163 research outputs found
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- superconductors.Comment: 10 pages, 1 figure, revtex
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
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.
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
- …