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Zhen Liu

70 accepted papers

2026

A Unified Shape-Aware Foundation Model for Time Series Classification

AAAI 2026technical

Foundation models pre-trained on large-scale source datasets are reshaping the traditional training paradigm for time series classification. However, existing time series foundation models primarily focus on forecasting tasks and often overlook classification-specific challenges, such as modeling in

Cited by 0SourcePDFScholar
2026

Bridging RGB and RAW: Single-step Deterministic Flow with Homogeneous Aligned Guidance

ICML 2026poster

Reconstructing high-fidelity RAW sensor data from processed RGB images is a fundamental yet ill-posed problem, plagued by irreversible information loss and complex non-linear ISP transformations. While generative models offer high-quality reconstruction, they suffer from prohibitive computational co…

Cited by 0SourceScholar
2026

ExpoCM: Exposure-Aware One-Step Generative Single-Image HDR Reconstruction

CVPR 2026

Single-image HDR reconstruction aims to recover high dynamic range radiance from a single low dynamic range (LDR) input, but remains highly ill-posed due to detail saturation in over-exposed regions and noise amplification in under-exposed areas. While recent diffusion-based approaches offer powerfu

Cited by 0SourcecodeScholar
2026

Learning Recursive Multi-Scale Representations for Irregular Multivariate Time Series Forecasting

ICLR 2026poster

Irregular Multivariate Time Series (IMTS) are characterized by uneven intervals between consecutive timestamps, which carry sampling pattern information valuable and informative for learning temporal and variable dependencies. In addition, IMTS often exhibit diverse dependencies across multiple time…

Cited by 0SourcecodeScholar
2026

ORSATR-X: A Foundation Model based on Differential-and-Excitation Networks for Optical Remote Sensing Object Recognition

CVPR 2026

Recent advances in Remote Sensing Foundation Models (RSFMs) have demonstrated considerable potential for Earth Observation (EO) tasks. While adopting natural image foundation models (e.g., DINO) provides a data-efficient strategy for building RSFMs, their strong generalization capability does not fu

Cited by 0SourcecodeScholar
2026

RAW-Flow: Advancing RGB-to-RAW Image Reconstruction with Deterministic Latent Flow Matching

AAAI 2026technical

RGB-to-RAW reconstruction, or the reverse modeling of a camera Image Signal Processing (ISP) pipeline, aims to recover high-fidelity RAW data from RGB images. Despite notable progress, existing learning-based methods typically treat this task as a direct regression objective and still struggle with

Cited by 0SourcePDFScholar
2026

Structured Progressive Knowledge Activation for LLM-Driven Neural Architecture Search

ICML 2026poster

This paper focuses on a key challenge in Neural Architecture Search (NAS): integrating established architectural knowledge while exploring new designs under expensive evaluations. Large language models (LLMs) are a promising assistant for NAS because they can translate rich architectural and coding …

Cited by 0SourceScholar
2026

ZeroIDIR: Zero-Reference Illumination Degradation Image Restoration with Perturbed Consistency Diffusion Models

CVPR 2026

In this paper, we propose a zero-reference diffusion-based framework, named ZeroIDIR, for illumination degradation image restoration, which decouples the restoration process into adaptive illumination correction and diffusion-based reconstruction while being trained solely on low-quality degraded im

Cited by 0SourcecodeScholar
2025

A Modular Magnetic Navigation System for Actuating Surface Microwalkers

RA-L 2025

The complex motion modes of surface microwalkers rely on magnetic torque generated by rotating/oscillating magnetic fields. Actuation systems based on rotating permanent magnets exhibit considerable advantages in generating these dynamic fields due to their high flexibility. However, current omnidir

Cited by 0SourceScholar
2025

Can Large Language Models Understand Symbolic Graphics Programs?

