Decision Making in Manufacturing and Services
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ISSN 1896-8325
e-ISSN: 2300-7087
Issue Date
2007
Volume
Vol. 1
Number
No. 1/2
Description
Journal Volume
Decision Making in Manufacturing and Services
Vol. 1 (2007)
Projects
Pages
Articles
Three-machine flowshop scheduling problem to minimize total completion time with bounded setup and processing times
(2007) Allahverdi, Ali
The three-machine flowshop scheduling problem to minimize total completion time is studied where setup times are treated as separate from processing times. Setup and processing times of all jobs on all machines are unknown variables before the actual occurrence of these times. The lower and upper bounds for setup and processing times of each job on each machine is the only information that is available. In such a scheduling environment, there may not exist a unique schedule that remains optimal for all possible realizations of setup and processing times. Therefore, it is desired to obtain a set of dominating schedules (which dominate all other schedules) if possible. The objective for such a scheduling environment is to reduce the size of dominating schedule set. We obtain global and local dominance relations for a three-machine flowshop scheduling problem. Furthermore, we illustrate the use of dominance relations by numerical examples and conduct computational experiments on randomly generated problems to measure the effectiveness of the developed dominance relations. The computational experiments show that the developed dominance relations are quite helpful in reducing the size of dominating schedules.
Batch scheduling of deteriorating products
(2007) Barketau, Maksim S.; Cheng, T. C. Edwin; Kovalëv, Mihail Y.; Ng, C. T. Daniel
In this paper we consider the problem of scheduling $N$ jobs on a single machine, where the jobs are processed in batches and the processing time of each job is a simple linear increasing function depending on job's waiting time, which is the time between the start of the processing of the batch to which the job belongs and the start of the processing of the job. Each batch starts from the setup time $S$. Jobs which are assigned to the batch are being prepared for the processing during time $S_{0} < S$. After this preparation they are ready to be processed one by one. The non-negative number $b_i$ is associated with job $i$. The processing time of the $i$-th job is equal to $b_{i}(s_{i} - (s_{i}^{b} + S0))$, where $s_{i}^{b}$ and $s_i$ are the starting time of the $b$-th batch to which the $i$-th job belongs and the starting time of this job, respectively. The objective is to minimize the completion time of the last job. We show that the problem is NP-hard. After that we present an $O(N)$ time algorithm solving the problem optimally for the case $b_{i} = b$. We further present an $O(N^{2})$ time approximation algorithm with a performance guarantee 2.
Optimizing modular machining line design problem with mixed activation mode of machining units
(2007) Belmokhtar, Sana; Dolgui, Alexandre; Delorme, Xavier; Ignatenko, Ivan
A modular transfer line designing problem is investigated. The problem is to find the best subset of modules (machining units) from a given set and to assign them to different stations so that technological constraints and cycle upper limit are respected and the line cost is minimal. The investigated lines have a mixed activation mode for the machining units of each station, i. e. the units of each station are arranged into a series of stages such that each stage is composed of several units activated in parallel. A mixed integer program approach is proposed to model and solve the corresponding design problem. Improvements are suggested in order to reduce the model size and speed up the computations.
The errors-in-variable model in the optimal portfolio construction
(2007) Czapkiewicz, Anna; Machowska, Małgorzata
In the paper we consider a modification of Sharpe's method used in classical portfolio analysis for optimal portfolio building. The conventional theory assumes there is a linear relationship between asset's return and market portfolio return, while the influence of all the other factors is not included. We propose not to neglect them any more, but include them into a model. Since the factors in question are often hard to measure or even characterize, we treat them as a disturbances on random variables used by classical Sharpe's method. The key idea of the paper is the modification of the classical approach by application of the errors-in-variable model. We assume that both independent (market portfolio return) as well as dependent (given asset's return) variables are randomly distributed values related with each other by linear relationship and we build the model used for parameters' estimation. To verify the model, we performed an analysis based on archival data from Warsaw Stock Exchange. The results are also included.
Resource management in machine scheduling problems a survey
(2007) Janiak, Adam; Janiak, Władysław; Lichtenstein, Maciej
The paper is a survey devoted to job scheduling problems with resource allocation. We present the results available in the scientific literature for commonly used models of job processing times and job release dates, i.e., the models in which the job processing time or the job release date is given as a linear or convex function dependent on the amount of the additional resource allotted to the job. The scheduling models with resource dependent processing times or resource dependent release dates extend the classical scheduling models to reflect more precisely scheduling problems that appear in real life. Thus, in this paper we present the computational complexity results and solution algorithms that have been developed for this kind of problems.