1,226 research outputs found
Elastic properties of cubic crystals: Every's versus Blackman's diagram
Blackman's diagram of two dimensionless ratios of elastic constants is
frequently used to correlate elastic properties of cubic crystals with
interatomic bondings. Every's diagram of a different set of two dimensionless
variables was used by us for classification of various properties of such
crystals. We compare these two ways of characterization of elastic properties
of cubic materials and consider the description of various groups of materials,
e.g. simple metals, oxides, and alkali halides. With exception of intermediate
valent compounds, the correlation coefficients for Every's diagrams of various
groups of materials are greater than for Blackaman's diagrams, revealing the
existence of a linear relationship between two dimensionless Every's variables.
Alignment of elements and compounds along lines of constant Poisson's ratio
, ( arbitrary perpendicular to ) is
observed. Division of the stability region in Blackman's diagram into region of
complete auxetics, auxetics and non-auxetics is introduced. Correlations of a
scaling and an acoustic anisotropy parameter are considered.Comment: 8 pages, 9 figures, presented on The Ninth International School on
Theoretical Physics "Symmetry and Structural Properties of Condensed Matter",
5 - 12 September 2007, Myczkowce, Polan
Surfactant mixtures at the oil–water interface
NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Colloid and Interface Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in JOURNAL OF COLLOID AND INTERFACE SCIENCE, VOL 398, (2013) DOI 10.1016/j.jcis.2013.01.06
Evidence for Charging Effects in CdTe/CdMgTe Quantum Point Contacts
Here we report on fabrication and low temperature magnetotransport
measurements of quantum point contacts patterned from a novel two-dimensional
electron system - CdTe/CdMgTe modulation doped heterostructure. From the
temperature and bias dependence we ascribe the reported data to evidence for a
weakly bound state which is naturally formed inside a CdTe quantum
constrictions due to charging effects. We argue that the spontaneous
introduction of an open dot is responsible for the replacement of flat
conductance plateaus by quasi-periodic resonances with amplitude less than
2e^{2}/h, as found in our system. Additionally, below 1 K a pattern of weaker
conductance peaks, superimposed upon wider resonances, is also observed.Comment: 4 pages, 4 figure
Dynamics of the Tippe Top -- properties of numerical solutions versus the dynamical equations
We study the relationship between numerical solutions for inverting Tippe Top
and the structure of the dynamical equations. The numerical solutions confirm
oscillatory behaviour of the inclination angle for the symmetry
axis of the Tippe Top. They also reveal further fine features of the dynamics
of inverting solutions defining the time of inversion. These features are
partially understood on the basis of the underlying dynamical equations
Effect of interface resistance on thermoelectric properties in (1-x)LaSrCoMnO/(x)WC composite
In this study, the synergistic effect of the particle size of the dispersed
phase and the interface thermal resistance (R) between the phases on
the phonon thermal conductivity () of the
(1-x)LaSrCoMnO/(x)WC thermoelectric
composite, is demonstrated. Further, the correlation between the R and
the Kapitza radius is discussed using the Bruggeman's asymmetrical model. In
particular, the polycrystalline
LaSrCoMnO sample is synthesized using a
standard-solid state route. The presence of WC nanoparticle is confirmed from
the electron microscopy images. Electrical conductivity () increases,
and the Seebeck coefficient () decreases with the increase in
conducting WC volume fraction in the composite. The simultaneous increase in
and a decrease in with the WC volume fraction results in
an increased figure of merit (zT) for
(1-x)LaSrCoMnO/(x)WC composite. A
maximum zT 0.20 is obtained for
(1-x)LaSrCoMnO/(x)WC composite for
x=0.010 at 463 K. The results obtained in the present study shows promise to
design thermoelectric composites with desired phonon thermal conductivity
considering the elastic properties between the phases.Comment: 15 pages, 6 figures, 1 tabl
Study of high altitude plume impingement
Computer program has been developed as analytical tool to predict severity of effects of exhaust of rocket engines on adjacent spacecraft surfaces. Program computes forces, moments, pressures, and heating rates on surfaces immersed in or subjected to exhaust plume environments. Predictions will be useful in design of systems where such problems are anticipated
Reasoning about transfinite sequences
We introduce a family of temporal logics to specify the behavior of systems
with Zeno behaviors. We extend linear-time temporal logic LTL to authorize
models admitting Zeno sequences of actions and quantitative temporal operators
indexed by ordinals replace the standard next-time and until future-time
operators. Our aim is to control such systems by designing controllers that
safely work on -sequences but interact synchronously with the system in
order to restrict their behaviors. We show that the satisfiability problem for
the logics working on -sequences is EXPSPACE-complete when the
integers are represented in binary, and PSPACE-complete with a unary
representation. To do so, we substantially extend standard results about LTL by
introducing a new class of succinct ordinal automata that can encode the
interaction between the different quantitative temporal operators.Comment: 38 page
- …