A scheduling model for production in a hot strip mill
- Authors: Hamman, Gert J. M.
- Date: 2011-12-06
- Subjects: Production scheduling , Mills and mill-work , Steel-works , Mills and mill-work technological innovations , Steel-works technological innovations , Mills and mill-work production standards , Steel-works production standards
- Type: Thesis
- Identifier: uj:1843 , http://hdl.handle.net/10210/4201
- Description: M.Ing. , This research dissertation highlights the important role of scheduling in a production environment. The functioning of an integrated iron and steel works is discussed. The importance of production scheduling in this environment is shown, followed by a literature survey of strip mill production scheduling models. Thereafter a model is introduced that aids in the production scheduling of plate via coil in a hot strip mill. Finally the benefits of the scheduling model are shown.
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Economic scheduling of steam boiler plant shut downs for targeted availability
- Authors: Els, Daniel Pieter
- Date: 2011-11-30
- Subjects: Production scheduling , Steam-boilers
- Type: Thesis
- Identifier: uj:1750 , http://hdl.handle.net/10210/4105
- Description: M.Ing. , In the highly competitive environment in which all companies have to operate, it is becoming more and more important to optimise the amount of time a piece of equipment is down for scheduled repairs and the scheduling of these repairs. In this dissertation the equipment that is considered are the seventeen Babcock Borsig designed boilers situated on the Sasol Secunda site. A schematic drawing of these boilers is shown in figure 1. This drawing does not include the Electrostatic Precipitator that is located at the outlet of the boiler. The main function of the seventeen boilers on the Secunda site is to supply process steam to the rest of the factory. With each of the plants that are supplied with process steam having its own needs at any point in time, ensuring that enough steam is available in the system becomes an extremely important issue. The reason for this is that the plants that are supplied with process steam form a train and if one of the plants can not produce to full capacity, the down stream plants are also affected. The secondary function of the boilers is to supply steam to ten turbines for the generation of electricity. This means that any steam that the factory is not using is used for the generation of electricity. The ten generators can not supply the full need of the factory and the rest is drawn in from the national electricity supplier. It is thus best to generate as much electricity as possible. With the price of electricity varying during the year, winter being more expensive, the time when a boiler is off becomes critical. To ensure that the necessary process steam is available the long term plan of the factory is used to calculate the year budget for steam required by the factory. But as with everything plans do change and a short term plan is used to ensure that enough process steam is available for the factory.
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Operating system scheduling optimization
- Authors: Anderson, George Georgevich
- Date: 2013-05-28
- Subjects: Operating systems (Computers) , Production scheduling , Computer scheduling
- Type: Thesis
- Identifier: uj:7567 , http://hdl.handle.net/10210/8430
- Description: D.Phil. (Electrical and Electronic Engineering) , This thesis explores methods for improving, or optimizing, Operating System (OS) scheduling. We first study the problem of tuning an OS scheduler by setting various parameters, or knobs, made available. This problem has not been addressed extensively in the literature, and has never been solved for the default Linux OS scheduler. We present three methods useful for tuning an Operating System scheduler in order to improve the quality of scheduling leading to better performance for workloads. The first method is based on Response Surface Methodology, the second on the Particle Swarm Optimization (PSO), while the third is based on the Golden Section method. We test our proposed methods using experiments and suitable benchmarks and validate their viability. Results indicate significant gains in execution time for workloads tuned with these methods over execution time for workloads running under schedulers with default, unoptimized tuning parameters. The gains for using RSM-based over default scheduling parameter settings are only limited by the type of workload (how much time it needs to execute); gains of up to 16:48% were obtained, but even more are possible, as described in the thesis. When comparing PSO with Golden Section, PSO produced better scheduling parameter settings, but it took longer to do so, while Golden Section produced slightly worse parameter settings, but much faster. We also study a problem very critical to scheduling on modern Central Processing Units (CPUs). Modern CPUs have multicore designs, which corresponds to having more than one CPU on a single chip. These are known as Chip Multiprocessors (CMPs). The CMP is now the standard type of CPU for many different types of computers, including Personal Computers.
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