The Toktogul hydrodevelopment is being constructed in a zone of high seismic activity, in designing the dam an earthquake with an intensity of 9 with verification for i0 was adopted as the design seismic load [i, 2].In consideration of the extremely high intensity of the seismic load, the uniqueness of the structure, and the increased requirements imposed on the reliability of the hydrodevelopment, a cycle of experimental and theoretical investigations for substantiation of the seismic stability of the dam was carried out in the research department of the All-Union Planning, Surveying, and Scientific-Research Institute (Gidroproekt).* Numerical investigations of the stresses and strains in the dam were conducted on orders of the research department of Gidroproekt at the Institute of Hydromechanics, Academy of Sciences of the Ukrainian SSR, under the supervision of Doctor of Technical Sciences L. I. Dyatlovitskii; model investigations of the stress state of a dam sectioned by contraction joints were carried out on orders of the research department of Gidroproekt at the department of hydraulic structures of the Moscow Institute of Engineering Reclamation under the supervision of Doctor of Technical Sciences N. P. Rozanov. EVALUATION OF SEISMIC LOADSComputations of the seismic loads for large hydraulic structures are based on the selection or construction of a representative seismogram characterizing the displacement or other kinematic characteristic (velocity, acceleration) of the motion of an arbitrary horizontal surface of the earth at the structure site.The analog accelerogram a(t) of the Yurek earthquake (Fig. i), selected and transformed on the basis of seismogeological and geophysical characteristics in conformity with the method developed at Gidroproekt, was used as the initial seismologic information in investigations to evaluate the seismic stability of specific design variants of the Toktogul dam. This seismogram is referred to an arbitrary horizontal surface.The effect of the relief and presence of the hydrodevelopment structure and reservoir was studied on a three-dimensional elastic model with a linear scale of 1:4000, which reproduced the main geophysical characteristics of the region, encompassing a zone with an area 6 x 6 km to a depth of 4 km from the surface.The method of such investigations is known [3,4], but practical testing of a three-dimensional model of such scale was apparently performed here for the first time.The investigations were carried out for the following states of the canyon: without the dam, with the dam, and with water in the reservoir.Three-component piezoelectric receivers measuring 3 x 2 x 3 mm recorded the vibrations of the model at a height to 2H (H is the height of the dam) from the bottom of the river.The seismic load was assigned successively in the following directions:vertically from below under the dam; horizontally from the right flank; at an angle of 45 ~ to the horizontal from the reservoir.The following premises were used on converting the accelerograms from mode...

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The paper considers determination of attitude parameters, including true heading, by an inte grated orientation and navigation system (IONS) comprising MEMS based inertial measurement unit (IMU) and multiantenna GNSS receiving equipment. IONS generates orientation solution using phase data from two antenna GNSS module with antenna base about the wavelength of the satellite signal at carrier fre quency. The system algorithms and errors are studied. IMU and GNSS antenna base are subjected to modu lating rotation. Effectiveness of using GNSS phase determinations for estimating heading errors with a short rotating antenna base is investigated. The system experimental sample uses IMU based on STIM300 Senso nor MEMS sensors (Norway), navigation and phase measurements by GNSS receivers 1K 181 by Russian Institute of Radionavigation and Time (Russia). The results obtained in bench tests are presented.

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