Dr. Karim H. Ali ِAbood (original) (raw)
Uploads
Papers by Dr. Karim H. Ali ِAbood
Modern Applied Science, 2011
A mathematical model of a railway carriage running on curved tracks is constructed by deriving th... more A mathematical model of a railway carriage running on curved tracks is constructed by deriving the equations of motion concerning the model in which single-point and two-point wheel-rail contact is considered. The presented railway carriage model comprises of front and rear simple conventional bogies with two leading and trailing wheelets attached to each bogie. The railway carriage is modeled by 31 degrees of freedom which govern vertical displacement, lateral displacement, roll angle and yaw angle dynamic response of wheelset whereas vertical displacement, lateral displacement, roll angle, pitch angle and yaw angle dynamic response of carbody and each of the two bogies. Linear stiffness and damping parameters of longitudinal, lateral and vertical primary and secondary suspensions are provided to the railway carriage model. Combination of linear Kalker's theory and nonlinear Heuristic model is adopted to calculate the creep forces in which introduced at wheel and rail contact patch area. Computer aided-simulation is constructed to solve the governing differential equations of the mathematical model using Runge-Kutta fourth order method. Principle of limit cycle and phase plane approach is applied to realize the stability and evaluate the concerning critical hunting velocity at which railway carriage starts to hunt. The numerical simulation model is used to study the influence of vertical secondary suspension spring stiffness on the ride passenger comfort of railway carbody running with speeds under and at critical hunting velocity. High magnitudes of vertical secondary spring stiffness suspension introduce undesirable roll and yaw dynamic response in which affect ride passenger comfort at critical hunting velocity. Low critical hunting velocity with railway carriage running on curved tracks can be represented.
As lithographic dimensions progress through sub-micron sizes, the effect of contamination becomes... more As lithographic dimensions progress through sub-micron sizes, the effect of contamination becomes more severe. The occurance of small particulates rises rapidly as their size decreases, not only because of the larger number of small airborne particulates but also because of the particulates from tools and semiconductor materials. Even with better clean rooms, this larger defect density can cause drastic yield reductions unless specific measures are taken to reduce its impact.
Investigation to improve hunting stability of railway carriage using semi-active longitudinal pri... more Investigation to improve hunting stability of railway carriage using semi-active longitudinal primary stiffness suspension
Mathematical Models and Methods in Applied Sciences, 2011
A mathematical model of a railway carriage running on curved tracks is constructed by deriving th... more A mathematical model of a railway carriage running on curved tracks is constructed by deriving the equations of motion concerning the model in which single-point and two-point wheel-rail contact is considered. The presented railway carriage model comprises of front and rear simple conventional bogies with two leading and trailing wheelets attached to each bogie. The railway carriage is modeled by 31 degrees of freedom which govern vertical displacement, lateral displacement, roll angle and yaw angle dynamic response of wheelset whereas vertical displacement, lateral displacement, roll angle, pitch angle and yaw angle dynamic response of carbody and each of the two bogies. Linear stiffness and damping parameters of longitudinal, lateral and vertical primary and secondary suspensions are provided to the railway carriage model. Combination of linear Kalker's theory and nonlinear Heuristic model is adopted to calculate the creep forces in which introduced at wheel and rail contact p...
Railway carriage model moving on tangent tracks is constructed by deriving the associated equatio... more Railway carriage model moving on tangent tracks is constructed by deriving the associated equations of motion where single-point and two-point wheel-rail contact is considered. The railway carriage is modeled by 31 degrees of freedom which govern vertical displacement, lateral displacement, roll angle and yaw angle of wheelset whereas vertical displacement, lateral displacement, roll angle, pitch angle and yaw angle of carbody and each of two bogies. Linear stiffness and damping parameters of primary and secondary suspensions are provided to the railway carriage model. Combination of linear Kalker's theory and nonlinear heuristic model is adopted to calculate the creep forces in which introduced at wheel and rail contact area. Computer aided-simulation is constructed to solve the governing differential equations of motion using Runge-Kutta fourth order method. Principles of limit cycle and phase plane approach is applied to study the stability and evaluate critical hunting veloc...
A mathematical model of a railway carriage moving on tangent tracks is constructed by deriving th... more A mathematical model of a railway carriage moving on tangent tracks is constructed by deriving the equations of motion concerning the model in which singlepoint and two-point wheel-rail contact is considered. The presented railway carriage model comprises of carbody and front and rear simple conventional bogie with two leading and trailing wheelets attached to each bogie. The railway carriage is modeled by 31 degrees of freedom which govern vertical displacement, lateral displacement, roll angle and yaw angle dynamic response of wheelset whereas vertical displacement, lateral displacement, roll angle, pitch angle and yaw angle dynamic response of carbody and each of the two bogies. Linear stiffness and damping parameters of longitudinal, lateral and vertical primary and secondary suspensions are provided to the railway carriage model. Combination of linear Kalker's theory and nonlinear Heuristic model is adopted to calculate the creep forces in which introduced at wheel and rail...
