Martha Roselia Contreras Valenzuela - Academia.edu (original) (raw)

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Papers by Martha Roselia Contreras Valenzuela

International Journal of Environmental Research and Public Health

In this work, we propose a fuzzy inference as a decision support system built in the MATLAB Fuzzy... more In this work, we propose a fuzzy inference as a decision support system built in the MATLAB Fuzzy Logic Designer for evaluating manual material handling risk conditions. The input variables for the fuzzy decision were: (1) the total time duration of the manual material handling in one shift of 450 min, with 3 h considered the maximal exposition time; (2) 25 kg as a maximal mass reference which should never be exceeded; (3) the repetitiveness of the manual material handling task through the shift considering as the maximal frequency of four lifts per min. Results of 135 earlier direct ergonomic evaluations made using the method proposed by the ISO 11228-1 were used as validator results, and called “expected results”. The experimentation intended to simulate an ergonomic evaluation in different boundary conditions of work and verify if the fuzzy interface could correctly replicate the results of the ergonomic evaluations. As validation, the list with the 135 expected results was compa...

Advances in Social and Organizational Factors, 2020

The Faculty of chemical sciences and engineering form the Morelos University in México, has devel... more The Faculty of chemical sciences and engineering form the Morelos University in México, has developed a tool called “QOC Matrix - the worker’s voice”. It is based on the logics of QOC (Questions, Options and Criterion), 6’s philosophy, ISO International Standers about Ergonomic guiding principles, National Institute for Occupational Safety and Health – USA publications, among others. Quality concepts like the Voice of Customer VOC (activity to meet the customer’s requirements), are used to obtain “The worker’s voice”, that will be used in the decision-making process about the design or redesign their workstation. The results obtained from the matrix have the objective to define if the workstations meet standards about cleanliness, organization and safety. Also, identify, the waste of “Talent” (underestimating as the creativity and intelligence of the workforce). All these having as a goal: “to create formal means to add value to the voice of the worker to express quality of working ...

Advances in Intelligent Systems and Computing, 2019

In order to determine ergonomic risk factors to be abated during an ergonomic intervention in a m... more In order to determine ergonomic risk factors to be abated during an ergonomic intervention in a metal washing process, two tools were implemented. The questionnaires from the QOC Matrix the workers’ voice was used to build a relationship diagram used to develop an ergonomic mapping. The Ergonomic risk map resulted identified the relationship, between workplace design and non-ergonomic content task. The method used to determine the risk factors was the follow: (a) define the non-ergonomic parameters inside work areas and task content using QOC results, (b) measure the results to categorise them in an ergonomic risk map, (c) using the ergonomic risk map a diagnosis was to carry out, (d) a redesign was proposed to abate non-ergonomic parameters. The activities developed for filling and discharging the washing machine included handling, lifting and carrying a plastic bucket of 40 kg above the shoulders, with an exerting force of 250 N in each lifting, for 120 times. It represented the main ergonomic problem. During the intervention, a new redesign for the working place was proposed; the improving phase incorporated two automatic sulfuric acid dilution system, two automatic mixers and an automatic production line for filling and discharging the washing machine. Consequently, workers change their character of mixers and loaders to the operators of an automatic control panel.

A method to determine drawbacks during REBA implementation inside aseptic areas was established e... more A method to determine drawbacks during REBA implementation inside aseptic areas was established employing opinions from twelve specialists. They assessed six aseptic areas. During the assessment, the specialists wore aseptic garments that difficult the observation of angles adopted by workers during job tasks, load demands and work cycles; information needed to achieve REBA. The method determines critical drawbacks through establish the procedure elements required to implement REBA, define ten main drawbacks, determine critical drawback items using a determination matrix, finally a procedure to implement REBA inside aseptic areas was proposed. It includes changes in the way of measure angles adopted by body segments and work task analysis.

Applications of Design for Manufacturing and Assembly, Jan 3, 2019

Ergonomics - New Developments for Global Change [Working Title], 2018