Probability Of Destruction Research Articles

Analytical solutions of radiative transfer equations in accretion discs with finite optical depth

ABSTRACT The main purpose of this paper is to obtain analytical solutions for radiative transfer equations related to the vertical structure of accretion discs with finite optical depth. In the non-grey atmosphere, we employ the optical-depth dependent Eddington factor to define the relationship between the mean intensity and radiation stress tensor. Analytical solutions are achieved for two cases: (i) radiative equilibrium, and (ii) a disc with uniform internal heating and both cases are assumed to be in local thermodynamical equilibrium (LTE), too. These solutions enable us to study probable role of scattering and disc optical depth on the emergent intensity and other radiative quantities. Our results show that for the first case, the surface value of mean intensity with constant Eddington factor is three times larger than that with variable factor. Moreover, scattering has no role in the vertical radiative structure of discs with the assumptions of the first case. On the other hand, for the second case, we encounter reductions in all radiative quantities as the photon destruction probability decreases (which is equivalent to increasing scattering). Furthermore, for both cases with total optical depth less than unity, the outward intensity towards the polar direction becomes less than that from the edges of disc which is contrary to limb-darkening. At the end, we apply our results to find the spectrum from accretion systems, based on two dynamical models. Consequently, we can see that how the total optical depth varies with frequency and causes remarkable changes on the emergent spectra.

High H-atom Density in R(He,Ar)/x%(N2–5%H2) Early Afterglows

Absolute densities of N atoms and N2(A) molecules and estimated densities of H atoms and N2(X,v > 13) and NH molecules are determined in R(He,Ar)/x%(N2–5%H2) flowing microwave discharges by a band intensity ratio method after calibration of the N atom density by NO titration. By varying the plasma parameters: pressure of 8 and 4 Torr, flow rates of 0.5, 1.0 and 2.0 slpm, HF power up to 150 W, a high N + N recombination fraction (> 80%) has been observed with He dilution in the early afterglow (t = 5 × 10–3 s). A maximum value of the H-atom density has been found in the He/2%(N2–5%H2) gas mixture at 8 Torr, 0.5 slpm and 150 W, with a [H]/[N] ratio of 0.3. With Ar dilution, it is found that the Ar/5%(N2–5%H2) gas mixture at 4 Torr, 0.5 slpm, 100 W brought a high H2 dissociation (80%), with a [H]/[N] ratio of about 0.6. From the variation of the H-atom density along the quartz tube, the wall destruction probability of the H-atoms was calculated to be $${\gamma }_{H}^{He}$$ = $${\gamma }_{H}^{Ar}$$ = (1–4) × 10–3 in helium and argon mixtures. Such results are of interest for the enhancement of surface nitriding by the combined effects of N and H atoms inclusion inside a TiO2 surface.

ON DETERMINATION OF ASSAULT AVIATION AIRCRAFT EFFECTIVENESS

When analyzing typical assault aviation combat missions, the most common objects for each aircraft actions should be identified, a preliminary estimate of their distance from the front line has to be provided, and one of the objects should be selected as the typical target for evaluating the aircraft effectiveness.
 A destruction of a typical target by an aircraft with a certain probability is one of the main components of the assault aviation aircraft effectiveness, but it does not fully characterize the effectiveness of the aircraft.
 In the course of assault aircraft combat mission accomplishment, the generally accepted approach is identification the four aircraft flight phases with a purpose of destruction a surface target.
 As a combat mission for assault aircraft the striking for destruction an enemy airfield or division of guided missiles can be considered.
 The choice of flight route and profile is related to the assessment of the enemy's actual areas of engagement to determine the line of maneuvering.
 The feature of devastating effect of attack ammunition is the conditional law of target destruction. For the means of destruction of a remote action the feature of devastating effect of attack ammunition is a cumulative effect of each munitions at known coordinates of impact points.
 For the means of destruction which are used in cluster bombs, as a result of small caliber live ammunition scattering the total area of destruction is created. The cover area for single cluster bomb is ellipse shaped.
 Thus, in order to evaluate the effectiveness of the assault aviation aircraft employment it is advisable to use an indicator such as the effectiveness of the aircraft in one combat sortie. Evaluation of aircraft effectiveness in one sortie consists of estimates of the probability for penetration the means of air defense, the probability of target detection, the probability of target attack, the probability of target destruction and reliability of aviation equipment. For assault aviation, the effectiveness of an aircraft in a single combat sortie has the notion of a total probability of a target destruction or a mathematical expectation of a target destruction.

