An adaptive BPSO algorithm for multi-skilled workers assignment problem in aircraft assembly lines

2015 ◽  
Vol 35 (4) ◽  
pp. 317-328 ◽  
Author(s):  
Bo Xin ◽  
Yuan Li ◽  
Jianfeng Yu ◽  
Jie Zhang
Keyword(s):  
Cycle Time ◽  
Assignment Problem ◽  
Stability And Convergence ◽  
Binary Particle Swarm Optimization ◽  
Assembly Lines ◽  
Skilled Workers ◽  
Time Model ◽  
Content Type ◽  
Aircraft Assembly ◽  
Human Cost

Purpose – The purpose of this paper is to investigate the multi-skilled workers assignment problem in complex assembly systems such as aircraft assembly lines. An adaptive binary particle swarm optimization (A-BPSO) algorithm is proposed, which is used to balance the workload of both assembly stations and processes and to minimize the human cost. Design/methodology/approach – Firstly, a cycle time model considering the cooperation of multi-skilled workers is constructed. This model provides a quantitative description of the relationship between the cycle time and multi-skilled workers by means of revising the standard learning curve with the “Partition-And-Accumulate” method. Then, to improve the accuracy and stability of the current heuristic algorithms, an A-BPSO algorithm that suits for the discrete optimization problems is proposed to assign multi-skilled workers to assembly stations and processes based on modified sigmoid limiting function. Findings – The proposed method has been successfully applied to a practical case, and the result justifies its advantage as well as adaptability to both theory and engineering application. Originality/value – A novel cycle time model considering cooperation of multi-skilled workers is constructed so that the calculation results of cycle time are more accurate and closer to reality. An A-BPSO algorithm is proposed to improve the stability and convergence in dealing with the problems with higher dimensional search space. This research can be used by the project managers and dispatchers on assembly field.

Study on Aircraft Assembly Line Balancing Problem Based on Mobile Workers

2016 ◽  
Author(s):  
Jie Zhang ◽  
Bo Xin ◽  
Pan Wang
Keyword(s):  
Assembly Line ◽  
Particle Swarm ◽  
Assembly Line Balancing ◽  
Line Balancing ◽  
Stability And Convergence ◽  
Particle Swarm Algorithm ◽  
Binary Particle Swarm Optimization ◽  
Assembly Lines ◽  
Aircraft Assembly ◽  
Assembly Line Balancing Problem

In order to improve the balance and load equilibrium of aircraft assembly lines, and to enhance the management of on-site resources, a Type-E balancing method was proposed based on the mobile operation of assembly personnel in the aircraft assembly line. This method was aimed to minimize the smoothness index of the overall assembly line and each assembly station, and also to minimize manpower costs. First, a model of personnel flow and an assembly line balancing model were constructed based on the characteristics of aircraft assembly lines. Next, an Accelerated Binary Particle Swarm Optimization (ABPSO) based on improved sig function was designed in order to improve the original stability and convergence of the standard binary particle swarm algorithm. Finally, the validity of the method was verified with a real fuselage assembly line and the results show the effectiveness.

A novel optimal method of robotic weld assembly line balancing problems with changeover times: a case study

2018 ◽  
Vol 38 (4) ◽  
pp. 376-386 ◽  
Author(s):  
Binghai Zhou ◽  
Qiong Wu
Keyword(s):  
Local Search ◽  
Cycle Time ◽  
Assembly Line ◽  
Research Work ◽  
Assembly Line Balancing ◽  
Line Balancing ◽  
Assembly Lines ◽  
Optimal Method ◽  
Content Type ◽  
Changeover Times

