A Reverse Path Planning Approach for Enhanced Performance of Multi-Degree-of-Freedom Industrial Manipulators

In the domain of autonomous industrial manipulators,precise positioning and appropriate posture selection in path planning are pivotal for tasks involving obstacle avoidance,such as handling,heat sealing,and stacking.While Multi-Degree-of-Freedom(MDOF)manipulators offer kinematic redundancy,aiding in the derivation of optimal inverse kinematic solutions to meet position and posture requisites,their path planning entails intricate multiobjective optimization,encompassing path,posture,and joint motion optimization.Achieving satisfactory results in practical scenarios remains challenging.In response,this study introduces a novel Reverse Path Planning(RPP)methodology tailored for industrial manipulators.The approach commences by conceptualizing the manipulator’s end-effector as an agent within a reinforcement learning(RL)framework,wherein the state space,action set,and reward function are precisely defined to expedite the search for an initial collision-free path.To enhance convergence speed,the Q-learning algorithm in RL is augmented with Dyna-Q.Additionally,we formulate the cylindrical bounding box of the manipulator based on its Denavit-Hartenberg(DH)parameters and propose a swift collision detection technique.Furthermore,the motion performance of the end-effector is refined through a bidirectional search,and joint weighting coefficients are introduced to mitigate motion in high-power joints.The efficacy of the proposed RPP methodology is rigorously examined through extensive simulations conducted on a six-degree-of-freedom(6-DOF)manipulator encountering two distinct obstacle configurations and target positions.Experimental results substantiate that the RPP method adeptly orchestrates the computation of the shortest collision-free path while adhering to specific posture constraints at the target point.Moreover,itminimizes both posture angle deviations and joint motion,showcasing its prowess in enhancing the operational performance of MDOF industrial manipulators.

Reinforcing Paper Strength by Dual Treatment of a Cationic Water-soluble Polymer and Cellulose Nanofibril

Cellulose nanofibril(CNF)was used as the anionic component of two dual strengthening systems wherein polyamidopolyamine epichlorohydrin resin(PAE)or cationic starch(CS)was used as the cationic component.Their strengthening effects were investigated for lowbasis-weight(30 g/m2)paper composed of a mixture of fully bleached softwood and hardwood pulp in a 4:1 mass ratio.Using the PAE/CNF or CS/CNF dual system,it was generally easier to achieve higher wet and dry tensile strengths of paper compared to the paper using the single PAE or CS system.For example,the paper using the PAE(0.4%)/CNF(0.3%)dual system exhibited 89%higher wet tensile strength than the paper using the single PAE(0.4%)system,and the paper using CS(1.3%)/CNF(0.3%)dual treatment showed 21%higher dry strength than that using the single CS(1.3%)system.However,the PAE/CNF system only showed small improvement in the dry strength of paper(11%higher than that of paper using the single PAE system),so did the CS/NFC system on wet strength improvement(only 17%higher than that of paper using the single CS system).

Effect of Farmyard Manure Application on Dissolution of Carbonate Rocks and Its Eco-environmental Impact

A much improved understanding of how farmyard manure application may affect carbonate rock dissolution is needed in order to predict possible feedbacks between the rock carbon cycle and the global climate system. Two carbonate mineral rock tablets; dolomite and limestone were buried at six depths between 0 and 110 cm in a soil typical of the subtropical karst area in Guiyang City, Guizhou Province. The extent of tablet dissolution, soil CO2, soil p H, soil water content, soil mineral and chemical composition, and chemical composition of soil water were tested in order to assess the degree of dissolution under manure application over the course of one year. The results show that manure addition decreases the dissolution rate of carbonate rocks; limestone and dolomite by between 11.7%-116.9% and 25.0%-65.69% respectively, with the dissolution rate of limestone consistently exceeding that of dolomite under the same conditions. Our data indicates that the rate of pedogenesis of the dolomite and limestone rocks is decreased as much as 35.77% and 59.41% respectively, as a result of manure application. Moreover, the results suggest that manure application accelerated the generation of soil CO2, with soil CO2 concentration increasing on average by 93.94%, and the CO2 flux increasing by 67.64% compared with the control profile. Finally, the data also indicates that manure decreases CO2 uptake by dissolution of carbonate rocks by 25.50%-39.45% on a Guiyang city scale. The counteraction of the CO2 sink contributed by karst water due to farmyard manure utilization in general karst area（both dolomite and limestone） however was 59.41%-62.72%, indicating the application of manure successfully reduces both dissolution and CO2 release to the atmosphere.

Estimating the effect of shallow groundwater on diurnal heat transport in a vadose zone

The influence of shallow groundwater on the diurnal heat transport of the soil profile was analyzed using a soil sensor automatic monitoring system that continu- ously measures temperature and water content of soil profiles to simulate heat transport based on the Philip and de Vries （PDV） model. Three experiments were conducted to measure soil properties at depths of 5 cm, 10 cm, 20 cm, and 30 cm when groundwater tables reached l0 cm, 30 cm, and 60 cm （Experiments I, II, and III）. Results show that both the soil temperature near shallow groundwater and the soil water content were effectively simulated by the PDV model. The root mean square errors of the temperature at depths of 5 cm, 10 cm, and 20 cm were 1.018℃, 0.909℃, and 0.255℃, respectively. The total heat flux generated the convergent and divergent planes in space-time fields with valley values of-161.5 W-m 2 at 7：30 and -234.6 W.m2 at 11：10 in Experiments II and III, respectively. The diurnal heat transport of the saturated soil occurred in five stages, while that of saturated-unsaturated and unsaturated soil profiles occurred in four stages because high moisture content led to high thermal conductivity, which hastened the heat transport.

Experimental study of the effect of shallow groundwater table on soil thermal properties

In plains areas with semi-arid climates, shallow groundwater is one of the important factors affecting soil thermal properties. In this study, soil temperature and water content were measured when groundwater tables reached 10 cm, 30 cm, and 60 cm depths （Experiment I, II, and III） by using sensors embedded at depths of 5 cm, 10 cm, 20 cm, and 30 cm for 5 days. Soil thermal properties were analyzed based on the experimental data using the simplified de Vries model. Results show that soil water content and temperature have fluctuations that coincide with the 24 h diurnal cycle, and the amplitude of these fluctuations decreased with the increase in groundwater table depth. The amplitude of soil water content at 5 cm depth decreased from 0.025 m^3·m^-3 in Experiment II to 0.01 m^3·m^-3 in Experiment III. Moreover, it should be noted that the soil temperature in Experiment III gradually went up with the lowest value increasing from 26.0℃ to 28.8℃. By contrast, the trends were not evident in Experiments I and II. Results indicate that shallow groundwater has a ＂cooling＂ effect on soil in the capillary zone. In addition, calculated values of thermal conductivity and heat capacity declined with the increasing depth of the groundwater table, which is consistent with experimental results. The thermal conductivity was stable at a value of 2.3 W.cm^-1·K^-1 in Experiment I. The average values of thermal conductivity at different soil depths in Experiment II were 1.82 W.cm^-1·K^-1, 2.15 W.cm^-1·K^-1, and 2.21 W. cm^-1·K^-1, which were always higher than that in Experiment III.