Криптографические методы защиты информации

Developed computer algorithms that simulate the dynamic interaction of elastic blocks through thin viscoelastic layer in structurally inhomogeneous media such as rocks. On the basis of rheological models are constructed for the deformation of the material layers of different levels of complexity. In the numerical solution of one-dimensional problems of applied monotonous gridcharacteristic schemes with a balanced number of time steps in the blocks and interlayers. The problems of software implementation of algorithms on multiprocessor systems with graphics cards. Numerical results demonstrate the qualitative features of the propagation of plane waves in materials with a layered microstructure

Численное моделирование распространения упругих волн в слоистых средах с податливыми прослойками

Methodological approach to students research-oriented teaching of basics of mathematical modeling of real processes is developed. The application of the method is described through an example of theoretical analysis of elastic electron scattering from solid surface phenomenon.

Математическое моделирование в исследовательско-ориентированном обучении студентов физике поверхности конденсированных веществ

The article is devoted to the problem of reduction of tram vibration impact to buildings. It's proposed several variants of down vibration and given short estimation.

Защита зданий от вибрации

The use of ammonia in large-scale refrigeration systems (such as those used for a stadium) requires adequate ammonia leakage prevention mechanisms are put in place. In the present study, numerical simulations have been conducted to study the dispersion law in the ammonia machinery room of the refrigeration system for the 2022 Beijing Winter Olympics. The wind speed, and release location have been varied to investigate their effects on the dispersion profile. Different positions of the leakage points in the ammonia storage tank have been found to lead to different areas affected accordingly. In general, the dangerous region area decreases with an increase in the wind speed. However, when the wind is aligned with the leakage direction, this trend is reverted. The study may offer an effective method to predict the impact of ammonia dispersion and implement the safe operation of such large-scale systems.

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Simulation Analysis of Ammonia Leakage and Dispersion in a Large-Scale Refrigeration System

L. Amelina: ORCID 0000-0002-8525-7096; M. Biliaiev: ORCID 0000-0002-1531-7882; O. Berlov: ORCID 0000-0002-7442-0548; L. Cherednychenko: ORCID 0000-0002-1457-9282

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Risk assessment with the use of the monte-carlo method

Purpose. Development fast calculating model which takes into account the meteorological parameters and buildings which are situated near the source of toxic chemical emission. Methodology. The developed model is based on the equation for potential flow and equation of pollutant dispersion. Equation of potential flow is used to compute wind pattern among buildings. To solve equation for potential flow Samarskii implicit difference scheme is used. The implicit change – triangle difference scheme is used to solve equation of mass transfer. Numerical integration is carried out using the rectangular difference grid. Method of porosity technique («markers method») is used to create the form of comprehensive computational region. Emission of ammonia is modeled using Delta function for point source. Findings. Developed 2D numerical model belongs to the class of «diagnostic models». This model takes into account the main physical factors affecting the process of dispersion of pollutants in the atmosphere. The model takes into account the influence of buildings on pollutant dispersion. On the basis of the developed numerical models a computational experiment was carried out to estimate the level of toxic chemical pollution in the case of unplanned ammonia release at ammonia pump station. Originality. Developed numerical model allows to calculate the 2D wind pattern among buildings and pollutant dispersion in the case unplanned ammonia release. Model allows to perform fast calculations of the atmosphere pollution. Practical value. The model can be used when developing the PLAS (Emergency Response Plan).

http://stp.diit.edu.ua/article/download/104142/102161

Numerical simulation of air pollution in case of unplanned ammonia release

Purpose. The aim of this work is development of numerical model, which allows to calculate the efficiency of neutralizer supply for reduction of air pollution in case of unplanned ammonia emission at the territory of ammonia pump station. The numerical model should allow fast calculating, taking into account the meteorological parameters and buildings situated near the source of toxic chemical emission and equipment for neutralizer supply. Methodology. The developed model is based on the equation for potential flow and equation of pollutant dispersion. To simulate the chemical interaction between ammonia and neutralizer the stoichiometry equation is used. Equation of potential flow is used to compute flow pattern among buildings. To solve the equation for potential flow the Samarskii implicit difference scheme is used. The implicit change-triangle difference scheme is used to solve equation of mass transfer. While for the numerical integration the authors use the rectangular difference grid. Method of porosity technique («markers method») is applied to create the form of comprehensive computational region. Emission of ammonia is modeled using Delta function for point source. Findings. Developed numerical model belongs to the class of «diagnostic models». This model takes into account the main physical factors affecting the process of dispersion of ammonia and neutralizer in the atmosphere, as well as the influence of buildings on admixture dispersion. On the basis of the developed numerical models the authors carried out a computational experiment to estimate the efficiency of neutralizer supply for reduction of air pollution in case of unplanned ammonia release at ammonia pump station. Originality. Developed numerical model allows calculating the flow pattern among buildings and estimating the efficiency of neutralizer supply for reduction of air pollution in the case unplanned ammonia release. Practical value. Model allows performing fast calculations of the atmosphere pollution in the case of unplanned ammonia release

