100 research outputs found
On dynamical tunneling and classical resonances
This work establishes a firm relationship between classical nonlinear
resonances and the phenomenon of dynamical tunneling. It is shown that the
classical phase space with its hierarchy of resonance islands completely
characterizes dynamical tunneling and explicit forms of the dynamical barriers
can be obtained only by identifying the key resonances. Relationship between
the phase space viewpoint and the quantum mechanical superexchange approach is
discussed in near-integrable and mixed regular-chaotic situations. For
near-integrable systems with sufficient anharmonicity the effect of multiple
resonances {\it i.e.,} resonance-assisted tunneling can be incorporated
approximately. It is also argued that the, presumed, relation of avoided
crossings to nonlinear resonances does not have to be invoked in order to
understand dynamical tunneling. For molecules with low density of states the
resonance-assisted mechanism is expected to be dominant.Comment: Completely rewritten and expanded version of a previous submission
physics/0410033. 14 pages and 10 figure
Bio-signals compression using auto-encoder
Latest developments in wearable devices permits un-damageable and cheapest way for gathering of medical data such as bio-signals like ECG, Respiration, Blood pressure etc. Gathering and analysis of various biomarkers are considered to provide anticipatory healthcare through customized applications for medical purpose. Wearable devices will rely on size, resources and battery capacity; we need a novel algorithm to robustly control memory and the energy of the device. The rapid growth of the technology has led to numerous auto encoders that guarantee the results by extracting feature selection from time and frequency domain in an efficient way. The main aim is to train the hidden layer to reconstruct the data similar to that of input. In the previous works, to accomplish the compression all features were needed but in our proposed framework bio-signals compression using auto-encoder (BCAE) will perform task by taking only important features and compress it. By doing this it can reduce power consumption at the source end and hence increases battery life. The performance of the result comparison is done for the 3 parameters compression ratio, reconstruction error and power consumption. Our proposed work outperforms with respect to the SURF method
Silver lead borate glasses doped with europium ions for phosphors applications
Europium (Eu3+) doped silver lead borate glasses with the composition of xEu2O3�(1 � x)Ag2 O�29PbO�70B2O3 (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5 mol) have been successfully prepared by conventional melt quenching method. Thermal, structural and luminescence properties have been studied using thermograms, transmittance, excitation and emission spectra. From the differential scanning calorimetry studies, the glass transition temperatures (Tg) have been investigated and their values are ranging from 449 to 458�C. The investigation of Fourier transformer infrared spectra shows the presence of boron atoms in both BO3 and BO4 units in the glass network. In addition, it was found that new structural groups were present, such as boroxyl rings, pyro and dipenta-borate. Photoluminescence spectroscopy was used to examine down conversion emission under 394 nm excitation, which exhibits five emission bands centred at 577, 590, 612, 650 and 697 nm corresponding to 5D0�7F0, 5D0�7F1, 5D0�7F2, 5D0�7F3 and 5D0�7F4 transitions of Eu3+ ions, respectively. The Commission International de I�Eclairage France 1931 chromaticity coordinates estimated from the emission spectra; it was shown that a 0.5 mol Eu2O3 doped glass is quite suitable for efficient red phosphors application. © Indian Academy of Sciences
Europium-doped boro-bismuth-tellurite glasses for multicolor phosphor applications
The glass system (50–x)B2O3–30Bi2O3–20TeO2–xEu2O3 (x = 0, 0.1, 0.5, 1.0, 1.5, and 2.0 mol%) having been prepared using the conventional melt quenching method, is investigated in terms of physical, optical, and luminescence properties. The density of these glasses is measured and the corresponding molar volume is also calculated. The (αhν)1/n versus hν graph was plotted and it is well fitted to both direct (n = 1/2) and indirect (n = 2) band gaps. The direct and indirect band gap values range from 2.57 to 2.94 eV and 1.74 to 2.58 eV, respectively. The Urbach energy of the glass system was calculated to have values ranging from 0.29 to 0.62 eV. Yellow, orange, and red emissions have been observed through photoluminescence (PL) spectroscopy excited at 464 nm and the obtained multicolor emissions have been demonstrated according to the Commission International de l’Eclairage de France 1931 standards. The results of PL studies indicated the possibility towards the development of multicolor phosphor applications
Influence of europium (Eu3+) ions on the optical properties of silver lead borate glasses
