86,727 research outputs found
A voltage controlled oscillator for obtaining a frequency reference constantly locked to L1 GPS carrier for Power Quality assessment applications
No full textThe need to correlate as accurately as possible Time to the power quality events pushes
towards the necessity to develop circuits able to yield a time reference that is referable to International
Time Standards. Moreover, the necessity to deploy distributed power quality monitoring systems
requires these time references to be easy to disseminate, making them available on specific monitoring
sites. In this paper, the possibility to obtain a time reference continuously traceable to a Cs133 atomic
standard is proposed, by locking the Cesium-derived L1 GPS satellites carrier by means of a
specifically designed GPS receiver. Such time reference would simply require visibility of one GPS
satellite in order to be operative. In particular, the overall architecture of such receiver will be first
outlined and then attention will be focused on the design and realization of the VCO which is one of its
fundamental building blocks. Measurements carried out on a prototype of the proposed VCO show that
its performances are adequate for the aim
L'ESERCITO SILENZIOSO. OSSERVAZIONI PRELIMINARI SU UN LUOGO DI SEPOLTURA DELLE GUERRE GRADISCANE (1615-1617) A MARIANO DEL FRIULI
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Forni di Sopra (UD). Indagine nel castrum di Cuol di Ciastiel ad Andrazza. III campagna 2008
No full textIl contesto e i lavori pregressi
No full textSi offre una revisione degli scavi condotti negli anni ottanta, e un'introduzione alle fonti scritte relative al castello di San Giovanni di Flagogna (Forgaria nel Friuli-UD)
Customized system for vegetable oils quality control based on dielectric spectroscopy analysis
No full textIn this work, a dielectric permittivity measurement system, to be used for quality control of edible oils, is presented. The proposed system relies both on low-frequency and high-frequency measurements (performed through and LCR meter and through a time-domain reflectometer, respectively), thus allowing a "broadband" investigation of the dielectric behavior of edible oils. The adoption of a single, specifically-designed probe (used for all the measurements), along with the possibility of using portable instrumentation, makes the proposed system an appealing candidate for the realization of a continuous, on-site system for quality monitoring of edible oils. The proposed system was first validated on materials with well-known dielectric characteristics. Successively, it was used to investigate the dielectric behavior of some autochthonous varieties of olive oils and of seed oils. The ultimate goal of this work is to pave the way for the development of an alternative method of analysis that could be able to distinguish among different kinds of oils, to certify oil quality and origin, and to detect the possible presence of adulterants
Radiation-Enhancement Properties of an X-Band Woodpile EBG and its Application to a Planar Antenna
Get PDFA woodpile Electromagnetic Bandgap (EBG) material has been designed, by using an in-house code that implements the Fourier Modal Method (FMM). A couple of alumina-woodpile samples have been fabricated. Several results have been collected for the transmission behaviour of the woodpile and of resonators with woodpile mirrors, in a shielded anechoic chamber, by using a vector network analyzer, in the 8-12 GHz range. These new experimental data highlight interesting properties of 3D EBG resonators and suggest possible innovative applications. Comparisons of the collected results with FMM show a satisfactory agreement. An application of the EBG resonator has been considered, for gain enhancement of a microstrip antenna: an increase of about 10 dB in the broadside gain has been measured; experimental data and numerical results obtained with the commercial software HFSS show a good agreement. A comparison is presented between EBG resonator antennas and two-dimensional uniform arrays. Finally, HFSS results are provided for EBG resonator antennas working at higher frequencies or with a more selective superstrate: a gain enhancement of more than 18 dB is achieved by such antennas
Wideband measurement of dielectric properties of wheat flour
No full textUse of electromagnetic (EM) fields in the food industry for food inspection as well as sterilization and drying is increasing. To develop such applications, the knowledge of the dielectric properties of food is fundamental. In the literature, there is scarcity of data on dielectric properties of powdered foods, with reported values that are usually at specific frequencies only. This article reports the development of an experimental framework to characterize the dielectric properties of powdered food over a wide range of frequencies. The used methodologies include the open-ended coaxial probe technique and waveguide systems: the first being intrinsically a broadband technique but strongly dependent on the type of material being tested, and the latter being a medium- to narrowband technique allowing a better control of the tested material. The proposed framework is then used to measure the dielectric properties of several types of flour between 500 MHz and 20 GHz. The measured properties are then characterized in terms of density and interpolated with a Cole-Cole dispersive model. From the measured results, the suitability of the proposed setup was demonstrated. Additionally, it was verified that the permittivity of flour does not depend on the brand and can be expressed as a function of the density of the material, following a mixture formula already proposed in the literature. Moreover, the proposed Cole-Cole fit is able to represent the frequency behavior of the real part of permittivity of flour with differences within 3% from the measured data
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