Design and optimization of steel portal frames according to Eurocode using genetic algorithm

One of the essential engineer’s jobs is to achieve the most economical technical solutions. Weight optimization is important since it provides a structure that can carry the applied loads in addition to fulfilling the structural requirements. In this project, a Matlab-algorithm has been developed to find the optimum design of steel portal frames according to “Eurocode 3: Design of steel structures” with regard to the weight. To get the final design of the frame, some inputs have to be specified by the user such as the material, the coordinates, the loads and the distribution pattern of the bracings. The algorithm goes through three essential steps before getting the optimal frame: - Analyzing the frame with help of CALFEM-toolbox: In this step, the frame is geometric nonlinearly analyzed due to certain load combination according to the Ultimate Limit State (ULS) and Serviceability Limit State (SLS) criterion. The internal forces and the displacement established and the axial force diagram, shear force diagram, bending moment diagram and the deformed shape of the frame to be calculated and plotted. - Checking the capacity of the frame according to Eurocode: Some constraints with regard to EC should not be violated. These checks may refer to the frame capacity, checking the capacity against the risk of buckling and the deformations which should not be exceed the Serviceability Limit State (SLS) limitations. - Finding the optimal design of the frame using Genetic Algorithm optimization method: Genetic Algorithm (GA) is an iterative searching method based on the evolution of species’ principle. The algorithm repeat the two steps above every iteration cycle trying to find the best design that has the minimum weight without violating the limitations. Since it is an iterative process, the time required to find the optimum design depends on some factors such as the speed of the computer, the number of variables the size of frame mesh etc. The project ends with some testing examples in which a frame with width span of 20 m, and a height of 6.5 m and uniformly distributed loads as snow loads are acting on the roof of the frame. In these examples, the algorithm has been tested to compare the design that have been got in case of fully braced frame, unbraced and by letting the algorithm to find the optimal number and position of the bracings along the frame. Another comparison has been done to see the difference of the design in case of absence /existing of the deformation limitations

Influence of Temperature on the Growth of Vertically Aligned ZnO Nanowires in Wet Oxygen Environment

The nanowires (NWs) of zinc oxide (ZnO) are developed effectively on an n-type silicon substrate through a seed zinc (Zn) layer by a wet oxidation technique. The growth is performed at different temperatures, 650, 750, and 850 °C, in a wet and rich oxygen environment under a flow of oxygen in the presence of water vapor at atmospheric pressure with a heating rate of 100 °C in 30 min. At 415 °C, the oxygen gas is introduced for the oxidation process. The Zn seed layer is deposited by the thermal evaporation technique. The structural, morphological, and optical properties are investigated. The temperature effect on NWs of ZnO growth intensity and their direction are explored. The nanowires are grown vertically oriented at a temperature of T = 750 °C. The ultraviolet (UV) analysis has been exposed in the visible region ranging from 10 nm to 700 nm at UV to visible intensity ratio of 2.22. In addition, X-ray diffraction analysis (XRD) is employed to research the structural properties of NWs of ZnO, and the characterization is verified by a scanning electron microscope (SEM) to investigate the morphology

Prospective observational cohort study on grading the severity of postoperative complications in global surgery research

Background The Clavien–Dindo classification is perhaps the most widely used approach for reporting postoperative complications in clinical trials. This system classifies complication severity by the treatment provided. However, it is unclear whether the Clavien–Dindo system can be used internationally in studies across differing healthcare systems in high- (HICs) and low- and middle-income countries (LMICs). Methods This was a secondary analysis of the International Surgical Outcomes Study (ISOS), a prospective observational cohort study of elective surgery in adults. Data collection occurred over a 7-day period. Severity of complications was graded using Clavien–Dindo and the simpler ISOS grading (mild, moderate or severe, based on guided investigator judgement). Severity grading was compared using the intraclass correlation coefficient (ICC). Data are presented as frequencies and ICC values (with 95 per cent c.i.). The analysis was stratified by income status of the country, comparing HICs with LMICs. Results A total of 44 814 patients were recruited from 474 hospitals in 27 countries (19 HICs and 8 LMICs). Some 7508 patients (16·8 per cent) experienced at least one postoperative complication, equivalent to 11 664 complications in total. Using the ISOS classification, 5504 of 11 664 complications (47·2 per cent) were graded as mild, 4244 (36·4 per cent) as moderate and 1916 (16·4 per cent) as severe. Using Clavien–Dindo, 6781 of 11 664 complications (58·1 per cent) were graded as I or II, 1740 (14·9 per cent) as III, 2408 (20·6 per cent) as IV and 735 (6·3 per cent) as V. Agreement between classification systems was poor overall (ICC 0·41, 95 per cent c.i. 0·20 to 0·55), and in LMICs (ICC 0·23, 0·05 to 0·38) and HICs (ICC 0·46, 0·25 to 0·59). Conclusion Caution is recommended when using a treatment approach to grade complications in global surgery studies, as this may introduce bias unintentionally

The surgical safety checklist and patient outcomes after surgery: a prospective observational cohort study, systematic review and meta-analysis

© 2017 British Journal of Anaesthesia Background: The surgical safety checklist is widely used to improve the quality of perioperative care. However, clinicians continue to debate the clinical effectiveness of this tool. Methods: Prospective analysis of data from the International Surgical Outcomes Study (ISOS), an international observational study of elective in-patient surgery, accompanied by a systematic review and meta-analysis of published literature. The exposure was surgical safety checklist use. The primary outcome was in-hospital mortality and the secondary outcome was postoperative complications. In the ISOS cohort, a multivariable multi-level generalized linear model was used to test associations. To further contextualise these findings, we included the results from the ISOS cohort in a meta-analysis. Results are reported as odds ratios (OR) with 95% confidence intervals. Results: We included 44 814 patients from 497 hospitals in 27 countries in the ISOS analysis. There were 40 245 (89.8%) patients exposed to the checklist, whilst 7508 (16.8%) sustained ≥1 postoperative complications and 207 (0.5%) died before hospital discharge. Checklist exposure was associated with reduced mortality [odds ratio (OR) 0.49 (0.32–0.77); P\u3c0.01], but no difference in complication rates [OR 1.02 (0.88–1.19); P=0.75]. In a systematic review, we screened 3732 records and identified 11 eligible studies of 453 292 patients including the ISOS cohort. Checklist exposure was associated with both reduced postoperative mortality [OR 0.75 (0.62–0.92); P\u3c0.01; I2=87%] and reduced complication rates [OR 0.73 (0.61–0.88); P\u3c0.01; I2=89%). Conclusions: Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine

Critical care admission following elective surgery was not associated with survival benefit: prospective analysis of data from 27 countries

This was an investigator initiated study funded by Nestle Health Sciences through an unrestricted research grant, and by a National Institute for Health Research (UK) Professorship held by RP. The study was sponsored by Queen Mary University of London