Liang-Chieh (Jay) Chen- Home Page

Liang-Chieh Chen
Research Scientist, ByteDance, Los Angeles

Email: lcchen at cs dot ucla dot edu

About me

I am currently a Research Scientist at ByteDance / TikTok. My research interests include Computer Vision, and Deep Learning.

Before joining ByteDance, I was a Research Scientist at Google, Los Angeles. I received my Ph.D. in Computer Science at UCLA under the supervision of Alan L. Yuille.

News

For motivated Ph.D. students looking for internships or full-time positions, feel free to contact me for details. Our team works on fundamental research on visual recognition, representation learning, and deep learning.

MaXTron, a simple, strong, and efficient video segmenter, is open-source in PyTorch!

FC-CLIP, a simple, strong, and efficient open-vocabulary segmenter, is open-source in PyTorch!

Re-implementation of kMaX-DeepLab in PyTorch is open-source!

Papers

MaXTron: Mask Transformer with Trajectory Attention for Video Panoptic Segmentation
Ju He, Qihang Yu, Inkyu Shin, Xueqing Deng, Xiaohui Shen, Alan Yuille, Liang-Chieh Chen
Technical report
[preprint (arxiv: 2311.18537)] [PyTorch code]

Towards Open-Ended Visual Recognition with Large Language Model
Qihang Yu, Xiaohui Shen, Liang-Chieh Chen
Technical report
[preprint (arxiv: 2311.08400)] [PyTorch code]

PolyMaX: General Dense Prediction with Mask Transformer
Xuan Yang, Liangzhe Yuan, Kimberly Wilber, Astuti Sharma, Xiuye Gu, Siyuan Qiao, Stephanie Debats, Huisheng Wang, Hartwig Adam, Mikhail Sirotenko, Liang-Chieh Chen
In Winter Conference on Applications of Computer Vision (WACV), Waikoloa, Hawaii, USA, January 2024.
[preprint (arxiv: 2311.05770)]

Superpixel Transformers for Efficient Semantic Segmentation
Alex Zihao Zhu, Jieru Mei, Siyuan Qiao, Hang Yan, Yukun Zhu, Liang-Chieh Chen, Henrik Kretzschmar
In International Conference on Intelligent Robots and Systems (IROS), Detroit, Michigan, USA, October 2024
[preprint (arxiv: 2309.16889)]

Convolutions Die Hard: Open-Vocabulary Segmentation with Single Frozen Convolutional CLIP
Qihang Yu, Ju He, Xueqing Deng, Xiaohui Shen, Liang-Chieh Chen
In Neural Information Processing Systems (NeurIPS), New Orleans, Louisiana, USA, December 2024
[preprint (arxiv: 2308.02487)] [PyTorch code]

ReMaX: Relaxing for Better Training on Efficient Panoptic Segmentation
Shuyang Sun, Weijun Wang, Qihang Yu, Andrew Howard, Philip Torr, Liang-Chieh Chen
In Neural Information Processing Systems (NeurIPS), New Orleans, Louisiana, USA, December 2024
[preprint (arxiv: 2306.17319)]

DaTaSeg: Taming a Universal Multi-Dataset Multi-Task Segmentation Model
Xiuye Gu, Yin Cui, Jonathan Huang, Abdullah Rashwan, Xuan Yang, Xingyi Zhou, Golnaz Ghiasi, Weicheng Kuo, Huizhong Chen, Liang-Chieh Chen, David Ross
In Neural Information Processing Systems (NeurIPS), New Orleans, Louisiana, USA, December 2024
[preprint (arxiv: 2306.01736)]

A Study of Autoregressive Decoders for Multi-Tasking in Computer Vision
Lucas Beyer, Bo Wan, Gagan Madan, Filip Pavetic, Andreas Steiner, Alexander Kolesnikov, Andre Susano Pinto, Emanuele Bugliarello, Xiao Wang, Qihang Yu, Liang-Chieh Chen, Xiaohua Zhai
Technical report
[preprint (arxiv: 2303.17376)]

