Application of dynamic vibration dampers for vibration protection of bridge structures

Introduction. The increase in traffic intensity and the prospects for the development of high-speed railway transport require solving the problem of the effectiveness of vibration protection of transport infrastructure facilities by developing innovative solutions. Currently, the issues of combating vibration in relation to the span structures of bridges and overpasses are insufficiently studied. The purpose of the work is to study the promising directions of vibration protection of bridge structures based on the use of dynamic vibration dampers.Research methodology. To achieve the goal of research and implementation of effective technical solutions in the field of vibration protection of bridge structuresimproved design of dynamic vibration damper is proposed in which inertial mass is fixed on two springs, upper of which is connected to structure protected from vibration, and lower spring to base or foundation of object. Oscillations are damped due to oscillations in antiphase due to free and forced oscillations of auxiliary inertial masses protected from vibrations. This technical solution makes it possible to balance forces of elastic interaction of damping device and object protected against vibration and moments from these forces.Results. As a result of experimental studies of the prototype of the improved dynamic vibration damper installed on the vibration stand, it was found that the vibration levels in all directions significantly decreased, including in the vertical direction by 5.7 times.Discussion and conclusion. The obtained positive results of experiments and the relative simplicity of the proposed design make it possible to propose this method of vibration protection of superstructures for both newly designed and already in operation facilities. It is especially important to minimize the possibility of resonant phenomena and pitching. The results of the study will make it possible in the future to ensure the effectiveness of vibration protection of oscillating machines, mechanisms and infrastructure facilities

TOMO-ETNA experiment at Etna volcano: Activities on land

In the present paper we describe the on-land field operations integrated in the TOMO-ETNA experiment carried out in June-November 2014 at Mt. Etna volcano and surrounding areas. This terrestrial campaign consists in the deployment of 90 short-period portable three-component seismic stations, 17 broadband seismometers and the coordination with 133 permanent seismic station belonging to Italy’s Istituto Nazionale di Geofisica e Vulcanologia (INGV). This temporary seismic network recorded active and passive seismic sources. Active seismic sources were generated by an array of air-guns mounted in the Spanish oceanographic vessel “Sarmiento de Gamboa” with a power capacity of up to 5200 cubic inches. In total more than 26,000 shots were fired and more than 450 local and regional earthquakes were recorded. We describe the whole technical procedure followed to guarantee the success of this complex seismic experiment. We started with the description of the location of the potential safety places to deploy the portable network and the products derived from this search (a large document including full characterization of the sites, owners and indication of how to arrive to them). A full technical description of the seismometers and seismic sources is presented. We show how the portable seismic network was deployed, maintained and recovered in different stages. The large international collaboration of this experiment is reflected in the participation of more than 75 researchers, technicians and students from different institutions and countries in the on-land activities. The main objectives of the experiment were achieved with great success.PublishedS04272SR. VULCANI - Servizi e ricerca per la SocietàJCR Journalope

Methodology for evaluating energy-saving technical solutions of impact machines and equipment

Abstract The paper proposes a method of sequential exclusion at the stage of designing feature elements in known and synthesized pneumatic impact mechanisms in order to select preferred constructive solution of machine mechanism for destruction of mountain ranges in preparing the bases for construction of buildings and structures. The method involves a phased analysis of several variants of mechanisms at the same time with exception of the same structural features, elements that have the same effect on the work process and resource mechanisms. Thus, only original compositions remain that characterize distinctive qualities of technical solution of the pneumatic impact mechanism variant corresponding to its intended purpose.</jats:p

Experimental studies of a valveless non spool-type pneumatic percussion mechanism of a hammer

Abstract Performing different kinds of activities, both in mining companies and in construction of industrial, housing and civil facilities requires specialized equipment provided with attached active operating elements, for example, pneumatic hammers. The analysis and selection of a schematic diagram of a pneumatic percussion mechanism are performed using known elements-features and structural additional expanding elements-features. This allowed a development of a new design of a valveless non spool-type pneumatic percussion mechanism of a hammer, for which analytical studies of its operating modes using a mathematical model were conducted. Experimental studies were carried out with an experimental sample of a pneumatic percussion mechanism to specify the reliability of parameters for the proposed mathematical model.</jats:p

50 YEARS OF RESEARCH IN CONTINUUM AT THE UTR-2 RADIO TELESCOPE

Purpose: The results of research in continuum decameter-wave radio emission of the Galaxy background, ionized hydrogen regions, supernova remnants, extragalactic discrete sources, extended galaxies, galactic clusters, extragalactic background are given. The aim of this work is reviewing the results achieved for over 50-years of the UTR-2 radiotelescope research of our Galaxy and its population, as well as extragalactic radio sources in the continuum radio emission spectrum at extremely low frequencies for the ground based observations. Design/methodology/approach: The review, analysis, collection of archival data in various publications related to the subjectof this work. Findings: The basic results of studying the ionized hydrogen regions, supernova remnants, Galaxy background emission and its large-scale structure are given, and the maps of these sources are obtained. The catalog of extragalactic discrete radio sources of the most Northern sky part and the cosmological conclusions based on its analysis are described; the estimate of the isotropic extragalactic background brightness temperature is obtained; for the first time, the observational results for the Andromeda galaxy and two galactic clusters Coma and A2255 are given briefly. Conclusions: All the results presented here emphasize the uniqueness and importance of research in the decameter wavelength range, and the large area, flexibility of structure, continuous improvement make the UTR-2 radio telescope an indispensable tool for solving the most important tasks of modern radio astronomy, despite its respectable age. For example, only in the range of 10 to 30 MHz the ionized part of the most common element in the universe, the hydrogen, becomes optically thick and begins to absorb the synchrotron emission on the line of sight, which allows rather easy separation of thermal and non-thermal components of radioemission. This property allows to determine the ionized hydrogen regions’ electron temperature and the electron concentration on the line of sight independently in studying the hydrogen emission regions. When studying the supernova remnants, we can determine the ionized matter location by their spectrum drops ‒ before, inside or behind the remnant. Based on the HB3 supernova remnant radio imagies, an assumption was made on the existence of an ionized hydrogen relic shell aroundit, being caused by the initial ultraviolet flash of a supernova. For the first time, the maps of the Northern sky large-scale structure in the declination range from ‒15° to +85° at extremely low frequencies 10, 12.6, 14.7, 16.7, 20 and 25 MHz for the ground-based observations are published, which, besides their own scientific value, may allow to correct the UTR-2 radio telescope imaging results. Using the full-resolution UTR-2 maps and the developed method of multifrequency T‒T diagrams, it was possible to separate the background radiation into galactic and extragalactic components and construct the spectrum of the latter. From the analysis of the most complete decameter wavelength range catalog of discrete sources, it follows that there is a gap in the redshift spatial distribution for all classes of extragalactic sources. The existence of an ionized hydrogen ring in the Andromeda Nebula disk has been suggested. It is shown that the main partof the galaxy clusters decameter-wave emission comes from haloes and relics. Key words: decameter range; discrete sources; supernovaremnants; catalog; continuum radio emission; HII regions; UTR-2; background emission</jats:p