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In response to the deformation and failure of surrounding rock in large section chamber underground roadways of coal mines, this study focuses on the sorting and filling of large section chamber underground roadways in Ulan Mulun coal mine. Similar simulation experiments are conducted using monotonically increasing and constant load uniaxial compression methods to investigate the deformation and failure laws of surrounding rock in large section chamber underground roadways. The results show the following points. ① The failure evolution and deformation displacement trends of the two loading methods are similar in the compaction stage, elastic deformation stage, and micro fracture stable development stage. ② The sample using monotonically increasing loading method has fewer cracks but larger crack gaps. The sample suddenly breaks along the main crack, during which a large amount of debris flies out. The deformation of the sample is mainly concentrated at the boundary of the surrounding rock. More energy is released during the failure, but the duration of energy release after the peak is relatively short. ③ The stress of the specimen loaded with a constant load remains constant, and the strain slowly increases, during which a large number of small cracks are generated. The deformation position of the specimen mainly surrounds the chamber, and the energy released during failure is relatively small, but the duration of energy release after the peak is longer. Based on the deformation and failure law of the surrounding rock of the large section chamber, a bolt and cable support scheme is proposed. A long anchor cable is installed at the top of the chamber to connect the roof and the hard rock above it as a whole. The inclined anchor rods are installed at the coal rock interface of the roadway to tightly connect the coal rock interface with the surrounding rock mass. The numerical simulation results show that after support, the stress, displacement, and plastic zone of the surrounding rock are significantly reduced, the stability of the surrounding rock is greatly improved, and the support effect is good.

In order to investigate the acoustic vibration characteristics of steel-concrete composite (SCC) beams under train excitation, a 50 m simply supported SCC beam on a high-speed railway with a train speed of 400 km/h was taken as the subject. The acoustic vibration responses of the bridge under vehicle load were calculated using a hybrid Finite Element-Boundary Element-Statistical Energy Analysis (FE- BE-SEA) prediction method. The results were compared with those of a concrete simply supported box beam of similar span under the same excitation conditions. The effects of track parameters (such as damping pads) and structural parameters (including deck thickness and diaphragm spacing) on the vibration and acoustic radiation characteristics of the bridge were studied. The results showed that, among the components of the steel-concrete composite beam, the deck exhibited the highest total vibration acceleration level. In most frequency bands, compared with SCC, the vibration and sound responses of concrete beam were significantly lower, with the vibration responses of the concrete web being reduced the most. The damping pads were found to be highly effective in vibration reduction and noise attenuation, particularly in the mid-to-high frequency ranges. Changing the thickness of the bridge deck reduced the structural noise of the SCC. When the deck thickness increased by 50%, the total sound pressure levels (SPLs) of the structural noise changed by -3.0 dB(A) to -2.9 dB(A). Reducing the diaphragm spacing also significantly reduced the structural noise of the bridge. When the diaphragm spacing was reduced by 50%, the total SPLs changed by -5.6 dB(A) to -5.0 dB(A). [ABSTRACT FROM AUTHOR]

Fire and smoke detection is crucial for the safe mining of coal energy, but previous fire-smoke detection models did not strike a perfect balance between complexity and accuracy, which makes it difficult to deploy efficient fire-smoke detection in coal mines with limited computational resources. Therefore, we improve the current advanced object detection model YOLOv8s based on two core ideas: (1) we reduce the model computational complexity and ensure real-time detection by applying faster convolutions to the backbone and neck parts; (2) to strengthen the model's detection accuracy, we integrate attention mechanisms into both the backbone and head components. In addition, we improve the model's generalization capacity by augmenting the data. Our method has 23.0% and 26.4% fewer parameters and FLOPs (Floating-Point Operations) than YOLOv8s, which means that we have effectively reduced the computational complexity. Our model also achieves a mAP (mean Average Precision) of 91.0%, which is 2.5% higher than the baseline model. These results show that our method can improve the detection accuracy while reducing complexity, making it more suitable for real-time fire-smoke detection in resource-constrained environments. [ABSTRACT FROM AUTHOR]