Video-kMaX: A Simple Unified Approach for Online and Near-Online Video Panoptic Segmentation
Inkyu Shin, Dahun Kim, Qihang Yu, Jun Xie, Hong-Seok Kim, Bradley Green, In So Kweon, Kuk-Jin Yoon, Liang-Chieh Chen
Full version appeared in Winter Conference on Applications of Computer Vision (WACV), Waikoloa, Hawaii, USA, January 2024. (oral)
Short version appeared in CVPR 2023 T4V (Transformers for Vision) workshop, Vancouver, Canada, June 2023. (spotlight)
[preprint (arxiv: 2304.04694)]

MOAT: Alternating Mobile Convolution and Attention Brings Strong Vision Models
Chenglin Yang, Siyuan Qiao, Qihang Yu, Xiaoding Yuan, Yukun Zhu, Alan Yuille, Hartwig Adam, Liang-Chieh Chen
International Conference on Learning Representations (ICLR), Kigali, Rwanda, May 2023.
[preprint (arxiv: 2210.01820)] [code]

k-means Mask Transformer
Qihang Yu, Huiyu Wang, Siyuan Qiao, Maxwell Collins, Yukun Zhu, Hartwig Adam, Alan Yuille, Liang-Chieh Chen
In European Conference on Computer Vision (ECCV), Tel Aviv, Israel, October 2022.
[preprint (arxiv: 2207.04044)] [TensorFlow2 code] [Google AI Blog post] [PyTroch code]

Waymo Open Dataset: Panoramic Video Panoptic Segmentation
Jieru Mei, Alex Zihao Zhu, Xinchen Yan, Hang Yan, Siyuan Qiao, Yukun Zhu, Liang-Chieh Chen, Henrik Kretzschmar, Dragomir Anguelov
In European Conference on Computer Vision (ECCV), Tel Aviv, Israel, October 2022.
[preprint (arxiv: 2206.07704)] [dataset]

CMT-DeepLab: Clustering Mask Transformers for Panoptic Segmentation (oral)
Qihang Yu, Huiyu Wang, Dahun Kim, Siyuan Qiao, Maxwell Collins, Yukun Zhu, Hartwig Adam, Alan Yuille, Liang-Chieh Chen
In Conference on Computer Vision and Pattern Recognition (CVPR), New Orleans, Louisiana, USA, June 2022.
[preprint (arxiv: 2206.08948)] [talk]

TubeFormer-DeepLab: Video Mask Transformer
Dahun Kim, Jun Xie, Huiyu Wang, Siyuan Qiao, Qihang Yu, Hong-Seok Kim, Hartwig Adam, In So Kweon, Liang-Chieh Chen
In Conference on Computer Vision and Pattern Recognition (CVPR), New Orleans, Louisiana, USA, June 2022.
[preprint (arxiv: 2205.15361)] [video-prediction-results]

DeepLab2: A TensorFlow Library for Deep Labeling
Mark Weber*, Huiyu Wang*, Siyuan Qiao*, Jun Xie, Maxwell Collins, Yukun Zhu, Liangzhe Yuan, Dahun Kim, Qihang Yu,
Daniel Cremers, Laura Leal-Taixe, Alan Yuille, Florian Schroff, Hartwig Adam, Liang-Chieh Chen
(*equal contribution)
Technical report
[preprint (arxiv: 2106.09748)] [DeepLab2 code] [Talk at ICCV 2021 VSPW workshop]

STEP: Segmenting and Tracking Every Pixel
Mark Weber, Jun Xie, Maxwell Collins, Yukun Zhu, Paul Voigtlaender, Hartwig Adam, Bradley Green, Andreas Geiger,
Bastian Leibe, Daniel Cremers, Aljosa Osep, Laura Leal-Taixe, Liang-Chieh Chen
In Neural Information Processing Systems (NeurIPS) Track on Datasets and Benchmarks, Virtual, December 2021.
[preprint (arxiv: 2102.11859)] [DeepLab2 code] [STQ numpy code] [KITTI-STEP] [MOTChallenge-STEP]

ViP-DeepLab: Learning Visual Perception with Depth-aware Video Panoptic Segmentation
Siyuan Qiao, Yukun Zhu, Hartwig Adam, Alan Yuille, Liang-Chieh Chen
In Conference on Computer Vision and Pattern Recognition (CVPR), Virtual, June 2021.
[preprint (arxiv: 2012.05258)] [video demo] [dataset and evaluation code] [DeepLab2 code] [Google AI Blog post]

