Abstract
Road damage detection is an important task to ensure road safety and realize the timely repair of road damage. The previous manual detection methods are low in efficiency and high in cost. ...To solve this problem, an improved YOLOv5 road damage detection algorithm, MN-YOLOv5, was proposed. We optimized the YOLOv5s model and chose a new backbone feature extraction network MobileNetV3 to replace the basic network of YOLOv5, which greatly reduced the number of parameters and GFLOPs of the model, and reduced the size of the model. At the same time, the coordinate attention lightweight attention module is introduced to help the network locate the target more accurately and improve the target detection accuracy. The KMeans clustering algorithm is used to filter the prior frame to make it more suitable for the dataset and to improve the detection accuracy. To improve the generalization ability of the model, a label smoothing algorithm is introduced. In addition, the structure reparameterization method is used to accelerate model reasoning. The experimental results show that the improved YOLOv5 model proposed in this paper can effectively identify pavement cracks. Compared with the original model, the mAP increased by 2.5%, the F1 score increased by 2.6%, and the model volume was smaller than that of YOLOv5. 1.62 times, the parameter was reduced by 1.66 times, and the GFLOPs were reduced by 1.69 times. This method can provide a reference for the automatic detection method of pavement cracks.
► Linear Darcy’s law holds for water flow in mated fracture. ► Forchheimer and Izbash laws offer good description for non-mated flow fracture. ► The confining stress does not change the linear and ...nonlinear trend flow patterns. ► Forchheimer nonlinear factor b with changing in situ stress was first quantified. ► The critical Reynolds number to demark linear and nonlinear flow was estimated.
The presence of fracture roughness, isolated contact areas and the occurrence of nonlinear flow complicate the fracture flow process. To experimentally investigate the fluid flow regimes through deformable rock fractures, water flow tests through both mated and non-mated sandstone fractures were conducted in triaxial cell under changing confining stress from 1.0MPa to 3.5MPa. For the first time Forchheimer’s nonlinear factor b describing flow in non-mated fractures under variable confining stress has been quantified. The results show that linear Darcy’s law holds for water flow through mated fracture samples due to high flow resistance caused by the small aperture and high tortuosity of the flow pathway, while nonlinear flow occurs for non-mated fracture due to enlarged aperture. Regression analyses of experimental data show that both Forchheimer equation and Izbash’s law provide an excellent description for this nonlinear fracture flow process. Further, the nonlinear flow data indicate that for smaller true transmissivity, the appreciable nonlinear effect occurs at lower volumetric flow rates. The experimental data of both mated and non-mated fracture flow show that the confining stress does not change the linear and nonlinear flow patterns, however, it has a significant effect on flow characteristics. For mated fracture flow, the slope of pressure gradient versus flow rate becomes steeper and the transmissivity decreases hyperbolically with increase of confining stress, while for non-mated fracture flow, the rate of increase of the nonlinear coefficient b used in Forchheimer equation steadily diminishes with the increase of confining stress. Based on Forchheimer equation and taking 10% of the nonlinear effect as the critical state to distinguish between linear and nonlinear flow, the critical Reynolds number was successfully estimated by using a nonlinear effect coefficient E. This method appears effective to determine critical Reynolds numbers for specific flow cases.
Photoelectrochemical (PEC) water oxidation based on semiconductor materials plays an important role in the production of clean fuel and value‐added chemicals. Nanostructure–interface engineering has ...proven to be an effective way to construct highly efficient PEC water oxidation photoanodes with good light capture, carrier transport, and water oxidation kinetics. However, from theoretical and application perspectives, the relationship between the nanostructure and interface of photoanode materials and their PEC performance remains unclear. In this review, the PEC water oxidation reaction mechanism and evaluation criteria are briefly presented. The theoretical basis and research status of the nanostructure–interface engineering on constructing high‐performance PEC water oxidation photoanodes are summarized and discussed. Finally, the current challenges and the future opportunities of nanostructure–interface engineering for the PEC reactions are pointed out.
Photoelectrochemical (PEC) photoanode materials with better optical response and surface/interface carrier transport/injection performance can allow more efficient PEC water oxidation. Various strategies for improving the PEC water oxidation performance from the perspective of nanostructure–interface engineering are summarized and the relationship between nanostructure–interface engineering and the optical‐response, surface/interfacial carrier transport/injection processes of photoanode materials are discussed.
