Special operational features of a variometer for measuring small pressure change rates

Conclusions In principle, the time lag of a variometer designed to measure small pressure change rates can be made as small as one pleases. However, when the time lag of the variometer is decreased, so too is the pressure drop between the static and dynamical chambers. This means that highly sensitive membranes of large dimensions must be used, and, in the final analysis, that the sensitivity of the variometer as a whole is lessened. To obtain the necessary sensitivity of the instrument, it is necessary to increase the volume of the static chamber, and, at the same time, to keep the time lag unchanged, it is necessary to lessen the effective resistance of the capillary.Translated from Izmeritel'naya Tekhnika, No. 11, pp. 33–35, November, 1971.     

An improvement of face detection algorithm for color photos

The problem of automatic detection of regions of interest (ROI) on color photos is considered. The efficiency of Viola-Jones face detector implemented in Intel OpenCV library is analyzed. The image size dependence of the algorithm characteristics is studied. It is shown that there are 2 significant drawbacks of this face detection algorithm as applied to the task mentioned. Some modifications are made for elimination of these drawbacks. To reduce false positives it is proposed to modify the algorithm with color segmentation and human skin tones analysis. To reduce the processing time the algorithm of downsizing preprocessing is proposed.     

Foam-rubber sample volume measuring

For industrial quality control of foam-rubber material, it is required to measure volume of the sample. A new approach is proposed to measure sample volume by images of sample faces. Faces images are got via flatbed scanner. The faces images are processed and the sample is approximated by hexahedron. Then the sample volume is calculated analytically. Also we proposed an iterative approach based on splitting geometrical model of the sample into several smaller hexahedrons. The test results have shown that results of volume measurements obtained by proposed approach coincide well with ones obtained by the standard method. However, repeatability and reproducibility of measurements is better for proposed algorithm, and it is faster. The article is published in the original. Ilia V. Safonov. Received his MS degree in automatic and electronic engineering from Moscow Engineering Physics Institute/University (MEPhI), Russia in 1994 and his PhD degree in computer science from MEPhI in 1997. Since 1998 he is an associate professor of faculty of Cybernetics of MEPhI while conducting researches in image segmentation, features extraction and pattern recognition problems. Since 2004, Dr. Safonov has joint Image Enhancement Technology Group, Printing Technology Lab, Samsung Research Center, Moscow, Russia where he is engaged in photo, video and document image enhancement projects. Sergei Yu. Yakovlev. Received the MS degree in cybernetics from Moscow Engineering Physics Institute/University (MEPhI), Russia in 2005. He is presently working towards his PhD degree. His current research interests include image processing, pattern recognition and 3D shape reconstruction.     

Fitting controllers to data

The problem of optimally fitting controllers to data is formulated and solved. This formulation is applied to the case in which the class of controllers considered is the same as the one used in model reference adaptive control problem and in which we minimize the induced norm of the control error. The solution to this problem, besides illustrating an use of the saying “let the data speak” to its extremes, gives a robustness-oriented perspective on model reference adaptive control.     

Effect of WC on electrodeposition and corrosion behaviour of chromium coatings

To study the effect of WC particles on corrosion behaviour of chromium coating steel samples were plated in Cr(VI) baths with various concentrations of WC. XPS, EPM and XRD were used to study the chemical composition, morphology and texture of the coatings. The corrosion behaviour was studied at different exposure times in solution containing 0.01 mol L^–1 H₂SO₄ + 0.5 mol L^–1 Na₂SO₄ using cyclic voltammetry and impedance spectroscopy. Cyclic polarization measurements suggest that WC particles slow down the processes of passive film dissolution and penetration of aggressive ions to the substrate. Electrochemical impedance spectroscopy (EIS) was used to reveal the details of the corrosion process at the solution/electrode interface. The simulation of EIS data with a proposed equivalent circuit model made it possible to obtain quantitative valuation of the Y₀ (Q_c), Y₀ (Q_s) and R_pore parameters, reflecting corrosion behaviour of samples at the solution/electrode interface. Samples plated in a Cr(VI) bath with WC provided better resistance to corrosion than those plated in a bath without WC. Analysis of the data obtained suggests that WC particles enhance corrosion resistance due to the microstructural features of the coatings.     

Peculiarities of Silicon-Donor Ionization and Electron Scattering in Pseudomorphous AlGaAs/InGaAs/GaAs Quantum Wells with Heavy Unilateral Delta-Doping

The influence of the concentration of silicon donors on the electron-transport properties of pseudomorphous Al_0.25Ga_0.75As/In_0.2Ga_0.8As/GaAs quantum wells (QWs) in heterostructures with heavy unilateral δ-doping by Si atoms was studied in a broad temperature interval (2.1–300 K). High electron mobility (up to 35700 cm²/(V s)) at T = 4.2 K was observed at a 2D (sheet) electron density of 2 × 10¹² cm^–2 in the QW. A band mechanism limiting the ionization of donors at an increased level of doping is described. The nonmonotonic variation of electron mobility with increasing silicon concentration is explained. A growth in the mobility is related to increase in the Fermi momentum and screening, while the subsequent decay is caused by tunneling-induced degradation of the spacer layer with decreasing potential of the conduction band in the region of δ-Si layer. It is shown that the effect is not related to filling of the upper subband of dimensional quantization.     

Unfalsifying Pole Locations Using a Fading Memory Cost Function

Given a feedback control system with an unknown plant, the problem of choosing a stabilizing controller is considered. Working within the framework of unfalsified adaptive control, we consider a finite‐dimensional linear time invariant system as a special case of the standard adaptive configuration. A fading memory cost function is presented in which the influence of older data is reduced exponentially. With this cost function, the location of the poles can be detected with only input‐output data. Compared with existing results, the cost function can detect changes affecting stability sooner and be used in adaptive switching control to improve the performance of controller switching.     

Structure and properties of the surface of iron-carbon alloys melted by laser radiation

The aim of the work consists in analyzing the special features of structure formation in melted zones (MZ) in laser treatment of iron-carbon alloys with a eutectic. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 7–10, January, 1999.