ICLR 2025spotlight

Against the backdrop of enthusiasm for large language models (LLMs), there is a growing need to scientifically assess their capabilities and shortcomings. This is nontrivial in part because it is difficult to find tasks which the models have not encountered during training. Utilizing symbolic graphi…

Cited by 11SourcePDFScholar
2025

ChatGarment: Garment Estimation, Generation and Editing via Large Language Models

CVPR 2025poster

We introduce ChatGarment, a novel approach that leverages large vision-language models (VLMs) to automate the estimation, generation, and editing of 3D garment sewing patterns from images or text descriptions. Unlike previous methods that often lack robustness and interactive editing capabilities, C…

Cited by 5SourcePDFScholar
2025

Efficient Diversity-Preserving Diffusion Alignment via Gradient-Informed GFlowNets

ICLR 2025poster

While one commonly trains large diffusion models by collecting datasets on target downstream tasks, it is often desired to align and finetune pretrained diffusion models with some reward functions that are either designed by experts or learned from small-scale datasets. Existing post-training method…

Cited by 0SourcePDFScholar
2025

FlowPolicy: Enabling Fast and Robust 3D Flow-Based Policy via Consistency Flow Matching for Robot Manipulation

AAAI 2025technical

Robots can acquire complex manipulation skills by learning policies from expert demonstrations, which is often known as vision-based imitation learning. Generating policies based on diffusion and flow matching models has been shown to be effective, particularly in robotic manipulation tasks. However…

2025

Fusion Meets Diverse Conditions: A High-diversity Benchmark and Baseline for UAV-based Multimodal Object Detection with Condition Cues

ICCV 2025poster

Unmanned aerial vehicles (UAV)-based object detection with visible (RGB) and infrared (IR) images facilitates robust around-the-clock detection, driven by advancements in deep learning techniques and the availability of high-quality dataset. However, the existing dataset struggles to fully capture r…

Cited by 0SourcePDFScholar
2025

Hi-Patch: Hierarchical Patch GNN for Irregular Multivariate Time Series

ICML 2025poster

Multi-scale information is crucial for multivariate time series modeling. However, most existing time series multi-scale analysis methods treat all variables in the same manner, making them unsuitable for Irregular Multivariate Time Series (IMTS), where variables have distinct origin scales/sampling…

Cited by 0SourcePDFScholar
2025

HyperIMTS: Hypergraph Neural Network for Irregular Multivariate Time Series Forecasting

ICML 2025poster

Irregular multivariate time series (IMTS) are characterized by irregular time intervals within variables and unaligned observations across variables, posing challenges in learning temporal and variable dependencies. Many existing IMTS models either require padded samples to learn separately from te…

2025

Learning Soft Sparse Shapes for Efficient Time-Series Classification

ICML 2025spotlight

Shapelets are discriminative subsequences (or shapes) with high interpretability in time series classification. Due to the time-intensive nature of shapelet discovery, existing shapelet-based methods mainly focus on selecting discriminative shapes while discarding others to achieve candidate subsequ…

Cited by 0SourcePDFScholar
2025

Learning to See in the Extremely Dark

ICCV 2025poster

Learning-based methods have made promising advances in low-light RAW image enhancement, while their capability to extremely dark scenes where the environmental illuminance drops as low as 0.0001 lux remains to be explored due to the lack of corresponding datasets. To this end, we propose a paired-to…

2025

Luminance-Aware Statistical Quantization: Unsupervised Hierarchical Learning for Illumination Enhancement

NeurIPS 2025poster

Low-light image enhancement (LLIE) faces persistent challenges in balancing reconstruction fidelity with cross-scenario generalization. While existing methods predominantly focus on deterministic pixel-level mappings between paired low/normal-light images, they often neglect the continuous physical…

Cited by 0SourcecodeScholar
2025

Nabla-R2D3: Effective and Efficient 3D Diffusion Alignment with 2D Rewards

NeurIPS 2025poster

Generating high-quality and photorealistic 3D assets remains a longstanding challenge in 3D vision and computer graphics. Although state-of-the-art generative models, such as diffusion models, have made significant progress in 3D generation, they often fall short of human-designed content due to lim…

