scholarly journals A Perturbative Method for Calculating the Impedance of Coils on Laminated Ferromagnetic Cores

2010 ◽  
Vol 2010 ◽  
pp. 1-24 ◽  
Author(s):  
Serguei Maximov ◽  
Allen A. Castillo ◽  
Vicente Venegas ◽  
José L. Guardado ◽  
Enrique Melgoza
Keyword(s):  
Perturbation Theory ◽  
Cross Section ◽  
Thermal Effects ◽  
Maxwell’S Equations ◽  
Maxwell's Equations ◽  
Circular Cross Section ◽  
The Self ◽  
The Core ◽  
Perturbative Method ◽  
Excellent Accuracy

A new set of formulas for calculating the self and mutual impedances of coils on straight and closed laminated ferromagnetic cores of circular cross-section has been derived. The obtained formulas generalize the well-known formulas for impedances of coils on homogeneous ferromagnetic cores, for the case of laminated cores, and improve the previously known formulas for laminated cores. The obtained formulas are fully consistent with Maxwell's equations and, therefore, offer an excellent accuracy. The perturbation theory and the average field technique are used to solve Maxwell's equations inside and outside the core. The solution inside the core can also be used in the analysis of thermal effects occurring inside the laminated core.

scholarly journals On the self-induction of electric currents in a thin anchor-ring

1912 ◽  
Vol 86 (590) ◽  
pp. 562-571 ◽  
Keyword(s):  
Cross Section ◽  
Circular Cross Section ◽  
The Self ◽  
Electric Currents ◽  
Fourth Term ◽  
Starting Point ◽  
Axis Of Symmetry ◽  
The Difference ◽  
Circular Axis ◽  
Mutual Induction

In their useful compendium of "Formulæ and Tables for the Calculation of Mutual and Self-Inductance," Rosa And Cohen remark upon a small discrepancy in the formulæ given by myself and by M. Wien for the self-induction of a coil of circular cross-section over which the current is uniformly distributed . With omission of n , representative of the number of windings, my formula was L = 4 πa [ log 8 a / ρ - 7/4 + ρ 2 /8 a 2 (log 8 a / ρ + 1/3) ], (1) where ρ is the radius of the section and a that of the circular axis. The first two terms were given long before by Kirchhoff. In place of the fourth term within the bracket, viz., +1/24 ρ 2 / a 2 , Wien found -·0083 ρ 2 / a 2 . In either case a correction would be necessary in practice to take account of the space occupied by the insulation. Without, so far as I see, giving a reason, Rosa and Cohen express a preference for Wien's number. The difference is of no great importance, but I have thought it worth while to repeat the calculation and I obtain the same result as in 1881. A confirmation after 30 years, and without reference to notes, is perhaps almost as good as if it were independent. I propose to exhibit the main steps of the calculation and to make extension to some related problems. The starting point is the expression given by Maxwell for the mutual induction M between two neighbouring co-axial circuits. For the present purpose this requires transformation, so as to express the inductance in terms of the situation of the elementary circuits relatively to the circular axis. In the figure, O is the centre of the circular axis, A the centre of a section B through the axis of symmetry, and the position of any point P of the section is given by polar co-ordinates relatively to A, viz.

scholarly journals Cross-Sectional Geometry and the Intermetallics Structure in a High Pressure Die Cast Mg-Al Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 1579-1584 ◽  
Author(s):  
A.V. Nagasekhar ◽  
Carlos H. Cáceres ◽  
Mark Easton
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Rectangular Cross Section ◽  
Circular Cross Section ◽  
Al Alloy ◽  
Cross Sectional ◽  
The Core ◽  
Die Cast ◽  
Increased Strength ◽  
Scanning Electron

Specimens of rectangular and circular cross section of a Mg-9Al binary alloy have been tensile tested and the cross section of undeformed specimens examined using scanning electron microscopy. The rectangular cross sections showed three scales in the cellular intermetallics network: coarse at the core, fine at the surface and very fine at the corners, whereas the circular ones showed only two, coarse at the core and fine at the surface. The specimens of rectangular cross section exhibited higher yield strength in comparison to the circular ones. Possible reasons for the observed increased strength of the rectangular sections are discussed.

On Deformation of the Injection Mold Core

2008 ◽  
Vol 44-46 ◽  
pp. 85-89
Author(s):  
J.J. Jia ◽  
Zheng Hao Ge ◽  
Y. Li
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Special Section ◽  
Circular Cross Section ◽  
Injection Molding Process ◽  
Injection Mold ◽  
Molding Process ◽  
Finite Element Software ◽  
The Core

For injection mold with core, during the injection molding process, the pressure on the core is usually uneven and will cause the core to deform. In this paper, on the basis of some predigestions and assumptions of the model, formulas for forecasting the deformation of the circular cross-section and the rectangular cross-section cores under three different injection ways are analyzed. The theoretical analysis results of a core with special section are validated through finite element software. At the end, some suggestions are given to minish the core deformation when the calculation value is too large.

