The MIIS Eprints Archive: No conditions. Results ordered -Date Deposited. 2019-04-23T10:22:46ZEPrintshttp://www.maths-in-industry.org/images/sitelogo.gifhttp://www.maths-in-industry.org/miis/2013-12-04T23:34:43Z2015-05-29T20:15:29Zhttp://www.maths-in-industry.org/miis/id/eprint/634This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/6342013-12-04T23:34:43ZPrediction of sanding in subsurface hydrocarbon reservoirs.Sand production in oil and gas wells can occur if the fluid velocity exceeds a
certain value. Due to drilling operations, the mechanical stresses can exceed the load bearing capacity of the rock. As the local stresses exceed certain level, a certain amount of rock is fractured into sand. Then, the sand is carried by the fluid through the wellbore depending on the flow rate. The amount of the solids can be less than a few grams per cubic meter of reservoir fluid or an essential amount. In the later case erosion of the rock and removing sufficient quantities of rock can occur. This can produce subsurface cavities which collapse and destroy the well.

When sanding is unavoidable it is necessary to estimate the characteristics of the process. Our aim was to generate a simple one-dimensional local model, which predicts the volume of sanding, the radius and the porosity of the yielded zone. Such model will help the company in the development of complex 3D models.H. OckendonS. StoykovT. ZorawikS. DimovaI. GeorgievN. KolkovskaM. TodorovD. Vasileva2013-12-04T23:28:06Z2015-05-29T20:15:26Zhttp://www.maths-in-industry.org/miis/id/eprint/633This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/6332013-12-04T23:28:06ZLaboratory calibration of a MEMS accelerometer sensorIn the present work we address MEMS accelerometers. There are many sources of error that affect their behaviour. In this report, we present two mathematical models and associated algorithms for calibrating the device, i.e. compensating for the constant bias error (the offset of its output signal, when the device does not undergo any acceleration), scaling errors (the deviation of the accelerometer’s scale from the unit we want to use, like m/s2 ) and nonorthogonality of the axis.I. GeorgievaC. HofreitherT. IlievaT. IvanovS. Nakov2013-12-04T23:22:53Z2015-05-29T20:15:21Zhttp://www.maths-in-industry.org/miis/id/eprint/632This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/6322013-12-04T23:22:53ZMini Max WallpaperMini Max company formulated a problem for the automatic calculation of the number of wallpaper rolls necessary for decorating a room with wallpaper. The final goal is the development of a web-based calculator open for use to both Mini Max staff and the general public. We propose an approach for reducing the studied problem to the one-dimensional cutting-stock problem. We show this in details for the case of plain wallpapers as well as for the case of patterned wallpapers with straight match. The one-dimensional cutting-stock problem can be formulated as a linear integer programming problem. We develop an approach for calculating the needed number of wallpapers for relatively small problems, create an algorithm in a suitable graphical interface and make different tests. The tests show the efficiency of the proposed approach compared with the existent (available) wallpapers’ calculators.A. MarigondaD. AleksovJ. IdziakK. GeorgievM. KozlowskiM. KrastanovM. VenevaM. SikoraS. Angelov2013-12-04T23:15:36Z2015-05-29T20:15:17Zhttp://www.maths-in-industry.org/miis/id/eprint/631This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/6312013-12-04T23:15:36ZOptimization of the charging process in zinc hydrometallurgyThe main objective is to optimize the charging process in zinc metallurgy with respect to the technological price of the input components’ mixture. Assuming that the concentrate mixture is a linear combination of the charge components we decided to use the well-known linear optimization techniques including both real and integer ones. As the input data example could be presented in a table-like form we decided to use the commonly available MS EXCEL product with its built-in SOLVER [2].A. PeltekovD. BoyadzhievM. KozloskiZ. VarbanovZ. Minchev2013-12-04T23:04:35Z2015-05-29T20:15:13Zhttp://www.maths-in-industry.org/miis/id/eprint/630This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/6302013-12-04T23:04:35ZEstimation of errors in text and data processingThe company Adiss Lab Lts. obtained 1 000 000 medical reports that are either in free form text, or in XML format. One of the main goals of their development is to integrate an algorithm for information extraction (IE) in their platform. The verification of the algorithm’s output for a report is done by a medical doctor (MD) for a certain fee. Validating the correctness of all data would be overwhelming and very expensive. Hence, the problem, as presented by the company, is to provide a method (algorithm) which determines the minimum amount of reports that will validate the correctness of the IE algorithm and a procedure for selecting these reports.

In order to solve the problem we have considered an algorithm-centric approach uses active learning and semi-supervised learning.A. SlavovaB. ValkovK. TonchevN. DaskalovaM. NikolovaM. BivasP. MateevR. YordanovaS. Zhelezova2013-12-04T22:55:18Z2015-05-29T20:15:09Zhttp://www.maths-in-industry.org/miis/id/eprint/629This item is in the repository with the URL: http://www.maths-in-industry.org/miis/id/eprint/6292013-12-04T22:55:18ZCompressed representation of a partially defined integer function over multiple argumentsIn OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one?N. DaskalovaP. MateevS. Zhelezova