Non-Structural Damage Verification of the High Pressure Pump Assembly Ball Valve in the Gasoline Direct Injection Vehicle System

The injection pressure of the gasoline direct injection vehicle is currently developing from the low pressure to the high pressure, and the increase of the injection pressure has brought various damage problems to the high pressure pump structure. These problems should be solved urgently. In this paper, the damage problem of the high pressure pump unloading valve ball in a gasoline direct injection vehicle under high pressure conditions is studied. The theoretical calculation of the force of the pressure relief valve is carried out. Firstly, the equivalent friction coefficient is obtained by decoupling analysis of the statically indeterminate model. Based on this, a finite element model is established. The equivalent stress is obtained by numerical simulation. The equivalent stress is compared with the yield strength of the valve ball material to determine that the valve ball damage is a non-static damage. At the same time, the s-N curve of the probability of destruction of one-millionth of the material of the valve ball is given. Then, the fatigue numerical simulation is performed. A safety factor of 3.66 is obtained. In summary, the high pressure relief valve ball in the direct injection high pressure pump should not be a traditional structural damage under high pressure conditions. In the theoretical calculation, the tangential displacement and radial displacement of the ball are all on the micrometer level. It can be presumed that the surface damage of the valve ball is microscopic damage, such as fretting wear.

Statistical assessment of damnification risk due to inconformity of paint coating quality

Introduction. In connection with the increase in the proportion of paint compositions in the decoration of buildings and the actualization of the building structure finishing quality issues, it is necessary to determine the degree of damnification risk if the quality of paints and coatings does not conform to requirements.
 Materials and methods. In order to assess the risk in the work, the study used polyvinyl acetate cement (PVAC) paint, MA-15 oil paint, PF-115 alkyd paint, AK-111 water-dispersion acrylic paint, KO-168 organic-silicone paint, and PI polymer lime paint as paint compositions. The risk was considered as the probability of an event that harms the paint coating. In addition to this, a calculation of the risk R as the expected damage Y due to destruction of the coating was performed.
 Results. The research has established that some coatings are characterized by lower uniformity of adhesion strength values than it is required on the grounds of the relation between the actual and normative coefficients of variation. The values of risk r indicate that the probability of adhesive destruction is minimal. The calculation of the risk R as the expected damage Y because of the coating destruction due to the violation of adhesion showed that the maximum risk R values are from 0.068 to 11.18 rubles per square meter.
 Conclusions. It is established that the probability of paint coating adhesive destruction is minimal. The values of risk as expected damage because of coating adhesive destruction are from 0.068 to 11.18 rubles per square meterб depending on the coating type. When making a managerial decision on a paint production, a risk of economic damage should be estimated.

