steven barry - Academia.edu (original) (raw)
Papers by steven barry
Australian & New Zealand industrial and applied mathematics journal, Jun 22, 2006
International Journal of Non-Linear Mechanics, 1991
ABSTRACT
Mathematical and Computer Modelling, 2011
Although numerical methods have been developed for diffusion through single layer materials, few ... more Although numerical methods have been developed for diffusion through single layer materials, few have been developed for multiple layers. Diffusion processes through a multilayered material are of interest for a wide range of applications, including industrial, biological, electrical, and environmental areas. We present finite difference schemes for multilayered materials with a range of matching conditions between the layers, in particular for a jump matching condition. We show the finite difference methods are flexible, simple to implement, and help illustrate interesting behaviour in multilayered diffusion.
ZAMP Zeitschrift f�r angewandte Mathematik und Physik, 1991
The flow of a viscous fluid over a thin, deformable porous layer fixed to the solid wall of a cha... more The flow of a viscous fluid over a thin, deformable porous layer fixed to the solid wall of a channel is considered. The coupled equations for the fluid velocity and the infinitesimal deformation of the solid matrix within the porous layer are developed using binary mixture theory, Darcy's law and the assumption of linear elasticity. The case of pure shear is solved analytically for the displacement of the solid matrix, the fluid velocity both in the porous medium and the fluid above it. For a thin porous layer the boundary condition for the fluid velocity at the fluid-matrix interface is derived. This condition replaces the usual no slip condition and can be applied without solving for the flow in the porous layer.
Bulletin of Mathematical Biology, 1997
We describe a mathematical model of the flow and deformation in a human teat. Our aim is to compa... more We describe a mathematical model of the flow and deformation in a human teat. Our aim is to compare the theoretical milk yield during infant breast feeding with that obtained through the use of a breast pump. Infants use a peristaltic motion of the tongue, along with some suction, to extract milk, whereas breast pumps use a cyclic pattern of suction only. Our model is based on quasi-linear poroelasticity whereby the teat is modelled as a cylindrical porous elastic material saturated with fluid. We impose a cyclic axial suction pressure difference across the teat and impose a radial compressive force moving along the teat which mimics infant suckling. This is compared to the case of cyclic and steady pumping only which models the action of breast pumps. The results illustrate that there is an optimal time to apply the compressive force during the suction cycle that will increase the flow rate in our theoretical teat. The model and results may be of use in the future design of effective breast pumps.
Applied Mathematical Modelling, 1997
The flow of fluid from a point source or sink at some arbitrary height in a layer of deformable p... more The flow of fluid from a point source or sink at some arbitrary height in a layer of deformable porous material is considered. This problem is applicable to filtration through beds of sand and flow in soils. The porous material is assumed to be an isotropic, homogeneous, linear elastic solid. The equations governing the behaclior of the medium and jluid are derived for an axisymmetric geometry using linear poro-elasticity theory and are sok>ed using the Hankef transform with the Hankel inversion integral eualuated numerically. The upper surface is stress free and permeable, with the lower surface impermeable to fluid jlow. Two different boundary conditions are applied to the lower surface; stress free and tethered. Results are given for the pressure contours, sut$ace fluid velocity, and the displacement of the solid matrix for a variety of source heights and boundary conditions. These results provide an indication of the amount of swelling of the medium and subsequent deformation of the free sugace as a function of the location of the point source and boundary conditions.
ANZIAM Journal, 2006
Teaching Numerical Methods to first year engineering students is improved by a collaboration betw... more Teaching Numerical Methods to first year engineering students is improved by a collaboration between engineers, computer scientists and mathematicians. Our approach has been to teach a problem based course with six, fortnightly assignments, each revolving around an engineering problem solved by a specific numerical method. The collaborative delivery, engineering problem focus, and intensive tutorials all contribute to make this a very successful course that gives the students a sound foundation to take into later years and hopefully their careers.
