Junjie Ma

Dr. Junjie Ma

orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
25 January 2021 in IEEE Access
Verified
Journal Article
Open access
CLChang Liu
Chang Liu
HKHirota Kaoru
Hirota Kaoru
JMJunjie Ma
Junjie Ma
ZJZhiyang Jia
Zhiyang Jia
YDYaping Dai
Yaping Dai
Facial Expression Recognition (FER) has long been a challenging task in the field of computer vision. Most of the existing FER methods extract facial features on the basis of face pixels, ignoring the relative geometric position dependencies of facial landmark points. This article presents a hybrid feature extraction network to enhance the discriminative power of emotional features. The proposed network consists of a Spatial Attention Convolutional Neural Network (SACNN) and a series of Long Short-term Memory networks with Attention mechanism (ALSTMs). The SACNN is employed to extract the expressional features from static face images and the ALSTMs is designed to explore the potentials of facial landmarks for expression recognition. A deep geometric feature descriptor is proposed to characterize the relative geometric position correlation of facial landmarks. The landmarks are divided into seven groups to extract deep geometric features, and the attention module in ALSTMs can adaptively estimate the importance of different landmark regions. By jointly combining SACNN and ALSTMs, the hybrid features are obtained for expression recognition. Experiments conducted on three public databases, FER2013, CK+, and JAFFE, demonstrate that the proposed method outperforms the previous methods, with the accuracies of 74.31%, 95.15%, and 98.57%, respectively. The preliminary results of Emotion Understanding Robot System (EURS) indicate that the proposed method has the potential to improve the performance of human-robot interaction.

1 July 2019 in Neurocomputing
Verified
Journal Article
Closed access
JMJunjie Ma
Junjie Ma
YDYaping Dai
Yaping Dai
YTYap-Peng Tan
Yap-Peng Tan

23 September 2022 in IEEE Transactions on Automation Science and Engineering
Verified
Journal Article
Closed access
FSFuchun Sun
Fuchun Sun
JMJunjie Ma
Junjie Ma
TLTianyu Liu
Tianyu Liu
HLHuaping Liu
Huaping Liu
Bin FangBin Fang
Bin Fang
The outbreak of COVID-19 has led to the shortage of medical personnel and the increasing need for nucleic acid testing. Manual oropharyngeal sampling is susceptible to inconsistency caused by fatigue and close contact could also cause healthcare personnel exposure and cross infection. The innate deficiency calls for a safer and more consistent way to collect the oropharyngeal samples. Therefore a fully autonomous oropharyngeal-swab robot system is proposed in this paper. The system is installed in a negative pressure chamber and carrying out a standardized sampling process to minimize individual sampling differences. A hierarchical throat detection algorithm is presented and multiple modality sensory information are fused to safely and accurately localize the optimum sampling location. Also, a force/position hybrid control method is adopted to ensure both accurate sampling and subject comfort. The robot system described in this paper can safely and efficiently collect the oropharyngeal sample, providing a scalable solution for large-scale Polymerase Chain Reaction (PCR) Molecular sample collection for various respiratory diseases. Note to Practitioners —During the COVID-19 pandemic, pre-diagnostic is essential for both prevention and treatment. Existing approaches, including nasal swab and oropharyngeal-swab, require extensive medical worker training and increase the chance of cross-infection. The robot system introduced in this paper can take oropharyngeal-swab samples from subjects with minimum human intervention, reducing medical worker exposure, alleviating the work pressure of medical staff, and speed up large quantity of sampling plan. The robot will first guide the subject into position with vocal commands, and automatically detect the optimum sampling location with a real-time machine learning algorithm. A dedicated control strategy aiming at minimizing discomfort and uniforming sample quantity is then applied to safely collect nucleic samples from the throat. Eventually, while the swab is being stored in the culture medium, a disinfection process is carried out simultaneously to prepare the robot for the next subject. Preliminary clinical trials show that our robot system can safely and accurately collect samples from subjects.