Cited by 0SourceScholar
2025

UEVAVD: A Dataset for Developing UAV's Eye View Active Object Detection

RA-L 2025

Occlusion is a longstanding difficulty that challenges the UAV-based object detection. Many works address this problem by adapting the detection model. However, few of them exploit that the UAV could fundamentally improve detection performance by changing its viewpoint. Active Object Detection (AOD)

Cited by 4SourcecodeScholar
2025

Value Gradient Guidance for Flow Matching Alignment

NeurIPS 2025poster

While methods exist for aligning flow matching models -- a popular and effective class of generative models -- with human preferences, existing approaches fail to achieve both adaptation efficiency and probabilistically sound prior preservation. In this work, we leverage the theory of optimal contro…

Cited by 0SourceScholar
2024

A Dynamic Kernel Prior Model for Unsupervised Blind Image Super-Resolution

CVPR 2024poster

Deep learning-based methods have achieved significant successes on solving the blind super-resolution (BSR) problem. However most of them request supervised pre-training on labelled datasets. This paper proposes an unsupervised kernel estimation model named dynamic kernel prior (DKP) to realize an u…

2024

Diffusion Language-Shapelets for Semi-supervised Time-Series Classification

AAAI 2024technical

Semi-supervised time-series classification could effectively alleviate the issue of lacking labeled data. However, existing approaches usually ignore model interpretability, making it difficult for humans to understand the principles behind the predictions of a model. Shapelets are a set of discrimi…

2024

FINER: Flexible Spectral-bias Tuning in Implicit NEural Representation by Variable-periodic Activation Functions

CVPR 2024poster

Implicit Neural Representation (INR) which utilizes a neural network to map coordinate inputs to corresponding attributes is causing a revolution in the field of signal processing. However current INR techniques suffer from a restricted capability to tune their supported frequency set resulting in i…

Cited by 34SourcePDFScholar
2024

Ghost on the Shell: An Expressive Representation of General 3D Shapes

ICLR 2024oral

The creation of photorealistic virtual worlds requires the accurate modeling of 3D surface geometry for a wide range of objects. For this, meshes are appealing since they enable 1) fast physics-based rendering with realistic material and lighting, 2) physical simulation, and 3) are memory-efficient…

Cited by 15SourcePDFScholar
2024

Incremental Sequence Labeling: A Tale of Two Shifts

ACL 2024findings

The incremental sequence labeling task involves continuously learning new classes over time while retaining knowledge of the previous ones. Our investigation identifies two significant semantic shifts: E2O (where the model mislabels an old entity as a non-entity) and O2E (where the model labels a no…

2024

Knowledge-Empowered Dynamic Graph Network for Irregularly Sampled Medical Time Series

NeurIPS 2024poster

Irregularly Sampled Medical Time Series (ISMTS) are commonly found in the healthcare domain, where different variables exhibit unique temporal patterns while interrelated. However, many existing methods fail to efficiently consider the differences and correlations among medical variables together, l…

Cited by 1SourcePDFScholar
2024

Learning Over Molecular Conformer Ensembles: Datasets and Benchmarks

ICLR 2024poster

Molecular Representation Learning (MRL) has proven impactful in numerous biochemical applications such as drug discovery and enzyme design. While Graph Neural Networks (GNNs) are effective at learning molecular representations from a 2D molecular graph or a single 3D structure, existing works often…

2024

Parameter-Efficient Orthogonal Finetuning via Butterfly Factorization

ICLR 2024poster

Large foundation models are becoming ubiquitous, but training them from scratch is prohibitively expensive. Thus, efficiently adapting these powerful models to downstream tasks is increasingly important. In this paper, we study a principled finetuning paradigm -- Orthogonal Finetuning (OFT) -- for d…

Cited by 57SourcePDFScholar
2024

Uncertainty-Aware Yield Prediction with Multimodal Molecular Features

AAAI 2024technical

Predicting chemical reaction yields is pivotal for efficient chemical synthesis, an area that focuses on the creation of novel compounds for diverse uses. Yield prediction demands accurate representations of reactions for forecasting practical transformation rates. Yet, the uncertainty issues broad…

