Pipe bends exist in different angle forms and their cross sections are integrated with a continuous varying initial geometric imperfection. The literature shows that equations for determining the ...plastic collapse moment of pipe bends having initial imperfection under internal pressure and bending moment are limited to
90
∘
bend angle. It is also identified from literature that the plastic collapse moment has been changed considerably due to initial geometric imperfection. In present work, based on available mathematical formulations, Python script is implemented for modeling
30
∘
to
180
∘
initially imperfect actual cross sections pipe bends. The nonlinear three-dimensional finite element analyses are carried out for modeled pipe bends under internal pressure and in-plane closing bending considering strain-hardening material model and plastic collapse moments are determined in each case using twice-elastic-slope method. The results reveal that initially imperfect pipe bends have lower collapse moment values than circular pipe bends for unpressurized and lower pressurized conditions. At higher pressure, initial imperfection tends to increase collapse moment. Based on results, improved set of empirical equations are provided for determining plastic collapse moment of
30
∘
–
180
∘
pipe bends of more accurate cross section for a wide range of modeling parameters.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This study was intended to assess the utility of hyaluronic acid dermal fillers in patients who do not wish surgery in addition to the patients with minor post-surgery asymmetries. This was a ...prospective study which included post-surgery patients for minor nasal asymmetries, patients unwilling for surgery and those waiting for revision surgery. It is of great use in candidates who do not wish surgery but had the desire for different nasal appearance especially for important life events like marriage etc. This study included 20 patients with follow up period of 18 months. The results were compared on Nasal Imperfection Scale and Rhinoplasty Outcome Evaluation along with pre and post injection photographs. Nasal Imperfection Scale difference of 5 and Rhinoplasty Outcome Evaluation Scale differential of 50 is considered to be significant, which was observed in all individual cases. The growing need of medical rhinoplasty by the patient as well as surgeons has led to the introduction of fillers. Hyaluronic acid fillers are safe, easy and effective dermal fillers for patients undergoing all the expected indications of medical rhinoplasty. There is also growing number of candidates who wish for a ‘nose job’ for desired changes without coming under surgeon’s scalpel. Our clinical experience with 20 patients has been described with satisfactory results.
In spite of recent advancements in reliability analysis, high-dimensional and low-failure probability problems remain challenging because many samples and function calls are required for an accurate ...result. Function calls lead to a sharp increase in computational cost in terms of time. For this reason, an active learning algorithm is proposed using Kriging metamodel, where an unsupervised algorithm is used to select training samples from random samples for the first and second iterations. Then, the metamodel is improved iteratively by enriching the concerned domain with samples near the limit state function and samples obtained from a space-filling design. Hence, rapid convergence with the minimum number of function calls occurs using this active learning algorithm. An efficient stopping criterion has been developed to avoid premature or late-mature terminations of the metamodel and to regulate the accuracy of the failure probability estimations. The efficacy of this algorithm is examined using relative error, number of function calls, and coefficient of efficiency in five examples which are based on high-dimensional and low-failure probability with random and interval variables.
•An active learning algorithm is proposed to estimate failure probability with less computational effort.•A stopping criterion is suggested to overcome the shortcoming of premature for high-dimensional and low-failure probability problems.•The efficacy of the active learning procedure is examined using relative error (∈Pf), number of function calls (Ncall), and coefficient of efficiency (CoE).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Aim
This study aims to investigate the advantages of canal wall reconstruction mastoidectomy (C.W.R.) over the canal wall down (CWD) mastoidectomy.
Material and method
A prospective study was ...conducted on sixty patients with cholesteatoma who underwent operation from September 2010 to October 2016. Patients were divided into two groups: “Group A," posterior canal wall reconstruction group (C.W.R.) with 28 patients (28 ears) and “Group B” which included 32 patients (32 ears) in whom canal wall down mastoidectomy (CWD) was done without reconstruction. The patients were followed up at 3 months and 6 months postoperatively with otoendoscopy to look for recurrence or residual disease, the occurrence of any complications, and for hearing assessment.
Results
Group A (C.W.R.) patients were cosmetically better, and none had postoperative cavity problems. While in Group B (CWD), 16 patients (50%) had a cavity problem. Group A CWR group also had early epithelization. Both methods had hearing improvement postoperatively. Group A had more hearing improvement than Group B.
