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RISS 인기검색어
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- 저자 : Ebrahim Rahimi (검색결과 4 건)
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Effect of Debris on Piers Group Scour: An Experimental Study
Ebrahim Rahimi,Kourosh Qaderi,Majid Rahimpour,Mohammad Mehdi Ahmadi 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.4
Debris accumulation upstream of bridge piers is a destructive agent against the piers stability. In this study, the effect of debrisgeometrical characteristics on the local scour at piers group was investigated. A large set of experimental tests were conducted toinvestigate the effect of piers configurations, as well as, the shape, thickness, length, and position of debris on the dimensions of scourhole. The results showed that the debris with rectangular shape caused the most scour depth. In addition, among the differentconfigurations of bridge piers, the group piers (2 × 2) demonstrated the largest scour hole. In this configuration, high complexinteractions occurred among the flow, sediment and piers which generated strong horseshoe and wake vortices around the piers. Theobservations showed that the maximum depth of scour hole increases as the debris thickness increases. In addition, more the debriseffective length, more the depth of scour hole. In the case of debris with rectangular shape, as the relative thickness of debrisincreased from 0.5 to 2.67, the depth of scour hole increased 67%, 80%, 84% and 104%, in single, side by side, tandem, and grouppiers (2 × 2), respectively. By increasing the distance of debris from the water surface, the depth of scour hole increased at the first,and then decreased when the relative submergence depth of debris became 0.46. In this condition, the debris acted as a collar,prevented the bed from scour. The measured scour depths were compared with common empirical formula, the formula weremodified by considering the experimental results of this study.
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Decomposing gender disparity in total physical activity among Iranian adults
Ebrahim Rahimi,Seyed Saeed Hashemi-Nazari,Koorosh Etemad,Hamid Soori 한국역학회 2017 Epidemiology and Health Vol.39 No.-
OBJECTIVES: While gender differences in physical activity (PA) have been reported, their origin is not well understood. The present study aimed to identify factors contributing to this disparity. METHODS: This was a population-based cross-sectional study based on the 2011 surveillance of risk factors of non-communicable diseases that was conducted among Iranian adults. Multi-staged sampling was performed to obtain the required study sample. The primary outcome was gender differences in the prevalence of sufficient physical activity (SPA). Total physical activity (TPA) was calculated as metabolic equivalents (MET) per minute during a typical week, as recommended by the World Health Organization. On this basis, achieving 600 MET-min/wk or more was defined as SPA. The nonlinear Blinder-Oaxaca decomposition technique was used to explain the disparity. RESULTS: The predicted gap was 19.50%. About one-third of the gap was due to differences in the level of observable covariates. Among them, work status contributed the most (29.61%). A substantial portion of the gap remained unexplained by such differences, of which about 40.41% was related to unobservable variables. The differential effects of standard of living, ethnicity, and smoking status made the largest contribution, accounting for 37.36, 35.47, and 28.50%, respectively. CONCLUSIONS: Interventions to reduce the gender gap in PA should focus on increasing TPA among housewives and women with chronic diseases, as well as those with a higher standard of living. In addition, it is essential to explore the impact of ethnicity and smoking status on women’s TPA in order to promote health.
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Farzad Omidi-Kashani,Ebrahim Ghayem Hasankhani,Mohammad Dawood Rahimi,Reza Khanzadeh 대한정형외과학회 2014 Clinics in Orthopedic Surgery Vol.6 No.2
Background: The two most common types of surgically treated lumbar spondylolisthesis in adults include the degenerative and isthmic types. The aim of this study was to compare the functional outcomes of surgical decompression and posterolateral instrumented fusion in patients with lumbar degenerative and isthmic spondylolisthesis. Methods: In this retrospective study, we reviewed the clinical outcomes in surgically treated patients with single level, low grade lumbar degenerative, and isthmic spondylolisthesis (groups A and B, respectively) from August 2007 to April 2011. We tried to compare paired settings with similar initial conditions. Group A included 52 patients with a mean age of 49.2 ± 6.1 years, and group B included 52 patients with a mean age of 47.3 ± 7.4 years. Minimum follow-up was 24 months. The surgical procedure comprised neural decompression and posterolateral instrumented fusion. Pain and disability were assessed by a visual analog scale (VAS) and the Oswestry Disability Index (ODI), respectively. The Wilcoxon and Mann-Whitney U-tests were used to compare indices. Results: The most common sites for degenerative and isthmic spondylolisthesis were at the L4–L5 (88.5%) and L5–S1 (84.6%) levels, respectively. Surgery in both groups significantly improved VAS and ODI scores. The efficacy of surgery based on subjective satisfaction rate and pain and disability improvement was similar in the degenerative and isthmic groups. Notable complications were also comparable in both groups. Conclusions: Neural decompression and posterolateral instrumented fusion significantly improved pain and disability in patients with degenerative and isthmic spondylolisthesis. The efficacy of surgery for overall subjective satisfaction rate and pain and disability improvement was similar in both groups.
KCI
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