2023

Adversarial Driving Behavior Generation Incorporating Human Risk Cognition for Autonomous Vehicle Evaluation

IROS 2023poster

Autonomous vehicle (AV) evaluation has been the subject of increased interest in recent years both in industry and in academia. This paper focuses on the development of a novel framework for generating adversarial driving behavior of background vehicle interfering against the AV to expose effective…

Cited by 1SourceScholar
2023

CTW: Confident Time-Warping for Time-Series Label-Noise Learning

IJCAI 2023poster

Noisy labels seriously degrade the generalization ability of Deep Neural Networks (DNNs) in various classification tasks. Existing studies on label-noise learning mainly focus on computer vision, while time series also suffer from the same issue. Directly applying the methods from computer vision to…

2023

Controlling Text-to-Image Diffusion by Orthogonal Finetuning

NeurIPS 2023poster

Large text-to-image diffusion models have impressive capabilities in generating photorealistic images from text prompts. How to effectively guide or control these powerful models to perform different downstream tasks becomes an important open problem. To tackle this challenge, we introduce a princip…

Cited by 123SourcePDFScholar
2023

DINER: Disorder-Invariant Implicit Neural Representation

CVPR 2023highlight

Implicit neural representation (INR) characterizes the attributes of a signal as a function of corresponding coordinates which emerges as a sharp weapon for solving inverse problems. However, the capacity of INR is limited by the spectral bias in the network training. In this paper, we find that suc…

2023

Initial-Pose Self-Calibration for Redundant Cable-Driven Parallel Robot Using Force Sensors Under Hybrid Joint-Space Control

RA-L 2023

This letter investigates initial-pose estimation (Cartesian position and orientation) for redundant cable-driven parallel robots (CDPRs). As the forward kinematics cannot be performed if the robot is equipped with incremental sensors, a calibration method using force sensors is proposed. The self-ca

Cited by 6SourceScholar
2023

Iterative Teaching by Data Hallucination

AISTATS 2023poster

We consider the problem of iterative machine teaching, where a teacher sequentially provides examples based on the status of a learner under a discrete input space (i.e., a pool of finite samples), which greatly limits the teacher’s capability. To address this issue, we study iterative teaching unde…

2023

Locate Then Generate: Bridging Vision and Language with Bounding Box for Scene-Text VQA

AAAI 2023technical

In this paper, we propose a novel multi-modal framework for Scene Text Visual Question Answering (STVQA), which requires models to read scene text in images for question answering. Apart from text or visual objects, which could exist independently, scene text naturally links text and visual modaliti…

Cited by 10SourcePDFScholar
2023

Low-Light Image Enhancement with Illumination-Aware Gamma Correction and Complete Image Modelling Network

ICCV 2023poster

This paper presents a novel network structure with illumination-aware gamma correction and complete image modelling to solve the low-light image enhancement problem. Low-light environments usually lead to less informative large-scale dark areas, directly learning deep representations from low-light…

Cited by 37PDFScholar
2023

MeshDiffusion: Score-based Generative 3D Mesh Modeling

ICLR 2023top-25%

We consider the task of generating realistic 3D shapes, which is useful for a variety of applications such as automatic scene generation and physical simulation. Compared to other 3D representations like voxels and point clouds, meshes are more desirable in practice, because (1) they enable easy and…

2023

Scale-teaching: Robust Multi-scale Training for Time Series Classification with Noisy Labels

NeurIPS 2023poster

Deep Neural Networks (DNNs) have been criticized because they easily overfit noisy (incorrect) labels. To improve the robustness of DNNs, existing methods for image data regard samples with small training losses as correctly labeled data (small-loss criterion). Nevertheless, time series' discriminat…

2023

Span-level Aspect-based Sentiment Analysis via Table Filling

ACL 2023long

In this paper, we propose a novel span-level model for Aspect-Based Sentiment Analysis (ABSA), which aims at identifying the sentiment polarity of the given aspect. In contrast to conventional ABSA models that focus on modeling the word-level dependencies between an aspect and its corresponding opin…

