Anomalous Behavior (anomalous + behavior)

Distribution by Scientific Domains


Selected Abstracts


A General Approach to First Order Phase Transitions and the Anomalous Behavior of Coexisting Phases in the Magnetic Case

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
Sergio Gama
Abstract First order phase transitions for materials with exotic properties are usually believed to happen at fixed values of the intensive parameters (such as pressure, temperature, etc.) characterizing their properties. It is also considered that the extensive properties of the phases (such as entropy, volume, etc.) have discontinuities at the transition point, but that for each phase the intensive parameters remain constant during the transition. These features are a hallmark for systems described by two thermodynamic degrees of freedom. In this work it is shown that first order phase transitions must be understood in the broader framework of thermodynamic systems described by three or more degrees of freedom. This means that the transitions occur along intervals of the intensive parameters, that the properties of the phases coexisting during the transition may show peculiar behaviors characteristic of each system, and that a generalized Clausius,Clapeyron equation must be obeyed. These features for the magnetic case are confirmed, and it is shown that experimental calorimetric data agree well with the magnetic Clausius,Clapeyron equation for MnAs. An estimate for the point in the temperature-field plane where the first order magnetic transition turns to a second order one is obtained (the critical parameters) for MnAs and Gd5Ge2Si2 compounds. Anomalous behavior of the volumes of the coexisting phases during the magnetic first order transition is measured, and it is shown that the anomalies for the individual phases are hidden in the behavior of the global properties as the volume. [source]


Anomalous Behavior of Atomic Hydrogen Interacting with Gold Clusters.

CHEMINFORM, Issue 5 2004
Stefan Buckart
Abstract For Abstract see ChemInform Abstract in Full Text. [source]


A General Approach to First Order Phase Transitions and the Anomalous Behavior of Coexisting Phases in the Magnetic Case

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
Sergio Gama
Abstract First order phase transitions for materials with exotic properties are usually believed to happen at fixed values of the intensive parameters (such as pressure, temperature, etc.) characterizing their properties. It is also considered that the extensive properties of the phases (such as entropy, volume, etc.) have discontinuities at the transition point, but that for each phase the intensive parameters remain constant during the transition. These features are a hallmark for systems described by two thermodynamic degrees of freedom. In this work it is shown that first order phase transitions must be understood in the broader framework of thermodynamic systems described by three or more degrees of freedom. This means that the transitions occur along intervals of the intensive parameters, that the properties of the phases coexisting during the transition may show peculiar behaviors characteristic of each system, and that a generalized Clausius,Clapeyron equation must be obeyed. These features for the magnetic case are confirmed, and it is shown that experimental calorimetric data agree well with the magnetic Clausius,Clapeyron equation for MnAs. An estimate for the point in the temperature-field plane where the first order magnetic transition turns to a second order one is obtained (the critical parameters) for MnAs and Gd5Ge2Si2 compounds. Anomalous behavior of the volumes of the coexisting phases during the magnetic first order transition is measured, and it is shown that the anomalies for the individual phases are hidden in the behavior of the global properties as the volume. [source]


Anomalous behavior of the second and third harmonics generated by femtosecond Cr:forsterite laser pulses in SiC,polymer nanocomposite materials as functions of the SiC nanopowder content

JOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2003
S. O. Konorov
Abstract Femtosecond pulses of 1.25 m Cr:forsterite laser radiation were used to study second- and third-harmonic generation in silicon carbide nanopowders embedded in a poly(methyl methacrylate) (PMMA) film. Harmonic generation processes extend the analytical and sensing abilities of light-scattering techniques, including Raman spectroscopy, offering a convenient and efficient approach to the analysis of nanocomposite materials where nanoparticles tend to agglomerate, masking informative features in Raman spectra. The second- and third-harmonic yields are shown to display an anomalous, counterintuitive behavior as functions of the SiC nanopowder content in a polymer film. Whereas harmonic generation in polymer films with a high content of SiC nanocrystals is quenched by the absorption of agglomerating nanoparticles, the influence of absorption is less detrimental in nanocomposite films with a lower SiC content, leading to the growth of the second- and third-harmonic yields. Nanocomposite films with a lower SiC content are also characterized by a higher breakdown threshold, allowing pump pulses with higher fluences to be applied for more efficient harmonic generation. Copyright 2003 John Wiley & Sons, Ltd. [source]


