Bucket Brigades Research Articles

An Enhanced Social Engineering Optimizer for Solving an Energy-Efficient Disassembly Line Balancing Problem Based on Bucket Brigades and Cloud Theory

A disassembly line is an industrialized and automated production line which should be scheduled with high production efficiency. Although many disassembly line balancing optimization studies are contributed recently, they increase or reduce the number of workstations to balance the disassembly line. From real-world managerial settings, an increase or decrease workstations, is too expensive and not realistic. The bucket brigades' disassembly line is self-balancing and self-organizing, which is not constrained by the workstation beat time and only needs to distribute workers on the line according to certain rules to achieve line balancing after a period of time. In this paper, a bucket brigades disassembly line balancing optimization method considering uncertainty is proposed, in which a cloud model is used to represent the uncertain disassembly time. The proposed model handles multiple objectives including smoothness, disassembly cost and disassembly energy consumption to be minimized. To solve this complex problem, this study innovates a new heuristic method based on the social engineering optimizer as an enhanced local search metaheuristic. Finally, a ball collector is used to verify the effectiveness of the proposed method and extensive analysis is done to compare the performance of proposed model with other recent algorithms.

Managing Stochastic Bucket Brigades on Discrete Work Stations

Bucket brigades are notably used to coordinate workers in production systems. We study a J‐station, I‐worker bucket brigade system. The time duration for each worker to serve a job at a station is exponentially distributed with a rate that depends on the station's expected work content and the worker's work speed. Our goal is to maximize the system's productivity or to minimize its inter‐completion time variability. We analytically derive the throughput and the coefficient of variation (CV) of the inter‐completion time. We study the system under two cases. (i) If the work speeds depend only on the workers, the throughput gap between the stochastic and the deterministic systems can be up to [Formula: see text] when the number of stations is small. Either maximizing the throughput or minimizing the CV of the inter‐completion time, the slowest‐to‐fastest worker sequence always outperforms the reverse sequence for the stochastic bucket brigade. To maximize the throughput, more work content should be assigned to the stations near the faster workers. In contrast, to minimize the CV of the inter‐completion time, more work content should be allocated to the stations near the slower workers. (ii) If the work speeds depend on the workers and the stations such that the workers may not dominate each other at every station, the asymptotic throughput can be expressed as a function of the average work speeds and the asymptotic expected blocked times of the workers, and can be interpreted as the sum of the effective production rates of all the workers.

Revised Worker Collaboration Models for Cellular Bucket Brigades with Discrete Workstations

Revised Worker Collaboration Models for Cellular Bucket Brigades with Discrete Workstations

Workforce reconfiguration strategies in manufacturing systems: a state of the art

ABSTRACT This paper provides a literature review and an analysis of the studies related to workforce reconfiguration strategies as a part of workforce planning for various production environments. The survey demonstrates that these strategies play a crucial role in the resilience and flexibility of manufacturing systems since they help industrial companies to quickly adapt to frequent changes in demand both in terms of volume and product mix. Five strategies are considered: the use of utility, temporary, walking, cross-trained workers, and bucket brigades. They are analysed in the context of mixed and multi-model manual assembly lines, dedicated, cellular, flexible, and reconfigurable manufacturing systems. The review shows that most of the researches on these reconfiguration strategies focus on multi- or mixed-model assembly lines. At the same time, few studies consider workers team reconfiguration in flexible and reconfigurable manufacturing systems. Finally, this paper reveals several promising research directions in workforce reconfiguration planning, namely, the use of both machine and workforce reconfigurations, consideration of the ergonomic aspects, the combination of multiple workforce reconfiguration strategies, the study of workforce reconfiguration in human-robot collaborative systems, and the use of new technologies in human-machine industrial environments.

A New Self-Balancing Assembly Line Based on Collaborative Ant Behavior

In most mass-production assembly lines, workers perform a set of tasks repetitively predefined by assembly line balancing techniques. The static task assignment often leads to low productivity when the assembly system faces disruptions or uncertainties such as machine breakdown and uneven worker capabilities. The idea of bucket brigades (BB) has been introduced to address the static assignment problems where cooperative behavior of ants is applied to flow line control. This paper examines possible efficiency losses associated with the existing BB-based assembly cell and presents an improved version for assembly cells under uncertain environments. The new system attempts to enhance productivity by assigning assembly tasks to workers dynamically and possibly adding buffers for decoupling consecutive workers. The proposed assembly system is evaluated through simulation experiments under various manufacturing environments. The experimental results show that the new system provides higher productivity than the naïve BB-based assembly cell as well as traditional assembly cells, especially for uncertain assembly environments.

