Attitude-constrained interactive multi-model factor graph fusion for integrated navigation

With the flourishing of social media platforms, data in social networks, especially user-generated content, are growing rapidly, which makes it hard for users to select relevant content from the overloaded data. Recommender systems are thus developed to filter user-relevant content for better user experiences and also the commercial needs of social platform providers. Graph neural networks have been widely applied in recommender systems for better recommendation based on past interactions between users and corresponding items due to the graph structure of social data. Users might also be influenced by their social connections, which is the focus of social recommendation. Most works on recommendation systems try to obtain better representations of user embeddings and item embeddings. Compared with recommendation systems only focusing on interaction graphs, social recommendation has an additional task of combining user embedding from the social graph and interaction graph. This paper proposes a new method called SocialJGCF to address these problems, which applies Jacobi-Polynomial-Based Graph Collaborative Filtering (JGCF) to the propagation of the interaction graph and social graph, and a graph fusion is used to combine the user embeddings from the interaction graph and social graph. Experiments are conducted on two real-world datasets, epinions and LastFM. The result shows that SocialJGCF has great potential in social recommendation, especially for cold-start problems.

Group activity recognition aims to identify a consistent group activity from different actions performed by respective individuals. Most existing methods focus on learning the interaction between each two individuals (i.e., second-order interaction). In this work, we argue that the second-order interactive relation is insufficient to address this task. We propose a third-order active factor graph network, which models the third-order interaction in each pair of three active individuals. At first, to alleviate the noisy individual actions, we select active individuals by measuring each individual's influence. The individuals with the top-k largest influence weights are selected as active individuals. Then, for each three-individuals pair, we build a new factor node and contact the factor node with these individual nodes. In other words, we extend the base second-order interactive graph to a new third-order interactive graph, which is defined as factor graph. Next, we design a two-branch factor graph network, in which one branch is to consider all individuals (denoted as full factor graph) and the other one takes the active individuals into consideration (denoted as active factor graph). We leverage both the active and full factor graphs comprehensively for group activity recognition. Besides, to enforce group consistency, a consistency-aware reasoning module is designed with two penalty terms, which describe the inconsistency between individual actions and group activity respectively. Extensive experiments demonstrate that our method achieves state-of-the-art performance on four benchmark datasets, i.e., Volleyball, Collective Activity, Collective Activity Extended, and SoccerNet-v3 datasets. Visualization results further validate the interpretability of our method.

Many security sensors and other protection mechanisms are deployed at different levels to provide what is known as defensein-depth for systems and networks. However, the large volume of security alerts experienced makes it challenging for operators to analyze the attack situation and take an appropriate response. Based on network configurations there are two major challenges to display and analyze potentially very-large and complex graphs of multi-step cyber attacks against networks. One is to transform large quantities of network security data into real-time actionable intelligence. The other is to visualize the complex graphs, including all possible network attack paths, while still keeping complexity manageable. We have proposed a comprehensive and innovative approach that is based on of three bodies of work: attack graph research,1–4 alert correlation research,5–10 and attack visualization research.11–16 As can be seen in Figure 1, there are two major components: attack analysis and attack-graph visualization modules. Based on the proposed these, we can easily display and analyze potentially very-large and complex graphs of multi-step cyber attacks against networks based upon network vulnerabilities, connectivity, and attacker exploits. The attack graph visualization module consists of three fundamental blocks: hierarchy construction, hierarchical graph complexity reduction, and radial space-filling (RSF) hierarchy visualization. The visualization module provides access to all possible network attack paths while keeping complexity manageable via interactive hierarchical graph complexity reduction. Moreover, the RSF technique has the advantage of efficiently using the display space while conveying the hierarchical strucFigure 1. Analysis and visualization model for large complex multistep cyber attack graphs.

