This paper describes the development of linear parameter varying (LPV) models and an LPV-H∞ controller for one degree of freedom (DoF) electro-hydraulic systems. A virtual set-up consists of a hydraulic actuator driven by a servovalve and supplied from a constant-pressure power unit. The LPV models are derived based on two techniques: black-box modeling and the analytical description of the sys...

Surface area of root (m-2) Concentration of solutes (osmolal) Average solute concentration between inside and outside of root Diameter Diffusion coefficient (m2 s-l) Mass flow of solution (kg s-l) Classical root hydraulic conductance (kg s-I MPa-l) Mass flux density or Fm per unit root surface area (kg s-I m-2) Solute flux density (mol s-I m-2) Thermodynamic root hydraulic conductance (kg s-I M...

The recently developed Unconventional Fracture Model (UFM*) simulates complex hydraulic fracture network propagation in a formation with pre-existing closed natural fractures, and explicitly models hydraulic injection into a fracture network with multiple propagating branches [1]. The model predicts whether a hydraulic fracture front crosses or is arrested by a natural fracture it encounters, w...

Power head with high power and large torque is the main power equipment of the rotary drilling rig. Aimed at the working condition, energy saving torque loading test program of power head was put forward and mathematical and simulation models of hydraulic energy closed-loop torque loading system were established. Combined with bond graph and state equations of torque loading system with single ...

Based on the theory of hydraulic transients and the method of characteristics (MOC), a mathematic model of the differential surge tank with pressure-reduction orifices (PROs) and overflow weirs for transient calculation is proposed. The numerical model of hydraulic transients is established using the data of a practical hydropower station; and the probable transients are simulated. The results ...

A passivity framework for hydraulic actuators is developed by consideration of the compressibility energy function for a fluid with a pressure dependent bulk modulus. The typical actuator’s mechanical and pressure dynamic model is shown to be the Euler-Lagrange equations for this energy function. A passivity property for the actuator is exhibited in which the hydraulic supply rate contains the ...

in this study, hydraulic properties of low pressure drip irrigation systems were studied under laboratory conditions and using of the pipes that exist in iran. therefore, effect of various heads from 0.45 to 1.8m was evaluated for lateral pipe with outside diameter 32mm and length of 16, 30, 60 and also the lateral pipe with length 16 and outside diameter of 16, 20, 25 and 32mm, on hydraulic ch...

Trees face the dilemma that achieving high plant productivity is accompanied by a risk of drought-induced hydraulic failure due to a trade-off in the trees' vascular system between hydraulic efficiency and safety. By investigating the xylem anatomy of branches and coarse roots, and measuring branch axial hydraulic conductivity and vulnerability to cavitation in 4-year-old field-grown aspen plan...

A better understanding of the mechanistic basis of stomatal control is necessary to understand why modes of stomatal response differ among individual trees, and to improve the theoretical foundation for predictive models and manipulative experiments. Current understanding of the mechanistic basis of stomatal control is reviewed here and discussed in relation to the plant hydraulic system. Analy...

hydraulic fracturing in the fractured reservoirs plays a significant impact on the production rate. in this study, the hydrostatic condition is taken into account, the hydraulic fracturing operation was applied in every direction usinga written distinct element code. in each direction the hydraulic fracture is applied with different lengths and in each level the amount of production is predicte...