MaX-DeepLab: End-to-End Panoptic Segmentation with Mask Transformers
Huiyu Wang, Yukun Zhu, Hartwig Adam, Alan Yuille, Liang-Chieh Chen
In Conference on Computer Vision and Pattern Recognition (CVPR), Virtual, June 2021.
[preprint (arxiv: 2012.00759)] [DeepLab2 code] [Google AI Blog post]

Scaling Wide Residual Networks for Panoptic Segmentation
Liang-Chieh Chen, Huiyu Wang, Siyuan Qiao
Technical report
[preprint (arxiv: 2011.11675)] [DeepLab2 code]

View-Invariant, Occlusion-Robust Probabilistic Embedding for Human Pose
Ting Liu, Jennifer J. Sun, Long Zhao, Jiaping Zhao, Liangzhe Yuan, Yuxiao Wang, Liang-Chieh Chen, Florian Schroff, Hartwig Adam
International Journal of Computer Vision (IJCV)
[preprint (arxiv: 2010.13321)]

DetectoRS: Detecting Objects with Recursive Feature Pyramid and Switchable Atrous Convolution
Siyuan Qiao, Liang-Chieh Chen, Alan Yuille
In Conference on Computer Vision and Pattern Recognition (CVPR), Virtual, June 2021.
[preprint (arxiv: 2006.02334)] [code]

Naive-Student: Leveraging Semi-Supervised Learning in Video Sequences for Urban Scene Segmentation
Liang-Chieh Chen, Raphael Gontijo Lopes, Bowen Cheng, Maxwell D. Collins, Ekin D. Cubuk, Barret Zoph, Hartwig Adam, Jonathon Shlens
In European Conference on Computer Vision (ECCV), Glasgow, United Kingdom (Virtual), August 2020.
[preprint (arxiv: 2005.10266)]

Axial-DeepLab: Stand-Alone Axial-Attention for Panoptic Segmentation (spotlight)
Huiyu Wang, Yukun Zhu, Bradley Green, Hartwig Adam, Alan Yuille, Liang-Chieh Chen
In European Conference on Computer Vision (ECCV), Glasgow, United Kingdom (Virtual), August 2020.
[preprint (arxiv: 2003.07853)] [unofficial PyTorch re-implementation] [video]
[DeepLab2 code (official implementation)] [Google AI Blog post]

View-Invariant Probabilistic Embedding for Human Pose (spotlight)
Jennifer J. Sun, Jiaping Zhao, Liang-Chieh Chen, Florian Schroff, Hartwig Adam, Ting Liu
In European Conference on Computer Vision (ECCV), Glasgow, United Kingdom (Virtual), August 2020.
[preprint (arxiv: 1912.01001)] [Google AI Blog post]

Panoptic-DeepLab: A Simple, Strong, and Fast Baseline for Bottom-Up Panoptic Segmentation
Bowen Cheng, Maxwell D. Collins, Yukun Zhu, Ting Liu, Thomas S. Huang, Hartwig Adam, Liang-Chieh Chen
In Conference on Computer Vision and Pattern Recognition (CVPR), Virtual, June 2020.
[preprint (arxiv: 1911.10194)] [unofficial PyTorch re-implementation] [Detectron2/projects/Panoptic-DeepLab (unofficial re-implementation)]
[DeepLab2 code (official implementation)] [Google AI-Blog post]

Panoptic-DeepLab
Bowen Cheng, Maxwell D. Collins, Yukun Zhu, Ting Liu, Thomas S. Huang, Hartwig Adam, Liang-Chieh Chen
In ICCV 2019 Joint COCO and Mapillary Recognition Challenge Workshop.
Best result, best paper and most innovative awards on Mapillary Vistas Panoptic Segmentation track.
[preprint (arxiv: 1910.04751)]

SegSort: Segmentation by Discriminative Sorting of Segments
Jyh-Jing Hwang, Stella X. Yu, Jianbo Shi, Maxwell Collins, Tien-Ju Yang, Xiao Zhang, Liang-Chieh Chen
In International Conference on Computer Vision (ICCV), Seoul, Korea, October 2019.
[preprint (arxiv: 1910.06962)] [website and code]

SPGNet: Semantic Prediction Guidance for Scene Parsing
Bowen Cheng, Liang-Chieh Chen, Yunchao Wei, Yukun Zhu, Zilong Huang, Jinjun Xiong, Thomas Huang, Wen-Mei Hwu, Honghui Shi
In International Conference on Computer Vision (ICCV), Seoul, Korea, October 2019.
[preprint (arxiv: 1908.09798)]