КИНЕТИКА РАЗРУШЕНИЯ ЧАСТИЦ МАТЕРИАЛА В ДЕЗИНТЕГРАТОРЕ В РАМКАХ СТАТИСТИЧЕСКОГО ПОДХОДА

Disintegrators are one of the types of equipment that has the ability to combine grinding, mixing and activation of materials of medium strength and hardness. The advantages of disintegrators are the ability to integrate into existing technological schemes and obtain a grinding product with a given particle size distribution, as well as the simplicity of the design. This article analyzes the kinetics of particle destruction in the inter-row spaces of the disintegrator grinding chamber. A diagram of the disintegrator grinding chamber is presented. The mathematical description of impact destruction of particles in the grinding chamber is considered in the framework of the inhomogeneous Markov process. An equation is presented that describes the change in the statistical quantity m (t) - the mathematical expectation. It has been suggested that the intensity of the Markov process ( ) is proportional to the frequency (ω) of rotor rotation multiplied by the time function f (t). This functional dependence is determined from the condition of the same interaction time 0 of the material particle in the inter-row spaces of the grinding chamber. If we assume that the probability of destruction of the particles of the material in the interaction with each shock element is constant, then the mathematical expectation value m (t) will be proportional to the number of particles n (t). The resulting relation (11) determines the law of change in the number of particles during the passage of each row of shock elements. The article derived formulas for determining the change in the number of particles in each inter-row space of the grinding chamber. The obtained relations (24) and (25) describe the kinetics of grinding material particles in the grinding chamber of the disintegrator in the framework of the statistical approach and make it possible to determine the relationship between the size of the initial particles and the size of the grinding product.

PROCEDURE OF PROBABILISTIC STRENGTH ASSESSMENT OF MONOLITHIC REINFORCED CONCRETE LINIGS OF HIGH-PRESSURE HYDROTECHNICAL TUNNELS OF HPP AND PSPP DURING THE OPERATIONAL PERIOD

In the article, a methodology for the probabilistic assessment of the strength of monolithic reinforced concrete lining of hydraulic pressure tunnels of HPPs and PSPs during the operational period has been developed within the theory of complex technical systems reliability. Based on the analysis of the available deterministic solution to the problem of stresses in the working annular reinforcement for the considered lining, the coupling equation necessary for solving the probabilistic problem is obtained. The dividing of the parameters included in the coupling equation into random and nonrandom (deterministic) is justified. Recommendations for the selection of distribution functions types, as well as the parameters of these functions for random variables included in the obtained coupling equation are given. An algorithm for solving the posed probabilistic problem by the Monte Carlo method is proposed. Recommendations on the selection of the of statistical tests number that provide sufficient accuracy of the calculation results are given. Based on the proposed algorithm, Ukrhydroproject PJSC developed a software As a result of this software operation, the calculated probability of the tunnel lining destruction at the end of the estimated operating life, as well as the annual probability of the tunnel lining destruction, can be obtained. The calculations of the probability of destruction of the reinforced concrete lining of the supplying high-pressure tunnel of the Dniester PSP are carried out. The following results were obtained the probability of destruction of the lining of the tunnel during the estimated service life 2.42ˑ10-4 and the annual probability of destruction of the tunnel lining is 0.24ˑ10 -5 1/year.

Technological conditions of abrasive tool operation

. An abrasive instrument with every day finds all greater application at implementation of operations from finish abrasive treatment of details of machines, cleaning of metallic and non-metal surfaces from paints and varnishes coverages, blight and contaminations. Polymeric-abrasive brushes in most cases apply in combination with the hand angular grinding machines of small power.The basic task of work are determinations of power charges and their distribution with the aim of minimization of heating of polymeric matrix and increase of part of energy, that is spent on the output of material that is subject to moving away.At determination of power charges the next indexes of power were taken into account, namely: power, that is passed from abrasive grain that gap-filling fiber, at a contact with the processed surface; power of destruction of surface that is processed; power of thermal losses of energy is at the friction of fiber at the surface of material that is processed. Taking into account the enumerated indexes of power the condition of balance of energy is made. It allowed to define an output-input of abrasive instrument ratio and set, what factors result in his increase. And also, to get dependence, that describes the general overfall of temperatures on that the fiber of brush is heated for all the time of her work.For determination of probability of faultless work of machines with polymeric-abrasive brushes a flow diagram that includes two criteria was made: probability of destruction of fiber from a tiredness and probability of destruction of fiber from the pin loading. The made chart was examined with authenticity of faultless work of instrument on each of these criteria. The decision of the system of probability of faultless work of brush is dependence, that allows to define tenure of employment of brush. Thus, possibility to expect the number of polymeric-abrasive brushes for providing of trouble-free implementation of works appears on a site or assembling area.An increase to the output-input ratio is provided by next indexes, namely, diminishing of specific heat capacity, mass of fiber and overfall of temperatures of fiber for one turn of brush. And also increase of amount of abrasive, border of durability and crossing of fiber and length of arc of contact.Determination of probability of faultless work of hand and portable machines with polymeric-abrasive brushes the resource of their work allows to determine.

