EGAM Induced by Energetic-electrons and Nonlinear Interactions among EGAM, BAEs and Tearing Modes in a Toroidal Plasma

In this letter, it is reported that the first experimental results are associated with the GAM induced by energetic electrons (eEGAM) in HL-2A Ohmic plasma. The energetic-electrons are generated by parallel electric fields during magnetic reconnection associated with tearing mode (TM). The eEGAM localizes in the core plasma, i.e. in the vicinity of q=2 surface, and is very different from one excited by the drift-wave turbulence in the edge plasma. The analysis indicated that the eEGAM is provided with the magnetic components, whose intensities depend on the poloidal angles, and its mode numbers are jm/nj=2/0. Further, there exist intense nonlinear interactions among eEGAM, BAEs and strong tearing modes (TMs). These new findings shed light on the underlying physics mechanism for the excitation of the low frequency (LF) Alfv\'enic and acoustic uctuations.Comment: 5 pages,4 figure

ВЛИЯНИЕ РЕАЛИЗАЦИИ СКОРОСТНОГО ГРУЗОВОГО ДВИЖЕНИЯ НА ТЕПЛОВЫЕ НАГРУЖЕНИЯ ЦКК ПРИ ТОРМОЖЕНИИ

Braking systems on modern freight cars act in a kind of tribological triangle: brake shoe – wheel – rail. Kinetic energy stored by the car during movement at braking due to friction is converted into heat, which is distributed between a brake shoe and a wheel. Numerous studies in recent years have proved that up to 60% heat is generated in the wheel when using iron shoes and up to 95% using composite shoes. During operation the material of the wheel is subjected to thermal impact, the intensity of which depends directly on braking modes and motion parameters of the rolling stock. Repetitive heating and cooling of wrought wheels have a significant effect on the kinetics of their stress-strain state.The kinetics of the stress-strain state in operation is determined by the scheme and the level of residual stresses, formed during heat treatment in the manufacture of wheels, as well as stresses and strains associated with mechanical and thermal loading. The level of residual technological stresses in the wheel with which it comes into operation, in some cases, is one of the main indicators of quality, reliability and durability. The combination of stress-strain state with residual technological stresses under adverse conditions, such as low temperature, presence of microdefect or local deviations in the formation of the microstructure can lead to formation of cracks in disc or brittle fracture of wheel that has been repeatedly confirmed by experts.The objective of the authors is to investigate impact of high speeds on wrought wheels, in particular in case of thermal loading: both heating and cooling. Methods and software developed in MIIT allow computer simulation of the kinetics of thermal, thermal deformation and deformation processes in nonlinear unsteady statement with account of kinetics of the structural state at each step of the solution, which allows to analyze the current state of the structural element using a wide range of technological and operational loadings throughout the life cycle.Continuing the theme of modeling of wrought wheels thermal loading, described in previous publications, the authors on the basis of the calculation and simulation methodology, developed with their participation in order to determine heat intensity in the system «wheel-brake shoe», clarify the features of influence of high speed of car’s movement along the rails on the values of maximum temperatures on the wheel surface during braking. The study confirmed theoretically grounded assumptions that increasing speeds significantly affect the value of the maximum temperature on the surface of wrought wheel at the time of the end of braking, as well as the complex of mechanical properties, kinetics of structures, conditions causing formation of cracks, metal chipping and other defects that endanger the operation of the rolling stock.Продолжая тему моделирования тепловых нагружений цельнокатаных железнодорожных колёс (см. «МТ», 2014, № 5), авторы статьи на основе созданной с их участием методики расчета интенсивности выделения тепла в системе «колесо–тормозная колодка» уточняют особенности влияния высоких скоростей движения вагона по рельсам на значения максимальных температур на поверхности колёс в процессе торможения. Во внимание берутся весь комплекс механических характеристик, кинетика структур, условия для образования трещин, выкрашивания металла и прочих дефектов, создающих угрозу эксплуатации подвижного состава

Финансовое и банковское взаимодействие России и Белоруссии: история и современность

В данной статье анализируются вехи развития банковской системы Белоруссии и России. Выделяются их взаимосвязи и общие признаки. А также обстоятельства, способствующие их сближению после распада СССР