Determination of water application rates required for communities to suppress post‐flashover informal settlement fires based on numerical modelling and experimental tests

SummaryFires originating in informal settlements (ie, slums, ghettos, shantytowns, squatter camps) spread rapidly, due to the presence of densely packed, highly combustible dwellings, thereby making these communities inherently susceptible to large conflagrations. By the time, the fire brigades are notified and can get to the scene of the fire, the resulting conflagrations can be large. Thus, it is necessary to equip communities with the ability to combat smaller fires, although it is acknowledged that this is not ideal. Previous full‐scale testing and firefighter experience have shown that water application through ‘bucket brigades’ can be very effective at suppressing fires. In this article, a model is developed for approximately quantifying the amount of water, and discharge rate, that is, required for communities to suppress fires of various sizes using bucket brigades. This is done to answer the question: based on the water supply infrastructure in an area could a community put out post‐flashover fires of certain sizes? If this is not feasible, it would highlight the importance of communities having readily available pre‐filled water buckets at homes. The model presented is developed in fire dynamics simulator and is calibrated based on full‐scale experiments utilizing the bucket brigade technique. It is shown that standpipe discharge rates of 23 to 40 lpm are suitable for fire sizes of around 3.85 MW, based on a dwelling size of 2.4 x 3.6 x 2.4 m. This means that in communities with a single stand‐pipe (water supply point) with flow rates less than 23 lpm, that fires greater than 3.85 MW (as produced by a home of 2.4 x 3.6 m with a timber fuel load of 25 kg/m2) cannot be suppressed in time without resulting in substantial fire spread to adjacent dwellings.

The contribution of road‐based citizen science to the conservation of pond‐breeding amphibians

AbstractRoadside amphibian citizen science (CS) programmes bring together volunteers focused on collecting scientific data while working to mitigate population declines by reducing road mortality of pond‐breeding amphibians. Despite the international popularity of these movement‐based, roadside conservation efforts (i.e. “big nights,” “bucket brigades” and “toad patrols”), direct benefits to conservation have rarely been quantified or evaluated.As a case study, we used a population simulation approach to evaluate how volunteer intensity, frequency and distribution influence three conservation outcomes (minimum population size, population growth rate and years to extinction) of the spotted salamander (Ambystoma maculatum), often a focal pond‐breeding amphibian of CS and conservation programmes in the United States.Sensitivity analysis supported the expectation that spotted salamander populations were primarily recruitment‐driven. Thus, conservation outcomes were highest when volunteers focused on metamorph outmigration as opposed to adult in‐migration—contrary to the typical timing of such volunteer events.Almost every volunteer strategy resulted in increased conservation outcomes compared to a no‐volunteer strategy. Specifically, volunteer frequency during metamorph migration increased outcomes more than the same increases in volunteer effort during adult migration. Small population sizes resulted in a negligible effect of volunteer intensity. Volunteers during the first adult in‐migration had a relatively small effect compared to most other strategies.Synthesis and applications. Although citizen science (CS)‐focused conservation actions could directly benefit declining populations, additional conservation measures are needed to halt or reverse local amphibian declines. This study demonstrates a need to evaluate the effectiveness of focusing CS mitigation efforts on the metamorph stage, as opposed to the adult stage. This may be challenging, compared to other management actions such as road‐crossing infrastructure. Current amphibian CS programmes will be challenged to balance implementing evidence‐based conservation measures on the most limiting life stage, while retaining social and community benefits for volunteers.

Cellular Bucket Brigades with Worker Collaboration on U-Lines with Discrete Workstations

Cellular bucket brigades (CBB) are a new design of bucket brigade that can reduce unproductive travel by workers on U-shaped production lines. With CBB, each worker works on one side of an aisle when proceeding in one direction, and on the other side when proceeding in the reverse direction; workers then exchange their work when they meet each other. The throughput of CBB may be reduced due to blocking and/or halting at discrete workstations. A method for countering these blocking/halting conditions is proposed here; it utilizes worker collaboration such that a maximum of two workers can collaborate on the same task. The collaboration velocity is proportional to the sum of individual worker velocities, and is influenced by the worker collaboration coefficient. The existing model and its assumptions are utilized here to compare the performance of CBB against worker collaboration on a three-station, twoworker U-line for which the difference collaboration coefficient and work content of the product at each station are deterministic. The results show that worker collaboration almost always outperforms CBB, except for certain cases in which each worker has a different velocity at different stations.

