The true triaxial stress are typical stress state in the deep underground. 3D surface flaws, one of the most common type of flaws, extensively existed in the rocks. Therefore, the study on evolution of the 3D surface flaw under true triaxial stress is crucial to determine the fracture behaviors of the rock in some deep underground spaces. Gypsum, as a rock-like material, has been extensively used in studies of crack initiation and propagation. In this study, we prefabricate a pair of 3D surface flaws at 45° in the cubic gypsum specimen and investigates the effect of the intermediate principal stress on initiation and peak stresses (characteristic stress thresholds) of flaws and crack propagation patterns of 3D surface flaws parallel to the intermediate principal stress. The true triaxial apparatus and acoustic emission (AE) technique were used to test and monitor the mechanical behaviors of the samples. The internal crack propagation pattern was observed by X-ray CT scan. The results demonstrate that the intermediate principal stress strongly affects crack patterns but has a limited influence on characteristic stress thresholds. Both the intermediate and minimum principal stresses affect the difference in the crack peak and initiation stress, which elucidates how the true triaxial stress affects the fracture behavior of the specimen. Additionally, the intermediate principal stress effect on characteristic stresses is closely related to the magnitude of minimum principal stress. When the magnitude of minimum principal stress is small, with the rising intermediate principal stress, the characteristic stresses increase slowly. When the magnitude of minimum principal stress is large, the intermediate principal stress almost has no effect on characteristic stresses. The surface wing cracks and anti-wing cracks initiate from the flaw when the magnitude of intermediate principal stress is relatively small. With the intermediate principal stress increasing, the surface crack propagation pattern is shift from tensile crack to shear crack. Through the CT image reconstruction technique, the propagation patterns of the inner tips of single 3D surface flaw were illustrated in this paper. It is observed that the large intermediate principal stress can restrict the crack wrapping and even make the internal flaw propagation patterns same with that on the specimen surface, providing insights into the validity of simplifying 3D flaws as 2D flaws for analyzing and computing crack propagation.

The elastic stiffness of spudcan foundations in stiff-over-soft clays exhibits changes similar to “punch-through” failure, creating significant uncertainty for jack-up platform operations. This study conducted a three-dimensional small-strain finite element analysis on this specific topic to discretely simulate the spudcan elastic stiffness profile in stiff-over-soft clay. The influence of the soil surface, layered interface, and their coupling effects were isolated and separately evaluated, and a simple semi-theoretical framework for the influence zone was proposed. The key parameters of layered soil (thickness ratio, shear modulus ratio, soil heterogeneity coefficient, and backflow) affecting the influence mechanism of spudcan elastic stiffness were evaluated and analyzed. It was found that the effects of the soil surface and layered interface competed with each other. The vertical deformation mechanism of the spudcan reduces the “punch-through” failure risk of elastic stiffness by transferring more of the soil deformation to the bottom soft clay layer. Based on the findings from the parameter study, a simplified profile is proposed to predict the variation of the spudcan elastic stiffness. The proposed prediction method provides a comprehensive view of elastic stiffness in stiff-over-soft clay for offshore in-site assessment.

China will launch the “Tianwen-IV” mission around 2030, focusing on the orbiting exploration of Jupiter and Callisto, a moon of Jupiter. As part of this ambitious mission, a main satellite will carry another satellite that will be released in the Jupiter system to continue its journey toward Uranus. Considering the current mission planning, we propose an inter-satellite radio-observation mode that differs from the conventional observation mode of tracking from Earth to precisely determine the orbit of the satellites. Given the significance of the Callisto gravity field model in both science objectives and satellite navigation, we have conducted a series of simulation experiments to evaluate the potential of this inter-satellite range-rate data for accurately estimating the Callisto gravity field. The results obtained from the analysis demonstrate that by utilizing 40 days of ground station observations, it is possible to estimate the gravity field model of Callisto up to a degree of 70. Remarkably, when combining these ground station observations with inter-satellite observations, a comparable level of accuracy can be achieved with just 10 days of observations. Furthermore, with reduced inter-satellite observation noise, accuracy improves, enabling estimation up to 80 degrees or higher. Initial inter-satellite distance selection impacts estimation accuracy. These findings serve as a valuable test bed for the future “Tianwen-IV” mission to perform precise orbit determination and gravity field model estimation to reduce reliance on deep space stations.

