1,848 research outputs found
A Study on Principal Component Analysis over Wireless Channel
Applications in many fields such as the internet of things (IoT), stock market, image compression, food adulteration, wireless physical layer key generation, etc. are becoming progressively complex due to a large number of users and increment in their usage. Data obtained by these applications are in huge amount creating a high computational cost. Further, it is difficult to handle and analyze it. To deal with such problems, dimensionality reduction techniques are used and one of the dimensionality reduction techniques is the Principal Component Analysis (PCA). In this paper, PCA is applied over a wireless Rician channel with AWGN at different SNR. It is concluded that the information content is more in less number of principal components with samples at higher SNR. It is also observed that the different combinations of several groups and elements in the sample space provide a different cumulative percentage of information
Effects of dissipation on disordered quantum spin models
We study the effects of the coupling to an Ohmic quantum reservoir on the
static and dynamical properties of a family of disordered SU(2) spin models in
a transverse magnetic field using a method of direct spin summation. The
tendency to form a glassy phase increases with the strength of the coupling of
the system to the environment. We study the influence of the environment on the
features of the phase diagram of the various models as well as the stability of
the possible phases.Comment: 24 pages, 8 fig
Exchange Monte Carlo Method and Application to Spin Glass Simulations
We propose an efficient Monte Carlo algorithm for simulating a
``hardly-relaxing" system, in which many replicas with different temperatures
are simultaneously simulated and a virtual process exchanging configurations of
these replica is introduced. This exchange process is expected to let the
system at low temperatures escape from a local minimum. By using this algorithm
the three-dimensional Ising spin glass model is studied. The ergodicity
time in this method is found much smaller than that of the multi-canonical
method. In particular the time correlation function almost follows an
exponential decay whose relaxation time is comparable to the ergodicity time at
low temperatures. It suggests that the system relaxes very rapidly through the
exchange process even in the low temperature phase.Comment: 10 pages + uuencoded 5 Postscript figures, REVTe
Increasing of entanglement entropy from pure to random quantum critical chains
It is known that the entropy of a block of spins of size embedded in an
infinite pure critical spin chain diverges as the logarithm of with a
prefactor fixed by the central charge of the corresponding conformal field
theory. For a class of strongly random spin chains, it has been shown that the
correspondent block entropy still remains universal and diverges
logarithmically with an "effective" central charge. By computing the
entanglement entropy for a family of models which includes the -states
random Potts chain and the clock model, we give some definitive answer to
some recent conjectures about the behaviour of the effective central charge. In
particular, we show that the ratio between the entanglement entropy in the pure
and in the disordered system is model dependent and we provide a series of
critical models where the entanglement entropy grows from the pure to the
random case.Comment: 4 pages, 2 eps figures, added reference
Probable binary open star clusters in the galaxy
The existence of double/binary clusters in the Magellanic Clouds is fairly well established, whereas only one such pair, h + Ï Persei, is known in the Galaxy. From the catalogues of open clusters of the Galaxy, we have identified 18 probable pairs of clusters (with known distances), with spatial separations less than 20pc. The tidal disruption timescales for these pairs, due to Galactic differential rotation are calculated, using cluster data where available or by assuming typical values. In some cases, these timescales are larger than the average open cluster lifetime, â108yr. About 8% of open clusters appear to be members of binary systems, and hence binary cluster systems may not be very uncommon in the Galaxy
Low Complexity Security Algorithm for CPS / IoT Networks
Due to its noisy nature, wireless channel plays a dominant role in deciding the performance of data communication between the smart objects in the cyberphysical systems (CPS) or the internet of things (IoT). Open and heterogeneous nature of these networks makes them susceptible to vulnerable attacks. So, to keep up the confidentiality and integrity of the transmitted data against the adversaries, it should be secured before transmission. However, issues such as power efficiency, low computational complexity need to be considered when designing security algorithms for CPS/IoT networks. Traditional encryption algorithms, such as Advanced Encryption Standard (AES), International Data Encryption Algorithm (IDEA) can be used for security purpose, but they do not satisfy power and complexity criteria as per CPS/IOT networks requirements. Moreover, they exhibit poor bit error ratio (BER) performance in a noisy wireless channel. This paper presents a modified security algorithm, AES-P, with X-OR mapping on AES to make them suitable for CPS/IoT applications. Simulation and analysis of the proposed algorithm showed that its power consumption and complexity are reduced as compared to traditional AES. It also performed better in the wireless channel, while maintaining the required security level satisfied by Avalanche effect
Cadmium induced oxidative stress-mediated pathophysiological alterations in chickens and their amelioration by polyherbal mixture enriched feed
41-53The study was conducted to evaluate sub-acute toxicity of cadmium (Cd) in broiler chickens and its amelioration by polyherbal mixture enriched feed (PHMEF). Thirty broiler chickens were divided into five groups. Chickens of group 1 were kept as control (C1). Chickens of group T1, T2, T3 and T4 were exposed to cadmium (as cadmium chloride) through drinking water (100 ppm), Vitamin C with Vitamin E (250 mg/kg each) in feed + Cd in drinking water (100 ppm), PHMEF (2%) alone, and PHMEF (2%) + cadmium in drinking water (100 ppm) for 28 days, respectively. Haematology, serum biochemical parameters, oxidative stress parameters like superoxide dismutase, catalase, reduced-glutathione and malondialdehyde, cadmium accumulation in organs like kidney, liver and thigh muscle, scanning electron microscopy (SEM) of ileum, and histopathological examination of kidney, liver and intestine were performed to evaluate toxicity of cadmium and ameliorating potential of PHMEF in broiler chickens. PHMEF modifies biochemical parameters, and oxidative stress markers. There was a significant reduction of cadmium accumulations in the PHMEF treated group. Polyherbal mixture enriched feed showed ameliorating effect against cadmium induced toxicity due to antioxidant effect as well as effect on accumulation of the cadmium in chickens
SAO 75669: A late type giant behind the molecular cloud MBM 12
Photometric and spectroscopic observations of the star SAO 75669 in the region of the high galactic latitude molecular cloud MBM 12 are presented. The optical, near-infrared and far-infrared IRAS photometric magnitudes together with the observed CCD spectrum and the large degree of polarization are consistent with the star being and M type giant behind the molecular cloud MBM 12 suffering about 1.8 magnitudes visual extinction. The wavelength dependence of polarization indicates that the dust in the cloud is normal
Structural Probe of a Glass Forming Liquid: Generalized Compressibility
We introduce a new quantity to probe the glass transition. This quantity is a
linear generalized compressibility which depends solely on the positions of the
particles. We have performed a molecular dynamics simulation on a glass forming
liquid consisting of a two component mixture of soft spheres in three
dimensions. As the temperature is lowered (or as the density is increased), the
generalized compressibility drops sharply at the glass transition, with the
drop becoming more and more abrupt as the measurement time increases. At our
longest measurement times, the drop occurs approximately at the mode coupling
temperature . The drop in the linear generalized compressibility occurs at
the same temperature as the peak in the specific heat. By examining the
inherent structure energy as a function of temperature, we find that our
results are consistent with the kinetic view of the glass transition in which
the system falls out of equilibrium. We find no size dependence and no evidence
for a second order phase transition though this does not exclude the
possibility of a phase transition below the observed glass transition
temperature. We discuss the relation between the linear generalized
compressibility and the ordinary isothermal compressibility as well as the
static structure factor.Comment: 18 pages, Latex, 26 encapsulated postscript figures, revised paper is
shorter, to appear in Phys. Rev.
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