687,181 research outputs found
A GPGPU implementation of the discrete element method applied to modeling the dynamic particulate environment inside a tumbling mill
Includes bibliographical references.Tumbling mills have been an integral part of the comminution circuit for more than a century. With the advent of better computing, discrete element modeling (DEM) has taken on the challenge to model the dynamic particulate environment inside these devices in the search for understanding and hence improving the process of the size reduction of ore. This process represents a large percentage of the energy consumption of a mine. In this work, a discrete element modeling tool was built on a GPU-based platform to perform simulations on a single commodity hardware PC. With a view to elucidating the governing mechanisms inside such devices, the extreme capabilities of the GPU are utilised to provide performance and accurate simulation. The simulation environment offers control that can never be achieved in an experimental setup. Notwithstanding, when agreement with physical experiment is achieved, confidence can be gained in the computational results. In this work the foundations and framework for a large scale GPU based discrete element modeling tool have been built with an emphasis on strict physics requirements, rather than on performance or appearance. In this regard we demonstrate the validity of the GPU implementation of a Hertz-Mindlin-based contact model
Increase the Efficiency and Effectiveness of the Construction Field
These days with extreme responsibility and occupied life, many professionals face problems that result in the loss of their clients or certain overheads that spoil the process of satisfying the client. The proposed web application will be utilized by interior designers, garden designers, or architects. This proposed research doubtlessly goes about as a powerful device that can diminish the hole between modern organizations and clients notwithstandin8g other relevant business networks. It will help in picturing architectural plans, garden designs, and interior designs. A virtual model of genuine climate can be planned before its actual execution, it will permit inside originators to carry out their thought in the given work area essentially and afterward view it in genuine climate, it will likewise architects, interior designers, and garden designers to see their 3D perceptions on their 2D drawings [1]. The application depends on my discoveries of the client's assumptions for an expanded reality inside plan administration, a help which is a mix of different uses of web-based entertainment, increased reality (AR) and three-dimensional displaying that encases the idea of the home plan. This concentration particularly spans all clients of applicable organizations to the client escalated plan of an expanded reality. The paper gives you the internal profundity on how the expanded reality can be carried out to work with the planners and interior creators and garden designers too it talks about the calculation used to accomplish the functionalities. Furthermore, in this paper the architects and interior designers, and garden designers as welldiscuss the algorithm used to achieve the functionalities
Mainstream economics and the Austrian school: toward reunification
In this paper, I compare the methodology of the Austrian school to two alternative methodologies from the economic mainstream: the âorthodoxâ and revealed preference methodologies. I argue that Austrian school theorists should stop describing themselves as âextreme aprioristsâ (or writing suggestively to that effect), and should start giving greater acknowledgement to the importance of empirical work within their research program. The motivation for this dialectical shift is threefold: the approach is more faithful to their actual practices, it better illustrates the underlying similarities between the mainstream and Austrian research paradigms, and it provides a philosophical
foundation that is much more plausible in itself
Do Black Holes Destroy Information?
