484 research outputs found
A visual analysis of the usage efficiency of library books
The monographic collections in academic libraries have undergone a period of tremendous growth in volume, in subject diversity, and in formats during the recent several decades. Readers may find it difficult to prioritize which book(s) should be borrowed for a specific purpose. The log data of book loan record may serve as a visible indicator for the more sought-after books by the readers. This paper describes our experimental efforts in works in a university library setting. The visual analysis is thought to provide an effective way to extract the book usage information, which may yield new insights into a host of other related technical as well as user behavior issues. Initial experiment has demonstrated that the proposed approach as articulated in this article can actually benefit end-users as well as library collection development personnel in their endeavor of book selections with effective measure.</p
Why torus-unstable solar filaments experience failed eruption?
To investigate the factors that control the success and/or failure of solar
eruptions, we study the magnetic field and 3-Dimensional (3D) configuration of
16 filament eruptions during 2010 July - 2013 February. All these events, i.e.,
erupted but failed to be ejected to become a coronal mass ejection (CME), are
failed eruptions with the filament maximum height exceeding . The
magnetic field of filament source regions is approximated by a potential field
extrapolation method. The filament 3D configuration is reconstructed from three
vantage points by the observations of STEREO Ahead/Behind and SDO spacecraft.
We calculate the decay index at the apex of these failed filaments and find
that in 7 cases, their apex decay indexes exceed the theoretical threshold
() of the torus instability. We further determine the
orientation change or rotation angle of each filament top during the eruption.
Finally, the distribution of these events in the parameter space of rotation
angle versus decay index is established. Four distinct regimes in the parameter
space are empirically identified. We find that, all the torus-unstable cases
(decay index ), have a large rotation angles ranging from . The possible mechanisms leading to the rotation and failed eruption
are discussed. These results imply that, besides the torus instability, the
rotation motion during the eruption may also play a significant role in solar
eruptions
Plastic dilation rate characteristic of concrete confined with steel tube
The use of external confining devices to confine concrete has become widely used. One of the purposes is to gain additional concrete strength and ductility. Although there are many types of external confining devices, in this paper, the attention is limited to the use ofthe steel tube as anexternal confining device. One of the main objectives ofthis research is to study the plastic dilation rate behavior of concrete-filled-steel-tube (CFST) columns. The experimental data for the plastic dilation rate is extracted, and compared with the authors concrete plasticity model. In the authors’ previous research, the calibration of the plastic dilation rate model was based on confined concrete tested under both active and passive confinement using FRP wraps. Since the behavior of the steel tube and the FRP materials are different, the author’s plastic dilation rate model needs to be re-evaluated for CFST columns. Comparisons of the extracted experimental plastic dilation rates with the model prediction for CFST specimens with normal strength concrete show good agreement and requires no adjustment in the formulation. However, for a specimen with 80 MPa concrete, the proposed formulation showsslightly lowerplastic dilation rates.More experimental data for CFST using high strength concretes is required for further investigation. For the sake of completeness, the overall response of two CFST specimensisalso evaluated using anin-house three-dimensional non-linear finite element analysis (3D-NLFEA) using the author’s proposed plasticity formulation for confined concrete
Cross-Platform Presentation of Interactive Volumetric Imagery
Volume data is useful across many disciplines, not just medicine.
Thus, it is very important that researchers have a simple and
lightweight method of sharing and reproducing such volumetric
data. In this paper, we explore some of the challenges associated
with volume rendering, both from a classical sense and from the
context of Web3D technologies. We describe and evaluate the pro-
posed X3D Volume Rendering Component and its associated styles
for their suitability in the visualization of several types of image
data. Additionally, we examine the ability for a minimal X3D node
set to capture provenance and semantic information from outside
ontologies in metadata and integrate it with the scene graph
Dust and gas emission from cometary nuclei: the case of comet 67P/Churyumov-Gerasimenko
Comets display with decreasing solar distance an increased emission of gas
and dust particles, leading to the formation of the coma and tail. Spacecraft
missions provide insight in the temporal and spatial variations of the dust and
gas sources located on the cometary nucleus. For the case of comet
67P/Churyumov-Gerasimenko (67P/C-G), the long-term observations from the
Rosetta mission point to a homogeneous dust emission across the entire
illuminated surface. Despite the homogeneous initial distribution, a
collimation in jet-like structures becomes visible. We propose that this
observation is linked directly to the complex shape of the nucleus and projects
concave topographical features into the dust coma. To test this hypothesis, we
put forward a gas-dust description of 67P/C-G, where gravitational and gas
forces are accurately determined from the surface mesh and the rotation of the
nucleus is fully incorporated. The emerging jet-like structures persist for a
wide range of gas-dust interactions and show a dust velocity dependent bending.Comment: 17 pages, with 7 figures. To appear in Advances in Physics X (2018
The SSDC contribution to the improvement of knowledge by means of 3D data projections of minor bodies
The latest developments of planetary exploration missions devoted to minor
bodies required new solutions to correctly visualize and analyse data acquired
over irregularly shaped bodies. ASI Space Science Data Center (SSDC-ASI,
formerly ASDC-ASI Science Data Center) worked on this task since early 2013,
when started developing the web tool MATISSE (Multi-purpose Advanced Tool for
the Instruments of the Solar System Exploration) mainly focused on the
Rosetta/ESA space mission data. In order to visualize very high-resolution
shape models, MATISSE uses a Python module (vtpMaker), which can also be
launched as a stand-alone command-line software. MATISSE and vtpMaker are part
of the SSDC contribution to the new challenges imposed by the "orbital
exploration" of minor bodies: 1) MATISSE allows to search for specific
observations inside datasets and then analyse them in parallel, providing
high-level outputs; 2) the 3D capabilities of both tools are critical in
inferring information otherwise difficult to retrieve for non-spherical targets
and, as in the case for the GIADA instrument onboard Rosetta, to visualize data
related to the coma. New tasks and features adding valuable capabilities to the
minor bodies SSDC tools are planned for the near future thanks to new
collaborations
Analyzing and Visualizing Cosmological Simulations with ParaView
The advent of large cosmological sky surveys - ushering in the era of
precision cosmology - has been accompanied by ever larger cosmological
simulations. The analysis of these simulations, which currently encompass tens
of billions of particles and up to trillion particles in the near future, is
often as daunting as carrying out the simulations in the first place.
Therefore, the development of very efficient analysis tools combining
qualitative and quantitative capabilities is a matter of some urgency. In this
paper we introduce new analysis features implemented within ParaView, a
parallel, open-source visualization toolkit, to analyze large N-body
simulations. The new features include particle readers and a very efficient
halo finder which identifies friends-of-friends halos and determines common
halo properties. In combination with many other functionalities already
existing within ParaView, such as histogram routines or interfaces to Python,
this enhanced version enables fast, interactive, and convenient analyses of
large cosmological simulations. In addition, development paths are available
for future extensions.Comment: 9 pages, 8 figure
- …