СИЛОВЫЕ УСЛОВИЯ ПРЕССОВАНИЯ ЛЕГКОСПЛАВНЫХ БУРИЛЬНЫХ ТРУБ СО СПИРАЛЬНЫМ ОРЕБРЕНИЕМ

Following I.L. Perlin’s technique based on active and reactive forces balance, the formula was suggested to calculate extrusion force for spiral-finned drill pipes. The spiral pipe cross section was regarded as a smooth tube with a screw arrangement of metal fibers and external spiral fins. A component introducing energy spent for the screw motion of metal was added to the formula. It was shown that the extrusion force obtained by the modified formula is 28 % higher than the same for a smooth pipe of equal area. It was discovered that the increase of fin helix angle leads to the increase of force compared to that of longitudinally finned pipes. На основе методики И.Л. Перлина, основанной на балансе активных и реактивных сил, предложено уравнение для расчета усилия прессования бурильных труб со спиральным оребрением. Поперечное сечение спиральной трубы представлено в виде гладкой трубы с винтовым расположением волокон металла и внешних спиральных ребер. В формулу добавлена составляющая, учитывающая энергию, затрачиваемую на винтовое движение металла. Показано, что усилие прессования, полученное по модернизированной формуле, на 28 % больше, чем для равновеликой по площади гладкой трубы. Выявлено, что увеличение угла подъема спирали ребер приводит к росту усилия по сравнению с таковым для продольно-оребренных труб.

РАСПРЕДЕЛЕНИЕ КОНТАКТНЫХ НАПРЯЖЕНИЙ В ПРОЦЕССЕ ВОЛОЧЕНИЯ КРУГЛЫХ ИЗДЕЛИЙ

The computer simulation of contact stresses in the course of round product drawing through conical draw dies has been carried out by the finite element method with the DEFORM-2D particularized bundled software.Приведены результаты компьютерного моделирования контактных напряжений при волочении круглых изделий в конические волоки с помощью метода конечных элементов в специализированном программном комплексе DEFORM-2D

Analysis of a nanofilm of the mercaptophenyl diazonium modified gold electrode within new statistical parameters

The main aim of this study is to characterize the nanosurface of the mercaptophenyl diazonium modified gold (Au) surface by a new statistical approach. In this study the gold electrode surfaces were self-assembled in ethyl alcohol by 1.0 mM mercaptophenyl diazonium. FT-IR spectra of the surface modifier molecules in both solid and nanofilm of mercaptophenyl diazonium (MCP-Au) forms were recorded in the spectral range of 600-4,000 cm-1. The FT-IR spectra of solid mercaptophenyl diazonium tetrafluoroborate salt were obtained by using KBr pellets. The above FT-IR spectra of both bare Au and its nanofilm of mercaptophenyl diazonium were processed by new statistical approach to reach optimal smoothing trend for the characterization of the modified electrode surface consisting of the nanofilm of gold-mercaptophenyl diazonium. In the frame of new statistical approach all measured spectra have been 'read' in terms of a set of universal statistical parameters. These new parameters help to establish the statistical proximity of the smoothed spectra compared and give a possibility to classify the measured spectra in accordance with new set of statistical and robust quantitative values. Besides, there is a possibility to receive the relative fluctuations and the smoothed spectra of the second order. So, thanks to new approach we do not loose any measured information: the smoothed spectra and accompanied them noise (relative fluctuations) can be analyzed separately for detection of possible influence of predominant external factors that can be essential for this type of measurements. Copyright © 2010 American Scientific Publishers All rights reserved

Amino-nitrile cleavage in the electrochemical reduction of hydeazones of aromatic aldehydes

1. Factors which determine the possibility of amino-nitrile cleavage of hydrazones on electrochemical reduction (ECR) include the basicity of the anionic product formed in the course of the ECR and the mobility of the aldehyde hydrogen which depends on the character of the electron polarization of the hydrazone fragment and the polarity of the N-N bond. 2. The primary action in amino-nitrile cleavage under conditions of ECR is the deprotonation of the azomethine fragment in the unreduced molecule by electrochemically generated strong base (anion or dianion). © 1988 Plenum Publishing Corporation

Rates of convergence for empirical spectral measures: a soft approach

Understanding the limiting behavior of eigenvalues of random matrices is the central problem of random matrix theory. Classical limit results are known for many models, and there has been significant recent progress in obtaining more quantitative, non-asymptotic results. In this paper, we describe a systematic approach to bounding rates of convergence and proving tail inequalities for the empirical spectral measures of a wide variety of random matrix ensembles. We illustrate the approach by proving asymptotically almost sure rates of convergence of the empirical spectral measure in the following ensembles: Wigner matrices, Wishart matrices, Haar-distributed matrices from the compact classical groups, powers of Haar matrices, randomized sums and random compressions of Hermitian matrices, a random matrix model for the Hamiltonians of quantum spin glasses, and finally the complex Ginibre ensemble. Many of the results appeared previously and are being collected and described here as illustrations of the general method; however, some details (particularly in the Wigner and Wishart cases) are new. Our approach makes use of techniques from probability in Banach spaces, in particular concentration of measure and bounds for suprema of stochastic processes, in combination with more classical tools from matrix analysis, approximation theory, and Fourier analysis. It is highly flexible, as evidenced by the broad list of examples. It is moreover based largely on "soft" methods, and involves little hard analysis

