Chapter Autonomous Sensors: Existing and Prospective Applications

Diseases & disorder

Autonomous Sensors: Existing and Prospective Applications

Diseases & disorder

Chapter Vibration Energy Harvesting: Linear and Nonlinear Oscillator Approaches

Optical physic

Layered-double hydroxides and derived oxide as CRM-free highly active catalysts for the reduction of 4-nitrophenol

The present study investigates the possibility to abate 4-nitrophenol (4NP), a well-known persistent contaminant in wastewaters, using Layered-Double Hydroxides (LDH) based catalysts, non-noble metals-based and Critical Raw Materials-free materials used for 4NP reduction with NaBH4. It is reported the study of the effects of several parameters on the overall reaction kinetic by in situ monitoring of the 4NP reduction through UV-Vis Spec-troscopy, as: (i) LDH's trivalent and divalent cation nature, (ii) LDH thermal treatment, (iii) substrate/catalyst ratio, and (iv) stirring rate. The reasons that led to increased activity were identified and correlated with cat-alyst's structure characterization. The results pointed out that LDH enhance synergic effect of nickel and copper by increasing reducibility which is further raised when defective mixed oxide by calcination is obtained. This resulted in enhanced 4NP reduction which could be further increased by calcination providing a highly reducible mixed oxide

H2 Production by Methane Oxy-Reforming: Effect of Catalyst Pretreatment on the Properties and Activity of Rh-Ce0.5Zr0.5O2 Synthetized by Microemulsion

Green hydrogen introduction in hard-to-abate processes is held back by the cost of substituting steam reforming plants with electrolyzers. However, green hydrogen can be integrated in properly modified reforming processes. The process proposed here involves the substitution of steam reforming with oxy-reforming, which is the coupling of the former with catalytic partial oxidation (CPO), exploiting the pure oxygen coproduced during electrolysis to feed CPO, which allows for better heat exchange thanks to its exothermic nature. With the aim of developing tailored catalysts for the oxy-reforming process, Ce0.5Zr0.5O2 was synthetized by microemulsion and impregnated with Rh. The Ce-based supports were calcined at different temperatures (750 and 900 degrees C) and the catalysts were reduced at 750 degrees C or 500 degrees C. Tuning the calcination temperature allowed for an increase in the support surface area, resulting in well-dispersed Rh species that provided a high reducibility for both the metal active phase and the Ce-based support. This allowed for an increase in methane conversion under different conditions of contact time and pressure and the outperformance of the other catalysts. The higher activity was related to well-dispersed Rh species interacting with the support that provided a high concentration of surface OH* on the Ce-based support and increased methane dissociation. This anticipated the occurrence and the extent of steam reforming over the catalytic bed, producing a smoother thermal profile

Nonlinear Kinetic Energy Harvesting

Abstract Harvesting of kinetic energy present in the form of random vibrations is an interesting option due to the almost universal presence of this kind of motion. Traditional generators based on piezoelectric effect are built with linear oscillators made by a piezoelectric beam and a mass used to tune the resonance frequency on the predominant frequency of the vibrations spectrum. However, in most cases the ambient random vibrations have their energy distributed over a wide spectrum of frequencies, being rich especially at low frequency. Furthermore frequency tuning is not always possible due to geometrical/dynamical constraints. In this work we present a different method based on the exploitation of the nonlinear dynamical features of bistable oscillator. The experimental results and the digital simulations show that nonlinear harvester (e.g. bistable oscillators) can overcome some of the most severe limitations of generators based on linear dynamics

Nonlinear bi-stable vibration energy harvester at work

An extreme low power energy rectification, storage and management circuitry has been developed and used to power a small digital wireless sensor with a piezoelectric non-linear bi-stable vibration energy harvester for automotive application. All the system has been designed with off-the-shelf components and sends data in the 2.4 GHz band

Front-Ends and Phased Array Feeds for the Sardinia Radio Telescope

We describe the design and performance of the Front- Ends for the 64-m diameter Sardinia Radio Telescope (SRT). An early science program was completed with SRT in August 2016, following a successful technical and scientific commissioning of the telescope and of its instrumentation. We give an overview of the three cryogenic Front-Ends, covering four bands, that were deployed on SRT during the early science program: P-band (305-410 MHz), L-band (1.3-1.8 GHz), high C-band (5.7- 7.7 GHz) and K-band (18-26.5 GHz). In addition, we describe the cryogenic Front-Ends that are currently under development, among which a seven beam for S-band (3.0-4.5 GHz) a mono-feed for Low-Cband (4.2-5.6 GHz), a 19-element for Q-band (33-50 GHz) and a mono-feed for a 3 mm band. Finally, we describe the development status of a demonstrator of a cryogenic C-band Phased Array Feed (PAF) for potential use at the SRT primary focus