Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Model of Sunspot Number with Modified Logistic Function   Solar cycles are studied with the Version 2 monthly smoothed international
sunspot number, the variations of which are found to be well represented by the
modified logistic differential equation with four parameters: maximum
cumulative sunspot number or total sunspot number $x_m$, initial cumulative
sunspot number $x_0$, maximum emergence rate $r_0$, and asymmetry $\alpha$. A
two-parameter function is obtained by taking $\alpha$ and $r_0$ as fixed value.
In addition, it is found that $x_m$ and $x_0$ can be well determined at the
start of a cycle. Therefore, a prediction model of sunspot number is
established based on the two-parameter function. The prediction for cycles
$4-23$ shows that the solar maximum can be predicted with average relative
error being 8.8\% and maximum relative error being 22\% in cycle 15 at the
start of solar cycles if solar minima are already known. The quasi-online
method for determining solar minimum moment shows that we can obtain the solar
minimum 14 months after the start of a cycle. Besides, our model can predict
the cycle length with the average relative error being 9.5\% and maximum
relative error being 22\% in cycle 4. Furthermore, we predict the sunspot
number variations of cycle 24 with the relative errors of the solar maximum and
ascent time being 1.4\% and 12\%, respectively, and the predicted cycle length
is 11.0 (95\% confidence interval is 8.3$-$12.9) years. The comparison to the
observation of cycle 24 shows that our prediction model has good effectiveness.

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The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph