Double-channel parametric transducers with linear conversion functions

The design methods and technology are considered of precision instrumental transducers for an extensive class of automatic devices and systems operating in conditions of strong external interference. The paper is based on a report presented at the Transducers-98 Conference. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 39–45, May, 1999.     

Ionospheric radio tomography based on the GPS/GLONASS navigation systems

The specific features of the problem of ionospheric radio tomography based on the data from high-orbital navigation systems such as GPS and GLONASS are considered. An approach to solving this problem, which implies finding the solution with the minimum Sobolev’s norm (i.e., the smoothest solution) is proposed. The possibilities of the proposed approach are studied by numerical modeling with the use of real geometry of high-orbital satellite constellation and the layout of the receivers. The modeling shows that the proposed approach is very efficient in the regions with a sufficiently dense network of receivers. The resolution of possible radio tomographic systems over the territory of Russia is estimated. Examples of radiotomographic reconstructions of the ionosphere obtained from real high-orbital satellite data for the European region are presented.     

Mathematical model of the temperature field of a rail and a multinozzle device for induction hardening of rail heads

A mathematical model of the temperature field of a rail is developed for designing optimum regimes for surface hardening of rail heads from induction heating by HFC, and the cooling capacity of media formed in a newly designed multinozzle device is considered. It is established that the process of cooling of rail heads can be controlled by providing a high dispersity of the water-air mixture formed by a multinozzle cooling device with autonomous feeding of the coolant through each nozzle. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 31–35, December, 1999.     

Computation of laminar viscous fluid flows in arbitrary axisymmeric channels

A finite-difference method is proposed for computing flows in axisymmetric channels of arbitrary configuration in the presence of a swirling stream.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 8, No. 1, pp. 42–49, January, 1990.     

Buckling analysis and design of anisogrid composite lattice conical shells

Composite lattice anisogrid shells have now become a popular choice in many aerospace applications. Their use in various structural components, such as rocket interstages, payload adapters for spacecraft launchers, fuselage components for aerial vehicles, and parts of the deployable space antennas requires the development of more advanced finite-element models and analysis techniques capable of predicting buckling behaviour of these structures under variety of loadings. A specialised finite-element model generation procedure (design modeller) is developed and applied to the buckling analysis of the composite anisogrid conical shells treated as three-dimensional frames composed of the curvilinear ribs made of unidirectional composite material. Featuring a dedicated control procedure for positioning the beam elements, the design modeller enables a close approximation of the original twisted geometry of the curvilinear ribs. The parametric finite-element buckling analyses of the anisogrid conical shells subjected to axial compression, transverse bending, pure bending, and torsion showed the robustness and potential of the modelling approach. It was demonstrated that the buckling resistance can be significantly enhanced by either increasing the stiffness of a few hoop ribs located in the close proximity to the section with the larger diameter, or by introducing the additional hoop ribs in the same part of the conical shell. The effectiveness of the design analyses is demonstrated using particular examples. It has been shown that the resultant optimised designs can produce up to 22% mass savings in comparison with the non-optimised lattice shells.     

Method for detection of ground objects and recognition of their types from radar images of the earth surface

A method for detection of ground objects and recognition of their types against the background of the earth surface from objects’ radar images (RIs) is proposed. The method is based on a priori formation of template RIs of the objects in free space and scanning the RI of the earth surface with two types of rectangular windows. The dimensions of the window of the first type take into account the shadows of the objects, and the dimensions of the windows of the second type take into account only the outer dimensions of the objects. The results of the simulation of the detection characteristics and of the parameters of recognition of a KAMAZ truck and the control station mounted on the same chassis, which were located on a standard earth surface, are presented.     

The Effect of Radiative-Convective Heat Transfer on the Formation of Current Layer

A two-dimensional computational model is suggested for the calculation of radiative-convective heat transfer in the channel of an MHD generator with a self-sustaining current layer (T-layer). The calculation results demonstrate that the characteristic features of the T-layer dynamics include the development of hydrodynamic instability of the Rayleigh-Taylor type and the flow of electrically nonconducting gas past the discharge region. These physical mechanisms lead to irregularity and nonstationarity of flow in the channel; in so doing, the discharge region changes its structure periodically and exists both as several current-conducting channels and as a unified plasma formation.__________Translated from Teplofizika Vysokikh Temperatur, Vol. 43, No. 3, 2005, pp. 401–407.Original Russian Text Copyright © 2005 by E. N. Vasil’ev, and D. A. Nesterov.     

A liquid pulsed microwave radiation calorimeter

A wideband calorimeter intended for measuring energies of the pulsed microwave radiation with duration of several nanoseconds to 1 s is described. The calorimeter’s principle of operation is based on measuring the volume increment that results from heating, when the radiation is absorbed by a polar liquid. The energy measurement range is 10 mJ–100 J, the energy-absorption coefficient is >0.9 in a frequency band of 1.6–20 GHz and ～0.99 at frequencies of 4–18 GHz. The measurement error of the absorbed energy in the range 0.2–50 J does not exceed ±4%.     

The role of splenectomy in treating severe aplastic anemia

A hypotensive effect of clonidine in non-narcotized intact and aorta baro-denervated rats is studied under conditions of minimization of stress actions (radiotelemetry) and under standard conditions of direct recording arterial pressure (AP). Direct AP recording is shown to determine an increase in background AP in baro-denervated rats, but not in control rats. An increase in background AP level under conditions of direct recording is not accompanied with decreasing hypotensive effect of clonidine in baro-denervated rats.