This work proposes a numerical investigation on the effects of damage on the structural response of Reinforced Concrete(RC)bridge structures commonly adopted in highway and railway networks.An effective three-dimensio...This work proposes a numerical investigation on the effects of damage on the structural response of Reinforced Concrete(RC)bridge structures commonly adopted in highway and railway networks.An effective three-dimensional FE-based numerical model is developed to analyze the bridge’s structural response under several damage scenarios,including the effects of moving vehicle loads.In particular,the longitudinal and transversal beams are modeled through solid finite elements,while horizontal slabs are made of shell elements.Damage phenomena are also incorporated in the numerical model according to a smeared approach consistent with Continuum Damage Mechanics(CDM).In such a context,the proposed method utilizes an advanced and efficient computational strategy for reproducing Vehicle-Bridge Interaction(VBI)effects based on a moving mesh technique consistent with the Arbitrary Lagrangian-Eulerian(ALE)formulation.The proposed model adopts a moving mesh interface for tracing the positions of the contact points between the vehicle’s wheels and the bridge slabs.Such modeling strategy avoids using extremely refined discretization for structural members,thus drastically reducing computational efforts.Vibrational analyses in terms of damage scenarios are presented to verify how the presence of damage affects the natural frequencies of the structural system.In addition,a comprehensive investigation regarding the response of the bridge under moving vehicles is developed,also providing results in terms of Dynamic Amplification Factor(DAFs)for typical design bridge variables.展开更多
Modeling and experiments of the growth of ash deposits during the combustion in a drop tube furnace are presented in this paper.An existing deposition model for ash deposit was used,which involves relationship among t...Modeling and experiments of the growth of ash deposits during the combustion in a drop tube furnace are presented in this paper.An existing deposition model for ash deposit was used,which involves relationship among the force of gravity,elastic rebound and adhesion forces acting at the moment of ash particle impaction.Important parameters of this model were determined by the experimental data.The influence of particle size and velocity on deposit geometry was investigated.The growth of ash deposits involving various inlet velocities,tube diameters and tube arrangements were simulated with dynamic mesh technique in Fluent.The simulation results show that particle normal impacted velocity plays an important role due to elastic bounce force term.Deposited geometry was influenced by side velocity(velocity of inlet⁃2),and large velocity has an obvious effect to change the shape of deposition and postpone the steady time.展开更多
A modified paving technique for automatic generation of all-quadrilateral mesh fromarbitrary 2-D geometry is presented. The generated mesh elementS are nearly square andperpendicular to boundaries. Aner the nodes and...A modified paving technique for automatic generation of all-quadrilateral mesh fromarbitrary 2-D geometry is presented. The generated mesh elementS are nearly square andperpendicular to boundaries. Aner the nodes and elementS formation is completed. a fully automaticgrading method is applied to increase the accuracy and reliability of engineering analysis. In thispaper, we mainly describe the theory of mathematical algorithm and present some examples ofautomatically generated mesh.展开更多
电大尺寸目标高频散射场的仿真一般使用物理光学(physical optics,PO)方法,该方法要求对目标使用尺寸为八分之一倍波长的三角网格进行剖分.然而,随着入射波频率增加,网格数目呈指数增长.本文提出基于一倍波长的二次曲面网格的快速PO(fas...电大尺寸目标高频散射场的仿真一般使用物理光学(physical optics,PO)方法,该方法要求对目标使用尺寸为八分之一倍波长的三角网格进行剖分.然而,随着入射波频率增加,网格数目呈指数增长.本文提出基于一倍波长的二次曲面网格的快速PO(fast PO,FPO)方法,该方法使用线性多项式拟合振幅函数,能够有效降低面片数目.与二次多项式拟合振幅函数的快速物理光学方法相比,本文方法避免了菲涅尔积分的求解,且计算速度快1.22倍.为了进一步降低网格数目,提出了自适应网格技术的快速物理光学(FPO based on the adaptive mesh technique,AFPO)方法,允许使用比标准奈奎斯特采样率更少的网格数目对目标进行离散.通过后验误差估计和数值算例对所提出算法的精度和速度进行了验证,结果表明与采用均匀网格剖分的方法相比,AFPO方法所需的面片数目降低89.58%.展开更多