I review the information loss paradox that was first formulated by Hawking, and discuss possible ways of resolving it. All proposed solutions have serious drawbacks. I conclude that the information loss paradox may well presage a
revolution in fundamental physics
Robots with Lights: Overcoming Obstructed Visibility Without Colliding
Robots with lights is a model of autonomous mobile computational entities
operating in the plane in Look-Compute-Move cycles: each agent has an
externally visible light which can assume colors from a fixed set; the lights
are persistent (i.e., the color is not erased at the end of a cycle), but
otherwise the agents are oblivious. The investigation of computability in this
model, initially suggested by Peleg, is under way, and several results have
been recently established. In these investigations, however, an agent is
assumed to be capable to see through another agent. In this paper we start the
study of computing when visibility is obstructable, and investigate the most
basic problem for this setting, Complete Visibility: The agents must reach
within finite time a configuration where they can all see each other and
terminate. We do not make any assumption on a-priori knowledge of the number of
agents, on rigidity of movements nor on chirality. The local coordinate system
of an agent may change at each activation. Also, by definition of lights, an
agent can communicate and remember only a constant number of bits in each
cycle. In spite of these weak conditions, we prove that Complete Visibility is
always solvable, even in the asynchronous setting, without collisions and using
a small constant number of colors. The proof is constructive. We also show how
to extend our protocol for Complete Visibility so that, with the same number of
colors, the agents solve the (non-uniform) Circle Formation problem with
obstructed visibility
On The Content and Character of Pain Experience
Tracking representationalism explains the negative affective character of pain, and its capacity to motivate action, by reference to the representation of the badness for us of bodily damage. I argue that there is a more fitting instantiation of the tracking relation â the badness for us of extremely intense stimuli â and use this to motivate a non-reductive approach to the negative affective character of pain. The view of pain proposed here is supported by consideration of three related topics: the pain caused when the body is damaged, reparative pain, and the messenger-shooting objection to tracking representationalism
Extreme times for volatility processes
We present a detailed study on the mean first-passage time of volatility
processes. We analyze the theoretical expressions based on the most common
stochastic volatility models along with empirical results extracted from daily
data of major financial indices. We find in all these data sets a very similar
behavior that is far from being that of a simple Wiener process. It seems
necessary to include a framework like the one provided by stochastic volatility
models with a reverting force driving volatility toward its normal level to
take into account memory and clustering effects in volatility dynamics. We also
detect in data a very different behavior in the mean first-passage time
depending whether the level is higher or lower than the normal level of
volatility. For this reason, we discuss asymptotic approximations and confront
them to empirical results with a good agreement, specially with the ExpOU
model.Comment: 10, 6 colored figure
Formation Process of a Light Bridge Revealed with the Hinode Solar Optical Telescope
The Solar Optical Telescope (SOT) aboard HINODE successfully and continuously
observed a formation process of a light bridge in a matured sunspot of the NOAA
active region 10923 for several days with high spatial resolution. During its
formation, many umbral dots were observed emerging from the leading edges of
penumbral filaments, and intruding into the umbra rapidly. The precursor of the
light bridge formation was also identified as the relatively slow inward motion
of the umbral dots which emerged not near the penumbra, but inside the umbra.
The spectro-polarimeter on SOT provided physical conditions in the photosphere
around the umbral dots and the light bridges. We found the light bridges and
the umbral dots had significantly weaker magnetic fields associated with
upflows relative to the core of the umbra, which implies that there was hot gas
with weak field strength penetrating from subphotosphere to near the visible
surface inside those structures. There needs to be a mechanism to drive the
inward motion of the hot gas along the light bridges. We suggest that the
emergence and the inward motion are triggered by a buoyant penumbral flux tube
as well as the subphotospheric flow crossing the sunspot.Comment: 8 pages, 6 figures, accepted in the PASJ Hinode special issu
Improved SOT (Hinode mission) high resolution solar imaging observations
We consider the best today available observations of the Sun free of
turbulent Earth atmospheric effects, taken with the Solar Optical Telescope
(SOT) onboard the Hinode spacecraft. Both the instrumental smearing and the
observed stray light are analyzed in order to improve the resolution. The Point
Spread Function (PSF) corresponding to the blue continuum Broadband Filter
Imager (BFI) near 450 nm is deduced by analyzing i/ the limb of the Sun and ii/
images taken during the transit of the planet Venus in 2012. A combination of
Gaussian and Lorentzian functions is selected to construct a PSF in order to
remove both smearing due to the instrumental diffraction effects (PSF core) and
the large-angle stray light due to the spiders and central obscuration (wings
of the PSF) that are responsible for the parasitic stray light. A
Max-likelihood deconvolution procedure based on an optimum number of iterations
is discussed. It is applied to several solar field images, including the
granulation near the limb. The normal non-magnetic granulation is compared to
the abnormal granulation which we call magnetic. A new feature appearing for
the first time at the extreme- limb of the disk (the last 100 km) is discussed
in the context of the definition of the solar edge and of the solar diameter. A
single sunspot is considered in order to illustrate how effectively the
restoration works on the sunspot core. A set of 125 consecutive deconvolved
images is assembled in a 45 min long movie illustrating the complexity of the
dynamical behavior inside and around the sunspot.Comment: 15 pages, 22 figures, 1 movi
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