Abstract
Purpose
The purpose of this research is to examine how “mother fans” impact on the existing patterns of parasocial relationships between fans and idols and to gain deeper insights into the ...motivations underlying the purchase of idol dolls. Additionally, by including the experiences and perspectives of male idol fans, the research seeks to broaden the understanding of fan behavior and enhance comprehension of the motivations driving idol-doll consumption.
Design/methodology/approach
Taking idol-doll buyers as research objects, this research conducted textual analysis and in-depth interviews to explore fans’ motivations for purchasing idol dolls.
Findings
Idol doll purchases are driven by emotional attachment, particularly among mother fans who seek to establish a sense of control and maintain a mother–child relationship. Additionally, buying idol dolls can also serve as a disguise for girlfriend fans to cover up their romantic fantasies about their idols. Moreover, idol dolls serve as semiotic identifiers, attracting like-minded fans and gaining community recognition. It should be noted that male idol fans, who are considered deviant from the masculine normative, face scrutiny in female-dominated communities, needing further proof of authenticity.
Practical implications
This research promotes understanding the motivations behind idol-doll purchases and can assist marketers in catering to the emotional needs of fans, particularly mother fans, by designing and marketing dolls that resonate with their desired sense of attachment.
Social implications
By recognizing and emphasizing the positive aspects of fan activities, this study contributes to the ongoing process of de-demonization and normalization of fandom. Additionally, this research also seeks to contribute to a more comprehensive understanding of the struggles and emotional needs of the Chinese young generation.
Originality/value
This study explores the under-researched mother-fan group’s emotional needs and their motivations of purchasing idol-dolls. It also acknowledges the distinct perspectives and experiences of male idol fans, providing a fresh and unique viewpoint on idol-doll consumption.
The oscillation process based on acoustic vibration system and electrical circuit can be described by the same type of differential equation. MATLAB/SIMULINK was used to establish the electrical ...model of the outlet piping system of the 2D-90Mg-2.5/1.5 type air combined compressor in the laborator. The natural frequency of the gas column is obtained and compared with the results of finite element analysis. It is proved that the electrical simulation method is feasible and simple to calculate the natural frequency of gas column in compressor pipeline system.
The exploitation of mineral resources is gradually shifting from shallow to deep targets. However, the corresponding basic theoretical research has not determined the differences in rock-mining ...engineering at different depths. In this paper, longitudinal wave velocity measurements, uniaxial compression tests, and dynamic impact tests were conducted on granite from various burial depths to reveal the static and dynamic mechanical properties of the rocks. The initial damage variables of the rock specimens decrease after a rapid increase with increasing burial depth. The stress–strain curves of the deep rocks for various strain rates can be divided into two modes. The relationships between the secant modulus, peak stress, elastic modulus, and burial depth basically follow a quadratic function. The rock failure patterns observed in the uniaxial compression tests are basically tensile. In the dynamic loading experiments at various strain rates, the failure pattern of the rock changes with burial depth, when the strain rate is small, from local instability to overall instability and back to local instability; while the strain rate increases, the failure pattern transforms into overall instability. In the dynamic impact experiments with different confining pressures, the rock only undergoes shear failure due to the restriction of the lateral deformation from the confining pressure. These research achievements could provide significant theoretical support for rockburst prevention at greater mining depths.
Metallic lithium (Li) is a promising anode material for next‐generation rechargeable batteries. However, the dendrite growth of Li and repeated formation of solid electrolyte interface during Li ...plating and stripping result in low Coulombic efficiency, internal short circuits, and capacity decay, hampering its practical application. In the development of stable Li metal anode, the current collector is recognized as a critical component to regulate Li plating. In this work, a lithiophilic Cu‐CuO‐Ni hybrid structure is synthesized as a current collector for Li metal anodes. The low overpotential of CuO for Li nucleation and the uniform Li+ ion flux induced by the formation of Cu nanowire arrays enable effective suppression of the growth of Li dendrites. Moreover, the surface Cu layer can act as a protective layer to enhance structural durability of the hybrid structure in long‐term running. As a result, the Cu‐CuO‐Ni hybrid structure achieves a Coulombic efficiency above 95% for more than 250 cycles at a current density of 1 mA cm−2 and 580 h (290 cycles) stable repeated Li plating and stripping in a symmetric cell.
