A diffusion-cooled $CO_2$ laser using a coaxial waveguide is investigated theoretically. The resonator extracting the laser beam consits of two annular plane mirrors enclosing the two ends of the ...waveguide. A theoretical resonator model based on the vector modes of propagation in a dielectric coaxial waveguide is described.
The electrical properties of a-Si:( H ) and a- SiN ):( H ) films prepared by plasma deposition from SiH4+NH3 gas mixtures have been investigated. We observed anomalous peaks in the temperature ...dependent dark conductivity curves of annealed a-Si:H and a-SiN:H samples when the temperatures were increased from 90 K to room temperature at a constant heating rate. To study the surface adsorption effect, vacuum cryostat pressure dependence of these peaks are investigated. We have also studied the effect of nitrogen on these observed peaks in dark conductivity.
Magnetodielectrical polymer compositional materials containing carbonyl iron (CI) were obtained. The changes of permittivity and permeability, loss angle tangent, resistivity, mechanical and ...electrical properties, depending on the content of carbonyl iron have been investigated. It is shown that the magnetodielectrical materials with 20-40% mass content of carbonyl iron have possible practical use.
A deeper understanding of low-dimensional and small-scale electronic systems requires an accurate characterization of the many-electron effects. Based on the electron liquid (EL) model, these ...many-body effects in the three-dimensional (3D) and two-dimensional (2D) electronic systems are dealt going beyond the random phase approximation within the zero-temperature framework. The dielectric formulation of the many-body problem is recapitulated and the longitudinal dielectric function of the EL is obtained using the self-consistent local-field correction scheme, known as STLS, under a general spin-valley degeneracy. Extensive explicit expressions are provided for the use of other researchers. The performance of this formalism is compared in both 3D and 2D by the quantum Monte Carlo data and the pseudopotential approach introduced by Pines and co-workers. STLS is observed to be a highly satisfactory technique, with some reservations on the long-wavelength behaviour. Ground-state energy, correlation energy and the isothermal compressibility of the 2D EL are computed using a variety of approaches. Negative compressibility and overscreening are discussed in the light of the recent experiments.
We analyze the strains near threshold in 1-d charge density wave models at zero temperature and strong pinning. We show that in these models local strains diverge near the depinning threshold and ...characterize the scaling behavior of the phenomenon. This helps quantify when the underlying elastic description breaks down and plastic effects have to be included.
Dielektrik bir malzeme olan odunun dielektrik özellikleri, odunun elektrik alanı ile etkileşimi sonucu, malzeme içinde meydana gelen kutuplaşma aracılığıyla elektriksel potansiyel enerjinin ...depolanması ve ayrıca elektrik alanı kaldırıldığında bu enerjinin bir kısmının yayılımı veya kaybı olarak ifade edilir. Odunun dielektrik özellikleri, odunun lif yönü, rutubet miktarı, yoğunluğu, alan frekansı ve sıcaklıktan etkilenmektedir. Bu çalışmada, tam kuru ve rutubetli odunun dielektrik özellikleri üzerine bu faktörlerin etkisi hakkında bilgiler verilmektedir.
The dielectric properties of nonconductor wood material is described the interaction between the materials and the electric fields. These two interactions are the absorption and storage of electric potential energy in the form of polarization within the dielectric material, and the dissipation or loss portion of this energy when the electric field is removed. The dielectric properties of wood are affected by grain direction, moisture content, density, frequency and temperature. The effect of these factors on the dielectric properties of oven dry and moist wood are reviewed in this article.
The stepwise stability constants of $UO_2^+$, $Th^{4+}$, $Pr^{3+}$ and $Yb^{3+}$ ions with 3(acetophenonehydrazone)-6-phenyl pyridazine (AHP), 3-(p-chloroacetopheon-hydrazone)-6-phenyl pyridazine ...(C1AHP) and 3-p-aminoacetophenonehydrazone)-6-phenyl pyridazine (NH2AHP) have been investigated potentiometrically in 75% (v/v) dioxane-water and 0.1 MKNO3 at different temperatures (298,308 and 318K). For the same ligand, the order of stability decreases in the sequence; $Th^{4+}$ > $UO_2^{2+}$ > $Yb^{3+}$ >$Pr^{3+}$. The thermodynamic functions ($\Delta G$, $\Delta H$ and $\Delta S$) for the dissociation and the complexation reactions have been evaluated and discussed. The higher negative values of $\Delta H$ suggest an octahedral environment around the metal ions in solution. Also, the effect of the dielectric constant of the solvents, mole fraction and ionic strength of the medium on the stability of $UO_2^{2+}$-complexes were discussed.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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