Multi-population genetic algorithm to solve the synchronized and integrated two-level lot sizing and scheduling problem

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Are the anticipatory trunk movements occurring during load-carrying activities protective or risky?

This study evaluated anteroposterior trunk movements and the time spent on activities of load-carrying to surfaces at different heights, among experienced and inexperienced individuals. Thirty-six healthy males (16 experienced and 20 inexperienced in load-carrying) had their trunk movements recorded by an electrogoniometer while transporting boxes (7 and 15 kg) to surfaces of variable heights (low, low intermediate, high intermediate and high). Longer time was spent on trunk flexion when carrying loads to low surfaces and on trunk extension when carrying to high surfaces (p<0.05). Differences in time spent on trunk flexion/extension were identified between loads, and between groups for the heavier load. There were no differences in flexion/extension amplitudes between groups or loads. Although unnecessary flexion/extension occurring prior to a task may increase the exposure of the trunk to risky movements, the amplitudes reported here were relatively small and seemed to have occurred to facilitate the final tasks.Relevance to industryLifting devices and technological assistance are increasingly available in industrial settings. However, distribution centers and delivery services represent new demands on workers and involve an expressive amount of manual handling and carrying activities. Thus, studies on carrying strategies are necessary as they can provide guidelines for safer activities. (C) 2007 Elsevier B.V. All rights reserved.

A Lagrangian relaxation approach to a coupled lot-sizing and cutting stock problem

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of reusable cardboard box designs: Biomechanical and perceptual aspects

Reusable cardboard boxes can be ergonomically designed for internal transportation of dry products in industrial settings. In this study we compared the effects of handling a regular commercial box and two cardboard prototypes on upper limb postures through the evaluation of movements, myoelectrical activity, perceived grip acceptability and capacity for reuse. The ergonomic designs provided a more acceptable grip, safer wrist and elbow movements and lower wrist extensors and biceps activity. Biomechanical disadvantages were observed only for one of the prototypes when handling to high surface. The prototypes were durable and suitable for extensive reuse (more than 2000 handlings) in internal industrial transportation. Despite being slightly more expensive than regular cardboard, the prototypes showed good cost-benefit considering their high durability. Relevance to industry: Cardboard boxes can be efficiently redesigned for allowing safer upper limb movements and lower muscle workload in manual materials handling. New designs can also be extensively reused for internal industrial transportation with good cost-benefit. © 2012 Elsevier B.V.

A priori reformulations for joint rolling-horizon scheduling of materials processing and lot-sizing problem

In many production processes, a key material is prepared and then transformed into different final products. The lot sizing decisions concern not only the production of final products, but also that of material preparation in order to take account of their sequence-dependent setup costs and times. The amount of research in recent years indicates the relevance of this problem in various industrial settings. In this paper, facility location reformulation and strengthening constraints are newly applied to a previous lot-sizing model in order to improve solution quality and computing time. Three alternative metaheuristics are used to fix the setup variables, resulting in much improved performance over previous research, especially regarding the use of the metaheuristics for larger instances. © 2013 Elsevier Ltd. All rights reserved.

Are cutout handles used when available in real occupational settings? Description of grips and upper extremities movements during industrial box handling

In order to achieve better postures and decrease musculoskeletal risks adequate design of hand/box couplings for manual materials handling (MMH) are still needed. No studies evaluating upper limb movement thorough direct measurements during box handling in workplace were identified in the literature. In this study we describe the types of grip and movements adopted by ten workers when handling redesigned boxes with cutout handles between different heights on industrial pallets. The new handles were used by 90% of the workers through different types of grip. Electrogoniometric measurements showed relatively safe forearm and wrist movements, although elbow inadequate range of movement was recorded. Despite the good acceptance of the cutout by workers, the new design requires extra internal space in the boxes reducing applications for this alternative of box.