Motion stability of a spacecraft is discussed.A canonical Hamiltonian model for liquid sloshing is presented for a moving rigid body.An equivalent mechanical pendulum model is used to represent the fuel slosh inside t...Motion stability of a spacecraft is discussed.A canonical Hamiltonian model for liquid sloshing is presented for a moving rigid body.An equivalent mechanical pendulum model is used to represent the fuel slosh inside the container.In this model sloshing is represented by the moving mass,the rest of the mass of the spacecraft is assumed to be stationary.The spacecraft structure is considered to be an elliptical rigid shape and the steady rotation along the x-axis is taken as the major-axis rotation.Motion stability for the present model is analyzed using the Lyapunov theory with Casimir energy functions.Conditions for stability and instability are derived for a steady principal axis rotation of the rigid body.Simulation results are presented to distribute the region into stable and unstable regions.Besides this,the nonlinear behavior of the system is analyzed under the influence of an external force acting periodically.Chaos is observed through a bifurcation diagram.The time history map and phase portrait are also presented to analyze the nonlinear behavior of the system.展开更多
Water is the main factor for the healthy life of plant.One of the main negative effects of climate change is the increasing scarcity of water that is lethal for plant.Globally,for water deficit regions(arid and semi-a...Water is the main factor for the healthy life of plant.One of the main negative effects of climate change is the increasing scarcity of water that is lethal for plant.Globally,for water deficit regions(arid and semi-arid),drought is the main factor responsible for low production of agriculture,especially for cotton.Great efforts have been and are being made to find alternatives to water saving practices.This study aimed to examine the effects of partial rhizosphere drying(PRD,half of the root system irrigated at one event,and the other half irrigated in the next event,and so on)with and/or without various mulching treatments on physiological and biochemical traits of cotton.To explore this objective,we laid out experiments in completely randomized design with factorial arrangement in the Islamia University of Bahawalpur,Pakistan in 2016.Two factors included were four mulching treatments(M0,no mulching;M1,black plastic mulching;M2,wheat straw mulching;and M3,cotton sticks mulching)and two irrigation levels(I0,control(full irrigation);and I1,PRD).Fisher's analysis of variance among means of treatments was compared using least significant difference test at 5% probability level.Results revealed that the maximum plant height,leaf area,leaf gas exchange(photosynthetic rate and stomata conductance),chlorophyll,proline and total sugar contents,and enzyme activities were higher under M2 than under other three mulching treatments.As for irrigation levels,higher values of plant height,photosynthesis and water related parameters(leaf water potential,leaf osmotic potential,leaf turgor potential,etc.)were recorded.Contents of total sugar and proline and activities of antioxidant enzymes were significantly higher in PRD-treated plants than in control plants.It was concluded that combined application of PRD and mulching was more effective than the rest of the treatments used in the experiment.Similar study can be conducted in the field by applying irrigation water in alternate rows in semi-arid regions.展开更多
This article computes effect of uniform magnetic field on nanofluid flow filling porous medium inside parallel sheets. Darcy's law is used to characterize porous medium. Flow is caused by stretching of the lower s...This article computes effect of uniform magnetic field on nanofluid flow filling porous medium inside parallel sheets. Darcy's law is used to characterize porous medium. Flow is caused by stretching of the lower sheet. The governing systems are computed using Finite difference technique. This scheme is used due to its more general and powerful nature to solve nonlinear problems. Results are obtained and discussed graphically. Nusselt number, skin friction, streamlines,velocity and temperature are emphasized.展开更多
