Search Results (316)

Rock bolts are crucial components in the subterranean support systems in underground mines that provide adequate structural reinforcement to the rock mass to prevent unforeseen hazards like rockfalls. This makes frequent assessments of such bolts critical for maintaining rock mass stability and minimising risks in underground mining operations. Where manual surveying of rock bolts is challenging due to the low-light conditions in the underground mines and the time-intensive nature of the process, automated detection of rock bolts serves as a plausible solution. To that end, this study focuses on the automatic identification of rock bolts within medium- to large-scale 3D point clouds obtained from underground mines using mobile laser scanners. Existing techniques for automated rock bolt identification primarily rely on feature engineering and traditional machine learning approaches. However, such techniques lack robustness as these point clouds present several challenges due to data noise, varying environments, and complex surrounding structures. Moreover, the target rock bolts are extremely small objects within large-scale point clouds and are often partially obscured due to the application of reinforcement shotcrete. Addressing these challenges, this paper proposes an approach termed DeepBolt, which employs a novel two-stage deep learning architecture specifically designed for handling severe class imbalance for the automatic and efficient identification of rock bolts in complex 3D point clouds. The proposed method surpasses state-of-the-art semantic segmentation models by up to 42.5% in Intersection over Union (IoU) for rock bolt points. Additionally, it outperforms existing rock bolt identification techniques, achieving a 96.41% precision and 96.96% recall in classifying rock bolts, demonstrating its robustness and effectiveness in complex underground environments. Full article

Based on the need to enhance the seismic performance of point-supported steel frame precast cladding panel systems, this study proposes a novel friction-energy-dissipating connection joint. Through establishing refined finite element models, low-cycle reversed loading analyses and elastoplastic time-history analyses were conducted on three frame systems. These included a benchmark bare frame and two cladding-panel-equipped frame structures configured with energy-dissipating joints using different specifications of high-strength bolts (M14 and M20, respectively). The low-cycle reversed loading results demonstrate that the friction energy dissipation of the novel joints significantly improved the seismic performance of the frame structures. Compared to the bare frame, the frames equipped with cladding panels using M14 bolts demonstrated 10.9% higher peak lateral load capacity, 17.6% greater lateral stiffness, and 45.6% increased cumulative energy dissipation, while those with M20 bolts showed more substantial improvements of 22.8% in peak load capacity, 32.0% in lateral stiffness, and 64.2% in cumulative energy dissipation. The elastoplastic time-history analysis results indicate that under seismic excitation, the maximum inter-story drift ratios of the panel-equipped frames with M14 and M20 bolts were reduced by 42.7% and 53%, respectively, compared to the bare frame. Simultaneously, the equivalent plastic strain in the primary structural members significantly decreased. Finally, based on the mechanical equilibrium conditions, a calculation formula was derived to quantify the contribution of joint friction to the horizontal load-carrying capacity of the frame. Full article

As a plant-specific peroxidase family, class III peroxidase (PRX) plays an important role in plant growth, development, and stress response. In this study, a preliminary functional analysis of CqPRX9L1 was conducted. Bioinformatics analysis revealed that CqPRX9L1 encodes a 349-amino acid protein belonging to the plant-peroxidase-like superfamily, featuring a transmembrane domain and cytoplasmic localization. The promoter region of CqPRX9L1 harbors various cis-acting elements associated with stress responses, hormone signaling, light regulation, and meristem-specific expression. The tissue-specific expression pattern of the CqPRX9L1 gene and its characteristics in response to different stresses were explored using subcellular localization, quantitative real-time PCR (qRT-PCR), and heterologous transformation into Arabidopsis thaliana. The results showed that CqPRX9L1, with a transmembrane structure, was localized in the cytoplasm, which encodes 349 amino acids and belongs to the plant-peroxisome-like superfamily. The promoter region contains stress-response elements, hormone-response elements, light-response elements, and meristem expression-related elements. The expression of CqPRX9L1 was relatively higher in ears and roots at the panicle stage than in stems and leaves. CqPRX9L1 showed a dynamic expression pattern of first decreasing and then increasing under abiotic stresses such as 15% PEG 6000, low temperature, and salt damage, with differences in response time and degree. CqPRX9L1 plays an important role in response to abiotic stress by affecting the activity of antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (POD), as well as the synthesis and decomposition of proline (Pro). CqPRX9L1 also affects plant bolting and flowering by regulating key flowering genes (such as FT and AP1) and gibberellin (GA)-related pathways. The results establish a foundation for revealing the functions and molecular mechanisms of the CqPRX9L1 gene. Full article