The organic–inorganic composites F70-TiO2, based on fullerene with carboxyl group derivatives and TiO2 semiconductor, have been designed and constructed to become an optical-functional photocatalyst via the facile sol–gel method. The composite photocatalyst obtained shows excellent photocatalytic activity for the high-efficiency conversion of benzylamine (BA) to N-benzylidene benzylamine (NBBA) with air pressure at a normal temperature under visible light irradiation. By optimizing the composition, the composites with the 1:15 mass ratio of F70 and TiO2, denoted as F70-TiO2(1:15), demonstrated the highest reaction efficiency for benzylamine (>98% conversion) to N-benzylidene benzylamine (>93% selectivity) in this study. However, pure TiO2 and fullerene derivatives (F70) exhibit decreased conversion (56.3% and 89.7%, respectively) and selectivity (83.8% and 86.0%, respectively). The UV–vis diffuse reflectance spectra (DRS) and Mott–Schottky experiment's results indicate that the introduction of fullerene derivatives into anatase TiO2 would greatly broaden the visible light response range and adjust the energy band positions of the composites, enhancing the sunlight utilization and promoting the photogenerated charge (e−-h+) separation and transfer. Specifically, a series of results on the in situ EPR tests and the photo-electrophysical experiment indicate that the separated charges from the hybrid could effectively activate benzylamine and O2 to accelerate the formation of active intermediates, and then couple with free BA molecules to form the desired production of N-BBA. The effective combination, on a molecular scale, between fullerene and titanium dioxide has provided a profound understanding of the photocatalysis mechanism. This work elaborates and makes clear the relationship between the structure and the performance of functional photocatalysts. [ABSTRACT FROM AUTHOR]

Stiffened U-rib plates are the elementary components of steel box girders in bridges that directly bear the input external energy before transferring it to other components. Research on the dynamic characteristics of stiffened U-rib plates is the basis for examining vibration and noise in steel box girders. Most relevant studies have focused on the vibrational modes and single-frequency responses in this context, and few researchers have sought to optimize the design of stiffened U-rib plates to reduce responses due to vibrations and noise. This study identifies the global and local laws of vibrational transmission in stiffened U-rib plates subjected to harmonic loads through structural intensity (SI) analysis that is carried out by jointly using standard finite element software and a post-processing code created by the authors. The contributions of each component of vibrational waves are represented to reflect the dominant roles of the bending wave in the baseplate and the in-plane wave in the U-ribs, respectively. The effects of parameters of the U-rib plates on SI are also quantitatively investigated. SI analysis can be used as a new criterion for designing and optimizing bridges as well as formulating measures for vibration reduction. [ABSTRACT FROM AUTHOR]

Due to advantages such as small weight, large load capacity, and easy manufacturing, orthotropic steel decks (OSDs) are widely used in many steel bridges. As an important component of steel bridge decks that bear vehicle loads, OSDs may produce excessive vibrations and corresponding noise due to low dead loads. Therefore, it is important to study the vibration behavior of OSDs to guide the design to reduce vibration and noise in steel bridges. In this paper, the vibration response of an OSD with simply supported boundary conditions is calculated using the modal expansion method. The input mobility and insertion loss are selected as indices to evaluate the vibration response and suppression performance of the bridge. The results of calculations were compared with those of the finite element method to verify their accuracy. They showed that the input mobility of the OSD was affected primarily by the bending stiffness of the corresponding top plate and longitudinal ribs. The vibration energy of the OSD had both frequency-dependent and excitation location-dependent characteristics. When a source acted on the longitudinal rib or was close to it (within a distance of ¼ of the wavelength), the high-frequency vibration response of the OSD could still be greatly suppressed, with an average vibration reduction of approximately 15 dB. Reducing the spacing between the longitudinal ribs is one of the best ways to reduce the vibration response of the OSD. The frequency of the positive insertion loss ranged from 160 to 500 Hz when the longitudinal rib spacing was reduced from 0.8 to 0.4 m. The frequency-related vibration response of the OSD can be further reduced by adding transverse ribs, especially in the high-frequency range. [ABSTRACT FROM AUTHOR]

Curcuminoids have been extensively investigated as metal ion probes, but the intrinsic aggregation-caused-quenching (ACQ) characteristic of curcumin would hinder their applications in aqueous solution. Fortunately, tetraphenylethylene (TPE) could endow the compounds with aggregation-induced emission (AIE)/aggregation-induced enhanced emission (AIEE) characteristics to eliminate the ACQ effect. According to this strategy, a series of TPE-modified curcumin derivatives L1-4 were prepared and studied for their AIEE properties. Among the four TPE-curcumin analogues, only L1 particles have been successfully used as an on-off fluorescence probe for detecting Cu 2+ in aqueous solution. The fluorescence titration experiment determined its detection limit of 1.49 × 10 -7 mol L -1 , and the binding ratio between L1 and Cu 2+ was estimated as 2 : 1, which was in agreement with the results of high resolution mass spectrum and Job's plot. In addition, the binding constant was evaluated as 6.77 × 10 2 M -1 using a Benesi-Hildebrand plot. Finally, the obtained L1-based indicator paper showed significant fluorescence response to Cu 2+ aqueous solution. This TPE-modified strategy improves the detection capability of curcumin probe in aqueous solution and provides a feasible way to obtain other probes with ACQ characteristics., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)