scholarly journals EXISTENCE AND SIZING OF BUFFERS IN PARALLEL ASSEMBLY LINES WITH MULTI-LINE WORKSTATIONS AND DIFFERENT CYCLE TIMES

2021 ◽  
Vol 9 (1) ◽  
pp. [10 p.]-[10 p.]
Author(s):  
RAFAEL PASTOR MORENO ◽  
HARRY AGUILAR GAMARRA ◽  
ALBERTO GARCIA VILLORIA
Keyword(s):  
Programming Model ◽  
Mixed Integer ◽  
Buffer Size ◽  
Assembly Lines ◽  
Cycle Times ◽  
Task Sequencing ◽  
Buffer Sizing ◽  
Sequencing And Scheduling ◽  
Parallel Assembly ◽  
First Time

ABSTRACT: Parallel Assembly Lines with multi-line stations (PALBs) have been widely studied in recent years because PALBs can help improve the efficiency of a production system. However, the need of buffers has not been considered in the PALBP literature. In this study, for the first time in the literature, it is shown and demonstrated the need to consider the use of buffers in this type of line when their cycle times are different. Moreover, the buffer sizing problem in a multi-line workstation is presented and formalized. It is shown that the sequencing and scheduling of the task influences the buffer size. Finally, the designed resolution method is shown: solve a mixed integer linear programming model with a commercial software, with the objective of minimizing the size of the buffers. Keywords: Parallel assembly lines balancing, buffer sizing, task sequencing and scheduling.

MATHEMATICAL MODELS FOR BUFFER SIZING PROBLEMS IN PARALLEL ASSEMBLY LINES WITH MULTI-LINE STATIONS AND DIFFERENT CYCLE TIMES

10.6036/10223 ◽  
2021 ◽  
Vol 96 (6) ◽  
pp. 563-563
Author(s):  
HARRY AGUILAR GAMARRA ◽  
ALBERTO GARCIA VILLORIA ◽  
RAFAEL PASTOR MORENO
Keyword(s):  
Mathematical Models ◽  
Assembly Line ◽  
Production Systems ◽  
Assembly Lines ◽  
Cycle Times ◽  
Buffer Sizing ◽  
Parallel Assembly

In industry there are production systems consisting of more than one assembly line. If these are close together, it is possible for an operator to perform tasks from two adjacent lines assigned to his station (this will be a "multi-line station")

The PHEV Charging Infrastructure Planning (PCIP) Problem

2010 ◽  
Vol 11 (2) ◽  
Author(s):  
Yogesh Dashora ◽  
John W Barnes ◽  
Rekha S Pillai ◽  
Todd E Combs ◽  
Michael Hilliard ◽  
...  
Keyword(s):  
Programming Model ◽  
National Laboratory ◽  
Ghg Emissions ◽  
Geographic Location ◽  
Mixed Integer ◽  
Infrastructure Planning ◽  
Charging Infrastructure ◽  
Oak Ridge ◽  
Charging Station ◽  
First Time

Increasing debates over a gasoline independent future and the reduction of greenhouse gas (GHG) emissions has led to a surge in plug-in hybrid electric vehicles (PHEVs) being developed around the world. The majority of PHEV related research has been directed at improving engine and battery operations, studying future PHEV impacts on the grid, and projecting future PHEV charging infrastructure requirements. Due to the limited all-electric range of PHEVs, a daytime PHEV charging infrastructure will be required for most PHEV daily usage. In this paper, for the first time, we present a mixed integer mathematical programming model to solve the PHEV charging infrastructure planning (PCIP) problem for organizations with thousands of people working within a defined geographic location and parking lots well suited to charging station installations. Our case study, based on the Oak Ridge National Laboratory (ORNL) campus, produced encouraging results, indicates the viability of the modeling approach and substantiates the importance of considering both employee convenience and appropriate grid connections in the PCIP problem.

