A spectroscopic rotating polarizer-analyzer ellipsometer in which the polarizer and the analyzer rotate in opposite directions at the same speed and with a fixed retarder is proposed and investigated theoretically. The fixed phase retarder is introduced after the rotating polarizer to significantly reduce the percent error in the optical parameters.
Indices of selected financial markets from various parts of world, different sizes and levels of development are investigated. The local Hurst exponent is globally compared to log-prices. Periodic changes in correlation coefficient are quantified via discrete Fourier transform. Local Hurst exponents spectra are discussed for investigated markets.
This paper presents an analytical formulation of nonlocal elasticity theory for the buckling analysis of simply supported carbon nanotubes with rotational springs at both ends. The lateral displacement function is represented by a Fourier sine series expansion. Stoke's transformation is applied to construct the coefficient matrix of the corresponding systems of linear equations. This matrix gives more flexibility in boundary conditions. The accuracy of proposed method is validated for three well-known boundary conditions available in the literature. A very good agreement has been obtained. The present method permits to have more efficient stability matrix for calculating the buckling loads of carbon nanotubes with any desired boundary conditions.
The diffraction gratings, fabricated in our laboratory, were presented and analyzed by atomic force microscopy in earlier publications. In this paper we apply the Fourier-Pade approximation on our data previously analyzed by fast Fourier transform, proving advantages of using the Fourier-Pade approximation for spectral analysis of structural properties of some optical materials.
This paper considers the problem of finding the temperature field in two-layer metallic materials heated by a moving source of radiation. It describes developed by the authors numerical method for solving the problem of heating a two-layer plate by a moving axially symmetric surface heat source with regard to the function of distribution of the power density of the beam for which the program of computation in C^{++} was implemented. The calculation results were used for selecting the optimal parameters (speed and power density of the source) of modifying radiation of protective powder coatings on steel substrates.
In this paper a method based on the Fourier transform and Padé approximants is investigated for analysis of holographic photonic crystal structures fabricated in Laboratory for Photonics, Institute of Physics, Belgrade. Padé approximants are numerical tool that can be used to accelerate the convergence of a slowly converging sequence.
In this paper the problem of cycles existence in capital markets is addressed. A spectral analysis algorithm, which reduces signal-to-noise ratio, is proposed to derive cycle periodograms for the yield function of DJIA, WIG 20, and NIKKEI 225 indices. Peaks of the the periodograms provide premises to postulate the existence of some possible cycles. The 3.5 year periodicity in all 3 indices, which can be related to the Kitchin cycle is found to be the most distinctive one.
A relationship between daily prices of Polish WIG index and trading volumes is investigated. By introducing variables related to a number of last prices and volumes, a history of values in a certain period of time (which could be regarded as an investor memory) is taken into account. Different characteristics of autocorrelations for prices and trading volumes are observed. By studying mutual correlations between the variables, a local maximum at about 100 trading days is discovered. The Granger causality test is performed, indicating very strong influence of prices on volumes. This property can be considered as a sign of markets maturity.
Switching magnetization magnetic force microscopy (SM-MFM) is based on two-pass magnetic force microscopy with opposite orientation of tip magnetization between two scans. The sum of the scanned data with reversed tip magnetization depicts local van der Waals forces, and their difference maps the local magnetic forces. Tip magnetization can be easily reversed in external magnetic field during the scanning. The separation of the forces mapped enables scanning in close proximity of the sample (~5 nm). Therefore, extremely high spatial resolution (10 nm) is achievable by the SM-MFM. Image phase resolution of the MFM method depends on various geometric parameters of the tip, such as tip length, its apex radius and taper angle. The parameters are determined by the evaporation process, within which the standard atomic force microscopy tips are coated with magnetic layer. In this work we show that the thickness of the coated layer is important for the SM-MFM spatial resolution.
Theoretical investigation of acoustic field in a tellurium two-coordinate deflector was carried out. We used angular spectrum method supported by consideration to boundary conditions in approximation of a given displacement to calculate spatial distribution of the acoustic field intensity. Volumetric illustration is presented for the acoustic beam launched from YZ face of the crystal. Cross-sections of the acoustic field generated from XZ face are also presented in the work. It is shown that the strong anisotropy of acoustic properties in the Te crystal leads to principally different structure of the two fields excited from the XZ and YZ crystal faces. The acoustic field excited from the XZ face may be considered as a simple beam with a relatively high divergence. On the other hand, the field generated from the YZ face looks like superposition of two beams with relatively low divergence. Ratio of intensities of the two beams generated by longitudinal piezotransducers is equal to the ratio predicted by analysis based by plane-wave theory.
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