Graph neural network (GNN) has the proven ability to learn feature representations from graph data, and has been utilized for the tasks of predicting the machinery remaining useful life (RUL). However, existing methods only focus on a single graph structure and cannot integrate the correlation information contained in multi-graph structures. To address these issues, a multi-graph structure GNN prediction method with attention fusion (MGAFGNN) is proposed in this paper for GNN-based bearing RUL prediction. Specifically, a multi-channel graph attention module is designed to effectively learn the similar features of node neighbors from different graph data and capture the multi-scale latent features of nodes through the nonlinear transformation. Furthermore, a multi-graph attention fusion module (MGAFM) is proposed to extract the collaborative features from the interaction graph, thereby fusing the feature embeddings from different graph structures. The fused feature representation is sent to the long short-term memory network to further learn the temporal features and achieve RUL prediction. The experimental results on two bearing datasets demonstrate that MGAFGNN outperforms existing methods in terms of prediction performance by effectively incorporating multi-graph structural information.

Spatial transcriptomics enables genome-wide expression analysis within native tissue context, yet identifying spatial domains remains challenging due to complex gene-spatial interactions. Existing methods typically process spatial and feature views separately, fusing only at output level - an "encode-separately, fuse-late" paradigm that limits multi-scale semantic capture and cross-view interaction. Accordingly, stMFG is proposed, a multi-scale interactive fusion graph network that introduces layer-wise cross-view attention to dynamically integrate spatial and gene features after each convolution. The model combines cross-view contrastive learning with spatial constraints to enhance discriminability while maintaining spatial continuity. On DLPFC and breast cancer datasets, stMFG outperforms state-of-the-art methods, achieving up to 14% ARI improvement on certain slices.

An increasing number of people tend to convey their opinions in different modalities. For the purpose of opinion mining, sentiment classification based on multimodal data becomes a major focus. In this work, we propose a novel Multimodal Interactive and Fusion Graph Convolutional Network to deal with both texts and images on the task of document-level multimodal sentiment analysis. The image caption is introduced as an auxiliary, which is aligned with the image to enhance the semantics delivery. Then, a graph is constructed with the sentences and images generated as nodes. In line with the graph learning, the long-distance dependencies can be captured while the visual noise can be filtered. Specifically, a cross-modal graph convolutional network is built for multimodal information fusion. Extensive experiments are conducted on a multimodal dataset from Yelp. Experimental results reveal that our model obtains a satisfying working performance in DLMSA tasks.

This work presents a novel method to efficiently factorize the combination of multiple factor graphs having common variables of estimation. Variable ordering, a well-known variable elimination technique in linear algebra is employed to efficiently solve a factor graph. Our primary contribution in this work is to reuse the variable ordering of the graphs being combined to find the ordering of the fused graph called fusion ordering. By reusing the variable ordering of the parent graphs we were able to produce an order-of-magnitude difference in the time required for solving the fused graph. A formal verification is provided to show that the proposed strategy does not violate any of the relevant standards. The fusion ordering is experimented on the standard dataset used in the sparse linear algebra community called SuiteSparse [1]. Recent factor graph formulation for Simultaneous Localization and Mapping (SLAM) like Incremental Smoothing and Mapping (ISAM) using the Bayes tree has been very successful and garnered much attention. In the case of mapping, multi-robot system has a great advantage over a single robot that provides faster map coverage and better estimation quality. We also demonstrate the improvement of our ordering scheme on a real-world multi-robot AP Hill dataset [2].

We propose a novel privacy-preserving COVID-19 risk assessment algorithm that can make a fundamental contribution to the development of the next generation resilient public health and health care systems. The proposed algorithm, ShareTrace, uses a hyperlocal interaction graph to capture direct and indirect physical interactions among users. Combining user-reported symptoms that are propagated through the hyperlocal interaction graph via a novel message passing algorithm, ShareTrace is able to pick up early warning signals based on the combination of interactions with others and symptoms. The proposed algorithm is inspired by the belief propagation algorithm and iterative decoding of low-density parity-check codes over factor graphs. Our evaluation on synthetic data shows the efficiency and efficacy of the proposed solution.