MONITORING BEHAVIOR WITH AN ARRAY OF SENSORS

COMPUTATIONAL INTELLIGENCE, Issue 4 2007
Dorothy N. Monekosso
The objective is to detect activities taking place in a home and to create a model of behavior for the occupant. A behavior is a pattern in the sequence of activities. An array of sensors captures the status of appliances. Models for the occupant's activities are built from the captured data using supervised and unsupervised learning techniques. The models of behavior are built using the hidden Markov model (HMM) technique. Predictive models can be used in a number of ways: to enhance user experience, to maximize resource usage efficiency, for safety and security. This work focuses on supporting independent living and enhancing quality of life of older persons. The ultimate goal is for the system to distinguish between normal and anomalous behavior. In this paper, we present the results of comparing supervised and unsupervised classification techniques applied to the problem of modeling activity for the purpose of modeling behavior in a home. [source]


Anomalous Oxidation States in Multilayers for Fuel Cell Applications

ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010
James M. Perkins
Abstract Significant recent interest has been directed towards the relationship between interfaces and reports of enhanced ionic conductivity. To gain a greater understanding of the effects of hetero-interfaces on ionic conductivity, advanced analytical techniques including electron microscopy (TEM/STEM), electron energy loss spectroscopy (EELS), and secondary ion mass spectrometry (SIMS) are used to characterize CeO2/Ce0.85Sm0.15O2 multilayer thin films grown by pulsed laser deposition. High quality growth is observed, but ionic conductivity measured by impedance spectroscopy and 18O tracer experiments is consistent with bulk materials. EELS analysis reveals the unusual situation of layers containing only Ce(IV) adjacent to layers containing both Ce(III) and Ce(IV). Post oxygen annealing induced oxygen diffusion and mixed oxidation states in both layers, but only in the vicinity of low angle grain boundaries perpendicular to the layers. The implications of the anomalous behavior of the Ce oxidation states on the design of novel electrolytes for solid oxide fuel cells is discussed. [source]


Towards a debugging system for sensor networks

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 4 2005
Nithya Ramanathan
Due to their resource constraints and tight physical coupling, sensor networks afford limited visibility into an application's behavior. As a result it is often difficult to debug issues that arise during development and deployment. Existing techniques for fault management focus on fault tolerance or detection; before we can detect anomalous behavior in sensor networks, we need first to identify what simple metrics can be used to infer system health and correct behavior. We propose metrics and events that enable system health inferences, and present a preliminary design of Sympathy, a debugging tool for pre- and post-deployment sensor networks. Sympathy will contain mechanisms for collecting system performance metrics with minimal memory overhead; mechanisms for recognizing application-defined events based on these metrics; and a system for collecting events in their spatiotemporal context. The Sympathy system will help programmers draw correlations between seemingly unrelated, distributed events, and produce graphs that highlight those correlations. As an example, we describe how we used a preliminary version of Sympathy to help debug a complex application, Tiny Diffusion.,Copyright 2005 John Wiley & Sons, Ltd. [source]


Atomistic analysis of B clustering and mobility degradation in highly B-doped junctions

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 4-5 2010
Maria Aboy
Abstract In this paper we discuss from an atomistic point of view some of the issues involved in the modeling of electrical characteristics evolution in silicon devices as a result of ion implantation and annealing processes in silicon. In particular, evolution of electrically active dose, sheet resistance and hole mobility has been investigated for high B concentration profiles in pre-amorphized Si. For this purpose, Hall measurements combined with atomistic kinetic Monte Carlo atomistic simulations have been performed. An apparent anomalous behavior has been observed for the evolution of the active dose and the sheet resistance, in contrast to opposite trend evolutions reported previously. Our results indicate that this anomalous behavior is due to large variations in hole mobility with active dopant concentration, much larger than that associated to the classical dependence of hole mobility with carrier concentration. Simulations suggest that hole mobility is significantly degraded by the presence of a large concentration of boron-interstitial clusters, indicating the existence of an additional scattering mechanism. Copyright 2009 John Wiley & Sons, Ltd. [source]


Ground states of BeC and MgC: A comparative multireference Brillouin,Wigner coupled cluster and configuration interaction study,