2 November 2020 in IEEE Access
Verified
Journal Article
Open access
TBTianteng Bi
Tianteng Bi
JMJunjie Ma
Junjie Ma
YLYue Liu
Yue Liu
DWDongdong Weng
Dongdong Weng
YWYongtian Wang
Yongtian Wang
Measuring the material, geometry, and ambient lighting of surfaces is a key technology in the object’s appearance reconstruction. In this paper, we propose a novel deep learning-based method to extract such information to reconstruct the object’s appearance from an RGB image. Firstly, we design new deep convolutional neural network architectures to improve the performance by fusing complementary features from hierarchical layers and different tasks. Then we generate a synthetic dataset to train the proposed model to tackle the problem of the absence of the ground-truth. To transfer the domain from the synthetic data to the specific real image, we introduce a self-supervised test-time training strategy to finetune the trained model. The proposed architecture only requires one image as input when inferring the material, geometry, and ambient lighting. The experiments are conducted to evaluate the proposed method on both the synthetic data and real data. The results show that our trained model outperforms the existing baselines in each task and presents obvious improvement in final appearance reconstruction, which verifies the effectiveness of the proposed methods.

30 October 2025 in Electronics
Verified
Journal Article
Open access
PDF file
XJXu Ji
Xu Ji
LXLuo Xu
Luo Xu
LGLandi Gu
Landi Gu
JMJunjie Ma
Junjie Ma
ZZZichao Zhang
Zichao Zhang
WJWei Jiang
Wei Jiang
The Retrieval-Augmented Generation (RAG) framework shows great potential in terms of improving the reasoning and knowledge utilization capabilities of language models. However, most existing RAG systems heavily rely on large language models (LLMs) and suffer severe performance degradation when using small language models (SLMs), which limits their efficiency and deployment in resource-constrained environments. To address this challenge, we propose Retrieval-Adaptive-Planning RAG (RAP-RAG), a lightweight and high-efficiency RAG framework with adaptive retrieval task planning that is compatible with both SLMs and LLMs simultaneously. RAP-RAG is built on three key components: (1) a heterogeneous weighted graph index that integrates semantic similarity and structural connectivity; (2) a set of retrieval methods that balance efficiency and reasoning power; and (3) an adaptive planner that dynamically selects appropriate strategies based on query features. Experiments on the LiHua-World, MultiHop-RAG, and Hybrid-SQuAD datasets show that RAP-RAG consistently outperforms representative baseline models such as GraphRAG, LightRAG, and MiniRAG. Compared to lightweight baselines, RAP-RAG achieves 3–5% accuracy improvement while maintaining high efficiency and maintains comparable efficiency in both small and large model settings. In addition, our proposed framework reduces storage size by 15% compared to mainstream frameworks. Component analysis further confirms the necessity of weighted graphs and adaptive programming for robust retrieval under multi-hop reasoning and heterogeneous query conditions. These results demonstrate that RAP-RAG is a practical and efficient framework for retrieval-enhanced generation, suitable for large-scale and resource-constrained scenarios.

9 October 2025 in Electronics
Verified
Journal Article
Open access
PDF file
LGLandi Gu
Landi Gu
XJXu Ji
Xu Ji
ZZZichao Zhang
Zichao Zhang
JMJunjie Ma
Junjie Ma
XJXiaoxia Jia
Xiaoxia Jia
WJWei Jiang
Wei Jiang
Recent advancements in large language models (LLMs) have increased the necessity of alignment and safety mechanisms. Despite these efforts, jailbreak attacks remain a significant threat, exploiting vulnerabilities to elicit harmful responses. While white-box attacks, such as the Greedy Coordinate Gradient (GCG) method, have demonstrated promise, their efficacy is often limited by non-smooth optimization landscapes and a tendency to converge to local minima. To mitigate these issues, we propose Spatial Momentum GCG (SM-GCG), a novel method that incorporates spatial momentum. This technique aggregates gradient information across multiple transformation spaces—including text, token, one-hot, and embedding spaces—to stabilize the optimization process and enhance the estimation of update directions, thereby more effectively exploiting model vulnerabilities to elicit harmful responses. Experimental results on models including Vicuna-7B, Guanaco-7B, and Llama2-7B-Chat demonstrate that SM-GCG significantly enhances the attack success rate in white-box settings. The method achieves a 10–15% improvement in attack success rate over baseline methods against robust models such as Llama2, while also exhibiting enhanced transferability to black-box models. These findings indicate that spatial momentum effectively mitigates the problem of local optima in discrete prompt optimization, thereby offering a more powerful and generalizable approach for red-team assessments of LLM safety. Warning: This paper contains potentially offensive and harmful text.