A medium/low voltage transformer from a distribution substation for urban transports operating in a highly distorting regime is analyzed. Regimes of idle running, running with non-linear load, ...respectively fault (short-circuit) are presented from the theoretical point of view. The results yielded by their operation simulation using MATLAB / SIMULINK are discussed. Aspects related to the measurement and harmonic analysis of voltages and currents are analyzed, along with experimental results related to the highly distorted regime influence over the primary and secondary windings. Losses in distribution transformers due to non-linear loads resulting into (no-) load losses due to increased skin effect, eddy current, stray and losses through hysteresis with negative effects over the lifespan of the transformers and total costs are discussed too. As the analysis revealed that the harmonic content and reactive power must be diminished, some solutions are suggested. A relative cheap solution (not necessarily the best) is passive filtering. A more efficient solution for the compensation of the distorting regime is the active filtering, this being efficiently adaptable to the analyzed system's operating regimes, resulting into power savings and transformer's operation at the rated parameters. Another good solution is the substitution of old transformers (particularly sensitive to non-linear loads) by more efficient transformers.
Astrophys.J. 580 (2002) 16-28 We study the CMB anisotropy induced by the non-linear perturbations in the
massive neutrino density associated to the non-linear gravitational clustering
proceses. Our ...results show that for the neutrino fraction in agreement with
that indicated by the astroparticle and nuclear physics experiments and a
cosmological accreting mass comparable with the mass of known clusters, the
angular resolution and the sensitivity of the CMB anisotropy measurements from
the Planck surveyor will allow the detection of the dynamical effects of the
neutrino gravitational clustering.
The paper presents considerations regarding the problematic of induction generator's (IG) self excitation. There are considered the known issues, such as load loss racing, excitation reactive energy ...compensation, self-excitation and plant interconnection. The conducted theoretical and experimental studies permitted the establishment of technical conditions necessary for a normal operation of an IG in energy power stations..
A number of 87 reinterventions performed during a 5-year-period for late complications of the gastric and duodenal ulcer surgery are analysed. In most of them (64 cases), the cause of the ...reintervention was a postoperative ulcer. A long afferent loop (6 cases), the dumping syndrome (4 cases), the stenosis of the anastomosis opening (6 cases) and the primitive neoplasm of the gastric stump (7 cases) represented other causes of reintervention. The immediate postoperative results were very good and good in 69 cases. The risks related to the specific character of this surgery materialized themselves in 14 postoperative complications (anastomotic fistulas, haemorrhages from the anastomosis, stress ulcers etc.), which required iterative operations; the postoperative death rate attained 3.4%. The analysis of these postgastrectomy syndromes is an opportunity to discuss about the failure factors in the surgery of the gastric and duodenal ulcer, the possibilities of exploration and the principles which should guide the reparative therapy.
We investigate the role of the radiative effects for the temporal evolution of the reionization fraction by using cosmological Smooth Particle Hydrodynamics (SPH) simulations. We find that the ...increase of photo-ionization and photo-heating rates due to optical depth effects results in a significantly contribute to the heating of the IGM before and during the reionization. The main effect of the UV radiation spectrum on the temporal evolution of the ionization fraction is given by the value of the reionization redshift and the redshift interval, in which the reionization is completed. We evaluate the effects of the UV radiation background on the CMB angular power spectrum taking into account different temporal evolutions of the ionization fraction. We show that through E-mode CMB polarization power spectrum measurements, the Planck experiment will have the sensitivity to distinguish between different reionization histories even when they imply the same optical depth to electron scattering and degenerated temperature anisotropy power spectra.
We study the complementarity between the cosmological information obtainable
with the Planck surveyour and the large scale structure (LSS) redshift surveys
in LambdaCHDM cosmologies. We compute the ...initial full phase-space neutrino
distribution function for LambdaCHDM models by using numerical simulations. As
initial condition we adopt the HDM density fluctuation power spectrum
normalized on the basis of the analysis of the local cluster X-ray temperature
function and derive the initial neutrino phase-space distribution at each
spatial wave number k by using the Zel'dovich approximation. These initial
neutrino phase-space distributions are implemented in the CMBFAST code for the
integration of the coupled linearized Einstein, Boltzmann and fluid equations
in k-space. We find that the relative bias between the CMB temperature
fluctuations and the underlying matter density fluctuation power spectrum in
COBE/DMR normalization is given by the CDM component normalized accordingly to
the abundance of rich clusters at the present time. We use the Fisher
information matrix approximation to constrain a multi-dimensional
parametrization of the LambdaCHDM model, by jointly considering CMB and large
scale structure data according to the Planck and the SDSS experimental
specifications and by taking into account redshift distortions and nonlinear
effects on the matter power spectrum. We found that, although the CMB
anisotropy and polarization measurements tend to dominate the constraints on
most of the cosmological parameters, the additional small scale LSS data help
to break the parameter degeneracies. This work has been done in the framework
of the Planck LFI activities.
Escherichia coli ribosomes display a remarkable heterogeneity when submitted to polyacrylamide‐gel electrophoresis (4% acrylamide). Both the 70‐S ribosomes and 50‐S ribosomal subunits are resolved ...into at least four and the 30‐S ribosomal subunits into three particle subclasses.
After reversal of the current, all particles refocus into one single band at the origin. Ribosomes recovered from the gel after electrophoresis have retained some 40–100% of their capacity to synthesize peptide bonds. Their sedimentation behaviour has remained unaltered. Upon reelectrophoresis, no new peaks are detectable although the relative proportions of the various subclasses are frequently changed. The ratio in the occurrence of these subclasses is readily affected by a variety of factors, however, some of which are not directly related to the electrophoretic technique itself.
The three classes of ribosomes and subunits (70‐S, 50‐S and 30‐S) display approximately equal electrophoretic mobilities when the sieving action is reduced to a minimum. This conclusion follows from experiments in which the ribosomes are submitted to electrophoresis in a sucrose gradient or in 0.4% agarose gels. In contrast, electrophoresis in polyacrylamide gels with a gradient in pore size reveals the same ribosomal diversity as noted in gels with a fixed acrylamide concentration of 4%. In these pore‐gradient gels (3‐8% acrylamide), the migration rate of each ribosomal subclass decreases continuosly when the time of electrophoresis is prolonged. After about 30 h, further penetration seems to be blocked.
All three classes consist of particles with low electrophoretic mobility (designated I particles) and those which move faster (designated II particles). The I particles are partially converted to II particles by incubation at 37 °C and/or pelleting prior to electrophoresis. The II particles are converted to I particles upon raising the ribosome concentration. The electrophoretic profiles displayed by the various 50‐S subclasses are not strongly affected by variations in Mg2+ concentration in the range 0.5‐10.0 mM. The electropherograms of 30‐S subunits become more diffuse when the Mg2+ concentration is raised. The possible occurrence of ribosomal dimers and/or conformation changes is discussed.
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