ANZIAM Journal, 1998
The deformation of a poro-elastic cylinder due to radial fluid flow is considered. This has appli... more The deformation of a poro-elastic cylinder due to radial fluid flow is considered. This has application to modelling arterial flow and certain filtration processes. A diffusion equation for the dilatation with unusual integral boundary conditions is derived for two typical boundary conditions. Asymptotic solutions, to the linearised equations for small times, are found using
ANZIAM Journal, 2009
During annealing, heat transfer within steel coils is complicated by the different conductivity i... more During annealing, heat transfer within steel coils is complicated by the different conductivity in radial and axial directions due to small air gaps between the steel layers in the radial direction. Here an analytic solution augmented with numerical calculations illustrates some of the fundamental behaviour of the system, including calculations of the time lag. The beneficial effects of additional heating on the curved surfaces are shown. C669 3 Linear solution C672 4 Results C675 5 Conclusion C678 References C680
ANZIAM Journal, 2008
Airborne maritime surveillance operations are part of Australia's national security. The determin... more Airborne maritime surveillance operations are part of Australia's national security. The determination of an efficient route to approach each ship detected to within the classification range is a difficult variation on the classical Travelling Salesman Problem because, for example, the ships are moving. In this article, variations in the detection and classification ranges are investigated, with greater classification ranges resulting in route length reductions of up to 20%. Including a finite turning circle radius for an aircraft can cause in increase in route length of up to 20% for a turning circle radius of 10 nautical miles.
The key steps to our research endeavours are the analysis of real world problems; the formulation... more The key steps to our research endeavours are the analysis of real world problems; the formulation of the problem in mathematical terms; the use of that formulation to provide an understanding of the nature of the problems and how they may be solved; and the communication of the outcomes to both the originators of the problems and the wider applied mathematics research community. Group members call on the vast range of mathematical and statistical techniques supplemented with the application of extensive modern computing methods. The range of techniques and the mathematical thinking skills that experience develops results in an extraordinarily flexible and powerful approach that can be adapted to a huge set of different practical problems as illustrated by the list of projects. The interdisciplinary nature of the work and the constraints imposed by dealing with genuine practical problems make this a challenging and rewarding area for research. The importance and value of the work is ...
ANZIAM Journal, 2006
Wool scouring is the process of washing dirty wool after shearing. Our model simulates, using the... more Wool scouring is the process of washing dirty wool after shearing. Our model simulates, using the advection-diffusion equation, the movement of contaminants within a scour bowl. The effects of varying the important parameters are investigated. Interesting, but simple, relationships are found which give insight into the dynamics of a scour bowl.
Journal of Human Lactation, 1997
There is a role for computer models in increasing the understanding of milk extraction from the h... more There is a role for computer models in increasing the understanding of milk extraction from the human teat. A computer model can be used to investigate aspects of extracting milk from the human teat which are not feasible using clinical experiments. In this paper, the behavior of the human teat during an infant suckling and with the use of a breast pump is modeled. The model is used to (1) identify the role of suction and the peristaltic motion of the tongue during suckling and (2) compare the volume of milk extracted by an infant breastfeeding with that obtained using a breast pump. Infants use a peristaltic motion of the tongue, along with some suction, to extract milk. Breast pumps use a cyclic pattern of suction only. In the model, the human teat is represented as a cylindrical porous elastic material saturated with fluid. We mimic an infant suckling by imposing both suction and a peristaltic force in the computer model of the human teat. This is compared to the effect of suctio...
Journal of Applied Mechanics, 1997
The deformation, using linear poroelasticity, of a two-dimensional box of porous material due to ... more The deformation, using linear poroelasticity, of a two-dimensional box of porous material due to fluid flow from a line source is considered as a model of certain filtration processes. Analytical solutions for the steady-state displacement, pressure, and fluid velocity are derived when the side walls of the filter have zero solid stress. A numerical solution for the case where the porous material adheres to the side walls is also found. It will be shown, however, that simpler approximate solutions can be derived which predict the majority of the deformation behavior of the filter.
International Journal of Heat and Mass Transfer, 2011
Reaction diffusion has applications to a wide range of areas, including industrial, geological, a... more Reaction diffusion has applications to a wide range of areas, including industrial, geological, and medical problems. An important aspect is the phenomenon of 'critical time', which is a measure of how long the reaction and diffusion processes take. In this work, an exact solution using a linear reaction function is used to explore three critical time definitions. The outcome of the analysis is a simple, novel relationship between the reaction and diffusion time scales.
Page 1. The m aritim e surveillance problem Philip Kilby NICTA and Australian National University... more Page 1. The m aritim e surveillance problem Philip Kilby NICTA and Australian National University Patrick Tobin Swinburne University of Technology Ruth Luscombe University of Melbourne Steven I. Barry and Roslyn Hickson University of New South Wales @ ADFA ...
Air Traffic Control Quarterly, 2015
This paper presents a framework for the assessment of Air Traffic Management (ATM) performance in... more This paper presents a framework for the assessment of Air Traffic Management (ATM) performance in relation to flight efficiency. The main philosophy behind the approach presented in this paper is to quantify the quality of the service delivered by an Air Navigation Service Provider (ANSP) to an airline in terms of meeting commonly agreed objectives. The definition is therefore aligned with the future paradigm of Trajectory Based Operations, where achieving the trajectory agreed between the ANSP and the airspace user becomes the focus. A staged approach to flight efficiency assessment is proposed to quantify the quality of the ANSP's service in terms of both "facilitating what has been agreed" and "improving what can be agreed". The framework promotes the development of more consistent efficiency performance metrics between ANSPs, as clear definitions exist for assessment references. Application of the framework was illustrated with several examples using the Airservices Dalí trajectory modeller.
International Journal of Heat and Mass Transfer, 2009
Traditional averaging methods for multilayer diffusion give inaccurate approximations of critical... more Traditional averaging methods for multilayer diffusion give inaccurate approximations of critical time behaviour, such as the heating time of a material. In particular, they fail to capture the importance of layer order. We use a perturbation expansion of an exact solution to find a simple approximate solution which accurately describes the critical time for transport across multiple layers. This approximate solution is then used to find a correction for the averaging method which captures the key critical time behaviour.
Proceedings
Go-arounds (GAs) are standard air traffic control procedures during which aircraft approach a run... more Go-arounds (GAs) are standard air traffic control procedures during which aircraft approach a runway but do not land. The incidence of a GA can subsequently affect the workload of flight crews and air traffic controllers, and might impact an airport runway’s throughput capacity. In this study, two different modeling methods for predicting the occurrence of GAs based on open-source Automatic Dependent Surveillance–Broadcast (ADS-B) and meteorological data are presented. A macroscopic model quantifies the probability of a GA within the next hour for an airport by applying a generalized additive model. A microscopic model employs a number of machine learning classifiers on trajectories of aircraft on approach in order to predict if a GA will be performed. Even though the results of the macroscopic model are promising, the information currently available to predict the probability of a GA is not detailed enough to achieve satisfactory predictions. Similarly, the microscopic model is cap...
Australian & New Zealand industrial and applied mathematics journal, Jun 22, 2006
International Journal of Non-Linear Mechanics, 1991
ABSTRACT
Mathematical and Computer Modelling, 2011
Although numerical methods have been developed for diffusion through single layer materials, few ... more Although numerical methods have been developed for diffusion through single layer materials, few have been developed for multiple layers. Diffusion processes through a multilayered material are of interest for a wide range of applications, including industrial, biological, electrical, and environmental areas. We present finite difference schemes for multilayered materials with a range of matching conditions between the layers, in particular for a jump matching condition. We show the finite difference methods are flexible, simple to implement, and help illustrate interesting behaviour in multilayered diffusion.
ZAMP Zeitschrift f�r angewandte Mathematik und Physik, 1991
The flow of a viscous fluid over a thin, deformable porous layer fixed to the solid wall of a cha... more The flow of a viscous fluid over a thin, deformable porous layer fixed to the solid wall of a channel is considered. The coupled equations for the fluid velocity and the infinitesimal deformation of the solid matrix within the porous layer are developed using binary mixture theory, Darcy's law and the assumption of linear elasticity. The case of pure shear is solved analytically for the displacement of the solid matrix, the fluid velocity both in the porous medium and the fluid above it. For a thin porous layer the boundary condition for the fluid velocity at the fluid-matrix interface is derived. This condition replaces the usual no slip condition and can be applied without solving for the flow in the porous layer.
Bulletin of Mathematical Biology, 1997
We describe a mathematical model of the flow and deformation in a human teat. Our aim is to compa... more We describe a mathematical model of the flow and deformation in a human teat. Our aim is to compare the theoretical milk yield during infant breast feeding with that obtained through the use of a breast pump. Infants use a peristaltic motion of the tongue, along with some suction, to extract milk, whereas breast pumps use a cyclic pattern of suction only. Our model is based on quasi-linear poroelasticity whereby the teat is modelled as a cylindrical porous elastic material saturated with fluid. We impose a cyclic axial suction pressure difference across the teat and impose a radial compressive force moving along the teat which mimics infant suckling. This is compared to the case of cyclic and steady pumping only which models the action of breast pumps. The results illustrate that there is an optimal time to apply the compressive force during the suction cycle that will increase the flow rate in our theoretical teat. The model and results may be of use in the future design of effective breast pumps.
Applied Mathematical Modelling, 1997
The flow of fluid from a point source or sink at some arbitrary height in a layer of deformable p... more The flow of fluid from a point source or sink at some arbitrary height in a layer of deformable porous material is considered. This problem is applicable to filtration through beds of sand and flow in soils. The porous material is assumed to be an isotropic, homogeneous, linear elastic solid. The equations governing the behaclior of the medium and jluid are derived for an axisymmetric geometry using linear poro-elasticity theory and are sok>ed using the Hankef transform with the Hankel inversion integral eualuated numerically. The upper surface is stress free and permeable, with the lower surface impermeable to fluid jlow. Two different boundary conditions are applied to the lower surface; stress free and tethered. Results are given for the pressure contours, sut$ace fluid velocity, and the displacement of the solid matrix for a variety of source heights and boundary conditions. These results provide an indication of the amount of swelling of the medium and subsequent deformation of the free sugace as a function of the location of the point source and boundary conditions.
ANZIAM Journal, 2006
Teaching Numerical Methods to first year engineering students is improved by a collaboration betw... more Teaching Numerical Methods to first year engineering students is improved by a collaboration between engineers, computer scientists and mathematicians. Our approach has been to teach a problem based course with six, fortnightly assignments, each revolving around an engineering problem solved by a specific numerical method. The collaborative delivery, engineering problem focus, and intensive tutorials all contribute to make this a very successful course that gives the students a sound foundation to take into later years and hopefully their careers.
ANZIAM Journal, 1998
The deformation of a poro-elastic cylinder due to radial fluid flow is considered. This has appli... more The deformation of a poro-elastic cylinder due to radial fluid flow is considered. This has application to modelling arterial flow and certain filtration processes. A diffusion equation for the dilatation with unusual integral boundary conditions is derived for two typical boundary conditions. Asymptotic solutions, to the linearised equations for small times, are found using
ANZIAM Journal, 2009
During annealing, heat transfer within steel coils is complicated by the different conductivity i... more During annealing, heat transfer within steel coils is complicated by the different conductivity in radial and axial directions due to small air gaps between the steel layers in the radial direction. Here an analytic solution augmented with numerical calculations illustrates some of the fundamental behaviour of the system, including calculations of the time lag. The beneficial effects of additional heating on the curved surfaces are shown. C669 3 Linear solution C672 4 Results C675 5 Conclusion C678 References C680
ANZIAM Journal, 2008
Airborne maritime surveillance operations are part of Australia's national security. The determin... more Airborne maritime surveillance operations are part of Australia's national security. The determination of an efficient route to approach each ship detected to within the classification range is a difficult variation on the classical Travelling Salesman Problem because, for example, the ships are moving. In this article, variations in the detection and classification ranges are investigated, with greater classification ranges resulting in route length reductions of up to 20%. Including a finite turning circle radius for an aircraft can cause in increase in route length of up to 20% for a turning circle radius of 10 nautical miles.
The key steps to our research endeavours are the analysis of real world problems; the formulation... more The key steps to our research endeavours are the analysis of real world problems; the formulation of the problem in mathematical terms; the use of that formulation to provide an understanding of the nature of the problems and how they may be solved; and the communication of the outcomes to both the originators of the problems and the wider applied mathematics research community. Group members call on the vast range of mathematical and statistical techniques supplemented with the application of extensive modern computing methods. The range of techniques and the mathematical thinking skills that experience develops results in an extraordinarily flexible and powerful approach that can be adapted to a huge set of different practical problems as illustrated by the list of projects. The interdisciplinary nature of the work and the constraints imposed by dealing with genuine practical problems make this a challenging and rewarding area for research. The importance and value of the work is ...
ANZIAM Journal, 2006
Wool scouring is the process of washing dirty wool after shearing. Our model simulates, using the... more Wool scouring is the process of washing dirty wool after shearing. Our model simulates, using the advection-diffusion equation, the movement of contaminants within a scour bowl. The effects of varying the important parameters are investigated. Interesting, but simple, relationships are found which give insight into the dynamics of a scour bowl.
