Progetto e realizzazione di una scheda elettronica per applicazioni di spettroscopia di assorbimento con tecnica TDLAS

Lo studio svolto in questa tesi è indirizzato alla progettazione e realizzazione di due schede elettroniche per misure di spettroscopia. La prima è un driver di corrente con controllo di temperatura per laser VCSEL, mentre la seconda è una scheda di controllo, la quale genera il pattern di modulazione per il laser e acquisisce il segnale analogico proveniente dal fotodiodo. Questi circuiti elettronici sono necessari per poter effettuare delle misure di spettroscopia di assorbimento con tecnica TDLAS o WMS. Lo scopo del lavoro di tesi è realizzare delle schede elettroniche custom per l’utilizzo in strumentazione da banco e successivamente in ambiente industriale. Il driver di corrente è stato sottoposto ad alcuni test per provarne e garantirne il corretto funzionamento. Si è verificata la generazione dell’onda triangolare, del limite di corrente, il controllo di temperatura ed infine si è svolta una misura di spettroscopia. Le varie prove sono servite, oltre a testarne il funzionamento, ad apportare ulteriori piccole migliorie alla scheda realizzata. Per la scheda di generazione e acquisizione dei segnali si è costruito un prototipo e scritto una parte del software che gestisce la scheda. Nel prossimo futuro questa scheda sarà integrata per funzionare insieme al driver di corrente progettatoopenEmbargo per motivi di segretezza e di proprietà dei risultati e informazioni sensibil

History at School Outline of Textbooks

openLo studio della storia a scuola è molto importante per far crescere i futuri cittadini, così come la normativa impone. Questo lavoro ha l'obbiettivo di studiare come gli odierni manuali sono strutturati e se siano davvero efficaci per l’insegnamento della storia, sapendo che ogni studente ha diverse esigenze e potenzialità. I manuali di oggi, infatti, devono proporre un insegnamento flessibile così da permettere al docente di utilizzare al meglio il testo e rendere gli studenti sicuri nella conoscenza della materia. Ovviamente questo è possibile solo dopo aver valutato il contesto scolastico e dopo aver accuratamente scelto il manuale più adatto alla classe cui è destinato. A tale scopo, sono stati selezionati tre diversi manuali di tre diversi editori per analizzarli e compararli tra loro e valutare che siano un valido strumento per gli ultimi tre anni della scuola superiore. Sono stati verificati gli esercizi, il design grafico, la leggibilità linguistica e le caratteristiche storiografiche di ogni libro, sperando che questo elaborato possa aiutare a migliorare sempre di più la didattica.Studying History at school is important to build and create future citizens, as the law recommend. This work has the goal to study how today’s textbooks are built and if they are actually effective in teaching history, knowing that every student has different needs and competences. Today’s textbooks, indeed, should have a flexible teaching to allow the teacher to use it at its best and to make students confident in the subject. Of course this is possible only after an evaluation of the school environment and after having wisely matched the more appropriate book to the class. To do so, three different textbooks have been taken into consideration of three different publisher to analyse and compare them and see if they are a valid instrument for the last three years of high school. Exercises, the graphic design, the language’s legibility and the hystoriographic features of every books have been valued hoping that this work may be a little help to improve the teaching process

Exergy analysis of solar desalination systems based on passive multi-effect membrane distillation

Improving the efficiency and sustainability of water treatment technologies is crucial to reduce energy consumption and environmental pollution. Solar-driven devices have the potential to supply off-grid areas with freshwater through a sustainable approach. Passive desalination driven by solar thermal energy has the additional advantage to require only inexpensive materials and easily maintainable components. The bottleneck to the widespread diffusion of such solar passive desalination technologies is their lower productivity with respect to active ones. A completely passive, multi-effect membrane distillation device with an efficient use of solar energy and thus a remarkable enhancement in distillate productivity has been recently proposed. The improved performance of this distillation device comes from the efficient exploitation of low-temperature thermal energy to drive multiple distillation processes. In this work, we analyze the proposed distillation technology by a more in-depth thermodynamic detail, considering a Second Law analysis. We then report a detailed exergy analysis, which allows to get insights on the production of irreversibilities in each component of the assembly. These calculations provide guidelines for the possible optimization of the device, since simple changes in the original configuration may easily yield up to a 46% increase in the Second Law efficiency. Keywords: Sustainability, Exergy analysis, Water treatment, Membrane distillation, Solar energ

