535 research outputs found
Numerical Simulation of Pulsed Electromagnetic Stamping Processes
In earlier published papers simulation of electromagnetic forming (EMF) was often conducted assuming that pulsed electromagnetic load can be replaced by the pulse of mechanical force calculating its parameters similar to R-L-C electric circuit. However, in many practical cases, parameters of this circuit are variable during the process because of the displacement of the blank and from one operation to another due to the accumulation of heat in the coil. The distribution of electromagnetic forces is also non-uniform and may affect the quality of the part being stamped. In our opinion, the accuracy of the simulation of EMF can be significantly improved if the formulation of the problem includes Maxwell equations of the electromagnetic field propagation, equations of dynamic elastic-plastic deformation, and heat transfer equations all coupled together. In addition, this approach may provide knowledge of electromagnetic coil deformation, which was investigated earlier with significant simplifications. The complexity of the problem is defined by mutual dependence of all three physical processes (electromagnetic field propagation, dynamic elastic-plastic deformation, and heat transfer) and variable boundary conditions. The propagation of the electromagnetic field is defined by quasi-stationary Maxwell equations transformed in Lagrangian form. The dynamics of elastic-plastic deformation is modeled using the solid mechanics equation of motion, the modified theory of elastic plastic flow, and the Von Mises yield criterion. The energy conservation law is employed for the simulation of heat transfer, which is important to define the appropriate stamping rate without overheating the coil. The developed methodology is illustrated by 2D examples of cone formation from sheet using a flat coil and the conical die and 2D plane strain sheet formation by direct propagation of the electric current through the metal bar, serving as a coil, and through the deformed sheet
Repertory of Reading at the Bogolsovsk Factories at the Middle of the XIXth Century
ΠΠ° ΠΎΡΠ½ΠΎΠ²Π΅ Π°ΡΡ
ΠΈΠ²Π½ΡΡ
ΠΈΡΡΠΎΡΠ½ΠΈΠΊΠΎΠ² Π°Π½Π°Π»ΠΈΠ·ΠΈΡΡΠ΅ΡΡΡ ΡΠΎΡΡΠ°Π² ΠΈ ΠΈΡΡΠΎΡΠ½ΠΈΠΊΠΈ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠΎΠ²Π°Π½ΠΈΡ Π±ΠΈΠ±Π»ΠΈΠΎΡΠ΅ΠΊΠΈ ΠΠΎΠ³ΠΎΡΠ»ΠΎΠ²ΡΠΊΠΈΡ
Π·Π°Π²ΠΎΠ΄ΠΎΠ², ΡΡΠΎ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΠΏΠΎΡΡΠ°Π²ΠΈΡΡ Π΅Π΅ Π² ΡΡΠ΄ ΡΡΠ°ΡΠ΅ΠΉΡΠΈΡ
ΠΈ Π±ΠΎΠ³Π°ΡΠ΅ΠΉΡΠΈΡ
Π±ΠΈΠ±Π»ΠΈΠΎΡΠ΅ΠΊ Π·Π°Π²ΠΎΠ΄ΡΠΊΠΎΠ³ΠΎ Π£ΡΠ°Π»Π°. Π Π΅ΠΊΠΎΠ½ΡΡΡΡΠΈΡΡΠ΅ΡΡΡ ΡΠ΅ΠΏΠ΅ΡΡΡΠ°Ρ ΡΡΠ΅Π½ΠΈΡ Π½Π° ΠΠΎΠ³ΠΎΡΠ»ΠΎΠ²ΡΠΊΠΈΡ
Π·Π°Π²ΠΎΠ΄Π°Ρ
Π² ΡΠ΅ΡΠ΅Π΄ΠΈΠ½Π΅ XIX Π².The inventories and sources of acquisition of books for the library of the Bogoslovsk factories are analyzed on the basis of archival data. This library can be considered as one of the oldest and richest libraries of the Ural. The article gives a reconstruction of the repertory of reading at the Bogoslovsk factories in the middle of the XIXth century
Analysis of Blank-Die Contact Interaction in Pulsed Forming Processes
