Evaluation of the natural draught cooling tower shell using linearly and non-linearly numerical analysis

The shell shape of the natural cooling tower determines the sensitivity of the whole structure against wind excitation. This study analyses influence of the tower shell geometric parameters on the structural behavior, evaluated by linearly and nonlinearly numerical analyses. The goal of the study is to give an informative statement for the form-finding process of the cooling tower shell in the engineering practice. The generated 32 towers from an existing cooling tower are linearly analyzed base on the natural frequency. Further three representative models were selected, they were analyzed based on the buckling factor and the reinforced amount required according to a design guideline. The hyperbolic shell with overall radii as small as possible yielded not only a higher first natural frequency, thus less wind-insensitivity, but also a safer buckling behavior and a economical design due to less requirement of concrete and reinforcement. This advantageous structural behavior could be consistently verified in the nonlinear analysis, evaluated by load-deformation curves and damage indices based on the natural frequencies and modal contribution factors

Технология и техника сооружения разведочно-эксплуатационной скважины на Яро-Яхинском нефтегазоконденсатном месторождении (Ямало-Ненецкий автономный округ

Объектом исследования является сооружение разведочно-эксплуатационной скважины на Яро-Яхинском нефтегазоконденсатном месторождении (Ямало-Ненецкий автономный округ). В процессе выполнения работы была рассмотрена геологическая характеристика месторождения, была спроектирована и рассчитана технология строительства скважины, по данным расчетов был произведен подбор оптимального бурового и вспомогательного оборудования.В результате исследования были спроектированы технологические решения на строительство скважины глубиной 5500 м.The object of the study is the construction of an exploratory well at the Yaro-Yakhinsky oil and gas condensate field (Yamalo-Nenets Autonomous Okrug). In the work, the geological characteristics of the field were considered, the well construction technology was designed and calculated, and the optimal drilling and auxiliary equipment was selected according to the calculations. As a result of the study, technological solutions for the 5500 m well construction were designed

The Relationship Between Coronary Artery Calcification and Bone Mineral Density in Patients According to Their Metabolic Syndrome Status

Background and Objectives: The extent of coronary artery calcification (CAC) is closely related to total atherosclerotic plaque burden. However, the pathogenesis of CAC is still unclear. Conditions such as diabetes mellitus, renal failure, smoking, and chronic inflammation have been suggested to link vascular calcification and bone loss. In the present study, we hypothesized that bone loss can contribute to the pathogenesis of CAC in patients with the chronic inflammatory condition that accompanies metabolic syndrome (MetS). The objective of this study was to investigate the relationship between CAC and bone mineral density (BMD) in patients with MetS and in patients without MetS, by using coronary multidetector-row computed tomography (MDCT). Subjects and Methods: Data from 395 consecutive patients was analyzed retrospectively. From the MDCT database, only those patients who underwent both coronary MDCT and dual-energy X-ray absorptiometry within an interval of one month, were selected. The presence of MetS was determined by the updated criteria as defined by the Third Adult Treatment Panel Report of the National Cholesterol Education Program. Results: In patients with MetS, a significant correlation was found between CAC and age {odds ratio (OR)=1.139, 95% confidence interval (CI) 1.080 to 1.201, p<0.001}, CAC and male sex (OR=3.762, 95% CI 1.339 to 10.569, p=0.012), and CAC and T-score of L-spine (OR=0.740, 95% CI 0.550 to 0.996, p=0.047) using a forward multiple logistic regression analysis model including clinical variables of gender, age, lipid profile, body mass index, diabetes mellitus, hypertension, smoking, and BMD. But in patients without MetS, BMD by itself was not found to contribute to CAC. Conclusion: BMD was inversely correlated with CAC only in patients with MetS. This finding suggests that low BMD accompanied by MetS, may have significant clinical implications

Beitrag zur numerischen Analyse der Schädigungsmechanismen von Naturzugkühltürmen

In the present work the progressive damage process of natural draught cooling towers is analysed numerically. A non-linear composite material model for the reinforced concrete is formulated. Regarding the durability a special attention is paid to the cracking process and the determination of the crack width. Within the framework of the static analysis two existing large natural draught cooling towers are analysed considering the geometrical as well as the material non-linearity in detail. The modifications of the dynamic characteristics are identified by means of the natural frequency analysis. The structural damage is quantified by global damage indicators related to the natural frequencies of the cooling tower. The influence of the damage process on the increase of the wind excitation is assessed in consideration of the shifted natural frequencies in the VON-KARMAN wind spectrum. The analyses demonstrate that the shift of the dynamic system due to damage process leads to a progressive damage process in the structure

Beitrag zur numerischen Analyse der Schädigungsmechanismen von Naturzugkühltürmen

In the present work the progressive damage process of natural draught cooling towers is analysed numerically. A non-linear composite material model for the reinforced concrete is formulated. Regarding the durability a special attention is paid to the cracking process and the determination of the crack width. Within the framework of the static analysis two existing large natural draught cooling towers are analysed considering the geometrical as well as the material non-linearity in detail. The modifications of the dynamic characteristics are identified by means of the natural frequency analysis. The structural damage is quantified by global damage indicators related to the natural frequencies of the cooling tower. The influence of the damage process on the increase of the wind excitation is assessed in consideration of the shifted natural frequencies in the VON-KARMAN wind spectrum. The analyses demonstrate that the shift of the dynamic system due to damage process leads to a progressive damage process in the structure