Comparison of the beta-alpha angular correlations in the Li8 and B8 beta decays, and the conserved vector current theory

This paper describes a comparison of the beta-alpha angular correlations of the beta decays of Li8 and B8 to the 2.90-Mev alpha-unstable level of Be8. The data were fitted to an angular correlation in the laboratory system of the form W(θβα)=1+Acosθβα+Bcos2θβα, where A and B were independently determined for the Li8 and B8 beta decays from measurements at θβα=0°, 90°, and 180°. The coefficients A are due to the recoil of Be8* and have the same sign for both beta decays. The coefficients B arise from the interference of forbidden vector matrix elements with the allowed axial vector matrix element and have different signs in the two decays. The correlation for the Li8 decay was measured with average total beta energies, Wβ~5, 8, and 11 Mev. Both A and B were found to be approximately linear in Wβ. The correlation for the B8 decay was measured only with average Wβ~11 Mev. From the data with Wβ~11 Mev, the difference of the coefficients, B(Li8)-B(B8), equals (0.0070±0.0012)Wβ. This result is compared with theoretical predictions based on the older Fermi and the newer conserved vector current theories of beta decay. The experiment agrees with the prediction of the latter theory

Microscopic Black Hole Pairs in Highly-Excited States

We consider the quantum mechanics of a system consisting of two identical, Planck-size Schwarzschild black holes revolving around their common center of mass. We find that even in a very highly-excited state such a system has very sharp, discrete energy eigenstates, and the system performs very rapid transitions from a one stationary state to another. For instance, when the system is in the 100th excited state, the life times of the energy eigenstates are of the order of $10^{-30}$ s, and the energies of gravitons released in transitions between nearby states are of the order of $10^{22}$ eV.Comment: 22 pages, 3 figures, uses RevTe

Reliable Detection of Rotor Bars Breakage in Induction Motors via MUSIC and ZSC Methods

"(c) 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works"[EN] Induction motors are used in a variety of industrial applications where frequent startup cycles are required. In those cases, it is necessary to apply sophisticated signal processing analysis methods in order to reliably follow the time evolution of fault-related harmonics in the signal. In this paper, the zero-sequence current (ZSC) is analyzed using the high-resolution spectral method of multiple signal classification. The analysis of the ZSC signal has proved to have several advantages over the analysis of a single-phase current waveform. The method is validated through simulation and experimental results. The simulations are carried out for a 1.1-MW and a 4-kW induction motors under finite element analysis. Experimentation is performed on a healthy motor, a motor with one broken rotor bar, and a motor with two broken rotor bars. The analysis results are satisfactory since the proposed methodology reliably detects the broken rotor bar fault and its severity, both during transient and steady-state operation of the induction motor.This work was supported in part by the Spanish Ministerio de Economia y Competitividad (MINECO) and in part by the FEDER program in the framework of the Proyectos I+D del Subprograma de Generacion de Conocimiento, Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia under Grant DPI2014-52842-P.Morinigo-Sotelo, D.; Romero-Troncoso, R.; Panagiotou, P.; Antonino-Daviu, J.; Gyftakis, KN. (2018). Reliable Detection of Rotor Bars Breakage in Induction Motors via MUSIC and ZSC Methods. IEEE Transactions on Industry Applications. 54(2):1224-1234. https://doi.org/10.1109/TIA.2017.2764846S1224123454

Diagnosis of Broken Rotor Bars during the Startup of Inverter-Fed Induction Motors Using the Dragon Transform and Functional ANOVA

[EN] A proper diagnosis of the state of an induction motor is of great interest to industry given the great importance of the extended use of this motor. Presently, the use of this motor driven by a frequency converter is very widespread. However, operation by means of an inverter introduces certain difficulties for a correct diagnosis, which results in a signal with higher harmonic content and noise level, which makes it difficult to perform a correct diagnosis. To solve these problems, this article proposes the use of a time-frequency technique known as Dragon Transform together with the functional ANOVA statistical technique to carry out a proper diagnosis of the state of the motor by working directly with the curves obtained from the application of the transform. A case study is presented showing the good results obtained by applying the methodology in which the state of the rotor bars of an inverter-fed motor is diagnosed considering three failure states and operating at different load levels.This research has been partially funded by the University of Valladolid.Fernández-Cavero, V.; García-Escudero, LA.; Pons Llinares, J.; Fernández-Temprano, MA.; Duque-Perez, O.; Morinigo-Sotelo, D. (2021). Diagnosis of Broken Rotor Bars during the Startup of Inverter-Fed Induction Motors Using the Dragon Transform and Functional ANOVA. Applied Sciences. 11(9):1-12. https://doi.org/10.3390/app1109376911211

Comparison of the β-α Angular Correlations in Li8 and B8

Although the radiations following allowed β decay of unoriented nuclei are uncorrelated in angle with the β rays, forbidden effects may produce correlations of the form 1 + B cos^2 θ, where the small coefficient B depends on on the details of the matrix elements involved. As a possible test of the conserved vector current (C.V.C.) theory, various authors [2,3] have suggested a measurement of the difference, δ, of the B coefficients in the β-α correlations of the two decays: ....

Consortium corn-teak in crop-livestock-forest integration system in the state of Roraima.

Rapport over de kostprijsberekeningen van kersen en frambozen