Mechanism of Locust Air Posture Adjustment

Stimulated locusts often tumble during the jumping process. Locusts can also recover their bodies in the air for flight or landing stability. To increase jumping distance and avoid landing collision of bio-inspired jumping robots, the mechanism of air posture adjustment of locusts is examined in this research. This mechanism can be used to improve the stability of robot. The abdomen swings, wing motions, and the variations in body angle are recorded by a high-speed camera when locusts free fall in air with normal or upside-down initial posture. Results indicate that the wings and abdomen are mainly utilized for air posture adjustment. Moreover, abdomen swing and forewing rotation have positive effects on body pitch. However, locusts have dif- ficulty in recovering their bodies from the upside-down posture without wings, although the body pitch caused by unpredictable perturbation in air can be compensated through abdomen swing. Consequently, body roll is attributed to the wing motion, which is related to two factors, namely, the different flapping amplitudes of the wings on both sides, and the different flapping velocities of wings during the upstroke and downstroke periods. This research may provide reference for the design of jumping robots.

Restoration of hyper-eutrophic water with a modularized and air adjustable constructed submerged plant bed

A modularized and air adjustable constructed submerged plant bed(CSPB)which can be used to restore the eutrophic water is introduced in this paper.This plant bed helps hydrophyte grow under poor conditions such as frequently changed water depth,impaired water transparency,algae bloom and substantial duckweed in summer,which are not naturally suitable for growing hydrophyte.This pilot study in Waihuan River of Tianjin,China,revealed that reduction of Chemical Oxygen Demand(COD),Total Nitrogen(TN)and Total Phosphorus(TP)by the use of CSPB could be reached 30%-35%,35%-40%,30%-40%respectively in the growing season(from March to October)and 5%-10%,5%-15%,7%-20%respectively in the winter(from November to February)when the detention time was 6 d.The relationships between the concentration of COD,TN,TP and the detention time fit the first-order kinetic equation well and the coefficients of determination(R^(2))were all above 0.9.The attenuation coefficients k of the kinetic equation were a function of the water temperature.When the water temperature was quite low or quite high,k was not significantly changed with increasing or decreasing water temperature.While when the temperature was in a moderate range,an increase or decrease of water temperature would lead to a rapid increase or decrease in k.