Action of Pulse-Magnetic Fields on Liquid and Crystallizing Metal

Pulsed-magnetic fields are used for execution of a whole complex of technological processes: dividing, forming, assembling, welding and others. In all these technologies half-finished products from sheets, sections and tubes are used as billets. Action of magnetic fields on a cast metal is known in the metallurgy production, for example, casting to an electromagnetic crystallizer. In spite of a high electrical resistance of a melt and owing to low mechanical resistance of a liquid metal the use of high-intensity pulse-magnetic fields (PMF) in technologies of mechanical engineering is of interest. Even the first exploration experiment showed high efficiency of such action. At energy of 1, 2 kJ a portion of the melt under the action of the PMF has flown more than 4 m, spread in the form of a thin film on the ceiling and solidified. The paper presents three basic technological schemes of such action: with influence through a wall of a magneto-transparent crucible; by an immersion inductor; and action from the surface. Factors accompanying such action are: added sources of heat as a result of flowing of induced eddy currents through the melt; force action on the melt responsible for passage of waves of stress and metal flows. Action of these factors is controllable both in intensity and in direction. The temporal action of the pulse-magnetic field on a liquid and crystallizing metal (LCM) is to be matched with a curve of cooling the melt: either on the portion above the crystallization area or on its different portions, that is, at different relationships of solid and liquid phases.Factors of action of the pulse-magnetic field change temperature conditions of crystallization influence on the number of centers of crystallization and, as the consequence, change structure and properties of cast metal. The paper presents results of first studies on action of the pulse-magnetic field on a LCM which testify that such action is real and good. This has determined the prospects for development of new technologies in metallurgy (forming of an ingots structure, stirring of a material, rolling of cast metal and so on) and in mechanical engineering (in casting, stamping, welding and others)

Определение параметра интенсивности отрыва коробочек льна при работе очесывающего устройства

Flax harvesting consists of serial technological processes: pulling, separation of seed bolls from stalks, stalks spreading out, turning during a rest, picking up of them and baling in large packages, loading, and transportation. One of the most important operations is seed balls separation from stalks. Determination of parameter of intensity of flex balls combing by deseeder operation is a little studied. Parameter of intensity of a separation doesn't show clearly its dependence on design features and an operating mode of the unit. The authors considered this relation by the example of the comb deseeder which has different tines on a ridge with accidentally decreasing spacing towards the end. The existing deseeders do not provide qualitative combings of flax stalks. Therefore, theoretical and pilot researches of the ridge comb deseeder were conducted. The program and a technique of researches of the comb deseeder were developed. The theoretical basics of intensity of combing by the comb deseeder are covered. The various factors influence damageability of stalks: geometrical parameters of tines, number of at the same time operating combs, sequence of combing, ratio of tines speeds and gripping conveyor. Characteristics of a combed layer, a flax maturing level, the weight-average values of efficiency of single influence belong to the factors influencing intensity of combing. In the flax harvesters LK-4A and LKV-4A with increase in frequency of the comb deseeder to 2.87 rpm and speeds of the gripping conveyor from 1.54 to 1.58 meter per second the intensity decreased up to 3.02 tine per centimeter, and combing purity increased up to 98 percent. So, intensity 3.02 tine per centimeter should be considered as minimum admissible, and combing purity should be increased no more than by 2 percent.Уборка льна состоит из ряда последовательных технологических процессов: теребления, отделения семенных коробочек от стеблей, расстила стеблей, оборачивания стеблей во время вылежки, подбора их и прессования в крупные упаковки, погрузка и транспортирование паковок. Особое место среди перечисленных выше операций, в значительной мере определяющих качество получаемой продукции, занимает отделение семенных коробочек от стеблей. Определение параметра интенсивности отрыва коробочек льна при работе очесывающего устройства мало изучено. Параметр интенсивности отрыва не показывает в явном виде его зависимость от конструктивных особенностей и режима работы очесывающего устройства. Рассмотрели эту связь на примере гребневого очесывающего аппарата, у которого зубья на гребне различные, со случайно уменьшающимся шагом от начала к концу. Существующие очесывающие аппараты не обеспечивают качественного очеса стеблей льна. Поэтому проведены теоретические и экспериментальные исследования гребневого очесывающего аппарата. Разработаны программа и методика исследований очесывающего аппарата. Рассмотрены теоретические основы интенсивности очеса гребневым очесывающим аппаратом. Определены факторы, влияющие на повреждаемость стеблей: геометрические параметры зубьев, число одновременно работающих гребней, последовательность очеса, соотношение скоростей зубьев и зажимного транспортера. К факторам, влияющим на интенсивность очеса, относятся характеристики очесываемого слоя, степень созревания льна, средневзвешенные значения эффективности одиночного воздействия. В льноуборочных комбайнах ЛК-4А и ЛКВ-4А с повышением частоты очесывающего аппарата до 2,87 об/мин и скорости зажимного транспортера от 1,54 до 1,58 м/с интенсивность снизилась до 3,02 зуб./см, а чистота очеса повысилась до 98 процентов. На основании этого следует считать интенсивность 3,02 зуб./см как минимально допустимую, и чистота очеса может быть повышена не более чем на 2 процента

