Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Second Order Step by Step Sliding mode Observer for Fault Estimation in
  a Class of Nonlinear Fractional Order Systems   This paper considers fault estimation in nonlinear fractional order systems
in observer form. For this aim, a step by step second order sliding mode
observer is used. By means of a fractional inequality, the stability of the
observer estimation errors is analyzed and some conditions are introduced to
guarantee finite time convergence of estimation errors. Finally, in a numerical
example, effectiveness of this observer is demonstrated.

17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an