1,721,059 research outputs found
A Study of noise-independent Bias Error in Identification of the Parameters of Multitone random signals
No full textFlat-top smoothing of periodograms for improvement of accuracy in estimating power spectra with Welch’s method
No full textType A Evaluation of Uncertainty Due To Systematic Effects in Digital Oscilloscopes
No full textThe paper presents a type A (experimental) evaluation of the uncertainty due to systematic effects. After a brief discussion about the general problem of choosing a proper mathematical representation for systematic effects in the context of uncertainty evaluation, a pragmatic approach, based on the familiar random variable theory and the ISO 5725 norm is proposed. The approach is called “interinstrument experiment”, on the analogy of the “interlaboratory experiment” of the ISO 5725. Preliminary experimental results, relevant to commercial digital oscilloscopes, are presented and discussed
Qualitative and Quantitative Characterization of Liquids from TDR Measurements
No full textTime-domain Reflectometry (TDR) is a well-established technique for
the development of microwave sensors devoted to the dielectric characterization
of materials. This renders TDR an appealing method for a variety of monitoring
applications. Till now, TDR has been successfully applied to solve hydrological
or soil prospecting problems, though its adoption in many other cases is worth an
investigation. In this paper, it is demonstrated that TDR is a viable approach for
quantitative and qualitaive real-time characterization of liquids inside tanks. In
fact, in one shot the suitable handling of time-domain reflectometry data allows
the determination of the liquid level, as well as the evaluation of dielectric
properties, such as dielectric permittivity and electrical conductivity. Some
applications to real cases are proposed, referred to petrol-chemical mixtures or
water-based liquids, thus validating the approach on a wide range of materials
Valutazione di Tipo A dell’Incertezza Derivante da Errori Sistematici in Oscilloscopi Digitali
No full textCaratterizzazione Quantitativa e Qualitativa di Liquidi Tramite Tecnica di Riflettometria nel Dominio del Tempo
No full textA TDR method for real-time monitoring of liquids
No full textTime-domain-reflectometry (TDR) measurements,
which were originally used to locate and diagnose faults in transmission lines, have been widely applied in geology and soil science for accurate and flexible measurements of soil moisture and water content. Furthermore, the most attractive advantages of TDR rely on the possible determination of the spatial location and nature
of various objects, both in real time and with a nondestructive approach.
This makes the TDR technique an appealing candidate for
a variety of environmental and industrial applications. Although
the TDR instruments are commonly used to date, particularly
for the aforementioned purposes, the state of the art is rather
lacking in liquid-monitoring applications. This paper describes
how the suitable combination of TDR detecting functionalities can
lead to a simultaneous monitoring of quantitative and qualitative
properties of liquid samples. In fact, the proposed TDR method
allows, in one shot, the measurement of liquid levels, the determination of multiple interfaces in layered media, and the evaluation of dielectric properties such as dielectric permittivity or electrical conductivity. Some applications to real cases are proposed, which are referred to petrol–chemical mixtures or water-based liquids,
thus validating the approach on a wide range of materials
Long-Term Monitoring of Photovoltaic Plants
Full text linkThis paper deals with a data-acquisition system that has been specifically developed for a long-term monitoring of ten different photovoltaic plants. The main goals of the system consist in estimating the drift of the plant components, mainly photovoltaic modules and power inverters, and comparing the performance of the ten plants, which are based on different technologies and architectures. Owing to these goals, the traceabilityassurance of the obtained measurements is mandatory, hence the data-acquisition system has been designed to be easily calibrated and, if necessary, adjusted to compensate for measuring-chain drifts. In addition, the measurement uncertainty, which has to be suitable to distinguish the behaviour of the different PV plants, has to be stated for each of the estimated parameters. A brief description of the data-acquisition system is provided and its measurement capabilities are highlighted in terms of measured quantities and expected uncertainty. Results that refer to a period of thirty months are also reported
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