Various recast Nafion® composite membranes containing ceramic oxide fillers with different surface characteristics (SiO
2, SiO
2–PWA, Al
2O
3, ZrO
2) have been investigated for application in high ...temperature direct methanol fuel cells (DMFCs). Cell resistance at 145 °C increases as a function of the pH of slurry of the inorganic filler indicating a strong influence of the acid–base characteristics on the electrolyte conductivity. This effect has been attributed to the different water retention capabilities of the various membranes. Fuel cell performance at 145 °C, expressed as both maximum power density and current density at 0.5 V cell potential, increases almost linearly as the pH of slurry of the oxide materials decreases. Appropriate selection of the surface properties for the inorganic fillers allows to enhance the proton conductivity and extends the operating temperature range of composite membranes. The influence of fuel cell operating pressure on the humidification properties of these electrolytes at high temperature has been also investigated.
▶ Present work shows design, fabrication and functional characterization of a very low cost energy autonomous, maintenance free, flexible and wearable micro thermoelectric generator (μTEG). ▶ The ...preliminary prototype integrates an array of 100 thin films thermocouples of Sb2Te3 and Bi2Te3. ▶ At real operation conditions (thermal gradient of 15°C), device generates an open circuit output voltage of about 160mV, electrical output power up to 4.18nW. ▶ Deposition investigation of Sb2Te3 and Bi2Te3 thin films alloys on Kapton HN polyimide foil by RF magnetron co-sputtering technique is discussed. ▶ Deposition parameters have been optimized to gain perfect stoichiometric ratio and high thermoelectric power factor.
In this work we proposed design, fabrication and functional characterization of a very low cost energy autonomous, maintenance free, flexible and wearable micro thermoelectric generator (μTEG), finalized to power very low consumption electronics ambient assisted living (AAL) applications. The prototype, integrating an array of 100 thin films thermocouples of Sb2Te3 and Bi2Te3, generates, at 40°C, an open circuit output voltage of 430mV and an electrical output power up to 32nW with matched load. In real operation conditions of prototype, which are believed to be very close to a thermal gradient of 15°C, the device generates an open circuit output voltage of about 160mV, with an electrical output power up to 4.18nW.
In the first part of work, deposition investigation Sb2Te3 and Bi2Te3 thin films alloys on Kapton HN polyimide foil by RF magnetron co-sputtering technique is discussed. Deposition parameters have been optimized to gain perfect stoichiometric ratio and high thermoelectric power factor; fabricated thermogenerator has been tested at low gradient conditioned to evaluate applications like human skin wearable power generator for ambient assisted living applications.
A fast readout algorithm for Cluster Counting and Timing purposes has been implemented and tested on a Virtex 6 core FPGA board. The algorithm analyses and stores data coming from a Helium based ...drift tube instrumented by 1 GSPS fADC and represents the outcome of balancing between cluster identification efficiency and high speed performance. The algorithm can be implemented in electronics boards serving multiple fADC channels as an online preprocessing stage for drift chamber signals.
Mesoporous TiO₂/SiO₂ catalysts were prepared in order to increase the post-harvest life of climacteric fruits and vegetables reducing ethylene concentration by photo-oxidation. TiO₂/SiO₂ powders were ...synthesized by sol-gel method using titanium isopropoxide Ti(OiPr)₄ and tetraethoxysilane Si(OC₂H₅)₄ as source of metal oxides. Mesoporous SiO₂ framework was used as catalyst support of nanostructured TiO₂ to enhance the photocatalytic efficiency. Different TiO₂/SiO₂ molar ratios were prepared through sol-gel process. A liquid-crystal template route allowed to obtain the mesoporous silica structure, and contemporary TiO₂ insertion in the silica framework. The X-ray diffraction (XRD) analysis demonstrated that silica insertion in TiO₂ framework inhibits the anatase to rutile phase transformation at higher sintering temperature. The photocatalytic efficiency of the catalysts was measured by the photo-oxidation of ethylene gas under UV light irradiation. Complete photo-oxidation of ethylene was observed after 24 h of reaction time. Results show that the silica framework increases the surface area of the composites and make crystalline anatase phase more stable at higher temperature.
Operation of a liquid-fed Direct Methanol Fuel Cell (DMFC) working at 145°C was demonstrated by using a composite membrane made of Nafion® ionomer and silica. The enhanced humidification conditions ...of the membrane–electrode (M&E) assembly allowed taking advantage of the high operation temperature with consequent speeding up of the methanol oxidation kinetics. A peak power density of 240 mW/cm−2 for an oxygen-fed cell was reached; the measured methanol cross-over rate was 4×10−6 moles min−1 cm−2. A physico-chemical characterization of the cell components is also reported.
The AMY experiment aims to measure the Microwave Bremsstrahlung Radiation (MBR) Twitter by air-showers secondary electrons accelerating in collisions with neutral molecules of the atmosphere. The ...measurements are performed at the Beam Test Facility (BTF) of Frascati INFN National Laboratories and the final purpose is to characterize the process to be used in a next generation detectors of ultra-high energy cosmic rays (up to 10 super(20)eV). We describe the experimental set-up and the first test measurement performed in November 2011.