PurposeThe balancing of robotic weld assembly lines has a significant influence on achievable production efficiency. This paper aims to investigate the most suitable way to assign both assembly tasks and type of robots to every workstation, and present an optimal method of robotic weld assembly line balancing (ALB) problems with the additional concern of changeover times. An industrial case of a robotic weld assembly line problem is investigated with an objective of minimizing cycle time of workstations.Design/methodology/approachThis research proposes an optimal method for balancing robotic weld assembly lines. To solve the problem, a low bound of cycle time of workstations is built, and on account of the non-deterministic polynomial-time (NP)-hard nature of ALB problem (ALBP), a genetic algorithm (GA) with the mechanism of simulated annealing (SA), as well as self-adaption procedure, was proposed to overcome the inferior capability of GA in aspect of local search.FindingsTheory analysis and simulation experiments on an industrial case of a car body welding assembly line are conducted in this paper. Satisfactory results show that the performance of GA is enhanced owing to the mechanism of SA, and the proposed method can efficiently solve the real-world size case of robotic weld ALBPs with changeover times.Research limitations/implicationsThe additional consideration of tool changing has very realistic significance in manufacturing. Furthermore, this research work could be modified and applied to other ALBPs, such as worker ALBPs considering tool-changeover times.Originality/valueFor the first time in the robotic weld ALBPs, the fixtures’ (tools’) changeover times are considered. Furthermore, a mathematical model with an objective function of minimizing cycle time of workstations was developed. To solve the proposed problem, a GA with the mechanism of SA was put forth to overcome the inferior capability of GA in the aspect of local search.

Analysis of chaotic dynamics for aircraft assembly lines

2018 ◽  
Vol 38 (1) ◽  
pp. 20-25 ◽  
Author(s):  
Bo Xin ◽  
Yuan Li ◽  
Jian-feng Yu ◽  
Jie Zhang
Keyword(s):  
Nonlinear Dynamics ◽  
Experimental Study ◽  
Learning Curve ◽  
Production Rate ◽  
Learning Ability ◽  
Practical Case ◽  
Assembly Lines ◽  
Content Type ◽  
Time Dynamics ◽  
Aircraft Assembly

Purpose The purpose of this paper is to investigate the nonlinear dynamics of the aircraft assembly lines. An approach for modeling and analyzing the production rate of an aircraft assembly line is introduced using the chaos theory. Design/methodology/approach First, two key system variables including reliability and learning ability are considered to control the dynamics model. The discrete-time dynamics equation of the production rate is established as a function of the reliability and the learning rate. Then an improved Gauss-learning curve is proposed and applied to aircraft assembling condition. Finally, the bifurcation diagrams and the maximal Lyapunov exponents are used and applied to the experimental study to analyze the dynamic behavior under different combinations of parameters. Findings On the basis of the experimental study, it is shown that chaotic behavior really exists in the aircraft assembly lines. The reliability and the Gauss-learning curve can nonlinearly affect the production rate. Originality/value This paper applied nonlinear dynamics and chaotic theory to the production analyses of the aircraft assembly lines for the first time. The proposed model has been successfully applied to a practical case, and the result justifies its advantage as well as feasibility to both theory and engineering application.

Wheel design and motion analysis of a new heavy-duty AGV in aircraft assembly lines

2019 ◽  
Vol 40 (3) ◽  
pp. 387-397
Author(s):  
Junxia Jiang ◽  
Shenglin Zhang ◽  
Yuxiao He
Keyword(s):  
Dynamic Models ◽  
Kinematic Model ◽  
Aviation Industry ◽  
Heavy Duty ◽  
Assembly Lines ◽  
Heavy Load ◽  
Friction Forces ◽  
Content Type ◽  
Aircraft Assembly ◽  
Steering Mechanism

Purpose The flexible automatic transportation and manual assembly jobs for large aircraft components demand an automated guided vehicle (AGV) system with heavy-duty capacity and omnidirectional movability. This paper aims to propose a four driving-steering wheels-four supporting-steering wheels (4DSW-4SSW) layout plan to enhance the controllability and moving stability of AGV. Design/methodology/approach The anti-vibration structure of DS wheels and high-torque steering mechanism of SS wheels with tapered rolling bearings are rigorously designed to meet the functional requirements. Based on the specific wheel layout and vehicle dynamics, the rotational kinematic model as well as the straight and rotational dynamic models of AGV are established by the authors. To well verify the motion characteristics of wheels under heavy load in three motion states including straight motion, self-rotation and rotation around a certain point, the simulations in ADAMS and factory experiments have all been conducted. Findings Simulation results indicate that normal and friction forces of DS wheels and SS wheels are very stable except for some small oscillations, which are caused by non-center load distribution on AGV. Experimental results on driving speed of AGV have directly demonstrated that its positioning accuracy is enough for use in real aircraft assembly lines. Practical implications The designed AGV system has been applied to the final assembly line of a certain aircraft in Aviation Industry Corporation of China, Ltd, whose assembly efficiency and flexibility have been significantly improved. Originality/value A new layout plan of wheels for an omnidirectional heavy-duty AGV is proposed, which enhances the operating and moving capacity of AGV. A function of human-machine collaboration is also offered by the AGV for transporting large workpieces intelligently and economically in aerospace and other heavy industries.

