Xiangzhou Zheng

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To investigate the fate of urea nitrogen (N) applied to vegetable fields, three N rates, N0 (0 kg N/ha), N1(225 or 240 kg N/ha) and N2 (450 or 480 kg N/ha) were applied to a rotation system. Nitrogen fertilizer recovery (NFR), N residue in soil, and N losses were measured in situ. Higher N application rates resulted in lower NFR, and increased N residues in(More)
Statics of rotational 3-UPU parallel mechanisms (PM) based on principle of virtual work is presented in this paper. The rotational 3-UPU PM is made up of a fixed base and a movable platform interconnected by three identical UPU type limbs, where U and P stand for universal and prismatic joint respectively, and platform can only change its orientation(More)
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