Cited by 21SourcePDFScholar
2023

Temporal-Frequency Co-training for Time Series Semi-supervised Learning

AAAI 2023technical

Semi-supervised learning (SSL) has been actively studied due to its ability to alleviate the reliance of deep learning models on labeled data. Although existing SSL methods based on pseudo-labeling strategies have made great progress, they rarely consider time-series data's intrinsic properties (e.g…

2022

Generative Flow Networks for Discrete Probabilistic Modeling

ICML 2022spotlight

We present energy-based generative flow networks (EB-GFN), a novel probabilistic modeling algorithm for high-dimensional discrete data. Building upon the theory of generative flow networks (GFlowNets), we model the generation process by a stochastic data construction policy and thus amortize expensi…

2022

Ghost-Free High Dynamic Range Imaging with Context-Aware Transformer

ECCV 2022poster

"High dynamic range (HDR) deghosting algorithms aim to generate ghost-free HDR images with realistic details. Restricted by the locality of the receptive field, existing CNN-based methods are typically prone to producing ghosting artifacts and intensity distortions in the presence of large motion an…

2022

Multi-Target Encirclement with Collision Avoidance via Deep Reinforcement Learning using Relational Graphs

ICRA 2022poster

In this paper, we propose a novel decentralized method based on deep reinforcement learning using robot-level and target-level relational graphs, to solve the problem of multi-target encirclement with collision avoidance (MECA). Specifically, the robot-level relational graphs, composed of three hete…

Cited by 13SourceScholar
2022

Multi-UAV Cooperative Short-Range Combat via Attention-Based Reinforcement Learning using Individual Reward Shaping

IROS 2022poster

In this paper, we propose a novel distributed method based on attention-based deep reinforcement learning using individual reward shaping, for multiple unmanned aerial vehicles (UAVs) cooperative short-range combat mission. Specifically, a two-level attention distributed policy, composed of observat…

Cited by 13SourceScholar
2021

A Consciousness-Inspired Planning Agent for Model-Based Reinforcement Learning

NeurIPS 2021poster

We present an end-to-end, model-based deep reinforcement learning agent which dynamically attends to relevant parts of its state during planning. The agent uses a bottleneck mechanism over a set-based representation to force the number of entities to which the agent attends at each planning step to…

2021

Generalized Thinned Coprime Array for DOA Estimation

ICASSP 2021accepted

Owing to the large degrees of freedom and reduced mutual coupling by producing difference coarrays, nonuniform linear arrays have aroused great interest in direction of arrival (DOA) estimation. Previous works have presented some new sparse arrays, such as the thinned coprime array. In this paper, w…

Cited by 0SourceScholar
2021

Iterative Teaching by Label Synthesis

NeurIPS 2021spotlight

In this paper, we consider the problem of iterative machine teaching, where a teacher provides examples sequentially based on the current iterative learner. In contrast to previous methods that have to scan over the entire pool and select teaching examples from it in each iteration, we propose a lab…

Cited by 15SourcePDFScholar
2021

Learning with Hyperspherical Uniformity

AISTATS 2021poster

Due to the over-parameterization nature, neural networks are a powerful tool for nonlinear function approximation. In order to achieve good generalization on unseen data, a suitable inductive bias is of great importance for neural networks. One of the most straightforward ways is to regularize the n…

Cited by 46SourcePDFScholar
2021

Multi-target Coverage with Connectivity Maintenance using Knowledge-incorporated Policy Framework

ICRA 2021poster

This paper considers a multi-target coverage problem where a robot team aims to efficiently cover multi-targets while maintaining connectivity in a distributed manner. A novel knowledge-incorporated policy framework is proposed to derive a distributed, efficient, and connectivity guaranteed coverage…

