909 research outputs found
БОРГОВА БЕЗПЕКА ДЕРЖАВИ У СИСТЕМІ КРЕДИТНИХ ОПЕРАЦІЙ УРЯДУ УКРАЇНИ : ЕКОНОМІКО-МАТЕМАТИЧНЕ МОДЕЛЮВАННЯ
The article considers debt safety as an integral element of the country financial safety. The author has done regressive analysis of the state debt and the main macroeconomic indices and determined the close relationship with the state budget expenditures, the GDP, and the state budget deficit. The author has indicated methodological frameworks of calculation of a ratio of state debt safety: a ratio calculation procedure, a list of indicators of state debt safety, weight coefficients of the indicators, and their threshold values. The author has analyzed the condition of debt safety of Ukraine in 2008-2015. The author has determined the unstable condition in 2011-2012, the critical condition in 2008-2010, 2013, and the crisis condition in 2014-2015. There has been a stable tendency for deterioration of the debt safety condition and the increase of debt dependence of Ukraine since 2011. The author verifies the ratio of state debt safety with the use of a correlation matrix. The author substantiates expediency of application of a simplified model of the ratio of state debt safety on the basis of seven indicators: the relation between a general amount of the state and the government-backed debt and the GDP; a ratio of growth of the general amount of the state debt with reference to the GDP; a share of the external debt in the general amount of the debt; the difference between a rate of growth of the state debt and a rate of growth of the nominal GDP; a share of the debt denominated in a foreign currency in the general amount of the debt; a ratio of change of the official exchange rate of the national currency to the USA dollar; the relation between state debt payments and state budget revenues. В статье рассмотренно долговую безопасность как неотъемлемый элемент финансовой безопасности государства. Проведено регрессионный анализ государственного долга и основных макроэкономических показателей. Определены методологические основы расчета индекса боровой безопасности государства: порядок расчета индекса, перечень индикаторов долговой безопасности государства, весовые коэффициенты индикаторов и их пороговые значения. Проведен анализ состояния долговой безопасности Украины в 2008-2015 гг., осуществлена проверка полученной модели с помощью корреляционной матрицы. Обоснована целесообразность применения упрощенной модели индекса боровой безопасности государства. В статті розглянуто боргову безпеку як невід’ємний елемент фінансової безпеки держави. Проведено регресійний аналіз державного боргу та основних макроекономічних показників. Визначено методологічні засади розрахунку індексу боргової безпеки держави: порядок розрахунку індексу, перелік індикаторів боргової безпеки держави, вагові коефіцієнти індикаторів та їх порогові значення. Проведено аналіз стану боргової безпеки України у 2008-2015 рр. та здійснено перевірку одержаної моделі за допомогою кореляційної матриці. Обгрунтовано доцільність застосування спрощеної моделі індексу борової безпеки держави
Optimization of characteristics of multilayer spherical control joint-hinge stiffness
In this work the analytical expression is derived on the basis of the variational method for the evaluation of angular stiffness characteristics of the spherical multilayered elastomeric package joint-hinge subjected to loading with hinge moment and hydrostatic pressure on the lateral surfaces. Joint-package consists of alternating metallic and thin elastomeric layers. Metallic plates-layers are assumed to be rigid. It is demonstrated that the hydrostatic pressure can both mitigate and "harden" the hinge angular stiffness characteristics depending on which side surface of the elastomeric layer it is applied. Obtained relationships allow solving problems of optimal design, operation and control program selection for compensating joints of this type
Weak and strong coupling limits of the two-dimensional Fr\"ohlich polaron with spin-orbit Rashba interaction
The continuous progress in fabricating low-dimensional systems with large
spin-orbit couplings has reached a point in which nowadays materials may
display spin-orbit splitting energies ranging from a few to hundreds of meV.
This situation calls for a better understanding of the interplay between the
spin-orbit coupling and other interactions ubiquitously present in solids, in
particular when the spin-orbit splitting is comparable in magnitude with
characteristic energy scales such as the Fermi energy and the phonon frequency.
