The ability of plants to dynamically regulate water loss through stomata under conditions of changing evaporative demand or water availability is paramount for avoiding excessive desiccation, hydraulic failure, and plant death under conditions of water stress. Despite apparently similar functional demands on stomatal evolution, not all lineages employ the same mechanism of controlling water los...

Operational failures in centrifuge pumps could be hydraulic or mechanical. However, most of these mechanical and hydraulic failures are connected cause of their operational nature and finding the right cause is due to considering numerous mechanical and hydraulic signs and parameters in pumps. On the other hand, due to non-linear and fluctuant behavior of pumps in the matter of time and not pre...

Concepts of motivation are vital to progress in behavioral neuroscience. Motivational concepts help us to understand what limbic brain systems are chiefly evolved to do, i.e., to mediate psychological processes that guide real behavior. This article evaluates some major motivation concepts that have historic importance or have influenced the interpretation of behavioral neuroscience research. T...

This paper deals with the achievement of a reduced order mathematical model using the singular perturbations method for an electrohydraulic system composed by a hydraulic cylinder which is controlled with an electrohydraulic servovalve with five ways. Due to the high value of the bulk-modulus of fluid, to the low value of the fluid occupied volume and also to the spool valve mass low, the equat...

Many studies in the last years showed that, for a wide variety of plants, stomata apertures exhibits spatial temporal patterns in a phenomena known as patchy stomatal conductance. Many attempts were made to build numerical models to explain this complex behavior, but none were able to explain all of behaviors observed in nature. In this work we discuss some limitations of an hydraulic cellular ...

We introduce a discrete element simulation for the hydraulic fracture process in a petroleum well which takes into account the elastic behavior of the rock and the Mohr-Coulomb fracture criterium. The rock is modeled as an array of Voronoi polygons joined by elastic beams, which are submitted to tectonical stresses and the hydrostatic pressure of the fracturing fluid. The fluid pressure is trea...

Digitally controlled electrohydraulic (EH) closed-center valves and load sensing hydraulic pump systems have been quickly replacing the older generation of hydro-mechanically controlled (pilot actuated, mechanically controlled) open-center valves and fixed displacement pump systems in mobile equipment applications such as earth moving and construction equipment (i.e. wheel loaders, excavators, ...

Air bubbles in working oil influence stiffness and efficiency of hydraulic systems, thus it is important for technical issues to eliminate the air bubbles actively from the hydraulic oil. Bubble eliminator is a device that removes air bubbles by using a swirling flow. In this paper, we investigate flow behavior in the bubble eliminator by means of laboratory experiments with a transparent bubbl...

The aim of this paper is to analyze the driving system actuated by a proportional directional control valve on a hydraulic cylinder. In order to evaluate the dynamic interaction between the proportional valve and the cylinder theoretical analysis, numerical simulations as well as experimental test are performed. Coupling cylinder and proportional valve, it is very important to know the ratio of...

Modern machine tools based on parallel kinematic architecture provide excellent performance in terms of stiffness/weight ratio. Also, hydraulic actuators are widely used in industrial applications due to several advantages like large force and torque, high power to weight ratio, rapid response. The current paper presents the mechatronic design of a translational 3-DOF parallel robot which uses ...