First investigation of eclipsing binary KIC 9026766: analysis of light curve and periodic changes

We investigate a short-period W UMa binary KIC 9026766 with an orbital period of 0.2721278d in the Kepler field of view. By applying an automated q-search for the folded light curve and producing a synthetic light curve for this object based on the PHOEBE code, we calculate the fundamental stellar parameters. We also analyze the O − C curve of the primary minima. The orbital period changes can be attributed to the combination of an upward quadratic function and light-travel time effect (LTTE) due to a possible third body with a minimum mass of 0.029 M ⊙ and an orbital period of 972.5866 ±0.0041d. The relative luminosity of the primary and secondary eclipses (Min I − Min II) is calculated. The periodogram of the residuals of the LTTE and Min I − Min II show peaks with the same period of 0.8566d. The background effect of two nearby stars on our target is the possible reason for this signal. By considering the amplitudes and periods of the remaining signals in the O − C curve of minima, spot motion is possible.

Developing a Low-Cost Force Treadmill via Dynamic Modeling

By incorporating force transducers into treadmills, force platform-instrumented treadmills (commonly called force treadmills) can collect large amounts of gait data and enable the ground reaction force (GRF) to be calculated. However, the high cost of force treadmills has limited their adoption. This paper proposes a low-cost force treadmill system with force sensors installed underneath a standard exercise treadmill. It identifies and compensates for the force transmission dynamics from the actual GRF applied on the treadmill track surface to the force transmitted to the force sensors underneath the treadmill body. This study also proposes a testing procedure to assess the GRF measurement accuracy of force treadmills. Using this procedure in estimating the GRF of “walk-on-the-spot motion,” it was found that the total harmonic distortion of the tested force treadmill system was about 1.69%, demonstrating the effectiveness of the approach.