LaTeX-保持参考文献英文字母的大小写不变

[解决问题]：在使用 $\text{[math]}$ 排版论文时候，参考文献部分会出现论文题目的第一个字符外的其他字符转换为小写，例如论文题目为：

A data-driven hybrid ARX and Markov chain modeling approach to process dentification with time-varying time delays

编译后PDF中显示为：

A data-driven hybrid arx and markov chain modeling approach to process identification with time-varying time delays

为保留原有大写字符，可以在 .bib 文件中将参考文献的标题部分使用左右大括号将需保留的字段括起来，或者可以直接将文章题目两端直接加大括号，这样会更加方便：
原格式为：

@article{zhao2016data,
  title={A data-driven hybrid ARX and Markov chain modeling approach to process identification with time-varying time delays},
  author={Zhao, Yujia and Fatehi, Alireza and Huang, Biao},
  journal={IEEE Transactions on Industrial Electronics},
  volume={64},
  number={5},
  pages={4226--4236},
  year={2016},
  publisher={IEEE}
}

修改后：

@article{zhao2016data,
  title={{A data-driven hybrid ARX and Markov chain modeling approach to process identification with time-varying time delays}},
  author={Zhao, Yujia and Fatehi, Alireza and Huang, Biao},
  journal={IEEE Transactions on Industrial Electronics},
  volume={64},
  number={5},
  pages={4226--4236},
  year={2016},
  publisher={IEEE}
}