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Full-Text Articles in Physical Sciences and Mathematics

Seasonal Forcing In Stochastic Epidemiology Models, Lora Billings, Eric Forgoston Nov 2017

Seasonal Forcing In Stochastic Epidemiology Models, Lora Billings, Eric Forgoston

Lora Billings

The goal of this paper is to motivate the need and lay the foundation for the analysis of stochastic epidemiological models with seasonal forcing.We consider stochastic SIS and SIR epidemic models, where the internal noise is due to the random interactions of individuals in the population. We provide an overview of the general theoretic framework that allows one to understand noise-induced rare events, such as spontaneous disease extinction. Although there are many paths to extinction, there is one path termed the optimal path that is probabilistically most likely to occur. By extending the theory, we have identified the quasi-stationary solutions …


Seasonal Forcing In Stochastic Epidemiology Models, Lora Billings, Eric Forgoston Nov 2017

Seasonal Forcing In Stochastic Epidemiology Models, Lora Billings, Eric Forgoston

Eric Forgoston

The goal of this paper is to motivate the need and lay the foundation for the analysis of stochastic epidemiological models with seasonal forcing.We consider stochastic SIS and SIR epidemic models, where the internal noise is due to the random interactions of individuals in the population. We provide an overview of the general theoretic framework that allows one to understand noise-induced rare events, such as spontaneous disease extinction. Although there are many paths to extinction, there is one path termed the optimal path that is probabilistically most likely to occur. By extending the theory, we have identified the quasi-stationary solutions …


Existence Results For Multivalued Operators Of Monotone Type In Reflexive Banach Spaces, Dhruba Adhikari Nov 2017

Existence Results For Multivalued Operators Of Monotone Type In Reflexive Banach Spaces, Dhruba Adhikari

Dhruba Adhikari

No abstract provided.


Time Varying Parameter Estimation Scheme For A Linear Stochastic Differential Equation.Pdf, Michael Otunuga Aug 2017

Time Varying Parameter Estimation Scheme For A Linear Stochastic Differential Equation.Pdf, Michael Otunuga

Olusegun Michael Otunuga

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In this work, an attempt is made to estimate time varying parameters in a linear stochastic differential equation. By defining $m_{k}$ as the local admissible sample/data observation size at time $t_{k}$, parameters and state at time $t_{k}$ are estimated using past data on interval $[t_{k-m_{k}+1}, t_{k}]$. We show that the parameter estimates at each time $t_{k}$ converge in probability to the true value of the parameters being estimated. A numerical simulation is presented by applying the local lagged adapted generalized method of moments (LLGMM) method to the stochastic differential models governing prices …


Adoption Of Switchgrass Cultivation For Biofuel Under Uncertainty: A Discrete-Time Modeling Approach, Pralhad Burli, Eric Forgoston, Pankaj Lal, Lora Billings, Bernabas Wolde Jul 2017

Adoption Of Switchgrass Cultivation For Biofuel Under Uncertainty: A Discrete-Time Modeling Approach, Pralhad Burli, Eric Forgoston, Pankaj Lal, Lora Billings, Bernabas Wolde

Lora Billings

Production of biofuels from cellulosic sources, such as switchgrass, is being encouraged through mandates, incentives, and subsidies. However, uncertainty in future prices coupled with large establishment costs often inhibit their cultivation. Owing to their inability to incorporate uncertainty and dynamic decision-making, standard discounted cash flow techniques are ineffective for analyzing such investments. We formulate a discrete-time binomial framework to model output prices, allowing us to incorporate price uncertainty, stand age, and variable crop yields into the analytical framework. We analyze the feasibility of investments in switchgrass cultivation under varying price transition paths, evaluate the relationship between risk …


Adoption Of Switchgrass Cultivation For Biofuel Under Uncertainty: A Discrete-Time Modeling Approach, Pralhad Burli, Eric Forgoston, Pankaj Lal, Lora Billings, Bernabas Wolde Jul 2017

Adoption Of Switchgrass Cultivation For Biofuel Under Uncertainty: A Discrete-Time Modeling Approach, Pralhad Burli, Eric Forgoston, Pankaj Lal, Lora Billings, Bernabas Wolde

