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RISS 인기검색어
- 검색키워드
- 저자 : Tarar, Zahid Hassan (검색결과 8 건)
- 무료
- 기관 내 무료
- 유료
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Tarar, Wasim,Herman Shen, M.H.,George, Tommy,Cross, Charles Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.5
An energy-based fatigue life prediction framework was previously developed by the authors for prediction of axial, bending and shear fatigue life at various stress ratios. The framework for the prediction of fatigue life via energy analysis was based on a new constitutive law, which states the following: the amount of energy required to fracture a material is constant. In the first part of this study, energy expressions that construct the constitutive law are equated in the form of total strain energy and the distortion energy dissipated in a fatigue cycle. The resulting equation is further evaluated to acquire the equivalent stress per cycle using energy based methodologies. The equivalent stress expressions are developed both for biaxial and multiaxial fatigue loads and are used to predict the number of cycles to failure based on previously developed prediction criterion. The equivalent stress expressions developed in this study are further used in a new finite element procedure to predict the fatigue life for two and three dimensional structures. In the second part of this study, a new Quadrilateral fatigue finite element is developed through integration of constitutive law into minimum potential energy formulation. This new QUAD-4 element is capable of simulating biaxial fatigue problems. The final output of this finite element analysis both using equivalent stress approach and using the new QUAD-4 fatigue element, is in the form of number of cycles to failure for each element on a scale in ascending or descending order. Therefore, the new finite element framework can provide the number of cycles to failure at each location in gas turbine engine structural components. In order to obtain experimental data for comparison, an Al6061-T6 plate is tested using a previously developed vibration based testing framework. The finite element analysis is performed for Al6061-T6 aluminum and the results are compared with experimental results.
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Development of new finite elements for fatigue life prediction in structural components
Tarar, Wasim,Scott-Emuakpor, Onome,Herman Shen, M.H. Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.6
An energy-based fatigue life prediction framework was previously developed by the authors for prediction of axial and bending fatigue life at various stress ratios. The framework for the prediction of fatigue life via energy analysis was based on a new constitutive law, which states the following: the amount of energy required to fracture a material is constant. In this study, the energy expressions that construct the new constitutive law are integrated into minimum potential energy formulation to develop new finite elements for uniaxial and bending fatigue life prediction. The comparison of finite element method (FEM) results to existing experimental fatigue data, verifies the new finite elements for fatigue life prediction. The final output of this finite element analysis is in the form of number of cycles to failure for each element in ascending or descending order. Therefore, the new finite element framework can provide the number of cycles to failure for each element in structural components. The performance of the fatigue finite elements is demonstrated by the fatigue life predictions from Al6061-T6 aluminum and Ti-6Al-4V. Results are compared with experimental results and analytical predictions.
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Development of new finite elements for fatigue life prediction in structural components
Wasim Tarar,Onome Scott-Emuakpor,M.-H. Herman Shen 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.6
An energy-based fatigue life prediction framework was previously developed by the authors for prediction of axial and bending fatigue life at various stress ratios. The framework for the prediction of fatigue life via energy analysis was based on a new constitutive law, which states the following: the amount of energy required to fracture a material is constant. In this study, the energy expressions that construct the new constitutive law are integrated into minimum potential energy formulation to develop new finite elements for uniaxial and bending fatigue life prediction. The comparison of finite element method (FEM) results to existing experimental fatigue data, verifies the new finite elements for fatigue life prediction. The final output of this finite element analysis is in the form of number of cycles to failure for each element in ascending or descending order. Therefore, the new finite element framework can provide the number of cycles to failure for each element in structural components. The performance of the fatigue finite elements is demonstrated by the fatigue life predictions from Al6061-T6 aluminum and Ti-6Al-4V. Results are compared with experimental results and analytical predictions.
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Wasim Tarar,M.-H. Herman Shen,Tommy George,Charles Cross 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.5
An energy-based fatigue life prediction framework was previously developed by the authors for prediction of axial, bending and shear fatigue life at various stress ratios. The framework for the prediction of fatigue life via energy analysis was based on a new constitutive law, which states the following: the amount of energy required to fracture a material is constant. In the first part of this study, energy expressions that construct the constitutive law are equated in the form of total strain energy and the distortion energy dissipated in a fatigue cycle. The resulting equation is further evaluated to acquire the equivalent stress per cycle using energy based methodologies. The equivalent stress expressions are developed both for biaxial and multiaxial fatigue loads and are used to predict the number of cycles to failure based on previously developed prediction criterion. The equivalent stress expressions developed in this study are further used in a new finite element procedure to predict the fatigue life for two and three dimensional structures. In the second part of this study, a new Quadrilateral fatigue finite element is developed through integration of constitutive law into minimum potential energy formulation. This new QUAD-4 element is capable of simulating biaxial fatigue problems. The final output of this finite element analysis both using equivalent stress approach and using the new QUAD-4 fatigue element, is in the form of number of cycles to failure for each element on a scale in ascending or descending order. Therefore, the new finite element framework can provide the number of cycles to failure at each location in gas turbine engine structural components. In order to obtain experimental data for comparison, an Al6061-T6 plate is tested using a previously developed vibration based testing framework. The finite element analysis is performed for Al6061-T6 aluminum and the results are compared with experimental results.