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2005
Vasilios I. Teberekidis
Abstract The competing X3,, and 5,, states of the experimentally unknown alkaline,earth metal carbides BeC and MgC are examined with the multireference Brillouin,Wigner coupled cluster method restricted to single and double excitations (MRBW-CCSD). The results are compared against the traditional single-reference CCSD approach, as well as with other single and multireference methods. In both molecules, the CCSD 5,, , X3,, energy difference is underestimated, leading to an "erroneous" ground-state prediction in BeC. The MRBW-CCSD method corrects this anomalous behavior, leading to fair agreement with multireference configuration interaction (MR-CI) predictions. Our results at the highest levels of theory are extrapolated to the basis set limit, and the core/valence correlation is taken into account, leading to very accurate energetics and spectroscopic constants in both carbides. 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source]


Anomalous rheological response for binary blends of linear polyethylene and long-chain branched polyethylene

ADVANCES IN POLYMER TECHNOLOGY, Issue 3 2007
Naoya Mieda
Abstract The rheological properties are studied for binary blends composed of a low-density polyethylene (LDPE) and a linear polyethylene. It is found that some blends exhibit higher oscillatory shear moduli and drawdown force than the individual pure components, demonstrating that relaxation mechanism with longer characteristic time appears in the blend. The anomalous rheological behavior is detected more clearly for the blends with autoclave-LDPE than those with tubular-LDPE. Furthermore, the number of short-chain branches in a linear polyethylene has no influence on the rheological properties of the blends, suggesting that the phase separation will not be responsible for the anomalous behavior. It is also found that blends of autoclave-LDPE and tubular-LDPE show no synergetic effect. 2008 Wiley Periodicals, Inc. Adv Polym Techn 26:173,181, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20100 [source]


Raman scattering studies of the magnetic ordering in hexagonal HoMnO3 thin films

JOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2010
Nguyen Thi Minh Hien
Abstract We present the results of the temperature dependence of the Raman spectra of hexagonal HoMnO3 thin films in the 13,300 K temperature range. The films were grown on Pt(111)//Al2O3 (0001) substrates using the laser ablation method. In the HoMnO3 thin films, we initially observedseveral broad Raman peaks at ,510, 760, 955, 1120, and 1410 cm,1. These broad Raman peaks display an anomalous behavior near the magnetic transition temperature, and the intensity difference of the Raman spectra at different temperatures shows several pairs of negative and positive peaks as the temperature is lowered below the Nel temperature. Our analyses indicate that all the broad peaks are correlated with magnetic ordering, and we have assigned the origin of all the broad peaks. Purely on the basis of the Raman analysis, we have deduced the Nel temperature and the spin exchange integrals of HoMnO3 thin films. We also investigated the effects of the growth condition on the strongest broad peak at ,760 cm,1, which is related with pure magnetic ordering. This result indicates that the oxygen defect in the HoMnO3 sample has negligible effect on magnetic ordering. Copyright 2009 John Wiley & Sons, Ltd. [source]


Chimpanzee Theory of Mind: Looking in All the Wrong Places?

MIND & LANGUAGE, Issue 5 2005
Kristin Andrews
I argue that Povinelli and Vonk's proposed experiment is subject to their own criticisms and that there should be a more radical shift away from experiments that ask subjects to predict behavior. Further, I argue that Povinelli and Vonk's theoretical commitments should lead them to accept this new approach, and that experiments which offer subjects the opportunity to look for explanations for anomalous behavior should be explored. [source]


How do electronic properties of conventional III,V semiconductors hold for the III,V boron bismuth BBi compound?

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 14 2005
D. Madouri
Abstract We have performed ab-initio self-consistent calculations using the full potential linear augmented plane wave method to investigate the structural and the electronic properties of the boron bismuth III,V compound BBi. Our calculations provide the first available information about the structural and electronic ground-state properties of BBi. Total energy calculations of the cubic zinc-blende, wurtzite, rock-salt, cesium chloride and orthorhombic Cmcm phases are made. The zinc-blende structure is found to be the ground-state phase of BBi; within the generalized gradient approximation (local density approximation), we found a lattice constant of 5.529 (5.416 ) and a bulk modulus of 72.20 GPa (86.27 GPa). We found that, contrary to other boron compounds, the band gap of BBi is direct at the , point. The relativistic contraction of the 6s orbital of Bi has a strong influence on the bands and bonds of BBi. Consequently, the electronic properties of BBi are shown to differ considerably from those of common group III,V semiconductors (e.g. GaAs); in particular, we found an unusually strong p,p mixing of the valence-band maximum relative to most of the other III,V compounds. Furthermore, the calculated valence charge density shows an anomalous behavior, characterized by a charge transfer towards the ,cation' B atom, further illustrating the rich behavior of boron bismuth compounds. ( 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]