Aircraft sequencing and scheduling in TMAs under wind direction uncertainties

2020 ◽  
Vol 124 (1282) ◽  
pp. 1896-1912
Author(s):  
R.K. Cecen ◽  
C. Cetek ◽  
O. Kaya
Keyword(s):  
Stochastic Model ◽  
Wind Direction ◽  
Simulated Annealing Algorithm ◽  
Programming Model ◽  
Air Traffic ◽  
Mixed Integer ◽  
Scheduling Problems ◽  
Traffic Demand ◽  
Proposed Model ◽  
Sequencing And Scheduling

ABSTRACTAircraft sequencing and scheduling within terminal airspaces has become more complicated due to increased air traffic demand and airspace complexity. A stochastic mixed-integer linear programming model is proposed to handle aircraft sequencing and scheduling problems using the simulated annealing algorithm. The proposed model allows for proper aircraft sequencing considering wind direction uncertainties, which are critical in the decision-making process. The proposed model aims to minimise total aircraft delay for a runway airport serving mixed operations. To test the stochastic model, an appropriate number of scenarios were generated for different air traffic demand rates. The results indicate that the stochastic model reduces the total aircraft delay considerably when compared with the deterministic approach.

A genetic algorithm for supermarket location problem

2015 ◽  
Vol 35 (1) ◽  
pp. 122-127 ◽  
Author(s):  
Mohammed Alnahhal ◽  
Bernd Noche
Keyword(s):  
Genetic Algorithm ◽  
Mixed Model ◽  
Location Problem ◽  
Programming Model ◽  
Fixed Costs ◽  
Assembly Lines ◽  
Content Type ◽  
Mixed Model Assembly Lines ◽  
Mutation Operators ◽  
First Time

Purpose – This purpose of this paper is to investigate the location problem of supermarkets, feeding by material the mixed model assembly lines using tow trains. It determines the number and the locations of these supermarkets to minimize transportation and inventory fixed costs of the system. Design/methodology/approach – This is done using integer programming model and real genetic algorithm (RGA) in which custom chromosomes representation, two custom mating and two custom mutation operators were proposed. Findings – The performance of RGA is very good since it gives results that are very close or identical to the optimal ones in reasonable CPU time. Research limitations/implications – The study is applicable only if a group of supermarkets feed the same assembly line. Originality/value – For the first time in supermarket location problem, limitation on availability of some areas for possible supermarkets ' locations and capacity of the supermarkets were taken into consideration.

scholarly journals Explicit Modelling of Multi-Period Setup Times in Proportional Lot-Sizing Problem with Constant Capacity

2021 ◽  
Author(s):  
Waldemar Kaczmarczyk
Keyword(s):  
Programming Model ◽  
Lot Sizing ◽  
A Priori ◽  
Planning Horizon ◽  
Computational Effort ◽  
Setup Times ◽  
Mixed Integer ◽  
New Model ◽  
Cycle Times ◽  
Work In Process

Abstract The planning horizon of small bucket models is often divided into many fictitious micro-periods, with non-zero demand only in the last micro-period of each real (macro-)period. On the one hand, such models ensure schedules with short cycle times and low work-in-process inventory in multilevel systems; on the other, they make setup times that are longer than a single period more likely. This paper presents a new mixed-integer programming model for the case with setup operations that overlap multiple periods. The new model assumes that the capacity is constant in the whole planning horizon and explicitly determines the entire schedule of each changeover. Moreover, a two-level MIP heuristic is presented that uses model-specific cuts to fix a priori some minor decisions. The results of the computational experiments show that the new model and MIP heuristic require a substantially smaller computational effort from a standard MIP solver than the known models.MSC Classification: 90B30 , 90C11

A decision model for kitting and line stocking with variable operator walking distances

2015 ◽  
Vol 35 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Veronique Limère ◽  
Hendrik Van Landeghem ◽  
Marc Goetschalckx
Keyword(s):  
Space Constraint ◽  
Decision Model ◽  
Programming Model ◽  
Third Party ◽  
Mixed Integer ◽  
Future Research ◽  
Assembly Lines ◽  
Content Type ◽  
Variable Operator ◽  
Assignment Model

