Оценка чувствительности локомотивных приёмников при использовании испытательных шлейфов со скрещиваниями

Main technical and operational characteristics of the locomotive receiver of the automatic locomotive signalling system, which is part of all types of core locomotive safety devices, comprise its sensitivity. This characteristic makes it possible to estimate by indirect methods the signal/noise ratio at the input of the locomotive receiver, and, therefore, to evaluate the noise immunity of its operation at the nominal parameters of amperage and current frequency of signals of automatic locomotive signalling system in the track circuit under operating conditions.Thanks to correct adjustment of the sensitivity of the locomotive receiver, it is possible to significantly reduce the number of failures in operation of the main locomotive safety devices. Checking the sensitivity of the locomotive receiver and other parameters of safety devices is carried out at control points, usually equipped in depots, using stationary test loops that simulate the electromagnetic field generated by the signal current flowing in the track circuit. Sensitivity measurement results are influenced by various factors, primarily the position of the receiving coils along the test loop performed with crossings, as well as the distance between adjacent crossings. The influence of these factors may lead to the impossibility of checking the correct operation of locomotive safety devices at nominal signal parameters, as well as to an incorrect assessment of sensitivity.The objective of this work is to evaluate the influence of these factors on the results of measuring the sensitivity of a locomotive receiver. A model developed as part of the work and based on the well-known methods of analysis and synthesis and the Biot−Savart− Laplace law describes the inductive connection «test loop−coil». Several characteristic dependencies have been also obtained. The results have been compared with the existing requirements for the position of the coils relative to the test loop performed with crossings.To ensure the most accurate results of measurements of the sensitivity of the locomotive receiver, it is proposed to place the receiving coils of the locomotive safety devices at an equal distance from adjacent crossings of the test loop.Одной из основных технико-эксплуатационных характеристик локомотивного приёмника системы автоматической локомотивной сигнализации, входящего в состав всех типов основных локомотивных устройств безопасности, является его чувствительность. Данная характеристика позволяет оценить косвенными методами соотношение сигнал/ помеха на входе локомотивного приёмника, а, значит, и оценить помехоустойчивость его работы при номинальных параметрах сигналов автоматической локомотивной сигнализации в рельсовой линии в условиях эксплуатации – силе тока и частоте.За счёт правильной регулировки чувствительности локомотивного приёмника возможно существенно снизить число сбоев в работе основных локомотивных устройств безопасности. Проверка чувствительности локомотивного приёмника и других параметров устройств безопасности осуществляется на контрольных пунктах, оборудуемых, как правило, в депо при помощи стационарных испытательных шлейфов, имитирующих электромагнитное поле, формируемое сигнальным током, протекающим в рельсовой линии.На результаты измерения чувствительности оказывают влияние различные факторы, в первую очередь положение приёмных катушек вдоль испытательного шлейфа, выполненного со скрещиваниями, а также расстояние между соседними скрещиваниями. Влияние данных факторов может приводить к невозможности проверки правильности работы локомотивных устройств безопасности при номинальных параметрах сигналов, а также к неверной оценке чувствительности.Целью данной работы является оценка влияния указанных факторов на результаты измерения чувствительности локомотивного приёмника. В рамках работы, используя общеизвестные методы анализа и синтеза, была разработана модель, базирующаяся на законе Био−Савара−Лапласа и описывающая индуктивную связь «испытательный шлейф− катушка». Получен ряд характерных зависимостей. Результаты сопоставлены с существующими требованиями к положению катушек относительно испытательного шлейфа, выполненного со скрещиваниями.Для обеспечения наиболее точных результатов измерений чувствительности локомотивного приёмника предложено располагать приёмные катушки локомотивных устройств безопасности на равном удалении от соседних скрещиваний испытательного шлейфа

The improvement of thermal characteristics of autoclave aerated concrete for energy efficient high-rise buildings application

