Home – Home – Jornals – Avtometriya 2008 number 1

The problem of processing mass-spectrum data in dope testing is considered. It is shown that this problem concerned with dope testing is characterized by a high level of a priori uncertainty. It is proposed to use a contrast method for detecting mass-spectrum peaks. The main point of the method is as follows. At first, a sample of observations without a useful signal is taken (i.e., there is no bioassay in the mass-spectrometer work chamber, in this case, the mass-spectrum depends only on the features of the measuring channel and remains of dirt in the work chamber). Then the work sample in which the useful signal has to be detected is taken. Optimal detection algorithms based on statistical principles of invariance and unbiasedness are obtained. Results of statistical tests of the algorithm and a full-scale experiment are presented.

Results of frequency stability of Nd:YAG lasers locked to resonances of high-Q Fabry

An alternative design of a frequency spectrum synthesizer for an optical time standard with a lower-level spectral density of noise FM at the synthesizer outputs is considered. This is achieved by using a transistor generator with frequency stabilization by a dielectric resonator and subsequent division of reference frequency by diode and trigger dividers, and by realization of a phase lock loop.

An automatic system for measuring the quantum efficiency of multielement photodetectors applied in atomic emission spectral analysis is created. Results of measuring the quantum efficiency of BLPP-369 photodiode lines with different dopants and coating layers, and also lines of CCDs (Sony ILX-526A) are presented. It is shown that the quantum efficiency of photodiode lines between 180 and 360 nm is 0.3

Results of measuring the voltage-current characteristics (VCCs) of diodes for IR detectors with the cutoff wavelength l_c= 11 mm are presented. The diodes are based on variband Hg_0,78Cd_0,22Te layers grown by molecular beam epitaxy on semi-insulating GaAs substrates. It is found that diffusion current and generation current in the depletion layer of the p

A set of conversion functions of a cluster single-coil eddy-current sensor as the sensor inductance dependences on the blade tip coordinate displacement is described. A simplified model of electromagnetic interaction between the sensitive elements and the object simulator, that is, a rectangular plate, is developed. The model ensures calculating the set of conversion functions in an analytical form. Results of calculating the set of conversion functions, which were obtained for the given geometrical parameters of the measurement object, sensor, and current directions of its sensitive elements, are illustrated.

Properties of SISO adaptive stabilization systems with different types of reference model for prescribing dynamic and static characteristics are discussed. The influence of the model structure that forms the input action on the control signal is considered.

A one-step sequential procedure using a special rule of observation accumulation is proposed for estimating the linear parameters of a stable random coefficient autoregressive process. The upper bound for rms precision of a sequential estimate which decreases inversely to the value of the procedure parameter that determines the time of observations is obtained. Asymptotic behavior of the mean time of the procedure is studied. Results of numerical simulations are presented.

An iterative approach to solving the inverse kinematic problem with optimized choice of the initial approximation is proposed. The investigation is important for acoustic, optical, and seismic tomography in the conditions of geometric optics approximation.

Amounts of calculations intended for implementing various algorithms of cone-beam 3D tomography reconstruction are analyzed. A technically simple way of spiral scanning meeting the requirement of completeness condition is considered. Methods for reducing the amount of calculations by considering only the necessary part of projection data for object reconstruction at a specific point and by eliminating calculation of the beam index in the reciprocal projection are proposed. A method for modeling the cone-beam tomography process is illustrated using the proposed algorithm.

An approach to constructing specialized Internet portals is considered. These portals have to ensure access to knowledge and information resources of a certain field of knowledge. The information basis for such portals is formed by ontologies, which allow heterogeneous data and knowledge to be presented in a unified manner and ensure their relatedness. For simpler customization of the portal to a chosen field of knowledge, its ontology is divided into the base ontologies (ontologies of research activities and knowledge) independent of the knowledge domain of the portal and the domain-related ontology, which describes a certain field of knowledge. Based on the portal ontology, internal storages of data are constructed; management of information content, navigation and search in the information space of the portal are organized.

A method for digital stroboscopic holographic interferometry of focused images for measuring points of displacements of a metal plate vibrating at a resonant frequency is considered. Unlike classical holographic interferometry, in this method, the measurement process does not include the process of interferogram obtaining, recording, and interpretation.

The problem of creating exact 3D models of complex real objects for virtual reality applications is considered. One of the systems reconstructing 3D coordinates of a scene from its 2D image by means of structured illumination is presented. Problems related with system operation and leading to reconstruction errors are described. A new method is proposed for improving performance of the system due to considering optical distortions and using several images for reconstructing the same scene area.