This author has not been identified. Look up 'Na Liu' in GoogleThis author has not been identified. Look up 'Xiangyu Zhang' in GoogleThis author has not been identified. It may be one of the following persons: Look up 'Lin Zhang' in GoogleThis author has not been identified. Look up 'Deyong Shang' in GoogleThis author has not been identified. Look up 'Yin-Fan Xu' in Google