535 research outputs found

    Numerical Simulation of Pulsed Electromagnetic Stamping Processes

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    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

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    На основС Π°Ρ€Ρ…ΠΈΠ²Π½Ρ‹Ρ… источников анализируСтся состав ΠΈ источники комплСктования Π±ΠΈΠ±Π»ΠΈΠΎΡ‚Π΅ΠΊΠΈ Богословских Π·Π°Π²ΠΎΠ΄ΠΎΠ², Ρ‡Ρ‚ΠΎ позволяСт ΠΏΠΎΡΡ‚Π°Π²ΠΈΡ‚ΡŒ Π΅Π΅ Π² ряд ΡΡ‚Π°Ρ€Π΅ΠΉΡˆΠΈΡ… ΠΈ Π±ΠΎΠ³Π°Ρ‚Π΅ΠΉΡˆΠΈΡ… Π±ΠΈΠ±Π»ΠΈΠΎΡ‚Π΅ΠΊ заводского Π£Ρ€Π°Π»Π°. РСконструируСтся Ρ€Π΅ΠΏΠ΅Ρ€Ρ‚ΡƒΠ°Ρ€ чтСния Π½Π° Богословских Π·Π°Π²ΠΎΠ΄Π°Ρ… Π² сСрСдинС 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

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    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

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    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

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    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.БпСциализация ΠΈ профилизация Турналиста Ρ€Π°ΡΡΠΌΠ°Ρ‚Ρ€ΠΈΠ²Π°ΡŽΡ‚ΡΡ Π² ΡΡ‚Π°Ρ‚ΡŒΠ΅ Π² качСствС эффСктивных инструмСнтов ΠΌΠ΅Π΄ΠΈΠ°ΠΌΠ΅Π½Π΅Π΄ΠΆΠΌΠ΅Π½Ρ‚Π°. ОсобоС Π²Π½ΠΈΠΌΠ°Π½ΠΈΠ΅ обращаСтся Π½Π° процСсс трансформации этих элСмСнтов Π² условиях ΠΌΡƒΠ»ΡŒΡ‚ΠΈΠΌΠ΅Π΄ΠΈΠΉΠ½ΠΎΡΡ‚ΠΈ

    Chemical potential of quasi-equilibrium magnon gas driven by pure spin current

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    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

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    РСконструкция Π·Π°Π±Ρ€ΠΎΡˆΠ΅Π½Π½Ρ‹Ρ… ΠΈ ΠΏΡ€ΠΈΡˆΠ΅Π΄ΡˆΠΈΡ… Π² Π²Π΅Ρ‚Ρ…ΠΎΡΡ‚ΡŒ городских Ρ‚Π΅Ρ€Ρ€ΠΈΡ‚ΠΎΡ€ΠΈΠΉ рСсурсоСмка ΠΈ ΠΌΠΎΠΆΠ΅Ρ‚ Ρ‚Ρ€Π΅Π±ΠΎΠ²Π°Ρ‚ΡŒ Π΄Π»ΠΈΡ‚Π΅Π»ΡŒΠ½ΠΎΠ³ΠΎ Π²Ρ€Π΅ΠΌΠ΅Π½ΠΈ. НС всСгда Ρ‚Π΅Ρ€Ρ€ΠΈΡ‚ΠΎΡ€ΠΈΠΈ находятся Π½Π° ΠΎΠΊΡ€Π°ΠΈΠ½Π΅ Π³ΠΎΡ€ΠΎΠ΄Π°. ΠΠ»ΡŒΡ‚Π΅Ρ€Π½Π°Ρ‚ΠΈΠ²ΠΎΠΉ рСконструкции ΠΌΠΎΠ³ΡƒΡ‚ ΡΠ²Π»ΡΡ‚ΡŒΡΡ ΠΌΠ΅Ρ€Ρ‹ ΠΏΠΎ ΡΠΌΡΠ³Ρ‡Π΅Π½ΠΈΡŽ послСдствий Π΄Π΅Π³Ρ€Π°Π΄Π°Ρ†ΠΈΠΈ Ρ‚Π΅Ρ€Ρ€ΠΈΡ‚ΠΎΡ€ΠΈΠΉ ΠΈ сооруТСний. Π’ ΡΡ‚Π°Ρ‚ΡŒΠ΅ ΠΈΡΡΠ»Π΅Π΄ΡƒΡŽΡ‚ΡΡ возмоТности примСнСния ΠΌΠ΅Ρ€ ΠΏΠΎ ΡΠΌΡΠ³Ρ‡Π΅Π½ΠΈΡŽ послСдствий Π΄Π΅Π³Ρ€Π°Π΄Π°Ρ†ΠΈΠΉ Π½Π° ΠΏΡ€ΠΈΠΌΠ΅Ρ€Π΅ Π§Π΅Ρ…ΠΈΠΈ, Π‘Π»ΠΎΠ²Π°ΠΊΠΈΠΈ, Π“Π΅Ρ€ΠΌΠ°Π½ΠΈ

