Analysis of pressure blips in aft-finocyl solid rocket motor

Ballistic anomalies have frequently occurred during the firing of several solid rocket motors (SRMs) (Inertial Upper Stage, Space Shuttle Redesigned SRM (RSRM) and Titan IV SRM Upgrade (SRMU)), producing even relevant and unexpected variations of the SRM pressure trace from its nominal profile. This paper has the purpose to provide a numerical analysis of the following possible causes of ballistic anomalies in SRMs: an inert object discharge, a slag ejection, and an unexpected increase in the propellant burning rate or in the combustion surface. The SRM configuration under investigation is an aft-finocyl SRM with a first-stage/small booster design. The numerical simulations are performed with a quasi-one-dimensional (Q1D) unsteady model of the SRM internal ballistics, properly tailored to model each possible cause of the ballistic anomalies. The results have shown that a classification based on the head-end pressure (HEP) signature, relating each other the HEP shape and the ballistic anomaly cause, can be made. For each cause of ballistic anomalies, a deepened discussion of the parameters driving the HEP signatures is provided, as well as qualitative and quantitative assessments of the resultant pressure signals

Corrosion of bronzes by extended wetting with single versus mixed acidic pollutants

The corrosion of bronzes was examined in the context of single-acid versus mixed-acid (as in urban acid rain) solutions. Two bi-component bronzes (copper with either 3% Sn or 7% Sn) that closely represent those of historic artifacts were immersed for five weeks in conditions designed to replicate those experienced by statues and ornaments in cities where rainfall and humidity constantly produce an electrolyte layer on the surfaces of bronzes. Ions, acids, and particles of pollutants can dissolve in this layer, resulting in a variety of harsh corrosion processes. The kinetics of corrosion and the properties of the resulting patinas were monitored weekly by electrochemical impedance spectroscopy and open-circuit potential measurements. The sizes and appearances of the corrosion products were monitored and used to estimate the progress of the corrosion, whose crystalline structures were visualized using scanning electron microscopy with energy dispersive spectroscopy, identified by X-ray diffraction, and characterized by spectrocolorimetry. The electrochemical measurements demonstrated that greater damage (in terms of color change and corrosion product formation) did not correspond to deficiencies in protection. The mixed-acid solution did not corrode the bronzes, as would be expected from the additive effects of the single acids. The postulated mechanisms of metal dissolution appear to be specific to a particular bronze alloy, with the tin component playing an important role

Instrument and data analysis challenges for imaging spectropolarimetry

The next generation of solar telescopes will enable us to resolve the fundamental scales of the solar atmosphere, i.e., the pressure scale height and the photon mean free path. High-resolution observations of small-scale structures with sizes down to 50 km require complex post-focus instruments, which employ adaptive optics (AO) and benefit from advanced image restoration techniques. The GREGOR Fabry-Perot Interferometer (GFPI) will serve as an example of such an instrument to illustrate the challenges that are to be expected in instrumentation and data analysis with the next generation of solar telescopes.Comment: 4 pages, 1 figure, accepted for publication in Astronomische Nachrichten/AN, special issue of the 1st EAST-ATST Workshop: "Science with large solar telescopes" in Freiburg, Germany, October 14-16, 200

Nuove riflessioni sul canone teatrale del madrigale drammatico

The article deals with some case studies on theatrical spectacles with music, as the “mascherate” composed by Orazio Vecchi in Modena. Further, it examines some excerpts of the sixteenth-century Italian polyphony, which have not written for the stage, thus recreating the musical landscape inspired by popular songs and the onomatopoeic lexicon drawn from pastoral dramas and comedies before Vecchi’s "Amphiparnaso" (1597). In the second part, applying the criteria of narratology, the author analyses the works of Alessandro Striggio ("Il cicalamento delle donne al bucato", 1567), Gaspare Torelli ("I fidi amanti", 1600) and Adriano Banchieri ("La pazzia senile", 1607 2edn., "La prudenza giovenile", 1607, "La saviezza giovenile", 1628). This approach to the matter is required by the plot of the mentioned madrigal comedies, as suggested by stage directions, subtitles and various details joined to the introductions and intermedi. The co-existence of musical and stage traits acquires more evidence in Banchieri’s oeuvre, in which various accurate references to the scenarios occur, particularly referred to the staging of "Prudenza Giovenile". L’articolo presenta alcuni casi di testi di carattere teatrale posti in polifonia, di citazioni di canti popolari o polifonici usati in spettacoli teatrali ed elenca le concordanze tra le mascherate messe in scena da Orazio Vecchi a Modena e i brani da lui mandati successivamente in stampa. Ciò allo scopo di dimostrare che la creazione di un paesaggio sonoro di ascendenza rappresentativa è un patrimonio comune derivato dalla favola pastorale e dalla commedia, anteriore alla rivoluzionaria opera compiuta da Vecchi con l’"Amphiparnaso". Nella seconda parte l’autore ricorre alla narratologia per esaminare le composizioni di Alessandro Striggio ("Il cicalamento delle donne al bucato", 1567), di Gaspare Torelli ("I fidi amanti", 1600) e di Adriano Banchieri ("La pazzia senile", ed. 1607, "La prudenza giovenile", 1607, "La saviezza giovenile", 1628), poiché esse contengono didascalie e intermedi che funzionano come veri e propri scenari di teatro. In questo senso rivestono particolare importanza le indicazioni di Banchieri per un’autentica rappresentazione della "Prudenza giovenile"

