6,310 research outputs found
Audiomobiles, Sculptures and Conundrums
No full textRoberto Gerhard was a pioneer of electronic music in England creating a number of substantial concert, theatre and radio works from as early as 1954. Gerhard’s electronic music is one of the richest repositories for understanding the development of the composer’s late compositional technique. Apart from the Symphony no.3, ‘Collages’, none of Gerhard’s electronic music is published. This paper will discuss aspects of Gerhard’s electronic music, focusing on Audiomobiles (1958-59) and Sculptures (1963)
TDOA–based Localization in Two Dimensions: the Bifurcation Curve
No full textIn this paper, we complete the study of the geometry of the TDOA map that encodes the
noiseless model for the localization of a source from the range differences between three receivers
in a plane, by computing the Cartesian equation of the bifurcation curve in terms of the positions of
the receivers. From that equation, we can compute its real asymptotic lines. The present manuscript
completes the analysis of [12]. Our result is useful to check if a source belongs or is closed to the
bifurcation curve, where the localization in a noisy scenario is ambiguous
Roberto Gerhard’s Sound Compositions: A Historical-Philological Perspective. Archive, Process, Intent and reenactment
No full textThis research advances the current state of knowledge in the field of early tape music both empirically and methodologically. The purpose of this study is to evaluate the impact that the electronic medium exerted in the musical thinking of Roberto Gerhard, one of the most outspoken, prolific and influential composers in the Spanish diaspora whose musical legacy, for the most part unknown, is a major landmark in the early history of electroacoustic music. Gerhard’s personal tape collection, one of the largest historical archives of its kind reported in the literature, is exceptional for both its antiquity (50+-year-old tapes) and its abundance of production materials. Through the digitisation and analysis of the composer’s tape collection this research argues that the empirical study of audio documents sets out a basis for a broader understanding of textual processes. More specifically, the research demonstrates that the reconstruction of works based on magnetic tape sketches is a powerful method to advance the understanding of early tape music. This research also examines Gerhard’s sound compositions in relation to the post-war context in which they were composed. Finally, this research presents performance documentation that proposes an approach to the electroacoustic music repertoire in which creativity is not at odds with rigor and critical discernment demonstrating that archival study can be closely aligned to the concept of re-enactment
Filologia editoriale, Roberto Calasso in dialogo con Paola Italia e Francisco Rico
No full textPaola Italia e Francisco Rico intervengono sul libro di Roberto Calasso, presidente e fondatore di Adelphi Edizioni, L'impronta dell'editore, e discutono di problemi di filologia delle forme editoriali, dal punto di vista dell'autore, del lettore e dell'editore.Paola Italia and Francisco Ricos interview Roberto Calasso, Publisher, Writer, and Founder of Adelphi Edizioni, about his book: L'impronta dell'editore, talking about philology, publishing and editing, from the author, the reader and the publisher's point of view
Multistage metasomatism in ultrahigh-pressure mafic rocks from the North Dabie Complex (China)
No full textRelease of metamorphic fluids within the slab and/or from the slab to the mantle wedge in subduction environments can produce important metasomatic effects. Ultrahigh-pressure (UHP) metasomatised rocks represent ideal materials to study the element exchange at pressures corresponding to sub-arc depths in subduction zones. We present a petrologic and geochemical study of eclogites (s.l.) from the Dabie Mountains (China). The investigated samples were collected in the North Dabie Complex, where eclogite-facies rocks are significantly overprinted by granulite-facies metamorphism and partial melting. The studied eclogites are included in meta-lherzolitic bodies, which are in turn hosted by leucocratic gneisses. The textural relations among the various rock-forming minerals enabled us to identify several re-crystallisation stages. The peak (UHP) paragenesis consists of
garnet, clinopyroxene and rutile. UHP garnet and clinopyroxene display oriented inclusions of polycrystalline rods of rutile + ilmenite and of albite, K–Ba-feldspar and quartz, respectively. Garnet and clinopyroxene are both rimmed by an inclusion free zone that formed after the peak, still at high-pressure conditions. Such optical zoning does not correspond to a difference in major element concentrations between garnet core and rim. This observation provides evidence that the major element composition of garnet was reset during exhumation, thus preventing thermobarometric determination of peak metamorphic conditions. Further
decompression is documented by the formation of limited ilmenite+amphibole and granulite-facies coronas consisting of
clinopyroxene, orthopyroxene, plagioclase and amphibole around garnet. In order to investigate the stability of observed mineral parageneses, a series of reconnaissance piston cylinder synthesis experiments were carried out in an identical bulk composition.
