Fax
(still useful):
+33 4 92 38 79 71
A brief biography
I received
the Ph.D degree and the "Habilitation à diriger des recherches",
both in Computer Science, from the University of Orsay (Paris XI),
France, in 1989 and 1993, respectively.
I am currently a research director
at the performance evaluation group
MISTRAL of
the national research center on information and automation
(INRIA),
France.
My current research interests are in
control and performance analysis
of high speed communication networks,
scheduling and performance evaluation
of parallel and distributed systems.
I am also interested in Petri nets
and queueing networks.
One of my current activities consists in leading a project on
the modeling and the characterization of Web traffic.
We have been developing a software tool
WAGON
(Web
trAffic
GeneratOr
and beNchmark)
for generating Web traffic and for the performance
evaluation of Web servers and cache.
You are welcome to take a look at my
list of publications
to have a more general idea of my research activities.
I have been teaching DEA (i.e. Frecnch graduate) courses of Operations
Research, Networking and Parallel Computing for more than ten years.
These courses are concerned with Queueing Theory, Probabilistic Modeling,
Stochastic Scheduling and Quality of Service in Computer Networks.
Currently I am involved in the
DEA IRO
(Informatique et Recherche Opérationnelle, i.e.
Computer Science and Operations Research)
of the
University of Pierre & Marie Curie (Paris VI)
and the
DEA RSD
(Réseaux et Systèmes Distribués, i.e.
Computer Networks and Distributed Systems)
of the
University of Nice  Sophia Antipolis,
France.
I am currently supervising two Ph.D. students:
Past Graduate Students:
My research interests
are in
control and performance analysis
of high speed communication networks,
scheduling and performance evaluation
of parallel and distributed systems.
I am also interested in
queueing networks and Petri nets.
As a particular application area, I'm interested in the
analysis and optimization of the performance of Web servers and
Web applications.
You can take a look at the page on
our activities related to the
performance issues of the Web.
We are maintaining a
Web page on the literature
related to the above mentioned fields.
Any comments are welcome
and can be mailed to
Zhen Liu,
Nicolas Niclausse
and
Cesar Jalpa.
You are welcome to take a look at my
list of publications
to have a more general idea of my research activities.
Recent publications on Analysis and Optimization of the Performance of Web Servers
and Web Applications.

J. Talim, Z. Liu, P. Nain, E. G. Coffman, Jr.,
``Optimizing the Number of Robots for Web Search Engines'',
to appear in Telecommunication Systems.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/robot_num_ts.ps.gz

E. G. Coffman, Z. Liu, R. Weber,
``Optimal Robot Scheduling for Web Search Engines'',
Journal of Scheduling, Vol. 1, pp. 1529, 1998.
Preliminary version available as INRIA RR, No. 3317, 1997.
http://www.inria.fr/RRRT/RR3317.html
Recent publications on Control and Performance Analysis of
High Speed Communication Networks.

G. Koole, Z. Liu, R. Righter,
``Optimal Transmission Policies for Noisy Channels'',
Technical Report WS515, Faculteit der EXacte Wetenschappen,
Vrije Universiteit Amsterdam, 1999.
to appear in Operations Research.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/noise.ps.gz

A. Hordijk, Z. Liu, D.Towsley,
``Smoothing Effect of the Superposition
of Homogeneous Sources in Tandem Networks'',
to appear in the Journal of the Applied Probability,
Vol. 37, No.3, september 2000.
Preliminary version available as INRIA RR, No. 3839, 1999.
http://www.inria.fr/RRRT/RR3839.html

E. Altman, Z. Liu, R. Righter,
``Scheduling of InputQueued Switch to Achieve Maximal Throughput'',
to appear in Probability in the Engineering and
Information Sciences.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/input_stab.ps.gz

Z. Liu, R. Righter,
``The Impact of Cell Dropping Policies in ATM Networks'',
to appear in Operations Research.
Preliminary version available as INRIA RR, No. 3047, 1996.
http://www.inria.fr/RRRT/RR3047.html

