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The study aimed at investigating the addition effects of P, K, and micronutrient fertilizers on the permeability of N-nutrient fertilizer urea through a representative polymer membrane, which is of great importance in polymer-coated compound fertilizer. Specifically, the permeability of urea through polystyrene membrane was determined experimentally at the nominal temperature of 298 K using the Ussing chamber method for fertilizer solutions of urea-water, urea-NaH 2 PO 4 -water, urea-Ca(H 2 PO 4 ) 2 -water, urea-KCl-water, and urea-NaCl-water. The experimental data showed that the addition effects of NaH 2 PO 4 , KCl, and NaCl on urea permeability were pronounced and could be promotion or suppression depending on the amounts added. The variation of urea permeability with additive concentration could be explained by the 'solution-diffusion' model, suggesting that the specific intermolecular and interionic interactions in the permeation solution were an important factor determining the permeability. Using the saturated urea-water solution as basis, the addition of saturated KCl increased the urea permeability by 2.5 times, while the addition of saturated Ca(H 2 PO 4 ) 2 and NaH 2 PO 4 decreased the permeability by 41% and 76%, respectively.

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Rehabilitation robots can help physiatrists to assist patients in improving their movement ability. Due to the interaction between rehabilitation robots and patients, the robots need to complete rehabilitation training on a safe basis. This paper presents an approach for smooth trajectory planning for a cable-driven parallel waist rehabilitation robot (CDPWRR) based on the rehabilitation evaluation factors. First, motion capture technology is used to collect the motion data of several volunteers in waist twisting. Considering the impact of motion variability, the feature points at the center of the human pelvis are obtained after eliminating unreasonable data through rationality judgments. Then, point-to-point waist training trajectory planning based on quintic polynomial and cycloid functions, and multipoint waist training trajectory planning based on quintic B-spline functions are carried out. The corresponding planned curves and kinematics characteristics using three methods are compared and analyzed. Subsequently, the rehabilitation evaluation factors are introduced to conduct smooth trajectory planning for waist training, and the waist trajectory with better compliance is obtained based on the safety and feasibility of waist motion. Finally, the physical prototype of the CDPWRR is built, and the feasibility and effectiveness of the proposed smooth trajectory planning method are proved by numerical analysis and experiments.