In advanced structural applications—aerospace and automotive—fiber-laminated composite (FRP) materials are increasingly used for their superior strength-to-weight ratios, making the reliability of their mechanical joints a critical concern. Mechanically fastened joints play a major role in ensuring the structural stability of FRP Composite structures; however, accurately predicting their failure behavior remains a major challenge due to the anisotropic and heterogeneous nature of composite materials. This paper presents a progressive damage modeling approach to investigate the failure modes and joint strength of mechanically fastened carbon fiber-laminated (CFRP) composite joints. A 3D constitutive model based on continuum damage mechanics was developed and implemented within a three-dimensional finite element framework. The joint model comprises a composite plate, a steel plate, a steel washer, and steel bolts, capturing realistic assembly behavior. Both single- and double-lap joint configurations, featuring single and double bolts, were analyzed under tensile loading. The influence of clamping force on joint strength was also investigated. Model predictions were validated against existing experimental results, showing a good correlation. It was observed that double-lap joints exhibit nearly twice the strength of single-lap joints and can retain up to 85% of the strength of a plate with a hole. Furthermore, double-lap configurations support higher clamping forces, enhancing frictional resistance at the interface and load transfer efficiency. However, the clamping force must be optimized, as excessive values can induce premature damage in the composite before external loading. The stiffness of double-bolt double-lap (3DD) joints was found to be approximately three times that of single-bolt single-lap (3DS) joints, primarily due to reduced rotational flexibility. These findings provide useful insights into the design and optimization of composite bolted joints under tensile loading. Full article

Red-layer soft rock has characteristics such as softening when encountering water, loose structure, and significant rheological properties. In tunnel engineering, it is necessary to sort out and analyze the stress characteristics of its support structure. This paper focuses on the mechanical behavior and support effect during the construction of Neogene red-layer soft rock tunnels. Through field monitoring, it explores the mechanical characteristics of Huizhou Tunnel under complex geological conditions in depth. This study adopted a remote wireless monitoring system to conduct real-time monitoring of key indicators including tunnel surrounding rock pressure, support structure stress, and deformation, obtaining a large amount of detailed data. An analysis revealed that the stress experienced by rock bolts is complex and varies widely, with stress values between 105 and 330.5 MPa. The peak axial force at a depth of 2.5 m reflects that the thickness of the loosened zone in the surrounding rock is approximately 2.5 m. The compressive stress in the steel arches of the primary support does not exceed 305.3 MPa. Shotcrete effectively controls the surrounding rock deformation, but the timing of support installation needs careful selection. The stress in the secondary lining is closely related to the primary support. The research findings provide an important theoretical basis and practical guidance for optimizing the support design of red-bed soft rock tunnels and enhancing construction safety and reliability. Full article