Z. Liu, P. Nain, D. Towsley,
``On a Generalization of Kingman's Bounds'',
Mathematical Methods of Operations Research,
Vol. 49, No. 2, pp. 325333, 1999.
Preliminary version available as INRIA RR, No. 2423, 1994.
http://www.inria.fr/RRRT/RR2423.html

Z. Liu, R. Righter,
``Scheduling Multicast InputQueued ATM Switches'',
Journal of Scheduling, Vol. 2, pp. 99114, 1999.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/multicast.ps.gz

Z. Liu, P. Nain, D. Towsley, Z.L. Zhang,
``Asymptotic Behavior of a Multiplexer Fed by
a LongRange Dependent Process'',
Journal of Applied Probability, Vol. 36, No. 1, pp. 105118,
March 1999.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/mg_infty.ps.gz

Z.L. Zhang, Z. Liu, D. Towsley,
``ClosedForm Deterministic EndtoEnd Performance Bounds
for the Generalized Processor Sharing Scheduling Discipline'',
Journal of Combinatorial Optimization,
special issue on Scheduling. Vol. 1, No.4, pp. 457481, 1998.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/gps_e2e.ps.gz

A. JeanMarie, Z. Liu, P. Nain, D. Towsley,
``Computational aspects of the workload distribution in the MMPP/GI/1 queue'',
IEEE Journal on Selected Areas of Communications,
Vol. 16, pp. 640652, June 1998.
Special issue on computational aspects of teletraffic models.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/mmpp_g_1.ps.gz

G. Koole, Z. Liu,
``Stochastic Bounds for Queueing Systems
with Multiple OnOff Sources'',
Probability in the Engineering and
Information Sciences, Vol. 12, pp. 2548, Jan. 1998.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/on_off.ps.gz

Z. Liu, P. Nain, D. Towsley,
``Exponential Bounds with an Application to Call Admission''
Journal of the ACM, Vol. 44, No. 2, 1997.
Preliminary version available as INRIA RR, No. 2865, 1996.
http://www.inria.fr/RRRT/RR2865.html

J.C. Bermond, Z. Liu, M. Syska,
``Mean Eccentricities of de Bruijn Networks'',
Networks, Vol. 30, pp. 187203, 1997.
Preliminary version available as INRIA RR, No. 2114, 1993.
http://www.inria.fr/RRRT/RR2114.html

Z.L. Zhang, Z. Liu, J. Kurose, D. Towsley,
``Call Admission Control Schemes under the
Generalized Processor Sharing Scheduling Discipline'',
Telecommunication Systems, Vol. 7, No. 13, pp. 125152, July 1997.
Preliminary version available as INRIA RR, No. 2711, 1995.
http://www.inria.fr/RRRT/RR2711.html

Z. Liu, T. Y. Sung,
``Routing and Transmitting Problems in de Bruijn Networks'',
IEEE Trans. on Computers , Vol. 45, pp. 10561062, Sept. 1996.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/debruijn.ps.gz

E. Altman, Z. Liu,
``Improving the Stability Characteristics
of Asynchronous Traffic in FDDI Token Ring'',
Performance Evaluation, Vol. 26, pp. 219234, 1996.
Preliminary version available as INRIA RR, No. 1934, 1993.
http://www.inria.fr/RRRT/RR1934.html

Z. Liu, D. Towsley,
``Burst Reduction Properties of RateBased Flow Control Schemes:
Downstream Queue Behavior'',
IEEE/ACM Trans. on Networking, Vol. 3, No. 1, pp. 8290, 1995.
Preliminary version available as INRIA RR, No. 2117, 1993.
http://www.inria.fr/RRRT/RR2117.html
Recent publications on Scheduling, Routing and Performance Evaluation of
Parallel and Distributed Systems.

