IEEE CONTROL SYSTEMS SOCIETY TECHNICAL COMMITTEE
ON DISCRETE EVENT SYSTEMS

    Ryan J. Leduc
    Chair, IEEE CSS Technical Committee on DES
    Dept. of Computing and Software
    McMaster University
    1280 Main Street West
    Hamilton, Ontario
    Canada L8S 4K1

    Phone: (905) 525-9140 Ext. 27962
    Fax: (905) 524-0340
    e-mail: leduc@mcmaster.ca
    WWW: http://www.cas.mcmaster.ca/~leduc/

DESTC Web Page: http://www.cas.mcmaster.ca/destc/

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Contents:

1. Editorial

2. Announcements
 2.1 PhD and PostDoc positions at University of Zaragoza, Spain

3. Conferences
 3.1 European Control Conference 2009 (ECC'09), Budapest, Hungary,
     August 23 - 26, 2009
 3.2 ACM-SIAM Symposium on Discrete Algorithms (SODA09), New York, New
     York, USA, January 4 - 6, 2009

4. Journals
 4.1 Selections from Automatica, Volume 44, Issue 7, July 2008
 4.2 Selections from International Journal of Control, Volume 81 Issue
     9, September 2008
 4.3 Selections from IEEE Transactions on Man and Cybernetics, Part A,
     Volume: 38, Issue: 4, July 2008

Welcome to the newsletter of the IEEE Control Systems Technical Committee on Discrete Event Systems!

See http://www.cas.mcmaster.ca/destc/ for information on the DESTC.

Personal note from the editor:

Welcome to the July edition of the DESTC newseltter.  Sorry it's late. 

Ryan

Contributed by: Cristian Mahulea <cmahulea@unizar.es>

PHD AND POSTDOC POSITIONS AT UNIVERSITY OF ZARAGOZA, SPAIN

==========================================================================
   * PhD position with a grant for 4 years.
   * PostDoc position for one year (and can be extended to a second one).

Systems Engineering and Discrete Event Systems Group
(http://webdiis.unizar.es/GISED)
University of Zaragoza (Spain)

==========================================================================
The activities of the group are related to the modelling, analysis and
formal synthesis of some classes of artificial systems that are
interesting from a technical point of view (production, computer,
logistic, coordination, etc.). Usually more adequately modelled by
means of discrete event systems formalisms (automata, Petri nets,
process algebra, queuing networks...), the state explosion problem puts
a limit to most of the analysis or synthesis techniques. Relaxations
based on fluidification appear as a possible way to overcome these
difficulties when largely populated systems or systems with high
cadence are considered.

More specifically, the project will be mainly focused on the formalism
of continuous and hybrid Petri nets, defined by relaxing the
integrality constraint in a similar way as in fluid queuing networks.

Activities will be mainly related to the following aspects:

   * Modelling (fluidisability of ­discrete event­ net models)
   * Analysis and verification (both structural and model checking)
   * Optimization of design (placement and size of buffers, equipment
selection, ...) 
   * Operation (centralized and modular control, scheduling)
   * Observers design
   * Discretization of optimal continuous trajectories
   * Development of adequate computer tools for the modelling, analysis
and synthesis.

==========================================================================
PhD position

The main task for the accepted candidate will be to conduct research
towards his/her PhD. The candidate is expected to complete the degree
within 4 years.

Applicants must have MSc (or equivalent) degree in Automatic Control,
Computer Science, Mathematics, Electrical/Electronics or Communications
Engineering. Some knowledge on formal models on computer science,
automatic control or operational research will be especially welcome.

The salary will be around 1200 EUR/month, with an incremental raise in
the following years. Health insurance will also be provided.

The candidate could start on October-November 2008 or January 2009.

==========================================================================
PostDoc position

The position will be for one year (and can be extended to a second one).

A PhD-degree in automatic control, computer science, or operations
research is required. Knowledge on Petri nets, hybrid or piecewise
linear systems will be especially welcome.

The salary will be around 2000 EUR/month (in case, with an incremental
raise in the following year). Health insurance will also be provided.