Introduction: Cold welding is an anecdotally well-known complication of removal of metalwork, most commonly at the screw–plate interface, and can often complicate extraction of implants after fracture fixation. Even though this phenomenon is familiar amongst the orthopedic community, there is relatively little formalized discussion or literature pertaining to its identification and management clinically. In addition, as far as we can establish, there does not seem to be a paper that discusses the various techniques described in the literature that are employed to combat cold welding. Methods: A systematic review was carried out in accordance with the PRISMA guidance, with two independent reviewers and a third person to arbitrate for any discrepancies. Manuscripts were identified using a search of PubMed/MEDLINE and Google Scholar. Studies eligible for inclusion were tabulated and the results categorized qualitatively with respect to the technique described for removal of the implants. Results: A total of 272 manuscripts were identified using a search of PubMed/MEDLINE and Google Scholar, and of these 14 were ruled to be eligible for inclusion reporting on 292 patients. Common locations of the cold-welded screws included femur, tibia, distal radius and clavicle. The most common technique for metalwork removal was using either bolt cutters or burrs to cut the plates between the screws and mobilize the screw and plate as one unit. Other techniques included using specialized removal tools and cutting between the screw head and body. There was no appreciable correlation between the specific anatomic location of the welded implant and the technique used in its removal. From the studies, it was found that, of the total number of screws (n = 1654), 58 (3.5%) were cold welded. The mean time to metalwork removal was 1104 days (36.8 months). Conclusions: As far as we can tell, this is the first systematic review pertaining to the phenomenon of cold welding specifically, and with this project we have collated the techniques used to remove implants affected by cold welding from a variety of different articles. Our work aims to highlight the relative paucity of literature in this area and provide a number of accessible and safe techniques to facilitate the removal of cold-welded implants in fracture fixation. Full article

Orphan genes (OGs), which are unique to a specific taxon and have no detectable sequence homology to any known genes across other species, play a pivotal role in governing species-specific phenotypic traits and adaptive evolution. In this study, 20 OGs of Chinese cabbage (Brassica rapa OGs, BrOGs) were transferred into Arabidopsis thaliana by genetic transformation to construct an overexpression library in which 50% of the transgenic lines had a delayed flowering phenotype, 15% had an early flowering phenotype, and 35% showed no difference in flowering time compared to control plants. There were many other phenotypes attached to these transgenic lines, such as leaf color, number of rosette leaves, and silique length. To understand the impact of BrOGs on delayed flowering, BrOG142OE, which showed the most significantly delayed flowering phenotype, was chosen for further analysis, and BrOG142 was renamed BOLTING RESISTANCE 4 (BR4). In BR4OE, the expression of key flowering genes, including AtFT and AtSOC1, significantly decreased, and AtFLC and AtFRI expression increased. GUS staining revealed BR4 promoter activity mainly in the roots, flower buds and leaves. qRT-PCR showed that BR4 primarily functions in the flowers, flower buds, and leaves of Chinese cabbage. BR4 is a protein localized in the nucleus, cytoplasm, and cell membrane. The accelerated flowering time phenotype of BR4OE was observed under gibberellin and vernalization treatments, indicating that BR4 regulates flowering time in response to these treatments. These results provide a foundation for elucidating the mechanism by which OGs regulate delayed flowering and have significance for the further screening of bolting-resistant Chinese cabbage varieties. Full article

This study analyzes the deformation and internal force changes of the main tunnel during the cutting process of the pipe jacking method for cross passages. A combination of field monitoring and numerical simulation was used to investigate a construction case of the pipe jacking method for the cross passage of Zhengzhou Metro Line 12. The study provides an in-depth analysis of the stress characteristics of the main tunnel structure during the segment-cutting process. The research findings indicate that during the pre-support stage, the internal support system helps to disperse external water and soil pressure, thereby reducing the internal forces and deformation of the tunnel. In the segment-cutting stage, the horizontal diameter of the main tunnel near the hole location gradually increases, while the vertical diameter decreases. At the same time, the stress on the bolts also rises, with the circumferential bolt stress exceeding that of the longitudinal bolts, eventually approaching their yield strength. The upper and lower ends of the tunnel opening are cut to form cantilever ends, leading to inward converging deformation. This deformation causes the internal forces to disperse toward both sides of the opening, resulting in a noticeable increase in internal force at the 90° position of the semi-cutting ring. The research findings provide a theoretical reference for understanding the deformation patterns and internal force transfer mechanisms of the main tunnel structure during the construction process of cross passages using the pipe jacking method. Full article