Eric Forgoston

Production of biofuels from cellulosic sources, such as switchgrass, is being encouraged through mandates, incentives, and subsidies. However, uncertainty in future prices coupled with large establishment costs often inhibit their cultivation. Owing to their inability to incorporate uncertainty and dynamic decision-making, standard discounted cash flow techniques are ineffective for analyzing such investments. We formulate a discrete-time binomial framework to model output prices, allowing us to incorporate price uncertainty, stand age, and variable crop yields into the analytical framework. We analyze the feasibility of investments in switchgrass cultivation under varying price transition paths, evaluate the relationship between risk …


Adoption Of Switchgrass Cultivation For Biofuel Under Uncertainty: A Discrete-Time Modeling Approach, Pralhad Burli, Eric Forgoston, Pankaj Lal, Lora Billings, Bernabas Wolde Jul 2017

Adoption Of Switchgrass Cultivation For Biofuel Under Uncertainty: A Discrete-Time Modeling Approach, Pralhad Burli, Eric Forgoston, Pankaj Lal, Lora Billings, Bernabas Wolde

Pankaj Lal

Production of biofuels from cellulosic sources, such as switchgrass, is being encouraged through mandates, incentives, and subsidies. However, uncertainty in future prices coupled with large establishment costs often inhibit their cultivation. Owing to their inability to incorporate uncertainty and dynamic decision-making, standard discounted cash flow techniques are ineffective for analyzing such investments. We formulate a discrete-time binomial framework to model output prices, allowing us to incorporate price uncertainty, stand age, and variable crop yields into the analytical framework. We analyze the feasibility of investments in switchgrass cultivation under varying price transition paths, evaluate the relationship between risk …


Nontrivial Solutions Of Inclusions Involving Perturbed Maximal Monotone Operators, Dhruba Adhikari Jun 2017

Nontrivial Solutions Of Inclusions Involving Perturbed Maximal Monotone Operators, Dhruba Adhikari

Dhruba Adhikari

No abstract provided.


A Management Maturity Model (Mmm) For Project-Based Organisational Performance Assessment, Craig Langston, Amir Ghanbaripour Jun 2017

A Management Maturity Model (Mmm) For Project-Based Organisational Performance Assessment, Craig Langston, Amir Ghanbaripour

Amir Ghanbaripour

Common sense suggests that organisations are more likely to deliver successful projects if they have systems in place that reflect a mature project environment based on a culture of continuous improvement. This paper develops and discusses a Management Maturity Model (MMM) to assess the maturity of project management organisations through a customisable, systematic, strategic and practical methodology inspired from the seminal work of Darwin, Deming, Drucker and Daniel. The model presented is relevant to organisations, such as construction and engineering companies, that prefer to use the Project Management Body of Knowledge (PMBOK™ Guide) published by the Project Management Institute (PMI), …


When Cp(X) Is Domain Representable, William Fleissner, Lynne Yengulalp Mar 2017

When Cp(X) Is Domain Representable, William Fleissner, Lynne Yengulalp

Lynne Yengulalp

Let M be a metrizable group. Let G be a dense subgroup of MX . If G is domain representable, then G = MX . The following corollaries answer open questions. If X is completely regular and Cp(X) is domain representable, then X is discrete. If X is zero-dimensional, T2 , and Cp(X;D) is subcompact, then X is discrete.


Sphere Representations, Stacked Polytopes, And The Colin De Verdière Number Of A Graph, Lon Mitchell, Lynne Yengulalp Mar 2017

Sphere Representations, Stacked Polytopes, And The Colin De Verdière Number Of A Graph, Lon Mitchell, Lynne Yengulalp

Lynne Yengulalp

We prove that a k-tree can be viewed as a subgraph of a special type of (k + 1)- tree that corresponds to a stacked polytope and that these “stacked” (k + 1)-trees admit representations by orthogonal spheres in R k+1. As a result, we derive lower bounds for Colin de Verdi`ere’s µ of complements of partial k-trees and prove that µ(G) + µ(G) > |G| − 2 for all chordal G.