Z. Liu,
``Dynamic Scheduling of Parallel Computations'',
to appear in Theoretical Computer Science.
Preliminary version available as INRIA RR, No. 3048, 1996.
http://www.inria.fr/RRRT/RR3048.html

Z. Liu, R. Righter,
``Optimal Load Balancing on Distributed Homogeneous
Unreliable Processors'',
Operations Research, Vol. 46, No. 4, pp. 563573,
August 1998.
Preliminary version available as INRIA RR, No. 2659, 1995.
http://www.inria.fr/RRRT/RR2659.html

Z. Liu,
``WorstCase Analysis of Scheduling Heuristics of Parallel Systems'',
Parallel Computing, Vol. 24, issue 45, pp. 863891, 1998.
Preliminary version available as INRIA RR, No. 2710, 1995.
http://www.inria.fr/RRRT/RR2710.html

A. JeanMarie, S. LefebvreBarbaroux, Z. Liu,
``An Analytical Approach to the Performance Evaluation
of MasterSlave Computational Models'',
Parallel Computing, Vol. 24, issue 45, pp. 841862, 1998.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/master_slave.ps.gz

L. Finta, Z. Liu,
``Complexity of Task Graph Scheduling with Fixed Communication Capacity'',
International Journal of Fondations of Computer Science ,
Vol. 8, No. 1 (1997), pp. 4366.
Preliminary version available as INRIA RR, No. 2959, 1996.
http://www.inria.fr/RRRT/RR2959.html

Z. Liu, E. Sanlaville,
``Stochastic Scheduling with Variable Profile and Precedence Constraints'',
SIAM J. on Computing, Vol. 26, No. 1, pp. 173187, 1997.
Preliminary version available as INRIA RR, No. 1525, 1991.
http://www.inria.fr/RRRT/RR1525.html

Z. Liu, R. Righter,
``Optimal Scheduling on Parallel Processors
under Precedence Constraints for General Costs'',
Probability in the Engineering and
Information Sciences, Vol. 11, pp. 7993,
Jan. 1997.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/prec_gen.ps.gz

J. Blazewicz, Z. Liu,
``Scheduling Multiprocessor Tasks with Chain Constraints'',
European Journal on Operations Research, Vol. 94, pp. 231241, 1996.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/chain_task.ps.gz

L. Finta, Z. Liu,
``Single Machine Scheduling Subject to Precedence Delays'',
Discrete Applied Mathematics , Vol. 70, pp. 247266, 1996.
Preliminary version available as INRIA RR, No. 2198, 1994.
http://www.inria.fr/RRRT/RR2198.html

L. Finta, Z. Liu, I. Milis, E. Bampis,
``Scheduling UETUCT SeriesParallel Graphs on Two Processors'',
Theoretical Computer Science,
special issue on Parallelism and Irregularly Structured Problems,
Vol. 162, pp. 323340, July 1996.
Preliminary version available as INRIA RR, No. 2566, 1995.
http://www.inria.fr/RRRT/RR2566.html

Z. Liu, E. Sanlaville,
``Preemptive Scheduling with Variable Profile, Precedence Constraints
and Due Dates'',
Discrete Applied Mathematics , Vol. 58, pp. 253280, April 1995.
Preliminary version available as INRIA RR, No. 1622, 1992.
http://www.inria.fr/RRRT/RR1622.html
Recent publications on the Control and Analysis of Queueing Networks
and Petri nets.

Z. Liu,
``Performance Analysis of Stochastic Timed Petri Nets
using Linear Programming Approach'',
IEEE Trans. on Software Engineering,
Vol. 24, No. 11, pp. 10141030, November 1998.
Preliminary version available as INRIA RR, No. 2642, 1995.
http://www.inria.fr/RRRT/RR2642.html

Y. Dallery, Z. Liu, D. Towsley,
``Properties of Fork/Join Queueing Networks with Blocking under Various
Operating Mechanisms'',
IEEE Trans. on Robotics and Automation,
Vol. 13, No. 4, pp. 503518, Aug. 1997.
Preliminary version available in
http://www.inria.fr/mistral/personnel/Zhen.Liu/Papers/bas.ps.gz

Z. Liu, P. Nain, D. Towsley,
``Sample Path Methods in the Control of Queues'',
Queueing Systems, Vol. 21, pp. 293335,
special issue on Optimal Control in Queueing Systems, 1995.
Preliminary version available as INRIA RR, No. 2457, 1995.
http://www.inria.fr/RRRT/RR2457.html
Last modified: Tue Jul 25 10:59:21 MEST 2000
Zhen Liu