-
[show abstract]
[hide abstract]
ABSTRACT: In the context of the Packet Switching Networks, the main need is to optimize the paths connecting the source and the destination. In this paper the authors deal with the problem of routing by means of a neural approach. This is based on the assumption that each switching node is made up by a Hopfield network which is capable to determine the optimal path which connects the local node with a generic node in the packet switching network. On this basis, the suitable output link on which each incoming packet must be routed is chosen.
01/2006: pages 583-592;
-
S. Cavalieri
[show abstract]
[hide abstract]
ABSTRACT: Literature presents many approaches for location detection of a mobile user using IEEE 802.11b wireless communication standard; generally localisation is limited to indoor scenarios, where GPS cannot be used, and is based on pattern matching algorithm. The paper aims to reach two different goals. The first is the proposal of the use of IEEE 802.11b standard for outdoor location detection; this choice is mainly justified by the large availability of communication cards at very low costs and by the limits of GPS, which may introduce not negligible errors in location detection. The second aim of the paper is the proposal of a new approach for outdoor wireless localisation, aimed to reduce the complexity featuring by the well-known localisation approaches based on pattern matching algorithm.
Emerging Technologies and Factory Automation, 2005. ETFA 2005. 10th IEEE Conference on; 10/2005
-
S. Cavalieri
[show abstract]
[hide abstract]
ABSTRACT: IEEE 802.11b standard, also known as Wi-Fi, is one of the most used wireless communication systems. Location of a mobile user by IEEE 802.11b has a lot of advantages, mainly due to the use of the same hardware/software needed for the communication. Literature presents many approaches for localisation based on Wi-Fi; among them there is the pattern matching algorithm. The paper aims to present outdoor use of this algorithm, due to the lack in literature of relevant examples. Further, the paper will present a new approach for wireless localisation, aimed to reduce the complexity of the pattern matching algorithm.
Industrial Informatics, 2005. INDIN '05. 2005 3rd IEEE International Conference on; 09/2005
-
S. Cavalieri
[show abstract]
[hide abstract]
ABSTRACT: This paper deals with the problem of information flow scheduling in a communication system based on CAN ISO IS-11898 physical medium access mechanism. It mainly features a bus access arbitration protocol based on a priority assigned to each message to be transmitted; if two or more messages are transmitted at the same time by different communication nodes, only the message with the highest priority continues to be transmitted, the other being stopped. In real-time applications, messages are relevant to process variables which must be transmitted within strict time constraints; according to the CAN ISO IS-11898 bus arbitration protocol, respect of real-time constraints depends on the priority assigned to each variable. The aim of the paper is to propose a procedure for dynamic assignment of priorities to variables to be transmitted, in such a way the relevant real-time requirements are fulfilled. Although many other approaches can be found in literature, the proposal is original as it is based on standard full CAN communication stacks.
IEEE Transactions on Industrial Informatics 06/2005; · 2.99 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: One of the main limits of the current technology for the management of large plant (like those concerning water, gas, power distribution) is the lack of vertical and/or horizontal integration of information. Vertical integration refers to the need to integrate systems implemented at different administrative level of an organisation. Horizontal integration improves the concept of integration, allowing the user of large plant to execute very complex transformations on data coming from several real applications, also of different types. The Mobicossum EU project, IST 1999-57455, is a CRAFT project, aimed to define a middleware between (mobile) user and lower level applications, based on vertical and horizontal integrations of information.
Industrial Technology, 2004. IEEE ICIT '04. 2004 IEEE International Conference on; 01/2005
-
[show abstract]
[hide abstract]
ABSTRACT: The paper aims to point out the main results obtained during the European project Mobicossum IST 1999-57455, still running. This project aims to realise a horizontal and vertical integration of SCADA/GIS and DSS applications. Definition of horizontal and vertical integration would be clearly pointed out in the paper highlighting its relevant advantages. The paper focus only on some the results achieved at the date of the writing of the paper. These results able to point out the advantages coming from their adoption and their further improvement, for users of the main applications used in large plants (such that of water and gas distribution).
Industrial Electronics, 2004 IEEE International Symposium on; 06/2004
-
S. Cavalieri
[show abstract]
[hide abstract]
ABSTRACT: Fieldbuses are communication systems used in industrial environments to convey information on which process control is based. Due to the nature of this information, the presence of fault tolerance mechanisms is required. This letter proposes a fault recovery protocol compliant with Interbus-S, one of the most widely used fieldbuses.