Purpose – The purpose of this paper is to propose a decision model to choose between kitting and line stocking at the level of single parts, while taking into account the variable operator walking distances. Different ways of feeding assembly lines, such as kitting and line stocking not only have an impact on in-plant logistics flows but also determine the amount of stock that is available at the line. This, in turn, has an impact on operator walking distances during assembly. Design/methodology/approach – A mixed integer linear programming model is developed for the assignment of parts to one of both methods, and to be able to extensively test the model, an algorithm is created for the construction of representative datasets. Findings – Parts are often kitted because of a space constraint at the line, but even without a space constraint, the shorter walking distances might give preference to kitting. An analysis is presented that demonstrates how specific part characteristics influence the chances of a part being kitted. Research limitations/implications – Our research model can be extended to include, e.g., the study of alternative in-plant logistic designs and the outsourcing of kitting to a third-party logistics provider (3PL) or to the suppliers. Practical implications – The objective assignment model and the insights obtained from it are valuable for logistics and production engineers that otherwise have to rely solely on intuition. In situations with thousands of components, intuition mostly falls far short. Originality/value – First, existing models do not consider variable walking distances, which are shown to have a crucial impact on the decision. Second, the data instances created allow for a systematic comparison of future research in the field.

scholarly journals A Branch-and-Price Algorithm for Balancing Two-Sided Assembly Lines with Zoning Constraints

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Qidong Yin ◽  
Xiaochuan Luo ◽  
Julien Hohenstein
Keyword(s):  
Large Scale ◽  
Manufacturing Industry ◽  
Assembly Line ◽  
Programming Model ◽  
Assembly Line Balancing ◽  
Mixed Integer ◽  
Branch And Price ◽  
Assembly Lines ◽  
Real World Datasets ◽  
Assembly Production

Two-sided assembly lines are widely used in the large-size product manufacturing industry, especially for automotive assembly production. Balancing the assembly line is significant for assembly process planning and assembly production. In this study, we develop a novel and exact method to optimize the two-sided assembly line balancing problem with zoning constraints (TALBz), in which the aim is to minimize the number of mated-stations considering the task restrictions. A mixed-integer programming model is employed to exactly describe the TALBz problem. To strengthen the computational efficiency, we apply Dantzig–Wolfe decomposition to reformulate the TALBz problem. We further propose a branch-and-price (B&P) algorithm that integrates the column generation approach into a branch-and-bound frame. Both the benchmark datasets with zoning constraints and without zoning constraints are tested to evaluate the performance of the B&P algorithm. The numerical results show that our proposed approach can obtain optimal solutions efficiently on most cases. In addition, experiments on the real-world datasets originating from passenger vehicle assembly lines are conducted. The proposed B&P algorithm shows its advantage in tackling practical problems with the task restrictions. This developed methodology therefore provides insight for solving large-scale TALBz problems in practice.

Analysis on the Penetration Level of Wind Farm Considering Transient Stability Constraint and Uncertainty of Wind Power

2020 ◽  
Vol 13 (7) ◽  
pp. 1078-1086
Author(s):  
Bai Hao ◽  
Huang Andi ◽  
Zhou Changcheng
Keyword(s):  
Wind Power ◽  
Energy Function ◽  
Wind Farm ◽  
Transient Stability ◽  
Programming Model ◽  
Forecast Error ◽  
Credibility Theory ◽  
Mixed Integer ◽  
Stability Constraint ◽  
Level Problem

Background: The penetration level of a wind farm with transient stability constraint and static security constraint has been a key problem in wind power applications. Objective: The study explores maximum penetration level problem of wind considering transient stability constraint and uncertainty of wind power out, based on credibility theory and corrected energy function method. Methods: According to the corrected energy function, the transient stability constraint of the power grid is transferred to the penetration level problem of a wind farm. Wind speed forecast error is handled as a fuzzy variable to express the uncertainty of wind farm output. Then this paper builds a fuzzy chance-constrained model to calculate wind farm penetration level. To avoid inefficient fuzzy simulation, the model is simplified to a mixed integer linear programming model. Results: The results validate the proposed model and investigate the influence of grid-connection node, wind turbine characteristic, fuzzy reliability index, and transient stability index on wind farm penetration level. Conclusion: The result shows that the model proposed in this study can consider the uncertainty of wind power out and establish a quantitative transient stability constraint to determine the wind farm penetration level with a certain fuzzy confidence level.

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