Home – Home – Jornals – Advanced Search

A group of nonlinear perspectives for displaying three-dimensional visual scenes on elliptic surfaces and the interior of spheroids is considered. Scenes are transformed using a patented method for displaying objects with space compression and subsequent projection onto a sphere.

A new method is proposed to reduce image distortions caused by random noise and rectilinear uniform motion of the object or recording system. The of a restoration model is based on a statistical regularization method, and the obtained system of linear equations and inequalities is solved using a multistep support vector method. An advantage of this approach is that the iterative nature of the algorithm makes it possible to take into account the a priori information on the solution represented by the inequalities. The results of numerical experiments showing the efficiency of the algorithm are given.

This paper presents the results of modeling of several digital filtering algorithms of the ADC output codes for suppressing periodic and impulse noise signals and normal noise. The algorithms were tested in LabVIEW. It was shown that they provided real-time suppression of normal and impulse noise to a level from −57 to −63 dB.

The resonant properties of dielectric subsurface objects in the microwave range are considered. The paper gives formulas and experimental results for the properties of some small-size (∅ ≈ 200 mm) dielectric objects in sand with a moisture content of 6% at depths up to 8 cm at frequencies of 270-620 MHz and for metal springs which can be part of these objects at frequencies of 900-1200 MHz. It is shown that the objects can be identified by their amplitude-frequency characteristics in the microwave range.

This paper considers the problem of determining the true (nonsampling) variance of the Allan parameter-the main frequency instability characteristic of frequency generators, synthesizer, and standards in the time domain. The variables influencing the efficiency of estimating the parameter are determined and compared in magnitude. For frequency fluctuations with flicker noise power-law power spectral density, the parameter estimate accuracy is most significantly affected by the variance of the estimated average frequency-the quantity included in the Allan parameter and defining the quality of averaging over a finite time interval.

A method of nanostructuring of silicon-on-insulator (SOI) layers on the basis of gas etching in XeF₂ or SF₆:CFCl₃ is developed for the purpose of obtaining SOI nanowire structures. SOI nanowire transistors (SOI NWTs) with free channels, used as sensors in electron detectors, are fabricated and tested. The results of experiments show that the method used to fabricate nanowires requires no hightemperature operations for elimination of defects after nanostructuring of SOI layers. The sensitivity of SOI NWTs to test molecules of bovine serum albumin is 10⁻¹⁵ mole/liter, which is one of the best results for nanowire biosensors.

Chiral metamaterials of the terahertz range are formed by means of rolling of strained nanofilms. Structural elements of these metamaterials are metal-semiconductor microhelices. Resonant optical activity of new metamaterials in the terahertz range is demonstrated. Arrays of model wire helices are formed and tested in the microwave range.

Molecular beam epitaxial growth of HgCdTe solid solutions on silicon substrates of 76.2 mm diameter was studied. Conditions for producing HgCdTe/Si(310) heterostructures for the spectral range of 3-5 μm which are suitable for fabricating high-quality devices were determined. A 4× 288 photodetector was fabricated by hybrid assembly of an array photosensitive element with a multiplexer. Results on the sensitivity and stability of this photodetector to thermal cycling are given.

Current-voltage characteristics of IR photodiodes and distributions of charge carriers in n⁺-n⁻-p-structures based on vacancy p-doped Hg_1−xCd_xTe films with x = 0.22 are examined. Threedimensional numerical modeling of the distribution of charge carriers and current-voltage characteristics during photodiode annealing is performed. The calculations predict that large tunnel currents in diodes after implantation can result from an elevated (more than 10¹⁵ cm⁻³) concentration of donors in the n⁻-layer, which enhances tunneling by decreasing the thickness of the space charged region of the n-p-junction, and also from a small (less than 3 μm) depth of the p-n-junction.

The photomagnetic effect and photoconductivity in a magnetic field are studied at a liquid nitrogen temperature for the Voigt geometry on p-HgCdTe films with graded-gap boundary regions where the content of cadmium (x) is increased above its mole fraction in the central area of the structure with a uniform distribution of x. A case with dominating Shockley-Read recombination is considered. It is demonstrated on the basis of experimental data that the film structure in studying these effects can be replaced by the central area with an identical value of x, by introducing effective velocities of surface recombination and surface generation of excess charge carriers on the interfaces between the central area and the graded-gap regions.