IEEE Transactions on Industrial Electronics 09/2003; · 5.16 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The paper deals with the scheduling of periodic information flow in a FieldBus environment. The scheduling problem is defined from an analytical point of view, giving a brief survey of the most well-known solutions. One of these is called multicycle polling scheduling, which is based on the hypothesis that all the production periods of the periodic processes to be scheduled are harmonic. Although in some process control or manufacturing scenarios, this hypothesis may be acceptable, there are many real industrial processes to which it cannot be applied. The aim of the paper is to make a contribution towards solving the scheduling problem. It essentially concerns extension of the theory on which multicycle polling scheduling is based to a much more realistic and general scenario, where the periods of all the processes to be scheduled have arbitrary values. The authors present a new formulation of multicycle polling scheduling, called extended multicycle polling scheduling, and demonstrate that it comprises the scenario currently considered in the literature. Two algorithmic solutions for extended multicycle polling scheduling are then proposed, giving a computational complexity analysis which will highlight the capability of the algorithmic scheduling solutions to be performed on-line. The paper concludes by comparing the multicycle polling scheduling approach known in literature and the one presented in the paper. Comparison is performed by evaluating the use of available bandwidth to serve both periodic and asynchronous traffic in the two approaches.
Real-Time Systems 08/2003; 25(2):157-185. · 0.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The paper deals with the scheduling of periodic information flow in single and multi FieldBus environments. The problem is defined from an analytical point of view, giving a brief survey of the most well-known solutions. Then the authors make their contribution to the problem. More specifically, a modification to a well-known single FieldBus scheduling solution is introduced, in order to make its applicability wider. As far as multi FieldBus scheduling is concerned, a genetic approach is presented.
03/2003;
-
S. Cavalieri
[show abstract]
[hide abstract]
ABSTRACT: Object oriented software design is getting more and more common in the field of industrial control. In particular, Java seems extremely versatile for the development of distributed control applications. One of the main requirements of control application is a deterministic execution of the tasks, which generally feature real-time constraints. When Java language has been conceived, a little weight to the real-time requirements of applications has been given. In the last few years the limits to the use of Java for real-time applications has led to the definition of Java Real-Time platform specifications. Real-time capability of a Java virtual machine (VM) depends on a very large number of elements, among which the task scheduling algorithm, the memory management, the garbage collector algorithm and its execution policy. Knowledge of how each single internal mechanism of a Java VM influence its performance is very important to improve its real-time behaviour. This paper must be considered as a first step toward this direction, as its aim is to try to understand how real-time performance of a Java VM may be influenced by each its single component.
IECON 02 [Industrial Electronics Society, IEEE 2002 28th Annual Conference of the]; 12/2002
-
[show abstract]
[hide abstract]
ABSTRACT: Fieldbus systems were developed in order to overcome the very huge number of limits featured by the point-to-point links in distributed process control systems, by adopting a shared communication medium. This paper provides an analysis of the real-time behaviour of the multi-master Profibus DP network. The analysis presented represents a step toward the capability to perform a more accurate evaluation of the performance of the Profibus network.
Intelligent Control, 2002. Proceedings of the 2002 IEEE International Symposium on; 02/2002
-
[show abstract]
[hide abstract]
ABSTRACT: Profibus DP networks are often used as the communication infrastructure for supporting distributed computer-controlled applications, which, very often, impose strict real-time requirements. The aim of this paper is to present a novel methodology for evaluating the worst-case message response time in Profibus DP networks where high and low priority information flows coexist.
Factory Communication Systems, 2002. 4th IEEE International Workshop on; 02/2002
-
[show abstract]
[hide abstract]
ABSTRACT: The paper deals with the attempt to guarantee real-time services over TCP/IP. The scenario taken into consideration is a distributed computing environment where producer and consumer processes feature real time constraints and the communication between them is realised by a LAN based on TCP/IP protocols. The lack of determinism in the communication of this suite of protocols is the reason of the proposal of a real time access protocol. This protocol is implemented by a Java-based middleware between TCP/IP and user's real time applications. In order to introduce more determinism in the execution of the Java code, the PERC Real-Time Java Virtual Machine has been used. The paper focuses on the description of the centralised access protocol and its performance evaluation using the real-time PERC Virtual Machine
Industrial Electronics, 2001. Proceedings. ISIE 2001. IEEE International Symposium on; 02/2001
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, an implementation profile for the European Home System (EHS) is presented. The proposal derives from the consideration that the communication functions featured by the EHS communication stack are too complex for the application scenarios to which EHS is to be applied. After an analysis of each level of the EHS communication stack, pointing out the relative implementation complexity, a simplification is proposed, consisting of the definition of a communication device, called Small Simple Device-SSiD. The main features of the implementation profile proposed are: the simplicity of implementation of SSiDs; and total compatibility with the EHS standard.
Industrial Technology 2000. Proceedings of IEEE International Conference on; 02/2000
-
[show abstract]
[hide abstract]
ABSTRACT: Field bus technology is now a reality in industrial environments.
There are many field bus systems commercially available, and each is
suitable for particular kinds of applications. In this scenario the
Interbus-S system is playing a leading role, due to the efficiency of
its protocol. However, a drawback of this communication system is the
centralisation of the mono-master arbitration scheme. The presence of a
single device to co-ordinate communication activities makes the
Interbus-S protocol vulnerable to fault occurrences in the master.
