Research

Beauty of Math

Hoeffding's Inequality and MartingalesDec 2022

In this article we present the Hoeffding's Inequality and its proof. To do so, we first go through the Hoeffding's Lemma and Markov's Inequality. Also, we introduce the concept of Martingales and related Azuma-Hoeffding inequality. [PDF]

Research Experience

Adversarially Robust DPOJan 2026 - Present

Supervised by Prof. Lifeng Lai, UC Davis.

Graduate Student Researcher in Lai's group.

  • Study adversarial robustness of Direct Preference Optimization (DPO) against preference poisoning. Manuscript under review.

Preference Poisoning Attack on DPOMay 2025 - Dec 2025

Supervised by Prof. Lifeng Lai, UC Davis.

Graduate Student Researcher in Lai's group.

  • Studied targeted preference poisoning attacks against offline RLHF/DPO from a theoretical perspective.
  • Showed that label flipping in log-linear DPO induces a parameter-independent gradient shift, reducing attack design to a binary sparse approximation problem.
  • Proposed Binary-Aware Lattice Attack and Binary Matching Pursuit Attack with theoretical guarantees for attack feasibility, binary enforcement, minimum-flip recovery, support recovery, and impossibility of successful K-flip attacks.
  • Experiments on synthetic data and the SHP dataset validate the theory. Accepted to ICML 2026.

Preference Robustness of Online RLHFDec 2023 - May 2025

Supervised by Prof. Lifeng Lai, UC Davis.

Graduate Student Researcher in Lai's group.

  • Studied preference robustness of RLHF algorithms with online human feedback from a theoretical perspective.
  • Investigated preference attacks that force online RLHF to learn a target suboptimal policy with small attack cost.
  • Proposed an adversarial human-feedback poisoning strategy and proved its success in misleading online RLHF.
  • Proposed a robust-defense online RLHF algorithm and proved its robustness to any attacker with bounded attack cost.
  • Simulation results validate the theoretical analysis. Published in IEEE TSP 2025 [DOI].
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Reward Robustness of BanditSep 2022 - Feb 2024

Supervised by Prof. Lifeng Lai, UC Davis.

Graduate Student Researcher in Lai's group.

  • Studied reward attacks on stochastic multi-armed bandits in non-stationary environments.
  • Investigated attackers who force the victim algorithm to mostly choose a suboptimal arm with small attack cost.
  • Considered three general scenarios with different environments, algorithms, and attacker information.
  • Proposed three attack strategies and proved their success in terms of target-arm selection and attack cost.
  • Proposed a non-stationary bandit defense method and proved its robustness to any attacker with bounded attack cost.
  • Simulation results validate the theoretical analysis. Accepted to ACSSC 2023 [DOI]. Published in IEEE TSP 2024 [DOI].
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Edge AI System for Smart HomeJun 2021 - Sep 2021

Supervised by Prof. Xiaofan (Fred) Jiang, Columbia University.

Summer Research Assistant in Columbia Intelligent and Connected Systems Lab.

  • An auto-discover system able to allocate sensors and actuators according to the smart home applications specified by users; deployed in multiple lab rooms.
  • Designed the MCU/sensors-to-application architecture and built the hardware testbed from scratch.
  • Testbed: Arduino Uno reads custom sensor data (vibration, sound, etc.) and transmits them to ESP8266 via UART. ESP8266 packs data with DT format and MQTT discovery format, and sends them to a lab computer server (HTTP with Flask) and Home Assistant Raspberry Pi server (MQTT). Integrated Google Nest camera into HA and stored data in PostgreSQL and MariaDB.
  • Accepted to SenSys 2021 [DOI].
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Fever Screening SystemJan 2020 - May 2021

Supervised by Prof. Xiaofan (Fred) Jiang, Columbia University.

Research Intern in Columbia Intelligent and Connected Systems Lab.

  • A low-cost system based on RGB-thermal cameras for continuous fever screening of multiple people without human interaction; deployed in a restaurant and hospital clinic in New York City. Featured in Columbia News.
  • Implemented multiple RGB-thermal heads matching, trained and deployed YOLOV3 (head detection) and FSA-Net (head orientation regression), and estimated distance using non-identical RGB and thermal camera.
  • Accepted to SenSys 2020 [DOI], CPHS 2021 [DOI], and IPSN 2022 [DOI].
  • Project website: ICSL Fever Screening.
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Khameleon Scheduler in Reinforcement LearningJul 2020 - Sep 2020

Supervised by Prof. Eugene Wu, Columbia University.

Research Intern in WuLab Columbia University.

  • A server-side scheduler involving a complex optimization based on available resources, predicted user interactions, and response quality levels to maximize user-perceived interactivity and satisfaction in real-time.
  • Created the simulated RL environment, which can pre-compute transition relationships or compute them dynamically at run time.
  • Implemented Q-learning and SARSA-based prefetching schedulers to trade off latency and response quality with progressive encoded responses in cloud-based interactive applications.
  • Added predicted user-preferred action choices to the algorithms above.
  • Project GitHub: Khameleon-Scheduler-RL.
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Optimization of Integrated OpticsFeb 2019 – Jun 2019

Supervised by Prof. Xiaoqi Zhou, Sun Yat-sen University.