The new HMI beamline MAGS an instrument for hard X ray diffraction at BESSY

The Hahn Meitner Institute Berlin is operating the new hard X ray diffraction beamline MAGS at the Berlin synchrotron radiation source BESSY. The beamline is intended to complement the existing neutron instrumentation at the Berlin Neutron Scattering Centre. The new beamline uses a 7 T multipole wiggler to produce photon fluxes in the 1011 1012 photons s 100 mA 0.1 bandwidth range at energies from 4 to 30 keV at the experiment. It has active bendable optics to provide flexible horizontal and vertical focusing and to compensate the large heat load from the wiggler source. The experimental endstation consists of a six circle Huber diffractometer which can be used with an additional polarization analyser and different sample environments. The beamline is intended for single crystal diffraction and resonant magnetic scattering experiments for the study of ordering phenomena, phase transitions and materials scienc

Ultra precise characterization of LCLS hard X ray focusing mirrors by high resolution slope measuring deflectometry

We present recent results on the inspection of a first diffractionlimited hard X ray Kirkpatrick Baez KB mirror pair for the Coherent Xray Imaging CXI instrument at the Linac Coherent Light Source LCLS . The full KB system mirrors and holders was under inspection by use of high resolution slope measuring deflectometry. The tests confirmed that KB mirrors of 350mm aperture length characterized by an outstanding residual figure error of lt;1 nm rms has been realized. This corresponds to the residual figure slope error of about 0.05 amp; 956;rad rms, unprecedented on such long elliptical mirrors. Additional measurements show the clamping of the mirrors to be a critical step for the final shape preserving installation of such outstanding optic

1 m long multilayer-coated deformable piezoelectric bimorph mirror for adjustable focusing of high-energy X-rays

The Diamond Light Source (DLS) beamline I15-1 measures atomic pair distribution functions (PDF) using scattering of 40-80 keV X-rays. A unique focusing element was needed to condense these X-rays from an initial large cross section (11.0 mm H × 4.2 mm V) into a required spot size of FWHM ≈680 μm (H) × 20 μm (V) at a variable position between the sample and the detector. The large numerical aperture is achieved by coating a silicon substrate over 1 m long with three multilayer stripes of Bragg angle 4.2 mrad. One stripe selects X-rays of each energy 40.0, 65.4, and 76.6 keV. Sixteen piezoelectric bimorph actuators attached to the sides of the mirror substrate adjusted the reflecting surface’s shape. Focal spots of vertical width < 15 μm were obtained at three positions over a 0.92 m range, with fast, easy switching from one focal position to another. Minimized root mean square slope errors were close to 0.5 μrad after subtraction of a uniform curvature. Reflectivity curves taken along each stripe showed consistent high peaks with generally small angular variation of peak positions. This is the first application of a 1 m long multilayercoated bimorph mirror at a synchrotron beamline. Data collected with its help on a slice of a lithium ion battery’s cathode are presented

Sustainable polyethylene fabrics with engineered moisture transport for passive cooling

Polyethylene (PE) has emerged recently as a promising polymer for incorporation in wearable textiles owing to its high infrared transparency and tuneable visible opacity, which allows the human body to cool via thermal radiation, potentially saving energy on building refrigeration. Here, we show that single-material PE fabrics may offer a sustainable, high-performance alternative to conventional textiles, extending beyond radiative cooling. PE fabrics exhibit ultra-light weight, low material cost and recyclability. Industrial materials sustainability (Higg) index calculations predict a low environmental footprint for PE fabrics in the production phase. We engineered PE fibres, yarns and fabrics to achieve efficient water wicking and fast-drying performance which, combined with their excellent stain resistance, offer promise in reducing energy and water consumption as well as the environmental footprint of PE textiles in their use phase. Unlike previously explored nanoporous PE materials, the high-performance PE fabrics in this study are made from fibres melt spun and woven on standard equipment used by the textile industry worldwide and do not require any chemical coatings. We further demonstrate that these PE fibres can be dry coloured during fabrication, resulting in dramatic water savings without masking the PE molecular fingerprints scanned during the automated recycling process

Melting of tantalum at high pressure determined by angle dispersive x-ray diffraction in a double-sided laser-heated diamond-anvil cell

The high pressure and high temperature phase diagram of Ta has been studied in a laser-heated diamond-anvil cell (DAC) using x-ray diffraction measurements up to 52 GPa and 3800 K. The melting was observed at nine different pressures, being the melting temperature in good agreement with previous laser-heated DAC experiments, but in contradiction with several theoretical calculations and previous piston-cylinder apparatus experiments. A small slope for the melting curve of Ta is estimated (dTm/dP = 24 K/GPa at 1 bar) and a possible explanation for this behaviour is given. Finally, a P-V-T equation of states is obtained, being the temperature dependence of the thermal expansion coefficient and the bulk modulus estimated.Comment: 31 pages, 8 figures, to appear in J.Phys.:Cond.Matte