Quasi-normal modes of naked singularities in presence of non-linear scalar fields

We study linear perturbations against static spherically symmetric background configurations of General Relativity with a real scalar field (SF), which is minimally coupled with gravity; it is non-linear due to the presence of the self-action potential. The background solutions have a naked singularity at the center of the configuration. The focus is on the stability of the background and fundamental frequencies of the quasi-normal modes (QNM) of the axial perturbations in the Regge-Wheeler gauge. The problem is reduced to one hyperbolic master equation with an effective potential $W_{\rm eff}$, which turns out to be positive for a general non-negative SF potential; this ensures the linear stability with respect to this kind of perturbations. For numerical simulations, the SF potential was chosen in the power-law form $V(\phi)\sim\phi^{2n}$ with $2<n\le 40$. We extracted the fundamental frequencies of QNM for different $n$ and various sets of the background configuration parameters. The results show that even for a small background SF, there is a significant difference between the fundamental frequencies and ones in case of the Schwarzschild background. The results are also compared with the case of the Fisher-Janis-Newman-Winicour background dealing with a massless linear scalar field

Переселення та адаптація холмщаків на Волині в історичній пам’яті

Савчук Олег Анатолійович - кандидат історичних наук, докторант Католицького університету імені Івана Павла II (м. Люблін, Польща)

Investigation of some features of the movement of surface waves and their interaction with the surface objects´ bases and foundations providing seismic safety

В статті розглянуто особливості руху поверхневих хвиль, а також виконано аналіз існуючих методик знаходження часових характеристик та закономірностей їх зміни в процесі руху R-хвилі вздовж вільної поверхні. З цією метою були проведені розрахунки частотно-часових показників за різними формулами в R-хвилі й порівняння між собою та із значеннями в R-хвилі залежно від двох факторів: ваги заряду і приведеної відстані, результати яких висвітлено у даній роботі. Непрямим чином було встановлено, що на будь-якій епіцентральній приведеній відстані поверхнева хвиля значно більш сейсмонебезпечна, ніж об’ємна, яка на будь-яких гіпоцентральних відстанях в різних пунктів на поверхні не може перевищувати величини періоду коливань в пункті при приведеному радіусі, рівному одиниці.The article describes the features of surface waves motion as well as the analysis of existing methods for finding the timing and patterns of change in motion R-waves along the free surface. To this end, we calculated time-frequency performance under different formulas in R-wave and compared with each other and with values in R-wave dependsng on two main factors: the weight of the charge and the reduced distance, the results of which are shown in this paper. Indirectly, it was found that the at any epicentral distance surface wave is significantly seysmic unsafety than the body wave, which in any hypocentral distances at different points on the surface may not exceed the period of oscillation in the above point with raduced radius equal to one.В статье рассмотрены особенности движения поверхностных волн, а также выполнен анализ имеющихся методик нахождения временных характеристик и закономерностей их изменения в процессе движения R-волны вдоль свободной поверхности. С этой целью были проведены расчёты временно-частотных показателей по разным формулам в R-волне и сравнение между собой и с значениями в R-волне в зависимости от двух главных факторов: веса заряда и приведенного расстояния, результаты которых приведены в настоящей работе. Косвенным образом было установлено, что на любом эпицентральном приведенном расстоянии поверхностная волна значительно более сейсмоопасная, чем объемная, которая на любых гипоцентральных расстояниях в различных пунктах на поверхности не может превышать величины периода колебаний в пункте при приведенном радиусе равном 1

Efficiency Evaluation Of Implementation Of Optimization Methods Of Operation Modes Of The "Plast - Gas Pipeline" System By The Methods Of Mathematical Modeling

To date, Ukraine's mature gas fields, which are being developed in the gas regime, are at the final stage of development, which is characterized by a significant depletion of reservoir energy. The final stage of development requires solving complex problems related to watering wells, destruction of the reservoir, removal of formation water and mechanical impurities, increasing back pressure in the system, as well as the moral and physical wear and tear of industrial equipment. In the conditions of falling gas production, a significant part of the operating well stock is unstable, in the mode of unauthorized stops due to the accumulation of liquid at the bottom and insufficient gas velocities for removal to the surface, and also the accumulation of the liquid phase in the lowered places of the gas gathering system.Within the framework of the conducted studies, the gas dynamic models of the operation of the gas collection system of 3 oil/gas-condensate fields (OGCF) are created. A single model of the gas production system "reservoir - well - gas gathering system - inter-field gas pipeline - main facilities" is built. The current efficiency of the gas production, collection and transportation system is assessed. On the basis of model calculations, the current production capabilities of the wells are defined, as well as the "narrow" places of the system.It is established that the introduction of modern technologies for the operation of watered wells without optimizing the operation of the entire gas production system is irrational, since the liquid that is carried out from the wellbore will accumulate in the plumes and increase the back pressure level in the ground part. In conditions of increasing gas sampling, liquid flowlines can be taken out of the loops and deactivated the separation equipment.The feasibility of introducing methods for optimizing the operation modes of the gas production - gathering and transportation system is estimated, which allows choosing the optimal method for increasing the efficiency and reliability of its operation.For the first time in the Ukrainian gas industry, an integrated model of the field is created as a single chain of extraction, collection, preparation and transportation of natural gas, which can be adapted for the development and arrangement of both new and mature deposits.The main advantage of the application for the hydrocarbon production sector is the simulation of the processes, which makes it possible to evaluate the operating mode of the well in the safe zone while reducing the working pressure and introducing various intensification methods, and also to estimate the increase in hydrocarbon production. For the equipment of the ground infrastructure – "midstream" – the main advantage is a reduction in the time required to perform design calculations for gas pipelines, trains and pipelines for transporting multiphase media using public models.The creation and use of integrated models of gas fields gives an understanding of the integral picture of available resources and ensures an increase in the efficiency of field development management.The results of the calculation are clearly correlated with the actual data, which makes it possible to use the models constructed to obtain numerical results