In this article we investigate the flow of Sutterby liquid due to rotating stretchable disk. Mass and heat transport are analyzed through Brownian diffusion and thermophoresis. Further the effects of magnetic field, c...In this article we investigate the flow of Sutterby liquid due to rotating stretchable disk. Mass and heat transport are analyzed through Brownian diffusion and thermophoresis. Further the effects of magnetic field, chemical reaction and heat source are also accounted. We employ transformation procedure to obtain a system of nonlinear ODE's. This system is numerically solved by Built-in-Shooting method. Impacts of different involved parameter on velocity, temperature and concentration are described. Velocity, concentration and temperature gradients are numerically computed. Obtained results show that velocity is reduced through material parameter. Temperature and concentration are enhanced with thermophoresis parameter.展开更多
This paper presents a canonical Hamiltonian model of liquid sloshing for the container coupled with spacecraft. Elliptical shape of rigid body is considered as spacecraft structure. Hamiltonian system is an important ...This paper presents a canonical Hamiltonian model of liquid sloshing for the container coupled with spacecraft. Elliptical shape of rigid body is considered as spacecraft structure. Hamiltonian system is an important form of mechanical system. It mostly used to stabilize the potential shaping of dynamical system. Free surface movement of liquid inside the container is called sloshing. If there is uncontrolled resonance between the motion of tank and liquid-frequency inside the tank then such sloshing can be a reason of attitude disturbance or structural damage of spacecraft. Equivalent mechanical model of simple pendulum or mass attached with spring for sloshing is used by many researchers. Mass attached with spring is used as an equivalent model of sloshing to derive the mathematical equations in terms of Hamiltonian model. Analytical method of Lyapunov function with Casimir energy function is used to find the stability for spacecraft dynamics. Vertical axial rotation is taken as the major axial steady rotation for the moving rigid body.展开更多
Time-dependent viscous fluid flow due to a stretchable rotating disk is investigated.Magnetic field is applied in vertical direction to the disk.Temperature equation is assisted with Joule heating effect.Governing sys...Time-dependent viscous fluid flow due to a stretchable rotating disk is investigated.Magnetic field is applied in vertical direction to the disk.Temperature equation is assisted with Joule heating effect.Governing system of PDE's is transformed to dimensionless form by suitable variables.One of the numerical techniques known as finite difference scheme is adopted to tackle the given dimensionless partial differential system.This method results in a system of simple algebraic equations.The unknown function is analyzed inside domain of interest.In this technique of solution,a system is subdivided into many smaller parts called finite elements.The obtained simpler algebraic equations are then assembled to form a system of equations which governs the original problem.Variational method is used to get approximate solution by reducing the error function.Behaviors of pertinent variables on surface drag force,temperature,velocity and heat transfer rate are shown graphically.The obtained outcomes guarantee that velocity decreases for Hartmann number while it enhances with Reynolds number.Temperature increases for higher Prandtl,Eckert and Hartmann numbers.Skin friction boosts for larger values of Hartmann number.Nusselt number enhances with Hartmann number.展开更多
基金Supported by Higher Education Commission of Pakistan,the National Natural Science Foundation of China(11072030)Ph.D.Programs Foundation of Ministry of Education of China(20080070011)+1 种基金Scientific Research Foundation of Ministry of Education of China for Returned Scholars(20080732040)the Program of Beijing Municipal Key Discipline Construction.
文摘Motion stability of a spacecraft is discussed.A canonical Hamiltonian model for liquid sloshing is presented for a moving rigid body.An equivalent mechanical pendulum model is used to represent the fuel slosh inside the container.In this model sloshing is represented by the moving mass,the rest of the mass of the spacecraft is assumed to be stationary.The spacecraft structure is considered to be an elliptical rigid shape and the steady rotation along the x-axis is taken as the major-axis rotation.Motion stability for the present model is analyzed using the Lyapunov theory with Casimir energy functions.Conditions for stability and instability are derived for a steady principal axis rotation of the rigid body.Simulation results are presented to distribute the region into stable and unstable regions.Besides this,the nonlinear behavior of the system is analyzed under the influence of an external force acting periodically.Chaos is observed through a bifurcation diagram.The time history map and phase portrait are also presented to analyze the nonlinear behavior of the system.
