Theoretical and experimental investigation of the destruction of graphites in a flow of dissociated air

A method is presented for calculating the heating and erosion of blunt bodies made of graphite in a high-enthalpy flow of dissociated air, assuming chemical equilibrium on the surface and taking account of the thermal effects of combustion and sublimation of graphite. The analysis involves the use of a finite difference scheme to solve an equation of unsteady heat conduction. Attention is given to the equilibrium vaporization of C, C2 and C3 molecules. The calculations agree well with experimental data for a wide range of temperatures and stagnation pressures

Sympathetic nervous system and neurotransmitters: Their possible role in neuroimmunomodulation of multiple sclerosis and some other autoimmune diseases

Multiple sclerosis is still a disease without a cure. Although intensive research efforts have led to the development of drugs that modify the activity of the disease, most of them have various side effects and are expensive. At the same time it is becoming apparent that some remedies usually used to treat somatic and psychic disorders also have immunomodulating properties, and may help manage multiple sclerosis and other autoimmune diseases. We describe here the role of the sympathetic nervous system in the neuro-immune interaction in multiple sclerosis and other immune diseases with increased cellular immunity as well as neurochemical disturbances that take place in these disorders. © Versita Warsaw and Springer-Verlag Berlin Heidelberg 2006

Analysis of optical magnetoelectric effect in GaFeO_3

We study the optical absorption spectra in a polar ferrimagnet GaFeO_3. We consider the E1, E2 and M1 processes on Fe atoms. It is shown that the magnetoelectric effect on the absorption spectra arises from the E1-M1 interference process through the hybridization between the 4p and 3d states in the noncentrosymmetry environment of Fe atoms. We perform a microscopic calculation of the spectra on a cluster model of FeO_6 consisting of an octahedron of O atoms and an Fe atom displaced from the center with reasonable values for Coulomb interaction and hybridization. We obtain the magnetoelectric spectra, which depend on the direction of magnetization, as a function of photon energy in the optical region 1.0-2.5 eV, in agreement with the experiment.Comment: 18 pages, 5 figure

Effect of Stress on Irradiation-induced Creep and Swelling of Fe-18Cr-10Ni-Ti Steel Pressurized Specimens Irradiated in the BOR-60 Reactor

The paper presents the data on the effect of stress of various signs on the irradiationinduced creep strain and swelling of austenitic Fe-18Cr-10Ni-Ti steel pressurized specimens. The pressurized specimens of standard and contoured geometry were irradiated in the BOR-60 reactor up to the damage dose of 90 and 36 dpa, accordingly,under various stress levels applied. Presented are the data resulted from TEM investigations of pressurized specimens performed with the use of the transmission electron microscope

Методология проектирования объектов дорожного сервиса автомобилей

In modern methods of technological design, the capacity of service facilities depends on the number of cars entering them per unit of time. At the same time, regardless of the type of service object, the number of visits is somehow associated with intensity of the vehicle traffic on a given road, as well as with one of the characteristics that determine speed of this event. Such a characteristic, for example, for service or maintenance stations is intensity of vehicle failures, for fuelling stations – intensity of fuel consumption, for hotels and parking lots – intensity of the onset of fatigue for drivers and passengers. This gives ground for conclusion that there is a significant similarity between the processes that result in an event that can be called a visit to a service facility. Thus, the purpose of this theoretical study was to develop a common approach applicable to all road service facilities to determine the number of such events, as well as to develop a common methodology for their design.A characteristic feature of operation of service objects is a time-varying flow of demand for the operation of service facilities, as well as variable labour intensity and duration of troubleshooting or the provision of other service services. Systems in which the moments of receipt of requests for service and the duration of the services themselves are variable and random are called a queuing system. Therefore, to justify the number of car arrivals at road service facilities, the authors proposed a probabilistic method, the main tools of which are provisions and mathematical apparatus of the queuing theory.The main condition for functioning of the queuing system is the ratio between the incoming flow of requirements and the absolute throughput of the system. Thus, the mathematical model proposed by the authors considers the performance indicators of service facilities, depending on the size of the incoming flow of requirements and its variation, on the one hand, and on the throughput and performance of service facilities, on the other hand.В современных методиках технологического проектирования мощность объектов сервиса зависит от числа заездов на них автомобилей в единицу времени. При этом независимо от вида объекта сервиса число заездов так или иначе связывают с интенсивностью их движения на данной дороге, а также с одной из характеристик, определяющих скорость наступления данного события. Такой характеристикой, например, для СТО, является интенсивность отказов автомобилей, для АЗС – интенсивность расходования топлива, для гостиниц и стоянок – интенсивность наступления утомления водителей и пассажиров. Это позволяет сделать заключение о существенном сходстве процессов, в результате которых возникает событие, именуемое заездом. Таким образом, целью данного теоретического исследования являлась разработка единого для всех объектов дорожного сервиса подхода к определению числа таких событий, а также общей методологии их проектирования.Характерной особенностью работы объектов сервиса является изменяющийся во времени поток требований на работу средств обслуживания, а также переменные трудоёмкость и продолжительность устранения неисправностей или предоставление других услуг сервиса. Системы, в которых переменными и случайными являются моменты поступления требований на обслуживание и продолжительность самих обслуживаний, называют системой массового обслуживания. Поэтому авторами для обоснования числа заездов автомобилей на объекты дорожного сервиса предложен вероятностный метод, основным инструментом которого являются положения и математический аппарат теории массового обслуживания.Основным условием функционирования системы массового обслуживания является соотношение между входящим потоком требований и абсолютной пропускной способностью системы. Таким образом, математическая модель, предложенная авторами, рассматривает показатели эффективности средств обслуживания в зависимости с одной стороны от величины входящего потока требований и его вариации, а с другой – от пропускной способности и производительности средств обслуживания

