Luca Podesta

Optical sensors for electric substations: a voltage presence detector using a liquid crystal cell

A new fiber optic voltage presence detector is presented, based on the detection of the excitation state of a liquid crystal cell by means of an optical technique. The sensor was designed to work in electric metal-clad medium-voltage (MV) switchboards with SF/sub 6/ insulation where EM immunity and insulation requirements make fiber optic sensing the most suitable choice. The small size of the probe, its high reliability, and its low cost make it especially suited for these compact structures. Working principle and design details are reported. >

The Generalized Lambda Distribution for the Expression of Measurement Uncertainty

The generalized lambda distribution family fits the probability distributions of a wide variety of data sets, including the most important distributions in measurement applications (normal, uniform, students t, U-shaped, exponential). This paper illustrates how the representation of measurement uncertainty by means of the four parameters of the distribution can extend the information about the results of a measurement and their uncertainty. Such representation allows an immediate calculation of coverage intervals and is particularly able to support the techniques commonly applied in estimation of combined uncertainty. Moreover, in order to include the classical measurement information, a novel X-parametrization is proposed

Modular Architecture for Remote Management of Powe Generation Plants

This paper describes a network architecture to remotely monitor and control complex power generation plants. Such architecture was designed as a sequence of independent blocks, in order to allow the interchangeability among elements belonging to the same block type. The resulting systems can be adapted to the particular plant, the available communication media and the sustainable costs. The architecture and the proposed solutions were applied to two types of generation plants, based on photovoltaic and wind micro-generators

Binary Sequences with Good Spectral Properties Obtained by Genetic Algorithms

This paper describes a novel method for the digital synthesis of high quality signals by means of one-bit digital-to-analog converters. The aim of the paper is the individuation of the best binary sequences for signal generation and the analysis of their properties. Such sequences are obtained by genetic algorithms, either independently of a physical implementation of the analog-to-digital converter, or by optimizing the parameters of an oversampled conversion

A measurement campaign in a metro trains deposit/maintenance and repair site for PV production optimal sizing

The paper describes a measurement campaign conducted in a metro trains deposit/maintenance and repair site for the trains in operation on the metro line B of Rome. For the measurement campaign the network analyzer Chauvin Arnoux CA 8335 has been used. The measurements were conducted by performing a monitoring on general consumption and on relevant individual loads such as office building, lighting towers, lighting, lathe, etc. The knowledge of total energy consumption and of electrical loads allows the identification of possible different strategies for energy efficiency by using the PV production. Some evaluations are also conducted on the possible use of storage energy systems.

A comparison between backprojection and sensitivity methods in EIT reconstruction problems

Electrical impedance tomography is an imaging technique used to estimate the electrical conductivity distribution of human body sections. To solve the inverse problem of EIT many numerical methods have been developed. Two of these methods, namely the backprojection algorithm and the sensitivity method, are compared in this paper on some canonical models representing a section of the human body.

Distributed Network for Accurate Indoor Localization of Mobile Phones

The availability of a system to detect and localize mobile phones and portable electronic devices may be useful in many situations, generally corresponding to indoor environments. This paper describes a distributed system for the localization of mobile phones that can be extended to the detection of other portable electronic devices. It is based on a small low-cost sensing units developed to this purpose. Due to the peculiarity and variability of the emitting sources, of the adopted principles, and of the considered environments, the electromagnetic characterization of the system was referred to novel statistical parameters defined in a loaded reverberation chamber. The results of some experimental tests concerning the whole system and the single elements are also presented.

Comparison among low-cost portable systems for thoracic impedance plethysmography

Impedance plethysmography is a technique which allows the monitoring of respiratory activity through the measurement of variations in the trans-thoracic impedance. Provided the measurement system has enough sensitivity, the same technique can also detect heartbeats, thus adding cardiac activity monitoring capabilities. In this paper, a comparison is performed between 2-electrode and 4-electrode systems, considering both volt-amperometric and AC-bridge solutions. Attention is focused on low-cost, easily portable, and reconfigurable measurement set-ups, whose performances are analyzed in terms of sensitivity and accuracy. To this end, LabVIEW virtual instruments based on a data acquisition card are employed. An experimental metrological assessment of the systems shows that their basic accuracy is definitely adequate for patient monitoring. However, based on a theoretical study on measurement resolution, only the volt-amperometric solution in 4-electrode configuration achieves enough sensitivity to correctly detect the cardiac activity. The above conclusion is verified by acquisitions made on several volunteers.