Searching for MobileNetV3 (oral)
Andrew Howard, Mark Sandler, Grace Chu, Liang-Chieh Chen, Bo Chen, Mingxing Tan, Weijun Wang, Yukun Zhu, Ruoming Pang, Vijay Vasudevan, Quoc V. Le, Hartwig Adam
In International Conference on Computer Vision (ICCV), Seoul, Korea, October 2019.
[preprint (arxiv: 1905.02244)] [code for (image classification), (object detection), and (semantic segmentation)] [Google AI Blog post]

FEELVOS: Fast End-to-End Embedding Learning for Video Object Segmentation
Paul Voigtlaender, Yuning Chai, Florian Schroff, Hartwig Adam, Bastian Leibe, Liang-Chieh Chen
In Conference on Computer Vision and Pattern Recognition (CVPR), Long Beach, California, USA, June 2019.
[preprint (arxiv: 1902.09513)] [code]

DeeperLab: Single-Shot Image Parser
Tien-Ju Yang, Maxwell D. Collins, Yukun Zhu, Jyh-Jing Hwang, Ting Liu, Xiao Zhang, Vivienne Sze, George Papandreou, Liang-Chieh Chen
Technical report
[preprint (arxiv: 1902.05093)] [evaluation code]

Auto-DeepLab: Hierarchical Neural Architecture Search for Semantic Image Segmentation (oral)
Chenxi Liu, Liang-Chieh Chen, Florian Schroff, Hartwig Adam, Wei Hua, Alan Yuille, Li Fei-Fei
In Conference on Computer Vision and Pattern Recognition (CVPR), Long Beach, California, USA, June 2019.
[preprint (arxiv: 1901.02985)] [code]

The Devil is in the Decoder: Classification, Regression and GANs
Zbigniew Wojna, Vittorio Ferrari, Sergio Guadarrama, Nathan Silberman, Liang-Chieh Chen, Alireza Fathi, Jasper Uijlings
International Journal of Computer Vision (IJCV)
[preprint (arxiv: 1707.05847)]

Searching for Efficient Multi-Scale Architectures for Dense Image Prediction
Liang-Chieh Chen, Maxwell D. Collins, Yukun Zhu, George Papandreou, Barret Zoph, Florian Schroff, Hartwig Adam, Jonathon Shlens
In Neural Information Processing Systems (NeurIPS), Montréal, Canada, December 2018.
[preprint (arxiv: 1809.04184)] [code] [poster]

PersonLab: Person Pose Estimation and Instance Segmentation with a Bottom-Up, Part-Based, Geometric Embedding Model
George Papandreou, Tyler Zhu, Liang-Chieh Chen, Spyros Gidaris, Jonathan Tompson, Kevin Murphy
In European Conference on Computer Vision (ECCV), Munich, Germany, September 2018.
[preprint (arxiv: 1803.08225)]

Encoder-Decoder with Atrous Separable Convolution for Semantic Image Segmentation
Liang-Chieh Chen, Yukun Zhu, George Papandreou, Florian Schroff, Hartwig Adam
In European Conference on Computer Vision (ECCV), Munich, Germany, September 2018.
[preprint (arxiv: 1802.02611)] [code] [Google AI Blog post]

MobileNetV2: Inverted Residuals and Linear Bottlenecks
Mark Sandler, Andrew Howard, Menglong Zhu, Andrey Zhmoginov, Liang-Chieh Chen
In Conference on Computer Vision and Pattern Recognition (CVPR), Salt Lake City, Utah, USA, June 2018.
[preprint (arxiv: 1801.04381)] [code] [Google AI Blog post]

MaskLab: Instance Segmentation by Refining Object Detection with Semantic and Direction Features
Liang-Chieh Chen, Alexander Hermans, George Papandreou, Florian Schroff, Peng Wang, Hartwig Adam
In Conference on Computer Vision and Pattern Recognition (CVPR), Salt Lake City, Utah, USA, June 2018.
[preprint (arxiv: 1712.04837)]