A mathematical model of railway carriage on tangent tracks with single-point and two-point wheel-... more A mathematical model of railway carriage on tangent tracks with single-point and two-point wheel-rail contact is considered. The railway carriage is modeled by 31 degrees of freedom which govern vertical, lateral, pitch, roll and yaw dynamic responses of wheelset, carbody and bogies. Linear stiffness and damping parameters of longitudinal, lateral and vertical primary and secondary suspensions are provided. Linear Kalker's and nonlinear Heuristic model is adopted to calculate the creep forces introduced at wheel-rail contact patch area. Computer aided-simulation is constructed to solve the differential equations of the mathematical model using Runge-Kutta fourth order method. Principle of limit cycle and phase plane approach is applied to evaluate the critical hunting velocity. The numerical simulation model used to study dynamic responses of carbody and bogies subjected to specific parameters of wheel conicity and primary suspension characteristics at critical hunting velocity....
Abstract A mathematical model of railway carriage on tangent tracks with single-point and two-poi... more Abstract A mathematical model of railway carriage on tangent tracks with single-point and two-point wheel-rail contact is considered. The railway carriage is modeled by 31 degrees of freedom which govern vertical, lateral, pitch, roll and yaw dynamic responses of wheelset, ...
Railway carriage model moving on tangent tracks is constructed by deriving the associated equatio... more Railway carriage model moving on tangent tracks is constructed by deriving the associated equations of motion where single-point and two-point wheel-rail contact is considered. The railway carriage is modeled by 31 degrees of freedom which govern vertical displacement, lateral displacement, roll angle and yaw angle of wheelset whereas vertical displacement, lateral displacement, roll angle, pitch angle and yaw angle of carbody and each of two bogies. Linear stiffness and damping parameters of primary and secondary suspensions are provided to the railway carriage model. Combination of linear Kalker's theory and nonlinear heuristic model is adopted to calculate the creep forces in which introduced at wheel and rail contact area. Computer aided-simulation is constructed to solve the governing differential equations of motion using Runge-Kutta fourth order method. Principles of limit cycle and phase plane approach is applied to study the stability and evaluate critical hunting velocity of the system. The numerical simulation model is used to represent dynamic responses of the components of railway carriage subjected to specific parameters of wheel conicity and suspension characteristics. Longitudinal primary stiffness suspension is controlled using semi-active suspension with lateral displacement indicator. The controlled semi-active longitudinal primary suspension is examined to increase the critical hunting velocity and improve hunting stability of railway carriage.
Modern Applied Science, 2011
A mathematical model of a railway carriage running on curved tracks is constructed by deriving th... more A mathematical model of a railway carriage running on curved tracks is constructed by deriving the equations of motion concerning the model in which single-point and two-point wheel-rail contact is considered. The presented railway carriage model comprises of front and rear simple conventional bogies with two leading and trailing wheelets attached to each bogie. The railway carriage is modeled by 31 degrees of freedom which govern vertical displacement, lateral displacement, roll angle and yaw angle dynamic response of wheelset whereas vertical displacement, lateral displacement, roll angle, pitch angle and yaw angle dynamic response of carbody and each of the two bogies. Linear stiffness and damping parameters of longitudinal, lateral and vertical primary and secondary suspensions are provided to the railway carriage model. Combination of linear Kalker's theory and nonlinear Heuristic model is adopted to calculate the creep forces in which introduced at wheel and rail contact patch area. Computer aided-simulation is constructed to solve the governing differential equations of the mathematical model using Runge-Kutta fourth order method. Principle of limit cycle and phase plane approach is applied to realize the stability and evaluate the concerning critical hunting velocity at which railway carriage starts to hunt. The numerical simulation model is used to study the influence of vertical secondary suspension spring stiffness on the ride passenger comfort of railway carbody running with speeds under and at critical hunting velocity. High magnitudes of vertical secondary spring stiffness suspension introduce undesirable roll and yaw dynamic response in which affect ride passenger comfort at critical hunting velocity. Low critical hunting velocity with railway carriage running on curved tracks can be represented.
As lithographic dimensions progress through sub-micron sizes, the effect of contamination becomes... more As lithographic dimensions progress through sub-micron sizes, the effect of contamination becomes more severe. The occurance of small particulates rises rapidly as their size decreases, not only because of the larger number of small airborne particulates but also because of the particulates from tools and semiconductor materials. Even with better clean rooms, this larger defect density can cause drastic yield reductions unless specific measures are taken to reduce its impact.