The Cardiocoil Stent-Artery Interaction

2004 ◽  
Vol 127 (2) ◽  
pp. 337-344 ◽  
Author(s):  
Moshe Brand ◽  
Michael Ryvkin ◽  
Shmuel Einav ◽  
Leonid Slepyan
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Analytical Approach ◽  
Circular Cross Section ◽  
The Self ◽  
Elastic Cylindrical Shell ◽  
Mechanical Interaction ◽  
Damage Factor ◽  
Relative Thickness ◽  
Stenosed Artery

An analytical approach for the mechanical interaction of the self-expanding Cardiocoil stent with the stenosed artery is presented. The damage factor as the contact stress at the stent-artery interface is determined. The stent is considered as an elastic helical rod having a nonlinear pressure-displacement dependence, while the artery is modeled by an elastic cylindrical shell. An influence of a moderate relative thickness of the shell is estimated. The equations for both the stent and the artery are presented in the stent-associated helical coordinates. The computational efficiency of the model enabled to carry out a parametric study of the damage factor. Comparative examinations are conducted for the stents made of the helical rods with circular and rectangular cross sections. It was found, in particular, that, under same other conditions, the damage factor for the stent with a circular cross section may be two times larger than that for a rectangular one.

Finite Extension of an Elastic Strand With a Central Core

1978 ◽  
Vol 45 (4) ◽  
pp. 852-858 ◽  
Author(s):  
N. C. Huang
Keyword(s):  
Cross Section ◽  
Circular Cross Section ◽  
Single Layer ◽  
Finite Extension ◽  
Contact Forces ◽  
Central Core ◽  
The Core ◽  
Axial Forces ◽  
Helical Angle ◽  
Curved Rods

This paper deals with the finite extension of an elastic strand with a central core surrounded by a single layer of helical wires subjected to axial forces and twisting moments. The central core is considered as a straight rod of circular cross section and the helical wires are regarded as slender curved rods with circular cross section. The theory of slender curved rods is used in the analysis. Geometrical nonlinearities due to the reductions in helical angle and cross section of the core and wires are included. It is found that as a result of the contact between the central core and helical wires, a separation between helical wires can occur during the extension of the strand. Stresses in the core and wires as well as the contact forces between the core and wires are analyzed for strands with various helical angles subjected to different axial forces. Examples are presented for the finite extension of strands with fixed ends and strands with free ends.

Propagation of Nonlinear Electromagnetic Field Theories

1974 ◽  
Vol 52 (10) ◽  
pp. 917-918 ◽  
Author(s):  
A. Shamaly ◽  
A. Z. Capri
Keyword(s):  
Electromagnetic Field ◽  
Maxwell’S Equations ◽  
Maxwell's Equations ◽  
The Self ◽  
Field Theories ◽  
Proca Equation ◽  
Interaction Terms ◽  
Causal Propagation ◽  
Interaction Term

It is shown that the self-interaction term λ(AμAμ)2 added to the free Lagrangian for Maxwell's equations leads to acausal propagation. Furthermore, it is found that apart from the term λAμAμ which leads back to the Proca equation, all self-interaction terms leading to causal propagation must be nonpolynomial.

Perturbation theory for Maxwell’s equations with shifting material boundaries

2002 ◽  
Vol 65 (6) ◽  
Author(s):  
Steven G. Johnson ◽  
M. Ibanescu ◽  
M. A. Skorobogatiy ◽  
O. Weisberg ◽  
J. D. Joannopoulos ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Maxwell’S Equations ◽  
Maxwell's Equations

Study on a Preparation of PS Hollow Submicro-Fiber by Coaxial Electrospinning

2013 ◽  
Vol 652-654 ◽  
pp. 228-233
Author(s):  
Tai Qi Liu ◽  
Dan Lv ◽  
Xiao Long Zhao ◽  
Ning Gao ◽  
Na Zhao
Keyword(s):  
Drug Release ◽  
Cross Section ◽  
Circular Cross Section ◽  
Average Diameter ◽  
Gas Storage ◽  
Coaxial Electrospinning ◽  
Outer Flow ◽  
The Core ◽  
Polymer Liquids ◽  
Storage Energy

Coaxial electrospinning has been recognized as an efficient technique for fabrication of composite fibers with especial circular cross-section in a diameter from micrometers to nanometers. In this paper, PS hollow submicro-fibers have been successfully prepared by electrospinning two polymer liquids through a coaxial, two spinneret, followed by selective removal of the core. Moreover, the influence of the relative (inner-to-outer) flow rate on the morphology and the average diameter of the fibers have been studied. The hollow submicro-fibers are particularly attractive for use in catalysis, purification, separation, gas storage, energy conversion, drug release, sensing, and environmental protection.

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