Penile prosthetic implantation represents a cornerstone for patients with organic erectile dysfunction(ED)that is refractory,unsatisfactory,or contra-indicated for other approved medical or mechanical options.In this ...Penile prosthetic implantation represents a cornerstone for patients with organic erectile dysfunction(ED)that is refractory,unsatisfactory,or contra-indicated for other approved medical or mechanical options.In this study,we introduce the“Ghattas technique,”wherein we constructed a polypropylene mesh sheath that surrounds and is fixed to a 13-mm malleable prosthesis cylinder,which can increase the cylinder diameter for cases that need a larger prosthesis.All patients underwent preoperative evaluation and completed the five-item International Index of Erectile Function questionnaire(IIEF-5).Postoperative outcomes were evaluated by IIEF-5 and Erectile Dysfunction Inventory of Treatment Satisfaction(EDITS)questionnaires at final follow-up.The mean age of the 23 included patients was 57.9(standard deviation[s.d.]:11.4)years and the mean duration of ED was 8.5(s.d.:7.9)years.Erection improvement was determined by comparing mean preoperative and postoperative IIEF-5 scores(8.3[s.d.:3.9]vs 24.6[s.d.:0.6],P<0.001).High treatment satisfaction was determined according to a mean EDITS score of 94.9(s.d.:9.9).The proposed Ghattas technique was safe and effective in our patients,and provides opportunity for cases that need a diameter larger than 13 mm.Further studies are needed to confirm these results.展开更多
The paper presents a seismic safety assessment of unreinforced masonry(URM)building using two approaches.The first approach uses the‘Pier Analysis’method,based on the concept of equivalent lateral stiffness,where in...The paper presents a seismic safety assessment of unreinforced masonry(URM)building using two approaches.The first approach uses the‘Pier Analysis’method,based on the concept of equivalent lateral stiffness,where in-plane and out-of-plane actions are considered independently.The second approach is developed with the program SAP2000,where the linear response is evaluated using continuum‘finite element modelling’(FEM).Both methods are compared to evaluate the safety of wall piers and the differences in the outcomes under combined gravitational and lateral seismic forces.The analysis results showed that few wall elements are unsafe in in-plane and out-of-plane tension.It is also observed that the pier analysis method is conservative compared to FEM,but can be used as a simplified and quick tool in design offices for safety assessment,with reasonable accuracy.To safeguard the URM wall piers under lateral loads,a retrofitting technique is adopted by providing vertical and horizontal belts called splints and bandages,respectively,using welded wire mesh(WWM)reinforcement.The study using the‘Pier Analysis’shows that the lateral load capacity of unsafe URM piers can be enhanced up to 3.67 times and made safe using the applied retrofitting technique.Further,the retrofitting design methodology and recommendations for application procedures to on-site URM buildings are discussed in detail.展开更多
基金supported by Ministry of University and Research(MUR)through the Research Grant“PRIN 2020 No.2020EBLPLS”“Programma Operativo Nazionale(PON)2014-2020”.
文摘This work proposes a numerical investigation on the effects of damage on the structural response of Reinforced Concrete(RC)bridge structures commonly adopted in highway and railway networks.An effective three-dimensional FE-based numerical model is developed to analyze the bridge’s structural response under several damage scenarios,including the effects of moving vehicle loads.In particular,the longitudinal and transversal beams are modeled through solid finite elements,while horizontal slabs are made of shell elements.Damage phenomena are also incorporated in the numerical model according to a smeared approach consistent with Continuum Damage Mechanics(CDM).In such a context,the proposed method utilizes an advanced and efficient computational strategy for reproducing Vehicle-Bridge Interaction(VBI)effects based on a moving mesh technique consistent with the Arbitrary Lagrangian-Eulerian(ALE)formulation.The proposed model adopts a moving mesh interface for tracing the positions of the contact points between the vehicle’s wheels and the bridge slabs.Such modeling strategy avoids using extremely refined discretization for structural members,thus drastically reducing computational efforts.Vibrational analyses in terms of damage scenarios are presented to verify how the presence of damage affects the natural frequencies of the structural system.In addition,a comprehensive investigation regarding the response of the bridge under moving vehicles is developed,also providing results in terms of Dynamic Amplification Factor(DAFs)for typical design bridge variables.
基金Sponsored by the General Programs of the National Natural Science Foundation of China(Grant No.51676058).
