1,686 research outputs found
Compression for Smooth Shape Analysis
Most 3D shape analysis methods use triangular meshes to discretize both the
shape and functions on it as piecewise linear functions. With this
representation, shape analysis requires fine meshes to represent smooth shapes
and geometric operators like normals, curvatures, or Laplace-Beltrami
eigenfunctions at large computational and memory costs.
We avoid this bottleneck with a compression technique that represents a
smooth shape as subdivision surfaces and exploits the subdivision scheme to
parametrize smooth functions on that shape with a few control parameters. This
compression does not affect the accuracy of the Laplace-Beltrami operator and
its eigenfunctions and allow us to compute shape descriptors and shape
matchings at an accuracy comparable to triangular meshes but a fraction of the
computational cost.
Our framework can also compress surfaces represented by point clouds to do
shape analysis of 3D scanning data
Optimization of perturbative similarity renormalization group for Hamiltonians with asymptotic freedom and bound states
A model Hamiltonian that exhibits asymptotic freedom and a bound state, is
used to show on example that similarity renormalization group procedure can be
tuned to improve convergence of perturbative derivation of effective
Hamiltonians, through adjustment of the generator of the similarity
transformation. The improvement is measured by comparing the eigenvalues of
perturbatively calculated renormalized Hamiltonians that couple only a
relatively small number of effective basis states, with the exact bound state
energy in the model. The improved perturbative calculus leads to a few-percent
accuracy in a systematic expansion.Comment: 6 pages of latex, 4 eps figure
Session-state Reveal is stronger than Ephemeral Key Reveal: Attacking the NAXOS Authenticated Key Exchange protocol
In the papers Stronger Security of Authenticated Key Exchange [LLM07, LLM06], a new security model for key exchange protocols is proposed. The new model is suggested to be at least as strong as previous models for key exchange protocols. In particular, the model includes a new notion of an Ephemeral Key Reveal adversary query, which is claimed in [LLM06, Oka07, Ust08] to be at least as strong as existing definitions of the Session-state Reveal query. We show that for some protocols, Session-state Reveal is strictly stronger than Ephemeral Key Reveal. In particular, we show that the NAXOS protocol from [LLM07, LLM06] does not meet its security requirements if the Session-state Reveal query is allowed in the security model
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