343 research outputs found
Screen-printing of ferrite magnetic nanoparticles produced by carbon combustion synthesis of oxides
The feasibility of screen-printing process of hard ferrite magnetic nanoparticles produced by carbon combustion synthesis of oxides (CCSO) is investigated. In CCSO, the exothermic oxidation of carbon generates a smolder thermal reaction wave that propagates through the solid reactant mixture converting it to the desired oxides. The complete conversion of hexaferrites occurs using reactant mixtures containing 11 wt. % of carbon. The BaFe12O19 and SrFe12O19 hexaferrites had hard magnetic properties with coercivity of 3 and 4.5 kOe, respectively. It was shown that the synthesized nanoparticles could be used to fabricate permanent magnet structures by consolidating them using screen-printing techniques
Transfer ionization and its sensitivity to the ground-state wave function
We present kinematically complete theoretical calculations and experiments
for transfer ionization in HHe collisions at 630 keV/u. Experiment and
theory are compared on the most detailed level of fully differential cross
sections in the momentum space. This allows us to unambiguously identify
contributions from the shake-off and two-step-2 mechanisms of the reaction. It
is shown that the simultaneous electron transfer and ionization is highly
sensitive to the quality of a trial initial-state wave function
Physiological aspects of educational training adaptation of students
20 healthy male and female students of Artsakh State University aged 18-20 years have participated in an experiment to study the mechanisms of training adaptation. Surveys were conducted during the academic semester in 2 stages: the non-examination period (March-April) - Monday and Friday, before and after school and during the examination period (May-June) - before and after the exam. In order to study the impact of mental stress a survey was also conducted among students once they complete mental or intellectual Eysenck test. A psychological testing of students was carried out to identify the level of intelligence (IQ) by Eysenck, personal and situational anxiety by Spielberger and health, activity, mood by SAN (HAM) questionnaire. Basic hemodynamic parameters were measured: heart rate, systolic and diastolic blood pressure. ECG examination was conducted using R.M. Baevsky's cardio-ervalography method. Comparative analysis of the dynamics of the studied parameters showed that the process of adaptation of students to the teaching load is accompanied by periods of decline during non-examination period, more vividly expressed when doing mental or intellectual work, and tension of the studied parameters during the examination period
Statistical Mechanics of Semi-Supervised Clustering in Sparse Graphs
We theoretically study semi-supervised clustering in sparse graphs in the
presence of pairwise constraints on the cluster assignments of nodes. We focus
on bi-cluster graphs, and study the impact of semi-supervision for varying
constraint density and overlap between the clusters. Recent results for
unsupervised clustering in sparse graphs indicate that there is a critical
ratio of within-cluster and between-cluster connectivities below which clusters
cannot be recovered with better than random accuracy. The goal of this paper is
to examine the impact of pairwise constraints on the clustering accuracy. Our
results suggests that the addition of constraints does not provide automatic
improvement over the unsupervised case. When the density of the constraints is
sufficiently small, their only impact is to shift the detection threshold while
preserving the criticality. Conversely, if the density of (hard) constraints is
above the percolation threshold, the criticality is suppressed and the
detection threshold disappears.Comment: 8 pages, 4 figure
Emission Spectrum of a Dipole in a Semi-infinite Periodic Dielectric Structure: Effect of the Boundary
The emission spectrum of a dipole embedded in a semi-infinite photonic
crystal is calculated. For simplicity we study the case in which the dielectric
function is sinusoidally modulated only along the direction perpendicular to
the boundary surface plane. In addition to oscillations of the emission rate
with the distance of the dipole from the interface we also observed that the
shape of the emission spectrum srongly depends on the \em initial \em phase
of the dielectric modulation. When the direction of light propagation inside
the periodic structure is not normal to the boundary surface plane we observed
aditional singularities in the emission spectrum, which arise due to different
angle-dependence of the Bragg stop-band for and polarizations.Comment: 14 pages, 6 figures, to appear in Phys Rev
- …