4,191 research outputs found
Adversarially Tuned Scene Generation
Generalization performance of trained computer vision systems that use
computer graphics (CG) generated data is not yet effective due to the concept
of 'domain-shift' between virtual and real data. Although simulated data
augmented with a few real world samples has been shown to mitigate domain shift
and improve transferability of trained models, guiding or bootstrapping the
virtual data generation with the distributions learnt from target real world
domain is desired, especially in the fields where annotating even few real
images is laborious (such as semantic labeling, and intrinsic images etc.). In
order to address this problem in an unsupervised manner, our work combines
recent advances in CG (which aims to generate stochastic scene layouts coupled
with large collections of 3D object models) and generative adversarial training
(which aims train generative models by measuring discrepancy between generated
and real data in terms of their separability in the space of a deep
discriminatively-trained classifier). Our method uses iterative estimation of
the posterior density of prior distributions for a generative graphical model.
This is done within a rejection sampling framework. Initially, we assume
uniform distributions as priors on the parameters of a scene described by a
generative graphical model. As iterations proceed the prior distributions get
updated to distributions that are closer to the (unknown) distributions of
target data. We demonstrate the utility of adversarially tuned scene generation
on two real-world benchmark datasets (CityScapes and CamVid) for traffic scene
semantic labeling with a deep convolutional net (DeepLab). We realized
performance improvements by 2.28 and 3.14 points (using the IoU metric) between
the DeepLab models trained on simulated sets prepared from the scene generation
models before and after tuning to CityScapes and CamVid respectively.Comment: 9 pages, accepted at CVPR 201
Self-Similar Accretion Flows with Convection
We consider height-integrated equations of an advection-dominated accretion
flow (ADAF), assuming that there is no mass outflow. We include convection
through a mixing length formalism. We seek self-similar solutions in which the
rotational velocity and sound speed scale as R^{-1/2}, where R is the radius,
and consider two limiting prescriptions for the transport of angular momentum
by convection. In one limit, the transport occurs down the angular velocity
gradient, so convection moves angular momentum outward. In the other, the
transport is down the specific angular momentum gradient, so convection moves
angular momentum inward. We also consider general prescriptions which lie in
between the two limits.
When convection moves angular momentum outward, we recover the usual
self-similar solution for ADAFs in which the mass density scales as rho ~
R^{-3/2}. When convection moves angular momentum inward, the result depends on
the viscosity coefficient alpha. If alpha>alpha_{crit1} ~ 0.05, we once again
find the standard ADAF solution. For alpha<alpha_{crit}, however, we find a
non-accreting solution in which rho ~ R^{-1/2}. We refer to this as a
"convective envelope" solution or a "convection-dominated accretion flow".
Two-dimensional numerical simulations of ADAFs with values of alpha<0.03 have
been reported by several authors. The simulated ADAFs exhibit convection. By
virtue of their axisymmetry, convection in these simulations moves angular
momentum inward, as we confirm by computing the Reynolds stress. The
simulations give rho ~ R^{-1/2}, in good agreement with the convective envelope
solution. The R^{-1/2} density profile is not a consequence of mass outflow.Comment: 22 pages, 4 figures, final version accepted for publication in ApJ, a
new appendix was added and 3 figs were modifie
Structural, Magnetic and Magneto-caloric studies of Ni50Mn30Sn20Shape Memory Alloy
We have synthesized a nominal composition of Ni50Mn30Sn20 alloy using arc
melting technique. Rietveld refinement confirms the austenite L21 structure in
Fm-3m space group. Electrical resistivity has been found to clearly exhibiting
two different phenomena viz. a magnetic transition from paramagnetic to
ferromagnetic and a structural transition from austenite to martensitic phase.
Thermo-magnetization measurements M(T) confirms ferromagnetic transition
temperature TC at 222 K and martensitic transition starting at 127 K(MS).
Magnetization measurement M(H) at 10 K confirms the ferromagnetic state.
