Papers by michel cotsaftis
SIGLEAvailable from CEN Saclay, Service de Documentation, 91191 Gif-sur-Yvette Cedex (France) / I... more SIGLEAvailable from CEN Saclay, Service de Documentation, 91191 Gif-sur-Yvette Cedex (France) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
in Lisbon, Portugal, continued a series of events taking a global perspective on population healt... more in Lisbon, Portugal, continued a series of events taking a global perspective on population health, from national to crosscountry approaches, multiplatform technologies, from drug design to medicine accessibility; everything under mobile, ubiquitous, and personalized characteristics of new age population. Recent advances in technology and computational science influenced a large spectrum of branches in approaching population health. Despite significant progress, many challenges exist, including health informatics, crosscountry platforms interoperability, system and laws harmonization, protection of health data, practical solutions, accessibility to health services, and many others. Along with technological progress, personalized medicine, ambient assistance and pervasive health complement patient needs. A combination of classical and information-driven approach is developing now, where diagnosis systems, data protection mechanisms, remote assistance and hospital-processes are conver...
Physics Letters, 1983
The conditions for excitation of a standing magnetosonic wave structure in the region between the... more The conditions for excitation of a standing magnetosonic wave structure in the region between the ion-ion hybrid cut-off layer and an antenna situated near the wall on the outside of a toroidal plasma have been derived. It is shown that low-order radial eigenmodes may be excited under usual conditions, but the order of the mode increases as the plasma density
In order to give complex mechanical systems more capabilities in their dynamic behavior, it is re... more In order to give complex mechanical systems more capabilities in their dynamic behavior, it is recognized that they belong to a class of systems for which the classical approach has to be amended to comply with their very structure. This means that, as they exhibit a complicated and mixed pattern of displacements and deformations, their trajectories become exceedingly complicated and no structured information can be obtained from them. This leads to the concept of functional control, which is precisely aimed at globally controlling the system from its accessible previous rigid variables without entering the (unusable) detail of exact trajectories. Milder asymptotic convergence of the solution of the error equation is obtained than with (inapplicable) classical trajectory control (typically, polynomial vs. exponential decay). A possible improvement is obtained by adding a learning-type control, allowing past trajectory information to be accounted for by setting its parameters so that a converging fixed point property can be obtained
Kybernetika, 1997
Institute of Mathematics of the Academy of Sciences of the Czech Republic provides access to digi... more Institute of Mathematics of the Academy of Sciences of the Czech Republic provides access to digitized documents strictly for personal use. Each copy of any part of this document must contain these Terms of use.
HAL (Le Centre pour la Communication Scientifique Directe), Oct 4, 2007
They mainly concentrate on the difficult balance to be established between the relative system is... more They mainly concentrate on the difficult balance to be established between the relative system isolation when becoming complex and the delegation of corresponding new capability from (outside) operator. This implies giving the system some "intelligence" in an adequate frame between the new augmented system state and supervising operator, with consequences on the canonical system triplet {effector-sensor-controller} which has to be reorganized in this new setting. Moreover, it is observed that entering complexity state opens the possibility for the function to feedback onto the structure, ie to mimic at technical level the invention of Nature over Her very long history.
Nuclear Fusion, Mar 1, 1964
A method is proposed for discussing the linear stability of the stationary states of a Lagrangian... more A method is proposed for discussing the linear stability of the stationary states of a Lagrangian system by considering the marginally stable modes. A necessary and sufficient condition for marginal stability is derived. Perturbation theory is used to compute the change in frequency of a marginally stable mode as a result of a small change in the system. It is
Journal of nuclear energy, 1965
In the simple case of a cylindrical plasma with superficial current shear, a new instability due ... more In the simple case of a cylindrical plasma with superficial current shear, a new instability due to a coupling between compressibility and resistivity has been found. Near acoustic velocity phase, the growth rate of this instability is in η 1/4. In toroidal systems, this instability can appear under Kruskal limit, even for the mode m = 1, for which the stability limit is 1/2 in i/2π units, and the stability limit for m > 1 modes is the closer to 0 the greater is m.
Plasma Physics, Dec 1, 1979
ABSTRACT A differential equation for small amplitude wave propagation in a hot nonuniform magneti... more ABSTRACT A differential equation for small amplitude wave propagation in a hot nonuniform magnetized plasma is derived from the Vlasov equation by a perturbation expansion in the smallness of the Larmor radius compared to characteristic scale-lengths of the plasma. This equation is developed primarily to study the effects of strong plasma nonuniformities on propagation of waves which have counterparts in a uniform magnetized plasma. It consistently incorporates collisionless Landau-cyclotron damping effects in the wave propagation and is valid for wavelengths comparable to the scale-lengths of nonuniformities. Other features explicitly included in the equation are: (i) multiple ion species and (ii) weak nonlinear effects. An ordering has been established to evaluate the relative importance of finite Larmor radius effects and nonlinear effects.
