We discuss efficient solutions to systems of shifted linear systems arising in computations for oscillatory hydraulic tomography (OHT). The reconstruction of hydrogeological parameters such as hydraulic conductivity and specific storage, using limited discrete measurements of pressure (head) obtained from sequential oscillatory pumping tests, leads to a nonlinear inverse problem. We tackle this...

Hydraulic support is the main supporting equipment of the coal mining systems, and they are usually subjected to fatigue failure under the high dynamic load. The fracture positions are generally at welded joints where there is a serious stress concentration. In order to investigate and further improve the fatigue strength of hydraulic support, the present work first located the possible positio...

The moving process of a leveling and erecting mechanism is complicated, which involves six hydraulic cylinders. The research established mathematical model and optimized the moving process of the leveling and erecting mechanism. Kinematic analysis of the mechanism was accomplished. Mathematical model of the hydraulic system was established. Working scheme was designed consisting of workflow, tr...

Swelling of clay-sulfate rocks is a major threat in tunneling. It is triggered by the transformation of the sulfate mineral anhydrite into gypsum as a result of water inflow in anhydrite-containing layers after tunnel excavation. The present study investigates the hydraulic effects of tunneling on groundwater flow and analyzes how hydraulic changes caused by excavation lead to water inflow into...

In this paper, the hydraulic and heat-transfer properties of two sets of artificially fractured granite samples are investigated. First, the morphological information is determined using 3D modelling technology. The area ratio is used to describe the roughness of the fracture surface. Second, the hydraulic properties of fractured granite are tested by exposing samples to different confining pre...

Hydraulic cylinder actuators are used extensively in industrial, construction and agricultural works. The small sized outlet ports of the cylinders resist the flow of discharged oil; and as a result the piston motion is slowed down. This causes a lot of heat generation and energy loss within the actuators. The study investigates and analyzes the possibilities of reducing the hydraulic resistanc...

Karst topography is a special landscape shaped by the dissolution of one or more layers of soluble bedrock, usually carbonate rock such as limestone or dolomite. Due to subterranean drainage, overland flow, extraction of water by plants and evapotranspiration, there may be very limited surface water. The hydraulic architecture that plants use to adapt to karst topography is very interesting, bu...

1 Abstract The paper presents a hydraulic astable multivibrator system. The system consists of hydraulic resistors, hydraulic capacitors and hydraulic pressure controlled valves. The system is designed, realised and tested. The measured system behaviour agrees well with the model simulations. The free running frequency of the multivibrator is 0.18 Hz and the output pressure swing is 90% of the ...

Hydraulic excavator energy saving is important to relieve source shortage and protect environment. This paper mainly discusses the energy saving for the hybrid hydraulic excavator. By analyzing the excess energy of three hydraulic cylinders in the conventional hydraulic excavator, a new boom potential energy recovery system is proposed. The mathematical models of the main components including b...