Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

A Physical Basis for the Second Law of Thermodynamics: Quantum Nonunitarity

It is argued that if the non-unitary measurement transition, as codified by Von Neumann, is a real physical process, then the ‘probability assumption’ needed to derive the Second Law of Thermodynamics naturally enters at that point. The existence of a real, indeterministic physical process underlying the measurement transition would therefore provide an ontological basis for Boltzmann’s Stosszahlansatz and thereby explain the unidirectional increase of entropy against a backdrop of otherwise time-reversible laws. It is noted that the Transactional Interpretation (TI) of quantum mechanics provides such a physical account of the non-unitary measurement transition, and TI is brought to bear in finding a physically complete, non-ad hoc grounding for the Second Law.

The Higgs Boson, The God Particle, and the Correlation Between Scientific and Religious Narratives

The Higgs mechanism – as part of the Standard Model of Elementary Particle Physics – is mostly considered to be a real physical process that brings about the mass of every elementary particle. Recent discussions show that there are alternative interpretations of it, differing from the common one in the spectrum and the features of some specific physical objects. This, in turn, shows that the problem of reference remains unsolved for physical theories: It is not obvious what kind of objects theoretical terms exactly refer to. Given the fact that the reference to the object level is ambiguous even in the natural sciences, what correlations can be established between scientific terms and religious expressions at all? Do ontic ambiguities make the dialogue between science and religion easier or more complicated? This article reflects on these questions by examining the possible significations (and interrelations) of scientific and religious signs in general as well as from the perspective of the individual. I suggest that religious storytelling and ritual practices can establish specific associations between scientific and religious worldviews under certain conditions – without confusing the different world-views conceptually.

ON THE MASS NEUTRINO PHASE ALONG THE GEODESIC LINE AND THE NULL LINE IN CURVED AND FLAT SPACETIME

On the mass neutrino phase calculations along both the particle geodesic line and the photon null line, there exists a double counting, a factor of 2, when comparing the geodesic phase with the null phase. Moreover, we compare the phase calculations with the same-energy description and the same-momentum description by means of the Minkowski diagram, and obtain the practical equivalence of these two descriptions. On the same-velocity description, although not corresponding any real physical process, we still indicate its phase calculation in the Minkowski diagram, which has the same result as those of same-energy and same-momentum cases. Furthermore, in the curved spacetime, we also prove the existence of the double counting of the geodesic phase to the null phase. Our conclusions are the same as others' results by the different methods.

Rayleigh–Taylor modes in the presence of velocity shear and vortices

Two-field models for Rayleigh–Taylor modes are investigated. The changes due to external velocity shear (without flow curvature) are reviewed, and the influences of the various terms in the models are discussed. It is shown that, in principle, velocity shear in combination with dissipation leads to the suppression of linear Rayleigh–Taylor modes in the long-time limit. The long-wavelength modes first seem to be damped; however, later they show an algebraic growth in time, before ultimately the exponential viscous damping wins. In general, the amplitudes become very large, and therefore the often-quoted stability of Rayleigh–Taylor modes in the presence of velocity shear is more a mathematical artefact than a real physical process. Vortices, on the other hand, can lead (together with velocity shear) to a quite different dynamical behaviour. Because of a locking of the wave vectors, pronounced oscillations appear. This effect is demonstrated by a simple model calculation. When vortices and velocity shear are generated from linear instability, the resulting oscillatory state finally becomes unstable with respect to Rayleigh–Taylor modes on a long time scale (‘secondary instability’).

Markov Fatigue in Single Crystal Airfoils

This paper considers the influence of microstructure on macrobehavior in single crystal airfoils by treating the micromechanics of damage accumulation as a Markov process. Single Crystal Fatigue (SCF) is a result of several, simultaneous (competing), damage mechanisms, which are selectively favored by particular combinations of external conditions. As with any real physical process, SCF is also influenced by a stochastic component. This probabilistic influence can be exploited to help explain the macrobehavior. We begin with a description of single crystal materials and how they differ from more conventional (isotropic) alloys. Relationships are suggested among the more probable of several competing microstructural damage mechanisms and specific rate-controlling parameters. The states of microstructural damage are then described and catalogued, and the various avenues of damage accumulation are investigated. Next, the Markov paradigm is reviewed as it applies to these materials. Finally, a Markov model is presented to describe the rather complex behavior observed in single crystals, and its use in lifing gas turbine engine airfoils is discussed.