The influence of europium (Eu3+) ions on the optical properties of silver lead borate glasses of the xEu2O3–(1 – x)Ag2O–29PbO–70B2O3 (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5 mol%) glass system prepared by theconventional melt quenching technique and their physical and optical properties were investigated. The UV absorption spectra were recorded at room temperature in the wavelength range of 200–600 nm. From the absorption edge data, it is found that both the direct and indirect transitions and their values are ranging from 3.19 to 3.54 and 2.50 to 3.07 eV, respectively. The Urbach energy values for these glasses were found to be in the range of 0.39–0.52 eV. The refractive indices have also been evaluated with respect to different molar concentrations of Eu2O3 and their calculated values are ranging from 1.598 to 1.654
Understanding highly excited states via parametric variations
Highly excited vibrational states of an isolated molecule encode the
vibrational energy flow pathways in the molecule. Recent studies have had
spectacular success in understanding the nature of the excited states mainly
due to the extensive studies of the classical phase space structures and their
bifurcations. Such detailed classical-quantum correspondence studies are
presently limited to two or quasi two dimensional systems. One of the main
reasons for such a constraint has to do with the problem of visualization of
relevant objects like surface of sections and Wigner or Husimi distributions
associated with an eigenstate. This neccesiates various alternative techniques
which are more algebraic than geometric in nature. In this work we introduce
one such method based on parametric variation of the eigenvalues of a
Hamiltonian. It is shown that the level velocities are correlated with the
phase space nature of the corresponding eigenstates. A semiclassical expression
for the level velocities of a single resonance Hamiltonian is derived which
provides theoretical support for the correlation. We use the level velocities
to dynamically assign the highly excited states of a model spectroscopic
Hamiltonian in the mixed phase space regime. The effect of bifurcations on the
level velocities is briefly discussed using a recently proposed spectroscopic
Hamiltonian for the HCP molecule.Comment: 12 pages, 9 figures, submitted to J. Chem. Phy
An Investigation on the Influence of Modeling Approach and Load Pattern on Seismic Performance of RC Structures
Non-linear Static Analysis serves as a suitable measure to evaluate the performance of a structural system. The careful selection of modelling approach and the load pattern is critical to arrive at an adequate performance evaluation. The present study seeks to evaluate and compare the response of an existing eight story reinforced concrete structure, through the application of different modeling approaches and load patterns prescribed by FEMA 356. The results indicates that, with extreme clarity, that in all cases, the shape of the lateral load distribution is what the response of the buildings is finely accustomed to. This is especially true when different patterns of load are considered. It can also be observed that there is a very small difference between various load patterns
Analyzing intramolecular vibrational energy redistribution via the overlap intensity-level velocity correlator
Numerous experimental and theoretical studies have established that
intramolecular vibrational energy redistribution (IVR) in isolated molecules
has a heirarchical tier structure. The tier structure implies strong
correlations between the energy level motions of a quantum system and its
intensity-weighted spectrum. A measure, which explicitly accounts for this
correaltion, was first introduced by one of us as a sensitive probe of phase
space localization. It correlates eigenlevel velocities with the overlap
intensities between the eigenstates and some localized state of interest. A
semiclassical theory for the correlation is developed for systems that are
classically integrable and complements earlier work focusing exclusively on the
chaotic case. Application to a model two dimensional effective spectroscopic
Hamiltonian shows that the correlation measure can provide information about
the terms in the molecular Hamiltonian which play an important role in an
energy range of interest and the character of the dynamics. Moreover, the
correlation function is capable of highlighting relevant phase space structures
including the local resonance features associated with a specific bright state.
In addition to being ideally suited for multidimensional systems with a large
density of states, the measure can also be used to gain insights into the phase
space transport and localization. It is argued that the overlap intensity-level
velocity correlation function provides a novel way of studying vibrational
energy redistribution in isolated molecules. The correlation function is
ideally suited to analyzing the parametric spectra of molecules in external
fields.Comment: 16 pages, 13 figures (low resolution
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