During recent decade, significant efforts were dedicated to increasing the amount of Aluminum Alloys in automotive parts in order to reduce the net weight of cars. Processes of pulsed forming are known to expand the capabilities of traditional stamping operations. Propagation of pulsed electromagnetic field can be defined by quasi-stationary Maxwell equations, solved numerically using a non-orthogonal Lagrangian mesh. Suggested formulation included modelling of contact interaction of the blank with deformable die. Mild contact model based on introduction of acting-in-vicinity forces repelling the surfaces to be in contact was employed. It was tested by analyzing the elastic impact of bars and then was applied to the corner filling operation. This operation was analysed as a single pulse and as a multi pulse forming process. It indicated that some compromise between the blank formability enhancement and level of contact stresses on the die surface can be found. In addition, some examples of tubular parts pulsed press fitting using tube expansion with pulsed pressure were analyzed. Specific attention was paid to the analysis of factors playing important role in residual contact pressure between the exterior and interior tubes in pulsed press fitting operation
Design and Testing of Coils for Pulsed Electromagnetic Forming
Coil design influences the distribution of electromagnetic forces applied to both the blank and the coil. The required energy of the process is usually defined by deformation of the blank. However, the discharge also results in a significant amount of heat being generated and accumulating in the coil. Therefore, EMF process design involves working with three different problems: 1) propagation of an electromagnetic field through the coil-blank system and generation of pulsed electromagnetic pressure in specified areas, 2) high-rate deformation of the blank, and 3) heat accumulation and transfer through the coil with the cooling system. In the current work, propagation of an electromagnetic field in the coil, blank, die and surrounding air was defined using a consistent set of quasi stationary Maxwell equations applying a corresponding set of parameters for each media. Furthermore, a deformation of the blank driven by electromagnetic forces distributed through the volume of the blank was modeled using a solid mechanics equation of motion and the elastic plastic flow theory. During the discharge of capacitors the process was considered to be adiabatic due to the short duration of the pulse, so a heat transfer during the discharge time was neglected. The distribution of electric current density integrated during the discharge process defines the increase of temperature at every element of the coil. The distribution of temperature was calculated as a function of time using the energy conservation law
Specializing and profiling of journalistic practice in the terms of multimedia reality
In this article specializing and profiling of journalistic practice are examined as effective media management instruments. The author draws attention to the process of transformation of these elements to multimedia level.Π‘ΠΏΠ΅ΡΠΈΠ°Π»ΠΈΠ·Π°ΡΠΈΡ ΠΈ ΠΏΡΠΎΡΠΈΠ»ΠΈΠ·Π°ΡΠΈΡ ΠΆΡΡΠ½Π°Π»ΠΈΡΡΠ° ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ Π² ΡΡΠ°ΡΡΠ΅ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΡΡ
ΠΈΠ½ΡΡΡΡΠΌΠ΅Π½ΡΠΎΠ² ΠΌΠ΅Π΄ΠΈΠ°ΠΌΠ΅Π½Π΅Π΄ΠΆΠΌΠ΅Π½ΡΠ°. ΠΡΠΎΠ±ΠΎΠ΅ Π²Π½ΠΈΠΌΠ°Π½ΠΈΠ΅ ΠΎΠ±ΡΠ°ΡΠ°Π΅ΡΡΡ Π½Π° ΠΏΡΠΎΡΠ΅ΡΡ ΡΡΠ°Π½ΡΡΠΎΡΠΌΠ°ΡΠΈΠΈ ΡΡΠΈΡ
ΡΠ»Π΅ΠΌΠ΅Π½ΡΠΎΠ² Π² ΡΡΠ»ΠΎΠ²ΠΈΡΡ
ΠΌΡΠ»ΡΡΠΈΠΌΠ΅Π΄ΠΈΠΉΠ½ΠΎΡΡΠΈ
Chemical potential of quasi-equilibrium magnon gas driven by pure spin current
We show experimentally that the spin current generated by the spin Hall
effect drives the magnon gas in a ferromagnet into a quasi-equilibrium state
that can be described by the Bose-Einstein statistics. The magnon population
function is characterized either by an increased effective chemical potential
