The MIIS Eprints Archive: No conditions. Results ordered -Date Deposited. 2021-08-05T15:43:14ZEPrintshttp://miis.maths.ox.ac.uk/images/sitelogo.gifhttp://miis.maths.ox.ac.uk/miis/2008-01-24Z2015-05-29T19:47:42Zhttp://miis.maths.ox.ac.uk/miis/id/eprint/120This item is in the repository with the URL: http://miis.maths.ox.ac.uk/miis/id/eprint/1202008-01-24ZAn Optimal Strategy for Maintaining Excess CapacityBoeing is a manufacturing industry with very low production volumes of very large units. As such, they experience huge fluctuations in demand. A standard inventory model dictates massive changes in production capacity as demand varies. However all such models assume a continuous production stream. In this report we investigate the following question whether such a model is sensible in a problem of such large scale granularity. We describe a combination of stochastic, financial and simulation models to model the production of airplanes. A preliminary simulation of the model is also presented.Daya Gaur2008-01-24Z2015-05-29T19:47:43Zhttp://miis.maths.ox.ac.uk/miis/id/eprint/121This item is in the repository with the URL: http://miis.maths.ox.ac.uk/miis/id/eprint/1212008-01-24ZInventory Optimization using a Renewal Model for SalesAny optimization requires a realistic and simple model to predict future sales. The problem presenter had suggested that sales might arrive according to a Poisson distribution. We suggest that the company look at renewal theory for models of future sales orders. They have some very distinct advantages. They are powerful and easy to use, in fact the Poisson distribution is a special case. Renewal models are flexible enough to incorporate a variety of characteristics, such as clustering or regularity, upward or downward drift, and mean reversion. Also, some arguments can be made to justify the renewal models based on financial intuition. A realistic (albeit naive) problem is set up which has an analytic solution and other solution methods are discussed.Mark Paulhus2008-01-24Z2015-05-29T19:47:44Zhttp://miis.maths.ox.ac.uk/miis/id/eprint/122This item is in the repository with the URL: http://miis.maths.ox.ac.uk/miis/id/eprint/1222008-01-24ZA Problem in Petroleum Reservoir SimulationThe problem posed was to find an exact solution to the equations governing two-phase petroleum reservoirs that could be used to validate the numerical code used by the Computer Modeling Group in its simulations. Ideally, the analysis would result in an exact solution to the coupled system of equations for a specific rectangular geometry. It was soon realized that this was a hopeless task, so the group set out to find compromises that would still provide useful validation examples.Brian Seymour2008-01-24Z2015-05-29T19:47:45Zhttp://miis.maths.ox.ac.uk/miis/id/eprint/123This item is in the repository with the URL: http://miis.maths.ox.ac.uk/miis/id/eprint/1232008-01-24ZOn Seismic Imaging: Geodesics, Isochrons, and Fermat's PrincipleAnalytic expressions are derived for the isochrons in an inhomogeneous medium characterized by a linear velocity gradient and for an anisotropic medium characterized by an elliptical velocity dependence. The results were generated for a single surface source and five wellbore receivers over a dipping interface. The traveltime and reflection-point results appear to be sensitive to a given assumption of the velocity field. In complex geological areas the location of the planar reflector is tangent to the convex hull of isochrons and might not correspond to their intersection points since the two concepts need to coincide.Paul Webster2008-01-24Z2015-05-29T19:47:47Zhttp://miis.maths.ox.ac.uk/miis/id/eprint/124This item is in the repository with the URL: http://miis.maths.ox.ac.uk/miis/id/eprint/1242008-01-24ZTripwire Detection for LandminesPre-processed Radon transform-based detection methods were identified as the most viable technique. There are some issues that arose when testing the various methods. A) The 'log' edge detection in Matlab seemed better than the default 'sobel' method, but is still worth considering other edge detection algorithms that might deal more effectively with noisy or grainy image. B) The algorithm works best when the wire is horizontal and spans the length of the image. If constrained to thin-strip type images then a simple solution is to run the algorithm twice, once with the image and a second time with the same image rotated through 45 degrees.Chris BuddJohn Stockie2008-01-24Z2015-05-29T19:47:48Zhttp://miis.maths.ox.ac.uk/miis/id/eprint/125This item is in the repository with the URL: http://miis.maths.ox.ac.uk/miis/id/eprint/1252008-01-24ZTorsion in Multistrand CablesBody couples between the layers of wire were introduced and taken to be proportional to the body force between the layers with a coefficient of friction as the constant of proportionality. These friction coefficients were taken to be free parameters a sequence of numerical experiments. The results were unconvincing and although they suggest that the changes were at least not in the wrong direction, they are not recommended as a solution to the problem. A more detailed investigation is warranted which carefully considers the number of contact points between the layers and direction in which the frictional forces act.Rex Westbrook2008-01-24Z2015-05-29T19:47:49Zhttp://miis.maths.ox.ac.uk/miis/id/eprint/126This item is in the repository with the URL: http://miis.maths.ox.ac.uk/miis/id/eprint/1262008-01-24ZAutomatic Detection of Egg Shell CracksThe challenge was to find a reliable, non-intrusive means of detecting cracks in eggs. Intensity data from eggs were collected by VisionSmart for the group to analyse. Given the short time period three main questions were addressed. 1) Is there a feature of the intensity data which detects, and discriminates between pinholes, cage marks and cracks? 2) Are there ways to improve the current data collection process? 3) Are there other data collection methods which should be tried? A partial positive response to 1) is presented and describes the many problems that arose. Some answers to 2) and 3) are also presented.Rachel KuskeDavid LyderJonathan SamuelChris SoterosDavid Wolfe