Cited by 11SourceScholar
2021

Parameter Identifiability Of Spatial-Smoothing-Based Bistatic Mimo Radar

ICASSP 2021accepted

Diversity smoothing has been widely developed for angle estimation with bistatic multiple input multiple output (MIMO) radar in the presence of coherent targets, the parameter identifiability of which is an important issue. In this paper, we are devoted to establishing more accurate conditions by st…

Cited by 0SourceScholar
2020

Regularizing Neural Networks via Minimizing Hyperspherical Energy

CVPR 2020poster

Inspired by the Thomson problem in physics where the distribution of multiple propelling electrons on a unit sphere can be modeled via minimizing some potential energy, hyperspherical energy minimization has demonstrated its potential in regularizing neural networks and improving their generalizatio…

Cited by 34PDFScholar
2020

Trajectory Optimization for a Six-DOF Cable-Suspended Parallel Robot with Dynamic Motions Beyond the Static Workspace

ICRA 2020poster

This paper presents a trajectory optimization formulation for planning dynamic trajectories of a six-degree-of-freedom (six-DOF) cable-suspended parallel robot (CSPR) that extend beyond the static workspace. The optimization is guided by low-dimensional dynamic models to overcome the local minima an…

Cited by 8SourceScholar
2019

Closed-Form Equations and Experimental Verification for Soft Robot Arm Based on Cosserat Theory

IROS 2019poster

Compared with conventional robots, soft structures such as living octopus arms and various soft-robot arms have more degrees of freedom (DOFs) and greater flexibility. Soft robot arms have a considerable range of applications. However, it is arduous to establish a mechanical model for them, because…

Cited by 10SourceScholar
2019

Exponential Family Estimation via Adversarial Dynamics Embedding

NeurIPS 2019poster

We present an efficient algorithm for maximum likelihood estimation (MLE) of exponential family models, with a general parametrization of the energy function that includes neural networks. We exploit the primal-dual view of the MLE with a kinetics augmented model to obtain an estimate associated wi…

2019

Sparse Subspace Clustering for Evolving Data Streams

ICASSP 2019accepted

The data streams arising in many applications can be modeled as a union of low-dimensional subspaces known as multi-subspace data streams (MSDSs). Clustering MSDSs according to their underlying low-dimensional subspaces is a challenging problem which has not been resolved satisfactorily by existing…

Cited by 0SourceScholar
2018

Coupled Variational Bayes via Optimization Embedding

NeurIPS 2018poster

Variational inference plays a vital role in learning graphical models, especially on large-scale datasets. Much of its success depends on a proper choice of auxiliary distribution class for posterior approximation. However, how to pursue an auxiliary distribution class that achieves both good approx…

2018

Deep Forward and Inverse Perceptual Models for Tracking and Prediction

ICRA 2018poster

We consider the problems of learning forward models that map state to high-dimensional images and inverse models that map high-dimensional images to state in robotics. Specifically, we present a perceptual model for generating video frames from state with deep networks, and provide a framework for i…

Cited by 25SourceScholar
2018

Learning towards Minimum Hyperspherical Energy

NeurIPS 2018poster

Neural networks are a powerful class of nonlinear functions that can be trained end-to-end on various applications. While the over-parametrization nature in many neural networks renders the ability to fit complex functions and the strong representation power to handle challenging tasks, it also lead…

Cited by 178SourcePDFScholar
2018

SBEED: Convergent Reinforcement Learning with Nonlinear Function Approximation

ICML 2018oral

When function approximation is used, solving the Bellman optimality equation with stability guarantees has remained a major open problem in reinforcement learning for decades. The fundamental difficulty is that the Bellman operator may become an expansion in general, resulting in oscillating and eve…

Cited by 336SourcePDFScholar
2017

Motion planning with graph-based trajectories and Gaussian process inference

ICRA 2017poster

Motion planning as trajectory optimization requires generating trajectories that minimize a desired objective function or performance metric. Finding a globally optimal solution is often intractable in practice: despite the existence of fast motion planning algorithms, most are prone to local minima…

Cited by 37SourceScholar