Energy Density in Expanding Universes as Seen by Unruh's Detector

We consider the response of an Unruh detector to scalar fields in an expanding space-time. When combining transition elements of the scalar field Hamiltonian with the interaction operator of detector and field, one finds at second order in time-dependent perturbation theory a transition amplitude, which actually dominates in the ultraviolet over the first order contribution. In particular, the detector response faithfully reproduces the particle number implied by the stress-energy of a minimally coupled scalar field, which is inversely proportional to the energy of a scalar mode. This finding disagrees with the contention that in de Sitter space, the response of the detector drops exponentially with particle energy and therefore indicates a thermal spectrum.Comment: 15 pages, 1 figur

Manifestation of the Arnol'd Diffusion in Quantum Systems

We study an analog of the classical Arnol'd diffusion in a quantum system of two coupled non-linear oscillators one of which is governed by an external periodic force with two frequencies. In the classical model this very weak diffusion happens in a narrow stochastic layer along the coupling resonance, and leads to an increase of total energy of the system. We show that the quantum dynamics of wave packets mimics, up to some extent, global properties of the classical Arnol'd diffusion. This specific diffusion represents a new type of quantum dynamics, and may be observed, for example, in 2D semiconductor structures (quantum billiards) perturbed by time-periodic external fields.Comment: RevTex, 4 pages including 7 ps-figures, corrected forma

Monitoring of the content of manganese in soils and agricultural plants of the central Chernozem Region of Russia

The paper deals with the analysis of long-term observations of the manganese distribution in the soils of the south-western part of the Central Chernozem region of Russia in the Belgorod regio

Conformally invariant wave-equations and massless fields in de Sitter spacetime

Conformally invariant wave equations in de Sitter space, for scalar and vector fields, are introduced in the present paper. Solutions of their wave equations and the related two-point functions, in the ambient space notation, have been calculated. The ``Hilbert'' space structure and the field operator, in terms of coordinate independent de Sitter plane waves, have been defined. The construction of the paper is based on the analyticity in the complexified pseudo-Riemanian manifold, presented first by Bros et al.. Minkowskian limits of these functions are analyzed. The relation between the ambient space notation and the intrinsic coordinates is then studied in the final stage.Comment: 21 pages, LaTeX, some details adde

Large-order Perturbation Theory and de Sitter/Anti de Sitter Effective Actions

We analyze the large-order behavior of the perturbative weak-field expansion of the effective Lagrangian density of a massive scalar in de Sitter and anti de Sitter space, and show that this perturbative information is not sufficient to describe the non-perturbative behavior of these theories, in contrast to the analogous situation for the Euler-Heisenberg effective Lagrangian density for charged scalars in constant electric and magnetic background fields. For example, in even dimensional de Sitter space there is particle production, but the effective Lagrangian density is nevertheless real, even though its weak-field expansion is a divergent non-alternating series whose formal imaginary part corresponds to the correct particle production rate. This apparent puzzle is resolved by considering the full non-perturbative structure of the relevant Feynman propagators, and cannot be resolved solely from the perturbative expansion.Comment: 18 page