МОДЕЛИРОВАНИЕ ТЕПЛОВЫХ НАГРУЖЕНИЙ ЦЕЛЬНОКАТАНЫХ КОЛЁС

Actually used diagnostic systems do not allow to evaluate fairly enough the background of loading of an object, to identify those states which are characterized by absence of a defect, but at the same time warn of a mature environment for its formation. That is, they do not provide a full assessment of risks and the residual operation life of an object. The main disadvantage is a fact that they do not permit to analyze the kinetics of transient processes related to operational or technological impact. The paper clarifies approaches to evaluation of kinetics of transient thermal processes in a running wrought wheel (the system «wheel-shoe») on the basis of original methodology established by authors and of the results of computer simulation.Применяемые ныне системы диагностики не позволяют достаточно объективно оценить предысторию нагружения объекта, выявить такие состояния, которые характеризуются отсутствием дефекта, но вместе с тем и предупреждают о наличии сформировавшихся условий для его образования. То есть не обеспечивают в полном объеме оценку рисков и остаточного ресурса объекта. Главным же недостатком является то, что они не позволяют проводить анализ кинетики нестационарных процессов, связанных с эксплуатационными или технологическими воздействиями. В статье уточняются подходы к оценке кинетики нестационарных тепловых процессов в цельнокатаном работающем колесе (система «колесо-колодка») на основе созданной авторами методики и результатов компьютерного моделирования

ТЕПЛОВЫЕ И ДЕФОРМАЦИОННЫЕ ПРОЦЕССЫ В ЦКК ПРИ ДЛИТЕЛЬНОМ ТОРМОЖЕНИИ

Railway wrought wheels (hereinafter- WW) belong to the most critical elements in the design of rolling stock, the reliability of which largely influences traffic safety. During operation, they are subjected to high thermal effects resulted from braking (system «brake shoe-wheel») and mechanical loading during the interaction of wheel and rail.Continuing previous publications in World of Transport and Transportation journal (Vol. 12, Iss. 5, pp. 22–37; Vol. 13, Iss. 1, pp. 56–62) the authors analyze the studies that were conducted at MIIT to assess the influence of braking parameters on the kinetics of thermal and deformation processes taking into account the geometry of the wheel disc. Modern technical means and methods do not allow for analysis of the distribution of thermal processes throughout the wheel volume during braking and implementation of direct measurements of deformation of WW elements at the end of the freight car braking.The objective of the authors was to present an analysis of the influence of the wheel disc geometry on maximum values of deformation of the rim at the end of extended braking. In the paper the authors use analysis, mathematical and engineering methods.The results were obtained by methodological tools, designed at MIIT, and a software complex SANAK, created on its basis. Computer modeling was carried out using volumetric finite element models of wrought wheels with a diameter of 950 mm with rectilinear and curvilinear shapes of the disc with the size specified in GOST 10791–2011 [1]. The features of interaction in the system «wheel-rail», and wheel wear during its operation were not taken into account (thickness of the rim was 70 mm).В продолжение публикаций об исследованиях ученых МИИТ, которые посвящены оценке влияния условий длительного торможения грузового вагона на кинетику тепловых и деформационных процессов в системе «тормозная колодка–колесо» («МТ», 2014, № 5, с. 22–37; 2015, № 1, с. 56–62), авторы знакомят с анализом влияния геометрии диска цельнокатаного колеса (ЦКК) на максимальные значения деформаций обода в момент окончания торможения. На основе полученных данных дается заключение о максимальном тепловложении именно в ободе ЦКК, оцениваются последствия смещений и перемещений элементов колеса в зависимости от конструкционных их особенностей и степени влияния на безопасность движения

Observation of suprathermal electrons during magnetic reconnection at the sawtooth instability in DIII-D TOKAMAK

OAK A271 Observation of suprathermal electrons during magnetic reconnection at the sawtooth instability in DIII-D TOKAMAK. Intense bursts of x-ray and electron cyclotron emission are observed during sawtooth instabilities in high-temperature plasmas in the DIII-D tokamak. The bursts are initiated around the X-point of the m = 1, n = 1 magnetic island at the beginning of the sawtooth crash and are displaced to larger radii later during the temperature collapse. Reconstruction of the magnetic configuration using motional Stark effect (MSE) data and numerical simulations indicates that the bursts can be connected with suprathermal electrons (E sub r approx 30-40 keV) generated during reconnection of the magnetic field around the q = 1 surface

Numerical simulation of feedback control of coupled tearing modes at JET

Available from British Library Document Supply Centre- DSC:4672.2625(JET-R--95/06) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo