Исследование нагрузочной характеристики гибкого вала винтовых забойных двигателей при бурении скважин

Цель работы – проведение расчета гибкого вала винтового забойного двигателя. Область применения: нефтегазовая промышленность.The purpose of the work is to calculate the flexible shaft of the downhole screw motor. Application: oil and gas industry

Experimental simulation of large, high field, superconducting magnet operation First quarterly report, Mar. 1 - May 31, 1965

Magnetic coil testing and experiment preparations for magnet facility in simulation of large high field superconducting magnet operatio

Асинхронный электропривод неполно-поворотной заслонки

В процессе работы были исследованы переходные процессы модели привода ГУСАР при закрытии заслонки, открытии, повороте на несколько градусов градус, при пониженном напряжении сети. Дипломный проект содержит описание требований предъявляемых к электроприводу заслонки, разработанный алгоритм формирования момента, разработанную модель электропривода заслонки в среде Matlab Simulink. Рассчитаны технико-экономические показатели; рассмотрены основные вопросы экологичности и безопасности проекта.In the process, the transient processes of the GUSAR drive model were studied with the shutter closed, opening, turning several degrees, with a reduced network voltage. The graduation project contains a description of the requirements for an electric drive damper, developed by an algorithm for generating a moment, developed by a model of an electric drive damper in a Matlab Simulink environment. Technical and economic indicators are calculated; The main issues of environmental friendliness and safety of the project are considered

Elasticity-driven interaction between vortices in type-II superconductors

The contribution to the vortex lattice energy which is due to the vortex-induced strains is calculated covering all the magnetic field range which defines the vortex state. This contribution is compared with previously reported ones what shows that, in the most part of the vortex state, it has been notably underestimated until now. The reason of such underestimation is the assumption that only the vortex cores induce strains. In contrast to what is generally assumed, both core and non-core regions are important sources of strains in high-$\kappa$ superconductors.Comment: 10 pages, 1 figure, revtex

Self-organization of vortices in type-II superconductors during magnetic relaxation

We revise the applicability of the theory of self-organized criticality (SOC) to the process of magnetic relaxation in type-II superconductors. The driving parameter of self-organization of vortices is the energy barrier for flux creep and not the current density. The power spectrum of the magnetic noise due to vortex avalanches is calculated and is predicted to vary with time during relaxation.Comment: RevTex, 5 pages, 2 PS figures. Accepted in Phys. Rev.

Surface deformation caused by the Abrikosov vortex lattice

In superconductors penetrated by Abrikosov vortices the magnetic pressure and the inhomogeneous condensate density induce a deformation of the ionic lattice. We calculate how this deformation corrugates the surface of a semi-infinite sample. The effect of the surface dipole is included

Технологические особенности процесса антипомпажного регулирования на компрессорных станциях

Объект исследования является явление помпажа, возникающее при эксплуатации центробежных компрессоров, а также методы и способы его регулирования. Цель исследования – анализ существующих методов и средств антипомпажного регулирования, поиск оптимальной конструкции регулирующего устройства для предупреждения возникновения помпажа. В процессе исследования проведен анализ нагрузок, действующих на центробежный компрессор. Определены причины возникновения явления помпажа и проанализировано его влияние на работу оборудования.The object of research is the phenomenon of surging that occurs during the operation of centrifugal compressors, as well as methods and methods of its regulation. The purpose of the study is to analyze the existing methods and means of anti-surge control, to find the optimal design of the control device to prevent the occurrence of surging. In the course of the study, the analysis of the loads acting on the centrifugal compressor was carried out. The causes of the surge phenomenon are determined and its impact on the operation of the equipment is analyzed

Defect structures in MgB2 wires introduced by hot isostatic pressing

The microstructures of MgB2 wires prepared by the powder-in-tube technique and subsequent hot isostatic pressing were investigated using transmission electron microscopy. Large amount of crystalline defects including small angle twisting, tilting, and bending boundaries, in which high densities of dislocations reside, were found forming sub-grains within MgB2 grains. It is believed that these defects resulted from particle deformation during the hot isostatic pressing process and are effective flux pinning centers that contribute to the high critical current densities of the wires at high temperatures and at high fields.Comment: 16 pages, 6 figure

Simple de Sitter Solutions

We present a framework for de Sitter model building in type IIA string theory, illustrated with specific examples. We find metastable dS minima of the potential for moduli obtained from a compactification on a product of two Nil three-manifolds (which have negative scalar curvature) combined with orientifolds, branes, fractional Chern-Simons forms, and fluxes. As a discrete quantum number is taken large, the curvature, field strengths, inverse volume, and four dimensional string coupling become parametrically small, and the de Sitter Hubble scale can be tuned parametrically smaller than the scales of the moduli, KK, and winding mode masses. A subtle point in the construction is that although the curvature remains consistently weak, the circle fibers of the nilmanifolds become very small in this limit (though this is avoided in illustrative solutions at modest values of the parameters). In the simplest version of the construction, the heaviest moduli masses are parametrically of the same order as the lightest KK and winding masses. However, we provide a method for separating these marginally overlapping scales, and more generally the underlying supersymmetry of the model protects against large corrections to the low-energy moduli potential.Comment: 37 pages, harvmac big, 4 figures. v3: small correction