Search results for "ELECTRICITY"

Parametric self-trapping in the presence of randomized quasi phase matching

2010

We report on experimental evidence of parametric spatial solitons in a quadratic crystal with randomized periodic ferroelectric poling. Two-color self-focusing via quadratic cascading overcomes the diffractive nature of both fundamental and frequency-doubled beams.

Integrated frequency shifter in periodically poled lithium tantalate waveguide

2010

A frequency shifting device is fabricated and tested in a ferroelectric waveguide in a low-photorefractivity crystal. Periodic poling for quasi-phase-matching and channels for operation in the near-infrared C-band were obtained in congruent lithium tantalate, demonstrating for the first time both wave confinement and two-stage parametric conversion in such waveguides.

Free Charge Carriers in Mixed Valency Oxides as Possible Mediators of Magnetoelectric Effect

2009

We show, that in a substance with mixed-valence ions, which can supply free carriers and have electric dipole and spin moments, three types of long-range order (ferromagnetic, ferroelectric and magnetoelectric (ME)) can occur at low temperatures. The origin of the effect is that free charge carriers can mediate the multiferroic behavior via spin – spin (RKKY), dipole-dipole and dipole - spin interactions. We show that there is an optimal carrier concentration, at which the strength of ME interaction is maximal and comparable to that of RKKY interaction. Our analysis shows that disorder and finite conductivity in the above substances does not suppress multiferroic effects.

Transition probabilities of PrII-lines emitted from a ferroelectric plasma source

1991

Abstract An argon-praseodymium plasma was generated under atmospheric pressure between a ceramic ferroelectric plate and a praseodymium plate. The system of plates was connected to an acoustic frequency supply. The plasma radiation was analyzed in the spectral range from 2000 to 7000 A by using a grating spectrograph with a linear dispersion near 1 mm/A, adopted to photoelectric measurements. The emission spectrum of praseodymium was recorded and the intensities of a few hundred lines were measured. Transition probabilities were determined for 62PrII-lines, using available lifetime data for excited levels and measured branching ratios of the corresponding lines. Reasonable agreement has bee…

Eksperimentālā fizika, 2. sējums: Elektrība. Magnetisms. Atombūve

1925

CORRELATIONS AMONG FORWARD RETURNS IN THE NORDIC ELECTRICITY MARKET

2009

I analyze empirical correlations of electricity forward returns from the perspective of a random field model that specifies the correlations in terms of the temporal separation between forward maturities. It turns out that temporal separation cannot fully account for the empirical forward return correlations. Specifically, the relation between correlations and temporal separation does not seem to be invariant across segments of the electricity forward market or trading periods.

Thickness Dependence of Random Field Distribution in Thin Films Made of Disordered Ferroelectrics

2005

Abstract We present the calculation of first moment E 0 and variance ΔE of distribution function of random fields in a ferroelectric of finite size. Specific calculations have been performed for the case of slab-shaped ferroelectric thin film. We have shown that E 0 and ΔE can be expressed through the integrals from first and second degree of Green's function of ferroelectric in k-space. To obtain the Green's function, we solve the differential equation minimizing Landau free energy of a ferroelectric with respect to the boundary conditions on its surfaces. We show that both E 0 and ΔE depend on film thickness L.

Selective quantification of humidity and ammonia by optical excitation of molecular semiconductor-doped insulator (MSDI) sensors

2015

MSDI (molecular semiconductor-doped insulator) ammonia sensors have been investigated using cyclic optical excitation as multi-signal generation method. This method enables a selective quantification of both humidity in the range of 30–70 %rh and ammonia concentration in the range of 0–30 ppm with a single sensor at room temperature.

Blocking of an ion channel by a highly charged drug: Modeling the effects of applied voltage, electrolyte concentration, and drug concentration

2005

We present a simple physical model to estimate the blocked pore probability of an ion channel that can be blocked by a highly charged drug in solution. The model is inspired by recent experimental work on the blocking of the ${\mathrm{PA}}_{63}$ channel, involved in the anthrax toxin infection, by a highly charged drug [Karginov et al. PNAS 102, 15075 (2005)]. The drug binding to the pore is highly specific but the strong dependence of blocking on the applied voltage and electrolyte concentration suggests that long range electrostatic interactions are important. Since basic electrostatic concepts rather than detailed molecular models are considered, the microscopic details of the channel bl…

Molecular dynamics in low-molar and polymeric ferroelectric liquid crystals

1991

Broadband dielectric spectroscopy covering the frequency range from 10−1 Hz to 109 Hz was employed to study the molecular dynamics in low-molar and polymeric ferrroelectric liquid crystals. At frequencies below 106 Hz the ferroelectric modes, soft and Goldstone mode are observed. In the frequency regime from 106 Hz to 109 Hz a fast relaxation process is found, which is assigned to the hindered rotation of the mesogens around their long molecular axis. It turns out that the molecular dynamics is not principally different between low-molar and polymeric systems.