The Devil is in the Decoder
Zbigniew Wojna, Vittorio Ferrari, Sergio Guadarrama, Nathan Silberman, Liang-Chieh Chen, Alireza Fathi, Jasper Uijlings
In British Machine Vision Conference (BMVC), Imperial College London, September 2017.
[preprint (arxiv: 1707.05847)]

Rethinking Atrous Convolution for Semantic Image Segmentation
Liang-Chieh Chen, George Papandreou, Florian Schroff, Hartwig Adam
Technical report
[preprint (arxiv: 1706.05587)] [code]

DeepLab: Semantic Image Segmentation with Deep Convolutional Nets, Atrous Convolution, and Fully Connected CRFs
Liang-Chieh Chen*, George Papandreou*, Iasonas Kokkinos, Kevin Murphy, Alan L. Yuille (*equal contribution)
Transactions on Pattern Analysis and Machine Intelligence (TPAMI)
[preprint (arxiv: 1606.00915)] [project] [code]

Zoom Better to See Clearer: Human Part Segmentation with Auto Zoom Net
Fangting Xia, Peng Wang, Liang-Chieh Chen, Alan L. Yuille
In European Conference on Computer Vision (ECCV), Amsterdam, Netherlands, October 2016.
[preprint (arxiv: 1511.06881)]

Semantic Image Segmentation with Task-Specific Edge Detection Using CNNs and a Discriminatively Trained Domain Transform
Liang-Chieh Chen, Jonathan T. Barron, George Papandreou, Kevin Murphy, Alan L. Yuille
In Conference on Computer Vision and Pattern Recognition (CVPR), Las Vegas, Nevada, USA, June 2016.
[preprint (arxiv: 1511.03328)] [project] [code]

Attention to Scale: Scale-aware Semantic Image Segmentation
Liang-Chieh Chen, Yi Yang, Jiang Wang, Wei Xu, Alan L. Yuille
In Conference on Computer Vision and Pattern Recognition (CVPR), Las Vegas, Nevada, USA, June 2016.
[preprint (arxiv: 1511.03339)] [Test results on subset of MPII] [project] [code] [PASCAL-Person-Part dataset] [PASCAL-Person-Part original webiste]

ABC-CNN: An Attention Based Convolutional Neural Network for Visual Question Answering
Kan Chen, Jiang Wang, Liang-Chieh Chen, Haoyuan Gao, Wei Xu, Ram Nevatia
Technical Report
[preprint (arxiv: 1511.05960)]

Weakly- and Semi-Supervised Learning of a Deep Convolutional Network for Semantic Image Segmentation
George Papandreou*, Liang-Chieh Chen*, Kevin Murphy, Alan L. Yuille
(*equal contribution)
International Conference on Computer Vision (ICCV), Santiago, Chile, December 2015.
[preprint (arxiv: 1502.02734)] [spotlight] [project] [code]

Learning Deep Structured Models (oral)
Liang-Chieh Chen*, Alexander G. Schwing*, Alan L. Yuille, Raquel Urtasun
(*equal contribution)
International Conference on Machine Learning (ICML), Lille, France, July 2015.
[pdf] [talk]

Semantic Image Segmentation with Deep Convolutional Nets and Fully Connected CRFs
Liang-Chieh Chen*, George Papandreou*, Iasonas Kokkinos, Kevin Murphy, Alan L. Yuille
(*equal contribution)
International Conference on Learning Representations (ICLR), San Diego, California, USA, May 2015.
[preprint (arXiv:1412.7062)] [project] [code]

Beat the MTurkers: Automatic Image Labeling from Weak 3D Supervision
Liang-Chieh Chen, Sanja Fidler, Alan L. Yuille, Raquel Urtasun
In Conference on Computer Vision and Pattern Recognition (CVPR), Columbus, Ohio, USA, June 2014.
[pdf] [Supplementary Doc] [project] [CAD models]

Modeling Image Patches with a Generic Dictionary of Mini-Epitomes
George Papandreou, Liang-Chieh Chen, Alan L. Yuille
In Conference on Computer Vision and Pattern Recognition (CVPR), Columbus, Ohio, USA, June 2014.
[pdf] [Supplementary Doc]

Learning a Dictionary of Shape Epitomes with Applications to Image Labeling
Liang-Chieh Chen, George Papandreou, Alan L. Yuille
In International Conference on Computer Vision (ICCV), Sydney, Australia, Dec. 2013.
[pdf] [Supplementary Doc]

Activities

Area Chair for ICCV 2019, CVPR 2020, 2023, 2024, ECCV 2020, 2024, NeurIPS 2022.

