Electro hydraulic drives are often used where the dynamic response requirements of the driven load in terms of speed, cycling, accuracy and stability are particularly severe. One such application is the control and drive system associated with a high frequency hydraulic vibrator. A hydraulic shaker controls a valve which directs high pressure hydraulic fluid to generate controlled vibration. Hy...

In order to optimize the design method and improve the performance of hydraulic retarder, the numerical simulation of multi-field coupling of heat, fluid and solid is carried out to hydraulic retarder, based on the numerical computation and algorithm of heat-fluid coupling and fluid-solid coupling. The computation models of heat-fluid coupling and fluid-solid coupling of hydraulic retarder are ...

Measurement uncertainty is a key hindrance to the quanti_cation of water ~uxes at all scales of investigation[ Predictions of soil!water ~ux rely on accurate or representative measurements of hydraulic gradients and _eld! state hydraulic conductivity[ We quanti_ed the potential magnitude of errors associated with the parameters and variables used directly and indirectly within the DarcyÐBucking...

Hydraulic fracturing technology is usually used to stimulate tight gas reservoirs for increasing gas production. The stimulated volume depends in part on the pre-existing natural fractures in a reservoir. The mechanisms influencing the interaction between hydraulic fractures and natural fractures have to be well understood in order to achieve a successful application of hydraulic fracturing. In...

To solve the technical problems in controlling surrounding rock of gob-side entry retaining deep and close distance coal seams under goaf, deformation failure characteristics goaf were analyzed this paper. Basic support inside roadway high-strength prestressed wire meshes, beam cable anchor, reinforcement single hydraulic with hinged roof roadside high-water material filling structure proposed....

The main goal of the study is to analyze all relevant properties of the electro hydraulic systems and based on that to make a proper choice of the control strategy that may be used for the control of the servomechanism system. A combination of electronic and hydraulic systems is widely used since it combines the advantages of both. Hydraulic systems are widely spread because of their properties...

The paper aims to develop a novel pitch control system for a large wind turbine driven by a variable-speed pump-controlled hydraulic servo system. To perform practical pitch control experiments, a full-scale test rig of the hydraulic pitch control system for a 2 MW wind turbine’s blade, including a novel pitch control mechanism, a variable-speed pump-controlled hydraulic servo system, a disturb...

A theoretical method is proposed to estimate post-fracturing fracture size and transmissivity, and as a test of the methodology, data collected from two wells were used for verification. This method can be employed before hydrofracturing in order to obtain estimates of the potential hydraulic benefits of hydraulic fracturing. Five different pumping test analysis methods were used to evaluate th...

Stochastic modeling of soil water fluxes in the absence of measured hydraulic parameters requires a knowledge of the expected istribution of the hydraulic parameters in different soil types. Predictive relationships describing the hydraulic parameter distributions must be developed based on the common descriptors of the physical properties of soils (e.g., texture, structure, particle size distr...