The experimental study indicates that the peak metamorphic paragenesis is stable at P∼3.5 GPa and T≥750–800 °C. The
petrological study, combined with bulk-rock and mineral trace element analyses, provides evidence of intense metasomatism
affecting these eclogites. The bulk-rock major and trace element compositions indicate that the eclogites derive from basaltic protoliths with MORB and E-MORB affinity. Compared with such basalts, the studied rocks show strong depletion in SiO2 and alkalis and enrichment in MgO and FeO. These features likely derive from element exchange with ultramafic rocks prior to subduction, possibly related with the influx of Si-depleted and Mg-enriched fluids produced during the serpentinisation of the associated lherzolitic rocks. On the other hand, the trace element bulk-rock compositions show strong enrichment in Cs, Ba and Pb. The same characteristic enrichment and fractionation is recorded by peak metamorphic clinopyroxene but not in retrograde amphibole. Therefore, influx of crustal fluids transporting LILE and light elements must have occurred during subduction at UHP conditions. This stage likely records the tectonic coupling of the mafic–ultramafic rocks with the associated crustal rock units and provides evidence of LILE mobility between different slab components
Roberto Tibau and the process of making architecture
No full textEste estudo documenta a vida e a obra de Roberto José Goulart Tibau (1924-2003), arquiteto brasileiro. O objetivo fundamental - e mais importante - é reunir informações sobre os projetos e obras mais significativos desenvolvidos durante sua atividade profissional, tornando-os acessíveis através dessa pesquisa. O trabalho baseou-se em pesquisa bibliográfica, levantamento e registro das obras e projetos realizados, currículo profissional, e depoimento de Tibau, concedido ao autor, em 1998. Em Roberto Tibau e o fazer arquitetura são descritos os caminhos percorridos pelo arquiteto; o contexto histórico de sua formação e atuação profissional; a relação de sua produção arquitetônica com outras obras da época; e eventuais referências projetuais utilizadas na criação dos seus projetos. Este trabalho vem preencher uma lacuna bibliográfica considerável, trazendo à luz, a obra deste significativo arquiteto, que dedicou sua vida ao trabalho na prancheta, na qual deixou sua marca de humanista.This study documents the life and work of Roberto José Goulart Tibau (1924-2003), a Brazilian architect. It aims to collect information about the most significant projects developed during the years of his professional career, which will become available through this research. The present study based on bibliographical research, examination and registration of the projects executed by the architect, his resumé, and his testimonial to the author of this research, in 1998. In Roberto Tibau and the process of making architecture there is a description of the ways in which his projects were conceived; the historical context through his professional activity since graduation, the relation between his own production and the production of other architects of the same period, and the projecting references used for his creations. This research is also an attempt to fill a signicant bibliographical gap of architecture history in Brazil by bringing to light the work of this relevant architect, who dedicated his life to working on his drawing table, leaving to us his humanistic style
Polyphase inclusions in garnet–orthopyroxenite (Dabie Shan, China) as monitors for metasomatism and fluid-related trace element transfer in subduction zone peridotite
No full textThe ultrahigh-pressure (UHP) Maowu Ultramafic Complex (Dabie Shan, China) is hosted by coesite-bearing gneisses. Textural and geochemical data demonstrate that garnet-orthopyroxenites within the ultramafic complex derive from garnet-harzburgite precursors that have been metasomatised at peak UHP conditions (4.0 ± 1.0 GPa, 750 ± 50 °C) by the addition of a silica- and incompatible trace element-rich fluid phase (hydrous melt), sourced from the associated crustal rocks. This metasomatism produced poikilitic orthopyroxene with high LREE and Ni contents and inclusion-rich garnet porphyroblasts. Solid polyphase primary inclusions within peak metamorphic garnet display negative crystal shapes and constant volume ratios of infilling mineral phases. Experimental homogenisation of these inclusions at conditions close to the estimated metamorphic peak demonstrates that the polyphase inclusions derive from trapped solute-rich aqueous fluids. The trace element characteristics of the experimentally re-homogenised inclusions include high LREE contents, a pronounced enrichment in LILE, with spikes of Cs, Ba, Pb and high U/Th. The investigated UHP garnet-orthopyroxenites from Maowu represent a natural laboratory to constrain the trace element transfer from the subducted crust to the