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Zahid Ijaz Tarar,Umer Farooq,Mustafa Gandhi,Saad Saleem,Ebubekir Daglilar 대한소화기내시경학회 2023 Clinical Endoscopy Vol.56 No.5
Background/Aims: The safety of endoscopic retrograde cholangiopancreatography (ERCP) in hepatic cirrhosis and the impact ofChild-Pugh class on post-ERCP complications need to be better studied. We investigated the post-ERCP complication rates in patientswith cirrhosis compared with those without cirrhosis. Methods: We conducted a literature search of relevant databases to identify studies that reported post-ERCP complications in patientswith hepatic cirrhosis. Results: Twenty-four studies comprising 28,201 patients were included. The pooled incidence of post-ERCP complications in cirrhosiswas 15.5% (95% confidence interval [CI], 11.8%–19.2%; I2=96.2%), with an individual pooled incidence of pancreatitis 5.1% (95% CI,3.1%–7.2%; I2=91.5%), bleeding 3.6% (95% CI, 2.8%–4.5%; I2=67.5%), cholangitis 2.9% (95% CI, 1.9%–3.8%; I2=83.4%), and perforation0.3% (95% CI, 0.1%–0.5%; I2=3.7%). Patients with cirrhosis had a greater risk of post-ERCP complications (risk ratio [RR], 1.41;95% CI, 1.16–1.71; I2=56.3%). The risk of individual odds of adverse events between cirrhosis and non-cirrhosis was as follows: pancreatitis(RR, 1.25; 95% CI, 1.06–1.48; I2=24.8%), bleeding (RR, 1.94; 95% CI, 1.59–2.37; I2=0%), cholangitis (RR, 1.15; 95% CI, 0.77–1.70;I2=12%), and perforation (RR, 1.20; 95% CI, 0.59–2.43; I2=0%). Conclusions: Cirrhosis is associated with an increased risk of post-ERCP pancreatitis, bleeding, and cholangitis.
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Hassan, Syed Tauseef,Danish, Danish,khan, Salah-Ud-Din,Baloch, Muhammad Awais,Tarar, Zahid Hassan Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.12
Looking at the recent studies, nuclear energy and carbon dioxide (CO<sub>2</sub>) emissions nexus shows inconclusive result. To further explain nuclear energy-pollution nexuses this study is an attempt to analyze the impact of nuclear energy on pollution reduction for BRICS countries covering data for the period from 1993 to 2017. This study conducts advanced panel techniques such as Continuously-Updated Fully-Modified (CUP-FM) and Continuously-Updated Bias-Corrected (CUP-BC) for long run estimation. Our results support the notion that nuclear energy reduce CO<sub>2</sub> emissions. Also, renewable energy corrects environmental pollution in BRICS countries. The magnitude of the coefficient of nuclear energy is less as compared to renewable energy, implying that nuclear is less effective in reducing environmental pollution. The findings offer significant policy understandings and suggestions not only for BRICS economies but for developing countries as well in designing suitable nuclear energy-growth-carbon policies.
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Nutritional and biochemical evaluation of sorghum supplemented sourdough flat bread
Tariq Ismail,Saeed Akhtar,Muhammad Riaz,Orner Mukhtar Tarar,Amir Ismail 단국대학교 국제농업협력연구소 2012 단국대학교 국제농업협력연구소 학술대회 Vol.2012 No.1
Wheat flour supplemented with 5, 10, 15, 20 and 25% sorghum flour and sourdough bread made thereof were evaluated for mineral contents, phytic acid, tannin, total phenols and in vitro protein digestibility. Effect of supplementation was assessed on nutritional quality of the sourdough flatbread. Analyses of the sorghum supplemented flours revealed a significant (p<0.05) increase in crude fat(%), crude fiber(%) and NFE (%)with a decreasing pattern in crude protein and ash contents. Sourdough fermentation appeared to improve mineral contents in bread since the concentration of iron, zinc and manganese were increased from 3.07-4.41, 0.87-0.95 and 2.48-2.56 mg/100 g, respectively. Phytic acid (%) and tannin (%) were reduced from 1.14 to 0.57, and 0.40 to 0.22, respectively in flatbread. Total phenols of composite flour decreased from 342 to 104 mg/100 g in sourdough flatbread. Similarly, in vitro protein digestibility was shown to increase from 74.81 to 81.14% apparently due to reduction in concentration of chelating agents by fermentation process. Conclusively, composite flour technology in combination with lactic acid fermentation was found quite successfully exploited to reduce anti-nutritional compounds, enhance availability of minerals and improve the digestibility of non-conventional cereal grains.
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