Publications (68)
Direct linearisation approach to discrete integrable systems associated with graded Lax pairs
Wei Fu
Fordy and Xenitidis [J. Phys. A: Math. Theor. 50 (2017) 165205] recently proposed a large class of discrete integrable systems which include a number of novel integrable difference…
SmartCut Er:LiNbO3 with high optical coherence enabling optical thickness control
Sihao Wang, Likai Yang, Mohan Shen +5
Integrated photonics capable of incorporating rare earth ions with high optical coherence is desirable for realizing efficient quantum transducers, compact quantum memories, and hy…
SRL: Scaling Distributed Reinforcement Learning to Over Ten Thousand Cores
Zhiyu Mei, Wei Fu, Jiaxuan Gao +3
The ever-growing complexity of reinforcement learning (RL) tasks demands a distributed system to efficiently generate and process a massive amount of data. However, existing open-s…
Radiative cooling of a superconducting resonator
Mingrui Xu, Xu Han, Chang-Ling Zou +5
Cooling microwave resonators to near the quantum ground state, crucial for their operation in the quantum regime, is typically achieved by direct device refrigeration to a few tens…
Why is Differential Evolution Better than Grid Search for Tuning Defect Predictors?
Wei Fu, Vivek Nair, Tim Menzies
Context: One of the black arts of data mining is learning the magic parameters which control the learners. In software analytics, at least for defect prediction, several methods, l…
Easy over Hard: A Case Study on Deep Learning
Wei Fu, Tim Menzies
While deep learning is an exciting new technique, the benefits of this method need to be assessed with respect to its computational cost. This is particularly important for deep le…
Revisiting Unsupervised Learning for Defect Prediction
Wei Fu, Tim Menzies
Collecting quality data from software projects can be time-consuming and expensive. Hence, some researchers explore "unsupervised" approaches to quality prediction that does not re…
SCKAN: Structural Consensus-based KAN Prototype Learning for Semi-Supervised Pancreas Segmentation
Yuqi Liu, Yufei Chen, Wei Fu +2
Accurate pancreas segmentation is critical for early cancer diagnosis, where annotation scarcity necessitates Semi-Supervised Learning (SSL). However, due to significant inter-samp…
Survival Trees for Interval-Censored Survival data
Wei Fu, Jeffrey S. Simonoff
Interval-censored data, in which the event time is only known to lie in some time interval, arise commonly in practice; for example, in a medical study in which patients visit clin…
Applications of Psychological Science for Actionable Analytics
Di Chen, Wei Fu, Rahul Krishna +1
Actionable analytics are those that humans can understand, and operationalize. What kind of data mining models generate such actionable analytics? According to psychological scient…
Data-Driven Search-based Software Engineering
Vivek Nair, Amritanshu Agrawal, Jianfeng Chen +6
This paper introduces Data-Driven Search-based Software Engineering (DSE), which combines insights from Mining Software Repositories (MSR) and Search-based Software Engineering (SB…
Quantum Microwave Radiometry with a Superconducting Qubit
Zhixin Wang, Mingrui Xu, Xu Han +6
The interaction of photons and coherent quantum systems can be employed to detect electromagnetic radiation with remarkable sensitivity. We introduce a quantum radiometer based on…
Integrable properties of the differential-difference Kadomtsev-Petviashvili hierarchy and continuum limits
Wei Fu, Lin Huang, K. M. Tamizhmani +1
The paper reveals clear links between the differential-difference Kadomtsev-Petviashvili hierarchy and the (continuous) Kadomtsev-Petviashvili hierarchy, together with their symmet…
ReaL: Efficient RLHF Training of Large Language Models with Parameter Reallocation
Zhiyu Mei, Wei Fu, Kaiwei Li +3
Reinforcement Learning from Human Feedback (RLHF) is a pivotal technique for empowering large language model (LLM) applications. Compared with the supervised training process of LL…
High Quality Factor Surface Fabry-Perot Cavity of Acoustic Waves
Yuntao Xu, Wei Fu, Chang-ling Zou +2