Maintaining full compatibility with the existing standard, the authors
have defined a protocol extension which allows the whole communication
system to continue working after the occurrence of a fault in the master
node
Factory Communication Systems, 2000. Proceedings. 2000 IEEE International Workshop on; 02/2000
-
[show abstract]
[hide abstract]
ABSTRACT: The aim of the paper is to evaluate the impact of the occurrence
of faults on the IEC 61158 type 1 field-bus protocol. This communication
system was developed for use in a process control environment, where
robustness to the occurrence of a fault is an important requirement.
After a survey of the protocol's main features, certain types of
failures are defined, the occurrence of which may be critical for the
communication system. It is shown that for some of the failures
considered, the IEC 61158 type 1 protocol doesn't foresee any recovery
procedure. When other failures occur, the fault states caused by them,
may be not recovered by the fault recovery procedures provided for by
the IEC 61158 type 1 standard. In particular it is shown that the
standard provides for procedures aimed to recover faults caused by some
kind of failure, but these procedures are unable to perform their goal.
The evaluation of the effect of these faults on the performance of the
communication system seems to be an important issue. For this reason,
the paper presents a performance evaluation of the fault recovery
mechanisms, foreseen by the IEC protocol, but unable to recover some
faults. The evaluation is based on Petri Net model simulation, and is
aimed at evaluating the impact on the recovery procedures on the
information flow between control processes
Industrial Electronics, 2000. ISIE 2000. Proceedings of the 2000 IEEE International Symposium on; 02/2000
-
S. Cavalieri
[show abstract]
[hide abstract]
ABSTRACT: The main goal of the paper is to propose a methodology to improve
the performance of a flexible manufacturing system (FMS), based on the
use of Petri nets. The modelling is performed with the aim to represent
the general behaviour of the FMS, avoiding a detailed description of the
operations it involves. The model of the FMS is then used to evaluate
its performance through simulation. The methodology proposed in the
paper allows tuning suitable parameters of the FMS in order to improve
its performance. The paper refers to a case study concerning the ST
Microelectronics plant in Catania (Italy) for the production of
semiconductor devices
Industrial Electronics Society, 2000. IECON 2000. 26th Annual Confjerence of the IEEE; 02/2000
-
S Cavalieri
[show abstract]
[hide abstract]
ABSTRACT: The paper deals with integer linear programming problems. As is well known, these are extremely complex problems, even when the number of integer variables is quite low. Literature provides examples of various methods to solve such problems, some of which are of a heuristic nature. This paper proposes an alternative strategy based on the Hopfield neural network. The advantage of the strategy essentially lies in the fact that hardware implementation of the neural model allows for the time required to obtain a solution so as not depend on the size of the problem to be solved. The paper presents a particular class of integer linear programming problems, including well-known problems such as the Travelling Salesman Problem and the Set Covering Problem. After a brief description of this class of problems, it is demonstrated that the original Hopfield model is incapable of supplying valid solutions. This is attributed to the presence of constant bias currents in the dynamic of the neural model. A demonstration of this is given and then a novel neural model is presented which continues to be based on the same architecture as the Hopfield model, but introduces modifications thanks to which the integer linear programming problems presented can be solved. Some numerical examples and concluding remarks highlight the solving capacity of the novel neural model.
International Journal of Neural Systems 03/1999; 9(1):27-39. · 4.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The solution of constrained satisfaction and constrained optimization problems using a Hopfield model requires determination of the values of a certain number of coefficients linked to the surrounding conditions of the problem. It is quite difficult to determine these values, mainly because a heuristic search is necessary. This is not only time-consuming but may lead to solutions that are far from optimal, or even nonvalid ones. So far, there have been no works in literature offering a general method for the search for coefficents with will guarantee optimal or close to optimal solutions. This paper proposes a fuzzy approach which allows automatic determination of Hopfield coefficients.
IEEE Transactions on Systems Man and Cybernetics Part B (Cybernetics) 02/1999; 29(6):895-902. · 3.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The aim of the paper is to propose a fault recovery model to be adopted in the IEC/ISA FieldBus communication protocol. The authors present the results of their research, which highlights that some types of fault cannot be recovered by the IEC/LSA FieldBus protocol, whereas others are recovered but the time required is at times excessive. The paper then suggests some innovative recovery mechanisms which, along with those the protocol currently offers, are able to guarantee a high degree of reliability. The proposed mechanisms are compatible with the actual FieldBus communication protocol as they could be included in the system and network management layer, which is not yet totally defined. The paper concludes by presenting an evaluation of the fault recovery mechanisms proposed, demonstrating their effectiveness
Industrial Electronics, 1999. ISIE '99. Proceedings of the IEEE International Symposium on; 02/1999
