2007
Authors
Tisserant, E; Bessard, L; de Sousa, M;
Publication
2007 5TH IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL INFORMATICS, VOLS 1-3
Abstract
The IEC 61131-3 standard defines a common framework for programming PLCs (Programmable Logic Controllers), which includes the complete definition of four programming languages and a state machine definition language. Industrial PLC vendors are slowly offering support for this standard, however small inconsistencies remain between their implementations, transferring programs between vendors is almost impossible due to different rile formats, and licenses are generally too expensive to allow students do install these commercial solutions on their own computers. To this end, the authors have developed an Integrated Development Environment (IDE) for the IEC 61131-3 framework, which is being offered to the general public under the GNU Public License (GPL). The IDE consists of a Graphical User Interface (GUI) and a backend compiler. Using the GUI the user may develop programs in any of the four programming languages, as well as the state machine definition language. The backend compiler is used to convert these programs into equivalent C++ programs which may later be compiled and executed on various platforms.
2007
Authors
De Sousa, M; Santos, AA;
Publication
IEEE International Conference on Industrial Informatics (INDIN)
Abstract
The IEC-61499 standard defines a framework in which distributed control applications may be developed, and how these are interpreted and executed. With the distributed nature of the control applications, many new issues also need to be taken into account. Most of these arise due to the new error model and failure modes of the distributed hardware on which the distributed application is being executed. On the other hand, the distributed nature of the hardware also allows new capabilities to be explored, such as improved reliability through masking of faults. Fault tolerance is usually achieved by the use of replication. Replication at the software level allows for much smaller granularity, but all replicas must be kept synchronised in order to produce the same output data and events. To achieve replica determinism all replicas must process the same set of inputs in the same order, and the outputs of the replicas must somehow be consolidated. The IEC 61499 framework however does not explicitly handle the replication of software components. In this paper we propose a replication model for IEC-61499 applications, and discuss which mechanisms and protocols may be used for their support. In short, replica determinism is achieved through the use of distributed synchronised clocks, atomic multicast protocols, as well as timed messages. ©2007 IEEE.
2007
Authors
Ruiz, AM; Sousa, JJ; Hanssen, RF; Perski, Z; Bastos, L; Gil, AJ;
Publication
European Space Agency, (Special Publication) ESA SP
Abstract
Recently, two CAT-1 projects have been initiated related to Granada Basin area (Betic Cordillera, Southern Spain), aimed at the detection of deformation in the region applying time series InSAR methodology. Due to the outstanding availability of ERS-1/2 and Envisat acquisitions, a time span of more than 12 years is covered and time series can be produced, enabling us to assess the feasibility of monitoring deformation with millimetre precision. The ultimate goal of these projects is the quantification of displacements and determination of their mean directions, relating them to dynamic changes and stress accumulation in order to identify potential seismic hazard locations. For the moment, not all available scenes have been received, so a preliminary data processing has been carried out at the Padul fault area. In this paper, we present a status report of both projects.
2007
Authors
Fonseca Ferreira, NM; Tenreiro Machado, JA; Tar, JK;
Publication
JACIII
Abstract
This paper analyzes the dynamic performance of two cooperative robot manipulators. It is studied the implementation of fractional-order algorithms in the position/force control of two cooperating robotic manipulators holding an object. The simulations reveal that fractional algorithms lead to performances superior to classical integer-order controllers. © 2008 IEEE.
2007
Authors
Sabugosa Madeira, B; Abreu, I; Ribeiro, H; Gomes, A; Cunha, M;
Publication
APIDOLOGIE
Abstract
2007
Authors
Ribeiro, H; Cunha, M; Abreu, I;
Publication
AEROBIOLOGIA
Abstract
The aim of this study was to improve the accuracy of aeropalynological models to forecast yields in areas with heterogeneous characteristics by applying principal component analysis to integrate the airborne pollen sampled from more than one trap. The sampling was performed during the past seven years (1998-2004) in the main northeast olive regions of Portugal. Annual crop production was forecasted on the basis of airborne pollen concentration measured at flowering, comparing the performance of three different independent variables: total airborne pollen concentration sampled in each trap and a derived variable that was determined by principal component analysis of the total airborne pollen concentration sampled. The best predictive results were obtained using a logarithmic relationship with airborne pollen concentration principal component scores describing about 97% of olive fruit production variability over the last seven years. The use of this technique improved the ability of pollen to explain the production interannual variations by about 13%. The comparison between actual reported and the adjusted production showed an average spread deviation of 5%.
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