Surface acoustic wave (SAW) resonators are critical components in wireless communications and many sensing applications. They have also recently emerged as subject of study in quan…
Cavity piezo-mechanics for superconducting-nanophotonic quantum interface
Xu Han, Wei Fu, Changchun Zhong +8
Hybrid quantum systems are essential for the realization of distributed quantum networks. In particular, piezo-mechanics operating at typical superconducting qubit frequencies feat…
Large-area and high-quality 2D transition metal telluride
Jiadong Zhou, Fucai Liu, Junhao Lin +24
Atomically thin transitional metal ditellurides like WTe2 and MoTe2 have triggered tremendous research interests because of their intrinsic nontrivial band structure. They are also…
Revisiting Some Common Practices in Cooperative Multi-Agent Reinforcement Learning
Wei Fu, Chao Yu, Zelai Xu +2
Many advances in cooperative multi-agent reinforcement learning (MARL) are based on two common design principles: value decomposition and parameter sharing. A typical MARL algorith…
Towards edge engineering of two-dimensional layered transition-metal dichalcogenides by chemical vapor deposition
Wei Fu, Mark John, Thathsara D. Maddumapatabandi +4
The manipulation of edge configurations and structures in atomically thin transition metal dichalcogenides (TMDs) for versatile functionalization has attracted intensive interest i…
Nuclear Physics at BRIF
Wei Nan, Bing Guo, Jie Chen +22
The Beijing Radioactive Ion-beam Facility (BRIF), which is based on Isotope Separation On-Line (ISOL) technique, consists of a 100 MeV proton cyclotron as the driving accelerator,…
Controlled Synthesis of Organic/Inorganic van der Waals Solid for Tunable Light-matter Interactions
Lin Niu, Xinfeng Liu, Chunxiao Cong +22
Van der Waals (vdW) solids, as a new type of artificial materials that consist of alternating layers bonded by weak interactions, have shed light on fascinating optoelectronic devi…
Heralded Generation and Detection of Entangled Microwave--Optical Photon Pairs
Changchun Zhong, Zhixin Wang, Changling Zou +8
Quantum state transfer between microwave and optical frequencies is essential for connecting superconducting quantum circuits to coherent optical systems and extending microwave qu…
MBD: A Model-Based Debiasing Framework Across User, Content, and Model Dimensions
Yuantong Li, Lei Yuan, Zhihao Zheng +27
Modern recommendation systems rank candidates by aggregating multiple behavioral signals through a value model. However, many commonly used signals are inherently affected by heter…
Is DPO Superior to PPO for LLM Alignment? A Comprehensive Study
Shusheng Xu, Wei Fu, Jiaxuan Gao +6
Reinforcement Learning from Human Feedback (RLHF) is currently the most widely used method to align large language models (LLMs) with human preferences. Existing RLHF methods can b…
What is Wrong with Topic Modeling? (and How to Fix it Using Search-based Software Engineering)
Amritanshu Agrawal, Wei Fu, Tim Menzies
Context: Topic modeling finds human-readable structures in unstructured textual data. A widely used topic modeler is Latent Dirichlet allocation. When run on different datasets, LD…
Dielectrics for Two-Dimensional Transition Metal Dichalcogenide Applications
Chit Siong Lau, Sarthak Das, Ivan A. Verzhbitskiy +6
Despite over a decade of intense research efforts, the full potential of two-dimensional transition metal dichalcogenides continues to be limited by major challenges. The lack of c…
Predicting Health Indicators for Open Source Projects (using Hyperparameter Optimization)
Tianpei Xia, Wei Fu, Rui Shu +2
Software developed on public platform is a source of data that can be used to make predictions about those projects. While the individual developing activity may be random and hard…
The semi-discrete AKNS system: Conservation laws, reductions and continuum limits
Wei Fu, Zhijun Qiao, Junwei Sun +1
In this paper, the semi-discrete Ablowitz-Kaup-Newell-Segur (AKNS) hierarchy is shown in spirit composed by the Ablowitz-Ladik flows under certain combinations. Furthermore, we der…
Continuously Discovering Novel Strategies via Reward-Switching Policy Optimization
Zihan Zhou, Wei Fu, Bingliang Zhang +1
