Ayas Ahmed - Academia.edu (original) (raw)

Papers by Ayas Ahmed

Research paper thumbnail of Probabilistic estimation of the buckling strength of a CFS lipped-channel section with Type 1 imperfection

Thin-Walled Structures, 2017

Local geometric imperfections in a cold-formed steel (CFS) member can significantly alter the for... more Local geometric imperfections in a cold-formed steel (CFS) member can significantly alter the force-carrying capacity of the member. These are the dents and undulations which occur during cold-rolling, handling, transportation and erection of CFS members. The buckling strength of a lipped channel section with Type 1 local imperfection is obtained and characterised statistically using finite element analyses and Monte Carlo simulations. The reduction in strength due to these imperfections are found to be significant. The quantification of reduction in strength due to these imperfections is found for different values of non-dimensional slenderness ratio. Based on the statistical analysis, design equations and strength curves are recommended for the buckling strength of geometrically imperfect members. Legitimacy of using a generalised statistics of imperfection, in the case of unavailability of specific data for a particular section, is also verified. 1. Type 1: Maximum local imperfection in a stiffened element, such as a web

Research paper thumbnail of Effects Of Damping Parameters On Damping Force Of Two Wheeler Front Suspension

International journal of engineering research and technology, 2013

The automotive suspension plays a crucial role in vehicle safety and driving comfort. One of the ... more The automotive suspension plays a crucial role in vehicle safety and driving comfort. One of the most important components in vehicle suspensions is the damper (or shock absorber). This paper presents a detailed model of a hydraulic shock absorber. The detailed structure includes in the model, are three parameters such as damping hole, suspension velocity, oil viscosity .We analyzed the effect of this three parameters on damping force .The detailed mathematical model is simulated by Minitab14 and simulation results fit experiment data very well this shows that the model can be used to forecast the performance of shock absorber when design In this investigation, an effective approach based on Taguchi method, analysis of variance (ANOVA), multivariable linear regression (MVLR), has been developed to determine the optimum conditions leading to higher damping force. Experiments were conducted by varying damping hole, suspension velocity, and viscosity using L9 orthogonal array of Taguch...

Research paper thumbnail of Analysis Of Damping Force Of Two Wheeler Front Suspension

The automotive suspension plays a crucial role in vehicle safety and driving comfort. One of the ... more The automotive suspension plays a crucial role in vehicle safety and driving comfort. One of the most important components in vehicle suspensions is the damper (or shock absorber). This paper presents a detailed model of a hydraulic shock absorber. The detailed structure includes in the model, are three parameters such as damping hole, suspension velocity, oil viscosity .We analyzed the effect of this three parameters on damping force .The detailed mathematical model is simulated by Minitab14 and simulation results fit experiment data very well this shows that the model can be used to forecast the performance of shock absorber when design In this investigation, an effective approach based on Taguchi method, analysis of variance (ANOVA), multivariable linear regression (MVLR), has been developed to determine the optimum conditions leading to higher damping force. Experiments were conducted by varying damping hole, suspension velocity, and viscosity using L9 orthogonal array of Taguchi method. The present work aims at optimizing damping force process parameters to achieve high high damping force. Experimental results from the orthogonal array were used as the training data for the MVLR model to map the relationship between process parameters and and damping force the experiment was conducted on two wheeler front suspension. From the investigation It concludes that suspension velocity is most influencing parameter followed by damping hole and oil viscosity on damping force

Research paper thumbnail of Correlation between median nerve conduction studies and ultrasonography in cases of carpal tunnel syndrome

The Egyptian Journal of Neurology, Psychiatry and Neurosurgery, 2016

Background Nerve conduction studies (NCS) have long been the only objective measure used to confi... more Background Nerve conduction studies (NCS) have long been the only objective measure used to confirm the diagnosis of carpal tunnel syndrome (CTS), localize median nerve abnormalities, and exclude alternative diagnosis. Ultrasonography (US) can give information about the contents of carpal tunnel (CT) as well as aid in assessing the size of the median nerve (MN). Aim The aim of this study was to detect the relation between median NCS and cross-sectional area (CSA) of the MN measured using US in different grades of CTS. Patients and methods This study was a case–control, age-group matched, cross-sectional one. It included 60 wrists of 30 patients diagnosed with CTS and 60 wrists from 30 controls. Candidates were subjected to clinical assessment, median NCS, and measurement of CSA using US. Results There was a significant positive correlation between CSA of the MN at CT inlet and both motor and sensory responses latencies (r=0.638, P Conclusion US is highly correlated to NCS results in CTS. CSA of the MN at CT inlet measured using ultrasonography can be used as a screening tool for detection as well as discrimination of severe cases of CTS.