Journal of Human Lactation, 1997
There is a role for computer models in increasing the understanding of milk extraction from the h... more There is a role for computer models in increasing the understanding of milk extraction from the human teat. A computer model can be used to investigate aspects of extracting milk from the human teat which are not feasible using clinical experiments. In this paper, the behavior of the human teat during an infant suckling and with the use of a breast pump is modeled. The model is used to (1) identify the role of suction and the peristaltic motion of the tongue during suckling and (2) compare the volume of milk extracted by an infant breastfeeding with that obtained using a breast pump. Infants use a peristaltic motion of the tongue, along with some suction, to extract milk. Breast pumps use a cyclic pattern of suction only. In the model, the human teat is represented as a cylindrical porous elastic material saturated with fluid. We mimic an infant suckling by imposing both suction and a peristaltic force in the computer model of the human teat. This is compared to the effect of suctio...
Journal of Applied Mechanics, 1997
The deformation, using linear poroelasticity, of a two-dimensional box of porous material due to ... more The deformation, using linear poroelasticity, of a two-dimensional box of porous material due to fluid flow from a line source is considered as a model of certain filtration processes. Analytical solutions for the steady-state displacement, pressure, and fluid velocity are derived when the side walls of the filter have zero solid stress. A numerical solution for the case where the porous material adheres to the side walls is also found. It will be shown, however, that simpler approximate solutions can be derived which predict the majority of the deformation behavior of the filter.
International Journal of Heat and Mass Transfer, 2011
Reaction diffusion has applications to a wide range of areas, including industrial, geological, a... more Reaction diffusion has applications to a wide range of areas, including industrial, geological, and medical problems. An important aspect is the phenomenon of 'critical time', which is a measure of how long the reaction and diffusion processes take. In this work, an exact solution using a linear reaction function is used to explore three critical time definitions. The outcome of the analysis is a simple, novel relationship between the reaction and diffusion time scales.
Page 1. The m aritim e surveillance problem Philip Kilby NICTA and Australian National University... more Page 1. The m aritim e surveillance problem Philip Kilby NICTA and Australian National University Patrick Tobin Swinburne University of Technology Ruth Luscombe University of Melbourne Steven I. Barry and Roslyn Hickson University of New South Wales @ ADFA ...
Air Traffic Control Quarterly, 2015
This paper presents a framework for the assessment of Air Traffic Management (ATM) performance in... more This paper presents a framework for the assessment of Air Traffic Management (ATM) performance in relation to flight efficiency. The main philosophy behind the approach presented in this paper is to quantify the quality of the service delivered by an Air Navigation Service Provider (ANSP) to an airline in terms of meeting commonly agreed objectives. The definition is therefore aligned with the future paradigm of Trajectory Based Operations, where achieving the trajectory agreed between the ANSP and the airspace user becomes the focus. A staged approach to flight efficiency assessment is proposed to quantify the quality of the ANSP's service in terms of both "facilitating what has been agreed" and "improving what can be agreed". The framework promotes the development of more consistent efficiency performance metrics between ANSPs, as clear definitions exist for assessment references. Application of the framework was illustrated with several examples using the Airservices Dalí trajectory modeller.
International Journal of Heat and Mass Transfer, 2009
Traditional averaging methods for multilayer diffusion give inaccurate approximations of critical... more Traditional averaging methods for multilayer diffusion give inaccurate approximations of critical time behaviour, such as the heating time of a material. In particular, they fail to capture the importance of layer order. We use a perturbation expansion of an exact solution to find a simple approximate solution which accurately describes the critical time for transport across multiple layers. This approximate solution is then used to find a correction for the averaging method which captures the key critical time behaviour.
Proceedings
Go-arounds (GAs) are standard air traffic control procedures during which aircraft approach a run... more Go-arounds (GAs) are standard air traffic control procedures during which aircraft approach a runway but do not land. The incidence of a GA can subsequently affect the workload of flight crews and air traffic controllers, and might impact an airport runway’s throughput capacity. In this study, two different modeling methods for predicting the occurrence of GAs based on open-source Automatic Dependent Surveillance–Broadcast (ADS-B) and meteorological data are presented. A macroscopic model quantifies the probability of a GA within the next hour for an airport by applying a generalized additive model. A microscopic model employs a number of machine learning classifiers on trajectories of aircraft on approach in order to predict if a GA will be performed. Even though the results of the macroscopic model are promising, the information currently available to predict the probability of a GA is not detailed enough to achieve satisfactory predictions. Similarly, the microscopic model is cap...