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 My Research
Research Interest: Control System, Information System,
Nonlinear Dynamics, Chaos, Bifurcation,Secure Communication
Recent Researchs:
Modelling and Classifying ECG signals.
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We want to investigate a chaos-based technique for
modeling the diversity of approximately periodic signals
(ECG signals),combined with generalized chaotic synchronization
phenomena.
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Time-Delay Chaos Based Secure Communication System
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According to the obtained results, we have found
time-delay Lorenz system can generate complex chaotic
attractors and complicated time series which is suitable
to secure communication. Considering time-delay Lorenz
system as a key stream generator, we have developed
a hybrid cryptosystem, composed of symmetric key algorithms
and asymmetric key algorithms.
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Synchronization on Time-Delay Chaotic Systems
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Based on Lyapunov stability theory, a functional
relation that exists in two coupled time-delay chaotic
systems is designed to obtain synchronization. This
proposed synchronization method owns some advantages.
One is that there is no need to calculate the conditional
Lyapunov exponents for determining if there is a copy
subsystem can synchronize with the original one. Another
advantage is that the initial states of transmitting
system and receiving system haven't to be restricted
in the same attracting region.
For instance, consider the following system(obtained
from Lorenz system added linear DFC):
When K=5 and delay time =0.8, the above system can
not be synchronized by common drive-response method.
By setting up a suitable coupling function relation,
we construct a receiving system which can be synchronized
with sending system (referred as the above system).
The result is implicated as follow.
However we need do further work to apply this synchronization
scheme to secure communication since usually the designed
coupling function relation composes of more than one
single driving signal, which is difficult to be implemented
in real communication system.
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Control and Anticontrol of Lorenz System by Using
Linear Time Delayed Feedbacks
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A linear DFC(Delayed Feedback Control) is employed
to investigate the effects of time delay on original
Lorenz system. The control scheme is shown in the below
figure.
Complex dynamic behaviors, including periodic, quasi-periodic,
chaotic motions have been found. Some new chaotic attractors
are shown, for instance, a 3-scroll attractor similar
to Chen's attractor and another very strange attractor
like "wormhole" etc.
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| Original Lorenz Attractor
3-Scroll Chaotic Attractor
"Wormhole" Chaotic Attractor |
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Graduate Thesis (09/2002--present) |
07-25-2003
00:17 pm |
 Topic: "Time-Delay Chaos Based Communication System
Encryption"
Basic research of nonliear dynamics, chaos control and synchronization,
and cryptgraphy. In order to construct a highly secure chaos
based communication system, more complex chaotic attractors
should be obtained. Time-delay chaotic system is considered
to be a suitable candidate for secure communication. I first
investigated the effect of time delayed feedbacks on Lorenz
system and found that rich delay-induced dynamics behaviors
come up in the sysetm under consideration, including periodc,
quasi-periodic, chaotic motions and several complex chaotic
attractors. Then I research the synchronization technique
of the time-delay chaotic systems. After synchronization,
I will apply it to the secure communication based on Internet,
doing some noise perturbation or decoding analysis and making
necessary adjustments. Now I have obtained a time-delay chaos
model which is a fresh result in the international nonlinear
field and I have also implemented a secure communication system
in our lab by using Java and SQL Server database.
| Undergraduate Thesis (03/2001--07/2001) |
07-24-2003 00:02 pm |
Topic: "Realization
of the 3-D Hydraulic Fracturing Simulation Software"
The realization of the 3-D hydraulic fracturing simulation
software is introduced completely in this paper. This software
use Borland C++Builder5.0 as a front design implements and
its back database is created by Microsoft SQL Server7.0. It
is introduced in this paper about C++Builder and SQL Server,
the law of oriented object design, and the basic knowledge
of database in client/server mode. The design of window during
the software development is also discussed in this paper.
The process of designing and setting up database is described
in details and several main problems in programming by C++
Builder are listed. The 3-D hydraulic fracturing simulation
software will be applicated extensively in engineering practice
of exploiting oil and natural gas etc.
| Automatic Control System
for Pumping Station (07/2000--09/2000) |
07-23-2003 22:02 pm |
As a research assistant in Central Laboratory of Electrical
and Information Engineering College, Tongji University. Responsible
for designing and programming the control system to implement
the water treatment technics flow in a pumping station of
Baotou Second Steel Factory, in which the programmable logic
controller (PLC) of SIEMENS Corporation played an important
role. I also accompanied with my mentor to Baotou city for
optimizing and debugging system and later I had a paper published
in "2001 Water Treatment Automation Technology Conference".
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