In order to make the anchor bolt support prestress field fully diffuse in the composite rock stratum, improve the overall bearing capacity of surrounding rock, and give full play to the role of active support of the anchor bolt, a self-made 1:1-scale composite rock stratum similarity simulation test bed was used to compare and analyze the distribution of the anchor bolt support prestress field using different anchoring surrounding rock lithology and anchorage lengths, and the principle for optimum selection of anchoring parameters of composite rock stratum was proposed based on the test results. Considered from the point of view of stress diffusion, the effect of prestress diffusion of end anchorage bolts is better than that of lengthening anchorage; at the same time, the anchorage section should be preferentially arranged in hard rock, and the area of anchorage section near the free section should avoid the structural plane of surrounding rock. In conclusion, an industrial test was carried out under the conditions of a deep composite roof of the 2# coal seam in Qinyuan Mining Area, which determined a reasonable anchoring method and position of the composite roof under different conditions and achieved good results. Full article

The attenuation of bolt preload is a critical factor leading to bolt fatigue failure, whereas the study of the nonlinear attenuation behavior of preload and its mechanism during installation is an inevitable challenge in engineering practice. The attenuation of the preload of a bolt is mainly related to the stiffness of the bolt body as well as the stiffness of the connected parts. This study aimed to develop an experimental system to analyze the nonlinear attenuation behavior of preload during bolt tightening. First, a simulation system replicating the bolt installation process was constructed in a laboratory setting, incorporating blade and pitch bearing specimens identical to those used in a 10 MW wind turbine, restoring the stiffness coupling characteristics of the “composite-metal bearing” heterogeneous interface at the blade root through a 1:1 full-scale simulation system for the first time. Second, ultrasonic preload measurement equipment was employed to monitor preload variations during the bolt tightening process. Finally, the instantaneous preload decay rate of the wind turbine blade-root bolts and the over-draw coefficient were quantified. Experiments have shown that the preload decay rate of commonly used M36 leaf root bolts is 11–16%. If a more precise value is required, each bolt needs to be calibrated. These findings provide valuable insights for optimizing bolt installation procedures, enabling precise preload control to mitigate fatigue failures caused by abnormal preload attenuation. Full article

Bolt connections are the primary component of beam–column joints, which frequently become loose during their service life due to environmental factors. Assessing the tightness of bolts is essential for maintaining structural integrity and safety. Although the guided wave method has been proven effective for detecting bolt looseness, the severe dispersion properties and complex structure of beam–column joints pose difficulties for the quantitative evaluation of bolt looseness. Therefore, a deep neural network model integrating a convolutional neural network (CNN), long short-term memory (LSTM), and multi-head self-attention mechanism (MHSA) is introduced to identify the degree of looseness in multiple bolts using SH-typed guided waves. The dispersion properties of the I-shaped steel beam were analyzed using the semi-analytical finite element method, and a mode weight coefficient was presented to clarify the mode distribution under different types of external loads. Two pairs of transducers arranged on the same side of the bolt-connected region were utilized to obtain the directly incoming and end-reflected wave packets from four wave propagation paths. The received signals were converted into time–frequency spectra, and the effective components were extracted to form the input pattern for the neural network. Numerical simulations were performed on a beam–column joint with eight bolts, and the number of training samples was increased using data augmentation techniques. The results indicate that the CNN-LSTM-MHSA model can accurately estimate the bolt looseness conditions better than other methods. Noise injection testing was also conducted to investigate the effect of measurement noise. Full article

Cleaning operations in narrow pipelines are often hindered by limited maneuverability and low efficiency, necessitating the development of a high-performance and highly adaptable robotic solution. To address this challenge, this study proposes a pipeline-cleaning robot specifically designed for the heat-exchange tubes of industrial heat exchangers. The robot features a dual-wheel cross-drive configuration to enhance motion stability and integrates a gear–rack-based alignment mechanism with a cam-based propulsion system to enable autonomous deployment and cleaning via a flexible arm. The robot adopts a modular architecture with a separated body and cleaning arm, allowing for rapid assembly and maintenance through bolted connections. A vision-guided control system is implemented to support accurate positioning and task scheduling within the primary pipeline. Experimental results demonstrate that the robot can stably execute automatic navigation and sub-pipe cleaning, achieving pipe-switching times of less than 30 s. The system operates reliably and significantly improves cleaning efficiency. The proposed robotic system exhibits strong adaptability and generalizability, offering an effective solution for automated cleaning in confined pipeline environments. Full article

