MULTIPATH ANTENNA SYSTEM OF THE VHF BAND BASED ON A LENS MADE OF GRANITE RUBBLE

Предложена конструкция приземной многолучевой антенной решетки на основе линзы из гранитного щебня, позволяющая одновременно формировать до нескольких десятков лучей в длинноволновой области УКВ-диапазона волн. Эффективная диэлектрическая проницаемость гранитного щебня оценивалась с помощью формулы Лихтенекера для мелкодисперсных смесей; ее величина приблизительно равна 3. Для оценки величины замедления поверхностных волн в линзе использовалась методика анализа дисперсионных характеристик зеркального диэлектрического волновода; при высоте линзы 1.8 метра эффективная диэлектрическая проницаемость эквивалентного зеркального диэлектрического волновода равна 2.1. В качестве облучателей линзы - несимметричные электрические вибраторы, расположенные на окружности по периметру линзы, диаметр которой составляет 30 метров; диаметр подстилающей стальной поверхности составляет 40 метров. Предложенная антенная система характеризуется потерями в щебне около 3 дБ при диаметре линзы около 3,8 длин волн; показано, что коэффициент направленного действия у каждого луча может составлять около 15,5 дБ, при ширине главного лепестка в азимутальной плоскости по уровню половинной мощности около 10 градусов We propose a design of a surface multi-beam antenna array based on a lens of crushed granite, which makes it possible to simultaneously form up to several tens of beams in the long-wave region of the VHF wave range. We estimated the effective dielectric constant of crushed granite using the Lichtenecker formula for fine mixtures; its value is approximately equal to 3. To estimate the magnitude of the deceleration of surface waves in the lens, we used a technique to analyze the dispersion characteristics of a mirror dielectric waveguide; at a lens height of 1.8 meters, the effective dielectric constant of the equivalent mirror dielectric waveguide is 2.1. As irradiators of the lens - asymmetric electric vibrators located on a circle around the perimeter of the lens, the diameter of which is 30 meters; the diameter of the underlying steel surface is 40 meters. The proposed antenna system is characterized by a loss in rubble of about 3 dB with a lens diameter of about 3.8 wavelengths; the directivity of each beam can be about 15.5 dB, with the width of the main lobe in the azimuthal plane at half power level of about 10 degrees

Size effect at testing strength properties of concrete

Various strength characteristics of concrete are considered as fracture parameters. The compressive strength of concrete is of paramount importance when designing concrete structures, whereas tensile strength of concrete is the basic property when estimating cracking resistance of a structure and analysing fracture processes in concrete. When testing the compressive strength of concrete, the results are dependent on the shape and dimensions of used specimens. Some findings reported in the literature suggest that size effect exists also when testing such fracture properties of concrete as tensile strength. Unfortunately this problem is much less recognized and described compared to size effect in compressive test results. In this paper, the experimental investigation is presented on how the length of cylindrical specimens influences the tensile splitting strength of concrete obtained by means of the Brazilian method. Additional variable parameters were: type of aggregate (natural gravel and crushed granite) and cement-water ratio (C/W = 1.8 and C/W = 2.6). In conducted laboratory experiments a higher splitting tensile strength of concrete was noted for all specimens with nominal dimensions of 150×150 mm, compared to specimens 150×300 mm in size, regardless of type of aggregate or cement-water ratio.

An Application of Safety Assessment for Radioactive Waste Repository: Non-Equilibrium Transport of Tritium, Selenium, and Cesium in Crushed Granite with Different Path Lengths

Advection-dispersion experiments (ADE) were effectively designed for inadequate transport models through a calibration/validation process. HTO, selenium (Se), and cesium (Cs) transport in crushed granite were studied using a highly reliable, dynamic column device in order to obtain the retardation factors (R) and the dispersion coefficients (D) by fitting experimental breakthrough curves (BTCs) for various path lengths. In order to conduct a safety assessment (SA) of a deep geological repository for high-level radioactive waste, radionuclide transport in rock systems is necessary to clarify and establish a suitable model. A dynamic column with a radiotracer (HTO, Se(IV), and Cs) was applied to 2, 4, and 8 cm path lengths using a STANMOD simulation. The results showed similar results between the BTCs of Se and Cs by fitting a non-equilibrium sorption model due to the retardation effect. In fact, there was a relatively obvious sorption of Se and Cs in the BTCs obtained by fitting a retardation factor (R) value higher than 1. In addition, a two-region (physical) and a two-site (chemical) non-equilibrium model with either the lowest sum of squared residuals (SSQ) or the root mean square error (RMSE) were applied to determine the Se and Cs sorption mechanisms on granite.

