1,224 research outputs found
Computing HF^ by factoring mapping classes
Bordered Heegaard Floer homology is an invariant for three-manifolds with
boundary. In particular, this invariant associates to a handle decomposition of
a surface F a differential graded algebra, and to an arc slide between two
handle decompositions, a bimodule over the two algebras. In this paper, we
describe these bimodules for arc slides explicitly, and then use them to give a
combinatorial description of HF^ of a closed three-manifold, as well as the
bordered Floer homology of any 3-manifold with boundary.Comment: 106 pages, 46 figure
A refinement of Rasmussen's s-invariant
In a previous paper we constructed a spectrum-level refinement of Khovanov
homology. This refinement induces stable cohomology operations on Khovanov
homology. In this paper we show that these cohomology operations commute with
cobordism maps on Khovanov homology. As a consequence we obtain a refinement of
Rasmussen's slice genus bound s for each stable cohomology operation. We show
that in the case of the Steenrod square Sq^2 our refinement is strictly
stronger than s.Comment: 26 pages, 2 figure
Modified face seal for positive film stiffness
The film stiffness of a face seal is improved without increasing the sealing and dam area by using an apparatus which includes a primary seal ring in the form of a nose piece. A spring forces a sealing surface on the seal ring into sealing contact with a seat to form a face seal. A circumferential clearance seal is formed in series with this face seal by a lip on the piece. The width of the surface of the lip is substantially the same as the width of the sealing surface on the face seal and the clearance between the surface on the lip and the shaft is substantially the same as the spacing between the face sealing surfaces on the face seal when the shaft is rotating. The circumferential clearance seal restricts the flow of fluid from a main cavity to an intermediate cavity with a resulting pressure drop. The hydrostatic opening face is strongly dependent on the face seal clearance, and the desired axial stiffness is achieved
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