Microstructure and crystallographic texture of silicon iron modified by torsion under quasihydrostatic pressure

The electron backscatter diffraction, X-ray diffraction analysis, electromotive force instantaneous measurement, microhardness and coercive force measurement techniques are used to explore the development of the microstructure, crystallographic texture and physico-mechanical properties of silicon iron (Fe-3% Si) alloy under quasi-hydrostatic pressure in a Bridgman anvil. It is found that the alloy deformation is accompanied by its significant hardenin

Enhancement of field generation via maximal atomic coherence prepared by fast adiabatic passage in Rb vapor

We have experimentally demonstrated the enhancement of coherent Raman scattering in Rb atomic vapor by exciting atomic coherence with fractional stimulated Raman adiabatic passage. Experimental results are in good agreement with numerical simulations. The results support the possibility of increasing the sensitivity of CARS by preparing atomic or molecular coherence using short pulses

Buffer-gas induced absorption resonances in Rb vapor

We observe transformation of the electromagnetically induced transparency (EIT) resonance into the absorption resonance in a $\Lambda$ interaction configuration in a cell filled with $^{87}$Rb and a buffer gas. This transformation occurs as a one-photon detuning of the coupling fields is varied from the atomic transition. No such absorption resonance is found in the absence of a buffer gas. The width of the absorption resonance is several times smaller than the width of the EIT resonance, and the changes of absorption near these resonances are about the same. Similar absorption resonances are detected in the Hanle configuration in a buffered cell.Comment: 11 pages, 15 figures; 13 pages, 17 figures, added numerical simulatio

Ultralow-power local laser control of the dimer density in alkali-metal vapors through photodesorption

Ultralow-power diode-laser radiation is employed to induce photodesorption of cesium from a partially transparent thin-film cesium adsorbate on a solid surface. Using resonant Raman spectroscopy, we demonstrate that this photodesorption process enables an accurate local optical control of the density of dimer molecules in alkali-metal vapors.Comment: 4 pages, 4 figure

Phenomenological description of the gamma* p cross section at low Q2

Low Q2 photon-proton cross sections are analysed using a simple, QCD-motivated parametrisation $\sigma_{\gamma^\star p}\propto 1/(Q^2+Q_0^2)$, which gives a good description of the data. The Q2 dependence of the gamma* p cross section is discussed in terms of the partonic transverse momenta of the hadronic state the photon fluctuates into.Comment: 14 pages, revtex, epsfig, 2 figure

Explanation of the Gibbs paradox within the framework of quantum thermodynamics

The issue of the Gibbs paradox is that when considering mixing of two gases within classical thermodynamics, the entropy of mixing appears to be a discontinuous function of the difference between the gases: it is finite for whatever small difference, but vanishes for identical gases. The resolution offered in the literature, with help of quantum mixing entropy, was later shown to be unsatisfactory precisely where it sought to resolve the paradox. Macroscopic thermodynamics, classical or quantum, is unsuitable for explaining the paradox, since it does not deal explicitly with the difference between the gases. The proper approach employs quantum thermodynamics, which deals with finite quantum systems coupled to a large bath and a macroscopic work source. Within quantum thermodynamics, entropy generally looses its dominant place and the target of the paradox is naturally shifted to the decrease of the maximally available work before and after mixing (mixing ergotropy). In contrast to entropy this is an unambiguous quantity. For almost identical gases the mixing ergotropy continuously goes to zero, thus resolving the paradox. In this approach the concept of ``difference between the gases'' gets a clear operational meaning related to the possibilities of controlling the involved quantum states. Difficulties which prevent resolutions of the paradox in its entropic formulation do not arise here. The mixing ergotropy has several counter-intuitive features. It can increase when less precise operations are allowed. In the quantum situation (in contrast to the classical one) the mixing ergotropy can also increase when decreasing the degree of mixing between the gases, or when decreasing their distinguishability. These points go against a direct association of physical irreversibility with lack of information.Comment: Published version. New title. 17 pages Revte

Определение коэффициентов трения стеблей льна по характеристикам шероховатости

When harvesting flax, its stems get into contact with the working elements of flax harvesting machines. The authors have found that the diversity of materials used to manufacture the working elements made it necessary to calculate the friction coefficients in the interaction between the stems and these materials, since it is not always possible to do this experimentally. They confirmed the possibility of calculating the friction coefficients in the butt, middle and apical parts of the stem. Research purpose Calculation of the friction coefficients of flax stems according to the given microgeometry characteristics of their surface.Materials and methods The studies were carried out on a standard device, a profile meter-and-recorder made by the Kalibr plant, make 201. Common (fibre) flax of the Mogilevskiy 2 variety at the stage of brown ripeness, at a humidity - 43.79 percent, with total length of stems – 78, 9 cm and a flax straw yield of 3.575 tons per hectare were chosen for the experiments. The flax crop was harvested by hand on the experimental field during the harvesting period. During the preparation of experimental samples, the flax stem was divided into three parts - butt, middle and apical. Each of the stem parts was divided into two halves along the axis, then one of the halves was unrolled and pasted on a solid base (steel plate). Profile diagrams of flax stems parts of were processed with conventional methods.Results and discussion The authors have obtained the friction coefficients of the stems of different humidity as they moved along the steel surface. It has been established that the calculated values of the friction coefficients are slightly higher than those obtained as a result of experiments. (Conclusions) It has been established that as the humidity of flax stems increases, the molecular component of the friction coefficient increases too. It has been determined that when the moisture content of the stems is 20-45 percent, the friction coefficient values range from 0.38 to 0.98 percent.При уборке льна-долгунца его стебли контактируют с рабочими органами льноуборочных машин. Выявили, что многообразие материалов для изготовления рабочих органов вызвало необходимость рассчитать коэффициенты трения при взаимодействии стеблей с этими материалами, так как сделать это опытным путем не всегда представляется возможным. Подтвердили возможность вычисления коэффициентов трения в комлевой, средней и верхушечной частях стебля.Цель исследования Рассчитать коэффициенты трения стеблей льна-долгунца по заданным характеристикам микрогеометрии их поверхности.Материалы и методы Исследования проводили на стандартном приборе профилограф-профилометр завода «Калибр», модель 201. В качестве исследуемого материала использовали лен-долгунец сорта Могилевский 2 в фазе бурой спелости, (влажность – 43,79 процента, общая длина стеблей – 78,9 сантиметра, урожайность льносоломы – 3,575 тонны с гектара). Растения льна-долгунца вытеребливали вручную на опытном поле в период уборки. В ходе подготовки опытных образцов стебель льна делили на три части – комлевую, среднюю и верхушечную. Каждую из частей стебля разделяли на две половины вдоль оси, затем одну из половин разворачивали и наклеивали на твердое основание (стальную пластину). Профилограммы частей стеблей льна обрабатывали по известным методикам.Результаты и обсуждение Получили коэффициенты трения стеблей разной влажности при их перемещении по стальной поверхности. Установили, что расчетные значения коэффициентов трения несколько превышают показатели, полученные в результате опыта.Выводы Установили, что с повышением влажности стеблей льна возрастает молекулярная составляющая коэффициента трения. Определили, что при влажности стеблей 20-45 процентов коэффициент трения колеблется в пределах от 0,38 до 0,98 процента

Исследования параметров и режимов работы аппарата для очеса льна на корню

The authors showed that the main technological process in the combined and separate methods of fiber flax harvesting is deseeding or separating the seed part of the crop from the stems. It was confirmed that there is a direct impact of this process success on seed and straw losses, the fiber yield and quality, the heap composition, the labor intensity and energy consumption of flax drying and processing. (Research purpose) To develop a technology for stripping fiber flax with a comb deseeder during harvesting, to study the deseeder’s specifications and operating modes. (Materials and methods) The authors studied the technological process of stripping flax with a comb deseeder. An experimental plant of a comb deseeder was designed. A model of theoretical calculation was proposed based on the physical and mechanical properties of fiber flax and agrotechnical requirements for its harvesting. (Results and discussion) The authors theoretically determined the comb deseeder’s optimal height, operation kinematic mode, stripping cleanliness, the radius of the stripper drum. Laboratory studies were conducted. It was shown that threshing seeds in the field will reduce the loss of flax seeds by 10 per cent and the stem waste due to tangling during the harvesting process – by 18 per cent. It will also reduce the number of harvesting vehicles, personnel, and the cost of product. The authors identified an opportunity to increase productivity by increasing the width of the header grip: for example, the width of a grain harvester header is about 4 meters, and the width of a flax harvester header is 1.52 meters, that is, the productivity of flax harvesting will increase 2.6 times at the same speed, and 3 times at a higher speed. It was possible to eliminate one piece of equipment – a heap separating machine, since the technological operation of heap processing is carried out by a grain harvester. (Conclusions) The authors presented a theoretical substantiation of the comb deseeder’s operating parameters and modes for stripping fiber flax in the field. The authors proposed a model to determine them based on the physical and mechanical properties of flax and agrotechnical requirements for its harvesting.Показали, что основной технологический процесс в комбайновом и раздельном способах уборки льна-долгунца – отделение семенной части урожая от стеблей. Подтвердили, что от его совершенства зависят потери семян и соломы, выход и качество волокна, состав вороха, трудоемкость и энергоемкость его сушки и переработки. (Цель исследования) Разработать технологию очеса льна-долгунца на корню очесывающим устройством, изучить его параметры и режимы работы. (Материалы и методы) Исследовали технологический процесс очеса льна на корню очесывающим устройством. Разработали экспериментальную установку очесывающего аппарата. Предложили модель теоретического расчета исходя из физико-механических свойств льна-долгунца и агротехнических требований для его уборки. (Результаты и обсуждение) Теоретически определили: оптимальную высоту, кинематический режим работы, чистоту очеса, радиус барабана очесывающего устройства, провели лабораторные исследования. Показали, что обмолот семян в поле позволит снизить потери семян льна на 10 процентов и отход стеблей в путанину в процессе уборки – на 18 процентов, сократить количество уборочной техники, численность персонала, уменьшить себестоимость продукта. Выявили возможность повысить производительность путем увеличения ширины захвата жатки: например, ширина захвата жатки зернового комбайна около 4 метров, а льноуборочного – 1,52 метра, то есть производительность уборки льна увеличится при одной и той же скорости в 2,6 раза, а на более высокой скорости – в 3 раза. Сократили одну единицу техники – ворохоразделовательную машину, поскольку технологическую операцию по переработке вороха осуществляет зерновой комбайн. (Выводы) Представили теоретическое обоснование параметров и режимов работы очесывающего аппарата для очеса льна-долгунца на корню. Предложили модель их определения на основе физико-механических свойств льна и агротехнических требований для его уборки.