The accurate detection of surface bolt defects in railway steel truss bridges plays a vital role in maintaining structural integrity. Conventional manual inspection techniques require extensive labor and introduce subjective assessments, frequently yielding variable results across inspections. While UAV-based approaches have recently been developed, they still encounter significant technical obstacles, including small target recognition, background complexity, and computational limitations. To overcome these challenges, CSEANet is introduced—an improved YOLOv8-based framework tailored for bolt defect detection. Our approach introduces three innovations: (1) a sliding-window SAF preprocessing method that improves small target representation and reduces background noise, achieving a 0.404 mAP improvement compared with not using it; (2) a refined network architecture with BSBlock and MBConvBlock for efficient feature extraction with reduced redundancy; and (3) a novel BoltFusionFPN module to enhance multi-scale feature fusion. Experiments show that CSEANet achieves an mAP@50:95 of 0.952, confirming its suitability for UAV-based inspections in resource-constrained environments. This framework enables reliable, real-time bolt defect detection, supporting safer railway operations and infrastructure maintenance. Full article

This study focuses on the importance of the real-time monitoring of bolt loads in roadways affected by high-intensity mining and the limitations of conventional monitoring methods. Fiber Bragg grating (FBG) sensors were embedded and encapsulated in rock bolts, and tensile tests were conducted indoors to verify their feasibility. The research was conducted using the consolidated face of the Bultai Coal Mine in the Shendong Mining Area as the engineering background. Real-time monitoring wavelength data from the FBG bolt sensor were obtained through field tests. The analysis of the data aimed to assess the condition of the FBG sensor and variations in axial force within the service bolts of the mining roadway. Using these monitoring results, the real-time stability and safety of the roadway bolts were evaluated. The study indicates that as the working face advances, the axial force in the bolt progressively rises under the effect of mine pressure. The left gang bolt rod’s shaft force changes significantly, while the right gang’s change is relatively small. When the working face moves 60 m past the bolt rod, the axial force in the bolt rises sharply. Moreover, the axial force at different positions of the left and right gang bolts exhibits a distinct variation pattern. The real-time monitoring of bolt support in the return roadway provides essential data for assessing bolt safety. Full article

The degeneration of germplasm is a key factor limiting the yield and quality of Gastrodia elata Blume. Sexual reproduction is a primary method to address this degeneration, while the number of flowers and capsules is directly related to sexual reproduction. However, the genetic mechanisms underlying the high flower/fruit-bearing traits in G. elata remain unclear. We first compared the quantitative and qualitative traits during the flowering to fruiting period of G. elata, including bolting height, flowering quantity, flowering time, fruiting quantity, capsule spacing, seed quality, etc. The natural materials were selected by multi-capsule and few-capsule for transcriptome analysis to screen the differentially expressed genes (DEGs); the candidate gene GePIF4 was suspected to regulate the formation of multiple flowers and fruits. It was confirmed that GePIF4 has multiple biological functions in the overexpression of transgenic lines, including increasing numbers of vegetative propagation corms (VPCs) and promoting the growth of G. elata. Through comparative transcriptomic analysis of EV and OE-GePIF4 transgenic lines, the transcriptional regulatory network of GePIF4 was identified, and transient expression of GePIF4 was demonstrated to significantly promote gastrodin accumulation. The dual-LUC assay and in vitro yeast one hybrid results showed that GePIF4 could directly bind to GeRAX2 to regulate multi-capsule formation, and GePIF4 could directly bind to GeC4H1 to promote gastrodin accumulation. Therefore, we elucidate the role of GePIF4 in multi-capsule formation and secondary metabolite accumulation, thereby laying the groundwork for the genetic improvement of G. elata germplasm resources. Full article