Metodologia para modelagem, validação e programação de controladores lógicos industriais usando statecharts básicos

Due of industrial informatics several attempts have been done to develop notations and semantics, which are used for classifying and describing different kind of system behavior, particularly in the modeling phase. Such attempts provide the infrastructure to resolve some real problems of engineering and construct practical systems that aim at, mainly, to increase the productivity, quality, and security of the process. Despite the many studies that have attempted to develop friendly methods for industrial controller programming, they are still programmed by conventional trial-and-error methods and, in practice, there is little written documentation on these systems. The ideal solution would be to use a computational environment that allows industrial engineers to implement the system using high-level language and that follows international standards. Accordingly, this work proposes a methodology for plant and control modelling of the discrete event systems that include sequential, parallel and timed operations, using a formalism based on Statecharts, denominated Basic Statechart (BSC). The methodology also permits automatic procedures to validate and implement these systems. To validate our methodology, we presented two case studies with typical examples of the manufacturing sector. The first example shows a sequential control for a tagged machine, which is used to illustrated dependences between the devices of the plant. In the second example, we discuss more than one strategy for controlling a manufacturing cell. The model with no control has 72 states (distinct configurations) and, the model with sequential control generated 20 different states, but they only act in 8 distinct configurations. The model with parallel control generated 210 different states, but these 210 configurations act only in 26 distinct configurations, therefore, one strategy control less restrictive than previous. Lastly, we presented one example for highlight the modular characteristic of our methodology, which it is very important to maintenance of applications. In this example, the sensors for identifying pieces in the plant were removed. So, changes in the control model are needed to transmit the information of the input buffer sensor to the others positions of the cell

O processo de urbanização turística em Natal: a perspectiva do residente

The objective of the study was to analyze and discuss the process of urbanization in the tourist city of Natal focusing on the actions of the resident agent as a producer of space tourism. The production and expertise in the areas of the city for the performance of tourism have led to the intensification of social problems of nature that comes to few expelling the residents of the beaches. The cut space of the study included the four beaches of Natal / RN, the praias do Centro, Via Costeira, Ponta Negra beach in the Redinha. For this, was conducted a case study, using the technique of questioning, with the application of one hundred and sixteen (116) questionnaires to residents, with age from thirty-five years, between the four of the City Administrative Regions. The results show that the process of urbanization has interferido tourism on the practices of the recreation of residents in the areas as tourism has shown a trend seen in the intensifying problems of social order, such as prostitution, insecurity, pollution of beaches, etc. The combination of these problems are reflected negatively on the tourist areas and are gradually removing the residents. Through this framework problematic, given to tourist areas in the city, the resident still has not positioned the way criticizes the defense of these, choosing not express or adopting a form of discrete event, such as the gradual exit of the areas and electing tourist beaches in other municipalities. The results are of great significance for the direction of a trip planning committed with the participation of the resident in the planning process. The study is to corroborate with the importance of the participation of the resident, before the trip planning, as it is a fundamental agent for the sustainability of space tourism

Equações discretas no ensino médio: modelos de dinâmicas populacionais

Pós-graduação em Matemática em Rede Nacional - IBILCE

A produção enxuta em um sistema de fabricação contínuo: aplicação da simulação discreta estocástica na indústria de condutores elétricos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Metodologia para utilização de algoritmos genéticos em modelos de simulação computacional em ambientes de manufatura

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modeling of active holonic control systems for intelligent buildings

Building facilities have become important infrastructures for modern productive plants dedicated to services. In this context, the control systems of intelligent buildings have evolved while their reliability has evidently improved. However, the occurrence of faults is inevitable in systems conceived, constructed and operated by humans. Thus, a practical alternative approach is found to be very useful to reduce the consequences of faults. Yet, only few publications address intelligent building modeling processes that take into consideration the occurrence of faults and how to manage their consequences. In the light of the foregoing, a procedure is proposed for the modeling of intelligent building control systems, considersing their functional specifications in normal operation and in the of the event of faults. The proposed procedure adopts the concepts of discrete event systems and holons, and explores Petri nets and their extensions so as to represent the structure and operation of control systems for intelligent buildings under normal and abnormal situations. (C) 2012 Elsevier B.V. All rights reserved.

Action crisis and cost–benefit thinking: A cognitive analysis of a goal-disengagement phase

The present research is based on the notion that disengagement from goals is not a discrete event but a process (Klinger, 1975). A critical phase in this process is when difficulties and setbacks in striving for a goal accumulate. This critical phase is termed here as an action crisis. Given the profound effects that people's thoughts have on their self-regulatory efficiency, it is essential to understand the cognitive correlates of an action crisis. In two experimental lab and two correlational field studies, the hypothesis that goal-related costs and benefits become cognitively highly accessible during an action crisis was tested and supported. Participants who were experiencing an action crisis in such diverse goal areas as intimate relationships, sports, and university studies, thought about goal-related costs and benefits more intensively and frequently in comparison to participants who were not in an action crisis. In an incidental learning task they recognized more of cost–benefit-items and less of implementation-items than the control group. Results are interpreted in terms of action phase specific mindsets (Gollwitzer, 1990, 2012).

The Struggle of Giving Up Personal Goals – Affective, Physiological, and Cognitive Consequences of an Action Crisis.