The candidate could start on October-November 2008 or January 2009.
Contact:

==========================================================================
Applicants should send by email their CVs before 8th September 2008 to:

Prof. Manuel Silva (silva@unizar.es)
with copy to Dr. Cristian Mahulea (cmahulea@unizar.es)

Departamento de Informática e Ingeniería de Sistemas, and
Instituto de Investigación en Ingeniería de Aragón (I3A)
Universidad de Zaragoza

María de Luna, 1
50018 ZARAGOZA (Spain)
==========================================================================

Contributed by: Ryan Leduc <leduc aT mcmaster dOt ca>

EUROPEAN CONTROL CONFERENCE 2009 (ECC'09)
Budapest, Hungary
August 23 - 26, 2009

CALL FOR PAPERS

The European Control Conference (ECC) is organised biannually under the
auspices of the European Union Control Association (EUCA) and aims to
bring together academic and industrial professionals in the field of
systems and control, and promote scientific cooperation and exchanges
within the European Union and between Europe and other parts of the
World.

ECC'09 is the 10th in the EUCA Series of European Control Conferences
and will be held in Budapest, capital of Hungary, between 23-26 August
2009. The Conference local organiser is the Computer and Automation
Research Institute of the Hungarian Academy of Sciences (MTA SZTAKI),
the member of ERCIM.

TOPICS

The topics of the conference will include, but will not be limited to,
the followings:

Adaptive and Learning Systems; Autonomous Systems; Biological
Systems; Computational Methods; Control Applications; Control
Education; Control of Electrical Systems; Control of Mechanical
Systems; Discrete Event Systems; Distributed Parameter Systems;
Emerging Control Theory and Applications; Fault Detection and
Accommodation; Hybrid Systems; Intelligent Systems; Large-Scale
Systems; Linear Systems; Micro and Nano Systems; Modeling; Networks
and Communication; Nonlinear Systems; Optimization; Process Control
Systems; Signal Processing; Stochastic Systems; System Identification;
Uncertain Systems; Verification and Validation

SUBMISSION INFORMATION

Original high-quality papers dealing with the theory and practice of
systems and control are welcome for presentation. Besides contributed
and interactive papers, the conference will also have plenary/semi-
plenary papers and mini-tutorials.

For further information, please visit the conference web site:
www.conferences.hu/ecc09

IMPORTANT DATES

Deadline for invited session proposals: 15 September 2008
Deadline for paper submission: 15 October 2008
Notification of acceptance/ non-acceptance: 1 March 2009
Early registration deadline: 15 May 2009
Deadline for final manuscripts submission: 31 May 2009

Looking forward to meeting you in Budapest, Hungary in August 2009

Laszlo Keviczky
General Chair of ECC'09

Jozsef Bokor
IPC Chair of ECC'09

web site: click here

Contributed by: Ryan Leduc <leduc aT mcmaster dOt ca>

ACM-SIAM SYMPOSIUM ON DISCRETE ALGORITHMS (SODA09)
New York, New York, USA
January 4 - 6, 2009

This symposium focuses on research topics related to efficient
algorithmsand data structures for discrete problems. In addition to
the design of such methods and structures, the scope also includes
their use, performance analysis, and the mathematical problems related to
their development or limitations. Performance analyses may be analytical or
experimental and may address worst-case or expected-case
performance. Studies can be theoretical or based on data sets that have
arisen in practice and may address methodological issues involved in
performance analysis.

SUBMISSION DEADLINES
June 26, 2008 - Pre-Submission Deadline
July 3, 2008 - Final Submission Deadline

PRE-REGISTRATION DEADLINE
December 1, 2008

HOTEL RESERVATION DEADLINE
December 1, 2008

web site: click here

Contributed by: Ryan Leduc <leduc aT mcmaster dOt ca>

SELECTIONS FROM AUTOMATICA
VOLUME 44, ISSUE 7
JULY, 2008

1)Reduction of constraints for controller synthesis based on safe Petri
Nets

Abbas Dideban, Hassane Alla

Abstract:

In this paper, we present an efficient method based on safe Petri Nets
to construct a controller. A set of linear constraints allows
forbidding the reachability of specific states. The number of these
so-called forbidden states, and consequently the number of constraints,
are large and lead to a large number of control places. A systematic
method to reduce the size and the number of constraints for safe Petri
Nets is offered. By using a method based on Petri Net invariants,
maximal permissive controllers are determined.

