Gongcheng Kexue Yu Jishu/Advanced Engineering Science

As the basic part of motion of humanoid robots, human-like motion planning of the anthropomorphic arm is always one of the research hotspots and difficulties. A novel human-like motion planning method based on movement primitives was proposed. This method can satisfy the feature of arm motion and improve the accuracy. Firstly, the arm structure was decoupled and the arm model was built to express different arm movements. The methods of extraction and connection about movement primitives were established. The mapping relations between the arm models and inverse kinematic (IK) solutions were established. Meanwhile, a motion framework was proposed. The joint trajectories of a certain platform can be generated to accomplish required tasks with this motion framework. Secondly, according to the motion features of different movement primitives, the associated Human Performance Measures for different movement primitives were constructed to solve the IK problem. Finally, the proposed method was verified by the similarity experiment and the human-like movement experiment for the general motion of humanoid robot NAO. In the similarity experiment, the robot NAO generated the human-like movements with the proposed method. The motion data were compared with the real data generated by humans. All the errors were less than 1 cm, which satisfied the accuracy requirements of human-like movements. In the human-like movement experiment, the robot NAO performed a human-like arm movement with the proposed method. The proposed method was also compared with the minimum total potential energy method and the last norm algorithm. Using the proposed method, 7% and 58 % increase in similarity were achieved respectively, compared with those two methods. With the proposed method, the complex motion models were decoupled into different simple sub-movements and the classification of the movements reduced the calculation amount. The experiments proved that the anthropomorphic arm can generate human-like movements accurately.

Industrial and agricultural activities lead to increasing soil cadmium (Cd) pollution. As an important functional component of soil colloid, both montmorillonite (Me) and humic acid (HA) have good adsorption properties for Cd. Four molecular weight grades of HA were obtained by tangential flow ultrafiltration. FTIR, element determination, functional group titration were used to study the effect of HA with different molecular weight on the adsorption of Cd on montmorillonite and the mechanism of action. The results showed that with the increase of molecular weight of HA, the content of hydroxyl and carboxyl groups decreased while the phenolic hydroxyl group and methyl group increased, the aromaticity increased, the hydrophobicity became stronger, and the pH value increased. The contents of Cd and HA adsorbed by montmorillonite in the ternary system increased with the increase of molecular weight. When the initial concentration of Cd was 50 mg/L, the adsorption capacity of HA, HA1, HA2, HA3, HA4 montmorillonite system for Cd was 1.99, 2.11, 2.46, 4.12, 4.88 mg/g, respectirely. And the Cd adsorbed under the action of each molecular weight HA was mainly reducible state. The smaller HA was easier to compete for the adsorption of the Cd already bound on the surface of montmorillonite, and due to its strong hydrophilicity, the Cd adsorbed by small HA would be brought into the solution, reducing the content of Cd absorbed by the system. With the increase of molecular weight, its competition effect with montmorillonite was reduced, and the HA was difficult to enter into the montmorillonite layers. At this time, under the hydrophobic effect, the large molecule HA adsorbed Cd would cover the surface of montmorillonite, thus increasing the adsorption amount of Cd in the system.

The composite strengthening method with near surface mounted steel bars and wrapped fiber reinforced polymer strips can improve the bearing capacity and deformation behavior of timber columns effectively, and enhance their working performance greatly. To propose the load-bearing capacity formula of short timber columns strengthened with near surface mounted steel bars and wrapped carbon fiber reinforced polymer (CFRP) strips, a total of 42 reinforced specimens (12 groups) were tested under axial compression. The test results indicated that the failure of timber columns mainly occurred where the initial defects concentrated , and the bearing capacity and deformation performance of timber columns could be improved through the composite strengthening, showing significant strengthening effectiveness.Based on the typical strength model of concrete columns wrapped with fiber reinforced polymer strips, three strength models of timber columns with wrapped CFRP strips by analyzing and fitting the relevant experiment data were proposed. Through the comparison between theoretical and test values, the feasible strength model for the calculation of timber columns confined by CFRP strips was selected, and then the calculation formula of bearing capacity for the circular timber columns with composite reinforcement method was obtained. According to the additional experiment results and the comparison calculation for test data in existed research, it can be obtained that the theoretical calculation was able to predict the test results,which verified the reliability of the formula for the calculation of the strengthened timber columns' load-bearing capacity.

A water–soil coupling model of channel fluid movement is established considering the interaction of gully bed erosion, slope confluence, and rainfall, which can provide theoretical basis for watershed risk assessment, disaster prevention and mitigation, and identification of potential debris flow gully. By analyzing the erosion process of the channel fluid on the movable solid source of the gully bed, and coupling it with the slope confluence and the rainfall over the channel with temporal and spatial variability, the water–soil coupling model of the channel fluid movement in the small watershed can be established. The finite difference method was used to discretize the water–soil coupling model of fluid movement in time and space. A computer code for the coupling model of fluid motion was written in MATLAB. Meanwhile, laboratory experiments were carried out with varying flow rates and groove slopes to observe the evolution of fluid flow depth, flow velocity and fluid bulk density under different working conditions. By analyzing the results of the 12 sets of experiments, it was found that under the condition that the slope of the groove remains unchanged, the fluid flow depth and the fluid velocity were positively correlated with the flow and the bulk density was negatively correlated with the flow. At the same time, the numerical simulation results of the fluid flow depth, flow velocity and fluid bulk density at the control point of the groove were compared to and analyzed with the experimental results. It was found that the simulation accuracy of the fluid flow velocity and fluid bulk density were higher than 90%, and the simulation accuracy of the fluid flow depth was higher than 80%. The results revealed that the established water–soil coupling model of the channel fluid movement in the small watershed is accurate.

The base isolation structure has a high requirement for integrity of the isolation layer, and the connection behavior of the isolation layer members affects the integrity and the seismic behavior of the isolation layer directly. In this paper, the welding connection mode between longitudinal reinforcements at the bottom of the beam was improved, the tensile tests were also carried out, and a new frame joint was proposed of the isolation layer for prefabricated concrete base isolation structure. Then, the finite element models of the new frame joint and traditional cast-in-place joint were established to simulate the seismic behavior and the structural integrity under the lateral repeated loads in ABAQUS. Finally, an improved connection mode for the new frame joint was proposed by comparing the difference of seismic behavior between the two kinds of joints. The results showed that the tensile strength of the specimen which connected by grooving and welding on the steel plate was close to that of the complete reinforcement, and could significantly reduce the bending deformation of the connecting steel plate. The bearing capacity, stiffness and energy dissipation capacity of the prefabricated frame joint were lower than that of the cast-in-place joint, but the deformation capacity was stronger. The bearing capacity, stiffness, and deformation capacity of the new frame joint on the prefabricated isolation layer increased when some anchored rebars were added to the ends of the prefabricated beam, the reinforcement ratio at the end of beams also increased, at the same time, the plastic development of the longitudinal reinforcement was delayed by the anchored rebars, so the energy dissipation capacity decreased. The load-bearing capacity, stiffness and deformation capacity of the improved prefabricated frame joint were all stronger than that of cast-in-place joint, so the improved new frame joint had an excellent structural integrity, and it could be used in practical engineering widely.