Redistribution of sediment and sediment-associated contaminants in the River Chern basin during the last 50 years

A detailed study was undertaken in the upper part of the River Chern basin (126 km2). An integrated approach was used to investigate the redistribution of sediment and sediment-associated contaminants within the upper part of the basin, upstream from the reservoir located in the middle reach of the main valley. It was found that maximum sheet, rill and gully erosion rates were observed during the 1960s. This led to increased erosion rates in all parts of the fluvial system. The intensity of erosion decreased considerably after 1991 for a number of reasons. The commencement of mining activity and the sharp increase in the application of chemical fertilizers caused detectable heavy metal pollution within the basin during the late 1950s and early 1960s, when the Mikhailovsky iron ore mining development started. As a result, concentrations of Zn and As in floodplain sediment increased and exceeded the maximum permissible levels, according to Russian human health standards. Copyright © 2012 IAHS Press

Effects of land use and climate changes on small reservoir siltation in the agricultural belt of European Russia

Small reservoirs of agriculture-dominated areas experience severely increased sediment input caused by soil erosion on cultivated slopes, also accompanied at some locations by gully erosion. This causes rapid decrease of the reservoir water storage and shortened periods of functioning. In this paper we discuss several examples of the 137Cs-based short-term siltation chronology of small reservoirs located in different landscape zones within the agricultural belt of European Russia. From two to four time marks could have been established in 137Cs depth distribution curves constructed from detailed depth-incremental sampling of reservoir infill sediment, allowing reconstruction of sediment microstratigraphy and deposition rates. In combination with other independent information sources this provides insight on the relative importance of recent land use changes and climatic variability in controlling sediment delivery within small agriculture-dominated fluvial systems. In combination with sediment redistribution studies, it has become possible to construct closed sediment budgets for catchments of several reservoirs and make a quantitative assessment of sediment delivery variability. Such information is important for appropriate design and management of small agricultural reservoirs in Russia. Copyright © 2013 IAHS Press

Using Chernobyl-derived 137Cs to document recent sediment deposition rates on the River Plava floodplain (Central European Russia)

Floodplain sedimentation is one of the most dynamic geomorphic processes within plain and lowland landscapes. There is generally a good understanding of longer term floodplain evolution, but quantitative information on overbank deposition rates for recent shorter timescales is lacking. This paper describes the application of Chernobyl-derived 137Cs to quantify floodplain aggradation rates for the River Plava (a small river draining a severely contaminated part of the upland region of Central European Russia), based on detailed sampling of four representative floodplain study sites. Two approaches have been employed for estimating post-Chernobyl (1986-2009) floodplain accumulation rates. The first was based simply on locating the Chernobyl fallout-associated 137Cs peak in overbank sediment sections. The second involved quantification of the increase in the total 137Cs inventory at individual sampling points associated with the post-Chernobyl deposition of contaminated suspended sediment. It has been shown that considerable local-scale variability of overbank deposition rates exists, with aggradation rates on the low level floodplain (6±1.2-14±2.8 mm year-1) exceeding by 1.5-3 times the values for the middle level floodplain (2±0.4-9±1.8 mm year-1) and by 3-6 times the values for the upper level floodplain (1±0.2-5±1.0 mm year-1) floodplain levels. Combining these estimates with information on the areas occupied by different floodplain levels within the 54 km long valley section, derived from detailed geomorphic surveys of the selected reaches, it has been estimated that about 9700±1950 t of sediment have been stored on floodplain during the 1986-2009 period. The role of floodplain storage in the overall basin sediment budget and conveyance losses within the main channel system have been evaluated. © 2012 John Wiley & Sons, Ltd