Research paper thumbnail of Probabilistic estimation of the buckling strength of a CFS lipped-channel section with Type 1 imperfection

Thin-Walled Structures, 2017

Local geometric imperfections in a cold-formed steel (CFS) member can significantly alter the for... more Local geometric imperfections in a cold-formed steel (CFS) member can significantly alter the force-carrying capacity of the member. These are the dents and undulations which occur during cold-rolling, handling, transportation and erection of CFS members. The buckling strength of a lipped channel section with Type 1 local imperfection is obtained and characterised statistically using finite element analyses and Monte Carlo simulations. The reduction in strength due to these imperfections are found to be significant. The quantification of reduction in strength due to these imperfections is found for different values of non-dimensional slenderness ratio. Based on the statistical analysis, design equations and strength curves are recommended for the buckling strength of geometrically imperfect members. Legitimacy of using a generalised statistics of imperfection, in the case of unavailability of specific data for a particular section, is also verified. 1. Type 1: Maximum local imperfection in a stiffened element, such as a web

Research paper thumbnail of Effects Of Damping Parameters On Damping Force Of Two Wheeler Front Suspension

International journal of engineering research and technology, 2013

The automotive suspension plays a crucial role in vehicle safety and driving comfort. One of the ... more The automotive suspension plays a crucial role in vehicle safety and driving comfort. One of the most important components in vehicle suspensions is the damper (or shock absorber). This paper presents a detailed model of a hydraulic shock absorber. The detailed structure includes in the model, are three parameters such as damping hole, suspension velocity, oil viscosity .We analyzed the effect of this three parameters on damping force .The detailed mathematical model is simulated by Minitab14 and simulation results fit experiment data very well this shows that the model can be used to forecast the performance of shock absorber when design In this investigation, an effective approach based on Taguchi method, analysis of variance (ANOVA), multivariable linear regression (MVLR), has been developed to determine the optimum conditions leading to higher damping force. Experiments were conducted by varying damping hole, suspension velocity, and viscosity using L9 orthogonal array of Taguch...

Research paper thumbnail of Analysis Of Damping Force Of Two Wheeler Front Suspension

The automotive suspension plays a crucial role in vehicle safety and driving comfort. One of the ... more The automotive suspension plays a crucial role in vehicle safety and driving comfort. One of the most important components in vehicle suspensions is the damper (or shock absorber). This paper presents a detailed model of a hydraulic shock absorber. The detailed structure includes in the model, are three parameters such as damping hole, suspension velocity, oil viscosity .We analyzed the effect of this three parameters on damping force .The detailed mathematical model is simulated by Minitab14 and simulation results fit experiment data very well this shows that the model can be used to forecast the performance of shock absorber when design In this investigation, an effective approach based on Taguchi method, analysis of variance (ANOVA), multivariable linear regression (MVLR), has been developed to determine the optimum conditions leading to higher damping force. Experiments were conducted by varying damping hole, suspension velocity, and viscosity using L9 orthogonal array of Taguchi method. The present work aims at optimizing damping force process parameters to achieve high high damping force. Experimental results from the orthogonal array were used as the training data for the MVLR model to map the relationship between process parameters and and damping force the experiment was conducted on two wheeler front suspension. From the investigation It concludes that suspension velocity is most influencing parameter followed by damping hole and oil viscosity on damping force

Research paper thumbnail of Correlation between median nerve conduction studies and ultrasonography in cases of carpal tunnel syndrome

The Egyptian Journal of Neurology, Psychiatry and Neurosurgery, 2016

Background Nerve conduction studies (NCS) have long been the only objective measure used to confi... more Background Nerve conduction studies (NCS) have long been the only objective measure used to confirm the diagnosis of carpal tunnel syndrome (CTS), localize median nerve abnormalities, and exclude alternative diagnosis. Ultrasonography (US) can give information about the contents of carpal tunnel (CT) as well as aid in assessing the size of the median nerve (MN). Aim The aim of this study was to detect the relation between median NCS and cross-sectional area (CSA) of the MN measured using US in different grades of CTS. Patients and methods This study was a case–control, age-group matched, cross-sectional one. It included 60 wrists of 30 patients diagnosed with CTS and 60 wrists from 30 controls. Candidates were subjected to clinical assessment, median NCS, and measurement of CSA using US. Results There was a significant positive correlation between CSA of the MN at CT inlet and both motor and sensory responses latencies (r=0.638, P Conclusion US is highly correlated to NCS results in CTS. CSA of the MN at CT inlet measured using ultrasonography can be used as a screening tool for detection as well as discrimination of severe cases of CTS.