基金funded by the Higher Education Commission of Pakistan(#20-4968/NRPU/R&D/HEC)
文摘Water is the main factor for the healthy life of plant.One of the main negative effects of climate change is the increasing scarcity of water that is lethal for plant.Globally,for water deficit regions(arid and semi-arid),drought is the main factor responsible for low production of agriculture,especially for cotton.Great efforts have been and are being made to find alternatives to water saving practices.This study aimed to examine the effects of partial rhizosphere drying(PRD,half of the root system irrigated at one event,and the other half irrigated in the next event,and so on)with and/or without various mulching treatments on physiological and biochemical traits of cotton.To explore this objective,we laid out experiments in completely randomized design with factorial arrangement in the Islamia University of Bahawalpur,Pakistan in 2016.Two factors included were four mulching treatments(M0,no mulching;M1,black plastic mulching;M2,wheat straw mulching;and M3,cotton sticks mulching)and two irrigation levels(I0,control(full irrigation);and I1,PRD).Fisher's analysis of variance among means of treatments was compared using least significant difference test at 5% probability level.Results revealed that the maximum plant height,leaf area,leaf gas exchange(photosynthetic rate and stomata conductance),chlorophyll,proline and total sugar contents,and enzyme activities were higher under M2 than under other three mulching treatments.As for irrigation levels,higher values of plant height,photosynthesis and water related parameters(leaf water potential,leaf osmotic potential,leaf turgor potential,etc.)were recorded.Contents of total sugar and proline and activities of antioxidant enzymes were significantly higher in PRD-treated plants than in control plants.It was concluded that combined application of PRD and mulching was more effective than the rest of the treatments used in the experiment.Similar study can be conducted in the field by applying irrigation water in alternate rows in semi-arid regions.
文摘This article computes effect of uniform magnetic field on nanofluid flow filling porous medium inside parallel sheets. Darcy's law is used to characterize porous medium. Flow is caused by stretching of the lower sheet. The governing systems are computed using Finite difference technique. This scheme is used due to its more general and powerful nature to solve nonlinear problems. Results are obtained and discussed graphically. Nusselt number, skin friction, streamlines,velocity and temperature are emphasized.
文摘In this article we investigate the flow of Sutterby liquid due to rotating stretchable disk. Mass and heat transport are analyzed through Brownian diffusion and thermophoresis. Further the effects of magnetic field, chemical reaction and heat source are also accounted. We employ transformation procedure to obtain a system of nonlinear ODE's. This system is numerically solved by Built-in-Shooting method. Impacts of different involved parameter on velocity, temperature and concentration are described. Velocity, concentration and temperature gradients are numerically computed. Obtained results show that velocity is reduced through material parameter. Temperature and concentration are enhanced with thermophoresis parameter.
基金supported by Higher Education Commis- sion of Pakistan,National Natural Science Foundation of China(11072030)Ph.D.Programs Foundation of Ministry of Education of China(20080070011)+1 种基金Scientific Research Foundation of Ministry of Education of China for Returned Scholars(20080732040)Program of Beijing Municipal Key Discipline Construction
文摘This paper presents a canonical Hamiltonian model of liquid sloshing for the container coupled with spacecraft. Elliptical shape of rigid body is considered as spacecraft structure. Hamiltonian system is an important form of mechanical system. It mostly used to stabilize the potential shaping of dynamical system. Free surface movement of liquid inside the container is called sloshing. If there is uncontrolled resonance between the motion of tank and liquid-frequency inside the tank then such sloshing can be a reason of attitude disturbance or structural damage of spacecraft. Equivalent mechanical model of simple pendulum or mass attached with spring for sloshing is used by many researchers. Mass attached with spring is used as an equivalent model of sloshing to derive the mathematical equations in terms of Hamiltonian model. Analytical method of Lyapunov function with Casimir energy function is used to find the stability for spacecraft dynamics. Vertical axial rotation is taken as the major axial steady rotation for the moving rigid body.
文摘Time-dependent viscous fluid flow due to a stretchable rotating disk is investigated.Magnetic field is applied in vertical direction to the disk.Temperature equation is assisted with Joule heating effect.Governing system of PDE's is transformed to dimensionless form by suitable variables.One of the numerical techniques known as finite difference scheme is adopted to tackle the given dimensionless partial differential system.This method results in a system of simple algebraic equations.The unknown function is analyzed inside domain of interest.In this technique of solution,a system is subdivided into many smaller parts called finite elements.The obtained simpler algebraic equations are then assembled to form a system of equations which governs the original problem.Variational method is used to get approximate solution by reducing the error function.Behaviors of pertinent variables on surface drag force,temperature,velocity and heat transfer rate are shown graphically.The obtained outcomes guarantee that velocity decreases for Hartmann number while it enhances with Reynolds number.Temperature increases for higher Prandtl,Eckert and Hartmann numbers.Skin friction boosts for larger values of Hartmann number.Nusselt number enhances with Hartmann number.