Coarser Connected Topologies And Non-Normality Points, Lynne Yengulalp Mar 2017

Coarser Connected Topologies And Non-Normality Points, Lynne Yengulalp

Lynne Yengulalp

We investigate two topics, coarser connected topologies and non-normality points. The motivating question in the first topic is:

Question 0.0.1. When does a space have a coarser connected topology with a nice topological property? We will discuss some results when the property is Hausdorff and prove that if X is a non-compact metric space that has weight at least c, then it has a coarser connected metrizable topology. The second topic is concerned with the following question:

Question 0.0.2. When is a point y ∈ β X\X a non-normality point of β X\X? We will discuss the question in the …


Non-Normality Points Of Β X\X, William Fleissner, Lynne Yengulalp Mar 2017

Non-Normality Points Of Β X\X, William Fleissner, Lynne Yengulalp

Lynne Yengulalp

We seek conditions implying that (β X\X) \ {y} is not normal. Our main theorem: Assume GCH and all uniform ultrafilters are regular. If X is a locally compact metrizable space without isolated points, then (β X\X) \ {y} is not normal for all y ∈ β X\X. In preparing to prove this theorem, we generalize the notions “uniform”, “regular”, and “good” from set ultrafilters to z-ultrafilters. We discuss non-normality points of the product of a discrete space and the real line. We topologically embed a nonstandard real line into the remainder of this product space.


A Discontinuous Galerkin Method For Unsteady Two-Dimensional Convective Flows, Andreas C. Aristotelous, N. C. Papanicolaou Feb 2017

A Discontinuous Galerkin Method For Unsteady Two-Dimensional Convective Flows, Andreas C. Aristotelous, N. C. Papanicolaou

Andreas Aristotelous

We develop a High-Order Symmetric Interior Penalty (SIP) Discontinuous Galerkin (DG) Finite Element Method (FEM) to investigate two-dimensional in space natural convective flows in a vertical cavity. The physical problem is modeled by a coupled nonlinear system of partial differential equations and admits various solutions including stable and unstable modes in the form of traveling and/or standing waves, depending on the governing parameters. These flows are characterized by steep boundary and internal layers which evolve with time and can be well-resolved by high-order methods that also are adept to adaptive meshing. The standard no-slip boundary conditions which apply on the …


Global Stability Of Nonlinear Stochastic Sei Epidemic Model With Fluctuations In Transmission Rate Of Disease, Olusegun M. Otunuga Jan 2017

Global Stability Of Nonlinear Stochastic Sei Epidemic Model With Fluctuations In Transmission Rate Of Disease, Olusegun M. Otunuga

Olusegun Michael Otunuga

We derive and analyze the dynamic of a stochastic SEI epidemic model for disease spread. Fluctuations in the transmission rate of the disease bring about stochasticity in model. We discuss the asymptotic stability of the infection-free equilibrium by first deriving the closed form deterministic ($R_{0}$) and stochastic ($\mathcal{R}_{0}$) basic reproductive number. Contrary to some author's remark that different diffusion rates have no effect on the stability of the disease-free equilibrium, we showed that even if no epidemic invasion occurs with respect to the deterministic version of the SEI model (that is, $R_{0}<1$), epidemic can still …


Modified Error In Constitutive Equations (Mece) Approach For Ultrasound Elastography Jan 2017

Modified Error In Constitutive Equations (Mece) Approach For Ultrasound Elastography

Susanta Ghosh

No abstract provided.


Application Of Polynomial Interpolation In The Chinese Remainder Problem, Tian-Xiao He, S. Macdonald, P. J.-S. Shiue Dec 2016

Application Of Polynomial Interpolation In The Chinese Remainder Problem, Tian-Xiao He, S. Macdonald, P. J.-S. Shiue

Tian-Xiao He

This paper presents an application of polynomial interpolation in the solution of the Chinese Remainder Problem for bother integers and polynomials.


15004.Pdf, Marcus C. Randall Dec 2016

15004.Pdf, Marcus C. Randall

Marcus Randall

Increasing human populations and the continual change of the Earth’s climate has meant that food security is becoming an increasingly important issue. One of the main factors contributing to food security is the availability of water for agricultural purposes. Recently, a few models have been proposed for water management problems in agricultural contexts which aim to maximise crop yield (i.e., farm and regional profitability) while minimising the effect that this has on the environment. It is the exploration of the latter that is of the most interest given the above, and hence the subject of this paper. As a refinement …