Cutoff Surfaces Research Articles

Analysis of the Sawing Process With Abrasive Circular Saw Blades

This study simulates the sawing process with an abrasive circular saw blade and analyzes the generation of cutoff surfaces in the sawing process with the consideration of the blade deflection caused by the asymmetric wear of the blade outer edge. The analysis is built on the previous work of Matsui (1956, J. Jpn. Soc. Precis. Eng., 22, pp. 477–481) who presented an analytical formula for cutting force acting on a conical cutting edge. In this paper, the Matsui formula is modified to take into account the “size effect” of grinding and used to calculate the grinding force acting on the blade surface. A differential equation is constructed, and the related numerical solutions are provided to describe the blade deflection behavior in the sawing process. The study then discusses the influences of the “size effect,” workpiece length, workpiece speed and feed rate, as well as cutting edge density on sawing accuracies. Also discussed are workpiece speed and cutting edge density on the maximum deviation of the cutoff surface.

Effects of Two-Dimensional Inhomogeneity in O-X Mode Conversion in Tokamak Plasmas

Ordinary and extraordinary wave couplings in the vicinity of the cutoff surfaces in magnetized plasmas are analyzed in a two-dimensionally inhomogeneous tokamak-like geometry. It is demonstrated that the mode conversion may be of an essentially two-dimensional nature when the cutoff surfaces intersect in space along a certain line. For the latter case the reduced wave equations in the transformation region are derived and solved analytically. Structures of the transformed and reflected waves and corresponding transformation coefficients are obtained for an arbitrary field distribution in the incident beam. In particular, the intensity transformation coefficients of Gaussian beams are analyzed in more detail.

On the influence of 2D inhomogeneity on electromagnetic mode conversion near the cut-off surfaces in magnetized plasmas

Peculiarities of the ordinary to extraordinary wave conversion in the electron cyclotron frequency range near the cut-off surfaces in magnetized plasmas are analysed in a two-dimensionally inhomogeneous simplified tokamak-like geometry. It is demonstrated that the mode conversion may be of essentially two-dimensional nature even neglecting the curvature of the cut-off surfaces; for the latter case a set of reduced wave equations in the transformation region is derived and solved analytically. Transformation coefficients for quasi-optical beams with a finite transverse distribution of rf field are obtained as well as a recipe for synthesis of the optimal (perfectly converted) beam. Applicability limits of a conventional one-dimensional theory are finally discussed.

Dynamic modeling of geomagnetic cutoff for the 23–24 November 2001 solar energetic particle event

We investigate numerically the time variations of geomagnetic cutoffs of solar energetic particles. As a test case, the geomagnetic cutoff of 25 MeV protons is modeled for the 23–24 November 2001 solar energetic particle (SEP) event. Following Smart and Shea [2001], solar energetic particle access is determined by computing the reverse particle trajectories. Magnetospheric fields are obtained from the Lyon‐Feder‐Mobarry (LFM) global MHD model, which is driven by measured solar wind parameters at the sunward boundary. We find well‐defined surfaces of constant cutoff that exhibit dynamic behavior in response to solar wind conditions. We show that dynamic modeling of cutoff surfaces may be used as a tool to investigate SEP access to the inner magnetosphere. The numerical results are compared with proton observations from a highly elliptical orbit (HEO) satellite. The results suggest that an enhancement in the solar wind dynamic pressure plays a role in the observed ion injection.

Elastic energy of a screw dislocation near a planar interface: effect of inner cut-off

The energy of a screw dislocation near the planar interface separating two isotropic media of different shear moduli is calculated via the work done by surface forces during a virtual process of dislocation creation. In addition to the only term usually considered arising from the cut across the material, contributions from the inner and outer cut-off surfaces have been taken into account. The force on the dislocation arising from the difference in elastic moduli is found neither to diverge nor to vanish at the interface. The critical stress to force the dislocation into a medium with higher modulus is discussed and compared with other calculations based on non local elasticity or a Peierls model. This calculation method of the total elastic strain energy finds a useful application in atomistic calculations of dislocations making possible accurate energy comparisons.

The contribution of plasma dielectric properties to the cyclotron radiation spectrum from a tokamak plasma

The effects of the dielectric properties of the plasma on the cyclotron radiation spectrum from a tokamak discharge are investigated for propagation perpendicular to the magnetic field. At the cut-offs and at the upper hybrid resonance the cold-plasma dispersion relation is assumed to be valid. It is shown that the presence of evanescent regions, cut-off surfaces, and an upper hybrid resonance surface in the plasma distorts the line shape at the lower harmonics when ωp ∼ ωc. The first-harmonic extraordinary-mode emission is suppressed as ωp/ωc at the centre of the discharge increases owing to the de-coupling of the electromagnetic wave from the plasma electrons. A computer study is made of the changes in the spectrum as (ωp/ωc)r=0 is increased. The anisotropy of the cyclotron radiation spectrum about the minor axis of the torus is also investigated. Both line width and shape depend on the viewing direction.

Electromagnetic Waves in Parameter Space for Finite Magnetoplasmas

High-frequency electromagnetic waves guided by an air-bounded, axially magnetized, plasma column of radius a are studied through the technique of parameter space mapping. The parameter space is 3-dimensional with coordinates ωp/ω, ωb/ω, and c/ωa. In this 3-space, cutoff and resonance loci form surfaces which enclose approximate domains of existence for various classes of waves. Three wave classes, characterized by distinctive cutoff and resonance surfaces, are identified for a magnetized plasma column, and their relation to waves in a boundless plasma, and on a column of small radius (quasistatic waves) is investigated. Also, evidence is found for the continued existence of the surface wave class into the regime ωb>ωp. Parameter space analysis leads to a determination of salient dispersion characteristics for all wave classes and all order of azimuthal variation by a method contributing to physical insight but which avoids exact but laborious numerical computation. Waves are found which change from forward to backward or vice versa with increasing wave number.