Search results for "Head"
showing 10 items of 1640 documents
New Computational Fluid Dynamic Procedure to Estimate Friction and Local Losses in Coextruded Drip Laterals
2007
The design of trickle irrigation systems is crucial to optimize profitability and to warrant high values for the emission uniformity (EU) coefficient. EU depends on variation of the pressure head due to head losses along the lines and elevation changes, as well as the water temperature, and other parameters related to the emitters (manufacturer's coefficient of variation, number of emitters per plants, emitter spacing). Trickle irrigation plants are usually designed using small diameter plastic pipes (polyethylene or polyvinyl chloride). The design problem, therefore, needs to consider head losses along the lines as well as emitter discharge variations due to the manufacturer's variability.…
Experimental investigation on PLC signal crossing of power transformers
2014
In this work the use of PLC in MV-LV networks is investigated, by means of experimental tests in the case of a two-ways MV/LV communication between two secondary substations. The two substations are connected by a MV overhead power line. Moreover each substation has a by-pass connection at MV bus-bars and a MV/LV power transformer. A ST7580 transceiver is used to inject the communication signal. The transceiver is embedded in a new interface device developed by the authors. In the paper the communication issues are introduced and some experimental tests are presented and discussed. Such tests have been carried out in the presence of voltage net, i.e. 24 kV, with the aim to verify the possib…
FE Calculation Methodology for the Thermodynamic Fatigue Analysis of an Engine Component
2006
Thermo mechanical fatigue problem is treated to define an analysis methodology permitting the strength evaluation by reliability viewpoint. The main difficulty is the lack of both theoretical and experimental information; consequently the problem is treated verifying continually the validity and the limits of the developing solution method. The main task of the activity described in this paper was the development of a numerical methodology, based on FE analyses, for the evaluation of the structural behavior of engine components subjected to thermo mechanical fatigue phenomena. The chosen application was the exhaust manifold of an IC engine; FE analyses were executed following the standard m…
Oil filled MV/LV Power Transformer Behavior in Narrow Band Power Line Communication Systems
2012
The aim of this paper is to characterize oil-filled power transformers in the narrow-band power-line communication (PLC) frequency range of 50-150 kHz. A new model is proposed for such type of a transformer, in the aforementioned frequency range of interest, in order to study its influence on the signal transmission and to investigate the possibility that the PLC signal can cross the power transformer itself. The new model is simpler than those previously proposed in literature, and it can be used in the whole frequency range available for NB PLC according to the CENELEC EN 50065-1 A-band. In order to validate the model, simulation and measurement results are compared for four oil-filled po…
On the roadmap to supergrid in Sicily: LiDAR technology and HTLS conductors for uprating the 150 kV lines
2014
Difficulties in building new power lines in Italy because of authorization problems, and the production of electricity from renewable sources growing more and more, induces Terna S.p.A. (Italian TSO) to take advantage of existing overhead transmission lines. In order to increase the transmission capacity, Terna has used a software in GIS (Geographic Information System) environment which allows for the management of the interferences according to all the legislative bonds by referring to the LIDAR (Laser Imaging Detection and Ranging) remote sensing technology. This paper, after a description of the GIS and the LiDAR technology, shows how the calculation of the current capacity of some High …
GIS systems and LIDAR technology for the operation of HV lines. Sicilian transmission network applications
2013
The difficulties to build new power lines within the national territory cause of authorization problems, and the evermore growing production of electricity from renewable sources, induces Terna S.p.A. (Italian TSO) to take advantage of existing overhead transmission lines. Therefore, in order to increase the transmission capacity, and to optimize the maintenance and management of power lines, for some years Terna has been using a software in GIS environment (Geographic Information System) that referring to the LIDAR (Laser Imaging Detection and Ranging) remote sensing technology, allows to manage the interferences according to all the requirements and legislative bonds and to fulfill the im…
Methodological frontier in operational analysis for roundabouts: a review
2016
Several studies and researches have shown that modern roundabouts are safe and effective as engineering countermeasures for traffic calming, and they are now widely used worldwide. The increasing use of roundabouts and, more recently, turbo and flower roundabouts, has induced a great variety of experiences in the field of intersection design, traffic safety, and capacity modeling. As for unsignalized intersections, which represent the starting point to extend knowledge about the operational analysis to roundabouts, the general situation in capacity estimation is still characterized by the discussion between gap acceptance models and empirical regression models. However, capacity modeling mu…
A Simple Method for Evaluating Ground-Fault Current Transfer at the Transition Station of a Combined Overhead-Cable Line
2008
When a substation is fed by a combined overhead-cable transmission line, a significant part of the ground fault current flows through cable sheaths and is discharged into the soil at the transition station where cables are connected to the overhead line. Such a phenomenon, known as ldquofault application transfer,rdquo may result in high ground potentials at the transition station which may cause shocks and equipment damage. The scope of this paper is to present new analytic formulas which can be used for the direct calculation of the fault current transferred at the transition station and its ground potential rise as well as the substation earth current. The proposed formulas allow evaluat…
Low-cost underwater navigation systems by multi-pressure measurements and AHRS data
2017
This paper deals with accurate navigation for underwater remotely operated vehicles. A feasibility study for a multi-pressure device to be mounted on an ROV is presented. The device can provide accurate estimates of a ROV orientation and angular speed. It is based on the well-known total pressure principle, also used in a Pitot tube, and allows reconstruction of static and dynamic pressures, which in turn provide good estimates of the ROV's orientation and rotational speed, respectively. An appealing feature of the proposed device is its ability to provide accurate estimates even for low-speed movements.
Head and Body Coordination during Locomotion and Complex Movements
1994
Publisher Summary This chapter discusses theory in which it is argued that during complex movements, the head is stabilized intermittently under the control of gaze, and that this stabilization allows the head to serve as an inertial guidance platform for the control of multilimb movement. The otolithic organs, sacculus and utriculus, are inertial detectors of linear acceleration of the head in the plane of their macula. It is well established that in normal gravity conditions, although the perceived gravitational vertical deviates from the objective vertical by a few degrees, gravitational reference is used not only for posture but also for perceptual tasks that involve orientation in spac…