A critical phase in goal striving occurs when setbacks accumulate and goal disengagement becomes an issue. This critical phase is conceptualized as an action crisis and assumed to be characterized by an intrapsychic conflict in which the individual becomes torn between further goal pursuit and goal disengagement. Our theorizing converges with Klinger’s conceptualization of goal disengagement as a process, rather than a discrete event. Two longitudinal field studies tested and found support for the hypothesis that an action crisis not only compromises an individual’s psychological and physiological well-being, but also dampens the cognitive evaluation of the respective goal. In Study 3, marathon runners experiencing an action crisis in their goal of running marathons showed a stronger cortisol secretion and a lower performance in the race 2 weeks later. Results are interpreted in terms of action-phase–specific mindsets with a focus on self-regulatory processes in goal disengagement.

Agent-based modelling for cement hydration

The Agent-Based Modelling and simulation (ABM) is a rather new approach for studying complex systems withinteracting autonomous agents that has lately undergone great growth in various fields such as biology, physics, social science, economics and business. Efforts to model and simulate the highly complex cement hydration process have been made over the past 40 years, with the aim of predicting the performance of concrete and designing innovative and enhanced cementitious materials. The ABM presented here - based on previous work - focuses on the early stages of cement hydration by modelling the physical-chemical processes at the particle level. The model considers the cement hydration process as a time and 3D space system, involving multiple diffusing and reacting species of spherical particles. Chemical reactions are simulated by adaptively selecting discrete stochastic simulation for the appropriate reaction, whenever that is necessary. Interactions between particles are also considered. The model has been inspired by reported cellular automata?s approach which provides detailed predictions of cement microstructure at the expense of significant computational difficulty. The ABM approach herein seeks to bring about an optimal balance between accuracy and computational efficiency.

A tutorial on the cross-entropy method

The cross-entropy (CE) method is a new generic approach to combinatorial and multi-extremal optimization and rare event simulation. The purpose of this tutorial is to give a gentle introduction to the CE method. We present the CE methodology, the basic algorithm and its modifications, and discuss applications in combinatorial optimization and machine learning. combinatorial optimization

A formal methodology for the verification of concurrent systems

There is an increasing emphasis on the use of software to control safety critical plants for a wide area of applications. The importance of ensuring the correct operation of such potentially hazardous systems points to an emphasis on the verification of the system relative to a suitably secure specification. However, the process of verification is often made more complex by the concurrency and real-time considerations which are inherent in many applications. A response to this is the use of formal methods for the specification and verification of safety critical control systems. These provide a mathematical representation of a system which permits reasoning about its properties. This thesis investigates the use of the formal method Communicating Sequential Processes (CSP) for the verification of a safety critical control application. CSP is a discrete event based process algebra which has a compositional axiomatic semantics that supports verification by formal proof. The application is an industrial case study which concerns the concurrent control of a real-time high speed mechanism. It is seen from the case study that the axiomatic verification method employed is complex. It requires the user to have a relatively comprehensive understanding of the nature of the proof system and the application. By making a series of observations the thesis notes that CSP possesses the scope to support a more procedural approach to verification in the form of testing. This thesis investigates the technique of testing and proposes the method of Ideal Test Sets. By exploiting the underlying structure of the CSP semantic model it is shown that for certain processes and specifications the obligation of verification can be reduced to that of testing the specification over a finite subset of the behaviours of the process.

Determinization of timed Petri nets behaviors

International audience

Supervisory control of (max,+) automata: extensions towards applications

International audience

Diseño e implementación del kernel de xDEVS, versión distribuida

Para entender nuestro proyecto, debemos comprender DEVS. Dentro de los formalismos más populares de representación de sistemas de eventos discretos se encuentra DES. En la década de los 70, el matemático Bernard Zeigler propuso un formalismo general para la representación de dichos sistemas. Este formalismo denominado DEVS (Discrete EVent System Specification) es el formalismo más general para el tratamiento de DES. DEVS permite representar todos aquellos sistemas cuyo comportamiento pueda describirse mediante una secuencia de eventos discretos. Estos eventos se caracterizan por un tiempo base en el que solo un número de eventos finitos puede ocurrir. DEVS Modelado y Simulación tiene múltiples implementaciones en varios lenguajes de programación como por ejemplo en Java, C# o C++. Pero surge la necesidad de implementar una plataforma distribuida estable para proporcionar la mecánica de interoperabilidad e integrar modelos DEVS diversificados. En este proyecto, se nos dará como código base el core de xDEVS en java, aplicado de forma secuencial y paralelizada. Nuestro trabajo será implementar el core de manera distribuida de tal forma que se pueda dividir un sistema DEVS en diversas máquinas. Para esto hemos utilizado sockets de java para hacer la transmisión de datos lo más eficiente posible. En un principio deberemos especificar el número de máquinas que se conectarán al servidor. Una vez estas se hayan conectado se les enviará el trabajo específico que deberán simular. Cabe destacar que hay dos formas de dividir un sistema DEVS las cuales están implementadas en nuestro proyecto. La primera es dividirlo en módulos atómicos los cuales son subsistemas indivisibles en un sistema DEVS. Y la segunda es dividir las funciones de todos los subsistemas en grupos y repartirlos entre las máquinas. En resumen el funcionamiento de nuestro sistema distribuido será comenzar ejecutando el trabajo asignado al primer cliente, una vez finalizado actualizará la información del servidor y este mandara la orden al siguiente y así sucesivamente.

Impact of retransmissions in IEEE 802.11bd

The main goal of this thesis is to study the impact of retransmissions in the upcoming IEEE 802.11bd standard and to determine an algorithm which can, on a vehicle to vehicle basis, activate them or not depending on the channel state, using the channel busy rate (CBR) as the leading metric. The study was based on simulations performed with the WiLabV2Xsim, which is an open source discrete event simulator that can be used to simulate communication between vehicles under the rules of different protocols.