Nowadays, the interest in low-cost and increasingly accurate phasor measurement units (PMUs) for active distribution systems is steadily growing. In this paper, an algorithm for synchrophasor, fundamental frequency, and rate of change of frequency estimation tailored for processing platforms with limited computational resources is described and characterized extensively in terms of both accuracy and processing time. The proposed solution harnesses the main advantages of two state-of-the-art algorithms, i.e., the interpolated discrete Fourier transform and the Taylor-Fourier transform. Such algorithms are combined and implemented in a computationally efficient manner to reduce processing time as much as possible, while ensuring good accuracy in the main testing conditions specified in the IEEE Standard C37.118.1-2011 and its Amendment C37.118.1a-2014. Estimation accuracy has been evaluated not only through simulations but also experimentally. The good consistency between simulation-based and experimental results provides clear evidence that the uncertainty contributions due to transducers, acquisition, and synchronization systems can be reasonably kept under control. The processing times of the algorithm, implemented on an embedded platform suitable for PMU prototyping, are compliant with the mandatory reporting rates of Class M PMUs.

Solid-state chemiresistive gas sensors have attracted a lot of researchers’ attention during the last half-century thanks to their ability to detect different gases with high sensitivity, low power consumption, low cost, and high portability. Among the most promising sensitive materials, carbon nanotubes (CNTs) have attracted a lot of interest due to their large active surface area (in the range of 50–1400 m²/g, depending on their composition) and the fact that they can operate at room temperature. In this study, single-walled carbon nanotube (SWCNT)-based sensing films were prepared and deposited by spray deposition for the fabrication of gas sensors. For the deposition, various SWCNTs were prepared in deionized water with the addition of specific surfactants, i.e., carboxymethyl cellulose (CMC) and sodium dodecyl sulfate (SDS), which act as dispersing agents to create a suitable ink for deposition. This study aims to elucidate the possible differences in the sensing performance of the fabricated devices due to the use of the two different surfactants. To achieve this goal, all the devices were tested versus ethanol (C₂H₅OH), carbon monoxide (CO), nitrogen dioxide (NO₂), and ammonia (NH₃). The produced devices demonstrated high selectivity towards NH₃ and NO₂. The different sensors, prepared with different deposition thicknesses (from 0.51 nm to 18.41 nm), were tested in dry and wet conditions (40% humidity), highlighting an enhanced response as a function of relative humidity. In addition, sensor performance was evaluated at different working temperatures, showing the best performance when heated up to 150 °C. The best sensing conditions we found were against NO₂, sensors with 10 layers of deposition and an operating temperature of 150 °C; in this condition, sensors showed high responses compared those found in the literature (62.5%—SDS-based and 78.6%—CMC-based). Finally, cross-sensitivity measurements showed how the produced sensors are good candidates for the practical and selective detection of NO₂, even in the presence of the most important interfering gases identified, i.e., NH₃.

Microbial Fuel Cells are a promising technology for many different applications like wastewater treatment and energy supply system for monitoring hostile environments. In this article, we discuss and analyze the possibility to use jointly a small scale MFC as an energy source and a biosensor to monitor the health of the plants, with an embedded wireless sensor node. We present the prototype of the MFC and the embedded system powered by the electric energy generated by bacteria. The rate of energy generation is used as a feedback on plant's health state. Finally, we demonstrate that the amount of scavenged energy is sufficient to power on even some external sensors embedded in the wireless node.

Excessive or improper street lighting is currently responsible for a significant waste of electrical energy in many cities worldwide. In order to improve energy efficiency, the traditional light posts are expected to be gradually replaced by smart systems able to adapt the features of the emitted light to different environmental, traffic, or crowdedness conditions. Power Line Communication (PLC) is the natural choice to support smart light control, since no additional communication infrastructure is needed. However, at the moment not so many simulation tools exist to guide the design and the deployment of smart lighting systems based on PLC. In this paper, we partially address this issue by presenting suitable circuit models that can be used to analyze (through simulations at the physical layer) the behavior of narrowband PLC (NB-PLC) signals transmitted over low-voltage (LV) lines for street light control. The proposed approach is quite simple from the computational point of view, and it is scalable enough to evaluate the quality of PLC signals in large networks with different topologies. The results of several simulations, with signals in the frequency range 95-148.5 kHz, have been compared with the outcomes of some laboratory experiments over a test line.

Power line communication is becoming important as a leading technology in Smart Grid applications. This paper presents a new system to reduce the power consumption of the power line modems, implementing a zero-power stand-by feature. The incoming wake-up signal is as simple as a PLC frame and its associated energy is used to supply the wake-up logic. The system is mainly conceived for street lighting systems that use power line communication and where the stand-by power represents an issue because there are thousands of lamps in a city, and the total power consumption of the modems in stand-by mode is not negligible. This paper presents the architecture of the system, as well as the design choices. Experimental results of the system applied to a street light network show that it is possible to wake-up selectively a cluster of lamps up to a distance of about 250m.