Passive control is the addition of a small object to an object to reduce the drag force of the object. This study focuses on three passive controls. Numerically, the problem of three passive controls for drag reduction of circular cylinder is studied. In this case, three passive controls are placed in front of and in the rear of the main object. A passive control type-I is in front of circular cylinder while the others are in rear. The distance of the passive controls is varies to the circular cylinder. In this study, we want to find an effective distance of the main object to three passive controls from the shape and the angle position of the passive controls.

The ionospheric diurnal variation from TEC Global Ionospheric Maps (GIM) data at the epicenter coordinates of the Lombok earthquake on July 29 2018 (-8.4°, 116.5°) has been analyzed using harmonic function which is the sum of the sine and cosine functions with estimated harmonic coefficients obtained using Kalman Filter (KF) method. The initial value of the estimated KF method was obtained from Least Square Estimation (LSE) on the first day data. The estimated TEC value by the KF method shows that there are seasonal variations of the peak values of diurnal variations which is a result of variation in the zenith angle of the sun that change over a year with peaks in March and November in the equator. The results of the first-order harmonic amplitude analysis, namely the diurnal TEC variation (A24) which is the root value of the sum of the squared values of the A1 and B1 coefficients were further analyzed by estimating polynomials with order 17 to eliminate the seasonal effect on A24. The difference in value of A24 from its estimation with order 17 polynomial (delta A24) shows the influence of geomagnetic and seismic activity. A24 analysis based on solar radiation flux at wavelength 10.7 cm (F10.7) does not indicate a strong influence or relationship> Equatorial geomagnetic disturbance index (etc.) shows the influence of geomagnetic storms on diurnal amplitude and earthquake data around Lombok indicating symptoms of pre-earthquake that affects the ionospheric TEC through a decrease in diurnal amplitude a few days before the earthquake.