358 research outputs found
Inflationary Predictions and Moduli Masses
A generic feature of inflationary models in supergravity/string constructions
is vacuum misalignment for the moduli fields. The associated production of
moduli particles leads to an epoch in the post-inflationary history in which
the energy density is dominated by cold moduli particles. This modification of
the post-inflationary history implies that the preferred range for the number
of e-foldings between horizon exit of the modes relevant for CMB observations
and the end of inflation depends on moduli masses. This in turn implies
that the precision CMB observables and are sensitive to moduli
masses. We analyse this sensitivity for some representative models of inflation
and find the effect to be highly relevant for confronting inflationary models
with observations.Comment: 17 pages, 3 figures; v2 minor additions in tex
Investigations on Machining Aspects of Inconel 718 During Wire Electro-Discharge Machining (WEDM): Experimental and Numerical Analysis
Wire electro- discharge machining (WEDM) is known as unique cutting in manufacturing industries, especially in the good tolerance with intricate shape geometry in die industry. In this study the workpiece has been chosen as Inconel 718. Inconel 718 super alloy is widely used in aerospace industries. This nickel based super alloy has excellent resistance to high temperature, mechanical and chemical degradations with toughness and work hardening characteristics materials. Due to these properties, the machinability studies of this material have been carried-out in this study. The machining of Inconel 718 using variation of wire electrode material (brass wire electrode and zinc coated brass wire) with diameter equal to 0.20mm has been carried out. The objective of this study is mainly to investigate the various WEDM process parameters and performance of wire electrodes materials on Inconel 718 with various types of cutting. The optimal process parameter setting for each of wire electrode material has been obtained for multi-objective response. The kerf width, Material Removal Rate (MRR) and surface finish, corner error, corner deviation and angular error are the responses which are function of process variables viz. pulse-on time, discharge current, wire speed, flushing pressure and taper angle. The non-linear regression analysis has been developed for relationship between the process parameter and process characteristics. The optimal parameters setting have been carried out using multi-objective nature-inspired meta-heuristic optimization algorithm such as Whale Optimization Algorithm (WOA) and Gray Wolf Optimizer (GWO). Lastly numerical model analysis has been carried out to determine MRR and residual stress using ANSYS software and MRR model validated with the experimental results. The overlapping approach has been adopted for solving the multi-spark problem and validate with the experimental results
Nonlocal description of sound propagation through an array of Helmholtz resonators
A generalized macroscopic nonlocal theory of sound propagation in
rigid-framed porous media saturated with a viscothermal fluid has been recently
proposed, which takes into account both temporal and spatial dispersion. Here,
we consider applying this theory capable to describe resonance effects, to the
case of sound propagation through an array of Helmholtz resonators whose
unusual metamaterial properties such as negative bulk moduli, have been
experimentally demonstrated. Three different calculations are performed,
validating the results of the nonlocal theory, relating to the
frequency-dependent Bloch wavenumber and bulk modulus of the first normal mode,
for 1D propagation in 2D or 3D periodic structures.Comment: 19 page
GENERATING DYNAMIC EMOTIVE ANIMATIONS FOR AUGMENTED REALITY
The method may include receiving, at a user interface generated for the electronic device, an indication to access an augmented reality fitting environment associated with at least one shopping item; receiving a selected image of a location in which to display the augmented reality fitting environment; obtaining user measurement data, shopping item data, and emotions analytics data associated with the augmented reality fitting environment; and generating, based on the obtained user measurement data, a plurality of three-dimensional avatars representing a user accessing the augmented reality fitting environment on the electronic device. For each avatar, the method may include generating, using the shopping item data and the user measurement data, a unique three-dimensional representation of the at least one shopping item, generating emotive content based at least in part on the emotions analytics data and on the respective generated representation of the at least one shopping item, and triggering, in the user interface, display of the plurality of three-dimensional avatars in the augmented reality fitting environment and within the selected image of the location, each avatar being depicted with the respective generated emotive content and wearing the respective generated representation of the at least one shopping item
Transformation Optics scheme for two-dimensional materials
Two dimensional optical materials, such as graphene can be characterized by a
surface conductivity. So far, the transformation optics schemes have focused on
three dimensional properties such as permittivity and permeability
. In this paper, we use a scheme for transforming surface currents to
highlight that the surface conductivity transforms in a way different from
and . We use this surface conductivity transformation to
demonstrate an example problem of reducing scattering of plasmon mode from
sharp protrusions in graphene
Enhanced Security Framework to Develop Secure Data Warehouse
Data Warehouse contains crucial information about organization. This information is utilized by decision maker to analyze the current status and planning the development of the organization. The data warehouse can be easily accessed by an authorized user or by an unauthorized user through unfair means. To preclude this data from unauthorized access, several measures have been taken and a lot of research is going on. In this paper, a framework is proposed to prevent the data from unauthorized access and thereby increases the security of data warehouse
Tunable light-matter interaction and the role of hyperbolicity in graphene-hBN system
Hexagonal boron nitride (hBN) is a natural hyperbolic material which can also
accommodate highly dispersive surface phonon-polariton modes. In this paper, we
examine theoretically the mid-infrared optical properties of graphene-hBN
heterostructures derived from their coupled plasmon-phonon modes. We found that
the graphene plasmon couples differently with the phonons of the two
Reststrahlen bands, owing to their different hyperbolicity. This also leads to
distinctively different interaction between an external quantum emitter and the
plasmon-phonon modes in the two bands, leading to substantial modification of
its spectrum. The coupling to graphene plasmons allows for additional gate
tunability in the Purcell factor, and narrow dips in its emission spectra
Photon Emission Rate Engineering using Graphene Nanodisc Cavities
In this work, we present a systematic study of the plasmon modes in a system
of vertically stacked pair of graphene discs. Quasistatic approximation is used
to model the eigenmodes of the system. Eigen-response theory is employed to
explain the spatial dependence of the coupling between the plasmon modes and a
quantum emitter. These results show a good match between the semi-analytical
calculation and full-wave simulations. Secondly, we have shown that it is
possible to engineer the decay rates of a quantum emitter placed inside and
near this cavity, using Fermi level tuning, via gate voltages and variation of
emitter location and polarization. We highlighted that by coupling to the
bright plasmon mode, the radiative efficiency of the emitter can be enhanced
compared to the single graphene disc case, whereas the dark plasmon mode
suppresses the radiative efficiency
Adjusting the rotation speed of a 3D object according to zoom level
When a user attempts to rotate a 3D object in a 3D viewer while the object is scaled up at a high level of zoom, the speed of rotation can be too fast to allow the user to discern and focus on specific parts of the object at that size. This disclosure describes techniques to adjust the speed of rotation of an interactive 3D object depending on the scale at which the user is viewing the object. The dynamic adjustment of the speed of rotation make it possible for users to look at the details of the object at various scales while maintaining a smooth user experience (UX) for interacting with the object by scaling and rotating
- …