• Computers and Concrete
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• v.33 no.3
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• pp.241-250
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• 2024

This article investigates the thermal and post-buckling problems of graphene platelets reinforced metal foams (GPLRMF) beams with initial geometric imperfection. Three distribution forms of graphene platelet (GPLs) and foam are employed. This article utilizes the mixing law Halpin Tsai model to estimate the physical parameters of materials. Considering three different boundary conditions, we used the Euler beam theory to establish the governing equations. Afterwards, the Galerkin method is applied to discretize these equations. The correctness of this article is verified through data analysis and comparison with the existing articles. The influences of geometric imperfection, GPL distribution modes, boundary conditions, GPLs weight fraction, foam distribution pattern and foam coefficient on thermal post-buckling are analyzed. The results indicate that, perfect GPLRMF beams do not undergo bifurcation buckling before reaching a certain temperature, and the critical buckling temperature is the highest when both ends are fixed. At the same time, the structural stiffness of the beam under the GPL-A model is the highest, and the buckling response of the beam under the Foam-II mode is the lowest, and the presence of GPLs can effectively improve the buckling strength.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4295-4306
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• 2023

The vibration of fuel rods in axial flow is a universally recognized issue within both engineering and academic communities due to its significant importance in ensuring structural safety. This paper aims to thoroughly investigate the stability and nonlinear vibration of a fuel rod subjected to axial flow in a newly designed high temperature gas cooled reactor. Considering the possible presence of thermal expansion and large deformation in practical scenarios, the thermal effect and geometric nonlinearity are modeled using the von Karman equation. By applying Hamilton's principle, we derive the comprehensive governing equation for this fluid-structure interaction system, which incorporates the quadratic nonlinear stiffness. To establish a connection between the fluid and structure aspects, we utilize the Galerkin method to solve the perturbation potential function, while employing mode expansion techniques associated with the structural analysis. Following convergence and validation analyses, we examine the stability of the structure under various conditions in detail, and also investigate the bifurcation behavior concerning the buckling amplitude and flow velocity. The findings from this research enhance the understanding of the underlying physics governing fuel rod behavior in axial flow under severe yet practical conditions, while providing valuable guidance for reactor design.

• Journal of radiological science and technology
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• v.32 no.3
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• pp.285-291
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• 2009

The aim of the present study was undertaken to investigate the association between diagnostic indices of metabolic syndrome(MetS) with carotid intima-media thickness using ultrasonography. The participants in the study were 315 male employees without carotid atherosclerosis and other cardiovascular disease. This study was approved by the Institutional Review Board of Occupational Safety and Health Research Institute. Written informed consent for the participants in this study was obtained from all individuals. Anthropometric parameters and biochemical characteristics were done using each specific equipments and the NCEP-ATP III criteria were used to define MetS. They were examined by B-mode ultrasound to measure the carotid intima-media thickness(carotid IMT) at the near and far walls of common carotid and bifurcation(bulb). The mean carotid IMT was $0.739{\pm}0.137\;mm$ and it's thickness significantly increased with the increase in age. Also, amounts of systolic and diastolic blood pressure, triglyceride and fasting glucose were significantly increased with the increase in age. Carotid IMT were significantly correlated with BMI(r=0.170, p=0.004), systolic(r=0.148, p=0.011) and diastolic blood pressure(r=0.123, p=0.036) and HDL-cholesterol(r=-0.164, p=0.005). On multiple logistic regression analysis for the diagnostic indices of MetS, carotid IMT were significantly associated with blood pressure(OR=4.220, p<0.01) and MetS(OR=1.301, p<0.05). The results indicate that blood pressure and MetS are important risk factors for carotid atherosclerosis.

• Journal of Chest Surgery
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• v.31 no.5
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• pp.488-493
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• 1998

In the preoperative evaluation before coronary artery bypass surgery, review of the coronary arteriogram is the most important step. Expected "normal" lumen diameter at a given coronary anatomic location is a basis for quantative estimation of coronary disease severity that could be more useful than the traditional "percent stenosis". The distribution and number of major coronary artery branches are determinants of number of bypass grafts needed. We reviewed the coronary artery anatomy in 174 adult patients who revealed no coronary pathology in angiographic studies done from September 1994 to June 1996. Quantative analysis was done in all cases by a single person using a Computerized System (Arripro 35ⓡ). The results were follows; 1) The mean diametre of left main coronary artery was 4.45 mm(range 2.74~6.72). The pattern of branching was bifurcation in 67.24%, trifurcation in 28.74% and quadrifurcation in 4.02% of the patients. 2) The mean diametre of left anterior descending artery was 3.17 mm(range 2.10~5.85), 2.79 (range 1.55~5.59) and 2.17 mm(range 1.37~3.81) in the proximal, mid, and the distal portions, respectively. The number of diagonal branches of left anterior artery was from one to four(mode=2). 3) The mean diametre of proximal and distal left circumflex artery were 3.17mm(range 1.74~4.89) and 2.19 mm(range 1.21~4.46). The number of obtuse marginal branches of left circumflex artery is from one to six(mode 2). 4) The mean diametre of proximal and distal right coronary artery, the posterior descending artery and the largest posterolateral branch were mean 3.51 mm(range 2.07~5.67), 2.09 mm (range 1.42~3.60), 2.09 mm(range 1.02~3.60) and 2.30 mm(range 1.39~4.39). 5) The right coronary artery dominant was 163 cases(93.68%) of the total 174 cases. 6) The large significant acute marginal artery was visualized in more than half of the people. half of the people.