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Finite element modelling and load share analysis for involute worm gears with localised tooth contact
A new approach has been developed by the authors to estimate the load share of worm gear drives, and to calculate the instantaneous tooth meshing stiffness and loaded transmission errors. In the approach, the finite element (FE) modelling is based on the modified tooth geometry, which ensures that the worm gear teeth are in localized contact. The geometric modelling method for involute worm gears allows the tooth elastic deformation and tooth root stresses of worm gear drives under different load conditions to be investigated. On the basis of finite element analysis, the instantaneous meshing stiffness and loaded transmission errors are obtained and the load share is predicted. In comparison with existing methods, this approach applies loaded tooth contact analysis and provides more accurate load capacity rating of worm gear drives
Nature of Quasielectrons and the Continuum of Neutral Bulk Excitations in the Laughlin Quantum Hall Fluids
We construct model wavefunctions for a family of single-quasielectron states
supported by the fractional quantum Hall (FQH) fluid. The charge
= quasielectron state is identified as a composite of a
charge- quasiparticle and a quasihole, orbiting around their
common center of charge with relative angular momentum , and
corresponds precisely to the "composite fermion" construction based on a filled
Landau level plus an extra particle in level . An effective
three-body model (one quasiparticle and two quasiholes) is
introduced to capture the essential physics of the neutral bulk excitations.Comment: 4 pages, 3 figs, minor modifications for the published versio
Dark matter and dark gauge fields
Following the unexpected theoretical discovery of a mass dimension one
fermionic quantum field of spin one half, we now present first results on two
_local_ versions. The Dirac and Majorana fields of the standard model of
particle physics are supplemented by their natural counterparts in the dark
matter sector. The possibility that a mass dimension transmuting symmetry may
underlie a new standard model of particle physics is briefly suggested.Comment: This manuscript combines a plenary talk (by DVA) and an invited talk
(by DS) at "Dark 2007 - Sixth International Heidelberg Conference on Dark
Matter in Astro and Particle Physics (Sydney, Australia, 24th-28th September
2007)." 11 pages. v2: minor typos correcte
Emergent states in heavy electron materials
We obtain the conditions necessary for the emergence of various low
temperature ordered states (local moment antiferromagnetism, unconventional
superconductivity, quantum criticality, and Landau Fermi liquid behavior) in
Kondo lattice materials by extending the two-fluid phenomenological theory of
heavy electron behavior to incorporate the concept of hybridization
effectiveness. We use this expanded framework to present a new phase digram and
consistent physical explanation and quantitative description of measured
emergent behaviors such as the pressure variation of the onset of local moment
antiferromagnetic ordering at T_N, the magnitude of the ordered moment, the
growth of superconductivity within that ordered state, the location of a
quantum critical point, and of a delocalization line in the
pressure/temperature phase diagram at which local moments have disappeared and
the heavy electron Fermi surface has grown to its maximum size. We apply our
model to CeRhIn_5 and a number of other heavy electron materials and find good
agreement with experiment.Comment: 20 pages, 8 figures, 1 tabl
Spinless Calogero-Sutherland model with twisted boundary condition
In this work, the spinless Calogero-Sutherland model with twisted boundary
condition is studied. The ground state wavefunctions, the ground state
energies, the full energy spectrum are provided in details.Comment: preprint of ETH-L, appearing in recent PR
Exactly solvable extended Hubbard model
In this work, we introduce long range version of the extended Hubbard model.
The system is defined on a non-uniform lattice. We show that the system is
integrable. The ground state, the ground state energies, the energy spectrum
are also found for the system. Another long range version of the extended
Hubbard model is also introduced on a uniform lattice, and this system is
proven to be integrable.Comment: 10 pages, Latex. Typoes are fixed in this revised versio
Effect of iron on the microstructure and mechanical property of Al-Mg-Si-Mn and Al-Mg-Si diecast alloys
This article is made available through the Brunel Open Access Publishing Fund. Copyright @ 2012 Elsevier B.V.This article has been made available through the Brunel Open Access Publishing Fund.AlāMgāSi based alloys can provide super ductility to satisfy the demands of thin wall castings in the application of automotive structure. In this work, the effect of iron on the microstructure and mechanical properties of the AlāMgāSi diecast alloys with different Mn concentrations is investigated. The CALPHAD (acronym of Calculation of Phase Diagrams) modelling with the thermodynamic properties of the multi-component AlāMgāSiāMnāFe and AlāMgāSiāFe systems is carried out to understand the role of alloying on the formation of different primary Fe-rich intermetallic compounds. The results showed that the Fe-rich intermetallic phases precipitate in two solidification stages in the high pressure die casting process: one is in the shot sleeve and the other is in the die cavity, resulting in the different morphologies and sizes. In the AlāMgāSiāMn alloys, the Fe-rich intermetallic phase formed in the shot sleeve exhibited coarse compact morphology and those formed in the die cavity were fine compact particles. Although with different morphologies, the compact intermetallics were identified as the same Ī±-AlFeMnSi phase with typical composition of Al24(Fe,Mn)6Si2. With increased Fe content, Ī²-AlFe was found in the microstructure with a long needle-shaped morphology, which was identified as Al13(Fe,Mn)4Si0.25. In the AlāMgāSi alloy, the identified Fe-rich intermetallics included the compact Ī±-AlFeSi phase with typical composition of Al8Fe2Si and the needle-shaped Ī²-AlFe phase with typical composition of Al13Fe4. Generally, the existence of iron in the alloy slightly increases the yield strength, but significantly reduces the elongation. The ultimate tensile strength maintains at similar levels when Fe contents is less than 0.5 wt%, but decreases significantly with the further increased Fe concentration in the alloys. CALPHAD modelling shows that the addition of Mn enlarges the Fe tolerance for the formation of Ī±-AlFeMnSi intermetallics and suppresses the formation of Ī²-AlFe phase in the AlāMgāSi alloys, and thus improves their mechanical properties.EPSRC and JL
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