ГЕОМЕХАНИЧЕСКОЕ ОБОСНОВАНИЕ ПАРАМЕТРОВ УСТОЙЧИВЫХ КАМЕР И ЦЕЛИКОВ В СЛОЖНЫХ ГОРНО-ГЕОЛОГИЧЕСКИХ УСЛОВИЯХ

Актуальность исследования обусловлена необходимостью обеспечения безопасности на Соколовском подземном руднике, а также повышения полноты и качества выемки руды в сложных горно-геологических условиях – при наличии покрывающей толщи обводненных рыхлых отложений. Цель: определить оптимальные параметры устойчивых камер и целиков для предотвращения обрушения горных пород и проникновения песчано-глинистых масс в подземные выработки. Объект: массив горных пород на Северном участке Соколовского месторождения. Методы. Многовариантное численное моделирование методом конечных элементов в двумерной постановке выполнялось в программе Rocscience RS2, что позволило учесть большое количество факторов, влияющих на состояние массива. При расчетах приняты во внимание не только физико-механические свойства пород и действующие в массиве напряжения, но и структурные характеристики массива, а также степень техногенного воздействия. В качестве модели поведения массива использовалась модель Хоека–Брауна, отличительным преимуществом которой является ее нелинейность. Так как реальный массив характеризуется неоднородностью прочностных свойств и напряженно-деформированного состояния, был выполнен предусмотренный в программном комплексе Rocscience вероятностный анализ, учитывающий изменение граничных условий в установленных интервалах для создаваемой модели. В результате численного моделирования определено изменение напряженно-деформированного состояния массива, на основании чего вычислены коэффициент устойчивости окружающего массива, величины и направления его смещений, а также установлены зоны распределения вероятности разрушения массива в заданных интервалах граничных условий. Определены параметры камер и целиков, обеспечивающие общую устойчивость, минимизирующие возможность прорыва водогрязевых масс в выработки. Выводы. Сохранение устойчивости кровли подземных камер при отработке очистных рудных блоков на шахте «Соколовская» позволит снизить риск проникновения песчано-глинистых масс в подземные выработки, обеспечивая безопасное и эффективное ведение горных работ, а также повысить полноту и качество выемки руды. Выполненное методом конечных элементов многовариантное численное моделирование влияния очистных выработок на массив позволило определить оптимальные геометрические параметры камер и целиков, обеспечивающие устойчивость окружающего массива. Применение программного комплекса Rocscience RS2 в результате учета большого количества факторов, влияющих на состояние массива, значительно повышает надежность оценки устойчивости массива.

Probability of brick structures destruction

The results of calculations of construction brick destruction probability determination at central and off-center compressionare given; the determination of the brick structures destruction probability, caused by the exhaustion of the masonry strengthon local compression (crushing); determination of the brick structures destruction probability associated with the exhaustionof the masonry strength on the displacement (cut); determination of the brick structures destruction probability associatedwith the exhaustion of the masonry strength on the fold, the stretch; determination of the brick structures destruction probabilityon the crack opening. The value of the security characteristic for each case has been determined and the comparisonwith the normative values has been made.