In urban road environments, global navigation satellite system (GNSS) signals may be interrupted due to occlusion by buildings and obstacles, resulting in reduced accuracy and discontinuity of combined GNSS/inertial navigation system (INS) positioning. Improving the accuracy and robustness of combined GNSS/INS positioning systems for land vehicles in the presence of GNSS interruptions is a challenging task. The main objective of this paper is to develop a method for predicting GNSS information during GNSS outages based on a long short-term memory (LSTM) neural network to assist in factor graph-based combined GNSS/INS localization, which can provide a reliable combined localization solution during GNSS signal outages. In an environment with good GNSS signals, a factor graph fusion algorithm is used for data fusion of the combined positioning system, and an LSTM neural network prediction model is trained, and model parameters are determined using the INS velocity, inertial measurement unit (IMU) output, and GNSS position incremental data. In an environment with interrupted GNSS signals, the LSTM model is used to predict the GNSS positional increments and generate the pseudo-GNSS information and the solved results of INS for combined localization. In order to verify the performance and effectiveness of the proposed method, we conducted real-world road test experiments on land vehicles installed with GNSS receivers and inertial sensors. The experimental results show that, compared with the traditional combined GNSS/INS factor graph localization method, the proposed method can provide more accurate and robust localization results even in environments with frequent GNSS signal loss.

Indoor localization for unmanned aerial vehicles (UAVs) remains challenging in GNSS-denied environments due to the difficulty of position calibration of multiple ultra-wideband (UWB) anchors and the asynchronous fusion of heterogeneous sensors. This paper proposes a multi-sensor fusion localization framework that integrates multi-anchor one-shot calibration with factor graph optimization (FGO). First, Landmark Multidimensional Scaling (LMDS) is used to reconstruct the relative geometry of the anchors and the onboard tag from ranging measurements. Then, rigid Procrustes alignment is performed using a small number of anchors with known coordinates in the East–North–Up (ENU) frame to recover the transformation to the ENU frame, thereby enabling efficient position calibration of multiple UWB anchors and UAV pose initialization. Subsequently, a tightly coupled factor graph is constructed by incorporating inertial measurement unit (IMU) pre-integration, UWB ranging, laser rangefinder height measurements, and visual–inertial odometry (VIO) pose constraints. The resulting nonlinear optimization problem is solved using incremental smoothing, which improves robustness against non-line-of-sight (NLOS) errors and long-term drift. Experimental results on anchor calibration, public datasets, and real-world indoor UAV flights demonstrate that the proposed method improves the accuracy and robustness of indoor UAV localization. In particular, on the real-world rectangle trajectory, FGO-TC reduces the RMSE by approximately 38.8% compared with FGO-LC.

Document Similarity Detection (DSD) is important for checking about plagiarism and duplicate project approval. Abundant word-based detection methods are not enough for actual requirements. The semantic level DSD has recently become a challenging direction because semantic information needs mine. Firstly, we propose a Contextual Multi-feature Semantic Fusion (CMSF) module to purify keyword recognition, and then propose a Concept Graph (CG) structure for document entity. CMSF employs multi-feature enhanced semantics to represent entity, and CG leverages the text interaction graph and text semantic representation vector as initial features, and then Graph Convolutional Network (GCN) uses the features to match document. Extensive experiments based on the real dataset show that CMSF-GCN may converge quickly and get a high accuracy rate compared with recent methods about natural language matching.

