The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
We present evidence, that an extended gas target has affected seriously the measurement of double differential electron distributions, particularly at small angles, in such a way that a previously observed ridge structure was considerably overestimated. using a newly developed spectrometer we now present distributions for electron loss and capture into the continuum which are not distorted by this...
We present detailed double differential distributions of electrons emitted in proton-Helium collisions measured in small steps for 50, 100, 150 and 200 keV proton energies. Our measurements include angles close to the direction of the projectile beam and cover an energy range of the emitted electrons in which the Coulomb interaction with both, the residual target ion and the projectile is comparable.
Low-frequency, wide-field radio telescopes such as the Murchison Widefield Array (MWA) enable the dense spatial sampling of the ionosphere and plasmasphere on regional scales. For a physically compact array such as the MWA, the refractive shifts in the positions of celestial sources in the synthesised radio images are proportional to spatial gradients in the total electron content (TEC) transverse...
The Sun has remained a difficult source to image for radio telescopes, especially at the low radio frequencies. Its morphologically complex emission features span a large range of angular scales and the emission mechanisms involved, span a wide range in brightness temperatures. In addition, time and frequency synthesis, the key tool used by most radio interferometers to build up information about...
The Murchison Widefield Array (MWA) is a new low frequency interferometric radio telescope, operating in the remote Murchison Radio Observatory in Western Australia. In this paper we present the first MWA observations of the well known radio relics in Abell 3667 (A3667) between 120 and 226 MHz. We clearly detect the radio relics in A3667 and present flux estimates and spectral indices for these features...
Old and poorly constructed pipelines, inadequate corrosion protection, poorly maintained valves and mechanical damage are factors contributing to leakage. One effect of water leakage, besides the loss of water resources, is reduced pressure in the supply system. Raising pressures to make up for such losses increases energy consumption. This rise in pressure makes leaking worse and has adverse environmental...
In this contribution an innovative non-invasive technique for water monitoring is presented. The effectiveness of the proposed tools and algorithms have been confirmed by experimental results, achieved at Laboratory of Water Engineering, University of Cassino (FR). The proposed techniques belong to the class of non-invasive electromagnetic methods, as the ones based on Ground Penetrating Radar (GPR).
Introduction and main concepts: An increasing interest in passive surveillance systems can be observed in last period. The key idea, which is also common to other non-radar applications, is to conveniently exploit opportunity signals, as analogue FM transmitters or Digital Video Broadcasters to detect and/or tracking targets [1–3].
This paper describes aspects of RAXEM2, an intelligent software system developed to support human mission planners in the daily task to plan uplink commands for the MARS EXPRESS mission at the European Space Agency. A first system called RAXEM has been in operational use at the ESA-ESOC mission control center since Summer 2007. During 2008 authors have been working to a new version of the tool to...
Service oriented architectures draw heavily on techniques for reusing and assembling off-the-shelf software components. While powerful, this programming practice is not without a cost: the software architect must ensure that the off-the-shelf components interact safely and in ways that conform with the specification. We develop a new theory for adaptable service composition. The theory provides an...
This paper presents a new systematic simulation procedure to compute the altimeter signal return, thus showing the correlation of the signal return shape with height, slope, sub-surface layers and different scales of roughness of the surface of interest. For the first time, and as appropriate to natural surfaces, the scene is fully modelled by means of the fractal geometry. By observing the results...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.