelerometers, and mass flow sensors, with perforation.
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Enlargement Ratio May Predict Device Size in Elderly Patients with Atrial Septal
Semi Ozturk,Ahmed Seyfettin Gurbuz,Suleyman Cagen Efe,Mehmet Fatih Yilmaz,Cevat Kirma 대한심장학회 2017 Korean Circulation Journal Vol.47 No.5
Background and Objectives Balloon sizing remains the main technique for determining occluder device size for atrial septal defects (ASDs). New evidence has proposed that accurate estimation of device size could be possible without using the balloon technique. Operators have predicted the amount of possible enlargement depending on their experiences. Thus, selection criteria have mostly relied on personal observations and experiences. The objective of this study was to determine the relationship between age, sex, defect size, and deployed device size based on the balloon technique. Subjects and Methods Sixty-six patients who underwent percutaneous ASD closure with a Cardi-O-Fix occluder between 2011 and 2012 were retrospectively evaluated. Patients whose maximum defect size and device size were available were included. Enlargement amount (EA) (device size−defect size) and enlargement ratio (ER) (EA/defect size) were calculated. The relationship between these 2 calculations and age, sex, and defect size were analyzed. Results EA and ER were 5.2±3.6 mm (min: 0, max: 15, median: 5) and 39.3%±31.5% (min: 0, max: 125, median: 32), respectively. EA and ER did not differ between genders (p=0.800; p=0.430). EA and ER were not correlated with maximum defect size (p=0.310; p=0.050). EA and ER showed no correlation with age (p=0.970; p=0.640). However when patients were dichomotized based on age 40, ER was significantly lower in older group (p=0.030). Unexpectedly, no difference was observed between the 2 groups in terms of EA (p=0.110). Size of deployed device had a strong correlation with defect size measured with two-dimensional (2D) transesophageal echocardiography (TEE; device size=1.1177×TEE defect size+3.5297; R=0.84; p<0.010). Conclusion EA and ER did not show a significant correlation with sex and defect size in our study. Patients older than 40 had a significantly lower ER compared to younger patients. Device size was strongly correlated with defect size measured with TEE.
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