Izabel Cristina Zattar

A multi-agent system for the integration of process planning and scheduling using operation-based time-extended negotiation protocols

This paper proposes the on-line adaptation of a process plan with alternatives, through the application of an operation-based time-extended negotiation protocol for decision-making for the real-time routing of job orders of parts composed of machining operations in a job-shop environment. The protocol is modified from the contract net protocol, which specifies the interaction between agents in a multi-agent system, in order to cater for the multiple tasks and many-to-many negotiations. A multi-agent system model was developed in order to make decisions based on a heterarchical structure, which allows grouping manufacturing parts composed of machining operations through the use of the new protocol. The grouping of the machining operations enables reduction of set-up times, resulting from the reduction of machines changes in flexible manufacturing environments. For each part, all feasible routings are considered as alternative process plans, provided the different manufacturing times in each machine are taken into account. This study evaluates four types of flexibility – operation flexibility, sequencing flexibility, processing flexibility, and machine flexibility – to identify which can provide better performance. The time-extended negotiation period allows the visualisation of all of the times involved in the manufacture of each part, including those times that are not considered in systems of this nature, such as the negotiation times among agents. Extensive experiments have been conducted in the system, and the performance measures, including makespan and flow time, are compared with those obtained by the search technique based on the co-evolutionary algorithm.

Integration between process planning and scheduling using feature-based time-extended negotiation protocols in a multiagent system

This paper describes the adaptation of process plan with alternatives, through an operation-based time extended negotiation protocol for decision-making about real-time routing of job orders of parts composed of machining operations in a job shop environment. The protocol is modified from the contract net protocol to cater for the multiple tasks and many-to-many negotiations. The grouping of the machining operations enables reduction of setup times, resulting from the reduction of machines changes. The time-extended negotiation period allows the visualisation of all the times involved in the manufacture of each part, including those times that are not considered in systems of this nature, such as the negotiation times among agents. Extensive experiments have been conducted, and the performance measures, including routings, makespan and flow time, are compared with those obtained by the following approaches: traditional hierarchical approach, a cooperative coevolutionary algorithm and the search technique based on a coevolutionary algorithm.

Prioritization of the Industrial Maintenance Activities According its Ergonomics Risks using Multi-criteria Analysis AHP

-Theactivities of industrial maintenance, which provide operational availability and reliability to the industrial production system, have at their core occupational risks to workers, particularly of ergonomic that influence the physical and organizational working conditions. The ergonomic factors related to industrial maintenance activities are poorly studied. Therefore, there is a need to identify the risks of ergonomic intrinsic to industrial maintenance activities and thus classify them regarding: the degree of treatment priority, their dangerousness concerning the physical conditions of the maintenance technician and their influence on the quality of maintenance services. This article demonstrates the identification of ergonomics risks presents during the performance of industrial maintenance activities, with the application of the AHP (Analytic Hierarchy Process) multi criteria analysis. This risk analysis directs to the criticality level determination, and to the impact that these risks may result regarding the quality of the industrial maintenance service provided.

O Impacto da Implementação da Manufatura Enxuta nos Indicadores Financeiros de uma Indústria Fordista: um estudo de caso

A Manufatura de Enxuta (ME) mostra-se superior quanto ao desempenho operacional comparado ao convencional modelo Fordista de producao e, consequentemente, no desempenho financeiro. Algumas pesquisas demonstram que a correlacao entre a ME e o desempenho financeiro e de fato positiva. Nesse contexto, uma questao pertinente e qual o impacto da implementacao da ME no desempenho financeiro de uma industria fordista. Mas, segundo Hoji (2009), a analise do desempenho financeiro, realizada atraves de indicadores financeiros, pode variar entre diferentes analistas. Portanto, o objetivo desse trabalho e verificar o impacto da implantacao da ME nos indicadores financeiros de uma industria Fordista atraves de um estudo de caso. Dessa forma, mantem-se a imparcialidade da pesquisa, deixando ao leitor a responsabilidade pela analise do desempenho financeiro. Para avaliacao do nivel de implementacao da ME, utilizou-se as normas SAE J4000 e J4001 que determinaram o nivel em 65,47%. Percebeu-se que, em pouco mais de um ano, implementacao da ME impactou positivamente indicadores financeiros relacionados a liquidez, atividade e lucratividade.

The Use of Expert Systems Associated to Agents for Routing Suggestions for Service Orders

In dynamic environments, a great obstacle for the integration between process planning and production scheduling is the lack of flexibility for the analysis of alternative resources during the allocation of the jobs on the shop floor. In this phase the process plan is treated as fixed, that is, scheduling does not consider all the possible manufacturing combinations. In order to solve this problem, it was proposed and developed a multiagent system that enables the use of process plans with on-line alternatives. After implementing the system, a large number of tests were carried out, resulting in a database with more than 12,000 simulations. By analyzing the results, it was observed that despite shorter makespan and flow times were attained, the standard deviation was high when comparing with other approaches found in the literature. As the problem is significantly complex, involving many parts, resources and alternative plans, an Expert Agent based on the Java Expert System Shell (JESS) language was implemented which, through the application of rules, filters the information in the database of simulations and provides the system with an adequate suggestion of the route to be executed.

Reducing the Standard Deviation When Integrating Process Planning and Production Scheduling Through the Use of Expert Systems in an Agent-based Environment

The main objective of this work is the reduction of the standard deviation generated through the routing of production orders in manufacturing resources in a job shop environment. This reduction is obtained through the suggestion of the best machining route for each job order in a simulation, based upon historic simulation data (base of facts) and a set of rules. In order to generate these routes, an expert agent and the expert system were developed. This agent is responsible for processing the information and controlling the rule engine, whereas the expert system code is responsible for the rules that will be chosen to be loaded and applied by the agent.

Integrating Manufacturing Process Planning with Scheduling via Operation-Based Time-Extended Negotiation Protocols

It is proposed in this paper the on-line adaptation of process plan with alternatives, through the application of an operation-based time-extended negotiation protocol for decision-making about real-time routing of job orders of parts composed of machining operations in a job-shop environment. The protocol is modified from the contract net protocol to cater for the multiple tasks and many-to-many negotiations. The grouping of the machining operations enables reduction of setup times, resulting from the reduction of machines changes. For each part, all feasible routings are considered as alternative process plans, provided the different manufacturing times in each machine are taken into account. The time-extended negotiation period allows the visualization of all of the times involved in the manufacture of each part, including those times that are not considered in systems of this nature, such as the negotiation times among agents. Extensive experiments have been conducted in the system, and the performance measures, including routings, makespan and flow time, are compared with those obtained by the search technique based on the co-evolutionary algorithm.