Closed-Loop System Identification Approach of the Inertial Models

The mathematical model that approximates the dynamics of the industrial process is essential for the efficient synthesis of control algorithms in industrial applications. The model of the process can be obtained according to the identification procedures in the open-loop, or in the closed-loop. In the open-loop, the identification methods are well known and offer good process approximation, which is not valid for the closed-loop identification, when the system provides the feedback output and doesn’t permit it to be identified in the open-loop. This paper offers an approach for experimental identification in the closed-loop, which supposes the approximation of the process with inertial models, with or without time delay and astatism. The coefficients are calculated based on the values of the critical transfer coefficient and period of the underdamped response of the closed-loop system with P controller, when system achieves the limit of stability. Finally, the closed-loop identification was verified by the computer simulation and the obtained results demonstrated, that the identification procedure in the closed-loop offers good results in process of estimation of the model of the process.

A SIMPLE NONLINEAR MODEL OF INERTIAL OSCILLATION OF ATMOSPHERE IN LOW-LATITUDES

In this paper,by simplifying the governing equation in low latitudes a nonlinear model which takes into consideration the equatorial β-plane approximation and describes the natural oscillation of the atmosphere has been set up.By applying this model the following results are shown: (1)There exists the pure inertial oscillation only in u_0>0(westerly current),the angular frequency of linear oscillation of y is ω_0~*=(β_0u_0~*)^(1/2),the corresponding oscillatory period is 1—2 weeks.There are two kinds of angular frequencies under the nonlinear condition,the one is ω_0=(β_0u_0)^(1/2)the other is ω_1= 1/2 β_0y_0.When a soliton oscillator occurs(ω_1=ω_0),the oscillatory period increases rapidly,and T→∞. (2)When the pressure field is considered,the oscillation exists not only in u_0>0(westerly current) but also in u_0<0(weak easterly current).However this weak pressure field has slight effect on the oscillatory period. (3)The stability of inertial oscillation depends on the linear inertial parameter μ.As the parameter μ changes sign from negative to positive,the supercritical bifurcation takes place in b<0.

Energy loss of tens keV charged particles traveling in the hot dense carbon plasma

The energy loss of charged particles, including electrons, protons, and α-particles with tens keV initial energy E0, traveling in the hot dense carbon(C) plasma for densities from 2.281 to 22.81 g/cm3 and temperatures from 400 to 1500 eV is systematically and quantitatively studied by using the dimensional continuation method. The behaviors of different charged particles are readily distinguishable from each other. Firstly, because an ion is thousands times heavier than an electron, the penetration distance of the electron is much longer than that of proton and α-particle traveling in the plasma. Secondly, most energy of electron projectile with E0 < 100 keV deposits into the electron species of C plasma, while for the cases of proton and α-particle with E0 < 100 keV,about more than half energy transfers into the ion species of C plasma. A simple decreasing law of the penetration distance as a function of the plasma density is fitted, and different behaviors of each projectile particle can be clearly found from the fitted data.We believe that with the advanced progress of the present experimental technology, the findings shown here could be confirmed in ion-stopping experiments in the near future.