Numerical simulation of surface waves instability on a discrete grid

We perform full-scale numerical simulation of instability of weakly nonlinear waves on the surface of deep fluid. We show that the instability development leads to chaotization and formation of wave turbulence. We study instability both of propagating and standing waves. We studied separately pure capillary wave unstable due to three-wave interactions and pure gravity waves unstable due to four-wave interactions. The theoretical description of instabilities in all cases is included into the article. The numerical algorithm used in these and many other previous simulations performed by authors is described in details.Comment: 47 pages, 40 figure

Mesoscopic wave turbulence

We report results of sumulation of wave turbulence. Both inverse and direct cascades are observed. The definition of "mesoscopic turbulence" is given. This is a regime when the number of modes in a system involved in turbulence is high enough to qualitatively simulate most of the processes but significantly smaller then the threshold which gives us quantitative agreement with the statistical description, such as kinetic equation. Such a regime takes place in numerical simulation, in essentially finite systems, etc.Comment: 5 pages, 11 figure

Optical Pulse Dynamics in Active Metamaterials with Positive and Negative Refractive Index

We study numerically the propagation of two-color light pulses through a metamaterial doped with active atoms such that the carrier frequencies of the pulses are in resonance with two atomic transitions in the $\Lambda$ configuration and that one color propagates in the regime of positive refraction and the other in the regime of negative refraction. In such a metamaterial, one resonant color of light propagates with positive and the other with negative group velocity. We investigate nonlinear interaction of these forward- and backward-propagating waves, and find self-trapped waves, counter-propagating radiation waves, and hot spots of medium excitation.Comment: 9 pages, 6 figure

Extraction processing of concentrated solutions of uranyl nitrate with high impurities content

Process flowsheet of recycling uranium concentrated solutions with its purification from insoluble impurities of iron, silicon, molybdenum, calcium oxides and hydroxides and soluble impurities with application of centrifugal extractors cascade has been developed and suggested for commercial introduction. The process was carried out at extractant saturation (30 % tributyl phosphate in hydrocarbon diluent) in extraction assembly lower than a limiting level (85...95 g/l) and in wash assembly - at limiting saturation (up to 120 g/l). As a result the waste uranium content in water-tail solutions 0,01...0,04 g/l and minimal content of impurities in re-extractors is provide

Coexistence of Weak and Strong Wave Turbulence in a Swell Propagation

By performing two parallel numerical experiments -- solving the dynamical Hamiltonian equations and solving the Hasselmann kinetic equation -- we examined the applicability of the theory of weak turbulence to the description of the time evolution of an ensemble of free surface waves (a swell) on deep water. We observed qualitative coincidence of the results. To achieve quantitative coincidence, we augmented the kinetic equation by an empirical dissipation term modelling the strongly nonlinear process of white-capping. Fitting the two experiments, we determined the dissipation function due to wave breaking and found that it depends very sharply on the parameter of nonlinearity (the surface steepness). The onset of white-capping can be compared to a second-order phase transition. This result corroborates with experimental observations by Banner, Babanin, Young.Comment: 5 pages, 5 figures, Submitted in Phys. Rev. Letter

Weak Turbulent Kolmogorov Spectrum for Surface Gravity Waves

We study the long-time evolution of gravity waves on deep water exited by the stochastic external force concentrated in moderately small wave numbers. We numerically implement the primitive Euler equations for the potential flow of an ideal fluid with free surface written in canonical variables, using expansion of the Hamiltonian in powers of nonlinearity of up to fourth order terms. We show that due to nonlinear interaction processes a stationary energy spectrum close to $|k| \sim k^{-7/2}$ is formed. The observed spectrum can be interpreted as a weak-turbulent Kolmogorov spectrum for a direct cascade of energy.Comment: 4 pages, 5 figure

Определение прогибов железобетонных стоек опор воздушных линий электропе-редачи

The paper contains values of torque magnification ratio while shifting vertical loads due to horizontal wind forces affecting on supports of overhead transmission lines of 35 kV and higher. These values pertain to various types of unified reinforced concrete conic and cylindrical supports while changing climatic conditions. The values make it possible to exclude rather complicated calculations in respect of support deflection in the case when there is uncertainty in initial data.Получены значения коэффициента увеличения изгибающего момента при смещении вертикальных нагрузок из-за действующих на опоры горизонтальных ветровых сил воздушных линий электропередачи напряжением 35 кВ и выше для различных типов унифицированных железобетонных конических и цилиндрических стоек при изменении климатических условий. Эти значения позволяют освободиться от необходимости выполнения сложных расчетов прогибов стоек при неопределенности исходной информации

