Operational Research Commons^™

Capacity Planning For Elderly Care In Ireland Using Simluation Modeling, Mohamed Ragab, Waleed Abo-Hamad, Amr Arisha

Conference papers

Global population aging is creating an immense pressure on healthcare facilities making them unable to cope with the growing demand for elderly healthcare services. Current demand-supply gaps result in prolonged waiting times for patients and substantial cost burdens for healthcare systems due to delayed discharges. This paper describes a project aimed at presenting modeling and simulation to address elderly care pathways within the Irish healthcare sector. The management of frail patients admitted to acute hospitals and the introduction of the new intermediate care beds are alternative interventions that healthcare executives are interested in simulating to examine their impact on the ...

Global Optimization Of Dynamic Process Systems Using Complete Search Methods, Ali Mohammad Sahlodin

Open Access Dissertations and Theses

Efficient global dynamic optimization (GDO) using spatial branch-and-bound (SBB) requires the ability to construct tight bounds for the dynamic model. This thesis works toward efficient GDO by developing effective convex relaxation techniques for models with ordinary differential equations (ODEs). In particular, a novel algorithm, based upon a verified interval ODE method and the McCormick relaxation technique, is developed for constructing convex and concave relaxations of solutions of nonlinear parametric ODEs. In addition to better convergence properties, the relaxations so obtained are guaranteed to be no looser than their underlying interval bounds, and are typically tighter in practice. Moreover, they are ...

Activity-Based Travel Scenario Analysis With Routing Problem Reoptimization, Joseph Yj Chow

Civil Engineering Working Papers

Activity-based travel scenario analysis and network design using a household activity pattern problem (HAPP) can face significant computational cost and inefficiency. One solution approach, called reoptimization, makes use of an optimal solution of a prior problem instance to find a new solution faster and more accurately. Although the method is generally NP-hard as well, the approximation bound is found to be tighter than a full optimization for several traveling salesman problem variations. To date, however, there have not been any computational studies conducted with the method, nor has there been any meta-heuristics designed with reoptimization in mind, particularly for generalized ...

Nonlinear Inverse Optimization And Link-Based Freight Assignment Of Commodity And Cyclic Vehicle Flows, Joseph Yj Chow, Stephen G. Ritchie, Kyungsoo Jeong

Civil Engineering Working Papers

An inverse nonlinear optimization approach is developed to solve a new parameter estimation problem class where demand and output flows are given or observed in a congested network. Unlike earlier work in the inverse optimization area, the problem is nonlinear and formulated with Karush-Kuhn-Tucker conditions. It is shown to be solvable using classical nonlinear optimization methods. This approach is used to systematically calibrate a new link-based variant of the STAN model which assigns commodity flows to cyclic vehicles, where freight facility parameters are typically difficult to observe. Commodities flow from origin to destination but vehicle path information is given up ...

A Model For Optimizing The Allocation Of Ethanol Production In The U.S., Anali Huggins

Industrial and Management Systems Engineering -- Dissertations and Student Research

In the last five years, fuel prices have fluctuated from 2.86$/gallon to 3.87$/gallon which represents an increase of 35%. This situation has collocated the ethanol manufacturing in an advantageous situation. However, a major problem that is faced by the ethanol producers is the high cost of transportation. The objective of this thesis study is to determine the optimal allocation of ethanol production in the U.S. in 2009 that minimizes the transportation cost. This thesis is based on the application of a linear programing model. The thesis is focused on two questions. The first is the ...

Development And Validation Of A Model For Granular Material Volume Measurements, Pourya Fasounaki

Industrial and Management Systems Engineering -- Dissertations and Student Research

Keeping inventory record of packed grains in silos poses challenges since the bulk material’s different segments do not discharge uniformly, leading to formation of random peaks and valleys on the surface. To facilitate obtaining accurate volume measurement of the grains by taking into account this non-linear behavior on the surface, laser or plumb-bob level-sensing devices are employed at different part of the surface to probe the level of material under those regions.

The main goals of this research is to study the behavior of granular material in silo while discharging downward and by doing so, differentiate certain flow patterns ...