Densities of Active Species in R/x%(N2–5%H2) (R = Ar or He) Microwave Flowing Afterglows

Afterglows of R/x(N2–5%H2) (R = Ar or He) flowing microwave discharges are characterized by optical emission spectroscopy. Absolute densities of N atoms and N2(A) and N2(X,v > 13) molecules and estimated densities of NH and H atoms are determined after calibration of the N atom density by NO titration. It is determined the variations of active species densities along the post-discharge tube from the early afterglow to the late afterglow region. Conditions allowing to obtain a high concentration of H-atoms in dominant N-atoms have been found in the early afterglow region of the R/x(N2–5%H2) mixture for x < 5%. From these densities, the destruction probabilities of the H-atoms on the afterglow quartz tube wall is found to be: $$\gamma_{H}^{He}$$ = (2–3) × 10−4 and $$\gamma_{H}^{Ar}$$ = (3–4) × 10−3. The interest of these results concerns the enhancement of surface nitriding by combined effects of N and H atoms inclusion in afterglow conditions.

Short communication: A model to predict flood loss in mountain areas

Because effects of climate change and an increase in elements at risk, mountain hazard loss increased throughout Europe. Yet, factors influencing loss, i.e. vulnerability, have gained less attention to date. Vulnerability is defined as the degree of loss resulting from the hazard impact on buildings. Recent studies have focused on evaluating vulnerability to dynamic flooding using proxies from case studies and based on empirical ex-post approaches. However, the transferability to other case studies and, therefore, the ability of such models to actually predict future losses is limited. To overcome this gap, we present a beta model based on loss data from the European Alps, which clearly shows that a single vulnerability function is sufficient to predict losses resulting from different types of torrential hazards and to provide probabilities of destruction under specific scenarios. As a result, the curves are transferable and may significantly increase the predictive power of risk analyses.

Study on the active phase formation of Pd-Zn/Sibunit catalysts during the thermal treatment in hydrogen

In the present research, the process of the formation of the active components of Pd-Zn catalysts supported on carbonaceous material Sibunit prepared by the joint impregnation (Pd:Zn = 1) is studied. It was shown by means of TPR and EXAFS techniques that the interaction between palladium and zinc begins already at T > 200 °C. During the reduction in hydrogen at temperatures of 200–300 °C the surface of particles being formed is enriched with oxidized zinc. In the temperature range of 400–500 °C zinc is completely reduced, and the crystal lattice of a substitutional solid solution based on fcc lattice of palladium is restructured in tetragonal lattice of PdZn. However, an increase of the calcination temperature in H2 atmosphere (500 °C) significantly rises up the probability of partial destruction of bimetallic phase due to the partial migration of zinc atoms from the surface into the bulk of particles.

Method of engine structural frame vibrations analysis during fan blade-out

The probability of fan blade destruction is extremely small but not equal to zero. The consequences of fan blade-out (FBO) can be catastrophic. The absence of dangerous consequences during FBO event should be confirmed by expensive tests. This causes urgency of developing accurate computational techniques for engine structural frame vibrations analysis. In this paper, we propose an approach to determining rotor-casing system dynamic response to unbalance associated with FBO. The problem is solved in a nonlinear non-stationary formulation. Rotor-casing contact interaction, blades crown stiffness and changes in rotational speed are taken into account.

Recurrent black stains and periodontal disease.

The objective of this study was to identify the anaerobic pigment-forming bacteria present in black stain and correlate its occurrence with dental caries incidence and periodontal destruction. A total of 50 healthy subjects with the chief complaint of recurrent black stains were selected based on the inclusion and exclusion criteria. decayed/missing/filled surfaces score, community periodontal index, Gingival Crevicular Fluid (GCF), black stain score, and microbial analysis were done. The data presented indicate that black stain has a constant microflora, dominated by various gram-negative rods, gram-positive cocci and rods (P ≤ 0.1). However, the incidence of gram-positive rods decreased with the increase in plaque score and probing depths and decrease in black stain score. Presence of black stains is predominated by various gram-positive and negative rods, and gram-positive cocci. Increase in the plaque score decreases the severity of black stains, thereby increasing the probability of periodontal destruction and dental caries incidence in adult subjects. Further studies are required to corroborate the results.

