Effect of ultraviolet and x-ray radiation on optical properties of epoxy polymers dyed with organic phosphors

Highly purified industrial bisphenol and cycloaliphatic epoxy oligomers of ED-24 and UP-612 brands were used to produce optically transparent products. UV radiation of a low-pressure mercury lamp with 80% of the light energy at 254 nm was used to study photodegradation. X-ray apparatus with 0.7BSV- Ag tube was used as an ionizing radiation source to investigate the effect of X-rays on the spectra of organic dyes in epoxy polymer. The threshold value of the energy generated by ruby laser which indicated the degradation in the test samples recorded by light scattering method was determined to study radiation resistance of epoxy polymers. Basically, all the dyes exhibited high resistance to UV light. The observation of the absorption spectra showed that on average, a third of the dye molecules in the matrix experienced photobleaching within 200 hour exposure. The exception was coumarin 1, which was completely decolourized after 40 hours of exposure. X-ray irradiation of the samples for two hours results in the change in the optical density equivalent to that caused by 40 hour exposure to UV irradiation. However, in the first case, the matrix optical density is proportional to the irradiation time, and in the second case, it remains stable upon further UV irradiation. The comparison of photoaging processes in dyed and undyed epoxy polymers showed that the investigated organic dyes do not have a sensitizing effect on the matrix. The stability of the optical properties of the epoxy matrices exposed to the effects of different factors was found to depend on the nature of epoxy polymer and the technique of its production. The results of these effects are significantly different in the character of the change in the optical density and mechanisms of chemical transformations in polymer

Three-dimensional steep wave impact on a vertical cylinder

In the present study we investigate the 3-D hydrodynamic slamming problem on a vertical cylinder due to the impact of a steep wave that is moving with a steady velocity. The linear theory of the velocity potential is employed by assuming inviscid, incompressible fluid and irrotational flow. As the problem is set in 3-D space, the employment of the Wagner condition is essential. The set of equations we pose, is presented as a mixed boundary value problem for Laplace's equation in 3-D. Apart from the mixed-type of boundary conditions, the problem is complicated by considering that the region of wetted surface of the cylinder is a set whose boundary depends on the vertical coordinate on the cylinder up to the free-surface. We make some simple assumptions at the start but otherwise we proceed analytically. We find closed-form relations for the hydrodynamic variables, namely the time dependent potential, the pressure impulse, the shape of the wave front (from the contact point to beyond the cylinder) and the slamming force

Deflection of ice cover caused by an underwater body moving in channel

Deflections and strains in an ice cover of a frozen channel caused by an underwater body moving under the ice with a constant speed along the channel are studied. The channel is of rectangular cross section, the fluid in the channel is inviscid and incompressible. The ice cover is clamped to the channel walls. The ice cover is modeled by a thin viscoelastic plate. The underwater body is modeled by a three-dimensional dipole. The intensity of the dipole is related to the speed and size of the underwater body. The problem is considered within the linear theory of hydroelasticity. For small deflections of the ice cover the velocity potential of the dipole in the channel is obtained by the method of images in leading order without account for the deflection of the ice cover. The problem of moving dipole in the channel with rigid walls provides the hydrodynamic pressure on the upper boundary of the channel, which corresponds to the ice cover. This pressure distribution does not depend on the deflection of the ice cover in the leading approximation. The deflections of the ice and strains in the ice plate are independent of time in the coordinate system moving together with the dipole. The problem is solved numerically using the Fourier transform, method of the normal modes and the truncation method for infinite systems of algebraic equations

Statistical indicators of the quality of medical care in the UMMC dental polyclinic

The article describes the experience of using the NPS patient loyalty index. Net Promoter Score-the general loyalty index-is a 10-point scale assessment of the patient's willingness to recommend a clinic for treatment to relatives and friends. to assess patient satisfaction with the medical care provided.В статье рассмотрен опыт использования индекса потребительской лояльности пациентов по методике NPS. Net Promoter Score - общий индекс лояльности – это рассчитанная по 10-бальной шкале оценка готовности пациента рекомендовать клинику для лечения близким и друзья. для оценки удовлетворенности пациентов оказанной медицинской помощью