Research Intern in Optical Quantum Information Lab.

  • Undergraduate thesis.
  • Design numerical methods to solve optimal parameters of grating coupler based on regression analysis and constrained optimization problem.
  • Conduct simulation experiment with one-dimensional grating coupler.
  • Outcome: One thesis paper written.

Cyber-Physical Energy SystemsOct 2017 - Feb 2019

Supervised by Prof. Jiang Wu, Xi'an Jiaotong University.

Member of XJTU Information-technology Talent Program.

Research Intern in Ministry of Education Key Lab for Intelligent Networks and Network Security.

  • Proposed centralized and distributed K-means methods using weighted combinations of PCA features and prior knowledge, plus parameter consensus and feature-transfer methods.
  • Analyzed urban power grid data and contributed to paper writing.
  • Accepted to Chinese Control Conference 2018 [DOI].
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Publication

University of California, Davis

  1. Chenye Yang, Weiyu Xu, Lifeng Lai, "Adversarially Robust Direct Preference Optimization against Preference Label Flip Attacks" Manuscript under review.
  2. Mo Lyu, Chenye Yang, Lifeng Lai, "Efficient Reward Manipulation Attacks Against GRPO under RLVR" Manuscript under review.
  3. Chenye Yang, Weiyu Xu, Lifeng Lai, "Efficient Preference Poisoning Attack on Offline RLHF" The 43rd International Conference on Machine Learning (ICML 2026) [DOI].
  4. Mo Lyu, Chenye Yang, Guanlin Liu, Lifeng Lai, "Dueling Bandit: Adversarial Attack and Robust Defense" Manuscript under review.
  5. Mo Lyu, Chenye Yang, Guanlin Liu, Lifeng Lai, "Adversarial Post-Action Attacks on Dueling Bandits" The 59th Asilomar Conference on Signals, Systems, and Computers (ACSSC 2025) [DOI].
  6. Chenye Yang, Mo Lyu, Guanlin Liu, Lifeng Lai, "Human Feedback Attack on Online RLHF: Attack and Robust Defense" IEEE Transactions on Signal Processing, Volume: 73 (IEEE TSP 2025) [DOI].
  7. Chenye Yang, Guanlin Liu, Lifeng Lai, "Stochastic Bandits With Non-Stationary Rewards: Reward Attack and Defense" IEEE Transactions on Signal Processing, Volume: 72 (IEEE TSP 2024) [DOI].
  8. Chenye Yang, Guanlin Liu, Lifeng Lai, "Reward Attack on Stochastic Bandits with Non-stationary Rewards" The 57th Asilomar Conference on Signals, Systems, and Computers (ACSSC 2023) [DOI].

Columbia University

  1. Kaiyuan Hou, Yanchen Liu, Peter Wei, Chenye Yang, Hengjiu Kang, Stephen Xia, Teresa Spada, Andrew Rundle, Xiaofan Jiang, "A Low-Cost In-situ System for Continuous Multi-Person Fever Screening" The 21st ACM/IEEE International Conference on Information Processing in Sensor Networks (IPSN 2022) [DOI].
  2. Stephen Xia, Rishikanth Chandrasekaran, Yanchen Liu, Chenye Yang, Tajana Simunic Rosing, Xiaofan Jiang, "Demo Abstract: A Drone-based System for Intelligent and Autonomous Homes" The 19th ACM Conference on Embedded Networked Sensor Systems (SenSys 2021), Best Demo Award [DOI].
  3. Peter Wei, Yanchen Liu, Hengjiu Kang, Chenye Yang, Xiaofan Jiang, "A Low-Cost and Scalable Personalized Thermal Comfort Estimation System in Indoor Environments" The 1st International Workshop on Cyber-Physical-Human System Design and Implementation (CPHS 2021) [DOI].
  4. Peter Wei, Chenye Yang, Xiaofan Jiang, "Poster Abstract: Low-Cost Multi-Person Continuous Skin Temperature Sensing System for Fever Detection" The 18th ACM Conference on Embedded Networked Sensor Systems (SenSys 2020) [DOI].

Sun Yat-sen University

  1. Chenye Yang, "Optimal Design of Integrated Photonic Devices Based on Regression Analysis and Constrained Optimization Problem Solving" Xi'an Jiaotong University undergraduate thesis.

Xi'an Jiaotong University

  1. Pengyuan Liu, Chenye Yang, Jiang Wu, "Hybrid Features Based K-means Clustering Algorithm for Use in Electricity Customer Load Pattern Analysis" The 37th Chinese Control Conference (CCC 2018) [DOI].