Evaluation Method of the Fatigue Life of Power Plant Pipelines

The method for estimating the fatigue life of power plant pipelines based on the results of one or two tests without destruction is proposed. The proposed method uses the classical model of fatigue resistance. Weller curves for power plant pipelines are determined experimentally, the experimental data are presented. Three curves are constructed for the probability of destruction of 2%, 50%, and 98%. The proposed method uses the hypothesis of linear summation of Palmgren-Miner injuries. When developing the method, much attention is paid to the ways of schematizing the actual process of loading the pipelines. Calculation of the distribution of the total number of cycles was carried out by the “Rainflow” method and the Gusev method. The application of this method with a set of design measures provides more than fivefold margin for fatigue resistance of all pipelines of the power plant.

Model of ultrasonic cavitation depolymerization of oil for evaluation of optimum modes and conditions providing reducing viscosity at low temperatures

The paper presents the model of ultrasonic cavitation depolymerization which is destruction of oil macromolecules under cavitation. The model allows to evaluate optimum modes and conditions of ultrasonic influence, providing reducing oil viscosity at low temperatures. The model is based on probability approach which allows to simplify the task of cavitation depolymerization calculation in order to solve the system of self-similar equations for macromolecules with different weights concentration. The equations include probability of macromolecules destruction. The probability is determined by cross-section of collision of macromolecules pair and possibility of macromolecule destruction at contact with another molecule. The calculations have shown that the cavitation reduces the modal molecular weight up to 2 times. It causes reducing the oil viscosity up to 4…10 times. This has great actuality for oil transferring at low temperatures.

Reliability Comparison of Trusses Made of Thin-Walled Steel Sections

The authors suggest a new truss with nodal conjugations without misalignment in the nodes. They have a greater load capacity and reliability. The results have been confirmed by the calculation of the above-mentioned trusses by the finite element method. The reliability function of trusses made of thin-walled steel sections can be determined taking into account the rods destruction probability in the system. We consider a design with the most unfavorable design model in which the destruction of any rod leads to the entire system failure. For the truss refusal it is assumed that the yield point of the material is reached at least in one of its cores. A probabilistic technique for estimating the reliability of rod structures made of thin-walled steel sections has been proposed. Other parameters being equal, including the geometric dimensions of the truss, loads, the nature of their application one can determine the most rational scheme of the truss in terms of its reliability. Differences in nodes design and internal forces direction will lead to a change in their values in trusses elements. Thus, the trusses reliability will depend on the mathematical expectation of internal efforts, camber and flexibility.

Formation of wear resistant nanostructural topocomposite coatings on metal materials by ionic-plasma processing

The article regards formation processes of activation and dissipative energy flows under ion-plasma sputtering of coatings. It proposes an advanced system of ionic-plasma processing with the activation of the processed surface by high voltage pulses of electric potential. The authors carry out the experimental evaluation of tribological properties for the samples with coatings and study the features of their surface damage. It is established that the topokompozitny coverings, containing high-disperse nanodimensional clusters reduce probability of brittle destruction during an initial stage of operation of tribocouplings. They show that the use of high-frequency pulse oscillations under ion-plasma sputtering decreases friction ratio and increases wear resistance of coatings.

STRENGTH CONTROL SYSTEM UNDER DYNAMIC LOAD WITH ELECTROMAGNETIC ACCELERATOR

The article describes the device to control the strength of brittle materials under dynamic load. A design was developed and an electromagnetic accelerator was manufactured. It allows to perform mechanical strength tests of brittle materials at speeds up to 10 m/s. It was defined that the device on the basis of the Hopkinson measuring cores can also be used while studying the energy characteristics of the solid alloys destruction and the investigation of the cutting process. The obtained experimental results on the strength of solid alloys can be used to predict the probability of incisors destruction.