    The 35S U5 snRNP is generated from the activated spliceosome during In vitro splicing

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    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

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    ВосстановлСниС Π·Π°Π±Ρ€ΠΎΡˆΠ΅Π½Π½Ρ‹Ρ… городских ΠΈ ΠΏΡ€ΠΎΠΌΡ‹ΡˆΠ»Π΅Π½Π½Ρ‹Ρ… Ρ‚Π΅Ρ€Ρ€ΠΈΡ‚ΠΎΡ€ΠΈΠΉ (ΠΎΠ±ΡŠΠ΅ΠΊΡ‚ΠΎΠ²) являСтся Π°ΠΊΡ‚ΡƒΠ°Π»ΡŒΠ½Ρ‹ΠΌ Π² соврСмСнных условиях. ΠŸΡ€Π°ΠΊΡ‚ΠΈΡ‡Π΅ΡΠΊΠΈ Π²Π΅Π·Π΄Π΅ ΡΡƒΡ‰Π΅ΡΡ‚Π²ΡƒΡŽΡ‚ ΠΎΠ±ΡŠΠ΅ΠΊΡ‚Ρ‹, ΠΊΠΎΡ‚ΠΎΡ€Ρ‹Π΅ ΠΎΡΠ»ΠΎΠΆΠ½ΡΡŽΡ‚ дальнСйшСС Ρ€Π°Π·Π²ΠΈΡ‚ΠΈΠ΅ насСлСнного ΠΏΡƒΠ½ΠΊΡ‚Π°. ΠœΠ°Ρ‚Π΅ΠΌΠ°Ρ‚ΠΈΡ‡Π΅ΡΠΊΠΎΠ΅ ΠΌΠΎΠ΄Π΅Π»ΠΈΡ€ΠΎΠ²Π°Π½ΠΈΠ΅ позволяСт ΡΠΏΡ€ΠΎΠ³Π½ΠΎΠ·ΠΈΡ€ΠΎΠ²Π°Ρ‚ΡŒ ΡΡ„Ρ„Π΅ΠΊΡ‚ΠΈΠ²Π½ΠΎΡΡ‚ΡŒ восстановлСния Ρ‚Π°ΠΊΠΈΡ… Ρ‚Π΅Ρ€Ρ€ΠΈΡ‚ΠΎΡ€ΠΈΠΉ. Π’ ΡΡ‚Π°Ρ‚ΡŒΠ΅ ΠΏΠΎΠΊΠ°Π·Π°Π½Π° мСтодология прогнозирования ΠΈ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΠΎΡΡ‚ΡŒ ΠΏΠΎΠ»ΡƒΡ‡Π°Π΅ΠΌΠΎΠ³ΠΎ Ρ€Π΅Π·ΡƒΠ»ΡŒΡ‚Π°Ρ‚Π°, ΠΈΠΌΠ΅ΡŽΡ‰Π΅Π³ΠΎ Π·Π½Π°Ρ‡ΠΈΡ‚Π΅Π»ΡŒΠ½ΡƒΡŽ ΡΠΊΠΎΠ½ΠΎΠΌΠΈΡ‡Π΅ΡΠΊΡƒΡŽ Ρ†Π΅Π½Π½ΠΎΡΡ‚ΡŒ Π½Π° ΠΏΡ€ΠΈΠΌΠ΅Ρ€Π΅ Π·Π°Π±Ρ€ΠΎΡˆΠ΅Π½Π½ΠΎΠΉ ΡˆΠ°Ρ…Ρ‚
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