Reviewer for CVPR, ECCV, ICCV, NeurIPS.

Interns whom I had the pleasure to work with

While at ByteDance / TikTok:

Jieneng Chen in Summer 2023. Ph.D. student at JHU.
Hosted with Qihang Yu, and Xueqing Deng.

Zhanpeng Zeng in Summer 2023. Ph.D. student at University of Wisconsin-Madison.
Hosted with Qihang Yu, Xueqing Deng, and Peng Wang.

Ju He in Spring 2023. Ph.D. student at JHU.
Hosted with Qihang Yu, and Xueqing Deng.

While at Google:

Shuyang Sun in Fall 2022. Ph.D. student at University of Oxford.
Hosted with Weijun Wang.

Inkyu Shin in Summer 2022. Ph.D. student at KAIST.
Hosted with Jun Xie, and Dahun Kim.

Chenglin Yang in Summer 2022. Ph.D. student at JHU.
Hosted with Siyuan Qiao, and Yukun Zhu.

Jieru Mei in Spring 2022. Ph.D. student at JHU.
Hosted with Alex Zihao Zhu, Xinchen Yan, and Hang Yan.

Dahun Kim in Summer 2021. Finished Ph.D. at KAIST. Now at Google.
Hosted with Jun Xie.

Qihang Yu in Summer 2021. Ph.D. student at JHU.
Hosted with Maxwell Collins, and Yukun Zhu.

Mark Weber in Summer 2020. Ph.D. student at TUM.
Hosted with Jun Xie.

Siyuan Qiao in Summer 2020. Finished Ph.D. at JHU. Now at Google.
Hosted with Yukun Zhu.

Huiyu Wang in Summer 2019 and 2020. Finished Ph.D. at JHU. Now at Facebook.
Hosted with Yukun Zhu.

Jennifer Sun in Summer 2019. Currently: Ph.D. student at Caltech.
Hosted with Ting Liu.

Colin Graber in Summer 2019. Currently: Ph.D. student at UIUC.
Hosted with Michalis Raptis.

Bowen Cheng in Summer 2019. Finished Ph.D. student at UIUC. Now at Tesla.
Hosted with Yukun Zhu.

Chenxi Liu in Summer 2018. Finished Ph.D. at JHU. Now at Waymo.
Hosted with Wei Hua, and Li Fei-Fei.

Mason Liu in Summer 2018. Currently: Ph.D. student at Cornell.
Hosted with Ting Liu.

Paul Voiglaender in Summer 2018. Finished Ph.D. at RWTH Aachen University. Now at Google.
Hosted with Yuning Chai.

Tien-Ju Yang in Summer 2018. Finished Ph.D. at MIT. Now at Google.
Hosted with Xiao Zhang.

Jyh-Jing Hwang in Summer 2018. Finished Ph.D. at UPenn. Now at Waymo.
Hosted with Maxwell Collins.

Alexander Hermans in Summer 2017. Finished Ph.D. at RWTH Aachen University.
Hosted with Chao-Yeh Chen.

US Patents

Generating Panoptic Segmentation Labels, 2023
Jieru Mei, Hang Yan, Liang-Chieh Chen, Siyuan Qiao, Yukun Zhu, Alex Zihao Zhu, Xinchen Yan, Henrik Kretzschmar

Neural Architecture Search for Dense Image Prediction Tasks, 2018
Liang-Chieh Chen, Maxwell D. Collins, Yukun Zhu, George Papandreou, Barret Zoph, Florian Schroff, Hartwig Adam, and Jonathon Shlens.

Instance Segmentation, 2018
Liang-Chieh Chen, Alexander Hermans, George Papandreou, Florian Schroff, Peng Wang, and Hartwig Adam.

Highly Efficient Convolutional Neural Networks, 2018
Mark Sandler, Andrew Howard, Menglong Zhu, Andrey Zhmoginov, and Liang-Chieh Chen.

Systems and Methods for Data Page Management of NAND Flash Memory Arrangements, November 2008
Liang-Chieh Chen and Xueshi Yang

Multi-Mode Encoding for Data Compression, February 2009
Liang-Chieh Chen and Xueshi Yang