54 research outputs found
Family and Labour in Corfu Manufacturing, 1920–1944
This article concentrates on the relation between labour and family in thesecondary sector of production of Corfu. It argues that family was crucial in forming the main characteristics of the labour force. The familial division of labour according to gender and age is examined not only as a decisive determinant in the categorisation of work positions as skilled and unskilled but also as a factor that defined the temporality or permanence of labour. It also focuses on the role of local and family networks and their effect on the labour market. These questions, thoroughly discussed by labour historians, will be applied to the case of Corfu, in an effort to complete the Greek paradigm
Improving NeRF Quality by Progressive Camera Placement for Unrestricted Navigation in Complex Environments
Neural Radiance Fields, or NeRFs, have drastically improved novel view
synthesis and 3D reconstruction for rendering. NeRFs achieve impressive results
on object-centric reconstructions, but the quality of novel view synthesis with
free-viewpoint navigation in complex environments (rooms, houses, etc) is often
problematic. While algorithmic improvements play an important role in the
resulting quality of novel view synthesis, in this work, we show that because
optimizing a NeRF is inherently a data-driven process, good quality data play a
fundamental role in the final quality of the reconstruction. As a consequence,
it is critical to choose the data samples -- in this case the cameras -- in a
way that will eventually allow the optimization to converge to a solution that
allows free-viewpoint navigation with good quality. Our main contribution is an
algorithm that efficiently proposes new camera placements that improve visual
quality with minimal assumptions. Our solution can be used with any NeRF model
and outperforms baselines and similar work
3D Gaussian Splatting for Real-Time Radiance Field Rendering
Radiance Field methods have recently revolutionized novel-view synthesis of
scenes captured with multiple photos or videos. However, achieving high visual
quality still requires neural networks that are costly to train and render,
while recent faster methods inevitably trade off speed for quality. For
unbounded and complete scenes (rather than isolated objects) and 1080p
resolution rendering, no current method can achieve real-time display rates. We
introduce three key elements that allow us to achieve state-of-the-art visual
quality while maintaining competitive training times and importantly allow
high-quality real-time (>= 30 fps) novel-view synthesis at 1080p resolution.
First, starting from sparse points produced during camera calibration, we
represent the scene with 3D Gaussians that preserve desirable properties of
continuous volumetric radiance fields for scene optimization while avoiding
unnecessary computation in empty space; Second, we perform interleaved
optimization/density control of the 3D Gaussians, notably optimizing
anisotropic covariance to achieve an accurate representation of the scene;
Third, we develop a fast visibility-aware rendering algorithm that supports
anisotropic splatting and both accelerates training and allows realtime
rendering. We demonstrate state-of-the-art visual quality and real-time
rendering on several established datasets.Comment: https://repo-sam.inria.fr/fungraph/3d-gaussian-splatting
Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagetic anomalies prior to the L'Aquila earthquake as pre-seismic ones. Part I
Ultra low frequency, kHz and MHz electromagnetic anomalies were recorded
prior to the L'Aquila catastrophic earthquake that occurred on April 6, 2009.
The main aims of this contribution are: (i) To suggest a procedure for the
designation of detected EM anomalies as seismogenic ones. We do not expect to
be possible to provide a succinct and solid definition of a pre-seismic EM
emission. Instead, we attempt, through a multidisciplinary analysis, to provide
elements of a definition. (ii) To link the detected MHz and kHz EM anomalies
with equivalent last stages of the L'Aquila earthquake preparation process.
