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Ecosystem carbon use efficiency (CUE) is a key parameter in the carbon cycling of terrestrial ecosystems. The magnitude of CUE reflects the ecosystem's potential for CO2 sequestration. China's grasslands play an important role in the carbon cycle. Here, we aimed to investigate the comparation of CUE and its environmental regulation among different grassland in Northern China based on eddy covariance carbon fluxes measurements of 31 grassland sites. The results showed that the average CUE of grassland in Northern China was 0.05 ± 0.22, with a range from −0.42 to 0.66. It was demonstrated that there were significant differences in CUE among different grassland types, and CUE values were ranked by type as follows: alpine grassland > temperate meadow steppe > temperate typical steppe > temperate desert steppe, driven by a combination of climatic, soil, and biological factors, with net ecosystem productivity (NEP) having the greatest impact on them. Except for meadow steppes, moisture had a greater impact on grassland CUE in Northern China than temperature. While temperate desert grassland CUE decreased with increasing soil water content (SWC), the CUE of other grassland types increased with higher precipitation and SWC. These findings will advance our ability to predict future grassland ecosystem carbon cycle scenarios. [ABSTRACT FROM AUTHOR]

The maximum load of wing and fuselage increases sharply while flapping-wing micro air vehicles(FWMAVS) flutters at high frequencies, which seriously affect the flight performance and flight life. The mathematical models of wing lift, drag and inertial forces during the FWMAVs fluttering are established, based on the analysis of movement and force conditions of the wing. A multi-objective optimization model targeting at improving the distribution of loads in the time domain is then proposed and solved by using NSGA-Ⅱ algorithm in Matlab environment. After all the work, the Pareto optimal solution set of the hovering state is obtained. Comparison and analysis of the data show that after the optimization, the peaks of lift and inertial forces decline significantly and the load distribution is obviously improved.

As a special type of micro ornithopter, the coaxial quad-wing flapper (CQWF) enables greater flight speed and higher stability than the paired-wing flapper. These characteristics are closely related to the unique pneumatic mechanism of the CQWF. Therefore, the aerodynamic generation mechanism of the CQWFs has been actively researched in recent years. This study verifies the reliability of flow-field simulations in a CQWF prototype with an aerodynamically optimized driving mechanism. For the selected motion parameters and shape dimensions of the flapping-wing aircraft, the vorticity fields at different elevation angles are observed in flow-field simulations. The elevation angle strongly affects the lift. Moreover, the wing movement based on the Clap–Fling mechanism significantly affected the acquisition of the lift, which explains the higher stability of the CQWF than that of the paired-wing flapper and provides a theoretical basis for the optimization of the flapping prototype. When tested on a wind-tunnel platform, the prototype yields slightly higher lift compared with those obtained in the simulation study. In addition to confirming the phenomenon revealed in flow visualization, it also showed that the unsteady mechanism of the two-pair wing is more powerful than calculated. [ABSTRACT FROM AUTHOR]

A new device architecture, dubbed elevated-metal–metal-oxide (EMMO) thin-film transistor (TFT), is presently proposed. During a heat-treatment process in oxygen, conductive source and drain regions spontaneously populated by donor defects are formed, while the defects in the channel region are simultaneously passivated. Compared with that of the conventional back-channel-etched TFT, this architecture inherently accommodates an etch-stop/passivation layer without increasing the mask count. EMMO TFT demonstrated using indium–gallium–zinc oxide as an active layer exhibited good performance metrics: a peak field-effect mobility of \sim 14 cm2/Vs, a steepest pseudo-subthreshold slope of \sim 120 mV/decade, a leakage current lower than \sim 10^-14 A, an on/off -current ratio above \sim 10^10 , and stability against environmental and electrical stress. [ABSTRACT FROM PUBLISHER]

The characteristics of metal-oxide-based thin-film transistors (TFTs) are known to have strong relations with the thermal processes they have gone through. Particularly, the resistivity of the indium-gallium-zinc-oxide (IGZO) film is sensitive to the annealing atmosphere, temperature and cover permeability. A new way of modulating turn-on voltage (Von) was proposed by controlling the annealing processes of TFT. The devices will change from enhancement mode to depletion mode with negative Von shift of several volts if they are annealed in nitrogen (N2), due to the decreased channel resistivity. And such shift can be recovered in an oxidizing annealing. Considering the absence of high performance p-type metal-oxide TFTs, this new method can be used to construct logic circuit based on enhancement and depletion mode n-type TFTs, exhibiting great potential in assembling system-on-panel application. [ABSTRACT FROM AUTHOR]