/pdf/reducing-ammonia-concentrations-in-atmosphere-after-its-2qy5qvby8q.pdf

Reducing Ammonia Concentrations in Atmosphere After its Unplanned Release

Purpose. This work provides for the development of a hydraulic model for calculating the unsteady ammonia outflow from a damaged pipeline and the implementation of this model into a numerical model for predicting emergency air pollution. Methodology. To solve the problem, the calculated dependencies of the pressure flow hydraulics were used. An empirical model to calculate the evaporation of ammonia from a damaged pipeline was also used. To calculate the process of spreading ammonia in atmospheric air, a three-dimensional equation of convective-diffusion transfer of impurities was used. Mathematical modeling of the spread of ammonia from a damaged pipeline takes into account the change with height of the wind flow velocity, as well as the change with height of the vertical coefficient of atmospheric diffusion, the dynamics of changes over time in the intensity of ammonia leakage from the damaged pipeline. For the numerical solution of the three-dimensional differential equation for the transfer of ammonia in atmospheric air, its physical splitting is carried out: an equation that describes the transport of an impurity due to convection is singled out separately, an equation that describes the transport of an impurity due to atmospheric diffusion and separately an equation that describes a change in the ammonia concentration in air due to the action of the emission source. The McCormack method is used to numerically integrate the equation for the convective transfer of ammonia in air. The Richardson method is used to numerically integrate the equation of diffusion transfer of an impurity. The Euler method is used to numerically integrate the equation that describes the change in ammonia concentration under the influence of an emission source. Findings. Based on the developed model of unsteady ammonia outflow from the damaged pipeline and the created numerical model of ammonia propagation in the atmospheric air, a computational experiment was carried out to assess the level of atmospheric air and underlying surface pollution in the event of an emergency ammonia outflow in the section where the Tolyatti – Odessa ammonia pipeline crosses the Dnipro River. Data on non-stationary environmental pollution were obtained. Originality. A mathematical model that allows calculating the unsteady process of ammonia outflow from a damaged pipeline has been developed. A numerical model is proposed to determine the areas of contamination during an emergency ammonia outflow from the Tolyatti – Odessa ammonia pipeline. Practical value. Based on the developed model, a code has been created that makes it possible to promptly predict the environmental pollution dynamics during an emergency ammonia outflow. The proposed mathematical model can be used in the development of emergency response plan for chemically hazardous facilities.

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Моделювання забруднення довкілля в разі емісії аміаку з пошкодженого трубопроводу

Мета. Ця робота передбачає розробку математичної моделі для розрахунку вибухонебезпечних зон у разі аварійної емісії аміаку. Як приклад розглянуто аварійну емісію аміаку на території насосної станції, що здійснює перекачування. Методика. Для розв’язання поставленої задачі використано рівняння для потоку нев’язкої нестисливої рідини – рівняння для потенціалу швидкості. Чисельне розв’язання цього тривимірного рівняння проведено за допомогою методу Річардсона. Після визначення потенціалу швидкості розраховано поле швидкості повітряного потоку. Для прогнозування вибухонебезпечних зон використано чисельне розв’язання тривимірного рівняння масопереносу аміаку. Під час використання цієї математичної моделі враховано нерівномірне поле швидкості вітрового потоку, зміну вертикального коефіцієнта атмосферної дифузії з висотою, інтенсивність емісії аміаку, місце викиду хімічно небезпечної речовини. Для чисельного розв’язання рівняння переносу аміаку в атмосферному повітрі використано різницеву схему розщеплення. На кожному кроці розщеплення невідоме значення концентрації аміаку визначено за явною схемою біжучого рахунку. Результати. На основі розробленої математичної моделі проведено обчислювальний експеримент для оцінки динаміки формування вибухонебезпечних зон на території насосної станції, що перекачує аміак. Отримано інформацію про формування зон хімічного зараження на території насосної станції. Наукова новизна. Розроблено математичну модель, що дозволяє оперативно розраховувати динаміку формування вибухонебезпечних зон на території хімічно небезпечного об’єкта в разі виникнення надзвичайної ситуації. Ця модель може бути використана для оцінки ризику токсичного ураження людей на хімічно небезпечному об’єкті під час виникнення аварійних ситуацій. Практична значимість. На базі розробленої чисельної моделі створено комп’ютерну програму, що дозволяє проводити серійні обчислювальні експерименти з визначення динаміки формування зон хімічного зараження атмосферного повітря. Для використання розробленої програми необхідні стандартні вхідні дані. Розроблена чисельна модель може бути використана для проведення серійних розрахунків під час розробки ПЛАСу (план ліквідації аварійної ситуації) для хімічно небезпечних об’єктів.

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L. V. Amelina

Papers

Risk assessment with the use of the monte-carlo method

Numerical simulation of air pollution in case of unplanned ammonia release

Reducing Ammonia Concentrations in Atmosphere After its Unplanned Release

Моделювання забруднення довкілля в разі емісії аміаку з пошкодженого трубопроводу

Calculation of explosive zones in emergency emission of ammonia