Investigation to improve hunting stability of railway carriage using semi-active longitudinal pri... more Investigation to improve hunting stability of railway carriage using semi-active longitudinal primary stiffness suspension
Mathematical Models and Methods in Applied Sciences, 2011
A mathematical model of a railway carriage running on curved tracks is constructed by deriving th... more A mathematical model of a railway carriage running on curved tracks is constructed by deriving the equations of motion concerning the model in which single-point and two-point wheel-rail contact is considered. The presented railway carriage model comprises of front and rear simple conventional bogies with two leading and trailing wheelets attached to each bogie. The railway carriage is modeled by 31 degrees of freedom which govern vertical displacement, lateral displacement, roll angle and yaw angle dynamic response of wheelset whereas vertical displacement, lateral displacement, roll angle, pitch angle and yaw angle dynamic response of carbody and each of the two bogies. Linear stiffness and damping parameters of longitudinal, lateral and vertical primary and secondary suspensions are provided to the railway carriage model. Combination of linear Kalker's theory and nonlinear Heuristic model is adopted to calculate the creep forces in which introduced at wheel and rail contact p...
Railway carriage model moving on tangent tracks is constructed by deriving the associated equatio... more Railway carriage model moving on tangent tracks is constructed by deriving the associated equations of motion where single-point and two-point wheel-rail contact is considered. The railway carriage is modeled by 31 degrees of freedom which govern vertical displacement, lateral displacement, roll angle and yaw angle of wheelset whereas vertical displacement, lateral displacement, roll angle, pitch angle and yaw angle of carbody and each of two bogies. Linear stiffness and damping parameters of primary and secondary suspensions are provided to the railway carriage model. Combination of linear Kalker's theory and nonlinear heuristic model is adopted to calculate the creep forces in which introduced at wheel and rail contact area. Computer aided-simulation is constructed to solve the governing differential equations of motion using Runge-Kutta fourth order method. Principles of limit cycle and phase plane approach is applied to study the stability and evaluate critical hunting veloc...
A mathematical model of a railway carriage moving on tangent tracks is constructed by deriving th... more A mathematical model of a railway carriage moving on tangent tracks is constructed by deriving the equations of motion concerning the model in which singlepoint and two-point wheel-rail contact is considered. The presented railway carriage model comprises of carbody and front and rear simple conventional bogie with two leading and trailing wheelets attached to each bogie. The railway carriage is modeled by 31 degrees of freedom which govern vertical displacement, lateral displacement, roll angle and yaw angle dynamic response of wheelset whereas vertical displacement, lateral displacement, roll angle, pitch angle and yaw angle dynamic response of carbody and each of the two bogies. Linear stiffness and damping parameters of longitudinal, lateral and vertical primary and secondary suspensions are provided to the railway carriage model. Combination of linear Kalker's theory and nonlinear Heuristic model is adopted to calculate the creep forces in which introduced at wheel and rail...
A mathematical model of railway carriage on tangent tracks with single-point and two-point wheel-... more A mathematical model of railway carriage on tangent tracks with single-point and two-point wheel-rail contact is considered. The railway carriage is modeled by 31 degrees of freedom which govern vertical, lateral, pitch, roll and yaw dynamic responses of wheelset, carbody and bogies. Linear stiffness and damping parameters of longitudinal, lateral and vertical primary and secondary suspensions are provided. Linear Kalker's and nonlinear Heuristic model is adopted to calculate the creep forces introduced at wheel-rail contact patch area. Computer aided-simulation is constructed to solve the differential equations of the mathematical model using Runge-Kutta fourth order method. Principle of limit cycle and phase plane approach is applied to evaluate the critical hunting velocity. The numerical simulation model used to study dynamic responses of carbody and bogies subjected to specific parameters of wheel conicity and primary suspension characteristics at critical hunting velocity....
Abstract A mathematical model of railway carriage on tangent tracks with single-point and two-poi... more Abstract A mathematical model of railway carriage on tangent tracks with single-point and two-point wheel-rail contact is considered. The railway carriage is modeled by 31 degrees of freedom which govern vertical, lateral, pitch, roll and yaw dynamic responses of wheelset, ...
Railway carriage model moving on tangent tracks is constructed by deriving the associated equatio... more Railway carriage model moving on tangent tracks is constructed by deriving the associated equations of motion where single-point and two-point wheel-rail contact is considered. The railway carriage is modeled by 31 degrees of freedom which govern vertical displacement, lateral displacement, roll angle and yaw angle of wheelset whereas vertical displacement, lateral displacement, roll angle, pitch angle and yaw angle of carbody and each of two bogies. Linear stiffness and damping parameters of primary and secondary suspensions are provided to the railway carriage model. Combination of linear Kalker's theory and nonlinear heuristic model is adopted to calculate the creep forces in which introduced at wheel and rail contact area. Computer aided-simulation is constructed to solve the governing differential equations of motion using Runge-Kutta fourth order method. Principles of limit cycle and phase plane approach is applied to study the stability and evaluate critical hunting velocity of the system. The numerical simulation model is used to represent dynamic responses of the components of railway carriage subjected to specific parameters of wheel conicity and suspension characteristics. Longitudinal primary stiffness suspension is controlled using semi-active suspension with lateral displacement indicator. The controlled semi-active longitudinal primary suspension is examined to increase the critical hunting velocity and improve hunting stability of railway carriage.