Nowadays, the problem of energy saving is very relevant. One of the ways to reduction energy consumption in construction materials production and construction of civil and industrial high-rise buildings is the application of claddings with heat-insulating performance. The concept of energy efficiency of high-rise buildings is closely related to environmental aspect and sustainability of applied construction materials; reducing service costs; energy saving and microclimate comfortability. A complexity of architectural and structural design as well as aesthetic characteristics of construction materials are also should be considered. The high interest focused on materials with combined properties. This work is oriented on the study of energy efficiency of buildings by improving heat-insulation and strength performance of autoclave aerated concrete. The applied method of sulfate activation of lime allows monitoring phase and structure formation in aerated concrete. The optimal mix design of aerated concrete with the compressive strength up to 8.5 MPa and decreased density up to 760 kg/m3 was proposed. Analysis of structure at macro-and microscale was performed as well as the criteria of an optimal porosity formation was considered a number, size, shape of pore and density of interior partition. SEM analysis and BET method were performed in this research work. The research results demonstrated the correlation between structure and vapor permeability resistance, also it was found that the increase of strength can lead to reduction of thermal conductivity

Green Buildings - sustainable development strategy

Green construction is one of the most promising directions for development not only in the construction complex, but also in the social environment. Green buildings, as human environment, are attractive for investors, designers, utility equipment manufacturers and housing owners. Requirements for green buildings are sufficiently high and cannot be met by the traditional design principles based mainly on typical solutions. As a result we need to arm designers, builders and operators with new creative knowledge. In essence certification of a facility as a green building initiates a creative search for architects and engineers of such technical solutions that minimize negative and optimize positive influence of energy, environmental and technological factors that define the building as human environment. In this work it is difficult to separate the creativity of architect and engineer: we have to consider their joint work during the entire design process and only such union can bring success in achievement of the set goal

ANALYSIS OF DEPENDENCE BETWEEN CAPITAL EXPENDUTURES OF CONSTRUCTION WORKS AND GAS DISTRIBUTION PIPELINE DIAMETER

Materials consumption rate is used by many authors as the criterion for the assessment of the economic efficiency of gas distribution networks in the course of their design. No doubt that control over the materials consumption rate is of particular importance. However, we believe that it represents one of several constituents of the overall cost of a gas network piping project. Labour expenditures and earth works that are, to some extent, dependent on the diameter of a pipeline, should also be taken into account. Presently, metal and polyethylene pipes of standard diameters are used in gas network development projects. Diameters of pipes of external gas distribution networks are rounded up to the closest standard diameter of pipes as a result of a hydraulic calculation. The cost of construction of a gas pipeline has multiple constituents that may be clustered into three principle groups: 1) earth works, 2) piping; 3) cost of materials. Calculation of the cost of construction of low and medium pressure pipelines to be made of steel and cross-linked polyethylene was performed to find out the cost of a pipeline. The calculations were made in the basic prices of the year 2000 adjusted to the figures of April 2011, given the standard piping conditions in a settlement within central Russia. The data were interpolated by means of a quadratic function. On the basis of the above data, a comparative analysis of capital expenditures in respect of steel and polyethylene piping may be performed. The research also contemplates the structure of expenses associated with the piping of gas distribution networks. Mathematical equations have been derived to perform sufficiently accurate calculations of costs of construction of various types and various lengths of gas pipelines

Technical Solution for Protection of Heat Pump Evaporators Against Freezing the Moisture Condensed

This article is dedicated to the study of the processes of formation and freezing of condensate in heat exchangers using ambientair heat and is prepared according to the results of experimental investigations. The aim of this work has been set to elaboratean energy-independent technical solution for protection of heat-exchange equipment against freezing the moisture condensed on the heat-exchange surfaces while using the low-potential heat of ambient air in heat pump systems. The investigations have shown that at the temperatures of ambient air close to 0°C when using the «traditional» way of defrostation, which means the reverse mode of operation of heat pump, an intensive formation of ice is observed at the bottom part of evaporator (if not provided with tray heater). This effect is provoked by downward flow of thawed water and it’s freezing in the lower part of the heat-exchanger due to the fact that the tray and housing of heat pump have a temperature below zero. Thereafter, while the defrostation mode has been periodically used, the ice coat would be going to continue its growth, and by time significant area of evaporator could appear to be covered with ice. The results of the investigations presented in the article could be applied both to air-source heat pumps and to ventilation air heat recuperators