Gauge Procedure Research Articles

A Kriging-Based Magnetic Flux Leakage Method for Fast Defect Detection in Massive Pipelines

Abstract Systems in service continue to degrade with the passage of time. Pipelines are among the most common systems that wear away with usage. For public safety, it is of utmost importance to monitor pipelines. Magnetic flux leakage (MFL) testing is a widely used nondestructive evaluation (NDE) technique for defect detections within the pipelines, particularly those composed of ferromagnetic materials. Pipeline inspection gauge (PIG) procedure based on line scans can collect accurate MFL readings for defect detection. However, in real world, applications involving large pipe sectors such as extensive scanning techniques are extremely time consuming and costly. In this article, we develop a fast and cheap methodology that does not need MFL readings at all the points used in traditional PIG procedures but conducts defect detection with similar accuracy. We consider an under-sampling based scheme that collects MFL at uniformly chosen random scan points over large lattices instead of extensive PIG scans over all lattice points. On the basis of readings from the chosen random scan points, we use kriging to reconstruct MFL readings. Thereafter, we use thresholding-based segmentation on the reconstructed data for detecting defective areas. We demonstrate the applicability of our methodology on synthetic data generated using finite element models and on MFL data collected via laboratory experiments. In these experiments, spanning a wide range of defect types, our proposed novel MFL-based NDE methodology is witnessed to have operating characteristics within the acceptable threshold of PIG-based traditional methods and thus provide an extremely cost-effective, fast procedure with competing error rates.

On the Variational Principle in the Cartan–Weyl Space

In [1, 2] the point of view was expressed that a gauge approach to the theory of gravitation should be added to the existing geometrical approach. On the basis of the gauge theory of the Poincare–Weyl group it was shown in [1, 2] that the Cartan–Weyl space 4 CW is the geometric background in the modern theory of gravitation. In these same works it was shown that within the framework of the gauge procedure the scalar Dirac field  arises in a natural way from geometrical requirements as an important addition to the metric tensor, having as fundamental a geometrical status as the metric tensor itself. The Dirac field  was introduced in a well-known work by Dirac, and also by Deser [3]. In the construction of the theory of gravitation in post-Riemannian spaces characterized by the 2-forms of curvature b R and torsion a T and the 1-form of nonmetricity ab Q , the choice of variational procedure and the basis for using this procedure to derive the gravitational field equations play an important role. In the present work we generalize the variational formalism in exterior forms, developed in [3, 4] for the Cartan–Weyl space 4 CW , to the presence of the Dirac scalar field, where the additional condition (Q is the Weyl 1-form)

A new formulation of non-relativistic diffeomorphism invariance

We provide a new formulation of non-relativistic diffeomorphism invariance. It is generated by localising the usual global Galilean symmetry. The correspondence with the type of diffeomorphism invariant models currently in vogue in the theory of fractional quantum Hall effect has been discussed. Our construction is shown to open up a general approach of model building in theoretical condensed matter physics. Also, this formulation has the capacity of obtaining Newton–Cartan geometry from the gauge procedure.

Scalar gauge fields

In this paper we give a variation of the gauge procedure which employs a scalar gauge field, $B (x)$, in addition to the usual vector gauge field, $A_\mu (x)$. We study this variant of the usual gauge procedure in the context of a complex scalar, matter field $\phi (x)$ with a U(1) symmetry. We will focus most on the case when $\phi$ develops a vacuum expectation value via spontaneous symmetry breaking. We find that under these conditions the scalar gauge field mixes with the Goldstone boson that arises from the breaking of a global symmetry. Some other interesting features of this scalar gauge model are: (i) The new gauge procedure gives rise to terms which violate C and CP symmetries. This may have have applications in cosmology or for CP violation in particle physics; (ii) the existence of mass terms in the Lagrangian which respect the new extended gauge symmetry. Thus one can have gauge field mass terms even in the absence of the usual Higgs mechanism; (iii) the emergence of a sine-Gordon potential for the scalar gauge field; (iv) a natural, axion-like suppression of the interaction strength of the scalar gauge boson.

20 versus 23 Gauge sclerotomies for silicone oil extraction in vitreoretinal surgery

AbstractPurpose The visco‐elastic features of silicone oil are a limiting factor transconjunctival vitreoretinal surgery. The flow resistence increases with the reduction of the inner diameter of the extrusion canula. Thise increases the duration of silicone oil extraction. The purpose of this study was to compare 2 surgical procedures for silicone oil extrusion: 20 versus 23 Gauge.Methods A retrospective pilot study compared two groups of patients scheduled for silicone oil extraction. In the first group silicone oil extraction was performed through a 20 Gauge scllerotomy after conjunctival dissection whereas a 25 Gauge tranconjunctival sclerotomy enabled saline infusion. In the second group both infusion and silicone oil extraction was performed through 23 Gayge transconjunctival sclerotomies. The duration of each procedure was the main outcome measure.Results The mean duration of the 23 Gauge procedure was 42 minutes compared with 22 minutes in the combined 20/25 Gauge procedure. Transitory intraoperative hypotonia was encountered in two patients, one in each group. During the post‐operative follow up, a vitreous hemorrhage occurred in one patient of the 23 Gauge procedure group.Conclusion Comparing two surgical procedures for silicone oil extraction, the conjunctival dissection time in the 20/25 Gauge group seems to be largely counterbalanced by the rapidity of the silicone oil extraction through a larger sclerotomy. The use of a combined 20/25 Gauge full transconjunctival procedure could probably reduce furthermore the duration of surgery .