Integration of Bucket Brigades and Worker Collaboration on a Production Line with Discrete Workstations

Integration of Bucket Brigades and Worker Collaboration on a Production Line with Discrete Workstations

Handling interference effects on foraging with bucket brigades

Many kinds of bio-inspired tasks have been tested with swarm robotics and task partitioning is one of the challenging subjects. In nature, it is well known that some colonies of social insects such as honeybees, termites, and ants use task partitioning strategies for their survival. In this paper, we demonstrate an effect of the task partitioning strategy called bucket brigade, which uses the direct transfer of materials or food between a pair of workers. We propose a task partitioning strategy based on the moving speeds of agents for the foraging task. We test various environmental conditions and compare the performance between task partitioning groups and non-partitioning groups. The experimental results show that task partitioning may not always be the best solution for foraging performance. However, when there exists a transfer bottleneck at a central location such as the entrance of the nest, task partitioning can be an effective strategy for reducing the traffic jam and improving the overall foraging performance of a group. The bucket brigade sequenced from the slowest agents (near the food source) to the fastest agents (near the nest) can particularly improve performance significantly in the region with traffic congestion near the nest. Generally, many social insect colonies consist of a number of members, and the entrances of colony nests always suffer from heavy traffic congestion. Our experimental results support the hypothesis that several social insects use one of the task partitioning strategies based on bucket brigades in their foraging tasks.

Performance of Cellular Bucket Brigades with Hand‐Off Times

A cellular bucket brigade is a way to coordinate workers along an aisle with work content on both sides. Each worker in a cellular bucket brigade works on one side of the aisle when he proceeds in one direction, and he works on the other side when he proceeds in the reverse direction. Although the cellular bucket brigade eliminates the unproductive walk‐back, it requires more hand‐offs to assemble a product than a traditional (serial) bucket brigade. These hand‐offs may waste significant production capacity as each of them requires an exchange of work, which can be complicated and time‐consuming in practice. This motivates us to investigate the impact of hand‐off times on the cellular bucket brigade's performance. We identify sufficient conditions to ensure no workers are idle in the long run and for the system to self‐balance in a model with hand‐off times. Our results suggest that even with significant hand‐off times, the cellular bucket brigade can remain substantially (about 50%) more productive than the traditional bucket brigade especially if the team size is small and the workers’ work velocities are close to their walk velocity.

Design of an enhanced multi-aisle order-picking system considering storage assignments and routing heuristics

Abstract Order-picking is the activity to retrieve items from the shelves to fulfill customers' orders. Order-picking is one of the most costly operations in warehousing accounting for 50–75% of total operating costs. This paper presents a novel model that is motivated by the normative order-picking algorithm known as “bucket brigades” to address multiple aisles in warehouses where workers have finite walk-back velocities and are allowed to pass successors. In order-picking operations, the majority of the previous research works have applied bucket brigades over a single-line (serial) system. The contributions of this research work are as follows. (1) A summary of an updated literature review of bucket brigades using a state-of-the-art-matrix. (2) A novel multi-aisle order picking model motivated by the normative single-aisle bucket brigade, which represents a more comprehensive and realistic scenario in order fulfillment warehouses. (3) A comparison between the single-line and multi-aisle models in order to analyze the difference in performance in terms of average system utilization, order cycle time and throughput. (4) A sensitivity analysis of different parameters and scenarios in order to identify the best routing heuristic, storage assignment and order type that maximizes utilization, minimizes cycle time and maximizes throughput in multi-aisle order picking systems. The results of the simulation studies are reported and analyzed. The proposed model is flexible and easily scalable to include other real-life warehousing considerations.

‘We Are the Monitors Now’

Residents of pollution hotspots often take on projects in ‘citizen science’, or popularepidemiology, in an effort to marshal the data that can prove their experience of the pollution to the relevant authorities. Sometimes these tactics, such as pollution logs or bucket brigades, take advantage of residents’ spatially ordered and finely honed experiential and sensory knowledge of the places they inhabit. But putting that knowledge into conversation with law requires them to mobilize a new, ‘foreign’ set of tools, primarily oriented to the observation, measurement and sampling of pollution according to conventional scientific standards. Here, I employ qualitative empirical methods in two case studies of communities ‘downwind’ of Canada’s contested tar sands region to demonstrate that the knowledge that is crucial to these citizen science strategies is not only local, situated and experiential in origin but also collectively generated and held. I draw on the notion of transcorporeality, emanating from feminist theory of the body, to demonstrate that the knowledge offered to law through these efforts often represents a fluid merger of experiential and conventional ways of knowing, posing a productive challenge to the strictly positive notions of science and evidence dominant in legal proceedings.

Characteristics analysis of cellular bucket brigades with different constraints

Cellular bucket brigade (CBB) is known as the self-organizing and self-balancing production system, but in different constraints, its self-organizing feature also presents different characteristics. According to constraints of station, this article divides the CBB system into three types: (1) CBB-1, no obvious location, in which an arbitrary position can be an exchange of work; (2) CBB-2, location limited, in which any place can be a transition; and (3) CBB-3, location limited, which cannot be exchanged within the stations. Then, the corresponding mathematical models are established to analyze the performance of the CBBs. At last, numerical simulation provides the following results: Both CBB-1 and CBB-2 have only one balance point and good convergence from any states to balance point, while the balance point of CBB-3 is of uncertainty.