О целесообразности прокладки вне населенных пунктов кабельных линий электропередачи напряжением 6–35 кВ вместо воздушных

. It is noted that at present, 10 and 35 kV overhead power transmission lines are being laid outside the settlements of the Republic of Belarus on reinforced concrete vibrated (10 kV) and centrifuged (35 kV) poles that are characterized by low reliability and damaging the environment (on account of alienation of land for poles, the need to make a wide clearing for laying in the forest, obstructions by poles and wires of lines to the operation of agricultural machinery, the danger of electric shock to personnel and the public). It is possible to avoid these disadvantages if, instead of overhead lines, power transmission cables with cables insulated by cross-linked polyethylene are used which are characterized by a very low failure flow parameter. Contrary to the prevailing opinion about the higher cost of cable power transmission lines compared to overhead ones of the same rated voltage, it turned out that, taking into account reliability, the cost of electricity lost in the lines for a year, damage to the environment and to the power system caused by the need to perform more expensive emergency repairs (as compared to a planned one), laying cable lines with three-core and single-core cables of a voltage of 10 and 35 kV instead of overhead cables outside the populated area is fairly justified. In this connection, the laying of three-core cables is more preferable. It should be also borne in mind that with an increase in the length of cable lines, the capacitive earth fault current increases, to compensate for which additional devices are needed to be installed in power centers, viz. arc-extinguishing reactors or resistors, accounting for the cost of which (up to 22 % of the cost of one kilometer of cable line) does not significantly affect the conclusions we have drawn regarding the effectiveness of using 6–35 kV cable power lines in an unpopulated area instead of overhead ones, however.В настоящее время в Республике Беларусь вне населенных пунктов прокладываются воздушные линии электропередачи напряжением 10 и 35 кВ на железобетонных вибрированных (10 кВ) и центрифугированных (35 кВ) стойках опор. Они отличаются низкой надежностью и наносят ущерб окружающей среде, поскольку требуют отчуждения земли под опоры и вырубки широкой просеки для прокладки в лесном массиве. Кроме того, опоры и провода линий электропередачи создают препятствия для работы сельскохозяйственных машин, несут опасность поражения электрическим током персонала и населения. Избежать отмеченных недостатков можно, заменив воздушные линии кабельными, в которых используются кабели с изоляцией из сшитого полиэтилена, характеризующиеся весьма низким параметром потока отказов. Вопреки сложившемуся мнению о более высокой стоимости кабельных линий электропередачи по сравнению с воздушными того же номинального напряжения, оказалось, что при учете надежности, стоимости потерянной в линиях за год электроэнергии, ущерба окружающей среде и энергосистеме от необходимости выполнения более дорогостоящих по сравнению с плановыми аварийных ремонтов, прокладка кабельных линий с одно- и трехжильными кабелями на напряжение 10 и 35 кВ вместо воздушных вне населенной местности вполне оправданна. При этом более предпочтительна прокладка трехжильных кабелей. Следует иметь в виду, что с увеличением протяженности кабельных линий растет емкостный ток замыкания на землю, для компенсации которого в центрах питания необходимо устанавливать дополнительные средства – дугогасящие реакторы или резисторы, учет стоимости которых (до 22 % от стоимости 1 км кабельной линии) тем не менее не оказывает существенного влияния  на сделанные нами выводы относительно эффективности применения кабельных линий электропередачи напряжением 6–35 кВ в ненаселенной местности вместо воздушных

Испытания кабельной продукции на термическую и динамическую стойкость

The paper considers conditions for selection of  power supply of the unit which is used for testing samples of cable products by thermal and dynamic stability currents. It has been shown that while conducting testing by thermal and dynamic stability currents at nominal cable voltage it is more justifiable to use a percussive energy accumulator, and in the case when the voltage is low an inductive energy accumulator is used.Рассмотрены условия выбора источника питания установки для проведения испытаний образцов кабельной продукции токами термической и динамической стойкости. показано, что при проведении испытаний токами термической и динамической стойкости при номинальном напряжении кабеля целесообразно использовать ударный накопитель энергии и при пониженном напряжении – индуктивный накопитель энерги