Conclusion
The C.W.R. method is a safe method for eliminating the problem of the mastoid cavity. This surgery can be easily taught and applied universally in all cholesteatoma patients as a primary treatment. The C.W.R. technique provides improved exposure to the middle ear without creating a mastoid bowl, which significantly reduces the incidence of residual and recurrent disease. These results indicate that the C.W.R. method is better than the CWD operation.
An implicit limit state function is predicted with a support vector machine (SVM) for reliability analysis of engineering structures to reduce the number of finite element analyses. The accuracy and ...predictability of the SVM method are reduced considerably by noise in data. In this paper, density-based spatial clustering of applications with noise (DBSCAN) is applied to reduce the noise in training samples for SVM regression. Then, the SVM model is linked with Monte Carlo simulation (MCS) to find out the reliability of the engineering structures. Four different examples of static and dynamic problems are solved to show acceptability and efficiency of the proposed method. It is observed that the proposed method is suitable for a smaller number of performance function calls. Direct MCS, artificial neural network-based MCS and response surface methods have been used to examine the effectiveness of the algorithm.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
The present study addresses outcomes of extensive nonlinear finite element analyses concerning a diverse geometric spectrum ranging from 30° to 180° pipe bend configurations accounting for the ...initial geometric deformations of the cross-sections resulting from the bending fabrication process. Pipe bends are modeled with the realistic and accurate cross-section by incorporating initial ovality and thinning/thickening (together called initial geometric imperfection) up to 20%. The modeled pipe bends are loaded by in-plane opening moment and internal pressure, considering material models of elastic-perfectly-plastic (EPP) and strain-hardening (SH). The detailed finite element results show that the presence of initial imperfection has a pronounced impact on the plastic collapse moment. At the lower magnitude of applied pressure, the initial imperfection decreases collapse moment of deformed pipe bends significantly as compared to that of circular cross-sectioned pipe bends. At the higher pressure values, the negative effect of initial imperfection decreases with increased pressure for thinner pipe bends. Based on the results of the conducted finite element analyses, governing empirical equations are formulated to predict the collapse moments of pressurized 30° to 180° thin-walled pipe bends with more realistic cross-section employing EPP and SH models.
•Nonlinear analysis of 30°to 180°pipe bends with initial geometric imperfection.•Elastic-perfectly plastic and strain-hardening materials are used for analysis.•The initial geometric imperfection produces negative effect on collapse moment.•Collapse moment equations are proposed for 30°to 180°pressurized pipe bends.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Sustainable development pickup its importance as population of world is increasing day by day. Demand and supply of natural resource in construction of road is facing great challenge for ...world pavement industry. Parallel to this, there was big challenge to dispose construction and demolition(C&D) waste according to environmental and economic growth of society. This paper focused on review of literature in use of C&D waste in road construction and on suitable alternative materials, better performance of road as well as the gap in the existing knowledge in construction. Some practical problem, suitability of C&D waste as road aggregate is also discussed.
► Statistical characterisation of primary stress index B2 considering geometric/fabrication uncertainties. ► Using Monte Carlo simulation techniques along with 3D nonlinear finite element analyses. ► ...Considered 90° thin stainless steel pipe bends subjected to in-plane closing moment, without temperature effects. ► The code-based expression for B2 is revised with a random variable K replacing the constant numerator. ► The statistics of K are provided for the different pipe nominal dimensions.
In recent years, the necessity of reliability-based design has received significant attention from researchers working in the area of pressure vessels and nuclear piping. Preliminary guidelines have been formulated for the reliability-based design of straight pipes using the load and resistance factor design (LRFD) format. In order to formulate similar LRFD design equations for pipe bends and elbows, the first step is a statistical characterisation of the stress indices B1 and B2, which play a significant role for the stress analysis of bend geometry. This paper focuses on the statistical characterisation of B2, which arises due to fabrication/geometric uncertainties, for a thin stainless steel pipe with a 90° bend, subjected to in-plane closing moment. Based on Monte Carlo simulation and nonlinear finite element analyses, the code-based expression for B2 is revised with a random variable K replacing the constant numerator. The statistics for K are provided for different pipe nominal dimensions. The overall mean value of K indicates that the existing code provision gives a conservative estimate of plastic collapse moment for pipe bends subjected to in-plane closing bending moments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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