MELT INCLUSIONS IN OLIVINE AS A SOURCE OF INFORMATION ON THE COMPOSITION AND EVOLUTION OF DEEP MELTS OF AILLIKITES (ULTRAMAFIC LAMPROPHYRES) OF THE ILBOKICHI UPLIFT, THE SW SIBERIAN PLATFORM

Aillikites are kimberlite-like rocks, important for understanding the composition and processes occurring in the mantle. Melt inclusions represent a reliable source of information. The paper provides the first results of studies (Raman, EDS) on primary and secondary melt inclusions in olivine from the Ilbokich uplift aillikites. The composition of primary inclusions is close to that of parent melt of aillikites. It was significantly enriched in CO2, H2O, phosphorus and titanium. Phlogopite, diopside, dolomite, calcite, apatite, Ti-containing phases (brookite, perovskite, Ti-magnetite) and lizardite were identified in these inclusions. The similarity of the composition and ratios of the daughter phases with the aillikite matrix indicates a slight change in the parent melt when it is rising to the surface. As to the secondary inclusions, there are wide variations in compositions and a smaller amount of silicates, as compared to the primary ones. The main daughter phases are carbonates, e.g. dolomite, calcite, magnesite and alkaline carbonates. In addition, phlogopite, clinopyroxene, apatite, halite, pyrrhotite and magnetite, graphite and CO2 were discovered. The variability of the compositions of the secondary inclusions might be due to the silicate-carbonate immiscibility that appeared during the rising of the aillikite melt at pressures <4 GPa

Photoelectron circular dichroism of O 1ss-photoelectrons of uniaxially oriented trifluoromethyloxirane: Energy dependence and sensitivity to molecular configuration

The photoelectron circular dichroism (PECD) of the O 1s-photoelectrons of trifluoromethyloxirane(TFMOx) is studied experimentally and theoretically for different photoelectron kinetic energies. The experiments were performed employing circularly polarized synchrotron radiation and coincidentelectron and fragment ion detection using Cold Target Recoil Ion Momentum Spectroscopy. The corresponding calculations were performed by means of the Single Center method within the relaxed-core Hartree-Fock approximation. We concentrate on the energy dependence of the differential PECD of uniaxially oriented TFMOx molecules, which is accessible through the employed coincident detection. We also compare results for differential PECD of TFMOx to those obtained for the equivalent fragmentation channel and similar photoelectron kinetic energy of methyloxirane (MOx), studied in our previous work. Thereby, we investigate the influence of the substitution of the methyl-group by the trifluoromethyl-group at the chiral center on the molecular chiral response. Finally, the presently obtained angular distribution parameters are compared to those available in literature.Comment: 6 fig

ТЕХНОЛОГИЧЕСКИЕ ОСОБЕННОСТИ ФОРМИРОВАНИЯ ПРОЗРАЧНЫХ ПРОВОДЯЩИХ КОНТАКТОВ ИЗ ПЛЕНКИ ITO ДЛЯ СВЕТОДИОДОВ НА ОСНОВЕ НИТРИДА ГАЛЛИЯ

ITO thin films were prepared by electron beam deposition method over a range of processing conditions. The target material used in this study was an ITO pellet with a composition: In2O3 90 wt% and SnO2 10 wt%. The evaporation conditions were: a vacuum of 5 × 10-4 or 4 × 10-2 Pa and the rate of evaporation were controlled within the range 0.075–0.4 nm/s. The thickness of thin film was controlled by using a quartz crystal thickness monitor, resulting in films having 200 nm. After the deposition, the samples were annealed in a thermal annealing furnace in air or nitrogen at 300-700 оC for 30 s. Experiments aimed at choosing the optimal atmosphere for annealing the films yielded the different results. Indium tin oxide coatings properties were researching as a function of the deposition atmosphere and conditions of a thermal annealing. The ITO films deposited and annealed under the optimized conditions work well as the transparent conducting electrode in the light emitting diodes based on GaN.Исследованы свойства пленок ITO, полученных электронно-лучевым испарением в широком диапазоне режимов: давление кислорода составляло от 5 × 10-4 до 4 × 10-2 Па, скорость испарения 0,075—0,4 нм/с. Испарение проведено из гранул размером 3—6 мм, состоящих из смеси стехиометрических оксидов индия и олова в соотношении 9 : 1. Скорость нанесения поддерживали постоянной с помощью кварцевого датчика скорости нанесения и толщины пленки. Испарение останавливалось по достижении заданной толщины пленки 200 нм. После нанесения пленки проведен отжиг образцов в течение 30 с в среде азота или воздуха при температуре 300—700 оC. Изучение свойств полученных пленок проведено с целью выбора оптимальных условий нанесения и последующего отжига. Полученные в оптимальных условиях пленки ITO были успешно использованы в структурах светодиодов в качестве прозрачных проводящих контактов в светодиодах на основе GaN

