Reference crop evapotranspiration (ET0) is a key to estimate crop water requirements, and also an important component of irrigation schedule and water resources planning, sensitivity analysis are crucial in assessing the impact of climate changes inET0estimations. In this study, based on the daily meteorological data of 18 meteorological stations in Shanxi Province from 1961 to 2000, the dailyET0values were calculated using Penman-Monteith equation recommended by FAO-56. The trends of climate variables were detected by using Mann-Kendall test. Sensitivity coefficients were employed to predict responses ofET0to five climatic variables, combined with annual of meteorological factors quantitative analysis ofET0changes. The results show that statistically significant decreasing trends are observed in wind and daily sunshine hours in Guanzhong and southern Shaanxi. Relative humidity has a significant decreasing trend in northern Shaanxi. In general,ET0value is on the decline; relative humidity is the most sensitive variable, followed by solar radiation, daily sunshine hour, wind speed and mean temperature. The change ofET0is primarily attributed to the significantly decreasing in wind speed and sunshine hour.
When a robot is used to polish or finish a curved surface, both feed movement and contact force have to be controlled at the same time so that the polishing tool would machine its work-piece at the right position in right posture with required force. In this paper, a passive wrist system is developed to adapt the shape of the machining curved surface by changing its posture along with the surface. And under the Fuzzy-PID policy, polishing force is controlled at a stable value in the normal direction of the named machining point while the polishing tool moving along the curved surface by multi-point machining. It means that the passive wrist system and the model of the surroundings could be used in force controlling when robots polish free-form surfaces with multi-point machining by a grinding ring.
First it sets up a kinematical model for a kind of industrial robots by D-H notation, and inverse kinematics solutions of its end effector are deduced according to its motion trail. By transforming the rotation angles of the robot’s joints into impulse signals, pulse signals could be used to interpolate its motion trail. Finally, it uses Matlab software to join various curve of each joint impulse signal, and formulation a mathematical model about various curve of each joint impulse signal. In this way, it could simplify program in INFORM Ⅲ language. Simulation shows that direct pulse signal interpolation improves the accuracy of trajectory positioning.
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