2) Dynamic buffer management using optimal control of hybrid systems

Wei Zhang, Jianghai Hu

Abstract: 

This paper studies a dynamic buffer management problem with one buffer
inserted between two interacting components. The component to be
controlled is assumed to have multiple power modes corresponding to
different data processing rates. The overall system is modeled as a
hybrid system and the buffer management problem is formulated as an
optimal control problem. Different from many previous studies, the
objective function of the proposed problem depends on the switching
cost and the size of the continuous state space, making its solution
much more challenging. By exploiting some particular features of the
problem, the best mode sequence and the optimal switching instants are
characterized analytically using a variational approach. Simulation
results based on real data shows that the proposed method can
significantly reduce the energy consumption compared with another
heuristic scheme in several typical situations.

web site: click here

Contributed by: Ryan Leduc <leduc aT mcmaster dOt ca>

SELECTIONS FROM INTERNATIONAL JOURNAL OF CONTROL
VOLUME 81 ISSUE 9
SEPTEMBER, 2008

1) Incremental hierarchical construction of modular supervisors for
discrete-event systems

R. C. Hill; D. M. Tilbury

Abstract:

Adoption of the supervisory control framework introduced by Ramadge and
Wonham has been slowed somewhat by the problem of state space explosion
that arises in systems of the scale common to most industrial
applications. Hierarchical and modular approaches have been explored
historically as means for addressing this problem. The limitations of
these approaches include that a 'consistent' hierarchy is often
difficult to achieve, and that modular supervisors often conflict with
each other when acting in conjunction. This paper offers an approach
that addresses some of these issues by incrementally building modular
supervisors that are nonconflicting by construction. Abstractions are
employed to make the procedure more computationally feasible. Proof is
given showing the set of modular supervisors generated in this manner
meet given specifications without blocking. Furthermore, examples are
provided that demonstrate the reduction in complexity that this
approach provides.

2) Supervisory control of discrete-event systems with output:
Application to hybrid systems 

Pedram Mahdavinezhad;  Peyman Gohari; Amir G. Aghdam

Abstract:

In this paper, the problem of supervisory control of discrete-event
systems (DES) with output is presented and discussed at length. In such
systems, causal output maps are employed to assign to each sequence of
input events a corresponding sequence of output events. When the
specification of desired behaviour is given by a formal language over
the output alphabet, necessary and sufficient conditions are derived
for the existence of non-blocking input as well as non-blocking output
supervisory control. After making minor adjustments the theory is
applied to non-deterministic discrete-event abstractions of hybrid
systems, giving rise to the development of a theory for non-blocking
supervisory control of hybrid systems. Our results enable one to apply
classical supervisory control theory to design supervisors for DES
approximations of hybrid systems, and to import many interesting
concepts from classical theory such as modular and hierarchical
control.

web site: click here

Contributed by: Ryan Leduc <leduc aT mcmaster dOt ca>

SELECTIONS FROM IEEE TRANSACTIONS ON MAN AND CYBERNETICS, PART A
VOLUME: 38, ISSUE: 4
JULY, 2008

1) Preserving Languages and Properties in Stepwise Refinement-Based
Synthesis of Petri Nets

Ding, Z.J.; Jiang, C.J.; Zhou, M.C.; Zhang, Y.Y.

Abstract:

The current stepwise refinement operation of Petri nets mainly
concentrates on property preservation, which is an effective way to
analyze and verify complex systems. Further steps into this field are
needed from the perspective of system synthesis and language
preservation. First, the refinement of Petri nets is introduced based
on a $k$ -well-behaved Petri net, in which  $k$ tokens can be
processed. Then, according to the different compositions of subsystems,
well-, under- and overmatched refined Petri nets are proposed. In
addition, the language and property relationships among sub-, original,
and refined nets are studied to demonstrate behavior characteristics
and property preservation in a system synthesis process. A
manufacturing system is given as an example to illustrate the
effectiveness of the proposed approach in synthesizing and analyzing
the Petri nets of complex systems.

2) Modeling and Analysis for Workflow Constrained by Resources and
Nondetermined Time: An Approach Based on Petri Nets

Huaiqing Wang; Qingtian Zeng

Abstract:

Time and resource management and verification are two important aspects
of workflow management systems. In this paper, we present a modeling
and analysis approach for a kind of workflow constrained by resources
and nondetermined time based on Petri nets. Different from previous
modeling approaches, there are two kinds of places in our model to
represent the activities and resources of a workflow, respectively. For
each activity place, its input and output transitions represent the
start and termination of the activity, respectively, and there are two
timing functions in it to define the minimum and maximum duration times
of the corresponding activity. Using the constructed Petri net model,
the earliest and latest times to start each activity can be calculated.
With the reachability graph of the Petri net model, the timing factors
influencing the implementation of the workflow can be calculated and
verified. In this paper, the sufficient conditions for the existence of
the best implementation case of a workflow are proved, and the method
for obtaining such an implementation case is presented. The obtained
results will benefit the evaluation and verification of the
implementation of a workflow constrained by resources and nondetermined
time.

web site: click here