Order batching in a bucket brigade order picking system considering picker blocking

Bucket brigade order picking improves operational productivity by balancing workloads among pickers with a minimal level of managerial planning and oversight. However, due to variability and uncertainty of the pick locations within a particular order or batch, pickers can encounter blocking delays and thus lose productivity. This study formulates a model to quantify blocking delays and develops a control model to reduce blocking in bucket brigade order picking systems. The Indexed Batching Model for Bucket brigades (IBMB) has indexed batching constraints for generating batch alternatives, bucket brigade picker blocking constraints for quantifying blocking delay, and release-time updating constraints for progressively connecting the batching results with blocking quantification. The IBMB minimizes total retrieval time and improves picker utilization from 2 to 9 % across diverse and practical order picking situations while maintaining the static Work-In-Process. We note that modeling the separation of retrieved batches into orders still remains a challenge.

Warehouse Order-Picking Process. Review

This article describes basic warehousing activities, namely: movement, information storage and transfer, as well as connections between typical warehouse operations (reception, transfer, assigning storage position and put-away, order-picking, hoarding and sorting, cross-docking, shipping). It presents a classification of the warehouse order-picking systems in terms of manual labor on offer as well as external (marketing channels, consumer’s demand structure, supplier’s replenishment structure and inventory level, total production demand, economic situation) and internal (mechanization level, information accessibility, warehouse dimensionality, method of dispatch for shipping, zoning, batching, storage assignment method, routing method) factors affecting the designing systems complexity. Basic optimization considerations are described. There is a literature review on the following sub-problems of planning and control of orderpicking processes. A layout design problem has been taken in account at two levels — external (facility layout problem) and internal (aisle configuration problem). For a problem of distributing goods or stock keeping units the following methods are emphasized: random, nearest open storage position, and dedicated (COI-based, frequency-based) distribution, as well as class-based and familygrouped (complimentary- and contact-based) one. Batching problem can be solved by two main methods, i.e. proximity order batching (seed and saving algorithms) and time-window order batching. There are two strategies for a zoning problem: progressive and synchronized, and also a special case of zoning — bucket brigades method. Hoarding/sorting problem is briefly reviewed. Order-picking routing problem will be thoroughly described in the next article of the cycle “Warehouse order-picking process”.

Cellular Bucket Brigades on U‐Lines with Discrete Work Stations

It is challenging to maximize and maintain productivity of a U‐line with discrete stations under the impact of variability. This is because maximizing productivity requires assigning workers to suitable tasks and maintaining productivity requires sufficient flexibility in task assignment to absorb the impact of variability. To achieve this goal, we propose an operating protocol to coordinate workers on the U‐line. Under the protocol the system can be configured such that its productivity is maximized. Workers are allowed to dynamically share work so that the system can effectively absorb the impact of variability. Analysis based on a deterministic model shows that the system always converges to a fixed point or a period‐2 orbit. We identify a sufficient condition for the system to converge to the fixed point. Increasing the number of stations improves productivity only under certain circumstances. The improvement is most significant when the number of stations in each stage increases from one to two, but further dividing the U‐line into more stations has diminishing return. Simulations based on random work velocities suggest that our approach significantly outperforms an optimized, static work allocation policy if variability in velocity is large.

Convergence in Bucket Brigades in a Tree-Shaped Picking System

Previous works on the dynamics of bucket brigades have mainly focused on linear production systems or tree-shaped assembly systems with insignificant walk-back time, but this assumption is invalid for most city picking systems. We propose a two-truck bucket brigade tree-shaped picking system when truck walk-back time is significant and analyze the dynamics of the system in each region of the parameter space, showing that relatively complex picking systems can enjoy the benefit of self-balance with minimal managerial intervention and provide insights and operating principles for the implementation and management of the bucket brigade picking system.

Bucket Brigades to Increase Productivity in a Luxury Assembly Line

One of the most challenging issues in manual assembly lines is to achieve the best balance of workloads. There are many analytic approaches to solve this problem, but they are often neglected, since they are time-consuming and require high level engineering skills. Fashion bags packaging lines must comply with a number of different products with low production volumes, while the organization of the line is often under the mere responsibility of the foreman, who balances workloads in an empirical way. The aim of this work is to evaluate the effectiveness of the arrangement of bucket brigades (BBs) for an assembly line of luxury handbags. To do this, it was decided to perform a testing activity in a company producing fashion handbags in order to compare the self-made design with the BBs and with a simple assembly line balancing problem algorithm. The originality of this research lies in the fact that there are no studies in the literature on BBs applied to the packaging of highly variable small batches. The results were excellent, showing the advantages of BBs in terms of flexibility, the reduction of work in the process and the ability to handle small anomalies.

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