Search results for "Head"
showing 10 items of 1640 documents
Finite Element Simulation of Multilayer Metal Cylinder Head Gaskets
2006
ABAQUS gasket elements are an efficient and flexible tool to study gasket applications. Nevertheless the usage of the ABAQUS gasket elements is not limited to gasket analysis, but it provides an effective improvement in structural analysis. The results point out that both the predicted contact pressure and the predicted stress distribution depend on the mesh topology. Several combinations of mesh dimension and topology are investigated. The purpose is the definition of a calculation methodology and the demonstration of the application potentiality. Complex models analysis highlights that the set methodology constitutes a very effective tool for the design and optimization of gasket, cylinde…
Dynamic railroad inspection using the laser-air hybrid ultrasonic technique
2006
Laser-Air Hybrid Ultrasonic Technique (LAHUT) combines laser generation with air-coupled detection of ultrasound. The technique is non-contact and has the characteristic of operating from remote distances. Acoustic wave laser-generation apparatus can be metres away from the interrogated surface while air-coupled detection standoff can be on the order of several centimetres. The technique has the unique capability of interrogating structural materials in their true industrial environment. Dynamic tests are performed on parts with complex geometry, limited accessibility and curved surfaces. Also, dark and rough finish surfaces, which significantly reduce the efficiency of optical detection te…
Turbo-roundabouts vs Roundabouts Performance Level
2012
AbstractIn this paper the performance level of basic turbo-roundabouts and double-lane roundabouts are compared. Cowan's M3 headway distribution was chosen to take into account bunched vehicles moving along each circulating lane; the Hagring model was adopted to evaluate entry capacity both at turbo-roundabout and at double-lane roundabout.The comparative analysis was performed evaluating operational performances in terms of delay suffered by users entering the intersection.Results of the analyses show that efficiency of basic turbo-roundabouts highly depend on traffic situations and can be significant when major road captures most of the traffic demand.
Finite-Difference Time-Domain Simulation of Towers Cascade Under Lightning Surge Conditions
2015
In this paper, the simulation of towers cascade under lightning surge conditions is presented. Finite-difference time-domain method is used to solve both the Maxwell's and telegraph equations. Maxwell's equations and the time-domain resistivity model of Darveniza are used to simulate the nonlinear behavior of the grounding system. Telegraph equations are used to describe the propagation in the overhead lines. Multiple ionizations, on different grounding electrodes belonging to various towers, can be implemented simultaneously, without making assumptions on the shape of the ionized areas.
Laser-air hybrid ultrasonic technique for dynamic railroad inspection applications
2005
The Laser-Air Hybrid Ultrasonic Technique (LAHUT) combines laser generation with air-coupled detection of ultrasound. The technique is non-contact and has the characteristic of operating from remote distances. Acoustic wave laser-generation apparatus can be metres away from the interrogated surface, while air-coupled detection stand-off can be on the order of several centimetres. The technique has the unique capability of interrogating structural materials in their true industrial environment. Dynamic tests are performed on parts with complex geometry, limited accessibility and curved surfaces. Also, dark and rough finish surfaces, which significantly reduce the efficiency of optical detect…
Uprating an Overhead Line. Italian TSO Applications for Integration of RES
2013
The increase of Renewable Energy Sources (RES) production units has caused significant changes in the electrical system configuration. The existing structural asset isn't adequate to dispatch these new power flows that, at same time, should be favorite by various TSOs in order to obtain incentives. The outage of primary substations on the grid and the increase of consumptions have caused growing load currents on existing overhead line. This paper, after introducing thermal resistant conductors and Dynamic Rating (DR) solutions, reports an applications used by TERNA Group S.p.A. (Italian TSO). These systems are already installed on lines and they are contributing to increase power flows than…
Ground fault distribution on overhead transmission lines
2006
When a ground fault occurs on an overhead transmission line in a power network with grounded neutral, the fault current returns to the grounded neutral through the tower structures, ground return paths and ground wires. This paper presents an analytical method in order to evaluate the ground fault current distribution in an effectively grounded power network. The effect of soil resistivity, ground resistance of towers and power line configuration, on the magnitude of return currents, has been examined.
Assessing a Local Losses Evaluation Procedure for Low-Pressure Lay-Flat Drip Laterals
2014
In the past, several research experiments have focused on the hydraulic characterization of traditional drip irrigation systems, and different design methodologies have been proposed with the aim of achieving very high emitter discharge uniformity (EU). The increasing use of low-pressure lay-flat drip laterals, characterized by a thin-walled polyethylene pipe, makes necessary a specific determination of their hydraulic properties, aimed to a correct design of such systems. Here, the validity of an empirical local losses estimation model was assessed for five different commercial lay-flat drip tapes. Moreover, the errors in the maximum lateral lengths obtained for a fixed emitter uniformity,…
Multimodal user interface for a semi-robotic visual assistance system for image guided neurosurgery
2005
Abstract We developed a visual assistance system for image guided neurosurgery, consisting of a stereoscopic digital camera (exoscope) mounted on a semi-robotic manipulator. In order to minimize the operation time, the application-specific multimodal user interface enables hands-free manipulation of the exoscope. The surgeon wears thereby a head-mounted unit with a binocular display, a head tracker, a microphone and earphones. Different modes of view positioning and adjustment can be selected by voice and controlled by head rotation while pressing a miniature confirmation button mounted on a finger ring or suction device. Apart from the development of the mechatronic and software modules of…
Cross-Flow Turbine Design For Energy Production And Discharge Regulation
2015
Cross-flow turbines are very efficient and cheap turbines that allow a very good cost/benefit ratio for energy production located at the end of conduits carrying water from a water source to a tank. In this paper a new design procedure for a cross-flow turbine working with a variable flow rate is proposed. The regulation of the head immediately upstream the turbine is faced by adopting a shaped semicircular segment moving around the impeller. The maximum efficiency of the turbine is attained by setting the velocity of the particles entering the impeller at about twice the velocity of the rotating system at the impeller inlet. If energy losses along the pipe are negligible, the semicircular …