We present Reward-Switching Policy Optimization (RSPO), a paradigm to discover diverse strategies in complex RL environments by iteratively finding novel policies that are both loc…
Brillouin scattering induced transparency and non-reciprocal light storage
Chun-Hua Dong, Zhen Shen, Chang-Ling Zou +3
Stimulated Brillouin scattering (SBS) is a very fundamental interaction between light and travelling acoustic waves, which is mainly attributed to the electrostriction and photoela…
Integrability properties of the dispersionless Kadomtsev-Petviashvili hierarchy
Wei Fu, R. Ilangovane, K. M. Tamizhmani +1
In the paper we investigate integrability characteristics for the dispersionless Kadomtsev-Petviashvili hierarchy. These characteristics include symmetries, Hamiltonian structures…
Superconducting cavity piezo-electromechanics: the realization of an acoustic frequency comb at microwave frequencies
Xu Han, Chang-Ling Zou, Wei Fu +3
We present a nonlinear multimode superconducting electroacoustic system, where the interplay between superconducting kinetic inductance and piezoelectric strong coupling establishe…
Ground Calibration Result of the Lobster Eye Imager for Astronomy
Huaqing Cheng, Zhixing Ling, Chen Zhang +22
We report on results of the on-ground X-ray calibration of the Lobster Eye Imager for Astronomy (LEIA), an experimental space wide-field (18.6*18.6 square degrees) X-ray telescope…
Photonic link from single flux quantum circuits to room temperature
Mohan Shen, Jiacheng Xie, Yuntao Xu +5
Broadband, energy-efficient signal transfer between cryogenic and room-temperature environment has been a major bottleneck for superconducting quantum and classical logic circuits.…
Liquid Metal Printed Ultrathin Oxides for Monolayer WS2 Top-Gate Transistors
Yiyu Zhang, Dasari Venkatakrishnarao, Michel Bosman +16
Two-dimensional (2D) semiconductors are promising channel materials for continued downscaling of complementary metal-oxide-semiconductor (CMOS) logic circuits. However, their full…
Embracing Intra-Class Heterogeneity for Semi-Supervised Medical Image Segmentation: From Diversity to Precision
Yuqi Liu, Yufei Chen, Wei Fu +2
Due to the scarcity of expert-annotated data, Semi-Supervised Medical Image Segmentation (SSMIS) has emerged as a promising approach. Many anatomical structures in medical images e…
Direct linearisation of the discrete-time two-dimensional Toda lattices
Wei Fu
The discrete-time two-dimensional Toda lattice of -type is studied within the direct linearisation framework, which allows us to deal with several nonlinear equations in…
Bidirectional electro-optic conversion reaching 1% efficiency with thin-film lithium niobate
Yuntao Xu, Ayed Al Sayem, Linran Fan +7
Superconducting cavity electro-optics (EO) presents a promising route to coherently convert microwave and optical photons and distribute quantum entanglement between superconductin…
Direct linearising transform for three-dimensional discrete integrable systems: the lattice AKP, BKP and CKP equations
Wei Fu, Frank Nijhoff
A unified framework is presented for the solution structure of three-dimensional discrete integrable systems, including the lattice AKP, BKP and CKP equations. This is done through…
High-acoustic-index-contrast phononic circuits: numerical modeling
Wance Wang, Mohan Shen, Chang-Ling Zou +3
We numerically model key building blocks of a phononic integrated circuit that enable phonon routing in high-acoustic-index waveguides. Our particular focus is on Gallium Nitride-o…
AREAL-DTA: Dynamic Tree Attention for Efficient Reinforcement Learning of Large Language Models
Jiarui Zhang, Yuchen Yang, Ran Yan +8
Reinforcement learning (RL)-based post-training for large language models (LLMs) is computationally expensive, as it generates many rollout sequences that frequently share long tok…
Ground-state Pulsed Cavity Electro-optics for Microwave-to-optical Conversion
Wei Fu, Mingrui Xu, Xianwen Liu +9
In the development of quantum microwave-to-optical (MO) converters, excessive noise induced by the parametric optical drive remains a major challenge at milli-Kelvin temperatures.…