In this article, the two-dimensional Fr\"ohlich electron-phonon problem is
reformulated by introducing the coupling to a spin-orbit Rashba potential,
allowing for a description of the spin-orbit effects on the electron-phonon
interaction. The ground state of the resulting Fr\"ohlich-Rashba polaron is
studied in the weak and strong coupling limits of the electron-phonon
interaction for arbitrary values of the spin-orbit splitting. The weak coupling
case is studied within the Rayleigh-Schr\"odinger perturbation theory, while
the strong-coupling electron-phonon regime is investigated by means of
variational polaron wave functions in the adiabatic limit. It is found that,
for both weak and strong coupling polarons, the ground state energy is
systematically lowered by the spin-orbit interaction, indicating that the
polaronic character is strengthened by the Rashba coupling. It is also shown
that, consistently with the lowering of the ground state, the polaron effective
mass is enhanced compared to the zero spin-orbit limit. Finally, it is argued
that the crossover between weakly and strongly coupled polarons can be shifted
by the spin-orbit interaction.Comment: 11 pages, 5 figure
On the electronic properties of GaSb irradiated with reactor neutrons and its charge neutrality level
The electronic properties and the limiting position of the Fermi level in p-GaSb crystals irradiated with full-spectrum reactor neutrons at up to a fluence of 8.6 × 1018 cm−2 are studied. It is shown that the irradiation of GaSb with reactor neutrons results in an increase in the concentration of free holes to p lim = (5−6) × 1018 cm−3 and in pinning of the Fermi level at the limiting position F lim close to E V + 0.02 eV at 300 K. The effect of the annealing of radiation defects in the temperature range 100–550°C is explored
Optimal design of turbines taking into consideration the mode of operation
The technique of turbines parameters optimization taking into consideration a variable mode of their operation has been developed. Block-hierarchical representation of design process is used. The hierarchy of local optimization problems is organized by a functional sign and realized in a common information space. The structure of optimization technique is shown, and also the analysis of the data streams uniting these problems in unified process of optimal design is resulted. By means of the developed technique optimal design of the 4-stage turbine expander with rated power 4 MW has been performed. Results of the design are presented and analyzed
Retro-Mode Scanning Laser Ophthalmoscopy Planning for Navigated Macular Laser Photocoagulation in Macular Edema
Purpose. To compare treatment areas and navigated macular laser photocoagulation (MLP) plans suggested by retro-mode scanning laser ophthalmoscopy (RM-SLO) image versus optical coherence tomography (OCT) central retinal thickness map and treatment planning among retina specialists. Methods. Thirty-nine eyes with diabetic or branch retinal vein occlusion-related ME undergoing navigated MLP with navigated photocoagulator had OCT and RM-SLO taken. OCT map and RM-SLO image were imported to the photocoagulator and aligned onto the retina. Two retina specialists placed laser spot marks separately based on OCT and RM-SLO images in a random fashion. The spots placed by each physician were compared between OCT and RM-SLO and among physicians. The areas of retinal edema on OCT and RM-SLO of the same eye were also compared. Results. The average number of laser spots using RM-SLO and OCT template was 189.6±77.4 and 136.6±46.8, respectively, P=0.003. The average area of edema on RM-SLO image was larger than that on OCT map (14.5±3.9 mm2 versus 10.3±2.8 mm2, P=0.005) because of a larger scanning area. There was narrow variability in treatment planning among retina specialists for both RM-SLO (P=0.13) and OCT (P=0.19). Conclusion. The RM-SLO image superimposed onto the fundus of the same eye can be used to guide MLP with narrow variability in treatment planning among retina specialists. The treatment areas suggested by RM-SLO-guided MLP plans for ME were shown to be larger than those suggested by OCT-guided plans
ДОСЛІДЖЕННЯ ЕЛЕКТРОМАГНІТНОГО ПРОЦЕСУ В ЕЛЕКТРИЧНІЙ МОДЕЛІ ШЕСТИЛОПАТЕВОГО ВІДЦЕНТРОВОГО НАСОСА
The comparison of the results of theoretical studies of electromagnetic processes in different modes of electrical model of centrifugal pump with six blades with simulation results of the same modes in software package of technical modeling complex electrical and electronic circuits and in software package for modeling hydraulic processes was made. Conclusion on the adequacy of electrical modeling of workflow of centrifugal pumps was done.Осуществлено сравнение результатов теоретических исследований электромагнитных процессов в разных режимах работы электрической модели шестилопастного центробежного насоса с результатами моделирования тех же режимов в пакете схемотехничного моделирования электрических и электронных схем и в пакете программного обеспечения для моделирования гидравлических процессов. Сделан вывод относительно адекватности электрического способа моделирования рабочих процессов центробежных насосов.Бібл. 2, табл. 1, рис. 3
Clinical Study Combination of Navigated Macular Laser Photocoagulation and Anti-VEGF Therapy: Precise Treatment for Macular Edema under Dry Retinal Conditions
Purpose. To compare the controllability of navigated macular laser photocoagulation (MLP) in dry versus edematous retina and validate that pretreatment diagnostic images can be used as basis for navigated MLP after the macular edema (ME) has been resolved. Materials and Methods. Group 1 was divided into subgroup 1 (dry retina MLP) and subgroup 2 (MLP in ME) for comparisons of laser-burn diameters. In group 2, the areas and locations of ME before an intravitreal injection of anti-VEGF (IVAV) were compared with those of recurrent ME. Results. The average actual diameter as percentage of planned diameter of laser burn in subgroup 1 (11 DME eyes, 6 BRVO eyes) versus subgroup 2 (5 DME eyes, 8 BRVO eyes) was 115.1 ± 9.1% versus 167.2 ± 13.8% (based on retro-mode scanning laser ophthalmoscopy), and 118.1 ± 14.8% versus 176.1 ± 11.6% (based on OCT) (p < 0 001). In group 2 (6 DME eyes, 6 BRVO eyes), difference in mean ME area before IVAV and that in recurrent edema was insignificant ( p > 0 05). Conclusion. The controllability of navigated MLP in dry retina is improved compared to edematous retina. This study validates that pretreatment diagnostic images can be used as basis for navigated MLP after the edema has been resolved
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