3-mm wavelength range radar altitude sensors

In this study, we analyse the specific features of design of 3-mm wavelength range radar altitude sensors based on domestic-made super high frequency modules М55323 and М55328. Some results of full-scale tests are given.

THE INFLUENCE OF HYDROPHOBIC COATING ON THE EFFICIENCY OF FIRE PROTECTION OF TEXTILE MATERIALS

The analysis of fire-retardant materials for fabrics is carried out and it is established that the paucity of data for explanation and description of the process of fire protection, neglect of elastic coatings, leads to ignition of fabric structures under the action of flame. The development of reliable methods for studying the conditions of fire protection of fabrics leads to the creation of new types of fire protective materials. Therefore, it becomes necessary to determine the conditions for the formation of a barrier both for high temperatures and for leaching in the presence of precipitation and to establish a mechanism for inhibition of these processes. In this regard, full-scale tests were carried out and it was found out that when the flame is applied to untreated model samples of tent elements made of canvas fabric, the surface ignites and spreads the flame, which leads to their complete combustion within 105...120 s, instead, the model The fire-resistant sample of tent elements did not catch fire when ignited with a gasoline-based substance, and the flame did not spread. In this case, the final combustion was recorded for 3 c and the swelling of the protective coating reached 3...5 mm, and the surface was charred on an area of about 80% from the inside. When tested for fire retardant efficiency for a fire-resistant sample treated with a water repellent (5 % solution of GDJ-94), a decrease in efficiency and carbonization of the material was recorded, which amounted to 100%, and for a fire-resistant sample treated with a water repellent (5 % solution), a decrease in efficiency was recorded due to the combustion of paraffin and local burnout of the material, and carbonization was 100 %. Obviously, such a mechanism of influence of the fire-retardant coating is the factor regulating the process, which preserves the integrity of the object. Thus, there is reason to argue about the possibility of targeted regulation of the processes of fire protection of the fabric by applying coatings capable of forming a protective layer on the surface of the material, which inhibits the rate of heat penetration.

THE INFLUENCE OF ENCLOSURE ON BURNING CHARACTERISTICS OF OSB FURNISHINGS

This paper presents a series of full-scale tests conducted with office furniture made from OSB boards. Ignition source (30 kW gas burner) position and enclosure effects, free burn vs. ISO 9705 room, were evaluated from the perspective of instantaneous (HRR) and total heat (THR) released by the fuel packages. It was found that both of the evaluated factors have impact primarily on HRR – the peak ranging from 874 kW to 1 154 kW was delayed by approx. 50 to 60 s in the free-burn experiments; the THR remained relatively consistent at approx. 875 ± 30 MJ, meaning that in the observed period very similar amounts of fuel were burned. The thermal feedback within the enclosure seemed to be partially counteracted by the lack of oxygen, resulting in slightly higher HRR in free-burn test following the first peak. The findings of the research are applicable to fire hazard prediction by fire modelling.

PARAMETRIC ESTIMATION OF THE DIRECTIONAL WAVE SPECTRUM FROM SHIP MOTIONS

A parametric estimation of the directional wave spectrum based on ship motions is presented. The estimation of the sea- state parameters is essential to have an updated data base of the main characteristics of the sea-state, which are useful for several applications on open-sea such as offshore platforms installations and safe ship navigation. The sea-state parameters at a fixed position can be obtained using a traditional waverider buoy. The analogy between the ship and the buoy is clear thus, it is possible to obtain an estimate of the wave spectrum at the location of an advancing ship by processing its wave-induced responses similarly to the traditional waverider buoy. In the parametric procedure the estimated wave spectrum is a-priori assumed to be composed of one parameterized spectrum or by the summation of several parameterized spectra, e.g. the generalized JONSWAP spectrum. Genetic algorithms are applied to found the best estimation of wave parameters. The wave estimation method is validated against numerical simulations and full scale tests in a patrol ship.