The Impact of Fission on R-Process Calculations

We have performed r-process calculations in neutron star mergers (NSM) and jets of magnetohydrodynamically driven (MHD) supernovae. In these very neutron-rich environments the fission model of heavy nuclei has an impact on the shape of the final abundance distribution and the second r-process peak in particular. We have studied the effect of different fission fragment mass distribution models in calculations of low-Ye ejecta, ranging from a simple parametrization to extensive statistical treatments (ABLA07). The r-process path ends when it reaches an area in the nuclear chart where fission dominates over further neutron captures. The position of this point is determined by the fission barriers and the neutron separation energies of the nuclei involved. As these values both depend on the choice of the nuclear mass model, so does the r-process path. Here we present calculations using the FRDM (Finite Range Droplet Model) and the ETFSI (Extended Thomas Fermi with Strutinsky Integral) mass model with the related TF and ETFSI fission barrier predictions. Utilizing sophisticated fission fragment distribution leads to a highly improved abundance distribution.Peer reviewe

Influence of anionic surfactant on stability of nanoparticles in aqueous solutions

Dispersion and aggregation of nanoparticles in aqueous solutions are important factors for safe and effective application of nanoparticles, for instance, in the oil industry. As conventional oil reserves are depleted, it is necessary to advance chemical enhanced oil recovery (cEOR) techniques to develop unconventional oil reservoirs. Nanoparticles modified by surfactants can be a promising reagent in cEOR. These nanomaterials can reduce interfacial tension and change the wettability of reservoir rock, which leads to an increase in oil recovery. However, the application of nanoparticles is limited by their substantial aggregation in aqueous solutions. The purpose of this work is to select nanoparticles for obtaining stable sols in water in the presence of an anionic surfactant and to optimize the conditions (pH) for further modifying the nanoparticles with the anionic surfactant. Sodium dodecyl sulfate (SDS) is used as an anionic surfactant. The aggregation of oxide and carbon nanoparticles in water and anionic surfactant solutions was studied by laser diffraction, dynamic and electrophoretic light scattering methods. Most of the studied nanoparticles in water form aggregates with bi-, three- and polymodal particle size distributions. TiO2 nanoparticles obtained by plasma dynamic synthesis form the most stable sols in anionic surfactant solutions. The range of 5–7 pH is defined as optimal for their modification with surfactants. The stability of carbon nanoparticles in aqueous solutions increases significantly in the presence of a surfactant. The obtained results form the basis for further research on the modification of marked nanoparticles in surfactant solutions

Routing of Displacement in Non-Stationary Radiation Fields with the Obstacle of Obstacles

The problem of routing of displacements with constraints and complicated cost functions is considered. The statement of the problem has limitations in the form of precedence conditions. A situation of this kind arises, in particular, in the liquidation of the consequences of radiation accidents at nuclear facilities. Under normal operation, the optimization of the movement route is relevant for performing instrumental measurements of radiation parameters by dosimeters at specified points in the NPP premises. In the presented research the approach to the decision of the given task by the parallel algorithm realized on the supercomputer URAN is stated.Рассмотрена задача маршрутизации перемещений с ограничениями и усложненными функциями стоимости. По постановке задачи имеются ограничения в виде условий предшествования. Ситуация такого рода возникает, в частности, при ликвидации последствий радиационных аварий на объектах использования атомной энергии. В условиях нормальной эксплуатации оптимизация маршрута перемещения актуальна для проведения инструментальных измерений радиационных параметров дозиметристами в заданных точках помещения АЭС. В представленном исследовании излагается подход к решению данной задачи параллельным алгоритмом, реализуемым на суперкомпьютере УРАН.Работа выполнена при поддержке гранта РФФИ № 17-08-0138

О ПЕРСПЕКТИВНЫХ НАПРАВЛЕНИЯХ СОЗДАНИЯ ГИДРАВЛИЧЕСКИХ АГРЕГАТОВ ПРИВОДОВ СТРОИТЕЛЬНЫХ И ДОРОЖНЫХ МАШИН

The paper presents the developed principle for volumetric division of operating fluid flow in  multi-motor hydraulic drive of working elements of construction and road machinery. Basic technical solutions and design parameters of discrete rotary-type  hydraulic distributive valve have been  determined in the paper.Разработан принцип объемного деления потока рабочей жидкости многомоторного гидропривода рабочих органов дорожно-строительных машин. Определены основные технические решения и конструктивные параметры дискретного гидрораспределителя роторного типа