Gyro spring augmentation system

Spring-loaded piston with provision for hydraulic control of spring action varies the stiffness of hydraulic control systems

The present state of the water exchange through the Strait of Gibraltar

The present two-way exchange through the Strait of Gibraltar stems from the fresh water deficit of the Mediterranean basin. The size of the exchanged flows is the outcome of the climatology over the basin and the morphology and internal hydraulics of the Strait. Its highly constraining topography imposes an upper bound to the flows that cannot be exceeded, a limit known as maximal exchange, which is associated with the minimum salinity difference (density, in fact) between the inflowing (Atlantic) and outflowing (Mediterranean) waters. A relevant question is whether or not the present exchange has achieved this limit. A simple steady-state model of the Mediterranean Sea and Strait of Gibraltar system in which the deep water formation rate is balanced by the Mediterranean outflow, strongly suggests that the exchange is quite close to (or, indeed, it is) maximal. The Strait topography requires two hydraulic control sections for this limit to be achieved, which could be thought as if one of them controls the outflow (the section of the main sill of Camarinal) and the second one the inflow (the narrowest section or Tarifa Narrows, to the east of the main sill). Oceanwards of Camarinal, the outflow accelerates and settles as one of the fastest and brisk bottom currents of the world ocean. East of Tarifa Narrows the inflow becomes a swift jet, the Atlantic Jet, which enters the Mediterranean Sea and sets up the basic features of the Alboran Sea surface circulation. The steady exchange so far depicted is not realistic. The flows undergo large fluctuations at different time scales, which modify the former description drastically. Of special importance are the tides and associated tidal flows, which can be up to 5 times greater than the long-term averaged flows. Under such huge fluctuations, the hydraulic control in Camarinal sill is periodically lost about two hours before high water, during the rising tide, when the tidal currents still head toward the Atlantic Ocean. The flooding of the control is revealed by the release of a vast internal hydraulic jump that progresses towards the Mediterranean Sea while evolving into a regularly shaped train of great amplitude internal waves that carry away part of the tidal energy accumulated nearby the sill during the rising tide. Whenever the hydraulic control at Camarinal is lost, a second sill located to the west (Espartel sill, the westernmost gateway of the Strait) takes over the control of the Mediterranean outflow. The hydraulic control at Espartel is very seldom flooded, which is a fundamental fact for understanding the internal dynamics of the exchange under large barotropic fluctuations. Without this sill, the Strait dynamics would be very different. It is behind the powerful, but periodically inverting, bottom currents nearby Camarinal sill and the also strong, but already unidirectional, bottom currents in Espartel sill and beyond, a reason for which this sill might well be considered as the proper source of the Mediterranean plume in the Atlantic Ocean.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Hydraulic control of continental shelf waves

This paper studies the hydraulic control of continental shelf waves using an inviscid barotropic quasi-geostrophic model with piecewise-constant potential vorticity, in which the shelf is represented by a flat step of variable width. A coastal-intensified geostrophic current generates topographic Rossby waves, which can become critical at a local decrease in shelf width when the background current opposes Rossby wave propagation. That is, the shelfbreak perturbation permanently modifies the flow field over arbitrarily large distances and the flow transitions from subcritical to supercritical as it crosses the perturbation. Critically controlled flows also lead to the exchange of significant volumes of water between the shelf and the deep ocean. We derive the boundaries for which critical control occurs in terms of a Froude number and the dimensionless magnitude of the perturbation, and analyse the possible transitions between controlled and far-field flow. When first-order dispersive terms are included in the model, transitions are resolved by dispersive shock waves, which remain attached to the forcing region when the Froude number is close to the boundary for critical flow. Contour dynamic simulations show that the dispersive long-wave model captures the quantitative behaviour of the full quasi-geostrophic system for slowly varying shelves, and replicates the qualitative behaviour even when the long-wave parameter is order one

Design of a wrist and operator interface for an agricultural manipulator : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Engineering and Automation at Massey University