(iii) To put forward physically meaningful arguments to support a way of
quantifying the time to global failure and the identification of distinguishing
features beyond which the evolution towards global failure becomes
irreversible. The whole effort is unfolded in two consecutive parts. We clarify
we try to specify not only whether or not a single EM anomaly is pre-seismic in
itself, but mainly whether a combination of kHz, MHz, and ULF EM anomalies can
be characterized as pre-seismic one
Cooperation between expert knowledge and data mining discovered knowledge: Lessons learned
Expert systems are built from knowledge traditionally elicited from the human expert. It is precisely knowledge elicitation from the expert that is the bottleneck in expert system construction. On the other hand, a data mining system, which automatically extracts knowledge, needs expert guidance on the successive decisions to be made in each of the system phases. In this context, expert knowledge and data mining discovered knowledge can cooperate, maximizing their individual capabilities: data mining discovered knowledge can be used as a complementary source of knowledge for the expert system, whereas expert knowledge can be used to guide the data mining process. This article summarizes different examples of systems where there is cooperation between expert knowledge and data mining discovered knowledge and reports our experience of such cooperation gathered from a medical diagnosis project called Intelligent Interpretation of Isokinetics Data, which we developed. From that experience, a series of lessons were learned throughout project development. Some of these lessons are generally applicable and others pertain exclusively to certain project types
Critical features in electromagnetic anomalies detected prior to the L'Aquila earthquake
Electromagnetic (EM) emissions in a wide frequency spectrum ranging from kHz
to MHz are produced by opening cracks, which can be considered as the so-called
precursors of general fracture. We emphasize that the MHz radiation appears
earlier than the kHz in both laboratory and geophysical scale. An important
challenge in this field of research is to distinguish characteristic epochs in
the evolution of precursory EM activity and identify them with the equivalent
last stages in the earthquake (EQ) preparation process. Recently, we proposed
the following two epochs/stages model: (i) The second epoch, which includes the
finally emerged strong impulsive kHz EM emission is due to the fracture of the
high strength large asperities that are distributed along the activated fault
sustaining the system. (ii) The first epoch, which includes the initially
emerged MHz EM radiation is thought to be due to the fracture of a highly
heterogeneous system that surrounds the family of asperities. A catastrophic EQ
of magnitude Mw = 6.3 occurred on 06/04/2009 in central Italy. The majority of
the damage occurred in the city of L'Aquila. Clear kHz - MHz EM anomalies have
been detected prior to the L'Aquila EQ. Herein, we investigate the seismogenic
origin of the detected MHz anomaly. The analysis in terms of intermittent
dynamics of critical fluctuations reveals that the candidate EM precursor: (i)
can be described in analogy with a thermal continuous phase transition; (ii)
has anti-persistent behaviour. These features suggest that the emerged
candidate precursor could be triggered by microfractures in the highly
disordered system that surrounded the backbone of asperities of the activated
fault. We introduce a criterion for an underlying strong critical behavior.Comment: 8 pages, 6 figure
Scaling similarities of multiple fracturing of solid materials
It has recently reported that electromagnetic flashes of low-energy <IMG WIDTH='12' HEIGHT='29' ALIGN='MIDDLE' BORDER='0' src='http://www.nonlin-processes-geophys.net/11/137/2004/npg-11-137-img1.gif' ALT=''>-rays emitted during multi-fracturing on a neutron star, and electromagnetic pulses emitted in the laboratory by a disordered material subjected to an increasing external load, share distinctive statistical properties with earthquakes, such as power-law energy distributions (Cheng et al., 1996; Kossobokov et al., 2000; Rabinovitch et al., 2001; Sornette and Helmstetter, 2002). The neutron starquakes may release strain energies up to <IMG WIDTH='32' HEIGHT='16' ALIGN='BOTTOM' BORDER='0' src='http://www.nonlin-processes-geophys.net/11/137/2004/npg-11-137-img2.gif' ALT=''>erg, while, the fractures in laboratory samples release strain energies approximately a fraction of an erg. An earthquake fault region can build up strain energy up to approximately <IMG WIDTH='32' HEIGHT='16' ALIGN='BOTTOM' BORDER='0' src='http://www.nonlin-processes-geophys.net/11/137/2004/npg-11-137-img3.gif' ALT=''>erg for the strongest earthquakes. Clear sequences of kilohertz-megahertz electromagnetic avalanches have been detected from a few days up to a few hours prior to recent destructive earthquakes in Greece. A question that arises effortlessly is if the pre-seismic electromagnetic fluctuations also share the same statistical properties. Our study justifies a positive answer. Our analysis also reveals 'symptoms' of a transition to the main rupture common with earthquake sequences and acoustic emission pulses observed during laboratory experiments (Maes et al., 1998)
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