mantle wedge at sub-arc depths. The observed textures and chemical characteristics provide evidence for the infiltration of a felsic hydrous melt into garnet-peridotite, a circumstance comparable to expected interaction of sediment-derived melts with mantle wedge peridotites in subduction zones. The SiO2 and Al2O3 component of the hydrous melt reacted with olivine to form replacive orthopyroxene and new garnet. The neoblastic orthopyroxene is able to accommodate some of the LREE, whereas the H2O and LILE component of the melt were partitioned into a residual aqueous fluid phase. Remnants of such an aqueous fluid were trapped in the garnet and formed the polyphase inclusions. The trace element pattern of these inclusions is very similar to the incompatible element enrichment observed in arc lavas. We suggest that the residual fluid produced by the peridotite/hydrous melt reaction is able to transfer the characteristic LILE signature from the subducted sediments to the locus of partial melting in the mantle wedge. Moreover, this study provides evidence that polyphase inclusions are important tools for constraining the nature and composition of UHP fluid
A comprehensive analysis of the geometry of TDOA maps in localization problems
Get PDFIn this paper we consider the well-established problem of time
differences of arrival (TDOA)-based source localization and propose a
comprehensive analysis of its solution for arbitrary sensor measurement and
placement. More specifically, we define the TDOA map from the physical
space of source locations to the space of range measurements (TDOAs), in the
specific case of three receivers in 2D space. We then study the identifiability
of the model, giving a complete analytical characterization of the image of
this map and its invertibility. This analysis has been conducted in a completely
mathematical fashion, using many different tools which make it valid for every
sensor configuration. These results are the first step toward the solution of
more general problems involving, for example, a larger number of sensors,
uncertainty in their placement, or lack of synchronization
Roberto Bolaño, la memoria antiheroica del exilio chileno
No full textThis article discusses the personality and the work of the Chilean writer Roberto Bolaño in an attempt to expand on the relationship between the author and his homeland Chile. Even though Bolaño left Chile at an early age and lived in many countries throughout his life, he tried to regain his roots as reflected in the novels about the Chilean dictatorship, Estrella distante and Nocturno de Chile. The author also attempts to vindicate his own origin in his literary alterego Arturo Belano. Thus, this article will highlight and analyse the relation between Roberto Bolaño and Chile through the antiheroic vision given not only to the characters but also to the settings of the narratives.Este artículo se centra en la personalidad del escritor chileno Roberto Bolaño y su obra para profundizar en la relación existente entre el autor y Chile, su país de origen. Pese a haber abandonado el país siendo muy joven y a haber residido en otros países a lo largo de su vida, Bolaño nunca perdió el interés por recuperar sus raíces chilenas tanto como lo reflejan las novelas que dedica a la dictadura chilena, Estrella distante y Nocturno de Chile sobre todo, así como por reivindicar su propio origen a través de su álter ego literario Arturo Belano. En este artículo se señalarán y analizarán estas relaciones entre Roberto Bolaño y Chile a través de la visión antiheroica que el autor confiere tanto a los ambientes como a los personajes que articulan su narrativa
Innovative unattended SEM-EDS analysis for asbestos fiber quantification
No full textScanning electron microscopy with energy dispersive spectrometry (SEM-EDS) is the only affordable analytical
technique that can discriminate both morphology and elemental composition of inorganic fibers. SEM-EDS is
indeed required to quantify asbestos in confounding natural matrixes (e.g. ophiolites), but is also time-consuming,
operator dependent, and strongly relies on the stochastic distribution of the fibers on the filter surface.
The balance between analytical time/cost and the method sensibility allows only about 0.5% of the filter to be
analyzed, strongly affecting the statistical significance of results. To improve sensitivity and precision and enhance
productivity, an unattended quantitative measurement of the asbestos fibers by SEM-EDS is proposed. The
method identifies the particle shape first and determines their chemical composition later, saving EDS analytical
time. Our approach was tested on four asbestos standards and the relative error on replicated measurements
was< 10%. The proposed unattended method quantifies asbestos in natural confounding matrix, also with a
very low asbestos content
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