Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Instantaneous time mirrors and wave equations with time-singular
  coefficients   We study in this work the concept of instantaneous time mirrors that were
recently introduced in the physics literature. Instantaneous time mirrors offer
a new method for time reversal with a simplified experimental setup compared to
classical techniques. At the mathematical level, instantaneous time mirrors are
modeled by singularities in the time variable in the coefficients of a wave
equation, and a prototype of such singularity is a Dirac delta. Our main goal
in this work is to obtain refocusing estimates for the wavefield that quantify
the quality of time reversal. This amounts to analyze the wave equation with
Dirac-type singularities and develop a proper regularity theory as well as
derive uniform estimates.

19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
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The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys