Permanent magnet linear synchronous motor (PMLSM), which has the advantages of simple structure, small volume, high force, is a research focus and difficulties because of the thrust ripple and control problems for PMLSM. In this paper, in order to reduce thrust ripple and improve system control performance, the space voltage vector pulse width modulation technology (SVPWM) was introduced into t...

The energy density of the vacuum, Λ, is at least 60 orders of magnitude smaller than several known contributions to it. Approaches to this problem are tightly constrained by data ranging from elementary observations to precision experiments. Absent overwhelming evidence to the contrary, dark energy can only be interpreted as vacuum energy, so the venerable assumption that Λ = 0 conflicts with o...

We propose a new mechanism of leptogenesis in which the asymmetries in lepton numbers are produced through the CP-violating oscillations of “sterile” (electroweak singlet) neutrinos. The asymmetry is communicated from singlet neutrinos to ordinary leptons through their Yukawa couplings. The lepton asymmetry is then reprocessed into baryon asymmetry by electroweak sphalerons. We show that the ob...

String theory axions appear to be promising candidates for explaining cosmological constant via quintessence. In this paper, we study conditions on the string compactifications under which axion quintessence can happen. For sufficiently large number of axions, cosmological constant can be accounted for as the potential energy of axions that have not yet relaxed to their minima. In compactificat...

Jesus College, Cambridge; [email protected] ABSTRACT A mechanism is suggested whereby thermonuclear energy released in Big Bang nucleosynthesis may lead to the formation of galaxies and large scale structure within a very short time period. This would perturb Friedmann cosmology and lead to a fractal Voronoi geometry. The true rate of expansion would be substantially below the observe...

Four ROSAT X-ray observations of the secondary optical minimum of the eclipsing binary system α CrB taken in 1992, 1993 and 1997 are presented. Because of the totality of the X-ray eclipse, the times of mid eclipse can be accurately determined from the ROSAT data. The period between secondary minima Ps is found to be significantly different from the optically well determined period between prim...

For the purpose of coping with the affluence of information available over the Internet, an efficient, accurate and user-friendly system for information retrieval is mandatory. This paper presents an intelligent system based on the use of spoken dialogue as the main channel for usersystem interface, use of key concepts, processing of unknown words, automatic acquisition of various kinds of know...

Dr. Carl S. Haegler. Translated by Charles Heron Watson, M.A., M.B. (Edin.). Pp. xix., 218. Edinburgh and London: William Green & Sons. 1906. Until the present work was published, we believe there was but one book of importance in the English language which dealt in a thorough manner with the subject of the disinfection of the hands, though in the German language there are many. For this reason...

In this paper, the possible realization of the electromagnetic (EM) absorber as a thin metasurface is considered. The metasurface is based on establishing a passive surface of electric and magnetic currents using the Huygen’s principle. So, the absorber is named Huygens Absorber (HA). The metasurface can be designed using split meander lines with spiral rings. In this way, both sides of the sub...

The paper addresses realization theory of discrete-time linear hybrid systems without guards (abbreviated by DTHLS ). We present necessary and sufficient conditions for existence of a realization, and a characterization of minimality. In addition, we present basic results on partial realization theory of DTHLSs along with a realization algorithm. We also sketch the application of the obtained r...