or by a reduced effective temperature, depending on the spin current
polarization. In the former case, the chemical potential can closely approach,
at large driving currents, the lowest-energy magnon state, indicating the
possibility of spin current-driven Bose-Einstein condensation
Possibilities of mitigation measures utilization at brownfield regeneration
Π Π΅ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΡ Π·Π°Π±ΡΠΎΡΠ΅Π½Π½ΡΡ
ΠΈ ΠΏΡΠΈΡΠ΅Π΄ΡΠΈΡ
Π² Π²Π΅ΡΡ
ΠΎΡΡΡ Π³ΠΎΡΠΎΠ΄ΡΠΊΠΈΡ
ΡΠ΅ΡΡΠΈΡΠΎΡΠΈΠΉ ΡΠ΅ΡΡΡΡΠΎΠ΅ΠΌΠΊΠ° ΠΈ ΠΌΠΎΠΆΠ΅Ρ ΡΡΠ΅Π±ΠΎΠ²Π°ΡΡ Π΄Π»ΠΈΡΠ΅Π»ΡΠ½ΠΎΠ³ΠΎ Π²ΡΠ΅ΠΌΠ΅Π½ΠΈ. ΠΠ΅ Π²ΡΠ΅Π³Π΄Π° ΡΠ΅ΡΡΠΈΡΠΎΡΠΈΠΈ Π½Π°Ρ
ΠΎΠ΄ΡΡΡΡ Π½Π° ΠΎΠΊΡΠ°ΠΈΠ½Π΅ Π³ΠΎΡΠΎΠ΄Π°. ΠΠ»ΡΡΠ΅ΡΠ½Π°ΡΠΈΠ²ΠΎΠΉ ΡΠ΅ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΈ ΠΌΠΎΠ³ΡΡ ΡΠ²Π»ΡΡΡΡΡ ΠΌΠ΅ΡΡ ΠΏΠΎ ΡΠΌΡΠ³ΡΠ΅Π½ΠΈΡ ΠΏΠΎΡΠ»Π΅Π΄ΡΡΠ²ΠΈΠΉ Π΄Π΅Π³ΡΠ°Π΄Π°ΡΠΈΠΈ ΡΠ΅ΡΡΠΈΡΠΎΡΠΈΠΉ ΠΈ ΡΠΎΠΎΡΡΠΆΠ΅Π½ΠΈΠΉ. Π ΡΡΠ°ΡΡΠ΅ ΠΈΡΡΠ»Π΅Π΄ΡΡΡΡΡ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΠΈ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡ ΠΌΠ΅Ρ ΠΏΠΎ ΡΠΌΡΠ³ΡΠ΅Π½ΠΈΡ ΠΏΠΎΡΠ»Π΅Π΄ΡΡΠ²ΠΈΠΉ Π΄Π΅Π³ΡΠ°Π΄Π°ΡΠΈΠΉ Π½Π° ΠΏΡΠΈΠΌΠ΅ΡΠ΅ Π§Π΅Ρ
ΠΈΠΈ, Π‘Π»ΠΎΠ²Π°ΠΊΠΈΠΈ, ΠΠ΅ΡΠΌΠ°Π½ΠΈ
The 35S U5 snRNP is generated from the activated spliceosome during In vitro splicing
Primary gene transcripts of eukaryotes contain introns, which are removed during processing by splicing machinery. Biochemical studies In vitro have identified a specific pathway in which introns are recognised and spliced out. This occurs by progressive formation of spliceosomal complexes designated as E, A, B, and C. The composition and structure of these spliceosomal conformations have been characterised in many detail. In contrast, transitions between the complexes and the intermediates of these reactions are currently less clear. We have previously isolated a novel 35S U5 snRNP from HeLa nuclear extracts. The protein composition of this particle differed from the canonical 20S U5 snRNPs but was remarkably similar to the activated B* spliceosomes. Based on this observation we have proposed a hypothesis that 35S U5 snRNPs represent a dissociation product of the spliceosome after both transesterification reactions are completed. Here we provide experimental evidence that 35S U5 snRNPs are generated from the activated B* spliceosomes during In vitro splicing
Verification of overall effectivity of brownfield regeneration based on mathematical model
ΠΠΎΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΈΠ΅ Π·Π°Π±ΡΠΎΡΠ΅Π½Π½ΡΡ
Π³ΠΎΡΠΎΠ΄ΡΠΊΠΈΡ
ΠΈ ΠΏΡΠΎΠΌΡΡΠ»Π΅Π½Π½ΡΡ
ΡΠ΅ΡΡΠΈΡΠΎΡΠΈΠΉ (ΠΎΠ±ΡΠ΅ΠΊΡΠΎΠ²) ΡΠ²Π»ΡΠ΅ΡΡΡ Π°ΠΊΡΡΠ°Π»ΡΠ½ΡΠΌ Π² ΡΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΡΡ
ΡΡΠ»ΠΎΠ²ΠΈΡΡ
. ΠΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΈ Π²Π΅Π·Π΄Π΅ ΡΡΡΠ΅ΡΡΠ²ΡΡΡ ΠΎΠ±ΡΠ΅ΠΊΡΡ, ΠΊΠΎΡΠΎΡΡΠ΅ ΠΎΡΠ»ΠΎΠΆΠ½ΡΡΡ Π΄Π°Π»ΡΠ½Π΅ΠΉΡΠ΅Π΅ ΡΠ°Π·Π²ΠΈΡΠΈΠ΅ Π½Π°ΡΠ΅Π»Π΅Π½Π½ΠΎΠ³ΠΎ ΠΏΡΠ½ΠΊΡΠ°. ΠΠ°ΡΠ΅ΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΡΠΏΡΠΎΠ³Π½ΠΎΠ·ΠΈΡΠΎΠ²Π°ΡΡ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ Π²ΠΎΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΈΡ ΡΠ°ΠΊΠΈΡ
ΡΠ΅ΡΡΠΈΡΠΎΡΠΈΠΉ. Π ΡΡΠ°ΡΡΠ΅ ΠΏΠΎΠΊΠ°Π·Π°Π½Π° ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ»ΠΎΠ³ΠΈΡ ΠΏΡΠΎΠ³Π½ΠΎΠ·ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΈ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΠΎΡΡΡ ΠΏΠΎΠ»ΡΡΠ°Π΅ΠΌΠΎΠ³ΠΎ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠ°, ΠΈΠΌΠ΅ΡΡΠ΅Π³ΠΎ Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΡΡ ΡΠΊΠΎΠ½ΠΎΠΌΠΈΡΠ΅ΡΠΊΡΡ ΡΠ΅Π½Π½ΠΎΡΡΡ Π½Π° ΠΏΡΠΈΠΌΠ΅ΡΠ΅ Π·Π°Π±ΡΠΎΡΠ΅Π½Π½ΠΎΠΉ ΡΠ°Ρ
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