Plasma sheet oscillations and their relation to substorm development: Cluster and double star TC1 case study

We examined two consecutive plasma sheet oscillation and dipolarization events observed by Cluster in the magnetotail, which are associated with a pseudo-breakup and a small substorm monitored by the IMAGE spacecraft. Energy input from the solar wind and an associated enhancement of the cross-tail current lead to current sheet thinning and plasma sheet oscillations of 3–5 min periods, while the pseudo-breakups occur during the loading phase within a spatially limited area, accompanied by a localized dipolarization observed by DSP TC1 or GOES 12. That is, the so-called “growth phase” is a preferable condition for both pseudo-breakup and plasma sheet oscillations in the near-Earth magnetotail. One of the plasma sheet oscillation events occurs before the pseudo-breakup, whereas the other takes place after pseudo-breakup. Thus there is no causal relationship between the plasma sheet oscillation events and pseudo-breakup. As for the contribution to the subsequent small substorm, the onset of the small substorm took place where the preceding plasma sheet oscillations can reach the region.     

Buckling and post-buckling behavior of shallow supported cylindrical panels

The problem of the post-buckling behavior of the supported cylindrical panel under uniform axial compression is solved. The cylindrical supported panel is considered as a beam on the Winkler elastic foundation, the stiffness coefficient of which is calculated at the known value of buckling load. The criteria for post-buckling estimation are introduced, namely, vanishing of the determinant of the resolving system of equations and going to infinity of the deflection and strain energy in the implementation of post buckling. A good agreement of the post-buckling load obtained in this work with the experimental results is shown.     

Fault diagnostics and fault tolerant control

A novel simultaneous fault detection and diagnostics (FDD) and fault tolerant control (FTC) strategy for nonlinear stochastic systems in closed loops based on a continuous stirred tank reactor (CSTR) is presented. The purpose of control is to track the reactant concentration setpoint. Instead of output feedback we propose here to use proportional-integral-derivative (PID) state feedback, which is shown essential to achieve FTC against sensor faults. A new concept of “equivalent bias” is proposed to model the sensor faults. Both the states and the equivalent bias are on-line estimated by a pseudo separate-bias estimation algorithm. The estimated equivalent bias is then evaluated via a modified Bayes' classification based algorithm to detect and diagnose the sensor faults. Many kinds of sensor faults are tested by Monte Carlo simulations, which demonstrate that the proposed strategy has definite fault tolerant ability against sensor faults, moreover the sensor faults can be on-line detected, isolated, and estimated simultaneously     

Electric Charging and Discharging Processes of Moving Projectiles

Every type of missle is electrically charged during free flight. The physical mechanism, leading to the electric charging and discharging effects, was investigated by measuring the electric field surrounding projectiles while leaving the muzzle region, during free flight, and on impact on targets. The electric charge on projectiles is 10-13 108C. Numerous experimental results were obtained with calibers 4-155 mm and velocities 50-120lm/ s. A physical model about the complex charging effects is derived.