Destruction Of Structural Elements Research Articles

ANALYSIS OF FACTORS AFFECTING THE SPREAD OF FIRE BY THE STRUCTURE OF FACADE THERMAL INSULATION WITH VENTILATED AIR LAYER

Aim. The purpose of this work is to analyse the factors influencing the development and spread of fire on the surface of external walls with facade insulation with a ventilated air layer. As well as analysis of causes and consequences of fires on the examples of resonant fires to develop and implement optimal engineering solutions to prevent the ignition and spread of fire on the surface of such structures.Research methods. The system approach and several general scientific research methods are used in the work. The analytical research method was used to analyse domestic and foreign regulations, guidelines and technical documents, manuals, reference books, test reports and other literature sources, Internet information.Results. At present, hinged ventilated facades are widely used for insulation during the reconstruction and construction of new buildings not only in our country but also abroad. At qualitative calculation, selection of materials and installation of such systems of warming, problems with its operation do not arise. However, still, the main problem of such structures is to ensure their fire safety. The article considers the causes and consequences of burning ventilated facades on the examples of resonant fires of previous years, as well as analyses the risks that arise during a fire in such systems. The factors influencing the destruction of structural elements and the spread of fire on the surface of the facade systems of the building are identified.To increase the fire safety of buildings equipped with ventilated facade systems, it is necessary to develop additional fire safety measures, which should include a study of the conditions of flame spread on the facade structures and the fire hazard of their elements; improvement of test methods for facade systems; development of methods to reduce fire hazard and increase the fire resistance of both systems in general and their elements in conjunction with the whole set of fire prevention measures of the building. The paper proposes optimal engineering measures that prevent ignition and spread of flame on the surface of the hinged ventilated facade system and provide the necessary limit of fire resistance of such structures.

ПОБУДОВА І АНАЛІЗ КОМП'ЮТЕРНИХ МОДЕЛЕЙ РЕЗОНАТОРІВ ЄМНОСТЕЙ ТЕХНОЛОГІЧНИХ АПАРАТІВ ВІЗУАЛЬНИМИ ЗАСОБАМИ PYTHON

Annotation. The study of nonlinear oscillations and processes in apparatuses that occur under the influence of complex oscillations presents significant mathematical difficulties. The arising strong nonlinear oscillations can significantly intensify technological processes or cause the destruction of structural elements. Therefore, the problem of using the vibrational energy arising in technological devices naturally matured for a long time both for equipment designers and production technologists. A computer model based on a differential equation for determining the frequencies and forms of bending vibrations of a tubular resonator is proposed. The use of the model makes it possible to visualize the modes and frequency of oscillations for a resonator in the form of a cylindrical part of a technological apparatus of any size. This takes into account the thickness of the walls, the outer and inner diameter of the vessel of the apparatus, and its length. The model takes into account the type of tank fastening with variation in the support stiffness. A distinctive feature of the resulting model is that for the first time an approach was used to solve the differential equation of capacity not by obtaining a numerical solution, but an approach was used that includes obtaining an analytical expression for each waveform with subsequent visualization using Python.

Analysis of the Torsional Stability of Split Phases

The specificity of overhead power lines is associated with the fact that the length of conductors between the supporting structures can reach tens of thousands of meters. Wires and their components are exposed to climatic factors, viz. wind, rain, ice, snow. As compared to other structural elements, conductors are of the highest flexibility and lowest rigidity, and, therefore, they are the most sensitive elements to these effects. Since the early fifties of the XX century, the increase in energy consumption has caused the construction of high and ultra-high voltage overhead lines with split phases. For these types of conductors, new forms of oscillations have been noticed in the areas between the struts, the essence of which is torqueing the split phase. As a result, there is a violation of the torsional stability of the phase: collision of wires in the middle of sub-span and friction of wires of stranded conductor against each other, which leads to damaging conductors and, as a consequence, to disruption of power supply to consumers. Almost any overhead lines may be subjected to oscillations of wires in the span under the influence of wind. One of the types of such mechanical oscillations is galloping, i. e. low-frequency oscillations of wires with an amplitude reaching the value of the boom of wire sagging, and, taking into account the possibility of elongation of the wire, even exceeding it. Fluctuations in the galloping can cause significant mechanical forces and last long enough to lead to the destruction of structural elements of power lines, viz. wires, insulators, fittings and even pillars. Due to the large amplitude of oscillations, conductors of neighboring phases can approach each other at an unacceptable distance, resulting in a short circuit. The boundary value problem of the torsional stability calculation of the split phase with a given multiplicity of splitting has been set and solved. The critical lengths of the sub-spans at which the stable violation of torsional stability is most likely have been determined. A computer program has been developed, which can be used in the design of high-voltage lines with split phase.

Influence of ultrasonic field during micro-arc oxidation on the structure and properties of calcium phosphate coatings

The study of the influence of applied external ultrasound (US) field with varied power of 35 or 100 W during the micro-arc oxidation (MAO) processing on the thickness growth, surface roughness, porosity, sizes of structural elements and structural-phase states of the calcium phosphate (CaP) coatings on the titanium surface was performed. It was shown that the US transmittance through the electrolyte for 10 min of MAO processing had led to the increase of the coating thickness from 50 to 60 µm, the surface roughness from 3 to 4.5 µm, and the cross-section porosity from 27 to 40%. However, under the action of external US there was a destruction of structural elements (spheres with pores) on the coating surface and a filling of pores’ spaces by fragments. That led to the decrease of the surface porosity from 30 to 12%. It was revealed by X-ray diffraction (XRD) that all types of the CaP coatings deposited under external US field and without it were in X-ray amorphous state. However, applied US field had led to the increase of the coating crystallinity with incorporation of CaHPO4 and β-Ca2P2O7 phases.

Cavitation in swirling flows of hydraulic spillways

During operation of high-head hydraulic spillway systems, cavitation phenomena often occur, leading to destruction of structural elements of their flow conductor portions. The article is devoted to the study of erosion due to cavitation in the circulation flows of eddy hydraulic spillways, including those equipped with counter-vortex flow energy dissipators. Cavitation destructive effects depend on many factors: intensity consisting in the rate of decrease in the volume or mass of a cavitating body per unit of time, the stage of cavitation, geometric configuration of the streamlined body, the content of air in water, the flow rate, the type of material. The objective of the study consisted in determination of cavitation impacts in circulating (swirling) water flows. The studies were conducted by a method of physical modeling using high-head research installations. Distribution of amplitudes of pulses of shock cavitation impact is obtained according to the frequency of their occurrence depending on the flow velocity, the swirl angle, the height of the cavitating drop wall and the stage of cavitation. The impact energy depending on the stage of cavitation and the flow rate is given for different operating modes of the counter-vortex flow energy dissipators of a hydraulic spillway. In the conclusions, it is noted that cavitation impacts in the circulation flows occur mainly inside the flow, which is a fundamental difference from similar processes in axial flows.

ОБ ОДНОМ МЕТОДЕ ПРИБЛИЖЕННОГО РЕШЕНИЯ НЕЛИНЕЙНОГО УРАВНЕНИЯ ТЕПЛОПРОВОДНОСТИ

In this paper a one-dimensional non-stationary heat conduction problem, modeling the process of rapid local heating of the sample beam type on the lateral surface is considered. The character of heating is such that it is possible to allocate only a certain directionof the heat propagation. Temperature fields are determined by an approximate method based on the idea of the thermal front. The solution is sought in the form of a power series in the coordinate with coefficients depending on time. The boundaries of the front heat distribution as a function of time are determined by the condition of the integral satisfaction of the heat conduction equation. Considered temperature fields arise in many industrial processes, such as laser material processing, when due to large temperature gradients can arise thermal stresses, leading to microcracking inner layers or the destruction of structural elements. Analytical view of the heat conduction problem’s solution allows to obtain analytical expressions for the thermal stresses and further facilitates the results analysis. The paper presents the solution of problems with boundary conditions of the first and second kinds for two monotonic and one non-monotonic dependencies of the thermal conductivity coefficient on temperature. The approximate solution and the exact solution of the nonstationary linear problem are compared and shows the suitability of the method for future use.

Nitric oxide modulation of the crystallogenic properties of a biological fluid

A comparative analysis of the influence of different nitric oxide forms on the character of the dehydration structuring of human serum samples was carried out. The effects of an NO-containing gas flow that was generated by a Plazon device (800 and 80 ppm), an experimental NO generator (20, 50, 75, and 100 ppm), as well as by glutathione-containing dinitrosyl iron complexes (3 mM/L) were investigated using 15 healthy donors. The influence of endogenous sodium on serum crystallization of intact and NO treated blood samples was evaluated. It was found that the effect of NO on the crystallogenic properties of blood serum is directly determined by its concentration and form (free or bound), as well as by the presence of reactive oxygen species in a gas flow. The most pronounced stimulatory effect was observed for the bound NO form, dinitrosyl iron complexes with glutathione ligands. Low NO concentrations modulated the crystallogenic properties of blood serum, while the best stimulatory effect was demonstrated by the gas flow that contained 20 ppm nitric oxide. In contrast, high NO concentrations (800 ppm) inhibited the crystallogenic activity of the biological medium due to an increase in the destruction of structural elements by many times, which lead to the formation of an additional band in the marginal zone of the microscope specimen.

Pediatric bronchiectasis: No longer an orphan disease.

Bronchiectasis is described classically as a chronic pulmonary disorder characterized by a persistent productive cough and irreversible dilatation of one or more bronchi. However, in children unable to expectorate, cough may instead be wet and intermittent and bronchial dilatation reversible in the early stages. Although still considered an orphan disease, it is being recognized increasingly as causing significant morbidity and mortality in children and adults in both affluent and developing countries. While bronchiectasis has multiple etiologies, the final common pathway involves a complex interplay between the host, respiratory pathogens and environmental factors. These interactions lead to a vicious cycle of repeated infections, airway inflammation and tissue remodelling resulting in impaired airway clearance, destruction of structural elements within the bronchial wall causing them to become dilated and small airway obstruction. In this review, the current knowledge of the epidemiology, pathobiology, clinical features, and management of bronchiectasis in children are summarized. Recent evidence has emerged to improve our understanding of this heterogeneous disease including the role of viruses, and how antibiotics, novel drugs, antiviral agents, and vaccines might be used. Importantly, the management is no longer dependent upon extrapolating from the cystic fibrosis experience. Nevertheless, substantial information gaps remain in determining the underlying disease mechanisms that initiate and sustain the pathophysiological pathways leading to bronchiectasis. National and international collaborations, standardizing definitions of clinical and research end points, and exploring novel primary prevention strategies are needed if further progress is to be made in understanding, treating and even preventing this often life-limiting disease.

Influence of heat treatment on the adsorption, structural, and catalytic properties of decationized L zeolites

1. The changes in the catalytic activity of decationized L zeolites during heat treatment are associated with the formation and removal of proton centers and are not directly related to the decrease in crystallinity. 2. The x-ray diffraction measurement of the decrease in crystllinity during heat treatment reflects the destruction of structural elements but does not permit evaluation of the degree of amorphization of zeolites. 3. The destruction of the skeleton of decationized L zeolites is accompanied by a decrease in the volume of the micropores, but it does not influence the content of open pores and macropores.