Roadside mowing and tree pruning has always been a job that most people would consider as unpleasant. This project is concerned with the development of a system to make these tasks simpler, safer and more pleasant for the operator. 1.1 Software This project is involved with the design of a complex mechanical system, which could be done using a modern CAD package. To achieve this, research into what modelling package was best was necessary. Several contenders were considered. These include SolidWorks [1], Mechanical Desktop [2] and CADKEY [3]. CADKHY was disregarded early as it is not as expandable as the other two. Both SolidWorks and Mechanical Desktop have additional software packages that allow for motion, force and stress analysis. The major difference between SolidWorks and Mechanical Desktop, is that SolidWorks is a true three dimensional modelling package, whereas Mechanical Desktop is based on the two dimensional AutoCAD system with a three dimensional toolbox. The choice was finalised to SolidWorks as it handles three dimensional modelling more efficiently. Massey University also uses SolidWorks. This allowed the project to continue while studying at the Turitea campus. 1.2 Overview This project is involved with the development of a wrist mechanism and hydraulic control system for an agricultural manipulator. The manipulator is called the Hydra Trim and was developed by Pivot Engineering Ltd. Napier [4]. The wrist mechanism is an integral part of making the Hydra Trim a success. The hydraulic control requires not only the valves but also an interface between the operator and the valves

Kelvin wave hydraulic control induced by interactions between vortices and topography

The interaction of a dipolar vortex with topography is examined using a combination of analytical solutions and idealized numerical models. It is shown that an anticyclonic vortex may generate along-topography flow with sufficient speeds to excite hydraulic control with respect to local Kelvin waves. A critical condition for Kelvin wave hydraulic control is found for the simplest case of a 1.5-layer shallow water model. It is proposed that in the continuously stratified case this mechanism may allow an interaction between low mode vortices and higher mode Kelvin waves, thereby generating rapidly converging isopycnals and hydraulic jumps. Thus, Kelvin wave hydraulic control may contribute to the flux of energy from mesoscale to smaller, unbalanced, scales of motion in the ocean

Literature Review on Design and Working of 3 Way Pilot Operated Diaphragm Controlled Hydraulic Control Valve

Most flow applications require regulating the flow of liquid and usually the parameter of flow is pressure. This paper focuses on the design assembly and working of a 3 way pilot operated diaphragm controlled hydraulic control valve. A 3 way pilot operated hydraulic control valve is used in this study for reducing the pressure on the main line, sustaining the pressure on the main line and quick pressure relief for a by-pass line. This study has been carried out on a 2” line with a bronze 2” diaphragm operated hydraulic control valve a brass pilot with pressure adjustment range of 0.7 bars to 6.5 bars. Through the study, I also found about the chaotic behaviour of the pilot with the sudden variation in the upstream pressure of the main line

Разработка компоновочного решения агрегатно-модульных гидроблоков управления и формы монтажного корпуса

Для определения формы монтажного корпуса агрегатно-модульных гидроблоков управления гидроприводов технологического оборудования выполнены исследования математической модели, устанавливающей взаимосвязи между фазовыми переменными элементов подсистем, включающих топологические модели подсистем гидроблоков управления и компоновочные их решения. Установлено, что оптимальная компоновка гидроблоков управления достигается в случае применения монтажного корпуса, форма которого позволяет установить в одном горизонтальном уровне четыре гидроаппарата.For defining the shape of the mounting frame for modular hydraulic control units for the hydraulic drive of manufacturing equipment the study of the mathematical model was carried out establishing the relations between phase variables of components of subsystems including topological models of the subsystems of hydraulic control units and their arrangement designs. It is established that an optimal hydraulic control unit arrangement is provided in case of using the mounting frame the shape of which enables to mount four hydraulic appa­ratuses on the same horizontal level

Pressure variable orifice for hydraulic control valve

Hydraulic valve absorbs impact energy generated in docking or joining of two large bodies by controlling energy release to avoid jarring shock. The area of exit porting presented to the hydraulic control fluid is directly proportional to the pressure acting on the fluid

Structure and dynamics of the sudden acceleration of Kuroshio off Cape Shionomisaki

A sudden acceleration of the Kuroshio jet appears off Cape Shionomisaki in the high-resolution (horizontal resolution of 1/36°) JCOPE 2 ocean reanalysis data. Using this dataset, we investigated the structure of the Kuroshio acceleration. The increase in the velocity of the current is accompanied by a downstream flow separation from the coast and an outcrop of cold temperature inshore. The acceleration of Kuroshio appears when it takes a near-shore path. Cape Shionomisaki amplifies the responses to the Kuroshio flow by creating the zonal velocity acceleration toward the downstream region when the Kuroshio flows closer to the coast. The Kuroshio acceleration coincided with the topographic ridge on the continental shelf near Cape Shionomisaki. This relation suggests that the dynamics of the acceleration is linked to the topographic feature. We proposed an explanation of the Kuroshio acceleration using a hydraulic control theory. An analytical solution was applied to the coastal topography around the Kii Peninsula. The solution captured some aspects of the Kuroshio acceleration