文摘Modeling and experiments of the growth of ash deposits during the combustion in a drop tube furnace are presented in this paper.An existing deposition model for ash deposit was used,which involves relationship among the force of gravity,elastic rebound and adhesion forces acting at the moment of ash particle impaction.Important parameters of this model were determined by the experimental data.The influence of particle size and velocity on deposit geometry was investigated.The growth of ash deposits involving various inlet velocities,tube diameters and tube arrangements were simulated with dynamic mesh technique in Fluent.The simulation results show that particle normal impacted velocity plays an important role due to elastic bounce force term.Deposited geometry was influenced by side velocity(velocity of inlet⁃2),and large velocity has an obvious effect to change the shape of deposition and postpone the steady time.
文摘A modified paving technique for automatic generation of all-quadrilateral mesh fromarbitrary 2-D geometry is presented. The generated mesh elementS are nearly square andperpendicular to boundaries. Aner the nodes and elementS formation is completed. a fully automaticgrading method is applied to increase the accuracy and reliability of engineering analysis. In thispaper, we mainly describe the theory of mathematical algorithm and present some examples ofautomatically generated mesh.
文摘电大尺寸目标高频散射场的仿真一般使用物理光学(physical optics,PO)方法,该方法要求对目标使用尺寸为八分之一倍波长的三角网格进行剖分.然而,随着入射波频率增加,网格数目呈指数增长.本文提出基于一倍波长的二次曲面网格的快速PO(fast PO,FPO)方法,该方法使用线性多项式拟合振幅函数,能够有效降低面片数目.与二次多项式拟合振幅函数的快速物理光学方法相比,本文方法避免了菲涅尔积分的求解,且计算速度快1.22倍.为了进一步降低网格数目,提出了自适应网格技术的快速物理光学(FPO based on the adaptive mesh technique,AFPO)方法,允许使用比标准奈奎斯特采样率更少的网格数目对目标进行离散.通过后验误差估计和数值算例对所提出算法的精度和速度进行了验证,结果表明与采用均匀网格剖分的方法相比,AFPO方法所需的面片数目降低89.58%.
文摘Penile prosthetic implantation represents a cornerstone for patients with organic erectile dysfunction(ED)that is refractory,unsatisfactory,or contra-indicated for other approved medical or mechanical options.In this study,we introduce the“Ghattas technique,”wherein we constructed a polypropylene mesh sheath that surrounds and is fixed to a 13-mm malleable prosthesis cylinder,which can increase the cylinder diameter for cases that need a larger prosthesis.All patients underwent preoperative evaluation and completed the five-item International Index of Erectile Function questionnaire(IIEF-5).Postoperative outcomes were evaluated by IIEF-5 and Erectile Dysfunction Inventory of Treatment Satisfaction(EDITS)questionnaires at final follow-up.The mean age of the 23 included patients was 57.9(standard deviation[s.d.]:11.4)years and the mean duration of ED was 8.5(s.d.:7.9)years.Erection improvement was determined by comparing mean preoperative and postoperative IIEF-5 scores(8.3[s.d.:3.9]vs 24.6[s.d.:0.6],P<0.001).High treatment satisfaction was determined according to a mean EDITS score of 94.9(s.d.:9.9).The proposed Ghattas technique was safe and effective in our patients,and provides opportunity for cases that need a diameter larger than 13 mm.Further studies are needed to confirm these results.
基金project of Indian Institute of Technology Roorkee(No.EQD-6031/2019-20)for conducting this research work.The support received from the grant authority is gratefully acknowledged.
文摘The paper presents a seismic safety assessment of unreinforced masonry(URM)building using two approaches.The first approach uses the‘Pier Analysis’method,based on the concept of equivalent lateral stiffness,where in-plane and out-of-plane actions are considered independently.The second approach is developed with the program SAP2000,where the linear response is evaluated using continuum‘finite element modelling’(FEM).Both methods are compared to evaluate the safety of wall piers and the differences in the outcomes under combined gravitational and lateral seismic forces.The analysis results showed that few wall elements are unsafe in in-plane and out-of-plane tension.It is also observed that the pier analysis method is conservative compared to FEM,but can be used as a simplified and quick tool in design offices for safety assessment,with reasonable accuracy.To safeguard the URM wall piers under lateral loads,a retrofitting technique is adopted by providing vertical and horizontal belts called splints and bandages,respectively,using welded wire mesh(WWM)reinforcement.The study using the‘Pier Analysis’shows that the lateral load capacity of unsafe URM piers can be enhanced up to 3.67 times and made safe using the applied retrofitting technique.Further,the retrofitting design methodology and recommendations for application procedures to on-site URM buildings are discussed in detail.
