Minimizing Makespan on Mixed Mass Production Lines of Two and Three Machines

The objective of the research discussed in this paper has been to find an optimal schedule on mixed mass production lines of two and three machines. Johnson's rule on flow shops is generalized to mixed mass production lines. Scheduling methods on three-machine lines are proposed for six special kinds of data of processing times of jobs. The scheduling method on two-machine lines is also proposed.

Solving Level Scheduling in Mixed Model Assembly Line by Simulated Annealing Method

This paper presents an application of the simulated annealing algorithm to solve level schedules in mixed model assembly line. Solving production sequences with both number of setups and material usage rates to the minimum rate will optimize the level schedule. Miltenburg algorithm (1989) is first used to get seed sequence to optimize further. For this the utility time of the line and setup time requirement on each station is considered. This seed sequence is optimized by simulated annealing. This investigation helps to understand the importance of utility in the assembly line. Up to 15 product sequences are taken and constructed by using randomizing method and find the objective function value for this. For a sequence optimization, a meta-heuristic seems much more promising to guide the search into feasible regions of the solution space. Simulated annealing is a stochastic local search meta-heuristic, which bases the acceptance of a modified neighboring solution on a probabilistic scheme inspired by thermal processes for obtaining low-energy states in heat baths. Experimental results show that the simulated annealing approach is favorable and competitive compared to Miltenburg’s constructive algorithm for the problems set considered. It is proposed to found 16,985 solutions, the time taken for computation is 23.47 to 130.35, and the simulated annealing improves 49.33% than Miltenberg.

Layout design of a mixed-flow production line based on processing energy consumption and buffer configuration

Green manufacturing is a growing trend,and an effective layout design method for production lines can reduce resource wastage in processing.This study focuses on existing problems such as low equipment utilization,long standby time,and low logistics efficiency in a mixed-flow parallel production line.To reduce the energy consumption,a novel method considering an independent buffer configuration and idle energy consumption analysis is proposed for this production line’s layout design.A logistics intensity model and a machine tool availability model are established to investigate the influences of independent buffer area configuration on the logistics intensity and machine tool availability.To solve the coupling problem between machine tools in such production lines,a decoupling strategy for the relationship between machine tool processing rates is explored.An energy consumption model for the machine tools,based on an optimized configuration of independent buffers,is proposed.This model can effectively reduce the idle energy consumption of the machine tools while designing the workshop layout.Subsequently,considering the problems encountered in workshop production,a comprehensive optimization model for the mixed-flow production line is developed.To verify the effectiveness of the mathematical model,it is applied to an aviation cabin production line.The results indicate that it can effectively solve the layout problem of mixed-flow parallel production lines and reduce the idle energy consumption of machine tools during production.The proposed buffer configuration and layout design method can serve as a theoretical and practical reference for the layout design of mixed-flow parallel production lines.

Investigation of cost, power, and spectral efficiency in fixed- and flexi-grid networks

With the steady growth of traffic volume in core networks,it is predicted that future optical network communication will be constrained mainly by cost and power consumption.Thus,for Internet sustainability,it will be necessary to ensure cost and power efficiency in optical networks.The aims of this study are(i)to identify the main sources of cost and power consumption in fixed-grid(SLR and MLR)and flexi-grid(OFDM)optical networks,and(ii)to compare techniques for improving cost and power efficiency in SLR/MLR-and OFDM-based networks.To this end,we conducted a comparative analysis of cost and power efficiency for the OFDM-and MLR/SLR-based networks,and considering realistic networks,evaluated the cost and power consumed by different components in the optical layer.Our results show that(i)OFDM-based networks outperform those based on MLR/SLR in terms of both cost and power-efficiency,(ii)the extra equipment cost incurred due to under-utilization of spectrum is reduced by switching to a flexi-grid network,(iii)lower power consumption per bit is obtained when the networking solution ensures a finer bit-rate granularity,and(iv)there exists a power and spectrum minimization trade-off that is network characteristic dependent.

On the Performance of MLR Optical WDM Network Based on ITU-T Conforming Fibers in the Presence of Dominant Physical Layer Impairments

The tremendous and consistent increase in the volume and heterogeneity of traffic has resulted in major innovations in the telecommunication networks.In regard to the optical networks,existing studies have shown that by adopting a mixed line rate(MLR)strategy,the wavelength division multiplexed optical networks can cost-effectively respond to the diverse variety of traffic requirements which have heterogeneous service demands.Unlike existing studies which focus on various MLR network issues by considering deployment of the standard single mode fiber only within the network,in the current work,we investigate the signal quality deterioration due to the combined effects of dominant physical layer impairments for an MLR optical network conforming to the various ITU-T compliant fibers and also considering the optical frequency grid based on ITU-T Recommendation G.692.The main aim of our current study is to identify,for a given fiber,the modulation format configuration which provides the highest performance.We conduct extensive simulations on the considered MLR system using the obtained optimum channel spacing values between the single and mixed line rates.Our results show that the existence of 10 Gbit/s line rate has a detrimental effect on the 40 Gbit/s and/or 100 Gbit/s line rate;however,the 40 Gbit/s and/or 100 Gbit/s line rate’s effect on a 10 Gbit/s line rate is not so detrimental,as well as between the similar line rates.Overall,our results clearly show that choice of the line rate of both,the central channel and its adjacent channels,has a major effect on the MLR network performance.