117,498 research outputs found
Determining the State of Activity of Transcrustal Magmatic Systems and Their Volcanoes
No full textPolygenetic volcanoes and calderas produce eruptions of a wide variety of magnitudes, chemistries, and recurrence times. Understanding the interplay between long- and short-term and deep and shallow processes associated with accumulation and transfer of eruptible magma is essential for assessing the potential for future eruptions to occur and estimating their magnitude, which remains one of the foremost challenges in the Earth sciences. We review literature and use existing data for emblematic volcanic systems to identify the essential data sets required to define the state of activity of volcanoes and their plumbing systems. We explore global eruptive records in combination with heat flux and other geological and geophysical data to determine the evolutionary stage of plumbing systems. We define a Volcanic Activity Index applicable to any volcano that provides an estimate of the potential of a system to erupt in the future, which is especially important for long-quiescent volcanoes.Magmatic plumbing systems that feed volcanic activity extend across Earth's crust and are long-lived at depth and ephemeral in their shallowest portions.We revise and update the definitions of active, quiescent, and extinct volcanoes based on physical proxies for the architecture, longevity, amount, and distribution of eruptible magma in the crust.We propose a Volcanic Activity Index, which provides a relative measure of the state of activity of a volcano with respect to all other volcanoes in the world.New imaging and monitoring strategies are required to improve our ability to detect lower and middle crust magmatic processes and forecast eruptions and their potential size
The temporal evolution of chemical and physical properties of magmatic systems
No full textExactly 100 years ago the great Canadian-born petrologist N. L. Bowen published two seminal works on the chemical differentiation of magmas in which he posed the basis for a physico-chemical understanding of the fractionation of crystals from melts in molten rock. A subsequent century of research and technological advances has enhanced our understanding of the physics and chemistry of magmatic systems and their temporal evolution. The image of sub-volcanic magmatic systems has evolved greatly in that time, from a simple ‘boiling vat’ concept of molten rock in which bubbles, crystals and melt separate gravitationally to a recognition that magma vats are relatively rare and that most magmatic systems spend much of their lifetime in a partially molten, or mushy, state. Real magmatic systems appear to be organized into a series of storage regions periodically connected by feeding structures transferring magma (and heat) at different fluxes. Magma fluxes between the different portions of this plumbing system, and the variation of the chemical and physical properties of magma as it rises through the crust, exert essential controls on the eruptive modalities of volcanoes and the geochemistry of their products. This book presents a collection of contributions that use petrology, geochemistry, geochronology and numerical modelling to identify the processes operating at different depths within magmatic systems and to characterize the fluxes of magma between them
A Novel Lightweight and Compact On-Line UPS Engine-Generator System
No full textNurnberg, Germany, 6-8 Giugno 200
Machine Learning Thermo-Barometry: Application to Clinopyroxene-Bearing Magmas
No full textWe introduce a new approach, based on machine learning, to estimate pre-eruptive temperatures and storage depths using clinopyroxene-melt pairs and clinopyroxene-only chemistry. The model is calibrated for magmas of a wide compositional range, it complements existing models, and it can be applied independently of tectonic setting. Additionally, it allows the identification of the main chemical exchange mechanisms occurring in response to pressure and temperature variations on the base of experimental data without a priori assumptions. After the validation process, performances are assessed with test data never used during the training phase. We estimate the uncertainty using the root-mean-square error (RMSE) and the coefficient of determination (R2). The application of the best performing algorithm (trained in the range 0–40 kbar and 952–1882 K) to clinopyroxene-melt pairs from primitive to extremely differentiated magmas of both subalkaline and alkaline systems returns a RMSE on the order of 2.6 kbar and 40 K for pressure and temperature, respectively. We additionally present a melt- and temperature-independent clinopyroxene barometer in the range 0–40 kbar, characterized by a RMSE of the order of 3 kbar. Tested for tholeiitic compositions in the range 0–10 kbar, the melt- and temperature-independent clinopyroxene barometer has a RMSE of 1.7 kbar. We finally apply the proposed approach to clinopyroxenes from Iceland, providing new, independent, insights about pre-eruptive storage depths of Icelandic volcanoes. The general applicability of this model will promote the comparison between the architecture of plumbing systems across tectonic settings and facilitate the comparison between petrologic and geophysical studies
Proprietà reologiche dei fusi naturali: i liquidi magmatici
No full textRiassunto: Questo contributo fornisce un aggiornamento sui più recenti studi
sperimentali e sui modelli di calcolo relativi allo studio della reologia dei fusi silicatici naturali
Burial history of the southern portion of the Tuscan Nappe (Northern Apennines) constrained by means of organic and inorganic paleo‐thermal indicators: implications for the orogenic wedge evolution
No full textCompact Permanent-Magnet Generator for Hybrid Vehicle Applications
No full textIn hybrid electric vehicle drivetrains an
electrical generator is coupled onto the shaft of an internal-combustion
engine in order to process either the entire or a given
fraction of the traction power required by the vehicle wheels. As
such an ICE-driven generator is being confined within the vehicle
hood and is exposed to heating resulting from ICE operation, high
compactness, totally enclosed construction, and suitable machine
cooling arrangement become challenging targets the generator
design must deal with. Due to unique characteristics such as
higher torque per volume and higher efficiency compared to other
machine topologies, the axial-field permanent-magnet machine
topology was selected for a 15-kW-at–4500-r/min-rated generator
prototype that would be utilized in a demonstrator of an HEV
drive train. This paper describes the original solutions adopted
for the design of such an HEV generator and reports experimental
results taken from the prototype machine
Experimental study on reducing cogging torque and core power loss in axial-flux permanent-magnet machines with slotted winding
No full textThe axial flux permanent magnet machine (AFPM) topology is suited for direct-drive applications, and due to their enhanced flux weakening capability AFPMs having slotted winding are the most promising candidate for use in wheel-motor drives. In consideration of that, this paper deals with an experimental study devoted to investigate a number of technical solutions to be used in AFPMs having a slotted winding in order to achieve substantial reduction of cogging torque and power loss in the stator core. To conduct such an experimental study, a laboratory machine was purposely built incorporating facilities that allow easy-to-achieve off-line modifications of the overall magnetic arrangement at the machine air gaps, such as magnet skewing, angular shifting between rotor discs and accommodation of either PVC or Somaloy wedges for closing the slot openings. The paper discusses experimental results and gives guidelines for the design of AFPMs with improved performance
Experimental Study on Reducing Cogging Torque and Core Power Loss in Axial-Flux Permanent-Magnet Machines with Slotted Winding
No full textThe axial-flux permanent-magnet machine (AFPM) topology is suited for direct-drive applications and, due to their enhanced flux-weakening capability, AFPMs having slotted windings are the most promising candidates for use in wheel-motor drives. In consideration of this, this paper deals with an experimental study devoted to investigate a number of technical solutions to be used in AFPMs having slotted windings in order to achieve substantial reduction of both cogging torque and no-load power loss in the machine. To conduct such an experimental study, a laboratory machine was purposely built incorporating facilities that allow easy-to-achieve offline modifications of the overall magnetic arrangement at the machine air gaps, such as magnet skewing, angular shifting between rotor discs, and accommodation of either PVC or Somaloy wedges for closing the slot openings. The paper discusses experimental results and gives guidelines for the design of AFPMs with improved performance
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