1,772 research outputs found
Noise and diffusion of a vibrated self-propelled granular particle
Granular materials are an important physical realization of active matter. In
vibration-fluidized granular matter, both diffusion and self-propulsion derive
from the same collisional forcing, unlike many other active systems where there
is a clean separation between the origin of single-particle mobility and the
coupling to noise. Here we present experimental studies of single-particle
motion in a vibrated granular monolayer, along with theoretical analysis that
compares grain motion at short and long time scales to the assumptions and
predictions, respectively, of the active Brownian particle (ABP) model. The
results demonstrate that despite the unique relation between noise and
propulsion, granular media do show the generic features predicted by the ABP
model and indicate that this is a valid framework to predict collective
phenomena. Additionally, our scheme of analysis for validating the inputs and
outputs of the model can be applied to other granular and non-granular systems.Comment: 5 pages, 4 figures; plus supplementar
Generalized Ideals and Co-Granular Rough Sets
Lattice-theoretic ideals have been used to define and generate non granular
rough approximations over general approximation spaces over the last few years
by few authors. The goal of these studies, in relation based rough sets, have
been to obtain nice properties comparable to those of classical rough
approximations. In this research paper, these ideas are generalized in a severe
way by the present author and associated semantic features are investigated by
her. Granules are used in the construction of approximations in implicit ways
and so a concept of co-granularity is introduced. Knowledge interpretation
associable with the approaches is also investigated. This research will be of
relevance for a number of logico-algebraic approaches to rough sets that
proceed from point-wise definitions of approximations and also for using
alternative approximations in spatial mereological contexts involving actual
contact relations. The antichain based semantics invented in earlier papers by
the present author also applies to the contexts considered.Comment: 20pages. Scheduled to appear in IJCRS'2017 Proceedings, LNCS,
Springe
Automatic Method for Identifying Photospheric Bright Points and Granules Observed by Sunrise
In this study, we propose methods for the automatic detection of photospheric
features (bright points and granules) from ultra-violet (UV) radiation, using a
feature-based classifier. The methods use quiet-Sun observations at 214 nm and
525 nm images taken by Sunrise on 9 June 2009. The function of region growing
and mean shift procedure are applied to segment the bright points (BPs) and
granules, respectively. Zernike moments of each region are computed. The
Zernike moments of BPs, granules, and other features are distinctive enough to
be separated using a support vector machine (SVM) classifier. The size
distribution of BPs can be fitted with a power-law slope -1.5. The peak value
of granule sizes is found to be about 0.5 arcsec^2. The mean value of the
filling factor of BPs is 0.01, and for granules it is 0.51. There is a critical
scale for granules so that small granules with sizes smaller than 2.5 arcsec^2
cover a wide range of brightness, while the brightness of large granules
approaches unity. The mean value of BP brightness fluctuations is estimated to
be 1.2, while for granules it is 0.22. Mean values of the horizontal velocities
of an individual BP and an individual BP within the network were found to be
1.6 km/s and 0.9 km/s, respectively. We conclude that the effect of individual
BPs in releasing energy to the photosphere and maybe the upper layers is
stronger than what the individual BPs release into the network
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Safety and efficacy of endoscopic submucosal dissection for rectal neoplasia: a multicenter North American experience.
Background and aims Rectal lesions traditionally represent the first lesions approached during endoscopic submucosal dissection (ESD) training in the West. We evaluated the safety and efficacy of rectal ESD in North America. Methods This is a multicenter retrospective analysis of rectal ESD between January 2010 and September 2018 in 15 centers. End points included: rates of en bloc resection, R0 resection, adverse events, comparison of pre- and post-ESD histology, and factors associated with failed resection. Results In total, 171 patients (median age 63 years; 56 % men) underwent rectal ESD (median size 43 mm). En bloc resection was achieved in 141 cases (82.5 %; 95 %CI 76.8-88.2), including 24 of 27 (88.9 %) with prior failed endoscopic mucosal resection (EMR). R0 resection rate was 74.9 % (95 %CI 68.4-81.4). Post-ESD bleeding and perforation occurred in 4 (2.3 %) and 7 (4.1 %), respectively. Covert submucosal invasive cancer (SMIC) was identified in 8.6 % of post-ESD specimens. There was one case (1/120; 0.8 %) of recurrence at a median follow-up of 31 weeks; IQR: 19-76 weeks). Older age and higher body mass index (BMI) were predictors of failed R0 resection, whereas submucosal fibrosis was associated with a higher likelihood of both failed en bloc and R0 resection. Conclusion Rectal ESD in North America is safe and is associated with high en bloc and R0 resection rates. The presence of submucosal fibrosis was the main predictor of failed en bloc and R0 resection. ESD can be considered for select rectal lesions, and serves not only to establish a definitive tissue diagnosis but also to provide curative resection for lesions with covert advanced disease
Municipal wastewater treatment and associated bioenergy generation using anaerobic granular bed baffled reactor
This study assesses a modified anaerobic granular bed baffled reactor (GRABBR) which was assessed for municipal wastewater treatment at high organic loading rates (chemical oxygen demand ≥ 1,100 mg/l) under varying temperatures. For the two mesophilic temperatures tested (37⁰C and 25⁰C) under steady state conditions, the removal of Chemical OxygenDemand (COD) and Biochemical Oxygen Demand (BOD) was 80 to 90 %. At lower organic loadings, the reactor operated as a completely mixed system with most of the treatment occurring in the first two compartments. The GRABBR also showed very high solids retention with low effluent suspended solids concentration for all organic and hydraulic conditions. Applications ofGRABBR as a single unit, two-phase treatment system could be an economical option reducing the cost to achieve similar treatment goals for high strength wastewaters. The findings of this research suggest that the application of GRABBR is suitable for the treatment of multiple pollutants present in wastewater where each compartment acts as a specialised treatment stagewith biogas production
Tenfold Magnetoconductance in a Non-Magnetic Metal Film
We present magnetoconductance (MC) measurements of homogeneously disordered
Be films whose zero field sheet conductance (G) is described by the
Efros-Shklovskii hopping law . The low field
MC of the films is negative with G decreasing 200% below 1 T. In contrast the
MC above 1 T is strongly positive. At 8 T, G increases 1000% in perpendicular
field and 500% in parallel field. In the simpler parallel case, we observe {\em
field enhanced} variable range hopping characterized by an attenuation of
via the Zeeman interaction.Comment: 9 pages including 5 figure
A comparative study of angle dependent magnetoresistance in [001] and [110]
The angle dependent magnetoresistance study on [001] and [110] LaSrMnO thin films show that the anisotropy energy of [110]
films is higher when compared with a [001] oriented LaSrMnO film of similar thickness. The data has been analyzed in the light
of multidomain model and it is seen that this model correctly explains the
observed behavior.Comment: 8pages, 2 figure
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