6,461 research outputs found
Observation of a temperature dependent electrical resistance minimum above the magnetic ordering temperature in GdPdSi
Results on electrical resistivity, magnetoresistance, magnetic Results on
electrical resistivity, magnetoresistance, magnetic susceptibility, heat
capacity and Gd Mossbauer measurements on a Gd-based intermetallic compound,
GdPdSi are reported. A finding of interest is that the resistivity
unexpectedly shows a well-defined minimum at about 45 K, well above the long
range magnetic ordering temperature (21 K), a feature which gets suppressed by
the application of a magnetic field. This observation in a Gd alloy presents an
interesting scenario. On the basis of our results, we propose electron
localization induced by s-f (or d-f) exchange interaction prior to long range
magnetic order as a mechanism for the electrical resistance minimum.Comment: 4 pages, 4 figure
Magnetic behaviour of Eu_2CuSi_3: Large negative magnetoresistance above Curie temperature
We report here the results of magnetic susceptibility,
electrical-resistivity, magnetoresistance (MR), heat-capacity and ^{151}Eu
Mossbauer effect measurements on the compound, Eu_2CuSi_3, crystallizing in an
AlB_2-derived hexagonal structure. The results establish that Eu ions are
divalent, undergoing long-range ferromagnetic-ordering below (T_C=) 37 K. An
interesting observation is that the sign of MR is negative even at temperatures
close to 3T_C, with increasing magnitude with decreasing temperature exhibiting
a peak at T_C. This observation, being made for a Cu containing magnetic
rare-earth compound for the first time, is of relevance to the field of
collosal magnetoresistance.Comment: To appear in PRB, RevTex, 4 pages text + 6 psFigs. Related to our
earlier work on Gd systems (see cond-mat/9811382, cond-mat/9811387,
cond-mat/9812069, cond-mat/9812365
Magnetic anisotropy, first-order-like metamagnetic transitions and large negative magnetoresistance in the single crystal of GdPdSi
Electrical resistivity (), magnetoresistance (MR), magnetization,
thermopower and Hall effect measurements on the single crystal
GdPdSi, crystallizing in an AlB-derived hexagonal structure are
reported. The well-defined minimum in at a temperature above N\'eel
temperature (T= 21 K) and large negative MR below 3T, reported
earlier for the polycrystals, are reproducible even in single crystals. Such
features are generally uncharacteristic of Gd alloys. In addition, we also
found interesting features in other data, e.g., two-step first-order-like
metamagnetic transitions for the magnetic field along [0001] direction. The
alloy exhibits anisotropy in all these properties, though Gd is a S-state ion.Comment: RevTeX, 5 pages, 6 encapsulated postscript figures; scheduled to be
published in Phy. Rev. B (01 November 1999, B1
La substitution induced linear temperature dependence of electrical resistivity and Kondo behavior in the alloys, Ce_{2-x}La_{x}CoSi_{3}
The results of electrical resistivity, heat capacity and magnetic
susceptibility behavior of new class of alloys, Ce_{2-x}La_{x}CoSi_{3}, are
reported. The x= 0.0 alloy is mixed valent and La substitution for Ce (x= 0.25)
induces linear temperature dependence of resistivity at low temperatures, an
observation of relevance to the topic of non-Fermi liquid behavior. The
modifications of Kondo effect for all the alloys are also presented.Comment: Accepted for publication in Solid State Communication
Design optimization and performance capabilities of the fast neutron imaging telescope (FNIT)
We describe the design optimization process and performance characterization of a next generation neutron telescope, with imaging and energy measurement capabilities, sensitive to neutrons in the 1-20 MeV energy range. The response of the Fast Neutron Imaging Telescope (FNIT), its efficiency in neutron detection, energy resolution and imaging capabilities were characterized through a combination of lab tests and Monte Carlo simulations. Monte Carlo simulations, together with experimental data, are also being used in the development and testing of the image reconstruction algorithm. FNIT was initially conceived to study solar neutrons as a candidate instrument for the Inner Heliosphere Sentinel (IHS) spacecraft. However, the design of this detector was eventually adapted to locate Special Nuclear Material (SNM) sources for homeland security purposes, by detecting fission neutrons. In either case, the detection principle is based on multiple elastic neutron-proton scatterings in organic scintillator. By reconstructing event locations and measuring the recoil proton energies, the direction and energy spectrum of the primary neutron flux can be determined and neutron sources identified. This paper presents the most recent results arising from our efforts and outlines the performance of the FNIT detector
Multi-layer Architecture For Storing Visual Data Based on WCF and Microsoft SQL Server Database
In this paper we present a novel architecture for storing visual data.
Effective storing, browsing and searching collections of images is one of the
most important challenges of computer science. The design of architecture for
storing such data requires a set of tools and frameworks such as SQL database
management systems and service-oriented frameworks. The proposed solution is
based on a multi-layer architecture, which allows to replace any component
without recompilation of other components. The approach contains five
components, i.e. Model, Base Engine, Concrete Engine, CBIR service and
Presentation. They were based on two well-known design patterns: Dependency
Injection and Inverse of Control. For experimental purposes we implemented the
SURF local interest point detector as a feature extractor and -means
clustering as indexer. The presented architecture is intended for content-based
retrieval systems simulation purposes as well as for real-world CBIR tasks.Comment: Accepted for the 14th International Conference on Artificial
Intelligence and Soft Computing, ICAISC, June 14-18, 2015, Zakopane, Polan
On the stability of an infinite swept attachment line boundary layer
The instability of an infinite swept attachment line boundary layer is considered in the linear regime. The basic three dimensional flow is shown to be susceptible to travelling wave disturbances which propagate along the attachment line. The effect of suction on the instability is discussed and the results suggest that the attachment line boundary layer on a swept wing can be significantly stabilized by extremely small amounts of suction. The results obtained are in excellent agreement with the available experimental observations
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