The effect of vibratory conditioning on tensile strength and microstructure of 1018 mild steel

2020 ◽  
Vol 17 (6) ◽  
pp. 837-844 ◽  
Author(s):  
Venkata Suresh Bade ◽  
Srinivasa Rao P. ◽  
Govinda Rao P.
Keyword(s):  
Tensile Strength ◽  
Mild Steel ◽  
Fusion Zone ◽  
Dc Motor ◽  
Grain Structure ◽  
Internal Stresses ◽  
Skilled Workers ◽  
Mechanical Vibrations ◽  
Content Type ◽  
Weld Defects

Purpose The purpose of this paper is to investigate the prominence of mechanical excitations at the time of welding. In the past years, the process of welding technology has expanded its influence in manufacturing. The crucial drawback of conventional welding is prompted by internal stresses and distortions, which is the focal reason for weld defects. These weld defects can be diminished by the process called post-weld heat treatment (PWHT), which consumes more working hours and needs skilled workers. To replace these PWHT processes, mechanical vibrations are introduced during the process of welding to diminish these weld defects. Design/methodology/approach In the current research, the mechanical vibrations are transferred to weld-pool through vibro-motor and DC motor connected to the electrode. As per standards, the tensile test specimens were prepared for welding with different voltages of vibro-motor and DC motor respectively. The weld joints were tested for tensile strength and analyzed the microstructure at the fusion zone. Findings Melt-ability at fusion zone of 1018 mild steel was investigated by the single-stroke intense heat process of fusion welding. It is observed that the mechanical vibrations technique has a profound influence on the enhancement of the fusion zone characteristics and grain structure. The peak value of the tensile strength is observed at 100 s of vibration, 190 V of vibro-motor voltage and 18 V of electrode voltage. The tensile strength of the welded joints with vibrations is increased up to 22.64% when it is compared with conventional welding. The enhancement of the tensile strength of the weld bead was obtained because of the formation of fine grain structure. So, mechanical vibrations are identified as the most convenient method for improving the mild steel alloys weld quality. Originality/value A novel approach called mechanical vibrations during the process of welding is implemented for fusion zone refinement.

Effect of education on migration decisions in Ghana: a rural-urban perspective

2016 ◽  
Vol 43 (2) ◽  
pp. 336-356 ◽  
Author(s):  
Franklin Amuakwa-Mensah ◽  
Louis Boakye-Yiadom ◽  
William Baah-Boateng
Keyword(s):  
Educational Attainment ◽  
Rural Areas ◽  
Migration Decision ◽  
Skilled Workers ◽  
Mixed Effect ◽  
Content Type ◽  
Rural And Urban ◽  
Migration Decisions ◽  
Negative Effect ◽  
The Impact

Purpose – The purpose of this paper is to investigate the effect of education on migration decisions focusing on rural and urban in-migrants by comparing the 2005/2006 and 2012/2013 rounds of the Ghana Living Standards Survey (GLSS5 and GLSS6). After correcting for selectivity bias, the authors observed that anticipated welfare gain and socio-economic variables such as sector of employment, sex, experience, age, educational level and marital status significantly affect an individual’s migration decision. Design/methodology/approach – The authors made use of Sjaastad’s (1962) human capital framework as a basis for examining the impact of education on migration. The migration decision equation was based on the Heckman two stage procedure. Findings – While educational attainment is observed to have a positive effect on migration decision in the period 2005/2006, the authors find a negative effect of educational attainment on migration decision in the period 2012/2013. The effect of educational attainment on migration decision in 2005/2006 for urban in-migrant is higher than the effect for rural in-migrant, with its significance varying for the different stages of educational attainment. In absolute terms, whereas the effect of secondary educational attainment on migration decisions for urban in-migrant is higher than that of rural in-migrant, the reverse holds for higher educational attainment during the period 2012/2013. Social implications – Based on the mixed effect of education on migration decision as evident from the study, policies to enhance the educational system in Ghana should be complemented with job creations in the entire country. Moreover, special attention should be given to the rural sector in such a way that the jobs to be created in the sector do not require skilled workers. With quality education and job creation, the welfare of individuals living in urban and rural areas will be enhanced. Originality/value – In spite of the importance of education in migration decisions, there is scanty literature on the rural-urban dimension. To the best of the author’s knowledge there is no literature in the Ghanaian context which examines the rural and urban perspective of the impact of education on migration with a much recent data. Further, the author consider how the determinants of migration decision have changed over time focusing on rural and urban perspectives.