Gauge procedure with gauge fields of various ranks

The standard procedure for making a global phase symmetry local involves the introduction of a rank 1, vector field in the definition of the covariant derivative. Here it is shown that it is possible to gauge a phase symmetry using fields of various ranks. In contrast to other formulations of higher rank gauge fields we begin with the coupling of the gauge field to some matter field, and then derive the gauge invariant, field strength tensor. Some of these gauge theories are similar to general relativity in that their covariant derivatives involve derivatives of the rank n gauge field rather than just the gauge field. For general relativity the covariant derivative involves the Christoffel symbols which are written in terms of derivatives of the metric tensor. Many (but not all) of the Lagrangians that we find for these higher rank gauge theories lead to non-renormalizable quantum theories which is also similar to general relativity.

Gauge-invariant tree-level photoproduction amplitudes with form factors

We show how the gauge-invariance formulation given by Haberzettl is implemented in practice for photoproduction amplitudes at tree level with form factors describing composite nucleons. We demonstrate that, in contrast to Ohta's gauge-invariance prescription, this formalism allows electric current contributions to be multiplied by a form factor, i.e., it does not require that they be treated like bare currents. While different in detail, this nevertheless lends support to previous ad hoc approaches which multiply the Born amplitudes by an overall form factor. Numerical results for kaon photoproduction off the nucleon are given. They show that the gauge procedure by Haberzettl leads to much improved ${\ensuremath{\chi}}^{2}$ values compared to Ohta's prescription.

On the isotropy of continuized dislocated crystals. II. The isotropy of diffusive properties

The classical theory of the influence of single immobile dislocations on the diffusion of point defects cannot be applied to the description of the influence of a finite but very large number of dislocations on this diffusion, because in this case dissipative effects (due to dislocations) cannot be neglected. In this paper these dissipative effects are described by means of a generalized gauge procedure taking advantage of the existence of the short-range order in continuized dislocated crystals. It is shown that, for uniformly dense distributions of dislocations, the existence of dissipative effects means the existence of a (nonvanishing) scalar curvature of a conformally flat configurational space of a single diffusing point defect. Equations describing the interaction energy between dislocations and a diffusing point defect are proposed, and the contribution to this energy of elastic as well as inelastic interactions is discussed.

On the Geometry of Diffusion Processes in Continuized Dislocated Crystals

Nonequilibrium diffusion processes of point defects in continuized dislocated crystals are considered. A generalized, stochastically motivated gauge procedure to introduce the geometry of a material space describing the influence of dislocations on the free diffusion process, is used. The dependence of diffusing processes and their steady states on the curvature of the material space of edge dislocations, on the scalar density of these dislocations, and on the interaction energy between dislocations and a diffusing atom, is analysed. An equation defining the interaction energy is deduced, using statistical arguments, from the material space geometry.

Geometrical and physical gauging in the theory of dislocations

Geometrical and variational aspects of the gauge theory of static equilibrium distributions of dislocations are analysed. The gauge procedure, based on Kondo and Kröner's Gedanken Experiments for dislocated bodies, is formulated and basal interpretation rules of the theory are proposed. The unimodular invariance of the free gauge field theory is discussed.

A note on the physical interpretation of Weyl gauging

A possible physical justification of the Weyl gauge procedure is proposed. It is argued that in the case of a general affine connection geodesic parameters have a nontrivial functional relation to metric interval. Since geodesic parameters can also define a notion of interval (via Schild's ladder), we appear to have an inconsistency at the very foundation of any theory which incorporates a nonmetric-compatible connection. This inconsistency can be removed by postulating the Weyl transformations as a valid symmetry of nature, at least at the appropriate energy scale. The method would appear to work even in theories containing shear, provided that it too acquires a mass as a result of (or prior to) the breaking of Weyl symmetry.

Locally equilibrium diffusion processes. I. Geometry of local thermodynamic equilibrium states

The geometric description of local thermodynamic equilibrium states in a locally homogeneous body is formulated. The considered geometry is defined on the basis of the condition that the gauge procedure of the partial derivative operations should preserve the form of the equations describing the local thermodynamic equilibrium state of the homogeneous body with diffusion, and be consistent with the description of diffusion as a Markovian diffusion process with different mean arriving and starting velocities. The statistical entropy of the diffusion process is examined.

A supersymmetric dynamics of hadrons

Combining the idea of supersymmetries with the standard gauge procedure an economic scheme for hadrodynamics including all types of its interactions is suggested.

Recent high field Nb<inf>3</inf>Sn tape solenoids of large radial access

Large radial access in a high field solenoid magnet is important in applications of current interest. Several magnets produced recently provide examples of two types of large radial access split solenoids. The variable gap split magnet provides flexibility in allowing fields above 15 T in a "closed position" without radial access and, in the same magnet, allowing fields above 13 T with radial access sufficient to test large cryostable conductors. The requirement of large solid angle view of the central field region is met with a second type of split magnet incorporating conical windings. The structural support of the windings above large radial ports is a critical design issue. Procedures developed recently for the use of cryogenic strain gauges in magnetic field environments have been adopted to measure support stresses. The strain gauge procedure, measurement results, and comparison with analysis is presented.