Accurate and robust underwater localization remains challenging due to limited absolute positioning availability, asynchronous multi-sensor updates, and non-Gaussian measurement disturbances. This paper presents MEKF-SWFGO, an uncertainty-aware hybrid framework that combines a Manifold Extended Kalman Filter (MEKF) front-end with a Sliding-Window Factor Graph Optimizer (SWFGO) back-end for cooperative INS/DVL/LBL navigation. The front-end enforces attitude consistency on the Lie group SO(3), employs a trapezoidal IMU preintegration for stable propagation, and applies a Huber M-estimator to downweight outliers. The back-end jointly refines recent trajectory segments using numerical Jacobian between-factors and adaptive covariance weighting, while an uncertainty-driven switching mechanism balances real-time filtering and delayed global refinement. Extensive experiments on real AUV data demonstrate that MEKF-SWFGO substantially improves localization accuracy and robustness: total position RMSE is reduced from 33.67 m (CEKF), 21.46 m (MEKF) and 17.05 m (UKF) to 12.10 m.Velocity RMSE falls to 0.44 m/s, representing an 19.1% reduction relative to UKF. Yaw RMSE is improved to 0.74°, a 50.4% reduction over CEKF. Statistical metrics and CDF analyses confirm that MEKF-SWFGO yields tighter, less heavy-tailed error distributions in position, velocity and attitude. These results indicate that the proposed uncertainty-aware manifold and sliding-window fusion is a practical and effective solution for resilient underwater navigation in real operating conditions.

Modified attitude factor graph fusion method for unmanned helicopter under atmospheric disturbance

The integrated strapdown inertial navigation system (SINS)/global navigation satellite system (GNSS) has been widely adopted in railway positioning applications. However, conventional filtering-based approaches are fundamentally constrained by their dependence on instantaneous state estimates while failing to exploit valuable historical measurement information. To overcome this limitation, we develop a factor graph optimization (FGO) framework to enhance data utilization efficiency. During GNSS signal outages, existing implementations typically preserve only SINS factors while excluding GNSS observations, leading to unbounded error growth. To bridge this gap, our novel solution integrates a gated recurrent unit (GRU) with an Improved Bidirectional Long Short-Term Memory (IBiLSTM) network to generate accurate pseudo-GNSS observations through effective learning from both preceding and subsequent GNSS data sequences. Comprehensive evaluation under GNSS-denied conditions demonstrates that our approach achieves significant improvements over conventional neural network-aided methods, with horizontal root mean square error (RMSE) reductions of 49.22% (simulation) and 36.24% (onboard vehicle). Subsequent FGO processing yields additional performance gains, further reducing RMSE by 46.67% (simulation) and 35.31% (onboard vehicle). This innovative methodology effectively maintains positioning accuracy and ensures navigation continuity during GNSS outages, thereby offering a robust solution for train positioning systems in challenging environments.

The signal blockage and multipath effects of the Global Navigation Satellite System (GNSS) caused by urban canyon scenarios have brought great technical challenges to the positioning and navigation of autonomous vehicles. In this paper, an improved factor graph optimization algorithm enhanced by a resilient noise model is proposed. The measurement noise is resilient and adjusted based on an approximate Gaussian distribution-based estimation. In estimating and adjusting the noise parameters of the measurement model, the error covariance matrix of the multi-sensor fusion positioning system is dynamically optimized to improve the system accuracy. Firstly, according to the approximate Gaussian statistical property of the GNSS/odometer velocity residual sequence, the measured data are divided into an approximate Gaussian fitting region and an approximate Gaussian convergence region. Secondly, the interval is divided according to the measured data, and the corresponding variational Bayesian network and Gaussian mixture model are used to estimate the innovation online. Further, the noise covariance matrix of the adaptive factor graph-based model is dynamically optimized using the estimated noise parameters. Finally, based on low-cost inertial navigation equipment, GNSS, odometer, and vision, the algorithm is implemented and verified using a simulation platform and real-vehicle road test. The experimental results show that in a complex urban road environment, compared with the traditional factor graph fusion localization algorithm, the maximum improvement in accuracy of the proposed algorithm can reach 65.63%, 39.52%, and 42.95% for heading, position, and velocity, respectively.