A lithiophilic Cu‐CuO‐Ni hybrid structure is synthesized on a Ni foam substrate as a current collector for lithium (Li) metal anodes. The collective effects of low overpotential of the Cu‐CuO‐Ni hybrid structure for Li nucleation, nanowire array configuration, and the Cu buffer layer are demonstrated to be keys for achieving an outstanding overall performance of the current collector.
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•The single crystal diamond (SCD) surface with ultra-low surface roughness and ultra-thin damage layer was obtained by CMP.•A novel CMP slurry was developed for the CMP of SCD ...consisting of SiO2, H2O2, FeSO4·7H2O, NTA and deionized water.•Under mixed effect of two oxidants, the post-polished surface quality of SCD was improved significantly.•The CMP mechanisms for a SCD were elucidated by XPS and IR measurements.
Single crystal diamond (SCD) has extremely high hardness and wear resistance. However, this hampers the development of surfaces with ultra-low surface roughness and ultra-thin damage layer. It is particularly challenging to achieve the chemical mechanical polishing (CMP) of SCD with a surface roughness less than 0.5 nm and a damage layer thickness <1 nm. In this study, the influence of the CMP slurries with different pH values and oxidants on the quality of polished SCD surface was investigated. The optimal slurry consisted of silica, ferrous sulfate, hydrogen peroxide, nitrilotriacetic acid, and deionized water achieved the lowest surface roughness of SCD. The average surface roughness Ra was 0.754 ± 0.062 nm over eight areas of 868 μm × 868 μm. The Ra value of 0.35 nm was obtained over a scanning area of 70 μm × 50 μm, while the thickness of the damage layer was 0.7 nm. The CMP mechanism was elucidated by X-ray photoelectron spectroscopy and infrared spectroscopy. Hydroxyl radicals and hydrogen ions were adsorbed on the surface, oxidation of the surface and generated C-H, C-O, and C = O groups, and they are eventually removed by silica abrasive, yielding an ultra-smooth SCD surface.
Abstract
Interest in two-dimensional (2D) van der Waals materials has grown rapidly across multiple scientific and engineering disciplines in recent years. However, ferroelectricity, the presence of ...a spontaneous electric polarization, which is important in many practical applications, has rarely been reported in such materials so far. Here we employ first-principles calculations to discover a branch of the 2D materials family, based on In
2
Se
3
and other III
2
-VI
3
van der Waals materials, that exhibits room-temperature ferroelectricity with reversible spontaneous electric polarization in both out-of-plane and in-plane orientations. The device potential of these 2D ferroelectric materials is further demonstrated using the examples of van der Waals heterostructures of In
2
Se
3
/graphene, exhibiting a tunable Schottky barrier, and In
2
Se
3
/WSe
2
, showing a significant band gap reduction in the combined system. These findings promise to substantially broaden the tunability of van der Waals heterostructures for a wide range of applications.
Traffic signs are updated quickly, and there image acquisition and labeling work requires a lot of manpower and material resources, so it is difficult to provide a large number of training samples ...for high-precision recognition. Aiming at this problem, a traffic sign recognition method based on FSOD (few-shot object learning) is proposed. This method adjusts the backbone network of the original model and introduces dropout, which improves the detection accuracy and reduces the risk of overfitting. Secondly, an RPN (region proposal network) with improved attention mechanism is proposed to generate more accurate target candidate boxes by selectively enhancing some features. Finally, the FPN (feature pyramid network) is introduced for multi-scale feature extraction, and the feature map with higher semantic information but lower resolution is merged with the feature map with higher resolution but weaker semantic information, which further improves the detection accuracy. Compared with the baseline model, the improved algorithm improves the 5-way 3-shot and 5-way 5-shot tasks by 4.27% and 1.64%, respectively. We apply the model structure to the PASCAL VOC dataset. The results show that this method is superior to some current few-shot object detection algorithms.
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