Journal de physique. Colloque, Jul 1, 1979
A differential equation for small amplitude wave propagation in a hot nonuniform magnetized plasm... more A differential equation for small amplitude wave propagation in a hot nonuniform magnetized plasma is derived from the Vlasov equation by a perturbation expansion in the smallness of the Larmor radius compared to characteristic scale-lengths of the plasma. This equation is developed primarily to study the effects of strong plasma nonuniformities on propagation of waves which have counterparts in a uniform magnetized plasma. It consistently incorporates collisionless Landaucyclotron damping effects in the wave propagation and is valid for wavelengths comparable to the scale-lengths of nonuniformities. Other features explicitly included in the equation are: (i) multiple ion species and (ii) weak nonlinear effects. An ordering has been established to evaluate the relative importance of finite Larmor radius effects and nonlinear effects. As a simple application of the basic equation, we discuss wave propagation in the ion-cyclotron range of frequencies in a hot nonuniform cylindrical plasma column with multiple ion-species and show that the phenomenon is essentially determined by a simple second order ordinary differential equation.
International Journal of Control, Dec 1, 1978
ABSTRACT
Nuclear Fusion, May 1, 1967
Ima Journal of Applied Mathematics, 1969
HAL (Le Centre pour la Communication Scientifique Directe), Nov 17, 2005
A consequence of very fast technology development is the appearance of new phenomena in man made ... more A consequence of very fast technology development is the appearance of new phenomena in man made systems related to their large number of heterogeneous interacting components. Then because of resulting larger complexity over passing human operator capability, the system can no longer be only guided and controlled at trajectory level. A larger and more global delegation should be given the system at decision making, and it is proposed here to manage it at task level usually corresponding to well identified sequences in system operation. To succeed in this transfer attention has to be paid to the fact that there are in general many trajectories for one prescribed task. So a new and completely transparent link should be established between trajectory and task controls, both acting at their own levels in the system. The corresponding double loop control is developed here, and consists mainly in an asymptotically stable functional control acting at trajectory level as a whole, and explicit in terms of main system power bounds guaranteeing robustness inside a ball the size of which is the manifold generated by all system trajectories for task accomplishment. At higher level a new decision control based on trajectory utility for succeeding in the task is proposed, the role of which is to maintain system dynamics inside the selected trajectory manifold corresponding to task. With this two step control, human operator role is eased and can be more oriented toward higher coordination and maintenance management.
The results of experiments in which oxygen gas is injected at the current plateau of a quasistati... more The results of experiments in which oxygen gas is injected at the current plateau of a quasistationary TFR deuterium plasma are presented. As a consequence of the injection, the molybdenum density in the plasma decreases, apparently because of a decreased molybdenum flux entering the plasma. This density decrease has a time constant which is a measure of the impurity particle
This chapter discusses a training simulator concept that has been developed for operator training... more This chapter discusses a training simulator concept that has been developed for operator training of hydraulic elevating platforms. Intervention in high place such as buildings requires hydraulic elevating platforms commonly used for assembling outside covers, washing windows, as well as inspection and safety for repairs, rescuing persons and fire fighting. As these platforms are aimed at providing a complex service, their operation, even when simplified by adequate design, requires a sophisticated action, which has to be learned by operator using a concept of a man-in- the-loop simulator. The simulator consists of the elevator platform mounted on a classical Stewart platform. Amplitudes of platform motion are reduced at actuator control level and smaller movements than in the real boom system are produced. As a consequence for validation of the simulator, a strong limitation is coming from the needs of a simulation model satisfying contradictory properties of accuracy and real time computation, which is transforming large boom movements to produce restricted motion in the Stewart mechanism.
IFAC Proceedings Volumes, Sep 1, 2000
In this paper the dynamics of a roll-nip system in paper finishing units in the case of pol ymer ... more In this paper the dynamics of a roll-nip system in paper finishing units in the case of pol ymer covered roll is studied. The delay effect which provides an important additional effect on roll defonnation and vibration of the system has been taken into account. The dynamical behavior of this system has been analysed in frequency domain and time domain.
From third international symposium on toroidal plasma confinement; ; Garching, Germany (26 Mar 19... more From third international symposium on toroidal plasma confinement; ; Garching, Germany (26 Mar 1973). In the TFR experiment, the pulse duration of ; the plasma current is expected to reach 0.5 s. This is much longer than the ; resistive penetration time of the copper shell and a feedback system must be used ; to control the plasma position. The primary and equilibrium circuits used have ; three purposes: to introduce the current into the plasma, to produce the vertical ; field needed for the equilibrium of the plasma column, and to compensate the ; transverse stray fields before the breakdown. A numerical code is being written ; that takes into account all the external circuits: primary, equilibrium circuit, ; liner, copper shell, plasma, and feed-back loops. This code will give the ; current evolution in all the circuits and the plasma parameters. (GE);
ABSTRACT Current emerging technologies in Wireless Sensor Networks are providing protocols and op... more ABSTRACT Current emerging technologies in Wireless Sensor Networks are providing protocols and operating systems to build up the Internet Of Things which heads towards SaaS approach in the Cloud. However, this paper discusses about the impossibility to directly route all nodes from the Cloud. Hence, this paper proposes a new framework based on mobile agents to distribute and deploy applications over a CoAP middleware. This is mainly performed using a distributed publish-subscribe mechanism on each node. The solution allows agents to model distributed applications and their remote deployments.
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Papers by michel cotsaftis