ABSTRACT The events recorded by ARGO-YBJ in more than five years of data collection have been analyzed to determine the diffuse gamma-ray emission in the Galactic plane at Galactic longitudes 25° < l ...< 100° and Galactic latitudes . The energy range covered by this analysis, from ∼350 GeV to ∼2 TeV, allows the connection of the region explored by Fermi with the multi-TeV measurements carried out by Milagro. Our analysis has been focused on two selected regions of the Galactic plane, i.e., 40° < l < 100° and 65° < l < 85° (the Cygnus region), where Milagro observed an excess with respect to the predictions of current models. Great care has been taken in order to mask the most intense gamma-ray sources, including the TeV counterpart of the Cygnus cocoon recently identified by ARGO-YBJ, and to remove residual contributions. The ARGO-YBJ results do not show any excess at sub-TeV energies corresponding to the excess found by Milagro, and are consistent with the predictions of the Fermi model for the diffuse Galactic emission. From the measured energy distribution we derive spectral indices and the differential flux at 1 TeV of the diffuse gamma-ray emission in the sky regions investigated.
The trigger system of the ARGO-YBJ experiment Aloisio, A.; Branchini, P.; Catalanotti, S. ...
IEEE transactions on nuclear science,
2004-Aug., 2004-08-00, 20040801, Letnik:
51, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Astrophysical radiation with ground-based observatory at YangBaJing (ARGO-YBJ) is a ground-based cosmic ray detector presently under construction at the Yangbajing High Altitude Cosmic Ray Laboratory ...(4300 m a.s.l.), Lhasa, Tibet. The apparatus has been designed to detect air showers with an energy threshold of a few hundred GeV and it has a total active area of 6400 m/sup 2/. The full-coverage central carpet of 5772 m/sup 2/ is equipped with an array of resistive plate counters. This array is surrounded by a partially instrumented guard ring to improve the reconstruction of showers with the core falling outside the carpet. The ARGO trigger logic implements simple yet robust algorithms, based on the timing distribution of the hits and their multiplicity on the central carpet. In this paper, we describe the hardware architecture and the main features of the trigger system.
Aluminum nitride (AlN) thin films were deposited on SiO2/Si substrates by radiofrequency (RF) magnetron sputtering using an aluminum target. The influence of the deposition parameters – such as ...nitrogen concentration in the sputtering atmosphere, RF power, total working pressure and substrate bias voltage – on the structure, morphology and composition of the thin films was discussed. The structure was studied using X-ray diffraction (XRD), the morphology was studied using scanning electron microscopy (SEM) and the composition was studied using energy dispersive spectroscopy (EDS). These investigations showed that all of the films grew preferentially along the c-axis regardless of the deposition conditions, without the application of external heating, whereas the grain size and morphology strongly depended on the process parameters. Additional energy, which was supplied to the growing films by increasing the power or decreasing the working pressure, improved the crystallinity, but compressive stress was induced in the samples, thus resulting in a surface morphology evolution.
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•c-axis oriented AlN thin films were grown on silicon by RF magnetron sputtering•The influence of sputtering parameters on structure and morphology was investigated•The competition between nucleation rate and mobility determines physical properties
The extended TeV gamma-ray source ARGO J2031+4157 (or MGRO J2031+41) is positionally consistent with the Cygnus Cocoon discovered by Fermi-LAT at GeV energies in the Cygnus superbubble. Reanalyzing ...the ARGO-YBJ data collected from 2007 November to 2013 January, the angular extension and energy spectrum of ARGO J2031+4157 are evaluated. After subtracting the contribution of the overlapping TeV sources, the ARGO-YBJ excess map is fitted with a two-dimensional Gaussian function in a square region of 10degrees x 10degrees, finding a source extension sigma sub(ext)= 1degrees.8 + or - 0degrees.5. The observed differential energy spectrum is dN/dE = (2.5 + or - 0.4) x 10 super(-11) (E/1 TeV) super(-2.6+ or -0.3) photons cm super(-2) s super(-1) TeV super(-1), in the energy range 0.2-10 TeV. The angular extension is consistent with that of the Cygnus Cocoon as measured by Fermi-LAT and the spectrum also shows a good connection with the one measured in the 1-100 GeV energy range. These features suggest to identify ARGO J2031+4157 as the counterpart of the Cygnus Cocoon at TeV energies. The Cygnus Cocoon, located in the star-forming region of Cygnus X, is interpreted as a cocoon of freshly accelerated cosmic rays related to the Cygnus superbubble. The spectral similarity with supernova remnants (SNRs) indicates that the particle acceleration inside a superbubble is similar to that in an SNR. The spectral measurements from 1 GeV to 10 TeV allows for the first time to determine the possible spectrum slope of the underlying particle distribution. A hadronic model is adopted to explain the spectral energy distribution.
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