El nacimiento de la historiografia musical en Italia durante la segunda mitad del siglo XIX y los problemas del metodo historico

The article explains the role, the scope and the methods of the 19th-Century music historiography in Italy in comparison to positivism, which fostered a scientific methodology to reshape history of arts and literature. Aiming to discover the value and the ideal place of musical oeuvre, some historiographers described the periodization by means of different paradigms and philosophies, drawn from the theory of evolution of Darwin and Spencer, and the positivism of Hyppolite Taine. Some essays, such as "L’evoluzione nella musica" (1898, 1911 enlarged ed.) and the monograph "Riccardo Wagner" (1890), written by Oscar Chilesotti and Luigi Torchi, are examined at the light of those philosophies. In these essays the focus of the research shifts from the biography of composers to the history of music, showing the relationship with national traditions

Figurations of the infra-ordinary. Play and urban imaginaries in Rimini Protokoll’s documentary theatre practice

Early June 2008. It’s a sunny and gorgeously warm day in Berlin. With a friend, I reach the Hebbel Am Uffer Theatre twenty minutes before the beginning of Call Cutta in a box, a piece by Rimini Protokoll, a label for the documentary theatre of Helgard Haug, Stefan Kaegi and Daniel Wetzel. In the brochure, we read that there are time slots for two spectators at once. We buy our tickets and move towards the theatre’s entrance. But apparently, there is no entrance. Instead, a huge guy looks at me kindly indicating the map in my hand and explaining that the show is not in the theatre but few metres away in a glass corporate building by the river

Automazione di un manipolatore per impianti di smontaggio elettrodomestici

L’obiettivo del presente lavoro di tesi è stato quello di automatizzare un macchinario esistente: il manipolatore per impianti di disassemblaggio di elettrodomestici giunti a fine vita, realizzato dal Dipartimento di Ingegneria Meccanica Nucleare e della Produzione della Facoltà di Ingegneria dell’Università di Pisa presso la sezione Produzione. Il macchinario, comandato manualmente da un operatore addetto tramite una pulsantiera con dei joystick, è in grado di afferrare una lavatrice e di movimentarla, consentendole di assumere la posizione più adatta per effettuare lo smontaggio. Affinché il processo di recupero dei materiali dall’elettrodomestico dismesso sia economicamente accettabile è necessario che il costo della manodopera, strettamente legato al tempo del processo di smontaggio, venga ridotto il più possibile. Questo obiettivo può essere raggiunto automatizzando la movimentazione della macchina. L’automazione del manipolatore è stata effettuata utilizzando un PLC, dotato, fra l’altro, di moduli per il controllo degli spostamenti . E’ stata comunque mantenuta la possibilità di comandare manualmente la macchina, modificando lo schema elettrico esistente in modo da poter escludere completamente la parte di controllo automatico. Per l’automazione della macchina è stato necessario effettuare la scelta dei trasduttori di spostamento dei tre assi del manipolatore, progettare e realizzare le interfacce con l’apparecchiatura esistente, istallare il PLC ed eseguire i cablaggi con i trasduttori e gli attuatori. Si è proceduto infine al settaggio dei parametri di funzionamento ed alla programmazione del PLC per la realizzazione del posizionamento in automatico, verificando quindi la possibilità di ottenere una gestione completamente automatica della movimentazione del gripper

Enhanced Self-organized Dewetting of Ultrathin Polymer Films under Water-organic Solutions: Fabrication of Sub-micron Spherical Lens Arrays

Field-induced self-organized patterning in ultrathin (< 100 nm) polymer films produces resolutions of the order of 10 {\mu}m or more because of the high energy penalty for the surface deformations on small scales. We propose here a very simple but versatile method to fabricate sub-micron (~100 nm) ordered and tunable polymeric structures by self-organized room temperature dewetting of ultrathin polystyrene films by minimizing the surface tension limitation. We illustrate this technique by fabricating sub-micron lens arrays of tunable curvature. This is achieved by switching to controlled room temperature dewetting under an optimal mix of water, acetone and methyl-ethyl ketone (MEK). Organic solvents used decrease the glass transition temperature, greatly decrease the interfacial tension, intensify the field and increase the contact angle/aspect ratio of the resulting tunable nano-structures, without a concurrent solubilization of PS owing to water being the majority phase in the outside mixture.Comment: 13 pages and 5 figure