Studying the Effect of some Factors on the Stress-Strain Behavior of the Rostov Region Limestones in the Course of their Production and Use

The paper considers the current state of the mineral raw material base and the construction material market of the Rostov Region. The effect of various factors on the strain-stress behavior of local limestones has been investigated. The scientific and technical literary sources devoted to the processes of rock failure under various loads have been analyzed. The experimental studies have shown that the tested samples of limestone with a high content of cuboidal grains have characteristics comparable to those of the crushed granite stone. It has been concluded that the use of the Rostov Region limestones in the construction industry is competitive and feasible, provided the proper implementation of the engineering measures proposed in their production.

Оценка уровня воздействия техногенных факторов при добыче и производстве гранитного щебня

Using the example of Open Joint Stock Company «Pavlovskgranit», located in the Voronezh region, the level of impact of technogenic factors (air pollution and noise) during the extraction and production of crushed granite was estimated. It was established that 61 pollutants enter the atmospheric air from 134 sources of pollution. The main contribution to the total volume of emissions (1881.0 tons/year) is made by inorganic dust with a SiO2 content of 70-20% - 73.4%, sulfur dioxide - 9.8%, carbon monoxide - 114.3 tons/year. Blasting operations in open pits during the extraction of crushed granite are the leading production process that makes a significant contribution to the volume of emissions. At the same time, the remoteness of industrial sites from the territory of residential development, the presence of a sanitary protection zone, allows us to speak about the admissibility of the impact of concentrations of pollutants in the air and the noise factor at the border of the territory of the nearest residential development.

Mining production as a factor of transformation of soils and soil cover

The article describes the component composition of the soil cover in the areas of mining granite material near Kuznechnoe, Leningrad region. Nonsoils formations take about 50 per cent of the study area. There are natural and varying degrees disturbed soils in this area around excavations of the quarry. Soils with Novic qualifiers are formed along the access roads to the quarry. There are stratified natural soils are diagnosed around the quarry in the direction of the rose diagram. Lithic Leptosol are formed at the crushed granite storage site. The degree of transformation of the component composition of the soil cover depends on anthropogenic activity in the territory adjacent to granite quarry has been defined. The article outlines the characteristics of the altered structure of the soil cover.

The use of screening of crushed granite stone for the production of building materials

The possibility of using technogenic raw materials – the screening of crushed stone with the addition of cullet based on a silicate binder for the production of construction materials for structural purposes is studied. By varying the processing temperature, it was possible to increase the softening coefficient of the products and to achieve the pH neutrality of their pore liquid. Products processed at a temperature of 500700 °C have the following performance characteristics: the compressive strength 16.6-31.4 MPa, the bendingstrength 3.4-5.9 MPa.

Development of Functionally Graded Concrete Using Rubber Fiber

The current study investigates the functionally graded concrete (FGC) prepared using waste rubber tyre fibers as replacement of fine aggregates (FA) at a constant w/c ratio of 0.45. FGC is a continuously graded concrete which has different properties either in top or bottom portion according to the properties of materials added. Different materials like fly ash, steel fibers, glass granules, crushed granite aggregates, etc., has been utilized by different researchers to prepare FGC. The percentage replacement of rubber fibers used was 0-20% at 5% intervals and 30% to prepare control concrete (CC), rubber fiber concrete (RFC) and rubberized functionally graded concrete (RFGC). The fresh and hardened properties were performed on the concrete samples for the detailed analysis. Workability, density, compressive strength, flexural strength and water permeability tests were conducted on the different types of concrete. Flexural strength was better observed for RFC and RFGC as compared to CC. Compressive strength and depth of penetration values decreased with the addition of rubber fibers, however, RFGC had better values as compared to RFC. Study concluded that RFGC could be a sustainable approach towards the construction were flexural strength is mainly required.