Narrow Results

A symbolic calculus named as the R-calculus is built to revise the defects of axiomatic systems mechanically when some counterexamples are found. The R-calculus consists of the rules of logical connective symbols and logical quantifier symbols of first order languages. The concept of reachability, soundness and completeness of the R-calculus are introduced. The basic theorem of software testing based on the R-calculus is also introduced to help mechanizing model checking.

The martensitic transformation is often accompanied by the production of defects either in the austenite, the martensite or in both phases. An interesting example of this is the generation of bulk dislocations and surface defects after pseudoelastic cycling in Cu-Zn-Al single crystals. The involved phases are the cubic (L2₁) of the austenite and the monoclinic 18R martensitic phase. The dislocations arrange in the bulk following crystallographic patterns associated to the habit plane of the transition and the basal plane of the martensite. A microscopic analysis shows that the dislocations are produced by plastic deformation of the martensite. These dislocations have several consequences on the mechanical behavior of the material and on the kinetics of the diffusional processes present in both phases. The formation of intrusions and extrusions at the surface specimens is another important effect of the pseudoelastic cycling. They play a crucial role on the fatigue life of the specimens. Recent results show a strong effect of composition on the nucleation of surface defects. The crystallography of the defects, the origin of the dislocations, their arrangements and their interaction with the specimen surface are discussed.

Instead of introducing an ad hoc dark energy in order to explain the accelerated expansion of the universe, we try a different approach treating space time as a physical continuum endowed of specific properties. A Lagrangian modeled on the one valid for simple dissipative phenomena in fluids is build and used for empty space time. The internal "viscosity" is shown to correspond to a four-vector field. Using the known symmetry of the universe, assuming the vector field to be divergence-less and solving the Euler-Lagrange equation we directly obtain inflation and a phase of accelerated expansion of space time. The vector field is shown to correspond to the displacement vector field induced by a point defect in a four-dimensional continuum. The presence of ordinary matter does not spoil the obtained general behaviour.

Changes of field variables may lead to multivalued fields which do not satisfy the Schwarz integrability conditions. Their quantum field theory needs special care as is illustrated here in applications to superfluid and superconducting phase transitions. Extending the notions that first qantization governs fluctuating orbits while second quantization deals with fluctuating field, the theory of multivalued fields may be considered as a theory of third quantization. The lecture is an introduction to my new book on this subject.

The surface Partial Discharge (PD) triggered by immobilized metal wire on Gas Insulated Switchgear (GIS) insulators in terms of the discharge phenomena alongside its evaluation process was researched in this paper. With the application of gradually increased voltage, long-term tests were conducted on a well-established 252kV GIS experiment platform to observe the entire evolution process of PD from its very initiation till the eventual flashover. Ream-time measurement was undertaken during the tests to capture the trend curve as a result of test time. The results indicate that PD initiated by defects in GIS can be classified into three severity levels, namely, petty discharge, medium discharge, and threatening discharge. Moreover, a procedure based on k-means cluster analysis is proposed to diagnose and assess the severity of PD automatically.

We report photoluminescence in the self-ion implanted silicon wafers annealed from room temperature to 950°C. The annealing temperature has been demonstrated to be a key factor which induces the dominant photoluminescence structures changed from broadband, W line, S bands, R line, to D bands with its increase. The optimal annealed temperature ranges for these features are obtained. At the low annealing temperatures (≤ 650°C), the PL spectra were predominated by several sharp peaks which originate from point defects at low record temperatures and by broadband which originate from cluster defects at high record temperature. At higher annealing temperature (> 650°C), the PL spectra were only dominated by D₁ band which undergoes red-shift and widening with increasing record temperature.

Space-time is described as a strained four-dimensional elastic continuum. The embedding of a given manifold in a higher dimensional at one allows to extend to four dimensions the usual three-dimensional theory of elastic and plastic deformations. Curvature is then described in terms of strain of the manifold and the strain tensor turns out to be the non-trivial part of the metric tensor. The global behaviour of space-time and its Robertson-Walker symmetry is described as being the consequence of a defect in the manifold. The analogy with the traditional elasticity theory suggests the introduction of an additional term in the Einstein-Hilbert action, representing the potential energy associated with the strained state. The new Lagrangian is then tested on the luminosity curve of type 1a supernovae and the accelerated expansion. The fit turns out to be slightly better than the one obtained by the ΛCDM theory and gives a value for the “bulk modulus” of space-time. The obtained value is consistent with the Newtonian limit of the theory up to the scale of galaxy clusters.

An interpretation of the gauge anomaly of the two-dimensional multi-phase σ-model is presented in terms of an obstruction to the existence of a topological defect network implementing a local trivialisation of the gauged σ-model.

This is a summary of the parallel session.

We give an overview of the use of multivalued fields to describe a Riemann-Cartan spacetimes with curvature and torsion with the help of multivalued displacement fields in spacetime.