Next-Generation Agentic Reinforcement Learning Systems Enable Self-Evolving Agents
Ran Yan, Wei Fu, Jiale Li +21
LLM agents are rapidly being deployed in production, including coding assistants, customer-support chatbots, and scientific research assistants, yet they remain fundamentally stati…
Ground Calibration Result of the Wide-field X-ray Telescope (WXT) onboard the Einstein Probe
Huaqing Cheng, Chen Zhang, Zhixing Ling +24
We report on results of the on-ground X-ray calibration of the Wide-field X-ray Telescope (WXT) built from novel lobster-eye micro-pore optics, onboard the Einstein Probe (EP) sate…
Vector Map as Language: Toward Unified Remote Sensing Vector Mapping
Yinglong Yan, Yunkai Yang, Haoyi Wang +7
Remote sensing vector mapping aims to generate structured maps of geospatial entities, such as buildings, roads, and water bodies, from remote sensing imagery. In practice, vector…
Estimating the number of clusters using cross-validation
Wei Fu, Patrick O. Perry
Many clustering methods, including k-means, require the user to specify the number of clusters as an input parameter. A variety of methods have been devised to choose the number of…
On reductions of the discrete Kadomtsev--Petviashvili-type equations
Wei Fu, Frank Nijhoff
The reduction by restricting the spectral parameters and on a generic algebraic curve of degree is performed for the discrete AKP, BKP and CKP equations, res…
Cladding Layer Enhanced GHz Bulk Acoustic Wave Resonance in Sodium Niobate Thin Films on Silicon
Zhi Shiuh Lim, Qibin Zeng, Hui Kim Hui +17
Bulk acoustic wave resonators (BAWR) and bandpass filters operating at GHz frequency are the workhorse of (Vo-)LTE telecommunication and broadband internet. In line with the Singap…
Light-induced dynamic frequency shifting of microwave photons in a superconducting electro-optic converter
Yuntao Xu, Wei Fu, Yiyu Zhou +4
Hybrid superconducting-photonic microresonators are a promising platform for realizing microwave-to-optical transduction. However, the absorption of scattered photons by the superc…
Polarization mode hybridization and conversion in phononic wire waveguides
Zhen Shen, Wei Fu, Ri-Sheng Cheng +3
Phononic wire waveguides of subwavelength cross-section support two orthogonal polarization modes: the out-of-plane motion dominated Rayleigh-like and the in-plane motion dominated…
AReaL-Hex: Accommodating Asynchronous RL Training over Heterogeneous GPUs
Ran Yan, Youhe Jiang, Tianyuan Wu +7
Maximizing training throughput and cost-efficiency of RL for LLMs is essential to democratize this advanced technique. One promising but challenging approach is to deploy such a co…
Building Better Quality Predictors Using "-Dominance"
Wei Fu, Tim Menzies, Di Chen +1
Despite extensive research, many methods in software quality prediction still exhibit some degree of uncertainty in their results. Rather than treating this as a problem, this pape…
500+ Times Faster Than Deep Learning (A Case Study Exploring Faster Methods for Text Mining StackOverflow)
Suvodeep Majumder, Nikhila Balaji, Katie Brey +2
Deep learning methods are useful for high-dimensional data and are becoming widely used in many areas of software engineering. Deep learners utilizes extensive computational power…
Learning Agile Bipedal Motions on a Quadrupedal Robot
Yunfei Li, Jinhan Li, Wei Fu +1
Can a quadrupedal robot perform bipedal motions like humans? Although developing human-like behaviors is more often studied on costly bipedal robot platforms, we present a solution…
Survival trees for left-truncated and right-censored data, with application to time-varying covariate data
Wei Fu, Jeffrey S. Simonoff
Tree methods (recursive partitioning) are a popular class of nonparametric methods for analyzing data. One extension of the basic tree methodology is the survival tree, which appli…
Beyond Ten Turns: Unlocking Long-Horizon Agentic Search with Large-Scale Asynchronous RL
Jiaxuan Gao, Wei Fu, Minyang Xie +5
Recent advancements in LLM-based agents have demonstrated remarkable capabilities in handling complex, knowledge-intensive tasks by integrating external tools. Among diverse choice…
How to "DODGE" Complex Software Analytics?
