191 research outputs found
Resistive switching in ultra-thin La0.7Sr0.3MnO3 / SrRuO3 superlattices
Superlattices may play an important role in next generation electronic and
spintronic devices if the key-challenge of the reading and writing data can be
solved. This challenge emerges from the coupling of low dimensional individual
layers with macroscopic world. Here we report the study of the resistive
switching characteristics of a of hybrid structure made out of a superlattice
with ultrathin layers of two ferromagnetic metallic oxides, La0.7Sr0.3MnO3
(LSMO) and SrRuO3 (SRO). Bipolar resistive switching memory effects are
measured on these LSMO/SRO superlattices, and the observed switching is
explainable by ohmic and space charge-limited conduction laws. It is evident
from the endurance characteristics that the on/off memory window of the cell is
greater than 14, which indicates that this cell can reliably distinguish the
stored information between high and low resistance states. The findings may
pave a way to the construction of devices based on nonvolatile resistive memory
effects
Implementing Dynamically Evolvable Communication with Embedded Systems through WEB Services
Embedded systems that monitor and control safety and mission critical system are communicated with by a HOST located at a remote location through Internet. Such kind of embedded systems are developed to be dynamically evolvable with respect to syntax, semantics, online testing and communication subsystems. All these systems are to be dynamically evolvable and the components needed for evolution are also to be added into the embedded system. Architectural models describe various components using which dynamically evolvable sub-systems are realised through implementation by using specific and related technologies. Implementation system describe the platform, code units and the interlacing of various processes/tasks to the elementary level of details. WEB services place an excellent platform for implementing dynamically evolvable systems due to the use of open standards. This paper presents an implementation system that is related to dynamically evolvable communication and other sub-systems using web services technologies
Martensite-like transition and spin-glass behavior in nanocrystalline Pr0.5Ca0.5MnO3
We report on isothermal pulsed (20 ms) field magnetization, temperature
dependent AC - susceptibility, and the static low magnetic field measurements
carried out on 10 nm sized Pr0.5Ca0.5MnO3 nanoparticles (PCMO10). The
saturation field for the magnetization of PCMO10 (~ 250 kOe) is found to be
reduced in comparison with that of bulk PCMO (~300 kOe). With increasing
temperature, the critical magnetic field required to 'melt' the residual
charge-ordered phase decays exponentially while the field transition range
broadens, which is indicative of a Martensite-like transition. The AC -
susceptibility data indicate the presence of a frequency-dependent freezing
temperature, satisfying the conventional Vogel-Fulcher and power laws, pointing
to the existence of a spin-glass-like disordered magnetic phase. The present
results lead to a better understanding of manganite physics and might prove
helpful for practical applications
Implementing Syntax Evolution of Embedded Systems
Safety critical systems such as nuclear recator systems cannot be shutdown as restrating is a huge process and incurs heavy cost. The embedded systems which are used for monitoring and controlling the safety critival systems cannot be shut down as well. ES systems which drives safety critical systems must be communicated from remote locations generally through a HOST connected on to Internet. Communication between the HOST and ES system is done using commnd lanaguage which has to be evolved from time to time. The chnage to the commnd lanauage must be undertaken while the embedded system is up and running, the evolution thus must be dynamic. Many architetcuers have been propsoed in the lieteratuer for evolving synatx of command lanaguage.The implemntaion of effcient architetcuer as such has not been found in the literatuer without which existing architetcuer as such has no menaing.The paper presntes a set of methods using which the syntax evolution of embedded systems as such can be achived. The synatx evolution methods have been applied to a safety critical system that monitors and controls tempartuers within a Nuclear recator system
Stability of geometrically frustrated magnetic state of Ca3CoRhO6 to applications of positive and negative pressure
The influence of negative chemical pressure induced by gradual replacement of
Ca by Sr as well as of external pressure (up to 10 kbar) on the magnetism of
Ca3CoRhO6 has been investigated by magnetization studies. It is found that the
solid solution, Ca(3-x)Sr(x)CoRhO6, exists at least till about x= 1.0 without
any change in the crystal structure. Apart from insensitivity of the spin-chain
feature to volume expansion, the characteristic features of geometrical
frustration interestingly appear at the same temperatures for all compositions,
in sharp contrast to the response to Y substitution for Ca (reported
previously). Interestingly, huge frequency dependence of ac susceptibility
known for the parent compound persists for all compositions. We do not find a
change in the properties under external pressure. The stability of the magnetic
anomalies of this compound to the volume change (about 4%) is puzzling
Exploring wind direction and SO2 concentration by circular-linear density estimation
The study of environmental problems usually requires the description of
variables with different nature and the assessment of relations between them.
In this work, an algorithm for flexible estimation of the joint density for a
circular-linear variable is proposed. The method is applied for exploring the
relation between wind direction and SO2 concentration in a monitoring station
close to a power plant located in Galicia (NW-Spain), in order to compare the
effectiveness of precautionary measures for pollutants reduction in two
different years.Comment: 17 pages, 7 figures, 2 table
Adaptive Density Estimation on the Circle by Nearly-Tight Frames
This work is concerned with the study of asymptotic properties of
nonparametric density estimates in the framework of circular data. The
estimation procedure here applied is based on wavelet thresholding methods: the
wavelets used are the so-called Mexican needlets, which describe a nearly-tight
frame on the circle. We study the asymptotic behaviour of the -risk
function for these estimates, in particular its adaptivity, proving that its
rate of convergence is nearly optimal.Comment: 30 pages, 3 figure
The variational Bayesian approach to fitting mixture models to circular wave direction data
The emerging variational Bayesian (VB) technique for approximate Bayesian statistical inference is a nonsimulation- based and time-efficient approach. It provides a useful, practical alternative to other Bayesian statistical approaches such as Markov chain Monte Carlo–based techniques, particularly for applications involving large datasets. This article reviews the increasingly popular VB statistical approach and illustrates how it can be used to fit Gaussian mixture models to circular wave direction data. This is done by taking the straightforward approach of padding the data; this method involves adding a repeat of a complete cycle of the data to the existing dataset to obtain a dataset on the real line. The padded dataset can then be analyzed using the standard VB technique. This results in a practical, efficient approach that is also appropriate for modeling other types of circular, or directional, data such as wind direction
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