Construction time prediction model for public building projects

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shambel Kifle Alemu
Keyword(s):  
Regression Analysis ◽  
Addis Ababa ◽  
Linear Regression Analysis ◽  
Research Work ◽  
Time Cost ◽  
Construction Time ◽  
Time Model ◽  
Building Projects ◽  
Public Building ◽  
Content Type

PurposeThe aim of the study was to develop a practical construction time model for public building projects in Addis Ababa, Ethiopia.Design/methodology/approachThis research work used regression analysis and also exploratory scatter and residual plot techniques. Simple and multiple regressions were used for the investigation of the best fit time model. The analyses were carried out using IBM SPSS statistical software, version 20.FindingsThe result revealed that the Bromilow time-cost principle was moderately applicable. However, the cubic regression model (CUB) was found a better time-cost relationship. On the contrary, the study has shown a poor relationship between actual time and gross floor area. Furthermore, multiple linear regression analysis (MLR) consists of three statistically significant variables were found a better fit time model.Research limitations/implicationsThe study is limited to only six project scope factors. Further research is recommended to include more building projects of similar type and implications of other factors to improve the reliability of the models.Practical implicationsThe developed model was not intended as a replacement for detailed construction scheduling techniques. The resulting model is applicable for front-end predictions of construction duration.Originality/valueThe main parties involved in the building projects should apply the model for benchmarking a precise construction time during the early planning phase.

System dynamics modelling of fixed and dynamic Kanban controlled production systems: a supply chain perspective

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jagan Mohan Reddy K. ◽  
Neelakanteswara Rao A. ◽  
Krishnanand Lanka ◽  
PRC Gopal
Keyword(s):  
Supply Chain ◽  
System Dynamics ◽  
Cycle Time ◽  
Production System ◽  
Demand Uncertainty ◽  
Production Systems ◽  
Decision Variable ◽  
Content Type ◽  
Pull Production ◽  
Kanban System

Purpose Pull production systems have received much attention in the supply chain management environment. The number of Kanbans is a key decision variable in the pull production system as it affects the finished goods inventory (FGI) and backorders of the system. The purpose of this study is to compare the performance of the fixed and dynamic Kanban systems in terms of operational metrics (FGI and backorders) under the demand uncertainty. Design/methodology/approach In this paper, the system dynamics (SD) approach was used to model the performance of fixed and dynamic Kanban based production systems. SD approach has enabled the feedback mechanism and is an appropriate tool to incorporate the dynamic control during the simulation. Initially, a simple Kanban based production system was developed and then compared the performance of production systems with fixed and dynamic controlled Kanbans at the various demand scenarios. Findings From the present study, it is observed that the dynamic Kanban system has advantages over the fixed Kanban system and also observed that the variation in the backorders with respect to the demand uncertainty under the dynamic Kanban system is negligible. Research limitations/implications In a just-in-time production system, the number of Kanbans is a key decision variable. The number of Kanbans is mainly depended on the demand, cycle time, safety stock factor (SSF) and container size. However, this study considered only demand uncertainty to compare the fixed and dynamic Kanban systems. This paper further recommends researchers to consider other control variables which may influence the number of Kanbans such as cycle time, SSF and container size. Originality/value This study will be useful to decision-makers and production managers in the selection of the Kanban systems in uncertain demand applications.

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