Amritanshu Agrawal, Wei Fu, Di Chen +2
Machine learning techniques applied to software engineering tasks can be improved by hyperparameter optimization, i.e., automatic tools that find good settings for a learner's cont…
On a coupled Kadomtsev--Petviashvili system associated with an elliptic curve
Wei Fu, Frank W. Nijhoff
The coupled Kadomtsev--Petviashvili system associated with an elliptic curve, proposed by Date, Jimbo and Miwa [J. Phys. Soc. Jpn., 52:766--771, 1983], is reinvestigated within the…
Tuning for Software Analytics: is it Really Necessary?
Wei Fu, Tim Menzies, Xipeng Shen
Context: Data miners have been widely used in software engineering to, say, generate defect predictors from static code measures. Such static code defect predictors perform well co…
Open-orbit induced low field extremely large magnetoresistance in graphene/h-BN superlattices
Zihao Wang, Pablo M. Perez-Piskunow, Calvin Pei Yu Wong +13
We report intriguing and hitherto overlooked low-field room temperature extremely large magnetoresistance (XMR) patterns in graphene/hexagonal boron nitride (h-BN) superlattices th…
Linear integral equations, infinite matrices, and soliton hierarchies
Wei Fu, Frank W. Nijhoff
A systematic framework is presented for the construction of hierarchies of soliton equations. This is realised by considering scalar linear integral equations and their representat…
AReaL: A Large-Scale Asynchronous Reinforcement Learning System for Language Reasoning
Wei Fu, Jiaxuan Gao, Xujie Shen +10
Reinforcement learning (RL) has become a dominant paradigm for training large language models (LLMs), particularly for reasoning tasks. Effective RL for LLMs requires massive paral…
Integrable semi-discretisation of the Drinfel'd--Sokolov hierarchies
Yue Yin, Wei Fu
We propose a novel semi-discrete Kadomtsev--Petviashvili equation with two discrete and one continuous independent variables, which is integrable in the sense of having the standar…
Iteratively Learn Diverse Strategies with State Distance Information
Wei Fu, Weihua Du, Jingwei Li +3
In complex reinforcement learning (RL) problems, policies with similar rewards may have substantially different behaviors. It remains a fundamental challenge to optimize rewards wh…
On Designing Effective RL Reward at Training Time for LLM Reasoning
Jiaxuan Gao, Shusheng Xu, Wenjie Ye +6
Reward models have been increasingly critical for improving the reasoning capability of LLMs. Existing research has shown that a well-trained reward model can substantially improve…
Linear integral equations and two-dimensional Toda systems
Yue Yin, Wei Fu
The direct linearisation framework is presented for the two-dimensional Toda equations associated with the infinite-dimensional Lie algebras , and ,…
How Far Are We from Optimal Reasoning Efficiency?
Jiaxuan Gao, Shu Yan, Qixin Tan +6
Large Reasoning Models (LRMs) demonstrate remarkable problem-solving capabilities through extended Chain-of-Thought (CoT) reasoning but often produce excessively verbose and redund…
On nonautonomous differential-difference AKP, BKP and CKP equations
Wei Fu, Frank W. Nijhoff
Based on the direct linearisation framework of the discrete Kadomtsev-Petviashvili-type equations presented in [Proc. R. Soc. A, 473 (2017) 20160915], six novel nonautonomous diffe…