Textbook question answering is challenging as it aims to automatically answer various questions on textbook lessons with long text and complex diagrams, requiring reasoning across modalities. In this work, we propose MRHF, a novel framework that incorporates dense passage re-ranking and the mixture-of-experts architecture for TQA. MRHF proposes a novel query augmentation method for diagram questions and then adopts multi-stage dense passage re-ranking with large pretrained retrievers for retrieving paragraph-level contexts. Then it employs a unified question solver to process different types of text questions. Considering the rich blobs and relation knowledge contained in diagrams, we propose to perform multimodal feature fusion over the retrieved context and the heterogeneous diagram features. Furthermore, we introduce the mixture-of-experts architecture to solve the diagram questions to learn from both the rich text context and the complex diagrams and mitigate the possible negative effects between features of the two modalities. We test the framework on the CK12-TQA benchmark dataset, and the results show that MRHF outperforms the state-of-the-art results in all types of questions. The ablation and case study also demonstrates the effectiveness of each component of the framework.

Cross-modal retrieval, as an important emerging foundational information retrieval task, benefits from recent advances in multimodal technologies. However, current cross-modal retrieval methods mainly focus on the interaction between textual information and 2D images, lacking research on 3D data, especially point clouds at scene level, despite the increasing role point clouds play in daily life. Therefore, in this paper, we proposed a cross-modal point cloud retrieval benchmark that focuses on using text or images to retrieve point clouds of indoor scenes. Given the high cost of obtaining point cloud compared to text and images, we first designed a pipeline to automatically generate a large number of indoor scenes and their corresponding scene graphs. Based on this pipeline, we collected a balanced dataset called CRISP, which contains 10K point cloud scenes along with their corresponding scene images and descriptions. We then used state-of-the-art models to design baseline methods on CRISP. Our experiments demonstrated that point cloud retrieval accuracy is much lower than cross-modal retrieval of 2D images, especially for textual queries. Furthermore, we proposed ModalBlender, a tri-modal framework which can greatly improve the Text-PointCloud retrieval performance. Through extensive experiments, CRISP proved to be a valuable dataset and worth researching. (Dataset can be downloaded at https://github.com/CRISPdataset/CRISP.)

The synchronization stability of a complex network system of coupled phase oscillators is discussed. In case the network is affected by disturbances, a stochastic linearized system of the coupled phase oscillators may be used to determine the fluctuations of phase differences in the lines between the nodes and to identify the vulnerable lines that may lead to desynchronization. The main result is the derivation of the asymptotic variance matrices of the phase differences which characterizes the severity of the fluctuations. It is found that the cycle space of the graph of the system plays a role in this characterization. With theory of the cycle space, the effect of forming small cycles on the fluctuations is evaluated. It is proven that adding a new line or increasing the coupling strength of a line affects the fluctuations in the lines in any cycle including this line, while it does not affect the fluctuations in the other lines. In particular, if the phase differences at the synchronous state are not changed by these actions, then the affected fluctuations reduce.

Current news datasets merely focus on text features on the news and rarely leverage the feature of images, excluding numerous essential features for news classification. In this paper, we propose a new dataset, N24News, which is generated from New York Times with 24 categories and contains both text and image information in each news. We use a multitask multimodal method and the experimental results show multimodal news classification performs better than text-only news classification. Depending on the length of the text, the classification accuracy can be increased by up to 8.11%. Our research reveals the relationship between the performance of a multimodal classifier and its sub-classifiers, and also the possible improvements when applying multimodal in news classification. N24News is shown to have great potential to prompt the multimodal news studies.

This study selects yellow, red and orange phosphors used in high color rendering white packages, analyzes their luminescence and thermal properties, crystal structures and micro morphologies during both the high temperature and high moisture ageing test and the water immersion test, and finally figures out the degradation mechanisms of different phosphors. The results show that: 1) the hydrolysis reaction of phosphors under hygrothermal environment produces OH^- and increases the environment's pH value, which can lower the crystallinity of phosphor hosts, increase the lattice vibration and light-induced heat, and enhance the thermal quenching effect of phosphors. Meanwhile, the surface roughening of phosphor particles can increase the blue light scattering and lower its absorption and conversion efficiency; 2) the degradation trends of both luminescence and thermal properties of phosphors under the water immersion test are similar to those under high temperature and high moisture ageing test. So it is an effective method to assess the reliability of LED phosphors under hygrothermal environment.

Due to low power consumption, long lifetime and many other advantages, Light-emitting Diode (LED) has increased dramatically all over the world. Chip Scale Package (CSP) LED is a new LED package with small size, high current, and high reliability. For the CSP LED with smaller size and lower thermal resistance, phosphors and silicone are usually combined as the phosphors/silicone composite and prepared by using a high temperature cure process. However, for those CSPs which are not sufficiently cured, their reliability under a harsh environment (e.g. high temperatures and high humidity) will obviously decrease. In this study, the influence of temperature and ultraviolet light on the cure process of phosphor/silicone composites is studied and an optimal cure process is extracted accordingly. According to the cure experiment under different conditions, the results show that ultraviolet light and phosphor can promote the cure reaction of silicone. With the increase of ultraviolet light intensity and phosphor mass fraction, the cure rate of the silicone and phosphor/silicone composite is greatly increased as well.