Compressive sampling for multispectral imaging in the vis-NIR-TIR: optical design of space telescopes

Micro-satellites equipped with multispectral payloads are now under development to acquire information on the radiation reflected and emitted from the earth in the vis-NIR-TIR bands. In this framework, we are studying different approaches based on the compressive sampling technique supported by innovative multispectral detectors, where the image sampling is performed on the telescope focal plane with a Digital Micromirror Device (DMD). We will describe in the paper the possibilities and the constraints given by the use of the DMD in the focal plane. The optical design of the telescope, relay system and detector in two different application cases will be provided

Bureaucratic rationalities and the prospect for party government

Digitised version produced by the EUI Library and made available online in 2020

Progetto a fatica di ruote dentate ad elevate prestazioni

The present paper deals with the experimental analysis and the numerical modelling of the fatigue performance of gears. Such components, used for the mechanical transmission of a racing car, are made in high strength steel and carburized, quenched, shot-peened and superfinished before exercise. After a brief introduction on the state of the art on fatigue design methods, up to present main results are presented. The influence of shot-peening and of superfinishing on the fatigue limit were studied, then the operative parameters of the peening treatment were optimized, and the whole S-N curve of the peened component was determined. On the basis of DOE statistical methods and of theoretical models, a methodology for fatigue design of highly loaded components was developed

Reliability Assessment of a Turbogenerator Coil Retaining Ring Based on Low Cycle Fatigue Data

Pierscienie ustalajace cewek turbogeneratora sa pasowane skurczowo na wirniku wokół cerek by zabezpieczyc je przed działaniem sił odsrodkowych. W typowych warunkach, sa one poddane narazeniom zmeczeniowym o malej liczbie cykli, przy czym kazdy cykl rozpoczyna sie od startu maszyny, a konczy przy jej zatrzymaniu. Przedmiotem artykułu jest wyznaczenie prawdopodobienstwa awarii pierscienia ustalajacego cewki. Rozwazanym uszkodzeniem jest pekniecie pierscienia spowodowane puchnieciem materiału pod wpływem naprezen wywołanych sila odsrodkowa. Ocena niezawodnosci przeprowadzona w tej pracy wykorzystuje dane wejsciowe wpływajace na obciazenie zmeczeniowe przy małej liczbie cykli i ich rozkłady stochastyczne. Dla rozwiazania problemu wyznaczono eksperymentalnie charakterystyki statyczne i krzywe cykli zmeczeniowych stosowanego materiału i zastosowano model statystyczny dla wyliczenia odpowiednich parametrów i ich odchylen standardowych. Na podstawie wyznaczonych rozkładów zmiennych estymuje sie prawdopodobienstwo uszkodzenia w formie dystrybuanty rozkładu. Wykorzystanyalgorytm obliczeniowy o duzej skutecznosci wykorzystuje metode ”zaawansowanej sredniej” (Advanced Mean Value). Uzyskane wyniki daja informacje o odpowiedzi materiału i stanie lokalnych naprezen i odkształcen w najbardziej obciazonych obszarach pierscienia ustalajacego cewki. Prawdopodobienstwo uszkodzenia, wyznaczone na koniec okresu eksploatacji maszyny, wynosi 10-12 i jest porównywalne z wartosciami referencyjnymi dla innych konstrukcji mechanicznych i lotniczych narazonych na zmeczenie

Experimental Stress Analysis Syllabus and Course Design

According to tradition, an Experimental Analysis Course has the task of presenting the main methods of experimental analysis in the awareness that stress and strain are responsible for a variety of phenomena of structural failures of modern artefacts, which are due to several causes such as load estimates, insufficient stress analysis and lack of data on materials. The discipline was created as a selection of tools for finding results when analytical solutions did not formerly exist, but today it has the new task of clarifying the limitations of analytical theories, of validating numerical results, of building the fundaments of phenomenological theories and simulations and of allowing reliability and life extension estimations especially in case of incomplete data and badly posed problems

Low Cycle Fatigue behaviour and anisotropy of two steels for turbogenerator coil retaining rings and rotors

Turbogenerator rotors and coil retaining rings (CRR) are typically subjected to low cycle fatigue (LCF). The rotor contains uniformly spaced longitudinal slots, where copper conductors are packed: at the nominal speed of 3000 rpm a great centrifugal force acts on the copper conductors that must be restrained by CRRs, shrunk fitted onto the body over the coils. Thus, at each on-off transitory (10,000 \u2013 15,000 in the whole machine life) both the rotor and the CRR are subjected to a cyclic load. Several contributions report the mechanical properties of the typically used steels for rotor and CRR manufacturing, but none deals with their characterization under LCF in strain controlled conditions, while investigations on the anisotropy were performed just on CRR steels in load controlled conditions. This research aims at determining the main parameters describing the LCF performance of two widely applied steels for rotors and CRRs, investigating also the anisotropy in the dynamic behaviour: for this purpose an extensive experimental campaign was carried out on specimens machined (in the tangential and radial directions) from prolongations of trial rotors and CRRs. An original approach was used for misalignment compensation, strain control and data recording, sensitivity analyses were finally performed on results

REGIOSELECTIVE AMINATION OF POLYUNSATURATED ETHERS

(Ethoxycarbonyl)nitrene (NCO2Et) adds selectively to methyl neryl ether, geranyl methyl ether, and allyl neryl ether. For all the substrates the main product (up to 50%) is the aziridine deriving from addition to the double bond remote from the oxygen atom. Competition experiments point to a different reactivity of the two kind of double bonds and these results are compared with those reported for similar substrates in other addition reactions