arXiv subjects

Kehao Chen

Publications and source records attributed to Kehao Chen.

4 recordsLinked to original sources

arXiv2026

Differentiable Routability-Driven Package Floorplanning with Pin Assignment

As advanced packaging technology evolves, increasing interconnect density in redistribution layers (RDLs) makes routability critical to package floorplanning. Meanwhile, power integrity requirements often reserve fan-in regions for the power delivery network (PDN), forcing signal nets through fan-out regions and complicating routability estimation. Existing uniform grid-based congestion models cannot accurately characterize fan-out congestion, while previous pin assignment methods struggle to evaluate net crossings. We propose a differentiable routability-driven floorplanning and pin assignment algorithm for advanced packaging with fan-out routing. First, a differentiable wirelength minimization method directly models discrete chip orientations and back-propagates wirelength gradients to chip locations and orientations. It reduces wirelength under fixed pin selection while avoiding the bias of continuous-angle modeling. Second, a crossing-aware pin assignment method incorporates net-crossing cost into a multi-strategy DPSO algorithm and uses GPU-parallel cost evaluation to reduce wirelength efficiently. Finally, a differentiable routability maximization method constructs a congestion model tailored to fan-out routing and establishes a back-propagation path from congestion information to chip locations, thereby guiding routability optimization. Experimental results show that our method achieves 100% routability on all benchmarks. For cases successfully routed by the baselines, it reduces wirelength by up to approximately 23% compared with a leading floorplanning method equipped with our pin assignment flow.

cs.AR↗

arXiv2025

Beyond Majority Voting: Towards Fine-grained and More Reliable Reward Signal for Test-Time Reinforcement Learning

Test-time reinforcement learning mitigates the reliance on annotated data by using majority voting results as pseudo-labels, emerging as a complementary direction to reinforcement learning with verifiable rewards (RLVR) for improving reasoning ability. However, this voting strategy often induces confirmation bias and suffers from sparse rewards, limiting the overall performance. In this work, we propose subgroup-specific step-wise confidence-weighted pseudo-label estimation (SCOPE), a framework integrating model confidence and dynamic subgroup partitioning to address these issues. Specifically, SCOPE integrates the proposed step-wise confidence into pseudo label estimation, prioritizing high-quality reasoning paths over simple frequency count. Furthermore, it dynamically partitions the candidate outputs pool into independent subgroups by balancing reasoning quality against exploration diversity. By deriving local consensus via repeat sampling for each sub group, SCOPE provides diverse supervision targets to encourage broader exploration. We conduct experiments across various models and benchmarks, experimental results show that SCOPE consistently outperforms recent baselines. Notably, SCOPE achieving relative improvements of 13.1% on challenging AIME 2025 and 8.1% on AMC. The code is released at https://github.com/szu-tera/SCOPE.

cs.CL↗

arXiv2025

Enhancing Sentiment Analysis through Multimodal Fusion: A BERT-DINOv2 Approach

Multimodal sentiment analysis enhances conventional sentiment analysis, which traditionally relies solely on text, by incorporating information from different modalities such as images, text, and audio. This paper proposes a novel multimodal sentiment analysis architecture that integrates text and image data to provide a more comprehensive understanding of sentiments. For text feature extraction, we utilize BERT, a natural language processing model. For image feature extraction, we employ DINOv2, a vision-transformer-based model. The textual and visual latent features are integrated using proposed fusion techniques, namely the Basic Fusion Model, Self Attention Fusion Model, and Dual Attention Fusion Model. Experiments on three datasets, Memotion 7k dataset, MVSA single dataset, and MVSA multi dataset, demonstrate the viability and practicality of the proposed multimodal architecture.

cs.CV↗

arXiv2024

Backdoor Attack with Invisible Triggers Based on Model Architecture Modification

Machine learning systems are vulnerable to backdoor attacks, where attackers manipulate model behavior through data tampering or architectural modifications. Traditional backdoor attacks involve injecting malicious samples with specific triggers into the training data, causing the model to produce targeted incorrect outputs in the presence of the corresponding triggers. More sophisticated attacks modify the model's architecture directly, embedding backdoors that are harder to detect as they evade traditional data-based detection methods. However, the drawback of the architectural modification based backdoor attacks is that the trigger must be visible in order to activate the backdoor. To further strengthen the invisibility of the backdoor attacks, a novel backdoor attack method is presented in the paper. To be more specific, this method embeds the backdoor within the model's architecture and has the capability to generate inconspicuous and stealthy triggers. The attack is implemented by modifying pre-trained models, which are then redistributed, thereby posing a potential threat to unsuspecting users. Comprehensive experiments conducted on standard computer vision benchmarks validate the effectiveness of this attack and highlight the stealthiness of its triggers, which remain undetectable through both manual visual inspection and advanced detection tools.

cs.CR↗