Frequency dependence of ac susceptibility \c{hi}' at low temperature suggests
spin glass behavior in the system. The isothermal magnetic entropy change
values have been found to be 1.14 J/Kg.K, 2.69 J/Kg.K and 3.9 J/Kg.K, with
refrigeration capacities of 19.6 J/kg, 37.8 J/kg and 54.6 J/kg for the field
change of 1, 2 and 3 Tesla respectively at 227 K.Comment: 16 pages text + Figs. Ni50Mn30Sn20 alloy: reasonable refrigeration
capacity tunable to Room
Non-Destructive Evaluation—A Pivotal Technology for Qualification of Composite Aircraft Structures
Tremendous advances in composite materials and a deeper understanding of their behavior have been responsible for the increased use of composites in the development of advanced, new generation civil and military aircraft. Composites play an important role in any aircraft development programme and are strong contenders to their metal counterparts due to their significant contributions towards improving strength, stiffness, fatigue properties & weight reduction. As materials, structural design &
processing have evolved, strong emphasis is placed on effective & reliable damage detection, durability
and damage tolerance. As a consequence, Non-destructive Evaluation (NDE) has also undergone significant advances towards meeting the growing demands of quality assurance. Advanced Composites Division (ACD) of National Aerospace Laboratories (NAL), has been involved in the development of
composite structures for both civil and military aircraft for over a decade and a half. Innovative composite processing methods like co-curing/co-bonding have been successfully employed to realize airworthy structures. The role of NDE in the development of these structures has been critical and not limited to damage detection alone. On several occasions, NDE has provided valuable inputs towards
improving design and process parameters. In-spite of the complexity of the structures, stringent quality requirements and tight delivery schedules, NDE has been successful in certifying these composite structures for airworthiness. This paper discusses the implementation of key NDE techniques like ultrasonics, radiography, acoustic emission and thermography for reliable flaw detection, characterization and quality assurance of composite aircraft structures
Effects of cement dust deposition on water, soil and green plants in Ariyalur district
The pollutant particles can have as consequence the reduction of biodiversity and the quality of water, soil and whole ecosystems. Especially, the cement dust can be emitted at every stage of cement production caused photosynthetic process, leaf stomata, discoloration, enzymatic malfunction, growth reduction and productivity of plants. In this study, the water, surface soil, bottom soil and two plant ( Croton bonplandianum and Cassiaauriculata) samples were collected from three different (cement dust exposed) sites of Ariyalur district during summer 2014 for physiochemical, heavy metal and biochemical constituents analysis. The sampling sites of S1, S2 and S3 were 0-500 m, 500-1000 m and 1000-1500 m away from the cement industry of Ariyalur industrial zone, respectively. The results from those sites were compared with control site (C1) (Jamal Mohammed College, Tiruchirappalli, Tamil Nadu - non-industrial area) results. The higher concentrations of physiochemical and heavy metal parameters were observed from the study areas than the control sites which indicated that those sites drained large amount of cement dust particles from cement industries. The surface soil got higher concentration of all parameters followed by bottom soil and ground water. The phytochemical concentration was also reduced in study area plants than control site plants. Hence, the Ariyalur district needed throughout impoundment
Least squares kinetic upwind method on moving grids for unsteady Euler computations
The present paper describes the extension of least squares kinetic upwind method for moving grids (LSKUM-MG). LSKUM is a kinetic theory based upwind Euler solver. LSKUM is a node based solver and can operate on any type of mesh or even on an arbitrary distribution of points. LSKUM-MG also has the capability to work on arbitrary meshes with arbitrary grid velocities. Results are presented for a moving piston problem and flow past an airfoil oscillating in pitch
Supersolid and solitonic phases in one-dimensional Extended Bose-Hubbard model
We report our findings on quantum phase transitions in cold bosonic atoms in
a one dimensional optical lattice using the finite size density matrix
renormalization group method in the framework of the extended Bose-Hubbard
model. We consider wide ranges of values for the filling factors and the
nearest neighbor interactions. At commensurate fillings, we obtain two
different types of charge density wave phases and a Mott insulator phase.
However, departure from commensurate fillings yield the exotic supersolid phase
where both the crystalline and the superfluid orders coexist. In addition, we
obtain signatures for solitary waves and also superfluidity.Comment: 7 pages, 11 figure
Characterization of Intermetallic Precipitates in Ni-Base Alloys by Non-destructive Techniques
The present industrial scenario requires all engineering structure to be designed considering stability of several parameters at the operating conditions (e.g. Temperature, pressure, resistance to mechanical and surface degradation). Choice of materials for any engineering component should be such that it operates safely for reliable function, without failure during in-service, giving optimum component life. Due to scarcity of various resources and cost of manufacturing, regular maintenance and evaluation of structural integrity at every stage of production is necessary. Non-destructive techniques (NDT), along with modern computational facility help in non-intrusive investigation of the component at regular intervals of the operating stages for many critical applications. This will result in increment of designed component life and also help in maximizing utilization of natural resources
- …