Simulation model for assessing the safety of water transport

Показано, что выявление объективных причин аварий водного транспорта и последующее их устранение способствует радикальному повышению уровня безопасности. Сформирована причинно-следственная схема возникновения аварий водного транспорта в зависимости от главных, непосредственных, объективных и сопутствующих причин. Установлено, что при обосновании рациональных способов априорной количественной оценки степени опасности проектируемого оборудования необходимо исходить из неприемлемости проведения специальных натурных испытаний, инициирующих аварии. С этой целью рекомендуется имитационное моделирование. Предложена имитационная модель оценки вероятности возникновения аварий в процессе эксплуатации энергетической судовой установки. Функционирование имитационной модели основано на том, что возникновение происшествий является следствием развития причинно- следственной связи предпосылок, триггерами и составными частями которой являются ошибочные действия или бездействие членов команды судна, неполадки и отказы технологического оборудования, а также неучтенное воздействие внешних факторов. Систематизированы факторы, способствующие возникновению аварий и инцидентов, в составе которых: технические факторы; личностные и факторы воздействия внешней среды В общем виде решение задачи обеспечения безопасности судна с использованием предложенной модели сводится к отысканию функциональной зависимости вероятности возникновения аварии и оценкой факторов опасности, которая уже на стадии проектирования судового оборудования позволяет количественно оценить вероятность возникновения аварий в процессе эксплуатации водного транспорта. Приведен пример количественной оценки вероятности возникновения аварии. Предложено в состав обязательных документов, обеспечивающих проектирование водных транспортных средств, включать «Программу обеспечения безопасности», которая должна определять перечень работ и мероприятий, проводимых на всех стадиях жизненного цикла судна. It is shown that the identification of objective causes of accidents of water transport and their subsequent elimination contributes to a radical increase in its safety level. A causal scheme of the occurrence of accidents of water transport has been formed, depending on the main, direct, objective and concomitant causes. It is established that when justifying rational methods of a priori quantitative assessment of the degree of danger of the designed equipment, it is necessary to proceed from the unacceptability of conducting special full-scale tests that initiate accidents. For this purpose, simulation modeling is recommended. A simulation model for estimating the probability of accidents during the operation of a ship's power plant is proposed. The functioning of the simulation model is based on the fact that the occurrence of accidents is a consequence of the development of a causal relationship of prerequisites, the triggers and components of which are erroneous actions or inaction of the ship's crew members, malfunctions and failures of technological equipment, as well as the unaccounted impact of external factors. The factors contributing to the occurrence of accidents and incidents are systematized, including: technical factors; personal and environmental factors In general, the solution of the problem of ensuring the safety of a vessel using the proposed model is reduced to finding the functional dependence of the probability of an accident and assessing the hazard factors, which already at the design stage of ship equipment allows us to quantify the probability of accidents during the operation of water transport. An example of a quantitative assessment of the probability of an accident is given. It is proposed that the "Safety Program" should be included in the mandatory documents that ensure the design of water vehicles, which should determine the list of works and activities carried out at all stages of the vessel's life cycle.

Results of experimental tests of building samples

The purpose of the experimental study presented in the work is to generate new knowledge about the quality of concrete samples in a new information field that consolidates information about the results of full-scale tests and video streams that were obtained during active laboratory experiments-studies. When conducting experimental studies, the traditional technology of testing concrete samples for central compression was used. This was accompanied by continuous monitoring and the formation of a video stream for each sample. A distinctive feature of the study is the formation of an information field of experiments, which contains three levels: the level of initial data, the level of analysis of initial data and the level of generation of new knowledge. The level of analysis of the source data using the video stream allows you to obtain information at the end of the experiment that cannot be recorded in real time. For the samples under study, time intervals with different rates of defect development were obtained. The results obtained made it possible to identify new possibilities for the formation of the information field during traditional experimental studies of the quality of concrete images and, based on the information obtained, to identify patterns of development of surface continuity disorders in dynamics. New opportunities for the formation of the information field allow in real time to obtain and process information on the state of concrete and reinforced concrete structures of construction projects by quality indicators and, on the basis of the data obtained, predicting the risk of accidents, including at hazardous production facilities.

Elastic characteristics of the underrail base of a ballastless railway track

Objective: Experimental determination track modulus and the coeffi cient of relative stiffness of underrail base and the rail, which are the main elastic characteristics that determine the stresses in the structural elements of track superstructure under the impact force from the train. The values of these parameters for a track with a ballast layer are well studied, in contrast to a ballastless track. Comparison of the elastic characteristics of a ballastless railway track with analogs of a track on ballast, as well as an assessment of their effect on the stress-strain state of the superstructure elements of a ballastless track. Methods: When carrying out full-scale tests, strain-gauge methods for measuring stresses in the elements of the track superstructure were used. The obtained values were processed by the methods of mathematical statistics. One statistical series included the values of stresses corresponding to one type of rolling stock, fi xed axle load and train speed, changing by no more than 10 km/h. The probability level in processing the results was taken in all cases equal to 0,994. Results: The values of track modulus and the coeffi cient of the relative stiffness of the underrail base and the rail were obtained for a ballastless structure of the RHEDA 2000 type. Practical importance: The results allow us to consider the rail as a beam lying on a solid elastic foundation in relation to the ballastless track and use the existing calculation methods for the design of ballastless track structures depending on the operating conditions.

Analytical Limit Load Procedure for The Axial Complex Shaped Defect in a Pressurized Pipe

The paper is devoted to elaboration of the analytical O-procedure for limit load analysis of complex shaped axial defect in a pressurized pipe. It is based on the classical lower bound theorem of the theory of plasticity, and consists in construction of the statically admissible solution, where distribution of stress satisfies to the equilibrium equations and strength conditions. O-procedure is an optimization process to get the most favorable stress distribution for providing the maximal pressure. It allows to explicitly account for the variable geometrical and physical parameters. Contrary to other approaches, the derived formula for rectangular defect is only a particular case of the general procedure application. Four different methods for the complex defects are compared. They are: first, ASME, A-, rectangular defect formula combined with RSTRENG, R-, procedure, i.e., A-R approach; second, PCORRC, P-, formula with R-procedure, P-R approach; third, Orynyak's, O-, formula with R-procedure, O-R approach; and fourth, our universal O-procedure. The verification begins for rectangular defects where both theoretical and experimental comparison is performed for A-, P-, and O- formulas. The difference between them is small, provided that all three employ the same characteristic of material, here the ultimate strength. Then theoretical comparison for A-R, P-R, O-R approaches and O-procedure is performed for the artificial complex defects, for two symmetrical rectangular defects, for triangular defect. Experimental comparison between four methods is made based on the well-known University of Waterloo full scale tests.