Diffusive Ionization of Relativistic Hydrogen-Like Atom

Stochastic ionization of highly excited relativistic hydrogenlike atom in the monochromatic field is investigated. A theoretical analisis of chaotic dynamics of the relativistic electron based on Chirikov criterion is given for the cases of one- and three-dimensional atoms. Critical value of the external field is evaluated analitically. The diffusion coefficient and ionization time are calculated.Comment: 13 pages, latex, no figures, submitted to PR

Dynamical Stability and Quantum Chaos of Ions in a Linear Trap

The realization of a paradigm chaotic system, namely the harmonically driven oscillator, in the quantum domain using cold trapped ions driven by lasers is theoretically investigated. The simplest characteristics of regular and chaotic dynamics are calculated. The possibilities of experimental realization are discussed.Comment: 24 pages, 17 figures, submitted to Phys. Rev

Определение связи лент льнотресты со стлищем при подборе их пальцами подбирающего аппарата

The quality of flax products depends on the way of flax straw retting. Currently, the best and most widely used method of flax straw retting is way of dew retting. Flax stems are laid in a thin layer on the flax field where they were grown or on a clover or grass field. During the retting process, plants tend to grow through the flax swaths depending on the air temperature (starting from 18°C) and humidity (50­-60%). Therefore, the flax straw picking up process should be done with certain efforts, however, without damaging the stems. (Research purpose) To determine the bonding forces of the flax straw with the rettery (a flax field or a grass field). (Materials and methods) The authors have designed an instrument to measure and register the considered forces as well as a general mechanism of the flax straw picking up process, which operates in conjunction with the IP 264 (BS) measurement information system, and also developed a research methodology. This system is integrated with to a laptop with the pre-­installed «Testing» software. The system is adopted to use the MS Excel software to transfer data in MS Excel format for further plotting. (Results and discussion) It has been shown that the bonding forces of flax stems, their changing pattern, and the maximum value during the picking up process depend on the degree of penetration by grass plants into flax swaths and the grass plant density per square meter. (Conclusions) In process of picking up the grass-­penetrated swaths, they show weak strength characteristics for transportation and an increased tendency to break the continuity of their picking up. The values of the ratio of the translational speed of a pick-­up device and the rotary speed of a picking device fingertip can be greater than the value of the relative elongation at the point of pulling the swath away from the ground. The coefficient of strength to pick up the swaths from a clover rettery is higher than that of flax and grass retteries.Качество льнотресты во многом зависит от выбора способа получения тресты. В настоящее время лучшим и широко распространенным способом получения тресты считается росяная мочка. Стебли льна укладывают тонким слоем на лугу (стлище), на поле из­под клевера (клеверище) или на участке, где их выращивали (льнище). В процессе вылежки лента прорастает при температуре 18 градусов Цельсия и влажности воздуха 50­60 процентов. При ее подъеме необходимо приложить определенное усилие чтобы не повредить стебли. (Цель исследования) Определить величину сил связи стеблей тресты с льнищем или стлищем и коэффициенты сцепления стеблей. (Материалы и методы) Для регистрации и замера исследуемых сил, характера процесса подъема был создан прибор, который работал совместно с измерительной информационной системой ИП 264 (БС), а также разработана методика исследований. Данную систему подключили к мобильному компьютеру с установленным в нем программным обеспечением «Испытания». Одна из особенностей программы – возможность передачи данных в формате MS Excel для дальнейшего построения графиков. (Результаты и обсуждение) Показали, что характер изменения сил связи стеблей в процессе их подъема, а также величина максимальной силы связи зависят от степени прорастания лент травой и густоты травостоя. (Выводы) При подъеме проросшей ленты склонность к разрыву непрерывности ее поступления увеличивается и проявляется при таких значениях соотношения поступательной скорости подборщика и окружной скорости конца пальца подбирающего аппарата, когда относительное удлинение ленты при подъеме на пальцах больше величины относительного удлинения в месте отрыва ее от земли, а коэффициент сопротивления отрыву лент, разостланных на клеверище, больше коэффициента сопротивления отрыву лент, разостланных на льнище и лугу