Quantum walks: a comprehensive review

Quantum walks, the quantum mechanical counterpart of classical random walks, is an advanced tool for building quantum algorithms that has been recently shown to constitute a universal model of quantum computation. Quantum walks is now a solid field of research of quantum computation full of exciting open problems for physicists, computer scientists, mathematicians and engineers. In this paper we review theoretical advances on the foundations of both discrete- and continuous-time quantum walks, together with the role that randomness plays in quantum walks, the connections between the mathematical models of coined discrete quantum walks and continuous quantum walks, the quantumness of quantum walks, a summary of papers published on discrete quantum walks and entanglement as well as a succinct review of experimental proposals and realizations of discrete-time quantum walks. Furthermore, we have reviewed several algorithms based on both discrete- and continuous-time quantum walks as well as a most important result: the computational universality of both continuous- and discrete- time quantum walks.Comment: Paper accepted for publication in Quantum Information Processing Journa

ИССЛЕДОВАНИЕ СТРУКТУРЫ И МОРФОЛОГИИ ПОВЕРХНОСТИ ДВУХСЛОЙНОЙ КОНТАКТНОЙ МЕТАЛЛИЗАЦИИ Ti/Al

Ti/Al/Ni/Au metallization widely used in the technology of GaN base devices have a very important imperfection: rough surface. There are different opinions about the causes of this imperfection: balling−up of molten aluminum or the appearance intermetallic melt phases in the Au–Al system. To check the effect of the former cause, we have studied the formation of rough surface after annealing of Ti/Al metallization which is used as a basis of many metallization systems for GaN. The substrates were made from silicon wafers covered with Si3N4 films (0.15 microns). On these substrates we deposited the Ti(12 nm)/Al(135 nm) metallization system. After this deposition the substrates were annealed in nitrogen for 30 s at 850 оС. The as−annealed specimens were tested for metallization sheet resistivity, appearance and surface morphology.We have shown that during annealing of the Ti/Al metallization system, mutual diffusion of metals and active interaction with the formation of intermetallic phases occur. This makes the metallization system more resistant to following anneals, oxidation and chemical etching. After annealing the surface of the Ti/Al metallization system becomes gently matted. However, large hemispherical convex areas (as in the Ti/Al/Ni/Au metallization system) do not form. Thus, the hypothesis on the balling−up of molten aluminum on the surface of the Ti/Al metallization system has not been confirmed.Широко распространенная в технологии приборов на основе GaN металлизация Ti/Al/Ni/Au имеет существенный недостаток: грубую шероховатую поверхность. Существуют различные мнения о причинах этого недостатка: агломерация расплавленного алюминия при высоких температурах отжига или возникновение расплава интерметаллидных соединений Au—Al, образующихся в результате взаимодействия алюминия с золотом через промежуточный слой барьерного металла, в частности никеля. С целью проверки влияния первой причины исследована возможность образования шероховатой поверхности после отжига у двухслойной металлизации титан—алюминий Ti(12 нм)/Al(135 нм), которую наносили на пластины кремния с пленкой нитрида кремния толщиной 0,15 мкм. После нанесения металлизации подложки подвергали отжигу в потоке азота. Длительность отжига составляла 300 с при различных температурах в диапазоне 400—700 °С или 30 с при температуре 850 °С. После каждого отжига образцов оценивали результаты термообработки по поверхностному сопротивлению металлизации, внешнему виду и морфологии ее поверхности. Показано, что во время отжига двух-слойной металлизации Ti/Al в ней происходят взаимная диффузия металлов и их активное взаимодействие с образованием их химических соединений, формирующих интерметаллидные фазы, которые делают металлизацию более стойкой к последующим более высокотемпературным отжигам, окислению и химическому травлению. Обнаружено, что после отжига двухслойной металлизации Ti/Al возрастает шероховатость ее поверхности, что приводит к тому, что поверхность металлизации становится слегка матовой. Но образование крупных полусферических выпуклостей, как это про-исходит у многослойной металлизации Ti/Al/Ni/Au, не выявлено. Таким образом, гипотеза о возникновении грубой шероховатости в виде большого числа куполообразных выступов на поверхности контактной металлизации из−за каплеобразования в слое алюминия в результате его плавления при высоких температурах отжига не подтверждена.