Preface: special issue on uncertainty quantification and its applications

Well-Posedness and Finite Element Approximations for Elliptic SPDEs with Gaussian Noises 
Yanzhao Cao, Jialin Hong & Zhihui Liu

Sparse Approximation of Data-Driven Polynomial Chaos Expansions: An Induced Sampling Approach 
Ling Guo, Akil Narayan, Yongle Liu & Tao Zhou

A Multiscale Multilevel Monte Carlo Method for Multiscale Elliptic PDEs with Random Coefficients 
Junlong Lyu & Zhiwen Zhang 

Stochastic Second-Order Two-Scale Method for Predicting the Mechanical Properties of Composite Materials with Random Interpenetrating Phase 
Hao Dong, Zihao Yang, Xiaofei Guan & Zhiqiang Yang 

An Ensemble Kalman Filter Approach Based on Level Set Parameterization for Acoustic Source Identification Using Multiple Frequency Information 
Xiao-Mei  Yang, Zhi-Liang Deng & Juan-Fang Wang  

Meshfree Finite Volume Element Method for Constrained Optimal Control Problem Governed by Random Convection Diffusion Equations 
Liang  Ge, Wanfang Shen & Wenbin Liu